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Sample records for eu tm yb

  1. Large-scale synthesis of Lu{sub 2}O{sub 3}:Ln{sup 3+} (Ln{sup 3+} = Eu{sup 3+}, Tb{sup 3+}, Yb{sup 3+}/Er{sup 3+}, Yb{sup 3+}/Tm{sup 3+}, and Yb{sup 3+}/Ho{sup 3+}) microspheres and their photoluminescence properties

    SciTech Connect

    Gao, Yu; Gong, Jian; Fan, Miaomiao; Fang, Qinghong; Wang, Na; Han, Wenchi; Xu, Zhenhe

    2012-12-15

    Graphical abstract: In this work, multicolor and monodisperse Lu{sub 2}O{sub 3}:Ln{sup 3+} (Ln{sup 3+} = Eu{sup 3+}, Tb{sup 3+}, Yb{sup 3+}/Er{sup 3+}, Yb{sup 3+}/Tm{sup 3+}, and Yb{sup 3+}/Ho{sup 3+}) microspheres were prepared by a homogeneous precipitation method followed by a subsequent calcination process. Display Omitted Highlights: ? Lu{sub 2}O{sub 3}:Ln{sup 3+} microspheres were prepared by a precipitation followed by a calcination process. ? Lu{sub 2}O{sub 3}:Eu{sup 3+}/Tb{sup 3+} samples exhibit respective red or green emissions. ? Lu{sub 2}O{sub 3}:Yb{sup 3+}/Er{sup 3+}/Tm{sup 3+}/Ho{sup 3+} exhibit emissions of green, blue, yellow-green, respectively. ? These finding may find potential applications in bioanalysis and field emission displays. -- Abstract: In this work, multicolor and monodisperse Lu{sub 2}O{sub 3}:Ln{sup 3+} (Ln{sup 3+} = Eu{sup 3+}, Tb{sup 3+}, Yb{sup 3+}/Er{sup 3+}, Yb{sup 3+}/Tm{sup 3+}, and Yb{sup 3+}/Ho{sup 3+}) microspheres were prepared by a homogeneous precipitation method followed by a subsequent calcination process. X-ray diffraction (XRD), Fourier transformed infrared (FT-IR), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), transmission electron microscopy (TEM), photoluminescence (PL) spectra, and cathodoluminescence (CL) spectra were employed to characterize the samples. Upon ultraviolet and low-voltage electron beams excitation, Lu{sub 2}O{sub 3}:Ln{sup 3+} (Ln{sup 3+} = Eu{sup 3+} and Tb{sup 3+}) samples exhibit respective bright red (Eu{sup 3+}, {sup 5}D{sub 0} ? {sup 7}F{sub 2}) and green (Tb{sup 3+}, {sup 5}D{sub 4} ? {sup 7}F{sub 5}) down-conversion (DC) emissions. Under 980 nm NIR irradiation, Lu{sub 2}O{sub 3}:Ln{sup 3+} (Ln{sup 3+} = Yb{sup 3+}/Er{sup 3+}, Yb{sup 3+}/Tm{sup 3+}, and Yb{sup 3+}/Ho{sup 3+}) exhibit characteristic up-conversion (UC) emissions of green (Er{sup 3+}, {sup 4}S{sub 3/2}, {sup 2}H{sub 11/2} ? {sup 4}I{sub 15/2}), blue (Tm{sup 3+}, {sup 1}G{sub 4} ? {sup 3}H{sub 6}) and yellow-green (Ho{sup 3+}, {sup 5}F{sub 4}, {sup 5}S{sub 2} ? {sup 5}I{sub 8}), respectively. These finding may find potential applications in bioanalysis, optoelectronic and nanoscale devices, field emission displays, and so on.

  2. Syntheses, structure and rare earth metal photoluminescence of new and known isostructural A{sub 2}Mo{sub 4}Sb{sub 2}O{sub 18} (A=Ce, Pr, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu) compounds

    SciTech Connect

    Mohitkar, Shrikant A.; Kalpana, G.; Vidyasagar, K.

    2011-04-15

    Nine new A{sub 2}Mo{sub 4}Sb{sub 2}O{sub 18} (A=Ce, Pr, Eu, Tb, Ho, Er, Tm, Yb, Lu) compounds have been synthesized by solid-state reactions. They are isostructural with six reported analogues of yttrium and other lanthanides and the monoclinic unit cell parameters of all fifteen of them vary linearly with the size of A{sup 3+} ion. Single crystal X-ray structures of eight A{sub 2}Mo{sub 4}Sb{sub 2}O{sub 18} (A=Ce, Pr, Eu, Gd, Tb, Ho, Er, Tm) compounds have been determined. Neat A{sub 2}Mo{sub 4}Sb{sub 2}O{sub 18} (A=Pr, Sm, Eu, Tb, Dy, Ho, Er, Tm) compounds exhibit characteristic rare earth metal photoluminescence. -- Graphical abstract: Among the fifteen isostructural A{sub 2}Mo{sub 4}Sb{sub 2}O{sub 18} (A=rare earth metal) molybdoantimonites, eight (A=Pr, Sm, Eu, Tb, Dy, Ho, Er, Tm) compounds exhibit neat characteristic lanthanide photoluminescence in the 200-800 nm range at room temperature. Display Omitted Research highlights: {yields} Syntheses of nine new A{sub 2}Mo{sub 4}Sb{sub 2}O{sub 18} (A=Ce, Pr, Eu, Tb, Ho, Er, Tm, Yb, Lu) compounds. {yields} X-ray structures of eight A{sub 2}Mo{sub 4}Sb{sub 2}O{sub 18} (A=Ce, Pr, Eu, Gd, Tb, Ho, Er, Tm) compounds. {yields} Photoluminescence of neat A{sub 2}Mo{sub 4}Sb{sub 2}O{sub 18} (A=Pr, Sm, Eu, Tb, Dy, Ho, Er, Tm) compounds.

  3. Intense red upconversion luminescence from Tm3Yb3 codoped transparent glass ceramic

    E-print Network

    Cao, Wenwu

    Intense red upconversion luminescence from Tm3Yb3 codoped transparent glass ceramic Wei Xu,1 (Doc. ID 158093); published January 12, 2012 Tm3Yb3 codoped transparent glass ceramic containing -PbF2 choose the oxyfluoride glass ceramic as the host material in our investigations. Through thermal treat

  4. Near-infrared quantum cutting in YPO4:Yb3+, Tm3+ via cooperative energy transfer

    NASA Astrophysics Data System (ADS)

    Xie, Lechun; Wang, Yuhua; Zhang, Huijuan

    2009-02-01

    The experimental evidences of the cooperative energy transfer from Tm3+ to Yb3+ have been presented by the photoluminescence properties of YPO4:Yb3+, Tm3+, and the decay lifetime curves of the G14 emission of Tm3+. Near-infrared quantum cutting involving the F25/2?F27/2 emission of Yb3+ (about 970-1010 nm) is achieved upon the excitation of G14 energy level of Tm3+ at 474 nm. Quantum efficiency related to Yb3+ concentration is calculated, and the maximum efficiency reaches 172.8%. Because the energy of Yb3+ transition is matched with the band gap of the crystalline Si, the phosphors could be applied potentially in silicon-based solar cells.

  5. Upconversion emission properties of CeO2: Tm3+, Yb3+ inverse opal photonic crystals

    NASA Astrophysics Data System (ADS)

    Cheng, Gong; Wu, Hangjun; Yang, Zhengwen; Liao, Jiayan; Lai, Shenfeng; Qiu, Jianbei; Song, Zhiguo

    2014-10-01

    The ordered and disordered templates were assembled by vertical deposition of polystyrene microspheres. The CeO2: Tm3+, Yb3+ precursor solution was used to infiltrate into the voids of the ordered and disordered templates, respectively. Then the ordered and disordered templates were calcined at 950°C in an air furnace, and the CeO2: Tm3+, Yb3+ inverse opals were obtained. The upconversion emissions from CeO2: Tm3+, Yb3+ inverse opals were suppressed due to the photon trapping caused by Bragg reflection of lattice planes when the upconversion emission band was in the range of the photonic band gaps in the inverse opals.

  6. Infrared luminescence of Tm{sup 3+}/Yb{sup 3+} codoped lanthanum aluminum germanate glasses

    SciTech Connect

    Zhang Qiang; Zhang Guang; Chen Guorong; Qiu Jianrong; Chen Danping

    2010-01-15

    Tm{sup 3+} doped and Tm{sup 3+}/Yb{sup 3+} codoped lanthanum aluminum germanate (LAG) glasses are prepared by melt-quenching method and characterized optically. Based on the measurement of absorption spectrum, Judd-Ofelt intensity parameters ({Omega}{sub 2},{Omega}{sub 4},{Omega}{sub 6}) are calculated. The radiation emission rates, branching ratios, and lifetimes of Tm{sup 3+} are calculated to evaluate the spectroscopic properties of Tm{sup 3+} in LAG glass. The infrared emission properties of the samples are investigated and the results show that the 1.8 {mu}m emission can be greatly enhanced by adding proper amount of Yb{sup 3+} under the excitation of 980 nm. The energy transfer processes of Yb{sup 3+}-Yb{sup 3+} and Yb{sup 3+}-Tm{sup 3+} are analyzed, and the results show that Yb{sup 3+} ions can transfer their energy to Tm{sup 3+} ions with high efficiency and large energy transfer coefficient.

  7. Thermoelectric properties of Yb(x)Eu(1-x)Cd2Sb2.

    PubMed

    Zhang, H; Fang, L; Tang, M-B; Man, Z Y; Chen, H H; Yang, X X; Baitinger, M; Grin, Y; Zhao, J-T

    2010-11-21

    The thermoelectric performance of EuCd(2)Sb(2) and YbCd(2)Sb(2) was improved by mixed cation occupation. The composition, structure, and thermoelectric properties of Yb(x)Eu(1-x)Cd(2)Sb(2) (x=0, 0.5, 0.75, and 1) have been investigated. Polycrystalline samples are prepared by direct reaction of the elements. Thermoelectric properties were investigated after densification of the materials by spark plasma sintering. Yb(x)Eu(1-x)Cd(2)Sb(2) crystallizes in the P3m1 space group. The lattice parameters increase with the europium content. These materials show low electrical resistivity, high Seebeck coefficient, and low thermal conductivity together with high carrier concentration and high carrier mobility. ZT values of 0.88 and 0.97 are obtained for Yb(0.5)Eu(0.5)Cd(2)Sb(2) and Yb(0.75)Eu(0.25)Cd(2)Sb(2) at 650 K, respectively. PMID:21090867

  8. Synthesis and optical properties of transparent glass ceramics with Eu,Yb:PbF2 nanocrystals

    NASA Astrophysics Data System (ADS)

    Loiko, P. A.; Rachkovskaya, G. E.; Zakharevich, G. B.; Yumashev, K. V.

    2015-02-01

    Transparent oxyfluoride glass ceramics containing Eu,Yb:PbF2 nanocrystals (average diameter 6.5 nm) is synthesized by secondary heat treatment of the initial SiO2-PbO-PbF2-CdF2 glass doped with YbF3 (1 mol %) and Eu2O3 (1 mol %); the optical absorption and the upconversion luminescence of this ceramics are studied. Intense orange luminescence (the CIE color coordinates are x = 0.602, y = 0.398) is obtained under excitation by a laser diode at a wavelength of 960 nm.

  9. Eu3+, Yb3+ and Eu3+-Yb3+ complexes with salicylic acid and 1,10-phenanthroline: synthesis, photoluminescent properties and energy transfer.

    PubMed

    Sharma, Garima; Narula, Anudeep Kumar

    2015-03-01

    This paper reports the synthesis of mononuclear Eu(3+), Yb(3+) and binuclear Eu(3+)-Yb(3+) complexes by solution technique, maintaining the stoichiometric ratios of salicylic acid (sal) and 1,10-phenanthroline (phen) as ligands and their structural, optical and morphological properties were demonstrated. The FTIR absorption spectra indicates that sal and phen are coordinated to the rare earth ion through the chemical bonds formed between oxygen and nitrogen atoms of the ligands and rare earth ion. The UV-vis absorption spectra of the complexes reflect the absorption spectra of the ligands and there is no significant change in the wavelength and band profiles between the spectra of the ligands and that of complexes except a slight red shift. The photoluminescent emission spectra of the complexes in visible and near-infrared (NIR) region was recorded and indicated the emission quenching in complex (2) due to the energy transfer from Eu(3+) ion to Yb(3+) ion. The morphological properties of the complexes as characterized by SEM revealed different morphologies of mononuclear and binuclear complexes. PMID:25653135

  10. Growth, thermal, and spectroscopic properties of a Cr,Yb,Ho,Eu:YAP laser crystal

    NASA Astrophysics Data System (ADS)

    Zhang, Huili; Sun, Dunlu; Luo, Jianqiao; Chen, Jiakang; Yang, Huajun; Xiao, Jingzhong; Zhang, Qingli; Yin, Shaotang

    2014-06-01

    A new Cr,Yb,Ho,Eu:YAlO3(YAP) laser crystal was successfully grown by the Czochralski method. Thermal properties were investigated along the a, b, and c crystalline axes. Results indicate that the Cr,Yb,Ho,Eu:YAP crystal has large anisotropic thermal expansion and that the suitable crystal growth direction is the b axis. The Debye temperatures were fitted, and the lattice vibration frequencies were calculated. Spectroscopic measurements show that Cr3+ and Yb3+ can be used as sensitizers of Ho3+ ions, and Eu3+ ions can play a role of the deactivator in decreasing the lifetime of laser lower level 5I7 from 8.69 ms to 1.89 ms, which is beneficial in decreasing laser threshold and increasing laser conversion efficiency. All these findings suggest that the Cr,Yb,Ho,Eu:YAP crystal is a new potential candidate for realizing 2.8-3 ?m laser output pumped by a 970 nm laser diode or pulsed flash lamp.

  11. Revisiting literature observations on photodarkening in Yb3+doped fiber considering the possible presence of Tm impurities

    E-print Network

    Peretti, Romain; Jurdyc, Anne-Marie

    2013-01-01

    Ytterbium (Yb) doped fiber lasers are known to be affected by the creation of color centers during lasing (socalled photodarkening (PD)). In a previous work, this defect creation was investigated from a spectroscopic point of view, showing the presence of traces (ppb) of thulium (Tm) in the Yb doped fiber. It was shown that Tm has a strong impact on the defect creation process involved in PD. In this paper, we compare the results from the literature with our Tm hypothesis, without finding any contradiction. Moreover, this hypothesis can be an explanation for the discrepancies in the literature.

  12. Up-conversion luminescence properties and energy transfer of Tm3+/Yb3+ co-doped BaLa2ZnO5

    NASA Astrophysics Data System (ADS)

    Xie, Jing; Mei, Lefu; Deng, Junru; Liu, Haikun; Ma, Bin; Guan, Ming; Liao, Libing; Lv, Guocheng

    2015-11-01

    Tm3+/Yb3+ co-doped BaLa2ZnO5 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 BaLa2ZnO5 among different co-doping concentrations. The structure of BaLa2ZnO5:0.75% Tm/10% Yb phosphor was refined by the Rietveld method and results show the decreased unit cell parameters and cell volume after doping Tm3+/Yb3+, indicating that Tm3+/Yb3+ have successfully replaced La3+. Under excitation at 980 nm, Tm3+/Yb3+ co-doped BaLa2ZnO5 phosphors present bright blue emission near 478 nm generated by the 1G4?3H6 transition and weak red emissions around 653 nm and 692 nm generated by the 1G4?3F4 and 3F3?3H6 transitions of Tm3+, respectively. The UC luminescence properties of BaLa2ZnO5 phosphors co-doped with different Tm3+/Yb3+ concentrations were investigated, and the related UC mechanisms of Tm3+/Yb3+ co-doped BaLa2ZnO5 depending on pump power were studied in detail.

  13. White Lighting Upconversion in Tm3+/Ho3+/Yb3+ Co-Doped CaWO4

    NASA Astrophysics Data System (ADS)

    Chung, Jun Ho; Yeop Lee, Sang; Shim, Kwang Bo; Ryu, Jeong Ho

    2012-05-01

    Controllable white upconversion (UC) luminescence was obtained from Tm3+/Ho3+/Yb3+-codoped CaWO4. Under the excitation of a 980 nm single wavelength laser diode, the Tm3+/Ho3+/Yb3+-codoped CaWO4 exhibited bright white UC luminescence composed of blue emission from Tm3+ and green and red emissions from Ho3+ visible to the naked eye. The intensity ratios of green, red, and blue UC emissions varied with Tm3+/Ho3+ concentrations, which can control white UC emission ranging from the cool to the warm region. Various white UC colors can be easily changed by adjusting the Tm3+/Ho3+ concentrations in the CaWO4 matrix.

  14. Visible to near-infrared downconversion in Tm3+/Yb3+ co-doped chalcohalide glasses for solar spectra converter

    NASA Astrophysics Data System (ADS)

    Huang, Fei; Chen, Liyan; Han, Ying; Tang, Junzhou; Nie, Qiuhua; Zhang, Peiqing; Xu, Yinsheng

    2015-07-01

    Near-infrared downconversion which can be used to improve the utilization of solar spectral has drawn much attention. In this work, chalcohalide glasses with compositions of 50GeS2-25Ga2S3-25CsCl (in mol.%): 0.1 wt.% Tm2 S3 - x wt.% Yb2S3 (x = 0, 0.1, 0.2, 0.3) were synthesized by vacuumed melt-quenching method. Absorption spectra, emission spectra, excitation spectra, and decay measurements were performed to prove the occurrence of cooperative energy transfer from the 1G4 level of Tm3+ ions to two Yb3+ ions. Quantum efficiency depends on Yb3+ concentration is calculated, and the highest is 114.1%. The photon energy of Yb3+ emission around 1 ?m well matched with the operation band gap of the crystalline Si, so the glasses could potentially be applied in Si-based solar cell.

  15. Sol-gel synthesis and characterization of sub-microsized lanthanide (Ho, Tm, Yb, Lu) aluminium garnets

    NASA Astrophysics Data System (ADS)

    Dubnikova, N.; Garskaite, E.; Beganskiene, A.; Kareiva, A.

    2011-06-01

    Sub-microsized and nanosized holmium aluminium garnet (Ho 3Al 5O 12, HoAG), thulium aluminium garnet (Tm 3Al 5O 12, TmAG), ytterbium aluminium garnet (Yb 3Al 5O 12, YbAG) and lutetium aluminium garnet (Lu 3Al 5O 12, LuAG) powders were prepared by a simple aqueous sol-gel method using aluminium nitrate nonahydrate, lutetium oxide, thulium oxide, holmium oxide and ytterbium oxide as starting materials. Ethane-1,2-diol was used as complexing agent. The powder X-ray diffraction (XRD) patterns of the specimens sintered at 1000 °C revealed the formation of monophasic HoAG, TmAG, YbAG, and LuAG. The phase composition of the samples was also characterized by infrared (IR) spectroscopy. Microstructural features of the polycrystalline garnets were studied by scanning electron microscopy (SEM).

  16. Trapping processes in CaS:Eu{sup 2+},Tm{sup 3+}

    SciTech Connect

    Jia, Dongdong; Jia, Weiyi; Evans, D. R.; Dennis, W. M.; Liu, Huimin; Zhu, Jing; Yen, W. M.

    2000-09-15

    CaS:Eu{sup 2+},Tm{sup 3+} is a persistent red phosphor. Thermoluminescence was measured under different excitation and thermal treatment conditions. The results reveal that the charge defects, created by substituting Tm{sup 3+} for Ca{sup 2+}, serve as hole traps for the afterglow at room temperature. Tm{sup 3+} plays the role of deep electron trapping centers, capturing electrons either through the conduction band or directly from the excited Eu{sup 2+} ions. These two processes, in which two different sites of Tm{sup 3+} are involved, correspond to two traps with different depths. (c) 2000 American Institute of Physics.

  17. Solvent extraction behaviour of calixarene-type cyclophanes towards trivalent La, Nd, Eu, Er and Yb

    SciTech Connect

    Ludwig, R.; Inoue, Katsutoshi; Yamato, Takehiko )

    1993-04-01

    In this paper we describe the solvent extraction behaviour of three calixarene-type cyclophanes towards trivalent lanthanides Ln[sup 3+] (Ln = La, Nd, Eu, Er and Yb). By using p-tert-butylcalix/6/arene hexacarboxylic acid (L1), the lanthanides were extracted from the aqueous phase at pH 2 to 3.5 into chloroform according to a cation exchange mechanism as 1:2 metal:ligand complexes. The extractability is: Nd, Eu > La > Er > Yb. In the presence of excess Na[sup +] in the aqueous phase, this order was not changed but the lanthanides were extracted as 1:1 complexes at low extractant concentration and their extractability decreased. The use of p-tert-butylcalix/4/arene tetracarboxylic acid (L2) with a smaller cavity size dissolved in chloroform or toluene results in lower distribution coefficients, D[sub Ln], compared with L1. The extraction constants of the 1:2 metal:extractant complexes for the water-toluene system follow the order Eu > Nd > Yb > Er > La. Upon addition of excess Na[sup +], both extractability and selectivity increased. The extraction behaviour of a third cyclophane (L3) with a cavity size similar to that of L1 containing four carboxylic acid groups was different from that of L1 with respect to extractability and order of extraction of the lanthanides. 21 refs., 12 figs.

  18. Thermoelectric properties of Yb{sub x}Eu{sub 1-x}Cd{sub 2}Sb{sub 2}

    SciTech Connect

    Zhang, H.; Fang, L.; Tang, M.-B.; Man, Z. Y.; Chen, H. H.; Yang, X. X.; Zhao, J.-T.; Baitinger, M.; Grin, Y.

    2010-11-21

    The thermoelectric performance of EuCd{sub 2}Sb{sub 2} and YbCd{sub 2}Sb{sub 2} was improved by mixed cation occupation. The composition, structure, and thermoelectric properties of Yb{sub x}Eu{sub 1-x}Cd{sub 2}Sb{sub 2} (x=0, 0.5, 0.75, and 1) have been investigated. Polycrystalline samples are prepared by direct reaction of the elements. Thermoelectric properties were investigated after densification of the materials by spark plasma sintering. Yb{sub x}Eu{sub 1-x}Cd{sub 2}Sb{sub 2} crystallizes in the P3m1 space group. The lattice parameters increase with the europium content. These materials show low electrical resistivity, high Seebeck coefficient, and low thermal conductivity together with high carrier concentration and high carrier mobility. ZT values of 0.88 and 0.97 are obtained for Yb{sub 0.5}Eu{sub 0.5}Cd{sub 2}Sb{sub 2} and Yb{sub 0.75}Eu{sub 0.25}Cd{sub 2}Sb{sub 2} at 650 K, respectively.

  19. Properties of single crystalline AZn2Sb2 (A=Ca,Eu,Yb)

    SciTech Connect

    May, Andrew F; McGuire, Michael A; Ma, Jie; Delaire, Olivier A; Huq, Ashfia; Custelcean, Radu

    2012-01-01

    Single crystals of CaZn{sub 2}Sb{sub 2}, EuZn{sub 2}Sb{sub 2}, and YbZn{sub 2}Sb{sub 2} were grown from melts of nominal composition AZn{sub 5}Sb{sub 5} (A = Ca,Eu,Yb) with the excess melt being removed at 1073 K. The electrical transport properties are consistent with those previously reported for polycrystalline samples. This confirms that the p-type carrier concentrations ranging from 2 x 10{sup 19} cm{sup -3} to -1 x 10{sup 20} cm{sup -3} are intrinsic to these materials. Also consistent with transport in polycrystalline materials, the carrier mobility is found to be lowest in CaZn{sub 2}Sb{sub 2}, suggesting the trends in mobility and thermoelectric efficiency within these compounds are inherent to the material systems and not due to inhomogeneity or impurities in polycrystalline samples. These results suggest CaZn{sub 2}Sb{sub 2} has the strongest coupling between the doping/defects and the electronic framework. Magnetization measurements reveal an antiferromagnetic transition near 13 K in EuZn{sub 2}Sb{sub 2}, and the observed magnetic anisotropy indicates the spins align parallel and anti-parallel to c in the trigonal lattice. Powder neutron diffraction on polycrystalline samples of CaZn{sub 2}Sb{sub 2} and YbZn{sub 2}Sb{sub 2} reveals smooth lattice expansion to 1000 K, with c expanding faster than a. The Debye temperatures calculated from specific heat capacity data and the isotropic displacement parameters are found to correlate with the carrier mobility, with the CaZn{sub 2}Sb{sub 2} displaying the largest Debye temperature and smallest mobility.

  20. Energy transfer and visible-infrared quantum cutting photoluminescence modification in Tm-Yb codoped YPO4 inverse opal photonic crystals.

    PubMed

    Wang, Siqin; Qiu, Jianbei; Wang, Qi; Zhou, Dacheng; Yang, Zhengwen

    2015-08-01

    YPO4:??Tm, Yb inverse opal photonic crystals were successfully synthesized by the colloidal crystal templates method, and the visible-infrared quantum cutting (QC) photoluminescence properties of YPO4:??Tm, Yb inverse opal photonic crystals were investigated. We obtained tetragonal phase YPO4 in all the samples when the samples sintered at 950°C for 5 h. The visible emission intensity of Tm3+ decreased significantly when the photonic bandgap was located at 650 nm under 480 nm excitation. On the contrary, the QC emission intensity of Yb3+ was enhanced as compared with the no photonic bandgap sample. When the photonic bandgap was located at 480 nm, the Yb3+ and Tm3+ light-emitting intensity weakened at the same time. We demonstrated that the energy transfer between Tm3+ and Yb3+ is enhanced by the suppression of the red emission of Tm3+. Additionally, the mechanisms for the influence of the photonic bandgap on the energy transfer process of the Tm3+, Yb3+ codoped YPO4 inverse opal are discussed. PMID:26368098

  1. Thermal decomposition assisted synthesis and upconversion property of Fe3O4@YPO4:Tm/Yb hybrid nano-composite phosphor

    NASA Astrophysics Data System (ADS)

    Tiwari, S. P.; Kumar, K.; Rai, V. K.

    2015-06-01

    Hybrid nano-composite phosphor has been successfully synthesized through thermal decomposition method. The dual phase of samples assigned by XRD analysis shows the formation of nano-composite with crystallite size 20 nm and 12 nm for YPO4: Tm/Yb and Fe3O4@YPO4:Tm/Yb respectively. The FESEM images show the spherical shape and non agglomerated formation of nanoparticles. Three bands in upconversion emission mode were found in intense blue at 472 nm, red at 662 nm and NIR at 798 nm regions corresponding to1G4 ? 3H6, 1G4 ? 3F4 and 3H4 ? 3H6 transition states respectively. The lifetime for1G4 ? 3H6 level is found 1150 microsecond and 1400 microsecond for YPO4: Tm/Yb and Fe3O4@YPO4:Tm/Yb samples respectively.

  2. Red Eu,Yb:KY(WO4)2 laser at ~702?nm

    NASA Astrophysics Data System (ADS)

    Dashkevich, V. I.; Bagayev, S. N.; Orlovich, V. A.; Bui, A. A.; Loiko, P. A.; Yumashev, K. V.; Yasukevich, A. S.; Kuleshov, N. V.; Vatnik, S. M.; Pavlyuk, A. A.

    2015-08-01

    In this letter, laser operation is demonstrated with a Eu,Yb: KY(WO4)2 crystal on the 5D0?????7F4 transition of the Eu3+ ion. When pumping into the 7F1?????5D1 absorption band by a diode-pumped Nd3+:KGd(WO4)2/KTP laser power-scaled at 533.6?nm up to a watt-level, we achieved 2.5?mW of the continuous wave (CW) red output at ~702.1?nm. At quasi-CW pumping with a duty cycle of 10%, the peak power of the ms-long pulses arrived at ~19?mW, corresponding to a green-to-red conversion efficiency of 0.8%.

  3. Mechanochemical preparation of nanocrystalline NaYF4:Gd3+/Yb3+/Tm3+: An efficient upconversion phosphor

    NASA Astrophysics Data System (ADS)

    Zhang, Jun; Riesen, Hans

    2015-11-01

    We report on a mechanochemical preparation route for NaYF4:Gd3+/Yb3+/Tm3+ nanoparticles by ball-milling NaF, YF3, GdF3, YbF3 and TmF3 at room temperature. An analysis by XRD and TEM demonstrates that the resulting materials are mainly (?88% after 4 h ball-milling) in the hexagonal phase and are on the nanoscale with an average crystallite size of ?20 nm. The prepared nanoparticles display efficient upconversion emission; upon excitation by a 980 nm laser diode, bright visible blue light emission can be observed. However, in accord with previous results, the strongest emission is observed in the NIR at 800 nm.

  4. Quenching of the upconversion luminescence of NaYF4:Yb3+,Er3+ and NaYF4:Yb3+,Tm3+ nanophosphors by water: the role of the sensitizer Yb3+ in non-radiative relaxation

    NASA Astrophysics Data System (ADS)

    Arppe, Riikka; Hyppänen, Iko; Perälä, Niina; Peltomaa, Riikka; Kaiser, Martin; Würth, Christian; Christ, Simon; Resch-Genger, Ute; Schäferling, Michael; Soukka, Tero

    2015-07-01

    We have studied the mechanisms of water-based quenching of the upconversion photoluminescence of upconverting nanophosphors (UCNPs) via luminescence decay measurements for a better understanding of the non-radiative deactivation pathways responsible for the relatively low upconversion luminescence efficiency in aqueous solutions. This included both upconversion luminescence measurements and the direct excitation of emissive energy states of Er3+ and Yb3+ dopants in NaYF4:Yb3+,Er3+ UCNPs by measuring the decays at 550 and 655 nm upon 380 nm excitation and at 980 nm upon 930 nm excitation, respectively. The luminescence intensities and decays were measured from both bare and silanized NaYF4:Yb3+,Er3+ and NaYF4:Yb3+,Tm3+ UCNPs in H2O and D2O. The measurements revealed up to 99.9% quenching of the upconversion photoluminescence intensity of both Er3+ and Tm3+ doped bare nanophosphors by water. Instead of the multiphonon relaxation of excited energy levels of the activators, the main mechanism of quenching was found to be the multiphonon deactivation of the Yb3+ sensitizer ion caused by OH-vibrations on the surface of the nanophosphor. Due to the nonlinear nature of upconversion, the quenching of Yb3+ has a higher order effect on the upconversion emission intensity with the efficient Yb-Yb energy migration in the ~35 nm nanocrystals making the whole nanophosphor volume susceptible to surface quenching effects. The study underlines the need of efficient surface passivation for the use of UCNPs as labels in bioanalytical applications performed in aqueous solutions.We have studied the mechanisms of water-based quenching of the upconversion photoluminescence of upconverting nanophosphors (UCNPs) via luminescence decay measurements for a better understanding of the non-radiative deactivation pathways responsible for the relatively low upconversion luminescence efficiency in aqueous solutions. This included both upconversion luminescence measurements and the direct excitation of emissive energy states of Er3+ and Yb3+ dopants in NaYF4:Yb3+,Er3+ UCNPs by measuring the decays at 550 and 655 nm upon 380 nm excitation and at 980 nm upon 930 nm excitation, respectively. The luminescence intensities and decays were measured from both bare and silanized NaYF4:Yb3+,Er3+ and NaYF4:Yb3+,Tm3+ UCNPs in H2O and D2O. The measurements revealed up to 99.9% quenching of the upconversion photoluminescence intensity of both Er3+ and Tm3+ doped bare nanophosphors by water. Instead of the multiphonon relaxation of excited energy levels of the activators, the main mechanism of quenching was found to be the multiphonon deactivation of the Yb3+ sensitizer ion caused by OH-vibrations on the surface of the nanophosphor. Due to the nonlinear nature of upconversion, the quenching of Yb3+ has a higher order effect on the upconversion emission intensity with the efficient Yb-Yb energy migration in the ~35 nm nanocrystals making the whole nanophosphor volume susceptible to surface quenching effects. The study underlines the need of efficient surface passivation for the use of UCNPs as labels in bioanalytical applications performed in aqueous solutions. Electronic supplementary information (ESI) available: Transmission electron micrographs of the bare and silanized UCNPs, X-ray powder diffraction spectra of the NaYF4:Yb3+,Er3+ and NaYF4:Yb3+,Tm3+ nanophosphors, FT-IR spectra of oleic acid capped and bare UCNPs, the repetitiveness study of luminescence lifetime measurement, decay curves and table of lifetimes of upconversion emission of bare NaYF4:Yb3+,Er3+ in different proportions of water in H2O and time points at 550 nm, and upconversion luminescence spectra of bare NaYF4:Yb3+,Er3+ in both D2O and H2O at different excitation power densities. See DOI: 10.1039/c5nr02100f

  5. WHITE UPCONVERSION LUMINESCENCE FROM (Yb3+/Tm3+/Ho3+) TRIDOPED GdF3 NANORODS AFTER HEAT TREATMENT

    NASA Astrophysics Data System (ADS)

    Guo, Linna; Wang, Yuhua; Zhang, Jia; Wang, Yanzhao; Dong, Pengyu

    2012-09-01

    A series of Ho3+/Yb3+/Tm3+ tridoped GdF3 nanorods with different dopant concentrations were synthesized by a hydrothermal method. Transmission electron microscope (TEM) images indicate that the length and diameter of the nanorods is about 90 nm and 31 nm, respectively on average. No bright white upconversion light was observed from the samples with different Yb3+, Ho3+ or Tm3+ concentrations. Unexpectedly, the emission color coordinates of the samples after heat treatment move toward the central white region of the chromaticity diagram, and among these samples, the color coordinate (0.349, 0.329) of GdF3:15% Yb3+, 0.1% Ho3+, 0.8% Tm3+ is the most close to the standard white light (0.333, 0.333). This is unlike previous reports in which white light was achieved via tuning dopant concentration or excitation power. The reasons for the above phenomenon are presented by means of FT-IR spectra and the energy level diagram of dopants.

