Sample records for ba eu yb

  1. Design, synthesis and luminescence properties of Ba2 YB2 O6 Cl- and Ba2 YB2 O6 F-based phosphors.

    PubMed

    Chen, Wanping; Yang, Xin; Liu, Yan; Dai, Xiaoyan

    2015-05-01

    Using a high-temperature solid-state reaction, the chlorine in Ba2 YB2 O6 Cl is gradually replaced by F, and a new compound with the nominal chemical formula Ba2 YB2 O6 F and two phosphors doped with Ce(3+) and Eu(3+) , respectively, are obtained. X-Ray diffraction and photoluminescence spectroscopy are used to characterize the as-synthesized samples. The as-synthesized Ba2 YB2 O6 Cl exhibits bright blue emission in the spectral range ~ 330-410 nm with a maximum around 363 nm under X-ray or UV excitation. Ba2 YB2 O6 F:0.01Ce(3+) exhibits blue emission in the range ~ 340-570 nm with a maximum around 383 nm. Ba2 YB2 O6 F:0.01Eu(3+) exhibits a predominantly (5) D0 -(7)  F2 emission (~610 nm) and the relative intensities of the (5) D0 -(7)  F0,1,2 emissions are tunable under different wavelength UV excitation. The luminescence behaviors of the two phosphors are explained simply in terms of the host composition and site occupancy probability of Ce(3+) and Eu(3+) , respectively. The results indicate that these phosphors have potential application as a blue phosphor or as a red phosphor. Copyright © 2014 John Wiley & Sons, Ltd.

  2. Interplay between magnetism and relativistic fermions in Eu doped (Sr/Ba)MnSb2

    NASA Astrophysics Data System (ADS)

    Liu, Jinyu; Hu, Jin; Zhu, Yanglin; Chuang, Alyssa; Graf, David; Jaime, Marcelo; Balakirev, Fedor; Weickert, Franziska; Zhang, Qiang; Ditusa, John; Wu, Yan; Cao, Huibo; Mao, Zhiqiang

    Layered compounds AMnBi2 (A =Ca, Sr, Ba, Eu, and Yb) have been established as Dirac materials with fascinating properties. In our previous work, we have demonstrated that Sr1-y Mn1-z Sb2 (y, z <0.1), isostructural to AMnBi2, not only host relativistic fermions, but also exhibit ferromagnetic properties, with its ferromagnetism being coupled to the relativistic fermions' transport. To gain further insight into the relativistic fermion-magnetism coupling, we have synthesized a series of Eu doped (Sr/Ba)MnSb2 single crystals and found Eu moments order antiferromagnetically. Through neutron scattering experiments, we determined the magnetic structures for Sr1-xEuxMnSb2 with x = 0.2, 0.5, and 0.8. From magnetotransport measurements, we find the Eu antiferromagnetism is also coupled to relativistic fermion transport. More importantly, we observed a novel quantum phase with saturated magnetoresistivity near the quantum limit for the 10% Eu doped BaMnSb2 sample. We will discuss possible mechanisms for this novel phase.

  3. Near-infrared luminescence from Y2O3:Eu3+, Yb3+ prepared by sol-gel method.

    PubMed

    Xie, Ying; Xiao, Lin J; Yan, Feng Q; Chen, Yong J; Li, Wen Z; Geng, Xiu J

    2014-06-01

    Eu3+ and Yb3+ codoped Y2O3 phosphors were synthesized by the sol-gel method. The phosphors possess absorption in the region of 300-550 nm, exhibiting an intense NIR emission of Yb3+ around 1000 nm, which is suitable for matching the maximum spectral response of c-Si solar cells. The optimum composition of Eu3+ and Yb3+ codoped Y2O3 was (Y1.94Yb0.04Eu0.02)2O3. It is observed that two-step energy transfer occurs from the 5D2 level of Eu3+ situated around (466 nm) exciting two neighboring Yb3+ ions to the 2F5/2 level (1000 nm). The down-conversion material based on Eu(3+)- Yb3+ couple may have great potential applications in c-Si solar cells to enhance their photovoltaic conversion efficiency via spectral modification.

  4. Further considerations of the Ce/Yb vs. Ba/Ce plot in volcanology and tectonics

    USGS Publications Warehouse

    Doe, B.R.

    2002-01-01

    A plot of Ce/Yh vs. Bd/Ce, for locality averages, effectively separates mid-ocean ridge basalts (MORB) (Ce/Yb 10, Ba/Ce 4.2). The conventional interpretation is that these three types of volcanic environments involve oceanic rift-related, large-volume partial melts (???20-30%) of a depleted source. (MORB), small volume melts (???5% for alkalic volcanics) of enriched sources related to plumes (OIV), and melts of hydrous-enriched sources during subduction, especially for Ba (IAV). There OIV sites, however, have average ratios that fall in the MORB field (e.g., Krafla Volcano, Iceland), and these localities also tend to have other geochemical data similar to MORB. Average ratios of Hawaiian tholeiitic shield basalts of Mauna Kea and Koolau volcanoes occupy a restricted field on a plot of Ce/Yb vs. Ba/Ce of 1O-18 for Ce/Yb and 2.8-3.1 for Ba/Ce, a field toward which other shield basalts and cone-building volcanics regress. In general, post-shield alkalic rocks have higher values of Ce/Yb than do tholeiites. Peralkalic basalts (basanites, melilitites, and phonolites) have even higher values of Ce/Yb, reflecting smaller degrees of partial melting (perhaps 1-2%) and melting of sources containing phlogopite that were enriched by CO2-dominated fluids. The minor post-erosion nephelinitic suites of Hawaii (e.g., the Honolulu Series on Oahu, and the Koloa suite on Kauai) generally have values both greater than IAV for Ce/Yb and greater than other kinds of OIV for Ba/Ce in a part of the plot previously not found to be occupied by data. Alkali basalts of both these nephelinitic series have the lowest and similar ratios (Ce/Yb ??? 25; Ba/Ce ??? 10). In the Hawaiian Islands. there are two trends. One (a), where phlogopite has heen interpreted tp remain in the source. generally has Ba/Ce decrease away from the alkali basalts as Ce/Yb increases. The other (b), where phlogopite has heen interpreted to enter the melt, occupies a field that is high in both Ce/Yb (>30) relative to IAV

  5. Measurement of Eu and Yb in aqueous solutions by underwater laser induced breakdown spectroscopy

    DOE PAGES

    Bhatt, Chet R.; Jain, Jinesh C.; Goueguel, Christian L.; ...

    2017-09-13

    In this paper, we report the use of laser induced breakdown spectroscopy (LIBS) to detect dissolved Eu and Yb in bulk aqueous solutions. Ten strong emission lines of Eu and one strong emission line of Yb were identified in the underwater LIBS spectra obtained by using Czerny–Turner spectrometer within the wavelength range of 375–515 nm. Temporal evolution of plasma and the effect of laser pulse energy on the spectral emission were studied. Finally, calibration curves using the concentration range from 500 to 10,000 ppm were developed and limits of detection for Eu and Yb were estimated to be 209 andmore » 156 ppm, respectively.« less

  6. Measurement of Eu and Yb in aqueous solutions by underwater laser induced breakdown spectroscopy

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Bhatt, Chet R.; Jain, Jinesh C.; Goueguel, Christian L.

    In this paper, we report the use of laser induced breakdown spectroscopy (LIBS) to detect dissolved Eu and Yb in bulk aqueous solutions. Ten strong emission lines of Eu and one strong emission line of Yb were identified in the underwater LIBS spectra obtained by using Czerny–Turner spectrometer within the wavelength range of 375–515 nm. Temporal evolution of plasma and the effect of laser pulse energy on the spectral emission were studied. Finally, calibration curves using the concentration range from 500 to 10,000 ppm were developed and limits of detection for Eu and Yb were estimated to be 209 andmore » 156 ppm, respectively.« less

  7. Spectral and multi-wavelength continuous-wave laser properties of Yb3+:BaLaGa3O7

    NASA Astrophysics Data System (ADS)

    Gao, Shufang; Xu, Shan

    2018-05-01

    Yb3+ doped BaLaGa3O7 crystal has been successfully grown by Czochralski method. The polarized absorption spectra, the fluorescence spectra and the fluorescence decay lifetime of Yb3+:BaLaGa3O7 crystal were measured at room temperature. The spectroscopic parameters of Yb3+:BaLaGa3O7 crystal are calculated. A continuous wave output power of 1.32W was obtained with four-wavelength emission corresponding to an optical-optical slope efficiency of 55%.

  8. Electronic Structure of I-M8Ga16Sn30 (M = Ba, Sr, Yb) by First-Principles Calculation

    NASA Astrophysics Data System (ADS)

    Wang, Jin-song; Liu, Hong-xia; Deng, Shuping; Li, De-cong; Shen, Lan-xian; Cheng, Feng; Deng, Shu-kang

    2017-05-01

    Sn-based clathrates possess excellent thermoelectric properties ascribed to their higher Seebeck coefficient and lower thermal conductivity. Guest atoms significantly modulate the thermoelectric properties of Sn-based calculates because of their diverse atomic radius and interactions with framework atoms. Thus, we explored the electronic structure of I-M8Ga16Sn30 (M = Ba, Sr, Yb) by first-principles calculation. Results revealed significant differences between Yb8Ga16Sn30 and M8Ga16Sn30 (M = Ba, Sr,). In particular, the Yb-filled compound substitution possesses lowest formation energy and the off-center distance of the Yb atom is the largest compared with the other structures. I-M8Ga16Sn30 (M = Ba, Sr, Yb) is an indirect band gap semiconductor, and the enhanced hybridization effect between the guest and framework atoms' orbits exists because the Yb f orbit results in a decrease in band gap. Ba- and Sr-filled clathrates have similar valence bands but slightly different conduction bands; however, Yb8Ga16Sn30 possess the spiculate density of states near the Fermi level that reveals excellent thermoelectric properties.

  9. Optical thermometry based on green upconversion emission in Er3+/Yb3+ codoped BaGdF5 glass ceramics

    NASA Astrophysics Data System (ADS)

    Wu, Ting; Zhao, Shilong; Lei, Ruoshan; Huang, Lihui; Xu, Shiqing

    2018-02-01

    Er3+/Yb3+ codoped BaGdF5 glass ceramics have been prepared and used to develop a portable all-fiber temperature sensor based on fluorescence intensity ratio technique. XRD and TEM results affirm the generation of BaGdF5 nanocrystals in the borosilicate glass. Eu3+ ions are used as spectral probe to investigate external environment around rare earth (RE) ions. Intense green upconversion emissions from Er3+ ions are detected in the BaGdF5 glass ceramics and their intensity are enhanced about three orders of magnitude after heat treatment, which is attributed to the enrichment of RE ions in the BaGdF5 phase. Based on green upconversion emission from Er3+ ions, the temperature sensing property of the portable all-fiber temperature sensor is studied. The maximum absolute sensitivity is 15.5 × 10-4 K-1 at 567 K and the relative sensitivity is 1.28% K-1 at 298 K, respectively.

  10. A new oxytelluride: Perovskite and CsCl intergrowth in Ba 3Yb 2O 5Te

    DOE PAGES

    Whalen, J. B.; Besara, T.; Vasquez, R.; ...

    2013-04-27

    The new oxytelluride Ba 3Yb 2O 5Te was obtained from an alkaline earth flux. Ba3Yb2O5Te crystallizes in the tetragonal space group P4/ mmm (#123), with a=4.3615(3) Å and c=11.7596(11) angstrom, Z=1. The structure combines two distinct building blocks, a Ba 2Yb 2O 5 perovskite-like double layer with square bipyramidal coordination of the ytterbium ions, and a CsCl-type BaTe layer. Short range magnetic order is apparent at below 5 K, with the magnetic behavior above this temperature dominated by crystal field effects. The structure may be considered as an analog to the Ruddlesden-Popper phases, where the NaCl-type layer has been replacedmore » by the CsCl-type layer. Finally, the two-dimensional magnetic behavior is expected based on the highly anisotropic nature of the structure.« less

  11. Core-shell-shell heterostructures of α-NaLuF4:Yb/Er@NaLuF4:Yb@MF2 (M = Ca, Sr, Ba) with remarkably enhanced upconversion luminescence.

    PubMed

    Su, Yue; Liu, Xiuling; Lei, Pengpeng; Xu, Xia; Dong, Lile; Guo, Xianmin; Yan, Xingxu; Wang, Peng; Song, Shuyan; Feng, Jing; Zhang, Hongjie

    2016-07-05

    Core-shell-shell heterostructures of α-NaLuF4:Yb/Er@NaLuF4:Yb@MF2 (M = Ca, Sr, Ba) have been successfully fabricated via the thermal decomposition method. Upconversion nanoparticles (UCNPs) were characterized by powder X-ray diffraction (XRD), transmission electron microscopy (TEM), upconversion luminescence (UCL) spectroscopy, etc. Under 980 nm excitation, the emission intensities of the UCNPs are remarkably enhanced after coating the MF2 (M = Ca, Sr, and Ba) shell. Among these samples, CaF2 coated UCNPs show the strongest overall emission, while BaF2 coated UCNPs exhibit the longest lifetime. These results demonstrate that alkaline earth metal fluorides are ideal materials to improve the UCL properties. Meanwhile, although the lattice mismatch between the ternary NaREF4 core and the binary MF2 (M = Sr and Ba) shell is relatively large, the successfully synthesized NaLuF4:Yb/Er@NaLuF4:Yb@MF2 indicates a new outlook on the fabrication of heterostructural core-shell UCNPs.

  12. Controlled synthesis and novel photoluminescence properties of BaTiO{sub 3}:Eu{sup 3+}/Eu{sup 2+} nanocrystals

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Feng, Li; Li, Ying; Wang, Guofeng, E-mail: wanggf75@gmail.com

    2015-01-15

    Highlights: • Tetragonal phase BaTiO{sub 3}:Eu nanocrystals were successfully synthesized using a hydrothermal method. • Under 398 nm excitation, the emissions from Eu{sup 2+} and Eu{sup 3+} ions were observed. • The emission band of Eu{sup 2+} from BaTiO{sub 3}:Eu was observed to broaden with increasing Eu concentration. - Abstract: Tetragonal phase BaTiO{sub 3}:Eu nanocrystals were successfully synthesized using a hydrothermal method and a subsequent calcination treatment. The structures and morphologies of nanocrystals were characterized by X-ray diffraction, Raman spectroscopy, transmission electron microscopy, and scanning electron microscopy. The photoluminescence properties of BaTiO{sub 3}:Eu were investigated in detail. Under 398 nmmore » excitation, the emissions from Eu{sup 2+} and Eu{sup 3+} ions were observed, indicating that Eu{sup 2+} and Eu{sup 3+} ions coexisted in BaTiO{sub 3}:Eu nanocrystals. Especially, the emission band of Eu{sup 2+} from BaTiO{sub 3}:Eu was observed to broaden with increasing Eu concentration. When the Eu concentration was 0.5 mol%, the {sup 5}D{sub 0} → {sup 7}F{sub 0} and {sup 5}D{sub 1} → {sup 7}F{sub 0} emissions were observed. In addition, under 537 nm excitation, the emission intensity increased with increasing Eu concentration.« less

  13. Up-conversion luminescence properties and energy transfer of Tm{sup 3+}/Yb{sup 3+} co-doped BaLa{sub 2}ZnO{sub 5}

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Xie, Jing; Mei, Lefu, E-mail: mlf@cugb.edu.cn; Deng, Junru

    2015-11-15

    Tm{sup 3+}/Yb{sup 3+} co-doped BaLa{sub 2}ZnO{sub 5} up-conversion (UC) phosphors were successfully synthesized by high temperature solid-state reaction method. The X-ray diffraction (XRD) results show that synthesized phosphor co-doped with 0.75% Tm/10% Yb has the optimum pure phase of BaLa{sub 2}ZnO{sub 5} among different co-doping concentrations. The structure of BaLa{sub 2}ZnO{sub 5}:0.75% Tm/10% Yb phosphor was refined by the Rietveld method and results show the decreased unit cell parameters and cell volume after doping Tm{sup 3+}/Yb{sup 3+}, indicating that Tm{sup 3+}/Yb{sup 3+} have successfully replaced La{sup 3+}. Under excitation at 980 nm, Tm{sup 3+}/Yb{sup 3+} co-doped BaLa{sub 2}ZnO{sub 5} phosphorsmore » present bright blue emission near 478 nm generated by the {sup 1}G{sub 4}→{sup 3}H{sub 6} transition and weak red emissions around 653 nm and 692 nm generated by the {sup 1}G{sub 4}→{sup 3}F{sub 4} and {sup 3}F{sub 3}→{sup 3}H{sub 6} transitions of Tm{sup 3+}, respectively. The UC luminescence properties of BaLa{sub 2}ZnO{sub 5} phosphors co-doped with different Tm{sup 3+}/Yb{sup 3+} concentrations were investigated, and the related UC mechanisms of Tm{sup 3+}/Yb{sup 3+} co-doped BaLa{sub 2}ZnO{sub 5} depending on pump power were studied in detail. - Graphical abstract: Up-conversion luminescence of BaLa{sub 2}ZnO{sub 5}:Tm{sup 3+}/Yb{sup 3+} and its crystal structure and up-conversion mechanisms. - Highlights: • Up-conversion phosphors BaLa{sub 2}ZnO{sub 5} co-doped with Tm{sup 3+}/Yb{sup 3+} were synthesized by high temperature solid-state reaction method. • The crystal structure of BaLa{sub 2}ZnO{sub 5} and the changes of cell parameters and volume of BaLa{sub 2}ZnO{sub 5} after doping Tm{sup 3+} and Yb{sup 3+} have been discussed. • Up-conversion luminescence properties and energy transfer between Tm{sup 3+} and Yb{sup 3+} in BaLa{sub 2}ZnO{sub 5} have been discussed in detail.« less

  14. Selective biosorption of lanthanide (La, Eu, Yb) ions by Pseudomonas aeruginosa

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Texier, A.C.; Andres, Y.; Cloirec, P. le

    1999-02-01

    The ability of Pseudomonas aeruginosa to adsorb selectively La{sup 3+}, Eu{sup 3+}, and Yb{sup 3+} from aqueous solution was investigated. The lanthanide biosorption equilibrium obeyed the Brunauer-Emmett-Teller isotherm model, indicating multilayer adsorption. Determined levels of maximum adsorption capacities were 397 {micro}mol/g for lanthanum, 290 {micro}mol/g for europium and 326 {micro}mol/g for ytterbium. The results indicated that there were about 100 preferential sites for lanthanum per g of dry biomass. Experiments with mixed-cation solutions showed that the sequence of preferential biosorption was Eu{sup 3+} = Yb{sup 3+} > La{sup 3+}. Biomass dried at 37 and 70 C showed the same selectivemore » behavior as wet biomass. Inert microbial biomass dried at 37 C appeared to be the most efficient form for experimental use. The uptake of lanthanide by P. aeruginosa cells was not affected by the presence of sodium, potassium, calcium, chloride, sulfate and nitrate ions. Aluminum was a strong inhibitor of lanthanide ions biosorption. 87% of the total Al{sup 3+} was removed from the 3 mM solution, whereas only 8%, 20% and 3% of the total La{sup 3+}, Eu{sup 3+}, and Yb{sup 3+}, respectively, were sorbed from 3 mM solutions. The results suggested that cells of Pseudomonas aeruginosa may find promising applications for removal and separation of lanthanide ions from aqueous effluents.« less

  15. Luminescence and Site Occupancy of Eu2+ in Ba2 Ca(BO3)2

    NASA Astrophysics Data System (ADS)

    Li, Pan-Lai; Wang, Zhi-Jun; Yang, Zhi-Ping; Guo, Qing-Lin

    2011-01-01

    A green phosphor Ba2Ca(BO3)2:Eu2+ was synthesized by a high temperature solid-state reaction method under a reductive atmosphere. The luminescence and site occupancy of Eu2+ in Ba2Ca(BO3)2 are investigated. Ba2Ca(BO3)2:Eu2+ shows one green band (537 nm) under 400 nm near ultraviolet excitation which is suitable for UV LED. Ca2+ and Ba2+ ions in Ba2Ca(BO3)2 are replaced by Eu2+ ions, the Ba2Ca(BO3)2:Eu2+ shows a dissymmetrical emission band. The influence of Eu2+ doping concentrations on the emission intensity of Ba2Ca(BO3)2:Eu2+ is studied. It is found that the emission intensity is influenced by the Eu2+ concentration and reaches the maximum value at 2% Eu2+. According to the Dexter theory, the concentration quenching mechanisms of Eu2+ in Ba2Ca(BO3)2 are the d-dinteraction.

  16. Enhanced NIR downconversion luminescence by precipitating nano Ca5(PO4)3F crystals in Eu2+-Yb3+ co-doped glass

    NASA Astrophysics Data System (ADS)

    Li, Chen; Song, Zhiguo; Li, Yongjin; Lou, Kai; Qiu, Jianbei; Yang, Zhengwen; Yin, Zhaoyi; Wang, Xue; Wang, Qi; Wan, Ronghua

    2013-10-01

    Eu2+-Yb3+ co-doped transparent glass-ceramic containing nano-Ca5(PO4)3F (FAP) was prepared in reducing atmosphere. XRD and TEM analysis indicated that nano-FAP about 40 nm precipitated homogeneously in glass matrix after heat treatment. Confirmed by spectroscopy measurements, the crystal-like absorption and emission of Eu2+ indicated the partition of Eu2+ into FAP nanocrystals in glass ceramic. NIR emission due to the transition 2F→2F of Yb3+ ions (about 980-1100 nm) was observed from glasses under ultraviolet excitation, ascribed to downconversion from Eu2+ to Yb3+, which can be enhanced by precipitating nano-FAP crystals. The results indicated that Eu2+-Yb3+ co-doped glass-ceramic embedding with nano-FAP is a promising candidate as downconversion materials for enhancing conversion efficiency of solar cells.

  17. Broadband near-infrared downconversion luminescence in Eu2+-Yb3+ codoped Ca9Y(PO4)7

    NASA Astrophysics Data System (ADS)

    Sun, Jiayue; Zhou, Wei; Sun, Yining; Zeng, Junhui

    2013-06-01

    An efficient broadband near-infrared (NIR) quantum cutting was demonstrated in Eu2+-Yb3+ codoped Ca9Y(PO4)7 phosphor. Upon excitation of Eu2+ ions to the 4f65d1 level with an ultraviolet photon at 322 nm, emissions of two NIR photons at 983 nm of Yb3+were achieved. The dependences of the visible and NIR emissions, the decay lifetime, the energy transfer efficiency (ETE), and the quantum efficiency (QE) on the Yb3+ doping content were investigated in detail. The results indicated that the maximum ETE and the corresponding downconversion QE can reach between 80% and 179%, respectively.

  18. Broadband near-infrared downconversion luminescence in Yb3+-doped BaZn2(BO3)2

    NASA Astrophysics Data System (ADS)

    Yu, Hua; Deng, Degang; Su, Weitao; Li, Chenxia; Xu, Shiqing

    2018-06-01

    BaZn2(BO3)2 self-activated phosphors were prepared by the conventional high temperature solid-state method. The PL spectra of BaZn2(BO3)2 powders prepared under reductive and air atmosphere consist of a weak ultraviolet emission band (∼410 nm) and a broad emission band which were centered at ∼ 500 and 545 nm, respectively. According to the spectral analysis and EPR results, the green and yellow emissions may arise from the transitions of photo-generated electron close to the conduction band to the deeply trapped hole in single ionized oxygen vacancy (V+ o) centers and single negatively charged interstitial oxygen ion (O- i), respectively. An efficient broadband near-infrared (NIR) quantum cutting was demonstrated in Yb3+ doped BaZn2(BO3)2 phosphor. Upon excitation with an ultraviolet photon at 375 nm, the emissions of two NIR photons at 983 nm from Yb3+ ions were achieved. The dependences of the visible and NIR emissions, the decay lifetime, the energy transfer efficiency, and the quantum efficiency on the Yb3+ doping content were investigated in detail. The results indicated that the maximum energy transfer and the corresponding downconversion quantum efficiency could reach between 68.5% and 168.5%.

  19. Optically stimulated luminescence in an imaging plate using BaFi:Eu.

    PubMed

    Nanto, H; Araki, T; Daimon, M; Kusano, E; Kinbara, A; Kawabata, K; Nakano, Y

    2002-01-01

    BaFI:Eu phosphors are fabricated using a new method of synthesis: liquid phase synthesis, in which the phosphor particles are formed through the association of Ba2+ ions, F-ions and Eu2+ ions in solution. An intense optically stimulated luminescence (OSL) peak at about 410 nm is observed by stimulating X ray irradiated BaFI:Eu phosphor with about 550-750 nm light. It is found that the peak wavelength of the optically stimulation spectrum is about 690 nm. This result suggests that the semiconductor laser can be used as the stimulating light source. It is also found that the OSL intensity is increased with increasing the X ray dose. The BaFI:Eu phosphor as a photostimulable material for the imaging plate of a computed radiography system provides the following advantages; (1) high X ray absorption coefficient, (2) high monodispersion in size which would contribute to sharp images, (3) high OSL and thus low luminescence mottle and (4) high DQE (detective quantum efficiency).

  20. Effect of Eu substitution on superconductivity in Ba{sub 8−x}Eu{sub x}Al{sub 6}Si{sub 40} clathrates

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Liu, Lihua; Bi, Shanli; Peng, Bailu

    2015-05-07

    The silicon clathrate superconductor is uncommon as its structure is dominated by strong Si-Si covalent bonds, rather than the metallic bond, that are more typical of traditional superconductors. To understand the influence of large magnetic moment of Eu on superconductivity for type-I clathrates, a series of samples with the chemical formula Ba{sub 8−x}Eu{sub x}Al{sub 6}Si{sub 40} (x = 0, 0.5, 1, and 2) were synthesised in which Eu occupied Ba sites in cage center. With the increase of Eu content, the cubic lattice parameter decreases monotonically signifying continuous shrinkage of the constituting (Ba/Eu)@Si{sub 20} and (Ba/Eu)@Si{sub 24} cages. The temperature dependence ofmore » magnetization at low temperature revealed that Ba{sub 8}Al{sub 6}Si{sub 40} is superconductive with transition temperature at T{sub C} = 5.6 K. The substitution of Eu for Ba results in a strong superconductivity suppression; Eu-doping largely decreases the superconducting volume and transition temperature T{sub C}. Eu atoms enter the clathrate lattice and their magnetic moments break paired electrons. The Curie-Weiss temperatures were observed at 3.9, 6.6, and 10.9 K, respectively, for samples with x = 0.5, 1.0, and 2.0. Such ferromagnetic interaction of Eu can destroy superconductivity.« less

  1. Understanding the infrared to visible upconversion luminescence properties of Er{sup 3+}/Yb{sup 3+} co-doped BaMoO{sub 4} nanocrystals

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Adhikari, Rajesh; Choi, Jinhyuk; Narro-García, R.

    2014-08-15

    In this paper we report the infrared to visible upconversion luminescence properties of Er{sup 3+}/Yb{sup 3+} co-doped BaMoO{sub 4} nanocrystals synthesized via microwave assisted sol–gel processing route. Structural, morphological and upconversion luminescence properties were investigated by X-ray diffraction (XRD), Transmission Electron Microscopy (TEM), UV–vis diffuse reflectance spectroscopy (UV–vis DRS) and Upconversion Photoluminescence spectra analysis. Results revealed that the oval shaped BaMoO{sub 4} nanocrystals ranging in size from 40 to 60 nm having tetragonal scheelite crystal structure were obtained by sol–gel route. The infrared to visible upconversion luminescence has been investigated in Er{sup 3+}/Yb{sup 3+} co-doped in BaMoO{sub 4}with different Yb{supmore » 3+} concentrations. Intense green upconversion emissions around 528, 550 nm, and red emission at 657 nm corresponding to the {sup 2}H{sub 11/2}, {sup 4}S{sub 3/2}, and {sup 4}F{sub 9/2} transitions, respectively to the {sup 4}I{sub 15/2} ground state were observed when excited by CW laser radiation at 980 nm. The green emissions were greatly enhanced after the addition of sensitizer (Yb{sup 3+} ions). The effect of Yb{sup 3+} on the upconversion luminescence intensity was analyzed and explained in terms of the energy transfer process based. The reported work establishes the understanding of molybdates as an alternative host material for upconversion luminescence. - Graphical abstract: Infrared to visible upconversion luminescence of Er{sup 3+}/Yb{sup 3+} co-doped BaMoO{sub 4} nanocrystals. - Highlights: • Nanocrystals were synthesized by microwave assisted sol–gel processing route. • Strong green emissions were observed in Er{sup 3+}/Yb{sup 3+} co-doped BaMoO{sub 4} nanocrystals. • Provides an insight on Upconversion luminescence properties of oxides host materials.« less

  2. Frequency upconversion and fluorescence intensity ratio method in Yb3+-ion-sensitized Gd2O3:Er3+-Eu3+ phosphors for display and temperature sensing

    NASA Astrophysics Data System (ADS)

    Ranjan, Sushil Kumar; Soni, Abhishek Kumar; Rai, Vineet Kumar

    2017-09-01

    Near infrared (NIR) to visible frequency upconversion emission studies in Er3+-Eu3+/Er3+-Eu3+-Yb3+ co-doped/tri-doped Gd2O3 phosphors prepared by the co-precipitation technique have been explored under 980 nm laser diode radiation. The developed phosphors were characterized with the help of XRD, FE-SEM and FTIR analysis. No upconversion (UC) emission was found in the Eu3+-doped Gd2O3 phosphor. UC emission from Eu3+ ions along with Er3+ ions was observed in Er3+-Eu3+ and Er3+-Eu3+-Yb3+ co-doped/tri-doped phosphors. The UC emission arising from the Er3+ and Eu3+ ions was enhanced several times due to the incorporation of Yb3+ ions. The processes involved in the UC emission were obtained on the basis of the effect of energy transfer/sensitization through the Yb3+ → Er3+ → Eu3+ process. The red/green intensity ratio was improved from 0.16 to 1.50 and 1.01 to 1.50 for Er3+-Eu3+-Yb3+ tri-doped phosphors as compared to the Er3+-doped and Er3+-Yb3+ co-doped phosphors, respectively, at a fixed pump power density. A UC fluorescence intensity ratio (FIR)-based temperature sensing study was performed in the prepared Er3+-Eu3+-Yb3+ tri-doped Gd2O3 phosphors for green upconversion emission bands in the 300 K-443 K temperature range. A maximum sensor sensitivity of about ˜0.0043 K-1 at 300 K was achieved for the synthesized tri-doped phosphors upon excitation with a 980 nm laser diode. The colour coordinates lying in the green-yellow region are invariant, with variation in pump power density and temperature. The observed results support the utility of the prepared tri-doped phosphors in optical temperature sensing, display devices and NIR to visible upconverters.

  3. The effect of X-ray exposure on Ba2SiO4:Eu3+

    NASA Astrophysics Data System (ADS)

    Volhard, Max-Fabian; Jüstel, Thomas

    2018-03-01

    The ortho-silicates Ba2SiO4:Eu3+ and Ba2SiO4:Eu2+ are well-established materials for fluorescent light sources, e.g., phosphor converted LEDs. Samples containing Eu2+or Eu3+were synthesised by the solid-state-method, and the phase purity was determined by X-ray powder diffractometry. The photoluminescence of both phosphors was examined as a function of the pre-treatment. Upon irradiation of Ba2SiO4:Eu3+ with X-rays (tungsten target source), the reduction of Eu3+ towards Eu2+ was observed. This reduction behaviour was thoroughly recorded, and the linearity of the process was determined. Furthermore, the relationship between the acceleration voltage and the reduction process is discussed.

  4. Preparation, photoluminescent properties and luminescent dynamics of BaAlF{sub 5}:Eu{sup 2+} nanophosphors

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Zhang, Wei; College of Life Science, Dalian Nationalities University, Dalian, Liaoning 116600; Hua, Ruinian, E-mail: rnhua@dlnu.edu.cn

    2014-12-15

    Graphical abstract: Rice-shaped BaAlF{sub 5}:Eu{sup 2+} nanophosphors were synthesized via one-pot hydrothermal process. The as-prepared BaAlF{sub 5}:Eu{sup 2+} are composed of many particles with an average diameter of 40 nm. When excited at 260 nm, the sharp line emission located at 361 nm of Eu{sup 2+} was observed. The optimum doping concentration of Eu{sup 2+} was confirmed to be 5 mol%. The strong ultraviolet emission of Eu{sup 2+} ions in BaAlF{sub 5}:Eu{sup 2+} nanoparticles suggests that these nanoparticles may have potential applications for sensing, solid-state lasers and spectrometer calibration. - Highlights: • BaAlF{sub 5}:Eu{sup 2+} nanophosphors were synthesized via amore » mild hydrothermal process. • The Van and Huang models were used to research the mechanism of concentration quenching. • The optimum doping concentration of Eu2+ was confirmed to be 5 mol%. - Abstract: Eu{sup 2+}-doped BaAlF{sub 5} nanophosphors were synthesized via a facile one-pot hydrothermal method. The final products were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), and photoluminescence (PL) spectroscopy. XRD results showed that the prepared samples are single-phase. The FE-SEM and TEM images indicated that the prepared BaAlF{sub 5}:Eu{sup 2+} nanophosphors are composed of many rice-shaped particles with an average diameter of 40 nm. When excited at 260 nm, BaAlF{sub 5}:Eu{sup 2+} nanophosphors exhibit the sharp line emissions of Eu{sup 2+} at room temperature. The optimum doping concentration of Eu{sup 2+} was confirmed to be 5 mol%. The Van and Huang models were used to study the mechanism of concentration quenching and the electric dipole–dipole interaction between Eu{sup 2+} can be deduced to be a dominant for quenching fluorescence in BaAlF{sub 5}:Eu{sup 2+} nanophosphors. The strong ultraviolet emission of Eu{sup 2+} in BaAlF{sub 5}:Eu{sup 2+} nanophosphors suggests

  5. Photoluminescence and thermoluminescence properties of Eu2+ doped and Eu2+ ,Dy3+ co-doped Ba2 MgSi2 O7 phosphors.

    PubMed

    Sao, Sanjay Kumar; Brahme, Nameeta; Bisen, D P; Tiwari, Geetanjali

    2016-11-01

    In this work, we report the preparation, characterization, comparison and luminescence mechanisms of Eu 2 + -doped and Eu 2 + ,Dy 3 + -co-doped Ba 2 MgSi 2 O 7 (BMSO) phosphors. Prepared phosphors were synthesized via a high temperature solid-state reaction method. All prepared phosphors appeared white. The phase structure, particle size, and elemental analysis were analyzed using X-ray diffraction (XRD), transmission electron microscopy (TEM) and energy-dispersive X-ray (EDX) analysis. The luminescence properties of the phosphors were investigated by thermoluminescence (TL) and photoluminescence (PL). The PL excitation and emission spectra of Ba 2 MgSi 2 O 7 :Eu 2 + showed the peak to be around 381 nm and 490 nm respectively. The PL excitation spectrum of Ba 2 MgSi 2 O 7 :Eu 2 + Dy 3 + showed the peak to be around 341 nm and 388 nm, and the emission spectrum had a broad band around 488 nm. These emissions originated from the 4f 6 5d 1 to 4f 7 transition of Eu 2 + . TL analysis revealed that the maximum TL intensity was found at 5 mol% of Eu 2 + doping in Ba 2 MgSi 2 O 7 phosphors after 15 min of ultraviolet (UV) light exposure. TL intensity was increased when Dy 3 + ions were co-doped in Ba 2 MgSi 2 O 7 :Eu 2 + and maximum TL intensity was observed for 2 mol% of Dy 3 + . TL emission spectra of Ba 1.95 MgSi 2 O 7 :0.05Eu 2 + and Ba 1.93 MgSi 2 O 7 :0.05Eu 2 + ,0.02Dy 3 + phosphors were found at 500 nm. TL intensity increased with UV exposure time up to 15 min, then decreased for the higher UV radiation dose for both Eu doping and Eu,Dy co-doping. The trap depths were calculated to be 0.54 eV for Ba 1.95 MgSi 2 O 7 :0.05Eu 2 + and 0.54 eV and 0.75 eV for Ba 1.93 MgSi 2 O 7 :0.05Eu 2 + ,0.02Dy 3 + phosphors. It was observed that co-doping with small amounts of Dy 3 + enhanced the thermoluminescence properties of Ba 2 MgSi 2 O 7 phosphor. Copyright © 2016 John Wiley & Sons, Ltd. [Correction added on 5 April 2016, after first online publication: The

  6. Energy transfer between Eu-Mn and photoluminescence properties of Ba0.75Al11O17.25-BaMgAl10O17:Eu2+,Mn2+ solid solution

    NASA Astrophysics Data System (ADS)

    Zhou, Jun; Wang, Yuhua; Liu, Bitao; Li, Feng

    2010-08-01

    In order to evaluate the energy transfer between Eu-Mn in Ba0.75Al11O17.25-BaMgAl10O17 solid solution, Ba0.75Al11O17.25-BaMgAl10O17:Eu2+,Mn2+ phosphors were prepared by flux method. The crystal structure and the morphology of the solid solution were demonstrated by x-ray dirrfactometer and scanning electron microscopy. The photoluminescence mechanisms were explained by the energy transfer of Eu2+ to Mn2+ and the Dexter theory. A redshift of green emission peak and a decrease in decay time with the increase in Mn2+ concentration were observed. These phenomena are attributed to the formation of Mn2+ paired centers after analysis by a method of Pade approximations.

  7. Effect of C6+ Ion Irradiation on structural and electrical properties of Yb and Eu doped Bi1.5 Zn0.92 Nb1.5 O6.92 pyrochlores

    NASA Astrophysics Data System (ADS)

    Yumak, Mehmet; Mergen, Ayhan; Qureshi, Anjum; Singh, N. L.

    2015-03-01

    Pyrochlore general formula of A2B2X7 where A and B are cations and X is an anion Pyrochlore compounds exhibit semiconductor, metallic or ionic conduction properties, depending on the doping, compositions/ substituting variety of cations and oxygen partial pressure. Ion beam irradiation can induce the structural disordering by mixing the cation and anion sublattices, therefore we aim to inevestigate effects of irradiation in pyrochlore compounds. In this study, Eu and Yb-doped Bi1.5Zn0.92Nb1.5O6.92 (Eu-BZN, Yb-BZN) Doping effect and single phase formation of Eu-BZN, Yb-BZN was characterized by X-ray diffraction technique (XRD). Radiation-induced effect of 85 MeV C6+ ions on Eu-BZN, Yb-BZN was studied by XRD, scanning electron microscopy (SEM) and temperature dependent dielectric measurements at different fluences. XRD results revealed that the ion beam-induced structural amorphization processes in Eu-BZN and Yb-BZN structures. Our results suggested that the ion beam irradiation induced the significant change in the temprature depndent dielectric properties of Eu-BZN and Yb-BZN pyrochlores due to the increased oxygen vacancies as a result of cation and anion disordering. Department of Metallurgical and Materials Eng., Marmara University, Istanbul-81040, Turkey.

  8. Irradiation effect on luminescence properties of fluoroperovskite single crystal (LiBaF3:Eu2+)

    NASA Astrophysics Data System (ADS)

    Daniel, D. Joseph; Madhusoodanan, U.; Nithya, R.; Ramasamy, P.

    2014-03-01

    Single crystals of pure and Eu2+ doped LiBaF3 have been grown from melt by using a vertical Bridgman-Stockbarger method. Effects induced by irradiation on europium doped LiBaF3 (lithium barium fluoride) single crystals were monitored by optical absorption, photoluminescence and thermoluminescence studies. The absorption bands of Eu2+ ions with peaks at 240, 290 and 320 nm were observed in the LiBaF3:Eu2+ crystal. Drastic increase in absorption was noted below 600 nm after gamma irradiation, which was dependent on the radiation dose. The additional absorption peak at around 570 nm was observed in irradiated crystal due to the ionization process Eu2+(-)e-→Eu3+. Photoluminescence of Eu2+ doped LiBaF3 single crystal shows sharp line peaked at ~359 nm and a broad band extending between 370 and 450 nm which shows a considerable reduction in Eu2+ PL intensity after gamma irradiation. Irradiated LiBaF3:Eu2+ sample has revealed three intense TL glow peaks at 128 °C (peak-1), 281 °C (peak-2) and 407 °C (peak-3). Activation energy (E) and frequency factor (s) of the latter two peaks were determined by various heating rate (VHR) method and graphical method.

  9. Higher thermoelectric performance of Zintl phases (Eu0.5Yb0.5)1-xCaxMg2Bi2 by band engineering and strain fluctuation.

    PubMed

    Shuai, Jing; Geng, Huiyuan; Lan, Yucheng; Zhu, Zhuan; Wang, Chao; Liu, Zihang; Bao, Jiming; Chu, Ching-Wu; Sui, Jiehe; Ren, Zhifeng

    2016-07-19

    Complex Zintl phases, especially antimony (Sb)-based YbZn0.4Cd1.6Sb2 with figure-of-merit (ZT) of ∼1.2 at 700 K, are good candidates as thermoelectric materials because of their intrinsic "electron-crystal, phonon-glass" nature. Here, we report the rarely studied p-type bismuth (Bi)-based Zintl phases (Ca,Yb,Eu)Mg2Bi2 with a record thermoelectric performance. Phase-pure EuMg2Bi2 is successfully prepared with suppressed bipolar effect to reach ZT ∼ 1. Further partial substitution of Eu by Ca and Yb enhanced ZT to ∼1.3 for Eu0.2Yb0.2Ca0.6Mg2Bi2 at 873 K. Density-functional theory (DFT) simulation indicates the alloying has no effect on the valence band, but does affect the conduction band. Such band engineering results in good p-type thermoelectric properties with high carrier mobility. Using transmission electron microscopy, various types of strains are observed and are believed to be due to atomic mass and size fluctuations. Point defects, strain, dislocations, and nanostructures jointly contribute to phonon scattering, confirmed by the semiclassical theoretical calculations based on a modified Debye-Callaway model of lattice thermal conductivity. This work indicates Bi-based (Ca,Yb,Eu)Mg2Bi2 is better than the Sb-based Zintl phases.

  10. Structure, thermal and luminescence properties of Eu/Tb(BA)3phen/PAN fibers fabricated by electrospinning

    NASA Astrophysics Data System (ADS)

    Wang, Shiwei; Xie, Guangbo; Zhang, Jingjing; Zhang, Sen; Li, Tingju

    2018-04-01

    Novel high luminescence fibers often exhibit potential applications in the fields of color displays and sensor systems. In this study, Eu(BA)3phen and Tb(BA)3phen powders was successfully synthesized by solvothermal reactions, firstly. Then, three kinds of novel flexible Eu(BA)3phen/PAN, Tb(BA)3phen/PAN and Eu/Tb(BA)3phen/PAN (BA = benzoic acid, phen = phenanthroline, PAN = Polyacrylonitrile) fibers had been successfully prepared by electrospinning technology. The characterizations of the final products have been investigated in detail. It was found that the diameter of the as-prepared fibers were almost uniform with the fabricated complexes doping into PAN successfully. Thermogravimetric analysis indicates that the thermal stability of the pure PAN fiber could be improved by the incorporation of the complex, although only 1 wt % was added. Furthermore, in Eu/Tb(BA)3phen complex, the fluorescence intensity of Eu3+ ions was remarkably increased by adding Tb3+ ions. This is primarily due to an energy transfer from the 5D4 level of Tb (III) to the 5D0 level of Eu (III) ions, where Tb3+ acted as sensitizer. The corresponding luminescent fibers displayed the same regularity as the complexes. Moreover, with the increasing of the incorporation of complexes into PAN, the fluorescence intensities were significantly enhanced and reached its maximum value at 2.5 wt % for Eu(BA)3phen/PAN fibers and 2.0 wt% for Tb(BA)3phen/PAN fibers. The further intensity decreased with the increasing content of the complexes because of typical emission concentration quenching.

  11. Preferential Eu Site Occupation and Its Consequences in the Ternary Luminescent Halides AB 2 I 5 : Eu 2 + ( A = Li – Cs ; B = Sr , Ba)

    DOE PAGES

    Fang, C.  M.; Biswas, Koushik

    2015-07-22

    Several rare-earth-doped, heavy-metal halides have recently been identified as potential next-generation luminescent materials with high efficiency at low cost. AB 2I 5:Eu 2+ (A=Li–Cs; B=Sr, Ba) is one such family of halides. Its members, such as CsBa 2I 5:Eu 2+ and KSr 2I 5:Eu 2+, are currently being investigated as high-performance scintillators with improved sensitivity, light yield, and energy resolution less than 3% at 662 keV. Within the AB 2I 5 family, our first-principles-based calculations reveal two remarkably different trends in Eu site occupation. The substitutional Eu ions occupy both eightfold-coordinated B1(VIII) and the sevenfold-coordinated B2(VII) sites in the Sr-containingmore » compounds. However, in the Ba-containing crystals, Eu ions strongly prefer the B2(VII)sites. This random versus preferential distribution of Eu affects their electronic properties. The calculations also suggest that in the Ba-containing compounds one can expect the formation of Eu-rich domains. These results provide atomistic insight into recent experimental observations about the concentration and temperature effects in Eu-doped CsBa 2I 5. We discuss the implications of our results with respect to luminescent properties and applications. We also hypothesize Sr, Ba-mixed quaternary iodides ABa VIIISr VIII 5:Eu as scintillators having enhanced homogeneity and electronic properties.« less

  12. Study of Eu{sup 3+} → Eu{sup 2+} reduction in BaAl{sub 2}O{sub 4}:Eu prepared in different gas atmospheres

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Rezende, Marcos V. dos S., E-mail: mvsrezende@gmail.com; Valerio, Mário E.G.; Jackson, Robert A.

    2015-01-15

    Highlights: • The effect of different gas atmospheres on the Eu reduction process was studied. • The Eu reduction was monitored analyzing XANES region at the Eu L{sub III}-edge. • Hydrogen reducing agent are the most appropriate gas for Eu{sup 2+} stabilization. • Only a part of the Eu ions can be stabilized in the divalent state. • A model of Eu reduction process is proposed. - Abstract: The effect of different gas atmospheres such as H{sub 2}(g), synthetic air, carbon monoxide (CO) and nitrogen (N{sub 2}) on the Eu{sup 3+} → Eu{sup 2+} reduction process during the synthesis ofmore » Eu-doped BaAl{sub 2}O{sub 4} was studied using synchrotron radiation. The Eu{sup 3+} → Eu{sup 2+} reduction was monitored analyzing XANES region when the sample are excited at the Eu L{sub III}-edge. The results show that the hydrogen reducing agent are the most appropriate gas for Eu{sup 2+} stabilization in BaAl{sub 2}O{sub 4} and that only a part of the Eu ions can be stabilized in the divalent state. A model of Eu reduction process, based on the incorporation of charge compensation defects, is proposed.« less

  13. Up-conversion multiwave (White) luminescence in the visible spectral range under excitation by IR laser diodes in the active BaY2F8:Yb3+,Pr3+ medium

    NASA Astrophysics Data System (ADS)

    Pushkar', A. A.; Uvarova, T. V.; Kiiko, V. V.

    2011-08-01

    The possibilities of occupying high-lying 4 f states of Pr3+ ions in the active BaY2F8:Yb3+,Pr3+ medium according to the photon avalanche and step-by-step sensitization mechanisms are compared. It is shown that the photon avalanche is unlikely to occur in the BaY2F8:Yb3+,Pr3+ crystal. The multiband luminescence spectra in the visible spectral range (white emission) under single- and multiwave pumping of BaY2F8:Yb3+,Pr3+ crystal by IR laser diodes are reported.

  14. [Effect of Eu(Pr) substitution at Ba sites on microstructure and superconductivity in EuBa2Cu3O7-delta ceramics].

    PubMed

    Peng, Zhen-sheng; Wang, Zhi-he

    2004-04-01

    Ceramics of Eu1+xBa2-xCu3O7-delta with x = 0.0, 0.05, 0.1, 0.2, 0.3, 0.4, 0.5 and EuBa2-xPrxCu3O7-delta with x=0.0, 0.05, 0.1, 0.2, 0.3, 0.4 have been synthesized and investigated by X-ray diffraction, resistivity, and Raman spectroscopy. The results show that the transition of crystal structure from orthorhombic to tetragonal occurs and the criticaltemperature decreases withthe increase in doping concentration x. The Raman spectra show that the frequency of the Cu(1)-O(4) stretching mode andthe Cu(2)-(2, 3) out-of-phase mode shifts to higher wave number with increasing doping concentration x.

  15. Scintillation properties of Eu 2+-doped KBa 2I 5 and K 2BaI 4

    DOE PAGES

    Stand, L.; Zhuravleva, M.; Chakoumakos, Bryan C.; ...

    2015-09-25

    We report two new ternary metal halide scintillators, KBa 2I 5 and K 2BaI 4, activated with divalent europium. Single crystal X-ray diffraction measurements confirmed that KBa 2I 5 has a monoclinic structure (P2 1/c) and that K 2BaI 4 has a rhombohedral structure (R3c). Differential scanning calorimetry showed singular melting and crystallization points, making these compounds viable candidates for melt growth. We grew 13 mm diameter single crystals of KBa 2I 5:Eu 2+ and K 2BaI 4:Eu2+ in evacuated quartz ampoules via the vertical Bridgman technique. The optimal Eu 2+ concentration was 4% for KBa 2I 5 and 7%more » for K 2BaI 4. The X-ray excited emissions at 444 nm for KBa 2I 5:Eu 4% and 448 nm for K 2BaI 4:Eu 7% arise from the 5d-4f radiative transition in Eu 2+. KBa 2I 5:Eu 4% has a light yield of 90,000 photons/MeV, with an energy resolution of 2.4% and K 2BaI 4:Eu 7% has a light yield of 63,000 ph/MeV, with an energy resolution of 2.9% at 662 keV. Both crystals have an excellent proportional response to a wide range of gamma-ray energies.« less

  16. Thermoelectric Performance of Yb-Doped Ba8Ni0.1Zn0.54Ga13.8Ge31.56 Type-I Clathrate Synthesized by High-Pressure Technique

    NASA Astrophysics Data System (ADS)

    Chen, Chen; Zhang, Long; Dong, Jianying; Xu, Bo

    2017-05-01

    Type I clathrates are a promising thermoelectric (TE) material for waste heat recovery applications. However, the TE figure-of-merit of type I clathrates still needs further improvement. In this study, Yb-doped Ba8- x Yb x Ni0.1Zn0.54 Ga13.8Ge31.56 (0 ≤ x ≤ 0.5) type I clathrates were synthesized using a high-pressure technique. Energy dispersive spectrometry confirmed successful Yb doping. An increased Yb doping level reduces electrical resistivity and suppresses lattice thermal conductivity while keeping the Seebeck coefficient almost unchanged. TE figure-of-merit of Ba7.7Yb0.3Ni0.1Zn0.54Ga13.8Ge31.56 type I clathrate was improved by 15% (0.91) at the highest measured temperature (900 K) compared with a Yb-free sample.

  17. Tailoring the structure and thermoelectric properties of BaTiO3via Eu2+ substitution.

    PubMed

    Xiao, Xingxing; Widenmeyer, Marc; Xie, Wenjie; Zou, Tianhua; Yoon, Songhak; Scavini, Marco; Checchia, Stefano; Zhong, Zhicheng; Hansmann, Philipp; Kilper, Stefan; Kovalevsky, Andrei; Weidenkaff, Anke

    2017-05-31

    A series of Ba 1-x Eu x TiO 3-δ (0.1 ≤ x ≤ 0.9) phases with ∼40 nm particle size were synthesized via a Pechini method followed by annealing and sintering under a reducing atmosphere. The effects of Eu 2+ substitution on the BaTiO 3 crystal structure and the thermoelectric transport properties were systematically investigated. According to synchrotron X-ray diffraction data only cubic perovskite structures were observed. On the local scale below about 20 Å (equal to ∼5 unit cells) deviations from the cubic structure model (Pm3[combining macron]m) were detected by evaluation of the pair distribution function (PDF). These deviations cannot be explained by a simple symmetry breaking model like in EuTiO 3-δ . The best fit was achieved in the space group Amm2 allowing for a movement of Ti and Ba/Eu along 〈110〉 of the parent unit cell as observed for BaTiO 3 . Density functional calculations delivered an insight into the electronic structure of Ba 1-x Eu x TiO 3-δ . From the obtained density of states a significant reduction of the band gap by the presence of filled Eu 2+ 4f states at the top of the valence band was observed. The physical property measurements revealed that barium-europium titanates exhibit n-type semiconducting behavior and at high temperature the electrical conductivity strongly depended on the Eu 2+ content. Activation energies calculated from the electrical conductivity and Seebeck coefficient data indicate that at high temperatures (800 K < T < 1123 K) the conduction mechanism of Ba 1-x Eu x TiO 3-δ (0.1 ≤ x ≤ 0.9) is a polaron hopping when 0 < x ≤ 0.6 and is a thermally activated process when 0.6 < x < 1. Besides, the thermal conductivity increases with increasing Eu 2+ concentration. Due to a remarkable improvement of the power factor, Ba 0.1 Eu 0.9 TiO 3-δ showed a ZT value of 0.24 at 1123 K.

  18. Eu-doped BaTiO₃powder and film from sol-gel process with polyvinylpyrrolidone additive.

    PubMed

    García-Hernández, Margarita; García-Murillo, Antonieta; de J Carrillo-Romo, Felipe; Jaramillo-Vigueras, David; Chadeyron, Geneviève; De la Rosa, Elder; Boyer, Damien

    2009-09-17

    Transparent BaTiO(3):Eu(3+) films were prepared via a sol-gel method and dip-coating technique, using barium acetate, titanium butoxide, and polyvinylpyrrolidone (PVP) as modifier viscosity. BaTiO(3):Eu(3+) films ~500 nm thick, crystallized after thermal treatment at 700 masculineC. The powders revealed spherical and rod shape morphology. The optical quality of films showed a predominant band at 615 nm under 250 nm excitation. A preliminary luminescent test provided the properties of the Eu(3+) doped BaTiO(3).

  19. Spectroscopic and laser cooling results on Yb3+-doped BaY2F8 single crystal

    NASA Astrophysics Data System (ADS)

    Bigotta, Stefano; Parisi, Daniela; Bonelli, Lucia; Toncelli, Alessandra; Tonelli, Mauro; Di Lieto, Alberto

    2006-07-01

    Anti-Stokes cooling has been observed in an Yb3+-doped BaY2F8 single crystal. Single crystals have been grown by the Czochralski technique. The absorption spectra and the emission properties have been measured at room temperature and at 10K. The energy positions of the Stark sublevels of the ground and the excited state manifolds have been determined and separated from the vibronic substructure. The intrinsic decay time of the F5/22 level has been measured taking care of avoiding the effect of multiple reabsorption processes. The theoretical and experimental cooling efficiencies of Yb:BaY2F8 are evaluated and compared with respect to those of the most frequently investigated materials for laser cooling. A temperature drop of almost 4K was measured by pumping the crystal with 3W of laser radiation at ˜1025nm in single pass configuration with a cooling efficiency of ˜3%.

  20. Synthesis of the complex fluoride LiBaF 3 and optical spectroscopy properties of LiBaF 3: M( M=Eu,Ce) through a solvothermal process

    NASA Astrophysics Data System (ADS)

    Hua, Ruinian; Lei, Bingfu; Xie, Demin; Shi, Chunshan

    2003-11-01

    The complex fluoride LiBaF 3 and LiBaF 3: M( M=Eu, Ce) is solvothermally synthesized at 180°C and characterized by means of X-ray powder diffraction, scanning electron microscopy, thermogravimetric analysis and infrared spectroscopy. In the solvothermal process, the solvents, molar ratios of initial mixtures and reaction temperature play important roles in the formation of products. The excitation and emission spectra of the LiBaF 3: M( M=Eu,Ce) have been measured by fluorescence spectrophotometer. In the LiBaF 3:Eu emission spectra, there is one sharp line emission located at 360 nm arising from f→ f transition of Eu 2+ in the host lattice, and typical doublet 5 d-4 f emission of Ce 3+ in LiBaF 3 powder is shown.

  1. Investigation of Upconversion, downshifting and quantum –cutting behavior of Eu3+, Yb3+, Bi3+ co-doped LaNbO4 phosphor as a spectral conversion material

    NASA Astrophysics Data System (ADS)

    Dwivedi, A.; Mishra, K.; Rai, S. B.

    2018-06-01

    This work presents the spectral conversion characteristics [upconversion (UC), downshifting (DS) and quantum–cutting (QC) optical processes] of Eu3+, Yb3+ and Bi3+ co-doped LaNbO4 (LBO) phosphor samples synthesized by solid state reaction technique. The crystal structure and the pure phase formation have been confirmed by x-ray diffraction (XRD) measurements. The surface morphology and particle size are studied by scanning electron microscopy (SEM). The rarely observed intense red UC emission from Eu3+ ion has been successfully obtained in Eu3+/Yb3+ co-doped LaNbO4 phosphor (on excitation with 980 nm) by optimizing the concentrations of Eu3+ and Yb3+ ions. The downshifting (DS) behavior has been studied by photoluminescence (PL) measurements on excitation with 265 nm wavelength from a Xe lamp source. A broad blue emission in the region 300–550 nm with its maximum ∼415 nm due to charge transfer band (CTB) of the host and large number of sharp peaks due to f-f transitions of Eu3+ ion have been observed. The energy transfer has been observed from (NbO4)3‑ to Eu3+ ion and the fluorescence emission has been optimized by varying the concentration of Eu3+ ion. An intense red emission has also been observed corresponding to 5D0 → 7F2 transition of Eu3+ ion at 611 nm in LBO: 0.09Eu3+ phosphor on excitation with 394 nm. The luminescence properties of Eu3+ ion are enhanced further through the sensitization effect of Bi3+ ion. The near infra-red (NIR) quantum cutting (QC) behavior due to Yb3+ ion has been monitored on excitation with 265 as well as 394 nm. The NIR QC is observed due to 2F5/2 → 2F7/2 transition of Yb3+ ion via co-operative energy transfer (CET) process from (NbO4)3‑ as well as Eu3+ ions to Yb3+ ion. This multimodal behavior (UC, DS and QC) makes this a promising phosphor material for multi-purpose spectral converter.

  2. Eu-Doped BaTiO3 Powder and Film from Sol-Gel Process with Polyvinylpyrrolidone Additive

    PubMed Central

    García-Hernández, Margarita; García-Murillo, Antonieta; de J. Carrillo-Romo, Felipe; Jaramillo-Vigueras, David; Chadeyron, Geneviève; De la Rosa, Elder; Boyer, Damien

    2009-01-01

    Transparent BaTiO3:Eu3+ films were prepared via a sol-gel method and dip-coating technique, using barium acetate, titanium butoxide, and polyvinylpyrrolidone (PVP) as modifier viscosity. BaTiO3:Eu3+ films ~500 nm thick, crystallized after thermal treatment at 700 ºC. The powders revealed spherical and rod shape morphology. The optical quality of films showed a predominant band at 615 nm under 250 nm excitation. A preliminary luminescent test provided the properties of the Eu3+ doped BaTiO3. PMID:19865533

  3. Analysis of Sr{sub 5{minus}x}Ba{sub x}(PO{sub 4}){sub 3}F:Yb{sup 3+} crystals for improved laser performance with diode-pumping

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Schaffers, K.I.; Bayramian, A.J.; Marshall, C.D.

    Crystals of Yb{sup 3+}:Sr{sub 1-x}Ba{sub x}(PO{sub 4}){sub 3}F (0 < x < 5) have been investigated as a means to obtain broader absorption bands than are currently available with Yb{sup 3+}:S-FAP [Yb{sup 3+}: Sr{sub 5}(PO{sub 4}){sub 3}F], thereby improving diode-pumping efficiency for high peak power applications. Large diode-arrays have a FWHM pump band of >5 nm while the FWHM of the 900 nm absorption band for Yb:S-FAP is 5.5 nm; therefore, a significant amount of pump power can be wasted due to the nonideal overlap. Spectroscopic analysis of Yb:Sr{sub 5-x}Ba{sub x}-FAP crystals indicates that adding barium to the lattice increasesmore » the pump band to 13-16 run which more than compensates for the diode-array pump source without a detrimental reduction in absorption cross section. However, the emission cross section decreases by approximately half with relatively no effect on the emission lifetime. The small signal gain has also been measured and compared to the parent material Yb:S-FAP and emission cross sections have been determined by the method of reciprocity, the Filchtbauer-Ladenburg method, and small signal gain. Overall, Yb{sup 3+}:Sr{sub 5-x}Ba{sub x}(PO{sub 4}){sub 3}F crystals appear to achieve the goal of nearly matching the favorable thermal and laser performance properties of Yb:S-FAP while having a broader absorption band to better accommodate diode pumping.« less

  4. Growth, improved thermal stability and spectral properties of Yb3+-ions doped high temperature phase α-Ba3Gd(BO3)3 crystals co-doped by Sr2+, Ca2+ and La3+ ions

    NASA Astrophysics Data System (ADS)

    Pan, Shangke; Zhang, Jianyu; Pan, Jianguo

    2018-02-01

    To investigate the cause of the thermal instability of Yb3+-ions doped Ba3Gd(BO3)3 crystal grown from Czochralski technique, the low temperature phase β-Ba3Gd(BO3)3 powder was synthesized at the temperature of 800 °C. To inhibit the phase transition of high temperature phase Yb:α-Ba3Gd(BO3)3 during the crystal growth process, co-doping ions Sr2+, Ca2+ and La3+ ions were introduced in Yb:α-Ba3Gd(BO3)3 crystal. The melting point increased and the thermal stability of Yb:α-Ba3Gd(BO3)3 crystal was improved by co-doping ions. The absorption peaks of co-doped crystals centered at 976 nm with FWHM of 11, 11 and 12 nm and the absorption cross sections were 3.40 × 10-21 cm2, 4.00 × 10-21 cm2 and 2.66 × 10-21 cm2, respectively. The emission cross sections at 1040 nm were 2.19 × 10-21 cm2, 2.53 × 10-21 cm2 and 1.93 × 10-21 cm2, respectively. The fluorescence times of co-doped by Sr2+, Ca2+ and La3+ ions were shorter than that of Yb:α-Ba3Gd(BO3)3 crystal. So Yb:α-Ba3Gd(BO3)3 crystals co-doped by Sr2+, Ca2+ and La3+ ions will be more suitable for LD-pumping laser.

  5. First-principles calculation on electronic structure and optical property of BaSi{sub 2}O{sub 2}N{sub 2}:Eu{sup 2+} phosphor

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Tong, Zhi-Fang, E-mail: tongzhifang1998@126.com; Wei, Zhan-Long; Xiao, Cheng

    The crystal structure, electronic structure and optical properties of BaSi{sub 2}O{sub 2}N{sub 2}:Eu{sup 2+} with varying Eu doping concentrations are computed by the density functional theory (DFT) and compared with experimental results. The results show that the lattice parameters of primitive cells of Ba{sub 1−x}Si{sub 2}O{sub 2}N{sub 2}:Eu{sub x} become smaller and Eu–N bond length shortens as Eu concentration increases. The band structure of Ba{sub 1−x}Si{sub 2}O{sub 2}N{sub 2}:Eu{sub x} exhibits a direct optical band gap and it's propitious to luminescence. The energy differences from the lowest Eu 5d state to the lowest Eu 4f state decrease with increasing Eumore » concentrations. The analysis of simulative absorption spectra indicates that the electron transition from Eu 4f states to 5d states of both Eu and Ba atoms contributes to the absorption of Ba{sub 1−x}Si{sub 2}O{sub 2}N{sub 2}:Eu{sub x}. Under the coupling effect between Eu and Ba, Ba in BaSi{sub 2}O{sub 2}N{sub 2} exhibits longer wavelength absorption and increases absorption efficiency. The emission wavelength is deduced by measuring energy differences from the lowest Eu 5d state to the lowest Eu 4f state, and the result is in good agreement with experimental value within experimental Eu{sup 2+} doping range. - Graphical abstract: The structure and optical property of BaSi{sub 2}O{sub 2}N{sub 2}:Eu{sup 2+} are computed by DFT and its absorption mechanism is analysed. Results show that absorption peak α is from the host lattice absorption. The absorption peaks β, γ and δ are from Eu 4f to Eu 5d and Ba 6s 5d states. The absorption is attributed to the coupling effect of Eu and Ba atom. - Highlights: • The crystal, electronic structure and optical properties of BaSi{sub 2}O{sub 2}N{sub 2}:Eu{sup 2+} are computed by DFT. • The lattice parameters of primitive cells reduces and Eu–N bond length shortens as Eu{sup 2+} increases. • The energy gap from Eu 5d state to Eu 4f state

  6. Direct visualization of gastrointestinal tract with lanthanide-doped BaYbF5 upconversion nanoprobes.

    PubMed

    Liu, Zhen; Ju, Enguo; Liu, Jianhua; Du, Yingda; Li, Zhengqiang; Yuan, Qinghai; Ren, Jinsong; Qu, Xiaogang

    2013-10-01

    Nanoparticulate contrast agents have attracted a great deal of attention along with the rapid development of modern medicine. Here, a binary contrast agent based on PAA modified BaYbF5:Tm nanoparticles for direct visualization of gastrointestinal (GI) tract has been designed and developed via a one-pot solvothermal route. By taking advantages of excellent colloidal stability, low cytotoxicity, and neglectable hemolysis of these well-designed nanoparticles, their feasibility as a multi-modal contrast agent for GI tract was intensively investigated. Significant enhancement of contrast efficacy relative to clinical barium meal and iodine-based contrast agent was evaluated via X-ray imaging and CT imaging in vivo. By doping Tm(3+) ions into these nanoprobes, in vivo NIR-NIR imaging was then demonstrated. Unlike some invasive imaging modalities, non-invasive imaging strategy including X-ray imaging, CT imaging, and UCL imaging for GI tract could extremely reduce the painlessness to patients, effectively facilitate imaging procedure, as well as rationality economize diagnostic time. Critical to clinical applications, long-term toxicity of our contrast agent was additionally investigated in detail, indicating their overall safety. Based on our results, PAA-BaYbF5:Tm nanoparticles were the excellent multi-modal contrast agent to integrate X-ray imaging, CT imaging, and UCL imaging for direct visualization of GI tract with low systemic toxicity. Copyright © 2013 Elsevier Ltd. All rights reserved.

  7. Broadband down-conversion based near infrared quantum cutting in Eu{sup 2+}–Yb{sup 3+} co-doped SrAl{sub 2}O{sub 4} for crystalline silicon solar cells

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Tai, Yuping, E-mail: yupingtai@126.com; Zheng, Guojun, E-mail: zhengguojun88@126.com; Wang, Hui, E-mail: huiwang@nwu.edu.cn

    2015-03-15

    Near infrared (NIR) quantum cutting involving the down conversion of an absorbed visible photon to emission of two NIR photons was achieved in SrAl{sub 2}O{sub 4}:0.01Eu{sup 2+}, xYb{sup 3+} (x=0, 1, 2, 5, 10, 20, 30 mol%) samples. The photoluminescence properties of samples in visible and NIR regions were measured to verify the energy transfer (ET) from Eu{sup 2+} to Yb{sup 3+}. The results demonstrated that Eu{sup 2+} was an efficient sensitizer for Yb{sup 3+} in the SrAl{sub 2}O{sub 4} host lattice. According to Gaussian fitting analysis and temperature-dependent luminescence experiments, the conclusion was drawn that the cooperative energy transfermore » (CET) process dominated the ET process and the influence of charge transfer state (CTS) of Yb{sup 3+} could be negligible. As a result, the high energy transfer efficiency (ETE) and quantum yield (QY) have been acquired, the maximum value approached 73.68% and 147.36%, respectively. Therefore, this down-conversion material has potential application in crystalline silicon solar cells to improve conversion efficiency. - Graphical abstract: Near infrared quantum cutting was achieved in Eu{sup 2+}–Yb{sup 3+} co-doped SrAl{sub 2}O{sub 4} samples. The cooperative energy transfer process dominated energy transfer process and high energy transfer efficiency was acquired. - Highlights: • The absorption spectrum of Eu{sup 2+} ion is strong in intensity and broad in bandwidth. • The spectra of Eu{sup 2+} in SrAl{sub 2}O{sub 4} lies in the strongest region of solar spectrum. • The cooperative energy transfer (CET) dominated the energy transfer process. • The domination of CET is confirmed by experimental analysis. • SrAl{sub 2}O{sub 4}:Eu{sup 2+},Yb{sup 3+} show high energy transfer efficiency and long lifetime.« less

  8. Eu(2+)-Activated Alkaline-Earth Halophosphates, M5(PO4)3X:Eu(2+) (M = Ca, Sr, Ba; X = F, Cl, Br) for NUV-LEDs: Site-Selective Crystal Field Effect.

    PubMed

    Kim, Donghyeon; Kim, Sung-Chul; Bae, Jong-Seong; Kim, Sungyun; Kim, Seung-Joo; Park, Jung-Chul

    2016-09-06

    Eu(2+)-activated M5(PO4)3X (M = Ca, Sr, Ba; X = F, Cl, Br) compounds providing different alkaline-earth metal and halide ions were successfully synthesized and characterized. The emission peak maxima of the M5(PO4)3Cl:Eu(2+) (M = Ca, Sr, Ba) compounds were blue-shifted from Ca to Ba (454 nm for Ca, 444 nm for Sr, and 434 nm for Ba), and those of the Sr5(PO4)3X:Eu(2+) (X = F, Cl, Br) compounds were red-shifted along the series of halides, F → Cl → Br (437 nm for F, 444 nm for Cl, and 448 nm for Br). The site selectivity and occupancy of the activator ions (Eu(2+)) in the M5(PO4)3X:Eu(2+) (M = Ca, Sr, Ba; X = F, Cl, Br) crystal lattices were estimated based on theoretical calculation of the 5d → 4f transition energies of Eu(2+) using LCAO. In combination with the photoluminescence measurements and theoretical calculation, it was elucidated that the Eu(2+) ions preferably enter the fully oxygen-coordinated sites in the M5(PO4)3X:Eu(2+) (M = Ca, Sr, Ba; X = F, Cl, Br) compounds. This trend can be well explained by "Pauling's rules". These compounds may provide a platform for modeling a new phosphor and application in the solid-state lighting field.

  9. A novel tunable white light emitting multiphase phosphor obtained from Ba2TiP2O9 by introducing Eu3+

    NASA Astrophysics Data System (ADS)

    Zhou, Zhenzhen; Liu, Guanghui; Wan, Jieqiong; Ni, Jia; Lu, Zhouguang; Ma, Ruguang; Zhou, Yao; Wang, Jiacheng; Liu, Qian

    2016-04-01

    Tunable white light was realized in samples Ba2(1- x)TiP2O9:2 xEu ( x = 0-0.80) by introducing orange-red light emitting Eu3+ in self-activated blue-green light emitting matrix Ba2TiP2O9. The sample Ba2(1- x)TiP2O9:2 xEu is a multiphase system consisting of Ba2TiP2O9, EuPO4 and TiO2 when x is greater than or equal to 0.20. The tunable light from blue-green to bluish-white, to white, and eventually to pinky-white of samples Ba2(1- x)TiP2O9:2 xEu under UV light excitation is attributed to the light mixture of tunable blue-green light from Ti4+-O2- charge transfer transition in Ba2TiP2O9 and orange-red light from Eu3+ 4f-4f transition mostly in EuPO4. The Commission International de l'Eclairage chromaticity coordinates, correlated color temperature and color rendering index were tuned from (0.262, 0.339), 9492 K and 74 for matrix sample Ba2TiP2O9 to (0.324, 0.346), 5876 K and 87 for sample Ba2(1- x)TiP2O9:2 xEu ( x = 0.40) under UV light excitation. Therefore, a kind of promising UV-excited white light emitting multiphase phosphor was obtained.

  10. Growth and scintillation properties of Eu doped BaCl2/LiF eutectic scintillator

    NASA Astrophysics Data System (ADS)

    Kamada, Kei; Hishinuma, Kosuke; Kurosawa, Shunsuke; Yamaji, Akihiro; Shoji, Yasuhiro; Pejchal, Jan; Yokota, Yuui; Ohashi, Yuji; Yoshikawa, Akira

    2015-12-01

    Eu doped BaCl2/LiF eutectics were grown by the micro-pulling down method and their directionally solidified eutectic (DSE) system has been investigated. The grown eutectic showed main phases of cubic LiF and orthorhombic BaCl2. In these eutectics, the 399 nm emission of Eu2+ 4f5d was obtained. It shows the intrinsic decay time of about 410 ns. The light yield of the 1-mm-thick eutectic showed 7000 ph/5.5 MeV alpha-ray.

  11. Synthesis and Photoluminescence Properties of BaWO4:RE3+ (RE = Eu or Sm) Phosphors

    NASA Astrophysics Data System (ADS)

    Cho, Shinho

    2018-04-01

    BaWO4:RE3+ (RE = Eu or Sm) phosphor powders were prepared with different doping concentrations of the activator ion by using the conventional solid-state reaction method. The dependences in the crystal structure, luminescence intensity, and morphology on the Eu3+ and the Sm3+ concentrations in BaWO4 were investigated using X-ray diffraction (XRD), photoluminescence spectrophotometry, and scanning electron microscopy (SEM), respectively. XRD analysis showed tetragonal BaWO4 structures for all the phosphors synthesized, regardless of the type and the doping concentration of the activator ion. SEM images indicated that as the concentration of activator ions was increased, the crystalline particles showed an increasing tendency to agglomerate irregularly. The room temperature excitation spectra of Eu3+- or Sm3+-doped BaWO4 phosphors consisted of a broad charge transfer band in the ultraviolet region and several sharp 4 f-4 f transitions. When Eu3+-doped BaWO4 phosphors were excited at 274 nm, the emission spectra exhibited sharp bands due to inner shell transitions occurring from the excited energy state 5 D 0 to the lower energy levels 7 F J ( J = 1, 2, 3, and 4). For Sm3+-doped BaWO4 phosphors, three intense emission peaks at 568, 603, and 649 nm and a very weak line at 712 nm were observed. The highest asymmetry ratio-the intensity ratio of the 4 G 5/2 → 6 H 9/2 electric dipole to the 4 G 5/2 → 6 H 5/2 magnetic dipole transitions-was obtained for 1 mol% doping of Sm3+, indicating that the Sm3+ ions occupied the non-inversion symmetry sites.

  12. Sol–gel synthesis, structure and luminescence properties of Ba{sub 2}ZnMoO{sub 6}:Eu{sup 3+} phosphors

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Li, Yuntong; Liu, Xiaohua, E-mail: xhliuxhliu@tom.com

    2015-04-15

    Graphical abstract: The phosphor powders of Ba{sub 2}ZnMoO{sub 6}:Eu{sup 3+} were prepared by sol–gel method. The dependence of luminescence intensity on the Eu{sup 3+} concentration was investigated. - Highlights: • We synthesize Ba{sub 2}ZnMoO{sub 6}:Eu{sup 3+} phosphors by the sol–gel method. • The effect of temperature on the crystallinity and morphology is investigated. • The phosphor presents an intense CT band in near UV range (370–410 nm). • The concentration quenching mechanism is the exchange interaction. - Abstract: Double-perovskite Ba{sub 2}Zn{sub 1−x}MoO{sub 6}:xEu{sup 3+} (x = 0, 0.02, 0.04, 0.06, 0.08, 0.1) orange–red emitting phosphors were synthesized by using themore » sol–gel method. The crystalline structure and photoluminescence properties of the phosphors were investigated. The X-ray diffraction (XRD) patterns indicate that the structure of matrix Ba{sub 2}ZnMoO{sub 6} is cubic double-perovskite with space group Fm-3m. The Ba{sub 2}ZnMoO{sub 6}:Eu{sup 3+} phosphors present an intense broad charge transfer (CT) band absorption in near UV range (370–410 nm), which attributes to the charge transfer state of MoO{sub 6}, and performs orange–red emission of Eu{sup 3+} ({sup 5}D{sub 0} → {sup 7}F{sub 1} transition) at around 596 nm. A low concentration quenching occurs in Ba{sub 2}ZnMoO{sub 6}:Eu{sup 3+} and the optimal doping concentration is about 6 mol%. The Ba{sub 2}ZnMoO{sub 6}:Eu{sup 3+} phosphors are considered to be a promising orange–red emitting phosphor for near ultraviolet GaN-based white light emitting diode.« less

  13. A new BaB{sub 2}Si{sub 2}O{sub 8}:Eu{sup 2+}/Eu{sup 3+}, Tb{sup 3+} phosphor - Synthesis and photoluminescence properties

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Saradhi, M.P.; Department of Chemistry, Indian Institute of Technology Hyderabad, Yeddumailaram, Hyderabad - 502205; Laboratoire de Cristallographie et Sciences des Materiaux, ENSICAEN, Universite de Caen, CNRS, 6 Bd Marechal Juin, F-14050 Caen

    2010-10-15

    In the present work, we have synthesized maleevite mineral phase BaB{sub 2}Si{sub 2}O{sub 8} for the first time, which is isostructural with the pekovite mineral SrB{sub 2}Si{sub 2}O{sub 8}. In these europium doped host lattices, we observed the partial reduction of Eu{sup 3+} to Eu{sup 2+} at high temperature during the synthesis in air. Tb{sup 3+} co-doping in MB{sub 2}Si{sub 2}O{sub 8}:0.01(Eu{sup 3+}/Eu{sup 2+}) [M=Sr, Ba] improves the emission properties towards white light. The emission color varies from bluish white to greenish white under UV lamp excitation when the host cation changes from Sr to Ba. - Graphical abstract: Themore » figure shows structure refinement of both MB{sub 2}Si{sub 2}O{sub 8} [M=Sr, Ba]. The structure refinement of newly synthesized phase BaB{sub 2}Si{sub 2}O{sub 8} was carried out by taking SrB{sub 2}Si{sub 2}O{sub 8} as starting structure model. Inset in the figure shows the structure projection of BaB{sub 2}Si{sub 2}O{sub 8}. The Sr{sup 2+}/Ba{sup 2+} are embedded in polyanionic network formed by corner sharing BO{sub 4}{sup 5-} and SiO{sub 4}{sup 4-} tetrahedral that intern form interconnected layers of 4 and 8 membered rings perpendicular to b-axis.« less

  14. Studies on up/down-conversion emission of Yb3+ sensitized Er3+ doped MLa2(MoO4)4 (M = Ba, Sr and Ca) phosphors for thermometry and optical heating

    NASA Astrophysics Data System (ADS)

    Sinha, Shriya; Kumar, Kaushal

    2018-01-01

    The photoluminescence properties of Yb3+ sensitized Er3+ doped BaLa2(MoO4)4, SrLa2(MoO4)4 and CaLa2(MoO4)4 phosphors synthesized via hydrothermal method are investigated upon 980 nm and 380 nm light excitations. The phase, purity, and morphology of the samples are characterized by X-ray diffraction, Fourier transform infrared spectroscopy and Field emission scanning electron microscope. Among these three phosphors, the strongest emission intensity is seen in BaLa2(MoO4)4: Er3+/Yb3+ through both the 980 nm and 380 nm light excitations and is explained by the lifetime measurement of 4S3/2 level of Er3+ ion. Temperature sensing measurements were performed by using the fluorescence intensity ratio (FIR) of green emission bands originated from the two thermally coupled 2H11/2 → 4I15/2 and 4S3//2 → 4I15/2 transitions of Er3+ and maximum temperature sensitivity of 1.05% K-1 at 305 K is found for BLa2(MoO4)4: Er3+/Yb3+ sample. Moreover, the laser induced heating is measured in the samples and the maximum temperature of the sample particles is calculated as 422 K at 76 W/cm2 in BaLa2(MoO4)4: Er3+/Yb3+, pointing out large amount of heat generation in such phosphors. The BaLa2(MoO4)4: Er3+/Yb3+ also exhibits higher photothermal conversion efficiency of 46.7%.

  15. Effect of Eu-doping on optical, structural and morphological properties of BaI2·nH2O powders

    NASA Astrophysics Data System (ADS)

    Salamakha, T.; Buryi, M.; Tratsiak, Y.

    2018-04-01

    The two-step approach to the Eu2+ doped BaI2·nH2O powders synthesis in Ar atmosphere from precursors containing different concentration of Eu3+ ions is reported. According to X-ray diffraction analysis the powders mainly consist of BaI2·2H2O phase. Their morphological, structural and luminescent properties depend on the Eu-ions concentration. The luminescence spectra are composed of broad and strong emission band peaking at 420 nm, which was related to the Eu2+ 5d-4f transition. Its intensity reaches maximum in the 2 at. % Eu2+ doped sample. Detailed analysis of the measured electron paramagnetic resonance spectra in the samples with different doping level confirms them belong to the Eu2+ ions substituting for the regular Ba2+ site in the BaI2 lattice. A sample exposed to the 330 nm UV irradiation exhibited an increase of the Eu2+ spectral intensity occurred exclusively due to the Eu3+ to Eu2+ transformation. No other signals either prior to or after the irradiation which might be attributed to the ions resided in e.g., interstitial positions or in any secondary phases were observed. Possible mechanisms of the Eu3+ stabilization in the host lattice with only divalent cation sites during the synthesis without additional treatment in reducing atmosphere are discussed as well.

  16. Activation of SO2 with [(η(5) -C5 Me5 )2 Ln(THF)2 ] (Ln=Eu, Yb) leading to dithionite and sulfinate complexes.

    PubMed

    Klementyeva, Svetlana V; Gamer, Michael T; Schmidt, Anna-Corina; Meyer, Karsten; Konchenko, Sergey N; Roesky, Peter W

    2014-10-13

    The reaction of decamethylytterbocene [(η(5) -C5 Me5 )2 Yb(THF)2 ] with SO2 at low temperature gave two new compounds, namely, the Yb(III) dithionite/sulfinate complex [{(η(5) -C5 Me5 )2 Yb(μ3 ,1κ(2) O(1,3) ,2κ(3) O(2,2',4) -S2 O4 )}2 {(η(5) -C5 Me5 )Yb(μ,1κO,2κO'-C5 Me5 SO2 )}2 ] (1) and the Yb(III) dithionite complex [{(η(5) -C5 Me5 )2 Yb}2 (μ,1κ(2) O(1,3) ,2κ(2) O(2,4) -S2 O4 )] (2). After extraction of 1, the mixture was heated to give the dinuclear tetrasulfinate complex [{(η(5) -C5 Me5 )Yb}2 (μ,κO,κO'-C5 Me5 SO2 )4 ] (3 a). In contrast, from the reaction of [(η(5) -C5 Me5 )2 Eu(THF)2 ] with SO2 only the tetrasulfinate complex [{(η(5) -C5 Me5 )Eu}2 (μ,κO,κO'-C5 Me5 SO2 )4 ] (3 b) was isolated. Two major reaction pathways were observed: 1) reductive coupling of two SO2 molecules to form the dithionite anion S2 O4 (2-) ; and 2) nucleophilic attack of one metallocene C5 Me5 ligand on the sulfur atom of SO2 . The compounds presented are the first dithionite and sulfinate complexes of the f-elements. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Insights into the discrepant luminescence for BaSiO3 :Eu2+ phosphors prepared by solid-state reaction and precipitation reaction methods.

    PubMed

    Xu, Jiao; Zhao, Yang; Chen, Jingjing; Mao, Zhiyong; Yang, Yanfang; Wang, Dajian

    2017-09-01

    Two synthesis routes, solid-state reaction and precipitation reaction, were employed to prepare BaSiO 3 :Eu 2+ phosphors in this study. Discrepancies in the luminescence green emission at 505 nm for the solid-state reaction method sample and in the yellow emission at 570 nm for the sample prepared by the precipitation reaction method, were observed respectively. A detail investigation about the discrepant luminescence of BaSiO 3 :Eu 2+ phosphors was performed by evaluation of X-ray diffraction (XRD), photoluminescence (PL)/photoluminescence excitation (PLE), decay time and thermal quenching properties. The results showed that the yellow emission was generated from the BaSiO 3 :Eu 2+ phosphor, while the green emission was ascribed to a small amount of Ba 2 SiO 4 :Eu 2+ compound that was present in the solid-state reaction sample. This work clarifies the luminescence properties of Eu 2+ ions in BaSiO 3 and Ba 2 SiO 4 hosts. Copyright © 2017 John Wiley & Sons, Ltd.

  18. Green-emissive transparent BaSi 2O 5:Eu 2 + film phosphor on quartz glass created by a sputtering thermal diffusion process

    NASA Astrophysics Data System (ADS)

    Seo, K. I.; Park, J. H.; Kim, J. S.; Na, Y. H.; Choi, J. C.; Bae, J. S.

    2009-10-01

    Eu 2+-doped BaSi 2O 5 film phosphors on quartz substrates are fabricated by radio-frequency magnetron sputtering thermal diffusion. The BaSi 2O 5: Eu 2+ phosphor crystals have some preferred orientations that are lattice-spacing matched with the crystallized β- SiO 2 crystals, and they show pore and grain boundary-free morphology with a rod-like shape fused into the crystallized β- SiO 2 crystals. The BaSi 2O 5: Eu 2+ film phosphor has a high transparency, with a transmittance of about 30% in visible light. The BaSi 2O 5: Eu 2+ film phosphor shows 510 nm green emission from the f-d transition of the Eu 2+ ions, and in particular the best sample shows a green photoluminescence brightness of about 5% of a BaSi 2O 5: Eu 2+ powder phosphor screen. These excellences in optical properties can be explained by less optical scattering at pores or grain boundaries, and less reflection at the continuously index-changed interface.

  19. Simultaneous multi-wavelength ultraviolet excited single-phase white light emitting phosphor Ba1-x(Zr,Ti)Si3O9:xEu

    NASA Astrophysics Data System (ADS)

    Zhou, Zhenzhen; Liu, Guanghui; Ni, Jia; Liu, Wanlu; Liu, Qian

    2018-05-01

    A kind of novel compound Ba1-x(Zr,Ti)Si3O9:xEu simultaneously activated by different-valence Eu2+ and Eu3+ ions has been successfully synthesized. The existence of Ti4+-O2- charge transfer (CT) transitions in Ba1-xZrSi3O9:xEu is proved by the photoluminescence spectra and first principle calculations, and the Ti4+ ions come from the impurities in commercial ZrO2 raw materials. Under the excitation of multi-wavelength ultraviolet radiation (λEX = 392, 260, 180 nm), Ba1-xZrSi3O9:xEu (x = 0.15) can directly emit nearly white light. The coexistence of multiple luminescent centers and the energy transfer among Zr4+-O2- CT state, Ti4+-O2- CT state, Eu2+ and Eu3+ ions play important roles in the white light emission. Ba1-xZrSi3O9:xEu (x = 0.15) has good thermal stability, in particular, the intensity of emission spectrum (λEX = 392 nm) at 150 °C is ∼96% of that at room temperature. In general, the multi-wavelength ultraviolet-excited single-phase white light emitting phosphor Ba1-x(Zr,Ti)Si3O9:xEu possesses a promise for applications in white light emitting diodes (WLEDs), agriculture, medicine and other photonic fields.

  20. Correlation of Structure, Tunable Colors, and Lifetimes of (Sr, Ca, Ba)Al₂O₄:Eu2+, Dy3+ Phosphors.

    PubMed

    Xie, Qidi; Li, Bowen; He, Xin; Zhang, Mei; Chen, Yan; Zeng, Qingguang

    2017-10-18

    (Sr, Ca, Ba)Al₂O₄:Eu 2+ , Dy 3+ phosphors were prepared via a high temperature solid-state reaction method. The correlation of phase structure, optical properties and lifetimes of the phosphors are investigated in this work. For the (Sr, Ca)Al₂O₄:Eu 2+ ,Dy 3+ phosphors, the different phase formation from monoclinic SrAl₂O₄ phase to hexagonal SrAl₂O₄ phase to monoclinic CaAl₂O₄ phase was observed when the Ca content increased. The emission color of SrAl₂O₄:Eu 2+ , Dy 3+ phosphors varied from green to blue. For the (Sr, Ba)Al₂O₄:Eu 2+ , Dy 3+ phosphors, different phase formation from the monoclinic SrAl₂O₄ phase to the hexagonal BaAl₂O₄ phase was observed, along with a shift of emission wavelength from 520 nm to 500 nm. More interestingly, the decay time of SrAl₂O₄:Eu 2+ , Dy 3+ changed due to the different phase formations. Lifetime can be dramatically shortened by the substitution of Sr 2+ with Ba 2+ cations, resulting in improving the performance of the alternating current light emitting diode (AC-LED). Finally, intense LEDs are successfully obtained by combining these phosphors with Ga(In)N near UV chips.