  6. White light upconversion emissions in Er3+/Tm3+/Yb3+ tridoped oxyfluoride glass

    NASA Astrophysics Data System (ADS)

    Guan, Xiaoping; Xu, Wei; Zhu, Shuang; Song, Qiutong; Wu, Xijun; Liu, Hailong

    2015-10-01

    Rare earth ions doped glasses producing visible upconversion emissions are of great interest due to their potential applications in the photonics filed. In fact, practical application of upconversion emissions has been used to obtain color image displays and white light sources. However, there are few reports on the thermal effect on tuning the emission color of the RE doped materials. In this work, the Er3+/Tm3+/Yb3+ tridoped oxyfluoride glasses were prepared through high temperature solid-state method. Under a 980 nm diode laser excitation, the upconversion emissions from the samples were studied. At room-temperature, bright white luminescence, whose CIE chromaticity coordinate was about (0.28, 0.31), can be obtained when the excitation power was 120 mW. The emission color was changed by varying the intensity ratios between RGB bands, which are strongly dependent on the rare earth ions concentration. The temperature dependent color emissions were also investigated. As temperature increased, the intensities for the emission bands presented different decay rates, finally resulting in the changing of the CIE coordinate. When the temperature was 573 K, white light with color coordinate of (0.31, 0.33) was achieved, which matches well with the white reference (0.33, 0.33). The color tunability, high quality of white light and intense emission intensity make the transparent oxyfluoride glasses excellent candidates for applications in solid-state lighting.

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

    PubMed

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

    2013-10-01

    Eu(2+)-Yb(3+) 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 Eu(2+) indicated the partition of Eu(2+) into FAP nanocrystals in glass ceramic. NIR emission due to the transition (2)F5/2?(2)F7/2 of Yb(3+) ions (about 980-1100 nm) was observed from glasses under ultraviolet excitation, ascribed to downconversion from Eu(2+) to Yb(3+), which can be enhanced by precipitating nano-FAP crystals. The results indicated that Eu(2+)-Yb(3+) co-doped glass-ceramic embedding with nano-FAP is a promising candidate as downconversion materials for enhancing conversion efficiency of solar cells. PMID:23816484

  8. Effect of Ag nanoparticles on the radiative properties of tellurite glasses doped with Er3+, Yb3+ and Tm3+ ions

    NASA Astrophysics Data System (ADS)

    Silva, G. H.; Holgado, D. P. A.; Anjos, V.; Bell, M. J. V.; Kassab, L. R. P.; Amâncio, C. T.; Moncorgè, Richard

    2014-11-01

    The present work is devoted to the characterization of the thermal and spectroscopic properties of tellurite glasses, codoped with Er3+, Yb3+ and Tm3+ rare-earth ions and silver nanoparticles (NPs). The techniques used for this investigation were UV-visible and infrared absorption, time-resolved luminescence and thermal lens. Time-resolved luminescence studies indicate efficient Yb3+ ? Er3+ and Yb3+ ? Tm3+ energy transfers and intense Er3+ and Tm3+ mid-infrared emissions around 1550 nm and 1860 nm, respectively. The presence NPs is found to increase the thermal diffusivity of the materials and to shorten the mid-infrared emission lifetime of both the Er3+ and Tm3+ ions.

  9. 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.

  10. Yb{sub 14?x}Tm{sub x}MnSb{sub 11} (0

    SciTech Connect

    Roudebush, John H.; Grebenkemper, Jason; Hu, Yufei; Kazem, Nasrin; Abdusalyamova, M.N.

    2014-03-15

    The compounds, Yb{sub 14?x}Tm{sub x}MnSb{sub 11} (0Tm was determined from wavelength dispersive microprobe analysis to be x=0.45 (1). Single crystal data are consistent with the Ca{sub 14}AlSb{sub 11} structure type and one formula unit can be described as consisting of 14 Yb{sup 2+} cations, MnSb{sub 4} tetrahedron, Sb{sub 3} linear anion and 4 Sb{sub 3}{sup -} anions. The site occupancy of the Tm atom was not determined because of the small amount and small difference in scattering between Tm and Yb. The difference in bond lengths or angles between the solid solution and pristine Yb{sub 14}MnSb{sub 11} is less than 1%. The magnetic susceptibility of samples prepared by Sn flux with the nominal composition of Yb{sub 14?x}Tm{sub x}MnSb{sub 11} (x=0.1, 0.2, 0.3, and 0.4), show that these phases are ferromagnetic at low temperature with the T{sub C} decreasing from 56 to 39 K with increasing x. Magnetic saturation for the x=0.4 composition at 5 K is consistent with Tm being present as Tm{sup 3+} and a negative magnetoresistance ratio (MR=[(?(H)??(0))/?(H)]×100%) of 18% at 3 T is observed. -- Graphical abstract: Magnetic susceptibility (?) for Yb{sub 14?x}Tm{sub x}MnSb{sub 11} at H{sub a}=0.01 T as a function of temperature along with a view of the structure. Highlights: • New rare earth containing transition metal Zintl phase. • Control of magnetic properties through aliovalent substitution. • Magnetic ordering due to both d and f electrons. • Large magnetoresistance at low temperatures.

  11. Upconversion luminescent property and EPR study of NaGdF4:Yb3+/Tm3+ synthesized by the hydrothermal method

    NASA Astrophysics Data System (ADS)

    Liu, Jing; Zhang, Jing-Ying; Liu, Kai; Gao, Hong-Jian; Yu, Xiao-Long; Cao, Yang; Liu, Zhong-Xin

    2015-09-01

    Water soluble upconversion (UC) luminescence hexagonal-phase NaGdF4: Yb3+/Tm3+ nanoparticles have been successfully synthesized by the hydrothermal method. XRD, SEM, UC photoluminescence spectra and electron paramagnetic resonance (EPR) spectrum were used to characterize the nanoparticles. The intensity of UC emission region could be controlled through different sodium source and the fluorine source, 6PJ?8S7/2 emission of Gd3+ is also observed at 310 nm. A broad spectrum with a dominant resonance at g of about 2 was observed by the EPR spectrum of the NaGdF4:Yb3+/Tm3+ nanoparticles. The transparent NaGdF4:Yb3+/Tm3+ solution presented naked eye-visible violet-blue light under the 980 nm LD excitation. The current work paves the way for their potential application in infrared tomography and magnetic resonance imaging (MRI).

  12. Synthesis of monodisperse hexagonal NaYF4:Yb, Ln (Ln = Er, Ho and Tm) upconversion nanocrystals in TOPO

    NASA Astrophysics Data System (ADS)

    Shan, Jingning; Qin, Xiao; Yao, Nan; Ju, Yiguang

    2007-11-01

    NaYF4 doped with Yb, Ln (Ln = Er, Ho and Tm) upconversion nanocrystals (UP-NCs) were synthesized in trioctylphosphine oxide (TOPO) solvent via a thermolysis method. It was found that the energy barrier of the phase transition from cubic (?) to hexagonal (?) was significantly reduced in TOPO, and the ?-phase NCs were obtained in a broad temperature window from 330 to 370 °C. The as-synthesized NCs had controllable sizes in the range 5-20 nm with narrow size distribution, and presented highly efficient UP fluorescence.

  13. Upconversion white-light emission in Ho3+/Yb3+/Tm3+ tridoped LiNbO3 single crystal.

    PubMed

    Xing, Lili; Wu, Xiaohong; Wang, Rui; Xu, Wei; Qian, Yannan

    2012-09-01

    Ho3+/Yb3+/Tm3+ tridoped LiNbO3 single crystal exhibiting intense upconversion white light under 980 nm excitation has been successfully fabricated by the Czochralski method. The tridoped LiNbO3 single crystal offers power dependent color tuning properties by simply changing excitation power. Efficient three-photon blue upconversion emission and two-photon green and red upconversion emissions have been observed. In addition, the red emission of Ho3+ originates dominantly from the nonradiative decay of green emission. The LiNbO3 with upconversion white light will be a potential laser candidate material. PMID:22940941

  14. Tunable multicolor and white-light upconversion luminescence in Yb3+/Tm3+/Ho3+ tri-doped NaYF4 micro-crystals.

    PubMed

    Lin, Hao; Xu, Dekang; Teng, Dongdong; Yang, Shenghong; Zhang, Yueli

    2015-09-01

    NaYF4 micro-crystals with various concentrations of Yb(3+) /Tm(3+) /Ho(3+) were prepared successfully via a simple and reproducible hydrothermal route using EDTA as the chelating agent. Their phase structure and surface morphology were studied using powder X-ray diffraction (XRD) and scanning electron microscopy (SEM). The XRD patterns revealed that all the samples were pure hexagonal phase NaYF4. SEM images showed that Yb(3+)/Tm(3+)/Ho(3+) tri-doped NaYF4 were hexagonal micro-prisms. Upconversion photoluminescence spectra of Yb(3+)/Tm(3+)/Ho(3+) tri-doped NaYF4 micro-crystals with various dopant concentrations under 980 nm excitation with a 665?mW pump power were studied. Tunable multicolor (purple, purplish blue, yellowish green, green) and white light were achieved by simply adjusting the Ho(3+) concentration in 20%Yb(3+)/1%Tm(3+)/xHo(3+) tri-doped NaYF4 micro-crystals. Furthermore, white-light emissions could be obtained using different pump powers in 20%Yb(3+)/1%Tm(3+)/1%Ho(3+) tri-doped NaYF4 micro-crystals at 980 nm excitation. The pump power-dependent intensity relationship was studied and relevant energy transfer processes were discussed in detail. The results suggest that Yb(3+)/Tm(3+) Ho(3+) tri-doped NaYF4 micro-crystals have potential applications in optoelectronic devices such as photovoltaic, plasma display panel and white-light-emitting diodes. PMID:25377774

  15. Pure and almost pure NIR emission of Tm and Tm,Yb-CeO2 under UV, X-ray and NIR up-conversion excitation: key roles of level selective antenna sensitization and charge-compensation.

    PubMed

    Avram, Daniel; Cojocaru, Bogdan; Urda, Adriana; Tiseanu, Ion; Florea, Mihaela; Tiseanu, Carmen

    2015-11-18

    Herein, we report on the pure and almost pure near-infrared (NIR) emission at around 807 nm observed for Tm(Yb) (co)-doped CeO2 nanoparticles (NPs) under UV, X-ray and NIR up-conversion excitation. The optical responses are attributed to the low-lying charge-transfer of CeO2 that acts as a selective antenna sensitizer of the Tm (3)H4 emission and Yb doping that lowers the local symmetry at Tm sites and introduces additional phonon modes. Selective antenna sensitization is also observed for Er/Ho (Yb) (co)-doped CeO2 NPs. To the best of our knowledge, this is a first study which correlates the down- and up-conversion emission properties of lanthanide(s)-(co) dopants with the CeO2 structure highlighting also the outstanding potential of these NPs in high-penetration tissue imaging and therapy. PMID:26411533

  16. Simultaneous size and luminescence control of NaYF4:Yb3+/RE3+ (RE = Tm, Ho) microcrystals via Li+ doping

    NASA Astrophysics Data System (ADS)

    Lin, Hao; Xu, Dekang; Teng, Dongdong; Yang, Shenghong; Zhang, Yueli

    2015-07-01

    Enhancement of upconversion (UC) luminescence is imperative for the applications of UC microcrystals (MCs). In this work, NaYF4:Yb3+/RE3+ (RE = Tm, Ho) MCs via Li+ doping were successfully prepared by a simple hydrothermal process with the assistance of citric acid. The UC luminescence intensities of NaYF4:Yb3+/RE3+ (RE = Tm, Ho) are significantly enhanced via Li+ doping at different concentrations. Compared to Li+-absent sample, UC luminescence intensities of blue emission (477 nm) and red emission (649 nm) in NaYF4:Yb3+/Tm3+ MCs via 15 mol% Li+ doping are improved by 10 and 9 times, respectively; UC luminescence intensities of green emission (538 nm) and red emission (644 nm) in NaYF4:Yb3+/Ho3+ MCs via 15 mol% Li+ doping are improved by 12 and 3 times, respectively. The mechanism of the enhancement via Li+ doping is discussed in details, which may be attributed to the fact that Li+ doping can cause the distortion of the local symmetry around RE ions. Our results indicate that the enhanced UC luminescence of NaYF4:Yb3+/RE3+ (RE = Tm, Ho) MCs via Li+ doping may have potential applications in optoelectronic devices such as solar cells and plasma display panel.

  17. Infrared-to-ultraviolet up-conversion luminescence from AlF 3: 0.2%Tm 3+, 10%Yb 3+ particles prepared by pulsed laser ablation

    NASA Astrophysics Data System (ADS)

    Qin, Guanshi; Qin, Weiping; Wu, Changfeng; Huang, Shihua; Zhao, Dan; Zhang, Jisen; Lu, Shaozhe

    2003-02-01

    AlF 3: 0.2%Tm 3+, 10%Yb 3+ particles were prepared by pulsed laser ablation (PLA). Under a 978 nm laser diode excitation, intense ultraviolet and weak blue up-conversion emissions were observed in the AlF 3: 0.2%Tm 3+, 10%Yb 3+ particles. Intensity dependence of the up-conversion emissions on the pump power was measured. The results show that the population of the states 1I 6, 1D 2 and 1G 4 may come from a five-photon, four-photon and three-photon energy transfer up-conversion process.

  18. Enhancement of near-infrared to near-infrared upconversion emission in the CeO?: Er³?, Tm³?, Yb³? inverse opals.

    PubMed

    Wu, Hangjun; Yang, Zhengwen; Liao, Jiayan; Lai, Shenfeng; Qiu, Jianbei; Song, Zhiguo; Yang, Yong; Zhou, Dacheng

    2014-02-15

    In this Letter, CeO?: Er³?, Tm³?, Yb³? inverse opal with near-infrared to near-infrared upconversion emission was prepared by polystyrene colloidal crystal templates, and the influence of photonic bandgap on the upconversion emission was investigated. Comparing with the reference sample, suppression of the blue or red upconversion luminescence was observed in the inverse opals. It is interesting that the near-infrared upconversion emission located at about 803 nm was enhanced due to the inhibition of visible upconversion emission in the inverse opals. Additionally, the variety of upconversion emission mechanisms was observed and discussed in the CeO?: Er³?, Tm³?, Yb³? inverse opals. PMID:24562241

  19. Uniform NaYF{sub 4}:Yb, Tm hexagonal submicroplates: Controlled synthesis and enhanced UV and blue upconversion luminescence

    SciTech Connect

    Huang, Wenjuan; Ding, Mingye; Huang, Hengming; Jiang, Chenfei; Song, Yan; Ni, Yaru; Lu, Chunhua; Xu, Zhongzi

    2013-02-15

    Graphical abstract: Display Omitted Highlights: ? ?-NaYF{sub 4} phosphors as an excellent upconversion materials. ? Oleic acid can promote the transformation of ? ? ? phase NaYF{sub 4}. ? The shape and size of ?-NaYF{sub 4} submicroplate can be tuned by reactant concentration. ? Enhanced UV and blue peaks can be obtained by varying Yb{sup 3+} and Tm{sup 3+} concentration. -- Abstract: We reported the preparation of cubic (?-) and hexagonal (?-) NaYF{sub 4} particles in high boiling organic solvents 1-octadecene (ODE) and oleic acid (OA), through a thermal decomposition synthesis route. The as-prepared products were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), photoluminescence (PL) spectra. By tuning the OA/ODE volume ratio and reactant concentration, we could manipulate the morphology, size, and crystal structure of the products. Highly uniform ?-NaYF{sub 4} submicroplates were obtained from ?-NaYF{sub 4} nanoparticles by increasing the OA/ODE volume ratio, while the phase kept unchanged with the increasing of reactant concentration. Upconversion emissions from UV to NIR emissions were observed in ?-NaYF{sub 4} hexagonal submicroplates under 980 nm laser diode excitation. In addition, the enhanced UV and blue upconversion emissions were obtained by varying Tm{sup 3+} and Yb{sup 3+} ion concentration.

  20. Determination of the refractive index of ?-NaYF4/Yb3+/Er3+/Tm3+ nanocrystals using spectroscopic refractometry

    NASA Astrophysics Data System (ADS)

    Sokolov, V. I.; Zvyagin, A. V.; Igumnov, S. M.; Molchanova, S. I.; Nazarov, M. M.; Nechaev, A. V.; Savelyev, A. G.; Tyutyunov, A. A.; Khaydukov, E. V.; Panchenko, V. Ya.

    2015-04-01

    A method for measuring refractive index n of nanosize particles in the visible and near-IR spectral ranges is proposed. The method is based on comparing refractive index n colloid of a colloid solution of nanoparticles in several solvents with refractive indices n solvent of corresponding pure solvents and has an accuracy of ±2 × 10-4. Upconversion nanosize phosphors (UCNPs) are synthesized in the form of a ?-NaYF4 crystalline matrix doped with Yb3+, Er3+, and Tm3+ rare earth ions. UCNPs have a doped core with a diameter of 40 ± 5 nm and undoped shell with a thickness of 3-5 nm. Synthesized nanocrystals possess intense photoluminescence in the blue, green, and red spectral ranges upon excitation by IR radiation with a wavelength of 977 nm. Using a spectroscopic refractometer, the dispersion of the refractive index of ?-NaYF4/Yb3+/Er3+/Tm3+ nanocrystals was measured for the first time in the spectral range of 450-1000 nm with an accuracy of ±2 × 10-4.

  1. Hydrothermal synthesis of Yb3+, Tm3+ co-doped Gd6MoO12 and its upconversion properties

    NASA Astrophysics Data System (ADS)

    Di, Qiu-Mei; Sun, Yu-Mei; Xu, Qi-Guang; Han, Liu; Xue, Bing; Sun, Jia-Yue

    2015-06-01

    Yb3+, Tm3+ co-doped Gd6MoO12 phosphors with different morphologies are prepared by the hydrothermal method. The dendrites present different morphologies (including hexagonal prisms, spindles, and spheres) after changing the pH value and edetate disodium (EDTA) usage. It is found that each of the two factors plays a crucial role in forming different morphologies. The up-conversion (UC) luminescence is studied. Under 980-nm semiconductor laser excitation, relatively strong blue emission and weak red emission are observed. Finally, the effect of pumping power on the UC luminescence properties and the level diagram mechanism of Gd6MoO12:Yb3+/Tm3+ phosphor are also discussed. Project supported by the National Natural Science Foundation of China (Grant No. 20976002), the Beijing Natural Science Foundation, China (Grant No. 2122012), the Key Projects for Science and Technology of Beijing Education Commission, China (Grant No. KZ201310011013), and the Education and Research Fund of Guangdong Province, China (Grant No. 2011B090400100).

  2. Hall and transverse even effects in the vicinity of a quantum critical point in Tm{sub 1-x}Yb{sub x}B{sub 12}

    SciTech Connect

    Sluchanko, N. E. Azarevich, A. N.; Bogach, A. V.; Glushkov, V. V.; Demishev, S. V.; Anisimov, M. A.; Levchenko, A. V.; Filipov, V. B.; Shitsevalova, N. Yu.

    2012-09-15

    The angular, temperature, and magnetic field dependences of the resistance recorded in the Hall effect geometry are studied for the rare-earth dodecaboride Tm{sub 1-x}Yb{sub x}B{sub 12} solid solutions where the metal-insulator and antiferromagnetic-paramagnetic phase transitions are observed in the vicinity of the quantum critical point x{sub c} Almost-Equal-To 0.3. The measurements performed on high-quality single crystals in the temperature range 1.9-300 K for the first time have revealed the appearance of the second harmonic contribution, a transverse even effect in these fcc compounds near the quantum critical point. This contribution a is found to increase drastically both under the Tm-to-ytterbium substitution in the range x > x{sub c} and with an increase in the external magnetic field. Moreover, as the Yb concentration x increases, a negative peak of a significant amplitude appears on the temperature dependences of the Hall coefficient R{sub H}(T) for the Tm{sup 1-x}Yb{sub x}B{sub 12} compounds, in contrast to the invariable behavior R{sub H}(T) Almost-Equal-To const found for TmB{sub 12}. The complicated activation-type behavior of the Hall coefficient is observed at intermediate temperatures for x {>=} 0.5 with activation energies E{sub g}/k{sub B} Almost-Equal-To 200 K and E{sub a}/k{sub B} 55-75 K, and the sign inversion of R{sub H}(T) is detected at liquid-helium temperatures in the coherent regime. Renormalization effects in the electron density of states induced by variation of the Yb concentration are analyzed. The anomalies of the charge transport in Tm{sub 1-x}Yb{sub x}B{sub 12} solid solutions in various regimes (charge gap formation, intra-gap many-body resonance, and coherent regime) are discussed in detail and the results are interpreted in terms of the electron phase separation effects in combination with the formation of nanosize clusters of rare earth ions in the cage-glass state of the studied dodecaborides. The data obtained allow concluding that the emergence of Yb-Yb dimers in the Tm{sub 1-x}Yb{sub x}B{sub 12} cage-glass matrix is the origin of the metal-insulator transition observed in the achetypal strongly correlated electron system of YbB{sub 12}.

  3. Lasing in a Tm : Yb{sub 3}Al{sub 5}O{sub 12} crystal pumped at 1.678 ?m

    SciTech Connect

    Zavartsev, Yu D; Zagumennyi, A I; Kalachev, Yu L; Kutovoi, S A; Mikhailov, V A; Shcherbakov, I A

    2014-10-31

    The Yb{sub 3}Al{sub 5}O{sub 12} (YbAG) crystal is proposed as a matrix of Tm{sup 3+}-doped laser elements for two-micron lasers. A Tm : YbAG crystal of high optical quality is grown by the Czochralski method and its spectral and luminescent characteristics are studied. The luminescence decay time for the upper laser level {sup 3}F{sub 4} is measured to be 4.7 ms. Lasing in this crystal pumped by a 1.678-?m fibre laser is obtained at a wavelength of 2.02 ?m for the first time. The total and slope efficiencies of the laser at room temperature and an output power up to 330 mW reach 33% and 41%, respectively. (lasers)

  4. Frequency upconversion luminescence from Yb{sup +3}-Tm{sup +3} codoped PbO-GeO{sub 2} glasses containing silver nanoparticles

    SciTech Connect

    Assumpcao, Thiago A. A.; Silva, Davinson M. da; Kassab, Luciana R. P.

    2009-09-15

    Infrared-to-visible and infrared-to-infrared frequency upconversion processes in Yb{sup 3+}-Tm{sup 3+} doped PbO-GeO{sub 2} glasses containing silver nanoparticles (NPs) were investigated. The experiments were performed by exciting the samples with a diode laser operating at 980 nm (in resonance with the Yb{sup 3+} transition {sup 2}F{sub 7/2}->{sup 2}F{sub 5/2}) and observing the photoluminescence (PL) in the visible and infrared regions due to energy transfer from Yb{sup 3+} to Tm{sup 3+} ions followed by excited state absorption in the Tm{sup 3+} ions. The intensified local field in the vicinity of the metallic NPs contributes for enhancement in the PL intensity at 480 nm (Tm{sup 3+}:{sup 1}G{sub 4}->{sup 3}H{sub 6}) and at 800 nm (Tm{sup 3+}:{sup 3}H{sub 4}->{sup 3}H{sub 6}).

  5. Activation of SO2 with [(?(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 [(?(5) -C5 Me5 )2 Yb(THF)2 ] with SO2 at low temperature gave two new compounds, namely, the Yb(III) dithionite/sulfinate complex [{(?(5) -C5 Me5 )2 Yb(?3 ,1?(2) O(1,3) ,2?(3) O(2,2',4) -S2 O4 )}2 {(?(5) -C5 Me5 )Yb(?,1?O,2?O'-C5 Me5 SO2 )}2 ] (1) and the Yb(III) dithionite complex [{(?(5) -C5 Me5 )2 Yb}2 (?,1?(2) O(1,3) ,2?(2) O(2,4) -S2 O4 )] (2). After extraction of 1, the mixture was heated to give the dinuclear tetrasulfinate complex [{(?(5) -C5 Me5 )Yb}2 (?,?O,?O'-C5 Me5 SO2 )4 ] (3?a). In contrast, from the reaction of [(?(5) -C5 Me5 )2 Eu(THF)2 ] with SO2 only the tetrasulfinate complex [{(?(5) -C5 Me5 )Eu}2 (?,?O,?O'-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. PMID:25196130

  6. Synthesis, structure, magnetism, and optical properties of theordered mixed-lanthanide sulfides gamma-LnLn'S3 (Ln=La, Ce; Ln'=Er, Tm,Yb)

    SciTech Connect

    Jin, G.B.; Choi, E.S.; Guertin, R.P.; Brooks, J.S.; Bray, T.H.; Booth, C.H.; Albrecht-Schmitt, T.E.

    2006-12-12

    {gamma}-LnLn{prime}S{sub 3} (Ln = La, Ce; Ln{prime} = Er, Tm, Yb) have been prepared as dark red to black single crystals by the reaction of the respective lanthanides with sulfur in a Sb{sub 2}S{sub 3} flux at 1000 C. This isotypic series of compounds adopts a layered structure that consists of the smaller lanthanides (Er, Tm, and Yb) bound by sulfide in six- and seven-coordinate environments that are connected together by the larger lanthanides (La and Ce) in eight- and nine-coordinate environments. The layers can be broken down into three distinct one-dimensional substructures containing three crystallographically unique Ln{prime} centers. The first of these is constructed from one-dimensional chains of edge-sharing [Ln{prime}S{sub 7}] monocapped trigonal prisms that are joined to equivalent chains via edge-sharing to yield ribbons. There are parallel chains of [Ln{prime}S{sub 6}] distorted octahedra that are linked to the first ribbons through corner-sharing. These latter units also share corners with a one-dimensional ribbon composed of parallel chains of [Ln{prime}S{sub 6}] polyhedra that edge-share both in the direction of chain propagation and with adjacent identical chains. Magnetic susceptibility measurements show Curie-Weiss behavior from 2 to 300 K with antiferromagnetic coupling, and no evidence for magnetic ordering. The {theta}{sub p} values range from -0.4 to -37.5 K, and spin-frustration may be indicated for the Yb-containing compounds. All compounds show magnetic moments substantially reduced from those calculated for the free ions. The optical band gaps for {gamma}-LaLn{prime}S{sub 3} (Ln{prime} = Er, Tm, Yb) are approximately 1.6 eV, whereas {gamma}-CeLn{prime}S{sub 3} (Ln{prime} = Er, Tm, Yb) are approximately 1.3 eV.

  7. Spectroscopic analysis of Eu{sup 3+} -and Eu{sup 3+}:Yb{sup 3+}-doped yttrium silicate crystalline powders prepared by combustion synthesis

    SciTech Connect

    Rakov, Nikifor; Amaral, Dayanne F.; Guimaraes, Renato B.; Maciel, Glauco S.

    2010-10-15

    Yttrium silicate powders doped with Eu{sup 3+} and codoped with Eu{sup 3+} and Yb{sup 3+} were prepared by combustion synthesis. The x-ray powder diffraction data showed the presence of Y{sub 2}SiO{sub 5} and Y{sub 2}Si{sub 2}O{sub 7} crystalline phases. Singly doped (1 wt %) sample illuminated with ultraviolet light ({lambda}=256 nm) showed the characteristic red luminescence corresponding to {sup 5}D{sub 0}{yields}{sup 7}F{sub J} transitions of Eu{sup 3+}. The Judd-Ofelt intensity parameters were calculated from experimental data and the radiative and nonradiative relaxation rates were estimated. The results showed that the nonradiative relaxation rate is smaller in yttrium silicate compared to yttrium oxide powder, a reference material, prepared under similar conditions. Codoped samples were exposed to near-infrared laser excitation ({lambda}=975 nm) and the red luminescence of Eu{sup 3+} was also observed. In this case, the luminescence is achieved due to a cooperative upconversion (CUC) process involving energy transfer (ET) from pairs of ytterbium ions to europium ions. The ET rate was estimated by fitting a rate equation model with the dynamics of CUC red emission.

  8. Spectroscopic properties and mechanism of Tm3+/Er3+/Yb3+co-doped oxyfluorogermanate glass ceramics containing BaF2 nanocrystals

    NASA Astrophysics Data System (ADS)

    Hu, Yue-Bo; Qiu, Jian-Bei; Zhou, Da-Cheng; Song, Zhi-Guo; Yang, Zheng-Wen; Wang, Rong-Fei; Jiao, Qing; Zhou, Da-Li

    2014-02-01

    Transparent Tm3+/Er3+/Yb3+ co-doped oxyfluorogermanate glass ceramics containing BaF2 nanocrystals are prepared. Under excitation of a 980-nm laser diode (LD), compared with the glass before heat treatment, the Tm3+/Er3+/Yb3+co-doped oxyfluorogermanate glass ceramics can emit intense blue, green and red up-conversion luminescence and Stark-split peaks; X-ray diffraction (XRD) and transmission electron microscope (TEM) results show that BaF2 nanocrystals with an average diameter of 20 nm are precipitated from the glass matrix. Stark splitting of the up-conversion luminescence peaks in the glass ceramics indicates that Tm3+, Er3+ and (or) Yb3+ ions are incorporated into the BaF2 nanocrystals. The up-conversion luminescence intensities of Tm3+, Er3+ and the splitting degree of luminescence peaks in the glass ceramics increase significantly with the increase of heat treat temperature and heat treat time extension. In addition, the possible energy transfer process between rare earth ions and the up-conversion luminescence mechanism are also proposed.

  9. Eu/sup 2 +/, Yb/sup 2 +/, and Es/sup 2 +/ coordination with sodium tetraphenylborate in water-ethanol solutions

    SciTech Connect

    Mikheev, N.B.; Kulyukhin, S.A.; Rumer, I.A.; Kamenskaya, A.N.

    1988-11-01

    Measurements have been made on the coordination of divalent lanthanoid s and actinoids with sodium tetraphenylborate (NaTPB) in water-ethanol solutions. Ln/sup 2 +/ and An/sup 2 +/ form cationic and neutral complexes. The coordination constants ..beta../sub 1/ and ..beta../sub 2/ have been determine: 6.5 and 25.7 for Yb/sup 2 +/, 1.7 and 52.7 for Eu/sup 2 +/, and 6.2 and 106.4 for Es/sup 2 +/. The trend indicates that the hydrated Es/sup 2 +/ is smaller than Yb/sup 2 +/ and Eu/sup 2 +/.

  10. Colour emission tunability in Ho3+-Tm3+-Yb3+ co-doped Y2O3 upconverted phosphor

    NASA Astrophysics Data System (ADS)

    Pandey, Anurag; Rai, Vineet Kumar

    2012-12-01

    The frequency upconversion (UC) emission throughout the visible region from the Y2O3:Ho3+-Tm3+-Yb3+ co-doped phosphors synthesized by using low temperature combustion process upon excitation with a diode laser operating at 980 nm have been presented. The colour emission tunability in co-doped phosphor has been observed on increasing the pump power and seen by the naked eyes. The tunability in colour emission has also been visualized by CIE chromaticity diagram. The variation in UC emission intensity of the 1G4 ? 3H6 (Tm3+) and 5F3 ? 5I8 (Ho3+) transitions lying in the blue region has been monitored with increase in the pump power and marked that their ratio can be used to determine the temperature. The developed phosphor has been used to record fingerprints. The observed most intense visible colour emission from the developed material may be used for photodynamic therapy and as an alternative of traditional fluorescent biolabels.

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

    PubMed Central

    Gavrilovi?, Tamara V.; Jovanovi?, Dragana J.; Lojpur, Vesna; Drami?anin, 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

  12. Effect of Li{sup +} ions on enhancement of near-infrared upconversion emission in Y{sub 2}O{sub 3}:Tm{sup 3+}/Yb{sup 3+} nanocrystals

    SciTech Connect

    Li Dongyu; Wang Yuxiao; Zhang Xueru; Dong Hongxing; Shi Guang; Liu Lu; Song Yinglin

    2012-11-01

    Near-infrared (NIR) to NIR upconversion emission is investigated in Tm{sup 3+}/Yb{sup 3+}/Li{sup +} triply doped Y{sub 2}O{sub 3} nanocrystals. Li{sup +} ions doped in Y{sub 2}O{sub 3}:Tm{sup 3+}/Yb{sup 3+} nanocrystals can greatly enhance the NIR upconversion emission intensity of Tm{sup 3+} ions. The abnormal shift of the (222) diffraction peak position determined from x-ray diffraction measurements is discussed, by introducing Li{sup +} ions in the Y{sub 2}O{sub 3}:Tm{sup 3+}/Yb{sup 3+} nanocrystals. The cause of the enhancement is the modification of the local symmetry induced by the Li{sup +} ions, which increases the intra-4f transitions of Tm{sup 3+} ion. Li{sup +} ions doped in Y{sub 2}O{sub 3}:Tm{sup 3+}/Yb{sup 3+} nanocrystals also can reduce the OH groups, dissociate the Yb{sup 3+} and Tm{sup 3+} ion clusters, and create the oxygen vacancies, which are the other reasons for enhancing the upconversion emission intensities. This material may be promising for in vitro and in vivo bioimaging probes.

  13. High-efficient near-infrared quantum cutting based on broadband absorption in Eu2+-Yb3+ co-doped glass for photovoltaic applications

    NASA Astrophysics Data System (ADS)

    Liu, Zijun; Dai, Nengli; Yang, Luyun; Li, Jinyan

    2015-05-01

    We report that Eu2+-Yb3+ system with high luminescent quantum efficiency and broadband excitation could be playing a significant role in solar cells. This borosilicate glass used as conversion layer can efficiently minimize the energy loss of thermalization. The cooperative energy transfer between Eu2+ and Yb3+ realized the emission of greenish and near-infrared light simultaneously with the blue light of xenon lamp excitation. The emission peaks located at 980 nm and 1,030 nm are the characteristic emission of Yb3+ with the energy matches well with the bandgap of silicon solar cells. The luminescent quantum efficiency is up to 163.5 % with the radiation rate being considered. Given the broad excitation band, high quantum efficiency and excellent mechanical, thermal and chemical stability, this system can be useful as down-conversion layer for solar cells.

  14. Specific features of magnetoresistance during the antiferromagnet-paramagnet transition in Tm{sub 1-x}Yb{sub x}B{sub 12}

    SciTech Connect

    Sluchanko, N. E. Azarevich, A. N.; Bogach, A. V.; Glushkov, V. V.; Demishev, S. V.; Levchenko, A. V.; Filippov, V. B.; Shitsevalova, N. Yu.

    2013-05-15

    The transverse magnetoresistance {Delta}{rho}/{rho}(H, T) of Tm{sub 1-x}Yb{sub x}B{sub 12} single crystals is studied in the ytterbium concentration range corresponding to the antiferromagnet-paramagnet transition in a magnetic field up to 80 kOe at low temperatures. A magnetic H-T phase diagram is constructed for the antiferromagnetic state of substitutional Tm{sub 1-x}Yb{sub x}B{sub 12} solid solutions with x {<=} 0.1. The contributions to the magnetoresistance in the antiferromagnetic and paramagnetic phases of the dodecaborides under study are separated. Along with negative quadratic magnetoresistance -{Delta}{rho}/{rho} {proportional_to} H{sub 2}, the magnetically ordered phase of these compounds is found to have component {Delta}{rho}/{rho} {proportional_to} H that linearly changes in a magnetic field. The negative contribution to the magnetoresistance of Tm{sub 1-x}Yb{sub x}B{sub 12} is analyzed in terms of the Yosida model for a local magnetic susceptibility.

  15. White upconversion emission in Y{sub 2}O{sub 3}:Er{sup 3+}–Tm{sup 3+}–Yb{sup 3+}phosphor

    SciTech Connect

    Rai, Vineet Kumar; Dey, Riya; Kumar, Kaushal

    2013-06-01

    Graphical abstract: Schematic energy level diagram of Er{sup 3+}–Yb{sup 3+}–Tm{sup 3+} system upon excitation at 980 nm. Highlights: ? Prepared the Er{sup 3+}–Tm{sup 3+}–Yb{sup 3+} codoped Y{sub 2}O{sub 3} phosphor. ? Excitation of the sample by 980 nm diode laser is studied. ? Explored the possibility of getting white light emission from the synthesized phosphor. ? Colour tunability of the prepared phosphor is studied. ? Temperature sensing behaviour is investigated using FIR studied. - Abstract: Er{sup 3+}–Tm{sup 3+}–Yb{sup 3+} codoped Y{sub 2}O{sub 3} phosphor has been synthesized by optimized combustion synthesis process and its white light upconversion emission property is investigated using cheap 980 nm diode laser excitation. Efficient red, green and blue light emission bands, necessary for attaining white light emission, are observed in the codoped sample. The concentration of each rare earth ion is adjusted to get the required emission. In this phosphor, interestingly, emission colour coordinates are found to almost independent on the excitation power density. The temperature sensing behaviour of the prepared samples has also been studied using fluorescence intensity ratio (FIR) technique.

  16. Cooperative reduction by Ln(2+) and Cp*(-) ions: synthesis and properties of Sm, Eu, and Yb complexes with 3,6-di-tert-butyl-o-benzoquinone.

    PubMed

    Pushkarevsky, Nikolay A; Ogienko, Mikhail A; Smolentsev, Anton I; Novozhilov, Igor N; Witt, Alexander; Khusniyarov, Marat M; Cherkasov, Vladimir K; Konchenko, Sergey N

    2016-01-01

    The first examples of samarium, europium, and ytterbium complexes with 3,6-di-tert-butyl-o-benzoquinone (3,6-dbbq) in the form of catecholate have been obtained by reactions of the quinone with the corresponding lanthanocenes, (n = 1 or 2) in solution. In the course of the reactions lanthanide ions lose one or two Cp* ligands, which take part in reduction of a quinone molecule into a catecholate anion (dbcat, 2-). As a result of the reactions, Sm and Yb clearly yield dimeric complexes [(LnCp*)2(dbcat)2], where each Ln ion loses one Cp* ligand. Eu forms a trimeric complex [(EuCp*)(Eu·thf)2(dbcat)3], in which one Eu ion is coordinated by one Cp* ligand, while two Eu ions have lost all Cp* ligands and are coordinated by THF molecules instead. Magnetic properties corroborate the assignment of oxidation states made on the basis of single-crystal X-ray diffraction: all the quinone ligands are present in the catecholate state; both Sm/Yb ions in the dimers are in the +3 oxidation state, whereas the Eu trimer contains two Eu(ii) and one Eu(iii) ions. Cyclovoltammetry studies show the presence of two reversible oxidation waves for all complexes, presumably concerned with the redox transitions of the dbcat ligands. PMID:26674171

  17. Upconversion luminescence and blackbody radiation in tetragonal YSZ co-doped with Tm(3+) and Yb(3.).

    PubMed

    Soares, M R N; Ferro, M; Costa, F M; Monteiro, T

    2015-12-21

    Lanthanide doped inorganic nanoparticles with upconversion luminescence are of utmost importance for biomedical applications, solid state lighting and photovoltaics. In this work we studied the downshifted luminescence, upconversion luminescence (UCL) and blackbody radiation of tetragonal yttrium stabilized zirconia co-doped with Tm(3+) and Yb(3+) single crystals and nanoparticles produced by laser floating zone and laser ablation in liquids, respectively. The photoluminescence (PL) and PL excitation (PLE) were investigated at room temperature (RT). PL spectra exhibit the characteristic lines in UV, blue/green, red and NIR regions of the Tm(3+) (4f(12)) under resonant excitation into the high energy (2S+1)LJ multiplets. Under NIR excitation (980 nm), the samples placed in air display an intense NIR at ?800 nm due to the (1)G4?(3)H5/(3)H4?(3)H6 transitions. Additionally, red, blue/green and ultraviolet UCL is observed arising from higher excited (1)G4 and (1)D2 multiplets. The power excitation dependence of the UCL intensity indicated that 2-3 low energy absorbed photons are involved in the UCL for low power levels, while for high powers, the identified saturation is dependent on the material size with a enhanced effect on the NPs. The temperature dependence of the UCL was investigated for single crystals and targets used in the ablation. An overall increase of the integrated intensity was found to occur between 12 K and the RT. The thermally activated process is described by activation energies of 10 meV and 30 meV for single crystals and targets, respectively. For the NPs, the UCL was found to be strongly sensitive to pressure conditions. Under vacuum conditions, instead of the narrow lines of the Tm(3+), a wide blackbody radiation was detected, responsible for the change in the emission colour from blue to orange. This phenomenon is totally reversible when the NPs are placed at ambient pressure. The UCL/blackbody radiation in the nanosized material exhibits non-contact pressure colour-based sensor characteristics. Moreover, tuning the color of the blackbody radiation in the nanoparticles by harvesting the low energy photons into the visible spectral region was found to be possible by adjusting the excitation power, paving the way for further developments of these nanoparticles for lighting and photovoltaic applications. PMID:26469333

  18. Synthesis, crystal structures, magnetic and electric transport properties of Eu{sub 11}InSb{sub 9} and Yb{sub 11}InSb{sub 9}

    SciTech Connect

    Xia Shengqing; Hullmann, Jonathan; Bobev, Svilen Ozbay, Arif; Nowak, Edmund R.; Fritsch, Veronika

    2007-07-15

    Two new rare-earth metal containing Zintl phases, Eu{sub 11}InSb{sub 9} and Yb{sub 11}InSb{sub 9} have been synthesized by reactions of the corresponding elements in molten In metal to serve as a self-flux. Their crystal structures have been determined by single crystal X-ray diffraction-both compounds are isostructural and crystallize in the orthorhombic space group Iba2 (No. 45), Z=4 with unit cell parameters a=12.224(2) A, b=12.874(2) A, c=17.315(3) A for Eu{sub 11}InSb{sub 9}, and a=11.7886(11) A, b=12.4151(12) A, c=16.6743(15) A for Yb{sub 11}InSb{sub 9}, respectively (Ca{sub 11}InSb{sub 9}-type, Pearson's code oI84). Both structures can be rationalized using the classic Zintl rules, and are best described in terms of discrete In-centered tetrahedra of Sb, [InSb{sub 4}]{sup 9-}, isolated Sb dimers, [Sb{sub 2}]{sup 4-}, and isolated Sb anions, Sb{sup 3-}. These anionic species are separated by Eu{sup 2+} and Yb{sup 2+} cations, which occupy the empty space between them and counterbalance the formal charges. Temperature-dependent magnetic susceptibility and resistivity measurements corroborate such analysis and indicate divalent Eu and Yb, as well as poorly metallic behavior for both Eu{sub 11}InSb{sub 9} and Yb{sub 11}InSb{sub 9}. The close relationships between these structures and those of the monoclinic {alpha}-Ca{sub 21}Mn{sub 4}Sb{sub 18} and Ca{sub 21}Mn{sub 4}Bi{sub 18} are also discussed. - Graphical abstract: Reported are the synthesis, the structure and the magnetic and electronic properties of two new rare-earth Zintl phases, Eu{sub 11}InSb{sub 9} and Yb{sub 11}InSb{sub 9}. The close relationships between these structures and those of the monoclinic {alpha}-Ca{sub 21}Mn{sub 4}Sb{sub 18} and Ca{sub 21}Mn{sub 4}Bi{sub 18} are also discussed.

  19. "White" phosphor on the basis of Gd2(MoO4)3: Tm,Tb,Eu single crystal

    NASA Astrophysics Data System (ADS)

    Sinitsyn, V. V.; Redkin, B. S.; Kiselev, A. P.; Shmurak, S. Z.; Kolesnikov, N. N.; Kveder, V. V.; Ponyatovsky, E. G.

    2015-08-01

    A single-crystal sample of Gd2(MoO4)3 simultaneously doped with europium, terbium and thulium is grown. The Tm, Tb and Eu dopants are employed as the luminescent centers emitting light in the red, green and blue ranges. Spectroscopy investigation reveals that simultaneous luminescence of the centers of all three types to produce white light occurs only under the sample excitation with ultraviolet (UV) light within the wavelength range 350 < ? < 370 nm. A commercial UV light-emitting diode (LED) with ?LED = 365 nm is applied in order to show that the Gd2(MoO4)3:Tm,Tb,Eu crystal converts its UV flux into white light. So, it is demonstrated that white light may be produced using one matrix with luminous centers of three types.

  20. 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.

  1. New intercalation compounds of layered lanthanide oxychlorides LnOCl (Ln = Ho, Er, Tm, and Yb) with pyridine and substituted pyridines

    SciTech Connect

    Song, K.; Kauzlarich, S.M. )

    1994-04-01

    The lanthanide oxychlorides of Ho, Er, Tm, and Yb crystallize in the hexagonal space group, R[bar 3]m as a mixture of the SmSI- and YOF-type layered structures. The oxychlorides are prepared by heating Ln[sub 2]O[sub 3] (Ln = Ho, Er, Tm, and Yb) with excess NH[sub 4]Cl, followed by pyrohydrolysis. Crystalline phases of the lanthanide oxychlorides are obtained by heating LnOCl in LiCl/KCl fluxes at 450[degrees]C. The cell parameters obtained from X-ray powder diffraction are as follows: HoOCl, a = 3.7697, c = 27.766 [angstrom]; ErOCl, a = 3.745, c = 27.719 [angstrom]; TmOCl, a = 3.708, c = 27.72 [angstrom]; YbOCl, a = 3.704, c = 27.68 [angstrom]. A series of new pyridine intercalation compounds, (py)[sub x]LnOCl, have been prepared by reactions of pyridine with the LnOCl hosts. Intercalation compounds are characterized by X-ray powder diffraction, mass spectroscopy, elemental analysis, thermal gravimetric analysis, infrared spectroscopy, and temperature-dependent magnetic susceptibility. There is no reduction in the host lattice and pyridine apparently intercalates as the neutral molecule. An acid-base interaction is proposed for the mode of intercalation of pyridine into the lanthanide oxychlorides. Further studies on the intercalation of substituted pyridines, 4-ethylpyridine, and 2,6-lutidine, indicate that the C[sub 2] axis of pyridine is oriented perpendicular to the LnOCl layers. 38 refs., 7 figs., 6 tabs.

  2. Multiple thermoluminescence glow peaks and afterglow suppression in CsI:Tl co-doped with Eu2+ or Yb2+

    NASA Astrophysics Data System (ADS)

    Bartram, R. H.; Kappers, L. A.; Hamilton, D. S.; Brecher, C.; Ovechkina, E. E.; Miller, S. R.; Nagarkar, V. V.

    2015-04-01

    CsI:Tl is a widely utilized scintillator material with many desirable properties but its applicability is limited by persistent afterglow. However, effective afterglow suppression has been achieved by co-doping with divalent lanthanides. The present report is concerned with observation of multiple thermoluminescence glow peaks in CsI:Tl,Eu and CsI:Tl,Yb, attributed to varying distributions of charge-compensating cation vacancies relative to divalent lanthanide co-dopants, and the subsequent modification of these distributions by repeated observations. It is observed that Yb2+ provides a slightly shallower electron trap than Eu2+, and that it can occupy a face-centered position by virtue of its relatively small ionic radius; the latter observation is confirmed by electrostatic calculations. It is also found that repeated observation of thermoluminescence in these materials has a modest adverse effect on afterglow suppression.

  3. Optical properties of trigonal single crystals (Yb,Tm)Al{sub 3}(BO{sub 3}){sub 4} grown from fluxes based on the bismuth and lithium molybdates

    SciTech Connect

    Temerov, V. L. Sokolov, A. E.; Sukhachev, A. L.; Bovina, A. F.; Edel'man, I. S.; Malakhovskii, A. V.

    2008-12-15

    The conditions for synthesis of Yb{sub x}Tm{sub 1-x}Al{sub 3}(BO{sub 3}){sub 4} (x = 0, 0.1, 0.2, 1.0) single crystals from fluxes based on bismuth trimolybdate Bi{sub 2}Mo{sub 3}O{sub 12} and lithium molybdate Li{sub 2}MoO{sub 4} are investigated. It is proposed to grow them by the group method on seeds. The polarized optical absorption spectra are measured for two mutually orthogonal linear polarizations at temperatures of 100 and 300 K.

  4. An experimental design approach for hydrothermal synthesis of NaYF4: Yb3+, Tm3+ upconversion microcrystal: UV emission optimization

    NASA Astrophysics Data System (ADS)

    Kaviani Darani, Masoume; Bastani, Saeed; Ghahari, Mehdi; Kardar, Pooneh

    2015-11-01

    Ultraviolet (UV) emissions of hydrothermally synthesized NaYF4: Yb3+, Tm3+ upconversion crystals were optimized using the response surface methodology experimental design. In these experimental designs, 9 runs, two factors namely (1) Tm3+ ion concentration, and (2) pH value were investigated using 3 different ligands. Introducing UV upconversion emissions as responses, their intensity were separately maximized. Analytical methods such as XRD, SEM, and FTIR could be used to study crystal structure, morphology, and fluorescent spectroscopy in order to obtain luminescence properties. From the photo-luminescence spectra, emissions centered at 347, 364, 452, 478, 648 and 803 nm were observed. Some results show that increasing each DOE factor up to an optimum value resulted in an increase in emission intensity, followed by reduction. To optimize UV emission, as a final result to the UV emission optimization, each design had a suggestion.

  5. [Synthesis and white light emission upconversion of Tm3+, Ho3+, Yb3+ co-doped YPO4 micro-nano tubes].

    PubMed

    Zhan, Shi-Ping; Gao, Yong-Yi; Huang, Hai; Zhong, Hui

    2012-10-01

    Tm3+, Ho3+, Yb3+ co-doped YPO4 micro-nano tubes were synthesized by hydrothermal method. Under the 980 nm near infrared (NI) excitation, the micro-nano tubes emitted red, green, blue visible light and a near infrared emission centered at 795 nm. The optical properties and structure of the synthesized Tm3+, Ho3+, Yb3+ co-doped YPO4 micro-nano tubes were characterized by testing the TEM, XRD and fluorescence spectra. The results showed that the micro-nano tubes are pure hexagonal phase. The hydrothermal temperature had obvious effect on fluorescence spectra but little effect on phase. The intensity of the emission peaks didn't increase with the concentration of doping ions monotonously under the same reaction temperature, but changed non-monotonously due to the concentration quenching and cross relation. The possible upconversion (UC) mechanism was discussed in this paper. This UC emission intensity controllable fluorescent material has potential application in three dimension solid display, UC illumination, fluorescence detection and some other fields. PMID:23285856

  6. Depositing CdS nanoclusters on carbon-modified NaYF4:Yb,Tm upconversion nanocrystals for NIR-light enhanced photocatalysis.

    PubMed

    Tou, Meijie; Mei, Yuanyuan; Bai, Song; Luo, Zhenguo; Zhang, Yong; Li, Zhengquan

    2015-12-17

    High-quality hexagonal NaYF4:Yb,Tm upconversion nanocrystals (UCNs) prepared in organic solutions display uniform sizes and strong UC emissions, but they possess a hydrophobic surface which hinders combining them with various semiconductor nanocrystals (NCs) to form a hybrid NIR-activated photocatalyst. Herein we present a facile approach to modify hydrophobic UCNs with a uniform carbon layer and enable them with hydrophilicity and surface functionalization. The carbon shell provides a good substrate for enriching with metal ions and in situ generation of CdS nanoclusters on the particle surface which can utilize both the upconverted UV and visible emissions. The developed NaYF4:Yb,Tm@C@CdS nanoparticles are characterized with TEM, SEM, XRD, PL and UV-Vis spectra and their formation mechanism is elucidated. The products display good photocatalytic activity under visible light and obviously enhanced performance under Vis-NIR light, due to the efficient utilization of UC emissions and the strong adsorption capacity of the carbon shell. The working mechanism of the hybrid photocatalysts is also proposed. PMID:26647306

  7. Toward NIR driven photocatalyst: Fabrication, characterization, and photocatalytic activity of ?-NaYF4:Yb(3+),Tm(3+)/g-C3N4 nanocomposite.

    PubMed

    Huang, Min-Zhong; Yuan, Baoling; Dai, Leyang; Fu, Ming-Lai

    2015-12-15

    The ?-NaYF4:Yb(3+),Tm(3+)/g-C3N4 (NYT/C3N4) photocatalyst has been successfully fabricated by a stepwise method. Firstly, the advanced near-infrared (NIR) driven photocatalyst was characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and UV-Vis-NIR diffuse reflectance spectroscopy. It was found that NYT/C3N4 photocatalyst consisted of uniform hexagonal phase NaYF4 nanocrystals with about 20nm diameter distributed on surface of g-C3N4 sheets, and the NYT/C3N4 composite exhibited strong near-infrared light absorption and the energy transfer from ?-NaYF4:Yb(3+),Tm(3+) to g-C3N4 was confirmed. Secondly, the photocatalytic activities of the catalysts were evaluated by the degradation of methyl blue dye and colorless phenol under the irradiation of 980nm laser. The results suggested that NYT/C3N4 nanocomposite is an advanced NIR-driven photocatalyst. Moreover the NYT/C3N4 photocatalyst showed good stability for photocatalytic decoloration of dye in the recycled tests. This study suggested a promising system to utilize the NIR energy of sunlight for photochemical and photoelectrical applications based on g-C3N4, which will contribute to the utilization of solar energy in the future. PMID:26343979

  8. Quantum coherent control of blue, green and red emissions from codoped lanthanide ions of Er3+/Tm3+/Yb3+ by two shaped infrared ultrashort laser beams

    NASA Astrophysics Data System (ADS)

    Cheng, Wenjing; Zhang, Shian; Jia, Tianqing; Ma, Jing; Sun, Zhenrong

    2014-01-01

    The enhancement and tunable color emissions from codoped lanthanide ions of Er3+/Tm3+/Yb3+ have been studied extensively in recent decades. In this paper, we present a new scheme for quantum coherent control of two-photon absorption (TPA) and color emission in codoped lanthanide ions of Er3+/Tm3+/Yb3+ by properly phase shaping two infrared ultrashort laser beams at central frequencies of 10?650 cm-1 and 7650 cm-1, respectively. Compared with the results irradiated by transform-limited pulses, the TPA probabilities of the blue, green and red emissions are independently controlled in the ranges 0-13.3, 0-14.5 and 0-1.0, respectively. The effects of the energy states of lanthanide ions and the laser spectral bandwidths on the coherent features are also discussed. The TPA probabilities for the blue and green emissions increase with the laser spectral bandwidths and decrease with the energy bandwidths of the final level states. As the intermediate energy level shifts in the range 10?100-10?500 cm-1, the TPA probabilities for the blue and green emissions change in the ranges 7-15 and 8-17, respectively.

  9. The action mechanism of TiO{sub 2}:NaYF{sub 4}:Yb{sup 3+},Tm{sup 3+} cathode buffer layer in highly efficient inverted organic solar cells

    SciTech Connect

    Liu, Chunyu; Chen, Huan; Zhao, Dan; Shen, Liang; He, Yeyuan; Guo, Wenbin E-mail: chenwy@jlu.edu.cn; Chen, Weiyou E-mail: chenwy@jlu.edu.cn

    2014-08-04

    We report the fabrication and characteristics of organic solar cells with 6.86% power conversion efficiency (PCE) by doping NaYF{sub 4}:Yb{sup 3+},Tm{sup 3+} into TiO{sub 2} cathode buffer layer. The dependence of devices performance on doping concentration of NaYF{sub 4}:Yb{sup 3+},Tm{sup 3+} is investigated. Results indicate that short-circuit current density (J{sub sc}) has an apparent improvement, leading to an enhancement of 22.7% in PCE for the optimized doping concentration of 0.05?mmol ml{sup ?1} compared to the control devices. NaYF{sub 4}:Yb{sup 3+},Tm{sup 3+} nanoparticles (NPs) can play threefold roles, one is that the incident light in visible region can be scattered by NaYF{sub 4} NPs, the second is that solar irradiation in infrared region can be better utilized by Up-conversion effect of Yb{sup 3+} and Tm{sup 3+} ions, the third is that electron transport property in TiO{sub 2} thin film can be greatly improved.

  10. Impact of codopant ions on 2.5-3.0 ?m emission of Er3+:4I11/2?4I13/2 transition in Yb,Er,Eu:LaYSGG crystal

    NASA Astrophysics Data System (ADS)

    Wang, Yan; Li, Jianfu; Zhu, Zhaojie; You, Zhenyu; Xu, Jinlong; Tu, Chaoyang

    2015-12-01

    The crystal of 1 at% Yb3+, 10 at% Er3+ and 0.1 at% Eu3+ triply doped La0.3Y2.7Sc2Ga3O12 (abbr. as Yb,Er,Eu:LaYSGG) was grown for the first time by using a Czochralski technique. Its absorption, near-infrared and mid-infrared fluorescence spectra, as well as the fluorescence decay curves of Er:4I13/2 and 4I11/2 levels were measured at room temperature. The spectroscopic properties including the absorption and emission cross-sections as well as the fluorescence lifetimes of the title crystal were revealed and compared with 10 at% Er3+:Y3Sc2Ga3O12 crystal. Spectral analyses show that the sensitization of Yb3+ ion leads to an enhanced 2.5-3.0 ?m emission corresponding to Er3+:4I11/2?4I13/2 transition in the grown crystal, meanwhile, the depopulation of Eu3+ ion from Er3+ inhibits the self-termination effect successfully. The energy transfer mechanism was discussed; the energy transfer efficiencies of Yb3+?Er3+ (ET1) and Er3+?Eu3+ (ET2) were estimated to be 94.8% and 93.9%, respectively. The results indicates that Yb,Er,Eu:LaYSGG crystal is a good candidate for LD pumped mid-infrared laser.

  11. Vacuum ultraviolet and near-infrared excited luminescence properties of Ca{sub 3}(PO{sub 4}){sub 2}:RE{sup 3+}, Na{sup +} (RE=Tb, Yb, Er, Tm, and Ho)

    SciTech Connect

    Zhang Jia; Wang Yuhua; Guo Linna; Zhang Feng; Wen Yan; Liu Bitao; Huang Yan

    2011-08-15

    Tb{sup 3+}, Yb{sup 3+}, Tm{sup 3+}, Er{sup 3+}, and Ho{sup 3+} doped Ca{sub 3}(PO{sub 4}){sub 2} were synthesized by solid-state reaction, and their luminescence properties were studied by spectra techniques. Tb{sup 3+}-doped samples can exhibit intense green emission under VUV excitation, and the brightness for the optimal Tb{sup 3+} content is comparable with that of the commercial Zn{sub 2}SiO{sub 4}:Mn{sup 2+} green phosphor. Under near-infrared laser excitation, the upconversion luminescence spectra of Yb{sup 3+}, Tm{sup 3+}, Er{sup 3+}, and Ho{sup 3+} doped samples demonstrate that the red, green, and blue tricolored fluorescence could be obtained by codoping Yb{sup 3+}-Ho{sup 3+}, Yb{sup 3+}-Er{sup 3+}, and Yb{sup 3+}-Tm{sup 3+} in Ca{sub 3}(PO{sub 4}){sub 2}, respectively. Good white upconversion emission with CIE chromaticity coordinates (0.358, 0.362) is achieved by quadri-doping Yb{sup 3+}-Tm{sup 3+}-Er{sup 3+}-Ho{sup 3+} in Ca{sub 3}(PO{sub 4}){sub 2}, in which the cross-relaxation process between Er{sup 3+} and Tm{sup 3+}, producing the {sup 1}D{sub 2}-{sup 3}F{sub 4} transition of Tm{sup 3+}, is found. The upconversion mechanisms are elucidated through the laser power dependence of the upconverted emissions and the energy level diagrams. - Graphical abstract: The CPO:0.25Tb{sup 3+}, 0.25Na{sup +} exhibits a comparable brightness to the commercial Zn{sub 2}SiO{sub 4}:Mn{sup 2+} upon 147 nm excitation. Good white light color is achieved in CPO:Yb{sup 3+}-Tm{sup 3+}-Er{sup 3+}-Ho{sup 3+} under 980 nm excitation. Highlights: > Ca{sub 3}(PO{sub 4}){sub 2}:Tb{sup 3+},Na{sup +} exhibits a comparable brightness with commercial Zn{sub 2}SiO{sub 4}:Mn{sup 2+}. > Red, green and blue colors are achieved in Yb{sup 3+}, Ho{sup 3+}, Er{sup 3+}, Tm{sup 3+} doped Ca{sub 3}(PO{sub 4}){sub 2}. > Good white emission is obtained in Yb{sup 3+}-Ho{sup 3+}-Er{sup 3+}-Tm{sup 3+} quadri-doped Ca{sub 3}(PO{sub 4}){sub 2}. > Ca{sub 3}(PO{sub 4}){sub 2}:Tb{sup 3+}, Yb{sup 3+}, Ho{sup 3+}, Er{sup 3+}, Tm{sup 3+} could be potential phosphors.

  12. High-power widely tunable Tm:fibre lasers pumped by an Er,Yb co-doped fibre laser at 1.6 ?m

    NASA Astrophysics Data System (ADS)

    Shen, D. Y.; Sahu, J. K.; Clarkson, W. A.