  1. Study on photoluminescence and energy transfer of Eu3+/Sm3+ single-doped and co-doped BaB8O13 phosphors

    NASA Astrophysics Data System (ADS)

    Lephoto, Mantwa A.; Tshabalala, Kamohelo G.; Motloung, Selepe J.; Ahemen, Iorkyaa; Ntwaeaborwa, Odireleng M.

    2018-04-01

    A series of Sm3+, Eu3+ and Eu3+- Sm3+ doped BaB8O13 were synthesized by using a solution combustion method. When excited at 394 nm, BaB8O13: Eu3+ emits red light, and the strongest peak was located at 614 nm, which is attributed to the 5D0→7F2 transition of Eu3+. BaB8O13: Sm3+ produced red-orange light, and the major emission peak was located at 596 nm under the 402 nm radiation excitation, which is assigned to the 4G5/2→6H7/2 transition of Sm3+. When excited at 402 nm, the PL emission intensity from BaB8O13: 0.05Eu3+; 0.005Sm3+ at 614 nm was enhanced considerably compared to that of the sample without Sm3+, suggesting that energy was transferred from Sm3+ to Eu3+. The Commission International de I‧Eclairage (CIE) chromaticity coordinates of BaB8O13: 0.05Eu3+; 0.005Sm3+ powder phosphor (0.637, 0.362) are located in the red region indicating that the phosphor can serve as a source of red light in LEDs.

  2. Origin and Luminescence of Anomalous Red-Emitting Center in Rhombohedral Ba9Lu2Si6O24:Eu(2+) Blue Phosphor.

    PubMed

    Liu, Yongfu; Zhang, Changhua; Cheng, Zhixuan; Zhou, Zhi; Jiang, Jun; Jiang, Haochuan

    2016-09-06

    We obtain a blue phosphor, Ba9Lu2Si6O24:Eu(2+) (BLS:Eu(2+)), which shows a strong emission peak at 460 nm and a weak tail from 460 to 750 nm. A 610 nm red emission is observed for the first time in this kind of rhombohedral structure material, which is much different from the same crystal structure of Ba9Sc2Si6O24:Eu(2+) and Ba9Y2Si6O24:Eu(2+). The luminescence properties and decays from 10 to 550 K are discussed. The new red emission arises from a trapped exciton state of Eu(2+) at the Ba site with a larger coordination number (12-fold). It exhibits abnormal luminescence properties with a broad bandwidth and a large Stokes shift. Under the 400 nm excitation, the external quantum efficiency of BLS:Eu(2+) is 45.4%, which is higher than the 35.7% for the commercial blue phosphor BAM:Eu(2+). If the thermal stability of BLS:Eu(2+) can be improved, it will show promising applications in efficient near-UV-based white LEDs.

  3. Multifunctional Eu3+- and Er3+/Yb3+-doped GdVO4 nanoparticles synthesized by reverse micelle method

    PubMed Central

    Gavrilović, Tamara V.; Jovanović, Dragana J.; Lojpur, Vesna; Dramićanin, Miroslav D.

    2014-01-01

    Synthesis of Eu3+- and Er3+/Yb3+-doped GdVO4 nanoparticles in reverse micelles and their multifunctional luminescence properties are presented. Using cyclohexane, Triton X-100, and n-pentanol as the oil, surfactant, and co-surfactant, respectively, crystalline nanoparticles with ~4 nm diameter are prepared at low temperatures. The particle size assessed using transmission electron microscopy is similar to the crystallite size obtained from X-ray diffraction measurements, suggesting that each particle comprises a single crystallite. Eu3+-doped GdVO4 nanoparticles emit red light through downconversion upon UV excitation. Er3+/Yb3+-doped GdVO4 nanoparticles exhibit several functions; apart from the downconversion of UV radiation into visible green light, they act as upconvertors, transforming near-infrared excitation (980 nm) into visible green light. The ratio of green emissions from 2H11/2 → 2I15/2 and 4S3/2 → 4I15/2 transitions is temperature dependent and can be used for nanoscale temperature sensing with near-infrared excitation. The relative sensor sensitivity is 1.11%K−1, which is among the highest sensitivities recorded for upconversion-luminescence-based thermometers. PMID:24572638

  4. Multifunctional Eu3+- and Er3+/Yb3+-doped GdVO4 nanoparticles synthesized by reverse micelle method

    NASA Astrophysics Data System (ADS)

    Gavrilović, Tamara V.; Jovanović, Dragana J.; Lojpur, Vesna; Dramićanin, Miroslav D.

    2014-02-01

    Synthesis of Eu3+- and Er3+/Yb3+-doped GdVO4 nanoparticles in reverse micelles and their multifunctional luminescence properties are presented. Using cyclohexane, Triton X-100, and n-pentanol as the oil, surfactant, and co-surfactant, respectively, crystalline nanoparticles with ~4 nm diameter are prepared at low temperatures. The particle size assessed using transmission electron microscopy is similar to the crystallite size obtained from X-ray diffraction measurements, suggesting that each particle comprises a single crystallite. Eu3+-doped GdVO4 nanoparticles emit red light through downconversion upon UV excitation. Er3+/Yb3+-doped GdVO4 nanoparticles exhibit several functions; apart from the downconversion of UV radiation into visible green light, they act as upconvertors, transforming near-infrared excitation (980 nm) into visible green light. The ratio of green emissions from 2H11/2 --> 2I15/2 and 4S3/2 --> 4I15/2 transitions is temperature dependent and can be used for nanoscale temperature sensing with near-infrared excitation. The relative sensor sensitivity is 1.11%K-1, which is among the highest sensitivities recorded for upconversion-luminescence-based thermometers.

  5. Multifunctional Eu3+- and Er3+/Yb3+-doped GdVO4 nanoparticles synthesized by reverse micelle method.

    PubMed

    Gavrilović, Tamara V; Jovanović, Dragana J; Lojpur, Vesna; Dramićanin, Miroslav D

    2014-02-27

    Synthesis of Eu(3+)- and Er(3+)/Yb(3+)-doped GdVO4 nanoparticles in reverse micelles and their multifunctional luminescence properties are presented. Using cyclohexane, Triton X-100, and n-pentanol as the oil, surfactant, and co-surfactant, respectively, crystalline nanoparticles with ~4 nm diameter are prepared at low temperatures. The particle size assessed using transmission electron microscopy is similar to the crystallite size obtained from X-ray diffraction measurements, suggesting that each particle comprises a single crystallite. Eu(3+)-doped GdVO4 nanoparticles emit red light through downconversion upon UV excitation. Er(3+)/Yb(3+)-doped GdVO4 nanoparticles exhibit several functions; apart from the downconversion of UV radiation into visible green light, they act as upconvertors, transforming near-infrared excitation (980 nm) into visible green light. The ratio of green emissions from (2)H11/2 → (2)I15/2 and (4)S3/2 → (4)I15/2 transitions is temperature dependent and can be used for nanoscale temperature sensing with near-infrared excitation. The relative sensor sensitivity is 1.11%K(-1), which is among the highest sensitivities recorded for upconversion-luminescence-based thermometers.

  6. Photoluminescence properties and thermal stability of blue-emitting Ba5-xCl(PO4)3:xEu2+ (0.004≤x≤0.016) phosphors.

    PubMed

    Liu, Jie; Zhang, Zhi-Ming; Wu, Zhan-Chao; Wang, Fang-Fang; Li, Zhen-Jiang; Kuang, Shao-Ping; Wu, Ming-Mei

    2017-01-15

    A series of blue-emitting Ba 5-x Cl(PO 4 ) 3 :xEu 2+ (0.004≤x≤0.016) phosphors were synthesized by conventional high-temperature solid state reaction. The structure and photoluminescence (PL) properties of the phosphors were investigated. The as-prepared phosphors exhibit broad excitation band ranging from 250 to 420nm, and strong asymmetric blue emission band peaking at 436nm. The optimum concentration of Eu 2+ in the Ba 5 Cl(PO 4 ) 3 :Eu 2+ phosphor is x=0.01, and the concentration quenching mechanism is verified to be the combined actions of dipole-dipole interaction and radiation re-absorption mechanism. The thermal stability of Ba 5 Cl(PO 4 ) 3 :Eu 2+ was evaluated by temperature-dependent PL spectra. Compared with that of commercial BaMgAl 10 O 17 :Eu 2+ (BAM) phosphor, the Ba 5-x Cl(PO 4 ) 3 :xEu 2+ phosphors exhibit similarly excellent thermal quenching property. In addition, the CIE chromaticity coordinates of Ba 5-x Cl(PO 4 ) 3 :xEu 2+ (0.004≤x≤0.016) were calculated to evaluate the color quality. All the results indicate that Ba 5 Cl(PO 4 ) 3 :Eu 2+ is a promising candidate phosphor for near-ultraviolet (n-UV) pumped LED. Copyright © 2016 Elsevier B.V. All rights reserved.

  7. Anisotropic Exchange within Decoupled Tetrahedra in the Quantum Breathing Pyrochlore Ba 3 Yb 2 Zn 5 O 11

    DOE PAGES

    Rau, J. G.; Wu, L. S.; May, A. F.; ...

    2016-06-24

    Tmore » he low energy spin excitation spectrum of the breathing pyrochlore Ba 3 Yb 2 Zn 5 O 11 has been investigated with inelastic neutron scattering. Several nearly resolution limited modes with no observable dispersion are observed at 250 mK while, at elevated temperatures, transitions between excited levels become visible. o gain deeper insight, a theoretical model of isolated Yb 3+ tetrahedra parametrized by four anisotropic exchange constants is constructed. he model reproduces the inelastic neutron scattering data, specific heat, and magnetic susceptibility with high fidelity. he fitted exchange parameters reveal a Heisenberg antiferromagnet with a very large Dzyaloshinskii-Moriya interaction. Ultimately, using this model, we predict the appearance of an unusual octupolar paramagnet at low temperatures and speculate on the development of inter-tetrahedron correlations.« less

  8. Strong green fluorescent hydrogels with Ba2 MgSi2 O7 :Eu2+ phosphor embedded in cellulose.

    PubMed

    Zhang, Xinguo; Qin, Xingzhen; Chen, Hailan

    2017-06-01

    Non-cytotoxic and green-emitting fluorescent hydrogels were constructed from a cellulose solution containing Ba 2 MgSi 2 O 7 :Eu 2 + green phosphor in a NaOH/urea aqueous system. The structure, optical properties and cytotoxicity of these hydrogels were studied. The Ba 2 MgSi 2 O 7 :Eu 2 + phosphor particles were dispersed evenly in the cellulose hydrogel matrix. Good luminescent properties of Ba 2 MgSi 2 O 7 :Eu 2 + phosphor were maintained in the hydrogels, leading to strong green emission under ultraviolet excitation. Fluorescent hydrogels have no obvious cytotoxicity in a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) proliferation test, and have potential use in in vivo applications like optical imaging and drug delivery. Copyright © 2016 John Wiley & Sons, Ltd.

  9. Energy transfer in M₅(PO₄)₃  F:Eu²⁺,Ce³⁺ (M = Ca and Ba) phosphors.

    PubMed

    Shinde, K N; Dhoble, S J

    2014-08-01

    M5(PO4)3F:Eu(2+) (M = Ca and Ba) co-doped with Ce(3+) phosphors were successfully prepared by the combustion synthesis method. The introduction of co-dopant (Ce(3+)) into the host enhanced the luminescent intensity of the M5(PO4)3F:Eu(2+) (M = Ca and Ba) efficiently. Previously, we have reported the synthesis and photoluminescence properties of same phosphors. The aim of this article is to report energy transfer mechanism between Ce(3+) ➔Eu(2+) ions in M5(PO4)3F:Eu(2+) (M = Ca and Ba) phosphors, where Ce(3+) ions act as sensitizers and Eu(2+) ions act as activators. The M5(PO4)3F:Eu(2+) (M = Ca and Ba) co-doped with Ce(3+) phosphor exhibits great potential for use in white ultraviolet (UV) light-emitting diode applications to serve as a single-phased phosphor that can be pumped with near-UV or UV light-emitting diodes. Copyright © 2013 John Wiley & Sons, Ltd.

  10. Observation of energy transfer phenomenon via up and down conversion in Eu3+ ions for BaMoO4:Er3+-Eu3+ nanophosphor

    NASA Astrophysics Data System (ADS)

    Soni, Abhishek Kumar; Ningthoujam, Raghumani Singh

    2018-04-01

    The Er3+-Eu3+ codoped BaMoO4 nanophosphor has been synthesized by using urea hydrolysis in ethylene glycol medium. The tetragonal phase formation of the codoped nanophosphor has been confirmed by the X-ray diffraction analysis. The up and down conversion emission spectra have been recorded via 980 and 270 nm excitation, respectively. The Eu3+ emission arising in the prepared Er3+-Eu3+ codoped BaMoO4 nanophosphor is basically due to the efficient energy transfer process. The energy level diagram has been sketched to show the energy transfer phenomenon in the Eu3+ ion from charge transfer band (host lattice absorption) and excited level of the Er3+ ion (multiphoton absorption). The values of colour co-ordinates suggest that materials can produce the red to yellow. The developed nanophosphor could be useful as an effective up and down converting optical material and lighting device applications.

  11. CW and femtosecond operation of a diode-pumped Yb:BaY(2)F(8) laser.

    PubMed

    Galzerano, G; Coluccelli, N; Gatti, D; Di Lieto, A; Tonelli, M; Laporta, P

    2010-03-15

    We report for the first time on laser action of a diode-pumped Yb:BaY(2)F(8) crystal. Both CW and femtosecond operations have been demonstrated at room-temperature conditions. A maximum output power of 0.56 W, a slope efficiency of 34%, and a tunability range from 1013 to 1067 nm have been obtained in CW regime. Transform-limited pulse trains with a minimum duration of 275 fs, an average power of 40 mW, and a repetition rate of 83 MHz have been achieved in a passive mode-locked regime using a semiconductor saturable absorber mirror.

  12. Enhanced phosphorescence in N contained Ba 2SiO 4:Eu 2+ for X-ray and cathode ray tubes

    NASA Astrophysics Data System (ADS)

    Wang, Meiyuan; Zhang, Xia; Hao, Zhendong; Ren, Xinguang; Luo, Yongshi; Wang, Xiaojun; Zhang, Jiahua

    2010-07-01

    A bluish-green color long-lasting phosphorescent phosphor of N contained Ba 2SiO 4:Eu 2+ for X-ray and cathode ray tubes are prepared with the chemical component formula Ba 2SiO 4:0.01Eu 2+ - xSi 3N 4 - 2BaCO 3 ( x = 0.1 to 1.0) by the conventional high-temperature solid-state method. The phosphorescence and fluorescence properties as a function of Si 3N 4 content and temperature are investigated. The emission spectra show a single broad band peaking at 505 nm, which are ascribed to the 4f 65d 1 → 4f 7 transition of Eu 2+. Thermoluminescence (TL) glow-curves show that Ba 2SiO 4:0.01Eu 2+ without N holds a high-temperature peak at 417 K. With increasing the content of Si 3N 4, the phosphorescence grows super-linearly and some new TL peaks appear at low temperatures of about 400, 355, 365, and 335 K. These peaks are ascribed to the formation of new traps related to N substitution for O.

  13. A novel greenish yellow-orange red Ba3Y4O9:Bi(3+),Eu(3+) phosphor with efficient energy transfer for UV-LEDs.

    PubMed

    Li, Kai; Lian, Hongzhou; Shang, Mengmeng; Lin, Jun

    2015-12-21

    A series of novel color-tunable Ba3Y4O9:Bi(3+),Eu(3+) phosphors were prepared for the first time via the high-temperature solid-state reaction route. The effect of Bi(3+) concentration on the emission intensity of Ba3Y4O9:Bi(3+) was investigated. The emission spectra of the Ba3Y4O9:Bi(3+),Eu(3+) phosphors present both a greenish yellow band of Bi(3+) emission centered at 523 nm, and many characteristic emission lines of Eu(3+), derived from the allowed (3)P1-(1)S0 transition of the Bi(3+) ion and the (5)D0-(7)FJ transition of the Eu(3+) ion, respectively. The energy transfer phenomenon from Bi(3+) to Eu(3+) ions is observed under UV excitation in Bi(3+), Eu(3+) co-doped Ba3Y4O9 phosphors, and their transfer mechanism is demonstrated to be a resonant type via dipole-quadrupole interaction. The critical distance between Bi(3+) and Eu(3+) for the energy transfer effect was calculated via the concentration quenching and spectral overlap methods. Results show that color tuning from greenish yellow to orange red can be realized by adjusting the mole ratio of Bi(3+) and Eu(3+) concentrations based on the principle of energy transfer. Moreover, temperature-dependent PL properties, CIE chromaticity coordinates and quantum yields of Ba3Y4O9:Bi(3+),Eu(3+) phosphors were also supplied. It is illustrated that the as-prepared Ba3Y4O9:Bi(3+),Eu(3+) phosphors can be potential candidates for color-tunable phosphors applied in UV-pumped LEDs.

  14. Structural, electronic, mechanical and magnetic properties of rare earth nitrides REN (RE= Pm, Eu and Yb)

    NASA Astrophysics Data System (ADS)

    Murugan, A.; Rajeswarapalanichamy, R.; Santhosh, M.; Iyakutti, K.

    2015-07-01

    The structural, electronic and mechanical properties of rare earth nitrides REN (RE=Pm, Eu and Yb) are investigated in NaCl and CsCl, and zinc blende structures using first principles calculations based on density functional theory. The calculated lattice parameters are in good agreement with the available results. Among the considered structures, these nitrides are most stable in NaCl structure. A pressure induced structural phase transition from NaCl to CsCl phase is observed in all these nitrides. The electronic structure reveals that these rare earth nitrides are half metallic at normal pressure. These nitrides are found to be covalent and ionic in the stable phase. The computed elastic constants indicate that these nitrides are mechanically stable and elastically anisotropic. Our results confirm that these nitrides are ferromagnetic in nature. A ferromagnetic to non-magnetic phase transition is observed at the pressures of 21.5 GPa and 46.1 GPa in PmN and YbN respectively.

  15. Luminescence and thermal stability tuning in (Ba,Mn)3(Gd,Y)Na(PO4)5F:Eu2+ phosphors via cation-substitution

    NASA Astrophysics Data System (ADS)

    Mei, Juan; Lv, Lemin; Gao, Junsong; Wei, Yi; Feng, Yuxin; Yan, Chunjie; Li, Guogang

    2018-04-01

    In this work, [Y3+-Gd3+] and [Mn2+-Ba2+] substitutions were designed in Ba3GdNa(PO4)5F:Eu2+ system, which were marked as BG1-xYxNPF:Eu2+ and B1-yMyGNPF:Eu2+, respectively. It is found that their luminescence properties and thermal stability could be obviously tuned. For BG1-xYxNPF:Eu2+ series, under 365 nm UV light, the emission spectra exhibited a continuous red-shift from 458 nm (x = 0) to 485 nm (x = 1) with the corresponding luminescence varying from blue light to cyan light. For B1-yMyGNPF:Eu2+ series, it was observed the coexistence of blue-green and enhanced red emission of Eu2+ and the appearance of Eu3+ emission when Mn2+ partly substituted Ba2+, resulting in a final white emission. In addition, the thermal stabilities of B1-yMyGNPF:Eu2+ were obviously improved with Mn2+ doping. The corresponding luminescence and thermal stability tuning mechanisms were investigated.

  16. New observations on the pressure dependence of luminescence from Eu2+-doped MF2 (M = Ca, Sr, Ba) fluorides.

    PubMed

    Su, Fu Hai; Chen, Wei; Ding, Kun; Li, Guo Hua

    2008-05-29

    The luminescence from Eu(2+) ions in MF2 (M = Ca, Sr, Ba) fluorides has been investigated under the pressure range of 0-8 GPa. The emission band originating from the 4f(6)5d(1) --> 4f(7) transition of Eu(2+) ions in CaF2 and SrF2 shows the red-shift as increasing pressure with pressure coefficients of -17 meV/GPa for CaF2 and -18 meV/GPa for SrF2. At atmospheric pressure, the emission spectrum of BaF2:Eu(2+) comprises two peaks at 2.20 and 2.75 eV from the impurity trapped exciton (ITE) and the self-trapped exciton (STE), respectively. As the pressure is increased, both emission peaks shift to higher energies, and the shifting rate is slowed by the phase transition from the cubic to orthorhombic phase at 4 GPa. Due to the phase transition at 4-5 GPa pressure, the ITE emission disappears gradually, and the STE emission is gradually replaced by the 4f(6)5d(1) --> 4f(7) transition of Eu(2+). Above 5 GPa, the pressure behavior of the 4f(6)5d(1) --> 4f(7) transition of Eu(2+) in BaF2:Eu(2+) is the same as the normal emission of Eu(2+) in CaF2 and SrF2 phosphors.

  17. NaLa(MoO{sub 4}){sub 2}: RE{sup 3+} (RE{sup 3+} = Eu{sup 3+}, Sm{sup 3+}, Er{sup 3+}/Yb{sup 3+}) microspheres: the synthesis and optical properties

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Gao, Zhiyi; Wang, Zhiying; Fu, Linlin

    The strong green upconversion (UC) emission were observed in various Er{sup 3+}, Yb{sup 3+} co-doped NaLa(MoO{sub 4}){sub 2} samples synthesized via a hydrothermal route. The UC intensity depends on the dopant concentration, and the optimal UC emission was obtained in NaLa(MoO{sub 4}){sub 2}: 0.02Er{sup 3+}/0.10 Yb{sup 3+}. - Highlights: • The NaLa(MoO{sub 4}){sub 2} microspheres doped with Eu{sup 3+}, Sm{sup 3+} and Er{sup 3+}/Yb{sup 3+} were synthesized by a hydrothermal method. • The effects of the EDTA in the initial solution crystal phase and morphology were studied. • The down-conversion luminescence properties of NaLa(MoO{sub 4}){sub 2}: RE{sup 3+} (RE{sup 3+}more » = Eu{sup 3+}, Sm{sup 3+}) were investigated. • The UC luminescence properties and mechanism of Er{sup 3+}/Yb{sup 3+} co-doped NaLa(MoO{sub 4}){sub 2} was discussed. - Abstract: NaLa(MoO{sub 4}){sub 2}: RE{sup 3+} (RE{sup 3+} = Eu{sup 3+}, Sm{sup 3+}) microspheres have been synthesized at 180 °C via a facile EDTA-mediated hydrothermal route. X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), photoluminescence (PL) spectra were employed to characterize the samples. It was found that the amount of EDTA in the initial solution was responsible for crystal phase and shape determination. The effect of Eu{sup 3+} and Sm{sup 3+} doping concentrations on the luminescent intensity was also investigated in details. Furthermore, the up-conversion (UC) emissions have been observed in a series of Er{sup 3+}/Yb{sup 3+} co-doped NaLa(MoO{sub 4}){sub 2} samples. Concentration dependent studies revealed that the optimal composition was realized for a 2% Er{sup 3+} and 10% Yb{sup 3+}-doping concentration.« less

  18. Correlation of Structure, Tunable Colors, and Lifetimes of (Sr, Ca, Ba)Al2O4:Eu2+, Dy3+ Phosphors

    PubMed Central

    Xie, Qidi; Li, Bowen; He, Xin; Zhang, Mei; Chen, Yan; Zeng, Qingguang

    2017-01-01

    (Sr, Ca, Ba)Al2O4:Eu2+, Dy3+ phosphors were prepared via a high temperature solid-state reaction method. The correlation of phase structure, optical properties and lifetimes of the phosphors are investigated in this work. For the (Sr, Ca)Al2O4:Eu2+, Dy3+ phosphors, the different phase formation from monoclinic SrAl2O4 phase to hexagonal SrAl2O4 phase to monoclinic CaAl2O4 phase was observed when the Ca content increased. The emission color of SrAl2O4:Eu2+, Dy3+ phosphors varied from green to blue. For the (Sr, Ba)Al2O4:Eu2+, Dy3+ phosphors, different phase formation from the monoclinic SrAl2O4 phase to the hexagonal BaAl2O4 phase was observed, along with a shift of emission wavelength from 520 nm to 500 nm. More interestingly, the decay time of SrAl2O4:Eu2+, Dy3+ changed due to the different phase formations. Lifetime can be dramatically shortened by the substitution of Sr2+ with Ba2+ cations, resulting in improving the performance of the alternating current light emitting diode (AC-LED). Finally, intense LEDs are successfully obtained by combining these phosphors with Ga(In)N near UV chips. PMID:29057839

  19. Color-tunable photoluminescence and energy transfer properties of single-phase Ba{sub 10}(PO{sub 4}){sub 6}O:Eu{sup 2+}, Mn{sup 2+} phosphors

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Guo, Qingfeng; Liao, Libing, E-mail: clayl@cugb.edu.cn; Mei, Lefu, E-mail: mlf@cugb.edu.cn

    2015-12-15

    Single-phase Ba{sub 10−x−y}(PO{sub 4}){sub 6}O:xEu{sup 2+},yMn{sup 2+} samples with apatite structure have been synthesized via a solid-state reaction method. The phase structure, luminescence properties, lifetime, PL thermal stability, as well as fluorescence decay curves of the samples were investigated. Effective energy transfer occurs from Eu{sup 2+} to Mn{sup 2+} in Ba{sub 10}(PO{sub 4}){sub 6}O and a possible mechanism of the energy-transfer from Eu{sup 2+} to Mn{sup 2+} is proposed. The critical distances R{sub c} was calculated by concentration quenching and turned out to be about 0.817 nm (x{sub c}=0.21). The CIE and thermally stable luminescence behaviors of Ba{sub 9.94}(PO{sub 4}){submore » 6}O:0.06Eu{sup 2+} phosphor were also studied in detail. All the results indicate that Ba{sub 10−x−y}(PO{sub 4}){sub 6}O:xEu{sup 2+}, yMn{sup 2+} phosphors have potential applications as near UV-convertible phosphors for white light-emitting diodes. - Graphical abstract: Crystal structure and luminescence property of Ba{sub 10−x−y}(PO{sub 4}){sub 6}O:xEu{sup 2+},yMn{sup 2+} have been discussed. - Highlights: • Ba{sub 10−x−y}(PO{sub 4}){sub 6}O:xEu{sup 2+},yMn{sup 2+} was firstly reported. • Ba{sub 9.94}(PO{sub 4}){sub 6}O:0.06Eu{sup 2+} exhibits high thermal quenching resistance. • The energy transfer between Eu{sup 2+} and Mn{sup 2+} was investigated.« less

  20. Bonding in gold-rare earth [Au2M] (M = Eu, Yb, Lu) ions. A strong covalent gold-lanthanide bond

    NASA Astrophysics Data System (ADS)

    Páez-Hernández, Dayán; Muñoz-Castro, Alvaro; Arratia-Perez, Ramiro

    2017-09-01

    The electronic structure and bonding nature of a series of intermetallic gold-lanthanide [Au2Ln] molecules, where Ln = Eu, Yb, Lu is predicted via the DFT and CASSCF/CASPT2 calculations. The 2c-2e bond model shows a good description of the intermetallic bonding which have a large covalent component with important contribution from bonding interaction between the 6s-Au and the 6s-Ln shell of orbitals.

  1. Synthesis, structural and optical properties of BaMoO{sub 4}:Eu{sup 3+} shuttle like phosphors

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Krishna Bharat, L.; Lee, Soo Hyun; Yu, Jae Su, E-mail: jsyu@khu.ac.kr

    2014-05-01

    Graphical abstract: - Highlights: • BaMoO{sub 4}:Eu{sup 3+} phosphors were synthesized by a facile synthesis route. • PL and CL spectra showed dominant emissions due to ({sup 5}D{sub 0} → {sup 7}F{sub 2}) hypersensitive transitions. • The excitation wavelengths in the UV-B region make BaMoO{sub 4}:Eu{sup 3+} phosphors as a good candidate in the red region for the development of UV-based white LEDs. • PL and CL spectra showed similar CIE values close to the commercially available Y{sub 2}O{sub 3}:Eu{sup 3+} phosphors. - Abstract: Eu{sup 3+} ions doped BaMoO{sub 4} phosphor samples were synthesized by a facile synthesis process. Themore » tetragonal phase of the host lattice was substantiated by the X-ray diffraction patterns. The morphological studies were carried out by taking the scanning electron microscope and transmission electron microscope images and confirmed the formation of shuttle like particles with perpendicular protrusions in the middle of the particle. The single crystalline nature of the phosphors was confirmed by the selected area electron diffraction pattern. The photoluminescence (PL) properties of the Eu{sup 3+} ions doped samples revealed good emission with a high asymmetry ratio when excited with ultraviolet B wavelengths (between 280 and 315 nm). The cathodoluminescence (CL) spectra showed similar results to the PL spectra. The calculated CIE values based on the PL and CL spectra were almost similar and confirmed the rich red emission.« less

  2. Host composition dependent tunable multicolor emission in the single-phase Ba2(Ln(1-z)Tb(z))(BO3)2Cl:Eu phosphors.

    PubMed

    Xia, Zhiguo; Zhuang, Jiaqing; Meijerink, Andries; Jing, Xiping

    2013-05-14

    A new strategy based on the host composition design has been adopted to obtain efficient color-tunable emission from Ba2Ln(0.97-z)Tb(z)(BO3)2Cl:0.03Eu (Ln = Y, Gd and Lu, z = 0-0.97) phosphors. This study reveals that the single-phase Ba2Ln(1-z)Tb(z)(BO3)2Cl compounds can be applied to use allowed Eu(2+) absorption transitions to sensitize Eu(3+) emission via the energy transfer Eu(2+) → (Tb(3+))n → Eu(3+). The powder X-ray diffraction (XRD) and Rietveld refinement analysis shows single-phase Ba2Ln(1-z)Tb(z)(BO3)2Cl. As-prepared Ba2Ln(0.97-z)Tb(z)(BO3)2Cl:0.03Eu phosphors show intense green, yellow, orange and red emission under 377 nm near ultraviolet (n-UV) excitation due to a variation in the relative intensities of the Eu(2+), Tb(3+) and Eu(3+) emission depending on the Tb content (z) in the host composition, allowing color tuning. The variation in emission color is explained by energy transfer and has been investigated by photoluminescence and lifetime measurements and is further characterized by the Commission Internationale de l'éclairage (CIE) chromaticity indexes. The quantum efficiencies of the phosphors are high, up to 74%, and show good thermal stabilities up to 150 °C. This investigation demonstrates the possibility to sensitize Eu(3+) line emission by Eu(2+)via energy migration over Tb(3+) resulting in efficient color tunable phosphors which are promising for use in solid-state white light-emitting diodes (w-LEDs).

  3. Snynthesis and magnetization of BaLn2O4 (Ln = lanthanide)

    NASA Astrophysics Data System (ADS)

    Lundberg, Matthew

    The BaLn2O4 family has been synthesized successfully as single crystals by the flux-growth method. The phases crystallize in the CaV2O4 structure prototype in space group Pnma (# 62). The structure has been studied using single-crystal x-ray diffraction, and stoichiometry confirmed with EDS, and the unit cell parameters and atomic positions have been determined for the whole lanthanide series (with the exception of the Lu compound). The effects of the lanthanide ionic radius on the atomic positions in the unit cell has been studied in terms of fractional atomic coordinates, bond lengths and angles, and bond valence sums. Magnetic measurements have been performed on the series with the exception of the La, Eu, and Lu members in the form of susceptibility versus temperature. The crystals all show signs of geometric antiferromagnetic frustration with the Neel temperatures significantly below the temperature predicted by the Weiss constant. Additionally some members of the family, namely BaCe2O4, BaNd2O4, BaPr 2O4, BaSm2O4, BaTb2O 4, and BaYb2O4 show significant crystal field splitting, that causes deviation from Currie-Weiss behavior.

  4. White up-conversion emission in Ho3+/Tm3+/Yb3+ tri-doped glass ceramics embedding BaF2 nanocrystals

    NASA Astrophysics Data System (ADS)

    Li, Chenxia; Xu, Shiqing; Ye, Rengguang; Deng, Degang; Hua, Youjie; Zhao, Shilong; Zhuang, Songlin

    2011-04-01

    Ho3+/Tm3+/Yb3+ tri-doped glass ceramics with white light emitting have been developed and demonstrated. Pumped by 980 nm laser diode (LD), intensive red, green and blue up-conversions (UC) were obtained. The green emission is assigned to Ho3+ ion and the blue emission is assigned to Tm3+ ion, whereas the red emission is the combination contribution of the Ho3+ and Tm3+ ions. The RGB intensities could be adjusted by tuning the rare-earth ion concentration and pump power intensity. Thus, multicolor of the luminescence, including perfect white light with CIE-X=0.329 and CIE-Y=0.342 in the 1931 CIE chromaticity diagram can be obtained in 0.15 Ho3+/0.2Tm3+/3Yb3+ tri-doped glass ceramics embedding BaF2 nanocrystals pumped by a single infrared laser diode source of 980 nm at 500 mW. The up-conversion luminescence mechanism of Yb3+ sensitize Ho3+ and Tm3+ ions and the energy transfer from Ho3+ to Tm3+ in oxy-fluoride silicate glass ceramics were analyzed.

  5. Co-Dopant Influence on the Persistent Luminescence of BaAl2O4:Eu2+,R3+

    NASA Astrophysics Data System (ADS)

    Rodrigues, Lucas C. V.; Hölsä, Jorma; Carvalho, José M.; Pedroso, Cássio C. S.; Lastusaari, Mika; Felinto, Maria C. F. C.; Watanabe, Shigeo; Brito, Hermi F.

    2014-04-01

    The R3+ (rare earth) co-dopants may have a surprisingly important role in persistent luminescence - enhancement of up to 1-3 orders of magnitude may be obtained in the performance of these phosphor materials - depending strongly on the R3+ ion, of course. In this work, the effects of the R3+ co-dopants in the BaAl2O4:Eu2+,R3+ materials were studied using mainly thermoluminescence (TL) and synchrotron radiation XANES methods. In BaAl2O4, the conventional and persistent luminescence both arise from the 4f7→4f65d1 transition of Eu2+, yielding blue-green emission color. The former, in the presence of humidity, turns to more bluish because of creation of an additional Eu2+ luminescence centre which is not, however, visible in persistent luminescence. The trap structure in the non-co-doped BaAl2O4:Eu2+ is rather complex with 4-5 TL bands above room temperature. With R3+ co-doping, this basic structure is modified though no drastic change can be observed. This underlines the fact that even very small changes in the trap depths can produce significant modifications in the persistent luminescence efficiency. It should be remembered that basically the persistent luminescence performance is controlled by the Boltzmann population law depending exponentially on both the temperature and trap depth. Some mechanisms for persistent luminescence have suggested the presence of either divalent R2+ or tetravalent RIV during the charging of the Eu2+ doped materials. The present XANES measurements on BaAl2O4:Eu2+,R3+ confirmed the presence of only the trivalent form of the R3+ co-dopants excluding both of these pathways. It must thus be concluded, that the energy is stored in intrinsic and extrinsic defects created by the synthesis conditions and charge compensation due to R3+ co-doping. Even though the effect of the R3+ co-dopants was carefully exploited and characterized, the differences in the effect of different R3+ ions with very similar chemical and spectroscopic properties could

  6. Eu2+-doped Ba2GaB4O9Cl blue-emitting phosphor with high color purity for near-UV-pumped white light-emitting diodes

    NASA Astrophysics Data System (ADS)

    Gao, Zhiwen; Deng, Huajuan; Xue, Na; Jeong, Jung Hyun; Yu, Ruijin

    2018-01-01

    Eu2+-doped borate fluoride Ba2GaB4O9Cl was synthesized by the conventional high-temperature solid-state reaction. The crystal structure and luminescence properties of the phosphors, as well as their thermal luminescence quenching capabilities and CIE chromaticity coordinates were systematically investigated. Under the excitation at 340 nm, the phosphor exhibited an asymmetric broad-band blue emission with a peak at 445 nm, which is ascribed to the 4f-5d transition of Eu2+. It was further proved that energy transfer among the nearest neighbor ions is the major mechanism for concentration quenching of Eu2+ in Ba2-xGaB4O9Cl:xEu2+ phosphors. The luminescence quenching temperature is 432 K. The CIE color coordinates are very close to those of BaMgAl10O17:Eu2+ (BAM). All the properties indicated that the blue-emitting Ba2GaB4O9Cl:Eu2+ phosphor has potential application in white LEDs.

  7. White light emission and effect of annealing on the Ho{sup 3+}–Yb{sup 3+} codoped BaCa{sub 2}Al{sub 8}O{sub 15} phosphor

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Kumari, Astha; Rai, Vineet Kumar, E-mail: vineetkrrai@yahoo.co.in

    Graphical abstract: The upconversion emission spectra of the Ho{sup 3+}/Yb{sup 3+} doped/codoped BaCa{sub 2}Al{sub 8}O{sub 15} phosphors with different doping concentrations of Ho{sup 3+}/Yb{sup 3+} ions along with UC emission spectrum of the white light emitting phosphor annealed at 800 °C. - Highlights: • BaCa{sub 2}Al{sub 8}O{sub 15} phosphors codoped with Ho{sup 3+}–Yb{sup 3+} have been prepared by combustion method. • Phosphor annealed at 800 °C, illuminate an intense white light upon NIR excitation. • The sample annealed at higher temperatures emits in the pure green region. • The colour emitted persists in the white region even at high pumpmore » power density. • Developed phosphor is suitable for making upconverters and WLEDs. - Abstract: The BaCa{sub 2}Al{sub 8}O{sub 15} (BCAO) phosphors codoped with suitable Ho{sup 3+}–Yb{sup 3+} dopant concentration prepared by combustion method illuminate an intense white light upon near infrared diode laser excitation. The structural analysis of the phosphors and the detection of impurity contents have been performed by using the X-Ray Diffraction, FESEM and FTIR analysis. The purity of white light emitted from the sample has been confirmed by the CIE chromaticity diagram. Also, the white light emitted from the sample persists with the variation of pump power density. The phosphors emit upconversion (UC) emission bands in the blue, green and red region (three primary colours required for white light emission) along with one more band in the near infrared region of the electromagnetic spectrum. On annealing the white light emitting sample at higher temperatures, the sample starts to emit green colour and also the intensity of green and red UC emission bands get enhanced largely.« less

  8. Magnetic properties of the doubly ordered perovskite NaLnCoWO6 (Ln = Y, La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Yb) family

    NASA Astrophysics Data System (ADS)

    Zuo, Peng; Klein, Holger; Darie, Céline; Colin, Claire V.

    2018-07-01

    The focus of this study is on the magnetic properties of the very recently synthesized doubly ordered perovskite family NaLnCoWO6 (Ln = Y, La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, and Yb). Magnetic characterizations were performed by magnetic susceptibility vs. temperature, isothermal magnetization and heat capacity measurements. All these compounds have been determined as antiferromagnets with Néel temperatures from 4 K to 13.1 K. When the lanthanide is magnetic, additional transitions were observed below the Néel temperature which are attributed to the polarization of the magnetic Ln3+ sublattice by the ordered Co2+ one. Taking into account the magnetic ordering found in this study and the polar structure in the nine compounds NaLnCoWO6 (Ln = Y, Sm, Eu, Gd, Tb, Dy, Ho, Er, and Yb) reported before, these compounds can be classified as new Type I multiferroics.

  9. Effect of structural defects on the magnetic properties of the EuBaCo1.90O5.36 single crystal

    NASA Astrophysics Data System (ADS)

    Arbuzova, T. I.; Naumov, S. V.; Telegin, S. V.

    2018-01-01

    The effect of structural defects in cobalt and oxygen sublattices with the constant average oxidation level 3+ of all cobalt ions on the magnetic properties of the EuBaCo1.90O5.36 single crystal has been studied. The magnetic properties of the single crystal and the polycrystalline sample of the corresponding composition are compared in the range T = 200-650 K. The results show that the cobalt-deficient EuBaCo2- x O5.5-δ samples demonstrate a three-dimensional XY ferromagnetic ordering of magnetic sublattices. The values of the effective magnetic moment at T > 480 K indicate the existence of the IS and HS states of Co3+ ions. The large difference of values of μeff of the EuBaCo1.90O5.36 single crystal and polycrystal can be due to that the magnetic ion spins lie in plane ab. The magnetic field directed along plane ab substantially influences the magnetic ordering at T < 300 K.

  10. Oxygen-vacancy-mediated dielectric property in perovskite Eu0.5Ba0.5TiO3-δ epitaxial thin films

    NASA Astrophysics Data System (ADS)

    Li, Weiwei; Gu, Junxing; He, Qian; Zhang, Kelvin H. L.; Wang, Chunchang; Jin, Kuijuan; Wang, Yongqiang; Acosta, Matias; Wang, Haiyan; Borisevich, Albina Y.; MacManus-Driscoll, Judith L.; Yang, Hao

    2018-04-01

    Dielectric relaxation in ABO3 perovskite oxides can result from many different charge carrier-related phenomena. Despite a strong understanding of dielectric relaxations, a detailed investigation of the relationship between the content of oxygen vacancies (VO) and dielectric relaxation has not been performed in perovskite oxide films. In this work, we report a systematic investigation of the influence of the VO concentration on the dielectric relaxation of Eu0.5Ba0.5TiO3-δ epitaxial thin films. Nuclear resonance backscattering spectrometry was used to directly measure the oxygen concentration in Eu0.5Ba0.5TiO3-δ films. We found that dipolar defects created by VO interact with the off-centered Ti ions, which results in the dielectric relaxation in Eu0.5Ba0.5TiO3-δ films. Activation energy gradually increases with the increasing content of VO. The present work significantly extends our understanding of relaxation properties in oxide films.

  11. Effect of europium ion concentration on the structural and photoluminescence properties of novel Li2BaZrO4: Eu3+ nanocrystals

    NASA Astrophysics Data System (ADS)

    Ahemen, I.; Dejene, F. B.; Kroon, R. E.; Swart, H. C.

    2017-12-01

    This work reports the influence of Eu3+ ion concentration on the structure and photoluminescence properties of Li2BaZrO4 nanocrystals including its intrinsic quantum efficiency (IQE). Chemical bath method was employed in the synthesis procedure. X-ray diffraction results showed tetragonal phase for Eu3+ ion concentration in the range 1 and 7 mol% and cubic phase at 8 mol%. The presence of barium oxide (BaO) was confirmed from selected area electron diffraction (SAED). The excitation spectra for these phosphors consisted of broad charge transfer (CT) bands due to the combination of Zr4+ - O2- and Eu3+-O2- charge transfer states. Superimposed on the CT band were direct excitation levels of Eu3+ and Ba2+ ions, in the range 320-450 nm. At high Eu3+ ions concentrations, the intensities of CT bands decreased because some of the ions were coordinated with Ba2+ ions. Photoluminescence emissions for all the doped samples at room temperature appeared to be entirely from intraconfigurational Eu3+ emissions and depended both on the site symmetry as well as the ion concentration. The quadrupole-quadrupole multipolar process was found to be solely responsible for the luminescence quenching. The intensity parameters (Ω2 ,Ω4), asymmetry ratio, R0 and the average decay lifetime of the nanocrystals showed dependence on concentration. High internal quantum efficiency (IQE) values were obtained at low Eu3+ ion concentrations, but efficiency decreased with increasing ion concentration. The CIE coordinates values were comparable to existing red phosphors and in combination with the high IQE make this phosphor a good candidate for red light emitting applications.

  12. Luminescence of BaBrI and SrBrI single crystals doped with Eu2+

    NASA Astrophysics Data System (ADS)

    Shalaev, A. A.; Shendrik, R.; Myasnikova, A. S.; Bogdanov, A.; Rusakov, A.; Vasilkovskyi, A.

    2018-05-01

    The crystal growth procedure and luminescence properties of pure and Eu2+-doped BaBrI and SrBrI crystals are reported. Emission and excitation spectra were recorded under ultraviolet and vacuum ultraviolet excitations. The energy of the first Eu2+ 4f-5d transition and SrBrI band gap are obtained. The electronic structure calculations were performed within GW approximation as implemented in the Vienna Ab Initio Simulation Package. The energy between lowest Eu2+ 5d state and the bottom of conduction band are found based on luminescence quenching parameters. The vacuum referred binding energy diagram of lanthanide levels was constructed using the chemical shift model.

  13. Structure, luminescence and thermal quenching properties of Eu doped Sr{sub 2−x}Ba{sub x}Si{sub 5}N{sub 8} red phosphors

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Liu, Y.H.; Chen, L.; Zhou, X.F.

    Eu{sup 2+} doped Sr{sub 2-x}Ba{sub x}Si{sub 5}N{sub 8} phosphors were synthesized at 1610 ℃ for 4 h via the solid-state reaction method. The XRD results confirm that the complete solid solutions are formed. With the increase of x, the emission spectra show an obvious blue-shift from 610 nm to 585 nm under the excitation of 460 nm. The color tone can be tuned from yellow to red. The corresponding mechanism for the blue-shift of peak-wavelength is studied in detail. The results of decomposed Gaussian spectra and fluorescence lifetime show that the local coordination structure surrounding activator ions changes with increasingmore » x value. It is found that the probability of Eu occupying Sr1 and Sr2 site is dependent on Ba/Sr ratio. The variation of thermal quenching properties and the corresponding mechanism is discussed in detail. The results indicate that Eu{sup 2+} doped Sr{sub 2-x}Ba{sub x}Si{sub 5}N{sub 8} is a promising orange red-emitting phosphor for near UV or blue light-pumped white light-emitting-diodes (wLEDs). - Graphical abstract: Eu{sup 2+} doped Sr{sub 2-x}Ba{sub x}Si{sub 5}N{sub 8} solid solutions were prepared by the solid-state reaction method. The structure, luminescence and thermal quenching properties with varying Ba/Sr ratio were investigated in detail. - Highlights: • The stucture and luminescence properties of Eu doped Sr{sub 2-x}Ba{sub x}Si{sub 5}N{sub 8} phosphors were investigated. • The samples with the intermediate compositions(x=1.0,1.5) show better stability than the end members of both Sr{sub 2}Si{sub 5}N{sub 8}:Eu{sup 2+} and Ba{sub 2}Si{sub 5}N{sub 8}:Eu{sup 2+}. • The possible mechanism for the improvement of thermal quenching properties was proposed.« less

  14. Facile morphology-controlled synthesis and luminescence properties of BaMoO4:Eu3+ microparticles and micro-rods obtained by a molten-salt reaction route.

    PubMed

    Xia, Zhiguo; Jin, Shuai; Sun, Jiayue; Du, Haiyan; Du, Peng; Liao, Libing

    2011-11-01

    This work focuses on the synthesis of morphology-controlled BaMoO4:Eu3+ micro-crystals such as microparticles and micro-rods using a facile molten salt method, and their morphology, structural characterization, and luminescent properties were comparatively investigated by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and fluorescence spectra. The molten salt method synthesized products from a reaction of BaMoO4 precursor obtained by a co-precipitation method of BaCl2 and Na2MoO4 with an eutectic salt mixture of NaCl-KCl at 700 degrees C. Detailed studies revealed that the formation of the different morphologies of the micro-crystals was strongly dependent on the weight ratio of the salt (NaCl-KCl) to the BaMoO4 precursor, and the formation mechanism of the products in the present molten salt system was also investigated. Based on the investigations of the photoluminescence properties, the samples with different morphologies prepared by the molten salt method had the strongest red emission at 615 nm, corresponding to the Eu3+ 5D0-7F2 transition in the BaMoO4 host lattice, and the emission intensity of BaMoO4:Eu3+ microparticles was stronger than that of BaMoO4:Eu3+ micro-rods.

  15. Single crystal synthesis and magnetism of the Ba Ln 2O 4 family ( Ln = lanthanide)

    DOE PAGES

    Besara, Tiglet; Lundberg, Matthew S.; Sun, Jifeng; ...

    2014-05-27

    The series of compounds in the Ba Ln 2O 4 family (Ln = La–Lu, Y) has been synthesized for the first time in single crystalline form, using a molten metal flux. The series crystallizes in the CaV 2O 4 structure type with primitive orthorhombic symmetry (space group Pnma, #62), and a complete structural study of atomic positions, bonds, angles, and distortions across the lanthanide series is presented. With the exception of the Y, La, Eu, and Lu members, magnetic susceptibility measurements were performed between 2 K and 300 K. BaCe 2O 4 and BaYb 2O 4 display large crystal fieldsmore » effects and suppression of magnetic ordering. As a result, all compounds show signs of magnetic frustration due to the trigonal arrangements of the trivalent lanthanide cations in the structure.« less

  16. Explaining the Ba, Y, Sr, and Eu abundance scatter in metal-poor halo stars: constraints to the r-process

    NASA Astrophysics Data System (ADS)

    Cescutti, G.; Chiappini, C.

    2014-05-01

    Context. Thanks to the heroic observational campaigns carried out in recent years we now have large samples of metal-poor stars for which measurements of detailed abundances exist. In particular, large samples of stars with metallicities -5 < [Fe/H] <-1 and measured abundances of Sr, Ba, Y, and Eu are now available. These data hold important clues on the nature of the contribution of the first stellar generations to the enrichment of our Galaxy. Aims: We aim to explain the scatter in Sr, Ba, Y, and Eu abundance ratio diagrams unveiled by the metal-poor halo stars. Methods: We computed inhomogeneous chemical evolution models for the Galactic halo assuming different scenarios for the r-process site: the electron-capture (EC) supernovae and the magnetorotationally driven (MRD) supernovae scenarios. We also considered models with and without the contribution of fast-rotating massive stars (spinstars) to an early enrichment by the s-process. A detailed comparison with the now large sample of stars with measured abundances of Sr, Ba, Y, Eu, and Fe is provided (both in terms of scatter plots and number distributions for several abundance ratios). Results: The scatter observed in these abundance ratios of the very metal-poor stars (with [Fe/H] <-2.5) can be explained by combining the s-process production in spinstars, and the r-process contribution coming from massive stars. For the r-process we have developed models for both the EC and the MRD scenarios that match the observations. Conclusions: With the present observational and theoretical constraints we cannot distinguish between the EC and the MRD scenarios in the Galactic halo. Independently of the r-process scenarios adopted, the production of elements by an s-process in spinstars is needed to reproduce the spread in abundances of the light neutron capture elements (Sr and Y) over heavy neutron capture elements (Ba and Eu). We provide a way to test our suggestions by means of the distribution of the Ba isotopic

  17. Ho3+/Yb3+ co-doped TeO2-BaF2-Y2O3 glasses for ∼1.2 μm laser applications

    NASA Astrophysics Data System (ADS)

    Wang, Shunbin; Li, Chengzhi; Yao, Chuanfei; Jia, Shijie; Jia, Zhixu; Qin, Guanshi; Qin, Weiping

    2017-02-01

    Intense ∼1.2 μm fluorescence is observed in Ho3+/Yb3+ co-doped TeO2-BaF2-Y2O3 glasses under 915 nm laser diode excitation. The 1.2 μm emission can be ascribed to the transition 5I6→5I8 of Ho3+. With the introducing of BaF2, the content of OH in the glasses drops markedly, and the 1.2 μm emission intensity increases gradually as increasing the concentration percentage of BaF2. Furthermore, microstructured fibers based on the TeO2-BaF2-Y2O3 glasses are fabricated by using a rod-in-tube method, and a relative positive gain of ∼9.42 dB at 1175.3 nm is obtained in a 5 cm long fiber.

  18. Eu(2+)-Activated Phase-Pure Oxonitridosilicate Phosphor in a Ba-Si-O-N System via Facile Silicate-Assisted Routes Designed by First-Principles Thermodynamic Simulation.

    PubMed

    Yun, Young Jun; Kim, Jin Kyu; Ju, Ji Young; Choi, Seul Ki; Park, Woon Ik; Jung, Ha-Kyun; Kim, Yongseon; Choi, Sungho

    2016-09-06

    Eu(2+)-activated single phase Ba(2+)-oxonitridosilicate phosphors were prepared under a mild synthetic condition via silicate precursors, and their luminescent properties were investigated. Both the preferred oxonitridosilicate formation as for the available host compounds and thermodynamic stability within the Ba-Si-O-N system were elucidated in detail by the theoretical simulation based on the first-principles density functional theory. Those results can visualize the optimum synthetic conditions for Eu(2+)-activated highly luminescent Ba(2+)-oxonitridosilicates, especially Ba3Si6O12N2, as promising conversion phosphors for white LEDs, including Ba3Si6O9N4 and BaSi2O2N2 phases. To prove the simulated design rule, we synthesized the Ba3Si6O12N2:Eu(2+) phosphor using various silicate precursors, Ba2Si4O10, Ba2Si3O8, and BaSiO3, in a carbothermal reduction ambient and finally succeeded in obtaining a phase of pure highly luminescent oxonitridosilicate phosphor without using any solid-state nitride addition and/or high pressure synthetic procedures. Our study provides useful guidelines for robust synthetic procedures for developing thermally stable rare-earth-ion activated oxonitridosilicate phosphors and an established simulation method that can be effectively applied to other multigas systems.

  19. Influence of MO/MF2 modifiers (M = Ca, Sr, Ba) on spectroscopic properties of Eu3+ ions in germanate and borate glasses

    NASA Astrophysics Data System (ADS)

    Zur, Lidia; Janek, Joanna; Pietrasik, Ewa; Sołtys, Marta; Pisarska, Joanna; Pisarski, Wojciech A.

    2016-11-01

    Series of Eu3+-doped lead-free germanate and borate glasses were synthesized. The MO glass modifiers (M = Ca, Sr or Ba) were partially or totally substituted by MF2 in chemical composition. In contrast to samples modified by CaO/CaF2 or SrO/SrF2, the germanate glass samples containing BaO and/or BaF2 are fully amorphous, while the lead-free borate glasses are fully amorphous, independently from glass modifiers. Effect of glass modifiers on spectroscopic properties of Eu3+ were systematically investigated. For that reason, excitation and emission spectra of Eu3+ ions in examined systems were registered. Based on the emission spectra, ratio of integrated luminescence intensity of the 5D0 → 7F2 transition to that of the 5D0 → 7F1 transition (R factor) was calculated. Moreover, the luminescence decay curves were collected and the luminescence lifetimes of the 5D0 excited state of Eu3+ ions were determined in function of MF2 concentration.

  20. Eu2P7X and Ba2As7X (X = Br, I): Chiral double-Zintl salts containing heptapnictotricyclane clusters

    NASA Astrophysics Data System (ADS)

    Dolyniuk, Juli-Anna; Lee, Shannon; Tran, Nhon; Wang, Jian; Wang, Lin-Lin; Kovnir, Kirill

    2018-07-01

    Chiral double Zintl salts present tunable crystal structures with enhanced structural flexibilities and potential for applications requiring chiral control and enantioselectivity. To accompany the chiral Sr2P7I and Sr2P7Br double Zintl salts reported by us previously, six new chiral Zintl salts of the form Ba2-ySryAs7I (y = 0, 0.23, 2), Eu2P7I, Eu2P7Br, and Eu1.3Ba0.7P7Br have been synthesized and characterized by single crystal X-ray diffraction and SEM-EDS analyses. All new compounds crystallize in the Sohncke space group P213 (No. 198) with variations of P73- (heptaphosphanortricyclane) or As73- (heptaarsanortricyclane) clusters surrounded by alkaline-earth or Eu cations and halogen anions. Band structure calculations predict semiconducting properties for all synthesized compounds. Diffuse reflectance UV-vis spectroscopy indicates that Eu2P7I is a direct bandgap semiconductor with Eg of 1.7 eV.

  1. Facile synthesis and color-tunable properties of BaLuF5:Ce,Tb,Eu(Sm) submicrospheres via a facile ionic liquid/EG two-phase system.

    PubMed

    Song, Yanhua; Li, Yi; Zhao, Tianqi; Wang, Yuexin; Cui, Tingting; Sheng, Ye; Zheng, Keyan; Zhou, Xiuqing; You, Hongpeng; Zou, Haifeng

    2017-02-01

    BaLuF 5 :Ce,Tb,Eu(Sm) submicrospheres were synthesized via an ILs/ethylene glycol(EG) two-phase system. The crystalline phase, size, morphology, and luminescence properties were characterized using powder X-ray diffraction (XRD), field emission-scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), photoluminescence (PL) spectra. The results show that 1-methyl-3-octylimidazolium hexafluorophosphate ([Omim]PF 6 ) was used as fluoride source and capping agent to tune morphology and size of the crystals. The formation mechanism has been supposed. Under the excitation of ultraviolet, the BaLuF 5 :5%Ce 3+ ,5%Tb 3+ , BaLuF 5 :Eu 3+ , and BaLuF 5 :5%Ce 3+ ,5%Sm 3+ exhibit green and red emission, which was derived from Tb 3+ , Eu 3+ , and Sm 3+ emission. When codoping Ce 3+ , Tb 3+ , Sm 3+ or Eu 3+ together, multi-color emission can be realized. Furthermore, this synthetic route may have potential applications for fabricating other lanthanide fluorides. Copyright © 2016 Elsevier Inc. All rights reserved.

  2. Spectral properties and anti-Stokes luminescence of TeO2-BaF2:Ho3+, Ho3+/Yb3+ ceramics and glass excited by 1.9-μm radiation of a Tm:LiYF4 laser

    NASA Astrophysics Data System (ADS)

    Savikin, A. P.; Egorov, A. S.; Budruev, A. V.; Perunin, I. Yu.; Krasheninnikova, O. V.; Grishin, I. A.

    2017-07-01

    We demonstrate the up-conversion of Tm:LiYF4 infrared (IR) laser radiation with 1908-nm wavelength into visible light with a spectral maximum at 650 nm by ceramics with a composition of (100 - x)TeO2- xBaF2 - 1 wt % HoF3- yYbF3, where x = 20, 30, or 40 mol % and y = 0 or 0.5 wt %. The samples of 60TeO2-40BaF2 - 1 wt % HoF3 - 0.5 wt % YbF3 exhibited anti-Stokes luminescence at a threshold radiation power density of 1.0-1.5 W cm-2.

  3. Bifunction in Er{sup 3+}/Yb{sup 3+} co-doped BaTi{sub 2}O{sub 5}–Gd{sub 2}O{sub 3} glasses prepared by aerodynamic levitation method

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Zhang, Minghui; University of Chinese Academy of Sciences, Beijing 100039; Yu, Jianding

    2013-11-15

    Graphical abstract: - Highlights: • Novel BaTi{sub 2}O{sub 5}–Gd{sub 2}O{sub 3} based glasses have been prepared by aerodynamic levitation. • The obtained glasses show high thermal stability with T{sub g} = 763.3 °C. • Er{sup 3+}/Yb{sup 3+} co-doped glasses show strong upconversion based on a two-photon process. • Red emission is stronger than green emissions for EBT by high Yb{sup 3+} concentration. • Magnetic ions are paramagnetic and the distribution is homogeneous in the glasses. - Abstract: Novel Er{sup 3+}/Yb{sup 3+} co-doped BaTi{sub 2}O{sub 5}–Gd{sub 2}O{sub 3} spherical glasses have been fabricated by aerodynamic levitation method. The thermal stability, upconversionmore » luminescence, and magnetic properties of the present glass have been studied. The glasses show high thermal stability with 763.3 °C of the onset temperature of the glass transition. Red and green emissions centered at 671 nm, 548 nm and 535 nm are obtained at 980 nm excitation. The upconversion is based on a two-photon process by energy transfer, excited-state absorption, and energy back transfer. Yb{sup 3+} ions are more than Er{sup 3+} ions in the glass, resulting in efficient energy back transfer from Er{sup 3+} to Yb{sup 3+}. So the red emission is stronger than the green emissions. Magnetization curves indicate that magnetic rare earth ions are paramagnetic and the distribution is homogeneous and random in the glass matrix. Aerodynamic levitation method is an efficient way to prepare glasses with homogeneous rare earth ions.« less

  4. Photoluminescence and cathodoluminescence properties of Eu{sup 3+} ions activated AMoO{sub 4} (A = Mg, Ca, Sr, Ba) phosphors

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Du, Peng; Yu, Jae Su, E-mail: jsyu@khu.ac.kr

    2015-10-15

    Highlights: • Under 393 nm excitation, strong red emission located at 615 nm was observed in all the samples. • The Eu{sup 3+}-activated CaMoO{sub 4} phosphor exhibited the strongest PL properties. • The CIE chromaticity coordinate of Eu{sup 3+}-activated CaMoO{sub 4} phosphor was (0.647,0.352). • The color purity of Eu{sup 3+}-activated CaMoO{sub 4} phosphor was 92.8%. • Strong CL properties were observed in the Eu{sup 3+}-activated CaMoO{sub 4} phosphor. - Abstract: Eu{sup 3+}-activated AMoO{sub 4} (A = Mg, Ca, Sr, Ba) phosphors were synthesized by a solid-state reaction method. Photoluminescence and cathodoluminescence (CL) spectra as well as X-ray diffraction patternsmore » were measured to characterize the fabricated samples. Under 393 nm excitation, strong red emissions located at ∼615 nm corresponding to the {sup 5}D{sub 0} → {sup 7}F{sub 2} transition of Eu{sup 3+} ions were observed in all the samples. Compared with other Eu{sup 3+} ions activated AMoO{sub 4} (A = Mg, Sr, Ba) phosphors, Eu{sup 3+}-activated CaMoO{sub 4} phosphor exhibited the strongest red emission intensity with better Commission Internationale de L’Eclairage chromaticity coordinate and higher color purity. Furthermore, the CL results indicated that the Eu{sup 3+}-activated CaMoO{sub 4} phosphor had excellent luminescence properties.« less

  5. Bluish-green color emitting Ba2Si3O8:Eu2+ ceramic phosphors for white light-emitting diodes.

    PubMed

    Xiao, F; Xue, Y N; Zhang, Q Y

    2009-10-15

    This paper reports on the structural and optical properties of Eu(2+) activated Ba(2)Si(3)O(8) ceramic phosphors synthesized by a sol-gel method. The ceramic phosphors have been characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM) and fluorescence measurements. The structural characterization results suggest that the as-prepared phosphors are of single phase monoclinic Ba(2)Si(3)O(8) with rod-like morphology. A broad excitation band ranging from 300 to 410 nm matches well with the ultraviolet (UV) radiation of light-emitting diodes (LEDs). Upon 380 nm UV light excitation, these phosphors emit bluish-green emission centered at 500 nm with color coordination (x=0.25, y=0.40). All the obtained results indicate that the Ba(2)Si(3)O(8):Eu(2+) ceramic phosphors are promising bluish-green candidates for the phosphor-converted white LEDs.

  6. Facile solution-precipitation assisted synthesis and luminescence property of greenish-yellow emitting Ca{sub 6}Ba(PO{sub 4}){sub 4}O:Eu{sup 2+} phosphor

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Ji, Haipeng; Huang, Zhaohui, E-mail: huang118@cugb.edu.cn; Xia, Zhiguo, E-mail: xiazg@ustb.edu.cn

    2016-03-15

    Highlights: • Ca{sub 6}Ba(PO{sub 4}){sub 4}O:Eu{sup 2+} phosphor was prepared by the solution-precipitation assisted route. • The phosphors have satisfactory smooth grain surface and particle size. • It shows greenish-yellow color emission (maximum at 540 nm) upon blue light excitation. • Eu{sup 2+} is coordinated with isolated oxygen atoms and those from PO{sub 4} polyhedra. - Abstract: Greenish-yellow emitting microcrystalline Ca{sub 6}Ba(PO{sub 4}){sub 4}O:Eu{sup 2+} phosphor was successfully prepared by a solution-precipitation assisted high temperature reaction method. Phase structure, morphology and/or luminescence properties of the precursor and the as-prepared phosphors were characterized. The phase-pure Ca{sub 6}Ba(PO{sub 4}){sub 4}O:Eu{sup 2+} phosphorsmore » were obtained with smooth grain surface and particle size of 2–8 μm. Ca{sub 6}Ba(PO{sub 4}){sub 4}O:Eu{sup 2+} exhibits bright greenish-yellow color emission with its maximum at 540 nm upon UV-blue light excitation. The maximum position of the broad emission band is independent on the calcination temperature. The emission intensity increases with increasing calcination temperature due to improved crystallinity. Besides, the presence of two Eu{sup 2+} emission centers in the Ca{sub 6}Ba(PO{sub 4}){sub 4}O crystal lattice was confirmed and the coordination effects are considered concerning the roles of isolated O atoms and those from the PO{sub 4} tetrahedra.« less

  7. Photoluminescence of transparent glass-ceramics based on ZnO nanocrystals and co-doped with Eu3+, Yb3+ ions

    NASA Astrophysics Data System (ADS)

    Arzumanyan, Grigory M.; Kuznetsov, Evgeny A.; Zhilin, Aleksandr A.; Dymshits, Olga S.; Shemchuk, Daria V.; Alekseeva, Irina P.; Mudryi, Alexandr V.; Zhivulko, Vadim D.; Borodavchenko, Olga M.

    2016-12-01

    Glasses of the K2Osbnd ZnOsbnd Al2O3sbnd SiO2 system co-doped with Eu2O3 and Yb2O3 were prepared by the melt-quenching technique. Transparent zincite (ZnO) glass-ceramics were obtained by secondary heat-treatments at 680-860 °C. At 860 °C, traces of Eu oxyapatite appeared in addition to ZnO nanocrystals. The average crystal size obtained from the X-ray diffraction data was found to range between 14 and 35 nm. Absorption spectra of the initial glasses are composed of an absorption edge and absorption bands due to electronic transitions of Eu3+ ions. With heat-treatment, the absorption edge pronouncedly shifts to the visible spectral range. The luminescence properties of the glass and glass-ceramics were studied by measuring their excitation and emission spectra at 300, 78, and 4.2 K. Strong red emission of Eu3+ ions dominated by the 5D0-7F2 (612 nm) electric dipole transition was detected. Changes in the luminescence properties of the Eu3+-related excitation and emission bands were observed after heat-treatments at 680 °C and 860 °C. The ZnO nanocrystals showed both broad luminescence (400-850 nm) and free-exciton emission near 3.3 eV at room temperature. The upconversion luminescence spectrum of the initial glass was obtained under excitation of the 976 nm laser source.

  8. Physical properties of superbulky lanthanide metallocenes: synthesis and extraordinary luminescence of [Eu(II)(Cp(BIG))2] (Cp(BIG) = (4-nBu-C6H4)5-cyclopentadienyl).

    PubMed

    Harder, Sjoerd; Naglav, Dominik; Ruspic, Christian; Wickleder, Claudia; Adlung, Matthias; Hermes, Wilfried; Eul, Matthias; Pöttgen, Rainer; Rego, Daniel B; Poineau, Frederic; Czerwinski, Kenneth R; Herber, Rolfe H; Nowik, Israel

    2013-09-09

    The superbulky deca-aryleuropocene [Eu(Cp(BIG))2], Cp(BIG) = (4-nBu-C6H4)5-cyclopentadienyl, was prepared by reaction of [Eu(dmat)2(thf)2], DMAT = 2-Me2N-α-Me3Si-benzyl, with two equivalents of Cp(BIG)H. Recrystallizyation from cold hexane gave the product with a surprisingly bright and efficient orange emission (45% quantum yield). The crystal structure is isomorphic to those of [M(Cp(BIG))2] (M = Sm, Yb, Ca, Ba) and shows the typical distortions that arise from Cp(BIG)⋅⋅⋅Cp(BIG) attraction as well as excessively large displacement parameter for the heavy Eu atom (U(eq) = 0.075). In order to gain information on the true oxidation state of the central metal in superbulky metallocenes [M(Cp(BIG))2] (M = Sm, Eu, Yb), several physical analyses have been applied. Temperature-dependent magnetic susceptibility data of [Yb(Cp(BIG))2] show diamagnetism, indicating stable divalent ytterbium. Temperature-dependent (151)Eu Mössbauer effect spectroscopic examination of [Eu(Cp(BIG))2] was examined over the temperature range 93-215 K and the hyperfine and dynamical properties of the Eu(II) species are discussed in detail. The mean square amplitude of vibration of the Eu atom as a function of temperature was determined and compared to the value extracted from the single-crystal X-ray data at 203 K. The large difference in these two values was ascribed to the presence of static disorder and/or the presence of low-frequency torsional and librational modes in [Eu(Cp(BIG))2]. X-ray absorbance near edge spectroscopy (XANES) showed that all three [Ln(Cp(BIG))2] (Ln = Sm, Eu, Yb) compounds are divalent. The XANES white-line spectra are at 8.3, 7.3, and 7.8 eV, for Sm, Eu, and Yb, respectively, lower than the Ln2O3 standards. No XANES temperature dependence was found from room temperature to 100 K. XANES also showed that the [Ln(Cp(BIG))2] complexes had less trivalent impurity than a [EuI2(thf)x] standard. The complex [Eu(Cp(BIG))2] shows already at room temperature

  9. Energy-transfer processes in Yb:Tm-doped KY3F10, LiYF4, and BaY2F8 single crystals for laser operation at 1.5 and 2.3 μm

    NASA Astrophysics Data System (ADS)

    Braud, A.; Girard, S.; Doualan, J. L.; Thuau, M.; Moncorgé, R.; Tkachuk, A. M.

    2000-02-01

    Energy-transfer processes have been quantitatively studied in various Tm:Yb-doped fluoride crystals. A comparison between the three host crystals which have been examined (KY3F10, LiYF4, and BaY2F8) shows clearly that the efficiency of the Yb-->Tm energy transfers is larger in KY3F10 than in LiYF4 or BaY2F8. The dependence of the energy-transfer parameters upon the codopant concentrations has been experimentally measured and compared with the results calculated on the basis of migration-assisted energy-transfer models. Using these energy-transfer parameters and a rate equation model, we have performed a theoretical calculation of the laser thresholds for the 3H4-->3F4 and 3H4-->3H5 laser transitions of the Tm ion around 1.5 and 2.3 μm, respectively. Laser experiments performed at 1.5 μm in Yb:Tm:LiYF4 then led to laser threshold values in good agreement with those derived theoretically. Based on these results, optimized values for the Yb and Tm dopant concentrations for typical values of laser cavity and pump modes were finally derived to minimize the threshold pump powers for the laser transitions around 1.5 and 2.3 μm.

  10. Dielectric, magnetic and structural properties of novel multiferroic Eu(0.5)Ba(0.5)TiO(3) ceramics.

    PubMed

    Goian, V; Kamba, S; Nuzhnyy, D; Vaněk, P; Kempa, M; Bovtun, V; Knížek, K; Prokleška, J; Borodavka, F; Ledinský, M; Gregora, I

    2011-01-19

    Dielectric properties of Eu(0.5)Ba(0.5)TiO(3) ceramics were investigated between 10 and 300 K in the frequency range of 1 MHz-100 THz. Permittivity exhibits a strong peak near the ferroelectric phase transition at 215 K. This is mainly due to softening of the lowest frequency polar phonon revealed in THz and infrared spectra. Dielectric relaxation was observed also below the ferroelectric soft mode frequency in the whole investigated temperature region, but it is probably caused by some defects such as Eu(3 + ) cations or oxygen vacancies. This implies that the ferroelectric phase transition has predominantly a displacive character. Raman scattering spectra revealed a lowering of crystal symmetry in the ferroelectric phase and XRD analysis indicated orthorhombic A2mm symmetry below 215 K. The magnetic measurements performed at various frequencies in the field cooled and field heating regime after cooling in zero magnetic fields excluded spin glass behavior and proved an antiferromagnetic order below 1.9 K in Eu(0.5)Ba(0.5)TiO(3).

  11. Pressure effects on magnetic pair-breaking in Mn- and Eu-substituted BaFe{sub 2}As{sub 2}

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Rosa, P. F. S., E-mail: ferrari@ifi.unicamp.br; University of California, Irvine, California 92697-4574; Garitezi, T. M.

    2014-05-07

    We report a combined study of hydrostatic pressure (P ≤ 25 kbar) and chemical substitution on the magnetic pair-breaking effect in Eu- and Mn-substituted BaFe{sub 2}As{sub 2} single crystals. At ambient pressure, both substitutions suppress the superconducting (SC) transition temperature (T{sub c}) of BaFe{sub 2–x}Co{sub x}As{sub 2} samples slightly under the optimally doped region, indicating the presence of a pair-breaking effect. At low pressures, an increase of T{sub c} is observed for all studied compounds followed by an expected decrease at higher pressures. However, in the Eu dilute system, T{sub c} further increases at higher pressure along with a narrowingmore » of the SC transition, suggesting that a pair-breaking mechanism reminiscent of the Eu Kondo single impurity regime is being suppressed by pressure. Furthermore, Electron Spin Resonance (ESR) measurements indicate the presence of Mn{sup 2+} and Eu{sup 2+} local moments and the microscopic parameters extracted from the ESR analysis reveal that the Abrikosov–Gor'kov expression for magnetic pair-breaking in a conventional sign-preserving superconducting state cannot describe the observed reduction of T{sub c}.« less

  12. Luminescence and energy transfer properties of Ca2Ba3(PO4)3Cl and Ca2Ba3(PO4)3Cl:A (A = Eu2+/Ce3+/Dy3+/Tb3+) under UV and low-voltage electron beam excitation.

    PubMed

    Shang, Mengmeng; Geng, Dongling; Yang, Dongmei; Kang, Xiaojiao; Zhang, Yang; Lin, Jun

    2013-03-18

    Pure Ca2Ba3(PO4)3Cl and rare earth ion (Eu(2+)/Ce(3+)/Dy(3+)/Tb(3+)) doped Ca2Ba3(PO4)3Cl phosphors with the apatite structure have been prepared via a Pechini-type sol-gel process. X-ray diffraction (XRD) and structure refinement, photoluminescence (PL) spectra, cathodoluminescence (CL) spectra, absolute quantum yield, as well as lifetimes were utilized to characterize samples. Under UV light excitation, the undoped Ca2Ba3(PO4)3Cl sample shows broad band photoluminescence centered near 480 nm after being reduced due to the defect structure. Eu(2+) and Ce(3+) ion doped Ca2Ba3(PO4)3Cl samples also show broad 5d → 4f transitions with cyan and blue colors and higher quantum yields (72% for Ca2Ba3(PO4)3Cl:0.04Eu(2+); 67% for Ca2Ba3(PO4)3Cl:0.016Ce(3+)). For Dy(3+) and Tb(3+) doped Ca2Ba3(PO4)3Cl samples, they give strong line emissions coming from 4f → 4f transitions. Moreover, the Ce(3+) ion can transfer its energy to the Tb(3+) ion in the Ca2Ba3(PO4)3Cl host, and the energy transfer mechanism has been demonstrated to be a resonant type, via a dipole-quadrupole interaction. However, under the low voltage electron beam excitation, Tb(3+) ion doped Ca2Ba3(PO4)3Cl samples present different luminescence properties compared with their PL spectra, which is ascribed to the different excitation mechanism. On the basis of the good PL and CL properties of the Ca2Ba3(PO4)3Cl:A (A = Ce(3+)/Eu(2+)/Tb(3+)/Dy(3+)), Ca2Ba3(PO4)3Cl might be promising for application in solid state lighting and field-emission displays.

  13. Highly efficient red-emitting BaMgBO3F:Eu3+,R+ (R: Li, Na, K, Rb) phosphor for near-UV excitation synthesized via glass precursor solid-state reaction

    NASA Astrophysics Data System (ADS)

    Shinozaki, Kenji; Akai, Tomoko

    2017-09-01

    Eu3+-doped fluoroborate crystals of BaMgBO3F were synthesized by a solid-state reaction using a glassy precursor material, and their photoluminescence (PL) was investigated. To compensate for the incorporation of Eu3+ into Ba2+ sites, samples codoped with alkali ions (Li+, Na+, K+, Rb+) were also prepared. The Eu3+-doped sample showed red PL with a quantum yield (QY) of 65% caused by near-UV excitation (λ = 393 nm), and PL intensity and QY increased with the codoping of Eu3+ and alkali ions. It was found that the Eu3+,Li+-codoped sample showed the highest PL intensity and a QY of 83%.

  14. A broadening temperature sensitivity range with a core-shell YbEr@YbNd double ratiometric optical nanothermometer

    NASA Astrophysics Data System (ADS)

    Marciniak, L.; Prorok, K.; Francés-Soriano, L.; Pérez-Prieto, J.; Bednarkiewicz, A.

    2016-02-01

    The chemical architecture of lanthanide doped core-shell up-converting nanoparticles can be engineered to purposely design the properties of luminescent nanomaterials, which are typically inaccessible to their homogeneous counterparts. Such an approach allowed to shift the up-conversion excitation wavelength from ~980 to the more relevant ~808 nm or enable Tb or Eu up-conversion emission, which was previously impossible to obtain or inefficient. Here, we address the issue of limited temperature sensitivity range of optical lanthanide based nano-thermometers. By covering Yb-Er co-doped core nanoparticles with the Yb-Nd co-doped shell, we have intentionally combined temperature dependent Er up-conversion together with temperature dependent Nd --> Yb energy transfer, and thus have expanded the temperature response range ΔT of a single nanoparticle based optical nano-thermometer under single ~808 nm wavelength photo-excitation from around ΔT = 150 K to over ΔT = 300 K (150-450 K). Such engineered nanocrystals are suitable for remote optical temperature measurements in technology and biotechnology at the sub-micron scale.The chemical architecture of lanthanide doped core-shell up-converting nanoparticles can be engineered to purposely design the properties of luminescent nanomaterials, which are typically inaccessible to their homogeneous counterparts. Such an approach allowed to shift the up-conversion excitation wavelength from ~980 to the more relevant ~808 nm or enable Tb or Eu up-conversion emission, which was previously impossible to obtain or inefficient. Here, we address the issue of limited temperature sensitivity range of optical lanthanide based nano-thermometers. By covering Yb-Er co-doped core nanoparticles with the Yb-Nd co-doped shell, we have intentionally combined temperature dependent Er up-conversion together with temperature dependent Nd --> Yb energy transfer, and thus have expanded the temperature response range ΔT of a single nanoparticle

  15. Remarkably Enhancing Green-Excitation Efficiency for Solar Energy Utilization: Red Phosphors Ba2ZnS3:Eu2+, X- Co-Doped Halide Ions (X = Cl, Br, I).

    PubMed

    Luo, Tingting; Du, Yun; Qiu, Zhongxian; Li, Yanmei; Wang, Xiaofang; Zhou, Wenli; Zhang, Jilin; Yu, Liping; Lian, Shixun

    2017-05-15

    Eu 2+ -activated Ba 2 ZnS 3 has been reported as a red phosphor with a broad emission band peaking at 650 nm under blue excitation for white-LED. In this study, Ba 2 ZnS 3 :Eu 2+ , X - (X = F, Cl, Br, I) phosphors doped with halide ions were prepared by traditional high-temperature solid-state reaction. Phase identification of powders was performed by X-ray powder diffraction analysis, confirming the existence of single-phase Ba 2 ZnS 3 crystals without dopant. The corresponding excitation spectra showed an additional broad band in the green region peaking at 550 nm when the phosphor was halogenated except by the smallest F - . It was proved that the green-excitation efficiency successively strengthened from Cl - , to Br - , to I - , which suggested larger halide ions made a greater contribution to the further splitting of the t 2g energy level of the doped Eu 2+ ions in the host Ba 2 ZnS 3 , and the optimized formula Ba 1.995 ZnS 2.82 :Eu 2+ 0.005 , I - 0.18 showed a potential application in solar spectral conversion for agricultural greenhouse and solar cell. Defect chemistry theory and crystal field theory provided insights into the key role of halide ions in enhancing green-excitation efficiency.

  16. Orange and red upconversion laser pumped by an avalanche mechanism in Pr3+, Yb3+:BaY2F8

    NASA Astrophysics Data System (ADS)

    Osiac, E.; Heumann, E.; Huber, G.; Kück, S.; Sani, E.; Toncelli, A.; Tonelli, M.

    2003-06-01

    The letter reports on upconverted orange (607.5 nm, 3P0→3H6) and red (638.7 nm, 3P0→3F2) laser oscillation at room temperature observed in Pr3+, Yb3+:BaY2F8 under excitation at 822 or 841 nm at 300 K. The upconversion mechanism that populates the emitting level is an avalanche excitation mechanism. Output powers up to 55 mW and slope efficiencies up to 27% were demonstrated at 607.5 nm. At 638.7 nm, the maximum output power was 26 mW with a slope efficiency of about 13.5%.

  17. Luminescent properties of Eu{sup 2+}-doped BaGdF{sub 5} glass ceramics a potential blue phosphor for ultra-violet light-emitting diode

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Zhang, Weihuan; Zhang, Yuepin, E-mail: zhangyuepin@nbu.edu.cn; Ouyang, Shaoye

    2015-01-14

    Eu{sup 2+} doped transparent oxyfluoride glass ceramics containing BaGdF{sub 5} nanocrystals were successfully fabricated by melt-quenching technique under a reductive atmosphere. The structure of the glass and glass ceramics were investigated by differential scanning calorimetry, X-ray diffraction (XRD), and transmission electron microscopy (TEM). The luminescent properties were investigated by transmission, excitation, and emission spectra. The decay time of the Gd{sup 3+} ions at 312 nm excited with 275 nm were also investigated. The results of XRD and TEM indicated the existence of BaGdF5 nanocrystals in the transparent glass ceramics. The excitation spectra of Eu{sup 2+} doped glass ceramics showed an excellent overlapmore » with the main emission region of an ultraviolet light-emitting diode (UV-LED). Compared with the as-made glass, the emission of glass ceramics is much stronger by a factor of increasing energy transfer efficiency from Gd{sup 3+} to Eu{sup 2+} ions, the energy transfer efficiency from Gd{sup 3+} to Eu{sup 2+} ions was discussed. In addition, the chromaticity coordinates of glass and glass ceramics specimens were also discussed, which indicated that the Eu{sup 2+} doped BaGdF{sub 5} glass ceramics may be used as a potential blue-emitting phosphor for UV-LED.« less

  18. Excitation-dependent local symmetry reversal in single host lattice Ba2A(BO3)2:Eu3+ [A = Mg and Ca] phosphors with tunable emission colours.

    PubMed

    Jayakiruba, S; Chandrasekaran, S Selva; Murugan, P; Lakshminarasimhan, N

    2017-07-05

    Eu 3+ activated phosphors are widely used as red emitters in various display devices and light emitting diodes (LEDs). The emission characteristics of Eu 3+ depend on the local site symmetry. The present study demonstrates the role of excitation-dependent local symmetry changes due to the structural reorganization on the emission colour tuning of Eu 3+ from orange-red to orange in single host lattices, Ba 2 Mg(BO 3 ) 2 and Ba 2 Ca(BO 3 ) 2 . The choice of these lattices was based on the difference in the extent of strain experienced by the oxygen atoms. The samples with Eu 3+ at Ba or Mg (Ca) sites were synthesized using the conventional high-temperature solid-state reaction method. The samples were characterized using powder XRD, 11 B MAS-NMR, FT-IR, and diffuse reflectance UV-Vis spectroscopic techniques. The room temperature photoluminescence (PL) recorded using different excitation wavelengths revealed a clear difference in the PL emission features due to symmetry reversal from non-inversion to inversion symmetry around Eu 3+ . The reorganization of highly strained oxygen atoms leads to such symmetry reversal. First-principles calculations were used to deduce the optimized structures of the two borate host lattices, and local geometries and their distortions upon Eu 3+ substitution. The outcomes of these calculations support the experimental findings.

  19. Sub-10 nm lanthanide doped BaLuF{sub 5} nanocrystals: Shape controllable synthesis, tunable multicolor emission and enhanced near-infrared upconversion luminescence

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Rao, Ling; Lu, Wei; Wang, Haibo

    2015-04-15

    Highlights: • Sub-10 nm cubic phase BaLuF{sub 5} nanocrystals were synthesized by a hydrothermal method for the first time. • Tunable multicolor from yellow to yellow-green was achieved by controlling Gd{sup 3+} content in BaLuF{sub 5}:Yb/Er system. • Intense near-infrared upconversion luminescence in BaLuF{sub 5}:Gd/Yb/Tm nanocrystal. • The enhancement near-infrared luminescence can be realized by adjusting the content of Gd{sup 3+} in BaLuF{sub 5}:Gd/Yb/Tm system. - Abstract: In this study, sub-10 nm BaLuF{sub 5} nanocrystals with cubic phase structure were synthesized by a solvothermal method using oleic acid as the stabilizing agent. The as-prepared BaLuF{sub 5} nanocrystals were characterized bymore » transmission electron microscopy (TEM), X-ray diffraction (XRD), and analyzed by the upconversion (UC) spectra. The TEM results reveal that these samples present high uniformity. Compared with Gd-free samples, the size of BaLuF{sub 5}:Yb/Er doped with 10% Gd{sup 3+} decreased to 5.6 nm. In addition, BaLuF{sub 5}:Yb/Tm/Gd upconversion nanoparticles (UCNPs) presented efficient near-infrared (NIR)-NIR UC luminescence. Therefore, it is expected that these ultra-small BaLuF{sub 5} nanocrystals with well-controlled shape, size, and UC emission have potential applications in biomedical imaging fields.« less

  20. Electrochemical performance of BaZr0.1Ce0.7Y0.1Yb0.1O3-δ electrolyte based proton-conducting SOFC solid oxide fuel cell with layered perovskite PrBaCo2O5+δ cathode

    NASA Astrophysics Data System (ADS)

    Ding, Hanping; Xie, Yuanyuan; Xue, Xingjian

    2011-03-01

    BaZr0.1Ce0.7Y0.1Yb0.1O3-δ (BZCYYb) exhibits adequate protonic conductivity as well as sufficient chemical and thermal stability over a wide range of SOFC operating conditions, while layered perovskite PrBaCo2O5+δ (PBCO) has advanced electrochemical properties. This research fully takes advantage of these advanced properties and develops a novel protonic ceramic membrane fuel cell (PCMFC) of Ni-BZCYYb|BZCYYb|PBCO. The performance of the button cell was tested under intermediate-temperature range from 600 to 700 °C with humified H2 (∼3% H2O) as fuel and ambient air as oxidant. The results show that the open circuit potential of 0.983 V and the maximal power density of 490 mW cm-2 were achieved at 700 °C. By co-doping barium zirconate-cerate with Y and Yb, the conductivity of electrolyte was significantly improved. The polarization processes of the button cell were characterized using the complicated electrochemical impedance spectroscopy technique. The results indicate that the polarization resistances contributed from both charge migration processes and mass transfer processes increase with decreasing cell voltage loads. However the polarization resistance induced by mass transfer processes is negligible in the studied button cell.

  1. Synthesis and luminescence characterization of Y2 BaZnO5 :RE (RE = Eu3+ , Tb3+ , Pr3+ and Sm3+ ) phosphors.

    PubMed

    Taikar, D R; Joshi, C P; Moharil, S V

    2017-09-01

    Modified synthesis and luminescence of Y 2 BaZnO 5 phosphors activated with the rare earths (RE) Eu 3 + , Tb 3 + , Pr 3 + and Sm 3 + are reported. RE 2 BaZnO 5 phosphors have attracted attention because of their interesting magnetic and optical properties; and are usually prepared using a two-step solid-state reaction. In the first step, carbonates or similar precursors are thoroughly mixed and heated at 900°C to decompose them to oxides. To eliminate the unwanted phases like BaRE 2 O 4 , the resulting powders are reheated at 1100°C for a long time. We prepared Y 2 BaZnO 5 phosphors activated with various activators by replacing the first step with combustion synthesis. The photoluminescence results are presented. The photoluminescence results for Eu 3 + , Tb 3 + and Pr 3 + are in good agreement with the literature. However, photoluminescence emission from Sm 3 + has not been documented previously. The excitation spectrum of Eu 3 + is dominated by a charge transfer band around 261 nm, and an additional band around 238 nm is always present, irrespective of the type of activator. The presence of this band for all these different types of activators was interpreted as host absorption. Copyright © 2016 John Wiley & Sons, Ltd.

  2. Effect of crystalline electric field on heat capacity of LnBaCuFeO5 (Ln = Gd, Ho, Yb)

    NASA Astrophysics Data System (ADS)

    Lal, Surender; Mukherjee, K.; Yadav, C. S.

    2018-02-01

    Structural, magnetic and thermodynamic properties of layered perovskite compounds LnBaCuFeO5 (Ln = Ho, Gd, Yb) have been investigated. Unlike the iso-structural compound YBaCuFeO5, which shows commensurate antiferromagnetic to incommensurate antiferromagnetic ordering below ∼200 K, the studied compounds do not show any magnetic transition in measured temperature range of 2-350 K. The high temperature heat capacity of the compounds is understood by employing contributions from both optical and acoustic phonons. At low temperature, the observed upturn in the heat capacity is attributed to the Schottky anomaly. The magnetic field dependent heat capacity shows the variation in position of the anomaly with temperature, which appears due to the removal of ground state degeneracy of the rare earth ions, by the crystalline electric field.

  3. Laser action of Pr3+ in LiYF4 and spectroscopy of Eu2+-sensitized Pr in BaY2F8

    NASA Astrophysics Data System (ADS)

    Knowles, David S.; Gabbe, David; Jenssen, H. P.; Zhang, Z.

    1988-06-01

    Laser action in flashlamp-pumped Pr:LiYF4 at room temperature is observed at 640 nm with a 15-J threshold, but only about 0.01 percent slope efficiency. Increased efficiency from sensitizing the Pr with Eu2+ is explored in the system Eu,Pr:BaY2F8. Codoped samples have been grown by the Czochralski growth method, and energy transfer between 2+ and Pr3+ is observed to be very weak. This is probably due to the poor overlap of the Eu2+ emission with the Pr3+ absorption lines, leading to the conclusion that hosts with a stronger crystal field at the Eu2+ site need to be identified.

  4. Luminescence properties of Eu2+ in M2MgSi2O7 (M=Ca, Sr, and Ba) phosphors

    NASA Astrophysics Data System (ADS)

    Kim, T.; Kim, Y.; Kang, S.

    2012-03-01

    The photoluminescence properties of alkali-earth magnesium silicates (M2MgSi2O7, M=Ca, Sr, and Ba) doped with Eu2+ were investigated. Solid solutions of Ba x Sr2- x Si2O7, Ca2MgSi2O7, and Sr2MgSi2O7 were prepared. Ba x Sr2- x Si2O7 retained a tetragonal crystal structure similar to the structure of the other compounds up to a stoichiometry of x=1.6, which enabled a systematic study of the common structure. Monoclinic Ba2MgSi2O7 was prepared, and the luminescence properties were compared with those of other samples. The emission and excitation spectra of tetragonal M2MgSi2O7 (M=Ca, Sr, and Ba) changed as a function of the covalency, site symmetry, and crystal field strength. The luminescence properties showed excellent agreement with theoretical predictions based on these factors. The Stokes shift differentiated the emission behaviors of the tetragonal and monoclinic structures.

  5. Photoluminescence and Energy Transfer Properties with Y+SiO4 Substituting Ba+PO4 in Ba3Y(PO4)3:Ce(3+)/Tb(3+), Tb(3+)/Eu(3+) Phosphors for w-LEDs.

    PubMed

    Li, Kai; Liang, Sisi; Shang, Mengmeng; Lian, Hongzhou; Lin, Jun

    2016-08-01

    A series of Ce(3+), Tb(3+), Eu(3+) doped Ba2Y2(PO4)2(SiO4) (BYSPO) phosphors were synthesized via the high-temperature solid-state reaction route. X-ray diffraction, high-resolution transmission electron microscopy, Fourier transform infrared, solid-state NMR, photoluminescence (PL) including temperature-dependent PL, and fluorescent decay measurements were conducted to characterize and analyze as-prepared samples. BYSPO was obtained by the substitution of Y+SiO4 for Ba+PO4 in Ba3Y(PO4)3 (BYPO). The red shift of PL emission from 375 to 401 nm occurs by comparing BYSPO:0.14Ce(3+) with BYPO:0.14Ce(3+) under 323 nm UV excitation. More importantly, the excitation edge can be extended from 350 to 400 nm, which makes it be excited by UV/n-UV chips (330-410 nm). Tunable emission color from blue to green can be observed under 365 nm UV excitation based on the energy transfer from Ce(3+) to Tb(3+) ions after codoping Tb(3+) into BYSPO:0.14Ce(3+). Moreover, energy transfer from Tb(3+) to Eu(3+) ions also can be found in BYSPO:Tb(3+),Eu(3+) phosphors, resulting in the tunable color from green to orange red upon 377 nm UV excitation. Energy transfer properties were demonstrated by overlap of excitation spectra, variations of emission spectra, and decay times. In addition, energy transfer mechanisms from Ce(3+) to Tb(3+) and Tb(3+) to Eu(3+) in BYSPO were also discussed in detail. Quantum yields and CIE chromatic coordinates were also presented. Generally, the results suggest their potential applications in UV/n-UV pumped LEDs.

  6. [Study on Hydrothermal Preparation and Luminescence Properties of Luminescent Material BaSrMg(PO₄)₂:Eu³⁺].

    PubMed

    Hu, Qing-song; Zhu, Cheng-jing; Xia, Yue-yi; Wang, Li-li; Liu, Wen-han; Pan, Zai-fa

    2016-02-01

    Eu³⁺ doped BaSrMg (PO₄)₂ were prepared by a hydrothermal method. The crystal structure and morphology of BaSrMg(PO₄)₂:Eu³⁺ phosphor were characterized by X-ray powder diffraction (XRD) and field emission scanning electron microscopy (FESEM). The effects of different pH values (5, 6, 7 and 8) and different reaction temperatures (120, 140, 160, 180 and 200 °C) on the crystal structure and morphology of BaSrMg(PO₄)₂:Eu³⁺ phosphor were studied in this paper. The results of XRD indicate that diffraction peaks are sharp and strong only when pH value is 6, meanwhile the FESEM shows the morphology is regular-shaped. The XRD patterns show amorphous halos superimposed with several weak sharp peaks for the samples preparing under the pH values of 5, 7 and 8. It indicates that these three samples are solid solution or mixed phases, which are in accord with the results of FESEM. From the fluorescence spectra, the peaks in the excitation spectra were assigned to the transition from ⁷F₀ to ⁵D₄, ⁵L₈, ⁵L₆ and ⁵D₂, while the peaks of emission spectra corresponding to the transition of ⁵D₁ --> ⁷F₁ and ⁵D₀-->⁷Fj (J = 0, 1, 2, 3 and 4). The strongest emission peak of the optimized phosphor located at 613 nm (⁵D0--> ⁷F₂), excited by the main excitation peak with wavelength of 394 nm. The splitting of the emission peaks changes depends on pH values and temperatures, which indicating that luminescence properties is closely related to the crystal structure and morphology of particles.

  7. Syntheses, crystal structure, and electronic properties of the five ABaMQ{sub 4} compounds RbBaPS{sub 4}, CsBaPS{sub 4}, CsBaVS{sub 4}, RbBaVSe{sub 4}, and CsBaVSe{sub 4}

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Mesbah, Adel; ICSM, UMR 5257 CEA / CNRS / UM / ENSCM, Site de Marcoule-Bâtiment 426, BP 17171, 30207 Bagnols-sur-Cèze Cedex; Prakash, Jai

    Five new compounds belonging to the ABaMQ{sub 4} family were synthesized by solid-state chemistry at 1123 K. The compounds RbBaPS{sub 4}, CsBaPS{sub 4}, CsBaVS{sub 4}, RbBaVSe{sub 4}, and CsBaVSe{sub 4} are isostructural and have the TlEuPS{sub 4} structure type. They crystallize in space group D{sup 16}{sub 2h} – Pnma of the orthorhombic system. Their structure consists isolated MQ{sub 4} tetrahedra separated by A and Ba atoms to form a salt-like structure. Density Functional Theory (DFT) calculations of the electronic structures with the use of the HSE functional suggest that the compounds are semiconductors with calculated band gaps of 3.3 eVmore » (RbBaPS{sub 4}), 3.4 eV (CsBaPS{sub 4}), 2.3 eV (CsBaVS{sub 4}), and 1.6 eV (RbBaVSe{sub 4}). - Graphical abstract: General view of the ABaMQ{sub 4} structure down the a axis. - Highlights: • Five new ABaMQ{sub 4} compounds were synthesized by solid-state chemistry at 1123 K. • RbBaPS{sub 4}, CsBaPS{sub 4}, CsBaVS{sub 4}, RbBaVSe{sub 4}, and CsBaVSe{sub 4} have the TlEuPS{sub 4} structure type. • The compounds are semiconductors with calculated band gaps ranging from 1.6 to 3.4 eV.« less

  8. Blue upconversion with excitation into Tm ions at 780 nm in Yb- and Tm-codoped fluoride crystals

    NASA Astrophysics Data System (ADS)

    Zhang, X. X.; Hong, P.; Bass, M.; Chai, B. H. T.

    1995-04-01

    Strong blue emissions have been observed in fluoride crystals, such as LiYF4, BaY2F8, and KYF4, codoped with Tm3+ and Yb3+ when excited into the Tm3+ 3F4 state at ~780 nm. Energy transfer from Tm3+ to Yb3+ ions followed by the transfer from Yb3+ to Tm3+ was demonstrated to be responsible for the upconversion process. A pumping scheme is proposed based on this upconversion mechanism for blue-laser applications using these materials.

  9. Metaheuristics-Assisted Combinatorial Screening of Eu2+-Doped Ca-Sr-Ba-Li-Mg-Al-Si-Ge-N Compositional Space in Search of a Narrow-Band Green Emitting Phosphor and Density Functional Theory Calculations.

    PubMed

    Lee, Jin-Woong; Singh, Satendra Pal; Kim, Minseuk; Hong, Sung Un; Park, Woon Bae; Sohn, Kee-Sun

    2017-08-21

    A metaheuristics-based design would be of great help in relieving the enormous experimental burdens faced during the combinatorial screening of a huge, multidimensional search space, while providing the same effect as total enumeration. In order to tackle the high-throughput powder processing complications and to secure practical phosphors, metaheuristics, an elitism-reinforced nondominated sorting genetic algorithm (NSGA-II), was employed in this study. The NSGA-II iteration targeted two objective functions. The first was to search for a higher emission efficacy. The second was to search for narrow-band green color emissions. The NSGA-II iteration finally converged on BaLi 2 Al 2 Si 2 N 6 :Eu 2+ phosphors in the Eu 2+ -doped Ca-Sr-Ba-Li-Mg-Al-Si-Ge-N compositional search space. The BaLi 2 Al 2 Si 2 N 6 :Eu 2+ phosphor, which was synthesized with no human intervention via the assistance of NSGA-II, was a clear single phase and gave an acceptable luminescence. The BaLi 2 Al 2 Si 2 N 6 :Eu 2+ phosphor as well as all other phosphors that appeared during the NSGA-II iterations were examined in detail by employing powder X-ray diffraction-based Rietveld refinement, X-ray absorption near edge structure, density functional theory calculation, and time-resolved photoluminescence. The thermodynamic stability and the band structure plausibility were confirmed, and more importantly a novel approach to the energy transfer analysis was also introduced for BaLi 2 Al 2 Si 2 N 6 :Eu 2+ phosphors.

  10. BaSO4:Eu as an energy independent thermoluminescent radiation dosimeter for gamma rays and C6+ ion beam

    NASA Astrophysics Data System (ADS)

    Sharma, Kanika; Bahl, Shaila; Singh, Birendra; Kumar, Pratik; Lochab, S. P.; Pandey, Anant

    2018-04-01

    BaSO4:Eu nanophosphor is delicately optimized by varying the concentration of the impurity element and compared to the commercially available thermoluminescent dosimeter (TLD) LiF:Mg,Ti (TLD-100) and by extension also to CaSO4:Dy (TLD-900) so as to achieve its maximum thermoluminescence (TL) sensitivity. Further, the energy dependence property of this barite nanophosphor is also explored at length by exposing the phosphor with 1.25 MeV of Co-60, 0.662 MeV of Cs-137, 85 MeV and 65 MeV of Carbon ion beams. Various batches of the phosphor at hand (with impurity concentrations being 0.05, 0.10, 0.20, 0.50 and 1.00 mol%) are prepared by the chemical co-precipitation method out of which BaSO4:Eu with 0.20 mol% Eu exhibits the maximum TL sensitivity. Further, the optimized nanophosphor exhibits a whopping 28.52 times higher TL sensitivity than the commercially available TLD-100 and 1.426 times higher sensitivity than TLD-900, a noteworthy linear response curve for an exceptionally wide range of doses i.e. 10 Gy to 2 kGy and a simple glow curve structure. Furthermore, when the newly optimized nanophosphor is exposed with two different energies of gamma radiations, namely 1.25 MeV of Co-60 (dose range- 10-300 Gy) and 0.662 MeV of Cs-137 (dose range- 1-300 Gy), it is observed that the shape and structure of the glow curves remain remarkably similar for different energies of radiation while the TL response curve shows little to no variation. When exposed to different energies of carbon ion beam BaSO4:Eu displays energy independence at lower doses i.e. from 6.059 to 14.497 kGy. Finally, even though energy independence is lost at higher doses, the material shows high sensitivity to higher energy (85 MeV) of carbon beam compared to the lower energy (65 MeV of C6+) and saturation is apparent only after 121.199 kGy. Therefore the present nanophosphor displays potential as an energy independent TLD.

  11. New ternary phosphides and arsenides. Syntheses, crystal structures, physical properties of Eu{sub 2}ZnP{sub 2}, Eu{sub 2}Zn{sub 2}P{sub 3} and Eu{sub 2}Cd{sub 2}As{sub 3}

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Wang, Jian; Xia, Sheng-Qing, E-mail: shqxia@sdu.edu.cn; Tao, Xu-Tang

    2013-09-15

    Three new europium pnictides Eu{sub 2}ZnP{sub 2}, Eu{sub 2}Zn{sub 2}P{sub 3} and Eu{sub 2}Cd{sub 2}As{sub 3} have been synthesized and their structures were determined by single-crystal X-ray diffraction. Eu{sub 2}ZnP{sub 2} is isotypic with Yb{sub 2}CdSb{sub 2} (Cmc2{sub 1} (No. 36); cell parameters a=4.1777(7) Å, b=15.925(3) Å, c=7.3008(12) Å), while the latter two compounds crystallize with the Ba{sub 2}Cd{sub 2}Sb{sub 3} structure type (C2/m (No. 12); cell parameters a=15.653(5)/16.402(1) Å, b=4.127(1)/4.445(4) Å, c=11.552(4)/12.311(1) Å and β=126.647(4)/126.515(7)° for Eu{sub 2}Zn{sub 2}P{sub 3} and Eu{sub 2}Cd{sub 2}As{sub 3}, respectively). Magnetic susceptibility measurements in the interval 5–300 K confirm paramagnetic behavior and effectivemore » magnetic moments characteristic of Eu{sup 2+} ([Xe] 4f{sup 7}) ground states. Temperature-dependent electrical conductivity measurements also prove that Eu{sub 2}Cd{sub 2}As{sub 3} is a semiconducting compound with a narrow band gap of 0.059 eV below 100 K. According to TG/DSC analyses, Eu{sub 2}Cd{sub 2}As{sub 3} starts to decompose at about 950 K. - Graphical abstract: A polyhedral view of the crystal structure of new pnictides Eu{sub 2}T{sub 2}Pn{sub 3} (T=Zn or Cd; Pn=P or As). Display Omitted - Highlights: • Three new ternary pnictide Zintl compounds, Eu{sub 2}ZnP{sub 2}, Eu{sub 2}Zn{sub 2}P{sub 3} and Eu{sub 2}Cd{sub 2}As{sub 3}, have been synthesized and characterized. • The europium cations are divalent and ferromagnetically coupled in both Eu{sub 2}Zn{sub 2}P{sub 3} and Eu{sub 2}Cd{sub 2}As{sub 3}. • Eu{sub 2}Cd{sub 2}As{sub 3} has a very small band gap of 0.06 eV and starts to decompose over 950 K.« less

  12. Intervalence charge transfer luminescence: Interplay between anomalous and 5d − 4f emissions in Yb-doped fluorite-type crystals

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Barandiarán, Zoila, E-mail: zoila.barandiaran@uam.es; Seijo, Luis; Instituto Universitario de Ciencia de Materiales Nicolás Cabrera, Universidad Autónoma de Madrid, 28049 Madrid

    2014-12-21

    In this paper, we report the existence of intervalence charge transfer (IVCT) luminescence in Yb-doped fluorite-type crystals associated with Yb{sup 2+}–Yb{sup 3+} mixed valence pairs. By means of embedded cluster, wave function theory ab initio calculations, we show that the widely studied, very broad band, anomalous emission of Yb{sup 2+}-doped CaF{sub 2} and SrF{sub 2}, usually associated with impurity-trapped excitons, is, rather, an IVCT luminescence associated with Yb{sup 2+}–Yb{sup 3+} mixed valence pairs. The IVCT luminescence is very efficiently excited by a two-photon upconversion mechanism where each photon provokes the same strong 4f{sup 14}–1A{sub 1g}→ 4f{sup 13}({sup 2}F{sub 7/2})5de{sub g}–1T{submore » 1u} absorption in the Yb{sup 2+} part of the pair: the first one, from the pair ground state; the second one, from an excited state of the pair whose Yb{sup 3+} moiety is in the higher 4f{sup 13}({sup 2}F{sub 5/2}) multiplet. The Yb{sup 2+}–Yb{sup 3+} → Yb{sup 3+}–Yb{sup 2+} IVCT emission consists of an Yb{sup 2+} 5de{sub g} → Yb{sup 3+} 4f{sub 7/2} charge transfer accompanied by a 4f{sub 7/2} → 4f{sub 5/2} deexcitation within the Yb{sup 2+} 4f{sup 13} subshell: [{sup 2}F{sub 5/2}5de{sub g},{sup 2}F{sub 7/2}] → [{sup 2}F{sub 7/2},4f{sup 14}]. The IVCT vertical transition leaves the oxidized and reduced moieties of the pair after electron transfer very far from their equilibrium structures; this explains the unexpectedly large band width of the emission band and its low peak energy, because the large reorganization energies are subtracted from the normal emission. The IVCT energy diagrams resulting from the quantum mechanical calculations explain the different luminescent properties of Yb-doped CaF{sub 2}, SrF{sub 2}, BaF{sub 2}, and SrCl{sub 2}: the presence of IVCT luminescence in Yb-doped CaF{sub 2} and SrF{sub 2}; its coexistence with regular 5d-4f emission in SrF{sub 2}; its absence in BaF{sub 2} and SrCl{sub 2}; the

  13. Optical properties of Eu2+ ions in BaY2F8 for completely-solid-state cw UV laser emission

    NASA Astrophysics Data System (ADS)

    Toncelli, Alessandra; Moglia, Francesca; Tonelli, Mauro

    2010-11-01

    Eu-doped BaYF single crystals have been grown with two different Eu ion concentrations: 0.5%, 1% Eu doping levels. It was found that part of the Eu ions added in the melt were reduced during the growth process and the ratio between the Eu and Eu content in the crystal depends on the duration of the growth process. A complete room-temperature polarized spectroscopic characterization of the divalent Eu ions in this host crystal is presented with particular insights in the laser potentialities of the compound in the UV region. Polarized absorption, emission and excitation spectra are presented together with the lifetime measurement of the emitting level. It was found that due to the weak nephelauxetic effect the 4f7→4f65d1 band is located at higher energy than the 4f→4f(8S→6P) transition. As a result, when pumped in the 200- 300 nm range, this crystal shows an interesting emission that extends from 351 to 366 nm and has a decay-time as long as τ=(1.5±0.1) ms. This opens the possibility to obtain completely-solid-state laser emission in the UV region with potentialities for cw or mode-locked emission.

  14. Data-driven discovery of energy materials: efficient BaM2Si3O10 : Eu2+ (M = Sc, Lu) phosphors for application in solid state white lighting.

    PubMed

    Brgoch, Jakoah; Hasz, Kathryn; Denault, Kristin A; Borg, Christopher K H; Mikhailovsky, Alexander A; Seshadri, Ram

    2014-01-01

    In developing phosphors for application in solid state lighting, it is advantageous to target structures from databases with highly condensed polyhedral networks that produce rigid host compounds. Rigidity limits channels for non-radiative decay that will decrease the luminescence quantum yield. BaM(2)Si(3)O(10) (M = Sc, Lu) follows this design criterion and is studied here as an efficient Eu(2+)-based phosphor. M = Sc(3+) and Lu(3+) compounds with Eu(2+) substitution were prepared and characterized using synchrotron X-ray powder diffraction and photoluminescence spectroscopy. Substitution with Eu(2+) according to Ba(1-x)Eu(x)Sc(2)Si(3)O(10) and Ba(1-x)Eu(x)Lu(2)Si(3)O(10) results in UV-to-blue and UV-to-blue-green phosphors, respectively. Interestingly, substitution with Eu(2+) in the Lu(3+) containing material produces two emission peaks at low temperature and with 365 nm excitation, as allowed by the two substitution sites. The photoluminescence of the Sc(3+) compound is robust at high temperature, decreasing by only 25% of its room temperature intensity at 503 K, while the Lu-analogue suffers a large drop (75%) from its room temperature intensity. The decrease in emission intensity is explained as stemming from charge transfer quenching due to the short distances separating the luminescent centers on the Lu(3+) substitution site. The correlation between structure and optical response in these two compounds indicates that even though the structures are three-dimensionally connected, high symmetry is required to prevent structural distortions that could impact photoluminescence.

  15. Photoluminescence properties and structure of double perovskite Ba2ZnWO6:Eu3+, Li+ as a novel red emitting phosphor

    NASA Astrophysics Data System (ADS)

    Chen, Peng; Yang, Dingming; Hu, Wenyuan; Zhang, Jing; Wu, Yadong

    2017-12-01

    Novel red-emitting Ba2Zn1-x-yWO6:xEu3+, yLi+ phosphors were prepared using a high-temperature solid-state method, and the crystal structure, the photoluminescence properties and the doping concentrations of Eu3+ and Li+ were investigated. The results show that these phosphors can be excited by near-ultraviolet light (250-400 nm) and co-doped Li+ can significantly enhance their PL performance. An intense red emission peak at 598 nm (5D0-7F1 transitions) was observed with an excitation wavelength of 316 nm. The CIE chromaticity coordinates of the phosphors are located in the red region, indicating that the BZW:Eu3+, Li+ phosphor holds promise as a red phosphor for near-ultraviolet excited WLEDs.

  16. High-Pressure Synthesis and Characterization of the Ammonium Yttrium Borate (NH4)YB8O14.

    PubMed

    Schmitt, Martin K; Podewitz, Maren; Liedl, Klaus R; Huppertz, Hubert

    2017-11-20

    The first high-pressure yttrium borate (NH 4 )YB 8 O 14 was synthesized at 12.8 GPa/1300 °C using a Walker-type multianvil module. The compound crystallizes in the orthorhombic space group Pnma (no. 62) with the lattice parameters a = 17.6375(9), b = 10.7160(5), and c = 4.2191(2) Å. (NH 4 )YB 8 O 14 constitutes a novel structure type but exhibits similarities to the crystal structure of β-BaB 4 O 7 . X-ray single-crystal and powder diffraction, EDX, vibrational spectroscopy as well as quantum chemical calculations were used to characterize (NH 4 )YB 8 O 14 .

  17. Preparation and Dielectric Measurements of the Rare Earth Green Phases R2BaCuO(5-x) (R = Y, Sm, Gd, Dy, Ho, Er, Yb)

    NASA Technical Reports Server (NTRS)

    Gonzalez-Titman, Carlos

    1994-01-01

    It has been demonstrated that R2BaCuO(5-x) (R = Y, Sm, Gd, Dy, Ho, Er, Yb) does not undergo significant densification unless the sintering temperatures are near the incongruent melting point or the sintering times are long. Good quality powders of Y2BaCuO(5-x) have been synthesized by using oxide raw materials or precursors such as acetates and nitrates. The acetates- and the nitrates-derived yttrium green phase resulted in finer particle sizes, acceptable dielectric properties and lower melting temperatures than those processed via oxide raw materials. The hot pressing technique has been employed to produce a dense R2BaCuO(5-x) (R=Y,Gd) substrate with satisfactory dielectric properties. Reactivity to reducing conditions, i.e. graphite die, limited the optimization of the properties. A high sensitivity to the annealing atmosphere has been demonstrated in Y2BaCuO,.,,. Oxygen treatment at 950 OC has been shown to improve the dielectric properties while treatment in nitrogen, at the same temperature, degraded desirable properties. A high sensitivity to the annealing atmosphere has been demonstrated in Y2BaCuO(5-x). Oxygen treatment at 950 C has been shown to improve the dielectric properties while treatment in nitrogen, at the same temperature, degraded desirable properties. The dielectric constants of the rare earth green phases R2BaCuO(5-x) were found to be low. Relaxation peaks were detected at low temperatures (T less than 150 K) and at high temperatures (150 less than T greater than 420 K). The dielectric losses and conductivities at 77 K were measured to be in the range of 10(exp -4) and 10(exp -12) (Omega-cm)(exp -1), respectively. Many parameters were found to exhibit dependencies on the rare earth cation sizes.

  18. Etude de l'halogénation de EuBa2Cu3O6

    NASA Astrophysics Data System (ADS)

    Tshimanga Kabeya, D.; Mokhtari, M.; Perrin, C.; Sergent, M.; Grushko, Yu.; Kokovina, L.; Rozhniakova, N.

    1994-11-01

    Sintered samples of EuBa2Cu3O6 have been halogenated at low temperature (t < 300 ^circC) by treatments under NF3 or CCl4 flow diluted in nitrogen, or by reaction with iodine in sealed tubes. Such mild conditions of synthesis allowed to avoid the decomposition of the material during the reactions. The incorporation of the halogen in the sample has been evidenced by the weight gain, by the evolution of the unit-cell parameters and by SEM and EDS analyses. After fluorination and chlorination, the samples become superconducting, but no superconducting behaviour is observed after iodination. These results are compared to the ones previously obtained during the halogenation of YBa2Cu3O6. Des échantillons frittés de EuBa2Cu3O6 ont été halogénés à basse température (t < 300 ^circC) par traitement sous courant de NF3 ou de CCl4 dilué dans de l'azote, ou par réaction avec de l'iode en tube scellé. De telles conditions de synthèse ont permis de limiter la décomposition du matériau au cours de la réaction. L'incorporation de l'halogène dans l'échantillon est mise en évidence par variation de masse, par l'évolution des paramètres de maille, par observations au MEB et analyses EDS. Après fluoration et chloration l'échantillon devient supraconducteur, tandis qu'aucun comportement supraconducteur n'est observé après iodation. Ces résultats sont comparés avec ceux qui avaient été obtenus préalablement lors de l'halogénation de YBa2Cu3O6.

  19. Synthesis and morphology of Ba1-xRE2x/3Nb2O6 nanocrystals with tungsten bronze structure in RE2O3-BaO-Nb2O5-B2O3 glasses (RE: Sm, Eu, Gd, Dy, Er)

    NASA Astrophysics Data System (ADS)

    Ida, H.; Shinozaki, K.; Honma, T.; Oh-ishi, K.; Komatsu, T.

    2012-12-01

    Ba1-xRE2x/3Nb2O6 nanocrystals with a tetragonal tungsten bronze (TTB) structure are synthesized using a conventional glass crystallization technique in 2.3RE2O3-27.4BaO-34.3Nb2O5-36B2O3 (mol%) (RE=Sm, Eu, Gd, Dy, and Er) glasses. One sharp crystallization peak is observed at ∼670 °C in both powdered and bulk glasses, and the formation of Ba1-xRE2x/3Nb2O6 nanocrystals with unit cell parameters of a∼1.24 nm and c∼0.39 nm was confirmed. It is found from high resolution transmission electron microscope observations that the morphology of Ba1-xRE2x/3Nb2O6 nanocrystals is ellipsoidal. Their average particle size is in the range of 15-60 nm and decreases with decreasing ionic radius of RE3+ being present in the precursor glasses. The optical transparent crystallized glass (bulk) shows the total photoluminescence (PL) quantum yield of 53% in the visible region of Eu3+ ions, suggesting a high potential of Ba1-xRE2x/3Nb2O6 nanocrystals as PL materials.

  20. Thermally stable green Ba(3)Y(PO(4))3:Ce(3+),Tb(3+) and red Ca(3)Y(AlO)(3)(BO(3))4:Eu(3+) phosphors for white-light fluorescent lamps.

    PubMed

    Huang, Chien-Hao; Kuo, Te-Wen; Chen, Teng-Ming

    2011-01-03

    A class of thermal stable of green-emitting phosphors Ba(3)Y(PO(4))(3):Ce(3+),Tb(3+) (BYP:Ce(3+),Tb(3+)) and red-emitting phosphors Ca(3)Y(AlO)(3)(BO(3))(4):Eu(3+) (CYAB:Eu(3+)) for white-light fluorescent lamps were synthesized by high temperature solid-state reaction. We observed a decay of only 3% at 150 °C for BYP:0.25Ce3+,0.25Tb3+ (3% for LaPO4:Ce(3+),Tb(3+)), and a decay of 4% for CYAB:0.5Eu(3+) (7% for Y(2)O(3):Eu(3+), 24% for Y(2)O(2)S:Eu(3+)). The emission intensity of composition-optimized Ba(3)(Y(0.5)Ce(0.25)Tb(0.25))(PO(4))(3) is 70% of that of commercial LaPO(4):Ce(3+),Tb(3+) phosphors, and the CIE chromaticity coordinates are found to be (0.323, 0.534). The emission intensity of Ca(3)(Y(0.5)Eu(0.5))(AlO)(3)(BO(3))(4) is 70% and 83% of those of Y(2)O(3):Eu(3+) and Y(2)O(2)S:Eu(3+) phosphors, respectively, and the CIE chromaticity coordinates are redder (0.652, 0.342) than those of Y(2)O(3):Eu(3+) (0.645, 0.347) and Y(2)O(2)S:Eu(3+) (0.647, 0.343). A white-light fluorescent lamp is fabricated using composition-optimized Ba(3)(Y(0.5)Ce(0.25)Tb(0.25))(PO(4))(3) and Ca(3)(Y(0.5)Eu(0.5))(AlO)(3)(BO(3))(4) phosphors and matching blue-emitting phosphors. The results indicate that the quality of the brightness and color reproduction is suitable for application in shortwave UV fluorescent lamps. The white-light fluorescent lamp displays CIE chromaticity coordinates of x = 0.33, y = 0.35, a warm white light with a correlated color temperature of 5646 K, and a color-rendering index of Ra = 70.

  1. Analysis of beta-decay rates for Ag 108, Ba 133, Eu 152, Eu 154, Kr 85, Ra 226, and Sr 90, measured at the Physikalisch-Technische Bundesanstalt from 1990 to 1996

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Sturrock, P. A.; Fischbach, E.; Jenkins, J.

    2014-10-10

    We present the results of an analysis of measurements of the beta-decay rates of Ag 108, Ba 133, Eu 152, Eu 154, Kr 85, Ra 226, and Sr 90 acquired at the Physikalisch-Technische Bundesanstalt from 1990 through 1995. Although the decay rates vary over a range of 165 to 1 and the measured detector current varies over a range of 19 to 1, the detrended and normalized count rate measurements exhibit a sinusoidal annual variation with amplitude in the small range 0.068%-0.088% (mean 0.081%, standard deviation 0.0072%, a rejection of the zero-amplitude hypothesis) and phase-of-maximum in the small range 0.062-0.083more » (January 23 to January 30). In comparing these results with those of other related experiments that yield different results, it may be significant that this experiment, at a standards laboratory, seems to be unique in using a 4π detector. These results are compatible with a solar influence, and do not appear to be compatible with an experimental or environmental influence. It is possible that Ba 133 measurements are also subject to a non-solar (possibly cosmic) influence.« less

  2. Metal atom dynamics in superbulky metallocenes: a comparison of (Cp(BIG))2Sn and (Cp(BIG))2Eu.

    PubMed

    Harder, Sjoerd; Naglav, Dominik; Schwerdtfeger, Peter; Nowik, Israel; Herber, Rolfe H

    2014-02-17

    Cp(BIG)2Sn (Cp(BIG) = (4-n-Bu-C6H4)5cyclopentadienyl), prepared by reaction of 2 equiv of Cp(BIG)Na with SnCl2, crystallized isomorphous to other known metallocenes with this ligand (Ca, Sr, Ba, Sm, Eu, Yb). Similarly, it shows perfect linearity, C-H···C(π) bonding between the Cp(BIG) rings and out-of-plane bending of the aryl substituents toward the metal. Whereas all other Cp(BIG)2M complexes show large disorder in the metal position, the Sn atom in Cp(BIG)2Sn is perfectly ordered. In contrast, (119)Sn and (151)Eu Mößbauer investigations on the corresponding Cp(BIG)2M metallocenes show that Sn(II) is more dynamic and loosely bound than Eu(II). The large displacement factors in the group 2 and especially in the lanthanide(II) metallocenes Cp(BIG)2M can be explained by static metal disorder in a plane parallel to the Cp(BIG) rings. Despite parallel Cp(BIG) rings, these metallocenes have a nonlinear Cpcenter-M-Cpcenter geometry. This is explained by an ionic model in which metal atoms are polarized by the negatively charged Cp rings. The extent of nonlinearity is in line with trends found in M(2+) ion polarizabilities. The range of known calculated dipole polarizabilities at the Douglas-Kroll CCSD(T) level was extended with values (atomic units) for Sn(2+) 15.35, Sm(2+)(4f(6) (7)F) 9.82, Eu(2+)(4f(7) (8)S) 8.99, and Yb(2+)(4f(14) (1)S) 6.55. This polarizability model cannot be applied to predominantly covalently bound Cp(BIG)2Sn, which shows a perfectly ordered structure. The bent geometry of Cp*2Sn should therefore not be explained by metal polarizability but is due to van der Waals Cp*···Cp* attraction and (to some extent) to a small p-character component in the Sn lone pair.

  3. A general way of analyzing EPR spectroscopy for a pair of magnetically equivalent lanthanide ions in crystal: A case study of BaY2F8:Yb3+ crystal

    NASA Astrophysics Data System (ADS)

    Liu, Honggang; Zheng, Wenchen

    2018-01-01

    Electron paramagnetic resonance (EPR) is an important tool to study the complex interactions (e.g., exchange and magnetic dipole-dipole interactions) for a pair of lanthanide (Ln) ions in crystals. How to analyze these EPR spectra and obtain the strength of each interaction is a challenge for experimentalists. In this work, a general way of calculating the EPR lines for two magnetically equivalent Ln ions is given by us to solve this problem. In order to explain their EPR spectra and obtain exchange interaction parameters Ji (i = x, y, z) between them, we deduce the analytic formulas for computing the angular dependent EPR lines for such Ln pairs under the condition of weak coupling (|Ji| ≪ hv, where v is the microwave frequency in the EPR experiment) and set up the spin-Hamiltonian energy matrix that should be diagonalized to obtain these lines if intermediate (|Ji| ˜ hv) and strong (|Ji| > hv) couplings are encountered. To verify our method, the experimental EPR spectra for the Yb3+ doped BaY2F8 crystal are considered by us and the EPR lines from the isolated Yb3+ ion and Yb3+-Yb3+ pair with distance R equal to 0.371 nm are identified clearly. Moreover, exchange interaction parameters (Jx ≈ -0.04 cm-1, Jy ≈ -0.24 cm-1, and Jz ≈ -0.1 cm-1) for such a pair are also determined by our calculations. This case study demonstrates that the theoretical method given in this work would be useful and could be applied to understand interactions between Ln ions in crystals.

  4. Photoluminescence of A- and B-site Eu{sup 3+}-substituted (Sr{sub x}Ba{sub 1−x}){sub 2}CaW{sub y}Mo{sub 1−y}O{sub 6} phosphors

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Sletnes, M.; Lindgren, M.; Valmalette, J.C.

    The photoluminescence of two series of A- and B-site Eu{sup 3+} substituted (Sr{sub x}Ba{sub 1−x}){sub 2}CaW{sub y}Mo{sub 1−y}O{sub 6} double perovskite phosphor materials, (Sr{sub x}Ba{sub 1−x}){sub 1.96}Eu{sub 0.02}K{sub 0.02}CaW{sub y}Mo{sub 1−y}O{sub 6} and (Sr{sub x}Ba{sub 1−x}){sub 2}Ca{sub 0.96}Eu{sub 0.02}Li{sub 0.02}W{sub y}Mo{sub 1−y}O{sub 6} (x and y=0, 0.25, 0.50, 0.75, and 1), were studied systematically as a function of stoichiometry and crystal structure. The Eu{sup 3+} lattice sites controlled by co-doping with either K or Li were confirmed by Raman spectroscopy. The variation in integrated emission intensity and emission colour over the experimental matrix was examined using statistical tools, and themore » observed trends were rationalized based on the physical and electronic structure of the phosphors. Phosphors with Eu on B-site with maximum Sr content had remarkably higher emission intensities than all other materials, but the emission was more orange than red due to domination of the {sup 5}D{sub 0}–{sup 7}F{sub 1} (595 nm) transition of Eu{sup 3+}. The relative intensities of the {sup 5}D{sub 0}–{sup 7}F{sub 2} (615 nm) and {sup 5}D{sub 0}–{sup 7}F{sub 1} transitions of Eu{sup 3+}, and thus the red-shift of the emission, decreased linearly with increasing Sr content in the A-site Eu-substituted phosphors, and reached a maximum for Sr{sub 1.96}Eu{sub 0.02}K{sub 0.02}CaW{sub 0.25}Mo{sub 0.75}O{sub 6}. A maximum external quantum efficiency of 17% was obtained for the phosphor Sr{sub 2}Ca{sub 0.7}Eu{sub 0.15}Li{sub 0.15}W{sub 0.5}Mo{sub 0.5}O{sub 6} with Eu on B-site. - Highlights: • Systematic study of the photoluminescence of Eu{sup 3+}-doped (Sr{sub x}Ba{sub 1−x}){sub 2}CaW{sub y}Mo{sub 1−y}O{sub 6}. • The Eu{sup 3+} lattice sites were confirmed by Raman spectroscopy. • A large parameter space was investigated using statistical tools. • A maximum external QE of 17% was obtained for Sr{sub 2}Ca{sub 0.7}Eu{sub 0

  5. Definition of an intramolecular Eu-to-Eu energy transfer within a discrete [Eu2L] complex in solution.

    PubMed

    Nonat, Aline; Regueiro-Figueroa, Martín; Esteban-Gómez, David; de Blas, Andrés; Rodríguez-Blas, Teresa; Platas-Iglesias, Carlos; Charbonnière, Loïc J

    2012-06-25

    Ligand L, based on two do3a moieties linked by the methylene groups of 6,6'-dimethyl-2,2'-bipyridine, was synthesized and characterized. The addition of Ln salts to an aqueous solution of L (0.01 M Tris-HCl, pH 7.4) led to the successive formation of [LnL] and [Ln(2)L] complexes, as evidenced by UV/Vis and fluorescence titration experiments. Homodinuclear [Ln(2)L] complexes (Ln = Eu, Gd, Tb, Yb, and Lu) were prepared and characterized. The (1)H and (13)C NMR spectra of the Lu and Yb complexes in D(2)O solution (pD = 7.0) showed C(1) symmetry of these species in solution, pointing to two different chemical environments for the two lanthanide cations. The analysis of the chemical shifts of the Yb complex indicated that the two coordination sites present square antiprismatic (SAP) coordination environments around the metal ions. The spectroscopic properties of the [Tb(2)L] complex upon ligand excitation revealed conventional behavior with τ(H2O) = 2.05(1) ms and ϕ(H2O) = 51%, except for the calculation of the hydration number obtained from the luminescent lifetimes in H(2)O and D(2)O, which pointed to a non-integer value of 0.6 water molecules per Tb(III) ion. In contrast, the Eu complex revealed surprising features such as: 1) the presence of two and up to five components in the (5)D(0)→(7)F(0) and (5)D(0)→(7)F(1) emission bands, respectively; 2) marked differences between the normalized spectra obtained in H(2)O and D(2)O solutions; and 3) unconventional temporal evolution of the luminescence intensity at certain wavelengths, the intensity profile first displaying a rising step before the occurrence of the expected decay. Additional spectroscopic experiments performed on [Gd(2-x)Eu(x)L] complexes (x = 0.1 and 1.9) confirmed the presence of two distinct Eu sites with hydration numbers of 0 (site I) and 2 (site II), and showed that the unconventional temporal evolution of the emission intensity is the result of an unprecedented intramolecular Eu-to-Eu

  6. Mn2+ concentration manipulated red emission in BaMg2Si2O7:Eu2+,Mn2+

    NASA Astrophysics Data System (ADS)

    Ye, Song; Zhang, Jiahua; Zhang, Xia; Lu, Shaozhe; Ren, Xinguang; Wang, Xiaojun

    2007-02-01

    The luminescent properties of concentration dependence are reported in BaMg2Si2O7:Eu2+,Mn2+ red phosphor. It is observed that the broad red emission of Mn2+ consists of two bands, located at 620 and 675 nm, respectively, which are attributed to two different Mn2+ centers [Mn2+(I) and Mn2+(II)] substituting for two nonidentical Mg2+ sites [Mg2+(I) and Mg2+(II)] in the host. It is also found that the relative emission intensity of the Mn2+(II) to the Mn2+(I) increases with increasing Mn2+ concentration, leading to a red-shift of the overall emission. A detail analysis on the energy transfer from Eu2+ to the two Mn2+ centers is presented, which indicates that the number ratio of Mn2+(II) to Mn2+(I) increases with increasing Mn2+ concentration. This result is interpreted by the preferential formation of Mn2+(I) substituting for Mg2+(I) site. Based on energy transfer, the emission intensity ratios of Mn2+(I) to Eu2+ and Mn2+(II) to Eu2+, which is Mn2+ concentration dependent, are calculated using related fluorescence lifetimes. The calculated results are in good agreement with that obtained experimentally in the emission spectra.

  7. Synthesis, crystal structure, and magnetism of A 2Co 12As 7 (A=Ca, Y, Ce–Yb)

    DOE PAGES

    Tan, Xiaoyan; Ovidiu Garlea, V.; Chai, Ping; ...

    2015-08-28

    In this study, ternary intermetallics, A 2Co 12As 7 (A=Ca, Y, Ce–Yb), have been synthesized by annealing mixtures of elements in molten Bi at 1223 K. The materials obtained crystallize in the P6 3/m variant of the Zr 2Fe 12P 7 structure type. The unit cell volume shows a monotonic decrease with the increasing atomic number of the rare-earth metal, with the exception of Ce-, Eu-, and Yb-containing compounds. An examination of these outliers with X-ray absorption near edge structures (XANES) spectroscopy revealed mixed valence of Ce, Eu, and Yb, with the average oxidation states of +3.20(1), +2.47(5), and +2.91(1),more » respectively, at room temperature. Magnetic behavior of A 2Co 12As 7 is generally characterized by ferromagnetic ordering of Co 3d moments at 100–140 K, followed by low-temperature ordering of rare-earth 4f moments. The 3d-4f magnetic coupling changes from antiferromagnetic for A=Pr–Sm to ferromagnetic for A=Ce and Eu–Yb. Finally, polarized neutron scattering experiments were performed to support the postulated ferro- and ferrimagnetic ground states for Ce 2Co 12As 7 and Nd 2Co 12As 7, respectively.« less

  8. Crystal structure and magnetism of layered perovskites compound EuBaCuFeO5

    NASA Astrophysics Data System (ADS)

    Lal, Surender; Mukherjee, K.; Yadav, C. S.

    2018-04-01

    Layered perovskite compounds have interesting multiferroic properties.YBaCuFeO5 is one of the layered perovskite compounds which have magnetic and dielectric transition above 200 K. The multiferroic properties can be tuned with the replacement of Y with some other rare earth ions. In this manuscript, structural and magnetic properties of layered perovskite compound EuBaCuFeO5 have been investigated. This compound crystallizes in the tetragonal structure with P4mm space group and is iso-structural with YBaCuFeO5. The magnetic transition has been found to shift to 120 K as compared to YBaCuFeO5 which has the transition at 200 K. This shift in the magnetic transition has been ascribed to the decrease in the chemical pressure that relaxes the magnetic moments.

  9. Monolithic translucent BaMgAl 10O 17:Eu 2+ phosphors for laser-driven solid state lighting

    DOE PAGES

    Cozzan, Clayton; Brady, Michael J.; O’Dea, Nicholas; ...

    2016-10-11

    With high power light emitting diodes and laser diodes being explored for white light generation and visible light communication, thermally robust encapsulation schemes for color-converting inorganic phosphors are essential. In the current work, the canonical blue-emitting phosphor, high purity Eu-doped BaMgAl 10O 17, has been prepared using microwave-assisted heating (25 min) and densified into translucent ceramic phosphor monoliths using spark plasma sintering (30 min). Lastly, the resulting translucent ceramic monoliths convert UV laser light to blue light with the same efficiency as the starting powder and provide superior thermal management in comparison with silicone encapsulation.

  10. Electronic structure of the gold/Bi2Sr2CaCu2O8 and gold/EuBa2Cu3O7 - delta interfaces as studied by photoemission spectroscopy

    NASA Astrophysics Data System (ADS)

    Dessau, D. S.; Shen, Z.-X.; Wells, B. O.; Spicer, W. E.; List, R. S.; Arko, A. J.; Bartlett, R. J.; Fisk, Z.; Cheong, S.-W.; Mitzi, D. B.; Kapitulnik, A.; Schirber, J. E.

    1990-07-01

    High-resolution photoemission has been used to probe the electronic structure of the gold/Bi2Sr2CaCu2O8 and gold/EuBa2Cu3O7-δ interface formed by a low-temperature (20 K) gold evaporation on cleaved high quality single crystals. We find that the metallicity of the EuBa2Cu3O7-δ substrate in the near surface region (˜5 Å) is essentially destroyed by the gold deposition, while the near surface region of Bi2Sr2CaCu2O8 remains metallic. This has potentially wide ranging consequences for the applicability of the different types of superconductors in real devices.

  11. Synthesis and effect of Sr substitution on fluorescence of new Ba 2-xSr xZnS 3: Eu 2+ red phosphor: Considerable enhancement of emission intensity

    NASA Astrophysics Data System (ADS)

    Lee, Chi-Woo; Petrykin, Valery; Kakihana, Masato

    2009-01-01

    A series of 0.5 mol% Eu 2+-activated Ba 2-xSr xZnS 3 phosphor materials were synthesized using precursors prepared by the polymerizable complex method and their fluorescent properties were studied for the first time. It was found that Sr substitution for Ba leads to the considerable improvement of internal quantum efficiency and emission intensity in these materials compared to Ba 2ZnS 3, while emission peak wavelength exhibits a blue shift from 680 to 660 nm. Rietveld refinement of crystal structure of sample with x=0.7 suggests that Sr ions preferentially occupy one of two Ba sites in this compound. Such a structural re-arrangement might be responsible for the observed quantum efficiency dependence on Sr concentration.

  12. Yb3+ can be much better than Dy3+: SMM properties and controllable self-assembly of novel lanthanide 3,5-dinitrobenzoate-acetylacetonate complexes.

    PubMed

    Gavrikov, Andrey V; Efimov, Nikolay N; Ilyukhin, Andrey B; Dobrokhotova, Zhanna V; Novotortsev, Vladimir M

    2018-05-01

    The first representatives of the binuclear lanthanide 3,5-dinitrobenzoate-acetylacetonate complexes, namely isostructural compounds [Ln(dnbz)(acac)2(H2O)(EtOH)]2 (Ln = Eu (1), Gd (2), Tb (3), Dy (4), Ho (5), Er (6), Tm (7), and Yb (8); dnbz - 3,5-dinitrobenzoate anion; acac - acetylacetonate (pentane-2,4-dionate) anion) were prepared and characterized. The SMM behavior of the Yb compound 8 was shown to be surprisingly less sensitive to the composition of the Yb3+ coordination environment in comparison with that of the Dy derivative. For Yb compound 8, the anisotropy barrier is Δeff/kB = 26 K under the dc field of 2000 Oe. This value is the highest one currently known for binuclear Yb complexes.

  13. Trap Depth Engineering of SrSi2O2N2:Ln2+,Ln3+ (Ln2+ = Yb, Eu; Ln3+ = Dy, Ho, Er) Persistent Luminescence Materials for Information Storage Applications.

    PubMed

    Zhuang, Yixi; Lv, Ying; Wang, Le; Chen, Wenwei; Zhou, Tian-Liang; Takeda, Takashi; Hirosaki, Naoto; Xie, Rong-Jun

    2018-01-17

    Deep-trap persistent luminescence materials exhibit unique properties of energy storage and controllable photon release under additional stimulation, allowing for both wavelength and intensity multiplexing to realize high-capacity storage in the next-generation information storage system. However, the lack of suitable persistent luminescence materials with deep traps is the bottleneck of such storage technologies. In this study, we successfully developed a series of novel deep-trap persistent luminescence materials in the Ln 2+ /Ln 3+ -doped SrSi 2 O 2 N 2 system (Ln 2+ = Yb, Eu; Ln 3+ = Dy, Ho, Er) by applying the strategy of trap depth engineering. Interestingly, the trap depth can be tailored by selecting different codopants, and it monotonically increases from 0.90 to 1.18 eV in the order of Er, Ho, and Dy. This is well explained by the energy levels indicated in the host-referred binding energy scheme. The orange-red-emitting SrSi 2 O 2 N 2 :Yb,Dy and green-emitting SrSi 2 O 2 N 2 :Eu,Dy phosphors are demonstrated to be good candidates of information storage materials, which are attributed to their deep traps, narrow thermoluminescence glow bands, high emission efficiency, and excellent chemical stability. This work not only validates the suitability of deep-trap persistent luminescence materials in the information storage applications, but also broadens the avenue to explore such kinds of new materials for applications in anticounterfeiting and advanced displays.

  14. White-emission in single-phase Ba2Gd2Si4O13:Ce3 +,Eu2 +,Sm3 + phosphor for white-LEDs

    NASA Astrophysics Data System (ADS)

    Jiang, Xiumin; Zhang, Yuqian; Zhang, Jia

    2018-03-01

    To develop new white-light-emitting phosphor, a series of Ce3 +-Eu2 +-Sm3 + doped Ba2Gd2Si4O13 (BGS) phosphors were prepared by the solid-state reaction method, and their photoluminescence properties were studied. The Ce3 + and Eu2 + single-doped BGS show broad emission bands around in the region of 350-550 and 420-650 nm, respectively. By co-doping Ce3 +-Eu2 + into BGS, the energy transfer (ET) from Ce3 + to Eu2 + is inefficient, which could be due to the competitive absorption between the two activator ions. The Sm3 +-activated BGS exhibits an orangey-red emission in the region of 550-750 nm. To achieve white emission, the BGS:0.06Ce3 +,0.04Eu2 +,ySm3 + (0 ≤ y ≤ 0.18) phosphors were designed, in which the ET from Ce3 +/Eu2 + to Sm3 + was observed. The emission color can be tuned by controlling the Sm3 + concentration, and white emission was obtained in the BGS:0.06Ce3 +,0.04Eu2 +,0.06Sm3 + sample. The investigation of thermal luminescence stability for the typical BGS:0.06Ce3 +,0.04Eu2 +,0.06Sm3 + sample reveals that the emission intensities of both Eu2 + and Sm3 + demonstrate continuous decrease but the Ce3 + emission is enhanced gradually with increasing temperature. The corresponding reason has been discussed.

  15. Synthesis and novel luminescence properties of one-dimension BaMoO{sub 4}:Ln{sup 3+} nanostructures

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Wang, Yuping; Li, Mingxia; Pan, Kai

    2015-12-15

    Highlights: • String BaMoO{sub 4}:Ln{sup 3+} nanobeans were prepared by a hydrothermal method. • The Decay dynamics were performed to study the photoluminescence of the BaMoO{sub 4}:Eu{sup 3+} nanobeans. • For BaMoO{sub 4}:Er{sup 3+}/Eu{sup 3+}, the {sup 2}P{sub 3/2} → {sup 4}I{sub 11/2} and {sup 2}H{sub 11/2}/{sup 4}S{sub 3/2} → {sup 4}I{sub 15/2} transitions were observed. - Abstract: String BaMoO{sub 4}:Ln{sup 3+} (Ln = Eu, Tb, Er, and Gd) nanobeans were prepared by a hydrothermal method. The samples were characterized by transmission electron microscope, scanning electron microscope, X-ray diffraction, X-ray photoelectron spectroscope, and Raman spectrometer. Under direct excitation in themore » charge transfer absorption band, concentration quenching phenomenon occurs and decay dynamics were performed to study the photoluminescence of the string BaMoO{sub 4}:Eu{sup 3+} nanobeans. In the emission spectra of BaMoO{sub 4}:Er{sup 3+}/Eu{sup 3+} under 274 nm excitation, the {sup 2}P{sub 3/2} → {sup 4}I{sub 11/2}, {sup 2}H{sub 11/2} → {sup 4}I{sub 15/2}, and {sup 4}S{sub 3/2} → {sup 4}I{sub 15/2} transitions from Er{sup 3+} ions were observed for the first time. In addition, the photoluminescence properties of BaMoO{sub 4}:Tb{sup 3+}/Eu{sup 3+} and BaMoO{sub 4}:Gd{sup 3+}/Eu{sup 3+} were also investigated.« less

  16. New yellow Ba 0.93Eu 0.07Al 2O 4 phosphor for warm-white light-emitting diodes through single-emitting-center conversion

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Li, Xufan; Budai, John D.; Liu, Feng

    2013-01-01

    Phosphor-converted white light-emitting diodes for indoor illumination need to be warm-white (i.e., correlated color temperature <4000 K) with good color rendition (i.e., color rendering index >80). However, no single-phosphor, single-emitting-center-converted white light-emitting diodes can simultaneously satisfy the color temperature and rendition requirements due to the lack of sufficient red spectral component in the phosphors’ emission spectrum. Here, we report a new yellow Ba 0.93Eu 0.07Al 2O 4 phosphor that has a new orthorhombic lattice structure and exhibits a broad yellow photoluminescence band with sufficient red spectral component. Warm-white emissions with correlated color temperature <4000 K and color rendering index >80more » were readily achieved when combining the Ba 0.93Eu 0.07Al 2O 4 phosphor with a blue light-emitting diode (440–470 nm). This study demonstrates that warm-white light-emitting diodes with high color rendition (i.e., color rendering index >80) can be achieved based on single-phosphor, single-emitting-center conversion.« less

  17. Photostimulated luminescence properties of Eu2+ -doped barium aluminate phosphor.

    PubMed

    He, Quanlong; Qiu, Guangyu; Xu, Xuhui; Qiu, Jianbei; Yu, Xue

    2015-03-01

    An intense green photostimulated luminescence in BaAl2 O4 :Eu(2+) phosphor was prepared. The thermoluminescence results indicate that there are at least three types of traps (T1 , T2 , T3 ) with different trap depths in BaAl2 O4 :Eu(2+) phosphor according to the bands located at 327, 361 and 555 K, respectively, which are closely associated with the phosphor's long persistent luminescence and photostimulated luminescence properties. In addition, as a novel optical read-out form, a photostimulated persistent luminescence signal can be repeatedly obtained in BaAl2 O4 :Eu(2+) phosphor. This shows that re-trapping of the electron released from a deep trap plays an important role in photostimulated persistent luminescence. Copyright © 2014 John Wiley & Sons, Ltd.

  18. Hydrogen separation through tailored dual phase membranes with nominal composition BaCe0.8Eu0.2O3-δ:Ce0.8Y0.2O2-δ at intermediate temperatures

    NASA Astrophysics Data System (ADS)

    Ivanova, Mariya E.; Escolástico, Sonia; Balaguer, Maria; Palisaitis, Justinas; Sohn, Yoo Jung; Meulenberg, Wilhelm A.; Guillon, Olivier; Mayer, Joachim; Serra, Jose M.

    2016-11-01

    Hydrogen permeation membranes are a key element in improving the energy conversion efficiency and decreasing the greenhouse gas emissions from energy generation. The scientific community faces the challenge of identifying and optimizing stable and effective ceramic materials for H2 separation membranes at elevated temperature (400-800 °C) for industrial separations and intensified catalytic reactors. As such, composite materials with nominal composition BaCe0.8Eu0.2O3-δ:Ce0.8Y0.2O2-δ revealed unprecedented H2 permeation levels of 0.4 to 0.61 mL·min-1·cm-2 at 700 °C measured on 500 μm-thick-specimen. A detailed structural and phase study revealed single phase perovskite and fluorite starting materials synthesized via the conventional ceramic route. Strong tendency of Eu to migrate from the perovskite to the fluorite phase was observed at sintering temperature, leading to significant Eu depletion of the proton conducing BaCe0.8Eu0.2O3-δ phase. Composite microstructure was examined prior and after a variety of functional tests, including electrical conductivity, H2-permeation and stability in CO2 containing atmospheres at elevated temperatures, revealing stable material without morphological and structural changes, with segregation-free interfaces and no further diffusive effects between the constituting phases. In this context, dual phase material based on BaCe0.8Eu0.2O3-δ:Ce0.8Y0.2O2-δ represents a very promising candidate for H2 separating membrane in energy- and environmentally-related applications.

  19. Chemical data and statistical interpretations for rocks and ores from the Ranger uranium mine, Northern Territory, Australia

    USGS Publications Warehouse

    Nash, J. Thomas; Frishman, David

    1983-01-01

    Analytical results for 61 elements in 370 samples from the Ranger Mine area are reported. Most of the rocks come from drill core in the Ranger No. 1 and Ranger No. 3 deposits, but 20 samples are from unmineralized drill core more than 1 km from ore. Statistical tests show that the elements Mg, Fe, F, Be, Co, Li, Ni, Pb, Sc, Th, Ti, V, CI, As, Br, Au, Ce, Dy, La Sc, Eu, Tb, Yb, and Tb have positive association with uranium, and Si, Ca, Na, K, Sr, Ba, Ce, and Cs have negative association. For most lithologic subsets Mg, Fe, Li, Cr, Ni, Pb, V, Y, Sm, Sc, Eu, and Yb are significantly enriched in ore-bearing rocks, whereas Ca, Na, K, Sr, Ba, Mn, Ce, and Cs are significantly depleted. These results are consistent with petrographic observations on altered rocks. Lithogeochemistry can aid exploration, but for these rocks requires methods that are expensive and not amenable to routine use.

  20. Magnetization and transport properties of single crystalline RPd 2P 2 (R=Y, La–Nd, Sm–Ho, Yb)

    DOE PAGES

    Drachuck, Gil; Böhmer, Anna E.; Bud'ko, Sergey L.; ...

    2016-05-27

    Single crystals of RPd 2P 2 (R=Y, La–Nd, Sm–Ho, Yb) were grown out of a high temperature solution rich in Pd and P and characterized by room-temperature powder X-ray diffraction, anisotropic temperature- and field-dependent magnetization and temperature-dependent in-plane resistivity measurements. In this series, YPd 2P 2 and LaPd 2P 2 YbPd 2P 2 (with Yb 2+) are non-local-moment bearing. Furthermore, YPd 2P 2 and LaPd 2P 2 are found to be superconducting with Tc≃0.75 and 0.96 K respectively. CePd 2P 2 and PrPd 2P 2 magnetically order at low temperature with a ferromagnetic component along the crystallographic c-axis. The rest of the series manifest low temperature antiferromagnetic ordering. EuPd 2P 2 has Eu 2+ ions and both EuPd 2P 2 and GdPd 2P 2 have isotropic paramagnetic susceptibilities consistent with L =0 and J=S=more » $$\\frac{7}{2}$$ and exhibit multiple magnetic transitions. For R=Eu–Dy, there are multiple, T>1.8 K transitions in zero applied magnetic field and for R=Nd, Eu, Gd, Tb, and Dy there are clear metamagnetic transitions at T=2.0 K for H< 55 kOe. Strong anisotropies arising mostly from crystal electric field (CEF) effects were observed for most magnetic rare earths with L≠0. The experimentally estimated CEF parameters B$$_2^0$$ were calculated from the anisotropic paramagnetic θ ab and θ c values and compared to theoretical trends across the rare earth series. Lastly, the ordering temperatures as well as the polycrystalline averaged paramagnetic Curie–Weiss temperature, θ ave, were extracted from magnetization and resistivity measurements, and compared to the de-Gennes factor.« less

  1. Magnetization and transport properties of single crystalline RPd 2P 2 (R=Y, La–Nd, Sm–Ho, Yb)

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Drachuck, Gil; Böhmer, Anna E.; Bud'ko, Sergey L.

    Single crystals of RPd 2P 2 (R=Y, La–Nd, Sm–Ho, Yb) were grown out of a high temperature solution rich in Pd and P and characterized by room-temperature powder X-ray diffraction, anisotropic temperature- and field-dependent magnetization and temperature-dependent in-plane resistivity measurements. In this series, YPd 2P 2 and LaPd 2P 2 YbPd 2P 2 (with Yb 2+) are non-local-moment bearing. Furthermore, YPd 2P 2 and LaPd 2P 2 are found to be superconducting with Tc≃0.75 and 0.96 K respectively. CePd 2P 2 and PrPd 2P 2 magnetically order at low temperature with a ferromagnetic component along the crystallographic c-axis. The rest of the series manifest low temperature antiferromagnetic ordering. EuPd 2P 2 has Eu 2+ ions and both EuPd 2P 2 and GdPd 2P 2 have isotropic paramagnetic susceptibilities consistent with L =0 and J=S=more » $$\\frac{7}{2}$$ and exhibit multiple magnetic transitions. For R=Eu–Dy, there are multiple, T>1.8 K transitions in zero applied magnetic field and for R=Nd, Eu, Gd, Tb, and Dy there are clear metamagnetic transitions at T=2.0 K for H< 55 kOe. Strong anisotropies arising mostly from crystal electric field (CEF) effects were observed for most magnetic rare earths with L≠0. The experimentally estimated CEF parameters B$$_2^0$$ were calculated from the anisotropic paramagnetic θ ab and θ c values and compared to theoretical trends across the rare earth series. Lastly, the ordering temperatures as well as the polycrystalline averaged paramagnetic Curie–Weiss temperature, θ ave, were extracted from magnetization and resistivity measurements, and compared to the de-Gennes factor.« less

  2. Genesis of post-collisional calc-alkaline and alkaline granitoids in Qiman Tagh, East Kunlun, China

    NASA Astrophysics Data System (ADS)

    Yu, Miao; Feng, Chengyou; Zhao, Yiming; Li, Daxin

    2015-12-01

    The post-collisional magmatism of Qiman Tagh is characterized by the intrusion of voluminous intermediate to felsic granitoids, including syenogranite, monzogranite, granodiorite, tonalite and diorite. The granitoids can be divided into two magmatic suites: Calc-alkaline (CA) and alkaline (Alk), which were emplaced from ~ 236 Ma to ~ 204 Ma. The CA suite contains metaluminous granodiorites and monzogranites. Typical Qiman Tagh CA granodiorites show moderately fractionated REE patterns ((La/Yb)N = 4.35-25.11) with significant negative Eu anomalies (Eu/Eu* = 0.54-1.34), and the primitive mantle-normalized spidergrams show strong depletion of Nb and Sr. The Qiman Tagh CA monzogranites show similar fractionated REE patterns ((La/Yb)N = 2.70-13.5) with less prominent negative Eu anomalies, and the chondrite-normalized spidergrams show strongly depleted Ba, Nb and Sr. The Alk suite, including syenogranite, is highly potassic (K2O/Na2O = 1.09-3.56) and peraluminous (A/CNK = 0.91-1.06). Compared to typical Qiman Tagh CA granodiorites, the Qiman Tagh Alk granitoids can be distinguished by their higher Rb, Nb, Ga/Al, FeO*/MgO, Y/Sr and Rb/Sr, as well as their lower Mg#, MgO, CaO, Al2O3, Sr, Co, V, Eu/Eu*, Ba/Nb, La/Nb, Ba/La and Ce/Nb. The Qiman Tagh CA rocks were most likely to be derived from the partial melting of garnet-amphibolite-facies rocks in the lower crust, leaving behind anhydrous granulite-facies rocks with plagioclase and garnet in the residue. The Alk rocks may have formed by the continued partial melting of granulite-facies rocks at elevated temperatures (> 830 °C).

  3. Spectroscopic study and enhanced thermostability of combustion-derived BaMgAl10O17:Eu2+ blue phosphors for solid-state lighting

    NASA Astrophysics Data System (ADS)

    Pradal, Nathalie; Potdevin, Audrey; Chadeyron, Geneviève; Bonville, Pierre; Caillier, Bruno; Mahiou, Rachid

    2017-02-01

    Blue-emitting BaMgAl10O17:Eu2+ (BAM:Eu), suitable for applications in a next generation of Hg-free lamps based on UV LEDs, was prepared by a microwave induced solution combustion synthesis, using urea as combustion fuel and nitrates as oxidizers. Purity control of the as-synthesized blue phosphor was undertaken by a washing step followed by a reduction one. Structural and morphological properties of the outcoming phosphors have been considered. Synthesis process allows producing a well-crystallized and nanostructured BAM phase within only few minutes. The influence of reduction treatment on the relative amounts of Eu2+/Eu3+ in our samples has been investigated through an original study by magnetization and Mössbauer spectroscopy. Furthermore, a complete optical study has been carried out and allowed us to determine the europium localization in the three possible sites in BAM matrix. The percentage of Eu2+ increased twofold after the reduction treatment, entailing an increase in the luminescence efficiency upon UV excitation. Finally, temperature-dependent luminescence of combustion-derived powders has been studied till 170 °C and compared to that of commercial BAM:Eu. MISCS-derived phosphors present a higher thermal stability than commercial one: whereas the emission efficiency of this last was reduced by 64%, the one of combustion-derived BAM:Eu experienced an only 12% decline. Furthermore, while commercial BAM suffered from a severe blue-shift with increasing temperature, our phosphors keep its color quality with a good stability of the photometric parameters.

  4. Novel and easy access to highly luminescent Eu and Tb doped ultra-small CaF2, SrF2 and BaF2 nanoparticles - structure and luminescence.

    PubMed

    Ritter, Benjamin; Haida, Philipp; Fink, Friedrich; Krahl, Thoralf; Gawlitza, Kornelia; Rurack, Knut; Scholz, Gudrun; Kemnitz, Erhard

    2017-02-28

    A universal fast and easy access at room temperature to transparent sols of nanoscopic Eu 3+ and Tb 3+ doped CaF 2 , SrF 2 and BaF 2 particles via the fluorolytic sol-gel synthesis route is presented. Monodisperse quasi-spherical nanoparticles with sizes of 3-20 nm are obtained with up to 40% rare earth doping showing red or green luminescence. In the beginning luminescence quenching effects are only observed for the highest content, which demonstrates the unique and outstanding properties of these materials. From CaF 2 :Eu10 via SrF 2 :Eu10 to BaF 2 :Eu10 a steady increase of the luminescence intensity and lifetime occurs by a factor of ≈2; the photoluminescence quantum yield increases by 29 to 35% due to the lower phonon energy of the matrix. The fast formation process of the particles within fractions of seconds is clearly visualized by exploiting appropriate luminescence processes during the synthesis. Multiply doped particles are also available by this method. Fine tuning of the luminescence properties is achieved by variation of the Ca-to-Sr ratio. Co-doping with Ce 3+ and Tb 3+ results in a huge increase (>50 times) of the green luminescence intensity due to energy transfer Ce 3+ → Tb 3+ . In this case, the luminescence intensity is higher for CaF 2 than for SrF 2 , due to a lower spatial distance of the rare earth ions.

  5. DOE Office of Scientific and Technical Information (OSTI.GOV)

    Jia, Li-Ping; Zhang, Qiang; State Key Laboratory of Pollution Control and Resource Reuse

    Graphical abstract: Lanthanide ions doped bare earth rare earth fluoride nanocrystals are synthesized by hydrothermal technology and characterized. The down/up-conversion luminescence of them are discussed. - Highlights: • Mixed hydrothermal system H{sub 2}O–OA (EDA)–O-A(LO-A) is used for synthesis. • Barium rare earth fluoride nanocrystals are synthesized comprehensively. • Luminescence for down-conversion and up-conversion are obtained for these systems. - Abstract: Mixed hydrothermal system H{sub 2}O–OA (EDA)–O-A(LO-A) is developed to synthesize barium rare earth fluorides nanocrystals (OA = oleylamine, EDA = ethylenediamine, O-A = oleic acid and LO-A = linoleic acid). They are presented as BaREF{sub 5} (RE = Ce, Pr,more » Nd, Eu, Gd, Tb, Dy, Y, Tm, Lu) and Ba{sub 2}REF{sub 7} (RE = La, Sm, Ho, Er, Yb). The influence of reaction parameters (rare earth species, hydrothermal system and temperature) is checked on the phase and shape evolution of the fluoride nanocrystals. It is found that reaction time and temperature of these nanocrystals using EDA (180 °C, 6 h) is lower than those of them using OA (220 °C, 10 h). The photoluminescence properties of these fluorides activated by some rare earth ions (Nd{sup 3+}, Eu{sup 3+}, Tb{sup 3+}) are studied, and especially up-conversion luminescence of the four fluoride nanocrystal systems (Ba{sub 2}LaF{sub 7}:Yb, Tm(Er), Ba{sub 2}REF{sub 7}:Yb, Tm(Er) (RE = Gd, Y, Lu)) is observed.« less

  6. High-Throughput Synthesis and Characterization of Eu Doped Ba xSr2- xSiO4 Thin Film Phosphors.

    PubMed

    Frost, Sara; Guérin, Samuel; Hayden, Brian E; Soulié, Jean-Philippe; Vian, Chris

    2018-06-20

    High-throughput techniques have been employed for the synthesis and characterization of thin film phosphors of Eu-doped Ba x Sr 2- x SiO 4 . Direct synthesis from evaporation of the constituent elements under a flux of atomic oxygen on a sapphire substrate at 850 °C was used to directly produce thin film libraries (415 nm thickness) of the crystalline orthosilicate phase with the desired compositional variation (0.24 > x > 1.86). The orthosilicate phase could be synthesized as a pure, or predominantly pure, phase. Annealing the as synthesized library in a reducing atmosphere resulted in the reduction of the Eu while retaining the orthosilicate phase, and resulted in a materials thin film library where fluorescence excited by blue light (450 nm) was observable by the naked eye. Parallel screening of the fluorescence from the combinatorial libraries of Eu doped Ba x Sr 2- x SiO 4 has been implemented by imaging the fluorescent radiation over the library using a monochrome digital camera using a series of color filters. Informatics tools have been developed to allow the 1931 CIE color coordinates and the relative quantum efficiencies of the materials library to be rapidly assessed and mapped against composition, crystal structure and phase purity. The range of compositions gave values of CIE x between 0.17 and 0.52 and CIE y between 0.48 and 0.69 with relative efficiencies in the range 2.0 × 10 -4 -7.6 × 10 -4 . Good agreement was obtained between the thin film phosphors and the fluorescence characteristics of a number of corresponding bulk phosphor powders. The thermal quenching of fluorescence in the thin film libraries was also measured in the temperature range 25-130 °C: The phase purity of the thin film was found to significantly influence both the relative quantum efficiency and the thermal quenching of the fluorescence.

  7. The laser-diode-excited 5 d-4 f luminescence of Ce3+ and Pr3+ ions embedded into a BaR2F8 matrix

    NASA Astrophysics Data System (ADS)

    Pushkar', A. A.; Uvarova, T. V.; Kozlova, N. S.; Kuznetsov, S. Yu.; Uvarova, A. G.

    2013-06-01

    We show the possibility of obtaining UV luminescence from 5 d-4 f transitions of rare-earth ions in the BaY2F8: (Yb3+, Pr3+, Ce3+) crystal under upconversion excitation by standard laser diodes with lasing wavelengths of 960, 808, and 840 nm. Various upconversion mechanisms of pumping for populating the higher-lying energy levels of the active ions, as well as methods of adaptation of the active medium BaY2F8: (Yb3+, Pr3+, Ce3+) to these mechanisms, are considered.

  8. Flux pinning forces in irradiated a-axis oriented EuBa{sub 2}Cu{sub 3}O{sub 7} films

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Martin, J. I.; Gonzalez, E. M.; Kwok, W.-K

    1999-10-12

    {alpha}-axis oriented EuBa{sub 2}Cu{sub 3}O{sub 7} films have been irradiated with high energy heavy ions in different configurations to study the possible pinning role of the artificial defects in this kind of samples. The original pinning limiting mechanism of the samples is not essentially altered what the irradiation is parallel to the CuO{sub 2} planes. However, when it is deviated from this direction, an increase in critical current density and a change in pinning force are observed when the magnetic field is parallel to the columnar defects at values around the matching field.

  9. DEPENDENCE OF THE Sr-TO-Ba AND Sr-TO-Eu RATIO ON THE NUCLEAR EQUATION OF STATE IN METAL-POOR HALO STARS

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Famiano, M. A.; Kajino, T.; Aoki, W.

    A model is proposed in which the dependence on the equation of state (EOS) of the scatter of [Sr/Ba] in metal-poor stars is studied. Light r-process element enrichment in these stars has been explained via a truncated r-process, or “tr-process.” The truncation of the r-process from a generic core-collapse event followed by a collapse into an accretion-induced black hole is examined in the framework of a galactic chemical evolution model. The constraints on this model imposed by observations of extremely metal-poor stars are explained, and the upper limits in the [Sr/Ba] distributions are found to be related to the nuclearmore » EOS in a collapse scenario. The scatter in [Sr/Ba] and [Sr/Eu] as a function of metallicity has been found to be consistent with turbulent ejection in core-collapse supernovae. Adaptations of this model are evaluated to account for the scatter in isotopic observables. This is done by assuming mixing in ejecta in a supernova event. Stiff EOS are eliminated by this model.« less

  10. Electronic structure of ferromagnetic heavy fermion, YbPdSi, YbPdGe, and YbPtGe studied by photoelectron spectroscopy, x-ray emission spectroscopy, and DFT + DMFT calculations

    DOE PAGES

    Yamaoka, Hitoshi; Thunstrom, Patrik; Tsujii, Naohito; ...

    2017-11-02

    Here, the electronic structures of ferromagnetic heavy fermion Yb compounds of YbPdSi, YbPdGe, and YbPtGe are studied by photoelectron spectroscopy around the Yb 4d–4f resonance, resonant x-ray emission spectroscopy at the Yb L 3 absorption edge, and density functional theory combined with dynamical mean field theory calculations. These compounds all have a temperature-independent intermediate Yb valence with largemore » $${\\rm Yb}^{3+}$$ and small $${\\rm Yb}^{2+}$$ components. The magnitude of the Yb valence is evaluated to be YbPtGe $<$ YbPdGe $$\\lesssim $$ YbPdSi, suggesting that YbPtGe is the closest to the quantum critical point among the three Yb compounds. Our results support the scenario of the coexistence of heavy fermion behavior and ferromagnetic ordering which is described by a magnetically-ordered Kondo lattice where the magnitude of the Kondo effect and the RKKY interaction are comparable.« less

  11. Electronic structure of ferromagnetic heavy fermion, YbPdSi, YbPdGe, and YbPtGe studied by photoelectron spectroscopy, x-ray emission spectroscopy, and DFT + DMFT calculations

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Yamaoka, Hitoshi; Thunstrom, Patrik; Tsujii, Naohito

    Here, the electronic structures of ferromagnetic heavy fermion Yb compounds of YbPdSi, YbPdGe, and YbPtGe are studied by photoelectron spectroscopy around the Yb 4d–4f resonance, resonant x-ray emission spectroscopy at the Yb L 3 absorption edge, and density functional theory combined with dynamical mean field theory calculations. These compounds all have a temperature-independent intermediate Yb valence with largemore » $${\\rm Yb}^{3+}$$ and small $${\\rm Yb}^{2+}$$ components. The magnitude of the Yb valence is evaluated to be YbPtGe $<$ YbPdGe $$\\lesssim $$ YbPdSi, suggesting that YbPtGe is the closest to the quantum critical point among the three Yb compounds. Our results support the scenario of the coexistence of heavy fermion behavior and ferromagnetic ordering which is described by a magnetically-ordered Kondo lattice where the magnitude of the Kondo effect and the RKKY interaction are comparable.« less

  12. Rare earth element abundances in presolar SiC

    NASA Astrophysics Data System (ADS)

    Ireland, T. R.; Ávila, J. N.; Lugaro, M.; Cristallo, S.; Holden, P.; Lanc, P.; Nittler, L.; Alexander, C. M. O'D.; Gyngard, F.; Amari, S.

    2018-01-01

    Individual isotope abundances of Ba, lanthanides of the rare earth element (REE) group, and Hf have been determined in bulk samples of fine-grained silicon carbide (SiC) from the Murchison CM2 chondrite. The analytical protocol involved secondary ion mass spectrometry with combined high mass resolution and energy filtering to exclude REE oxide isobars and Si-C-O clusters from the peaks of interest. Relative sensitivity factors were determined through analysis of NIST SRM reference glasses (610 and 612) as well as a trace-element enriched SiC ceramic. When normalised to chondrite abundances, the presolar SiC REE pattern shows significant deficits at Eu and Yb, which are the most volatile of the REE. The pattern is very similar to that observed for Group III refractory inclusions. The SiC abundances were also normalised to s-process model predictions for the envelope compositions of low-mass (1.5-3 M⊙) AGB stars with close-to-solar metallicities (Z = 0.014 and 0.02). The overall trace element abundances (excluding Eu and Yb) appear consistent with the predicted s-process patterns. The depletions of Eu and Yb suggest that these elements remained in the gas phase during the condensation of SiC. The lack of depletion in some other moderately refractory elements (like Ba), and the presence of volatile elements (e.g. Xe) indicates that these elements were incorporated into SiC by other mechanisms, most likely ion implantation.

  13. Electronic Spectra of Cs2NaYb(NO2)6: Is There Quantum Cutting?

    PubMed

    Luo, Yuxia; Liu, Zhenyu; Hau, Sam Chun-Kit; Yeung, Yau Yuen; Wong, Ka-Leung; Shiu, Kwok Keung; Chen, Xueyuan; Zhu, Haomiao; Bao, Guochen; Tanner, Peter A

    2018-05-03

    The crystal structure and electronic spectra of the T h symmetry hexanitritoytterbate(III) anion have been studied in Cs 2 NaY 0.96 Yb 0.04 (NO 2 ) 6 , which crystallizes in the cubic space group Fm3̅. The emission from Yb 3+ can be excited via the NO 2 - antenna. The latter electronic transition is situated at more than twice the energy of the former, but at room temperature, one photon absorbed at 470 nm in the triplet state produces no more than one photon emitted. Some degree of quantum cutting is observed at 298 K under 420 nm excitation into the singlet state and at 25 K using excitation into either state. The quantum efficiency is ∼10% at 25 K. The energy level scheme of Yb 3+ has been deduced from excitation and emission spectra and calculated by crystal field theory. New improved energy level calculations are also reported for the Cs 2 NaLn(NO 2 ) 6 (Ln = Pr, Eu, Tb) series using the f- Spectra package. The neat crystal Cs 2 NaYb(NO 2 ) 6 has also been studied, but results were unsatisfactory due to sample decomposition, and this chemical instability makes it unsuitable for applications.

  14. Coordination geometries of solvated lanthanide(II) ions: Molecular structures of the cationic species [(DIME)[sub 3]Ln][sup 2+] (DIME = diethylene glycol dimethyl ether; Ln[sup 2+] = Sm, Yb), [(DIME)[sub 2]Yb(CH[sub 3]CN)[sub 2

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    White, J.P. III; Deng, H.; Boyd, E.P.

    1994-04-13

    The first lanthanide(II) cationic species with coordination numbers 7,8, and 9 have been structurally characterized. Mercury amalgams of the elemental lanthanides (Ln(Hg) where Ln = Sm, Eu, Yb) cleanly reduce Mn[sub 2](CO)[sub 10] and Co[sub 2](CO)[sub 8] in polydentate ethers to [Mn(CO)[sub 5

  15. Enhanced performance of Cr,Yb:YAG microchip laser by bonding Yb:YAG crystal.

    PubMed

    Cheng, Ying; Dong, Jun; Ren, Yingying

    2012-10-22

    Highly efficient, laser-diode pumped Yb:YAG/Cr,Yb:YAG self-Q-switched microchip lasers by bonding Yb:YAG crystal have been demonstrated for the first time to our best knowledge. The effect of transmission of output coupler (T(oc)) on the enhanced performance of Yb:YAG/Cr,Yb:YAG microchip lasers has been investigated and found that the best laser performance was achieved with T(oc) = 50%. Slope efficiency of over 38% was achieved. Average output power of 0.8 W was obtained at absorbed pump power of 2.5 W; corresponding optical-to-optical efficiency of 32% was obtained. Laser pulses with pulse width of 1.68 ns, pulse energy of 12.4 μJ, and peak power of 7.4 kW were obtained. The lasers oscillated in multi-longitudinal modes. The wide separation of longitudinal modes was attributed to the mode selection by combined etalon effect of Cr,Yb:YAG, Yb:YAG thin plates and output coupler. Stable periodical pulse trains at different pump power levels have been observed owing to the longitudinal modes coupling and competition.

  16. Cation-Poor Complex Metallic Alloys in Ba(Eu)-Au-Al(Ga) Systems: Identifying the Keys that Control Structural Arrangements and Atom Distributions at the Atomic Level.

    PubMed

    Smetana, Volodymyr; Steinberg, Simon; Mudryk, Yaroslav; Pecharsky, Vitalij; Miller, Gordon J; Mudring, Anja-Verena

    2015-11-02

    Four complex intermetallic compounds BaAu(6±x)Ga(6±y) (x = 1, y = 0.9) (I), BaAu(6±x)Al(6±y) (x = 0.9, y = 0.6) (II), EuAu6.2Ga5.8 (III), and EuAu6.1Al5.9 (IV) have been synthesized, and their structures and homogeneity ranges have been determined by single crystal and powder X-ray diffraction. Whereas I and II originate from the NaZn13-type structure (cF104-112, Fm3̅c), III (tP52, P4/nbm) is derived from the tetragonal Ce2Ni17Si9-type, and IV (oP104, Pbcm) crystallizes in a new orthorhombic structure type. Both I and II feature formally anionic networks with completely mixed site occupation by Au and triel (Tr = Al, Ga) atoms, while a successive decrease of local symmetry from the parental structures of I and II to III and, ultimately, to IV correlates with increasing separation of Au and Tr on individual crystallographic sites. Density functional theory-based calculations were employed to determine the crystallographic site preferences of Au and the respective triel element to elucidate reasons for the atom distribution ("coloring scheme"). Chemical bonding analyses for two different "EuAu6Tr6" models reveal maximization of the number of heteroatomic Au-Tr bonds as the driving force for atom organization. The Fermi levels fall in broad pseudogaps for both models allowing some electronic flexibility. Spin-polarized band structure calculations on the "EuAu6Tr6" models hint to singlet ground states for europium and long-range magnetic coupling for both EuAu6.2Ga5.8 (III) and EuAu6.1Al5.9 (IV). This is substantiated by experimental evidence because both compounds show nearly identical magnetic behavior with ferromagnetic transitions at TC = 6 K and net magnetic moments of 7.35 μB/f.u. at 2 K. The effective moments of 8.3 μB/f.u., determined from Curie-Weiss fits, point to divalent oxidation states for europium in both III and IV.

  17. Growth and luminescent properties of Yb:YAG and Ca co-doped Yb:YAG ultrafast scintillation crystals

    NASA Astrophysics Data System (ADS)

    Zhu, Maodong; Qi, Hongji; Pan, Mingyan; Hou, Qing; Jiang, Benxue; Jin, Yaxue; Han, Hetong; Song, Zhaohui; Zhang, Hui

    2018-05-01

    In this work, Yb-doped Y3Al5O12 [yttrium aluminum garnet (YAG)] crystals and Ca co-doped Yb:YAG crystals were grown by the Czochralski (CZ) method. The chemical formulas of the two crystals are (Yb0.1Y0.9)3Al5O12 and (Ca0.001Yb0.1Y0.899)3Al5O12, respectively. The structural, optical and luminescent properties of the Yb:YAG and Ca, Yb:YAG crystals were investigated by X-ray rocking curve, X-ray diffraction, Raman spectra, UV-Visble-NIR absorption spectra and X-ray fluorescence. X-ray fluorescence spectrum with two emission peaks at 330 nm and 490 nm were observed in the two kinds of crystals, which would increase slightly after the annealing. Comparing to the Yb:YAG crystal, Ca co-doped Yb:YAG crystal behaved the better luminescent intensity without changing the crystal structure and vibrational modes. This indicates that by doping Ca2+ in Yb:YAG crystal may be an appropriate way to enhance the luminescent property of the scintillation crystal.

  18. Luminescence studies of a combustion-synthesized blue-green BaAlxOy:Eu2+,Dy3+ nanoparticles

    NASA Astrophysics Data System (ADS)

    Bem, Daniel B.; Dejene, F. B.; Luyt, A. S.; Swart, H. C.

    2012-05-01

    Blue-green emitting BaAlxOy:Eu2+,Dy3+ phosphor was synthesized by the combustion method. The influence of various parameters on the structural, photoluminescence (PL) and thermoluminescence (TL) properties of the phosphor were investigated by various techniques. Phosphor nanocrystallites with high brightness were obtained without significantly changing the crystalline structure of the host. In the PL studies, broad-band excitation and emission spectra were observed with major peaks at 340 and 505 nm, respectively. The observed afterglow is ascribed to the generation of suitable traps due to the presence of the co-doped Dy3+ ions. Though generally broad, the peak structure of the TL glow curves obtained after irradiation with UV light was non-uniform with suggesting the contribution to afterglow from multiple events at the luminescent centers. Further insight on the afterglow behavior of the phosphor was deduced from TL decay results.

  19. Synthesis and photoluminescence of EuII in barium zinc orthosilicate: a novel green color emitting phosphor for white-LEDs.

    PubMed

    Kasturi, S; Sivakumar, V; Varadaraju, U V

    2017-05-01

    A series of Eu 2+ -activated barium orthosilicates (BaZnSiO 4 ) were synthesized using a high-temperature solid-state reaction. A photoluminescence excitation study of Eu 2 + shows a broad absorption band in the range of 270-450 nm, with multiple absorption peak maxima (310, 350 and 400 nm) due to 4f-5d electronic transition. The emission spectra of all the compositions show green color emission (in the spectral region 450-550 nm with a peak maximum at 502 nm and a shoulder at ~ 490 nm) with appropriate Comission Internationale de l'Eclairage (CIE) color coordinates. The two emission peaks are due to the presence of Eu 2 + in two different Ba sites in the BaZnSiO 4 host lattice. The energy transfers between the Eu 2 + ions in BaZnSiO 4 host are elucidated from the critical concentration quenching data based on the electronic multipolar interaction. All Eu 2 + -activated BaZnSiO 4 phosphor materials can be efficiently excited in the ultraviolet (UV) to near UV-region (270-420 nm), making them attractive candidate as a green phosphor for solid state lighting-white light-emitting diodes. Copyright © 2016 John Wiley & Sons, Ltd.

  20. Cation-poor complex metallic alloys in Ba(Eu)–Au–Al(Ga) systems: Identifying the keys that control structural arrangements and atom distributions at the atomic level

    DOE PAGES

    Smetana, Volodymyr; Steinberg, Simon; Mudryk, Yaroslav; ...