    2006-06-01

    High-power and widely tunable Tm-doped silica fibre lasers cladding-pumped and core-pumped by a 1565 nm Er,Yb fibre laser are reported. Output power up to 19.2W was generated from the cladding-pumped cavity configuration for ~38.2W of launched pump power and with slope efficiency up to ~72% with respect to absorbed pump power. Wavelength tuning was realized by use of an external cavity containing a diffraction grating. A maximum output power of 17.4 W at 1941 nm was generated for 38.2 W of launched pump power and the operating wavelength could be tuned over 202 nm from 1859 to 2061 nm. In the core-pumped configuration, a maximum output power of 12.1 W was generated at 1851 nm for 23.1 W absorbed pump power using a simple free-running cavity configuration with only ~24 cm of Tm-doped fibre. By employing a tunable cavity configuration, the operating wavelength of the core-pumped Tm:fibre laser could be tuned over 250 nm from 1723-1973 nm at multiwatt power levels.

  13. Synthesis, characterisation and properties of rare earth oxyselenides A4O4Se3 (A = Eu, Gd, Tb, Dy, Ho, Er, Yb and Y).

    PubMed

    Tuxworth, Andrew J; Wang, Chun-Hai; Evans, John S O

    2015-02-21

    Rare earth oxyselenides A4O4Se3 (A = Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Yb and Y) were synthesised using solid state reactions and three new structure types (?, ?, and ?) were observed. A4O4Se3 materials adopt either the ? (A = Nd, Sm), ? (A = Eu), ? (A = Gd, Tb) or ? (A = Dy, Ho, Er, Yb, Y) structure depending on the rare earth radius. Each structure type contains alternating [A2O2](2+) and Se(2-)/Se2(2-) layers. Different ordered and disordered arrangements of Se(2-) and [Se-Se](2-) give the Se layer flexibility and lead to the four different structure types observed. The volume coefficients of expansion for A4O4Se3 ranged from +1.746(9) × 10(-5) to +2.237(3) × 10(-5) K(-1) from 12 to 300 K; no structural phase transitions were observed in this temperature range. Diffuse reflection spectra show A4O4Se3 are semiconductors with band gap Eg 1.02-1.46 eV. Gd4O4Se3, Dy4O4Se3, and Tb4O4Se3 samples show antiferromagnetic ordering with Néel temperature, TN, of 7-9 K. DFT calculations confirm the two different valence states of Se(2-) and Se2(2-) in Eu4O4Se3. PMID:25581725

  14. Controlled growth, intense upconversion emissions and concentration induced luminescence switching of bifunctional Tm(3+) doped hexagonal NaYb0.55Gd0.45F4 nanorods.

    PubMed

    Qu, Xilong; Li, Yongchang; Yu, Suixi; Yang, Liwen

    2013-11-01

    Bifunctional hexagonal Tm(3+) doped NaYb0.55Gd0.45F4 nanorods with tunable size are prepared via in situ cation-exchange reaction using hydrothermal method. The measured field dependence of magnetization of the NaYb0.55Gd0.45F4 nanorods shows typical paramagnetic characteristics that can be ascribed to the non-interacting localized nature of the magnetic moment of rare-earth ions. When excited by a 980nm laser, these nanorods exhibit intense multi-color up-conversion (UC) emissions in infrared, red, blue and especially ultraviolet. In addition, luminescent switching between different UC emission wavelengths of 480nm and 450nm is observed by adjusting Tm(3+) doping concentration. Based on power-dependent spectral analyses, it is found that with the increase of Tm(3+) doping concentration, due to the suppressed saturation effect, the dominative UC process redistribute the populations at (1)G4 and (1)D2(Tm(3+)) states of Tm(3+) ion resulting in the above luminescent switching. Our results indicate that bifunctional hexagonal NaYb1-xGdxF4 nanocrystals have potential applications in miniaturized solid-state light sources, optical processing sensors and fluorescent biolabels. PMID:23871979

  15. Effects of water on Eu/sup 2 +/, Yb/sup 2 +/, and Es/sup 2 +/ cocrystallization in the Sr(Sm)SO/sub 4/-ethanol system

    SciTech Connect

    Mikheev, N.B.; Kamenskaya, A.N.; Kulyukhin, S.A.

    1988-11-01

    Measurements have been made on the effects of water on the cocrystallization of divalent europium, ytterbium, and einsteinium in the Sr(Sm)SO/sub 4/-ethanol system. Water levels from 3 to 6 M affect the Eu/sup 2 +/ and Yb/sup 2 +/ cocrystallization coefficients, while above 6 M, they do not alter. With divalent einsteinium, there are changes in the coefficient up to (H/sub 2/O) = 10 M. The effects of the water concentration on the solubility have been examined for the sulfates of these three elements.

  16. Wideband saturable absorption in few-layer molybdenum diselenide (MoSe?) for Q-switching Yb-, Er- and Tm-doped fiber lasers.

    PubMed

    Woodward, R I; Howe, R C T; Runcorn, T H; Hu, G; Torrisi, F; Kelleher, E J R; Hasan, T

    2015-07-27

    We fabricate a free-standing molybdenum diselenide (MoSe2) saturable absorber by embedding liquid-phase exfoliated few-layer MoSe2 flakes into a polymer film. The MoSe2-polymer composite is used to Q-switch fiber lasers based on ytterbium (Yb), erbium (Er) and thulium (Tm) gain fiber, producing trains of microsecond-duration pulses with kilohertz repetition rates at 1060 nm, 1566 nm and 1924 nm, respectively. Such operating wavelengths correspond to sub-bandgap saturable absorption in MoSe2, which is explained in the context of edge-states, building upon studies of other semiconducting transition metal dichalcogenide (TMD)-based saturable absorbers. Our work adds few-layer MoSe2 to the growing catalog of TMDs with remarkable optical properties, which offer new opportunities for photonic devices. PMID:26367663

  17. Triple-doped KMnF3:Yb(3+)/Er(3+)/Tm(3+) nanocubes: four-color upconversion emissions with strong red and near-infrared bands.

    PubMed

    Wang, Hao; Hong, Xiaodong; Han, Renlu; Shi, Junhui; Liu, Zongjun; Liu, Shujuan; Wang, You; Gan, Yang

    2015-01-01

    Triple-doped (Yb(3+)/Er(3+)/Tm(3+)) KMnF3 nanocubes with uniform sizes of 250?nm were synthesized by a facile hydrothermal route using the oleic acid as the capping agent. It was found that these nanocubes can simultaneously exhibited four-color (blue, green, red and NIR) upconversion emissions under a single 980?nm near-infrared (NIR) laser excitation, which should have potential multicolor in vivo imaging applications. Specifically, the red (660?nm) and NIR (800?nm) peaks, known as two "optical windows" for imaging biological tissues, were strong. The spectral and pump analyses indicated the two-photon processes were responsible for the both red and NIR emissions. PMID:26608870

  18. Rational morphology control of ?-NaYF4:Yb,Er/Tm upconversion nanophosphors using a ligand, an additive, and lanthanide doping

    NASA Astrophysics Data System (ADS)

    Na, Hyejin; Woo, Kyoungja; Lim, Kipil; Jang, Ho Seong

    2013-05-01

    We report the systematic control of the morphology of ?-NaYF4:Yb,Er/Tm upconversion nanophosphors (UCNPs) from large spheres (37.9 nm) to rods (length = 60.1 nm, width = 21.5 nm) and from rods to hexagonal prisms (length = 48.8 nm, width = 44.0 nm) or small spheres (14.0 nm) by the use of a surfactant, an additive, and lanthanide doping. Increasing the ratio of oleic acid (OA) to 1-octadecene (ODE) caused a decrease in the size of the UCNPs, and increasing the OA/ODE ratio above a critical value caused the particle shape to change from a sphere to a rod. The length-to-width aspect ratio (AR) of upconversion nanorods (UCNRs) was finely manipulated from 1.28 to 2.80. The rounded tips of the UCNRs were flattened by adding Cl- ions, and the UCNRs changed to hexagonal prisms with a controllable AR depending on the quantity of Cl- ions. Additionally, the morphology of the ?-NaYF4-based UCNPs was controlled by lanthanide doping. The size and AR of the UCNRs decreased with Gd3+ doping, and the UCNRs ultimately transformed into small spheres (14.0 nm) with high monodispersity. Doping with Ce3+ ions also decreased the AR of the UCNRs from 2.80 to 1.27. In addition, highly transparent polymer composites for 3D volumetric displays were fabricated by blending high-AR ?-NaYF4:Yb,Er/Tm UCNRs with polydimethylsiloxane. These composites exhibited bright green and blue upconversion light during excitation with 980 nm light.We report the systematic control of the morphology of ?-NaYF4:Yb,Er/Tm upconversion nanophosphors (UCNPs) from large spheres (37.9 nm) to rods (length = 60.1 nm, width = 21.5 nm) and from rods to hexagonal prisms (length = 48.8 nm, width = 44.0 nm) or small spheres (14.0 nm) by the use of a surfactant, an additive, and lanthanide doping. Increasing the ratio of oleic acid (OA) to 1-octadecene (ODE) caused a decrease in the size of the UCNPs, and increasing the OA/ODE ratio above a critical value caused the particle shape to change from a sphere to a rod. The length-to-width aspect ratio (AR) of upconversion nanorods (UCNRs) was finely manipulated from 1.28 to 2.80. The rounded tips of the UCNRs were flattened by adding Cl- ions, and the UCNRs changed to hexagonal prisms with a controllable AR depending on the quantity of Cl- ions. Additionally, the morphology of the ?-NaYF4-based UCNPs was controlled by lanthanide doping. The size and AR of the UCNRs decreased with Gd3+ doping, and the UCNRs ultimately transformed into small spheres (14.0 nm) with high monodispersity. Doping with Ce3+ ions also decreased the AR of the UCNRs from 2.80 to 1.27. In addition, highly transparent polymer composites for 3D volumetric displays were fabricated by blending high-AR ?-NaYF4:Yb,Er/Tm UCNRs with polydimethylsiloxane. These composites exhibited bright green and blue upconversion light during excitation with 980 nm light. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr00080j

  19. Wideband saturable absorption in few-layer molybdenum diselenide (MoSe2) for Q-switching Yb-, Er- and Tm-doped fiber lasers

    E-print Network

    Woodward, R I; Runcorn, T H; Hu, G; Torrisi, F; Kelleher, E J R; Hasan, T

    2015-01-01

    We fabricate a free-standing molybdenum diselenide (MoSe2) saturable absorber by embedding liquid-phase exfoliated few-layer MoSe2 flakes into a polymer film. The MoSe2-polymer composite is used to Q-switch fiber lasers based on ytterbium (Yb), erbium (Er) and thulium (Tm) gain fiber, producing trains of microsecond-duration pulses with kilohertz repetition rates at 1060 nm, 1566 nm and 1924 nm, respectively. Such operating wavelengths correspond to sub-bandgap saturable absorption in MoSe2, which is explained in the context of edge-states, building upon studies of other semiconducting transition metal dichalcogenide (TMD)-based saturable absorbers. Our work adds few-layer MoSe2 to the growing catalog of TMDs with remarkable optical properties, which offer new opportunities for photonic devices.

  20. [Effect of bivalent alkaline earth fluorides introduction on thermal stability and spectroscopic properties of Er3+/Tm3+ /Yb3+ co-doped oxyfluorogermanate glasses].

    PubMed

    Hu, Yue-bo; Zhang, Xin-na; Zhou, Da-li; Jiao, Qing; Wang, Rong-fei; Huang, Jin-feng; Long, Xiao-bo; Qiu, Jian-bei

    2012-01-01

    Transparent Er3+/Tm3+ /Yb3+ co-doped oxyfluorogermanate glasses alone containing MgF2, CaF2, SrF2 or BaF2 and nano-glass-ceramics only containing BaF2 were prepared. The thermal stabilities and the up-conversion emission properties of the samples were investigated. Analyses of absorbance spectra reveal that the UV cutoff band moves slightly to shortwave band with the doping bivalent cation mass increasing. The results show that the emission color can be adjusted by changing the alkaline earth cation species in the glass matrixes, especially as Mg2+ is concerned, and the emission intensity can increase notably by heating the glass containing alkaline-earth fluoride into glass ceramic containing alkaline-earth fluoride nanocrystals or increasing the content of bivalent alkaline earth fluorides. PMID:22497127

  1. Triple-doped KMnF3:Yb3+/Er3+/Tm3+ nanocubes: four-color upconversion emissions with strong red and near-infrared bands

    PubMed Central

    Wang, Hao; Hong, Xiaodong; Han, Renlu; Shi, Junhui; Liu, Zongjun; Liu, Shujuan; Wang, You; Gan, Yang

    2015-01-01

    Triple-doped (Yb3+/Er3+/Tm3+) KMnF3 nanocubes with uniform sizes of 250?nm were synthesized by a facile hydrothermal route using the oleic acid as the capping agent. It was found that these nanocubes can simultaneously exhibited four-color (blue, green, red and NIR) upconversion emissions under a single 980?nm near-infrared (NIR) laser excitation, which should have potential multicolor in vivo imaging applications. Specifically, the red (660?nm) and NIR (800?nm) peaks, known as two “optical windows” for imaging biological tissues, were strong. The spectral and pump analyses indicated the two-photon processes were responsible for the both red and NIR emissions. PMID:26608870

  2. Real-time, non-invasive monitoring of hydrogel degradation using LiYF4:Yb(3+)/Tm(3+) NIR-to-NIR upconverting nanoparticles.

    PubMed

    Jalani, Ghulam; Naccache, Rafik; Rosenzweig, Derek H; Lerouge, Sophie; Haglund, Lisbet; Vetrone, Fiorenzo; Cerruti, Marta

    2015-07-14

    To design a biodegradable hydrogel as cell support, one should know its in vivo degradation rate. A technique commonly used to track gel degradation is fluorescence spectroscopy. However, the fluorescence from conventional fluorophores quickly decays, and the fluorophores are often moderately cytotoxic. Most importantly, they require ultraviolet or visible (UV-Vis) light as the excitation source, which cannot penetrate deeply through biological tissues. Lanthanide-doped upconverting nanoparticles (UCNPs) are exciting alternatives to conventional fluorophores because they can convert near-infrared (NIR) to UV-Vis-NIR light via a sequential multiphoton absorption process referred to as upconversion. NIR light can penetrate up to few cm inside tissues, thus making these UCNPs much better probes than conventional fluorophores for in vivo monitoring. Also, UCNPs have narrow emission bands, high photoluminescence (PL) signal-to-noise ratio, low cytotoxicity and good physical and chemical stability. Here, we show a nanocomposite system consisting of a biodegradable, in situ thermogelling injectable hydrogel made of chitosan and hyaluronic acid encapsulating silica-coated LiYF4:Yb(3+)/Tm(3+) UCNPs. We use these UCNPs as photoluminescent tags to monitor the gel degradation inside live, cultured intervertebral discs (IVDs) over a period of 3 weeks. PL spectroscopy and NIR imaging show that NIR-to-NIR upconversion of LiYF4:Yb(3+)/Tm(3+)@SiO2 UCNPs allows for tracking of the gel degradation in living tissues. Both in vitro and ex vivo release of UCNPs follow a similar trend during the first 5 days; after this time, ex vivo release becomes faster than in vitro, indicating a faster gel degradation ex vivo. Also, the amount of released UCNPs in vitro increases continuously up to 3 weeks, while it plateaus after 15 days inside the IVDs showing a homogenous distribution of UCNPs throughout the IVD tissue. This non-invasive optical method for real time, live tissue imaging holds great potential for tissue analysis, biomapping and bioimaging applications. PMID:26067274

  3. Incorporation of computed tomography and magnetic resonance imaging function into NaYF4:Yb/Tm upconversion nanoparticles for in vivo trimodal bioimaging.

    PubMed

    Shen, Ji-Wei; Yang, Cheng-Xiong; Dong, Lu-Xi; Sun, Hao-Ran; Gao, Kai; Yan, Xiu-Ping

    2013-12-17

    Rational design and fabrication of multimodal imaging nanoprobes are of great significance for in vivo imaging. Here we report the fabrication of a multishell structured NaYF4:Yb/Tm@NaLuF4@NaYF4@NaGdF4 nanoprobe via a seed-mediated epitaxial growth strategy for upconversion luminescence (UCL), X-ray computed tomography (CT), and magnetic resonance (MR) trimodal imaging. Hexagonal phase NaYF4:Yb/Tm is used as the core to provide UCL, while the shell of NaLuF4 is epitaxially grown on the core not only to provide an optically inert layer for enhancing the UCL but also to serve as a contrast agent for CT. The outermost NaGdF4 shell is fabricated as a thin layer to give the high longitudinal relaxivity (r1) desired for MR imaging. The transition shell layer of NaYF4 not only provides an interface to facilitate the formation of NaGdF4 shell but also inhibits the energy transfer from inner upconversion activator to surface paramagnetic Gd(3+) ions. The fabricated multishell structured nanoprobe shows intense near-infrared UCL, high r1 value of 3.76 mM(-1) s(-1), and in vitro CT contrast effect. The multishell structured nanoprobe offers great potential for in vivo UCL/CT/MR trimodal imaging. Further covalent bonding of folic acid makes the multishell structured nanoprobe promising for in vivo targeted UCL imaging of tumor-bearing mice. PMID:24237132

  4. Structural and Magnetothermal Properties of Compounds: Yb5SixGe4-x,Sm5SixGe4-x, EuO, and Eu3O4

    SciTech Connect

    Kyunghan Ahn

    2007-05-09

    The family of R{sub 5}Si{sub x}Ge{sub 4-x} alloys demonstrates a variety of unique physical phenomena related to magneto-structural transitions associated with reversible breaking and reforming of specific bonds that can be controlled by numerous external parameters such as chemical composition, magnetic field, temperature, and pressure. Therefore, R{sub 5}Si{sub x}Ge{sub 4-x} systems have been extensively studied to uncover the mechanism of the extraordinary magneto-responsive properties including the giant magnetoresistance (GMR) and colossal magnetostriction, as well as giant magnetocaloric effect (GMCE). Until now, more than a half of possible R{sub 5}Si{sub x}Ge{sub 4-x} pseudobinary systems have been completely or partially investigated with respect to their crystallography and phase relationships (R = La, Pr, Nd, Gd, Tb, Dy, Er, Lu, Y). Still, there are other R{sub 5}Si{sub x}Ge{sub 4-x} systems (R = Ce, Sm, Ho, Tm, and Yb) that are not studied yet. Here, we report on phase relationships and structural, magnetic, and thermodynamic properties in the Yb{sub 5}Si{sub x}Ge{sub 4-x} and Sm{sub 5}Si{sub x}Ge{sub 4-x} pseudobinary systems, which may exhibit mixed valence states. The crystallography, phase relationships, and physical properties of Yb{sub 5}Si{sub x}Ge{sub 4-x} alloys with 0 {le} x {le} 4 have been examined by using single crystal and powder x-ray diffraction at room temperature, and dc magnetization and heat capacity measurements between 1.8 K and 400 K in magnetic fields ranging from 0 to 7 T. Unlike the majority of R{sub 5}Si{sub x}Ge{sub 4-x} systems studied to date, where R is the rare earth metal, all Yb-based germanide-silicides with the 5:4 stoichiometry crystallize in the same Gd{sub 5}Si{sub 4}-type structure. The magnetic properties of Yb{sub 5}Si{sub x}Ge{sub 4-x} materials are nearly composition-independent, reflecting the persistence of the same crystal structure over the whole range of x from 0 to 4. Both the crystallographic and magnetic property data indicate that Yb{sub 5}Si{sub x}Ge{sub 4-x} alloys are mixed valence systems, in which the majority (60%) of Yb atoms is divalent, while the minority (40%) is trivalent. This finding is supported by recent Moessbauer spectroscopy data.

  5. High-temperature electrical and thermal transport properties of fully filled skutterudites RFe4Sb12 (R = Ca, Sr, Ba, La, Ce, Pr, Nd, Eu, and Yb)

    NASA Astrophysics Data System (ADS)

    Qiu, P. F.; Yang, J.; Liu, R. H.; Shi, X.; Huang, X. Y.; Snyder, G. J.; Zhang, W.; Chen, L. D.

    2011-03-01

    Fully filled skutterudites RFe4Sb12 (R = Ca, Sr, Ba, La, Ce, Pr, Nd, Eu, and Yb) have been prepared and the high-temperature electrical and thermal transport properties are investigated systematically. Lattice constants of RFe4Sb12 increase almost linearly with increasing the ionic radii of the fillers, while the lattice expansion in filled structure is weakly influenced by the filler valence charge states. Using simple charge counting, the hole concentration in RFe4Sb12 with divalent fillers (R = Ca, Sr, Ba, Eu, and Yb) is much higher than that in RFe4Sb12 with trivalent fillers (R = La, Ce, Pr, and Nd), resulting in relatively high electrical conductivity and low Seebeck coefficient. It is also found that RFe4Sb12 filled skutterudites having similar filler valence charge states exhibit comparable electrical conductivity and Seebeck coefficient, and the behavior of the temperature dependence, thereby leading to comparable power factor values in the temperature range from 300 to 800 K. All RFe4Sb12 samples possess low lattice thermal conductivity. The correlation between the lattice thermal resistivity WL and ionic radii of the fillers is discussed and a good relationship of WL ˜ (rcage-rion)3 is observed in lanthanide metal filled skutterudites. CeFe4Sb12, PrFe4Sb12, and NdFe4Sb12 show the highest thermoelectric figure of merit around 0.87 at 750 K among all the filled skutterudites studied in this work.

  6. Multi-modal luminescence properties of RE3+ (Tm3+, Yb3+) and Bi3+ activated GdNbO4 phosphors—upconversion, downshifting and quantum cutting for spectral conversion

    NASA Astrophysics Data System (ADS)

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

    2015-11-01

    This work investigates the promising multi-modal luminescence (upconversion (UC), downshifting (DS) and quantum cutting (QC)) properties of RE3+ (Tm3+, Yb3+) and Bi3+ activated GdNbO4 phosphors synthesized using the well-known solid state reaction method. Structural characterization using x-ray diffraction measurements confirms the formation of the pure phase of the GdNbO4 host with no impurities. The optical band gap (E g) of GdNbO4 (with and without RE3+ ions) calculated from UV-Vis-near-infrared (NIR) measurements was found to be the same ~4.44?eV which indicates that GdNbO4 is a wide band gap material. Further, Bi3+ doping presents an interesting E g tuning of the GdNbO4 phosphor, i.e. E g increases up to 5.38?eV. In terms of luminescence, this material produces intense blue and NIR emission via multi-modal optical processes. On NIR excitation (? exc??=??980?nm), Gd0.94Tm0.01Yb0.05NbO4 produces intense upconverted blue and NIR and relatively weak red emission. In addition to the UC process, Gd0.94Tm0.01Yb0.05NbO4 also exhibits pump power dependent variation in fluorescence intensity ratio for I 472/I 477 showing the applicability of this material as an optical heater. On UV excitation (? exc??=??265?nm), Gd0.99Tm0.01NbO4 produces intense DS blue emission due to the Tm3+ ion, overlapped with the emission of the (NbO4)3- ion through strong energy transfer (ET) from (NbO4)3- to Tm3+ ions. Interestingly, NIR QC has also been successfully observed in Gd0.9Yb0.1NbO4, Gd0.89Bi0.01Yb0.1NbO4 and Gd0.79Tm0.01Yb0.2NbO4 phosphors through cooperative ET from the (NbO4)3- group to the Yb3+ ion, Bi(6s)-Nb(4d) to the Yb3+ ion and the Tm3+ ion to the Yb3+ ion, respectively. The mechanisms involved in these processes are explained in detail in this work. The QC efficiency in this work has been found to be ~177%. Thus, the multi-modal luminescence (UC, DS and QC) property of this material makes it a promising candidate for display devices, spectral converters for enhancing the efficiency of silicon solar cells, etc.

  7. Neutron spectroscopic study of crystal-field excitations and the effect of the crystal field on dipolar magnetism in Li R F4 (R =Gd , Ho, Er, Tm, and Yb)

    NASA Astrophysics Data System (ADS)

    Babkevich, P.; Finco, A.; Jeong, M.; Dalla Piazza, B.; Kovacevic, I.; Klughertz, G.; Krämer, K. W.; Kraemer, C.; Adroja, D. T.; Goremychkin, E.; Unruh, T.; Strässle, T.; Di Lieto, A.; Jensen, J.; Rønnow, H. M.

    2015-10-01

    We present a systematic study of the crystal-field interactions in the Li R F4 (R = Gd , Ho, Er, Tm, and Yb) family of rare-earth magnets. Using detailed inelastic neutron scattering measurements, we have been able to quantify the transition energies and wave functions for each system. This allows us to quantitatively describe the high-temperature susceptibility measurements for the series of materials and make predictions based on a mean-field approach for the low-temperature thermal and quantum phase transitions. We show that coupling between crystal field and phonon states leads to line-shape broadening in LiTmF4 and level splitting in LiYbF4. Furthermore, using high-resolution neutron scattering from LiHoF4, we find anomalous broadening of crystal-field excitations which we attribute to magnetoelastic coupling.

  8. Synchrotron X-Ray Topography Study of Structural Defects and Strain in Epitaxial Structures of Yb- and Tm-Doped Potassium Rare-Earth Double Tungstates and Their Influence on Laser Performance.

    SciTech Connect

    Raghothamachar, B.; Carvajal, J; Pujol, M; Mateos, X; Sole, R; Aguilo, M; Diaz, F; Dudley, M

    2010-01-01

    Monoclinic potassium rare-earth double tungstates [KRE(WO{sub 4}){sub 2}, RE = Y, Lu, Yb; KREW] are well suited as hosts for active lanthanide ion (Ln{sup 3+}) dopants for diode-pumped solid-state lasers, with particular interest in thin-disk laser configurations when they are grown as thin films. Using synchrotron white-beam x-ray topography, we have imaged defects and strain in top-seeded solution-grown (TSSG) bulk substrates of different rare-earth tungstates as well as within Yb{sup 3+}- and Tm{sup 3+}-doped epitaxies for thin-disk laser applications grown on these substrates by liquid-phase epitaxy. Higher structural stress in Yb:KYW/KYW epitaxies compared with Yb:KLuW/KLuW epitaxies is found to lower efficiency in laser operation. The quality of Tm:KLuW/KLuW epitaxial films is sensitive to doping level, film thickness, and growth rate. Inhomogeneous stresses within the layers are dominated by lattice-mismatch effects rather than by crystallographic anisotropy.

  9. Near-infrared photocatalysts of BiVO4/CaF2:Er3+, Tm3+, Yb3+ with enhanced upconversion properties

    NASA Astrophysics Data System (ADS)

    Huang, Shouqiang; Zhu, Nanwen; Lou, Ziyang; Gu, Lin; Miao, Chen; Yuan, Haiping; Shan, Aidang

    2014-01-01

    Upconversion photocatalysts have the potential to absorb the near-infrared (NIR) light in solar energy and improve the photocatalytic performance. A hierarchical upconversion photocatalyst of BiVO4 (BVO)/CaF2:Er3+, Tm3+, Yb3+ (CF) combined with the narrow-band semiconductor of BVO and the luminescence agent of CF to enhance upconversion properties was synthesized via the hydrothermal method. The CF particles were deposited homogeneously on the surface of the BVO/CF composite with regular dendritic structure, which led to efficient upconversion emissions. The upconversion emission intensity of the BVO/CF composite was 8 times higher than that of pure CF, through tailoring the crystal symmetry of lanthanide ions by Bi3+ ions. The upconverted ultraviolet (361 and 379 nm), violet (408 nm), and blue (485 nm) light was able to excite BVO for photocatalysis in BVO/CF under NIR irradiation, which improved the degradation rate of methyl orange (MO).Upconversion photocatalysts have the potential to absorb the near-infrared (NIR) light in solar energy and improve the photocatalytic performance. A hierarchical upconversion photocatalyst of BiVO4 (BVO)/CaF2:Er3+, Tm3+, Yb3+ (CF) combined with the narrow-band semiconductor of BVO and the luminescence agent of CF to enhance upconversion properties was synthesized via the hydrothermal method. The CF particles were deposited homogeneously on the surface of the BVO/CF composite with regular dendritic structure, which led to efficient upconversion emissions. The upconversion emission intensity of the BVO/CF composite was 8 times higher than that of pure CF, through tailoring the crystal symmetry of lanthanide ions by Bi3+ ions. The upconverted ultraviolet (361 and 379 nm), violet (408 nm), and blue (485 nm) light was able to excite BVO for photocatalysis in BVO/CF under NIR irradiation, which improved the degradation rate of methyl orange (MO). Electronic supplementary information (ESI) available: Additional tables and figures. See DOI: 10.1039/c3nr05266d

  10. Structural and dielectric properties of Ba 2YbTaO 6, Ba 2YSbO 6 and Ba 2EuZrO 5.5

    NASA Astrophysics Data System (ADS)

    Konopka, Janusz; Jose, Rajan; Wo?cyrz, Marek

    2006-03-01

    Structural and dielectric properties of Ba2YbTaO6, Ba2YSbO6 and Ba2EuZrO5.5 perovskites are presented. Because these materials were suggested as prospective buffer layers and substrates for HTS electronic devices such as SIS structures etc., their chemical stability with YBa2Cu3O7-? (YBCO) and Bi2Sr2CanCun+1Ox (n = 1, 2; BiSCCO) was examined up to processing temperatures of listed superconductors. All three materials were found to be chemically stable with both YBCO and BiSCCO. Moreover, addition of ca. 20% of these perovskites to YBCO did not have any detrimental effect on the transition temperature. Dielectric properties of all a.m. materials were determined with high accuracy by measuring resonant frequencies of completely filled dielectric cavities at frequencies up to 40 GHz and at temperatures from 60 K to 350 K. The dielectric permittivities for particular materials are as follows: Ba2YbTaO6 ? ?? = 29.4; Ba2EuZrO5.5 ? ?? = 30.8; Ba2YSbO6 ? ?? = 13.5. In microwave range all materials exhibit low or moderate losses. However, at temperatures where HTS materials enter into superconducting state (80-130 K), they exhibit some unusual features (a kind of a phase transition), which may either help or hamper their suggested applications in HTS electronics [J. Konopka, I. Wolff, S.J. Lewandowski, J. Appl. Phys. 72 (1992) 218].

  11. New high pressure rare earth tantalates RExTa2O5+1.5x (RE=La, Eu, Yb)

    NASA Astrophysics Data System (ADS)

    Zibrov, Igor P.; Filonenko, Vladimir P.; Zakharov, Nikolai D.; Werner, Peter; Drobot, Dmitrii V.; Nikishina, Elena E.; Lebedeva, Elena N.

    2013-07-01

    Rare earth tantalates La0.075Ta2O5.113, Eu0.089Ta2O5.134 and Yb0.051Ta2O5.077 have been prepared by solid state reaction at P=7.0 GPa and T=1050-1100 °C and studied by X-ray diffraction, thermal analysis and electron microscopy. Low hydrated amorphous tantalum, lanthanum, europium and ytterbium hydroxides were used as starting materials. Aqueous as well as anhydrous compounds were obtained. Title tantalates are crystallized in the structure type of F-Ta2O5 [Zibrov et al. Russ. J. Inorg. Chem. 48 (2003) 464-471] [5]. The structure was refined by the Rietveld method from X-ray powder diffractometer data: La0.075Ta2O5.113, a=10.5099(2), b=7.2679(1), c=6.9765(1) Å, V=532.90(1) Å3, Z=6, space group Ibam; Eu0.089Ta2O5.134, a=10.4182(3), b=7.2685(1), c=6.9832(1) Å, V=528.80(2) Å3, Z=6, space group Ibam; Yb0.051Ta2O5.077, a=10.4557(2), b=7.3853(1), c=6.8923(1) Å, V=532.21(1) Å3, Z=6, space group Ibam. RE atoms do not replace the tantalum in its positions but the only water in the channels of the structure. Highly charged cations RE+3 compress the unit cell so that its volume becomes less than that of F-Ta2O5. Significant decrease of the unit cell volume after water removal from the structure is possible due to the puckering of pentagonal bipyramid layers and change of the corrugation angle in the layer.