    2015-10-19

    Four complex intermetallic compounds BaAu 6±xGa 6±y (x = 1, y = 0.9) (I), BaAu 6±xAl 6±y (x = 0.9, y = 0.6) (II), EuAu 6.2Ga 5.8 (III), and EuAu 6.1Al 5.9 (IV) have been synthesized, and their structures and homogeneity ranges have been determined by single crystal and powder X-ray diffraction. Whereas I and II originate from the NaZn 13-type structure (cF104–112, Fm3C), III (tP52, P4/nbm) is derived from the tetragonal Ce 2Ni 17Si 9-type, and IV (oP104, Pbcm) crystallizes in a new orthorhombic structure type. Both I and II feature formally anionic networks with completely mixed site occupationmore » by Au and triel (Tr = Al, Ga) atoms, while a successive decrease of local symmetry from the parental structures of I and II to III and, ultimately, to IV correlates with increasing separation of Au and Tr on individual crystallographic sites. Density functional theory-based calculations were employed to determine the crystallographic site preferences of Au and the respective triel element to elucidate reasons for the atom distribution (“coloring scheme”). Chemical bonding analyses for two different “EuAu 6Tr 6” models reveal maximization of the number of heteroatomic Au–Tr bonds as the driving force for atom organization. The Fermi levels fall in broad pseudogaps for both models allowing some electronic flexibility. Spin-polarized band structure calculations on the “EuAu 6Tr 6” models hint to singlet ground states for europium and long-range magnetic coupling for both EuAu 6.2Ga 5.8 (III) and EuAu 6.1Al 5.9 (IV). This is substantiated by experimental evidence because both compounds show nearly identical magnetic behavior with ferromagnetic transitions at T C = 6 K and net magnetic moments of 7.35 μB/f.u. at 2 K. As a result, the effective moments of 8.3 μB/f.u., determined from Curie–Weiss fits, point to divalent oxidation states for europium in both III and IV.« less

  1. Absence of ferroelectric features in Eu2BaNiO5: An anomalous case within this rare-earth family

    NASA Astrophysics Data System (ADS)

    Upadhyay, Sanjay Kumar; Sampathkumaran, E. V.

    2018-04-01

    We report the results of magnetization, heat-capacity, magnetodielectric and pyrocurrent measurements above 2 K for the compound, Eu2BaNiO5, a Haldane spin-chain compound. This compound has been known to exhibit a magnetic transition in the vicinity of 5 K from Eu and Ni, but we do not find any evidence for ferroelectricity above 2 K, in sharp contrast to the multiferroic behavior reported for other members of this Haldane spin-chain family. Instead, there is a pyrocurrent peak around 40 K, which is sensitive to the rate of change of temperature thereby providing an evidence for thermally stimulated depolarization current. Additionally, this study brings out two more features: (i) There is a dielectric anomaly in the range 75-100 K, attributable to short-range magnetic correlations, similar to the situation encountered in another spin-chain system Ca3Co2O6, and (ii) there is a sign crossover of magnetodielectric effect (MDE) with varying magnetic field well below 8 K only, with relatively negligible values of MDE above 4 K, and this observation establishes the existence of a coupling between magnetic and electric dipoles at the onset of long-range magnetic order.

  2. Optimizing Blue Persistent Luminescence in (Sr 1-δ Ba δ ) 2 MgSi 2 O 7: Eu 2+ ,Dy 3+ via Solid Solution for Use in Point-of-Care Diagnostics

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Finley, Erin; Cobb, Angelica; Duke, Anna

    Inorganic persistent luminescent phosphors are an excellent class of optical reporters for enabling sensitive point-of-care diagnostics, particularly with smartphone-based biosensing devices in testing formats such as the lateral flow assay (LFA). Here, the development of persistent phosphors for this application is focused on the solid solution (Sr 1-δBa δ) 2MgSi 2O 7:Eu 2+,Dy 3+ (δ = 0, 0.125, 0.25, 0.375), which is prepared using a high-temperature solid-state reaction as confirmed by synchrotron X-ray powder diffraction. The substitution of barium for strontium enables control over the Eu 2+ 5d-orbital crystal field splitting (CFS) as a tool for tuning the emission wavelengthmore » while maintaining luminescence lifetimes >9 min across the composition range. Thermoluminescence measurements of the solid solution provide evidence that trap states contribute to the persistent lifetimes with the trap depths also remaining constant as a function of composition. Time-gated luminescence images of these compounds are captured on a smartphone arranged in a layout to mimic a point-of-care test and demonstrate the viability of using these materials as optical reporters. Moreover, comparing the blue-emitting (Sr 0.625Ba 0.375) 2MgSi 2O 7:Eu 2+,Dy 3+ and the green-emitting SrAl 2O 4:Eu 2+,Dy 3+ in a single LFA-type format shows these two compounds can be detected and resolved simultaneously, thereby permitting the development of a multiplexed LFA.« less

  3. Influence of Europium Doping on Various Electrical Properties of Low-Temperature Sintered 0.5Ba0.90Ca0.10TiO3-0.5BaTi0.88Zr0.12O3-0.1%CuO- xEu Lead-Free Ceramics

    NASA Astrophysics Data System (ADS)

    Tian, Yongshang; Li, Shuiyun; Sun, Shulin; Gong, Yansheng; Li, Tiantian; Yu, Yongshang; Jing, Qiangshan

    2018-01-01

    0.5Ba0.90Ca0.10TiO3-0.5BaTi0.88Zr0.12O3-0.1%CuO- xEu (BCT-BZT-Cu- xEu; x = 0-0.90%) lead-free ceramics were sintered at 1220°C with as-synthesized nanoparticles by a modified Pechini method. The structural characteristics and electrical properties of the ceramics that were influenced by varying europium-doping were investigated. All the ceramics featured high densification (relative density: ˜ 96%). X-ray powder diffraction results indicated the samples possessed pure orthorhombic phase. The maximum relative permittivity ( ɛ r, 10869) was found at x around 0.30%. Europium ions could dope on different substitution sites in the ABO3 lattice, which evidently influenced electrical properties with various volumes of oxygen vacancy. Moreover, the formation mechanisms of oxygen vacancy and defect electron complexes were stated. The piezoelectric properties were impacted by defect electron complexes, internal stress, ionic electronegativity, etc. The optimal electrical properties, i.e., d 33 = 384 pC/N, Q m = 92, and k p = 0.36, were detected at x = 0.45%.

  4. From stable divalent to valence-fluctuating behaviour in Eu(Rh1-xIrx)2Si2 single crystals

    NASA Astrophysics Data System (ADS)

    Seiro, Silvia; Geibel, Christoph

    2011-09-01

    We have succeeded in growing high-quality single crystals of the valence-fluctuating system EuIr2Si2, the divalent Eu system EuRh2Si2 and the substitutional alloy Eu(Rh1-xIrx)2Si2 across the range 0 < x < 1, which we characterized by means of x-ray diffraction, energy-dispersive x-ray spectroscopy, specific heat, magnetization and resistivity measurements. On increasing x, the divalent Eu ground state subsists up to x = 0.25 with a slight increase in Néel temperature, while for 0.3≤x < 0.7 a sharp hysteretic change in susceptibility and resistivity marks the first-order valence transition. For x≳0.7 the broad feature observed in the physical properties is characteristic of the continuous valence evolution beyond the critical end point of the valence transition line, and the resistivity is reminiscent of Kondo-like behaviour while the Sommerfeld coefficient indicates a mass renormalization of at least a factor of 8. The resulting phase diagram is similar to those reported for polycrystalline Eu(Pd1-xAux)2Si2 and EuNi2(Si1-xGex)2, confirming its generic character for Eu systems, and markedly different to those of homologue Ce and Yb systems, which present a continuous suppression of the antiferromagnetism accompanied by a very smooth evolution of the valence. We discuss these differences and suggest them to be related to the large polarization energy of the Eu half-filled 4f shell. We further argue that the changes in the rare earth valence between RRh2Si2 and RIr2Si2 (R = Ce, Eu, Yb) are governed by a purely electronic effect and not by a volume effect.

  5. Eu oxidation state in fluorozirconate-based glass ceramics

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Henke, B.; Passlick, C.; Keil, P.

    2009-12-01

    The influence of InF{sub 3} doping and remelting on Eu-doped fluorozirconate-based glass ceramics was investigated using near-edge x-ray absorption and optical spectroscopy. It was found that the addition of InF{sub 3} to the melt decreases the Eu{sup 2+}/Eu{sup 3+} mole ratio, while remelting leads to a significant change in the Eu{sup 2+}/Eu{sup 3+} ratio in favor of Eu{sup 2+}. Photoluminescence spectroscopy shows that additional annealing steps lead to the formation of BaCl{sub 2} nanoparticles in the glass. In as-made glass ceramics containing InF{sub 3}, a phase transition of the nanoparticles from hexagonal to orthorhombic structure is observed. This phase transitionmore » is not observed in the remelted glasses studied here.« less

  6. Optical transitions of Ho(3+) in oxyfluoride glasses and upconversion luminescence of Ho(3+)/Yb(3+)-codoped oxyfluoride glasses.

    PubMed

    Feng, Li; Wu, Yinsu

    2015-05-05

    Optical properties of Ho(3+)-doped SiO2-BaF2-ZnF2 glasses have been investigated on the basis of the Judd-Ofelt theory. Judd-Ofelt intensity parameters, radiative transition probabilities, fluorescence branching ratios and radiative lifetimes have been calculated for different glass compositions. Upconversion emissions were observed in Ho(3+)/Yb(3+)-codoped SiO2-BaF2-ZnF2 glasses under 980nm excitation. The effects of composition, concentration of the doping ions, and excitation pump power on the upconversion emissions were also systematically studied. Copyright © 2015 Elsevier B.V. All rights reserved.

  7. Spectroscopic and crystal-field analysis of new Yb-doped laser materials

    NASA Astrophysics Data System (ADS)

    Haumesser, Paul-Henri; Gaumé, Romain; Viana, Bruno; Antic-Fidancev, Elisabeth; Vivien, Daniel

    2001-06-01

    Crystal-field effects are very important as far as laser performances of Yb-doped materials are concerned. In order to simplify the interpretation of low-temperature spectra, two tools derived from a careful examination of crystal-field interaction are presented. Both approaches are successfully applied in the case of new Yb-doped materials, namely Ca3Y2(BO3)4 (CYB), Ca3Gd2(BO3)4 (CaGB), Sr3Y(BO3)3 (SrYBO), Ba3Lu(BO3)3 (BLuB), Y2SiO5 (YSO), Ca2Al2SiO7 (CAS) and SrY4(SiO4)3O (SYS). The 2F7/2 splitting is particularly large in these materials and favourable to a quasi-three-level laser operating scheme. Calculations performed using the point charge electrostatic model for these compounds and using a consistent set of effective atomic charges confirm the experimental results. This should permit to use this model in a predictive approach.

  8. The Pressure-Induced Structural Response of A2Hf2O7 (A=Y, Sm, Eu, Gd, Dy, Yb) Compounds from 0.1-50 GPa

    NASA Astrophysics Data System (ADS)

    Turner, K. M.; Rittman, D.; Heymach, R.; Turner, M.; Tracy, C.; Mao, W. L.; Ewing, R. C.

    2016-12-01

    A2B2O7 (A, B= cations) compounds have structures that make their properties conducive to many applications; for example they are a proposed waste-form for actinides generated in the nuclear fuel cycle. This interest in part is due to their structural responses to extreme environments of high P, T, or under intense irradiation. Depending on their cationic radius ratio, ra/rb, A2B2O7 compounds either crystallize as pyrochlore (ra/rb=1.46-1.7) or "defect fluorite" (ra/rb>1.46). The structure types are similar: they are derivatives of ideal fluorite with two cations and 1/8 missing anions. In pyrochlore, the cations and anion vacancy are ordered. In "defect fluorite"-structured oxides, the cations and anion vacancies are random. A2B2O7 compounds rarely amorphize in extreme environments. Rather, they disorder and undergo phase transitions; this resistance to amorphization contributes to the durability of this potential actinide waste-form. Under high-pressure, A2B2O7 compounds are known to disorder or form a cottunite-like phase. Their radius ratio affects their response to extreme environments; "defect fluorite" type compounds tend to disorder, and pyrochlore type compounds tend to form the cottunite-like phase. We have examined six A2Hf2O7 compounds (A=Y, Sm, Eu, Gd, Dy, Yb) in situ to 50 GPa. By keeping the B-site constant (Hf), we examined the effect of a changing radius ratio on the pressure-induced structural response of hafnates. We used symmetric DACs, ruby fluorescence, stainless steel gaskets, and methanol: ethanol (4:1 by volume) pressure medium. We characterized these materials with in situ Raman spectroscopy at Stanford University, and synchrotron X-Ray Diffraction (XRD) at APS 16 BM-D and ALS 12.2.2. The compounds were pyrochlore structured (Sm, Eu, Gd) and "defect-fluorite" structured (Y, Dy, Yb) hafnates . These compounds undergo a slow phase transition to a high-pressure cotunnite-like phase between 18-30 GPa. They undergo disordering of their cation

  9. Yb:S-FAP Lasers

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Schaffers, K I

    It has recently been reported that several high power, diode-pumped laser systems have been developed based on crystals of Yb:S-FAP [Yb{sup 3+}:Sr{sub 5}(PO{sub 4}){sub 3}F]. The Mercury Laser, at Lawrence Livermore National Laboratory, is the most prominent system using Yb:S-FAP and is currently producing 23J at 5 Hz in a 15 nsec pulse, based on partial activation of the system. In addition, a regenerative amplifier is being developed at Waseda University in Japan and has produced greater than 12 mJ with high beam quality at 50Hz repetition rate. Q-peak has demonstrated 16 mJ of maximum energy/output pulse in a multi-pass,more » diode side-pumped amplifier and ELSA in France is implementing Yb:S-FAP in a 985 nm pump for an EDFA, producing 250 mW. Growth of high optical quality crystals of Yb:S-FAP is a challenge due to multiple crystalline defects. However, at this time, a growth process has been developed to produce high quality 3.5 cm diameter Yb:S-FAP crystals and a process is under development for producing 6.5 cm diameter crystals.« less

  10. Formation Mechanism, Structural, and Upconversion Properties of Alkaline Rare-Earth Fluoride Nanocrystals Doped With Yb3+/Er3+ Ions.

    PubMed

    Grzyb, Tomasz; Przybylska, Dominika

    2018-06-04

    Ultrasmall (9-30 nm) Yb 3+ /Er 3+ -doped, upconverting alkaline rare-earth fluorides that are promising for future applications were synthesized by the microwave-assisted hydrothermal method. The formation mechanism was proposed, indicating the influence of the stability of metal ions complexes with ethylenediaminetetraacetic acid on the composition of the product and tendency to form M 2 REF 7 (M 0.67 RE 0.33 F 2.33 ) cubic compounds in the M-RE-F systems. Their physicochemical properties (structure, morphology, and spectroscopic properties) are compared and discussed. The obtained nanoparticles exhibited emission of light in the visible spectra under excitation by 976 nm laser radiation. Excitation and emission spectra, luminescence decays, laser energy dependencies, and upconversion quantum yields were measured to determine the spectroscopic properties of prepared materials. The Yb 3+ /Er 3+ pair of ions used as dopants was responsible for an intense yellowish-green emission. The upconversion quantum yields determined for the first time for M 2 REF 7 -based materials were 0.0192 ± 0.001% and 0.0176 ± 0.001% for Sr 2 LuF 7 :Yb 3+ ,Er 3+ and Ba 2 LuF 7 :Yb 3+ ,Er 3+ respectively, the two best emitting samples. These results indicated the prepared materials are good and promising alternatives for the most studied NaYF 4 :Yb 3+ ,Er 3+ nanoparticles.

  11. Temperature-controlled down-conversion luminescence behavior of Eu3+ -doped transparent MF2 (M = Ba, Ca, Sr) glass ceramics.

    PubMed

    Zhou, B; E, C Q; Bu, Y Y; Meng, L; Yan, X H; Wang, X F

    2017-03-01

    Eu 3 + -doped transparent glass ceramics containing MF 2 (M = Ba, Ca, Sr) nanocrystals were fabricated using a melt-quenching method, and the resulting structures were studied using X-ray diffraction. Levels 5 D 1 and 5 D 0 of Eu 3 + ions were verified as thermally coupled levels using the fluorescence intensity ratio method. The fluorescence intensity ratios, optical temperature sensitivity and thermal quenching ratios of the transparent glass ceramics were studied as a function of temperature. With an increase in temperature, the relative sensitivity (S R ) decreased sharply at first, then slowly increased, before finally decreasing. The minimum S R values of GCBaF 2 (GCB), GCCaF 2 (GCC) and GCSrF 2 (GCS) were 2.8 × 10 -4 , 0.8 × 10 -4 and 1.9 × 10 - 4  K -1 at 360, 269 and 319 K, respectively. Glass ceramics with an intense emission intensity can be used to convert the measured spectrum into temperature and may have an important role in temperature detectors. Copyright © 2016 John Wiley & Sons, Ltd.

  12. The Crystal Structure of Ba 17Sm 10Cl 64

    NASA Astrophysics Data System (ADS)

    Liu, Guo; Eick, Harry A.

    1999-08-01

    The structure of Ba17Sm10Cl64, prepared by solvolytic extraction of a program-cooled 1:1 BaCl2:SmCl3 molar mixture sealed in a quartz tube and heated to 750°C, was determined from single-crystal X-ray diffraction data. The compound exhibits cubic symmetry, space group Pa3 (No. 205) with a=21.366(2) Å and Z=4. Refinement effected with I>2σ(I) yielded R1= 0.0926 and wR2=0.216. One Ba atom is 12-coordinated by Cl atoms in a distorted icosahedral arrangement; the three other Ba atoms are 10-coordinated in a distorted bicapped cubic arrangement. There are two Sm atom sites. The coordination around one Sm atom is best described as square antiprismatic, but one Sm-Cl distance is too long for effective bonding. The other Sm atom site, occupied statistically by {1}/{3}Ba and {2}/{3}Sm atoms, is 9-coordinated by Cl atoms in a monocapped square antiprismatic arrangement. The two types of Sm sites combine to form an M6Cl37 cuboctahedral cluster of the composition BaSm5Cl37. It is shown that the cβ phase identified previously in the Yb-F and related fluoride systems is probably isostructural with Ba17Sm10Cl64.

  13. Novel Red-Emitting Ba₃Y(BO₃)₃:Bi3+, Eu3+ Phosphors for N-UV White Light-Emitting Diodes.

    PubMed

    Maggay, Irish Valerie B; Liu, Wei-Ren

    2018-01-01

    Ba3Y(BO3)3:Eu3+, Bi3+ were successfully prepared via a solid-state reaction. The crystallinity, photoluminescence properties, energy transfer and thermal quenching properties were studied. Subjecting Ba3Y(BO3)3:Bi3+ samples to different excitation wavelengths (340-370 nm), obtained blue and green emission ascribed to Bi3+(II) and Bi3+(I) sites, respectively. The influence of these two sites were systematically investigated. Bi3+ efficiently transferred its absorbed energy to neighboring Eu3+ sites by enhancing its luminescence intensity. Moreover, Bi3+ greatly enhanced the excitation spectra of Eu3+ in the N-UV region by 2.26 times which indicates that Ba3Y(BO3)3:Eu3+, Bi3+ can be used as a phosphor for w-LEDs using N-UV LED chips.

  14. Photoluminescence and electrical characterization of unfilled tetragonal tungsten bronze Ba{sub 4}La{sub 1−x}Eu{sub x}TiNb{sub 9}O{sub 30}

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Wei, T., E-mail: weitong.nju@gmail.com; Wang, Y.Q.; Zhao, C.Z.

    Graphical abstract: PL spectra of the unfilled TTB structure BLTN: Eu{sup 3+}x samples (x = 0.00, 0.25, 0.50, 0.75, and 1.00) excited by 399 nm. The inset is a schematic diagram of the unfilled TTB structure. - Highlights: • Unfilled TTB structure BLTN: Eu{sup 3+}x ceramics have been synthesized. • Photoluminescenct properties of the BLTN: Eu{sup 3+}x ceramics have been first reported. • Bright red emission excited by NUV light has been observed at room temperature. • Obvious variations of dielectric characteristics have been confirmed. • Relaxor-like ferroelectric phase transitions have been detected. - Abstract: Unfilled tetragonal tungsten bronze (TTB)more » structure Ba{sub 4}LaTiNb{sub 9}O{sub 30} doped by Eu{sup 3+} (BLTN: Eu{sup 3+}x) with different x have been prepared, and their structural, photoluminescence, dielectric, and ferroelectric properties are carefully investigated in this work. Bright red emission, originating from {sup 5}D{sub 0} → {sup 7}F{sub 1} and {sup 5}D{sub 0} → {sup 7}F{sub 2} transitions of Eu{sup 3+} ions, has been observed by naked eyes at room temperature under near ultraviolet (NUV) light excitation. Optimized emission intensity is obtained when x = 1.00 for present unfilled TTB-type BLTN: Eu{sup 3+}x samples. Furthermore, with increasing x, the dielectric and ferroelectric characteristics of the unfilled TTB-type BLTN: Eu{sup 3+}x samples also display remarkable variation. When x ≥ 0.50 relaxor-like ferroelectric phase transitions are detected above room temperature, it is believed that unfilled TTB-type BLTN: Eu{sup 3+}x = 1.00 involving bright photoluminescence and enhanced ferroelectric properties may act as a potentially multifunctional optical-electro material.« less

  15. Crystal field excitations from Yb3 + ions at defective sites in highly stuffed Yb2Ti2O7

    NASA Astrophysics Data System (ADS)

    Sala, G.; Maharaj, D. D.; Stone, M. B.; Dabkowska, H. A.; Gaulin, B. D.

    2018-06-01

    The pyrochlore magnet Yb2Ti2O7 has been proposed as a quantum spin ice candidate, a spin liquid state expected to display emergent quantum electrodynamics with gauge photons among its elementary excitations. However, Yb2Ti2O7 's ground state is known to be very sensitive to its precise stoichiometry. Powder samples, produced by solid-state synthesis at relatively low temperatures, tend to be stoichiometric, while single crystals grown from the melt tend to display weak "stuffing" wherein ˜2 % of the Yb3 +, normally at the A site of the A2B2O7 pyrochlore structure, reside as well at the B site. In such samples Yb3 + ions should exist in defective environments at low levels and be subjected to crystalline electric fields very different from those at the stoichiometric A sites. Neutron scattering measurements of Yb3 + in four compositions of Yb2 +xTi2 -xO7 -y show the spectroscopic signatures for these defective Yb3 + ions and explicitly demonstrate that the spin anisotropy of the Yb3 + moment changes from X Y -like for stoichiometric Yb3 + to Ising-like for "stuffed" B site Yb3 + or for A site Yb3 + in the presence of oxygen vacancies.

  16. Absorption of Dy3+ and Nd3+ ions in Ba R 2F8 single crystals

    NASA Astrophysics Data System (ADS)

    Apollonov, V. V.; Pushkar', A. A.; Uvarova, T. V.; Chernov, S. P.

    2008-09-01

    The Dy3+ absorption and excitation spectra of BaY2F8 and BaYb2F8 single crystals are investigated in the ultraviolet, vacuum ultraviolet, and visible ranges at a temperature of 300 K. These crystals exhibit intense broad absorption bands due to the spin-allowed 4 f-5 d transitions in the range (56-78) × 10-3 cm-1 and less intense absorption bands that correspond to the spin-forbidden transitions in the range (50-56) × 10-3 cm-1. The Nd3+ absorption spectra of BaY2F8 single crystals are studied in the range (34-82) × 10-3 cm-1 at 300 K for different crystal orientations.

  17. Yb7Ni4InGe12: a quaternary compound having mixed valent Yb atoms grown from indium flux.

    PubMed

    Subbarao, Udumula; Jana, Rajkumar; Chondroudi, Maria; Balasubramanian, Mahalingam; Kanatzidis, Mercouri G; Peter, Sebastian C

    2015-03-28

    The new intermetallic compound Yb7Ni4InGe12 was obtained as large silver needle shaped single crystals from reactive indium flux. Single crystal X-ray diffraction suggests that Yb7Ni4InGe12 crystallizes in the Yb7Co4InGe12 structure type, and tetragonal space group P4/m and lattice constants are a = b = 10.291(2) Å and c = 4.1460(8) Å. The crystal structure of Yb7Ni4InGe12 consists of columnar units of three different types of channels filled with the Yb atoms. The crystal structure of Yb7Ni4InGe12 is closely related to Yb5Ni4Ge10. The effective magnetic moment obtained from the magnetic susceptibility measurements in the temperature range 200-300 K is 3.66μB/Yb suggests mixed/intermediate valence behavior of ytterbium atoms. X-ray absorption near edge spectroscopy (XANES) confirms that Yb7Ni4InGe12 exhibits mixed valence.

  18. Large negative magnetoresistance of a nearly Dirac material: Layered antimonide EuMnS b2

    NASA Astrophysics Data System (ADS)

    Yi, Changjiang; Yang, Shuai; Yang, Meng; Wang, Le; Matsushita, Yoshitaka; Miao, Shanshan; Jiao, Yuanyuan; Cheng, Jinguang; Li, Yongqing; Yamaura, Kazunari; Shi, Youguo; Luo, Jianlin

    2017-11-01

    Single crystals of EuMnS b2 were successfully grown and their structural and electronic properties were investigated systematically. The material crystallizes in an orthorhombic-layered structure (space group: Pnma, No. 62) comprising a periodic sequence of -MnSb/Eu/Sb/Eu/- layers (˜1 nm in thickness), and massless fermions are expected to emerge in the Sb layer, by analogy of the candidate Dirac materials EuMnB i2 and A Mn P n2 (A =Ca or Sr or Ba, P n =Sb or Bi). The magnetic and specific heat measurements of EuMnS b2 suggest an antiferromagnetic ordering of Eu moments near 20 K. A characteristic hump appears in the temperature-dependent electrical resistivity curve at ˜25 K . A spin-flop transition of Eu moments with an onset magnetic field of ˜15 kOe (at 2 K) was observed. Interestingly, EuMnS b2 shows a negative magnetoresistance (up to -95 % ) in contrast to the positive magnetoresistances observed for EuMnB i2 and A Mn P n2 (A =Ca or Sr or Ba, P n =Sb or Bi), providing a unique opportunity to study the correlation between electronic and magnetic properties in this class of materials.

  19. Functional conservation of rice OsNF-YB/YC and Arabidopsis AtNF-YB/YC proteins in the regulation of flowering time.

    PubMed

    Hwang, Yoon-Hyung; Kim, Soon-Kap; Lee, Keh Chien; Chung, Young Soo; Lee, Jeong Hwan; Kim, Jeong-Kook

    2016-04-01

    Rice Os NF - YB and Os NF - YC complement the late flowering phenotype of Arabidopsis nf - yb double and nf - yc triple mutants, respectively. In addition, OsNF-YB and OsNF-YC interact with AtNF-YC and AtNF-YB, respectively. Plant NUCLEAR FACTOR Y (NF-Y) transcription factors play important roles in plant development and abiotic stress. In Arabidopsis thaliana, two NF-YB (AtNF-YB2 and AtNF-YB3) and five NF-YC (AtNF-YC1, AtNF-YC2, AtNF-YC3, AtNF-YC4, and AtNF-YC9) genes regulate photoperiodic flowering by interacting with other AtNF-Y subunit proteins. Three rice NF-YB (OsNF-YB8, OsNF-YB10, and OsNF-YB11) and five rice OsNF-YC (OsNF-YC1, OsNF-YC2, OsNF-YC4, OsNF-YC6, and OsNF-YC7) genes are clustered with two AtNF-YB and five AtNF-YC genes, respectively. To investigate the functional conservation of these NF-YB and NF-YC genes in rice and Arabidopsis, we analyzed the flowering phenotypes of transgenic plants overexpressing the respective OsNF-YB and OsNF-YC genes in Arabidopsis mutants. Overexpression of OsNF-YB8/10/11 and OsNF-YC2 complemented the late flowering phenotype of Arabidopsis nf-yb2 nf-yb3 and nf-yc3 nf-yc4 nf-yc9 mutants, respectively. The rescued phenotype of 35S::OsNF-YC2 nf-yc3 nf-yc4 nf-yc9 plants was attributed to the upregulation of FLOWERING LOCUS T (FT) and SUPPRESSOR OF OVEREXPRESSION OF CONSTANS 1 (SOC1). In vitro and in planta protein-protein analyses revealed that OsNF-YB8/10/11 and OsNF-YC1/2/4/6/7 interact with AtNF-YC3/4/9 and AtNF-YB2/3, respectively. Our data indicate that some OsNF-YB and OsNF-YC genes are functional equivalents of AtNF-YB2/3 and AtNF-YC3/4/9 genes, respectively, and suggest functional conservation of Arabidopsis and rice NF-Y genes in the control of flowering time.

  20. Introducing Eu{sup 2+} into yellow phosphor LiBaB{sub 9}O{sub 15}:Ce{sup 3+}, Dy{sup 3+} as blue emitting source to realize white emission

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Li, Ting; Li, Panlai, E-mail: li_panlai@126.com; Fu, Nian, E-mail: funian3678@163.com

    A series of Dy{sup 3+}, Ce{sup 3+}/Dy{sup 3+}, Eu{sup 2+}/Dy{sup 3+} and Ce{sup 3+}/Eu{sup 2+}/Dy{sup 3+} doping LiBaB{sub 9}O{sub 15} (LBB) phosphors were synthesized via a high temperature solid-state method. LBB:Dy{sup 3+} cannot create light under ultraviolet radiation, however, LBB:Ce{sup 3+}, Dy{sup 3+} can produce yellow emission under 295 nm excitation. The energy transfer occurs from Ce{sup 3+} to Dy{sup 3+} ions via electric dipole-dipole interaction and the critical distance is estimated to be 21.15 Å based on concentration quenching model. Generally, Eu{sup 2+} ion is a sensitizer to Dy{sup 3+} ion, however, there is only the emission of Eu{supmore » 2+} in LBB:Eu{sup 2+}, Dy{sup 3+}, which means there is no energy transfer from Eu{sup 2+} to Dy{sup 3+} ions. Interestingly enough, when doping Eu{sup 2+} ion into LBB:Ce{sup 3+}, Dy{sup 3+}, white emission can be achieved by increase the blue (350–425 nm) emission intensity. The spectral property, quantum efficiency, CIE chromaticity coordinates and thermal quenching property of LBB:Ce{sup 3+}, Eu{sup 2+}, Dy{sup 3+} are investigated. The results indicate that LBB:Ce{sup 3+}, Eu{sup 2+}, Dy{sup 3+} may be a potential application to white light emitting diodes. - Graphical abstract: LBB:Ce{sup 3+}, Dy{sup 3+} can create white emission by doping Eu{sup 2+} ions. - Highlights: • LBB:Ce{sup 3+}, Dy{sup 3+} can produce white emission by doping Eu{sup 2+} ion. • There is no energy transfer from Eu{sup 2+} to Dy{sup 3+} ions. • Energy transfer occurs from Ce{sup 3+} to Dy{sup 3+} ions. • LBB:Ce{sup 3+}, Eu{sup 2+}, Dy{sup 3+} may be a potential application for white LEDs.« less

  1. Structure and luminescent property of complexes of aryl carboxylic acid-functionalized polystyrene with Eu(III) and Tb(III) ions.

    PubMed

    Gao, Baojiao; Shi, Nan; Qiao, Zongwen

    2015-11-05

    Via polymer reactions, naphthoic acid (NA) and benzoic acid (BA) were bonded onto the side chains of polystyrene (PS), respectively, and two aryl carboxylic acid-functionalized polystyrenes, PSNA and PSBA, were obtained. Using PSNA and PSBA as macromolecule ligands and Eu(3+) and Tb(3+) ions as central ions, various luminescent binary polymer-rare earth complexes were prepared. At the same time, with 1,10-phenanthroline (Phen) and 4,4'-bipyridine (Bipy) as small-molecule co-ligands, various ternary polymer-rare earth complexes were also prepared. On the basis of characterizing PSNA, PSBA and complexes, the relationship between structure and luminescent property for these prepared complexes were mainly investigated. The study results show that the macromolecule ligands PSNA and PSBA, or the bonded NA and BA ligands, can strongly sensitize the fluorescence emissions of Eu(3+) ion or Tb(3+) ion, but the sensitization effect is strongly dependent on the structure of the ligands and the property of the central ions, namely it is strongly dependent on the matching degree of energy levels. The fluorescence emission of the binary complex PS-(NA)3-Eu(III) is stronger than that PS-(BA)3-Eu(III), indicating ligand NA has stronger sensitization action for Eu(3+) ion than ligand BA; the binary complex PS-(BA)3-Tb(III) emit strong characteristic fluorescence of Tb(3+) ion, displaying that ligand BA can strongly sensitize Tb(3+) ion, whereas the binary complex PS-(NA)3-Tb(III) nearly does not emit the characteristic fluorescence of Tb(3+) ion, showing that ligand NA does not sensitize Tb(3+) ion. The fluorescence intensity of the ternary complexes is much stronger than that of the binary complexes in the same series. Copyright © 2015 Elsevier B.V. All rights reserved.

  2. NMR study of partially filled skutterudites AxCo4Sb12 (A = Yb, Ba, Sr, Ca) and BaxYbyCo4Sb12.

    NASA Astrophysics Data System (ADS)

    Tian, Yefan; Sirusi, Ali; Ross, Joseph; Ballikaya, Sedat; Uher, Ctirad; Chen, Yuqi; Sekine, Chihiro

    Partially filled Co-Sb skutterudites have been of considerable interest as thermoelectric materials, particularly with multiple filling for which high ZT values can be obtained. This is due in part to control of phonon thermal conductivity, but also the change in composition leads to subtle changes in electronic behavior as well as magnetism due both to rare earth filler atoms and to native defects. We measured 59Co NMR on several partially filled AxCo4Sb12 skutterudites in order to investigate such behavior. From the T-dependent NMR shifts along with T1 relaxation times we can separate metallic shift contributions from those due to local moments. We compare the results to predicted band-edge behavior with multiple minima, and the estimated g factors, by matching this behavior to transport measurements. Also the behavior of Yb-filled samples provides an estimate of the conduction band mediation of the magnetic response, and we also find magnetic shifts in Ba-doped skutterudite which we address in terms of Co mixed-valence behavior. This work was supported by the Robert A. Welch Foundation, Grant No. A-1526. Synthesis work was partly supported by the Center for Solar and Thermal Energy Conversion and a Grant-in-Aid for Scientific Research (B) (No. 23340092) from the Japan Society.

  3. Chemical abundances of 1111 FGK stars from the HARPS GTO planet search program. II. Cu, Zn, Sr, Y, Zr, Ba, Ce, Nd, and Eu

    NASA Astrophysics Data System (ADS)

    Delgado Mena, E.; Tsantaki, M.; Adibekyan, V. Zh.; Sousa, S. G.; Santos, N. C.; González Hernández, J. I.; Israelian, G.

    2017-10-01

    Aims: To understand the formation and evolution of the different stellar populations within our Galaxy it is essential to combine detailed kinematical and chemical information for large samples of stars. The aim of this work is to explore the chemical abundances of neutron capture elements which are a product of different nucleosynthesis processes taking place in diverse objects in the Galaxy, such as massive stars, asymptotic giant branch (AGB) stars and supernovae (SNe) explosions. Methods: We derive chemical abundances of Cu, Zn, Sr, Y, Zr, Ba, Ce, Nd, and Eu for a large sample of more than 1000 FGK dwarf stars with high-resolution (R 115 000) and high-quality spectra from the HARPS-GTO program. The abundances are derived by a standard local thermodynamic equilibrium (LTE) analysis using measured equivalent widths (EWs) injected to the code MOOG and a grid of Kurucz ATLAS9 atmospheres. Results: We find that thick disc stars are chemically disjunct for Zn and Eu and also show on average higher Zr but lower Ba and Y than the thin disc stars. We also discovered that the previously identified high-α metal-rich population is also enhanced in Cu, Zn, Nd, and Eu with respect to the thin disc but presents lower Ba and Y abundances on average, following the trend of thick disc stars towards higher metallities and further supporting the different chemical composition of this population. By making a qualitative comparison of O (pure α), Mg, Eu (pure r-process), and s-process elements we can distinguish between the contribution of the more massive stars (SNe II for α and r-process elements) and the lower mass stars (AGBs) whose contribution to the enrichment of the Galaxy is delayed, due to their longer lifetimes. The ratio of heavy-s to light-s elements of thin disc stars presents the expected behaviour (increasing towards lower metallicities) and can be explained by a major contribution of low-mass AGB stars for s-process production at disc metallicities. However, the

  4. Luminescence of Er/Yb and Tm/Yb doped FAp nanoparticles and ceramics

    NASA Astrophysics Data System (ADS)

    Grigorjeva, L.; Smits, K.; Millers, D.; Jankoviča, Dz

    2015-03-01

    The nanoparticles of hydroxiapatite and fluorapatite doped with Er/Yb and Tm/Yb were synthesized and characterized by FTIR, XRD, SEM and TEM methods. The results of up-conversion luminescence studies were presented for the samples as prepared, annealed at 500°C and at 900-1000 °C. At annealing above 800°C the ceramic state was formed. It is shown that fluorapatite host is more appropriate than hydroxiapatite host for rare ions luminescence and up-conversion processes. The post preparing annealing of nanarticles significantly enhanced the luminescence intensity. The Tm/Yb doped fluorapatite shows intense up-conversion luminescence in 790-800 nm spectral region and is potentially useful for biomedical applications.

  5. Four nucleocytoplasmic-shuttling proteins and p53 interact specifically with the YB-NLS and are involved in anticancer reagent-induced nuclear localization of YB-1

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Tanaka, Toru; Ohashi, Sachiyo; Kobayashi, Shunsuke

    In cancer cells, anticancer reagents often trigger nuclear accumulation of YB-1, which participates in the progression of cancer malignancy. YB-1 has a non-canonical nuclear localization signal (YB-NLS). Here we found that four nucleocytoplasmic-shuttling RNA-binding proteins and p53 interact specifically with the YB-NLS and co-accumulate with YB-1 in the nucleus of actinomycin D-treated cells. To elucidate the roles of these YB-NLS-binding proteins, we performed a dominant-negative experiment in which a large excess of YB-NLS interacts with the YB-NLS-binding proteins, and showed inhibitory effects on actinomycin D-induced nuclear transport of endogenous YB-1 and subsequent MDR1 gene expression. Furthermore, the YB-NLS-expressing cells weremore » also found to show increased drug sensitivity. Our results suggest that these YB-NLS-associating proteins are key factors for nuclear translocation/accumulation of YB-1 in cancer cells. - Highlights: • Four nucleocytoplasmic-shuttling proteins and p53 associate with YB-NLS. • They showed nuclear co-accumulation with YB-1 in actinomycin D-treated cells. • Overexpression of YB-NLS was carried out to take YB-NLS-binding proteins from YB-1. • YB-NLS inhibited actinomycin D-induced nuclear localization of endogenous YB-1. • YB-NLS suppressed actinomycin D-induced expression of MDR1.« less

  6. Effect of rare earth doping on optical and spectroscopic characteristics of BaZrO3:Eu3+,Tb3+ perovskites.

    PubMed

    Katyayan, Shambhavi; Agrawal, Sadhana

    2018-04-04

    This paper reports structural investigations of rare earth doped BaZrO 3 phosphors synthesized by Solid state reaction technique with varying concentrations of Eu 3+ and Tb 3+ from 0 mol% to 2 mol%. The synthesized phosphors show enhanced variable emissions in the visible region corresponding to different hypersensitive electronic transitions of Eu 3+ and Tb 3+ ions. With cubic structure confirmed in XRD analysis, the FESEM images show uniform grain connectivity and homogeneity of prepared samples. The TEM micrographs of the synthesized phosphors show agglomerated irregular structures. The synthesized phosphors were also subjected to FTIR, Raman, EDXS analysis along with studies of thermoluminescent and photoluminescent characteristics. On subjecting to 229 nm (UV) excitation, the phosphors show enhanced PL emissions corresponding to 571 nm ( 5 D 0 - 7 F 0 ), 591 nm ( 5 D 0 - 7 F 1 ), 615 nm ( 5 D 0 - 7 F 2 ) and 678 nm ( 5 D 0 - 7 F 4 ) hypersensitive transitions of Eu 3+ ions and emission peaks at 489 nm ( 5 D 4 - 7 F 6 ), 539 nm ( 5 D 4 - 7 F 5 ), 589 nm ( 5 D 4 - 7 F 4 ) and 632 nm ( 5 D 4 - 7 F 3 ) accounting for electronic transitions of Tb 3+ ions respectively. The computed average PL lifetime is 14.014 s. In the TL analysis, the second order of kinetics with the activation energy varying from 5.0 × 10 -1 eV to 6.6 × 10 -1 eV is reported. The maximum TL lifetime is estimated as 19.4985 min in the TL lifetime analysis.

  7. Effect of rare earth doping on optical and spectroscopic characteristics of BaZrO3:Eu3+,Tb3+ perovskites

    NASA Astrophysics Data System (ADS)

    Katyayan, Shambhavi; Agrawal, Sadhana

    2018-06-01

    This paper reports structural investigations of rare earth doped BaZrO3 phosphors synthesized by Solid state reaction technique with varying concentrations of Eu3+ and Tb3+ from 0 mol% to 2 mol%. The synthesized phosphors show enhanced variable emissions in the visible region corresponding to different hypersensitive electronic transitions of Eu3+ and Tb3+ ions. With cubic structure confirmed in XRD analysis, the FESEM images show uniform grain connectivity and homogeneity of prepared samples. The TEM micrographs of the synthesized phosphors show agglomerated irregular structures. The synthesized phosphors were also subjected to FTIR, Raman, EDXS analysis along with studies of thermoluminescent and photoluminescent characteristics. On subjecting to 229 nm (UV) excitation, the phosphors show enhanced PL emissions corresponding to 571 nm (5D0-7F0), 591 nm (5D0-7F1), 615 nm (5D0-7F2) and 678 nm (5D0-7F4) hypersensitive transitions of Eu3+ ions and emission peaks at 489 nm (5D4-7F6), 539 nm (5D4-7F5), 589 nm (5D4-7F4) and 632 nm (5D4-7F3) accounting for electronic transitions of Tb3+ ions respectively. The computed average PL lifetime is 14.014 s. In the TL analysis, the second order of kinetics with the activation energy varying from 5.0 × 10‑1 eV to 6.6 × 10‑1 eV is reported. The maximum TL lifetime is estimated as 19.4985 min in the TL lifetime analysis.

  8. Synthesis and characterisation of the n = 2 Ruddlesden–Popper phases Ln{sub 2}Sr(Ba)Fe{sub 2}O{sub 7} (Ln = La, Nd, Eu)

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Gurusinghe, Nicola N.M.; Figuera, Juand de la; Marco, José F.

    2013-09-01

    Graphical abstract: - Highlights: • Some Ruddlesden–Popper phases have been characterised. • Substitution on the A site influences cationic order. • The magnetic moment redirects with temperature - Abstract: A series of n = 2 Ruddlesden–Popper phases A{sub 2}B{sub 2}O{sub 7} of composition Ln{sub 2}Sr(Ba)Fe{sub 2}O{sub 7} (Ln = La, Nd, Eu) have been prepared. La{sub 2}SrFe{sub 2}O{sub 7} and La{sub 2}BaFe{sub 2}O{sub 7} crystallise in the tetragonal space group I4/mmm. The structures of Eu{sub 2}SrFe{sub 2}O{sub 7} and Nd{sub 2}SrFe{sub 2}O{sub 7} are best described in space group P4{sub 2}/mnm. Substitution on the A site with smaller lanthanide- andmore » larger alkaline metal- ions leads to enhanced cationic order in these phases and reflects increasing differences in cationic radii. All the compounds are antiferromagnetically ordered between 298 and 2 K. In La{sub 2}SrFe{sub 2}O{sub 7} the magnetic moment lies along [1 1 0] at all temperatures between 298 and 2 K whereas in La{sub 2}BaFe{sub 2}O{sub 7} the magnetic moment at 298 K lies along the crystallographic x-axis but redirects from the [1 0 0] to the [1 1 0] direction between 210 and 190 K and is retained in this direction until 2 K. In Nd{sub 2}SrFe{sub 2}O{sub 7} the magnetic moment at 298 K lies along [1 1 0] but rotates from [1 1 0] to [0 0 1] between 17 and 9 K. A series of {sup 57}Fe Mössbauer spectra recorded from La{sub 2}SrFe{sub 2}O{sub 7} between 290 and 600 K indicate a magnetic ordering temperature of T{sub N} ≥ 535 K.« less

  9. Influence of Sm2O3 microalloying and Yb contamination on Y211 particles coarsening and superconducting properties of IG YBCO bulk superconductors

    NASA Astrophysics Data System (ADS)

    Vojtkova, L.; Diko, P.; Kovac, J.; Vojtko, M.

    2018-06-01

    Single grain YBa2Cu3O7‑x (YBCO or Y123) bulk superconductors were produced by an infiltration growth process. The solid phase precursor was prepared by solid state synthesis from Y2O3 + BaCuO2 powders. The influence of the addition of Sm2O3 and YB contamination from the substrate on the microstructure and superconducting properties was analyzed. The dependences of Yb concentration on the distance from the bottom of the samples measured by energy dispersive spectroscopy microanalysis used in conjunction with scanning electron microscopy confirmed the contamination of the samples during the melting stage of the sample preparation. It is shown that the addition of Sm in low concentration and its combination with Yb from the substrate modify the coarsening of the Y211 particles as well as lead to the appearance of a secondary peak effect in the field dependences of the critical current density.

  10. Site Occupation of Eu2+ in Ba2- xSr xSiO4 ( x = 0-1.9) and Origin of Improved Luminescence Thermal Stability in the Intermediate Composition.

    PubMed

    Lin, Litian; Ning, Lixin; Zhou, Rongfu; Jiang, Chunyan; Peng, Mingying; Huang, Yucheng; Chen, Jun; Huang, Yan; Tao, Ye; Liang, Hongbin

    2018-06-18

    Knowledge of site occupation of activators in phosphors is of essential importance for understanding and tailoring their luminescence properties by modifying the host composition. Relative site preference of Eu 2+ for the two distinct types of alkaline earth (AE) sites in Ba 1.9995- x Sr x Eu 0.0005 SiO 4 ( x = 0-1.9) is investigated based on photoluminescence measurements at low temperature. We found that Eu 2+ prefers to be at the 9-coordinated AE2 site at x = 0, 0.5, and 1.0, while at x = 1.5 and 1.9, it also occupies the 10-coordinated AE1 site with comparable preference, which is verified by density functional theory (DFT) calculations. Moreover, by combining low-temperature measurements of the heat capacity, the host band gap, and the Eu 2+ 4f 7 ground level position, the improved thermal stability of Eu 2+ luminescence in the intermediate composition ( x = 1.0) is interpreted as due to an enlarged energy gap between the emitting 5d level and the bottom of the host conduction band (CB), which results in a decreased nonradiative probability of thermal ionization of the 5d electron into the host CB. Radioluminescence properties of the samples under X-ray excitation are finally evaluated, suggesting a great potential scintillator application of the compound in the intermediate composition.

  11. Yb5Ga2Sb6: a mixed valent and narrow-band gap material in the RE5M2X6 family.

    PubMed

    Subbarao, Udumula; Sarkar, Sumanta; Gudelli, Vijay Kumar; Kanchana, V; Vaitheeswaran, G; Peter, Sebastian C

    2013-12-02

    A new compound Yb5Ga2Sb6 was synthesized by the metal flux technique as well as high frequency induction heating. Yb5Ga2Sb6 crystallizes in the orthorhombic space group Pbam (no. 55), in the Ba5Al2Bi6 structure type, with a unit cell of a = 7.2769(2) Å, b = 22.9102(5) Å, c = 4.3984(14) Å, and Z = 2. Yb5Ga2Sb6 has an anisotropic structure with infinite anionic double chains (Ga2Sb6)(10-) cross-linked by Yb(2+) and Yb(3+) ions. Each single chain is made of corner-sharing GaSb4 tetrahedra. Two such chains are bridged by Sb2 groups to form double chains of 1/∞ [Ga2Sb6(10-)]. The compound satisfies the classical Zintl-Klemm concept and is a narrow band gap semiconductor with an energy gap of around 0.36 eV calculated from the electrical resistivity data corroborating with the experimental absorption studies in the IR region (0.3 eV). Magnetic measurements suggest Yb atoms in Yb5Ga2Sb6 exist in the mixed valent state. Temperature dependent magnetic susceptibility data follows the Curie-Weiss behavior above 100 K and no magnetic ordering was observed down to 2 K. Experiments are accompanied by all electron full-potential linear augmented plane wave (FP-LAPW) calculations based on density functional theory to calculate the electronic structure and density of states. The calculated band structure shows a weak overlap of valence band and conduction band resulting in a pseudo gap in the density of states revealing semimetallic character.

  12. Crystal structure of YbCu6In6 and mixed valence behavior of Yb in YbCu(6-x)In(6+x) (x = 0, 1, and 2) solid solution.

    PubMed

    Subbarao, Udumula; Peter, Sebastian C

    2012-06-04

    High quality single crystals of YbCu(6)In(6) have been grown using the flux method and characterized by means of single crystal X-ray diffraction data. YbCu(6)In(6) crystallizes in the CeMn(4)Al(8) structure type, tetragonal space group I4/mmm, and the lattice constants are a = b = 9.2200(13) Å and c = 5.3976(11) Å. The crystal structure of YbCu(6)In(6) is composed of pseudo-Frank-Kasper cages filled with one ytterbium atom in each ring. The neighboring cages share corners along [100] and [010] to build the three-dimensional network. YbCu(6-x)In(6+x) (x = 0, 1, and 2) solid solution compounds were obtained from high frequency induction heating and characterized using powder X-ray diffraction. The magnetic susceptibilities of YbCu(6-x)In(6+x) (x = 0, 1, and 2) were investigated in the temperature range 2-300 K and showed Curie-Weiss law behavior above 50 K, and the experimentally measured magnetic moment indicates mixed valent ytterbium. A deviation in inverse susceptibility data at 200 K suggests a valence transition from Yb(2+) to Yb(3+) as the temperature decreases. An increase in doping of Cu at the Al2 position enhances the disorder in the system and enhancement in the trivalent nature of Yb. Electrical conductivity measurements show that all compounds are of a metallic nature.

  13. Optical transitions of Tm3+ in oxyfluoride glasses and compositional and thermal effect on upconversion luminescence of Tm3+/Yb3+-codoped oxyfluoride glasses.

    PubMed

    Feng, Li; Wu, Yinsu; Liu, Zhuo; Guo, Tao

    2014-01-24

    Optical properties of Tm(3+)-doped SiO2-BaF2-ZnF2 glasses have been investigated on the basis of the Judd-Ofelt theory. Judd-Ofelt intensity parameters, radiative transition probabilities, fluorescence branching ratios and radiative lifetimes have been calculated for different glass compositions. Upconversion emissions were observed in Tm(3+)/Yb(3+)-codoped SiO2-BaF2-ZnF2 glasses under 980 nm excitation. The effects of composition, concentration of the doping ions, temperature, and excitation pump power on the upconversion emissions were also systematically studied. Copyright © 2013 Elsevier B.V. All rights reserved.

  14. From the ternary Eu(Au/In) 2 and EuAu 4(Au/In) 2 with remarkable Au/In distributions to a new structure type: The gold-rich Eu 5Au 16(Au/In) 6 structure

    DOE PAGES

    Steinberg, Simon; Card, Nathan; Mudring, Anja -Verena

    2015-08-13

    The ternary Eu(Au/In) 2 (EuAu 0.46In 1.54 (2)) (I), EuAu 4(Au/In) 2 (EuAu 4+xIn 2–x with x = 0.75(2) (II), 0.93(2), and 1.03(2)), and Eu 5Au 16(Au/In) 6 (Eu 5Au 17.29In 4.71(3)) (III) have been synthesized, and their structures were characterized by single-crystal X-ray diffraction. I and II crystallize with the CeCu 2-type (Pearson Symbol oI12; Imma; Z = 4; a = 4.9018(4) Å; b = 7.8237(5) Å; c = 8.4457(5) Å) and the YbAl 4Mo 2-type (tI14; I4/ mmm; Z = 2; a = 7.1612(7) Å; c = 5.5268(7) Å) and exhibit significant Au/In disorder. I is composed ofmore » an Au/In-mixed diamond-related host lattice encapsulating Eu atoms, while the structure of II features ribbons of distorted, squared Au 8 prisms enclosing Eu, Au, and In atoms. Combination of these structural motifs leads to a new structure type as observed for Eu 5Au 16(Au/In) 6 (Eu 5Au 17.29In 4.71(3)) (oS108; Cmcm; Z = 4; a = 7.2283(4) Å; b = 9.0499(6) Å; c = 34.619(2) Å), which formally represents a one-dimensional intergrowth of the series EuAu 2–“EuAu 4In 2”. The site preferences of the disordered Au/In positions in II were investigated for different hypothetical “EuAu 4(Au/In) 2” models using the projector-augmented wave method and indicate that these structures attempt to optimize the frequencies of the heteroatomic Au–In contacts. Furthermore, a chemical bonding analysis on two “EuAu 5In” and “EuAu 4In 2” models employed the TB-LMTO-ASA method and reveals that the subtle interplay between the local atomic environments and the bond energies determines the structural and site preferences for these systems.« less

  15. From the ternary Eu(Au/In) 2 and EuAu 4(Au/In) 2 with remarkable Au/In distributions to a new structure type: The gold-rich Eu 5Au 16(Au/In) 6 structure

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Steinberg, Simon; Card, Nathan; Mudring, Anja -Verena

    The ternary Eu(Au/In) 2 (EuAu 0.46In 1.54 (2)) (I), EuAu 4(Au/In) 2 (EuAu 4+xIn 2–x with x = 0.75(2) (II), 0.93(2), and 1.03(2)), and Eu 5Au 16(Au/In) 6 (Eu 5Au 17.29In 4.71(3)) (III) have been synthesized, and their structures were characterized by single-crystal X-ray diffraction. I and II crystallize with the CeCu 2-type (Pearson Symbol oI12; Imma; Z = 4; a = 4.9018(4) Å; b = 7.8237(5) Å; c = 8.4457(5) Å) and the YbAl 4Mo 2-type (tI14; I4/ mmm; Z = 2; a = 7.1612(7) Å; c = 5.5268(7) Å) and exhibit significant Au/In disorder. I is composed ofmore » an Au/In-mixed diamond-related host lattice encapsulating Eu atoms, while the structure of II features ribbons of distorted, squared Au 8 prisms enclosing Eu, Au, and In atoms. Combination of these structural motifs leads to a new structure type as observed for Eu 5Au 16(Au/In) 6 (Eu 5Au 17.29In 4.71(3)) (oS108; Cmcm; Z = 4; a = 7.2283(4) Å; b = 9.0499(6) Å; c = 34.619(2) Å), which formally represents a one-dimensional intergrowth of the series EuAu 2–“EuAu 4In 2”. The site preferences of the disordered Au/In positions in II were investigated for different hypothetical “EuAu 4(Au/In) 2” models using the projector-augmented wave method and indicate that these structures attempt to optimize the frequencies of the heteroatomic Au–In contacts. Furthermore, a chemical bonding analysis on two “EuAu 5In” and “EuAu 4In 2” models employed the TB-LMTO-ASA method and reveals that the subtle interplay between the local atomic environments and the bond energies determines the structural and site preferences for these systems.« less

  16. Yb:YAG disc for high energy laser systems

    NASA Astrophysics Data System (ADS)

    Nejezchleb, Karel; Kubát, Jan; Å ulc, Jan; Jelínková, Helena

    2017-02-01

    Large Yb:YAG crystals were grown using of new improved technology enabling to produce YAG crystals without central growth defect. The crystals diameter reached 115-120mm and their central part was used for manufacturing of discs with the diameter larger than 55 mm. Both sides of this discs were polished and coated. Doping concentration of Yb3+ ions in Yb:YAG crystals was measured using of X-ray fluorescence spectrometry. Absorption coefficient of Yb:YAG was measured for different doping concentration of Yb3+ ions. Fluorescence decay time of Yb:YAG was measured at temperatures of 300K and 80 K. We found the fluorescence decay time of the values of 0.95-1 ms at both temperatures stable and independent on the Yb3+ doping concentration in the range of 1-10 at.% Yb/Y demonstrating high chemical purity of grown crystals. Optical homogeneity as measured using of Fizeau double pass interferometer at 633nm resulted with PV values lower than 0.15 λ on clear aperture of 35 mm. Polished surfaces were ideally parallel with the wedge lower than 2 arcsec. Uniformity of laser properties of Yb:YAG was verified by scanning of the disc as active media in plan-convex pulsed laser resonator pumped by semiconductor diode (wavelength 969 nm, pumping beam diameter 100 μm). It was confirmed, that newly developed technology allows to manufacture very large high quality Yb:YAG discs suitable for high power lasers and amplifiers.

  17. Near infrared emission of TbAG:Ce3+,Yb3+ phosphor for solar cell applications

    NASA Astrophysics Data System (ADS)

    Meshram, N. D.; Yadav, P. J.; Pathak, A. A.; Joshi, C. P.; Moharil, S. V.

    2016-05-01

    Luminescent materials doped with rare earth ions are used for many devices such as optical amplifiers in telecommunication, phosphors for white light emitting diodes (LEDs), displays, and so on. Recently, they also have attracted a great interest for photovoltaic applications to improve solar cell efficiency by modifying solar spectrum. Crystal silicon (c-Si) solar cells most effectively convert photons of energy close to the semiconductor band gap. The mis-match between the incident solar spectrum and the spectral response of solar cells is one of the main reasons to limit the cell efficiency. The efficiency limit of the c-Si has been estimated to be 29% by Shockley and Queisser. However, this limit is estimated to be improved up to 38.4% by modifying the solar spectrum by a quantum cutting (down converting) phosphor which converts one photon of high energy into two photons of lower energy. The phenomenon such as the quantum cutting or the down conversion of rare earth ions have been investigated since Dexter reported the possibility of a luminescent quantum yield greater than unity in 1957. In the past, the quantum cutting from a vacuum ultraviolet photon to visible photons for Pr3+, Gd3+,Gd3+-Eu3+, and Er3+-Tb3+ had been studied. Recently, a new quantum cutting phenomenon from visible photon shorter than 500 nm to two infrared photons for Tb3+-Yb3+, Pr3+-Yb3+, and Tm3+-Yb3+ has been reported. The Yb3+ ion is suitable as an acceptor and emitter because luminescent quantum efficiency of Yb3+ is close to 100% and the energy of the only excited level of Yb3+ (1.2 eV) is roughly in accordance with the band gap of Si (1.1 eV). In addition, the Ce3+-doped Tb3Al5O12 (TbAG), used as a phosphor for white LED, has broad absorption bands in the range of 300-500 nm due to strong ligand field and high luminescent quantum efficiency. Therefore, the Ce3+ ions in the TbAG can be suitable as an excellent sensitizing donor for down conversion materials of Si solar cells. In this

  18. EuCo 2P 2: A Model Molecular-Field Helical Heisenberg Antiferromagnet

    DOE PAGES

    Sangeetha, N. S.; Cuervo-Reyes, Eduardo; Pandey, Abhishek; ...

    2016-07-19

    The metallic compound EuCo 2P 2 with the body-centered tetragonal ThCr 2Si 2 structure containing Eu spins-7/2 was previously shown from single-crystal neutron diffraction measurements to exhibit a helical antiferromagnetic (AFM) structure below T N=66.5 K with the helix axis along the c axis and with the ordered moments aligned within the ab plane. Here we report crystallography, electrical resistivity, heat capacity, magnetization, and magnetic susceptibility measurements on single crystals of this compound. We demonstrate that EuCo 2P 2 is a model molecular-field helical Heisenberg antiferromagnet from comparisons of the anisotropic magnetic susceptibility χ, high-field magnetization, and magnetic heat capacitymore » of EuCo 2P 2 single crystals at temperature T≤TN with the predictions of our recent formulation of molecular-field theory. Values of the Heisenberg exchange interactions between the Eu spins are derived from the data. The low-T magnetic heat capacity ~T 3 arising from spin-wave excitations with no anisotropy gap is calculated and found to be comparable to the lattice heat capacity. The density of states at the Fermi energy of EuCo 2P 2 and the related compound BaCo 2P 2 are found from the heat capacity data to be large, 10 and 16 states/eV per formula unit for EuCo 2P 2 and BaCo 2P 2, respectively. These values are enhanced by a factor of ~2.5 above those found from DFT electronic structure calculations for the two compounds. Additionally, the calculations also find ferromagnetic Eu–Eu exchange interactions within the ab plane and AFM interactions between Eu spins in nearest- and next-nearest planes, in agreement with the MFT analysis of χ ab(T≤TN).« less

  19. EuCo 2P 2: A Model Molecular-Field Helical Heisenberg Antiferromagnet

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Sangeetha, N. S.; Cuervo-Reyes, Eduardo; Pandey, Abhishek

    The metallic compound EuCo 2P 2 with the body-centered tetragonal ThCr 2Si 2 structure containing Eu spins-7/2 was previously shown from single-crystal neutron diffraction measurements to exhibit a helical antiferromagnetic (AFM) structure below T N=66.5 K with the helix axis along the c axis and with the ordered moments aligned within the ab plane. Here we report crystallography, electrical resistivity, heat capacity, magnetization, and magnetic susceptibility measurements on single crystals of this compound. We demonstrate that EuCo 2P 2 is a model molecular-field helical Heisenberg antiferromagnet from comparisons of the anisotropic magnetic susceptibility χ, high-field magnetization, and magnetic heat capacitymore » of EuCo 2P 2 single crystals at temperature T≤TN with the predictions of our recent formulation of molecular-field theory. Values of the Heisenberg exchange interactions between the Eu spins are derived from the data. The low-T magnetic heat capacity ~T 3 arising from spin-wave excitations with no anisotropy gap is calculated and found to be comparable to the lattice heat capacity. The density of states at the Fermi energy of EuCo 2P 2 and the related compound BaCo 2P 2 are found from the heat capacity data to be large, 10 and 16 states/eV per formula unit for EuCo 2P 2 and BaCo 2P 2, respectively. These values are enhanced by a factor of ~2.5 above those found from DFT electronic structure calculations for the two compounds. Additionally, the calculations also find ferromagnetic Eu–Eu exchange interactions within the ab plane and AFM interactions between Eu spins in nearest- and next-nearest planes, in agreement with the MFT analysis of χ ab(T≤TN).« less

  20. 10 W single-mode Er/Yb co-doped all-fiber amplifier with suppressed Yb-ASE

    NASA Astrophysics Data System (ADS)

    Sobon, G.; Sliwinska, D.; Abramski, K. M.; Kaczmarek, P.

    2014-02-01

    In this work we demonstrate a single-frequency, single-mode all-fiber master oscillator power amplifier (MOPA) source, based on erbium-ytterbium co-doped double-clad fiber emitting 10 W of continuous wave power at 1565 nm. In the power amplifier stage, the amplified spontaneous emission from Yb3+ ions (Yb-ASE) is forced to recirculate in a loop resonator in order to provide stable lasing at 1060 nm. The generated signal acts as an additional pump source for the amplifier and is reabsorbed by the Yb3+ ions in the active fiber, allowing an increase in the efficiency and boosting the output power. The feedback loop also protects the amplifier from parasitic lasing or self-pulsing at a wavelength of 1 μm. This allows one to significantly scale the output power in comparison to a conventional setup without any Yb-ASE control.

  1. Differences in photoluminescence properties and thermal degradation between nanoparticle and bulk particle BaMgAl10O17:Eu2+ phosphors under UV?VUV irradiation.

    PubMed

    Liu, Bitao; Xin, Shuangyu; Li, Fenghua; Zhang, Jiachi; Wang, Yuhua

    2014-05-01

    BaMgAl10O17:Eu2+ (BAM) phosphors used for plasma display panels and three-band fluorescence lamps are exposed to an oxidizing environment at about 500 degrees C, which is currently unavoidable in actual applications. We investigated the mechanism of the luminance degradation of BAM caused by annealing at 500 degrees C based on the difference in luminance degradation of bulk particle and nanoparticle samples under various excitation source irradiations. When the samples were excited by the different light sources, more than 30% degradation of luminance occurred under 147 nm while less than 10% degradation occurred under 254 nm both for nanoparticle and bulk particle samples. In addition, the luminescence degradation of nanophosphors shows a different tendency compared to the bulk phosphors. With a model based on the particle size and excitation light penetration depth, we demonstrate that the degradation is still mainly ascribed to the oxidized of divalent Eu. The differences in luminescence properties between nanophosphors and bulk phosphors are also illustrated by this model. As a result, the potential industrial applications of nanophosphors are evaluated.

  2. Synthesis and morphology of Ba{sub 1-x}RE{sub 2x/3}Nb{sub 2}O{sub 6} nanocrystals with tungsten bronze structure in RE{sub 2}O{sub 3}-BaO-Nb{sub 2}O{sub 5}-B{sub 2}O{sub 3} glasses (RE: Sm, Eu, Gd, Dy, Er)

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Ida, H.; Shinozaki, K.; Honma, T.

    2012-12-15

    Ba{sub 1-x}RE{sub 2x/3}Nb{sub 2}O{sub 6} nanocrystals with a tetragonal tungsten bronze (TTB) structure are synthesized using a conventional glass crystallization technique in 2.3RE{sub 2}O{sub 3}-27.4BaO-34.3Nb{sub 2}O{sub 5}-36B{sub 2}O{sub 3} (mol%) (RE=Sm, Eu, Gd, Dy, and Er) glasses. One sharp crystallization peak is observed at {approx}670 Degree-Sign C in both powdered and bulk glasses, and the formation of Ba{sub 1-x}RE{sub 2x/3}Nb{sub 2}O{sub 6} nanocrystals with unit cell parameters of a{approx}1.24 nm and c{approx}0.39 nm was confirmed. It is found from high resolution transmission electron microscope observations that the morphology of Ba{sub 1-x}RE{sub 2x/3}Nb{sub 2}O{sub 6} nanocrystals is ellipsoidal. Their average particlemore » size is in the range of 15-60 nm and decreases with decreasing ionic radius of RE{sup 3+} being present in the precursor glasses. The optical transparent crystallized glass (bulk) shows the total photoluminescence (PL) quantum yield of 53% in the visible region of Eu{sup 3+} ions, suggesting a high potential of Ba{sub 1-x}RE{sub 2x/3}Nb{sub 2}O{sub 6} nanocrystals as PL materials. - Graphical abstract: This figure shows a TEM photograph for the heat-treated (667 Degree-Sign C, 3 h) sample of 2.3Dy{sub 2}O{sub 3}-27.4BaO-34.3Nb{sub 2}O{sub 5}-36B{sub 2}O{sub 3}. An ellipsoidal-shaped Ba{sub 1-x}Dy{sub 2x/3}Nb{sub 2}O{sub 6} nanocrystal with diameters of 17 and 28 nm is observed. The ellipsoidal morphology is a common feature in Ba{sub 1-x}RE{sub 2x/3}Nb{sub 2}O{sub 6} nanocrystals synthesized by the crystallization of 2.3RE{sub 2}O{sub 3}-27.4BaO-34.3Nb{sub 2}O{sub 5}-36B{sub 2}O{sub 3} glasses. Highlights: Black-Right-Pointing-Pointer Ba{sub 1-x}RE{sub 2x/3}Nb{sub 2}O{sub 6} nanocrystals with a tetragonal tungsten bronze structure are synthesized. Black-Right-Pointing-Pointer A glass crystallization technique was applied. Black-Right-Pointing-Pointer The morphology of Ba{sub 1-x}RE{sub 2x/3}Nb{sub 2}O{sub 6} nanocrystals

  3. Structural and luminescent study of TeO2-BaO-Bi2O3-Ag glass system doped with Eu3+ and Dy3+ for possible color-tunable phosphor application

    NASA Astrophysics Data System (ADS)

    Lewandowski, Tomasz; Seweryński, Cezary; Walas, Michalina; Łapiński, Marcin; Synak, Anna; Sadowski, Wojciech; Kościelska, Barbara

    2018-05-01

    Tellurite glass systems of 73TeO2-4BaO-3Bi2O3-1Ag:xEu2O3-(2-x)Dy2O3 (where x = 0.5, 1, 1.5, 2 in molar ratio) composition have been successfully synthesized. In order to acquire Ag nanoparticles, materials have been heat treated at 350 °C in the air atmosphere. Structural properties of obtained samples were evaluated with various techniques. X-Ray Diffraction (XRD) measurements indicated that obtained materials are amorphous in nature. UV-vis results presented transitions characteristic to Dy3+ and Eu3+ ions. Additionally, X-Ray Photoelectron Spectroscopy (XPS) analysis indicated the presence of silver in metallic form. Photoluminescence measurements shown influence of Ag nanoparticles on emission characteristics. Simultaneous emission of Dy3+ and Eu3+ has been observed when samples were excited with λexc = 390 nm. Change of the emission color induced by heat treatment has been observed and described in case of x = 1 glass series. According to CIE results emission color changes as Eu/Dy ratio and heat treatment time are changed. Emission shifts from reddish-orange to yellowish white color. Obtained photoluminescence results confirm that synthesized materials are good candidates for color tunable phosphors.

  4. Crystal and electronic structures, luminescence properties of Eu 2+-doped Si 6-zAl zO zN 8-z and M ySi 6-zAl z-yO z+yN 8-z-y ( M=2Li, Mg, Ca, Sr, Ba)

    NASA Astrophysics Data System (ADS)

    Li, Y. Q.; Hirosaki, N.; Xie, R. J.; Takeda, T.; Mitomo, M.

    2008-12-01

    The crystal structure, electronic structure, and photoluminescence properties of Eu xSi 6-zAl z-xO z+xN 8-z-x ( x=0-0.1, 0< z<1) and Eu xM ySi 6-zAl z-x-yO z+x+yN 8-z-x-y ( M=2Li, Mg, Ca, Sr, Ba) have been studied. Single-phase Eu xSi 6-zAl z-xO z+xN 8-z-x can be obtained in very narrow ranges of x⩽0.06 ( z=0.15) and z<0.5 ( x=0.3), indicating that limited Eu 2+ ions can be incorporated into nitrogen-rich Si 6-zAl zO zN 8-z. The Eu 2+ ion is found to occupy the 2 b site in a hexagonal unit cell ( P6 3/ m) and directly connected by six adjacent nitrogen/oxygen atoms ranging 2.4850-2.5089 Å. The calculated host band gaps by the relativistic DV-X α method are about 5.55 and 5.45 eV (without Eu 2+ 4 f5 d levels) for x=0 and 0.013 in Eu xSi 6-zAl z-xO z+xN 8-z-x ( z=0.15), in which the top of the 5 d orbitals overlap with the Si-3 s3 p and N-2 p orbitals within the bottom of the conduction band of the host. Eu xSi 6-zAl z-xO z+xN 8-z-x shows a strong green emission with a broad Eu 2+ band centered at about 530 nm under UV to near-UV excitation range. The excitation and emission spectra are hardly modified by Eu concentration and dual-doping ions of Li and other alkaline-earth ions with Eu. Higher Eu concentrations can significantly quench the luminescence of Eu 2+ and decrease the thermal quenching temperature. In addition, the emission spectrum can only be slightly tuned to the longer wavelengths (˜529-545 nm) by increasing z within the solid solution range of z<0.5. Furthermore, the luminescence intensity of Eu xSi 6-zAl z-xO z+xN 8-z-x can be improved by increasing z and the dual-doping of Li and Ba.

  5. Structural and optical properties of rare earth-doped (Ba{sub 0.77}Ca{sub 0.23}){sub 1-x}(Sm, Nd, Pr, Yb){sub x}TiO{sub 3}

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Moraes, A. P. A.; Universidade Federal do Mato Grosso, 78060-900, Araguaia-MT; Filho, A. G. Souza

    2011-06-15

    The structural, dielectric, and vibrational properties of pure and rare earth (RE)-doped Ba{sub 0.77}Ca{sub 0.23}TiO{sub 3} (BCT23; RE = Nd, Sm, Pr, Yb) ceramics obtained via solid-state reaction were investigated. The pure and RE-doped BCT23 ceramics sintered at 1450 deg. C in air for 4 h showed a dense microstructure in all ceramics. The use of RE ions as dopants introduced lattice-parameter changes that manifested in the reduction of the volume of the unit cell. RE-doped BCT23 samples exhibit a more homogenous microstructure due to the absence of a Ti-rich phase in the grain boundaries as demonstrated by scanning electronmore » microscopy imaging. The incorporation of REs led to perturbations of the local symmetry of TiO{sub 6} octahedra and the creation of a new Raman mode. The results of Raman scattering measurements indicated that the Curie temperature of the ferroelectric phase transition depends on the RE ion and ion content, with the Curie temperature shifting toward lower values as the RE content increases, with the exception of Yb{sup 3+} doping, which did not affect the ferroelectric phase transition temperature. The phase transition behavior is explained using the standard soft mode model. Electronic paramagnetic resonance measurements showed the existence of Ti vacancies in the structure of RE-doped BCT23. Defects are created via charge compensation mechanisms due to the incorporation of elements with a different valence state relative to the ions of the pure BCT23 host. It is concluded that the Ti vacancies are responsible for the activation of the Raman mode at 840 cm{sup -1}, which is in agreement with lattice dynamics calculations.« less

  6. Electrodynamic response of the type-II Weyl semimetal YbMnBi 2

    DOE PAGES

    Chinotti, M.; Pal, A.; Ren, W. J.; ...

    2016-12-01

    Weyl fermions play a major role in quantum field theory but have been quite elusive as fundamental particles. These quasi-two-dimensional bismuth layers based materials were recently designed and provide an arena for studying the interplay between anisotropic Dirac fermions, magnetism, and structural changes, allowing the formation of Weyl fermions in condensed matter. We perform an optical investigation of YbMnBi 2 , a representative type-II Weyl semimetal, and contrast its excitation spectrum with the optical response of the more conventional semimetal EuMnBi 2 . This comparative study allows us to disentangle the optical fingerprints of type-II Weyl fermions, but also challengesmore » the present theoretical understanding of their electrodynamic response.« less

  7. Single crystals of the fluorite nonstoichiometric phase Eu{0.916/2+}Eu{0.084/3+}F2.084 (conductivity, transmission, and hardness)

    NASA Astrophysics Data System (ADS)

    Sobolev, B. P.; Turkina, T. M.; Sorokin, N. I.; Karimov, D. N.; Komar'kova, O. N.; Sulyanova, E. A.

    2010-07-01

    The nonstoichiometric phase EuF2+ x has been obtained via the partial reduction of EuF3 by elementary Si at 900-1100°C. Eu{0.916/2+}Eu{0.084/3+}F2.084 (EuF2.084) single crystals have been grown from melt by the Bridgman method in a fluorinating atmosphere. These crystals belong to the CaF2 structure type (sp. gr. Fm bar 3 m) with the cubic lattice parameter a = 5.8287(2) Å, are transparent in the spectral range of 0.5-11.3 μm, and have microhardness H μ = 3.12 ± 0.13 GPa and ionic conductivity σ = 1.4 × 10-5 S/cm at 400°C with the ion transport activation energy E a = 1.10 ± 0.05 eV. The physicochemical characteristics of the fluorite phases in the EuF2 - EuF3 systems are similar to those of the phases in the SrF2 - EuF3 and SrF2 - GdF3 systems due to the similar lattice parameters of the EuF2 and SrF2 components. Europium difluoride supplements the list of fluorite components MF2 ( M = Ca, Sr, Ba, Cd, Pb), which are crystal matrices for nonstoichiometric (nanostructured) fluoride materials M 1 - x R x F2 + x ( R are rare earth elements).

  8. Partial melting under conditions of filter pressing: field and geochemical evidence from the migmatites of NE Minnesota

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Sheehan, T.J.; Bauer, R.L.; Nabelek, P.I.

    1985-01-01

    Amphibolite-grade Archean migmatites in the southern Vermilion Granitic Complex with well-defined paleosome-melanosome and melanosome-leucosome boundaries and with exceptionally wide melanosomes (on the order of centimeters) were studied to elucidate granite-forming processes during high-grade metamorphism. Metagreywacke paleosomes containing 50% plag, 28% qtz, 20% biot and minor hbld, and apat, have (Ce/Yb)/sub N/ = 13.5 to 21 with 650-960 ppm Ba, 42-110 ppm Rb, and 982-1159 ppm Sr. Melanosomes containing 45% plag, 35% biot, 20% hbld and minor qtz and apat, have (Ce/Yb)/sub N/ = 6.8 to 9.3 and have 950-1750 ppm Ba, 41-194 ppm Rb, and 1020-1926 ppm Sr. Leucosomes containingmore » 82% plag, 13% qtz, 5% biot and minor hbld and apat, have overall depleted REE patterns with positive Eu anomalies and 460-750 ppm Ba, 41-43 ppm Rb, and 1876-2106 ppm Sr, suggesting cumulate plagioclase. Mass balance calculations preclude formation of the melanosome from mixing the paleosomes and leucosomes. However, major and trace element modeling suggest that the leucosome formed by in situ partial melting followed by fractional crystallization and filter pressing which resulted in the removal of the residual liquid. Model REE patterns for the melt drive off by this process are REE enriched with a negative Eu anomaly. Such patterns which have been found in some low Sr granites are difficult to produce by simple belting models. Partial melting under conditions of tectonic stress may thus provide an explanation for such granites.« less

  9. Use of Yb(III) Centered Near Infra-Red (NIR) Luminescence to Determine the Hydration State of a 3,2-HOPO based MRI-Contrast Agent

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Moore, Evan G.; Seitz, Michael; Raymond, Kenneth N.

    It has been more than a decade since the first reports of [Gd(Tren-Me-3,2-HOPO)(H{sub 2}O){sub 2}] as a potential new class of magnetic resonance imaging contrast agent (MRI-CA). The defining feature of these 1-methyl-3-hydroxypyridin-2-one (Me-3,2-HOPO) based compounds has been the use of a hexadentate ligand design, and hence an increase in the number of metal bound water molecules, without sacrificing complex stability compared to the typically octadentate contrast agents used commercially. Since that time, significant advances in the properties of these chelates have been steadily reported, including improvements in relaxivity, incorporation into macromolecular architectures and, recently, the first direct verification ofmore » solution structure using the discovery of Eu(III) centered luminescence with the isomeric 1-hydroxypyridin-2-one (1,2-HOPO) chelate as a sensitizing chromophore. Nonetheless, it has remained frustrating that direct measurements of the inner sphere hydration state, q, using luminescence techniques with the parent Me-3,2-HOPO compounds have remained elusive, even when direct laser excitation of weakly absorbing f-f transitions were employed (eg. for Eu(III) complexes). This failing can likely be traced to the presence of a low lying LMCT state which efficiently quenches metal based emission. Instead, estimates of the q and hence solution structure have relied on the fitting of relaxivity data to the Solomon-Bloembergen-Morgan equations or, where sufficiently soluble in aqueous solution, studies on the temperature dependence of the paramagnetic contribution to the water {sup 17}O NMR transverse relaxation rate. Recently, Beeby et al reported on a qualitative equation to determine inner sphere hydration based on the change in lifetimes for Yb(III) in going from H{sub 2}O to D{sub 2}O solution, and we reasoned that the lower energy accepting state of Yb(III) may lie below the LMCT state which quenches Eu(III) emission, and hence may

  10. Transport, Thermal, and Magnetic Properties of YbNi3X9 (X = Al, Ga): A Newly Synthesized Yb-Based Kondo Lattice System

    NASA Astrophysics Data System (ADS)

    Yamashita, Tetsuro; Miyazaki, Ryoichi; Aoki, Yuji; Ohara, Shigeo

    2012-03-01

    We have succeeded in synthesizing a new Yb-based Kondo lattice system, YbNi3X9 (X = Al, Ga). Our study reveals that YbNi3Al9 shows typical features of a heavy-fermion antiferromagnet with a Néel temperature of TN = 3.4 K. All of the properties reflect a competition between the Kondo effect and the crystalline electric field (CEF) effect. The moderate heavy-fermion state leads to an enhanced Sommerfeld coefficient of 100 mJ/(mol\\cdotK2), even if ordered antiferromagnetically. On the other hand, the isostructural gallide YbNi3Ga9 is an intermediate-valence system with a Kondo temperature of TK = 570 K. A large hybridization scale can overcome the CEF splitting energy, and a moderately heavy Fermi-liquid ground state with high local moment degeneracy should form at low temperatures. Note that the quality of single-crystalline YbNi3X9 is extremely high compared with those of other Yb-based Kondo lattice compounds. We conclude that YbNi3X9 is a suitable system for investigating the electronic structure of Yb-based Kondo lattice systems from a heavy-fermion system with an antiferromagnetically ordered ground state to an intermediate-valence system.

  11. X-ray Excitation Triggers Ytterbium Anomalous Emission in CaF2:Yb but Not in SrF2:Yb.

    PubMed

    Hughes-Currie, Rosa B; Ivanovskikh, Konstantin V; Wells, Jon-Paul R; Reid, Michael F; Gordon, Robert A; Seijo, Luis; Barandiarán, Zoila

    2017-03-16

    Materials that luminesce after excitation with ionizing radiation are extensively applied in physics, medicine, security, and industry. Lanthanide dopants are known to trigger crystal scintillation through their fast d-f emissions; the same is true for other important applications as lasers or phosphors for lighting. However, this ability can be seriously compromised by unwanted anomalous emissions often found with the most common lanthanide activators. We report high-resolution X-ray-excited optical (IR to UV) luminescence spectra of CaF 2 :Yb and SrF 2 :Yb samples excited at 8949 eV and 80 K. Ionizing radiation excites the known anomalous emission of ytterbium in the CaF 2 host but not in the SrF 2 host. Wave function-based ab initio calculations of host-to-dopant electron transfer and Yb 2+ /Yb 3+ intervalence charge transfer explain the difference. The model also explains the lack of anomalous emission in Yb-doped SrF 2 excited by VUV radiation.

  12. High dispersibility and enhanced luminescence properties of BaMgAl10O17:Eu2+ phosphors derived from molten salt synthesis

    NASA Astrophysics Data System (ADS)

    Wang, Xiang; Li, Jin-hong; Shi, Ping-lu; Guan, Wei-min; Zhang, Hong-yao

    2015-08-01

    BaMgAl10O17:Eu2+ (BAM) phosphors were prepared via the molten salt synthesis (MSS) method. The NaCl-KCl eutectic mixture and LiF were used as the molten salt and flux, respectively. X-ray powder diffraction (XRD) patterns indicate that the BAM phase is formed above 1200 °C and that the addition of LiF leads to an obvious improvement in crystallinity. The emission intensity of the BAM phosphor with 10 wt% LiF is about 85% higher than that of the phosphor without LiF and about 200% higher than that of the phosphor without molten salt and LiF. Scanning electron microscopy (SEM) reveal that the as-prepared phosphors have good crystallinity and regular morphology, and most importantly, they are not aggregated. Li+ doping is benefit for the thermal stability and results in a slightly longer decay times of 1.17 μs.

  13. Electroluminescent Yb2O3:Er and Yb2Si2O7:Er nanolaminate films fabricated by atomic layer deposition on silicon

    NASA Astrophysics Data System (ADS)

    Ouyang, Zhongtao; Yang, Yang; Sun, Jiaming

    2018-06-01

    Atomic layer doped Yb2O3:Er and Yb2Si2O7:Er nanolaminate films are fabricated on silicon by atomic layer deposition, and ∼1530 nm electroluminescence (EL) is obtained from the metal-oxide-semiconductor light-emitting devices (MOSLEDs) based on these films. The Yb2O3 films transfer to Yb2Si2O7 phase after annealing above 1000 °C. Intense photoluminescence from Yb2Si2O7 film confirms high efficiency and energy transfer under optical excitation, but the limited electron conduction restricts the EL performance. EL from the Yb2O3:Er MOSLED outperforms, presenting an external quantum efficiency up to 8.5% and the power efficiency of 1 × 10-3. The EL is derived to result from the impact excitation of Er3+ ions by hot electrons, which stem from Fowler-Nordheim tunneling mechanism under sufficient bias voltage. The critical distance for the cross relaxation of doped Er3+ ions in nanolaminate Yb2O3 matrix is experimentally determined to be ∼3 nm. Such devices manifest the technological potential of Er-doped Yb-oxides for applications in silicon-based optoelectronics.

  14. Understanding the photoluminescence characteristics of Eu{sup 3+}-doped double-perovskite by electronic structure calculation

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Ghosh, Binita; Halder, Saswata; Sinha, T. P.

    2016-05-23

    Europium-doped luminescent barium samarium tantalum oxide Ba{sub 2}SmTaO{sub 6} (BST) has been investigated by first-principles calculation, and the crystal structure, electronic structure, and optical properties of pure BST and Eu-doped BST have been examined and compared. Based on the calculated results, the luminescence properties and mechanism of Eu-doped BST has been discussed. In the case of Eu-doped BST, there is an impurity energy band at the Fermi level, which is formed by seven spin up energy levels of Eu and act as the luminescent centre, which is evident from the band structure calculations.

  15. Consequences of Optimal Bond Valence on Structural Rigidity and Improved Luminescence Properties in Sr xBa 2-xSiO 4:Eu 2+ Orthosilicate Phosphors

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Denault, Kristin A.; Brgoch, Jakoah; Gaultois, Michael W.

    The orthosilicate phosphors Sr xBa 2–xSiO 4:Eu 2+ have now been known for over four decades and have found extensive recent use in solid-state white lighting. It is well-recognized in the literature and in practice that intermediate compositions in the solid-solutions between the orthosilicates Sr 2SiO 4 and Ba 2SiO 4 yield the best phosphor hosts when the thermal stability of luminescence is considered. We employ a combination of synchrotron X-ray diffraction, total scattering measurements, density functional theory calculations, and low-temperature heat capacity measurements, in conjunction with detailed temperature- and time-resolved studies of luminescence properties to understand the origins ofmore » the improved luminescence properties. We observe that in the intermediate compositions, the two cation sites in the crystal structure are optimally bonded as determined from bond valence sum calculations. Optimal bonding results in a more rigid lattice, as established by the intermediate compositions possessing the highest Debye temperature, which are determined experimentally from low-temperature heat capacity measurements. Greater rigidity in turn results in the highest luminescence efficiency for intermediate compositions at elevated temperatures.« less

  16. Divalent europium doped CaF 2 and BaF 2 nanocrystals from ionic liquids

    DOE PAGES

    Anghel, Sergiu; Golbert, Sebastian; Meijerink, Andries; ...

    2016-10-11

    A new, facile and quick synthesis method for Eu 2+ doped the alkaline earth fluorides was developed using ionic liquids as solvent, precursor and capping agent. Reductive atmosphere and very high temperatures were avoided, while still attaining the desired structure, small particle sizes and divalent oxidation state of the lanthanide. Here, this opens the door for the development of new Ln 2+ doped nanomaterials. Here, the successful Eu 2+ incorporation was proven by optical spectroscopic measurements which showed the spin and parity allowed f-d transitions of Eu 2+ in CaF 2:Eu 2+/BaF 2:Eu 2+. 4f 7-4f 7 transitions could bemore » observed at low temperatures (7 K).« less

  17. Lifetime measurement in ^170Yb

    NASA Astrophysics Data System (ADS)

    Wang, Z.; Krücken, R.; Beausang, C. W.; Casten, R. F.; Cooper, J. R.; Cederkäll, J.; Caprio, M.; Novak, J. R.; Zamfir, N. V.; Barton, C.

    1999-10-01

    The nature of the low lying K^π=0^+ excitations in deformed nuclei have recently been subject of intense discussion. In this context we present results from a Coulomb excitation experiment on ^170Yb using a 70MeV ^16O beam on a gold backed, 1.5 mg/cm^2 thick ^170Yb target. The beam was delivered by the ESTU tandem accelerator of WNSL at Yale University. Gamma rays were detected by the YRAST Ball array in coincidence with back-scattered ^16O particles, which were detected in an array of 8 solar cells. Lineshapes were observed for several transitions from collective states in ^170Yb and the lifetimes for those states were extracted using a standard DSAM analysis. The results will be presented together with a short introduction to the solar cell array at Yale (SCARY) that was used to make angular selection of the excited ^170Yb nuclei. This work is supported by the US-DOE under grant numbers DE-FG02-91ER-40609 and DE-FG02-88ER-40417.

  18. The new model of chemical evolution of r-process elements based on the hierarchical galaxy formation. I. Ba and Eu

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Komiya, Yutaka; Suda, Takuma; Yamada, Shimako

    2014-03-10

    We investigate the chemical enrichment of r-process elements in the early evolutionary stages of the Milky Way halo within the framework of hierarchical galaxy formation using a semi-analytic merger tree. In this paper, we focus on heavy r-process elements, Ba and Eu, of extremely metal-poor (EMP) stars and give constraints on their astronomical sites. Our models take into account changes of the surface abundances of EMP stars by the accretion of interstellar medium (ISM). We also consider metal-enrichment of intergalactic medium by galactic winds and the resultant pre-enrichment of proto-galaxies. The trend and scatter of the observed r-process abundances aremore » well reproduced by our hierarchical model with ∼10% of core-collapse supernovae in low-mass end (∼10 M {sub ☉}) as a dominant r-process source and the star formation efficiency of ∼10{sup –10} yr{sup –1}. For neutron star mergers as an r-process source, their coalescence timescale has to be ∼10{sup 7} yr, and the event rates ∼100 times larger than currently observed in the Galaxy. We find that the accretion of ISM is a dominant source of r-process elements for stars with [Ba/H] < –3.5. In this model, a majority of stars at [Fe/H] < –3 are formed without r-process elements, but their surfaces are polluted by the ISM accretion. The pre-enrichment affects ∼4% of proto-galaxies, and yet, is surpassed by the ISM accretion in the surface of EMP stars.« less

  19. Identification and characterization of NF-YB family genes in tung tree.

    PubMed

    Yang, Susu; Wang, Yangdong; Yin, Hengfu; Guo, Haobo; Gao, Ming; Zhu, Huiping; Chen, Yicun

    2015-12-01

    The NF-YB transcription factor gene family encodes a subunit of the CCAAT box-binding factor (CBF), a highly conserved trimeric activator that strongly binds to the CCAAT box promoter element. Studies on model plants have shown that NF-YB proteins participate in important developmental and physiological processes, but little is known about NF-YB proteins in trees. Here, we identified seven NF-YB transcription factor-encoding genes in Vernicia fordii, an important oilseed tree in China. A phylogenetic analysis separated the genes into two groups; non-LEC1 type (VfNF-YB1, 5, 7, 9, 11, 13) and LEC1-type (VfNF-YB 14). A gene structure analysis showed that VfNF-YB 5 has three introns and the other genes have no introns. The seven VfNF-YB sequences contain highly conserved domains, a disordered region at the N terminus, and two long helix structures at the C terminus. Phylogenetic analyses showed that VfNF-YB family genes are highly homologous to GmNF-YB genes, and many of them are closely related to functionally characterized NF-YBs. In expression analyses of various tissues (root, stem, leaf, and kernel) and the root during pathogen infection, VfNF-YB1, 5, and 11 were dominantly expressed in kernels, and VfNF-YB7 and 9 were expressed only in the root. Different VfNF-YB family genes showed different responses to pathogen infection, suggesting that they play different roles in the pathogen response. Together, these findings represent the first extensive evaluation of the NF-YB family in tung tree and provide a foundation for dissecting the functions of VfNF-YB genes in seed development, stress adaption, fatty acid synthesis, and pathogen response.

  20. Growth of EuO Single Crystals at Reduced Temperatures

    NASA Astrophysics Data System (ADS)

    Besara, Tiglet; Ramirez, Daniel; Whalen, Jeffrey; Siegrist, Theo

    Single crystals of Eu1-xBaxO have been grown in a barium-magnesium flux at moderate temperatures up to 1000°C, producing single crystals with barium doping levels ranging from x = 0 . 03 to x = 0 . 25 . Magnetic measurements show that the ferromagnetic Curie temperature TC correlates with the Ba doping levels, and a modified Heisenberg model is employed to describe the TC dependence on the stoichiometry. The decrease in TC is dominated by the Ba substitution on the Eu lattice with a small contribution arising from the lattice strain. Extrapolation of results indicates that a sample at x = 0 . 72 should have a TC = 0 K, potentially producing a quantum phase transition in this material. DOE SC-0008832, NSF DMR-1157490. This work was supported by the Department of Energy, Office of Basic Science, under contract DOE SC-0008832. This work has been performed at the National High Magnetic Field Laboratory, which is supported by the National Science Foundation Cooperative Agreement DMR-1157490, the State of Florida, and the U.S. Department of Energy.

  1. Laser-diode pumped 40-W Yb:YAG ceramic laser.

    PubMed

    Hao, Qiang; Li, Wenxue; Pan, Haifeng; Zhang, Xiaoyi; Jiang, Benxue; Pan, Yubai; Zeng, Heping

    2009-09-28

    We demonstrated a high-power continuous-wave (CW) polycrystalline Yb:YAG ceramic laser pumped by fiber-pigtailed laser diode at 968 nm with 400 mum fiber core. The Yb:YAG ceramic laser performance was compared for different Yb(3+) ion concentrations in the ceramics by using a conventional end-pump laser cavity consisting of two flat mirrors with output couplers of different transmissions. A CW laser output of 40 W average power with M(2) factor of 5.8 was obtained with 5 mol% Yb concentration under 120 W incident pump power. This is to the best of our knowledge the highest output power in end-pumped bulk Yb:YAG ceramic laser.

  2. Muramyl peptides activate innate immunity conjointly via YB1 and NOD2.

    PubMed

    Laman, Alexander G; Lathe, Richard; Shepelyakovskaya, Anna O; Gartseva, Alexandra; Brovko, Feodor A; Guryanova, Svetlana; Alekseeva, Ludmila; Meshcheryakova, Elena A; Ivanov, Vadim T

    2016-11-01

    Bacterial cell wall muramyl dipeptide (MDP) and glucosaminyl-MDP (GMDP) are potent activators of innate immunity. Two receptor targets, NOD2 and YB1, have been reported; we investigated potential overlap of NOD2 and YB1 pathways. Separate knockdown of NOD2 and YB1 demonstrates that both contribute to GMDP induction of NF-κB expression, a marker of innate immunity, although excess YB1 led to induction in the absence of NOD2. YB1 and NOD2 co-migrated on sucrose gradient centrifugation, and GMDP addition led to the formation of higher molecular mass complexes containing both YB1 and NOD2. Co-immunoprecipitation demonstrated a direct interaction between YB1 and NOD2, a major recombinant fragment of NOD2 (NACHT-LRR) bound to YB1, and complex formation was stimulated by GMDP. We also report subcellular colocalization of NOD2 and YB1. Although YB1 may have other binding partners in addition to NOD2, maximal innate immunity activation by muramyl peptides is mediated via an interaction between YB1 and NOD2.

  3. Luminescence in Ba2 Sr2 Al2 O7 :RE (RE = Tb(3) (+) ,Eu(3) (+) and Dy(3) (+) ) novel aluminate phosphors.

    PubMed

    Pardhi, S A; Panse, V R; Dhoble, S J

    2016-09-01

    The luminescence of novel rare earth (Tb(3) (+) , Eu(3) (+) and Dy(3) (+) )-activated Ba2 Sr2 Al2 O7 phosphors for solid-state lighting is presented. The aluminate phosphors were synthesized using a one-step combustion method. X-Ray diffraction, scanning electron microscopy and photoluminescence characterizations were performed to understand the mechanism of excitation and the corresponding emission in the as-prepared phosphor, as characterized the phase purity and microstructure. Improvements in the luminescence properties of the phosphors with rare earth concentration were observed. The phosphor hue could be tuned from blue, green and red by proper selection of rare earth ions in typical concentrations. Effective absorption in the near-ultraviolet region was observed, which makes the phosphor a potential candidate for ultraviolet light-emitting diodes. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

  4. Europium mixed-valence, long-range magnetic order, and dynamic magnetic response in EuCu 2 ( Si x Ge 1 - x ) 2

    DOE PAGES

    Nemkovski, Krill S.; Kozlenko, D. P.; Alekseev, Pavel A.; ...

    2016-11-01

    In mixed-valence or heavy-fermion systems, the hybridization between local f orbitals and conduction band states can cause the suppression of long-range magnetic order, which competes with strong spin uctuations. Ce- and Yb-based systems have been found to exhibit fascinating physical properties (heavy-fermion superconductivity, non-Fermi-liquid states, etc.) when tuned to the vicinity of magnetic quantum critical points by use of various external control parameters (temperature, magnetic eld, chemical composition). Recently, similar effects (mixed-valence, Kondo uctuations, heavy Fermi liquid) have been reported to exist in some Eu-based compounds. Unlike Ce (Yb), Eu has a multiple electron (hole) occupancy of its 4f shell,more » and the magnetic Eu 2+ state (4f 7) has no orbital component in the usual LS coupling scheme, which can lead to a quite different and interesting physics. In the EuCu 2(Si xGe 1-x) 2 series, where the valence can be tuned by varying the Si/Ge ratio, it has been reported that a significant valence uctuation can exist even in the magnetic order regime. This paper presents a detailed study of the latter material using different microscopic probes (XANES, Mossbauer spectroscopy, elastic and inelastic neutron scattering), in which the composition dependence of the magnetic order and dynamics across the series is traced back to the change in the Eu valence state. In particular, the results support the persistence of valence uctuations into the antiferromagnetic state over a sizable composition range below the critical Si concentration x c ≈ 0:65. In conclusion, the sequence of magnetic ground states in the series is shown to re ect the evolution of the magnetic spectral response.« less

  5. Relativistic coupled-cluster calculations of the 173Yb nuclear quadrupole coupling constant for the YbF molecule

    NASA Astrophysics Data System (ADS)

    Pašteka, L. F.; Mawhorter, R. J.; Schwerdtfeger, P.

    2016-04-01

    We report calculations on the q(Yb) electric field gradient (EFG) for the X2Σ+ and A2Π1/2 electronic states of the ytterbium monofluoride (YbF) molecule at the molecular mean-field Dirac-Coulomb-Gaunt as well as scalar-relativistic coupled-cluster levels of theory using large uncontracted basis sets. Vibrational contributions are included in the final results. Our estimated nuclear quadrupole coupling constants of -3386(78) MHz and -2083(153) MHz for the X2Σ+ and A2Π1/2 states of 173YbF are in stark contrast to the only available experimental results (-2050(170) MHz and -1090(160) MHz) respectively, where the only similarity is the difference between the two values. Perturbative triple contributions in the coupled cluster treatment are significant and point towards the necessity to go to higher order in the coupled-cluster treatment in future calculations. We also present density functional calculations which show rather large variations for the Yb EFG with different functionals used; the best result was obtained using the CAM-B3LYP* functional.

  6. A novel fluorescent probe (dtpa-bis(cytosine)) for detection of Eu(III) in rare earth metal ions

    NASA Astrophysics Data System (ADS)

    Yang, Fan; Ren, Peipei; Liu, Guanhong; Song, Youtao; Bu, Naishun; Wang, Jun

    2018-03-01

    In this paper, a novel fluorescent probe, dtpa-bis(cytosine), was designed and synthesized for detecting europium (Eu3 +) ion. Upon addition of Eu3 + ions into the dtpa-bis(cytosine) solution, the fluorescence intensity can strongly be enhanced. Conversely, adding other rare earth metal ions, such as Y3 +, Ce3 +, Pr3 +, Nd3 +, Sm3 +, Gd3 +, Tb3 +, Dy3 +, Ho3 +, Er3 +, Yb3 + and Lu3 +, into dtpa-bis(cytosine) solution, the fluorescence intensity is decreased slightly. Some parameters affecting the fluorescence intensity of dtpa-bis(cytosine) solution in the presence of Eu3 + ions were investigated, including solution pH value, Eu3 + ion concentration and interfering substances. The detection mechanism of Eu3 + ion using dtpa-bis(cytosine) as fluorescent probe was proposed. Under optimum conditions, the fluorescence emission intensities of EuIII-dtpa-bis(cytosine) at 375 nm in the concentration range of 0.50 × 10- 5 mol • L- 1-5.00 × 10- 5 mol • L- 1 of Eu3 + ion display a better linear relationship. The limit of detection (LOD) was determined as 8.65 × 10- 7 mol • L- 1 and the corresponding correlation coefficient (R2) of the linear equation is 0.9807. It is wished that the proposed method could be applied for sensitively and selectively detecting Eu3 + ion.

  7. Covalently-bonded grafting of [Ln3(Benzimidazole)4]-arrayed (Ln = Tb, Nd, Yb or Er) complex monomers into PNBE (poly(norbornene)) with highly luminous color-purity green-light or efficient NIR luminescence

    NASA Astrophysics Data System (ADS)

    Liu, Lin; Fu, Guorui; Feng, Heini; Guan, Jiaqing; Li, Fengping; Lü, Xingqiang; Wong, Wai-Kwok; Jones, Richard A.

    2017-07-01

    Within series of Ln3-grafted polymers Poly({[Ln3(L)4(NO3)6]·(NO3)·(H3O)2}-co-NBE) (Ln = La, 1; Ln = Eu, 2; Ln = Tb, 3; Ln = Nd, 4; Ln = Yb, 5; Ln = Er, 6 or Ln = Gd, 7) obtained from ring-opening metathesis polymerization (ROMP) of norbornene (NBE) with each of allyl-functionalized complex monomers {[Ln3(L)4(NO3)6]·(NO3)·(H3O)2} (HL = 4-allyl-2-(1H-benzo[d]imidazol-2-yl)-6-methoxyphenol), PNBE-assisted effective energy transfer renders Poly(3-co-NBE) Tb3+-centered highly luminous color-purity green-light with an attractive quantum yield of 87% and efficient near-infrared (NIR) luminescence (ΦNdL = 0.61%; ΦYbL = 1.47% and ΦErL = 0.03%) for Nd3+-, Yb3+- or Er3+-grafted polymers.

  8. High pressure synthesis of a new phase of YbAg 2: Structure, valence of Yb and properties

    DOE PAGES

    Tsvyashchenko, A. V.; Menushenkov, A. P.; Sidorov, V. A.; ...

    2015-08-05

    The new phase of YbAg 2 was obtained using high-pressure and high-temperature reaction. YbAg 2 crystallizes in the MgZn 2 structure (the space group P6 3/mmc space group, No 194) with a = 5.68153(3) Å and c = 9.31995(7) Å and the unit cell volume V = 260.54(3) Å 3. The XANES analysis showed that the valence state of Yb is +2.8. The low-temperature dependences of the electrical resistivity and magnetic susceptibility can be adequately described by a T 2 term that supports the Fermi-liquid picture. Furthermore, the Kadowaki–Woods relation gives a low value of the degeneracy (N = 2).

  9. Blue–green afterglow of BaAl{sub 2}O{sub 4}:Dy{sup 3+} phosphors

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Zhai, Bao-gai; Ma, Qing-lan; School of Electronics and Information, Nantong University, Jiangsu 226019

    Highlights: • Afterglow can be achieved when Eu{sup 2+} is absent in the DyAl{sub 2}O{sub 4}:Dy{sup 3+} phosphors. • The afterglow of DyAl{sub 2}O{sub 4}:Dy{sup 3+} phosphors is discernible to naked eyes for minutes. • Dy{sup 3+} introduced trap centers are believed to be responsible for the afterglow. - Abstract: Dy{sup 3+} doped barium aluminate (BaAl{sub 2}O{sub 4}:Dy{sup 3+}) phosphors were prepared via the sol–gel combustion route at the ignition temperature of 600 °C. The phosphors were characterized with X-ray diffractometry, scanning electron microscopy, transmission electron microscopy, photoluminescence spectroscopy, Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. Regardless of themore » absence of Eu{sup 2+} luminescent centers, broadband blue–green afterglow with its peak at about 490 nm was recorded in the BaAl{sub 2}O{sub 4}:Dy{sup 3+} phosphors. The decay profile of the blue–green afterglow can be best fitted into a two-component exponential function with the two lifetime decay constants to be 8.81 and 45.25 s, respectively. The observation of blue–green afterglow from BaAl{sub 2}O{sub 4}:Dy{sup 3+} in the absence of Eu{sup 2+} provides unique opportunity in unveiling the afterglow mechanisms of rare-earth doped alkaline-metal aluminates. Possible mechanisms on the blue–green afterglow in BaAl{sub 2}O{sub 4}:Dy{sup 3+} phosphors are discussed in terms of the Dy{sup 3+} ions introduced trap centers as well as luminescent centers in the crystal lattice.« less

  10. Near infrared emission of TbAG:Ce{sup 3+},Yb{sup 3+} phosphor for solar cell applications

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Meshram, N. D., E-mail: meshramnileshsd@gmail.com; Yadav, P. J., E-mail: yadav.pooja75@yahoo.in; Pathak, A. A., E-mail: aapathak@yahoo.com

    2016-05-06

    Luminescent materials doped with rare earth ions are used for many devices such as optical amplifiers in telecommunication, phosphors for white light emitting diodes (LEDs), displays, and so on. Recently, they also have attracted a great interest for photovoltaic applications to improve solar cell efficiency by modifying solar spectrum. Crystal silicon (c-Si) solar cells most effectively convert photons of energy close to the semiconductor band gap. The mis-match between the incident solar spectrum and the spectral response of solar cells is one of the main reasons to limit the cell efficiency. The efficiency limit of the c-Si has been estimatedmore » to be 29% by Shockley and Queisser. However, this limit is estimated to be improved up to 38.4% by modifying the solar spectrum by a quantum cutting (down converting) phosphor which converts one photon of high energy into two photons of lower energy. The phenomenon such as the quantum cutting or the down conversion of rare earth ions have been investigated since Dexter reported the possibility of a luminescent quantum yield greater than unity in 1957. In the past, the quantum cutting from a vacuum ultraviolet photon to visible photons for Pr{sup 3+}, Gd{sup 3+},Gd{sup 3+}–Eu{sup 3+}, and Er{sup 3+}–Tb{sup 3+} had been studied. Recently, a new quantum cutting phenomenon from visible photon shorter than 500 nm to two infrared photons for Tb{sup 3+}–Yb{sup 3+}, Pr{sup 3+}–Yb{sup 3+}, and Tm{sup 3+}–Yb{sup 3+} has been reported. The Yb{sup 3+} ion is suitable as an acceptor and emitter because luminescent quantum efficiency of Yb{sup 3+} is close to 100% and the energy of the only excited level of Yb{sup 3+} (1.2 eV) is roughly in accordance with the band gap of Si (1.1 eV). In addition, the Ce{sup 3+}-doped Tb{sub 3}Al{sub 5}O{sub 12} (TbAG), used as a phosphor for white LED, has broad absorption bands in the range of 300–500 nm due to strong ligand field and high luminescent quantum efficiency

  11. The use of 133 Ba+ as a new candidate for trapped atomic ion qubits

    NASA Astrophysics Data System (ADS)

    Hucul, David; Christiansen, Justin; Campbell, Wesley; Hudson, Eric

    2016-05-01

    Trapped atomic ions are qubit standards in quantum information science because of their long coherence times and high fidelity entangling gates. Many different atomic ions have been used as qubits, each with strengths and weaknesses dictated by its atomic structure. We propose to use 133 Ba+ as an atomic qubit. 133 Ba+ is a nearly ideal, all-purpose candidate by combining many of the strengths of different workhorse atomic ions. 133 Ba+, like 171 Yb+, has a nuclear spin 1/2, allowing for a robust hyperfine qubit with simple state preparation and readout via differential fluorescence. The lack of a low-lying F-state, like in Ca+, simplifies high-fidelity qubit state detection that relies on shelving a qubit level to a meta-stable excited state. In addition, 133 Ba+ can be used for background-free qubit state detection where the wavelength of the qubit detection light differs from all excitation light by at least 50 THz. Unlike all other ions in use, the optical transitions of barium are in the visible spectrum, enabling the use of high power lasers, low-loss fibers, high quantum efficiency detectors, and other technologies developed for visible wavelengths of light to ease some requirements toward scaling a quantum system.

  12. Synthesis and luminescence properties of blue-emitting phosphor Ca12 Al14 O32 F2 :Eu2+ for white light-emitting diode.

    PubMed

    Chen, Wanping; Zhang, Xinzhu; Wang, Liping

    2017-09-01

    A blue-emitting phosphor Ca 12 Al 14 O 32 F 2 :Eu 2+ was synthesized using a high-temperature solid-state reaction under a reductive atmosphere. The X-ray diffraction measurements indicate that a pure phase Ca 12 Al 14 O 32 F 2 :Eu 2+ can be obtained for low doping concentration of Eu 2+ . The phosphor has a strong absorption in the range 270-420 nm with a maximum at ~340 nm and blue emission in the range 400-500 nm with chromatic coordination of (0.152, 0.045). The optimal doping concentration is ~0.24. In addition, the luminescence properties of the as-synthesized phosphor were evaluated by comparison with those of Ca 12 Al 14 O 32 Cl 2 :Eu 2+ and the commercially available phosphor BaMgAl 10 O 17 :Eu 2+ . The emission intensity of Ca 12 Al 14 O 32 F 2 :Eu 2+ was ~72% that of BaMgAl 10 O 17 :Eu 2+ under excitation at λ = 375 nm. The results indicate that Ca 12 Al 14 O 32 F 2 :Eu 2+ has potential application as a near-UV-convertible blue phosphor for white light-emitting diodes. Copyright © 2017 John Wiley & Sons, Ltd.

  13. Relaxor-ferroelectric BaLnZT (Ln = La, Nd, Sm, Eu, and Sc) ceramics for actuator and energy storage application

    NASA Astrophysics Data System (ADS)

    Ghosh, Sarit K.; Mallick, Kaushik; Tiwari, B.; Sinha, E.; Rout, S. K.

    2018-01-01

    Lead free ceramics Ba1-x Ln2x/3Zr0.3Ti0.7O3 (Ln = La, Nd, Sm, Eu and Sc), x = 0.02-0.10 are investigated for electrostrictive effect and energy storage properties in the proximity of relaxor-paraelectric phase boundary. Relaxor phase evidence from slim hysteresis loop and low remnant polarization are the key parameters responsible for improve the electrostrictive effect and energy storage properties simultaneously. With increase in rare earth content negative strain disappeared and almost hysteresis free strain is achieved. Strain-hysteresis profile in term of S-E, S-E 2 and S-P 2 is used to analyze the electrostrictive behavior of these ceramics. An average strain (S%) ˜ 0.03%, is accomplished at initial concentrations of x = 0.02-0.04 and electrostrictive coefficients (Q 11, and M 11) as well as the energy storage density is improved by a factor of 1.2 and 2.6 respectively when compare with pure (x = 0.0) ceramic. Above x ≥ 0.06, all compositions show a stable behavior which suggested the possibilities of these relaxor ceramics towards high precision actuators and energy storage application.

  14. Post-adsorption process of Yb phosphate nano-particle formation by Saccharomyces cerevisiae

    NASA Astrophysics Data System (ADS)

    Jiang, MingYu; Ohnuki, Toshihiko; Tanaka, Kazuya; Kozai, Naofumi; Kamiishi, Eigo; Utsunomiya, Satoshi

    2012-09-01

    In this study, we have investigated the post-adsorption process of ytterbium (Yb) phosphate nano-particle formation by Saccharomyces cerevisiae (yeast). The yeast grown in P-rich medium were exposed to 1.44 × 10-4 mol/L Yb(III) solution for 2-120 h, and 2 months at 25 ± 1 °C at an initial pH of 3, 4, or 5, respectively. Ytterbium concentrations in solutions decreased as a function of exposure time. Field-emission scanning electron microscopy equipped with energy-dispersive X-ray spectroscopy (FESEM), transmission electron microscopy (TEM), and synchrotron-based extended X-ray absorption fine structure (EXAFS) analyses revealed that nano-sized blocky Yb phosphate with an amorphous phase formed on the yeast cells surfaces in the solutions with Yb. These nano-sized precipitates that formed on the cell surfaces remained stable even after 2 months of exposure at 25 ± 1 °C around neutral pHs. The EXAFS data revealed that the chemical state of the accumulated Yb on the cell surfaces changed from the adsorption on both phosphate and carboxyl sites at 30 min to Yb phosphate precipitates at 5 days, indicating the Yb-phosphate precipitation as a major post-adsorption process. In addition, the precipitation of Yb phosphate occurred on cell surfaces during 7 days of exposure in Yb-free solution after 2 h of exposure (short-term Yb adsorption) in Yb solution. These results suggest that the released P from the inside of yeast cells reacted with adsorbed Yb on cell surfaces, resulting in the formation of Yb precipitates, even though no P was added to the exposure solution. In an abiotic system, the EXAFS data showed that the speciation of sorbed Yb on the reference materials, carboxymethyl cellulose and Ln resin, did not change even when the Yb was exposed to P solution, without forming Yb phosphate precipitates. This result strongly suggests that the cell surface of the yeast plays an important role in the Yb-phosphate precipitation process, not only as a carrier of the

  15. Dramatic change of photoexcited quasiparticle relaxation dynamics across Yb valence state transition in YbInCu4

    NASA Astrophysics Data System (ADS)

    Zhang, M. Y.; Chen, R. Y.; Dong, T.; Wang, N. L.

    2017-04-01

    YbInCu4 undergoes a first-order structural phase transition near Tv=40 K associated with an abrupt change of Yb valence state. We perform an ultrafast pump-probe measurement on YbInCu4 and find that the expected heavy-fermion properties arising from the c -f hybridization exist only in a limited temperature range above Tv. Below Tv, the compound behaves as a normal metal though a prominent hybridization energy gap is still present in the infrared measurement. We elaborate that those seemingly controversial phenomena could be well explained by assuming that the Fermi level suddenly shifts up and moves away from the flat f -electron band as well as the indirect hybridization energy gap in the intermediate valence state below Tv.

  16. Synthesis and crystal structure of a new aluminum-silicon-nitride phosphor containing boron, Ba5B2Al4Si32N52:Eu

    NASA Astrophysics Data System (ADS)

    Yoshimura, Fumitaka; Yamane, Hisanori; Nagasako, Makoto

    2017-07-01

    Single crystals of Ba5B2Al4Si32N52:Eu were grown on the wall of a boron nitride crucible by heating a starting mixture of binary nitrides at 2050 °C and a N2 pressure of 0.85 MPa. The fundamental reflections of X-ray diffraction (XRD) for the crystals were indexed with triclinic cell parameters, a=9.7879(11) Å, b=9.7920(11) Å, c=12.7226(15) Å, α=96.074(4)°, β=112.330(3)°, and γ=94.080(4)°. Streak lines were observed between the fundamental reflections in the direction of the c* axis in the oscillation XRD images and selected area electron diffraction (SAED) patterns, indicating stacking faults in the structure. The atomic images of stacking faults with a slip system of (0 0 1)[-1 1 0]/3, and displacement of a Ba atom layer with (0 0 1)[-1 -1 0]/6 were observed with a scanning transmission electron microscope (STEM). The models of the basic (normal-stacking) structure with space group P1 and local structures of the stacking faults are herein presented. The single crystals emitted blue light with a peak wavelength of 472 nm and a full width at half maximum of 78 nm under 365 nm excitation.

  17. Crystallization and photoluminescence properties of α-RE2(WO4)3 (RE: Gd, Eu) in rare-earth tungsten borate glasses

    NASA Astrophysics Data System (ADS)

    Wang, Yong; Honma, Tsuyoshi; Komatsu, Takayuki

    2013-03-01

    Glasses with the compositions of 22.5RE2O3-47.5WO3-30B2O3 (mol%) (RE: Gd, Eu) were prepared by a conventional melt quenching method, and α-Gd2(WO4)3 and α-Eu2(WO4)3 crystals were synthesized through their crystallization. The two types of WO4 tetrahedra present in α-RE2(WO4)3 provide the Raman bands at 931-934 cm-1 for WIIO4 tetrahrdra with much distortions and at 946-950 cm-1 for WIO4 tetrahedra with a near regular symmetry. The crystallized samples containing α-Eu2(WO4)3 exhibit strong red emissions under the excitation at 396 and 467 nm, although the base glass has no photoluminescence emission. α-Gd2(WO4)3 and α-Eu2(WO4)3 crystals were patterned on the glass surface by irradiations of a continuous wave Yb:YVO4 fiber laser (wavelength: 1080 nm).

  18. Cold shock protein YB-1 is involved in hypoxia-dependent gene transcription

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Rauen, Thomas; Frye, Bjoern C.; Pneumology, University Medical Center, University of Freiburg, Freiburg

    Hypoxia-dependent gene regulation is largely orchestrated by hypoxia-inducible factors (HIFs), which associate with defined nucleotide sequences of hypoxia-responsive elements (HREs). Comparison of the regulatory HRE within the 3′ enhancer of the human erythropoietin (EPO) gene with known binding motifs for cold shock protein Y-box (YB) protein-1 yielded strong similarities within the Y-box element and 3′ adjacent sequences. DNA binding assays confirmed YB-1 binding to both, single- and double-stranded HRE templates. Under hypoxia, we observed nuclear shuttling of YB-1 and co-immunoprecipitation assays demonstrated that YB-1 and HIF-1α physically interact with each other. Cellular YB-1 depletion using siRNA significantly induced hypoxia-dependent EPOmore » production at both, promoter and mRNA level. Vice versa, overexpressed YB-1 significantly reduced EPO-HRE-dependent gene transcription, whereas this effect was minor under normoxia. HIF-1α overexpression induced hypoxia-dependent gene transcription through the same element and accordingly, co-expression with YB-1 reduced HIF-1α-mediated EPO induction under hypoxic conditions. Taken together, we identified YB-1 as a novel binding factor for HREs that participates in fine-tuning of the hypoxia transcriptome. - Highlights: • Hypoxia drives nuclear translocation of cold shock protein YB-1. • YB-1 physically interacts with hypoxia-inducible factor (HIF)-1α. • YB-1 binds to the hypoxia-responsive element (HRE) within the erythropoietin (EPO) 3′ enhancer. • YB-1 trans-regulates transcription of hypoxia-dependent genes such as EPO and VEGF.« less

  19. Characterization of Yb{sup 3+}:Sr{sub 5{minus}x}Ba{sub x}(PO{sub 4}){sub 3}F crystals for diode pumped lasers

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Bayramian, A.J.; Marshall, C.D.; Schaffers, K.I.

    Ytterbium-doped Sr{sub 5}(PO{sub 4}){sub 3}F (S-FAP) has been shown to be a useful material for diode pumping, since it displays high gain, low loss, and a long radiative lifetime. One of the issues with S-FAP is that it has a relatively narrow absorption bandwidth ({approximately}5 nm) at 900 nm, the diode-pumping wavelength, while the diode`s output bandwidth can be large ({approximately}10 nm). By changing the host slightly, the absorption feature can be broadened to better match the pump bandwidth. Four mixed crystal boules of Yb{sup 3+}:Sr{sub 5{minus}x}Ba{sub x}(PO{sub 4}){sub 3}F were grown by the Czochralski method with x = 0.25,more » 0.5, 1, and 2. The bandwidth of the 900-nm absorption feature was found to grow with increasing barium concentration from 4.7 nm to a maximum of 15.9 nm. Emission spectra showed a similar bandwidth increase with barium content from 4.9 nm to a maximum of 10 nm. Emission cross sections for these materials were deduced by the methods of reciprocity, the Einstein method, and small-signal gain. The absorption feature`s homogeneity was probed using a tunable pump source which qualitatively showed that the barium-broadened lines were at least partly inhomogeneous. Each of these materials lased with a variety of output couplers. This family of materials was found to provide suitable laser hosts where a broader absorption and/or emission bandwidth is desired.« less

  20. Ultraviolet and near-infrared luminescence of LaBO3:Ce3+,Yb3+

    NASA Astrophysics Data System (ADS)

    Wei, Heng-Wei; Shao, Li-Ming; Jiao, Huan; Jing, Xi-Ping

    2018-01-01

    Ce3+ or Yb3+ singly doped LaBO3 and Ce3+-Yb3+ co-doped LaBO3 were prepared by conventional solid state reactions at 1100 °C and their photoluminescence (PL) properties were investigated. The emission spectrum of LaBO3:Ce3+,Yb3+ contains both the Ce3+ ultraviolet (UV) emissions (355 nm and 380 nm) and the Yb3+ near infrared (NIR) emission (975 nm) when excited by the UV light at 270 nm. By using the data of the Ce3+ decay curves and the PL intensities of both Ce3+ and Yb3+, the energy transfer efficiency (η) from Ce3+ to Yb3+, the actual energy transfer efficiency (AE) and the quantum efficiency (Q) of the Yb3+ emission were calculated. In the Ce3+-Yb3+ co-doped LaBO3, Ce3+ can transfer its absorbed energy to Yb3+ efficiently (η can be over 60%), and Yb3+ shows the Q value over 50% when it accepts the energy from Ce3+, which results in the low AE value ∼30%. The energy transfer process from Ce3+ to Yb3+ may be understood by the charge transfer mechanism: Ce3+ + Yb3+ ↔ Ce4+ + Yb2+. Particularly the Ce3+-Yb3+ co-doped LaBO3 phosphor gives the emissions mainly in the UV range and the NIR range with a portion of visible emissions in eye-insensitive range. This unique property may be suitable for applications in anti-counterfeiting techniques and public security affairs.

  1. Barium Qubit State Detection and Ba Ion-Photon Entanglement

    NASA Astrophysics Data System (ADS)

    Sosnova, Ksenia; Inlek, Ismail Volkan; Crocker, Clayton; Lichtman, Martin; Monroe, Christopher

    2016-05-01

    A modular ion-trap network is a promising framework for scalable quantum-computational devices. In this architecture, different ion-trap modules are connected via photonic buses while within one module ions interact locally via phonons. To eliminate cross-talk between photonic-link qubits and memory qubits, we use different atomic species for quantum information storage (171 Yb+) and intermodular communication (138 Ba+). Conventional deterministic Zeeman-qubit state detection schemes require additional stabilized narrow-linewidth lasers. Instead, we perform fast probabilistic state detection utilizing efficient detectors and high-NA lenses to detect emitted photons from circularly polarized 493 nm laser excitation. Our method is not susceptible to intensity and frequency noise, and we show single-shot detection efficiency of ~ 2%, meaning that we can discriminate between the two qubits states with 99% confidence after as little as 50 ms of averaging. Using this measurement technique, we report entanglement between a single 138 Ba+ ion and its emitted photon with 86% fidelity. This work is supported by the ARO with funding from the IARPA MQCO program, the DARPA Quiness program, the AFOSR MURI on Quantum Transduction, and the ARL Center for Distributed Quantum Information.

  2. Evaluation of YB-1 levels in patients with endometriosis.

    PubMed

    Ahrens, Thorben; Silveira, Cassia G T; Banz-Jansen, Constanze; Rody, Achim; Hornung, Daniela

    2015-08-01

    The objective of this study is the evaluation of serum YB-1 levels in the diagnosis of endometriosis. Serum samples of 12 patients with histologically confirmed endometriosis and of 10 control patients were collected. Western blot analysis was used to assess serum YB-1 levels. Groups were compared with Student's t-test or, if not normally distributed, with the Mann-Whitney test. Sensitivity and specificity for the potential diagnostic performance of serum YB-1 were assessed by receiver operating characteristic (ROC) curves. Serum YB-1 levels were significantly higher in patients with endometriosis (=0.004). The area under the curve was 0.867 (95% confidence interval 0.714-1.019) with sensitivity and specificity of 83.3% and 70% respectively. Serum YB-1 levels in patients with endometriosis are significantly higher compared to control patients and may be used as a potential diagnostic biomarker for endometriosis. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  3. Yb3+/Ho3+-codoped antimony-silicate optical fiber

    NASA Astrophysics Data System (ADS)

    Żmojda, Jacek; Dorosz, Dominik; Kochanowicz, Marcin; Miluski, Piotr; Dorosz, Jan

    2012-05-01

    The emission properties of Yb3+/Ho3+-codoped antimony-silicate optical fiber has been investigated. Luminescence at 2.1 μm corresponding to 5I7--> 5I8 transition in holmium was obtained by energy transfer between Yb3+ and Ho3+ ions. According to the Dexter-Miyakawa model, the parameters of energy migration CDD of the 2F5/2 (Yb3+) <--> 2F5/2 (Yb3+) transition and direct energy transfer CDA of the 2F5/2 (Yb3+) --> 5I6 (Ho3+) transition was calculated. The optimization of the activator content and the concentration ratio were conducted with the purpose of maximizing the efficiency of energy transfer. It made possible to select best-suited glass which was used to manufacture double-clad optical fiber. Strong and narrow bands of spontaneous emission which formed as a result of energy transfer between ytterbium and holmium ions were observed in the fiber under exciting with radiation at 978 nm wavelength.

  4. A novel fluorescent probe (dtpa-bis(cytosine)) for detection of Eu(III) in rare earth metal ions.

    PubMed

    Yang, Fan; Ren, Peipei; Liu, Guanhong; Song, Youtao; Bu, Naishun; Wang, Jun

    2018-03-15

    In this paper, a novel fluorescent probe, dtpa-bis(cytosine), was designed and synthesized for detecting europium (Eu 3+ ) ion. Upon addition of Eu 3+ ions into the dtpa-bis(cytosine) solution, the fluorescence intensity can strongly be enhanced. Conversely, adding other rare earth metal ions, such as Y 3+ , Ce 3+ , Pr 3+ , Nd 3+ , Sm 3+ , Gd 3+ , Tb 3+ , Dy 3+ , Ho 3+ , Er 3+ , Yb 3+ and Lu 3+ , into dtpa-bis(cytosine) solution, the fluorescence intensity is decreased slightly. Some parameters affecting the fluorescence intensity of dtpa-bis(cytosine) solution in the presence of Eu 3+ ions were investigated, including solution pH value, Eu 3+ ion concentration and interfering substances. The detection mechanism of Eu 3+ ion using dtpa-bis(cytosine) as fluorescent probe was proposed. Under optimum conditions, the fluorescence emission intensities of Eu III -dtpa-bis(cytosine) at 375nm in the concentration range of 0.50×10 -5 mol∙L -1 -5.00×10 -5 mol∙L -1 of Eu 3+ ion display a better linear relationship. The limit of detection (LOD) was determined as 8.65×10 -7 mol∙L -1 and the corresponding correlation coefficient (R 2 ) of the linear equation is 0.9807. It is wished that the proposed method could be applied for sensitively and selectively detecting Eu 3+ ion. Copyright © 2017 Elsevier B.V. All rights reserved.

  5. Assessment of effect of Yb3+ ion pairs on a highly Yb-doped double-clad fibre laser

    NASA Astrophysics Data System (ADS)

    Vallés, J. A.; Martín, J. C.; Berdejo, V.; Cases, R.; Álvarez, J. M.; Rebolledo, M. Á.

    2018-03-01

    Using a previously validated characterization method based on the careful measurement of the characteristic parameters and fluorescence emission spectra of a highly Yb-doped double-clad fibre, we evaluate the contribution of ion pair induced processes to the output power of a double-clad Yb-doped fibre ring laser. This contribution is proved to be insignificant, contrary to analysis by other authors, who overestimate the role of ion pairs.

  6. Buffer layers and articles for electronic devices

    DOEpatents

    Paranthaman, Mariappan P.; Aytug, Tolga; Christen, David K.; Feenstra, Roeland; Goyal, Amit

    2004-07-20

    Materials for depositing buffer layers on biaxially textured and untextured metallic and metal oxide substrates for use in the manufacture of superconducting and other electronic articles comprise RMnO.sub.3, R.sub.1-x A.sub.x MnO.sub.3, and combinations thereof; wherein R includes an element selected from the group consisting of La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and Y, and A includes an element selected from the group consisting of Be, Mg, Ca, Sr, Ba, and Ra.

  7. Mineralogical and geochemical features of the coarse saprolite developed on orthogneiss in the SW of Yaoundé, South Cameroon

    NASA Astrophysics Data System (ADS)

    Ndjigui, P.-D.; Badinane, M. F. B.; Nyeck, B.; Nandjip, H. P. K.; Bilong, P.

    2013-03-01

    A petrological investigation was performed in the coarse saprolite on orthogneiss in Yaoundé (South Cameroon) using combined whole rock geochemical (XRF, ICP-MS) and mineralogical (XRD, SEM) techniques. The orthogneiss has high contents in SiO2 (61.56 wt.%), Ba (916 ppm) and REE (209 ppm), moderate content in Al2O3 (14.34 wt.%) and negative Eu anomaly (Eu/Eu* = 0.68). The weathering leads to the formation of three main constituents in the coarse saprolite: (i) the loose materials (∼85 vol.%) are basically clayey silty with relic structure. They are composed of kaolinite, quartz and goethite. The loose materials have high contents in SiO2 (56-64.83 wt.%) and Al2O3 (21.48-23.96 wt.%), and moderate contents in V (163-236 ppm), Ba (95-340 ppm) and Zr (160-313 ppm). The REE content is low (∼49-169 ppm) relative to the parent rock with LREE-enrichment (LREE/HREE ∼ 7-17). Positive Ce anomaly (Ce/Ce* ∼ 3.35) is observed in the white veins and slight positive Eu anomalies (Eu/Eu* ∼ 1.2-1.4) are noted in all loose samples. The (La/Yb)N ratios (∼0.8-1.5) indicate high REE-fractionation. The mass balance calculation reveals the depletion of several elements except Al, Ti, Sc, Y, Th, Sb and Hf; (ii) the iron duricrust (∼10 vol.%) is located at the bottom and the top of the horizon. The mineral assemblage is dominated by hematite and goethite. The upper iron duricrust has high contents in Fe2O3 (45.60 wt.%) and Cr (1641 ppm), moderate contents in V (459 ppm) and Zn (143 ppm), and low REE content (47 ppm) with low LREE/HREE ratio (4.28). The upper iron duricrust is more enriched in Fe2O3 (53.26 wt.%) than the lower one. Vanadium, Cr and Zr have high contents relative to other trace elements. The REE content is low (39 ppm) as well as the LREE/HREE ratio (2.94). The iron duricrust has negative Ce anomalies (Ce/Ce* ∼ 0.66-0.69) and very low (La/Yb)N ratios (0.1-0.3). Several elements reported in the iron duricrust are highly leached except Fe, Cr, Zn, Sc, V, Pb, Zr

  8. Valence fluctuating compound α-YbAlB4 studied by 174Yb Mössbauer spectroscopy and X-ray diffraction using synchrotron radiation

    NASA Astrophysics Data System (ADS)

    Oura, Momoko; Ikeda, Shugo; Masuda, Ryo; Kobayashi, Yasuhiro; Seto, Makoto; Yoda, Yoshitaka; Hirao, Naohisa; Kawaguchi, Saori I.; Ohishi, Yasuo; Suzuki, Shintaro; Kuga, Kentaro; Nakatsuji, Satoru; Kobayashi, Hisao

    2018-05-01

    The structural properties and the Yb 4 f electronic state of the valence fluctuating α-YbAlB4 have been investigated by powder X-ray diffraction under pressure and 174Yb Mössbauer spectroscopy with magnetic fields at low temperature, respectively, using synchrotron radiation. Powder X-ray diffraction patterns showed that the crystal structure does not change up to p ∼ 18 GPa at 8 K and the volume decreases smoothly. However, the pressure dependence of the difference in the structure factor between the (060) and (061) diffraction lines changes at ∼ 3.4 GPa, indicating the change of atomic coordination parameters. The 174Yb Mössbauer spectroscopy measurements at 2 K with 10 and 50 kOe suggest that the electrical quadrupole interaction changes by applied magnetic fields.

  9. 12 mJ Yb:YAG/Cr:YAG microchip laser

    NASA Astrophysics Data System (ADS)

    Guo, Xiaoyang; Tokita, Shigeki; Kawanaka, Junji

    2018-02-01

    By cryogenically cooling the Yb:YAG/Cr:YAG medium, one can break through the damage limit of Yb:YAG/Cr:YAG passively Q-switched microchip lasers at room temperature and thus achieve a shorter minimum pulse duration. In the proof of principle experiment we carried out, a 160.6 ps pulse duration was obtained. To the best of our knowledge, this is the first realization of sub-200 ps pulse operation for an Yb:YAG/Cr:YAG microchip laser

  10. High-brightness and high-color purity red-emitting Ca3Lu(AlO)3(BO3)4:Eu3+ phosphors with internal quantum efficiency close to unity for near-ultraviolet-based white-light-emitting diodes.

    PubMed

    Huang, Xiaoyong; Wang, Shaoying; Li, Bin; Sun, Qi; Guo, Heng

    2018-03-15

    In this work, we reported on high-brightness Eu 3+ -activated Ca 3 Lu(AlO) 3 (BO 3 ) 4 (CLAB) red-emitting phosphors. Under 397 nm excitation, the CLAB:Eu 3+ phosphors showed intense red emissions at around 621 nm with CIE coordinates of (0.657, 0.343). The optimal doping concentration of Eu 3+ ions was found to be 30 mol. %, and the CLAB:0.3Eu 3+ sample possessed high-color purity of 93% and ultra-high internal quantum efficiency as great as 98.5%. Importantly, the CLAB:0.3Eu 3+ also had good thermal stability. Finally, a white-light-emitting diode (WLED) lamp with good color-rendering index was fabricated by using a 365 nm ultraviolet chip and the phosphor blends of CLAB:0.3Eu 3+ red-emitting phosphors, (Ba,Sr) 2 SiO 4 :Eu 2+ green-emitting phosphors, and BaMgAl 10 O 7 :Eu 2+ blue-emitting phosphors.

  11. Thermodynamic and transport properties of YbNi 4Cd

    NASA Astrophysics Data System (ADS)

    Lee, J.; Park, H.; Lee-Hone, N. R.; Broun, D. M.; Mun, E.

    2018-05-01

    The single crystal growth and the physical properties of the intermetallic compounds R Ni4Cd (R =Y and Yb) which crystallize in the face-centered cubic (fcc) MgCu4Sn -type structure (space group F 4 ¯3 m ) are discussed. Thermodynamic and transport properties of YbNi4Cd are studied by measuring the magnetization, electrical resistivity, and specific heat. The magnetic susceptibility measurement shows that the 4 f electrons of Yb3 + ions are well localized. The electrical resistivity and specific heat exhibits an antiferromagnetic ordering below TN=0.97 K. Applying the field along the [111] direction results in the suppression of TN below 0.4 K at the critical field Hc˜4.5 kOe. No non-Fermi liquid behavior has been observed in the vicinity of Hc. Above Hc, the magnetoresistivity shows an unconventional temperature dependence ρ (T ) =ρ0+A Tn with n >2 , suggesting that an additional scattering mechanism in the resistivity needs to be considered. Based on the analysis of experimental results, we conclude that the Yb3 + moments and conduction electrons are weakly coupled. Despite the antiferromagnetic ordering below TN, YbNi4Cd exhibits a large frustration parameter | θp/TN|˜16 , where the magnetic Yb3 + ions occupy the tetrahedra on the fcc lattice.

  12. YB-1 overexpression promotes a TGF-β1-induced epithelial–mesenchymal transition via Akt activation

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Ha, Bin; Lee, Eun Byul; Cui, Jun

    2015-03-06

    The Y-box binding protein-1 (YB-1) is a transcription/translation regulatory protein, and the expression thereof is associated with cancer aggressiveness. In the present study, we explored the regulatory effects of YB-1 during the transforming growth factor-β1 (TGF-β1)-induced epithelial-to-mesenchymal transition (EMT) in lung adenocarcinoma cells. Downregulation of YB-1 increased E-cadherin promoter activity, and upregulation of YB-1 decreased promoter activity, suggesting that the YB-1 level may be correlated with the EMT. TGF-β1 induced YB-1 expression, and TGF-β1 translocated cytosolic YB-1 into the nucleus. YB-1 overexpression promoted TGF-β1-induced downregulation of epithelial markers, upregulation of mesenchymal markers, and cell migration. Moreover, YB-1 overexpression enhanced themore » expression of E-cadherin transcriptional repressors via TGF-β1-induced Akt activation. Our findings afford new insights into the role played by YB-1 in the TGF-β1 signaling pathway. - Highlights: • YB-1 regulates E-cadherin expression in A549 cells. • TGF-β1 induces upregulating and nuclear localization of YB-1. • YB-1 overexpression accelerates TGF-β1-induced EMT and cell migration. • YB-1 regulates Snail and Slug expression via Akt activation.« less

  13. Sol-Gel Derived Active Material for Yb Thin-Disk Lasers

    PubMed Central

    Almeida, Rui M.; Ribeiro, Tiago

    2017-01-01

    A ytterbium doped active material for thin-disk laser was developed based on aluminosilicate and phosphosilicate glass matrices containing up to 30 mol% YbO1.5. Thick films and bulk samples were prepared by sol-gel processing. The structural nature of the base material was assessed by X-ray diffraction and Raman spectroscopy and the film morphology was evidenced by scanning electron microscopy. The photoluminescence (PL) properties of different compositions, including emission spectra and lifetimes, were also studied. Er3+ was used as an internal reference to compare the intensities of the Yb3+ PL peaks at ~ 1020 nm. The Yb3+ PL lifetimes were found to vary between 1.0 and 0.5 ms when the Yb concentration increased from 3 to 30 mol%. Based on a figure of merit, the best active material selected was the aluminosilicate glass composition 71 SiO2-14 AlO1.5-15 YbO1.5 (in mol%). An active disk, ~ 36 μm thick, consisting of a Bragg mirror, an aluminosilicate layer doped with 15 mol% Yb and an anti-reflective coating, was fabricated. PMID:28869488

  14. Coherent excitations and electron-phonon coupling in Ba/EuFe2As2 compounds investigated by femtosecond time- and angle-resolved photoemission spectroscopy

    NASA Astrophysics Data System (ADS)

    Avigo, I.; Cortés, R.; Rettig, L.; Thirupathaiah, S.; Jeevan, H. S.; Gegenwart, P.; Wolf, T.; Ligges, M.; Wolf, M.; Fink, J.; Bovensiepen, U.

    2013-03-01

    We employed femtosecond time- and angle-resolved photoelectron spectroscopy to analyze the response of the electronic structure of the 122 Fe-pnictide parent compounds Ba/EuFe2As2 and optimally doped BaFe1.85Co0.15As2 near the Γ point to optical excitation by an infrared femtosecond laser pulse. We identify pronounced changes of the electron population within several 100 meV above and below the Fermi level, which we explain as a combination of (i) coherent lattice vibrations, (ii) a hot electron and hole distribution, and (iii) transient modifications of the chemical potential. The responses of the three different materials are very similar. In the coherent response we identify three modes at 5.6, 3.3, and 2.6 THz. While the highest frequency mode is safely assigned to the A1g mode, the other two modes require a discussion in comparison to the literature. Employing a transient three temperature model we deduce from the transient evolution of the electron distribution a rather weak, momentum-averaged electron-phonon coupling quantified by values for λ<ω2> between 30 and 70 meV2. The chemical potential is found to present pronounced transient changes reaching a maximum of 15 meV about 0.6 ps after optical excitation and is modulated by the coherent phonons. This change in the chemical potential is particularly strong in a multiband system like the 122 Fe-pnictide compounds investigated here due to the pronounced variation of the electron density of states close to the equilibrium chemical potential.

  15. A single-phase Ba{sub 9}Lu{sub 2}Si{sub 6}O{sub 24}:Eu{sup 2+}, Ce{sup 3+}, Mn{sup 2+} phosphor with tunable full-color emission for NUV-based white LED applications

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Zhang, Changhua; Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201; Liu, Yongfu, E-mail: liuyongfu@nimte.ac.cn

    Highlights: • A single phase Ba{sub 9}Lu{sub 2}Si{sub 6}O{sub 24}:Eu{sup 2+}, Ce{sup 3+}, Mn{sup 2+} phosphor with full-color emission was obtained by solid-state reactions. • Eu{sup 2+}, Ce{sup 3+}, and Mn{sup 2+} acts as blue, green, and red luminescence centers, respectively. • The BLS:Eu{sup 2+}, Ce{sup 3+}, Mn{sup 2+} phosphor shows a high quantum efficient of ∼62% and a good color stability. • Combining this single phosphor with a 395 nm NUV-chip, an ideal white LED with a high CRI of 85 and a CCT of 6300 K was obtained. - Abstract: We obtained a single phase BLS:Eu{sup 2+}, Ce{supmore » 3+}, Mn{sup 2+} phosphor by solid-state reactions. Eu{sup 2+}, Ce{sup 3+}, and Mn{sup 2+} gives rise to the blue, green, and red emission, respectively. The Mn{sup 2+} red emission can be effectively enhanced via energy transfers from both Eu{sup 2+} and Ce{sup 3+}. Thus a tunable full color emission from 410 to 750 nm was realized in this single phosphor. The Eu{sup 2+} → Mn{sup 2+} energy transfer mechanism was investigated by the fluorescence decay curves. This single phosphor exhibits an efficient excitation band covering from 390 to 410 nm, which matches well with the emission light of the efficient NUV chips. The optimized BLS:Eu{sup 2+}, Ce{sup 3+}, Mn{sup 2+} phosphor shows a high quantum efficient of ∼62% and a good color stability. When this single phosphor was combined with a 395 nm NUV-chip, an ideal white LED with a high color render index (CRI) of 85 and a correlated color temperature (CCT) of 6300 K was obtained. This demonstrates the promising application of the BLS:Eu{sup 2+}, Ce{sup 3+}, Mn{sup 2+} single phosphor for the NUV-based white LEDs.« less

  16. Efficient Nd3+→Yb3+ energy transfer processes in high phonon energy phosphate glasses for 1.0 μm Yb3+ laser

    NASA Astrophysics Data System (ADS)

    Rivera-López, F.; Babu, P.; Basavapoornima, Ch.; Jayasankar, C. K.; Lavín, V.

    2011-06-01

    Efficient Nd3+→Yb3+ resonant and phonon-assisted energy transfer processes have been observed in phosphate glasses and have been studied using steady-state and time-resolved optical spectroscopies. Results indicate that the energy transfer occurs via nonradiative electric dipole-dipole processes and is enhanced with the concentration of Yb3+ acceptor ions, having an efficiency higher than 75% for the glass doped with 1 mol% of Nd2O3 and 4 mol% of Yb2O3. The luminescence decay curves show a nonexponential character and the energy transfer microscopic parameter calculated with the Inokuti-Hirayama model gives a value of 240 × 10-40 cm6 s-1, being one of the highest reported in the literature for Nd3+-Yb3+ co-doped matrices. From the steady-state experimental absorption and emission cross-sections, a general expression for estimating the microscopic energy transfer parameter is proposed based upon the theoretical methods developed by Miyakawa and Dexter and Tarelho et al. This expression takes into account all the resonant mechanisms involved in an energy transfer processes together with other phonon-assisted nonvanishing overlaps. The value of the Nd3+→Yb3+ energy transfer microscopic parameter has been calculated to be 200 × 10-40 cm6 s-1, which is in good agreement with that obtained from the Inokuti-Hirayama fitting. These results show the importance of the nonresonant phonon-assisted Nd3+→Yb3+ energy transfer processes and the great potential of these glasses as active matrices in the development of multiple-pump-channel Yb3+ lasers.

  17. In-Situ Growth of Yb2O3 Layer for Sublimation Suppression for Yb14MnSb11 Thermoelectric Material for Space Power Applications

    NASA Technical Reports Server (NTRS)

    Nesbitt, James A.; Opila, Elizabeth J.; Nathal, Michael V.

    2012-01-01

    The compound Yb14MnSb11 is a p-type thermoelectric material of interest to the National Aeronautics and Space Administration (NASA) as a candidate replacement for the state-of-the-art Si-Ge used in current radioisotope thermoelectric generators (RTGs). Ideally, the hot end of this leg would operate at 1000 C in the vacuum of space. Although Yb14MnSb11 shows the potential to double the value of the thermoelectric figure of merit (zT) over that of Si-Ge at 1000 C, it suffers from a high sublimation rate at elevated temperatures and would require a coating in order to survive the required RTG lifetime of 14 years. The purpose of the present work is to measure the sublimation rate of Yb14MnSb11 and to investigate sublimation suppression for this material. This paper reports on the sublimation rate of Yb14MnSb11 at 1000 C (approximately 3 x 10(exp -3) grams per square centimeter hour) and efforts to reduce the sublimation rate with an in situ grown Yb2O3 layer. Despite the success in forming thin, dense, continuous, and adherent oxide scales on Yb14MnSb11, the scales did not prove to be sublimation barriers.

  18. Visible upconversion emission and non-radiative direct Yb 3+ to Er 3+ energy transfer processes in nanocrystalline ZrO 2:Yb 3+,Er 3+

    NASA Astrophysics Data System (ADS)

    Diaz-Torres, L. A.; Meza, O.; Solis, D.; Salas, P.; De la Rosa, E.

    2011-06-01

    Wide band gap Yb 3+ and Er 3+ codoped ZrO 2 nanocrystals have been synthesized by a modified sol-gel method. Under 967 nm excitation strong green and red upconversion emission is observed for several Er 3+ to Yb 3+ ions concentration ratios. A simple microscopic rate equation model is used to study the effects of non-radiative direct Yb 3+ to Er 3+ energy transfer processes on the visible and near infrared fluorescence decay trends of both Er 3+ and Yb 3+ ions. The microscopic rate equation model takes into account the crystalline phase as well as the size of nanocrystals. Nanocrystals phase and size were estimated from XRD patterns. The rate equation model succeeds to fit simultaneously all visible and near infrared fluorescence decay profiles. The dipole-dipole interaction parameters that drive the non-radiative energy transfer processes depend on doping concentration due to crystallite phase changes. In addition the non-radiative relaxation rate ( 4I11/2→ 4I13/2) is found to be greater than that estimated by the Judd-Ofelt parameters due to the action of surface impurities. Results suggest that non-radiative direct Yb 3+ to Er 3+ energy transfer processes in ZrO 2:Yb,Er are extremely efficient.

  19. Temperature influence on diode pumped Yb:GGAG laser

    NASA Astrophysics Data System (ADS)

    Veselský, Karel; Boháček, Pavel; Šulc, Jan; Jelínková, Helena; Trunda, Bohumil; Havlák, Lubomír.; Jurek, Karel; Nikl, Martin

    2017-05-01

    We present temperature influence (in range from 78 up to 400,K) on spectroscopic properties and laser performance of new Yb-doped mixed garnet Gd3GaxAl5-xO12 (Yb:GGAG). The sample was 2.68 mm thick plane-parallel face-polished Yb:GGAG single-crystal plate which was AR coated for pump (930 nm) and generated (1030 nm) laser radiation wavelength. The composition of sample was Gd3.098Yb0:0897Ga2:41Al2.41O12 (3 at % Yb/Gd). The Yb:GGAG crystal was mounted in temperature controlled copper holder of the liquid nitrogen cryostat. The 138 mm long semi-hemispherical laser resonator consisted of a flat pumping mirror (T > 90 % @ 930 nm, HR @ 1030 nm) placed inside cryostat, and a curved output coupler (r = 150 mm, R = 94.5 % @ 1030 nm) placed outside cryostat. For longitudinal pumping a fiber coupled laser diode was used. The diode was operating in the pulse regime (5 ms pulse length, 20 Hz repetition rate) at wavelength 928.5 nm. The absorption spectrum was measured for the temperatures from 78 to 400 K, and absorption lines narrowing was observed with temperature decrease. Zero-phonon line at 970 nm has width 1 nm (FWHM) at 100 K. The fluorescence intensity decay time was measured and it increased linearly with temperature from 864 μs @ 78 K to 881 μs @ 300 K. The temperature of active medium has strong influence mainly on laser threshold which was 5 times lower at 100 K than at 300 K, and on slope efficiency which was 3 times higher at 100 K than at 300 K.

  20. Comparing Zeeman qubits to hyperfine qubits in the context of the surface code: +174Yb and +171Yb

    NASA Astrophysics Data System (ADS)

    Brown, Natalie C.; Brown, Kenneth R.

    2018-05-01

    Many systems used for quantum computing possess additional states beyond those defining the qubit. Leakage out of the qubit subspace must be considered when designing quantum error correction codes. Here we consider trapped ion qubits manipulated by Raman transitions. Zeeman qubits do not suffer from leakage errors but are sensitive to magnetic fields to first order. Hyperfine qubits can be encoded in clock states that are insensitive to magnetic fields to first order, but spontaneous scattering during the Raman transition can lead to leakage. Here we compare a Zeeman qubit (+174Yb) to a hyperfine qubit (+171Yb) in the context of the surface code. We find that the number of physical qubits required to reach a specific logical qubit error can be reduced by using +174Yb if the magnetic field can be stabilized with fluctuations smaller than 10 μ G .

  1. Synthesis and photoluminescence in Yb doped cerium phosphate CePO4

    NASA Astrophysics Data System (ADS)

    Bhonsule, S. U.; Wankhede, S. P.; Moharil, S. V.

    2018-05-01

    This paper presents the preparation of CePO4 and Yb doped CePO4 using simple solid state reaction method. PL measurements indicated significant energy transfer from Ce3+ to Yb3+ ions. Further evidence of energy transfer was provided by analysis of Luminescence Decay measurements. Energy transfer efficiency of 50% was obtained for 5%Yb doping. Energy transfer from Ce3+ to Yb3+ ions takes place by Cooperative energy transfer mechanism. Such phosphors can be used in white LED's, Lasers and energy saving fluorescent lamps.

  2. First-Order Antiferromagnetic Transition and Fermi Surfaces in Semimetal EuSn3

    NASA Astrophysics Data System (ADS)

    Mori, Akinobu; Miura, Yasunao; Tsutsumi, Hiroki; Mitamura, Katsuya; Hagiwara, Masayuki; Sugiyama, Kiyohiro; Hirose, Yusuke; Honda, Fuminori; Takeuchi, Tetsuya; Nakamura, Ai; Hiranaka, Yuichi; Hedo, Masato; Nakama, Takao; Ōnuki, Yoshichika

    2014-02-01

    We grew high-quality single crystals of the antiferromagnet EuSn3 with the AuCu3-type cubic crystal structure by the Sn self-flux method and measured the electrical resistivity, magnetic susceptibility, high-field magnetization, specific heat, thermal expansion, and de Haas-van Alphen (dHvA) effect, in order to study the magnetic and Fermi surface properties. We observed steplike changes in the electrical resistivity and magnetic susceptibility, and a sharp peak of the specific heat and thermal expansion coefficient at a Néel temperature TN = 36.4 K. The first-order nature of the antiferromagnetic transition was ascertained by the observation of thermal hysteresis as well as of latent heat at TN. The present antiferromagnetic transition is found to be not a typical second-order phase transition but a first-order one. From the results of dHvA experiment, we clarified that the Fermi surface is very similar to that of the divalent compound YbSn3, mainly consisting of a nearly spherical hole Fermi surface and eight ellipsoidal electron Fermi surfaces. EuSn3 is possibly a compensated metal, and the occupation of a nearly spherical hole Fermi surface is 3.5% in its Brillouin zone, indicating that EuSn3 is a semimetal.

  3. Cold shock protein YB-1 is involved in hypoxia-dependent gene transcription.

    PubMed

    Rauen, Thomas; Frye, Bjoern C; Wang, Jialin; Raffetseder, Ute; Alidousty, Christina; En-Nia, Abdelaziz; Floege, Jürgen; Mertens, Peter R

    2016-09-16

    Hypoxia-dependent gene regulation is largely orchestrated by hypoxia-inducible factors (HIFs), which associate with defined nucleotide sequences of hypoxia-responsive elements (HREs). Comparison of the regulatory HRE within the 3' enhancer of the human erythropoietin (EPO) gene with known binding motifs for cold shock protein Y-box (YB) protein-1 yielded strong similarities within the Y-box element and 3' adjacent sequences. DNA binding assays confirmed YB-1 binding to both, single- and double-stranded HRE templates. Under hypoxia, we observed nuclear shuttling of YB-1 and co-immunoprecipitation assays demonstrated that YB-1 and HIF-1α physically interact with each other. Cellular YB-1 depletion using siRNA significantly induced hypoxia-dependent EPO production at both, promoter and mRNA level. Vice versa, overexpressed YB-1 significantly reduced EPO-HRE-dependent gene transcription, whereas this effect was minor under normoxia. HIF-1α overexpression induced hypoxia-dependent gene transcription through the same element and accordingly, co-expression with YB-1 reduced HIF-1α-mediated EPO induction under hypoxic conditions. Taken together, we identified YB-1 as a novel binding factor for HREs that participates in fine-tuning of the hypoxia transcriptome. Copyright © 2016 Elsevier Inc. All rights reserved.

  4. Yb-doped aluminophosphosilicate ternary fiber with high efficiency and excellent laser stability

    NASA Astrophysics Data System (ADS)

    Li, Yuwei; Peng, Kun; Zhan, Huan; Liu, Shuang; Ni, Li; Wang, Yuying; Yu, Juan; Wang, Xiaolong; Wang, Jianjun; Jing, Feng; Lin, Aoxiang

    2018-03-01

    By using chelate precursor doping technique and traditional modified chemical vapor deposition system, we fabricated Yb-doped aluminophosphosilicate (Al2O3-P2O5-SiO2, ternary Yb-APS) large-mode-area fiber and reported on its laser performance. The fiber preform was doped with Al, P and Yb with concentration of ∼8000 ppm, ∼1700 ppm and ∼400 ppm in molar percent, respectively. Tested with master oscillator power amplifier system, the home-made Yb-APS fiber was found to present 1.02 kW at 1061.1 nm with a high slope efficiency of 81.2% and excellent laser stability with power fluctuation less than ±1.1% for over 10 h. Compared with Yb-doped aluminosilicate (Al2O3-SiO2, binary Yb-AS) fiber, the introduction of P2O5 effectively suppressed photodarkening effect even the P/Al ratio is much less than 1, indicating that Yb-APS fiber is a better candidate for high power fiber lasers.

  5. Ligand lability and chirality inversion in yb heterobimetallic catalysts.

    PubMed

    Di Bari, Lorenzo; Lelli, Moreno; Salvadori, Piero

    2004-09-20

    We have investigated the exchange dynamics between the free and bound ligand in K3[Yb[(R)-binol]3], the most active heterobimetallic lanthanoid catalyst for cyclic imine hydrophosphonylation; we found that the Yb-binol bond is labile. The rate constant for this exchange was determined through NMR saturation transfer experiments. Upon addition of (S)-binaphthol, ligand exchange leads to the formation of a small quantity of heterochiral complexes and, in the presence of a molar excess of (S)-binaphthol, to chirality inversion of the whole complex. This demonstrates that, in contrast to other analogous systems, K3[Yb(binol)3] displays a strong chiral discrimination, with the overwhelming preference for ligands of the same configuration. The lability of Yb-binol bond in THF may suggest a ligand-to-substrate exchange as a key step in the catalytic process.

  6. Laser, optical and thermomechanical properties of Yb-doped fluorapatite

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Payne, S.A.; Smith, L.K.; DeLoach, L.D.

    The laser performance of Yb-doped fluorapatite (Ca[sub 5](PO[sub 4])[sub 3]F or FAP), is assessed by employing a Ti:sapphire laser operating at 905 nm as the pump source. The authors have measured slope efficiencies to be as high as 79%; the residual decrement from the quantum defect-limited efficiency of 87% is accounted for by the presence of passive loss at the 1,043-nm laser wavelength. The important spectral properties of Yb:FAP were evaluated, including the absorption and emission cross sections, excited-state lifetime, and ground-state energy-level splitting. The emission and absorption cross sections of Yb[sup 3+] in FAP are found to be substantiallymore » larger than those of other Yb-doped media. The thermal, physical, and optical properties of the FAP host are reported as well.« less

  7. Coexistence of metallic and insulating channels in compressed YbB6

    NASA Astrophysics Data System (ADS)

    Ying, Jianjun; Tang, Lingyun; Chen, Fei; Chen, Xianhui; Struzhkin, Viktor V.

    2018-03-01

    It remains controversial whether compressed YbB6 material is a topological insulator or a Kondo topological insulator. We performed high-pressure transport, x-ray diffraction (XRD), x-ray absorption spectroscopy, and Raman-scattering measurements on YbB6 samples in search for its topological Kondo phase. Both high-pressure powder XRD and Raman measurements show no trace of structural phase transitions in YbB6 up to 50 GPa. The nonmagnetic Yb2 + gradually change to magnetic Yb3 + above 18 GPa concomitantly with the increase in resistivity. However, the transition to the insulating state occurs only around 30 GPa, accompanied by the increase in the shear stress, and anomalies in the pressure dependence of the Raman T2 g mode and in the B atomic position. The resistivity at high pressures can be described by a model taking into account coexisting insulating and metallic channels with the activation energy for the insulating channel about 30 meV. We argue that YbB6 may become a topological Kondo insulator at high pressures above 35 GPa.

  8. Cryogenic Yb: YAG Thin-Disk Laser

    DTIC Science & Technology

    2016-09-09

    AFRL-RD-PS- TP-2016-0004 AFRL-RD-PS- TP-2016-0004 CRYOGENIC Yb: YAG THINN-DISK LASER N . Vretenar, et al. 19 August 2011 Technical Paper...Cryogenic Yb: YAG Thin-Disk Laser 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) * N . Vretenar, R. Carson, ***T. Lucas, T. Newell, W.P. Latham...Thin-Disk Laser N . Vretenar,1 T. Carson,2 T. Lucas,3T. Newell,2 W. P. Latham,2 and P. Peterson,3 H. Bostanci,4 J. J. Lindauer4, B. A. Saarloos,4

  9. Investigation of optical properties and the photocatalytic activity of synthesized YbYO4 nanoparticles and YbVO4/NiWO4 nanocomposites by polymeric capping agents

    NASA Astrophysics Data System (ADS)

    Pourmasoud, Saeid; Sobhani-Nasab, Ali; Behpour, Mohsen; Rahimi-Nasrabadi, Mehdi; Ahmadi, Farhad

    2018-04-01

    YbVO4 nanoparticles YbVO4/NiWO4 nanocomposites were synthesized by simple and new method. The effect of various polymeric capping agents such as Tween 80, Tween 20 and PEG on the shape and size of YbVO4/NiWO4 nanocomposites were investigated. YbVO4/NiWO4 nanocomposites were analyzed through some techniques including, X-ray diffraction (XRD), Fourier-transform infrared (FT-IR) spectroscopy, vibrating sample magnetometer (VSM), thermogravimetry differential thermal analysis (TG-DTA), transmission electron microscopy (TEM), field emission electron microscopy (FESEM), ultraviolet-visible spectroscopy (UV-Vis), and energy-dispersive X-ray spectroscopy (EDX). This attempt is the first study on the photocatalytic performance of the YbVO4/NiWO4 nanocomposites in various conditions such as size of particles and kind of dyes (rhodamine B (Rh B), methylene blue (MB), methyl orange (MO), and phenol red (Ph R)), under visible light.

  10. Magnetic properties of rare-earth sulfide YbAgS2

    NASA Astrophysics Data System (ADS)

    Iizuka, Ryosuke; Numakura, Ryosuke; Michimura, Shinji; Katano, Susumu; Kosaka, Masashi

    2018-05-01

    We have succeeded in synthesizing single-phase polycrystalline samples of YbAgS2 belonging to the tetragonal system with space group I41 md . YbAgS2 shows an antiferromagnetic transition at TN = 6.6 K . The effective magnetic moment is in good agreement with the theoretical value for Yb3+ free ion. A broad anomaly is observed just above TN in the temperature dependence of magnetic susceptibility. The entropy released at TN is only about half of Rln2 expected for a Kramers doublet ground state. We consider that these phenomena are due to the existence of short-range magnetic correlations rather than the partial screening of the Yb moments by conduction electrons via the Kondo effect.

  11. Spectroscopic and laser characterization of Yb,Tm:KLu(WO4)2 crystal

    NASA Astrophysics Data System (ADS)

    Loiko, P. A.; Serres, J. M.; Mateos, X.; Demesh, M. P.; Yasukevich, A. S.; Yumashev, K. V.; Petrov, V.; Griebner, U.; Aguiló, M.; Díaz, F.

    2016-01-01

    We report on a comprehensive spectroscopic and laser characterization of monoclinic Yb,Tm:KLu(WO4)2 crystals. Stimulated-emission cross-section spectra corresponding to the 3F4 → 3H6 transition of Tm3+ ions are determined. The radiative lifetime of the 3F4 state of Tm3+ ions is 0.82 ms. The maximum Yb3+ → Tm3+ energy transfer efficiency is 83.9% for 5 at.% Yb - 8 at.% Tm doping. The fractional heat loading for Yb,Tm:KLu(WO4)2 is 0.45 ± 0.05. Using a hemispherical cavity and 5 at.% Yb - 6 at.% Tm doped crystal, a maximum CW power of 227 mW is achieved at 1.983-2.011 μm with a maximum slope efficiency η = 14%. In the microchip laser set-up, the highest slope efficiency is 20% for a 5 at.% Yb- 8 at.% Tm doped crystal with a maximum output power of 201 mW at 1.99-2.007 μm. Operation of Yb,Tm:KLu(WO4)2 as a vibronic laser emitting at 2.081-2.093 μm is also demonstrated.

  12. Photoemission Studies of Kondo Lattice Compounds YbNi3(Ga1-xAlx)9

    NASA Astrophysics Data System (ADS)

    Utsumi, Yuki; Sato, Hitoshi; Nagata, Heisuke; Kodama, Junichi; Ohara, Shigeo; Yamashita, Tetsuro; Mimura, Kojiro; Motonami, Satoru; Arita, Masashi; Ueda, Shigenori; Shimada, Kenya; Namatame, Hirofumi; Taniguchi, Masaki

    We have investigated the electronic structure of YbNi3 (Ga1-xAlx)9 (x = 0, 0.05, 0.10, 0.15) by means of hard x-ray (hν ˜ 6 keV) and low energy (hν ˜ 7 eV) photoemission spectroscopies (HAXPES and LEPES). Both Yb2+ and Yb3+ components are observed in the Yb 3d HAXPES spectra, which is an evidence of the valence fluctuation in YbNi3(Ga1-xAlx)9. A substitution of an Al ion for a Ga ion in YbNi3Ga9 changes the Yb ion into a trivalent state. The LEPES spectra of YbNi3Ga9 clearly exhibit the Kondo peak near the Fermi level (EF) and the Kondo temperature is estimated to be TK ˜ 550 K. With the Al substitution, the Kondo peak is shifted toward EF, indicating the decrease of TK

  13. Forward to cryogenic temperature: laser cooling of Yb: LuLiF crystal

    NASA Astrophysics Data System (ADS)

    Zhong, Biao; Luo, Hao; Lei, Yongqing; Shi, Yanling; Yin, Jianping

    2017-06-01

    The high quality Yb-doped fluoride crystals have broad prospects for optical refrigeration. We have laser cooled the Yb:LuLiF crystal to a temperature below the limit of current thermoelectric coolers ( 180 K). The 5% Yb:LuLiF crystal sample has a geometry of 2 mm×2 mm×5 mm and was supported by two fibers of 200 μm in diameter. They were placed in a 2×10-4 Pa vacuum chamber with an environment temperature of 294.5 K. The 1019 nm CW laser of power 38.7 W was adopted to irradiate the sample. The temperature of the sample was measured utilizing the DLT methods. After 20 minutes of laser irradiation, the 5% Yb:LuLiF crystal sample was cooled down to 182.4 K. By further optimizing experimental conditions and increasing the doped Yb concentration, the Yb:LuLiF crystal might be optically cooled below the cryogenic temperature of 123K in the near future.

  14. YB-1, the E2F Pathway, and Regulation of Tumor Cell Growth

    PubMed Central

    Samuel, Weini; Cao, Helen; Patel, Rachna; Mehta, Reena; Stern, J. Lewis; Reid, Glen; Woolley, Adele G.; Miller, Lance D.; Black, Michael A; Shelling, Andrew N.; Print, Cristin G.; Braithwaite, Antony W.

    2012-01-01

    Background Y-box binding factor 1 (YB-1) has been associated with prognosis in many tumor types. Reduced YB-1 expression inhibits tumor cell growth, but the mechanism is unclear. Methods YB-1 mRNA levels were compared with tumor grade and histology using microarray data from 771 breast cancer patients and with disease-free survival and distant metastasis–free survival using data from 375 of those patients who did not receive adjuvant therapy. Microarrays were further searched for genes that had correlated expression with YB-1 mRNA. Small interfering RNA (siRNA) was used to study the effects of reduced YB-1 expression on growth of three tumor cell lines (MCF-7 breast, HCT116 colon, and A549 lung cancer cells), on tumorigenesis by A549 cells in nude mice, and on global transcription in the three cancer cell lines. Reporter gene assays were used to determine whether YB-1 siRNAs affected the expression of E2F1, and chromatin immunoprecipitation was used to determine whether YB-1 bound to various E2F promoters as well as E2F1-regulated promoters. All P values were from two-sided tests. Results YB-1 levels were elevated in more aggressive tumors and were strongly associated with poor disease-free survival and distant metastasis–free survival. YB-1 expression was often associated with the expression of genes with E2F sites in their promoters. Cells expressing YB-1 siRNA grew substantially more slowly than control cells and formed tumors less readily in nude mice. Transcripts that were altered in cancer cell lines with YB-1 siRNA included 32 genes that are components of prognostic gene expression signatures. YB-1 regulated expression of an E2F1 promoter–reporter construct in A549 cells (eg, relative E2F1 promoter activity with control siRNA = 4.04; with YB-1 siRNA = 1.40, difference= −2.64, 95% confidence interval = −3.57 to −1.71, P < .001) and bound to the promoters of several well-defined E2F1 target genes. Conclusion YB-1 expression is associated with the

  15. Flux growth of Yb(6.6)Ir(6)Sn(16) having mixed-valent ytterbium.

    PubMed

    Peter, Sebastian C; Subbarao, Udumula; Rayaprol, Sudhindra; Martin, Joshua B; Balasubramanian, Mahalingam; Malliakas, Christos D; Kanatzidis, Mercouri G

    2014-07-07

    The compound Yb6.6Ir6Sn16 was obtained as single crystals in high yield from the reaction of Yb with Ir and Sn run in excess indium. Single-crystal X-ray diffraction analysis shows that Yb6.6Ir6Sn16 crystallizes in the tetragonal space group P42/nmc with a = b = 9.7105(7) Å and c = 13.7183(11) Å. The crystal structure is composed of a [Ir6Sn16] polyanionic network with cages in which the Yb atoms are embedded. The Yb sublattice features extensive vacancies on one crystallographic site. Magnetic susceptibility measurements on single crystals indicate Curie-Weiss law behavior <100 K with no magnetic ordering down to 2 K. The magnetic moment within the linear region (<100 K) is 3.21 μB/Yb, which is ∼70% of the expected value for a free Yb(3+) ion suggesting the presence of mixed-valent ytterbium atoms. X-ray absorption near edge spectroscopy confirms that Yb6.6Ir6Sn16 exhibits mixed valence. Resistivity and heat capacity measurements for Yb6.6Ir6Sn16 indicate non-Fermi liquid metallic behavior.

  16. Novel red phosphors KBaEu(XO4)3 (X = Mo, W) show high color purity and high thermostability from a disordered chained structure.

    PubMed

    Wang, G Q; Gong, X H; Chen, Y J; Huang, J H; Lin, Y F; Luo, Z D; Huang, Y D

    2017-05-23

    Two novel red phosphors KBaEu(XO 4 ) 3 (X = Mo, W) have been synthesized by high-temperature solid-state reactions and the crystal structures were determined for the first time. Single-crystal X-ray diffraction data reveal that their space groups are C2/c. The crystalline structure is constituted of K/BaO 8 distorted square antiprisms and distorted EuO 8 polyhedra which form chains lying along the c-axis and two kinds of distorted XO 4 tetrahedra. This high disorder of K/Ba which might lower the crystal field symmetry around Eu 3+ results in the high purity of red emission around 615 nm originating from 5 D 0 → 7 F 2 transition under near-ultraviolet (NUV) excitation. With increasing temperature, the luminescence of KBaEu(XO 4 ) 3 (X = Mo, W) phosphors decreases almost linearly with subtle alteration for the CIE coordinate. As the temperature reaches 550 K, the red emission intensity decreases to 37.3% and 50.7% of that at 300 K for KBaEu(MoO 4 ) 3 and KBaEu(WO 4 ) 3 , respectively. The analysis of the decay curves of the 5 D 0 → 7 F 2 emission at variable temperatures indicates the weak cross relaxation and non-radiative energy transfer between Eu 3+ ions. These results demonstrate that the investigated phosphors are attractive for application in high power NUV excited white LEDs.

  17. Preparation, Biological Evaluation and Dosimetry Studies of 175Yb-Bis-Phosphonates for Palliative Treatment of Bone Pain.

    PubMed

    Fakhari, Ashraf; Jalilian, Amir R; Yousefnia, Hassan; Shanehsazzadeh, Saeed; Samani, Ali Bahrami; Daha, Fariba Johari; Ardestani, Mehdi Shafiee; Khalaj, Ali

    2015-10-05

    Optimized production and quality control of ytterbium-175 (Yb-175) labeled pamidronate and alendronate complexes as efficient agents for bone pain palliation has been presented. Yb-175 labeled pamidronate and alendronate (175Yb-PMD and 175Yb-ALN) complexes were prepared successfully at optimized conditions with acceptable radiochemical purity, stability and significant hydroxyapatite absorption. The biodistribution of complexes were evaluated up to 48 h, which demonstrated significant bone uptake ratios for 175Yb-PAM at all-time intervals. It was also detected that 175Yb-PAM mostly washed out and excreted through the kidneys. The performance of 175Yb-PAM in an animal model was better or comparable to other 175Yb-bone seeking complexes previously reported. Based on calculations, the total body dose for 175Yb-ALN is 40% higher as compared to 175Yb-PAM (especially kidneys) indicating that 175Yb-PAM is probably a safer agent than 175Yb-ALN.

  18. Preparation, Biological Evaluation and Dosimetry Studies of 175Yb-Bis-Phosphonates for Palliative Treatment of Bone Pain

    PubMed Central

    Fakhari, Ashraf; Jalilian, Amir R.; Yousefnia, Hassan; Shanehsazzadeh, Saeed; Samani, Ali Bahrami; Daha, Fariba Johari; Ardestani, Mehdi Shafiee; Khalaj, Ali

    2015-01-01

    Objective: Optimized production and quality control of ytterbium-175 (Yb-175) labeled pamidronate and alendronate complexes as efficient agents for bone pain palliation has been presented. Methods: Yb-175 labeled pamidronate and alendronate (175Yb-PMD and 175Yb-ALN) complexes were prepared successfully at optimized conditions with acceptable radiochemical purity, stability and significant hydroxyapatite absorption. The biodistribution of complexes were evaluated up to 48 h, which demonstrated significant bone uptake ratios for 175Yb-PAM at all-time intervals. It was also detected that 175Yb-PAM mostly washed out and excreted through the kidneys. Results: The performance of 175Yb-PAM in an animal model was better or comparable to other 175Yb-bone seeking complexes previously reported. Conclusion: Based on calculations, the total body dose for 175Yb-ALN is 40% higher as compared to 175Yb-PAM (especially kidneys) indicating that 175Yb-PAM is probably a safer agent than 175Yb-ALN. PMID:27529886

  19. Solvothermal syntheses, and characterization of [Ln(en){sub 4}(SbSe{sub 4})] (Ln=Ce, Pr) and [Ln(en){sub 4}]SbSe{sub 4}.0.5en (Ln=Eu, Gd, Er, Tm, Yb): The effect of lanthanide contraction on the crystal structures of lanthanide selenidoantimonates(V)

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Jia Dingxian; Zhu Aimei; Jin Qinyan

    Two types of lanthanide selenidoantimonates [Ln(en){sub 4}(SbSe{sub 4})] (Ln=Ce(1a), Pr(1b)) and [Ln(en){sub 4}]SbSe{sub 4}.0.5en (Ln=Eu(2a), Gd(2b), Er(2c), Tm(2d), Yb(2e); en=ethylenediamine) were solvothermally synthesized by reactions of LnCl{sub 3}, Sb and Se with the stoichiometric ratio in en solvent at 140 deg. C. The four-en coordinated lanthanide complex cation [Ln(en){sub 4}]{sup 3+} formed in situ balances the charge of SbSe{sub 4}{sup 3-} anion. In compounds 1a and 1b, the SbSe{sub 4}{sup 3-} anion act as a monodentate ligand to coordinate complex [Ln(en){sub 4}]{sup 3+} and the neutral compound [Ln(en){sub 4}(SbSe{sub 4})] is formed. The Ln{sup 3+} ion has a nine-coordinated environmentmore » involving eight N atoms and one Se atom forming a distorted monocapped square antiprism. In 2a-2e the lanthanide(III) ion exists as isolated complex [Ln(en){sub 4}]{sup 3+}, in which the Ln{sup 3+} ion is in a bicapped trigonal prism geometry. A systematic investigation of the crystal structures reveals that two types of structural features of these lanthanide selenidoantimonates are related with lanthanides contraction across the lanthanide series. TG curves show that compounds 1a-1b and 2a-2e remove their organic components in one and two steps, respectively. - Graphical abstract: Two types of lanthanide selenidoantimonates [Ln(en){sub 4}(SbSe{sub 4})] (Ln=Ce, Pr) and [Ln(en){sub 4}]SbSe{sub 4}.0.5en (Ln=Eu, Gd, Er, Tm, Yb; en=ethylenediamine) have been synthesized under the mild solvothermal conditions, and a systematic investigation of the crystal structures reveals that two types of structural features of these lanthanide selenidoantimonates are related with lanthanides contraction across the lanthanide series.« less

  20. Mechanisms of combustion synthesis and magnetic response of high-surface-area hexaboride compounds.

    PubMed

    Kanakala, Raghunath; Escudero, Roberto; Rojas-George, Gabriel; Ramisetty, Mohan; Graeve, Olivia A

    2011-04-01

    We present an analysis of the combustion synthesis mechanisms for the preparation of hexaboride materials using three compounds as model systems: EuB(6), YbB(6), and YB(6). These three hexaborides were chosen because of the differences in ionic radii between Eu(3+), Yb(3+), and Y(3+), which is a factor in their stability. The powders were prepared using metal nitrates, carbohydrazide, and two different boron precursor powders. The resulting materials were analyzed by X-ray diffraction, which showed that combustion synthesis is effective for the synthesis of EuB(6), since the Eu(3+) ion has an ionic radius greater than ∼1 Å. The synthesis of YbB(6) and YB(6) is not as effective because of the small size of the Yb(3+) and Y(3+) ions, making the hexaborides of these metals less stable and resulting in the synthesis of borates due to the presence of oxygen during the combustion process. Scanning electron microscopy and dynamic light scattering of the EuB(6) powders shows that the particle size of the hexaboride product is dependent on the particle size of the boron precursor. The magnetic susceptibility of our EuB(6) powders manifests irreversible behavior at low applied fields, which disappears at higher fields. This behavior can be attributed to the increase in size and number of magnetic polarons with increasing magnetic field. © 2011 American Chemical Society

  1. High-energy, ceramic-disk Yb:LuAG laser amplifier.

    PubMed

    Siebold, M; Loeser, M; Roeser, F; Seltmann, M; Harzendorf, G; Tsybin, I; Linke, S; Banerjee, S; Mason, P D; Phillips, P J; Ertel, K; Collier, J C; Schramm, U

    2012-09-24

    We report the first short-pulse amplification results to several hundred millijoule energies in ceramic Yb:LuAG. We have demonstrated ns-pulse output from a diode-pumped Yb:LuAG amplifier at a maximum energy of 580 mJ and a peak optical-to-optical efficiency of 28% at 550 mJ. In cavity dumped operation of a nanosecond oscillator we obtained 1 mJ at up to 100 Hz repetition rate. A gain bandwidth of 5.4 nm was achieved at room temperature by measuring the small-signal single-pass gain. Furthermore, we compared our results with Yb:YAG within the same amplifier system.

  2. Yb-doped polarizing fiber

    NASA Astrophysics Data System (ADS)

    Gillooly, A.; Webb, A. S.; Favero, F. C.; Bouchan, T.; Cooper, L. J.; Read, D.; Hill, M.

    2017-02-01

    An ytterbium (Yb) doped polarizing fiber is demonstrated. The fiber offers the opportunity to build all-fiber lasers with single polarization output and without the need for free-space polarizing components. Traditional single polarization fiber lasers utilize polarization-maintaining (PM) gain fiber with a single polarization stimulation signal. Whilst this results in an approximation to a single polarization laser, the spontaneous emission from the unstimulated polarization state limits the polarization extinction ratio (PER). The PER is further limited as the stimulated signal is prone to crosstalk. Furthermore, controlling amplitude modulation of the stimulated signal is critical for maximizing the peak power of an optical pulse, particularly for high energy lasers. If light is allowed to leak in to the unstimulated axis it will travel at a different velocity to the stimulated axis and can cross-couple back into the signal axis, creating an interference effect which leads to amplitude modulation on the signal pulse. Single-polarization Yb-doped fiber ensures that light on the fast axis is constantly attenuated; ensuring that light on the unstimulated axis cannot propagate and thus cannot degrade the PER or create amplitude modulation. In this paper we report on, to the best of our knowledge, the first demonstration of a single polarization Yb-doped bowtie optical fiber manufactured using a combination of Modified Chemical Vapor Deposition (MCVD) and rare-earth solution doping technology. The fiber has a single-polarization window of 80nm at the operating wavelength of 1060nm and a PER of >18dB. The fabrication and characterization of the fiber is reported.