  12. Photoluminescence of rare-earth ion (Eu3+, Tm3+, and Er3+)-doped and co-doped ZnNb2O6 for solar cells

    NASA Astrophysics Data System (ADS)

    Gao, Sen-Pei; Qian, Yan-Nan; Wang, Biao

    2015-08-01

    Visible converted emissions produced at an excitation of 286 nm in ZnNb2O6 ceramics doped with rare-earth ions (RE = Eu3+, Tm3+, Er3+ or a combination of these ions) were investigated with the aim of increasing the photovoltaic efficiency of solar cells. The structure of RE:ZnNb2O6 ceramics was confirmed by x-ray diffraction patterns. The undoped ZnNb2O6 could emit a blue emission under 286-nm excitation, which is attributed to the self-trapped excitons’ recombination of the efficient luminescence centers of edge-shared NbO6 groups. Upon 286-nm excitation, Eu:ZnNb2O6, Tm:ZnNb2O6, and Er:ZnNb2O6 ceramics showed blue, green, and red emissions, which correspond to the transitions of 5D0 ? 7FJ (J = 1-4) (Eu3+), 1G4 ? 3H6 (Tm3+), and 2H11/2/4S3/2 ? 4I15/2 (Er3+), respectively. The calculated CIE chromaticity coordinates of Eu:ZnNb2O6, Tm:ZnNb2O6, and Er:ZnNb2O6 are (0.50, 0.31), (0.14, 0.19), and (0.29, 0.56), respectively. RE ion-co-doped ZnNb2O6 showed a combination of characteristic emissions. The chromaticity coordinates of Eu/Tm:ZnNb2O6, Eu/Er:ZnNb2O6, and Tm/Er:ZnNb2O6 were calculated to be (0.29, 0.24), (0.45, 0.37), and (0.17, 0.25). Project supported by the National Natural Science Foundation of China (Grant Nos. 10572155 and 10732100) and the Research Fund for the Doctoral Program of Ministry of Education, China (Grant No. 20130171130003).

  13. Structure, magnetism and transport of the perovskite manganites Ln0.5Ca 0.5MnO 3 ( Ln=Ho, Er, Tm, Yb and Lu)

    NASA Astrophysics Data System (ADS)

    Yoshii, Kenji; Abe, Hideki; Ikeda, Naoshi

    2005-12-01

    It was found that the manganese perovskite oxides Ln0.5Ca0.5MnO3 (Ln=Ho, Er, Tm, Yb and Lu) have an orthorhombic structure (space group Pnma). The Mn-O-Mn angles were calculated to be ?148-150°, revealing an existence of a large crystallographic distortion in these oxides. Electrical resistivity measurements indicated both an insulating nature and a small magnetoresistance effect, both of which are owing to narrow bandwidths of the Mn-3d electrons arising from the crystallographic distortion. DC magnetization measurements showed the three characteristic temperatures, which could be assigned to charge-order, antiferromagnetism of Mn moments, and possible glassy states. All of these temperatures were decreased for the heavier Ln ions, which is explained in connection with both a difference of ionic radii of Ln3+ and Ca2+, and a lowering of electron transfer. The charge-ordering transition was not clearly observed only for Lu0.5Ca0.5MnO3 containing the smallest lanthanide ion, plausibly due to a large randomness of magnetic interactions arising from the ionic radii difference of Lu3+ and Ca2+. In addition, preliminary measurements of AC dielectric response suggested that these manganites belong to a so-called multiferroic system.

  14. Infrared-active optical phonons and magnetic excitations in the hexagonal manganites RMnO3 (R =Ho, Er, Tm, Yb, and Lu)

    NASA Astrophysics Data System (ADS)

    Basistyy, R.; Stanislavchuk, T. N.; Sirenko, A. A.; Litvinchuk, A. P.; Kotelyanskii, M.; Carr, G. L.; Lee, N.; Wang, X.; Cheong, S.-W.

    2014-07-01

    Optical properties of hexagonal multiferroic oxides RMnO3, where R=Ho, Er, Tm, Yb, and Lu, have been studied in the far-infrared spectral range between 100 and 2000 cm-1 and temperatures between 1.5 and 300 K by means of several experimental techniques: Mueller matrix spectroscopic ellipsometry, rotating analyzer ellipsometry, and optical transmission spectroscopy. Spectra of the optical phonons are described in terms of the temperature dependencies of their frequency, damping, and oscillator strength. For all studies, oxide materials' clear signatures of the spin-phonon interaction have been found below the temperature of the antiferromagnetic phase transition TN due to magnetic ordering of Mn3+ spins. A decrease of the ionic radius for R3+ ions between Ho3+ and Lu3+ in the corresponding RMnO3 compounds resulted in systematic variation of the frequency for several optical phonons. A magnetic excitation at ˜190 cm-1 was observed at low temperatures below TN and interpreted as resulting from two-magnon absorption.

  15. Structural and thermoelectric properties of BaRCo{sub 4}O{sub 7} (R = Dy, Ho, Er, Tm, Yb, and Lu)

    SciTech Connect

    Wong-Ng, W.; Yan, Y.; Liu, G.; Xie, W.; Tritt, T.; Kaduk, J.; Thomas, E.

    2011-12-01

    The structure and thermoelectric properties of a series of barium lanthanide cobaltites, BaRCo{sub 4}O{sub 7} (R = Dy, Ho, Er, Tm, Yb, and Lu), which were prepared using the spark plasma synthesis technique, have been investigated. The space group of these compounds was re-determined and confirmed to be P31c instead of the reported P6{sub 3}mc. The lattice parameters a and c range from 6.26279(2) Angst to 6.31181(6) Angst , and from 10.22468(6) Angst to 10.24446(15) Angst for R = Lu to Dy, respectively. The crystal structure of BaRCo{sub 4}O{sub 7} is built up from Kagome sheets of CoO{sub 4} tetrahedra, linked by triangular layers of CoO{sub 4} tetrahedra. The values of figure of merit (ZT) of the BaRCo{sub 4}O{sub 7} samples were determined to be around 0.02 at 800 K. X-ray diffraction patterns of these samples have been determined and submitted to the Powder Diffraction File.

  16. Thermoelectric transport properties of CaMg2Bi2, EuMg2Bi2, and YbMg2Bi2

    SciTech Connect

    May, Andrew F; McGuire, Michael A; Ma, Jie; Delaire, Olivier A; Huq, Ashfia; Singh, David J; Cai, Wei; Wang, Hsin

    2012-01-01

    The thermoelectric transport properties of CaMg{sub 2}Bi{sub 2}, EuMg{sub 2}Bi{sub 2}, and YbMg{sub 2}Bi{sub 2} were characterized between 2 and 650 K. As synthesized, the polycrystalline samples are found to have lower p-type carrier concentrations than single-crystalline samples of the same empirical formula. These low carrier concentration samples possess the highest mobilities yet reported for materials with the CaAl{sub 2}Si{sub 2} structure type, with a mobility of {approx}740 cm{sup 2}/V/s observed in EuMg{sub 2}Bi{sub 2} at 50 K. Despite decreases in the Seebeck coefficient ({alpha}) and electrical resistivity ({rho}) with increasing temperature, the power factor ({alpha}{sup 2}{rho}) increases for all temperatures examined. This behavior suggests a strong asymmetry in the conduction of electrons and holes. The highest figure of merit (zT) is observed in YbMg{sub 2}Bi{sub 2}, with zT approaching 0.4 at 600 K for two samples with carrier densities of approximately 2 x 10{sup 18} cm{sup -3} and 8 x 10{sup 18} cm{sup -3} at room temperature. Refinements of neutron powder diffraction data yield similar behavior for the structures of CaMg{sub 2}Bi{sub 2} and YbMg{sub 2}Bi{sub 2}, with smooth lattice expansion and relative expansion in c being {approx}35% larger than relative expansion in a at 973 K. First-principles calculations reveal an increasing band gap as Bi is replaced by Sb and then As, and subsequent Boltzmann transport calculations predict an increase in {alpha} for a given n associated with an increased effective mass as the gap opens. The magnitude and temperature dependence of {alpha} suggests higher zT is likely to be achieved at larger carrier concentrations, roughly an order of magnitude higher than those in the current polycrystalline samples, which is also expected from the detailed calculations.

  17. Ultraviolet-driven white light generation from oxyfluoride glass co-doped with Tm{sup 3+}-Tb{sup 3+}-Eu{sup 3+}

    SciTech Connect

    Kuznetsov, A. S.; Nikitin, A.; Tikhomirov, V. K.; Shestakov, M. V.; Moshchalkov, V. V.

    2013-04-22

    Tm{sup 3+}-Tb{sup 3+}-Eu{sup 3+} co-doped oxyfluoride glasses, doped with about 3.0 mol. % TmF{sub 3}, 0.25 mol. % TbF{sub 3}, and 0.25 mol. % EuF{sub 3}, have been prepared by melt quenching technique. Under excitation at commercial 365 nm, the rare-earth co-dopants are all directly excited and emit in the blue, green, and red, respectively, without appreciable energy transfer amongst the co-dopants. Tint of the white luminescence can be adjusted by changing the ratio of the co-dopants. Properties of the glass host promote excellent dissolution of the co-dopants and low non-radiative decay rate. The white emission at 365 nm excitation is suitable for light emitting diodes applications.

  18. Up-conversion in sol-gel derived nano-glass-ceramics comprising NaYF 4 nano-crystals doped with Yb 3+, Ho 3+ and Tm 3+

    NASA Astrophysics Data System (ADS)

    Santana-Alonso, A.; Méndez-Ramos, J.; Yanes, A. C.; del-Castillo, J.; Rodríguez, V. D.

    2010-07-01

    NaYF 4 is an excellent host material for rare-earth ions presenting very high efficiencies in up-conversion processes. Thus, nano-glass-ceramics containing NaYF 4 nano-crystals emerge as promising candidates for general lighting appliances and integrated optical devices. Here we report highly transparent sol-gel derived nano-glass-ceramics comprising Yb 3+-Ho 3+ and Yb 3+-Ho 3+-Tm 3+ co-doped NaYF 4 nano-crystals. A structural analysis by means of X-ray diffraction measurements confirmed the formation of NaYF 4 nano-crystals during thermal treatment. Luminescence features have been related to the crystallinity degree of the samples. Violet, blue, green and red up-conversion emissions were obtained under infrared excitation at 980 nm and corresponding mechanisms involved have been analysed. Additionally, the total visible up-conversion emission has been quantified in terms of the standard chromaticity coordinates. In particular, an overall colour emission, very close to the standard equal energy white-light illumination point of the chromaticity diagram, was obtained in the Yb 3+-Ho 3+-Tm 3+ triply-doped samples.

  19. Up-conversion emission tuning in triply-doped Yb3+/Tm3+/Er3+ novel fluoro-phosphate glass and glass-ceramics

    NASA Astrophysics Data System (ADS)

    Ledemi, Yannick; Trudel, Andrée.-Anne; Rivera, Victor A. G.; Messaddeq, Younes

    2014-03-01

    New Yb3+, Er3+ and Tm3+ triply doped fluoro-phosphate glasses belonging to the system NaPO3-YF3-BaF2-CaF2 have been prepared by the classical melt-casting technique. Glasses containing up to 10 wt.% of rare-earth ions fluorides have been obtained and characterized by using differential scanning calorimetry (DSC), UV-visible-near-infrared spectroscopy and up-conversion emission spectroscopy under excitation with a 975 nm laser diode. Transparent and optically homogeneous glass-ceramics have been reproducibly obtained by appropriate heat treatment in view to manage the red, green and blue emissions upon 975 nm laser excitation. According to the applied thermal heat-treatment, a large enhancement of intensity of the up-conversion emission - from 10 to 160 times higher - has been achieved in the glassceramics compared to that of glasses, suggesting incorporation of the rare-earth ions into the crystalline phase. Furthermore, a large range of color rendering has been observed in these materials by controlling the laser excitation power and material crystallization rate. Time-resolved luminescence experiments as well as X-ray diffractometry and scanning electron microscopy techniques have been employed in order to understand and correlate the multicolor emission changes to the crystallization behavior of this material. A progressive phase transformation of the fluorite-type CaF2-based nanocrystals initially generated was observed along with increasing heat-treatment time, thus modifying the rare earth ions spectroscopic features.

  20. Turn-on detection of a cancer marker based on near-infrared luminescence energy transfer from NaYF4:Yb,Tm/NaGdF4 core-shell upconverting nanoparticles to gold nanorods.

    PubMed

    Chen, Hongqi; Guan, Yingying; Wang, Shaozhen; Ji, Yuan; Gong, Mengqi; Wang, Lun

    2014-11-01

    A homogeneous immunoassay for the sensitive and selective determination of trace amounts of ?-fetoprotein (AFP, a cancer marker) by detection in the near-infrared (NIR) region based on luminescence energy transfer (LET) from NaYF4:Yb,Tm/NaGdF4 core-shell upconverting nanoparticles to gold nanorods (GNRs) is presented. The carboxyl-functionalized NaYF4:Yb,Tm/NaGdF4 core-shell upconverting nanoparticles (UCNPs) were excited by a 980 nm continuous wavelength laser, and its emission peak appeared at a near-infrared wavelength (?804 nm). The carboxyl-functionalized upconverting nanoparticles were conjugated with the anti-AFP (Ab1) and acted as donor. GNRs with a high absorption band around 790 nm, which was overlapped the UCNPs emission, were synthesized and acted as the acceptor. The donor (negatively charged) interacted with the acceptor (positively charged) via electrostatic interactions to bring them into close proximity. LET could occur, producing a quenching phenomenon. When the AFP antigens were added into the system, the binding affinity between AFP and Ab1 was stronger than the electrostatic interactions, which released the energy acceptors from the energy donors, interrupting luminescence energy transfer, and therefore, the luminescence was recovered. On the basis of the restored luminescence, a turn-on optical immunosening system was developed. Under the optimal conditions, the linear range of detection was from 0.18 to 11.44 ng/mL for AFP (R = 0.99), with a detection limit as low as 0.16 ng/mL. The proposed method has also been used to monitor AFP in human serum samples. Therefore, further study based on the NaYF4:Yb,Tm/NaGdF4 core-shell nanoparticles-GNRs construction may open the way for a new class of NIR-LET biosensors with wide applications. PMID:25296290

  1. New high pressure rare earth tantalates RE{sub x}Ta{sub 2}O{sub 5+1.5x} (RE=La, Eu, Yb)

    SciTech Connect

    Zibrov, Igor P.; Filonenko, Vladimir P.; Zakharov, Nikolai D.; Nikishina, Elena E.; Lebedeva, Elena N.

    2013-07-15

    Rare earth tantalates La{sub 0.075}Ta{sub 2}O{sub 5.113}, Eu{sub 0.089}Ta{sub 2}O{sub 5.134} and Yb{sub 0.051}Ta{sub 2}O{sub 5.077} have been prepared by solid state reaction at P=7.0 GPa and T=1050–1100 °C and studied by X-ray diffraction, thermal analysis and electron microscopy. Low hydrated amorphous tantalum, lanthanum, europium and ytterbium hydroxides were used as starting materials. Aqueous as well as anhydrous compounds were obtained. Title tantalates are crystallized in the structure type of F–Ta{sub 2}O{sub 5} [Zibrov et al. Russ. J. Inorg. Chem. 48 (2003) 464–471] [5]. The structure was refined by the Rietveld method from X-ray powder diffractometer data: La{sub 0.075}Ta{sub 2}O{sub 5.113}, a=10.5099(2), b=7.2679(1), c=6.9765(1) Å, V=532.90(1) Å{sup 3}, Z=6, space group Ibam; Eu{sub 0.089}Ta{sub 2}O{sub 5.134}, a=10.4182(3), b=7.2685(1), c=6.9832(1) Å, V=528.80(2) Å{sup 3}, Z=6, space group Ibam; Yb{sub 0.051}Ta{sub 2}O{sub 5.077}, a=10.4557(2), b=7.3853(1), c=6.8923(1) Å, V=532.21(1) Å{sup 3}, Z=6, space group Ibam. RE atoms do not replace the tantalum in its positions but the only water in the channels of the structure. Highly charged cations RE{sup +3} compress the unit cell so that its volume becomes less than that of F–Ta{sub 2}O{sub 5}. Significant decrease of the unit cell volume after water removal from the structure is possible due to the puckering of pentagonal bipyramid layers and change of the corrugation angle in the layer. - Graphical abstract: The structure of RE{sub x}Ta{sub 2}O{sub 5+1.5x} and its HRTEM image (“A” arrows show empty channel, “B” arrows show filled channel). - Highlights: • We synthesized new tantalates of RE under high pressure high temperature conditions. • RE atoms replace water molecules in the channels of the structure. • Aqueous as well as anhydrous tantalates were obtained. • Highly charged cations RE{sup +3} compress the unit cell decreasing RE–O distances.

  2. Observation of superconductivity at 30~46 K in A(x)Fe?Se?(A = Li, Na, Ba, Sr, Ca, Yb, and Eu).

    PubMed

    Ying, T P; Chen, X L; Wang, G; Jin, S F; Zhou, T T; Lai, X F; Zhang, H; Wang, W Y

    2012-01-01

    New iron selenide superconductors by intercalating smaller-sized alkali metals (Li, Na) and alkaline earths using high-temperature routes have been pursued ever since the discovery of superconductivity at about 30?K in KFe?Se?, but all have failed so far. Here we demonstrate that a series of superconductors with enhanced T(c) = 30?46?K can be obtained by intercalating metals, Li, Na, Ba, Sr, Ca, Yb, and Eu in between FeSe layers by the ammonothermal method at room temperature. Analysis on their powder X-ray diffraction patterns reveals that all the main phases can be indexed based on body-centered tetragonal lattices with a?3.755-3.831 Å while c?15.99-20.54 Å. Resistivities show the corresponding sharp transitions at 45?K and 39?K for NaFe?Se? and Ba?.?Fe?Se?, respectively, confirming their bulk superconductivity. These findings provide a new starting point for studying the properties of these superconductors and an effective synthetic route for the exploration of new superconductors as well. PMID:22645642

  3. Lattice dynamics of rare-earth titanates with the structure of pyrochlore R 2Ti2O7 ( R = Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu): Ab initio calculation

    NASA Astrophysics Data System (ADS)

    Chernyshev, V. A.; Petrov, V. P.; Nikiforov, A. E.

    2015-05-01

    The ab initio calculation has been performed for the crystal structure and the phonon spectrum of titanates with the structure of pyrochlore R 2Ti2O7 ( R = Gd-Lu). The frequencies and types of fundamental vibrations have been found. For R = Tb, Tm, and Yb, this calculation has been carried out for the first time; furthermore, there is no available information on experimental studies of the phonon spectrum for Tm and Yb. The influence of hydrostatic pressure to 35 GPa on the structure, dynamics, and elastic properties of the Gd2Ti2O7 lattice has been investigated. The dependence of the phonon frequencies on the pressure has been obtained. The calculations have predicted that the relative change in the pyrochlore structure volume during compression at pressures to 35 GPa is well described by the third-order Birch-Murnaghan equation of states. The results of the calculations agree with the available experimental data. It has been shown that the structural, dynamic, and elastic properties of the R 2Ti2O7 crystal lattice can be adequately described in the case where the inner shells of the RE ion up to 4 f are replaced by the pseudopotential.

  4. Spatial distribution of defects and the kinetics of nonequilibrium charge carriers in GaN wurtzite crystals doped with Sm, Eu, Er, Tm, and supplementary Zn impurities

    SciTech Connect

    Mezdrogina, M. M. Krivolapchuk, V. V.; Kozhanova, Yu. V.

    2008-02-15

    By analyzing time-resolved and steady-state photoluminescence spectra, it is established that the spatial distribution of rare-earth ion dopants in wurtzite GaN crystals doped with Sm, Eu, Er, or Tm is governed by the type and concentration of defects in the initial semiconductor matrix as well as by the type of the impurity (its capacity for segregation). Doping with multicharged rare-earth impurities and additionally introduced Zn impurity leads to an intensification of emission. The effect of intensification of emission in the case of n-and p-GaN crystals is considered with the use of the model of isoelectronic traps.

  5. Electric field gradient in bixbyite rare-earth oxides R2O3 (R=Tl, Eu, Lu, Tm) measured by perturbed angular correlation

    NASA Astrophysics Data System (ADS)

    Carbonari, A. W.; Mestnik-Filho, J.; Attili, R. N.; Moralles, M.; Saxena, R. N.

    1999-09-01

    The electric field gradient (EFG) at 111Cd nuclei dilutely substituting the cation site in bixbyite rare-earth oxides Tl2O3, Eu2O3, Lu2O3 and Tm2O3 has been measured using perturbed angular correlation technique. The 111In(EC) 111Cd probe nuclei were introduced into the samples by thermal diffusion. The experimental EFG values are compared with those calculated using the point charge model (PCM). The results are discussed in terms of a correlation between the electric field gradient and cation oxygen bond length in metal oxides.

  6. Photoluminescence properties of rare earths (Eu{sup 3+}, Tb{sup 3+}, Dy{sup 3+} and Tm{sup 3+}) activated NaInW{sub 2}O{sub 8} wolframite host lattice

    SciTech Connect

    Asiri Naidu, S.; Boudin, S.; Varadaraju, U.V.; Raveau, B.

    2012-01-15

    The photoluminescence (PL) studies on NaIn{sub 1-x}RE{sub x}W{sub 2}O{sub 8}, with RE=Eu{sup 3+}, Tb{sup 3+}, Dy{sup 3+} and Tm{sup 3+} phases have shown that the relative contribution of the host lattice and of the intra-f-f emission of the activators to the PL varies with the nature of the rare earth cation. In the case of Dy{sup 3+} and Tm{sup 3+} activators, with yellow and blue emission, respectively, the energy transfer from host to the activator plays a major role. In contrast for Eu{sup 3+}, with intense red emission, the host absorption is less pronounced and the intra-f-f transitions of the Eu{sup 3+} ions play a major role, whereas for Tb{sup 3+} intra-f-f transitions are only observed, giving rise to green emission. - Graphical abstract: NaInW{sub 2}O{sub 8} double tungstate doped with Eu{sup 3+}, Dy{sup 3+}, Tb{sup 3+}and Tm{sup 3+} shows characteristic emission of intense red for Eu{sup 3+}, yellow for Dy{sup 3+}, green for Tb{sup 3+} and blue for Tm{sup 3+}. Highlights: Black-Right-Pointing-Pointer Characteristic emissions of rare earths (Eu{sup 3+}, Tb{sup 3+}, Dy{sup 3+} and Tm{sup 3+}) are observed NaInW{sub 2}O{sub 8} wolframite. Black-Right-Pointing-Pointer Energy transfer from host to the activators (Eu{sup 3+} Dy{sup 3+} Tm{sup 3+} is observed. Black-Right-Pointing-Pointer PL properties of rare earth ions depend on minor structural variations in the host lattice.

  7. Highly uniform and monodisperse GdOF:Ln3+ (Ln = Eu, Tb, Tm, Dy, Ho, Sm) microspheres: hydrothermal synthesis and tunable-luminescence properties.

    PubMed

    Zhang, Yang; Kang, Xiaojiao; Geng, Dongling; Shang, Mengmeng; Wu, Yuan; Li, Xuejiao; Lian, Hongzhou; Cheng, Ziyong; Lin, Jun

    2013-10-21

    GdOF:Ln(3+) (Ln = Eu, Tb, Tm, Dy, Ho and Sm) microspheres (1.5 ?m) with high uniformity and monodispersity have been synthesized via a facile hydrothermal method followed by heat treatment (600 °C). X-Ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), as well as photoluminescence (PL) and cathodoluminescence (CL) spectra are used to characterize the resulting samples. A series of controlled experiments indicate that sodium citrate (Cit(3-)) as a shape modifier introduced into the reaction system plays a critical role in the shape evolution of the final products. Furthermore, the shape and size of the products can be further manipulated by adjusting the dosage of Cit(3-) and pH values in the initial solution. The possible formation mechanism for these microspheres has been presented. Under UV light and low-voltage electron beam excitation, GdOF:Ln(3+) microspheres show the characteristic f-f transitions of Ln(3+) (Eu, Tb/Ho, Tm, Dy and Sm) ions and give bright red, green, blue, yellow and yellowish-orange emission, respectively. In addition, multicolored luminescence containing white emission have been successfully confected for co-doped GdOF:Ln(3+) phosphors by changing the doped Ln(3+) ions and adjusting their doping concentrations due to the simultaneous luminescence of Ln(3+) in the GdOF host, making these materials have potential applications in field-emission display devices. PMID:23942823

  8. EPR study of the ground state of Mn2+ impurity ions in alumoborates MAl3(BO3)4 (M = Y, Eu, Tm)

    NASA Astrophysics Data System (ADS)

    Prokhorov, ? ?; Prokhorov, A. D.; Chernush, L. F.; Dyakonov, V. P.; Szymczak, H.; Dejneka, A.

    2015-06-01

    New data about the ground state of the Mn2+ impurity ions in a series of single crystals of alumbrados MAl3(BO3)4, where M = Y,Eu,Tm were obtained. The electron paramagnetic resonance (EPR) spectra of the Mn2+ spectra were studied, the parameters of the spin Hamiltonian describing the angular dependence of the spectrum were defined. It was shown that Mn2+ ions substitute trivalent ions of rare earth metals without changing the symmetry of the substitution site. The charge compensation process was found to be a nonlocal one. The cooling of the crystals leads to the increase of the splitting of the ground state, which is associated with the anisotropy of the thermal expansion coefficient. It was shown that an application of the superposition model to explain the distortions induced by an impurity Mn2+ ion has some limitations. The EPR linewidth of the Mn2+ ion in the TmAl3(BO3)4 crystal increases with increasing temperature as a result of the dipole-dipole and exchange interactions with the excited states of the host lattice Tm3+ ion.

  9. Crystal structures of RPt{sub 3-x}Si{sub 1-y}(R=Y, Tb, Dy, Ho, Er, Tm, Yb) studied by single crystal X-ray diffraction

    SciTech Connect

    Gribanov, Alexander; Grytsiv, Andriy; Rogl, Peter; Seropegin, Yurii; Giester, Gerald

    2009-07-15

    The crystal structures of ternary compounds RPt{sub 3-x}Si{sub 1-y}(R=Y, Tb, Dy, Ho, Er, Tm, Yb) have been elucidated from X-ray single crystal CCD data. All compounds are isotypic and crystallize in the tetragonal space group P4/mbm. The general formula RPt{sub 3-x}Si{sub 1-y} arises from defects: x{approx}0.20, y{approx}0.14. The crystal structure of RPt{sub 3-x}Si{sub 1-y} can be considered as a packing of four types of building blocks which derive from the CePt{sub 3}B-type unit cell by various degrees of distortion and Pt, Si-defects. - Graphical Abstract: Electron density in RPt{sub 3-x}Si{sub 1-y} at 0, 1/2 , 0.

  10. High-throughput and microwave investigation of rare earth phosphonatoethanesulfonates-Ln(O{sub 3}P-C{sub 2}H{sub 4}-SO{sub 3}) (Ln=Ho, Er, Tm, Yb, Lu, Y)

    SciTech Connect

    Sonnauer, Andreas

    2008-11-15

    Following the strategy of using bifunctional phosphonic acids for the synthesis of new metal phosphonates, the flexible ligand 2-phosphonoethanesulfonic acid, H{sub 2}O{sub 3}P-C{sub 2}H{sub 4}-SO{sub 3}H (H{sub 3}L), was used in a high-throughput (HT) and microwave investigation of rare earth phosphonatoethanesulfonates. The HT-investigation led to six isotypic compounds Ln(O{sub 3}P-C{sub 2}H{sub 4}-SO{sub 3}) with Ln=Ho (1), Er (2), Tm (3), Yb (4), Lu (5) and Y (6). The syntheses were scaled-up in glass reactor tubes in order to obtain larger amounts for a detailed characterization. Based on these results all compounds could be also synthesized by microwave-assisted heating and the influence of reaction time and stirring rate during the synthesis was established. For compound 2 the crystal structure was determined by single-crystal X-ray diffraction. The compounds contain isolated slightly distorted LnO{sub 6} octahedra that are connected by the phosphonate and sulfonate groups into a three-dimensional framework. Thermogravimetric investigations demonstrate the high thermal stability of the compounds up to 460 deg. C. - Graphical abstract: A high-throughput and microwave investigation of the System LnX{sub 3}/H{sub 2}O{sub 3}P-C{sub 2}H{sub 4}-SO{sub 3}/NaOH/H{sub 2}O led to six new compounds Ln(O{sub 3}P-C{sub 2}H{sub 4}-SO{sub 3}) with Ln=Ho, Er, Tm, Yb, Lu, Y.

  11. Wideband saturable absorption in few-layer molybdenum diselenide (MoSe2) for Q-switching Yb-, Er- and Tm-doped fiber lasers

    E-print Network

    Woodward, R. I.; Howe, R. C. T.; Runcorn, T. H.; Hu, G.; Torrisi, F.; Kelleher, E. J. R.; Hasan, T.

    2015-06-23

    We fabricate a free-standing molybdenum diselenide (MoSe2) saturable absorber by embedding liquid-phase exfoliated few-layer MoSe2 flakes into a polymer film. The MoSe2-polymer composite is used to Q-switch fiber lasers based on ytterbium (Yb...

  12. Up/down conversion luminescence and charge compensation investigation of Ca0.5Y1-x(WO4)2:xLn3+ (Ln = Pr, Sm, Eu, Tb, Dy, Yb/Er) phosphors

    NASA Astrophysics Data System (ADS)

    Mahalingam, Venkatakrishnan; Thirumalai, Jagannathan; Krishnan, Rajagopalan; Mantha, Srinivas

    2016-01-01

    Microstructures of Ca0.5Y(1-x)(WO4)2:xLn3+ (Ln = Pr, Sm, Eu, Tb, Dy, Yb/Er) phosphors were prepared via the solid-state reaction method. X-ray diffraction, scanning electron microscopy and photoluminescence were used to characterize the prepared phosphor samples. The results reveal that the phosphor samples have single phase scheelite structures with tetragonal symmetry of I41/a. The down/up conversion photoluminescence of the Ca0.5Y(1-x)(WO4)2:xLn3+ (Ln = Pr, Sm, Eu, Tb, Dy, Yb/Er) phosphors properties reveal characteristic visible emissions. The energy transfer process, fluorescence lifetime and color coordinates are discussed in detail. Furthermore, the phosphor Ca0.5Y(1-x)(WO4)2:xPr3+ co-doped with alkali chlorides shows the enhancement of luminescence, which was found in the sodium chloride co-doped powder phosphor. The photometric characteristics indicate the suitability of the inorganic powder phosphors for solid-state lighting and display applications.

  13. Up/down conversion luminescence and charge compensation investigation of Ca0.5Y1-x(WO4)2:xLn(3+) (Ln=Pr, Sm, Eu, Tb, Dy, Yb/Er) phosphors.