  3. Nuclear YB-1 expression as a negative prognostic marker in nonsmall cell lung cancer.

    PubMed

    Gessner, C; Woischwill, C; Schumacher, A; Liebers, U; Kuhn, H; Stiehl, P; Jürchott, K; Royer, H D; Witt, C; Wolff, G

    2004-01-01

    The human Y-box binding protein, YB-1, is a multifunctional protein that regulates gene expression. Nuclear expression of YB-1 has been associated with chemoresistance and poor prognosis of tumour patients. Representative samples from autopsied material of primary tumours from 77 patients with NSCLC were investigated by immunohistochemistry for subcellular distribution of YB-1 and p53, in order to evaluate the prognostic role of nuclear expression of YB-1. Cytoplasmic YB-1 expression was found in all tumour samples, whereas nuclear expression was only observed in 48%. There was no correlation with histological classification, clinical parameters or tumour size, stage and metastasis status. However, patients with positive nuclear YB-1 expression in tumours showed reduced survival times when compared with patients without nuclear expression. Including information about the histology and mutational status for p53 increased the prognostic value of nuclear YB-1. Patients with nuclear YB-1 expression and p53 mutations had the worst prognosis (median survival 3 months), while best outcome was found in patients with no nuclear YB-1 and wildtype p53 (median survival 15 months). This suggests that the combined analysis of both markers allows a better identification of subgroups with varying prognosis. Nuclear expression of Y-box binding protien seems to be an independent prognostic marker.

  4. Effect of silver nanoparticles on the 1.53 μm fluorescence in Er3+/Yb3+ codoped tellurite glasses

    NASA Astrophysics Data System (ADS)

    Wu, Libo; Zhou, Yaxun; Zhou, Zizhong; Cheng, Pan; Huang, Bo; Yang, Fengjing; Li, Jun

    2016-07-01

    Improving the spectroscopic properties of rare earth (RE) doped glass materials is a challenging task. In the present work the metallic silver nanoparticles (Ag NPs) were embedded into Er3+/Yb3+ codoped tellurite glasses with composition TeO2-Bi2O3-TiO2, prepared using melt-quenching and subsequent heat-treated techniques, and the improved effect of Ag NPs on the 1.53 μm band fluorescence of Er3+ ions was investigated. About 24 h heat-treatment of Er3+/Yb3+ codoped tellurite glass containing 1 mol % amount of AgNO3 at the temperature 370 °C yielded the well-dispersed and near-spherical Ag NPs with ∼11.4 nm average diameter as evidenced by transmission electron microscopy (TEM) image. The intense 1.53 μm band fluorescence was observed in the prepared Er3+/Yb3+ codoped tellurite glasses under the excitation of 980 nm and was further improved with the presence of Ag NPs in the glass matrix, which is attributed to the enhanced local electric field around doped RE ions induced by Ag NPs and the possible energy transfer from Ag NPs to Er3+ ions. The enhanced local electric field was well demonstrated by comparing the variation of emission spectra of hypersensitive probe Eu3+ ions in tellurite glasses with and without Ag NPs. From the Judd-Ofelt analysis, it was also found that the value of Ω6 intensity parameter increased slightly with the increase of Ag NPs concentration in a certain range, also confirming the possibility of realizing strong fluorescence emission. In addition, the amorphous structural nature was demonstrated by the measured X-ray diffraction (XRD) patterns with no sharp diffraction peak. The enhanced 1.53 μm band fluorescence indicates that the Er3+/Yb3+ codoped tellurite glass with an appropriate amount of Ag NPs is a promising candidate for the development of Er3+-doped fiber amplifiers (EDFAs) applied in the WDM systems.

  5. Interplay between YB-1 and IL-6 promotes the metastatic phenotype in breast cancer cells.

    PubMed

    Castellana, Bàrbara; Aasen, Trond; Moreno-Bueno, Gema; Dunn, Sandra E; Ramón y Cajal, Santiago

    2015-11-10

    Epithelial to mesenchymal transition (EMT) induces cell plasticity and promotes metastasis. The multifunctional oncoprotein Y-box binding protein-1 (YB-1) and the pleiotropic cytokine interleukin 6 (IL-6) have both been implicated in tumor cell metastasis and EMT, but via distinct pathways. Here, we show that direct interplay between YB-1 and IL-6 regulates breast cancer metastasis. Overexpression of YB-1 in breast cancer cell lines induced IL-6 production while stimulation with IL-6 increased YB-1 expression and YB-1 phosphorylation. Either approach was sufficient to induce EMT features, including increased cell migration and invasion. Silencing of YB-1 partially reverted the EMT and blocked the effect of IL-6 while inhibition of IL-6 signaling blocked the phenotype induced by YB-1 overexpression, demonstrating a clear YB-1/IL-6 interdependence. Our findings describe a novel signaling network in which YB-1 regulates IL-6, and vice versa, creating a positive feed-forward loop driving EMT-like metastatic features during breast cancer progression. Identification of signaling partners or pathways underlying this co-dependence may uncover novel therapeutic opportunities.

  6. Electronic structure and direct observation of ferrimagnetism in multiferroic hexagonal YbFeO 3

    DOE PAGES

    Cao, Shi; Sinha, Kishan; Zhang, Xin; ...

    2017-06-26

    Here, the magnetic interactions between rare-earth and Fe ions in hexagonal rare-earth ferrites (h–RFeO 3), may amplify the weak ferromagnetic moment on Fe, making these materials more appealing as multiferroics. To elucidate the interaction strength between the rare-earth and Fe ions as well as the magnetic moment of the rare-earth ions, element-specific magnetic characterization is needed. Using x-ray magnetic circular dichroism, we have studied the ferrimagnetism in h–YbFeO 3 by measuring the magnetization of Fe and Yb separately. The results directly show antialignment of magnetization of Yb and Fe ions in h–YbFeO 3 at low temperature, with an exchange fieldmore » on Yb of about 17 kOe. The magnetic moment of Yb is about 1.6μ B at low temperature, significantly reduced compared with the 4.5μ B moment of a free Yb 3+. In addition, the saturation magnetization of Fe in h–YbFeO 3 has a sizable enhancement compared with that in h–LuFeO 3. These findings directly demonstrate that ferrimagnetic order exists in h–YbFeO 3; they also account for the enhancement of magnetization and the reduction of coercivity in h–YbFeO 3 compared with those in h–LuFeO 3 at low temperature, suggesting an important role for the rare-earth ions in tuning the multiferroic properties of h–RFeO 3.« less

  7. Superconducting transition temperature in the Y(1-x)M(x)Ba2Cu3O(y) system

    NASA Astrophysics Data System (ADS)

    Suzuki, Takeyuki; Yamazaki, Tsutomu; Sekine, Ryuuta; Koukitsu, Akinori; Seki, Hisashi

    1989-04-01

    Experimental results are presented for the inclusion of compositional additives, M, to the sintered high-temperature superconductor Y(1-x)M(x)Ba2Cu3O(y); M can be the oxides of Mg, Ce, Gd, Yb, Ti, Zr, V, Nb, Ta, Cr, Mo, W, Mn, Fe, Co, Ni, Zn, B, Al, Ga, In, Si, Ge, Sn, Pb, Sb, Bi, and Te, as well as Li, Na, K, Ca, Sr, and La carbonates. Temperature dependence of the electrical resistance was measured down to about 80 K. Attention is given to the influence of ionic radius and the valence of the M species.

  8. The isotopic and chemical evolution of Mount St. Helens

    USGS Publications Warehouse

    Halliday, A.N.; Fallick, A.E.; Dickin, A.P.; Mackenzie, A.B.; Stephens, W.E.; Hildreth, W.

    1983-01-01

    Isotopic and major and trace element analysis of nine samples of eruptive products spanning the history of the Mt. St. Helens volcano suggest three different episodes; (1) 40,000-2500 years ago: eruptions of dacite with ??{lunate}Nd = +5, ??{lunate}Sr = -10, variable ??18O, 206Pb/204Pb ??? 18.76, Ca/Sr ??? 60, Rb/Ba ??? 0.1, La/Yb ??? 18, (2) 2500-1000 years ago: eruptions of basalt, andesite and dacite with ??{lunate}Nd = +4 to +8, ??{lunate}Sr = -7 to -22, variable ??18O (thought to represent melting of differing mantle-crust reservoirs), 206Pb/204Pb = 18.81-18.87, variable Ca/Sr, Rb/Ba, La/Yb and high Zr, (3) 1000 years ago to present day: eruptions of andesite and dacite with ??{lunate}Nd = +6, ??{lunate}Sr = -13, ??18O ???6???, variable 206Pb/204Pb, Ca/Sr ??? 77, Rb/Ba = 0.1, La/Yb ??? 11. None of the products exhibit Eu anomalies and all are LREE enriched. There is a strong correlation between 87Sr/86Sr and differentiation indices. These data are interpreted in terms of a mantle heat source melting young crust bearing zircon and garnet, but not feldspar, followed by intrusion of this crustal reservoir by mantle-derived magma which caused further crustal melting and contaminated the crustal magma system with mafic components. Since 1000 years ago all the eruptions have been from the same reservoir which has displayed a much more gradual re-equilibration of Pb isotopic compositions than other components suggesting that Pb is being transported via a fluid phase. The Nd and Sr isotopic compositions lie along the mantle array and suggest that the mantle underneath Mt. St. Helens is not as depleted as MORB sources. There is no indication of seawater involvement in the source region. ?? 1983.

  9. Innate immunity: Bacterial cell-wall muramyl peptide targets the conserved transcription factor YB-1.

    PubMed

    Laman, A G; Lathe, R; Savinov, G V; Shepelyakovskaya, A O; Boziev, Kh M; Baidakova, L K; Chulin, A N; Brovko, F A; Svirshchevskaya, E V; Kotelevtsev, Y; Eliseeva, I A; Guryanov, S G; Lyabin, D N; Ovchinnikov, L P; Ivanov, V T

    2015-07-08

    The bacterial cell wall muramyl dipeptides MDP and glucosaminyl-MDP (GMDP) are powerful immunostimulators but their binding target remains controversial. We previously reported expression cloning of GMDP-binding polypeptides and identification of Y-box protein 1 (YB-1) as their sole target. Here we show specific binding of GMDP to recombinant YB-1 protein and subcellular colocalization of YB-1 and GMDP. GMDP binding to YB-1 upregulated gene expression levels of NF-κB2, a mediator of innate immunity. Furthermore, YB-1 knockdown abolished GMDP-induced Nfkb2 expression. GMDP/YB-1 stimulation led to NF-κB2 cleavage, transport of activated NF-κB2 p52 to the nucleus, and upregulation of NF-κB2-dependent chemokine Cxcr4 gene expression. Therefore, our findings identify YB-1 as new target for muramyl peptide signaling. Copyright © 2015 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.

  10. Intermediate Valence Tuning and Seebeck Coefficient Optimization in Yb-based Low-Temperature Thermoelectric Materials

    NASA Astrophysics Data System (ADS)

    Lehr, Gloria; Morelli, Donald; Jin, Hyungyu; Heremans, Joseph

    2014-03-01

    Several Yb-based intermediate valence compounds have unique thermoelectric properties at low temperatures. These materials are interesting to study for niche applications such as cryogenic Peltier cooling of infrared sensors on satellites. Elements of different sizes, which form isostructural compounds, are used to form solid solutions creating a chemical pressure (smaller atoms - Sc) or relaxation (larger atoms - La) to alter the volume of the unit cell and thereby manipulate the average Yb valence. Magnetic susceptibility measurements show a strong correlation between the Seebeck coefficient and the ratio of trivalent to divalent Yb in these compounds. Two different Yb-based solid solution systems, Yb1-xScxAl2 and Yb1-xLaxCu2Si2, demonstrate that the concentration of Yb can be used to tune both the magnitude of the Seebeck coefficient as well as the temperature at which its absolute maximum occurs. This work is supported by Michigan State University and AFOSR-MURI ``Cryogenic Peltier Cooling'' Contract #FA9550-10-1-0533.

  11. Dual spectra band emissive Eu2+/Mn2+ co-activated alkaline earth phosphates for indoor plant growth novel phosphor converted-LEDs.

    PubMed

    Yun, Young Jun; Kim, Jin Kyu; Ju, Ji Young; Choi, Seul Ki; Park, Woon Ik; Suh, Jae Yong; Jung, Ha-Kyun; Kim, Yongseon; Choi, Sungho

    2017-05-10

    This paper reports designing a novel single composition blue/red color illuminating phosphor followed by fabricating "smart" agricultural/horticultural LED lighting. Color-tunable Eu 2+ /Mn 2+ co-activated alkaline earth phosphates, Na(Sr,Ba)PO 4 and Ca 3 Mg 3 (PO 4 ) 4 , are considered, and the stable doping sites for the corresponding activators are identified by using first-principle DFT calculations. We can realize the designated color purity with stable thermal quenching preserved luminescence behavior is induced by the Eu 2+ center positioned at different coordination states with intermixed Sr 2+ /Ba 2+ sites in Na(Sr,Ba)PO 4 hosts. Moreover, we demonstrate that the resultant LED lighting adopting the proposed novel phosphor composition stimulates the enhanced photosynthesis reaction for indoor hydroponics plants, such as oats and onions, which is superior to the narrow line emission band induced by the mixture of conventional red/green/blue LEDs. Thus, using the color-tunable single composition luminescent material may produce an innovative energy-efficient artificial lighting for indoor plant growth.

  12. Resolution of the discrepancy between the variation of the physical properties of Ce 1-xYb xCoIn 5 single crystals and thin films with Yb composition

    DOE PAGES

    Jang, S.; White, B. D.; Lum, I. K.; ...

    2014-11-18

    The extraordinary electronic phenomena including an Yb valence transition, a change in Fermi surface topology, and suppression of the heavy fermion quantum critical field at a nominal concentration x≈0.2 have been found in the Ce 1-xYb xCoIn 5 system. These phenomena have no discernable effect on the unconventional superconductivity and normal-state non-Fermi liquid behaviour that occur over a broad range of x up to ~0.8. However, the variation of the coherence temperature T* and the superconducting critical temperature T c with nominal Yb concentration x for bulk single crystals is much weaker than that of thin films. To determine whethermore » differences in the actual Yb concentration of bulk single crystals and thin film samples might be responsible for these discrepancies, we employed Vegard’s law and the spectroscopically determined values of the valences of Ce and Yb as a function of x to determine the actual composition x act of bulk single crystals. This analysis is supported by energy-dispersive X-ray spectroscopy, wavelength-dispersive X-ray spectroscopy, and transmission X-ray absorption edge spectroscopy measurements. The actual composition x act is found to be about one-third of the nominal concentration x up to x~0.5, and resolves the discrepancy between the variation of the physical properties of Ce 1-xYb xCoIn 5 single crystals and thin films with Yb concentration.« less

  13. Yb:YAG Lasers for Space Based Remote Sensing

    NASA Technical Reports Server (NTRS)

    Ewing, J.J.; Fan, T. Y.

    1998-01-01

    Diode pumped solid state lasers will play a prominent role in future remote sensing missions because of their intrinsic high efficiency and low mass. Applications including altimetry, cloud and aerosol measurement, wind velocity measurement by both coherent and incoherent methods, and species measurements, with appropriate frequency converters, all will benefit from a diode pumped primary laser. To date the "gold standard" diode pumped Nd laser has been the laser of choice for most of these concepts. This paper discusses an alternate 1 micron laser, the YB:YAG laser, and its potential relevance for lidar applications. Conceptual design analysis and, to the extent possible at the time of the conference, preliminary experimental data on the performance of a bread board YB:YAG oscillator will be presented. The paper centers on application of YB:YAG for altimetry, but extension to other applications will be discussed.

  14. Ramifications of codoping SrI2:Eu with isovalent and aliovalent impurities

    NASA Astrophysics Data System (ADS)

    Feng, Qingguo; Biswas, Koushik

    2016-12-01

    Eu2+ doped SrI2 is an important scintillator having applications in the field of radiation detection. Codoping techniques are often useful to improve the electronic response of such insulators. Using first-principles based approach, we report on the properties of SrI2:Eu and the influence of codoping with aliovalent (Na, Cs) and isovalent (Mg, Ca, Ba, and Sn) impurities. These codopants do not preferably bind with Eu and are expected to remain as isolated impurities in the SrI2 host. As isolated defects they display amphoteric behavior having, in most cases, significant ionization energies of the donor and acceptor levels. Furthermore, the acceptor states of Na, Cs, and Mg can bind with I-vacancy forming charge compensated donor-acceptor pairs. Such pairs may also bind additional holes or electrons similar to the isolated defects. Lack of deep-to-shallow behavior upon codoping and its ramifications will be discussed.

  15. Local structure investigation of Ga and Yb dopants in Co 4 Sb 12 skutterudites

    DOE PAGES

    Hu, Yanyun; Chen, Ning; Clancy, J. P.; ...

    2017-12-29

    We report our x-ray absorption spectroscopy studies at both Ga K-edge and Yb L 2-edge to elucidate the local structure of Ga and Yb dopants in Yb xGa yCo 4Sb 12. Our extended x-ray absorption fine structure (EXAFS) data confirm that Ga atoms occupy two crystallographic sites: one is the 24g site replacing Sb, and the other is the 2a site in the off-center void position. We find that the occupancy ratio of these two sites varies significantly as a function of the filling fraction of additional Yb, which exclusively occupies the 2a on-center site. At low concentrations of Yb,more » Ga 24g and Ga 2a dopants coexist and they form a charge-compensated compound defect proposed by Qiu et al. [Adv. Mater. 23, 3194 (2013)]. The Ga 24g occupancy increases gradually with increasing Yb concentration, and almost all Ga occupies the 24g site for the highest Yb concentration (x = 0.4). In addition to the local crystal structure evidence provided by our EXAFS data, we also present x-ray absorption near-edge structure (XANES) spectra, which show a small Ga K-edge energy shift as a function of Yb concentration consistent with the change from predominantly Ga 2a to Ga 24g states. Our result suggests that the increased solubility of Yb in Yb-Ga co-doped Co 4Sb 12 skutterudites is due to the increased Ga 24g electron acceptor, and thus provides an important strategy to optimize the carrier concentration in partially filled skutterudites.« less

  16. Local structure investigation of Ga and Yb dopants in Co 4 Sb 12 skutterudites

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Hu, Yanyun; Chen, Ning; Clancy, J. P.

    We report our x-ray absorption spectroscopy studies at both Ga K-edge and Yb L 2-edge to elucidate the local structure of Ga and Yb dopants in Yb xGa yCo 4Sb 12. Our extended x-ray absorption fine structure (EXAFS) data confirm that Ga atoms occupy two crystallographic sites: one is the 24g site replacing Sb, and the other is the 2a site in the off-center void position. We find that the occupancy ratio of these two sites varies significantly as a function of the filling fraction of additional Yb, which exclusively occupies the 2a on-center site. At low concentrations of Yb,more » Ga 24g and Ga 2a dopants coexist and they form a charge-compensated compound defect proposed by Qiu et al. [Adv. Mater. 23, 3194 (2013)]. The Ga 24g occupancy increases gradually with increasing Yb concentration, and almost all Ga occupies the 24g site for the highest Yb concentration (x = 0.4). In addition to the local crystal structure evidence provided by our EXAFS data, we also present x-ray absorption near-edge structure (XANES) spectra, which show a small Ga K-edge energy shift as a function of Yb concentration consistent with the change from predominantly Ga 2a to Ga 24g states. Our result suggests that the increased solubility of Yb in Yb-Ga co-doped Co 4Sb 12 skutterudites is due to the increased Ga 24g electron acceptor, and thus provides an important strategy to optimize the carrier concentration in partially filled skutterudites.« less

  17. Scaling of Yb-Fiber Frequency Combs

    NASA Astrophysics Data System (ADS)

    Ruehl, Axel; Marcinkevicius, Andrius; Fermann, Martin E.; Hartl, Ingmar

    2010-06-01

    Immediately after their introduction in 1999, femtosecond laser frequency combs revolutionized the field of precision optical frequency metrology and are key elements in many experiments. Frequency combs based on femtosecond Er-fiber lasers based were demonstrated in 2005, allowing additionally rugged, compact set-ups and reliable unattended long-term operation. The introduction of Yb-fiber technology led to an dramatic improvement in fiber-comb performance in various aspects. Low-noise Yb-fiber femtosecond oscillators enabled a reduction of relative comb tooth linewidth to the sub-Hz level as well as scaling of the fundamental comb spacings up to 1 GHz. This is beneficial for any frequency-domain comb application due to the higher power per comb-mode. Many spectroscopic applications require, however, frequency combs way beyond the wavelength range accessible with broad band laser materials, so nonlinear conversion and hence higher peak intensity is required. We demonstrated power scaling of Yb-fiber frequency combs up to 80 W average power in a strictly linear chirped-pulse amplification schemes compatible with low-noise phase control. These high-power Yb-fiber-frequency combs facilitated not only the extension to the mid-IR spectral region. When coupled to a passive enhancement cavity, the average power can be further scaled to the kW-level opening new capabilities for XUV frequency combs via high-harmonic generation. All these advances of fiber-based frequency combs will trigger many novel applications both in fundamental and applied sciences. Schibli et al., Nature Photonics 2 355 (2008). Hartl et al., MF9 in Advanced Solid-State Photonics. 2009, Optical Society of America. Ruehl et al., AWC7 in Advanced Solid-State Photonics. 2010, Optical Society of America. Adler et al., Optics Letters 34 1330 (2009). Yost et al., Nature Physics 5 815 (2009).

  18. Luminescence of Yb3+ ions in silica-based glasses synthesized by SPCVD

    NASA Astrophysics Data System (ADS)

    Savel'ev, E. A.; Krivovichev, A. V.; Yapaskurt, V. O.; Golant, K. M.

    2017-02-01

    The spectra and decay kinetics of Yb3+ single-ion and cooperative luminescence in silica-based optical slab waveguides are investigated. The slab waveguides with a high content of Yb and various amounts of P and Al additives to the light-guiding core glass were fabricated on the basis of fused and unfused glassy layers synthesized via surface-plasma chemical vapor deposition (SPCVD). Luminescence was pumped by laser diodes at ∼904 nm and ∼967 nm wavelengths and recorded in the 450-1175 nm spectral band. For the pure silica host doped with Yb, only the influence of cluster sizes on the luminescence decay kinetics is determined. It is found that the profusion of deposited glass with increased Al content favors separation by geometry of the Yb3+ and Tm3+ ions; the latter are present in the glass as an uncontrollable contamination. Evidence was found that at least two different types of Yb clusters were formed in P doped silica as a result of profusion.

  19. Application of Yb:YAG short pulse laser system

    DOEpatents

    Erbert, Gaylen V.; Biswal, Subrat; Bartolick, Joseph M.; Stuart, Brent C.; Crane, John K.; Telford, Steve; Perry, Michael D.

    2004-07-06

    A diode pumped, high power (at least 20W), short pulse (up to 2 ps), chirped pulse amplified laser using Yb:YAG as the gain material is employed for material processing. Yb:YAG is used as the gain medium for both a regenerative amplifier and a high power 4-pass amplifier. A single common reflective grating optical device is used to both stretch pulses for amplification purposes and to recompress amplified pulses before being directed to a workpiece.

  20. Electronic structure of YbB 6 : Is it a topological insulator or not?

    DOE PAGES

    Kang, Chang -Jong; Denlinger, J. D.; Allen, J. W.; ...

    2016-03-17

    Here, to finally resolve the controversial issue of whether or not the electronic structure of YbB6 is nontrivially topological, we have made a combined study using angle-resolved photoemission spectroscopy (ARPES) of the nonpolar (110) surface and density functional theory (DFT). The flat-band conditions of the (110) ARPES avoid the strong band bending effects of the polar (001) surface and definitively show that YbB 6 has a topologically trivial B 2p–Yb 5d semiconductor band gap of ~0.3 eV. Accurate determination of the low energy band topology in DFT requires the use of a modified Becke-Johnson exchange potential incorporating spin-orbit coupling andmore » an on-site Yb 4f Coulomb interaction U as large as 7 eV. The DFT result, confirmed by a more precise GW band calculation, is similar to that of a small gap non-Kondo nontopological semiconductor. Additionally, the pressure-dependent electronic structure of YbB 6 is investigated theoretically and found to transform into a p–d overlap semimetal with small Yb mixed valency.« less

  1. Controlling Magnetism via Transition Metal Exchange in the Series of Intermetallics Eu( T1, T2)5In ( T = Cu, Ag, Au)

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Mudring, Anja -Verena; Smetana, Volodymyr; Pecharsky, Vitalij K.

    Three series of intermetallic compounds Eu( T1, T2) 5In (T = Cu, Ag, Au) have been investigated in full compositional ranges. Single crystals of all compounds have been obtained by self-flux and were analyzed by single X-ray diffraction revealing the representatives to fall into two structure types: CeCu 6 ( oP28, Pnma, a = 8.832(3)–9.121(2) Å, b = 5.306(2)–5.645(1) Å, c = 11.059(4)–11.437(3) Å, V = 518.3(3)–588.9(2) Å 3) and YbMo2Al4 ( t I14, I4/ mmm, a = 5.417(3)–5.508(1) Å, c = 7.139(2)– 7.199(2) Å, V = 276.1(2)–285.8(1) Å 3). The structural preference was found to depend on the cation/anionmore » size ratio, while the positional preference within the CeCu 6 type structure shows an apparent correlation with the anion size. Chemical compression, hence, a change in cell volume, which occurs upon anion substitution appears to be the main driving force for the change of magnetic ordering. While EuAg 5In shows antiferromagnetic behavior at low temperatures, mixing Cu and Au within the same type of structure results in considerable changes in the magnetism. The Eu(Cu,Au) 5In alloys with CeCu 6 structure show complex magnetic behaviors and strong magnetic field-induced spin-reorientation transition with the critical field of the transition being dependent on Cu/Au ratio. The alloys adopting the YbMo 2Al 4 type structure are ferromagnets exhibiting unusually high magnetic moments. The heat capacity of EuAu 2.66Cu 2.34In reveals a double-peak structure evolving with the magnetic field. Furthermore, low-temperature X-ray powder diffraction does not show a structural transition.« less

  2. Controlling Magnetism via Transition Metal Exchange in the Series of Intermetallics Eu( T1, T2)5In ( T = Cu, Ag, Au)

    DOE PAGES

    Mudring, Anja -Verena; Smetana, Volodymyr; Pecharsky, Vitalij K.; ...

    2017-11-24

    Three series of intermetallic compounds Eu( T1, T2) 5In (T = Cu, Ag, Au) have been investigated in full compositional ranges. Single crystals of all compounds have been obtained by self-flux and were analyzed by single X-ray diffraction revealing the representatives to fall into two structure types: CeCu 6 ( oP28, Pnma, a = 8.832(3)–9.121(2) Å, b = 5.306(2)–5.645(1) Å, c = 11.059(4)–11.437(3) Å, V = 518.3(3)–588.9(2) Å 3) and YbMo2Al4 ( t I14, I4/ mmm, a = 5.417(3)–5.508(1) Å, c = 7.139(2)– 7.199(2) Å, V = 276.1(2)–285.8(1) Å 3). The structural preference was found to depend on the cation/anionmore » size ratio, while the positional preference within the CeCu 6 type structure shows an apparent correlation with the anion size. Chemical compression, hence, a change in cell volume, which occurs upon anion substitution appears to be the main driving force for the change of magnetic ordering. While EuAg 5In shows antiferromagnetic behavior at low temperatures, mixing Cu and Au within the same type of structure results in considerable changes in the magnetism. The Eu(Cu,Au) 5In alloys with CeCu 6 structure show complex magnetic behaviors and strong magnetic field-induced spin-reorientation transition with the critical field of the transition being dependent on Cu/Au ratio. The alloys adopting the YbMo 2Al 4 type structure are ferromagnets exhibiting unusually high magnetic moments. The heat capacity of EuAu 2.66Cu 2.34In reveals a double-peak structure evolving with the magnetic field. Furthermore, low-temperature X-ray powder diffraction does not show a structural transition.« less

  3. Distribution behavior of uranium, neptunium, rare-earth elements ( Y, La, Ce, Nd, Sm, Eu, Gd) and alkaline-earth metals (Sr,Ba) between molten LiClKCI eutectic salt and liquid cadmium or bismuth

    NASA Astrophysics Data System (ADS)

    Kurata, M.; Sakamura, Y.; Hijikata, T.; Kinoshita, K.

    1995-12-01

    Distribution coefficients of uranium neptunium, eight rare-earth elements (Y, La, Ce, Pr, Nd, Sm, Eu and Gd) and two alkaline-earth metals (Sr and Ba) between molten LiCl-KCI eutectic salt and either liquid cadmium or bismuth were measured at 773 K. Separation factors of trivalent rare-earth elements to uranium or neptunium in the LiCl-KCl/Bi system were by one or two orders of magnitude larger than those in the LiCl-KCl/Cd system. On the contrary, the separation factors of alkaline-earth metals and divalent rare-earth elements to trivalent rare-earth elements were by one or two orders of magnitude smaller in the LiCl-KCl/Bi system.

  4. Multi-watt passively Q-switched Yb:YAB/Cr:YAG microchip lasers

    NASA Astrophysics Data System (ADS)

    Serres, Josep Maria; Loiko, Pavel; Mateos, Xavier; Liu, Junhai; Zhang, Huaijing; Yumashev, Konstantin; Griebner, Uwe; Petrov, Valentin; Aguiló, Magdalena; Díaz, Francesc

    2017-02-01

    A trigonal 5.6 at.% Yb:YAl3(BO3)4 (Yb:YAB) crystal is employed in continuous-wave (CW) and passively Q-switched microchip lasers pumped by a diode at 978 nm. Using a 3 mm-thick, c-cut Yb:YAB crystal, which has a higher pump absorption efficiency, efficient CW microchip laser operation is demonstrated. This laser generated a maximum output power of 7.18 W at 1041-1044 nm with a slope efficiency η of 67% (with respect to the absorbed pump power) and an almost diffraction-limited beam, M2 x,y < 1.1. Inserting a Cr:YAG saturable absorber, stable passive Q-switching of the Yb:YAB microchip laser was obtained. The maximum average output power from the Yb:YAB/Cr:YAG laser reached 2.82 W at 1042 nm with η = 53% and a conversion efficiency with respect to the CW mode of 65% (when using a 0.7 mm-thick Cr:YAG). The latter corresponded to a pulse duration and energy of 7.1 ns / 47 μJ at a pulse repetition rate (PRR) of 60 kHz. Using a 1.3 mm-thick Cr:YAG, 2.02 W were achieved at 1041 nm corresponding to η = 38%. The pulse characteristics were 4.9 ns / 83 μJ at PRR = 24.3 kHz and the maximum peak power reached 17 kW. Yb:YAB crystals are very promising for compact sub-ns power-scalable microchip lasers.

  5. Luminescence properties of phosphate phosphor Ba{sub 3}Y(PO{sub 4}){sub 3}:Sm{sup 3+}

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Yang, Fu; Liu, Yufeng, E-mail: liuyufeng4@126.com; Tian, Xiaodong

    2015-05-15

    A series of reddish orange-emitting phosphate phosphors Ba{sub 3}Y{sub 1−x}(PO{sub 4}){sub 3}:xSm{sup 3+}(0.01≤x≤0.20) were synthesized by solid-state reaction. X-ray diffraction and photoluminescence spectra were utilized to characterize the structure and luminescence properties of as-synthesized phosphors. The optimized phosphors Ba{sub 3}Y{sub 0.95}(PO{sub 4}){sub 3}:0.05Sm{sup 3+} present several excitation bands from 300 to 500 nm, and exhibit intense reddish orange-emitting properties. The energy transfer type between Sm{sup 3+} ions was confirmed as d–d interaction by using Van Uitert model. The chromatic properties of the typical sample Ba{sub 3}Y(PO{sub 4}){sub 3}:0.05Sm{sup 3+} phosphor have been found to have chromaticity coordinates of (0.583, 0.405),more » which are located in reddish orange region under the excitation of 401 nm. These results indicated that Ba{sub 3}Y(PO{sub 4}){sub 3}:Sm{sup 3+} phosphors have potential applications in the field of lighting and display due to their effective excitation in the near-ultraviolet range. - Graphical abstract: The color coordinates for 5 mol% Sm{sup 3+} doped Ba{sub 3}Y(PO{sub 4}){sub 3} phosphor were calculated to be (0.583, 0.405), which are located in reddish orange region under the excitation of 401 nm. The peaks of Ba{sub 3}Y{sub 0.95}(PO{sub 4}){sub 3}:0.05Sm{sup 3+} phosphor with the highest emission intensity at 600 nm are broader than those of Y{sub 2}O{sub 3}:Eu{sup 3+} and Y{sub 2}O{sub 2}S:Eu{sup 3+} phosphors. All these characteristics suggest that Ba{sub 3}Y(PO{sub 4}){sub 3}:Sm{sup 3+} phosphors are suitable for near-UV (370–410 nm) excitation and can be applicable to near UV-based WLEDs. ▪ - Highlights: • Different concentration Sm{sup 3+}-doped Ba{sub 3}Y(PO{sub 4}){sub 3} phosphors were fabricated by solid state method. • The optimized phosphors present the several excitation bands from 300 to 500 nm. • The Ba{sub 3}Y(PO{sub 4}){sub 3}:Sm{sup 3+} shows bright reddish

  6. Effects of crystalline electronic field and onsite interorbital interaction in Yb-based quasicrystal and approximant crystal.

    PubMed

    Watanabe, Shinji; Miyake, Kazumasa

    2018-05-10

    To get an insight into a new type of quantum critical phenomena recently discovered in the quasicrystal Yb 15 Al 34 Au 51 and approximant crystal (AC) Yb 14 Al 35 Au 51 under pressure, we discuss the property of the crystalline electronic field (CEF) at Yb in the AC and show that uneven CEF levels at each Yb site can appear because of the Al/Au mixed sites. Then we construct the minimal model for the electronic state on the AC by introducing the onsite Coulomb repulsion between the 4f and 5d orbitals at Yb. Numerical calculations for the ground state shows that the lattice constant dependence of the Yb valence well explains the recent measurement done by systematic substitution of elements of Al and Au in the quasicrystal and AC, where the quasicrystal Yb 15 Al 34 Au 51 is just located at the point from where the Yb-valence starts to change drastically. Our calculation convincingly demonstrates that this is indeed the evidence that this material is just located at the quantum critical point of the Yb-valence transition.

  7. Effects of crystalline electronic field and onsite interorbital interaction in Yb-based quasicrystal and approximant crystal

    NASA Astrophysics Data System (ADS)

    Watanabe, Shinji; Miyake, Kazumasa

    2018-05-01

    To get an insight into a new type of quantum critical phenomena recently discovered in the quasicrystal Yb15Al34Au51 and approximant crystal (AC) Yb14Al35Au51 under pressure, we discuss the property of the crystalline electronic field (CEF) at Yb in the AC and show that uneven CEF levels at each Yb site can appear because of the Al/Au mixed sites. Then we construct the minimal model for the electronic state on the AC by introducing the onsite Coulomb repulsion between the 4f and 5d orbitals at Yb. Numerical calculations for the ground state shows that the lattice constant dependence of the Yb valence well explains the recent measurement done by systematic substitution of elements of Al and Au in the quasicrystal and AC, where the quasicrystal Yb15Al34Au51 is just located at the point from where the Yb-valence starts to change drastically. Our calculation convincingly demonstrates that this is indeed the evidence that this material is just located at the quantum critical point of the Yb-valence transition.

  8. Geochemical associations between fluorite mineralization and A-type shoshonitic magmatism in the Keban-Elazig area, East Anatolia, Turkey

    NASA Astrophysics Data System (ADS)

    Akgul, Bunyamin

    2015-11-01

    Keban fluorite mineralizations are closely related Coniacian-Campanian subvolcanics intruded into Permian-Triassic Keban metamorphites; this event caused pyrometasomatic, porphyry, and vein-type Pb-Zn-Ag, Cu, W, and Pb-Zn-Ag-Mo-F mineralizations. These rocks are syenitic and syenomonzonitic in composition and have high Al2O3, alkali (Na2O + K2O), FeO*/MgO, Zr, Nb, Ta, Ga, Rb, Y, and rare earth element (REE) contents. They are A-type, metaluminous, and all fall in the shoshonitic series field in K2O vs SiO2 and Th/Yb vs Ta/Yb diagrams. The trace element contents and discriminations indicate that the Keban syenitoids were derived from lithospheric mantle metasomatized by oceanic-crust/sediment fluids. The metal and halogen contents of the Keban mineralizations apparently originated from metasomatized mantle and were transported to the crust by syenitoid magmas. Clear resemblances in chondrite-normalized REE patterns, LREE-HREE partionation, and high LILE contents of the magmatics and fluorites indicate a close kinship between the syenitoids and fluorite mineralizations. The HFSE contents of the fluorites are lower than those of the magmatics, as HFSEs are not soluble in aqueous fluids. The fluorites are products of early-phase alkali magmatism (LREE > HREE). The high contents of Rb, Sr, and Ba of fluorites are inherited from the magma, which also has very high contents of these elements. In Sc-∑REE, (La/Yb)n-(Eu/Eu*)n and (Tb/La)n-(Tb/Ca)n diagrams, Keban fluorites fall into distinct areas from Akcakisla-Akdagmadeni and Celikhan-Adiyaman fluorites.

  9. Ceramic oxyanion emitter

    DOEpatents

    Delmore, J.E.; Appelhans, A.D.; Peterson, E.S.

    1996-04-09

    A rare earth oxide matrix (composition of matter) is formed which emits (upon heating) heavy metal oxide anions (oxyanions) into a gas phase, wherein the anions are emitted with high intensity, and wherein longevity of life of the composition of matter is retained. The matter is formed by blending a major component of a rare earth oxide, europium oxide (Eu{sub 2}O{sub 3}) or ytterbium oxide (Yb{sub 2}O{sub 3}), with a minor component of a barium (Ba), calcium (Ca) or strontium (Sr) salt of a heavy metal oxyanion. Heavy anions are emitted upon heating the composition of matter to a predetermined temperature of about 800 C.

  10. Determination of 30 elements in coal and fly ash by thermal and epithermal neutron-activation analysis

    USGS Publications Warehouse

    Rowe, J.J.; Steinnes, E.

    1977-01-01

    Thirty elements are determined in coal and fly ash by instrumental neutron-activation analysis using both thermal and epithermal irradiation. Gamma-ray spectra were recorded 7 and 20 days after the irradiations. The procedure is applicable to the routine analysis of coals and fly ash. Epithermal irradiation was found preferable for the determination of Ni, Zn, As, Se, Br, Rb, Sr, Mo, Sb, Cs, Ba, Sm, Tb, Hf, Ta, W, Th and U, whereas thermal irradiation was best for Sc, Cr, Fe, Co, La, Ce, Nd, Eu, Yb and Lu. Results for SRM 1632 (coal) and SRM 1633 (fly ash) agree with those of other investigators. ?? 1977.

  11. Local structure investigation of Ga and Yb dopants in Co4Sb12 skutterudites

    NASA Astrophysics Data System (ADS)

    Hu, Yanyun; Chen, Ning; Clancy, J. P.; Salvador, James R.; Kim, Chang-Yong; Shi, Xiaoya; Li, Qiang; Kim, Young-June

    2017-12-01

    We report comprehensive x-ray absorption spectroscopy studies at both the Ga K edge and Yb L2 edge to elucidate the local structure of Ga and Yb dopants in YbxGayCo4Sb12 . Our extended x-ray absorption fine structure (EXAFS) data confirm that Ga atoms occupy two crystallographic sites: one is the 24 g site replacing Sb, and the other is the 2 a site in the off-center void position. We find that the occupancy ratio of these two sites varies significantly as a function of the filling fraction of additional Yb, which exclusively occupies the 2 a on-center site. At low concentrations of Yb, Ga24 g and Ga2 a dopants coexist and they form a charge-compensated compound defect proposed by Qiu et al. [Adv. Funct. Mater. 23, 3194 (2013), 10.1002/adfm.201202571]. The Ga24 g occupancy increases gradually with increasing Yb concentration, and almost all Ga occupies the 24 g site for the highest Yb concentration studied (x =0.4 ). In addition to the local structural evidence provided by our EXAFS data, we also present x-ray absorption near-edge structure (XANES) spectra, which show a small Ga K -edge energy shift as a function of Yb concentration consistent with the change from predominantly Ga2 a to Ga24 g states. Our result suggests that the increased solubility of Yb in Yb-Ga co-doped Co4Sb12 skutterudites is due to the increased Ga24 g electron acceptor, and thus provides an important strategy to optimize the carrier concentration in partially filled skutterudites.

  12. Microscopic analysis of shape transition in neutron-deficient Yb isotopes

    NASA Astrophysics Data System (ADS)

    Fu, Y.; Tong, H.; Wang, X. F.; Wang, H.; Wang, D. Q.; Wang, X. Y.; Yao, J. M.

    2018-01-01

    The development of nuclear collectivity in even-even Yb-170152 is studied with three types of mean-field calculations: the nonrelativistic Hartree-Fock plus BCS calculation using the Skyrme SLy4 force plus a density-dependent δ pairing force and the relativistic mean-field calculation using a point-coupling energy functional supplemented with either a density-independent δ pairing force or a separable pairing force. The low-lying states are obtained by solving a five-dimensional collective Hamiltonian with parameters determined from the three mean-field solutions. The energy surfaces, excitation energies, electric multiple transition strengths, and differential isotope shifts are presented in comparison with available data. Our results show that different treatments of pairing correlations have a significant influence on the speed of developing collectivity as the increase of neutron number. All the calculations demonstrate the important role of dynamic shape-mixing effects in resolving the puzzle in the dramatic increase of charge radius from 152Yb to 154Yb and the role of triaxiality in Yb 160 ,162 ,164 .

  13. Yb:YAG ceramic-based laser driver for Inertial Fusion Energy (IFE)

    NASA Astrophysics Data System (ADS)

    Vetrovec, John; Copeland, Drew A.; Litt, Amardeep S.

    2016-03-01

    We report on a new class of laser amplifiers for inertial confinement fusion (ICF) drivers based on a Yb:YAG ceramic disk in an edge-pumped configuration and cooled by a high-velocity gas flow. The Yb lasant offers very high efficiency and low waste heat. The ceramic host material has a thermal conductivity nearly 15-times higher than the traditionally used glass and it is producible in sizes suitable for a typical 10- to 20-kJ driver beam line. The combination of high lasant efficiency, low waste heat, edge-pumping, and excellent thermal conductivity of the host, enable operation at 10 to 20 Hz at over 20% wall plug efficiency while being comparably smaller and less costly than recently considered face-pumped alternative drivers using Nd:glass, Yb:S-FAP, and cryogenic Yb:YAG. Scalability of the laser driver over a broad range of sizes is presented.

  14. Preparation and laser properties of Yb3+-doped microstructure fiber based on hydrolysis-melting technique

    NASA Astrophysics Data System (ADS)

    Wang, Chao

    2017-01-01

    The Yb3+-doped silica glass was prepared by the SiCl4 hydrolysis doping and powder melting technology based on high frequency plasma. The absorption and emission characteristics of the Yb3+-doped silica glass are studied at room temperature. The integrated absorption cross section, stimulated emission cross section and fluorescence lifetime are calculated to be 8.56×104 pm3, 1.39 pm2 and 0.56 ms, respectively. The Yb3+-doped microstructure fiber (MSF) was also fabricated by using the Yb3+-doped silica glass as fiber core. What's more, the laser properties of the Yb3+-doped MSF are studied.

  15. Polyamorphism in Yb-based metallic glass induced by pressure

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Li, Liangliang; Luo, Qiang; Li, Renfeng

    2017-04-25

    The Yb 62.5Zn 15Mg 17.5Cu 5 metallic glass is investigated using synchrotron x-ray total scattering method up to 38.4 GPa. The polyamorphic transformation from low density to high density with a transition region between 14.1 and 25.2 GPa is observed, accompanying with a volume collapse reflected by a discontinuousness of isothermal bulk modulus. This collapse is caused by that distortional icosahedron short range order precedes to perfect icosahedron, which might link to Yb 4f electron delocalization upon compression, and match the result of in situ electrical resistance measurement under high pressure conditions. Furthermore, this discovery in Yb-based metallic glass, combinedmore » with the previous reports on other metallic glass systems, demonstrates that pressure induced polyamorphism is the general behavior for typical lanthanide based metallic glasses.« less

  16. Formation, optical properties, and electronic structure of thin Yb silicide films on Si(111)

    NASA Astrophysics Data System (ADS)

    Galkin, N. G.; Maslov, A. M.; Polyarnyi, V. O.

    2005-06-01

    Continuous very thin (2.5-3.0 nm) and thin (16-18 nm) ytterbium suicide films with some pinhole density (3×107- 1×108 cm-2) have been formed on Si(111) by solid phase epitaxy (SPE) and reactive deposition epitaxy (RDE) growth methods on templates. The stoichiometric ytterbium suicide (YbSi2) formation has shown in SPE grown films by AES and EELS data. Very thin Yb suicide films grown by RDE method had the silicon enrichment in YbSi2 suicide composition. The analysis of LEED data and AFM imaging has shown that ytterbium suicide films had non-oriented blocks with the polycrystalline structure. The analysis of scanning region length dependencies of the root mean square roughness deviation (σR(L)) for grown suicide films has shown that the formation of ytterbium suicide in SPE and RDE growth methods is determined by the surface diffusion of Yb atoms during the three-dimensional growth process. Optical functions (n, k, α, ɛ1, ɛ2, Im ɛ1-1, neff, ɛeff) of ytterbium silicide films grown on Si(1 1 1) have been calculated from transmittance and reflectance spectra in the energy range of 0.1-6.2 eV. Two nearly discrete absorption bands have been observed in the electronic structure of Yb silicide films with different composition, which connected with interband transitions on divalent and trivalent Yb states. It was established that the reflection coefficient minimum in R-spectra at energies higher 4.2 eV corresponds to the state density minimum in Yb suicide between divalent and trivalent Yb states. It was shown from optical data that Yb silicide films have the semi-metallic properties with low state densities at energies less 0.4 eV and high state densities at 0.5-2.5 eV.

  17. New insight into the shape coexistence and shape evolution of {sup 157}Yb

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Xu, C.; Hua, H.; Li, X. Q.

    2011-01-15

    High-spin states in {sup 157}Yb have been populated in the {sup 144}Sm({sup 16}O,3n){sup 157}Yb fusion-evaporation reaction at a beam energy of 85 MeV. Two rotational bands built on the {nu}f{sub 7/2} and {nu}h{sub 9/2} intrinsic states, respectively, have been established for the first time. The newly observed {nu}f{sub 7/2} band and previously known {nu}i{sub 13/2} band in {sup 157}Yb are discussed in terms of total Routhian surface methods and compared with the structures in the neighboring N = 87 isotones. The structural characters observed in {sup 157}Yb provide evidence for shape coexistence of three distinct shapes: prolate, triaxial, and oblate.more » At higher spins, both the {nu}f{sub 7/2} band and {nu}i{sub 13/2} band in {sup 157}Yb undergo a shape evolution with sizable alignments occurring.« less

  18. Chemistry of amphiboles and clinopyroxenes from Euganean (NE Italy) cumulitic enclaves: implications for the genesis of melts in an extensional setting

    NASA Astrophysics Data System (ADS)

    Bartoli, O.; Meli, S.; Sassi, R.; Magaraci, D.

    2009-04-01

    The magmatism of the Euganean Volcanic District (Veneto Volcanic Province, VVP) developed in the last phases of the Alpine orogenesis; the geochemical and geophysical data are consistent with an extensional geodynamic context (Milani et al., 1999). Cumulitic gabbroic enclaves occur within the Euganean trachytes, and Bartoli et al. (2008) pointed to their cogenetic origin with the Euganean host lavas. Sr isotopic data suggest that these cumulates derived from uncontaminated mantle-derived liquids. We analysed both cumulus and intercumulus amphiboles and clinopyroxenes by electron microprobe and LA-ICP-MS. The cumulus-intercumulus Cpx are diopsides and augites. The Mg#Cpx varies in a wide range (Mg#cumulus-Cpx= 0.74-0.84 and Mg#intercumulus-Cpx= 0.67-0.68). They show a MREE enrichment relative to LREE and HREE (LaN/SmN= 0.46-0.68 and TbN/YbN= 2.18-4.77). No significant Eu anomaly (Eu/Eu* = 0.78-1.23) was observed. On a chondrite-normalized spiderdiagram Cpx exhibits significant Pb and Co negative anomalies, and less evident negative anomalies for Sr and Zr. La, Sm and HREE increase, whereas Ba, Ti, Li and V decrease from core to rim. These Cpx exhibit high Cr contents (701-2958 ppm). Moreover, they display trace element differences when compared to Cpx from MORB gabbros. We analyzed also amphiboles: pargasites, edenites and kaersutites. In the cumulus Amph Mg# varies in the range 0.60-0.69, whereas in the intercumulus assemblage from 0.57 to 0.63. The high K2O and TiO2 contents are distinct from that of amphiboles in MORB gabbros. LREE are enriched relative to HREE (LaN/YbN = 5.07-7.56). Moreover, TbN/YbN = 2.50-4.02 indicates a HREE depletion relative to MREE. REE patterns lack a significant Eu anomaly (Eu/Eu* = 1.06-1.19). From core to rim Th and U decrease in cumulus crystals, but they increase in the intercumulus Amph. Ba (258-282 ppm) is enriched relative to other LILE and Nb-Ta are enriched relative to LREE. Cr varies in the range 423-594 ppm. The similar REE

  19. Novel yellow-emitting Sr8MgLn(PO4)7:Eu2+ (Ln=Y, La) phosphors for applications in white LEDs with excellent color rendering index.

    PubMed

    Huang, Chien-Hao; Chen, Teng-Ming

    2011-06-20

    Eu(2+)-activated Sr(8)MgY(PO(4))(7) and Sr(8)MgLa(PO(4))(7) yellow-emitting phosphors were successfully synthesized by solid-state reactions for applications in excellent color rendering index white light-emitting diodes (LEDs). The excitation and reflectance spectra of these phosphors show broad band excitation and absorption in the 250-450 nm near-ultraviolet region, which is ascribed to the 4f(7) → 4f(6)5d(1) transitions of Eu(2+). Therefore, these phosphors meet the application requirements for near-UV LED chips. Upon excitation at 400 nm, the Sr(8)MgY(PO(4))(7):Eu(2+) and Sr(8)MgLa(PO(4))(7):Eu(2+) phosphors exhibit strong yellow emissions centered at 518, 610, and 611 nm with better thermal stability than (Ba,Sr)(2)SiO(4) (570 nm) commodity phosphors. The composition-optimized concentrations of Eu(2+) in Sr(8)MgLa(PO(4))(7):Eu(2+) and Sr(8)MgY(PO(4))(7):Eu(2+) phosphors were determined to be 0.01 and 0.03 mol, respectively. A warm white-light near-UV LED was fabricated using a near-UV 400 nm chip pumped by a phosphor blend of blue-emitting BaMgAl(10)O(17):Eu(2+) and yellow-emitting Sr(8)MgY(PO(4))(7):0.01Eu(2+) or Sr(8)MgLa(PO(4))(7):0.03Eu(2+), driven by a 350 mA current. The Sr(8)MgY(PO(4))(7):0.01Eu(2+) and Sr(8)MgLa(PO(4))(7):0.03Eu(2+) containing LEDs produced a white light with Commission International de I'Eclairage (CIE) chromaticity coordinates of (0.348, 0.357) and (0.365, 0.328), warm correlated color temperatures of 4705 and 4100 K, and excellent color rendering indices of 95.375 and 91.75, respectively. © 2011 American Chemical Society

  20. Laser and spectroscopic properties of Sr[sub 5](PO[sub 4])[sub 3]F:Yb

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    DeLoach, L.D.; Payne, S.A.; Smith, L.K.

    Sr[sub 5](PO[sub 4])[sub 3]F (S-FAP) has been investigated as a new Yb-doped laser crystal belonging to the apatite structural family. The spectroscopy of the Yb[sup 3+] ion and the laser properties of the medium have been investigated. The maximum absorption cross section of Yb in S-FAP is 8.6 [times] 10[sup [minus]20] cm[sup 2], and the maximum emission cross section is 7.3 [times] 10[sup [minus]20] cm[sup 2]. The measured emission lifetime of Yb[sup 3+] is 1.26 ms. An Yb:S-FAP laser has been demonstrated with a Ti:sapphire laser pump operating at 899 nm. The Yb:S-FAP laser was measured to have slope efficienciesmore » as high as 71%. The spectroscopy and laser studies are reported, as well as certain thermal, mechanical, and optical properties.« less

  1. Enhanced broadband near-infrared luminescence from transparent Yb3+/Ni2+ codoped silicate glass ceramics.

    PubMed

    Wu, Botao; Zhou, Shifeng; Ruan, Jian; Qiao, Yanbo; Chen, Danping; Zhu, Congshan; Qiu, Jianrong

    2008-02-04

    The near-infrared emission intensity of Ni(2+) in Yb(3+)/Ni(2+) codoped transparent MgO-Al(2)O(3)-Ga(2)O(3)-SiO(2)-TiO(2) glass ceramics could be enhanced up to 4.4 times via energy transfer from Yb(3+) to Ni(2+) in nanocrystals. The best Yb(2)O(3) concentration was about 1.00 mol%. For the Yb(3+)/Ni(2+) codoped glass ceramic with 1.00 mol% Yb(2)O(3), a broadband near-infrared emission centered at 1265 nm with full width at half maximum of about 300 nm and lifetime of about 220 mus was observed. The energy transfer mechanism was also discussed.

  2. A buetschliite-type rare-earth borate, KBaY(BO 3) 2

    NASA Astrophysics Data System (ADS)

    Gao, Jianhua; Song, Limei; Hu, Xiaoyun; Zhang, Dekai

    2011-01-01

    The title compound was firstly synthesized by solid state reaction and its single crystals were successfully obtained using a selected flux. It is isotypic with the mineral buetschliite, K 2Ca(CO 3) 2, and crystallizes in the trigonal space group R-3m with a = 5.4526(12) Å, c = 17.781(8) Å, Z = 3. In the structure, Ba and K atoms are disordered on a same site in the proportion of 0.492(4):0.508(4). The fundamental building units are YO 6 octahedra and BO 3 triangles. The structure consists of [YB 2O 6] ∞ double layers constructed by corner-sharing YO 6 and BO 3 groups. Ba/K atoms occupy the spaces between these two layers and play the role of bridges. In addition, the luminescence properties of Eu 3+ doped KBaY(BO 3) 2 were also studied.

  3. ‘Obligate’ anaerobic Salmonella strain YB1 suppresses liver tumor growth and metastasis in nude mice

    PubMed Central

    Li, Chang-Xian; Yu, Bin; Shi, Lei; Geng, Wei; Lin, Qiu-Bin; Ling, Chang-Chun; Yang, Mei; Ng, Kevin T. P.; Huang, Jian-Dong; Man, Kwan

    2017-01-01

    The antitumor properties of bacteria have been demonstrated over the past decades. However, the efficacy is limited and unclear. Furthermore, systemic infection remains a serious concern in bacteria treatment. In this study, the effect of YB1, a rationally designed ‘obligate’ anaerobic Salmonella typhimurium strain, on liver tumor growth and metastasis in a nude mouse orthotopic liver tumor model was investigated. The orthotopic liver tumor model was established in nude mice using the hepatocellular carcinoma cell line MHCC-97L. Two weeks after orthotopic liver tumor implantation, YB1, SL7207 and saline were respectively administered through the tail vein of the mice. Longitudinal monitoring of tumor growth and metastasis was performed using Xenogen IVIS, and direct measurements of tumor volume were taken 3 weeks after treatment. In vitro, MHCC-97L and PLC cells were incubated with YB1 or SL7207 under anaerobic conditions. YB1 was observed to invade tumor cells and induce tumor cell apoptosis and death. The results revealed that all mice in the YB1 group were alive 3 weeks after YB1 injection while all mice in the SL7207 group died within 11 days of the SL7207 injection. The body weight decreased by ~9% on day 1 after YB1 injection and but subsequently recovered. Liver tumor growth and metastases were significantly inhibited following YB1 treatment. By contrast to the control group, a large number of Gr1-positive cells were detected on days 1 to 21 following YB1 treatment. Furthermore, YB1 also effectively invaded tumor cells and induced tumor cell apoptosis and death. In conclusion, YB1 suppressed liver tumor growth and metastasis in a nude mice liver tumor model. The potential mechanism may be through enhancing innate immune response and inducing tumor cell apoptosis and cell death. PMID:28123538

  4. Synthesis and photoluminescence properties of a cyan-emitting phosphor Ca3(PO4)2:Eu2+ for white light-emitting diodes

    NASA Astrophysics Data System (ADS)

    Zhou, Wenli; Han, Jin; Zhang, Xuejie; Qiu, Zhongxian; Xie, Qingji; Liang, Hongbin; Lian, Shixun; Wang, Jing

    2015-01-01

    In this paper, a cyan-emitting phosphor Ca3(PO4)2:Eu2+ (TCP:Eu2+) was synthesized and evaluated as a candidate for white light emitting diodes (WLEDs). This phosphor shows strong and broad absorption in 250-450 nm region, but the emission spectrum is prominent at around 480 nm. The emission intensity of the TCP:Eu2+ was found to be 60% and 82% of that of the commercial BaMgAl10O17:Eu2+ (BAM) under excitation at 340 nm and 370 nm, respectively. Upon excitation at 370 nm, the absolute internal and external quantum efficiencies of the Ca3(PO4)2:1.5%Eu2+ are 60% and 42%, respectively. Moreover, a white LED lamp was fabricated by coating TCP:Eu2+ with a blue-emitting BAM and a red-emitting CaAlSiN3:Eu2+ on a near-ultraviolet (375 nm) LED chip, driven by a 350 mA forward bias current, and it produces an intense white light with a color rendering index of 75.

  5. Quantum critical scaling in beta-YbAlB4 and theoretical implications

    NASA Astrophysics Data System (ADS)

    Nevidomskyy, Andriy

    2012-02-01

    Emergent phenomena in quantum materials are subject of intense experimental and theoretical research at present. A wonderful example thereof are the sister phases of YbAlB4 - a newly discovered heavy fermion material [1]. While one phase (α-YbAlB4) is a heavy Fermi liquid, its sibling β-YbAlB4 is quantum critical, supporting an unconventional superconductivity with a tiny transition temperature of ˜80 mK. Latest experiments [2] uncover the quantum critical T/B-scaling in β-YbAlB4 and prove that superconductivity emerges from a strange metal governed by an extremely fragile quantum criticality, which apparently occurs at zero field, without any external tuning. Here, we will present a theoretical perspective on the quantum critical scaling in β-YbAlB4 and will show that the critical exponents can be derived from the nodal structure of the hybridization matrix between Yb f-band and the conduction electrons. It follows that the free energy at low temperatures can be written in a scaling form F[(kBT)^2 + (gμBB)^2]^3/4, which predicts the divergent Sommerfeld coefficient γ and quasi-particle effective mass as B->0: γ˜m^*/m B-1/2. This is indeed observed in the experiment [1,2], which places a tiny upper bound on the critical magnetic field Bc<0.2 mT. We will discuss theoritical implications of this fragile intrinsic quantum criticality in β-YbAlB4 and discuss the possibility of a quantum critical phase, rather than a quantum critical point, in this material. [1] S. Nakatsuji et al., Nature Physics 4, 603 (2008). [2] Y. Matsumoto, S. Nakatsuji, K. Kuga, Y. Karaki, Y. Shimura, T. Sakakibara, A. H. Nevidomskyy, and P. Coleman, Science 331, 316 (2011).

  6. Semiconductor-insulator transition in a YbB6 nanowire with boron vacancy

    NASA Astrophysics Data System (ADS)

    Han, Wei; Wang, Zhen; Li, Qidong; Lian, Xin; Liu, Xudong; Fan, Qinghua; Zhao, Yanming

    2018-06-01

    In this paper, we report the study of transport and magnetic properties of ytterbium hexaboride (YbB6) nanowires grown by a low trigger-temperature (200-240 °C) solid state method. The temperature dependence of resistivity shows that the YbB6 nanowire undergoes a semiconductor-insulator transition (SIT) below 20 K with an activation energy ΔE of 1 meV. The value of ρ at 2 K reaches 49 times the value of ρ at 300 K (ρ2 K/ρ300 K = 49). The observed non-saturating magnetoresistance (MR) has a linear relationship with B2. The anomalous electronic transport in the YbB6 nanowire can be explained by the mixed valence of Yb ions due to the boron deficiency supporting by the X-ray photoelectron spectroscopy (XPS) and paramagnetic magnetization.

  7. Y-box-binding protein-1 (YB-1) promotes cell proliferation, adhesion and drug resistance in diffuse large B-cell lymphoma

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Miao, Xiaobing; Wu, Yaxun; Wang, Yuchan

    YB-1 is a multifunctional protein, which has been shown to correlate with resistance to treatment of various tumor types. This study investigated the expression and biologic function of YB-1 in diffuse large B-cell lymphoma (DLBCL). Immunohistochemical analysis showed that the expression statuses of YB-1 and pYB-1{sup S102} were reversely correlated with the clinical outcomes of DLBCL patients. In addition, we found that YB-1 could promote the proliferation of DLBCL cells by accelerating the G1/S transition. Ectopic expression of YB-1 could markedly increase the expression of cell cycle regulators cyclin D1 and cyclin E. Furthermore, we found that adhesion of DLBCLmore » cells to fibronectin (FN) could increase YB-1 phosphorylation at Ser102 and pYB-1{sup S102} nuclear translocation. In addition, overexpression of YB-1 could increase the adhesion of DLBCL cells to FN. Intriguingly, we found that YB-1 overexpression could confer drug resistance through cell-adhesion dependent and independent mechanisms in DLBCL. Silencing of YB-1 could sensitize DLBCL cells to mitoxantrone and overcome cell adhesion-mediated drug resistance (CAM-DR) phenotype in an AKT-dependent manner. - Highlights: • The expression statuses of YB-1 and pYB-1{sup S102} are reversely correlated with outcomes of DLBCL patients. • YB-1 promotes cell proliferation by accelerating G1/S transition in DLBCL. • YB-1 confers drug resistance to mitoxantrone in DLBCL.« less

  8. Microstructure investigations of Yb- and Bi-doped Mg{sub 2}Si prepared from metal hydrides for thermoelectric applications

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Janka, Oliver; Zaikina, Julia V.; Bux, Sabah K.

    2017-01-15

    Within the field of thermoelectric materials for energy conversion magnesium silicide, Mg{sub 2}Si, is an outstanding candidate due to its low density, abundant constituents and low toxicity. However electronic and thermal tuning of the material is a required necessity to improve its Figure of Merit, zT. Doping of Yb via reactive YbH{sub 2} into the structure is performed with the goal of reducing the thermal conductivity. Hydrogen is released as a by-product at high temperatures allowing for facile incorporation of Yb into the structure. We report on the properties of Yb- and Bi-doped Mg{sub 2}Si prepared with MgH{sub 2} andmore » YbH{sub 2} with the focus on the synthetic conditions, and samples’ microstructure, investigated by various electron microscopy techniques. Yb is found in the form of both Yb{sub 3}Si{sub 5} inclusions and Yb dopant segregated at the grain boundary substituting for Mg. The addition of 1 at% Yb concentration reduced the thermal conductivity, providing a value of 30 mW/cm K at 800 K. In order to adjust carrier concentration, the sample is additionally doped with Bi. The impact of the microstructure on the transport properties of the obtained material is studied. Idealy, the reduction of the thermal conductivity is achieved by doping with Yb and the electronic transport is adjusted by doping with Bi. Large grain microstructure facilitates the electronic transport. However, the synthetic conditions that provide the optimized microstructure for electrical transport do not facilitate the additional Yb dopant incorporation. Therefore, the Yb and Bi containing sample with the optimized microstructure provides a zT=0.46 at 800 K. - Graphical abstract: 1% or less addition of YbH{sub 2} to Mg{sub 2}Si significantly reduces the thermal conductivity of the material. Yb replaces some Mg in Mg{sub 2}Si and the remainder is distributed as Yb{sub 3}Sb{sub 5} in the Yb-doped Mg{sub 2}Si matrix. Correlation between the observed grain size and transport

  9. Microchip laser based on Yb:YAG/V:YAG monolith crystal

    NASA Astrophysics Data System (ADS)

    Nejezchleb, Karel; Šulc, Jan; Jelínková, Helena; Škoda, Václav

    2016-03-01

    V:YAG crystal was investigated as a passive Q-switch of longitudinally diode-pumped microchip laser, emitting radiation at wavelength 1030.5 nm. This laser was based on diffusion bonded monolith crystal (diameter 3 mm) which combines in one piece an active laser part (Yb:YAG crystal, 10 at.% Yb/Y, 3 mm long) and saturable absorber (V:YAG crystal, 2 mm long, initial transmission 86 % @ 1031 nm). The microchip resonator consisted of dielectric mirrors directly deposited on the monolith surfaces (pump mirror HT @ 968 nm and HR @ 1031 nm on Yb:YAG part, output coupler with reflection 55 % @ 1031 nm on the V:YAG part). For longitudinal CW pumping of Yb:YAG part, a fibre coupled (core diameter 100 μm, NA = 0.22, emission @ 968 nm) laser diode was used. The laser threshold was 3.8W. The laser slope efficiency for output mean in respect to incident pumping was 16 %. The linearly polarized generated transversal intensity beam profile was close to the fundamental Gaussian mode. The generated pulse length, stable and mostly independent on pumping power, was equal to 1.3 ns (FWHM). The single pulse energy was increasing with the pumping power and for the maximum pumping 9.7W it was 78 μJ which corresponds to the pulse peak-power 56 kW. The maximum Yb:YAG/V:YAG microchip laser mean output power of 1W was reached without observable thermal roll-over. The corresponding Q-switched pulses repetition rate was 13.1 kHz.

  10. Role of electron transfer in Ce{sup 3+} sensitized Yb{sup 3+} luminescence in borate glass

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Sontakke, Atul D., E-mail: sontakke.atul.55a@st.kyoto-u.ac.jp; Katayama, Yumiko; Zhuang, Yixi

    2015-01-07

    In a Ce{sup 3+}-Yb{sup 3+} system, two mechanisms are proposed so far namely, the quantum cutting mechanism and the electron transfer mechanism explaining Yb{sup 3+} infrared luminescence under Ce{sup 3+} excitation. Among them, the quantum cutting mechanism, where one Ce{sup 3+} photon (ultraviolet/blue) gives rise to two Yb{sup 3+} photons (near infrared) is widely sought for because of its huge potential in enhancing the solar cell efficiency. In present study on Ce{sup 3+}-Yb{sup 3+} codoped borate glasses, Ce{sup 3+} sensitized Yb{sup 3+} luminescence at ∼1 μm have been observed on Ce{sup 3+} 5d state excitation. However, the intensity of sensitized Yb{supmore » 3+} luminescence is found to be very weak compared to the strong quenching occurred in Ce{sup 3+} luminescence in Yb{sup 3+} codoped glasses. Moreover, the absolute luminescence quantum yield also showed a decreasing trend with Yb{sup 3+} codoping in the glasses. The overall behavior of the luminescence properties and the quantum yield is strongly contradicting with the quantum cutting phenomenon. The results are attributed to the energetically favorable electron transfer interactions followed by Ce{sup 3+}-Yb{sup 3+} ⇌ Ce{sup 4+}-Yb{sup 2+} inter-valence charge transfer and successfully explained using the absolute electron binding energies of dopant ions in the studied borate glass. Finally, an attempt has been presented to generalize the electron transfer mechanism among opposite oxidation/reduction property dopant ions using the vacuum referred electron binding energy (VRBE) scheme for lanthanide series.« less

  11. Synthesis and characterization of Nd3+: Yb3+ co-doped near infrared sensitive fluorapatite nanoparticles as a bioimaging probe

    NASA Astrophysics Data System (ADS)

    Karthi, S.; Kumar, G. A.; Sardar, D. K.; Santhosh, C.; Girija, E. K.

    2018-03-01

    Trivalent Nd and Yb co-doped rod shaped hexagonal phase fluorapatite (FAP) nanoparticles of length and width about 32 and 13 nm, respectively were prepared by hydrothermal method and investigated the ability for 980 nm emission via Nd3+ → Yb3+ energy transfer with the objective of utilizing them in biomedical imaging. Nd3+ → Yb3+ energy transfer in FAP was studied as a function of both Nd3+ and Yb3+ concentrations and found that when Yb3+ concentration was 10 mol% the FAP phase has partially turned in to YbPO4 phase. The Yb3+ emission intensity at 980 nm significantly increased up to 5 mol% Yb3+ doping and then reduced drastically for further increase in its concentration. Nd3+ →Yb3+ energy transfer rates were evaluated from the decay curves and found that a transfer rate of 71% for 2 mol% Nd3+ co-doped with 5 mol% Yb3+. The cytocompatibility test with fibroblast like cells using MTT assay revealed that the nanoparticles are compatible with the cells.

  12. Progress Toward an Neutral Yb Frequency Standard

    NASA Astrophysics Data System (ADS)

    Cramer, Claire; Hong, Tao; Nagourney, Warren; Fortson, Norval

    2004-05-01

    We report recent progress toward a direct observation of the ^1S_0^ -- ^3P0 clock transition at 578 nm in atomic Yb and review the experimental path to an optical frequency standard based on neutral Yb confined in a Stark-free optical lattice. Lamb-Dicke confinement in an optical lattice at the ``magic wavelength'' (λ _M) at which ground and excited state light shifts cancel will free the spectrum from Doppler and recoil shifts, providing an optimal environment for a clock consisting of an ensemble of cold, trapped atoms. In^171Yb the ^3P0 level has a hfs induced lifetime of 21 s. With this isotope in a Stark-free lattice at λ M ng 750 nm, perturbations to the clock energy levels can be held below the mHz level, providing an accuracy of a few parts in 10^18[1]. To observe the clock transition we use a shelving scheme that creates a leak in a MOT on the ^1S_0^ -- ^1P1 transition. A laser resonant with the clock transition drives atoms into the ^3P0 state, in which they can escape the MOT, leading to an observable decrease in MOT fluorescence. [1] S. Porsev and A. Derevianko, to be published in PRA

  13. Identification of parasitic losses in Yb:YLF and prospects for optical refrigeration down to 80K.

    PubMed

    Melgaard, Seth; Seletskiy, Denis; Polyak, Victor; Asmerom, Yemane; Sheik-Bahae, Mansoor

    2014-04-07

    Systematic study of Yb doping concentration in the Yb:YLF cryocoolers by means of optical and mass spectroscopies has identified iron ions as the main source of the background absorption. Parasitic absorption was observed to decrease with Yb doping, resulting in optical cooling of a 10% Yb:YLF sample to 114K ± 1K, with room temperature cooling power of 750 mW and calculated minimum achievable temperature of 93 K.

  14. Magnetocaloric behavior in ternary europium indides EuT 5In: Probing the design capability of first-principles-based methods on the multifaceted magnetic materials

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Bigun, Inna; Steinberg, Simon; Smetana, Volodymyr

    The most favorable structures and the types of magnetic ordering predicted from first-principles-based methods in a family of closely related transition-metal-rich indides EuT 5In (T = Cu, Ag, Au) are gauged against relevant experiments. The EuT5In compounds adopt a different structure for each different coinage metal—EuCu 5In ( hR42; Rmore » $$\\overline{3}$$m, a = 5.0933(7), c = 30.557(6) Å), EuAg 5In ( oP28; Pnma, a = 9.121(2), b = 5.645(1), c = 11.437(3) Å), and EuAu 5In ( tI14; I4/ mmm, a = 7.1740(3), c = 5.4425(3) Å)—and crystallize with the Sr 5Al 9, CeCu 6, and YbMo 2Al 4 structure types, respectively. EuCu 5In and EuAg 5In order antiferromagnetically at T N = 12 and 6 K, respectively, whereas EuAu 5In is ferromagnetic below T C = 13 K. EuCu 5In exhibits complex magnetism: after the initial drop at T N, the magnetization rises again below 8 K, and a weak metamagnetic-like transition occurs at 2 K in μ 0H = 1.8 T. The electronic heat capacity of EuCu 5In, γ = ~400 mJ/(mol K 2), points to strong electronic correlations. Spin-polarized densities of states suggest that the magnetic interactions in the three materials studied are supported via mixing 4 f and 5 d states of Eu. As a result, a chemical bonding analysis based on the Crystal Orbital Hamilton populations reveals the tendency to maximize overall bonding as a driving force to adopt a particular type of crystal structure.« less

  15. Magnetocaloric behavior in ternary europium indides EuT 5In: Probing the design capability of first-principles-based methods on the multifaceted magnetic materials

    DOE PAGES

    Bigun, Inna; Steinberg, Simon; Smetana, Volodymyr; ...

    2017-01-27

    The most favorable structures and the types of magnetic ordering predicted from first-principles-based methods in a family of closely related transition-metal-rich indides EuT 5In (T = Cu, Ag, Au) are gauged against relevant experiments. The EuT5In compounds adopt a different structure for each different coinage metal—EuCu 5In ( hR42; Rmore » $$\\overline{3}$$m, a = 5.0933(7), c = 30.557(6) Å), EuAg 5In ( oP28; Pnma, a = 9.121(2), b = 5.645(1), c = 11.437(3) Å), and EuAu 5In ( tI14; I4/ mmm, a = 7.1740(3), c = 5.4425(3) Å)—and crystallize with the Sr 5Al 9, CeCu 6, and YbMo 2Al 4 structure types, respectively. EuCu 5In and EuAg 5In order antiferromagnetically at T N = 12 and 6 K, respectively, whereas EuAu 5In is ferromagnetic below T C = 13 K. EuCu 5In exhibits complex magnetism: after the initial drop at T N, the magnetization rises again below 8 K, and a weak metamagnetic-like transition occurs at 2 K in μ 0H = 1.8 T. The electronic heat capacity of EuCu 5In, γ = ~400 mJ/(mol K 2), points to strong electronic correlations. Spin-polarized densities of states suggest that the magnetic interactions in the three materials studied are supported via mixing 4 f and 5 d states of Eu. As a result, a chemical bonding analysis based on the Crystal Orbital Hamilton populations reveals the tendency to maximize overall bonding as a driving force to adopt a particular type of crystal structure.« less

  16. The complexity of the CaF2:Yb system: evidence that CaF2:Yb2+ is not an impurity trapped exciton system

    NASA Astrophysics Data System (ADS)

    Mackeen, Cameron; Bridges, Frank; Kozina, Michael; Mehta, Apurva; Reid, M. F.; Wells, J.-P. R.; BarandiaráN, Zoila

    Fluorite crystal structures doped with rare-earth elements exhibit an anomalous redshifted luminescence upon UV excitation, generally attributed to the relaxation of impurity trapped excitons (ITE). We find that the intensity of this luminescence decreases as the total concentration of Yb 2+ increases in unexposed samples, which is in conflict with the currently accepted ITE model. Further, using x-ray absorption spectroscopy and UV-vis studies of CaF2:Yb, we find a large (but reversible) Yb valence reduction upon x-ray exposure at 200 K - from mostly 3+ to 2+. This valence reduction is stable for long time periods at low T < 50 K, but reverts to the initial state upon warming to 300 K. After reverting to the initial valence state of 3+ the anomalous luminescence does not reappear; only after annealing at 900 K do we again observe the anomalous emission below 150 K. To explore the mechanism at work, we employ extended x-ray fine-structure absorption spectroscopy (EXAFS) to probe local structure and its role in the anomalous luminescence. The x-ray and emission studies show that CaF2:Yb is not described by the ITE model; the data appear more consistent with an intervalence charge transfer (IVCT) model. It is likely that many similar ITE systems have also been misidentified.

  17. Treatment of Neuroblastoma with an Engineered “Obligate” Anaerobic Salmonella typhimurium Strain YB1

    PubMed Central

    Ning, Bo-Tao; Yu, Bin; Chan, Shing; Chan, Jian-liang; Huang, Jian-Dong; Chan, Godfrey Chi-Fung

    2017-01-01

    Purpose Neuroblastoma is an embryonic solid tumor derived from the progenitors of the sympathetic nervous system. More than half of the patients developed metastatic disease at the time of initial diagnosis and had poor outcome with current therapeutic approaches. In recent years, some obligate and facultative anaerobic bacteria were reported to target the hypoxic and necrotic region of solid tumor models and caused tumor regression. We recently successfully constructed an “obligate” anaerobic Salmonella strain YB1 that was applied in breast cancer nude mice model by us. Here, we report the application of YB1 in neuroblastoma treatment. Methods The anti-cancer effect and side-effects of YB1 was examined in both in vitro and in vivo experiment. Previous established orthotopic neuroblastoma SCID/beige murine model using SK-NLP/luciferase cell line was adopted. Results In vitro, YB1 induced apoptosis for up to 31.4% of the neuroblastoma cells under anaerobic condition, three times more than that under aerobic condition (10.9%). The expression of both Toll like Receptor 4 and 5 (TLR4 and TLR5) in cancer cells were significantly up-regulated (p<0.05, p<0.01 respectively) after the treatment of YB1 under anaerobic condition. In mouse model, YB1 preferentially accumulated inside the core of the tumors, rather than in normal tissues as our previous reported. This is suggestive of the hypoxic nature of tumor core. Tumor growth was significantly retarded in YB1 treatment group (n=6, P<0.01). Furthermore, there was no long-term organ damage noted in all the organs examined including heart, lung, liver, spleen and brain in the YB1 treated mice. Conclusion The genetic modified Salmonella strain YB1 is a promising anti-tumor strategy against the tumor bulk for neuroblastoma. Future study can be extended to other common cancer types to verify the relative efficacy on different neoplastic cells. PMID:28775780

  18. Interferon-gamma interferes with transforming growth factor-beta signaling through direct interaction of YB-1 with Smad3.

    PubMed

    Higashi, Kiyoshi; Inagaki, Yutaka; Fujimori, Ko; Nakao, Atsuhito; Kaneko, Hideo; Nakatsuka, Iwao

    2003-10-31

    Transforming growth factor-beta (TGF-beta) and interferon-gamma (IFN-gamma) exert antagonistic effects on collagen synthesis in human dermal fibroblasts. We have recently shown that Y box-binding protein YB-1 mediates the inhibitory effects of IFN-gamma on alpha2(I) procollagen gene (COL1A2) transcription through the IFN-gamma response element located between -161 and -150. Here we report that YB-1 counter-represses TGF-beta-stimulated COL1A2 transcription by interfering with Smad3 bound to the upstream sequence around -265 and subsequently by interrupting the Smad3-p300 interaction. Western blot and immunofluorescence analyses using inhibitors for Janus kinases or casein kinase II suggested that the casein kinase II-dependent signaling pathway mediates IFN-gamma-induced nuclear translocation of YB-1. Down-regulation of endogenous YB-1 expression by double-stranded YB-1-specific RNA abrogated the transcriptional repression of COL1A2 by IFN-gamma in the absence and presence of TGF-beta. In transient transfection assays, overexpression of YB-1 in human dermal fibroblasts exhibited antagonistic actions against TGF-beta and Smad3. Physical interaction between Smad3 and YB-1 was demonstrated by immunoprecipitation-Western blot analyses, and electrophoretic mobility shift assays using the recombinant Smad3 and YB-1 proteins indicated that YB-1 forms a complex with Smad3 bound to the Smad-binding element. Glutathione S-transferase pull-down assays showed that YB-1 binds to the MH1 domain of Smad3, whereas the central and carboxyl-terminal regions of YB-1 were required for its interaction with Smad3. YB-1 also interferes with the Smad3-p300 interaction by its preferential binding to p300. Altogether, the results provide a novel insight into the mechanism by which IFN-gamma/YB-1 counteracts TGF-beta/Smad3. They also indicate that IFN-gamma/YB-1 inhibits COL1A2 transcription by dual actions: via the IFN-gamma response element and through a cross-talk with the TGF

  19. Near-infrared quantum cutting in Yb3+ ion doped strontium vanadate

    NASA Astrophysics Data System (ADS)

    Sawala, N. S.; Bajaj, N. S.; Omanwar, S. K.

    2016-05-01

    The materials Sr3-x(VO4)2:xYb were successfully synthesized by co-precipitation method varying the concentration of Yb3+ ions from 0 to 0.06 mol. It was characterize by powder X-ray powder diffraction (XRD) and surface morphology was studied by scanning electronic microscope (SEM). The photoluminescence (PL) properties were studied by spectrophotometers in near infra red (NIR) and ultra violet visible (UV-VIS) region. The Yb3+ ion doped tristrontium vanadate (Sr3(VO4)2) phosphors that can convert a photon of UV region (349 nm) into photons of NIR region (978, 996 and 1026 nm). Hence this phosphor could be used as a quantum cutting (QC) luminescent convertor in front of crystalline silicon solar cell (c-Si) panels to reduce thermalization loss due to spectral mismatch of the solar cells. The theoretical value of quantum efficiency (QE) was calculated from steady time decay measurement and the maximum efficiency approached up to 144.43%. The Sr(3-x) (VO4)2:xYb can be potentiality used for betterment of photovoltaic (PV) technology.

  20. [Preparation, characterization and upconversion fluorescence of NaYF4 : Yb, Er /graphene oxide nanocomposites].

    PubMed

    Ji, Tian-Hao; Qie, Nan; Wang, Ji-Mei; Hua, Yong-Yong; Ji, Zhi-Jiang

    2013-03-01

    NaYF4 : Yb, Er/rGO and SiO2-coated NaYF4 : Yb, Er/rGO nanocomposites can be prepared through "one-pot" and directly mixing preparation routes. Various measurement results show that the NaYF4 : Yb, Er in the nanocomposites exhibits a cubic a-type structure and nanoparticle-like morphology with a diameter range of 30-70 nm; the rGO layers are well-dispersed in the nanocomposites, and whereas the rGO obtained from "one-pot" preparation renders relatively better dispersion. Raman spectra demonstrate that there exists a surface coupling action between the two kinds of nanomaterials, and with the increase in the relative rGO content, such action becomes stronger. UC fluorescence measurement results reveal that the rGO has significantly quenching effect and optical-limiting performance on the UC fluorescence, particularly on the red-emission of the NaYFa : Yb, Er or SiO2-coated NaYF4 : Yb, Er nanoparticles. The red-emission intensity gradually decreases with an increase in the rGO content, but the green-emission shows less change. It should be stressed that, in comparison with NaYF4 : Yb, Er/rGO, with a similar rGO content, the red-emission intensity of SiO2-coated NaYF4 : Yb, Er/rGO decreases much obviously due to a stronger light-absorption caused by part rGO aggregation.

  1. Constitutive overexpression of the TaNF-YB4 gene in transgenic wheat significantly improves grain yield

    PubMed Central

    Yadav, Dinesh; Shavrukov, Yuri; Bazanova, Natalia; Chirkova, Larissa; Borisjuk, Nikolai; Kovalchuk, Nataliya; Ismagul, Ainur; Parent, Boris; Langridge, Peter; Hrmova, Maria; Lopato, Sergiy

    2015-01-01

    Heterotrimeric nuclear factors Y (NF-Ys) are involved in regulation of various vital functions in all eukaryotic organisms. Although a number of NF-Y subunits have been characterized in model plants, only a few have been functionally evaluated in crops. In this work, a number of genes encoding NF-YB and NF-YC subunits were isolated from drought-tolerant wheat (Triticum aestivum L. cv. RAC875), and the impact of the overexpression of TaNF-YB4 in the Australian wheat cultivar Gladius was investigated. TaNF-YB4 was isolated as a result of two consecutive yeast two-hybrid (Y2H) screens, where ZmNF-YB2a was used as a starting bait. A new NF-YC subunit, designated TaNF-YC15, was isolated in the first Y2H screen and used as bait in a second screen, which identified two wheat NF-YB subunits, TaNF-YB2 and TaNF-YB4. Three-dimensional modelling of a TaNF-YB2/TaNF-YC15 dimer revealed structural determinants that may underlie interaction selectivity. The TaNF-YB4 gene was placed under the control of the strong constitutive polyubiquitin promoter from maize and introduced into wheat by biolistic bombardment. The growth and yield components of several independent transgenic lines with up-regulated levels of TaNF-YB4 were evaluated under well-watered conditions (T1–T3 generations) and under mild drought (T2 generation). Analysis of T2 plants was performed in large deep containers in conditions close to field trials. Under optimal watering conditions, transgenic wheat plants produced significantly more spikes but other yield components did not change. This resulted in a 20–30% increased grain yield compared with untransformed control plants. Under water-limited conditions transgenic lines maintained parity in yield performance. PMID:26220082

  2. Feasibility study of CaSO4:Tb,Yb as a thermoluminescent dosimeter

    NASA Astrophysics Data System (ADS)

    Junot, Danilo O.; Santos, Max A.; Chagas, Marcos A. P.; Couto dos Santos, Marcos A.; Nunes, Luiz A. O.; Souza, Divanizia N.

    2014-02-01

    A new composite based on CaSO4, using terbium as dopant and ytterbium as co-dopant (CaSO4:Tb,Yb), was developed for employment as a thermoluminescent (TL) dosimeter. The crystals used in this work were grown using a production route based on the Yamashita method (Yamashita et al., 1968). Crystal powder was calcined at 600 °C for 1 h. Pellets were made by adding commercial and colorless glass to improve physical resistance and sintered at 700 °C for 6 h. All samples were irradiated by a beta source (90Sr/90Y) and received doses from 1 Gy to 5 Gy. TL analyses have been performed and characteristics such as sensitivity, reproducibility, linearity, and fading have been studied. The CaSO4:Tb,Yb pellets glow curves presented two peaks, the first at around 115 °C, and the second at around 200 °C. The highest intensity was shown for CaSO4:Tb,Yb with a concentration of 0.1 mol% of Tb and Yb together. In all the samples the TL response was proportional to the absorbed dose. Therefore, the CaSO4:Tb,Yb has potential to be used as a thermoluminescent dosimeter.

  3. Highly-efficient multi-watt Yb:CaLnAlO4 microchip lasers

    NASA Astrophysics Data System (ADS)

    Loiko, Pavel; Serres, Josep Maria; Mateos, Xavier; Xu, Xiaodong; Xu, Jun; Yumashev, Konstantin; Griebner, Uwe; Petrov, Valentin; Aguiló, Magdalena; Díaz, Francesc; Major, Arkady

    2017-02-01

    Tetragonal rare-earth calcium aluminates, CaLnAlO4 where Ln = Gd or Y (CALGO and CALYO, respectively), are attractive laser crystal hosts due to their locally disordered structure and high thermal conductivity. In the present work, we report on highly-efficient power-scalable microchip lasers based on 8 at.% Yb:CALGO and 3 at.% Yb:CALYO crystals grown by the Czochralski method. Pumped by an InGaAs laser diode at 978 nm, the 6 mm-long Yb:CALGO microchip laser generated 7.79 W at 1057-1065 nm with a slope efficiency of η = 84% (with respect to the absorbed pump power) and an optical-to-optical efficiency of ηopt = 49%. The 3 mm-long Yb:CALYO microchip laser generated 5.06 W at 1048-1056 nm corresponding to η = 91% and ηopt = 32%. Both lasers produced linearly polarized output (σ- polarization) with an almost circular beam profile and beam quality factors M2 x,y <1.1. The output performance of the developed lasers was modeled yielding a loss coefficient as low as 0.004-0.007 cm-1. The results indicate that the Yb3+- doped calcium aluminates are very promising candidates for high-peak-power passively Q-switched microchip lasers.

  4. Interaction of ultra-depleted MORBs with plagioclase: implications for CO2/Ba ratios

    NASA Astrophysics Data System (ADS)

    Shimizu, K.; Hauri, E.; Saal, A. E.; Perfit, M. R.; Hekinian, R.

    2017-12-01

    Carbon in Earth's upper mantle can significantly reduce its solidus temperature, which in turn can affect other physical properties through generation of partial melt. Carbon content in the depleted upper mantle can be estimated using ultra-depleted mid-ocean ridge basalt (UD-MORB) glasses and melt inclusions that are undersaturated in CO2. CO2 has been shown to behave as a highly incompatible element during mantle melting both through natural samples and experiments. Given its highly incompatible behavior, CO2/Ba and CO2/Nb ratios in CO2 undersaturated UD-MORBs have been used to estimate the CO2/Ba and CO2/Nb ratios and carbon content in Earth's upper mantle. A potential issue with part of this approach is the effect of melt-plagioclase chemical interaction on the CO2/Ba ratios in UD-MORBs. Plagioclase is ubiquitous in the oceanic crust and is enriched in Ba relative to other phases. Chemical interactions (assimilation and/or diffusion) between MORB melts and plagioclase bearing rocks have been shown to affect the Ba (and Sr and Eu) concentrations in MORBs, implying that such processes may also affect their CO2/Ba ratio. Hence, understanding the effect of chemical interaction between plagioclase and UD-MORBs is important for having better constraints on CO2/Ba ratio and carbon content in Earth's upper mantle. In this study, we report on the compositions of olivine-hosted melt inclusions and glasses from the Siqueiros and Garrett transform faults. A subset of melt inclusions in lavas from both transform faults show potential signatures of chemical interaction with plagioclase such as low CO2/Ba, Nb/Ba, and Nd/Sr. CO2 degassing cannot explain the low CO2/Ba ratio in the samples as they are undersaturated in CO2. To better understand the effect of chemical interaction with plagioclase on the composition of UD-MORBs, we model end-member scenarios, which are (1) assimilation of plagioclase and (2) diffusion of elements from plagioclase into the UD-MORBs. In general

  5. Optimization of the cooling profile to achieve crack-free Yb:S-FAP crystals

    NASA Astrophysics Data System (ADS)

    Fang, H. S.; Qiu, S. R.; Zheng, L. L.; Schaffers, K. I.; Tassano, J. B.; Caird, J. A.; Zhang, H.

    2008-08-01

    Yb:S-FAP [Yb 3+:Sr 5(PO 4) 3F] crystals are an important gain medium for diode-pumped laser applications. Growth of 7.0 cm diameter Yb:S-FAP crystals utilizing the Czochralski (CZ) method from SrF 2-rich melts often encounters cracks during the post-growth cool-down stage. To suppress cracking during cool-down, a numerical simulation of the growth system was used to understand the correlation between the furnace power during cool-down and the radial temperature differences within the crystal. The critical radial temperature difference, above which the crystal cracks, has been determined by benchmarking the simulation results against experimental observations. Based on this comparison, an optimal three-stage ramp-down profile was implemented, which produced high-quality, crack-free Yb:S-FAP crystals.

  6. Wavelength tunability of laser based on Yb-doped YGAG ceramics

    NASA Astrophysics Data System (ADS)

    Šulc, Jan; Jelínková, Helena; Jambunathan, Venkatesan; Miura, Taisuke; Endo, Akira; Lucianetti, Antonio; Mocek, TomáÅ.¡

    2015-02-01

    The wavelength tunability of diode pumped laser based on Yb-doped mixed garnet Y3Ga2Al3O12 (Yb:YGAG) ceramics was investigated. The tested Yb:YGAG sample (10% Yb/Y) was in the form of 2mm thick plane-parallel face-polished plate (without AR coatings). A fiber (core diameter 100 μm, NA= 0.22) coupled laser diode (LIMO, LIMO35-F100-DL980-FG-E) with emission at wavelength 969 nm, was used for longitudinal Yb:YGAG pumping. The laser diode was operating in the pulsed regime (2 ms pulse length, 10 Hz repetition rate). The duty-cycle 2% ensured a low thermal load even under the maximum diode pumping power amplitude 20W (ceramics sample was only air-cooled). The 145mm long semi-hemispherical laser resonator consisted of a flat pumping mirror (HR @ 1.01 - 1.09 μm, HT @ 0.97 μm) and curved (r = 150mm) output coupler with a reflectivity of ˜ 97% @ 1.01 - 1.09 μm. Wavelength tuning of the ytterbium laser was accomplished by using a birefringent filter (single 1.5mm thick quartz plate) placed inside the optical resonator at the Brewster angle between the output coupler and the laser active medium. The laser was continuously tunable over ˜ 58nm (from 1022nm to 1080 nm) and the tuning band was mostly limited by the free spectral range of used birefringent filter. The maximum output power amplitude 3W was obtained at wavelength 1046nm for absorbed pump power amplitude 10.6W. The laser slope efficiency was 34%.

  7. X-ray structural study of intermetallic alloys RT{sub 2}Si and RTSi{sub 2} (R=rare earth, T=noble metal)

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Gribanov, Alexander, E-mail: avgri@mail.r; Chemistry Department of the Moscow State University, Leninskie Gory, GSP-1, 119991 Moscow; Grytsiv, Andriy

    Two series of intermetallic alloys, RT{sub 2}Si and RTSi{sub 2}, have been synthesized from stoichiometric compositions. The crystal structures of EuPt{sub 1+x}Si{sub 2-x} (CeNiSi{sub 2}-type), CeIr{sub 2}Si (new structure type), YbPd{sub 2}Si and YbPt{sub 2}Si (both YPd{sub 2}Si-type) have been elucidated from X-ray single crystal CCD data, which were confirmed by XPD experiments. The crystal structures of LaRh{sub 2}Si and LaIr{sub 2}Si (CeIr{sub 2}Si-type), {l_brace}La,Ce,Pr,Nd{r_brace}AgSi{sub 2} (all TbFeSi{sub 2}-type), and EuPt{sub 2}Si (inverse CeNiSi{sub 2}-type) were characterized by XPD data. RT{sub 2}Si/RTSi{sub 2} compounds were neither detected in as-cast alloys Sc{sub 25}Pt{sub 50}Si{sub 25}, Eu{sub 25}Os{sub 25}Si{sub 50} and Eu{submore » 25}Rh{sub 25}Si{sub 50} nor after annealing at 900 {sup o}C. Instead, X-ray single crystal data prompted Eu{sub 2}Os{sub 3}Si{sub 5} (Sc{sub 2}Fe{sub 3}Si{sub 5}-type) and EuRh{sub 2+x}Si{sub 2-x} (x=0.04, ThCr{sub 2}Si{sub 2}-type) as well as a new structure type for Sc{sub 2}Pt{sub 3}Si{sub 2} (own type). - Graphical abstract: Two series of the intermetallic compounds, RT{sub 2}Si and RTSi{sub 2}, have been investigated by X-ray diffraction methods. The new tetragonal CeIr{sub 2}Si-type of the crystal structure was described and the interrelation between orthorhombic CeNiSi{sub 2} and tetragonal CeIr{sub 2}Si had been discussed as a similar packing of the BaAl{sub 4} and AlB{sub 2} slabs.« less

  8. Effect of Yb(3+) on the Crystal Structural Modification and Photoluminescence Properties of GGAG:Ce(3+).

    PubMed

    Luo, Zhao-Hua; Liu, Yong-Fu; Zhang, Chang-Hua; Zhang, Jian-Xin; Qin, Hai-Ming; Jiang, Hao-Chuan; Jiang, Jun

    2016-03-21

    Gadolinium gallium aluminum garnet (GGAG) is a very promising host for the highly efficient luminescence of Ce(3+) and shows potential in radiation detection applications. However, the thermodynamically metastable structure would be slanted against it from getting high transparency. To stabilize the crystal structure of GGAG, Yb(3+) ions were codoped at the Gd(3+) site. It is found that the decomposition of garnet was suppressed and the transparency of GGAG ceramic was evidently improved. Moreover, the photoluminescence of GGAG:Ce(3+),xYb(3+) with different Yb(3+) contents has been investigated. When the Ce(3+) ions were excited under 475 nm, a typical near-infrared region emission of Yb(3+) ions can be observed, where silicon solar cells have the strongest absorption. Basing on the lifetimes of Ce(3+) ions in the GGAG:Ce(3+),xYb(3+) sample, the transfer efficiency from Ce(3+) to Yb(3+) and the theoretical internal quantum efficiency can be calculated and reach up to 86% and 186%, respectively. This would make GGAG:Ce(3+),Yb(3+) a potential attractive downconversion candidate for improving the energy conversion efficiency of crystalline silicon (c-Si) solar cells.

  9. Mobilization of Ag, heavy metals and Eu from the waste deposit of the Las Herrerias mine (Almería, SE Spain)

    NASA Astrophysics Data System (ADS)

    Navarro, A.; Cardellach, E.

    2009-02-01

    We studied the mobility of silver, heavy metals and europium in waste from the Las Herrerías mine in Almería (SE Spain). The most abundant primary mineral phases in the mine wastes are hematite, hydrohematite, barite, quartz, muscovite, anorthite, calcite and phillipsite. The minor phase consisted of primary minerals including ankerite, cinnabar, digenite, magnesite, stannite, siderite and jamesonite, and secondary minerals such as glauberite, szomolnokite, thenardite and uklonscovite. The soils show high concentrations of Ag (mean 21.6 mg kg-1), Ba (mean 2.5%), Fe (mean 114,000 mg kg-1), Sb (mean 342.5 mg kg-1), Pb (mean 1,229.8 mg kg-1), Zn (mean 493 mg kg-1), Mn (mean 4,321.1 mg kg-1), Cd (mean 1.2 mg kg-1) and Eu (mean 4.0 mg kg-1). The column experiments showed mobilization of Ag, Al, Ba, Cu, Cd, Eu, Fe, Mn, Ni, Sb, Pb and Zn, and the inverse modelling showed that the dissolution of hematite, hausmannite, pyrolusite and anglesite can largely account for the mobilization of Fe, Mn and Pb in the leaching experiment. The mobility of silver may be caused by the presence of kongsbergite and chlorargyrite in the waste, while the mobility of Eu seems to be determined by Eu(OH)3, which controls the solubility of Eu in the pH-Eh conditions of the experiments. The mineralogy, pH, Eh and geochemical composition of the mine wastes may explain the possible mobilization of heavy metals and metalloids. However, the absence of contaminants in the groundwater may be caused by the carbonate-rich environment of “host-rocks” that limits their mobility.

  10. Yb14MgBi11: structure, thermoelectric properties and the effect of the structure on low lattice thermal conductivity.

    PubMed

    Hu, Yufei; Kauzlarich, Susan M

    2017-03-21

    Zintl phases Yb 14 MnSb 11 and Yb 14 MgSb 11 , which share the same complex structure type, have been demonstrated as the best p-type thermoelectric materials for the high temperature region (800-1200 K). A new iso-structural compound, Yb 14 MgBi 11 , was synthesized in order to investigate the structure and thermoelectric properties of the Bi analogs. Yb 14 MgBi 11 crystallizes in the Ca 14 AlSb 11 structure-type with the space group I4 1 /acd [a = 16.974(2) Å, c = 22.399(4) Å, V = 6454(2) Å 3 , R 1 /wR 2 = 0.0238/0.0475]. The structure follows the previous description of this structure type and the trend observed in previous analogs. Thermoelectric properties of Yb 14 MgBi 11 are measured together with Yb 14 MnBi 11 and both compounds are metallic. Compared to Yb 14 MgSb 11 , Yb 14 MgBi 11 has a higher carrier concentration with a similar mobility and effective mass. The lattice thermal conductivity of Yb 14 MgBi 11 is extremely low, which is as low as 0.16-0.36 W(mK) -1 . The zT values of Yb 14 MgBi 11 and Yb 14 MnBi 11 reach 0.2 at 875 K.

  11. Investigating the evolution of local structure around Er and Yb in ZnO:Er and ZnO:Er, Yb on annealing using X-ray absorption spectroscopy

    NASA Astrophysics Data System (ADS)

    Anjana, R.; Jayaraj, M. K.; Yadav, A. K.; Jha, S. N.; Bhattacharyya, D.

    2018-04-01

    The local structure around Er and Yb centre in ZnO favouring upconversion luminescence was studied using EXAFS (Extended X-ray absorption fine structure spectroscopy). Due to the ionic radii difference between Zn and Er, Yb ions, the dopants cannot replace Zn in the ZnO lattice properly. Er2O3 and Yb2O3 impurity phases are formed at the grain boundaries of ZnO. It is found that the local structure around the Er centre in ZnO is modified on annealing in air. The symmetry around both erbium and ytterbium reduces with increase in annealing temperature. Symmetry reduction will favour the intra-4f transition and the energy transitions causing upconversion luminescence. By fitting the EXAFS data with theoretically simulated data, it is found that the Er centre forms a local structure similar to C4ν symmetry which is a distorted octahedron. On annealing the sample to 1200 °C, all the erbium centres are transformed to C4ν symmetry causing enhanced upconversion emission. Yb centre has also been modified on annealing. The decrease in co-ordination number with annealing temperature will decrease the symmetry and increase the near infrared absorption cross section. The decrease in symmetry around both the erbium and ytterbium centre and formation of C4ν symmetry around Er centre is the reason behind the activation of upconversion luminescence with high temperature annealing in both Er doped and Er, Yb co-doped ZnO samples. The study will be useful for the synthesis of high efficiency upconversion materials.

  12. Optimization of the cooling profile to achieve crack-free Yb:S-FAP crystals

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Fang, H; Qiu, S; Kheng, L

    Yb:S-FAP [Yb{sup 3+}:Sr{sub 5}(PO{sub 4}){sub 3}F] crystals are an important gain medium for diode-pumped laser applications. Growth of 7.0 cm diameter Yb:S-FAP crystals utilizing the Czochralski (CZ) method from SrF{sub 2}-rich melts often encounter cracks during the post growth cool down stage. To suppress cracking during cool down, a numerical simulation of the growth system was used to understand the correlation between the furnace power during cool down and the radial temperature differences within the crystal. The critical radial temperature difference, above which the crystal cracks, has been determined by benchmarking the simulation results against experimental observations. Based on thismore » comparison, an optimal three-stage ramp-down profile was implemented and produced high quality, crack-free Yb:S-FAP crystals.« less

  13. Cold Shock Domain Family Members YB-1 and MSY4 Share Essential Functions during Murine Embryogenesis▿ †

    PubMed Central

    Lu, Zhi Hong; Books, Jason T.; Ley, Timothy J.

    2006-01-01

    Three cold shock domain (CSD) family members (YB-1, MSY2, and MSY4) exist in vertebrate species ranging from frogs to humans. YB-1 is expressed throughout embryogenesis and is ubiquitously expressed in adult animals; it protects cells from senescence during periods of proliferative stress. YB-1-deficient embryos die unexpectedly late in embryogenesis (embryonic day 18.5 [E18.5] to postnatal day 1) with a runting phenotype. We have now determined that MSY4, but not MSY2, is also expressed during embryogenesis; its abundance declines substantially from E9.5 to E17.5 and is undetectable on postnatal day 1(adult mice express MSY4 in testes only). Whole-mount analysis revealed similar patterns of YB-1 and MSY4 RNA expression in E11.5 embryos. To determine whether MSY4 delays the death of YB-1-deficient embryos, we created and analyzed MSY4-deficient mice and then generated YB-1 and MSY4 double-knockout embryos. MSY4 is dispensable for normal development and survival, but the testes of adult mice have excessive spermatocyte apoptosis and seminiferous tubule degeneration. Embryos doubly deficient for YB-1 and MSY4 are severely runted and die much earlier (E8.5 to E11.5) than YB-1-deficient embryos, suggesting that MSY4 indeed shares critical cellular functions with YB-1 in the embryonic tissues where they are coexpressed. PMID:16954378

  14. Testing Room-Temperature Ionic Liquid Solutions for Depot Repair of Aluminum Coatings

    DTIC Science & Technology

    2011-05-01

    Ne 3 Na Mg IIIB IVB VB VIB VIIB ------ VIIIB ------ IB IIB Al Si P S Cl Ar 4 K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr 5 Rb Sr Y Zr Nb Mo Tc...Ru Rh Pd Ag Cd In Sn Sb Te I Xe 6 Cs Ba La Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn 7 Fr Ra Ac Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu Th Pa U Np...Electroplating Bath Lid Arrangement ;:::::::::::=== Thermometer Purge gas vent Anode lead Cathode lead (Extractable from the lid) Purge feed gas

  15. Electro-optic modulator material

    DOEpatents

    Adams, John J.; Ebbers, Chris A.

    2005-02-22

    An electro-optic device for use with a laser beam. A crystal has a first face and a second face. Means are provided for applying a voltage across the crystal to obtain a net phase retardation on the polarization of the laser beam when the laser beam is passed through the crystal. In one embodiment the crystal is composed of a compound having the chemical formula ReAe40(BO3)3 where: RE consists of one or more of the following elements La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu and two other elements Y and Sc; and where Ae is from the list of Ca, Sr, or Ba.

  16. Ceramic oxyanion emitter

    DOEpatents

    Delmore, James E.; Appelhans, Anthony D.; Peterson, Eric S.

    1996-01-01

    A rare earth oxide matrix (composition of matter) is formed which emits (upon heating) heavy metal oxide anions (oxyanions) into a gas phase, wherein the anions are emitted with high intensity, and wherein longevity of life of the composition of matter is retained. The matter is formed by blending a major component of a rare earth oxide, Europium oxide (Eu.sub.2 O.sub.3) or Ytterbium oxide (Yb.sub.2 O.sub.3), with a minor component of a Barium (Ba), Calcium (Ca) or Strontium (Sr) salt of a heavy metal oxyanion. Heavy anions are emitted upon heating the composition of matter to a predetermined temperature of about 800.degree. C.

  17. Controlling the 1 μm spontaneous emission in Er/Yb co-doped fiber amplifiers.

    PubMed

    Sobon, Grzegorz; Kaczmarek, Pawel; Antonczak, Arkadiusz; Sotor, Jaroslaw; Abramski, Krzysztof M

    2011-09-26

    In this paper we present our experimental studies on controlling the amplified spontaneous emission (ASE) from Yb(3+) ions in Er/Yb co-doped fiber amplifiers. We propose a new method of controlling the Yb-ASE by stimulating a laser emission at 1064 nm in the amplifier, by providing a positive 1 μm signal feedback loop. The results are discussed and compared to a conventional amplifier setup without 1 μm ASE control and to an amplifier with auxiliary 1064 nm seeding. We have shown, that applying a 1064 nm signal loop in an Er/Yb amplifier can increase the output power at 1550 nm and provide stable operation without parasitic lasing at 1 μm. © 2011 Optical Society of America

  18. Origin of Quantum Criticality in Yb-Al-Au Approximant Crystal and Quasicrystal

    NASA Astrophysics Data System (ADS)

    Watanabe, Shinji; Miyake, Kazumasa

    2016-06-01

    To get insight into the mechanism of emergence of unconventional quantum criticality observed in quasicrystal Yb15Al34Au51, the approximant crystal Yb14Al35Au51 is analyzed theoretically. By constructing a minimal model for the approximant crystal, the heavy quasiparticle band is shown to emerge near the Fermi level because of strong correlation of 4f electrons at Yb. We find that charge-transfer mode between 4f electron at Yb on the 3rd shell and 3p electron at Al on the 4th shell in Tsai-type cluster is considerably enhanced with almost flat momentum dependence. The mode-coupling theory shows that magnetic as well as valence susceptibility exhibits χ ˜ T-0.5 for zero-field limit and is expressed as a single scaling function of the ratio of temperature to magnetic field T/B over four decades even in the approximant crystal when some condition is satisfied by varying parameters, e.g., by applying pressure. The key origin is clarified to be due to strong locality of the critical Yb-valence fluctuation and small Brillouin zone reflecting the large unit cell, giving rise to the extremely-small characteristic energy scale. This also gives a natural explanation for the quantum criticality in the quasicrystal corresponding to the infinite limit of the unit-cell size.

  19. Luminescence performance of Eu{sup 3+} doped lead free zinc phosphate glasses for red emission

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Prasad, V. Reddy; Babu, S.; Ratnakaram, Y. C., E-mail: ratnakaramsvu@gmail.com

    2016-05-06

    Luminescence performance of zinc phosphate glasses containing Eu{sup 3+} ion with the chemical compositions (60-x)NH{sub 4}H{sub 2}PO{sub 4}-20ZnO-10BaF{sub 2}-10NaF-x Eu{sub 2}O{sub 3} (where x = 0.2, 0.5, 1.0 and 1.5 mol%) has been studied. The Fourier Transform Infrared Spectroscopy (FT-IR) shows several vibrations bands. Luminescence spectra of these glasses exhibit characteristic emission of Eu{sup 3+} ion with an intense and most prominent red emission (614 nm) which is attributed to {sup 5}D{sub 0}→{sup 7}F{sub 2} transition. Judd-Ofelt (Ω{sub 2}, Ω{sub 4}) parameters have been evaluated from the luminescence intensity ratios of {sup 5}D{sub 0}→{sup 7}F{sub J} (where J = 2 and 4)more » to {sup 5}D{sub 0}→{sup 7}F{sub 1} transition as well as absorption spectra under different constraints. Using J-O parameters and excitation spectra, the radiative parameters are calculated for different Eu{sup 3+} doped glasses.« less

  20. Influence of other rare earth ions on the optical refrigeration efficiency in Yb:YLF crystals.

    PubMed

    Di Lieto, Alberto; Sottile, Alberto; Volpi, Azzurra; Zhang, Zhonghan; Seletskiy, Denis V; Tonelli, Mauro

    2014-11-17

    We investigated the effect of rare earth impurities on the cooling efficiency of Yb³⁺:LiYF₄ (Yb:YLF). The refrigeration performance of two single crystals, doped with 5%-at. Yb and with identical history but with different amount of contaminations, have been compared by measuring the cooling efficiency curves. Spectroscopic and elemental analyses of the samples have been carried out to identify the contaminants, to quantify their concentrations and to understand their effect on the cooling efficiencies. A model of energy transfer processes between Yb and other rare earth ions is suggested, identifying Erbium and Holmium as elements that produce a detrimental effect on the cooling performance.

  1. New hydrolytically stable solvent for Am/Eu separation in acidic media

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Smirnov, I.V.; Babain, V.A.; Chirkov, A.V.

    Americium and europium extraction by synergistic mixture of 2,6-bis(1-aryl-1H-tetrazol-5-yl)pyridines (ATP) - chlorinated cobalt dicarbollide (CCD) in polar diluent s from HNO{sub 3} media was studied. Meta-nitro-benzo-trifluoride, phenyl-tri-fluoro-methyl sulfone and 1,2-dichloroethane were used as diluents. The effect of diluent, composition of aqueous phase and substituent nature in aryl ring of ATPs on the extraction efficiency and selectivity of americium and europium separation was investigated. At the optimal ratio of nATP:CCD 1:1 the Am - Eu separation factor exceeded 90. Extraction of {sup 85}Sr, {sup 137}Cs and {sup 133}Ba was investigated and it was found that the mixture nATP-CCD provided the separationmore » of Sr /Ba pair with a factor of 35. High resistance of 2,6-bisaryltetrazolyl pyridines to the action of nitric acid was demonstrated. (authors)« less

  2. Spectroscopy and laser operation of Indium-modified Yb:KLuW: a promising crystal for femtosecond lasers

    NASA Astrophysics Data System (ADS)

    Mateos, Xavier; Serres, Josep Maria; Loiko, Pavel; Yumashev, Konstantin; Griebner, Uwe; Petrov, Valentin; Aguiló, Magdalena; Díaz, Francesc

    2017-02-01

    We report on the growth, spectroscopic and laser characterization of a novel monoclinic laser crystal, 3.5 at.% Yb, 5.5 at.% In:KLu(WO4)2 (Yb,In:KLuW). Single-crystals of high optical quality are grown by the TSSG method. The absorption, stimulated-emission and gain cross-sections are determined for this material at room temperature with polarized light. The maximum σabs is 9.9×10-20 cm2 at 980.8 nm for light polarization E || Nm. The radiative lifetime of Yb3+ in Yb,In:KLuW is 237+/-5 μs. The stimulated-emission cross-sections are σSE(m) = 2.4×10-20 cm2 at 1022.4 nm and σSE(p) = 1.3×10-20 cm2 at 1039.1 nm corresponding to an emission bandwidth of >30 nm and >35 nm, respectively. A diode-pumped Ng-cut Yb,In:KLuW microchip laser generates 4.11 W at 1047-1052 nm with a slope efficiency of 78%. Passive Q-switching of a Yb,In:KLuW laser is also demonstrated. The Yb,In:KLuW crystal seems very promising for sub-100 fs mode-locked lasers.

  3. Constitutive overexpression of the TaNF-YB4 gene in transgenic wheat significantly improves grain yield.

    PubMed

    Yadav, Dinesh; Shavrukov, Yuri; Bazanova, Natalia; Chirkova, Larissa; Borisjuk, Nikolai; Kovalchuk, Nataliya; Ismagul, Ainur; Parent, Boris; Langridge, Peter; Hrmova, Maria; Lopato, Sergiy

    2015-11-01

    Heterotrimeric nuclear factors Y (NF-Ys) are involved in regulation of various vital functions in all eukaryotic organisms. Although a number of NF-Y subunits have been characterized in model plants, only a few have been functionally evaluated in crops. In this work, a number of genes encoding NF-YB and NF-YC subunits were isolated from drought-tolerant wheat (Triticum aestivum L. cv. RAC875), and the impact of the overexpression of TaNF-YB4 in the Australian wheat cultivar Gladius was investigated. TaNF-YB4 was isolated as a result of two consecutive yeast two-hybrid (Y2H) screens, where ZmNF-YB2a was used as a starting bait. A new NF-YC subunit, designated TaNF-YC15, was isolated in the first Y2H screen and used as bait in a second screen, which identified two wheat NF-YB subunits, TaNF-YB2 and TaNF-YB4. Three-dimensional modelling of a TaNF-YB2/TaNF-YC15 dimer revealed structural determinants that may underlie interaction selectivity. The TaNF-YB4 gene was placed under the control of the strong constitutive polyubiquitin promoter from maize and introduced into wheat by biolistic bombardment. The growth and yield components of several independent transgenic lines with up-regulated levels of TaNF-YB4 were evaluated under well-watered conditions (T1-T3 generations) and under mild drought (T2 generation). Analysis of T2 plants was performed in large deep containers in conditions close to field trials. Under optimal watering conditions, transgenic wheat plants produced significantly more spikes but other yield components did not change. This resulted in a 20-30% increased grain yield compared with untransformed control plants. Under water-limited conditions transgenic lines maintained parity in yield performance. © The Author 2015. Published by Oxford University Press on behalf of the Society for Experimental Biology.

  4. Systematic analysis of hot Yb* isotopes using the energy density formalism

    NASA Astrophysics Data System (ADS)

    Jain, Deepika; Sharma, Manoj K.; Rajni; Kumar, Raj; Gupta, Raj K.

    2014-10-01

    A systematic study of the spin-orbit density interaction potential is carried out, with spherical as well as deformed choices of nuclei, for a variety of near-symmetric and asymmetric colliding nuclei leading to various isotopes of the compound nucleus Yb*, using the semiclassical extended Thomas-Fermi formulation (ETF) of the Skyrme energy density formalism (SEDF). We observe that the spin-orbit density interaction barrier height ( and barrier position ( increase systematically with the increase in number of neutrons in both the projectile and target, for spherical systems. On allowing deformation effects with optimum orientations, the barrier-height increases by a large order of magnitude, as compared to the spherical case, in going from 156Yb* to 172Yb* nuclear systems formed via near-symmetric Ni+Mo or asymmetric O+Sm colliding nuclei, except that for the oblate-shaped nuclei, the is the highest and shifts towards a smaller (compact) interaction radius. The temperature does not change the behavior of spin-orbit density dependent ( and independent ( interaction potentials, except for some minor changes in the magnitude. The orientation degree of freedom also plays an important role in modifying the barrier characteristics and hence produces a large effect on the fusion cross section. The fusion excitation function of the compound nuclei 160, 164Yb* formed in different incoming channels, show clearly that the new forces GSkI and KDE0v1 respond better than the old SIII force. Among the first two, KDE0v1 seems to perform better. The fusion cross-sections are also predicted for a few other isotopes of Yb*.

  5. Developmental characterization and environmental stress responses of Y-box binding protein 1 gene (AccYB-1) from Apis cerana cerana.

    PubMed

    Li, Guilin; Wang, Lijun; Wang, Ying; Li, Han; Liu, Zhenguo; Wang, Hongfang; Xu, Baohua; Guo, Xingqi

    2018-06-22

    Y-box binding protein 1 (YB-1) is a member of the cold shock domain protein superfamily and is involved in development, environmental stresses and DNA oxidative damage in many organisms. However, the precise functions of YB-1 are still not well understood in various insects, including bees. In the current study, we identified a YB-1 gene in Apis cerana cerana (AccYB-1). The predicted cis-acting elements in the promoter sequence of AccYB-1 indicated its possible roles in development and stress responses. AccYB-1 expression was higher in one-day-old larvae and dark-eyed pupae than in other development stages. Tissue-specific expression analysis showed that the mRNA level of AccYB-1 was higher in the thorax and midgut than in other tissues. The results from real-time PCR showed that AccYB-1 was induced by many environmental stresses. Silencing AccYB-1 downregulated the transcriptional level of some growth- and development-related genes and antioxidant genes and decreased the enzyme activities of several antioxidant-related enzymes, further indicating a possible function of AccYB-1 in growth, development and stress responses. Taken together, our findings suggest that AccYB-1 may play an indispensable role in growth and development and environmental stress responses in Apis cerana cerana. To our knowledge, this is the first paper to explore the role of YB-1 in bees. Copyright © 2018. Published by Elsevier B.V.

  6. X-ray excitation fluorescence spectra of the Eu2+-stabilized VK center in alkaline-earth fluoride mixed-crystal systems

    NASA Astrophysics Data System (ADS)

    Kawano, K.; Ohya, T.; Tsurumi, T.; Katoh, K.; Nakata, R.

    1999-11-01

    X-ray excitation fluorescence spectra were investigated for MF2:Eu (M=Ca, Sr, and Ba) and their mixed-crystal systems, Ca1-xSrxF2 and Sr1-xBaxF2 with the same fluorite structure. The UV recombination fluorescence band of the VK center associated with blue emission due to the f-d transition of Eu2+ ions was observed with changing mixture ratios x at room temperature. Two sets of weak spectra due to f-f transitions of Eu3+ ions also appeared in the 500-600-nm wavelength region. The peak wavelengths and the integrated intensities of the observed fluorescence were investigated as a function of the Eu concentration as well as the mixture ratio. For the blue emission of Eu2+, pulsed x-ray excitation resulted in shorter lifetimes (500-800 ns) than optical excitation, suggesting energy transfers between the excited states of VK centers and Eu2+. A kinematical fluorescence mechanism was proposed, taking into account the formation of a close pair of a hopping VK center and an immobile Eu2+ ion followed by an energy transfer from the former to the latter. Based on the calculated fluorescence decay curves best fitted to the response curves by x-ray pulse excitation, the energy transfer rates from VK centers to Eu2+ were estimated.

  7. 12  mJ Yb:YAG/Cr:YAG microchip laser.

    PubMed

    Guo, Xiaoyang; Tokita, Shigeki; Kawanaka, Junji

    2018-02-01

    We have developed a quasi-continuous wave diode end-pumped cryogenically cooled Yb:YAG/Cr:YAG passively Q-switched microchip laser. A maximum energy of 12.1 mJ with 3.7 MW of peak power was obtained. To the best of our knowledge, this is the highest energy and peak power obtained by an Yb:YAG/Cr:YAG microchip laser so far.

  8. Chemical pressure effects on magnetism in the quantum spin liquid candidates Yb2X2O7 (X =Sn, Ti, Ge)

    NASA Astrophysics Data System (ADS)

    Dun, Z. L.; Lee, M.; Choi, E. S.; Hallas, A. M.; Wiebe, C. R.; Gardner, J. S.; Arrighi, E.; Freitas, R. S.; Arevalo-Lopez, A. M.; Attfield, J. P.; Zhou, H. D.; Cheng, J. G.

    2014-02-01

    The linear and nonlinear ac susceptibility measurements of Yb-pyrochlores, Yb2X2O7 (X =Sn, Ti, and Ge), show transitions with a ferromagnetic nature at 0.13 and 0.25 K for Yb2Sn2O7 and Yb2Ti2O7, respectively, and an antiferromagnetic ordering at 0.62 K for Yb2Ge2O7. These systematical results (i) provided information about the nature of the unconventional magnetic ground state in Yb2Ti2O7; (ii) realized a distinct antiferromagnetic ordering state in Yb2Ge2O7; and (iii) demonstrated that the application of chemical pressure through the series of Yb-pyrochlores can efficiently perturb the fragile quantum spin fluctuations of the Yb3+ ions and lead to very different magnetic ground states.

  9. Luminescent and lasing characteristics of heavily doped Yb{sup 3+}:KY(WO{sub 4}){sub 2} crystals

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Kisel', V E; Troshin, A E; Shcherbitskii, V G

    The luminescence decay times are measured taking into account reabsorption for KY(WO{sub 4}){sub 2}:Yb(KYW:Yb) crystals with atomic concentrations of active ions from 0.2% to 30%. The radiative lifetime of Yb{sup 3+} ions was measured to be 233 {mu}s. The cw output power of 1.46 and 1.62 W was achieved with the slope efficiency 52% and 47% for Yb:KYW lasers with the atomic concentration of Yb{sup 3+} ions equal to 10% and 30%, respectively. Using a semiconductor mirror with a saturable absorber (SESAM) in the passive mode-locking regime, pulses of duration 194 and 180 fs were obtained at wavelengths of 1042more » and 1039 nm for crystals with Yb{sup 3+} concentrations equal to 10% and 30%, respectively, the average output power being 0.63 and 0.75 W. (lasers and amplifiers)« less

  10. YB-1 expression promotes epithelial-to-mesenchymal transition in prostate cancer that is inhibited by a small molecule fisetin

    PubMed Central

    Khan, Mohammad Imran; Adhami, Vaqar Mustafa; Lall, Rahul Kumar; Sechi, Mario; Joshi, Dinesh C.; Haidar, Omar M.; Syed, Deeba Nadeem; Siddiqui, Imtiaz Ahmad; Chiu, Shing-Yan; Mukhtar, Hasan

    2014-01-01

    Epithelial-to-mesenchymal transition (EMT) plays an important role in prostate cancer (PCa) metastasis. The transcription/translation regulatory Y-box binding protein-1 (YB-1) is known to be associated with cancer metastasis. We observed that YB-1 expression increased with tumor grade and showed an inverse relationship with E-cadherin in a human PCa tissue array. Forced YB-1 expression induced a mesenchymal morphology that was associated with down regulation of epithelial markers. Silencing of YB-1 reversed mesenchymal features and decreased cell proliferation, migration and invasion in PCa cells. YB-1 is activated directly via Akt mediated phosphorylation at Ser102 within the cold shock domain (CSD). We next identified fisetin as an inhibitor of YB-1 activation. Computational docking and molecular dynamics suggested that fisetin binds on the residues from β1 - β4 strands of CSD, hindering Akt's interaction with YB-1. Calculated free binding energy ranged from −11.9845 to −9.6273 kcal/mol. Plasmon Surface Resonance studies showed that fisetin binds to YB-1 with an affinity of approximately 35 μM, with both slow association and dissociation. Fisetin also inhibited EGF induced YB-1 phosphorylation and markers of EMT both in vitro and in vivo. Collectively our data suggest that YB-1 induces EMT in PCa and identify fisetin as an inhibitor of its activation. PMID:24770864

  11. Dual functional NaYF4:Yb3+, Er3+@NaYF4:Yb3+, Nd3+ core-shell nanoparticles for cell temperature sensing and imaging

    NASA Astrophysics Data System (ADS)

    Shi, Zengliang; Duan, Yue; Zhu, Xingjun; Wang, Qiwei; Li, DongDong; Hu, Ke; Feng, Wei; Li, Fuyou; Xu, Chunxiang

    2018-03-01

    Lanthanide-doped up-conversion nanoparticles (UCNPs) provide a remote temperature sensing approach to monitoring biological microenvironments. In this research, the UCNPs of NaYF4:Yb3+, Er3+@NaYF4:Yb3+, Nd3+ with hexagonal (β)-phase were synthesized and applied in cell temperature sensing as well as imaging after surface modification with meso-2, 3-dimercaptosuccinic acid. In the core-shell UCNPs, Yb3+ ions were introduced as energy transfer media between sensitizers of Nd3+ and activators of Er3+ to improve Er3+emission and prevent their quenching behavior due to multiple energy levels of Nd3+. Under the excitations of 808 nm and 980 nm lasers, the NaYF4:Yb3+, Er3+@NaYF4:Yb3+, Nd3+ nanoparticles exhibited an efficient green band with two emission peaks at 525 nm and 545 nm, respectively, which originated from the transitions of 2H11/2 → 4I15/2 and 4S3/2 → 4I15/2 for Er3+ ions. We demonstrate that an occurrence of good logarithmic linearity exists between the intensity ratio of these two emission peaks and the reciprocal of the inside or outside temperature of NIH-3T3 cells. A better thermal stability is proved through temperature-dependent spectra with a heating-cooling cycle. The obtained viability of NIH-3T3 cells is greater than 90% after incubations of about 12 and 24 (h), and they possess a lower cytotoxicity of UCNPs. This work provides a method for monitoring the cell temperature and its living state from multiple dimensions including temperature response, cell images and visual up-conversion fluorescent color.

  12. Compositional dependence of broadband near-infrared downconversion and upconversion of Yb3+-doped multi-component glasses

    NASA Astrophysics Data System (ADS)

    Zhang, Liaolin; Xia, Yu; Shen, Xiao; Wei, Wei

    2017-07-01

    Yb3+ single-doped glasses show a strong excitation band in the 300-400 nm region, and efficiently emit photons with wavelengths of 920-1150 nm, and have potential applications in solar cells operating in an extraterrestrial situation. In this work, we systematically study the broadband near-infrared downconversion and upconversion of Yb3+-doped silicate, germanate, phosphate, tellurite and tungsten tellurite glasses. All samples show a broad excitation band in the 300-400 nm range, which is attributed to the charge transfer of the Yb3+-O2- couple. The position of the charge transfer band (CTB) shifts from 300 nm to longer wavelengths around 350 nm when the length of the R-O(Si, P, Ge, Te) increases. The longer R-O gives rise to a smaller central void for Yb3+, thus resulting in a small proportion of Yb3+ ions, thus leading to the blue-shift of the CTB. A smaller proportion of Yb3+ in silicate glasses causes in the strongest upconversion emission at 500 nm.

  13. Gain and noise figure enhancement of Er+3/Yb+3 co-doped fiber/Raman hybrid amplifier

    NASA Astrophysics Data System (ADS)

    Mahran, O.

    2016-02-01

    An Er/Yb co-doped fiber/Raman hybrid amplifier (HA) is proposed and studied theoretically and analytically to improve the gain and noise figure of optical amplifiers. The calculations are performed under a uniform dopant and steady-state conditions. The initial energy transfer efficiency for Er/Yb co-doped fiber amplifier (EYDFA) is introduced, while the amplified spontaneous emission (ASE) is neglected. The glass fiber used for both Er/Yb and Raman amplifiers is phosphate. Different pump powers are used for both EYDFA and RA with 1 μW input signal power, 1 m length of Er/Yb amplifier and 25 km length of Raman amplifier (RA). The proposed model is validated for Er/Yb co-doped amplifier and Raman amplifier separately by comparing the calculating results with the experimental data. A high gain and low noise figure at 200 mW Raman pump power and 500 mW Er/Yb pump power are obtained for the proposed HA as compared with the experimental results of EYDFA, Raman amplifier and the EDFA/Raman hybrid amplifier.

  14. Pump-induced phase aberrations in Yb3+-doped materials(Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Keppler, Sebastian; Tamer, Issa; Hornung, Marco; Körner, Jörg; Liebetrau, Hartmut; Hein, Joachim; Kaluza, Malte C.

    2017-05-01

    Optical pumping of laser materials is an effective way to create a population inversion necessary for laser operation. However, a fraction of the pump energy is always transfered as heat into the laser material, which is mainly caused by the quantum defect. For Yb3+-doped materials, the small energy difference between the pump level and the laser level and the pumping with narrowband high-power laser diodes result in a quantum defect of approx. 9%, which is significantly lower compared to other dopants e.g. Ti3+ (33%) or Nd3+ (24%). Due to the low heat introduction, high optical-to-optical efficiency and high repetition rate laser systems based on diode-pumping are well-suited for a number of applications. Here, however, laser beam quality is of crucial importance. Phase distortions and beam profile modulations can lead to optical damages as well as a significant reduction of the focal spot intensity. Pump-induced phase aberrations are the main cause for phase distortions of the amplified laser beam. The heat transferred to the material causes a change of the refractive index (dn/dT), thermal expansion and stress within the laser material, eventually leading to spatial phase aberrations (also called `thermal lens'). However, the spatially dependent distribution of the population inversion itself also leads to spatial phase aberrations. Since electron excitation directly leads to a change in the charge distribution of the laser active ions, the dynamic response of the material to external fields changes. These electronic phase aberrations (also called `population lens') are described by a change in the polarizability of the material. Due to the low quantum defect of Yb3+-doped materials, this effect becomes more important. We show the first comprehensive spatio-temporal characterization of the pump-induced phase aberration including both effects. A high-resolution interference measurement was carried out with time steps of 50µs for times during the pump period and

  15. Hyper-O-GlcNAcylation of YB-1 affects Ser102 phosphorylation and promotes cell proliferation in hepatocellular carcinoma

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Liu, Qingqing; Jiangsu Province Key Laboratory for Inflammation and Molecular Drug Target, Nantong University, 19 Qi-xiu Road, Nantong 226001, Jiangsu Province; Tao, Tao

    As an essential post-translational modification, O-GlcNAcylation has been thought to be able to modulate various nuclear and cytoplasmic proteins and is emerging as a key regulator of multiple biological processes, such as transcription, cell growth, signal transduction, and cell motility. Recently, authoritative glycomics analyses have reported extensive crosstalk between O-GlcNAcylation and phosphorylation, which always dynamically interplay with each other and regulate signaling, transcription, and other cellular processes. Also, plentiful studies have shown close correlation between YB-1 phosphorylation and tumorigenesis. Therefore, our study aimed to determine whether YB-1 was O-GlcNAc modified and whether such modification could interact with its phosphorylation duringmore » the process of HCC development. Western blot and immunohistochemistry were firstly conducted to reveal obvious up-regulation of YB-1, OGT and O-GlcNAc modification in HCC tissues. What is more, not only YB-1 was identified to be O-GlcNAcylated but hyper-O-GlcNAcylation was demonstrated to facilitate HCC cell proliferation in a YB-1 dependent manner. Moreover, we detected four specific O-GlcNAc sites and confirmed T126A to be the most effective mutant in HCC cell proliferation via close O-GlcNAcylation-phosphorylation interaction. Even more interestingly, we discovered that T126A-induced HCC cell retardation and subdued transcriptional activity of YB-1 could be partially reversed by T126A/S102E mutant. From all above, it is not difficult to find that glycosylated-YB-1 mainly enhanced cell proliferation through congenerous actions with YB-1 phosphorylation and thus played indispensable roles in fine-tuning cell proliferation and procession of HCC. - Highlights: • YB-1 and OGT are associated with HCC prognosis. • YB-1 is O-GlcNAc modified in HCC. • Hyper-O-GlcNAcylation promotes HCC cell proliferation in dependent of YB-1. • The proliferating role of O-GlcNAcylation is based on Ser

  16. Ultralow-threshold Yb(3+):SiO(2) glass laser fabricated by the solgel process.

    PubMed

    Ostby, Eric P; Yang, Lan; Vahala, Kerry J

    2007-09-15

    A Yb-doped silica microcavity laser on a silicon chip is fabricated from a solgel thin film. The high-Q micro-toroid cavity, which has a finesse of 10,000, is evanescently coupled to an optical fiber taper. We report a threshold of 1.8 microW absorbed power that is, to the best of our knowledge, the lowest published threshold to date for any Yb-doped laser. The effect of Yb(3+) concentration on laser threshold is experimentally quantified.

  17. Synthesis, structure, and luminescence properties of SrSiAl2O3N2:Eu(2+) phosphors for light-emitting devices and field emission displays.

    PubMed

    Wang, Xicheng; Zhao, Zhengyan; Wu, Quansheng; Li, Yanyan; Wang, Chuang; Mao, Aijun; Wang, Yuhua

    2015-06-28

    A series of SrSiAl2O3N2:Eu(2+) (0.005 ≤x≤ 0.05) phosphors were successfully synthesized through a pressureless, facile, and efficient solid state route. The crystal structure, band structure, and their photoluminescence and cathodoluminescence properties were investigated in detail. The phosphors exhibit rod shape morphology with a uniform Eu(2+) distribution. Under n-UV excitation the emission spectra shift from 477 to 497 nm with an increase of Eu(2+) concentration. The concentration quenching mechanism of Eu(2+) emission was dominated by the dipole-dipole interaction. The thermal stability is comparable to that of the commercial Ba2SiO4:Eu(2+) phosphor. The phosphor also exhibits high current saturation and high resistance under low voltage electron bombardment. All the results indicate that the SrSiAl2O3N2:Eu(2+) phosphors can be considered as candidates for application in both white LEDs and FEDs.

  18. Alumina Paste Layer as a Sublimation Suppression Barrier for Yb14MnSb11

    NASA Technical Reports Server (NTRS)

    Paik, Jong-Ah; Caillat, Thierry

    2010-01-01

    Sublimation is a major cause of degradation of thermoelectric power generation systems. Most thermoelectric materials tend to have peak values at the temperature where sublimation occurs. A sublimation barrier is needed that is stable at operating temperatures, inert against thermoelectric materials, and able to withstand thermal cycling stress. A porous alumina paste layer is suitable as a sublimation barrier for Yb14MnSb11. It can accommodate stress generated by the thermal expansion discrepancy between the suppression layer and thermoelectric materials. Sublimation suppression is achieved by filling pores naturally with YbO2, a natural byproduct of sublimation. YbO2 generated during the sublimation of Yb14MnSb11 fills the porous structure of the alumina paste, causing sublimation to decrease with time as the pores become filled.

  19. Single linearly polarized, widely and freely tunable two wavelengths Yb3+-doped fiber laser

    NASA Astrophysics Data System (ADS)

    Liu, Dongfeng; Wang, Chinhua

    2010-01-01

    We report a novel single linearly polarized, widely, freely and continuously tunable two wavelengths Yb3+-doped fiber laser. The laser generates stable arbitrary two wavelengths output between 1003.1 and 1080.7 nm peak wavelengths simultaneously with a 346.0 mW CW power by using polarization beam splitting (PBS) for separation of two wavelengths. Each lasing line shows a single polarization with a polarization extinction ratio of >20 dB under different pump levels. The central and the interval of the two wavelengths can be tuned smoothly and independently in the entire gain region of >70 nm of PM Yb3+-doped single mode fiber. Strongly enhanced polarization-hole burning (PHB) phenomena in polarization maintain (PM) Yb3+-doped fiber was observed in the tunable two wavelengths Yb3+-doped fiber laser.

  20. Synthesis, structure, and bonding of BaTl4. Size effects on encapsulation of cations in electron-poor metal networks.

    PubMed

    Dai, Jing-Cao; Gupta, Shalabh; Corbett, John D

    2011-01-03

    The synthesis, structure, and bonding of BaTl(4) are described [C2/m, Z = 4, a = 12.408(3), b = 5.351(1), c = 10.383(2) Å, β = 116.00(3)°]. Pairs of edge-sharing Tl pentagons are condensed to generate a network of pentagonal biprisms along b that encapsulate Ba atoms. Alternating levels of prisms along c afford six more bifunctional Tl atoms about the waists of the biprisms, giving Ba a coordination number of 16. Each Tl atom is bonded to five to seven other Tl atoms and to three to five Ba atoms. There is also strong evidence that Hg substitutes preferentially in the shared edges of the Tl biprisms in BaHg(0.80)Tl(3.20) to generate more strongly bound Hg(2) dimers. Cations that are too small relative to the dimensions of the surrounding polyanionic network make this BaTl(4) structure (and for SrIn(4) and perhaps EuIn(4) as well) one stable alternative to tetragonal BaAl(4)-type structures in which cations are bound in larger hexagon-faced nets, as for BaIn(4) and SrGa(4). Characteristic condensation and augmentation of cation-centered prismatic units is common among many relatively cation- and electron-poor, polar derivatives of Zintl phases gain stability. At the other extreme, the large family of Frank-Kasper phases in which the elements exhibit larger numbers of bonded neighbors are sometimes referred to as orbitally rich.

  1. Theoretical and empirical investigations of KCl:Eu2+ for nearly water-equivalent radiotherapy dosimetry

    PubMed Central

    Zheng, Yuanshui; Han, Zhaohui; Driewer, Joseph P.; Low, Daniel A.; Li, H. Harold

    2010-01-01

    Purpose: The low effective atomic number, reusability, and other computed radiography-related advantages make europium doped potassium chloride (KCl:Eu2+) a promising dosimetry material. The purpose of this study is to model KCl:Eu2+ point dosimeters with a Monte Carlo (MC) method and, using this model, to investigate the dose responses of two-dimensional (2D) KCl:Eu2+ storage phosphor films (SPFs). Methods: KCl:Eu2+ point dosimeters were irradiated using a 6 MV beam at four depths (5–20 cm) for each of five square field sizes (5×5–25×25 cm2). The dose measured by KCl:Eu2+ was compared to that measured by an ionization chamber to obtain the magnitude of energy dependent dose measurement artifact. The measurements were simulated using DOSXYZnrc with phase space files generated by BEAMnrcMP. Simulations were also performed for KCl:Eu2+ films with thicknesses ranging from 1 μm to 1 mm. The work function of the prototype KCl:Eu2+ material was determined by comparing the sensitivity of a 150 μm thick KCl:Eu2+ film to a commercial BaFBr0.85I0.15:Eu2+-based SPF with a known work function. The work function was then used to estimate the sensitivity of a 1 μm thick KCl:Eu2+ film. Results: The simulated dose responses of prototype KCl:Eu2+ point dosimeters agree well with measurement data acquired by irradiating the dosimeters in the 6 MV beam with varying field size and depth. Furthermore, simulations with films demonstrate that an ultrathin KCl:Eu2+ film with thickness of the order of 1 μm would have nearly water-equivalent dose response. The simulation results can be understood using classic cavity theories. Finally, preliminary experiments and theoretical calculations show that ultrathin KCl:Eu2+ film could provide excellent signal in a 1 cGy dose-to-water irradiation. Conclusions: In conclusion, the authors demonstrate that KCl:Eu2+-based dosimeters can be accurately modeled by a MC method and that 2D KCl:Eu2+ films of the order of 1 μm thick would have

  2. Strong Eu2+ light emission in Eu silicate through Eu3+ reduction in Eu2O3/Si multilayer deposited on Si substrates

    PubMed Central

    2013-01-01

    Eu2O3/Si multilayer nanostructured films are deposited on Si substrates by magnetron sputtering. Transmission electron microscopy and X-ray diffraction measurements demonstrate that multicrystalline Eu silicate is homogeneously distributed in the film after high-temperature treatment in N2. The Eu2+ silicate is formed by the reaction of Eu2O3 and Si layers, showing an intense and broad room-temperature photoluminescence peak centered at 610 nm. It is found that the Si layer thickness in nanostructures has great influence on Eu ion optical behavior by forming different Eu silicate crystalline phases. These findings open a promising way to prepare efficient Eu2+ materials for photonic application. PMID:23618344

  3. Structural and optical properties of novel surfactant-coated Yb@TiO2 nanoparticles

    NASA Astrophysics Data System (ADS)

    Calandra, P.; Lombardo, D.; Pistone, A.; Turco Liveri, V.; Trusso, S.

    2011-11-01

    In this paper a novel hybrid approach to synthesise composite nanoparticles is presented. It is based on the laser ablation of a bulk target (Yb) immersed in a reversed micellar solution which contains nanoparticles of a different host material (TiO2 nanoparticles) previously synthesised by chemical method. This approach thus exploits the advantages of the chemical synthesis through reversed micellar solution (size control, nanoparticle stabilisation), and of the laser ablation ("clean" synthesis, no side reactions). Central role is played by the microscopic processes controlling the deposition of the ablated Yb atoms onto the surface of TiO2 nanoparticles which actually behave as nucleation seeds. The structural features of the resulting Yb@TiO2 composite nanoparticles have been studied by Transmission Electron Microscopy, whereas their peculiar optical properties have been explored by UV-Vis spectroscopy and steady-state fluorescence. Results consistently show the formation of Yb and TiO2 glued nanodomains to form nearly spherical and non-interacting nanoparticles with enhanced photophysical properties.

  4. Influence of temperature on Yb:YAG/Cr:YAG microchip laser operation

    NASA Astrophysics Data System (ADS)

    Šulc, Jan; Eisenschreiber, Jan; Jelínková, Helena; Nejezchleb, Karel; Å koda, Václav

    2017-02-01

    The goal of this work was an investigation of the temperature influence (in range from 80 up to 320 K) on the laser properties of Yb:YAG/Cr:YAG Q-switched diode-pumped microchip laser. This laser was based on monolith crystal (diameter 3mm) which combines in one piece an active laser part (Yb:YAG crystal, 10 at.% Yb/Y, 3mm long) and saturable absorber (Cr:YAG crystal, 1.36mm long, initial transmission 90% @ 1031 nm). The laser resonator pump mirror (HT for pump radiation, HR for generated radiation) was directly deposited on the Yb:YAG monolith part. The output coupler with reflection 55% for the generated wavelength was placed on the Cr:YAG part. The microchip laser was placed in the temperature controlled cupreous holder inside vacuum chamber of the liquid nitrogen cryostat. For Yb:YAG part longitudinal pulsed pumping (pumping pulse length 2.5 ms, rep-rate 20 Hz, power amplitude 21W) a fibre coupled (core diameter 400 μm, NA= 0:22) laser diode, operating at wavelength 933 nm, was used. The microchip laser mean output power, pulse duration, repetition rate, emission wavelength, and laser beam profile were measured in dependence on temperature. The generated pulse length was in range from 2.2 ns to 1.1 ns (FWHM) with the minimum at 230 K. The single pulse energy was peaking (0.4 mJ) at 180 K. The highest peak power (325 kW) was obtained at 220 K. The highest pulse repetition rate (38 kHz) and output mean power (370mW) was reached for temperature 80 K.

  5. Updated level scheme of 172Yb from 171Yb(nth, γ) reaction studied via gamma-gamma coincidence spectrometer

    NASA Astrophysics Data System (ADS)

    Nguyen, Ngoc Anh; Nguyen, Xuan Hai; Pham, Dinh Khang; Nguyen, Quang Hung; Ho, Huu Thang

    2017-08-01

    This paper provides the updated information on the level scheme of 172Yb nucleus studied via 171Yb(nth, γ) reaction using the gamma-gamma coincidence spectrometer at Dalat Nuclear Research Institute (Viet Nam). The latter is used because of its advantages in achieving the low Compton background as well as in identifying the correlated gamma transitions. We have detected in total the energies and intensities of 128 two-step gamma cascades corresponding to 79 primary transitions. By comparing the measured data with those extracted from the ENSDF library, 61 primary gamma transitions and corresponding energy levels together with 20 secondary gamma transitions are found to be the same as the ENSDF data. Beside that, 18 additional primary gamma transitions and corresponding energy levels plus 108 secondary ones are not found to currently exist in this library and they are therefore considered as the new data.

  6. Diode-pumped Yb:Sr{sub 5}(PO{sub 4}){sub 3}F laser performance

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Marshall, C.D.; Payne, S.A.; Smith, L.K.

    The performance of the first diode-pumped Yb{sup 3+}-doped Sr{sub 5}(PO{sub 4}){sub 3}F (Yb:S-FAP) laser is discussed. We found the pumping dynamics and extraction cross-sections of Yb:S-FAP crystals to be similar to those previously inferred by purely spectroscopic techniques. The saturation fluence for pumping was measured to be 2.2 J/cm{sup 2} using three different methods based on either the spatial, temporal, or energy transmission properties of a Yb:S-FAP rod. The small signal gain implies an emission cross section of 6.0 x 10{sup -20} cm{sup 2} that falls within error bars of the previously reported value of 7.3 x 10{sup -20} cm{supmore » 2}, obtained from spectroscopic techniques. Up to 1.7 J/cm{sup 3} of stored energy density was achieved in a 6 x 6 x 44 mm Yb:S-FAP amplifier rod. An InGaAs diode array has been fabricated that has suitable specifications for pumping a 3 x 3 x 30 mm Yb:S-FAP rod. In a free running configuration diode-pumped slope efficiencies up to 43% were observed with output energies up to {approximately}0.5 J per 1 ms pulse. When the rod was mounted in a copper block for cooling, 13 W of average power was produced with power supply limited operation at 70 Hz and 500 {mu}s pulses.« less

  7. K(+)-Induced in situ self-assembly of near-infrared luminescent membrane material armored with bigger Yb(III) complex crystallites.

    PubMed

    Chen, Wanmin; Tang, Xiaoliang; Dou, Wei; Ju, Zhenghua; Xu, Benhua; Xu, Wenxuan; Liu, Weisheng

    2016-04-14

    A semi-rigid ligand could capture effectively Yb(3+) ions to form a stable Yb(3+) complex and provide a potential cavity to accommodate alkali metal ions. Only K(+) ions could induce the Yb(3+) complex to form a 1D coordination polymer and promote the in situ formation of an NIR membrane coated with bigger Yb(3+) complex crystallites under mild conditions.

  8. Growth and laser properties of Yb : Ca 4YO(BO 3) 3 crystal

    NASA Astrophysics Data System (ADS)

    Zhang, Huaijin; Meng, Xianlin; Zhu, Li; Wang, Pu; Liu, Xuesong; Cheng, Ruiping; Dawes, Judith; Dekker, Peter; Zhang, Shaojun; Sun, Lianke

    1999-04-01

    Yb : Ca 4YO(BO 3) 3 (Yb : YCOB) crystal has been grown by the Czochralski method. The absorption and fluorescence spectra have been measured. The green luminescence is also observed. The output laser at 1032 nm has been demonstrated pumped by laser diode (LD) at 976.4 nm.

  9. Life Testing of Yb14MnSb11 for High Performance Thermoelectric Couples

    NASA Technical Reports Server (NTRS)

    Paik, Jong-Ah; Brandon, Erik; Caillat, Thierry; Ewell, Richard; Fleurial, Jean-Pierre

    2011-01-01

    The goal of this study is to verify the long term stability of Yb14MnSb11 for high performance thermoelectric (TE) couples. Three main requirements need to be satisfied to ensure the long term stability of thermoelectric couples: 1) stable thermoelectric properties, 2) stable bonding interfaces, and 3) adequate sublimation suppression. The efficiency of the couple is primarily based on the thermoelectric properties of the materials selected for the couple. Therefore, these TE properties should exhibit minimal degradation during the operating period of the thermoelectric couples. The stability of the bonding is quantified by low contact resistances of the couple interfaces. In order to ensure high efficiency, the contact resistances of the bonding interfaces should be negligible. Sublimation suppression is important because the majority of thermoelectric materials used for power generation have peak figures of merit at temperatures where sublimation rates are high. Controlling sublimation is also essential to preserve the efficiency of the couple. During the course of this research, three different life tests were performed with Yb14MnSb11 coupons. TE properties of Yb14MnSb11 exhibited no degradation after 6 months of aging at 1273K, and the electrical contact resistance between a thin metallization layer and the Yb14MnSb11 remained negligible after 1500hr aging at 1273K. A sublimation suppression layer for Yb14MnSb11 was developed and demonstrated for more than 18 months with coupon testing at 1273K. These life test data indicate that thermoelectric elements based on Yb14MnSb11 are a promising technology for use in future high performance thermoelectric power generating couples.

  10. Interband Transitions, IR-Active Phonons, and Plasma Vibrations of Some Metal Hexaborides

    NASA Astrophysics Data System (ADS)

    Werheit, H.; Au, T.; Schmechel, R.; Paderno, Yu. B.; Konovalova, E. S.

    2000-10-01

    The high IR reflectivity of monocrystalline metallic metal hexaborides is superimposed by weak phonon spectra. The symmetry selection rules are lifted, probably because of structural defects. From the plasmon-phonon polariton frequencies in metallic LaB6 compared with those in semiconducting EuB6 and YbB6, the softening and the hardening of specific F1u modes by the free carriers are determined. From the plasma edges of EuB6 and YbB6, some parameters of the electronic transport are derived. The electron concentration increases proportional to the C content, whose donor properties are found to be comparable to those of hydrogen-like impurities. The existence of energy gaps in EuB6 and YbB6 proves that these compounds are semiconductors.

  11. Investigation of Thermal Conductivities and Expansion Coefficients of (Yb1 - x La x )2AlTaO7 Ceramics

    NASA Astrophysics Data System (ADS)

    Xiaoge, Chen; Hongsong, Zhang; Sai, Su; Yongde, Zhao; An, Tang; Haoming, Zhang

    2017-12-01

    The (Yb1 - x La x )2AlTaO7 ( x = 0, 0.1, 0.3, 0.5) ceramics were prepared by solid-state reaction method. The phase composition, microstructure, thermophysical properties of (Yb1 - x La x )2AlTaO7 ceramics were investigated. Results reveal that (Yb1 - x La x )2AlTaO7 ( x = 0, 0.1, 0.3) ceramics exhibit a single pyrochlore-type structure, and the (Yb0.5La0.5)2AlTaO7 has an orthorhombic weberite structure. The thermal conductivities of (Yb1 - x La x )2AlTaO7 ( x = 0, 0.1, 0.3) ceramics decrease with increasing Yb2O3 contents. (Yb0.5La0.5)2AlTaO7 has the highest thermal conductivity among all the ceramics studied, within the range of 1.48-1.75 W/m K (20-1200 °C). The thermal expansion coefficients of (Yb1 - x La x )2AlTaO7 ceramics decrease gradually with increasing La2O3 fractions, and the thermal expansion coefficients are close to those of YSZ.

  12. High-performance n-type Yb xCo 4Sb 12: from partially filled skutterudites towards composite thermoelectrics

    DOE PAGES

    Wang, Shanyu; Salvador, James R.; Yang, Jiong; ...

    2016-07-01

    The filling fraction limit (FFL) of skutterudites, that is, the complex balance of formation enthalpies among different species, is an intricate but crucial parameter for achieving high thermoelectric performance. In this work, we synthesized a series of Yb xCo 4Sb 12 samples with x=0.2–0.6 and systemically studied the FFL of Yb, which is still debated even though this system has been extensively investigated for decades. Our combined experimental efforts of X-ray diffraction, microstructural and quantitative compositional analyses clearly reveal a Yb FFL of ~0.29 in CoSb 3, which is consistent with previous theoretical calculations. For the excess Yb in samplesmore » with x>0.35 mainly form metallic YbSb 2 precipitates, the Fermi level increases significantly and thus increases the electrical conductivity and decreasing the Seebeck coefficient. Our result is further corroborated by the numerical calculations based on the Bergman’s composite theory, which accurately reproduces the transport properties of the x>0.35 samples based on nominal Yb 0.35Co 4Sb 12 and YbSb 2 composites. A maximum ZT of 1.5 at 850 K is achieved for Yb 0.3Co 4Sb 12, which is the highest value for a single-element-filled CoSb 3. The high ZT originates from the high-power factor (in excess of 50 μW cm -K -2) and low lattice thermal conductivity (well below 1.0 W m -K -1). More importantly, the large average ZTs, for example, ~1.05 for 300–850 K and ~1.27 for 500–850 K, are comparable to the best values for n-type skutterudites. The high thermoelectric and thermomechanical performances and the relatively low air and moisture sensitivities of Yb make Yb-filled CoSb 3, a promising candidate for large-scale power generation applications.« less

  13. Crystal structure, electronic structure, optical and scintillation properties of self-activated Cs 4YbI 6 [Crystal structure, optical and scintillation properties of self-activated Cs 4YbI 6

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Wu, Yuntao; Chakoumakos, Bryan C.; Shi, Hongliang

    A self-activated Cs 4YbI 6 single crystal was grown by the vertical Bridgman method. Crystal structure refinements verified the phase purity and the trigonal crystal system with a space group of more » $$\\bar{R}$$3 c. By using differential scanning calorimetry, the melting and crystallization points were determined to be 550 and 510 °C, respectively. Luminescence and scintillation properties were systematically studied. Upon ultraviolet light (360 nm) excitation, the Cs 4YbI 6 crystal exhibits bluish-green emission centered at 450 and 480 nm due to spin-allowed and spin-forbidden transitions of Yb 2+ activators. The lifetimes of the corresponding emission bands at room temperature are tens and hundreds of nanoseconds, respectively. X-ray excited radioluminescence spectrum is dominated by the spin-forbidden transition of Yb 2+ at 480 nm. The absolute light yield is 2700 ± 200 photons/MeV with a principal scintillation decay time of 33 ns. In conclusion, the physical explanation for the low light yield observed is proposed from experimental and theoretical insights.« less

  14. Crystal structure, electronic structure, optical and scintillation properties of self-activated Cs 4YbI 6 [Crystal structure, optical and scintillation properties of self-activated Cs 4YbI 6

    DOE PAGES

    Wu, Yuntao; Chakoumakos, Bryan C.; Shi, Hongliang; ...

    2018-05-14

    A self-activated Cs 4YbI 6 single crystal was grown by the vertical Bridgman method. Crystal structure refinements verified the phase purity and the trigonal crystal system with a space group of more » $$\\bar{R}$$3 c. By using differential scanning calorimetry, the melting and crystallization points were determined to be 550 and 510 °C, respectively. Luminescence and scintillation properties were systematically studied. Upon ultraviolet light (360 nm) excitation, the Cs 4YbI 6 crystal exhibits bluish-green emission centered at 450 and 480 nm due to spin-allowed and spin-forbidden transitions of Yb 2+ activators. The lifetimes of the corresponding emission bands at room temperature are tens and hundreds of nanoseconds, respectively. X-ray excited radioluminescence spectrum is dominated by the spin-forbidden transition of Yb 2+ at 480 nm. The absolute light yield is 2700 ± 200 photons/MeV with a principal scintillation decay time of 33 ns. In conclusion, the physical explanation for the low light yield observed is proposed from experimental and theoretical insights.« less

  15. CW and tunable performances of Yb3+:LuAG transparent ceramics with different doping concentrations

    NASA Astrophysics Data System (ADS)

    Ma, Chaoyang; Zhu, Jiangfeng; Liu, Kai; Wen, Zicheng; Ma, Ran; Long, Jiaqi; Yuan, Xuanyi; Cao, Yongge

    2017-07-01

    We report the CW laser operation and wavelength tunability of 10 at%, 15 at% and 20 at% Yb3+-doping LuAG ceramics pumped at 970 nm. The absorption saturation effects were taken into account herein. For 10 at% Yb3+-doping sample, the maximum slop efficiency and output power was 60.7% and 1.8 W, respectively. Furthermore, the slop efficiencies of 52.3% (15 at%) and 46.5% (20 at%) were reported. What's more, the maximum optical-to-optical efficiency for our samples was determined to be 40.1%, 36.8%, and 33.1% at the incident pump power of 4 W, respectively. The round-trip cavity loss of the laser system based on our Yb3+:LuAG ceramics were evaluated. The tuning curve of a 20 at% Yb3+:LuAG ceramic extended from 1018 nm up to 1062 nm, and that of 10 at% and 15 at% samples became much more broader, making Yb3+:LuAG ceramics possible candidates for ultrashort pulse generation.

  16. Composite Yb:YAG/SiC-prism thin disk laser.

    PubMed

    Newburgh, G A; Michael, A; Dubinskii, M

    2010-08-02

    We report the first demonstration of a Yb:YAG thin disk laser wherein the gain medium is intracavity face-cooled through bonding to an optical quality SiC prism. Due to the particular design of the composite bonded Yb:YAG/SiC-prism gain element, the laser beam impinges on all refractive index interfaces inside the laser cavity at Brewster's angles. The laser beam undergoes total internal reflection (TIR) at the bottom of the Yb(10%):YAG thin disk layer in a V-bounce cavity configuration. Through the use of TIR and Brewster's angles, no optical coatings, either anti-reflective (AR) or highly reflective (HR), are required inside the laser cavity. In this first demonstration, the 936.5-nm diode pumped laser performed with approximately 38% slope efficiency at 12 W of quasi-CW (Q-CW) output power at 1030 nm with a beam quality measured at M(2) = 1.5. This demonstration opens up a viable path toward novel thin disk laser designs with efficient double-sided room-temperature heatsinking via materials with the thermal conductivity of copper on both sides of the disk.

  17. Thermal Conductivity and Expansion Coefficient of (Sm1- x Yb x )2Ce2O7 Ceramics for Thermal Barrier Coatings

    NASA Astrophysics Data System (ADS)

    Xiaoge, Chen; Hongsong, Zhang; Kun, Sun; Xudan, Dang; Haoming, Zhang; Bo, Ren; An, Tang

    2017-12-01

    In the current paper, the (Sm1- x Yb x )2Ce2O7 ceramics were prepared via sol-gel and high-temperature solid reaction methods. The phase composition, microstructure, thermal conductivity, and expansion coefficient were investigated. Results indicate that pure (Sm1- x Yb x )2Ce2O7 ceramics with single defect-fluorite structure are synthesized successfully. Owing to the phonon scattering caused by Yb addition, the thermal conductivity of (Sm1- x Yb x )2Ce2O7 ceramics decreases with increasing Yb2O3 content at identical temperatures, which is lower than that of YSZ. Due to the relatively low ionic radius of Yb3+ ions, the addition of Yb2O3 decreases the thermal expansion coefficient of (Sm1- x Yb x )2Ce2O7 ceramics, which is higher than that of 8YSZ. The synthesized (Sm1- x Yb x )2Ce2O7 ceramics can be explored as candidate materials for thermal barrier coatings.

  18. Multimodal emissions from Tb{sup 3+}/Yb{sup 3+} co-doped lithium borate glass: Upconversion, downshifting and quantum cutting

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Bahadur, A.; Yadav, R.S.; Yadav, R.V.

    This paper reports the optical properties of Tb{sup 3+}/Yb{sup 3+} co-doped lithium borate (LB) glass prepared by melt quench method. The absorption spectrum of the Yb{sup 3+} doped LB glass contains intense NIR band centered at 976 nm due to {sup 2}F{sub 7/2}→{sup 2}F{sub 5/2} transition. The emission spectra of the prepared glasses have been monitored on excitation with 266, 355 and 976 nm. The Yb{sup 3+} doped glass emits a broad NIR band centered at 976 nm whereas the Tb{sup 3+} doped glass gives off visible bands on excitations with 266 and 355 nm. When the Tb{sup 3+} andmore » Yb{sup 3+} ions are co-doped together, the emission intensity in the visible region decreases whereas it increases in the NIR region significantly. The increase in the emission intensity in the NIR region is due to efficient cooperative energy transfer (CET) from Tb{sup 3+} to Yb{sup 3+} ions. The quantum cutting efficiency for Tb{sup 3+}/Yb{sup 3+} co-doped glass has been calculated and compared for 266 and 355 nm excitations. The quantum cutting efficiency is larger for 355 nm excitation (137%). The Tb{sup 3+}/Yb{sup 3+} co-doped LB glass also emits upconverted visible bands on excitation with 976 nm. The mechanisms involved in the energy transfer have been discussed using schematic energy level diagram. The Tb{sup 3+}/Yb{sup 3+} co-doped LB glass may be used in the optical devices and in solar cell for solar spectral conversion and behaves as a multi-modal photo-luminescent material. - Graphical abstract: The Tb{sup 3+}/Yb{sup 3+} co-doped lithium borate (LB) glass prepared by melt quench method emits upconverted visible emissions through upconversion CET from Yb{sup 3+} to Tb{sup 3+} ions and quantum cutting emissions through downconversion CET from Tb{sup 3+} to Yb{sup 3+} ions. Therefore, the Tb{sup 3+}/Yb{sup 3+} co-doped LB glass may find applications in optical devices and solar cell and behaves as a multi-modal photo-luminescent material. - Highlights: • The Tb{sup 3

  19. A dosimetric comparison of {sup 169}Yb versus {sup 192}Ir for HDR prostate brachytherapy

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Lymperopoulou, G.; Papagiannis, P.; Sakelliou, L.

    2005-12-15

    For the purpose of evaluating the use of {sup 169}Yb for prostate High Dose Rate brachytherapy (HDR), a hypothetical {sup 169}Yb source is assumed with the exact same design of the new microSelectron source replacing the {sup 192}Ir active core by pure {sup 169}Yb metal. Monte Carlo simulation is employed for the full dosimetric characterization of both sources and results are compared following the AAPM TG-43 dosimetric formalism. Monte Carlo calculated dosimetry results are incorporated in a commercially available treatment planning system (SWIFT{sup TM}), which features an inverse treatment planning option based on a multiobjective dose optimization engine. The qualitymore » of prostate HDR brachytherapy using the real {sup 192}Ir and hypothetical {sup 169}Yb source is compared in a comprehensive analysis of different prostate implants in terms of the multiobjective dose optimization solutions as well as treatment quality indices such as Dose Volume Histograms (DVH) and the Conformal Index (COIN). Given that scattering overcompensates for absorption in intermediate photon energies and distances in the range of interest to prostate HDR brachytherapy, {sup 169}Yb proves at least equivalent to {sup 192}Ir irrespective of prostate volume. This has to be evaluated in view of the shielding requirements for the {sup 169}Yb energies that are minimal relative to that for {sup 192}Ir.« less

  20. Diode-Pumped Narrow Linewidth Multi-kW Metalized Yb Fiber Amplifier

    DTIC Science & Technology

    2016-10-01

    multi-kW Yb fiber amplifier in a bi-directional pumping configuration. Each pump outputs 2 kW in a 200 µm, 0.2 NA multi-mode fiber. Gold -coated...multi-mode instability, with 90% O-O efficiency 12 GHz Linewidth and M2 < 1.15. OCIS codes: (140.3510) Lasers , fiber; (140.3615) Lasers , ytterbium...060.2430) Fibers, single-mode. 1. INTRODUCTION Yb-doped fiber laser has experienced exponential growth over the past decade. The output power

  1. Development of cryogenic Yb:YAG ceramics amplifier for over 100 J DPSSL

    NASA Astrophysics Data System (ADS)

    Sekine, T.; Takeuchi, Y.; Kurita, T.; Hatano, Y.; Muramatsu, Y.; Mizuta, Y.; Kabeya, Y.; Tamaoki, Y.; Kato, Y.

    2017-02-01

    A high gain cryogenic Yb:YAG ceramics laser amplifier for a high energy laser amplification system has been developed. The laser system consists of a fiber oscillator and two stage LD pumped cryogenic Yb:YAG ceramic amplifiers. The preamplifier stage has a 5-pass laser amplifier head and the main amplifier stage has a 2-pass laser amplifier head, respectively. The preamplifier obtained an average stored energy density of 0.836 J/cc and small-signal gain (SSG) of 60 with 33 J of stored energy. Then about 1 μJ of input energy from the oscillator was amplified to 3.6 J. The main amplifier head had four pumping LD modules which irradiated the Yb:YAG ceramics directly. This original angular pumping scheme ideally increases irradiation intensity and homogenizes irradiation pattern on the Yb:YAG ceramics due to superposition effect of all of the LD modules. A maximum peak power of over 100 kW was generated by one LD module. When the output energy of the LD modules was 450 J, a 20 of SSG at single pass was obtained. Stored energy density was evaluated to 0.429 J/cc when 148 J energy was stored in 346 cc of Yb:YAG ceramics. As a result, a 55-J output energy with 10 ns pulse duration was demonstrated at a pumping energy of 450 J. The optical-tooptical conversion efficiency which includes transmissivity of the LD modules was 12 %. The extraction efficiency was estimated to 37%.

  2. Morphology and orientation of β-BaB{sub 2}O{sub 4} crystals patterned by laser in the inside of samarium barium borate glass

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Nishii, Akihito; Shinozaki, Kenji; Honma, Tsuyoshi

    Nonlinear optical β-BaB{sub 2}O{sub 4} crystal lines (β-BBO) were patterned in the inside of 8Sm{sub 2}O{sub 3}–42BaO–50B{sub 2}O{sub 3} glass by irradiations of continuous-wave Yb:YVO{sub 4} lasers with a wavelength of 1080 nm (power: P=0.8–1.0 W, scanning speed: S=0.2–2.5 μm/s), in which the laser focal position was moved gradually from the surface to the inside. The morphology, size, and orientation of β-BBO crystals were examined from polarization optical microscope and birefringence imaging observations. It was demonstrated that c-axis oriented β-BBO crystals with long lengths (e.g., 20 mm) were patterned in the inside of the glass. The morphology of β-BBO inmore » the cross-section of lines was a rectangular shape with rounded corners, and the volume of β-BBO formed increased with increasing laser power and with decreasing laser scanning speed. The maximum depth in the inside from the surface for β-BBO patterning increased with increasing laser power, e.g., D{sub max}∼100 μm at P=0.8 W, D{sub max}∼170 μm at P=0.9 W, and D{sub max}∼200 μm at P=1 W. The present study proposes that the laser-induced crystallization opens a new door for applied engineering in glassy solids. - Graphical abstract: This figure shows the POM photographs for β-BaB{sub 2}O{sub 4} crystal lines patterned by cw Yb:YVO{sub 4} fiber laser irradiations with a laser power of P=0.8 W and a laser scanning speed S=2 μm/s in the glass. The laser focal point was moved gradually from the surface into the inside. The results shown in Fig. 1 demonstrate that it is possible to pattern highly oriented β-BaB{sub 2}O{sub 4} crystals even in the inside of glasses. - Highlights: • β-BaB{sub 2}O{sub 4} crystal lines were patterned in the inside of a glass by lasers. • Laser focal position was moved gradually from the surface to the inside. • Birefringence imaging was observed. • Morphology, size, and orientation of crystals were clarified. • Crystal lines with long

  3. YB-1 regulates tiRNA-induced Stress Granule formation but not translational repression

    PubMed Central

    Lyons, Shawn M.; Achorn, Chris; Kedersha, Nancy L.; Anderson, Paul J.; Ivanov, Pavel

    2016-01-01

    Stress-induced angiogenin (ANG)-mediated tRNA cleavage promotes a cascade of cellular events that starts with production of tRNA-derived stress-induced RNAs (tiRNAs) and culminates with enhanced cell survival. This stress response program relies on a subset tiRNAs that inhibit translation initiation and induce the assembly of stress granules (SGs), cytoplasmic ribonucleoprotein complexes with cytoprotective and pro-survival properties. SG-promoting tiRNAs bear oligoguanine motifs at their 5′-ends, assemble G-quadruplex-like structures and interact with the translational silencer YB-1. We used CRISPR/Cas9-based genetic manipulations and biochemical approaches to examine the role of YB-1 in tiRNA-mediated translational repression and SG assembly. We found that YB-1 directly binds to tiRNAs via its cold shock domain. This interaction is required for packaging of tiRNA-repressed mRNAs into SGs but is dispensable for tiRNA-mediated translational repression. Our studies reveal the functional role of YB-1 in the ANG-mediated stress response program. PMID:27174937

  4. Spectroscopy of Yb-doped tungsten-tellurite glass and assessment of its lasing properties

    NASA Astrophysics Data System (ADS)

    Merzliakov, M. A.; Kouhar, V. V.; Malashkevich, G. E.; Pestryakov, E. V.

    2018-01-01

    Glasses of the TeO2-WO3-Yb2O3 system are synthesized for wide range of Yb3+ concentrations of up to 6.0 × 1021 ions/cm3. The spectral-luminescent properties of lightly doped samples are investigated at room temperature and at the boiling point of liquid nitrogen. The energies of the Stark levels of the ground and excited states of Yb3+ ions incorporated into tungsten-tellurite glass are determined by analyzing the low-temperature spectra. The absorption, emission, and gain cross section spectra are obtained. The excess of the measured fluorescence decay time over the radiative lifetime ∼0.3 ms derived from the absorption spectra is attributed to the reabsorption effect in bulk samples. Measurements of lightly doped glass powder in the immersion liquid are made to reduce the effect of reabsorption. The fluorescence decay time of the powder is very close to the calculated radiative lifetime. Compared with phosphate, silicate, and other Yb3+-doped glasses, the tungsten-tellurite glass has a promising potential as a gain medium for lasers and amplifiers.

  5. Luminescence properties of Y2O3:Bi3+, Yb3+ co-doped phosphor for application in solar cells

    NASA Astrophysics Data System (ADS)

    Lee, E.; Kroon, R. E.; Terblans, J. J.; Swart, H. C.

    2018-04-01

    Bismuth (Bi3+) and ytterbium (Yb3+) co-doped yttrium oxide (Y2O3) phosphor powder was successfully synthesised using the co-precipitation technique. The X-ray diffraction (XRD) patterns confirmed that a single phase cubic structure with a Ia-3 space group was formed. The visible emission confirmed the two symmetry sites, C2 and S6, found in the Y2O3 host material and revealed that Bi3+ ions preferred the S6 site as seen the stronger emission intensity. The near-infrared (NIR) emission of Yb3+ increased significantly by the presence of the Bi3+ ions when compared to the singly doped Y2O3:Yb3+ phosphor with the same Yb3+ concentration. An increase in the NIR emission intensity was also observed by simply increasing the Yb3+ concentration in the Y2O3:Bi3+, Yb3+ phosphor material where the intensity increased up to x = 5.0 mol% of Yb3+ before decreasing due to concentration quenching.

  6. Tuning the Kondo effect in Yb(Fe 1-xCo x) 2Zn 20

    DOE PAGES

    Kong, Tai; Taufour, Valentin; Bud'ko, Sergey L.; ...

    2017-04-03

    We study the evolution of the Kondo effect in heavy fermion compounds, Yb(Fe 1-xCo x) 2Zn 20 (0 ≲ x ≲ 1), by means of temperature-dependent electric resistivity and speci c heat. The ground state of YbFe 2Zn 20 can be well described by a Kondo model with degeneracy N = 8 and a T K ~30 K. In the presence of a very similar total CEF splitting with YbFe 2Zn 20, the ground state of YbCo 2Zn 20 is close to a Kondo state with degeneracy N = 2 and a much lower TK ~ 2 K. Upon Comore » substitution, the coherence temperature of YbFe 2Zn 20 is suppressed, accompanied by an emerging Schottky-like feature in speci c heat associated with the thermal depopulation of CEF levels upon cooling. For 0.4 ≲ x ≲ 0.9, the ground state remains roughly the same which can be qualitatively understood by Kondo effect in the presence of CEF splitting. There is no clear indication of Kondo coherence observable in resistivity within this substitution range down to 500 mK. The coherence re-appears at around x≳ 0.9 and the coherence temperature increases with higher Co concentration levels.« less

  7. Thermal and electron transport studies on the valence fluctuating compound YbNiAl4

    NASA Astrophysics Data System (ADS)

    Falkowski, M.; Kowalczyk, A.

    2018-05-01

    We report the thermoelectric power S and thermal conductivity κ measurements on the valence fluctuating compound YbNiAl4, furthermore taking into account the impact of the applied magnetic field. We discuss our new results with revisiting the magnetic [χ(T)], transport [ρ(T)], and thermodynamic [Cp(T)] properties in order to better understand the phenomenon of thermal and electron transport in this compound. The field dependence of the magnetoresistivity data is also given. The temperature dependence of thermoelectric power S(T) was found to exhibit a similar behaviour as expected for Yb-based compounds with divalent or nearly divalent Yb ions. In addition, the values of total thermal conductivity as a function of temperature κ(T) of YbNiAl4 are fairly low compared to those of pure metals which may be linked to the fact that the conduction band is perturbed by strong hybridization. A deeper analysis of the specific heat revealed the low-T anomaly of the ratio Cp(T)/T3, most likely associated with the localized low-frequency oscillators in this alloy. In addition, the Kadowaki-Woods ratio and the Wilson ratio are discussed with respect to the electronic correlations in YbNiAl4.

  8. Strength improvement and purification of Yb 2Si 2O 7-SiC nanocomposites by surface oxidation treatment

    DOE PAGES

    Nguyen, Son T.; Nakayama, Tadachika; Suematsu, Hisayuki; ...

    2017-04-03

    A two-step processing was developed to prepare Yb 2Si 2O 7-SiC nanocomposites. Yb 2Si 2O 7-Yb 2SiO 5-SiC composites were first fabricated by a solid state reaction/hot-pressing method. The composites were then annealed at 1250°C in air for 2 h to activate the oxidation of SiC, which effectively transformed the Yb 2SiO 5 into Yb 2Si 2O 7. The surface cracks purposely induced can be fully healed during the oxidation treatment. The treated composites have improved flexural strength compared to their pristine composites. As a result, the mechanism for crack-healing and silicate transformation have been proposed and discussed in detail.

  9. Yb3+/Ho3+ Co-Doped Apatite Upconversion Nanoparticles to Distinguish Implanted Material from Bone Tissue.

    PubMed

    Li, Xiyu; Chen, Haifeng

    2016-10-07

    The exploration of bone reconstruction with time requires the combination of a biological method and a chemical technique. Lanthanide Yb 3+ and Ho 3+ co-doped fluorapatite (FA:Yb 3+ /Ho 3+ ) and hydroxyapatite (HA:Yb 3+ /Ho 3+ ) particles with varying dopant concentrations were prepared by hydrothermal synthesis and thermal activation. Controllable green and red upconversion emissions were generated under 980 nm near-infrared excitation; the FA:Yb 3+ /Ho 3+ particles resulted in superior green luminescence, while HA:Yb 3+ /Ho 3+ dominated in red emission. The difference in the green and red emission behavior was dependent on the lattice structure and composition. Two possible lattice models were proposed for Yb 3+ /Ho 3+ co-doped HA and FA along the hydroxyl channel and fluorine channel of the apatite crystal structure. We first reported the use of the upconversion apatite particles to clearly distinguish implanted material from bone tissue on stained histological sections of harvested in vivo samples. The superposition of the tissue image and material image is a creative method to show the material-tissue distribution and interrelation. The upconversion apatite particles and image superposition method provide a novel strategy for long-term discriminable fluorescence tracking of implanted material or scaffold during bone regeneration.

  10. Single frequency 1560nm Er:Yb fiber amplifier with 207W output power and 50.5% slope efficiency

    NASA Astrophysics Data System (ADS)

    Creeden, Daniel; Pretorius, Herman; Limongelli, Julia; Setzler, Scott D.

    2016-03-01

    High power fiber lasers/amplifiers in the 1550nm spectral region have not scaled as rapidly as Yb-, Tm-, or Ho-doped fibers. This is primarily due to the low gain of the erbium ion. To overcome the low pump absorption, Yb is typically added as a sensitizer. Although this helps the pump absorption, it also creates a problem with parasitic lasing of the Yb ions under strong pumping conditions, which generally limits output power. Other pump schemes have shown high efficiency through resonant pumping of erbium only without the need for Yb as a sensitizer [1-2]. Although this can enable higher power scaling due to a decrease in the thermal loading, resonant pumping methods require long fiber lengths due to pump bleaching, which may limit the power scaling which can be achieved for single frequency output. By using an Er:Yb fiber and pumping in the minima of the Yb pump absorption at 940nm, we have been able to simultaneously generate high power, single frequency output at 1560nm while suppressing the 1-micron ASE and enabling higher efficiency compared to pumping at the absorption peak at 976nm. We have demonstrated single frequency amplification (540Hz linewidth) to 207W average output power with 49.3% optical efficiency (50.5% slope efficiency) in an LMA Er:Yb fiber. We believe this is the highest reported efficiency from a high power 9XXnm pumped Er:Yb-doped fiber amplifier. This is significantly more efficient that the best-reported efficiency for high power Er:Yb doped fibers, which, to-date, has been limited to ~41% slope efficiency [3].

  11. Comparing Yb-fiber and Ti:Sapphire lasers for depth resolved imaging of human skin (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Balu, Mihaela; Saytashev, Ilyas; Hou, Jue; Dantus, Marcos; Tromberg, Bruce J.

    2016-02-01

    We report on a direct comparison between Ti:Sapphire and Yb fiber lasers for depth-resolved label-free multimodal imaging of human skin. We found that the penetration depth achieved with the Yb laser was 80% greater than for the Ti:Sapphire. Third harmonic generation (THG) imaging with Yb laser excitation provides additional information about skin structure. Our results indicate the potential of fiber-based laser systems for moving into clinical use.

  12. Lattice instability and enhancement of superconductivity in YB6

    NASA Astrophysics Data System (ADS)

    Sluchanko, N.; Glushkov, V.; Demishev, S.; Azarevich, A.; Anisimov, M.; Bogach, A.; Voronov, V.; Gavrilkin, S.; Mitsen, K.; Kuznetsov, A.; Sannikov, I.; Shitsevalova, N.; Filipov, V.; Kondrin, M.; Gabáni, S.; Flachbart, K.