    PubMed

    Mahalingam, Venkatakrishnan; Thirumalai, Jagannathan; Krishnan, Rajagopalan; Mantha, Srinivas

    2016-01-01

    Microstructures of Ca0.5Y(1-x)(WO4)2:xLn(3+) (Ln=Pr, Sm, Eu, Tb, Dy, Yb/Er) phosphors were prepared via the solid-state reaction method. X-ray diffraction, scanning electron microscopy and photoluminescence were used to characterize the prepared phosphor samples. The results reveal that the phosphor samples have single phase scheelite structures with tetragonal symmetry of I41/a. The down/up conversion photoluminescence of the Ca0.5Y(1-x)(WO4)2:xLn(3+) (Ln=Pr, Sm, Eu, Tb, Dy, Yb/Er) phosphors properties reveal characteristic visible emissions. The energy transfer process, fluorescence lifetime and color coordinates are discussed in detail. Furthermore, the phosphor Ca0.5Y(1-x)(WO4)2:xPr(3+) co-doped with alkali chlorides shows the enhancement of luminescence, which was found in the sodium chloride co-doped powder phosphor. The photometric characteristics indicate the suitability of the inorganic powder phosphors for solid-state lighting and display applications. PMID:26208272

  14. NaYF4:Yb,Tm nanocrystals and TiO2 inverse opal composite films: a novel device for upconversion enhancement and solid-based sensing of avidin

    NASA Astrophysics Data System (ADS)

    Xu, Sai; Xu, Wen; Wang, Yunfeng; Zhang, Shuang; Zhu, Yongsheng; Tao, Li; Xia, Lei; Zhou, Pingwei; Song, Hongwei

    2014-05-01

    Upconversion luminescence (UCL) detection based on rare-earth doped upconversion nanocrystals (UCNCs) as probes has been proved to exhibit a large anti-Stokes shift, no autofluorescence from biological samples, and no photobleaching. However, it is still a challenge to achieve a stable, reproducible solid-based UCL biosensor because of ineffective UCL of the UCNCs. In this work, we fabricated TiO2 inverse opal photonic crystals (IOPCs)/NaYF4:Yb3+,Tm3+ (Er3+) UCNC composite films, which can tremendously improve the overall UCL of Tm3+ as high as 43-fold. Based on the fluorescence resonance energy transfer (FRET) and the specific interaction between biotin and avidin, a novel solid-based UC biosensor is presented for sensing avidin. This solid-based detection system is convenient for detection, and also can offer two parameters for detecting trace amounts of avidin, namely, the emission intensity and the fluorescence decay time. The sensor has a high sensitivity of 34 pmol-1, a good linear relationship of 0.996 and a low detection limit of 48 pmol. It also exhibits excellent long-time photostability, and the absence of autofluorescence, and thus may have great potential for versatile applications in biodetection.

  15. Ag{sub 2}O dependent up-conversion luminescence properties in Tm{sup 3+}/Er{sup 3+}/Yb{sup 3+} co-doped oxyfluorogermanate glasses

    SciTech Connect

    Hu, Yuebo; Qiu, Jianbei Song, Zhiguo; Zhou, Dacheng

    2014-02-28

    Up-conversion (UC) luminescence properties of Ag/Tm{sup 3+}/Er{sup 3+}/Yb{sup 3+} co-doped oxyfluorogermanate glasses have been studied to assess the effective role of silver nanoparticles as a sensitizer for Tm{sup 3+} and Er{sup 3+} ions. The X-ray diffraction patterns obtained in this work do not reveal any crystalline phase in the glass. However, the absorption spectra reveal that surface plasmons resonance band of Ag undergoes a distinct split with two maxima and a very broad absorption peak with a background that extends toward the near infrared (NIR) with the increasing of Ag{sub 2}O added concentration. Transmission electron microscope images confirm that silver nanoparticles have been precipitated from matrix glasses and show their distribution, size, and shapes. In addition, changes in UC luminescence intensity of four emission bands 476, 524, 546, and 658?nm corresponding to {sup 1}G{sub 4} ? {sup 3}H{sub 6} (Tm{sup 3+}), ({sup 2}H{sub 11/2}, {sup 4}S{sub 3/2}) ? {sup 4}I{sub 15/2} (Er{sup 3+}), and {sup 4}F{sub 9/2} ? {sup 4}I{sub 15/2} (Er{sup 3+}) transitions, respectively, as a function of silver addition to the base composition have been measured under 980?nm excitation. It is confirmed that Ag{sub 2}O added concentration plays an important role in increasing the UC luminescence intensity; however, further increase in Ag{sub 2}O added concentration reduces the intensity.

  16. Enhanced dual contrast agent, Co(2+)-doped NaYF4:Yb(3+),Tm(3+) nanorods, for near infrared-to-near infrared upconversion luminescence and magnetic resonance imaging.

    PubMed

    Xia, Ao; Zhang, Xiaofeng; Zhang, Jun; Deng, Yunyun; Chen, Qiang; Wu, Shishan; Huang, Xiaohua; Shen, Jian

    2014-11-01

    Dual-modality imaging with magnetic resonance (MR) and upconversion luminescence (UCL) is a promising technique for molecular imaging in biomedical research. Multifunctional lanthanide-based nanoparticles have been widely investigated as agents for contrast enhanced MR and fluorescence imaging. However, the use of rare earth fluoride nanoparticles for dual-modality imaging of T2-weighted MR and UCL is rarely reported. We find that NaYF4:Yb(3+),Tm(3+),Co(2+) (MUC) nanorods can be applied as a high-performance dual contrast agent for both T2-weighted MR and UCL dual-modality imaging. After modification with 6-O-carboxymethyl chitosan (OCC), MUC nanorods can be endocytosed by cells without showing signs of cytotoxicity. High-quality UCL images of living cells incubated with MUC-OCC nanorods were acquired on a near-infrared (NIR) confocal microscopy under the excitation at 980 nm. Moreover, MUC-OCC nanorods display high transverse (r2) relaxivities in vitro. The application of low-dose MUC-OCC nanorods for NIR-to-NIR UCL and MR dual-modality in vivo imaging was also carried out successfully. In addition, the toxicity of MUC-OCC nanorods was evaluated by MTT assay, serological tests and histological analysis of visceral organs. PMID:25108318

  17. Synthesis, Characterization, and Application in HeLa Cells of an NIR Light Responsive Doxorubicin Delivery System Based on NaYF4:Yb,Tm@SiO2-PEG Nanoparticles.

    PubMed

    Alonso-Cristobal, Paulino; Oton-Fernandez, Olalla; Mendez-Gonzalez, Diego; Díaz, J Fernando; Lopez-Cabarcos, Enrique; Barasoain, Isabel; Rubio-Retama, Jorge

    2015-07-15

    Herein, we present a phototriggered drug delivery system based on light responsive nanoparticles, which is able to release doxorubicin upon NIR light illumination. The proposed system is based on upconversion fluorescence nanoparticles of ?-NaYF4:Yb,Tm@SiO2-PEG with a mean diameter of 52±2.5 nm that absorb the NIR light and emit UV light. The UV radiation causes the degradation of photodegradable ortho-nitrobenzyl alcohol derivates, which are attached on one side to the surface of the nanoparticles and on the other to doxorubicin. This degradation triggers the doxorubicin release. This drug delivery system has been tested "in vitro" with HeLa cells. The results of this study demonstrated that this system caused negligible cytotoxicity when they were not illuminated with NIR light. In contrast, under NIR light illumination, the HeLa cell viability was conspicuously reduced. These results demonstrated the suitability of the proposed system to control the release of doxorubicin via an external NIR light stimulus. PMID:26094748

  18. Structure determination of KScS?, RbScS? and KLnS? (Ln = Nd, Sm, Tb, Dy, Ho, Er, Tm and Yb) and crystal-chemical discussion.

    PubMed

    Havlák, Lubomír; Fábry, Jan; Henriques, Margarida; Dušek, Michal

    2015-07-01

    The title structures of KScS2 (potassium scandium sulfide), RbScS2 (rubidium scandium sulfide) and KLnS2 [Ln = Nd (potassium neodymium sufide), Sm (potassium samarium sulfide), Tb (potassium terbium sulfide), Dy (potassium dysprosium sulfide), Ho (potassium holmium sulfide), Er (potassium erbium sulfide), Tm (potassium thulium sulfide) and Yb (potassium ytterbium sulfide)] are either newly determined (KScS2, RbScS2 and KTbS2) or redetermined. All of them belong to the ?-NaFeO2 structure type in agreement with the ratio of the ionic radii r(3+)/r(+). KScS2, the member of this structural family with the smallest trivalent cation, is an extreme representative of these structures with rare earth trivalent cations. The title structures are compared with isostructural alkali rare earth sulfides in plots showing the dependence of several relevant parameters on the trivalent cation crystal radius; the parameters thus compared are c, a and c/a, the thicknesses of the S-S layers which contain the respective constituent cations, the sulfur fractional coordinates z(S(2-)) and the bond-valence sums. PMID:26146403

  19. (?-NaYbF4:Tm3+)/CaF2 Core/Shell Nanoparticles with Efficient Near-Infrared to Near-Infrared Upconversion for High-Contrast Deep Tissue Bioimaging

    PubMed Central

    Chen, Guanying; Shen, Jie; Ohulchanskyy, Tymish Y.; Patel, Nayan J.; Kutikov, Artem; Li, Zhipeng; Song, Jie; Pandey, Ravindra K.; Ågren, Hans; Prasad, Paras N.; Han, Gang

    2012-01-01

    We describe the development of novel and biocompatible core/shell (?-NaYbF4:Tm3+)/CaF2 nanoparticles which exhibit highly efficient NIRin-NIRout upconversion (UC) for high contrast and deep bioimaging. When excited at ~980 nm, these nanoparticles emit photoluminescence (PL) peaked at ~800 nm. The quantum yield of this UC PL under low power density excitation (~0.3 W/cm2) is 0.6±0.1%. This high UC PL efficiency is realized by suppressing surface quenching effects via hetero-epitaxial growth of a biocompatible CaF2 shell which results in a 35-fold increase in the intensity of UC PL from the core. Small animal whole-body UC PL imaging with exceptional contrast (signal-to-background ratio of 310) is shown using BALB/c mice intravenously injected with aqueously dispersed nanoparticles (700 pmol/kg). High-contrast UC PL imaging of deep tissues is also demonstrated, using a nanoparticle-loaded synthetic fibrous mesh wrapped around rat femoral bone, and a cuvette with nanoparticle aqueous dispersion - covered with a 3.2-cm thick animal tissue (pork). PMID:22928629

  20. Structure, magnetism and transport of the perovskite manganites Ln {sub 0.5}Ca{sub 0.5}MnO{sub 3} (Ln=Ho, Er, Tm, Yb and Lu)

    SciTech Connect

    Yoshii, Kenji . E-mail: yoshiike@spring8.or.jp; Abe, Hideki; Ikeda, Naoshi

    2005-12-15

    It was found that the manganese perovskite oxides Ln {sub 0.5}Ca{sub 0.5}MnO{sub 3} (Ln=Ho, Er, Tm, Yb and Lu) have an orthorhombic structure (space group Pnma). The Mn-O-Mn angles were calculated to be {approx}148-150{sup o}, revealing an existence of a large crystallographic distortion in these oxides. Electrical resistivity measurements indicated both an insulating nature and a small magnetoresistance effect, both of which are owing to narrow bandwidths of the Mn-3d electrons arising from the crystallographic distortion. DC magnetization measurements showed the three characteristic temperatures, which could be assigned to charge-order, antiferromagnetism of Mn moments, and possible glassy states. All of these temperatures were decreased for the heavier Ln ions, which is explained in connection with both a difference of ionic radii of Ln {sup 3+} and Ca{sup 2+}, and a lowering of electron transfer. The charge-ordering transition was not clearly observed only for Lu{sub 0.5}Ca{sub 0.5}MnO{sub 3} containing the smallest lanthanide ion, plausibly due to a large randomness of magnetic interactions arising from the ionic radii difference of Lu{sup 3+} and Ca{sup 2+}. In addition, preliminary measurements of AC dielectric response suggested that these manganites belong to a so-called multiferroic system.

  1. Preparation and spectroscopic properties of rare-earth (RE) (RE = Sm, Eu, Tb, Dy, Tm)-activated K{sub 2}LnZr(PO{sub 4}){sub 3} (Ln = Y, La, Gd and Lu) phosphate in vacuum ultraviolet region

    SciTech Connect

    Zhang, Zhi-Jun; Lin, Xiao; Graduate School of Chinese Academy of Science, Beijing, 100039 ; Zhao, Jing-Tai; Zhang, Guo-Bin

    2013-02-15

    Graphical abstract: Display Omitted Highlights: ? We report the VUV spectroscopic properties of rare-earth ions in K{sub 2}LnZr(PO{sub 4}){sub 3}. ? The O{sup 2?}-Eu{sup 3+} charge transfer bands at about 220 nm have been observed. ? The 4f–5d spin-allowed and spin-forbidden transitions of Tb{sup 3+} have been observed. ? There is energy transfer between the host and rare-earth activators. -- Abstract: Rare earth (RE = Sm, Eu, Tb, Dy and Tm)-activated K{sub 2}LnZr(PO{sub 4}){sub 3} (Ln = Y, La, Gd and Lu) have been synthesized by solid-state reaction method, and their vacuum ultraviolet (VUV) excitation luminescent characteristics have been investigated. The band in the wavelength range of 130–157 nm and the other one range from 155 to 216 nm with the maximum at about 187 nm in the VUV excitation spectra of these compounds are attributed to the host lattice absorption and O–Zr charge transfer transition, respectively. The charge transfer bands (CTB) of O{sup 2?}-Sm{sup 3+}, O{sup 2?}-Dy{sup 3+} and O{sup 2?}-Tm{sup 3+}, in Sm{sup 3+}, Dy{sup 3+} and Tm{sup 3+}-activated samples, have not been obviously observed probably because the 2p electrons of oxygen are tightly bound to the zirconium ion in the host lattice. For Eu{sup 3+}-activated samples, the relatively weak O{sup 2?}-Eu{sup 3+} CTB at about 220 nm is observed. And for Tb{sup 3+}-activated samples, the bands at 223 and 258 nm are related to the 4f-5d spin-allowed and spin-forbidden transitions of Tb{sup 3+}, respectively. It is observed that there is energy transfer between the host lattice and the luminescent activators (e.g. Eu{sup 3+}, Tb{sup 3+}). From the standpoint of luminescent efficiency, color purity and chemical stability, K{sub 2}GdZr(PO{sub 4}){sub 3}:Sm{sup 3+}, Eu{sup 3+}, Tb{sup 3+} are attractive candidates for novel yellow, red, green-emitting PDP phosphors.

  2. Multitemperature crystal structures and physical properties of the partially filled thermoelectric skutterudites M0.1Co4Sb12(M=La,Ce,Nd,Sm,Yb,andEu)

    NASA Astrophysics Data System (ADS)

    Mi, Jian-Li; Christensen, Mogens; Nishibori, Eiji; Iversen, Bo Brummerstedt

    2011-08-01

    Partially filled skutterudites with nominal compositions of M0.1Co4Sb12 (M = La, Ce, Nd, Sm, Yb; and Eu) were investigated by multitemperature (90-700 K) synchrotron radiation powder x-ray diffraction (SR-PXRD), and electrical and thermal transport property, heat capacity, and Hall effect measurements were also taken. The filling fractions, i.e., the occupancy factors of the guest atoms, were obtained from structure refinement of the SR-PXRD data, and they reflect the capacity for the individual guest atom species to fill the voids of the CoSb3 structure. The filling fraction of the lanthanide guest ions correlates with their effective ionic radii and valences, and the larger the ionic radii or the lower the charge state, the larger is the occupancy. Due to the different guest atom occupancies, the doping levels vary among the samples, and they are in a good agreement with the measured charge carrier concentrations, except for the magnetic samples (Sm, Eu). Anomalously large atomic displacement parameters (ADPs) are observed for the weakly bonded guest atoms, in agreement with the “rattling” concept, but no correlation is observed between the magnitude of the ADP and the ionic radius of the guest atom. Einstein and Debye temperatures were derived from analysis of the multitemperature ADPs of guest atoms and the framework atoms, respectively, and this analysis also shows that neither the guest atoms nor the host structure atoms contain large disorder contributions to their ADPs. In ternary skutterudites without host structure substitution or disorder, partial guest filling can affect the lattice thermal conductivity (?L) either by direct phonon-phonon interaction or through the inherent structural disorder introduced with the partial occupancy of the voids. The present data suggest that the magnitude of the guest atom ADPs correlates with ?L, and the larger the ADP, the lower is the ?L.

  3. Two new ternary lanthanide antimony chalcogenides: Yb{sub 4}Sb{sub 2}S{sub 11.25} and Tm{sub 4}Sb{sub 2}Se{sub 11.68} containing chalcogenide Q{sup 2-} and dichalcogenide (Q{sub 2}){sup 2-} anions

    SciTech Connect

    Babo, Jean-Marie; Albrecht-Schmitt, Thomas E.

    2012-03-15

    Dark red and dark brown crystals of Yb{sub 4}Sb{sub 2}S{sub 11.25} and Tm{sub 8}Sb{sub 4}Se{sub 11.68}, respectively, were obtained from the reaction of the elements in Sb{sub 2}Q{sub 3} (Q=S, Se) fluxes. Both non-stoichiometric compounds are orthorhombic and crystallize in the same space group Pnnm, with two formula units per unit cell (a=12.446(2), b=5.341(1), c=12.058(2) for sulfide and a=13.126(2), b=5.623(1), c=12.499(2) for the selenide). Their crystal structures are dominated by lanthanide-chalcogenide polyhedra (CN=7 and 8), which share corners, edges, triangular- and square-faces to form a three-dimensional framework embedding antinomy cations. The latter are coordinated by three sulfide anions with 5(1+2+2) secondary contacts forming basically infinite chains running along [0 1 0]. The chalcogens in both compounds form chalcogenide Q{sup 2-} and dichalcogenide (Q{sub 2}){sup 2-} anionic units. The optical analysis made on those compounds shows that both are semiconductors with band gap of 1.71 and 1.22 eV for Yb{sub 4}Sb{sub 2}S{sub 11.25} and Tm{sub 4}Sb{sub 2}Se{sub 11.75,} respectively. - Graphical Abstract: The crystal structure of Yb{sub 4}Sb{sub 2}S{sub 11} viewed along the [0 1 0]. Highlights: Black-Right-Pointing-Pointer Lanthanide chalcogenides. Black-Right-Pointing-Pointer Semiconductors. Black-Right-Pointing-Pointer Tunnel structures. Black-Right-Pointing-Pointer Lone-pair effects.

  4. Terpyridine-based heteroditopic ligand for Ru(II)Ln3(III) metallostar architectures (Ln = Gd, Eu, Nd, Yb) with MRI/optical or dual-optical responses.

    PubMed

    Boulay, Alexandre; Deraeve, Céline; Vander Elst, Luce; Leygue, Nadine; Maury, Olivier; Laurent, Sophie; Muller, Robert N; Mestre-Voegtlé, Béatrice; Picard, Claude

    2015-02-16

    A new ditopic ligand (L) based on a 2,2':5',4?-terpyridine unit substituted in the 2?,6? positions with iminodiacetate arms has been designed and synthesized for the construction of Ru(II)L3Ln3(III) supramolecular architectures. The two components of this system, a 2,2'-bipyridine unit for Ru(II) coordination and a pyridine-bis(iminodiacetate) core for Ln(III) coordination, are tightly connected via a covalent Carom(py)-Carom(py) bond. The paramagnetic and photophysical properties of the corresponding tetrametallic Ru(II)L3Gd3(III) complex have been evaluated, highlighting the potential of this metallostar structure to act as a bimodal MRI/optical imaging agent. Variable-temperature (17)O NMR and proton nuclear magnetic relaxation dispersion (NMRD) measurements showed that this complex exhibits (i) a remarkable relaxivity per metallostar molecule, particularly at clinical and high magnetic fields (r1(310K) = 51.0 and 36.0 mM(-1) s(-1) at 20 and 300 MHz, respectively) and (ii) a near-optimal residence lifetime of Gd(III) coordinated water molecule (?M(310K) = 77.5 ns). This is the result of the presence of two inner-sphere water molecules in the Gd(III) components of the metallostar and a slow tumbling rate of the molecule (?R(310K) = 252 ps). Upon excitation in the visible domain (?exc = 472 nm), the Ru(II) component of the complex exhibits a bright-red luminescence centered at 660 nm with a quantum yield of 2.6% in aqueous solutions at pH 7.4. Moreover, this Ru(II)L3Gd3(III) assembly is also characterized by a high kinetic inertness in biological media (PBS and human serum solutions) and a high photostability (photobleaching). Finally, preliminary photophysical studies on RuL3Nd3 and RuL3Yb3 assemblies revealed that the Ru(II) center acts as an effective sensitizer for Ln(III)-based luminescence in the near-IR region. The Nd(III) species was found to be the most effective at quenching the (3)MLCT luminescence of the Ru center. PMID:25594876

  5. Elastic anomalies of YbIrGe in magnetic fields

    NASA Astrophysics Data System (ADS)

    Suzuki, T.; Noguchi, Y.; Ishii, I.; Goto, H.; Kamikawa, S.; Fujita, T. K.; Katoh, K.

    2015-03-01

    The Yb-based heavy-fermion compound YbIrGe, which has the orthorhombic structure, shows the crystal electric field effect at high temperatures and antiferromagnetic orderings at TN = 2.4 K and Tm = 1.4 K. We previously found anomalous elastic softening in zero magnetic field originating from an indirect quadrupole interaction between the ground doublet and the excited doublets, and determined the crystal electric field level scheme: the ground doublet and an excited doublet at 138 K. To investigate the antiferromagnetic orderings at TN and Tm, we performed ultrasonic measurements under magnetic fields along the a-axis on YbIrGe single crystals. Temperature dependence of elastic modulus C11 exhibits elastic hardening below both TN and Tm at 0 T. As increasing the magnetic field along the a-axis, both TN and Tm decrease monotonically, suggesting that both transitions are antiferromagnetic ordering. TN closes around 2 T, and Tm disappears above 1 T. We clarified the magnetic field- temperature phase diagram along the a-axis.

  6. Resonant photo-ionization of Yb+ to Yb2+

    E-print Network

    Simon Heugel; Martin Fischer; Vladimir Elman; Robert Maiwald; Markus Sondermann; Gerd Leuchs

    2015-12-07

    We demonstrate the controlled creation of a $\\mathrm{^{174}Yb^{2+}}$ ion by photo-ionizing $\\mathrm{^{174}Yb^+}$ with weak continuous-wave lasers at ultraviolet wavelengths. The photo-ionization is performed by resonantly exciting transitions of the $\\mathrm{^{174}Yb^+}$ ion in three steps. Starting from an ion crystal of two laser-cooled $\\mathrm{^{174}Yb^+}$ ions localized in a radio-frequency trap, the verification of the ionization process is performed by characterizing the properties of the resulting mixed-species ion-crystal. The obtained results facilitate fundamental studies of physics involving $\\mathrm{Yb^{2+}}$ ions.

  7. Triaxial strongly deformed bands in {sup 160,161}Tm

    SciTech Connect

    Teal, C.; Lagergren, K.; Aguilar, A.; Riley, M. A.; Hartley, D. J.; Simpson, J.; Joss, D. T.; Carpenter, M. P.; Janssens, R. V. F.; Lauritsen, T.; Lister, C. J.; Zhu, S.; Garg, U.; Kondev, F. G.; Wang, X.; Ragnarsson, I.

    2008-07-15

    High-spin states in {sup 160,161}Tm were populated using the {sup 128}Te({sup 37}Cl, 5n and 4n) reactions at a beam energy of 170 MeV. Emitted {gamma} rays were detected in the Gammasphere spectrometer. Two rotational bands with high moments of inertia were discovered, one assigned to {sup 160}Tm, while the other tentatively assigned to {sup 161}Tm. These sequences display features similar to bands observed in neighboring Er, Tm, Yb, and Lu nuclei which have been discussed in terms of triaxial strongly deformed structures. Cranked Nilsson Strutinsky calculations have been performed that predict well-deformed triaxial shapes at high spin in {sup 160,161}Tm.

  8. tmRDB (tmRNA database).

    PubMed

    Knudsen, B; Wower, J; Zwieb, C; Gorodkin, J

    2001-01-01

    The tmRNA database (tmRDB) is maintained at the University of Texas Health Science Center at Tyler, Texas, and accessible on the World Wide Web at the URL http://psyche.uthct.edu/dbs/tmRDB/tmRDB.++ +html. Mirror sites are located at Auburn University, Auburn, Alabama (http://www.ag.auburn.edu/mirror/tmRDB/) and the Institute of Biological Sciences, Aarhus, Denmark (http://www.bioinf.au. dk/tmRDB/). The tmRDB provides information and citation links about tmRNA, a molecule that combines functions of tRNA and mRNA in trans-translation. tmRNA is likely to be present in all bacteria and has been found in algae chloroplasts, the cyanelle of Cyanophora paradoxa and the mitochondrion of the flagellate Reclinomonas americana. This release adds 26 new sequences and corresponding predicted tmRNA-encoded tag peptides for a total of 86 tmRNAs, ordered alphabetically and phylogenetically. Secondary structures and three-dimensional models in PDB format for representative molecules are being made available. tmRNA alignments prove individual base pairs and are generated manually assisted by computational tools. The alignments with their corresponding structural annotation can be obtained in various formats, including a new column format designed to improve and simplify computational usability of the data. PMID:11125081

  9. Continuous wave diode pumped Yb:LLF and Yb:NYF lasers

    NASA Astrophysics Data System (ADS)

    Yasukevich, A. S.; Kisel, V. E.; Kurilchik, S. V.; Grigoriev, S. V.; Kuleshov, N. V.; Gordeev, E. Yu.; Korableva, S. L.; Naumov, A. K.; Semashko, V. V.

    2009-11-01

    Experimental and theoretical results of investigation of CW Yb:LiLuF 4 (Yb:LLF) and Yb:Na 4Y 6F 22 (Yb:NYF) lasers under longitudinal diode laser pump are reported. Slope efficiencies of 41%, 58% with 0.21, 0.53 W of output powers were obtained for the Yb:LLF and Yb:NYF lasers, correspondingly. The Yb:NYF laser demonstrated tunability in the region from 1005 to 1061 nm. The mathematical modelling of CW laser operation predicts under optimized laser parameters optical to optical efficiencies of about 55% and 51% for Yb:LLF and Yb:NYF lasers, respectively.

  10. Ultraviolet upconversion luminescence of Gd{sup 3+} and Eu{sup 3+} in nano-structured glass ceramics

    SciTech Connect

    Lin, Hang; Chen, Daqin; Yu, Yunlong; Yang, Anping; Zhang, Rui; Wang, Yuansheng

    2012-02-15

    Highlights: Black-Right-Pointing-Pointer Ultraviolet upconversion emissions of Eu{sup 3+} and Gd{sup 3+} are rarely studied. Black-Right-Pointing-Pointer Nanostructured glass ceramic is developed as a host for ultraviolet upconversion. Black-Right-Pointing-Pointer Ultraviolet upconversion signal are found greatly enhanced after crystallization. Black-Right-Pointing-Pointer It is promising for fabricating novel ultraviolet upconversion lasers. -- Abstract: Ultraviolet multiphoton upconversion emissions of Eu{sup 3+} ({sup 5}H{sub 3-7}, {sup 5}G{sub 2-6}, {sup 5}L{sub 6} {yields} {sup 7}F{sub 0}) and Gd{sup 3+} ({sup 6}I{sub J}, {sup 6}P{sub J} {yields} {sup 8}S{sub 7/2}) are studied in the Eu{sup 3+} (or Gd{sup 3+}) doped SiO{sub 2}-Al{sub 2}O{sub 3}-NaF-YF{sub 3} precursor glasses and glass ceramics containing {beta}-YF{sub 3} nanocrystals, under continuous-wavelength 976 nm laser pumping. It is experimentally demonstrated that energy transfer from Yb{sup 3+} to Tm{sup 3+}, then further to Eu{sup 3+} or Gd{sup 3+} is responsible for the upconversion process. Compared to those in the precursor glasses, the upconversion emission intensities in the glass ceramics are greatly enhanced, owing to the participation of rare earth ions into the low-phonon-energy environment of {beta}-YF{sub 3} nanocrystals. Hopefully, the studied glass ceramics may find potential applications in the field of ultraviolet solid-state lasers.

  11. Resonant photo-ionization of Yb+ to Yb2+

    E-print Network

    Simon Heugel; Martin Fischer; Vladimir Elman; Markus Sondermann; Gerd Leuchs

    2014-12-21

    We demonstrate the three-step fully-resonant photo-ionization of 174Yb+ with weak continuous-wave lasers at ultra violet wavelengths. Starting from an ion crystal of two laser-cooled Yb+ ions localized in a radio-frequency trap, the verification of the ionization process is performed by characterizing the motional dynamics of the resulting mixed-species ion-crystal.

  12. OncoLogicTM

    EPA Science Inventory

    OncoLogicTM - A Computer System to Evaluate the Carcinogenic Potential of Chemicals
    OncoLogicTM is a software program that evaluates the likelihood that a chemical may cause cancer. OncoLogicTM has been peer reviewed and is being rele...

  13. Thermoelectric Properties of Yb_14MnSb_11

    NASA Astrophysics Data System (ADS)

    Carr, C. W.; Klavins, P.; Shelton, R. N.; Kauzlarich, S. M.; Snyder, G. J.

    2000-03-01

    A class of compounds with the general formula R_14MnPn_11 (where R=Eu, Yb, Ca, Sr, Ba and Pn=P, As, Sb, Bi) have been studied for their interesting structural and magnetic properties.(Kauzlarich, S.M., Chemistry, Structure, and Bonding of Zintl Phases and Ions, (VCH Publishers, New York, 1996).) The compounds range from semiconducting to metallic across the series and exhibit colossal magnetoresistive properties at low temperatures. Preliminary measurements of one of these compounds, Yb_14MnSb_11, indicate that it may have potential as a new thermoelectric material. Recently it has been shown that atomic displacement parameters can be used to calculate the thermal conductivity of materials and that this method may prove useful in identifying new thermoelectric materials.(Sales, B.C., et al., J. Solid State Chem., vol. 146 (1999).) We utilize this method to estimate the thermal properties for the Zintl compound Yb_14MnSb_11. The estimated values will be compared with values measured by the 3-omega method.

  14. Synthesis, crystal structure, and magnetism of A2Co12As7 (ACa, Y, CeYb) Xiaoyan Tan a

    E-print Network

    Johnson, Peter D.

    of the rare-earth metal, with the exception of Ce-, Eu-, and Yb-containing compounds. An examination Intermetallics formed by rare-earth (R) and transition (T) metals represent a large family of compounds with many moments at 100­140 K, followed by low-temperature ordering of rare-earth 4f moments. The 3d-4f magnetic

  15. 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^?=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.

  16. Effects of Yb concentration on the spectroscopic properties of Yb: Y3Al5O12.

    PubMed

    Wang, Xiaodan; Xu, Xiaodong; Zeng, Xionghui; Zhao, Zhiwei; Jiang, Benxue; He, Xiaoming; Xu, Jun

    2006-01-01

    Yb:YAG single crystals with Yb doping concentration 5.4, 16.3, 27.1, 53.6, and 100 at.% were grown by the Czochralski process. The effects of Yb concentration on the absorption spectra (190-1100 nm), fluorescence spectra under 940 nm and X-ray excitation were studied. The concentration quenching of fluorescence was observed when the Yb doping concentration reaches to as high as 27.1at.% for Yb:YAG. Under 940 nm excitation, the influence of the self-absorption at 969 and 1029 nm on the fluorescence spectra is not evident when the Yb doping concentration is as high as 27.1at.%. However, it can greatly change the shape of fluorescence spectra of Yb:YAG when the Yb doping concentration reaches to above 53.6 at.%. PMID:16344242

  17. YB48 the metal rich boundary of YB66; crystal growth and thermoelectric properties

    NASA Astrophysics Data System (ADS)

    Hossain, M. Anwar; Tanaka, Isao; Tanaka, Takaho; Khan, A. Ullah; Mori, Takao

    2015-12-01

    It was discovered that the well-known higher boride YB66, one of the first reported phonon glass electron crystals (PGEC), could be obtained in a much more metal-rich composition than previously thought possible. Using the floating zone growth method, YB48 single crystals with YB66 crystal structure could be obtained, and their thermoelectric properties measured. This expansion of the homogeneity range of the well-known YB66 compound is surprising and a new Y atomic site was discovered. YB48 exhibits much higher power factors than YB66 which increase rapidly with increasing temperature. The obtained dimensionless figure of merit of this compound at 990 K is approximately 30 times higher than that of previously reported YB66 samples, and higher than any other pristine higher boride. This discovery reveals YB48 as a promising high temperature thermoelectric material.