    2017-10-01

    The superconducting and normal state characteristics of yttrium hexaboride (YB6) have been investigated for the single crystals with a transition temperatures Tc ranging between 4.2 K and 7.6 K. The extracted set of microscopic parameters [the coherence length ξ (0 )˜320 -340 Å , the penetration depth λ (0 )˜1100 -3250 Å and the mean free path of charge carriers l =11 -58 Å , the Ginzburg-Landau-Maki parameters κ1 ,2(0 ) ˜3.3 -9.5, and the superconducting gap Δ (0 )˜6.2 -14.8 K] confirms the type II superconductivity in "dirty limit" (ξ ≫l ) with a medium to strong electron-phonon interaction (the electron-phonon interaction constant λe -ph=0.32 -0.96 ) and s -type pairing of charge carriers in this compound [2 Δ (0 ) /kBTc≈3 -4]. The comparative analysis of charge transport (resistivity, Hall and Seebeck coefficients) and thermodynamic (heat capacity, magnetization) properties in the normal state in YB6 allowed to assume a transition into the cage-glass state at T*˜50 K with a static disorder in the arrangement of the Y3 + ions. We argue that the significant Tc variations in YB6 single crystals are determined by two main factors: (i) the superconductivity enhancement is related with the increase of the number of vacancies, both at yttrium and boron sites, leading to nonstoichiometric composition, which is accompanied by the enhancement of electron-phonon interaction in the hexaboride lattice; (ii) stronger Tc depression is observed in near stoichiometric and more dense crystals and it is induced by the development of bcc lattice instability producing strong distortion, disordering, and formation of defect complexes in the matrix of YB6.

  13. Spin re-orientation in heavy fermion system α - YbAl1 - x FexB4

    NASA Astrophysics Data System (ADS)

    Wu, Shan; Broholm, C.; Kuga, K.; Suzuki, Shintaro; Nakatsuji, S.; Mourigal, M.; Stone, M.; Tian, Wei; Qiu, Y.; Rodriguez-Rivera, Jose

    Non centro-symmetric α - YbAlB4 has a heavy Fermi liquid ground state and shares many characteristics with centro-symmetric β - YbAlB4 . Both isomorphs display intermediate valence, associated with a fluctuation scale of T0 = 200 K and a Kondo lattice scale of T* = 8 K. Unlike β - YbAlB4 , α - YbAlB4 is at the boundary of a transition from a Fermi liquid metallic state to an antiferromagnetic (AFM) insulating state, driven by Fe substitution of Al. Magnetization and specific heat measurements reveal two different antiferromagnetic phases with TN = 9 K and TN = 2 K for Fe concentration above and below x =0.07. We report single crystal neutron scattering experiments on Fe doped YbAlB4 with x =0.035 and x =0.125. While the ordering wave vector is identical, k -> = (1 , 0 , 0) , the spin orientation switches from c to a with increasing Fe concentration. This suggests different anisotropic hybridization between 4f and conduction electrons that we confirmed by determining the crystal field levels. Supported by DOE, BES through DE-FG02-08ER46544.

  14. DOE Office of Scientific and Technical Information (OSTI.GOV)

    Cho, Young-Sik; Huh, Young-Duk, E-mail: ydhuh@dankook.ac.kr

    Highlights: • Red-emitting BaWO{sub 4}:Eu phosphors were prepared in hexane-water bilayer system. • The hydrophobic nanometer-sized BaWO{sub 4}:Eu phosphors were obtained in hexane. • The hydrophilic micrometer-sized BaWO{sub 4}:Eu dendrites were obtained in water. - Abstract: BaWO{sub 4}:Eu phosphors were prepared by performing a solvothermal reaction in a water–hexane bilayer system. A barium oleate (and europium oleate) complex was obtained in hexane via a phase transfer reaction involving Ba{sup 2+} (and Eu{sup 3+}) ions in an aqueous solution of sodium oleate. The outer surfaces of the nanometer-sized BaWO{sub 4}:Eu phosphors were capped by the long alkyl chain of oleate; therefore,more » the hydrophobic nanometer-sized BaWO{sub 4}:Eu phosphors preferentially dissolved in the hexane layer. The micrometer-sized BaWO{sub 4}:Eu phosphors were obtained in the water layer. The BaWO{sub 4}:Eu phosphors prepared in hexane and water yielded sharp strong absorption and emission peaks at 464 and 615 nm, respectively, due to the {sup 7}F{sub 0} → {sup 5}D{sub 2} and the {sup 5}D{sub 0} →{sup 7} F{sub 2} transitions of the Eu{sup 3+} ions. The BaWO{sub 4}:Eu phosphors are good candidate red-emitting phosphors for use in InGaN blue-emitting diodes, which have an emission wavelength of 465 nm.« less

  15. Microwave hydrothermal synthesis and upconversion properties of Yb3+/Er3+ doped YVO4 nanoparticles

    NASA Astrophysics Data System (ADS)

    Kshetri, Yuwaraj K.; Regmi, Chhabilal; Kim, Hak-Soo; Wohn Lee, Soo; Kim, Tae-Ho

    2018-05-01

    Yb3+ and Er3+ doped YVO4 (Yb3+/Er3+:YVO4) nanoparticles with highly efficient near-infrared to visible upconversion properties have been synthesized by microwave hydrothermal process. Uniform-sized Yb3+/Er3+:YVO4 nanoparticles were synthesized within 1 h at 140 °C which is relatively faster than the conventional hydrothermal process. Under 980 nm laser excitation, strong green and less strong red emissions are observed which are attributed to 2H11/2, 4S3/2 to 4I15/2 and 4F9/2 to 4I15/2 transitions of Er3+ respectively. The emission intensity is found to depend strongly on the concentration of Yb3+. The quadratic dependence of upconversion intensity on the excitation power indicates that the upconversion process is governed by two-photon absorption process.

  16. Microwave hydrothermal synthesis and upconversion properties of Yb3+/Er3+ doped YVO4 nanoparticles.

    PubMed

    Kshetri, Yuwaraj K; Regmi, Chhabilal; Kim, Hak-Soo; Lee, Soo Wohn; Kim, Tae-Ho

    2018-05-18

    Yb 3+ and Er 3+ doped YVO 4 (Yb 3+ /Er 3+ :YVO 4 ) nanoparticles with highly efficient near-infrared to visible upconversion properties have been synthesized by microwave hydrothermal process. Uniform-sized Yb 3+ /Er 3+ :YVO 4 nanoparticles were synthesized within 1 h at 140 °C which is relatively faster than the conventional hydrothermal process. Under 980 nm laser excitation, strong green and less strong red emissions are observed which are attributed to 2 H 11/2 , 4 S 3/2 to 4 I 15/2 and 4 F 9/2 to 4 I 15/2 transitions of Er 3+ respectively. The emission intensity is found to depend strongly on the concentration of Yb 3+ . The quadratic dependence of upconversion intensity on the excitation power indicates that the upconversion process is governed by two-photon absorption process.

  17. Type-I superconductivity in YbSb2 single crystals

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Zhao, Liang L.; Lausberg, Stefan; Kim, Hyunsoo

    2012-06-25

    We present evidence of type-I superconductivity in YbSb2 single crystals from dc and ac magnetization, heat capacity, and resistivity measurements. The critical temperature and critical field are determined to be Tc≈ 1.3 K and Hc≈ 55 Oe. A small Ginzburg-Landau parameter κ= 0.05, together with typical magnetization isotherms of type-I superconductors, small critical field values, a strong differential paramagnetic effect signal, and a field-induced change from second- to first-order phase transition, confirms the type-I nature of the superconductivity in YbSb2. A possible second superconducting state is observed in the radio-frequency susceptibility measurements, with Tc(2)≈ 0.41 K and Hc(2)≈ 430 Oe.

  18. Dual nature of 3 d electrons in YbT 2 Zn 20 (T = Co; Fe) evidenced by electron spin resonance

    DOE PAGES

    Ivanshin, V. A.; Litvinova, T. O.; Gimranova, K.; ...

    2015-03-18

    The electron spin resonance experiments were carried out in the single crystals YbFe 2Zn 20. The observed spin dynamics is compared with that in YbCo 2Zn 20 and Yb 2Co 12P 7 as well as with the data of inelastic neutron scattering and electronic band structure calculations. Our results provide direct evidence that 3d electrons are itinerant in YbFe 2Zn 20 and localized in YbCo 2Zn 20. Possible connection between spin paramagnetism of dense heavy fermion systems, quantum criticality effects, and ESR spectra is discussed.

  19. YB-1 Is Important for Late-Stage Embryonic Development, Optimal Cellular Stress Responses, and the Prevention of Premature Senescence

    PubMed Central

    Lu, Zhi Hong; Books, Jason T.; Ley, Timothy J.

    2005-01-01

    Proteins containing “cold shock” domains belong to the most evolutionarily conserved family of nucleic acid-binding proteins known among bacteria, plants, and animals. One of these proteins, YB-1, is widely expressed throughout development and has been implicated as a cell survival factor that regulates the transcription and/or translation of many cellular growth and death-related genes. For these reasons, YB-1 deficiency has been predicted to be incompatible with cell survival. However, the majority of YB-1−/− embryos develop normally up to embryonic day 13.5 (E13.5). After E13.5, YB-1−/− embryos exhibit severe growth retardation and progressive mortality, revealing a nonredundant role of YB-1 in late embryonic development. Fibroblasts derived from YB-1−/− embryos displayed a normal rate of protein synthesis and minimal alterations in the transcriptome and proteome but demonstrated reduced abilities to respond to oxidative, genotoxic, and oncogene-induced stresses. YB-1−/− cells under oxidative stress expressed high levels of the G1-specific CDK inhibitors p16Ink4a and p21Cip1 and senesced prematurely; this defect was corrected by knocking down CDK inhibitor levels with specific small interfering RNAs. These data suggest that YB-1 normally represses the transcription of CDK inhibitors, making it an important component of the cellular stress response signaling pathway. PMID:15899865

  20. The r-process Pattern of a Bright, Highly r-process-enhanced Metal-poor Halo Star at [Fe/H] ∼ ‑2

    NASA Astrophysics Data System (ADS)

    Sakari, Charli M.; Placco, Vinicius M.; Hansen, Terese; Holmbeck, Erika M.; Beers, Timothy C.; Frebel, Anna; Roederer, Ian U.; Venn, Kim A.; Wallerstein, George; Davis, Christopher Evan; Farrell, Elizabeth M.; Yong, David

    2018-02-01

    A high-resolution spectroscopic analysis is presented for a new highly r-process-enhanced ([Eu/Fe] = 1.27, [Ba/Eu] = ‑0.65), very metal-poor ([Fe/H] = ‑2.09), retrograde halo star, RAVE J153830.9–180424, discovered as part of the R-Process Alliance survey. At V = 10.86, this is the brightest and most metal-rich r-II star known in the Milky Way halo. Its brightness enables high-S/N detections of a wide variety of chemical species that are mostly created by the r-process, including some infrequently detected lines from elements like Ru, Pd, Ag, Tm, Yb, Lu, Hf, and Th, with upper limits on Pb and U. This is the most complete r-process census in a very metal-poor r-II star. J1538–1804 shows no signs of s-process contamination, based on its low [Ba/Eu] and [Pb/Fe]. As with many other r-process-enhanced stars, J1538–1804's r-process pattern matches that of the Sun for elements between the first, second, and third peaks, and does not exhibit an actinide boost. Cosmo-chronometric age-dating reveals the r-process material to be quite old. This robust main r-process pattern is a necessary constraint for r-process formation scenarios (of particular interest in light of the recent neutron star merger, GW170817), and has important consequences for the origins of r-II stars. Additional r-I and r-II stars will be reported by the R-Process Alliance in the near future.

  1. Yb:Y2O3 transparent ceramics processed with hot isostatic pressing

    NASA Astrophysics Data System (ADS)

    Wang, Jun; Ma, Jie; Zhang, Jian; Liu, Peng; Luo, Dewei; Yin, Danlei; Tang, Dingyuan; Kong, Ling Bing

    2017-09-01

    Highly transparent 5 at.% Yb:Y2O3 ceramics were fabricated by using a combination method of vacuum sintering and hot isostatic pressing (HIP). Co-precipitated Yb:Y2O3 powders, with 1 at.% ZrO2 as the sintering aid, were used as the starting material. The Yb:Y2O3 ceramics, vacuum sintered at 1700 °C for 2 h and HIPed at 1775 °C for 4 h, exhibited small grain size of 1.9 μm and highly dense microstructure. In-line optical transmittance of the ceramics reached 83.4% and 78.9% at 2000 and 600 nm, respectively. As the ceramic slab was pumped by a fiber-coupled laser diode at about 940 nm, a maximum output power of 0.77 W at 1076 nm was achieved, with a corresponding slope efficiency of 10.6%.

  2. Fluorosilicate and fluorophosphate superfluorescent multicore optical fibers co-doped with Nd3+/Yb3+

    NASA Astrophysics Data System (ADS)

    Kochanowicz, M.; Zmojda, J.; Dorosz, D.

    2014-06-01

    In the paper spectroscopic properties of two fluorosilicate and fluorophosphate glass systems co-doped with Nd3+/Yb3+ ions are investigated. As a result of optical excitation at the wavelength of 808 nm strong and wide emission in the 1 μm region corresponding to the superposition of optical transitions 4F3/2 → 4I11/2 (Nd3+) and 2F5/2 → 2F7/2 (Yb3+) can be observed. The optimization of Nd3+ → Yb3+ energy transfer in both glasses allows to manufacture multicore optical fibers with narrowing and red-shifting of amplified spontaneous emission (ASE) at 1.1 μm.

  3. Magnetotransport study of Dirac fermions in YbMnBi 2 antiferromagnet

    DOE PAGES

    Wang, Aifeng; Zaliznyak, I.; Ren, Weijun; ...

    2016-10-15

    We report quantum transport and Dirac fermions in YbMnBi 2 single crystals. YbMnBi 2 is a layered material with anisotropic conductivity and magnetic order below 290 K. Magnetotransport properties, nonzero Berry phase, and small cyclotron mass indicate the presence of Dirac fermions. Lastly, angular-dependent magnetoresistance indicates a possible quasi-two-dimensional Fermi surface, whereas the deviation from the nontrivial Berry phase expected for Dirac states suggests the contribution of parabolic bands at the Fermi level or spin-orbit coupling.

  4. Several hundred kHz repetition rate nanosecond pulses amplification in Er-Yb co-doped fiber amplifier

    NASA Astrophysics Data System (ADS)

    Yang, Weiqiang; Yin, Ke; Zhang, Bin; Xue, Guanghui; Hou, Jing

    2014-07-01

    We have experimentally investigated several hundred kHz repetition rate 1,550-nm nanosecond pulses amplification in Er-Yb co-doped fiber amplifier (EYDFA). The experimental setup has three stage fiber amplifiers. At the output of the second stage EYDFA, Yb3+ ions induced amplified spontaneous emission (Yb-ASE) is not observed owing to the low pump power. In the third stage EYDFA, a simultaneously seeded 1,064-nm continuous-wave laser is used to control Yb-ASE. Without any additional 1,064-nm signal, significantly backward Yb-ASE which caused loss-induced heat accumulation at the input port of the pump combiner can be observed. The monitored temperature at the input port of the pump combiner rapidly grows from 30 to 80 °C when the pump power is turned from 20 to 32 W. When a 196-mW forward 1,064-nm laser is added, the monitored backward Yb-ASE power is significantly declined, and the monitored temperature is kept below 35 °C. But, the additional signal caused a large power fraction at 1,064 nm in the output laser. In our experiment at the maximum pump power of 48.5 W, the total output power is 20 W with ~6.4-W 1,550-nm pulsed laser and ~13-W 1,064-nm continuous-wave laser.

  5. Optical properties of Mg2+, Yb3+, and Ho3+ tri-doped LiNbO3 crystals

    NASA Astrophysics Data System (ADS)

    Dai, Li; Liu, Chun-Rui; Tan, Chao; Yan, Zhe-Hua; Xu, Yu-Heng

    2017-04-01

    A series of LiNbO3 crystals tri-doped with Mg{}2+, Yb{}3+, and Ho{}3+ are grown by the conventional Czochraski technique. The concentrations of Mg{}2+, Yb{}3+, and Ho{}3+ ions in Mg:Yb:Ho:LiNbO3 crystals are measured by using an inductively coupled plasma atomic emission spectrometry. The x-ray diffraction is proposed to determine the lattice constant and analyze the internal structure of the crystal. The light-induced scattering of Mg:Yb:Ho:LiNbO3 crystal is quantitatively described via the threshold effect of incident exposure energy flux. The exposure energy ({E}{{r}}) is calculated to discuss the optical damage resistance ability. The exposure energy of Mg(7 mol):Yb:Ho:LiNbO3 crystal is 709.17 J/cm2, approximately 425 times higher than that of the Mg(1 mol):Yb:Ho:LiNbO3 crystal in magnitude. The blue, red, and very intense green bands of Mg:Yb:Ho:LiNbO3 crystal are observed under the 980-nm laser excitation to evaluate the up-conversion emission properties. The dependence of the emission intensity on pumping power indicates that the up-conversion emission is a two-photon process. The up-conversion emission mechanism is discussed in detail. This study indicates that Mg:Yb:Ho:LiNbO3 crystal can be applied to the fabrication of new multifunctional photoluminescence devices. Project supported by the National Natural Science Foundation of China (Grant No. 51301055), the Youth Science Fund of Heilongjiang Province, China (Grant No. QC2015061), the Special Funds of Harbin Innovation Talents in Science and Technology Research, China (Grant No. 2015RQQXJ045 ), and the Science Funds for the Young Innovative Talents of Harbin University of Science and Technology, China (Grant No. 201501).

  6. ZmNF-YB16 Overexpression Improves Drought Resistance and Yield by Enhancing Photosynthesis and the Antioxidant Capacity of Maize Plants

    PubMed Central

    Wang, Baomei; Li, Zhaoxia; Ran, Qijun; Li, Peng; Peng, Zhenghua; Zhang, Juren

    2018-01-01

    ZmNF-YB16 is a basic NF-YB superfamily member and a member of a transcription factor complex composed of NF-YA, NF-YB, and NF-YC in maize. ZmNF-YB16 was transformed into the inbred maize line B104 to produce homozygous overexpression lines. ZmNF-YB16 overexpression improves dehydration and drought stress resistance in maize plants during vegetative and reproductive stages by maintaining higher photosynthesis and increases the maize grain yield under normal and drought stress conditions. Based on the examination of differentially expressed genes between the wild-type (WT) and transgenic lines by quantitative real time PCR (qRT-PCR), ZmNF-YB16 overexpression increased the expression of genes encoding antioxidant enzymes, the antioxidant synthase, and molecular chaperones associated with the endoplasmic reticulum (ER) stress response, and improved protection mechanism for photosynthesis system II. Plants that overexpression ZmNF-YB16 showed a higher rate of photosynthesis and antioxidant enzyme activity, better membrane stability and lower electrolyte leakage under control and drought stress conditions. These results suggested that ZmNF-YB16 played an important role in drought resistance in maize by regulating the expression of a number of genes involved in photosynthesis, the cellular antioxidant capacity and the ER stress response. PMID:29896208

  7. Synthesis and Photoluminescence Characteristics of Eu(3+)-Doped Molybdates Nanocrystals.

    PubMed

    Li, Fuhai; Yu, Lixin; Wei, Shuilin; Sun, Jiaju; Chen, Weiqing; Sun, Wei

    2015-12-01

    In this paper, the Eu(3+)-doped molybdate (CaMoO4, ZnMoO4 and BaMoO4) phosphors have been prepared by a hydrothermal method through modulating the pH value of the precursor solution (pH = 8, 10, and 12, respectively). The crystalline phase, morphology, photoluminescent properties of the prepared samples were systematically characterized by means of X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and photoluminescence (PL) spectra. The results indicate that the photoluminescence and morphology can be affected by the precursor solution. And the growth of the ZnMoO4 crystals also can be affected by the pH value of the precursor solution.

  8. A murine retrovirus co-Opts YB-1, a translational regulator and stress granule-associated protein, to facilitate virus assembly.

    PubMed

    Bann, Darrin V; Beyer, Andrea R; Parent, Leslie J

    2014-04-01

    The Gag protein of the murine retrovirus mouse mammary tumor virus (MMTV) orchestrates the assembly of immature virus particles in the cytoplasm which are subsequently transported to the plasma membrane for release from the cell. The morphogenetic pathway of MMTV assembly is similar to that of Saccharomyces cerevisiae retrotransposons Ty1 and Ty3, which assemble virus-like particles (VLPs) in intracytoplasmic ribonucleoprotein (RNP) complexes. Assembly of Ty1 and Ty3 VLPs depends upon cellular mRNA processing factors, prompting us to examine whether MMTV utilizes a similar set of host proteins to facilitate viral capsid assembly. Our data revealed that MMTV Gag colocalized with YB-1, a translational regulator found in stress granules and P bodies, in intracytoplasmic foci. The association of MMTV Gag and YB-1 in cytoplasmic granules was not disrupted by cycloheximide treatment, suggesting that these sites were not typical stress granules. However, the association of MMTV Gag and YB-1 was RNA dependent, and an MMTV RNA reporter construct colocalized with Gag and YB-1 in cytoplasmic RNP complexes. Knockdown of YB-1 resulted in a significant decrease in MMTV particle production, indicating that YB-1 plays a role in MMTV capsid formation. Analysis by live-cell imaging with fluorescence recovery after photobleaching (FRAP) revealed that the population of Gag proteins localized within YB-1 complexes was relatively immobile, suggesting that Gag forms stable complexes in association with YB-1. Together, our data imply that the formation of intracytoplasmic Gag-RNA complexes is facilitated by YB-1, which promotes MMTV virus assembly. Cellular mRNA processing factors regulate the posttranscriptional fates of mRNAs, affecting localization and utilization of mRNAs under normal conditions and in response to stress. RNA viruses such as retroviruses interact with cellular mRNA processing factors that accumulate in ribonucleoprotein complexes known as P bodies and stress granules

  9. Yb:FAP and related materials, laser gain medium comprising same, and laser systems using same

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Krupke, William F.; Payne, Stephen A.; Chase, Lloyd L.

    An ytterbium doped laser material remarkably superior to all others, including Yb:YAG, comprises Ytterbium doped apatite (Yb:Ca.sub.5 (PO.sub.4).sub.3 F) or Yb:FAP, or ytterbium doped crystals that are structurally related to FAP. The new laser material is used in laser systems pumped by diode pump sources having an output near 0.905 microns or 0.98 microns, such as InGaAs and AlInGaAs, or other narrowband pump sources near 0.905 microns or 0.98 microns. The laser systems are operated in either the conventional or ground state depletion mode.

  10. Yb:FAP and related materials, laser gain medium comprising same, and laser systems using same

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Krupke, W.F.; Payne, S.A.; Chase, L.L.

    An ytterbium doped laser material remarkably superior to all others, including Yb:YAG, comprises ytterbium doped apatite (Yb:Ca{sub 5}(PO{sub 4}){sub 3}F) or Yb:FAP, or ytterbium doped crystals structurally related to FAP. The new laser material is used in laser systems pumped by diode pump sources having an output near 0.905 microns or 0.98 microns, such as InGaAs and AlInGaAs, or other narrowband pump sources near 0.905 microns or 0.98 microns. The laser systems are operated in either the conventional or ground state depletion mode.

  11. High average power, widely tunable femtosecond laser source from red to mid-infrared based on an Yb-fiber-laser-pumped optical parametric oscillator.

    PubMed

    Gu, Chenglin; Hu, Minglie; Zhang, Limeng; Fan, Jintao; Song, Youjian; Wang, Chingyue; Reid, Derryck T

    2013-06-01

    We report on the highly efficient generation of widely tunable femtosecond pulses based on intracavity second harmonic generation (SHG) and sum frequency generation (SFG) in a MgO-doped periodically poled LiNbO(3) optical parametric oscillator (OPO), which is pumped by a Yb-doped large-mode-area photonics crystal fiber femtosecond laser. Red and near infrared from intracavity SHG and SFG and infrared signals were directly obtained from the OPO. A 2 mm β-BaB(2)O(4) is applied for Type I (oo → e) intracavity SHG and SFG, and then femtosecond laser pulses over 610 nm ~ 668 nm from SFG and 716 nm ~ 970 nm from SHG are obtained with high efficiency. In addition, the oscillator simultaneously generates signal and idler femtosecond pulses over 1450 nm ~ 2200 nm and 2250 nm ~ 4000 nm, respectively.

  12. Evidence of dissipative solitons in Yb³⁺:CaYAlO₄.

    PubMed

    Tan, W D; Tang, D Y; Xu, C W; Zhang, J; Xu, X D; Li, D Z; Xu, J

    2011-09-12

    Operation of an end-pumped Yb³⁺:CaYAlO₄ laser operating in the positive dispersion regime is experimentally investigated. The laser emitted strongly chirped pulses with extremely steep spectral edges, resembling the characteristics of dissipative solitons observed in fiber lasers. The results show that dissipative soliton emission constitutes another operating regime for mode locked Yb³⁺-doped solid state lasers, which can be explored for the generation of stable large energy femtosecond pulses.

  13. Low-temperature magnetoelectric effect in multiferroic h-Yb1-xHoxMnO3

    NASA Astrophysics Data System (ADS)

    Zhang, Jincang; Gang, Qiang; Fang, Yifei

    In this work, we study the low-temperature ferroelectricity, magnetic property and ME effect in Yb1-xHoxMnO3. In YbMnO3, ferroelectric polarization (P) is closely related with the structure change derived from spin-reorientation process. The initial symmetric relationship of P between the upper and lower half of magnetic sublattice will be broken, which gives rise to the detectable polarization. Additionally, the asymmetry of the P - T curves revealed the pinning effect of the defects in the material. In Ho-doped samples 2D antiferromagnetic perturbation as well as the second AFM ordering have been observed. Substitution of Yb by Ho atoms shows great influences on electric properties and the lowdoping concentration tend to be more favorable for the enhancement of P. The maximum polarization has been promoted hugely in Yb0.8Ho0.2MnO3. We suggested the variation of P is closely related with the stronger exchange interaction in Mn-O-Ho as well as the establishment of new Ho layers with the increase of Ho.

  14. High power Yb:CALGO ultrafast regenerative amplifier for industrial application

    NASA Astrophysics Data System (ADS)

    Caracciolo, E.; Guandalini, A.; Pirzio, F.; Kemnitzer, M.; Kienle, F.; Agnesi, A.; Aus der Au, J.

    2017-02-01

    We present a high-power, single-crystal based, Yb:CALGO regenerative amplifier. The system delivers more than 50 W output power in continuous-wave regime, with diffraction limited beam quality. In Q-switching regime the spectrum is centered at 1043 nm and is 11 nm wide. In regenerative amplification experiments we achieved 34 W at 500 kHz with 12.7 nm FWHM wide spectra centered at 1044 nm seeding with a broadly tunable, single-prism SESAM mode-locked Yb:CALGO laser providing 9 nm wide spectra at 1049 nm. Pulse duration after compression was 140 fs, with excellent beam quality (M2 < 1.25).

  15. Doped YbRh2Si2: not only ferromagnetic correlations but ferromagnetic order.

    PubMed

    Lausberg, S; Hannaske, A; Steppke, A; Steinke, L; Gruner, T; Pedrero, L; Krellner, C; Klingner, C; Brando, M; Geibel, C; Steglich, F

    2013-06-21

    YbRh2Si2 is a prototypical system for studying unconventional antiferromagnetic quantum criticality. However, ferromagnetic correlations are present which can be enhanced via isoelectronic cobalt substitution for rhodium in Yb(Rh(1-x)Co(x))2Si2. So far, the magnetic order with increasing x was believed to remain antiferromagnetic. Here, we present the discovery of ferromagnetism for x = 0.27 below T(C) = 1.30  K in single crystalline samples. Unexpectedly, ordering occurs along the c axis, the hard crystalline electric field direction, where the g factor is an order of magnitude smaller than in the basal plane. Although the spontaneous magnetization is only 0.1 μB/Yb it corresponds to the full expected saturation moment along c taking into account partial Kondo screening.

  16. Yb-doped Gd2O2CO3: Structure, microstructure, thermal and magnetic behaviour

    NASA Astrophysics Data System (ADS)

    Artini, Cristina; Locardi, Federico; Pani, Marcella; Nelli, Ilaria; Caglieris, Federico; Masini, Roberto; Plaisier, Jasper Rikkert; Costa, Giorgio Andrea

    2017-04-01

    Structural and microstructural features, as well as thermal and magnetic properties of Yb-doped Gd2O2CO3, were investigated with the aim to clarify the location and the oxidation state of Yb within the structure, and its role in driving the extent of the (Gd1-xYbx)2O2CO3 solid solution. Yb is found in the 3+ oxidation state and it enters the structure only at the rare earth atomic site; the solubility limit results to be located in the close vicinity of x=0.25, and thermal analyses reveal a linear decrease of the decomposition temperature with increasing the Yb amount, in agreement with literature data. The structural analysis allows to exclude long-range clusterization of Yb and Gd, since both rare earths randomly distribute over the 4f atomic position, but relying on the results of the microstructural analysis, the presence of compositional inhomogenities at the local scale cannot be excluded. Not all the structural forms are documented for the pure rare earth dioxycarbonates [1]; in particular, while form I exists for each lanthanide ion, form II is stable only for the largest ones (from La to Dy); moreover, even if II-Ho2O2CO3 (rHo3+ CN8=1.015 Å [6]) is not reported to be stable, the existence of II-Y2O2CO3 (rY3+ CN8=1.019 Å [6]) has been claimed [7]. Based on the described evidence, the stability of hexagonal Yb-doped Gd2O2CO3 is not expected along the whole compositional range. As a general remark, not all the rare earth mixed dioxycarbonates exist: (Ce, Gd)2O2CO3, for instance, could not be obtained at any composition [8]; moreover, all the structural forms can be observed only in some mixed systems, such as for example (Gd, Nd)2O2CO3, by varying temperature and tuning the composition [9]. Rare earth dioxycarbonates are studied mainly for their CO2 sensing properties [10,11], and for their emission when properly doped with a luminescent lanthanide ion [12-17]. Recently, a study of this research group [18] revealed in Gd2O2CO3:4% Yb a phenomenon of

  17. Effect of Yb substitution on room temperature magnetic and dielectric properties of bismuth ferrite nanoparticles

    NASA Astrophysics Data System (ADS)

    Remya, K. P.; Amirthapandian, S.; Manivel Raja, M.; Viswanathan, C.; Ponpandian, N.

    2016-10-01

    Effect of the Yb dopant on the structural, magnetic, and electrical properties of the multiferroic BiFeO3 have been studied. The structural properties of sol-gel derived Bi1-xYbxFeO3 (x = 0.0, 0.1, and 0.2) nanoparticles reveal the formation of a rhombohedrally distorted perovskite in XRD and a reduction in the average grain size have been observed with an increase in the Yb concentration. Microstructural studies exhibited the formation of sphere like morphology with decreasing particle size with increase in the dopant concentration. The effective doping also resulted in larger magnetization as well as coercivity with the maximum of 257 Oe and 1.76 emu/g in the Bi0.8Yb0.2FeO3 nanoparticles. Ferroelectric as well as dielectric properties of the nanoparticles were also improved on doping. The best results were obtained for the BiFeO3 nanoparticles having Yb concentration x = 0.2.

  18. Effect of [Li]/[Nb] ratio on composition and defect structure of Zr:Yb:Tm:LiNbO3 crystals

    NASA Astrophysics Data System (ADS)

    Liu, Chunrui; Dai, Li; Wang, Luping; Shao, Yu; Yan, Zhehua; Xu, Yuheng

    2018-04-01

    Zr:Yb:Tm:LiNbO3 crystals with various [Li]/[Nb] ratios (0.946, 1.05, 1.20 and 1.38) were grown by the Czochralski technique. Distribution coefficients of Zr4+, Yb3+ and Tm3+ ions were analyzed by the inductively coupled plasma-atomic emission spectrometer (ICP-AES). The influence of [Li]/[Nb] ratio on the composition and defect structure of Zr:Yb:Tm:LiNbO3 crystals was investigated by X-ray diffraction and IR transmission spectrum. The results show that as the [Li]/[Nb] ratio increases in the melt, the distribution coefficients of Yb3+ and Tm3+ ions both increase while that of Zr4+ ion deceases. When the [Li]/[Nb] ratio increases to 1.20 in the melt, Zr:Yb:Tm:LiNbO3 crystal is nearly stoichiometric. In addition, when the [Li]/[Nb] ratio reaches up to 1.38, NbLi4+ are completely replaced and Li+ starts to impel the Zr4+, Yb3+ and Tm3+ into the normal Li sites.

  19. Diode pumped Yb:CN laser at 1082 nm and intracavity doubling to the green spectral range

    NASA Astrophysics Data System (ADS)

    Liu, B.; Li, Y. L.; Jiang, H. L.

    2011-08-01

    A diode pumped Yb:CaNb2O6 (Yb:CN) laser at 1082 nm with a maximum output of 1.35 W at 13.3 W pump power has been demonstrated. The slope efficiency was 12.4%. Moreover, intracavity second-harmonic generation (SHG) has also been achieved with a maximum green power of 374 mW by using a LiB3O5 (LBO) nonlinear crystal. To the best of our knowledge, this is the first report on continuous wave (CW) green generation by intracavity frequency doubling Yb:CN laser.

  20. Quantum oscillations and coherent interlayer transport in a new topological Dirac semimetal candidate YbMnSb2

    NASA Astrophysics Data System (ADS)

    Wang, Yi-Yan; Xu, Sheng; Sun, Lin-Lin; Xia, Tian-Long

    2018-02-01

    Dirac semimetals, which host Dirac fermions and represent a new state of quantum matter, have been studied intensively in condensed-matter physics. The exploration of new materials with topological states is important in both physics and materials science. We report the synthesis and the transport properties of high-quality single crystals of YbMnSb2. YbMnSb2 is a new compound with metallic behavior. Quantum oscillations, including Shubnikov-de Haas (SdH) oscillation and de Haas-van Alphen-type oscillation, have been observed at low temperature and high magnetic field. Small effective masses and nontrivial Berry phase are extracted from the analyses of quantum oscillations, which provide the transport evidence for the possible existence of Dirac fermions in YbMnSb2. The measurements of angular-dependent interlayer magnetoresistance indicate that the interlayer transport is coherent. The Fermi surface of YbMnSb2 possesses a quasi-two-dimensional characteristic as determined by the angular dependence of SdH oscillation frequency. These findings suggest that YbMnSb2 is a new candidate of topological Dirac semimetals.

  1. Universal heat conduction in Ce 1-xYb xCoIn 5: Evidence for robust nodal d-wave superconducting gap

    DOE PAGES

    Xu, Y.; Petrovic, C.; Dong, J. K.; ...

    2016-02-01

    In the heavy-fermion superconductor Ce 1-xYb xCoIn 5, Yb doping was reported to cause a possible change from nodal d-wave superconductivity to a fully gapped d-wave molecular superfluid of composite pairs near x ≈ 0.07 (nominal value x nom = 0.2). Here we present systematic thermal conductivity measurements on Ce 1-xYb xCoIn 5 (x = 0.013, 0.084, and 0.163) single crystals. The observed finite residual linear term κ 0/T is insensitive to Yb doping, verifying the universal heat conduction of the nodal d-wave superconducting gap in Ce 1-xYb xCoIn 5. Similar universal heat conduction is also observed in the CeCo(Inmore » 1–yCd y) 5 system. Furthermore, these results reveal a robust nodal d-wave gap in CeCoIn 5 upon Yb or Cd doping.« less

  2. Spin-flop and magnetodielectric reversal in Yb substituted GdMnO3

    NASA Astrophysics Data System (ADS)

    Pal, A.; Prellier, W.; Murugavel, P.

    2018-03-01

    The evolution of various spin structures in Yb doped GdMnO3 distorted orthorhombic perovskite system was investigated from their magnetic, dielectric and magnetodielectric characteristics. The Gd1-x Yb x MnO3 (0  ⩽  x  ⩽  0.15) revealed an enhanced magnetodielectric coupling when their magnetic structure is guided from ab to the bc-cycloidal spin structure upon Yb doping. The compounds exhibit magnetic field and temperature controlled spin-flop from c to a-axis. Additionally, magnetodielectric reversal is observed for the x  =  0.1 sample which depends on both magnetic field and temperature. The resultant correlation between magnetic and electric orderings is discussed in the frame of symmetric and antisymmetric exchange interaction models. These findings provide further insight in understanding the magnetoelectric materials and importantly show a way to tune the magnetic and magnetodielectric properties towards better application potential.

  3. Plasmon-photon conversion to near-infrared emission from Yb(3+): (Au/Ag-nanoparticles) in tungsten-tellurite glasses.

    PubMed

    Rivera, V A G; Ledemi, Yannick; Pereira-da-Silva, Marcelo A; Messaddeq, Younes; Marega, Euclydes

    2016-01-04

    This manuscript reports on the interaction between (2)F5/2→(2)F7/2 radiative transition from Yb(3+) ions and localized surface plasmon resonance (from gold/silver nanoparticles) in a tungsten-tellurite glass. Such an interaction, similar to the down-conversion process, results in the Yb(3+) emission in the near-infrared region via resonant and non-resonant energy transfers. We associated such effects with the dynamic coupling described by the variations generated by the Hamiltonian HDC in either the oscillator strength, or the local crystal field, i.e. the line shape changes in the emission band. Here, the Yb(3+) ions emission is achieved through plasmon-photon coupling, observable as an enhancement or quenching in the luminescence spectra. Metallic nanoparticles have light-collecting capability in the visible spectrum and can accumulate almost all the photon energy on a nanoscale, which enable the excitation and emission of the Yb(3+) ions in the near-infrared region. This plasmon-photon conversion was evaluated from the cavity's quality factor (Q) and the coupling (g) between the nanoparticles and the Yb(3+) ions. We have found samples of low-quality cavities and strong coupling between the nanoparticles and the Yb(3+) ions. Our research can be extended towards the understanding of new plasmon-photon converters obtained from interactions between rare-earth ions and localized surface plasmon resonance.

  4. Plasmon-photon conversion to near-infrared emission from Yb3+: (Au/Ag-nanoparticles) in tungsten-tellurite glasses

    PubMed Central

    Rivera, V. A. G.; Ledemi, Yannick; Pereira-da-Silva, Marcelo A.; Messaddeq, Younes; Marega Jr, Euclydes

    2016-01-01

    This manuscript reports on the interaction between 2F5/2→2F7/2 radiative transition from Yb3+ ions and localized surface plasmon resonance (from gold/silver nanoparticles) in a tungsten-tellurite glass. Such an interaction, similar to the down-conversion process, results in the Yb3+ emission in the near-infrared region via resonant and non-resonant energy transfers. We associated such effects with the dynamic coupling described by the variations generated by the Hamiltonian HDC in either the oscillator strength, or the local crystal field, i.e. the line shape changes in the emission band. Here, the Yb3+ ions emission is achieved through plasmon-photon coupling, observable as an enhancement or quenching in the luminescence spectra. Metallic nanoparticles have light-collecting capability in the visible spectrum and can accumulate almost all the photon energy on a nanoscale, which enable the excitation and emission of the Yb3+ ions in the near-infrared region. This plasmon-photon conversion was evaluated from the cavity’s quality factor (Q) and the coupling (g) between the nanoparticles and the Yb3+ ions. We have found samples of low-quality cavities and strong coupling between the nanoparticles and the Yb3+ ions. Our research can be extended towards the understanding of new plasmon-photon converters obtained from interactions between rare-earth ions and localized surface plasmon resonance. PMID:26725938

  5. A series of binuclear lanthanide(III) complexes: Crystallography, antimicrobial activity and thermochemistry properties studies

    NASA Astrophysics Data System (ADS)

    Zhang, Ying-Ying; Ren, Ning; Xu, Su-Ling; Zhang, Jian-Jun; Zhang, Da-Hai

    2015-02-01

    A series of novel lanthanide complexes with the general formula [Ln(3,4-DClBA)3phen]2 (Ln = Ho(1), Nd(2), Sm(3), Dy(4), Eu(5), Tb(6), Yb(7) and Er(8), 3,4-DClBA = 3,4-dichlorobenzoate, phen = 1,10-phenanthroline) were prepared at room temperature and characterized. The crystal structures of complexes 1-8 have been determined by single crystal X-ray diffraction. These complexes are isomorphous and lanthanide ions are all eight-coordinated to oxygen atoms and nitrogen atoms with distorted square-antiprism geometry. The thermal decomposition mechanism and TG-FTIR spectra of gaseous products of thermal decomposition processes for complexes 1-8 were acquired through TG/DSC-FTIR system. The heat capacities of complexes 1-8 were measured using DSC technology and fitted to a polynomial equation by the least-squares method. Complexes 3-6 display characteristic lanthanide emission bands in the visible region. Meanwhile, these complexes exhibit in good antimicrobial activity against Candida albicans, Escherichia coli, and Staphylococcus aureu.

  6. Yb:FAP and related materials, laser gain medium comprising same, and laser systems using same

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Krupke, W.F.; Payne, S.A.; Chase, L.L.

    An ytterbium doped laser material remarkably superior to all others, including Yb:YAG, comprises ytterbium doped apatite (Yb:Ca[sub 5](PO[sub 4])[sub 3]F) or Yb:FAP, or ytterbium doped crystals that are structurally related to FAP. The new laser material is used in laser systems pumped by diode pump sources having an output near 0.905 microns or 0.98 microns, such as InGaAs and AlInGaAs, or other narrowband pump sources near 0.905 microns or 0.98 microns. The laser systems are operated in either the conventional or ground state depletion mode. 9 figures.

  7. Yb:FAP and related materials, laser gain medium comprising same, and laser systems using same

    DOEpatents

    Krupke, W.F.; Payne, S.A.; Chase, L.L.; Smith, L.K.

    1994-01-18

    An ytterbium doped laser material remarkably superior to all others, including Yb:YAG, comprises ytterbium doped apatite (Yb:Ca[sub 5](PO[sub 4])[sub 3]F) or Yb:FAP, or ytterbium doped crystals that are structurally related to FAP. The new laser material is used in laser systems pumped by diode pump sources having an output near 0.905 microns or 0.98 microns, such as InGaAs and AlInGaAs, or other narrowband pump sources near 0.905 microns or 0.98 microns. The laser systems are operated in either the conventional or ground state depletion mode. 9 figures.

  8. Electrochemical performance and carbon deposition resistance of M-BaZr0.1Ce0.7Y0.1Yb0.1O3-δ (M = Pd, Cu, Ni or NiCu) anodes for solid oxide fuel cells

    PubMed Central

    Li, Meng; Hua, Bin; Pu, Jian; Chi, Bo; Jian, Li

    2015-01-01

    Pd-, Cu-, Ni- and NiCu-BaZr0.1Ce0.7Y0.1Yb0.1O3-δ anodes, designated as M-BZCYYb, were prepared by impregnating M-containing solution into BZCYYb scaffold, and investigated in the aspects of electrocatalytic activity for the reactions of H2 and CH4 oxidation and the resistance to carbon deposition. Impregnation of Pd, Ni or NiCu significantly reduced both the ohmic (RΩ) and polarization (RP) losses of BZCYYb anode exposed to H2 or CH4, while Cu impregnation decreased only RΩ in H2 and the both in CH4. Pd-, Ni- and NiCu-BZCYYb anodes were resistant to carbon deposition in wet (3 mol. % H2O) CH4 at 750°C. Deposited carbon fibers were observed in Pd- and Ni-BZCYYb anodes exposed to dry CH4 at 750°C for 12 h, and not observed in NiCu-BZCYYb exposed to dry CH4 at 750°C for 24 h. The performance of a full cell with NiCu-BZCYYb anode, YSZ electrolyte and La0.6Sr0.4Co0.2Fe0.8O3-δ-Gd doped CeO2 (LSCF-GDC) cathode was stable at 750°C in wet CH4 for 130 h, indicating that NiCu-BZCYYb is a promising anode for direct CH4 solid oxide fuel cells (SOFCs). PMID:25563843

  9. Petrogenesis of ore-bearing porphyry in non-subduction setting: a case study of the Eocene potassic intrusions in the western Yangtze Block

    NASA Astrophysics Data System (ADS)

    Liu, Zheng; Liao, Shi-Yong; Zhou, Qing; Zhang, Xin

    2018-05-01

    In the western Yangtze Block, abundant Eocene ( 38-34 Ma) potassic adakite-like intrusions and associated porphyry copper deposits are exposed in non-subduction setting, including Machangjing, Beiya, Binchuan, Habo and Tongchang intrusions. All these ore-bearing porphyries share many geochemical characteristics of adakite such as depletion in heavy rare earth elements (HREEs), enrichment in Sr and Ba, absence of negative Eu anomalies, high SiO2, Al2O3, Sr/Y, La/Yb and low Y, Yb contents. They also exhibit affinities of potassic rocks, e.g., alkali-rich, high K2O/Na2O ratios and enrichment in light rare earth elements (LREEs) and large ion lithophile elements (LILEs). Their Sr-Nd isotopic ratios are similar to coeval shoshonitic lamprophyres. Geochemical data indicate that they were probably produced by partial melting of newly underplated potassic rocks sourced from a modified and enriched lithospheric mantle. These underplated rocks have elevated oxygen fugacity, water and copper contents, with high metallogenic potential. We propose that all the studied potassic rocks were emplaced in a post-collisional setting, associated with the local removal of lithospheric mantle.

  10. Yb3+ sensitized Tm3+ upconversion in tellurite lead oxide glass.

    PubMed

    Mohanty, Deepak Kumar; Rai, Vineet Kumar; Dwivedi, Y

    2012-04-01

    Triply ionized thulium/thulium--ytterbium doped/codoped TeO2-Pb3O4 (TPO) glasses have been fabricated by classical quenching method. The upconversion emission spectra in the Tm3+/Tm3+-Yb3+ doped/codoped glasses upon excitation with a diode laser lasing at ∼980 nm has been studied. Effect of the addition of the Yb3+ on the upconversion emission intensity in the visible and near infrared regions of the Tm3+ doped in TPO glass has been studied and the processes involved explored. Copyright © 2011 Elsevier B.V. All rights reserved.

  11. Fluorescence properties of Yb3+-Er3+ co-doped phosphate glasses containing silver nanoparticles

    NASA Astrophysics Data System (ADS)

    Martínez Gámez, Ma A.; Vallejo H, Miguel A.; Kiryanov, A. V.; Licea-Jiménez, L.; Lucio M, J. L.; Pérez-García, S. A.

    2018-04-01

    Er3+-Yb3+ co-doped phosphate glasses containing silver nitrate (SN), were fabricated. Transmission electron microscopy (TEM) and x-ray photoelectron spectroscopy (XPS) analyses were used to evidence the nucleation and presence of silver nanoparticles (SNP). The basic parameters of the glasses were inspected by means of absorption and fluorescence spectra, and fluorescence lifetimes under excitation at 916 nm (in-band of Yb3+), and at 406 nm (in-band of surface plasmon resonance given by the presence of SNP). The spectra as well as estimates for the basic parameters defining the lasing/amplifying potential of the glasses were studied as a function of SN concentration. The experimental results indicate that by increasing the SN content an enhancement of Er3+/Yb3+ fluorescence takes place.

  12. Charge transfer at the interface between ferromagnetic La0.7Sr0.3MnO3 and superconducting EuBa2Cu3O7 probed by STM/STS

    NASA Astrophysics Data System (ADS)

    Liu, Yinghao; Xiong, Jie

    2012-02-01

    La0.7Sr0.3MnO3 (LSMO) is a ferromagnetic half-metallic compound with nearly 100% spin polarization at room temperature, making it an ideal candidate for applications in spintronic devices. However, this useful functionality disappears when the thickness of LSMO film grown on SrTiO3 substrate is reduced to below 4 nm, limiting its application in nanoscale devices. Here, we show that metallic and ferromagnetic properties of ultrathin (< 4nm) LSMO film can be restored by interfacing it with a superconductor EuBa2Cu3O7- δ (EBCO). We use scanning tunneling microscopy and spectroscopy to probe the evolution of the electronic structure of LSMO film grown on EBCO as functions of LSMO layer thickness and aging of bilayer LSMO/EBCO. Our results reveal that the charge (hole) transfer at LSMO/EBCO interface is responsible for driving LSMO film (of only five-unit-cell thickness) to metallic state. The conductive behavior of aged LSMO/EBCO bilayers varies systematically with the thickness of LSMO layer, allowing us to estimate the charge-transfer depth to be 4˜5 nm on the LSMO side.

  13. High slope efficiency and high refractive index change in direct-written Yb-doped waveguide lasers with depressed claddings.

    PubMed

    Palmer, Guido; Gross, Simon; Fuerbach, Alexander; Lancaster, David G; Withford, Michael J

    2013-07-15

    We report the first Yb:ZBLAN and Yb:IOG10 waveguide lasers fabricated by the fs-laser direct-writing technique. Pulses from a Titanium-Sapphire laser oscillator with 5.1 MHz repetition rate were utilized to generate negative refractive index modifications in both glasses. Multiple modifications were aligned in a depressed cladding geometry to create a waveguide. For Yb:ZBLAN we demonstrate high laser slope efficiency of 84% with a maximum output power of 170 mW. By using Yb:IOG10 a laser performance of 25% slope efficiency and 72 mW output power was achieved and we measured a remarkably high refractive index change exceeding Δn = 2.3 × 10(-2).

  14. Characterizations of Pr-doped Yb3Al5O12 single crystals for scintillator applications

    NASA Astrophysics Data System (ADS)

    Yoshida, Yasuki; Shinozaki, Kenji; Igashira, Takuya; Kawano, Naoki; Okada, Go; Kawaguchi, Noriaki; Yanagida, Takayuki

    2018-04-01

    Yb3Al5O12 (YbAG) single crystals doped with different concentrations of Pr were synthesized by the Floating Zone (FZ) method. Then, we evaluated their basic optical and scintillation properties. All the samples showed photoluminescence (PL) with two emission bands appeared approximately 300-500 nm and 550-600 nm due to the charge transfer luminescence of Yb3+ and intrinsic luminescence of the garnet structure, respectively. A PL decay profile of each sample was approximated by a sum of two exponential decay functions, and the obtained decay times were 1 ns and 3-4 ns. In the scintillation spectra, we observed emission peaks in the ranges from 300 to 400 nm and from 450 to 550 nm for all the samples. The origins of these emissions were attributed to charge transfer luminescence of Yb3+ and intrinsic luminescence of the garnet structure, respectively. The scintillation decay times became longer with increasing the Pr concentrations. Among the present samples, the 0.1% Pr-doped sample showed the lowest scintillation afterglow level. In addition, pulse height spectrum of 5.5 MeV α-rays was demonstrated using the Pr-doped YbAG, and we confirmed that all the samples showed a full energy deposited peak. Above all, the 0.1% Pr-doped sample showed the highest light yield with a value of 14 ph/MeV under α-rays excitation.

  15. Kondo interactions from band reconstruction in YbInCu 4

    DOE PAGES

    Jarrige, I.; Kotani, A.; Yamaoka, H.; ...

    2015-03-27

    We combine resonant inelastic X-ray scattering (RIXS) and model calculations in the Kondo lattice compound YbInCu₄, a system characterized by a dramatic increase in Kondo temperature and associated valence fluctuations below a first-order valence transition at T≃42 K. In this study, the bulk-sensitive, element-specific, and valence-projected charge excitation spectra reveal an unusual quasi-gap in the Yb-derived state density which drives an instability of the electronic structure and renormalizes the low-energy effective Hamiltonian at the transition. Our results provide long-sought experimental evidence for a link between temperature-driven changes in the low-energy Kondo scale and the higher-energy electronic structure of this system.

  16. Color tunable emission through energy transfer from Yb3+ co-doped SrSnO3: Ho3+ perovskite nano-phosphor

    NASA Astrophysics Data System (ADS)

    Jain, Neha; Singh, Rajan Kr.; Sinha, Shriya; Singh, R. A.; Singh, Jai

    2018-04-01

    First time color tunable lighting observed from Ho3+ and Yb3+ co-doped SrSnO3 perovskite. Down-conversion and up-conversion (UC) photoluminescence emission spectra were recorded to understand the whole mechanism of energy migration between Ho3+ and Yb3+ ions. The intensity of green and red emission varies with Yb3+ doping which causes multicolour emissions from nano-phosphor. The intensity of UC red emission (654 nm) obtained from 1 at.% Ho3+ and 3 at.% Yb3+ co-doped nano-phosphor is nine times higher than from 1 at.% Ho3+ doped SrSnO3 nano-phosphor. Enhanced brightness of 654 nm in UC process belongs in biological transparency window so that it might be a promising phosphor in the bio-medical field. Moreover, for the other Yb3+ co-doped nano-phosphor, Commission Internationale de l'Éclairage chromaticity co-ordinates were found near the white region and their CCT values lie in the range 4900-5100 K indicating cool white. Decay time was measured for 545 nm emission of Ho3+ ion found in 7.652 and 8.734 µs at 355 nm excitation. The variation in lifetime was observed in ascending order with increasing Yb3+ concentration which supports PL emission spectra observation that with increasing Yb3+ concentration, rate of transition has changed. These studies reveal that Ho3+ and Yb3+ co-doped phosphor is useful for fabrication of white LEDs.

  17. Discovery of a phosphor for light emitting diode applications and its structural determination, Ba(Si,Al)5(O,N)8:Eu2+.

    PubMed

    Park, Woon Bae; Singh, Satendra Pal; Sohn, Kee-Sun

    2014-02-12

    Most of the novel phosphors that appear in the literature are either a variant of well-known materials or a hybrid material consisting of well-known materials. This situation has actually led to intellectual property (IP) complications in industry and several lawsuits have been the result. Therefore, the definition of a novel phosphor for use in light-emitting diodes should be clarified. A recent trend in phosphor-related IP applications has been to focus on the novel crystallographic structure, so that a slight composition variance and/or the hybrid of a well-known material would not qualify from either a scientific or an industrial point of view. In our previous studies, we employed a systematic materials discovery strategy combining heuristics optimization and a high-throughput process to secure the discovery of genuinely novel and brilliant phosphors that would be immediately ready for use in light emitting diodes. Despite such an achievement, this strategy requires further refinement to prove its versatility under any circumstance. To accomplish such demands, we improved our discovery strategy by incorporating an elitism-involved nondominated sorting genetic algorithm (NSGA-II) that would guarantee the discovery of truly novel phosphors in the present investigation. Using the improved discovery strategy, we discovered an Eu(2+)-doped AB5X8 (A = Sr or Ba, B = Si and Al, X = O and N) phosphor in an orthorhombic structure (A21am) with lattice parameters a = 9.48461(3) Å, b = 13.47194(6) Å, c = 5.77323(2) Å, α = β = γ = 90°, which cannot be found in any of the existing inorganic compound databases.

  18. Crystal Structure and Thermodynamic Stability of Ba/Ti-Substituted Pollucites for Radioactive Cs/Ba Immobilization

    DOE PAGES

    Xu, Hongwu; Chavez, Manuel E.; Mitchell, Jeremy N.; ...

    2015-04-23

    An analogue of the mineral pollucite (CsAlSi 2O 6), CsTiSi 2O 6.5 has a potential host phase for radioactive Cs. However, as 137Cs and 135Cs transmute to 137Ba and 135Ba, respectively, through the beta decay, it is essential to study the structure and stability of this phase upon Cs → Ba substitution. In this work, two series of Ba/Ti-substituted samples, Cs xBa (1-x)/2TiSi 2O 6.5 and Cs xBa 1-xTiSi 2O 7-0.5x, (x = 0.9 and 0.7), were synthesized by high-temperature crystallization from their respective precursors. Synchrotron X-ray diffraction and Rietveld analysis reveal that while Cs xBa (1-x)/2TiSi 2O 6.5 samplesmore » are phase-pure, Cs xBa 1-xTiSi 2O 7-0.5x samples contain Cs3x/(2+x)Ba (1-x)/(2+x)TiSi 2O 6.5 pollucites (i.e., also two-Cs-to-one-Ba substitution) and a secondary phase, fresnoite (Ba2TiSi2O8). Thus, the Cs xBa 1-xTiSi 2O 7-0.5x series is energetically less favorable than Cs xBa (1-x)/2TiSi 2O 6.5. To study the stability systematics of Cs xBa (1-x)/2TiSi 2O 6.5 pollucites, high-temperature calorimetric experiments were performed at 973 K with or without the lead borate solvent. Enthalpies of formation from the constituent oxides (and elements) have thus been derived. Our results show that with increasing Ba/(Cs + Ba) ratio, the thermodynamic stability of these phases decreases with respect to their component oxides. Hence, from the energetic viewpoint, continued Cs → Ba transmutation tends to destabilize the parent silicotitanate pollucite structure. However, the Ba-substituted pollucite co-forms with fresnoite (which incorporates the excess Ba), thereby providing viable ceramic waste forms for all the Ba decay products.« less

  19. Fano Resonance of Eu2+ and Eu3+ in (Eu,Gd)Te MBE Layers

    NASA Astrophysics Data System (ADS)

    Orlowski, B. A.; Kowalski, B. J.; Dziawa, P.; Pietrzyk, M.; Mickievicius, S.; Osinniy, V.; Taliashvili, B.; Kowalik, I. A.; Story, T.; Johnson, R. L.

    2006-11-01

    Resonant photoemission spectroscopy, with application of synchrotron radiation, was used to study the valence band electronic structure of clean surface of (EuGd)Te layers. Fano-type resonant photoemission spectra corresponding to the Eu 4d-4f transition were measured to determine the contribution of 4f electrons of Eu2+ and Eu3+ ions to the valence band. The resonant and antiresonant photon energies of Eu2+ ions were found as equal to 141 V and 132 eV, respectively and for Eu3+ ions were found as equal to 146 eV and 132 eV, respectively. Contribution of Eu2+4f electrons was found at the valence band edge while for Eu3+ it was located in the region between 3.5 eV and 8.5 eV below the valence band edge.

  20. 30-W Yb3+-pulsed fiber laser with wavelength tuning

    NASA Astrophysics Data System (ADS)

    Davydov, B. L.; Krylov, A. A.

    2007-12-01

    We have investigated various pulsed operation regimes of a diode-pumped Yb3+-doped fiber laser with both an acoustooptic filter and a shutter inside the resonator. To imbed the polarization-sensitive acoustooptic-tunable spectral filter into the polarization-nonmaintaining resonator, based on an “isotropic” single-mode fiber without “polarization’ losses, we have used a CaCO3 single-crystal nondispersive thermostable polarization splitter. Stable smooth bell-shaped laser pulses were obtained in the Q-switch generation regime across the entire wavelength tuning band. Their duration depended on the resonator travel time and their repetition rate was determined exclusively by the outer high-frequency generator controlling the acoustooptic shutter. A pulsed laser radiation tuning bandwidth of more than 20-nm at a repetition rate band of 10-100 kHz was observed in the amplification band of the Yb3+-doped fiber. A stable average power of 30 W of the pulsed 70-ns 100-kHz laser radiation in a near Gaussian beam was reached by means of the two-stage amplifier based on Yb3+-doped fibers with an enlarged mode field diameter (14 μm). The amplifier was pumped by λ = 975 nm CW multimode laser diodes with a maximum average power of 42 W.

  1. Quantitative megavoltage radiation therapy dosimetry using the storage phosphor KCl:Eu2+

    PubMed Central

    Han, Zhaohui; Driewer, Joseph P.; Zheng, Yuanshui; Low, Daniel A.; Li, H. Harold

    2009-01-01

    This work, for the first time, reports the use of europium doped potassium chloride (KCl:Eu2+) storage phosphor for quantitative megavoltage radiation therapy dosimetry. In principle, KCl:Eu2+ functions using the same photostimulatated luminescence (PSL) mechanism as commercially available BaFBr0.85I0.15:Eu2+ material that is used for computed radiography (CR) but features a significantly smaller effective atomic number—18 versus 49—making it a potentially useful material for nearly tissue-equivalent radiation dosimetry. Cylindrical KCl:Eu2+ dosimeters, 7 mm in diameter and 1 mm thick, were fabricated in-house. Dosimetric properties, including radiation hardness, response linearity, signal fading, dose rate sensitivity, and energy dependence, were studied with a laboratory optical reader after irradiation by a linear accelerator. The overall experimental uncertainty was estimated to be within ±2.5%. The findings were (1) KCl:Eu2+ showed satisfactory radiation hardness. There was no significant change in the stimulation spectra after irradiation up to 200 Gy when compared to a fresh dosimeter, indicating that this material could be reused at least 100 times if 2 Gy per use was assumed, e.g., for patient-specific IMRT QA. (2) KCl:Eu2+ exhibited supralinear response to dose after irradiation from 0 to 800 cGy. (3) After x ray irradiation, the PSL signal faded with time and eventually reached a fading rate of about 0.1%∕h after 12 h. (4) The sensitivity of the dosimeter was independent of the dose rate ranging from 15 to 1000 cGy∕min. (5) The sensitivity showed no beam energy dependence for either open x ray or megavoltage electron fields. (6) Over-response to low-energy scattered photons was comparable to radiographic film, e.g., Kodak EDR2 film. By sandwiching dosimeters between low-energy photon filters (0.3 mm thick lead foils) during irradiation, the over-response was reduced. The authors have demonstrated that KCl:Eu2+ dosimeters have many desirable

  2. Neutron spectroscopic study of crystalline electric field excitations in stoichiometric and lightly stuffed Yb 2 Ti 2 O 7

    DOE PAGES

    Gaudet, J.; Maharaj, D. D.; Sala, G.; ...

    2015-10-27

    Time-of-flight neutron spectroscopy has been used to determine the crystalline electric field Hamiltonian, eigenvalues and eigenvectors appropriate to the J=7/2 Yb 3+ ion in the candidate quantum spin ice pyrochlore magnet Yb 2Ti 2O 7. The precise ground state of this exotic, geometrically frustrated magnet is known to be sensitive to weak disorder associated with the growth of single crystals from the melt. Such materials display weak “stuffing,” wherein a small proportion, approximately 2%, of the nonmagnetic Ti 4+ sites are occupied by excess Yb 3+. We have carried out neutron spectroscopic measurements on a stoichiometric powder sample of Ybmore » 2Ti 2O 7, as well as a crushed single crystal with weak stuffing and an approximate composition of Yb 2+xTi 2–xO 7+y with x = 0.046. All samples display three crystalline electric field transitions out of the ground state, and the ground state doublet itself is identified as primarily composed of m J = ±1/2, as expected. However, stuffing at low temperatures in Yb 2+xTi 2–xO 7+y induces a similar finite crystalline electric field lifetime as is induced in stoichiometric Yb 2Ti 2O 7 by elevated temperature. In conclusion, an extended strain field exists about each local “stuffed” site, which produces a distribution of random crystalline electric field environments in the lightly stuffed Yb 2+xTi 2–xO 7+y, in addition to producing a small fraction of Yb ions in defective environments with grossly different crystalline electric field eigenvalues and eigenvectors.« less

  3. Eu 2+ –Eu 3+ valence transition in double, Eu-, and Na-doped PbSe from transport, magnetic, and electronic structure studies

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Wiendlocha, Bartlomiej; Kim, SunPhil; Lee, Yeseul

    The Eu atoms in Pb 1-xEu xSe have long been assumed to be divalent. We show that p-type doping of this magnetic semiconductor alloy with Na can modify the effective Eu valence: a mixed, Eu 2+–Eu 3+ state appears in Pb 1-x-yEu xNa ySe at particular values of y. Magnetization, carrier concentration, resistivity, and thermopower of Pb 1-x-yEu xNa ySe are reported for a number of samples with different x and y. A pronounced increase in thermopower at a given carrier concentration was identified and attributed to the presence of enhanced ionized impurity scattering. A strong decrease in the holemore » concentration is observed in Pb1-yNaySe when Eu is added to the system, which we attribute to a Eu 2+–Eu 3+ self-ionization process. This is evidenced by magnetization measurements, which reveal a significant reduction of the magnetic moment of Pb 1-xEu xSe upon alloying with Na. Further, a deviation of magnetization from a purely paramagnetic state, described by a Brillouin function, identifies antiferromagnetic interactions between the nearest-neighbor Eu atoms: a value of J ex/k B = -0.35 K was found for the exchange coupling parameter. The conclusion of a Eu 2+–Eu 3+ self-ionization process being in effect is supported further by the electronic structure calculations, which show that an instability of the 4f 7 configuration of the Eu 2+ ion appears with Na doping. In conclusion, schematically, it was found that the Eu 4f levels form states near enough to the Fermi energy that hole doping can lower the Fermi energy and trigger a reconfiguration of a 4f electronic shell.« less

  4. Eu 2+ –Eu 3+ valence transition in double, Eu-, and Na-doped PbSe from transport, magnetic, and electronic structure studies

    DOE PAGES

    Wiendlocha, Bartlomiej; Kim, SunPhil; Lee, Yeseul; ...

    2017-03-27

    The Eu atoms in Pb 1-xEu xSe have long been assumed to be divalent. We show that p-type doping of this magnetic semiconductor alloy with Na can modify the effective Eu valence: a mixed, Eu 2+–Eu 3+ state appears in Pb 1-x-yEu xNa ySe at particular values of y. Magnetization, carrier concentration, resistivity, and thermopower of Pb 1-x-yEu xNa ySe are reported for a number of samples with different x and y. A pronounced increase in thermopower at a given carrier concentration was identified and attributed to the presence of enhanced ionized impurity scattering. A strong decrease in the holemore » concentration is observed in Pb1-yNaySe when Eu is added to the system, which we attribute to a Eu 2+–Eu 3+ self-ionization process. This is evidenced by magnetization measurements, which reveal a significant reduction of the magnetic moment of Pb 1-xEu xSe upon alloying with Na. Further, a deviation of magnetization from a purely paramagnetic state, described by a Brillouin function, identifies antiferromagnetic interactions between the nearest-neighbor Eu atoms: a value of J ex/k B = -0.35 K was found for the exchange coupling parameter. The conclusion of a Eu 2+–Eu 3+ self-ionization process being in effect is supported further by the electronic structure calculations, which show that an instability of the 4f 7 configuration of the Eu 2+ ion appears with Na doping. In conclusion, schematically, it was found that the Eu 4f levels form states near enough to the Fermi energy that hole doping can lower the Fermi energy and trigger a reconfiguration of a 4f electronic shell.« less

  5. Bifunctional NaYF4:Er3+/Yb3+ submicron rods, implemented in quantum dot sensitized solar cell(Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Guerrero, J. Pablo; Cerdán Pasarán, Andrea; López-Luke, Tzarara; Ramachari, D.; Esparza, Diego; De la Rosa Cruz, Elder; Romero Arellano, Victor Hugo

    2016-09-01

    In this work are presented the results obtained with solar cells sensitized with quantum dots of cadmium sulphide (CdS) incorporating luminescent materials (NaYF4:Yb/Er). The study revealed that through using a bifunctional layer of NaYF4:Yb/Er submicron rods, the infrared radiation is absorbed in 980nm to generate luminescence in the visible region to 530nm, under the UP-conversion process, in the same way simultaneously, NaYF4:Yb/Er layer causes scattering toward the quantum dots, the emission and scattering generated by this material is reabsorbed by the QD-CdS, and these in turn are absorbing in its range of solar radiation absorption, Thus generates an increase in the electron injection into the semiconductor of TiO2. The results of a cell incorporating NaYF4: Yb/Er at 0.07M shown photoconversion efficiencies of 3.39% improving efficiency with respect to the reference solar cell without using NaYF4: Yb/Er of 1.99%. The obtained values of current and voltage showed a strong dependence of the percentage of NaYF4 Yb/Er, and the mechanism of incorporation of this material.

  6. Crystal structure and Temperature-Dependent Luminescence Characteristics of KMg4(PO4)3:Eu2+ phosphor for White Light-emitting diodes

    PubMed Central

    Chen, Jian; Liu, Yangai; Mei, Lefu; Liu, Haikun; Fang, Minghao; Huang, Zhaohui

    2015-01-01

    The KMg4(PO4)3:Eu2+ phosphor was prepared by the conventional high temperature solid-state reaction. The crystal structure, luminescence and reflectance spectra, thermal stability, quantum efficiency and the application for N-UV LED were studied respectively. The phase formation and crystal structure of KMg4(PO4)3:Eu2+ were confirmed from the powder X-ray diffraction and the Rietveld refinement. The concentration quenching of Eu2+ in the KMg4(PO4)3 host was determined to be 1mol% and the quenching mechanism was certified to be the dipole–dipole interaction. The energy transfer critical distance of as-prepared phosphor was calculated to be about 35.84Å. Furthermore, the phosphor exhibited good thermal stability and the corresponding activation energy ΔE was reckoned to be 0.24eV. Upon excitation at 365nm, the internal quantum efficiency of the optimized KMg4(PO4)3:Eu2+ was estimated to be 50.44%. The white N-UV LEDs was fabricated via KMg4(PO4)3:Eu2+, green-emitting (Ba,Sr)2SiO4:Eu2+, and red-emitting CaAlSiN3:Eu2+ phosphors with a near-UV chip. The excellent color rendering index (Ra = 96) at a correlated color temperature (5227.08K) with CIE coordinates of x = 0.34, y = 0.35 of the WLED device indicates that KMg4(PO4)3:Eu2+ is a promising blue-emitting phosphor for white N-UV light emitting diodes (LEDs). PMID:25855866

  7. Crystal structure and temperature-dependent luminescence characteristics of KMg4(PO4)3:Eu(2+) phosphor for white light-emitting diodes.

    PubMed

    Chen, Jian; Liu, Yangai; Mei, Lefu; Liu, Haikun; Fang, Minghao; Huang, Zhaohui

    2015-04-09

    The KMg4(PO4)3:Eu(2+) phosphor was prepared by the conventional high temperature solid-state reaction. The crystal structure, luminescence and reflectance spectra, thermal stability, quantum efficiency and the application for N-UV LED were studied respectively. The phase formation and crystal structure of KMg4(PO4)3:Eu(2+) were confirmed from the powder X-ray diffraction and the Rietveld refinement. The concentration quenching of Eu(2+) in the KMg4(PO4)3 host was determined to be 1 mol% and the quenching mechanism was certified to be the dipole-dipole interaction. The energy transfer critical distance of as-prepared phosphor was calculated to be about 35.84 Å. Furthermore, the phosphor exhibited good thermal stability and the corresponding activation energy ΔE was reckoned to be 0.24 eV. Upon excitation at 365 nm, the internal quantum efficiency of the optimized KMg4(PO4)3:Eu(2+) was estimated to be 50.44%. The white N-UV LEDs was fabricated via KMg4(PO4)3:Eu(2+), green-emitting (Ba,Sr)2SiO4:Eu(2+), and red-emitting CaAlSiN3:Eu(2+) phosphors with a near-UV chip. The excellent color rendering index (Ra = 96) at a correlated color temperature (5227.08 K) with CIE coordinates of x = 0.34, y = 0.35 of the WLED device indicates that KMg4(PO4)3:Eu(2+) is a promising blue-emitting phosphor for white N-UV light emitting diodes (LEDs).

  8. Multipolar Kondo effect in a S10-P32 mixture of 173Yb atoms

    NASA Astrophysics Data System (ADS)

    Kuzmenko, Igor; Kuzmenko, Tetyana; Avishai, Yshai; Jo, Gyu-Boong

    2018-02-01

    Whereas in the familiar Kondo effect the exchange interaction is dipolar, there are systems in which the exchange interaction is multipolar, as has been realized in a recent experiment. Here, we study multipolar Kondo effect in a Fermi gas of cold 173Yb atoms. Making use of different ac polarizabilities of the electronic ground state Yb (S10 ) and the long-lived metastable state Yb*(P32 ), it is suggested that the latter atoms can be localized and serve as a dilute concentration of magnetic impurities while the former ones remain itinerant. The exchange mechanism between the itinerant Yb and the localized Yb* atoms is analyzed and shown to be antiferromagnetic. The quadrupole and octupole interactions act to enhance the Kondo temperature TK that is found to be experimentally accessible. The bare exchange Hamiltonian needs to be decomposed into dipole (d), quadrupole (q), and octupole (o) interactions in order to retain its form under renormalization group (RG) analysis, in which the corresponding exchange constants (λd,λq, and λo) flow independently. Numerical solution of the RG scaling equations reveals a few finite fixed points. Arguments are presented that the Fermi-liquid fixed point at low temperature is unstable, indicating that the impurity is overscreened, which suggests a non-Fermi-liquid phase. The impurity contributions to the specific heat, entropy, and the magnetic susceptibility are calculated in the weak coupling regime (T ≫TK ), and are compared with the analogous results obtained for the standard case of dipolar exchange interaction (the s -d Hamiltonian).

  9. GHz Yb:KYW oscillators in time-resolved spectroscopy

    NASA Astrophysics Data System (ADS)

    Li, Changxiu; Krauß, Nico; Schäfer, Gerhard; Ebner, Lukas; Kliebisch, Oliver; Schmidt, Johannes; Winnerl, Stephan; Hettich, Mike; Dekorsy, Thomas

    2018-02-01

    A high-speed asynchronous optical sampling system (ASOPS) based on Yb:KYW oscillators with 1-GHz repetition rate is reported. Two frequency-offset-stabilized diode-pumped Yb:KYW oscillators are employed as pump and probe source, respectively. The temporal resolution of this system within 1-ns time window is limited to 500 fs and the noise floor around 10-6 (ΔR/R) close to the shot-noise level is obtained within an acquisition time of a few seconds. Coherent acoustic phonons are investigated by measuring multilayer semiconductor structures with multiple quantum wells and aluminum/silicon membranes in this ASOPS system. A wavepacket-like phonon sequence at 360 GHz range is detected in the semiconductor structures and a decaying sequence of acoustic oscillations up to 200 GHz is obtained in the aluminum/silicon membranes. Coherent acoustic phonons generated from semiconductor structures are further manipulated by a double pump scheme through pump time delay control.

  10. Two-wavelength, passive self-injection-controlled operation of diode-pumped cw Yb-doped crystal lasers.

    PubMed

    Louyer, Yann; Wallerand, Jean-Pierre; Himbert, Marc; Deneva, Margarita; Nenchev, Marin

    2003-09-20

    We demonstrate and investigate a peculiar mode of cw Yb3+-doped crystal laser operation when two emissions, at two independently tunable wavelengths, are simultaneously produced. Both emissions are generated from a single pumped volume and take place in either a single beam or spatially separated beams. The laser employs original two-channel cavities that use a passive self-injection-locking (PSIL) control to reduce intracavity loss. The advantages of the application of the PSIL technique and some limitations are shown. The conditions for two-wavelength multimode operation of the cw quasi-three-level diode-pumped Yb3+ lasers and the peculiarity of such an operation are carried out both theoretically and experimentally. The results reported are based on the example of a Yb3+:GGG laser but similar results are also obtained with a Yb3+:YAG laser. The laser operates in the 1023-1033-nm (1030-1040-nm) range with a total output power of 0.4 W. A two-wavelength, single longitudinal mode generation is also obtained.

  11. Enhanced frequency upconversion in Er3+-Yb3+ codoped heavy metal oxides based tellurite glasses.

    PubMed

    Azam, Mohd; Rai, Vineet Kumar

    2018-01-24

    The spectroscopic investigations on the Er 3+ /Yb 3+ ions doped/codoped TeO 2 -ZnO (TZ), TeO 2 -ZnO-WO 3 (TZW) and TeO 2 -ZnO-WO 3 -TiO 2 (TZWTi) heavy metal oxide (HMO) glasses have been made. The absorption, photoluminescence, decay curve and Judd-Ofelt analysis have been performed to optimise the optical properties of the Er 3+ /Yb 3+ ions. The effect of incorporation of HMOs like WO 3 and TiO 2 in the Er 3+ /Yb 3+ doped/codoped TZ glass on its optical properties have been investigated. The enhancement in upconversion emission intensity has been explained on the basis of efficient energy transfer and inhomogeneous local field generation around the rare earth ions. The spectroscopic quality factor, absorption and stimulated emission cross-sections, optical gain, quantum efficiency (∼17.53%), energy transfer efficiency (∼61.64%), colour purity (∼94.7%) and ionic nature of the bonding have been determined. The Er 3+ -Yb 3+ -TZWTi glass can be used in visible lasers, yellowish green optical devices and home appliances.

  12. Tectonic uplift-influenced monsoonal changes promoted hominin occupation of the Luonan Basin: Insights from a loess-paleosol sequence, eastern Qinling Mountains, central China

    NASA Astrophysics Data System (ADS)

    Fang, Qian; Hong, Hanlie; Zhao, Lulu; Furnes, Harald; Lu, Huayu; Han, Wen; Liu, Yao; Jia, Zhuoyue; Wang, Chaowen; Yin, Ke; Algeo, Thomas J.

    2017-08-01

    Quaternary soil deposits from northern and southern China are distinctly different, reflecting variability of the East Asian monsoon north and south of the Qinling Mountains. Coeval sediments from the transitional climatic zone of central China, which are little studied to date, have the potential to improve our understanding of Quaternary monsoon changes and associated influences on hominin occupation of this region. Here, we investigate in detail a well-preserved and continuous Quaternary loess-paleosol sequence (Shangbaichuan) from the Luonan Basin, using a variety of weathering indices including major and trace element ratios, clay mineralogy, and Fe-oxide mineralogy. The whole-rock samples display similar rare earth element patterns characterized by upper continental crustal ratios: (La/Yb)N ≈ 9.5 and Eu/Eu* ≈ 0.65. Elemental data such as (La/Yb)N, La/Th and Eu/Eu* ratios show a high degree of homogeneity, suggesting that dust in the source region may have been thoroughly mixed and recycled, resulting in all samples having a uniform initial composition. Indices for pedogenic weathering such as Na/K, Ba/Sr, Rb/Sr, CIA, CIW, CPA, PIA, kaolinite/illite, (kaolinite + smectite)/illite, and hematite/(hematite + goethite) exhibit similar secular trends and reveal a four-stage accumulation history. The indices also indicate that the climate was warmer and wetter during the most recent interglacial stage, compared with coeval environments of the Chinese Loess Plateau. Secular changes in weathering intensity can be related to stepwise uplift of the Qinling Mountains and variation in East Asian monsoon intensity, both of which played significant roles in controlling climate evolution in the Luonan Basin. Furthermore, intensified aridity and winter monsoon strength in dust source areas, as evidenced by mineralogic and geochemical changes, may have been due to the mid-Pleistocene climate transition. Based on temporal correlation of warmer and wetter climatic conditions

  13. Preparation of high density heavy metal fluoride glasses with extended ultraviolet and infra red ranges, and such high density heavy metal fluoride glasses

    NASA Technical Reports Server (NTRS)

    Martin, Steven W. (Inventor); Huebsch, Jesse (Inventor)

    2001-01-01

    A heavy metal fluoride glass composition range (in mol percent) consisting essentially of: (16-30)BaF.sub.2.(8-26)HfF.sub.4.(6-24)InF.sub.3 or GaF.sub.3.(4-16)CdF.sub.2.(6-24)YbF.sub.3.(4-22)ZnF.sub.2. In an alternative embodiment, a heavy metal fluoride glass composition range (in mol percent) comprises (16-30)BaF.sub.2.(8-26)HfF.sub.4.(6-24) of (0-24)InF.sub.3, (0-24)GaF.sub.3 and (0-19)AlF.sub.3.(1-16)CdF.sub.2.(6-24)YbF.sub.3.(4-26)ZnF.sub.2. A preferred heavy metal fluoride glass produced in accordance with the present invention comprises a composition (in mol %) and comprises about 26BaF.sub.2.18HfF.sub.4.7InF.sub.3.5GaF.sub.3.10CdF.sub.2.18YbF.sub.3. 16ZnF.sub.2. A preferred heavy metal fluoride glass has maximum thickness of most preferably about 3 mm. Another preferred heavy metal fluoride glass comprises a composition (in mol %) and comprises about 26BaF.sub.2.18HfF.sub.4.12AlF.sub.3.10CdF.sub.2.18YbF.sub.3.16ZnF.sub.2.

  14. Low-phonon-frequency chalcogenide crystalline hosts for rare earth lasers operating beyond three microns

    DOEpatents

    Payne, Stephen A.; Page, Ralph H.; Schaffers, Kathleen I.; Nostrand, Michael C.; Krupke, William F.; Schunemann, Peter G.

    2000-01-01

    The invention comprises a RE-doped MA.sub.2 X.sub.4 crystalline gain medium, where M includes a divalent ion such as Mg, Ca, Sr, Ba, Pb, Eu, or Yb; A is selected from trivalent ions including Al, Ga, and In; X is one of the chalcogenide ions S, Se, and Te; and RE represents the trivalent rare earth ions. The MA.sub.2 X.sub.4 gain medium can be employed in a laser oscillator or a laser amplifier. Possible pump sources include diode lasers, as well as other laser pump sources. The laser wavelengths generated are greater than 3 microns, as becomes possible because of the low phonon frequency of this host medium. The invention may be used to seed optical devices such as optical parametric oscillators and other lasers.

  15. Characterization of ancient glass excavated in Enez (Ancient Ainos) Turkey by combined Instrumental Neutron Activation Analysis and Fourier Transform Infrared spectrometry techniques

    NASA Astrophysics Data System (ADS)

    Akyuz, Sevim; Akyuz, Tanil; Mukhamedshina, Nuranya M.; Mirsagatova, A. Adiba; Basaran, Sait; Cakan, Banu

    2012-05-01

    Ancient glass fragments excavated in the archaeological district Enez (Ancient Ainos)-Turkey were investigated by combined Instrumental Neutron Activation Analysis (INAA) and Fourier Transform Infrared (FTIR) spectrometry techniques. Multi-elemental contents of 15 glass fragments that belong to Hellenistic, Roman, Byzantine, and Ottoman Periods, were determined by INAA. The concentrations of twenty six elements (Na, K, Ca, Sc, Cr, Mn, Fe, Co, Cu, Zn, As, Rb, Sr, Sb, Cs, Ba, Ce, Sm, Eu, Tb, Yb, Lu, Hf, Ta, Au and Th), which might be present in the samples as flux, stabilizers, colorants or opacifiers, and impurities, were examined. Chemometric treatment of the INAA data was performed and principle component analysis revealed presence of 3 distinct groups. The thermal history of the glass samples was determined by FTIR spectrometry.

  16. Chemical characterization of gas- and oil-bearing shales by instrumental neutron activation analysis

    USGS Publications Warehouse

    Frost, J.K.; Koszykowski, R.F.; Klemm, R.C.

    1982-01-01

    The concentration of As, Ba, Ca, Co, Cr, Cs, Dy, Eu, Fe, Ga, Hf, K, La, Lu, Mn, Mo, Na, Ni, Rb, Sb, Sc, Se, Sm, Sr, Ta, Tb, Th, U, Yb, and Zn were determined by instrumental neutron activation analysis in block shale samples of the New Albany Group (Devonian-Mississippian) in the in the Illinois Basin. Uranium content of the samples was as high as 75 ppm and interfered in the determination of samarium, molybdenum, barium and cerium. In the determination of selenium a correction was made for interference from tantalum. U, As, Co, Mo, Ni and Sb as well as Cu, V and pyritic sulphur which were determined by other methods, were found to correlate positively with the organic carbon content of the samples. ?? 1982 Akade??miai Kiado??.

  17. Ternary oxide nanostructures and methods of making same

    DOEpatents

    Wong, Stanislaus S [Stony Brook, NY; Park, Tae-Jin [Port Jefferson, NY

    2009-09-08

    A single crystalline ternary nanostructure having the formula A.sub.xB.sub.yO.sub.z, wherein x ranges from 0.25 to 24, and y ranges from 1.5 to 40, and wherein A and B are independently selected from the group consisting of Ag, Al, As, Au, B, Ba, Br, Ca, Cd, Ce, Cl, Cm, Co, Cr, Cs, Cu, Dy, Er, Eu, F, Fe, Ga, Gd, Ge, Hf, Ho, I, In, Ir, K, La, Li, Lu, Mg, Mn, Mo, Na, Nb, Nd, Ni, Os, P, Pb, Pd, Pr, Pt, Rb, Re, Rh, Ru, S, Sb, Sc, Se, Si, Sm, Sn, Sr, Ta, Tb, Tc, Te, Ti, Tl, Tm, U, V, W, Y, Yb, and Zn, wherein the nanostructure is at least 95% free of defects and/or dislocations.

  18. Transparent Oxyfluoride Nano-Glass-Ceramics Doped with Pr3+ and Pr3+-Yb3+ for NIR Emission

    NASA Astrophysics Data System (ADS)

    Gorni, Giulio; Cosci, Alessandro; Pelli, Stefano; Pascual, Laura; Durán, Alicia; Pascual, M. J.

    2016-12-01

    Pr3+-Yb3+ co-doped oxyfluoride glasses and glass-ceramics (GC) containing LaF3 nanocrystals have been prepared to obtain NIR emission of Yb3+ ions upon Pr3+ excitation in the blue region of the visible spectrum. Two different compositions have been tested 0.1-0.5 Pr-Yb and 0.5-1 Pr-Yb, in addition to Pr3+ singly doped samples. The crystallization mechanism of the nano-glass-ceramics was studied by DTA revealing that it occurs from a constant number of nuclei, the crystal growth being limited by diffusion. HR-TEM demonstrated that phase separation acts as precursor for LaF3 crystallization and a detailed analysis of the chemical composition (EDXS) revealed the enrichment in RE3+ ions inside the initial phase separated droplets, from which the LaF3 crystals are formed. The RE3+ ions incorporation inside LaF3 crystals was also proved by photoluminescence measurements showing Stark splitting of the RE3+ ions energy levels in the glass-ceramic samples. Lifetimes measurements showed the existence of a better energy transfer process between Pr3+ and Yb3+ ions in the glass-ceramics compared to the as made glass, and the highest value of energy transfer efficiency is 59% and the highest theoretical quantum efficiency is 159%, obtained for glass-ceramics GC0.1-0.5 Pr-Yb treated at 620 ºC-40 h.

  19. Investigation of ASE and SRS effects on 1018nm short-wavelength Yb3+-doped fiber laser

    NASA Astrophysics Data System (ADS)

    Xie, Zhaoxin; Shi, Wei; Sheng, Quan; Fu, Shijie; Fang, Qiang; Zhang, Haiwei; Bai, Xiaolei; Shi, Guannan; Yao, Jianquan

    2017-03-01

    1018nm short wavelength Yb3+-doped fiber laser can be widely used for tandem-pumped fiber laser system in 1 μm regime because of its high brightness and low quantum defect (QD). In order to achieve 1018nm short wavelength Yb3+-doped fiber laser with high output power, a steady-state rate equations considering the amplified spontaneous emission (ASE) and Stimulated Raman Scattering (SRS) has been established. We theoretically analyzed the ASE and SRS effects in 1018nm short wavelength Yb3+-doped fiber laser and the simulation results show that the ASE is the main restriction rather than SRS for high power 1018nm short wavelength Yb3+-doped fiber laser, besides the high temperature of fiber is also the restriction for high output power. We use numerical solution of steady-state rate equations to discuss how to suppress ASE in 1018nm short wavelength fiber laser and how to achieve high power 1018nm short-wavelength fiber laser.

  20. Ultralow-threshold laser and blue shift cooperative luminescence in a Yb{sup 3+} doped silica microsphere

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Huang, Yantang, E-mail: g@fzu.edu.cn; Huang, Yu; Zhang, Peijin

    2014-02-15

    An experimental investigation on ultralow threshold laser and blue shift cooperative luminescence (CL) in a Yb{sup 3+} doped silica microsphere (YDSM) with continuous-wave 976 nm laser diode pumping is reported. The experimental results show that the YDSM emits laser oscillation with ultralow threshold of 2.62 μW, and the laser spectrum is modulated by the microsphere morphology characteristics. In addition, blue emission of YDSM is also observed with the increase of pump power, which is supposed to be generated by CL of excited Yb ion-pairs with the absorption of 976 nm photons and Si-O vibration phonons, and the process is explainedmore » with an energy level diagram. This property of the blue shift CL with phonons absorption in the Yb{sup 3+}doped microcavity makes it attractive for the application of laser cooling based on anti-Stokes fluorescence emission, if the Yb{sup 3+}doped microcavity made from with low phonon energy host materials.« less