  18. CLOMP_TM

    Energy Science and Technology Software Center (ESTSC)

    2012-06-01

    The CLOMP_TM benchmark was developed to measure the overheads of various mechanisms used to guarantee the generation of correct results in threaded code even when multiple threads might be accessing and/or updating the same memory location at the same time. This includes widely supported mechanisms like OpenMP Atomic and Open MP Critical as well as new mechanisms like Transactional Memory (TM) and Speculative Execution (SE) of threads. The CLOMP_TM benchmark is highly configurable to allowmore »a variety of problem sizes, atomic update region sizes, and potential race condition opportunities to be studied. A wide variety of checks are done on the results to verify the expected answer was actuallyl generated. Thus CLOMP_TM can be used both to measure the overhead for various mechanisms and to check the correctness of their implementation.« less

  19. CLOMP_TM

    SciTech Connect

    2012-06-01

    The CLOMP_TM benchmark was developed to measure the overheads of various mechanisms used to guarantee the generation of correct results in threaded code even when multiple threads might be accessing and/or updating the same memory location at the same time. This includes widely supported mechanisms like OpenMP Atomic and Open MP Critical as well as new mechanisms like Transactional Memory (TM) and Speculative Execution (SE) of threads. The CLOMP_TM benchmark is highly configurable to allow a variety of problem sizes, atomic update region sizes, and potential race condition opportunities to be studied. A wide variety of checks are done on the results to verify the expected answer was actuallyl generated. Thus CLOMP_TM can be used both to measure the overhead for various mechanisms and to check the correctness of their implementation.

  20. Thermoelectric properties of the Zintl phases Yb5M2Sb6 (M = Al, Ga, In).

    PubMed

    Aydemir, Umut; Zevalkink, Alex; Ormeci, Alim; Wang, Heng; Ohno, Saneyuki; Bux, Sabah; Snyder, G Jeffrey

    2015-04-21

    Zintl compounds with chemical formula Yb5M2Sb6 (M = Al, Ga, and In) form one of two known A5M2Pn6 structure types characterized by double chains of corner-linked MPn4 tetrahedra bridged by Pn2 dumbbells. High temperature electronic and thermal transport measurements were used to characterize the thermoelectric properties of Yb5M2Sb6 compounds. All samples were found to exhibit similar high p-type carrier concentrations, low resistivity and low Seebeck coefficients in agreement with the band structure calculations. These results, combined with previous studies, suggest that Yb5M2Sb6 compounds are semimetals (i.e., they lack an energy gap between the valence and conduction bands), in contrast to the semiconducting alkaline earth (Ca, Sr, Ba) and Eu based A5M2Sb6 compounds. Yb5M2Sb6 compounds have very low lattice thermal conductivity, comparable to other closely related A5M2Sb6 and A3MSb3 phases. However, due to the semimetallic behaviour, the figure of merit of investigated samples remains low (zT < 0.15). PMID:25670617

  1. Optical waveguides in Yb:SBN crystals fabricated by swift C3+ ion irradiation

    NASA Astrophysics Data System (ADS)

    Liu, Guiyuan; Dong, Ningning; Wang, Jun; Akhmadaliev, Shavkat; Zhou, Shengqiang; Chen, Feng

    2016-01-01

    We report on the fabrication of optical planar waveguides supporting both the TE and TM confinements in Yb:SBN crystal by swift C3+ ions irradiation. A combination of the micro-photoluminescence and micro-Raman investigations have evidenced the presence of lattice distortion, damage and disordering of the SBN network along the ion irradiation path, with these effects being at the basis of the refractive index modification. The enhanced micro-photoluminescence and micro-Raman intensity in the waveguide volumes show the potential application of the obtained waveguides as active laser gain media.

  2. 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

    SciTech Connect

    White, J.P. III; Deng, H.; Boyd, E.P.; Gallucci, J.; Shore, S.G. )

    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

  3. CaF2:Yb laser ceramics

    NASA Astrophysics Data System (ADS)

    Akchurin, M. Sh.; Basiev, T. T.; Demidenko, A. A.; Doroshenko, M. E.; Fedorov, P. P.; Garibin, E. A.; Gusev, P. E.; Kuznetsov, S. V.; Krutov, M. A.; Mironov, I. A.; Osiko, V. V.; Popov, P. A.

    2013-01-01

    CaF2:Yb fluoride laser ceramics, prepared by hot-forming, exhibit the same optical properties as starting single crystals. Slope efficiency of the ?a0.95Yb0.05F2.05 is equal to 35% in the pulsed mode of laser operation. Decrease of ytterbium concentration in CaF2:Yb samples down to 3 mol.% resulted in the essential improvement of ?a0.97Yb0.03F2.03 thermal conductivity from 3.5 to 4.5 W/m K, but slightly decreased (down to 30%) slope efficiency of the samples under both pulsed and CW mode of operation. Alternative hot-pressing synthesis of CaF2:Yb fluoride laser ceramics provided materials with superior mechanical properties (microhardness ? = 3.2 GPa and fracture toughness ?1? = 0.65 ?P? m1/2) in comparison with hot-formed and/or single crystal CaF2:Yb specimens. For the first time, lasing has been observed for the novel aforementioned hot-pressed CaF2:Yb ceramics.

  4. Phase equilibrium and intermediate phases in the Eu-Sb system

    SciTech Connect

    Abdusalyamova, M.N.

    2011-10-15

    Rapid heating rate thermal analysis, X-ray diffraction, fluorescence spectrometry, and differential dissolution method were used to study the high-temperature phase equilibrium in the Eu-Sb system within the composition range between 37 and 96 at% Sb. The techniques were effective in determination of the vapor-solid-liquid equilibrium since intermediate phases except Eu{sub 4}Sb{sub 3} evaporated incongruently after melting. A thermal procedure was developed to determine the liquidus and solidus lines of the T-x diagram. Six stable phases were identified: two phases, EuSb{sub 2} and Eu{sub 4}Sb{sub 3}, melt congruently at 1045{+-}10 deg. C and 1600{+-}15 deg. C, the Eu{sub 2}Sb{sub 3}, Eu{sub 11}Sb{sub 10}, Eu{sub 5}Sb{sub 4}, and Eu{sub 5}Sb{sub 3} phases melt incongruently at 850{+-}8 deg. C, 950{+-}10 deg. C, 1350{+-}15 deg. C, and 1445{+-}15 deg. C, respectively. The exact composition shifting of Sb-rich decomposable phases towards Eu{sub 4}Sb{sub 3}, the most refractory compound, was determined. The topology of the Eu-Sb phase diagram was considered together with that of the Yb-Sb system. - Graphical abstract: The high-temperature range of the T-x phase diagram for the Eu-Sb system. Highlights: > The phase relations in the Eu-Sb system were studied over a large composition and temperature scale. > The liquidus and solidus lines of the T-x diagram were well established using effective techniques. > In the system, six binary phases are stable and they melt incongruently except EuSb{sub 2} and Eu{sub 4}Sb{sub 3}. > Incongruent evaporation was found to be typical of all the phases besides Eu{sub 4}Sb{sub 3}.

  5. GEOMAG[TM] Paradoxes

    ERIC Educational Resources Information Center

    Defrancesco, Silvia; Logiurato, Fabrizio; Karwasz, Grzegorz

    2007-01-01

    As often happens, a lot of physics can come out of a toy. What we found interesting is the observation of the magnetic field produced by different configurations built with GEOMAG[TM]. This toy provides small magnetic bars and steel spheres to play with. Amusing 3-D structures can be built; nevertheless, this possibility is not so obvious. Indeed,…

  6. Yb valence states in YbC2: a HERFD-XANES spectroscopic investigation.

    PubMed

    Link, Pascal; Glatzel, Pieter; Kvashnina, Kristina; Smith, Ronald I; Ruschewitz, Uwe

    2011-06-20

    The valence state of Yb in YbC(2) was analyzed using high-energy-resolution fluorescence detection (HERFD) X-ray absorption near-edge structure (XANES) spectroscopy and time-of-flight neutron powder diffraction to clarify a controversy in the literature. The unit cell volume of YbC(2) suggests a mixed Yb valence, which was formerly determined to be 2.8 by magnetization measurements and paramagnetic neutron scattering techniques. However, the nature of the intermediate valence was not clearly established. Both homogeneous and heterogeneous mixed valences were assumed in different publications. The temperature-dependent behavior of the valence state was only predicted, albeit not explicitly studied. In this work, the valence state of Yb in YbC(2) is, therefore, investigated thoroughly by HERFD-XANES spectroscopy at low and high temperatures. Our measurements result in an average Yb valence of 2.81 that is temperature-independent from 15 to 1123 K. These findings are confirmed by neutron powder diffraction experiments, which reveal a constant C-C distance of 128.7(9) pm in a temperature range from 5 to 100 K. A significant temperature dependence of the Yb valence state in YbC(2) can, therefore, be excluded by our experimental results. PMID:21612187

  7. Mode instability thresholds for Tm-doped fiber amplifiers pumped at 790 nm

    E-print Network

    Smith, Arlee V

    2015-01-01

    We use a detailed numerical model of stimulated thermal Rayleigh scattering to compute mode instability thresholds in Tm$^{3+}$-doped fiber amplifiers. The fiber amplifies 2040 nm light using a 790 nm pump. The cross-relaxation process is strong, permitting power efficiencies of 60%. The predicted instability thresholds are compared with those in similar Yb$^{3+}$-doped fiber amplifiers with 976 nm pump and 1060 nm signal, and are found to be higher, even though the heat load is much higher in Tm-doped amplifiers. The higher threshold in the Tm-doped fiber is attributed to its longer signal wavelength, and to stronger gain saturation, due in part to cross-relaxation heating.

  8. LiYbCl4(THF)4

    PubMed Central

    Richtera, Lukas; Jancik, Vojtech; Hermanova, Sona; Krpoun, Karel; Thompson-Montero, Kimberly

    2011-01-01

    The title compound, di-?-chlorido-dichlorido-1?2 Cl-tetra­kis­(tetra­hydro­furan)-1?2 O,2?2 O-lithiumytterbium(III), [LiYbCl4(C4H8O)4], was prepared by the reaction of YbCl3(THF)3 with LiCl in THF (THF is tetra­hydro­furan). The central motif of the structure is a Yb(?-Cl)2Li ring. The Yb atom is hexa­coordinated to four Cl atoms and two THF mol­ecules oriented in a trans fashion. The Li atom has a tetra­hedral environment and is coordinated to two Cl atoms and two THF mol­ecules. No inter­molecular inter­actions other than van der Waals forces were observed. Two of the THF mol­ecules are disordered over two positions. PMID:21754604

  9. Intermediate valence in Yb Intermetallic compounds Jon Lawrence

    E-print Network

    Lawrence, Jon

    1 Intermediate valence in Yb Intermetallic compounds Jon Lawrence University of California, Irvine-based intermetallics. The ground state is that of a heavy mass Fermi liquid. The d.c. and optical conductivity reflect. Talk at LBL, 12 April 2006 #12;2 Intermediate Valence Compounds CeSn3 Fermi liquid (FL) YbAgCu4, Yb

  10. Efficient blue up-conversion luminescence of Tm3+ ions in transparent oxyfluoride glass ceramics containing Pbx Cd1-x F2 nanocrystals

    NASA Astrophysics Data System (ADS)

    Qiu, J.; Mukai, A.; Makishima, A.; Kawamoto, Y.

    2002-12-01

    Oxyfluoride glasses were developed in the 30SiO2 . 15AlO1.5 . 28PbF2 . 22CdF2 . (4.8 - y)GdF3 . 0.1NdF3 . yYbF3 . 0.1TmF3 (y = 0, 0.1, 0.2, 0.5, 1, 2, 3, 4 and 4.8) composition, in mol%. X-ray diffraction analysis revealed that heat treatments of the oxyfluoride glasses cause the precipitation of (Nd3+, Yb3 +, Tm3+)-doped fluorite-type Pbx Cd1-x F2 nanocrystals of about 17.8 nm diameter in a glass matrix. Very strong blue up-conversion luminescence which can be assigned to the Tm3+ :1 G 4 rightarrow3 H 6 transition under 800 nm excitation was observed in these transparent glass ceramics. The intensity of the blue up-conversion luminescence is strongly dependent on the precipitation of Pbx Cd1-x F2 crystals and the YbF3 concentration. The reasons for the highly efficient Tm3+ up-conversion luminescence are discussed. An energy transfer process and an up-conversion mechanism in the glass and glass ceramics are also proposed.

  11. Anomalies in the Young modulus at structural phase transitions in rare-earth cobaltites RBaCo{sub 4}O{sub 7} (R = Y, Tm-Lu)

    SciTech Connect

    Kazei, Z. A. Snegirev, V. V.; Andreenko, A. S.; Kozeeva, L. P.

    2011-08-15

    The elastic properties of rare-earth cobaltites RBaCo{sub 4}O{sub 7} (R = Y, Tm-Lu) have been experimentally studied in the temperature range of 80-300 K. The strong softening of the Young modulus {Delta}E(T)/E{sub 0} Almost-Equal-To -(0.1-0.2) of cobaltites with Lu and Yb ions has been revealed, which is due to the instability of the crystal structure upon cooling and is accompanied by an inverse jump at the second-order structural phase transition. The softening of the Young modulus and the jump at the phase transition decrease by an order of magnitude and the transition temperature T{sub s} and hysteresis {Delta}T{sub s} increase from a compound with Lu to that with Tm. A large softening of the Young modulus at the structural transition in Lu- and Yb cobaltites indicates that the corresponding elastic constant goes to zero, whereas this constant in Tm cobaltite is not a 'soft' mode of the phase transition. It has been found that the structural phase transition in Lu- and Yb cobaltites is accompanied by a large absorption maximum at the phase transition point and an additional maximum in the low-temperature phase and absorption anomalies in Tm cobaltite is an order of magnitude smaller.

  12. Yb-Bi pulsed fiber lasers.

    PubMed

    Dvoyrin, V V; Mashinsky, V M; Dianov, E M

    2007-03-01

    A new type of pulsed fiber laser is suggested and developed - Yb-Bi lasers. In such lasers the Yb fiber laser is Q-switched by use of a saturable absorber, a Bi-doped fiber placed in its own resonator, and pulsed lasing is obtained in both fiber lasers. Continous-wave diode-clad pumping of the Yb-Bi lasers at a 975 nm wavelength with power up to 16.5 W results in pulsed laser action in a spectral diapason of 1050-1200 nm with a maximum pulse energy of up to 100 microJ, an average power up to 7.5 W, and a repetition rate up to 100 kHz. PMID:17392884

  13. Monodisperse lanthanide oxyfluorides LnOF (Ln = Y, La, Pr-Tm): morphology controlled synthesis, up-conversion luminescence and in vitro cell imaging

    NASA Astrophysics Data System (ADS)

    Zhang, Yang; Li, Xuejiao; Hou, Zhiyao; Lin, Jun

    2014-05-01

    Lanthanide oxyfluorides LnOF (Ln = Y, La, Pr-Tm) nano/micro-materials with a variety of well-defined morphologies including nanorods, nanospindles, nanorod-bundles and nanospheres, have been successfully synthesized via a facile precipitation technique followed by a heating treatment. It is found that the pH values, fluoride sources and dosage of urea in the initial reaction systems play critical roles in the morphology determination of the LnOF products and the possible formation mechanism for these diverse architectures has been presented. XRD, FT-IR, TG-DTA, SEM, TEM, as well as up-conversion (UC) luminescence spectra are used to characterize the synthesized samples. Under 980 nm NIR laser excitation, red, green and blue UC luminescence are observed from Yb3+/Er3+, Yb3+/Ho3+ and Yb3+/Tm3+ co-doped YOF nanospheres. The MTT assay indicates that YOF nanospheres exhibit good biocompatibility. Especially, the emission spectrum of YOF: 0.20Yb3+, 0.04Er3+ nanospheres is dominated by a single red emission at 660 nm, which falls into the ``optical window'' of biological tissues. The application of YOF: 0.20Yb3+, 0.04Er3+ nanospheres in the cell imaging is also investigated, which shows a bright-red emission without background noise.Lanthanide oxyfluorides LnOF (Ln = Y, La, Pr-Tm) nano/micro-materials with a variety of well-defined morphologies including nanorods, nanospindles, nanorod-bundles and nanospheres, have been successfully synthesized via a facile precipitation technique followed by a heating treatment. It is found that the pH values, fluoride sources and dosage of urea in the initial reaction systems play critical roles in the morphology determination of the LnOF products and the possible formation mechanism for these diverse architectures has been presented. XRD, FT-IR, TG-DTA, SEM, TEM, as well as up-conversion (UC) luminescence spectra are used to characterize the synthesized samples. Under 980 nm NIR laser excitation, red, green and blue UC luminescence are observed from Yb3+/Er3+, Yb3+/Ho3+ and Yb3+/Tm3+ co-doped YOF nanospheres. The MTT assay indicates that YOF nanospheres exhibit good biocompatibility. Especially, the emission spectrum of YOF: 0.20Yb3+, 0.04Er3+ nanospheres is dominated by a single red emission at 660 nm, which falls into the ``optical window'' of biological tissues. The application of YOF: 0.20Yb3+, 0.04Er3+ nanospheres in the cell imaging is also investigated, which shows a bright-red emission without background noise. Electronic supplementary information (ESI) available: The XRD patterns of GdOF, ErOF, Tm(OF)1.93 and YOF obtained after calcinations at 800 °C for 3 h and the corresponding standard data of GdOF, ErOF, Tm(OF)1.93 and YOF. The accurate amounts of Ln3+ and F- for LaOF, GdOF, ErOF and YOF: 0.20Yb3+, 0.04Er3+, respectively. SEM images of the ErOF precursor under different experimental conditions (a) pH = 2, urea/Ln3+ = 66, with LiF; (b) pH = 2, urea/Ln3+ = 66, with KF; (c) pH = 6, urea/Ln3+ = 66, with NaF; (d) pH = 10, urea/Ln3+ = 66, with NaF; (e) pH = 2, urea/Ln3+ = 80, with NaF and (f) pH = 2, urea/Ln3+ = 100, with NaF. See DOI: 10.1039/c4nr00384e

  14. IMPLEMENTING EU BIODIVERSITY POLICY

    E-print Network

    Bateman, Ian J.

    IMPLEMENTING EU BIODIVERSITY POLICY: A UK CASE STUDY by Laure Ledoux Stephen Crooks Andrew Jordan R. Kerry Turner CSERGE Working Paper GEC 2000-03 #12;IMPLEMENTING EU BIODIVERSITY POLICY: A UK CASE STUDY into Biodiversity in the European Union. The authors gratefully acknowledge helpful comments from Richard Handley

  15. Intermetallic germanides with non-centrosymmetric structures derived from the Yb3Rh4Sn13 type.

    PubMed

    Gumeniuk, R; Schöneich, M; Kvashnina, K O; Akselrud, L; Tsirlin, A A; Nicklas, M; Schnelle, W; Janson, O; Zheng, Q; Curfs, C; Burkhardt, U; Schwarz, U; Leithe-Jasper, A

    2015-03-28

    New germanides with composition RE3Pt4Ge13 (RE = Y, Pr, Sm, Gd, Tb, Tm) have been prepared by high-pressure, high-temperature synthesis. Their crystal structures have been refined, and the relationship of this new rhombohedral and monoclinic structure types with the primitive cubic Yb3Rh4Sn13 prototype is discussed. Band structure calculations within density functional theory confirm the distorted rhombohedral and monoclinic structural arrangements to be energetically more favorable than the simple cubic one. X-ray absorption spectroscopy and magnetic susceptibility measurements indicate that the RE-atoms are in the +3 oxidation state in all studied compounds. PMID:25705863

  16. An Yb-Raman cascaded fiber laser with temporal stability

    NASA Astrophysics Data System (ADS)

    Wenliang, Wang; Jinyong, Leng; Yang, Gao; Shaofeng, Guo; Zongfu, Jiang

    2015-07-01

    We report a new structure of fiber laser, which has the advantages of temporal stability and wavelength agility. An Yb-Raman cascaded fiber oscillator generating 168 mW 1137 nm stable CW signal with 18.2% slope efficiency is demonstrated. In this fiber oscillator, the gain from both Yb ion and SRS effect is utilized. By comparison, the characteristics of the 1137 nm Yb-doped fiber laser are studied. The results show that the serious self-pulsation effect in the Yb-doped fiber laser is suppressed in the Yb-Raman cascaded fiber oscillator.

  17. The tmRNA website

    DOE PAGESBeta

    Hudson, C. M.; Williams, K. P.

    2014-11-05

    The transfer-messenger RNA (tmRNA) and its partner protein SmpB act together in resolving problems arising when translating bacterial ribosomes reach the end of mRNA with no stop codon. Their genes have been found in nearly all bacterial genomes and in some organelles. The tmRNA Website serves tmRNA sequences, alignments and feature annotations, and has recently moved to http: //bioinformatics.sandia.gov/tmrna/. New features include software used to find the sequences, an update raising the number of unique tmRNA sequences from 492 to 1716, and a database of SmpB sequences which are served along with the tmRNA sequence from the same organism.

  18. Growth and optical properties of Yb doped new scintillator crystals

    NASA Astrophysics Data System (ADS)

    Yoshikawa, A.; Ogino, H.; Lee, J. H.; Nikl, M.; Solovieva, N.; Garnier, N.; Dujardin, C.; Lebbou, K.; Pedrini, C.; Fukuda, T.

    2003-10-01

    Single crystal of heavily Yb 3+-doped Lu 3Al 5O 12 (Yb:LuAG) were grown by the micro-pulling-down method. Radio- and photoluminescence spectra of the Yb:LuAG were studied. Two bands peaking round 340-350 and 480-500 nm could be ascribed to charge transfer (CT) luminescence of Yb 3+, as their position nearly coincide with the Yb 3+-related CT emission in YAG matrix. The highest emission intensity was observed for Yb concentration of 5% with respect to the Lu site. Temperature dependence of photoluminescence spectra of the Yb: LuAG (5%) was measured and points to remarkable thermal quenching above liquid nitrogen temperature.

  19. Temperature dependence and optimization of 970-nm diode-pumped Yb:YAG and Yb:LuAG lasers.

    PubMed

    Kasamatsu, T; Sekita, H; Kuwano, Y

    1999-08-20

    We have investigated the temperature dependence of output performances for 970-nm diode-pumped Yb:YAG (Yb(3+):Y(3)Al(5)O(12)) and Yb:LuAG (Yb(3+):Lu(3)Al(5)O(12)) lasers over the wide temperature range from 80 to 310 K. Temperature-optimized operation was experimentally demonstrated at around 160 K and was theoretically confirmed by taking into account the absorption spectra change of Yb crystals at low temperatures. Cooling the crystal to below 160 K caused a narrowing of the absorption bandwidth and led to a decrease in output power and efficiency. PMID:18324010

  20. Temperature Dependence and Optimization of 970-nm Diode-Pumped Yb:YAG and Yb:LuAG Lasers

    NASA Astrophysics Data System (ADS)

    Kasamatsu, Tadashi; Sekita, Hitoshi; Kuwano, Yasuhiko

    1999-08-01

    We have investigated the temperature dependence of output performances for 970-nm diode-pumped Yb:YAG (Yb 3 :Y 3 Al 5 O 12 ) and Yb:LuAG (Yb 3 :Lu 3 Al 5 O 12 ) lasers over the wide temperature range from 80 to 310 K. Temperature-optimized operation was experimentally demonstrated at around 160 K and was theoretically confirmed by taking into account the absorption spectra change of Yb crystals at low temperatures. Cooling the crystal to below 160 K caused a narrowing of the absorption bandwidth and led to a decrease in output power and efficiency.

  1. Near infrared activation of an anticancer Pt(IV) complex by Tm-doped upconversion nanoparticles.

    PubMed

    Ruggiero, Emmanuel; Hernández-Gil, Javier; Mareque-Rivas, Juan C; Salassa, Luca

    2015-02-01

    The Pt(IV) complex cis,cis,trans-[Pt(NH3)2(Cl)2(O2CCH2CH2CO2H)2] is photoactivated by near infrared light (980 nm) using NaYF4:Yb(3+)/Tm(3+)@NaYF4 core-shell upconversion nanoparticles. Coupling of this cisplatin precursor with the biocompatible PEGylated phospholipid DSPE-PEG(2000)-NH2 affords a valuable approach to decorate the surface of the nanoparticles, providing novel photoactivatable nanomaterials capable of releasing Pt(II) species upon NIR light excitation. PMID:25536114

  2. Eu 3F 4S 2: Synthesis, crystal structure, and magnetic properties of the mixed-valent europium(II,III) fluoride sulfide EuF 2·(EuFS) 2

    NASA Astrophysics Data System (ADS)

    Grossholz, Hagen; Hartenbach, Ingo; Kotzyba, Gunter; Pöttgen, Rainer; Trill, Henning; Mosel, Bernd D.; Schleid, Thomas

    2009-11-01

    Using the method to synthesize rare-earth metal(III) fluoride sulfides MFS ( M=Y, La, Ce-Lu), in some cases we were able to obtain mixed-valent compounds such as Yb 3F 4S 2 instead. With Eu 3F 4S 2 another isotypic representative has now been synthesized. Eu 3F 4S 2 (tetragonal, I4 /mmm, a=400.34(2), c=1928.17(9) pm, Z=2) is obtained from the reaction of metallic europium, elemental sulfur, and europium trifluoride in a molar ratio of 5:6:4 within seven days at 850 °C in silica-jacketed gas-tightly sealed platinum ampoules. The single-phase product consists of black plate-shaped single crystals with a square cross section, which can be obtained from a flux using equimolar amounts of NaCl as fluxing agent. The crystal structure is best described as an intergrowth structure, in which one layer of CaF 2-type EuF 2 is followed by two layers of PbFCl-type EuFS when sheeted parallel to the (001) plane. Accordingly there are two chemically and crystallographically different europium cations present. One of them (Eu 2+) is coordinated by eight fluoride anions in a cubic fashion, the other one (Eu 3+) exhibits a monocapped square antiprismatic coordination sphere with four F - and five S 2- anions. Although the structural ordering of the different charged europium cations is plausible, a certain amount of charge delocalization with some polaron activity has to take place, which is suggested by the black color of the title compound. Temperature dependent magnetic susceptibility measurements of Eu 3F 4S 2 show Curie-Weiss behavior with an experimental magnetic moment of 8.19(5) ? B per formula unit and a paramagnetic Curie temperature of 0.3(2) K. No magnetic ordering is observed down to 4.2 K. In accordance with an ionic formula splitting like (Eu II)(Eu III) 2F 4S 2 only one third of the europium centers in Eu 3F 4S 2 carry permanent magnetic moments. 151Eu-Mössbauer spectroscopic experiments at 4.2 K show one signal at an isomer shift of -12.4(1) mm/s and a second one at 0.42(4) mm/s. These signals occur in a ratio of 1:2 and correspond to Eu 2+ and Eu 3+, respectively. The spectra at 78 and 298 K are similar, thus no change in the Eu 2+/Eu 3+ fraction can be detected.

  3. Effects of Second Phase Yb5Sb3 on the Thermoelectric Properties of YbAl3

    NASA Astrophysics Data System (ADS)

    Li, J. Q.; Liu, X. Y.; Li, Y.; Deng, J. F.; Ye, R. F.; Song, S. H.; Liu, F. S.; Ao, W. Q.

    2014-04-01

    The compound YbAl3 exhibits a very high power factor but also rather a large thermal conductivity, leading to a low figure of merit. The second phase Yb5Sb3 was introduced in the YbAl3 matrix to reduce its thermal conductivity. The composites (YbAl3)1- x (Yb5Sb3) x with x = 0, 0.01, 0.05, 0.10, and 0.20 were synthesized by high frequency induction melting, annealing treatment, and spark plasma sintering. The thermoelectric properties of the composites were evaluated. The composites are of n-type conduction. The pure YbAl3 obtained in this work shows a high power factor of 11,500 ?W m-1 K-2 but also a high thermal conductivity of 19.6 W m-1 K-1. However, the existence of Yb5Sb3 compound in the YbAl3 matrix enhances the electrical resistivity and the absolute Seebeck coefficient of the composite, but significantly reduces its thermal conductivity in the temperature range considered, thereby enhancing the figure of merit. The highest ZT value of 0.23 may be obtained in the sample (YbAl3)0.95(Yb5Sb3)0.05 at room temperature, which is apparently higher than that of pure YbAl3.

  4. Effects of Yb concentration on the fluorescence spectra of Yb-doped YAlO3 single crystals.

    PubMed

    Zeng, Xionghui; Zhao, Guangjun; Xu, Jun

    2006-09-01

    0.5 at.% Yb:YAlO(3)(YAP), 5 at.% Yb:YAP and 15 at.% Yb:YAP were grown using the Czochralski method. Their absorption and fluorescence spectra were measured at room temperature and their emission line shape was calculated using the method of reciprocity. It was observed that the fluorescence spectra changed appreciably with the increasing of Yb concentration. For 0.5 at.% Yb:YAP, the line shape of fluorescence is very similar with the calculated emission line shape; with the increasing of Yb doping concentration, the line shape of fluorescence is very different from the calculated emission line shape. These phenomena are caused by the strong self-absorption at 979 and 999 nm for Yb:YAP. PMID:16495140

  5. From Biology to DiscoveryTM LipodinProTM

    E-print Network

    Lebendiker, Mario

    an alternative to nucleic acids transfection and a powerful strategy for functional studies or therapeutic with a single sample. Principal LipodinPro TM advantages: · No need for DNA cloning or nucleic acid

  6. The tm2mon Program Dave Galloway

    E-print Network

    Rose, Jonathan

    for connections to those sockets. On one of the sockets (the housekeeping socket) tm2mon will accept requests the ports socket is used. A second program called tm2 is usually used to talk to the housekeeping socket it a "­" argument: tm2 ­ getdesigndir getdesigndate â??D Tm2mon Housekeeping Socket Requests This is a list

  7. [YB-1 as a potential target in cancer therapy].

    PubMed

    Lage, H; Surowiak, P; Holm, P S

    2008-11-01

    The 42-kDa multifunctional cellular protein Y-box protein 1 (YB-1) is expressed in various cancers. It is localized in the cytoplasm as well as in the nucleus. In particular, YB-1 is localized in the nuclear compartment following cellular stress, such as radiation, drug treatment, hyperthermia, or viral infection. Within the nucleus, YB-1 can act as a transcription factor, and it is involved in the regulation of important cancer-associated genes. For example, YB-1 triggers the expression of Her-2 and estrogen receptor alpha (ERalpha) in breast cancer. Thus, nuclear YB-1 appears to be a potential target for the inhibition of Her-2- and ERalpha-dependent proliferation signals, particularly with regard to resistance to Her-2-targeting drugs such as trastuzumab. In some cancers, YB-1 may be involved in regulating MDR1/P-glycoprotein, mediating classical multidrug resistance (MDR). Furthermore, YB-1 is involved in the replication of adenovirus type 5, a commonly used vector in gene therapy. Thus, YB-1 can trigger an "oncolytic" effect in YB-1 nuclear positive cancer cells treated with adenoviruses. Besides its impact as a prognostic factor, in the future the diagnostics of cellular YB-1 status may provide the basis for a virotherapy or a gene therapy incorporating adenoviruses. PMID:18773210

  8. Dysfunction of Rice Mitochondrial Membrane Induced by Yb(3.).

    PubMed

    Gao, Jia-Ling; Wu, Man; Liu, Wen; Feng, Zhi-Jiang; Zhang, Ye-Zhong; Jiang, Feng-Lei; Liu, Yi; Dai, Jie

    2015-12-01

    Ytterbium (Yb), a widely used rare earth element, is treated as highly toxic to human being and adverseness to plant. Mitochondria play a significant role in plant growth and development, and are proposed as a potential target for ytterbium toxicity. In this paper, the biological effect of Yb(3+) on isolated rice mitochondria was investigated. We found that Yb(3+) with high concentrations (200 ~ 600 ?M) not only induced mitochondrial membrane permeability transition (mtMPT), but also disturbed the mitochondrial ultrastructure. Moreover, Yb(3+) caused the respiratory chain damage, ROS formation, membrane potential decrease, and mitochondrial complex II activity reverse. The results above suggested that Yb(3+) with high concentrations could induce mitochondrial membrane dysfunction. These findings will support some valuable information to the safe application of Yb-based agents. PMID:26305923

  9. Resonantly pumped amplification in a Tm-doped large mode-area photonic crystal fiber

    NASA Astrophysics Data System (ADS)

    Sincore, Alex; Shah, Lawrence; Wysmolek, Mateusz; Ryan, Robert; Abdulfattah, Ali; Richardson, Martin

    2015-03-01

    Ultra-large mode area thulium-doped photonic crystal fibers (Tm:PCF) have enabled the highest peak powers in 2 micron fiber laser systems to date. However, Tm:PCFs are limited by slope efficiencies of <50% when pumped with 790 nm laser diodes. A well-known alternative is pumping at 1550 nm with erbium/ytterbium-doped fiber (Er/Yb:fiber) lasers for efficiencies approaching ~70%. However, these 1550 nm pump lasers are also relatively inefficient themselves. A recently demonstrated and more attractive approach to enable slope efficiencies over 90% in thuliumdoped step-index fibers is resonant pumping (or in-band pumping). This utilizes a high power thulium fiber laser operating at a shorter wavelength as the pump. In this manuscript, we describe an initial demonstration of resonant pumping in Tm:PCF. While the extracted power was still in the exponential regime due to pump power limitations, slope efficiencies in excess of ~64 have been observed, and there is still room for improvement. These initial results show promise for applying resonant pumping in Tm:PCF to improve efficiencies and facilitate high power scaling in ultralarge mode area systems.

  10. The spectroscopic properties of Yb3+ doped ?-BBO crystal

    NASA Astrophysics Data System (ADS)

    Yu, Pingsheng; Su, Liangbi; Wu, Feng; Xu, Jun

    2012-05-01

    2.0 mol% (relative to Ba2+) Yb3+ doped ?-BaB2O4 (?-BBO) crystal was obtained by the Czochralski method. The doped crystal structure was determined by means of an X-ray diffraction analysis. The absorption, near-infrared (NIR) luminescence spectra and fluorescence decay curve of Yb3+ doped ?-BBO crystal were investigated. NIR emission under 940 nm and 980 nm LDs (laser diodes) excitation was observed in the Yb doped ?-BBO crystal.

  11. 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).

  12. Quantum chaos in ultracold collisions between Yb($^1$S$_0$) and Yb($^3$P$_2$)

    E-print Network

    Green, Dermot G; Frye, Matthew D; Morita, Masato; Hutson, Jeremy M

    2015-01-01

    We calculate and analyze Feshbach resonance spectra for ultracold Yb($^1$S$_0$) + Yb($^3$P$_2$) collisions as a function of an interatomic potential scaling factor $\\lambda$ and external magnetic field. We show that, at zero field, the resonances are distributed randomly in $\\lambda$, but that signatures of quantum chaos emerge as a field is applied. The random zero-field distribution arises from superposition of structured spectra associated with individual total angular momenta. In addition, we show that the resonances in magnetic field in the experimentally accessible range 400 to 2000~G are chaotically distributed, with strong level repulsion that is characteristic of quantum chaos.

  13. Quantum chaos in ultracold collisions between Yb($^1$S$_0$) and Yb($^3$P$_2$)

    E-print Network

    Dermot G. Green; Christophe L. Vaillant; Matthew D. Frye; Masato Morita; Jeremy M. Hutson

    2015-10-23

    We calculate and analyze Feshbach resonance spectra for ultracold Yb($^1$S$_0$) + Yb($^3$P$_2$) collisions as a function of an interatomic potential scaling factor $\\lambda$ and external magnetic field. We show that, at zero field, the resonances are distributed randomly in $\\lambda$, but that signatures of quantum chaos emerge as a field is applied. The random zero-field distribution arises from superposition of structured spectra associated with individual total angular momenta. In addition, we show that the resonances in magnetic field in the experimentally accessible range 400 to 2000~G are chaotically distributed, with strong level repulsion that is characteristic of quantum chaos.

  14. Constitutive and functional expression of YB-1 in microglial cells.

    PubMed

    Keilhoff, G; Titze, M; Esser, T; Langnaese, K; Ebmeyer, U

    2015-08-20

    Y-box-binding protein (YB-1) is a member of the cold-shock protein family and participates in a wide variety of DNA/RNA-dependent cellular processes including DNA repair, transcription, mRNA splicing, packaging, and translation. At the cellular level, YB-1 is involved in cell proliferation and differentiation, stress responses, and malignant cell transformation. A general role for YB-1 during inflammation has also been well described; however, there are minimal data concerning YB-1 expression in microglia, which are the immune cells of the brain. Therefore, we studied the expression of YB-1 in a clinically relevant global ischemia model for neurological injury following cardiac arrest. This model is characterized by massive neurodegeneration of the hippocampal CA1 region and the subsequent long-lasting activation of microglia. In addition, we studied YB-1 expression in BV-2 cells, which are an accepted microglia culture model. BV-2 cells were stressed by oxygen/glucose deprivation (OGD), OGD-relevant mediators, lipopolysaccharide (LPS), and phagocytosis-inducing cell debris and nanoparticles. Using quantitative polymerase chain reaction (PCR), we show constitutive expression of YB-1 transcripts in unstressed BV-2 cells. The functional upregulation of the YB-1 protein was demonstrated in microglia in vivo and in BV-2 cells in vitro. All stressors except for LPS were potent enhancers of the level of YB-1 protein, which appears to be regulated primarily by proteasomal degradation and, to a lesser extent, by the activation (phosphorylation) of the translation initiation factor eIF4E. The proteasome of BV-2 cells is impaired by OGD, which results in decreased protein degradation and therefore increased levels of YB-1 protein. LPS induces proteasome activity, which enables the level of YB-1 protein to remain at control levels despite enhanced protein ubiquitination. The proteasome inhibitor MG-132 was able to increase YB-1 protein levels in control and LPS-treated cultures. YB-1 upregulation was not accompanied by its translocation from the cytoplasm to the nucleus. YB-1 induction appeared to be related to microglial proliferation because it was partially co-regulated with Ki67. In addition, YB-1 protein levels correlated with microglia phagocytic activity because its upregulation could also be induced by inert NPs. PMID:26102006

  15. Yb 3Cu 6Sn 5, Yb 5Cu 11Sn 8 and Yb 3Cu 8Sn 4: crystal structure of three ordered compounds

    NASA Astrophysics Data System (ADS)

    Fornasini, M. L.; Manfrinetti, P.; Mazzone, D.; Riani, P.; Zanicchi, G.

    2004-06-01

    Yb 3Cu 6Sn 5, Yb 5Cu 11Sn 8 and Yb 3Cu 8Sn 4 compounds were prepared in sealed Ta crucibles by induction melting and subsequent annealing. The crystal structures of Yb 3Cu 6Sn 5 and Yb 5Cu 11Sn 8 were determined from single crystal diffractometer data: Yb 3Cu 6Sn 5, isotypic with Dy 3Co 6Sn 5, orthorhombic, Immm, oI28, a=4.365(1) Å, b=9.834(3) Å, c=12.827(3) Å, Z=2, R=0.019, 490 independent reflections, 28 parameters; Yb 5Cu 11Sn 8 with its own structure, orthorhombic, Pmmn, oP48, a=4.4267(6) Å, b=22.657(8) Å, c=9.321(4) Å, Z=2, R=0.047, 1553 independent reflections, 78 parameters. Both compounds belong to the BaAl 4-derived defective structures, and are closely related to Ce 3Pd 6Sb 5 ( oP28, Pmmn). The crystal structure of Yb 3Cu 8Sn 4, isotypic with Nd 3Co 8Sn 4, was refined from powder data by the Rietveld method: hexagonal, P6 3mc, hP30, a=9.080(1) Å, c=7.685(1) Å, Z=2, Rwp=0.040. It is an ordered substitution derivative of the BaLi 4 type ( hP30, P6 3/ mmc). All compounds show strong Cu-Sn bonds with a length reaching 2.553(3) Å in Yb 5Cu 11Sn 8.

  16. Thermodynamics of the hydration equilibrium derived from the luminescence spectra of the solid state for the case of the Eu-EDTA system.

    PubMed

    Janicki, R; Mondry, A

    2015-11-28

    The luminescence properties of two compounds, [C(NH2)3][Eu(EDTA)(H2O)3] (I) and [C(NH2)3]2[Yb0.97Eu0.03(EDTA)(H2O)2]ClO4·6H2O (II), were determined. The weighted sum of luminescence spectra of I and II was used to reproduce the spectra of the Eu-EDTA system in aqueous solution in the temperature range 276-363 K. By implementing this method it was possible to determine the thermodynamic functions (?H = 18113 ± 506 J mole(-1) and ?S = 62.5 ± 4.9 J mole(-1) K(-1)) of the reaction [Eu(EDTA)(H2O)3](-)? [Eu(EDTA)(H2O)2](-) + H2O, which is difficult using other methods. PMID:26400410

  17. Composition and temperature dependence of the Yb valence in YbMn6Ge6-xSnx studied by RIXS

    NASA Astrophysics Data System (ADS)

    Mazet, T.; Malterre, D.; François, M.; Eichenberger, L.; Grioni, M.; Dallera, C.; Monaco, G.

    2015-08-01

    We investigate the composition and temperature (10-450 K) dependence of the Yb valence in YbMn6Ge6 -xSnx (x =0.0 , 3.8, 4.2, 4.4, and 5.5) using resonant inelastic x-ray scattering (RIXS). The observed change in the Yb valence with composition (from ? ˜3 for x =0 to ? ˜2.7 for x =5.5 ) is likely driven by negative chemical pressure effects due to the Sn for Ge substitution. While Yb is nonmagnetic in YbMn6Ge0.5Sn5.5 , intermediate valent Yb magnetically orders at unexpectedly high temperature (up to 90 K) in the alloys with x =3.8 , 4.2, and 4.4. The three latter alloys further exhibit an increase in the Yb valence upon cooling, which is opposite to the usual behavior. Interactions with the magnetically ordered Mn sublattice are invoked to account for these unprecedented phenomena through a simplified model based on an Anderson Hamiltonian with a Zeeman term mimicking the Mn-Yb exchange interactions. We further show that the Yb magnetic behavior in this series can be interpreted based on Doniach's picture. Compared with standard intermediate valent materials where Yb is embedded in a nonmagnetic matrix, the strong Mn-Yb exchange interaction enhances the intermediate valent Yb magnetic ordering temperature and allows for extending the stability domain of the Yb magnetic order towards lower Yb valence.

  18. Magnetic coupling between nonmagnetic ions: Eu3+ in EuN and EuP

    E-print Network

    Pickett, Warren

    Magnetic coupling between nonmagnetic ions: Eu3+ in EuN and EuP M. D. Johannes1 and W. E. Pickett2 2005 We consider the electronic structure of, and magnetic exchange spin interactions betweenP . Exchange spin-spin coupling calculated from correlated band theory is small and ferromagnetic in sign

  19. 75 FR 2129 - Lock+TM

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-01-14

    ... Energy Regulatory Commission Lock+ TM Hydro Friends Fund XXX, LLC; Notice of Preliminary Permit... January 6, 2010. On November 13, 2009, Lock+ TM Hydro Friends Fund XXX, LLC filed an application, pursuant...,018 megawatt-hours. Applicant Contact: Wayne F. Krouse, Lock+ TM Hydro Friends Fund XXX, LLC,...

  20. Candy LightsTM `Golden Lights'

    E-print Network

    Minnesota, University of

    20 Candy LightsTM `Golden Lights' `Mandarin Lights' `Northern Hi-Lights' Tri LightsTM #12;21 Lilac flowering. 3­4' Candy LightsTM 2001 Light pink Pale yellow streaks, very fragrant. 5­6' Golden Lights 1986

  1. 170 Yb Mossbauer study of the YbCd 5:7 binary quasi-crystal and related phases

    E-print Network

    Ryan, Dominic

    annealed at 575 Æ C for three hours. The melting point of YbCd (796 Æ C) lies above the boiling point of Cd point), and then water quenched. As YbCd 6 does not melt congruently, this sample had to be further

  2. Listening and Legos[TM

    ERIC Educational Resources Information Center

    Morris, Pamela

    2012-01-01

    This simple exercise, performed in teams, gives students practice in listening to instructions, particularly when there are restrictions for the communication. The teams compete in a limited amount of time to build a Lego[TM] structure based on the instructions of one team member. Which team listens the best and is most successful?

  3. Nanosecond cryogenic Yb:YAG disk laser

    SciTech Connect

    Perevezentsev, E A; Mukhin, I B; Kuznetsov, I I; Vadimova, O L; Palashov, O V

    2014-05-30

    A cryogenic Yb:YAG disk laser is modernised to increase its average and peak power. The master oscillator unit of the laser is considerably modified so that the pulse duration decreases to several nanoseconds with the same pulse energy. A cryogenic disk laser head with a flow-through cooling system is developed. Based on two such laser heads, a new main amplifier is assembled according to an active multipass cell scheme. The total small-signal gain of cryogenic cascades is ?10{sup 8}. (lasers)

  4. NIR and CT luminescence spectra of [Yb(TFN)(S-BINAPO)] and [Yb(HFA)(S-BINAPO)] complexes.

    PubMed

    Subhan, Md Abdus; Nakata, Hiroyasu

    2014-09-15

    The complexes [Yb(TFN)3(S-BINAPO)](TFN=4,4,4-trifluoro-1(2-napthyl)-1,3-butanedione) (complex 1) and [Yb(HFA)3(S-BINAPO)](HFA=hexafluoroacetylacetonate) (complex 2) were synthesized, characterized. The absorption as well as PL spectra have been studied. The complex [Yb(TFN)3(S-BINAPO)] showed narrowed emission peak (half width ?6 nm) at around 981 nm in addition to several emission peaks in NIR (near infrared) region. The complex [Yb(HFA)3(S-BINAPO)] showed strong emission peak at around 985 nm. The charge transfer luminescence of [Yb(TFN)3(S-BINAPO)] was also observed at 412-463 nm. PMID:24762571

  5. Harmonic mode-locking in a Tm-doped fiber laser: Characterization of its timing jitter and ultralong starting dynamics

    NASA Astrophysics Data System (ADS)

    Bao, Chengying; Yang, Changxi

    2015-12-01

    We report an experimental characterization on harmonic mode-locking in a Tm-doped fiber laser, which exhibits pump related timing jitter and ultralong mode-locking starting dynamics. The laser is pumped by a laser diode seeded EDFA. Harmonic mode-locking is initiated by nonlinear polarization rotation and showed a good long term stability. Timing jitter is found to be significantly influenced by the properties of laser diode seed for the EDFA. When switching the seed from a Fabry-Perot cavity laser diode to a distributed feedback (DFB) laser diode, timing jitter decreases from 16 ps to 6 ps. It also takes the laser an ultralong self-starting time (> 100 s), 3 order of magnitude longer than typical Er-doped or Yb-doped fiber lasers, to reach a steady harmonic mode-locking in some cases. These experimental evidences can contribute to a better understanding of Tm-doped fiber lasers.

  6. Ternary rare earth-lanthanide sulfides. [Re = Eu, Sm or Yb

    DOEpatents

    Takeshita, Takuo; Gschneidner, K.A. Jr.; Beaudry, B.J.

    1986-03-06

    Disclosed is a new ternary rare earth sulfur compound having the formula La/sub 3-x/M/sub x/S/sub 4/, where M is europium, samarium, or ytterbium, with x = 0.15 to 0.8. The compound has good high-temperature thermoelectric properties and exhibits long-term structural stability up to 1000/sup 0/C.

  7. Water Research 39 (2005) 239247 Biosorption of La, Eu and Yb using Sargassum biomass

    E-print Network

    Volesky, Bohumil

    2005-01-01

    with a high sorption potential (Yang and Volesky, 1999b). While rare earths are relatively abundant that in the year 2000, the rare earths were mainly used in automotive catalytic converters (22%), glass polishing and alloys (9%), rare-earth phosphors for lighting, televisions, computer monitors, radar, and X

  8. Synthesis and structure of nanocrystalline mixed Ce–Yb silicates

    SciTech Connect

    Ma?ecka, Ma?gorzata A. K?pi?ski, Leszek

    2013-07-15

    Graphical abstract: - Highlights: • New method of synthesis of nanocrystalline mixed lanthanide silicates is proposed. • Formation of A-type (Ce{sub 1?y}Yb{sub y}){sub 2}Si{sub 2}O{sub 7} in well dispersed Ce{sub 1?x}Yb{sub x}O{sub 2?(x/2)}–SiO{sub 2} system. • Formation of Yb{sub y}Ce{sub 9.33?y}(SiO{sub 4}){sub 6}O{sub 2} in agglomerated Ce{sub 1?x}Yb{sub x}O{sub 2?(x/2)}–SiO{sub 2} system. - Abstract: This work presents results of studies on synthesis and structure of mixed, nanocrystalline Ce–Yb silicates. Using TEM, XRD and FTIR we showed that heat treatment of nanocrystalline Ce{sub 1?x}Yb{sub x}O{sub 2?(x/2)} (x = 0.3, 0.5) mixed oxide supported on amorphous silica in reducing atmosphere, results in formation of Ce–Yb mixed silicates. Dispersion of the oxide on the silica surface and thus a local lanthanide/Si atomic ratio determines the stoichiometry of the silicate. Oxide crystallites uniformly dispersed on the silica surface transformed into A-(Ce{sub 1?y}Yb{sub y}){sub 2}Si{sub 2}O{sub 7} disilicate, while the agglomerated nanoparticles converted into Yb{sub y}Ce{sub 9.33?y}(SiO{sub 4}){sub 6}O{sub 2} oxyapatite silicate as an intermediate phase.

  9. Anisotropic magnetization and transport properties of RAgSb{sub 2} (R=Y, La-Nd, Sm, Gd-Tm)

    SciTech Connect

    Myers, Kenneth D.

    1999-11-08

    This study of the RAgSb{sub 2} series of compounds arose as part of an investigation of rare earth intermetallic compounds containing antimony with the rare earth in a position with tetragonal point symmetry. Materials with the rare earth in a position with tetragonal point symmetry frequently manifest strong anisotropies and rich complexity in the magnetic properties, and yet are simple enough to analyze. Antimony containing intermetallic compounds commonly possess low carrier densities and have only recently been the subject of study. Large single grain crystals were grown of the RAgSb{sub 2} (R=Y, La-Nd, Sm, Gd-Tm) series of compounds out of a high temperature solution. This method of crystal growth, commonly known as flux growth is a versatile method which takes advantage of the decreasing solubility of the target compound with decreasing temperature. Overall, the results of the crystal growth were impressive with the synthesis of single crystals of LaAgSb{sub 2} approaching one gram. However, the sample yield diminishes as the rare earth elements become smaller and heavier. Consequently, no crystals could be grown with R=Yb or Lu. Furthermore, EuAgSb{sub 2} could not be synthesized, likely due to the divalency of the Eu ion. For most of the RAgSb{sub 2} compounds, strong magnetic anisotropies are created by the crystal electric field splitting of the Hund's rule ground state. This splitting confines the local moments to lie in the basal plane (easy plane) for the majority of the members of the series. Exceptions to this include ErAgSb{sub 2} and TmAgSb{sub 2}, which have moments along the c-axis (easy axis) and CeAgSb{sub 2}, which at intermediate temperatures has an easy plane, but exchange coupling at low temperatures is anisotropic with an easy axis. Additional anisotropy is also observed within the basal plane of DyAgSb{sub 2}, where the moments are restricted to align along one of the {l_angle}110{r_angle} axes. Most of the RAgSb{sub 2} compounds containing magnetic rare earths, antiferromagnetically ordered at low temperatures. The ordering temperatures of these compounds are approximately proportional to the de Gennes factor, which suggests that the RKKY interaction is the dominant exchange interaction between local moments. Although metamagnetic transitions were observed in many members of the series, the series of sharp step-like transitions in DyAgSb{sub 2} are impressive. In this compound, up to 11 different magnetic states are stable depending on the magnitude and direction of the applied field. The saturated magnetization of these states and the critical fields needed to induce a phase transition vary with the direction of the applied field. Through detailed study of the angular dependence of the magnetization and critical fields, the net distribution of magnetic moments was determined for most, of the metamagnetic states. In DyAgSb{sub 2}, the crystal electric field (CEF) splitting of the Hund's rule ground state creates a strong anisotropy where the local Dy{sup 3+} magnetic moments are constrained to one of the equivalent {l_angle}110{r_angle} directions within the basal plane. The four position clock model was introduced to account for this rich metamagnetic system. Within this model, the magnetic moments are constrained to one of four equivalent orientations within the basal plane and interactions are calculated for up third nearest neighbors. The theoretical phase diagram, generated from the coupling constants is in excellent agreement with the experimental phase diagram. Further investigation of this compound using magnetic X-ray or neutron diffraction would be extremely useful to verify the net distributions of moments and determine the wave vectors of each of the ordered states.

  10. 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}

    SciTech Connect

    Wang, Jian; Xia, Sheng-Qing; Tao, Xu-Tang; Schäfer, Marion C.; Bobev, Svilen

    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 ?=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 effective 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.

  11. Magnetic, thermal and hyperfine behaviours of Tm3+ in TmPO4, YPO4 and LuPO4: a comparative study

    NASA Astrophysics Data System (ADS)

    Chakrabarti, P. K.; Chattopadhyay, K. N.; Modak, S.; Mondal, J.

    2007-02-01

    Single crystals of thulium phosphates (TmPO4) are grown and the principal magnetic susceptibility perpendicular to the symmetry axis ‘c’ of the crystal 2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaWaaeWaaeaaca% qGhpWaaSbaaSqaaiabgwQiEbqabaaakiaawIcacaGLPaaaaaa!3AAA! left( {{text{ ? }}_ bot } right) and the magnetic anisotropy 2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaeyiLdqKaae% 4XdmaabmaabaGaaeypaiaabE8adaWgaaWcbaGaeSyjIafabeaakiab% gkHiTiaabE8adaWgaaWcbaGaeyyPI4fabeaaaOGaayjkaiaawMcaaa% aa!41B6! ? {text{ ? }}left( {{text{ = ? }}_allel - {text{ ? }}_ bot } right) are measured in the temperature range 300-13.5 K and 300-80 K, respectively. Though 2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaae4XdmaaBa% aaleaacqGHLkIxaeqaaaaa!3917! {text{ ? }}_ bot increases rapidly with the decrease of temperature, 2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaae4XdmaaBa% aaleaacqWILicuaeqaaaaa!388E! {text{ ? }}_allel increases very slowly with the lowering of temperature. The tetragonal crystal structure of TmPO4 is similar to that of Tm3+ in YPO4 and LuPO4 and in all the cases the non-Kramers Tm3+ ion occupies a site of D2d symmetry. Our observed magnetic data on TmPO4 are analyzed using crystal field analysis where the Hamiltonian includes the atomic free ion and crystal field (one-electron) interaction term. The computed and measured paramagnetic susceptibilities of TmPO4 agree very well in the temperature range of our study. The magnetic behaviours of Tm3+ in YPO4 and LuPO4 are also studied and the results are compared with that of TmPO4. In all the cases the natures of thermal variations of average susceptibilities and magnetic anisotropies are mostly governed by the perpendicular susceptibilities as their values are higher and rapidly increase with the lowering of temperature compared to parallel susceptibilities. The computed nuclear quadruple splittings, electronic heat capacities of Tm3+ in three different hosts give some interesting results.

  12. Competition between the inter- and intra-sublattice interactions in Yb2V2O7

    NASA Astrophysics Data System (ADS)

    Dun, Zhiling; Ma, Jie; Cao, Huibo; Hong, Tao; Matsuda, Masaaki; Qiu, Yiming; Copley, John; Cheng, Jinguang; Lee, Minseong; Choi, Eunsang; Johnston, Steve; Zhou, Haidong

    2015-03-01

    We studied single crystals of Yb2V2O7 using dc and ac susceptibility measurements, elastic and inelastic neutron scattering measurements, and linear spin wave theory. The experimental data shows a ferromagnetic ordering of V4+ ions at 70 K, a short-range ordering of Yb3+ ions below 40 K, and finally a long-range non-collinear ordering of Yb3+ ions below 15 K. With external magnetic field oriented along the [111] axis, the Yb-sublattice experiences a spin flop transition related to the ``three-in one-out'' spin structure. By modeling the spin wave excitations, we extract the Hamiltonian parameters. Our results confirm that although the extra inter-sublattice Yb-V interactions dramatically increases the Yb ordering temperature to 15 K, the intra-sublattice Yb-Yb interactions, based on the pyrochlore lattice, still stabilize the Yb ions' non-collinear spin structure and spin flop transition.

  13. Crystal growth and luminescence properties of Yb-doped aluminate, gallate, phosphate and vanadate single crystals

    NASA Astrophysics Data System (ADS)

    Yoshikawa, A.; Nikl, M.; Ogino, H.; Shim, J. B.; Kochurikhin, V. V.; Solovieva, N.; Fukuda, T.

    2005-01-01

    (Lu1-xYbx)3Al5O12 (Yb:LuAG), (Y1-xYbx)AlO3 (Yb:YAP), (Y0.9Yb0.1)VO4 (Yb:YVO) and Ca8(La1.98Yb0.02)(PO4)6O2 (Yb:CLPA) single crystals were grown from the melt. Typical double peak spectrum of the Yb3+ Charge Transfer (CT) luminescence was observed in Yb-doped LuAG and YAP. Strong dependence of decay time and intensity on temperature was observed. Concentration quenching effect in Yb-rich Yb:YAP samples results in pronounced 1/e decay time shortening below 230 K, while above this temperature the decay curves are shaped mostly by the thermal quenching process. Double peak emission spectrum was not observed in Yb:YVO and Yb:CLPA. In the case of CLPA, under excitation in the Yb3+ CT absorption band round 270 nm both the fast (6 ns decay time) and slow components (about 150 ?s+600 ?s decay times) are observed at room temperature. CLPA emission intensity was not decreasing with temperature between 80 and 300 K. Mixing of the Yb3+ CT and CLPA excitonic states is proposed to explain this interesting phenomenon.

  14. 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.

  15. Multimodal bioimaging using rare earth doped Gd2O2S: Yb/Er phosphor with upconversion luminescence and magnetic resonance properties

    PubMed Central

    Ajithkumar, G.; Yoo, Benjamin; Goral, Dara E.; Hornsby, Peter J.; Lin, Ai-Ling; Ladiwala, Uma; Dravid, Vinayak P.; Sardar, Dhiraj K

    2013-01-01

    While infrared upconversion imaging using halide nanoparticles are so common the search for a very efficient halide free upconverting phosphors is still lacking. In this article we report Gd2O2S:Yb/Er,YbHo,YbTm systems as a very efficient alternative phosphors that show upconversion efficiency comparable or even higher than existing halide phosphors. While the majority of rare earth dopants provide the necessary features for optical imaging, the paramagnetic Gd ion also contributes to the magnetic imaging,thereby resulting in a system with bimodal imaging features. Results from imaging of the nanoparticles together with aggregates of cultured cells have suggested that imaging of the particles in living animals may be possible. In vitro tests revealed no signficant toxicity because no cell death was observed when the nanoparticles were in the presence of growing cells in culture. Measurement of the magnetization of the phosphor shows that the particles are strongly magnetic, thus making them suitable as an MRI agent. PMID:25191618

  16. From the Ternary Eu(Au/In)2 and EuAu4(Au/In)2 with Remarkable Au/In Distributions to a New Structure Type: The Gold-Rich Eu5Au16(Au/In)6 Structure.

    PubMed

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

    2015-09-01

    The ternary Eu(Au/In)2 (EuAu(0.46)In(1.54(2))) (I), EuAu4(Au/In)2 (EuAu(4+x)In(2-x) with x = 0.75(2) (II), 0.93(2), and 1.03(2)), and Eu5Au16(Au/In)6 (Eu5Au(17.29)In(4.71(3))) (III) have been synthesized, and their structures were characterized by single-crystal X-ray diffraction. I and II crystallize with the CeCu2-type (Pearson Symbol oI12; Imma; Z = 4; a = 4.9018(4) Å; b = 7.8237(5) Å; c = 8.4457(5) Å) and the YbAl4Mo2-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 of an Au/In-mixed diamond-related host lattice encapsulating Eu atoms, while the structure of II features ribbons of distorted, squared Au8 prisms enclosing Eu, Au, and In atoms. Combination of these structural motifs leads to a new structure type as observed for Eu5Au16(Au/In)6 (Eu5Au(17.29)In(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 EuAu2-"EuAu4In2". The site preferences of the disordered Au/In positions in II were investigated for different hypothetical "EuAu4(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. A chemical bonding analysis on two "EuAu5In" and "EuAu4In2" 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. PMID:26270622

  17. Monodisperse and core-shell structured SiO{sub 2}-Lu{sub 2}O{sub 3}:Ln{sup 3+} (Ln=Eu, Tb, Dy, Sm, Er, Ho, and Tm) spherical particles: A facile synthesis and luminescent properties

    SciTech Connect

    Xu, Zhenhe; Feng, Bin; Bian, Shasha; Liu, Tao; Wang, Mingli; Gao, Yu; Sun, Di; Gao, Xin; Sun, Yaguang

    2012-12-15

    The core-shell structured SiO{sub 2}-Lu{sub 2}O{sub 3}:Ln{sup 3+} particles were realized by coating the Lu{sub 2}O{sub 3}:Ln{sup 3+} phosphors onto the surface of non-aggregated, monodisperse and spherical SiO{sub 2} particles by the Pechini sol-gel method. The as-synthesized products were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), energy-dispersive X-ray (EDX) spectra, scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), photolumiminescence (PL), and low-voltage cathodoluminescence (CL). The results indicate that the 800 Degree-Sign C annealed sample consists of crystalline Lu{sub 2}O{sub 3} shells and amorphous SiO{sub 2} cores, in spherical shape with a narrow size distribution. The as-obtained particles show strong light emission with different colors corresponding to different Ln{sup 3+} ions under ultraviolet-visible light excitation and low-voltage electron beams excitation, which have potential applications in fluorescent lamps and field emission displays. - Graphical Abstract: Representative SEM and TEM images of the core-shell structured SiO{sub 2}-Lu{sub 2}O{sub 3}:Eu{sup 3+} particles; CIE chromaticity diagram showing the emission colors for SiO{sub 2}-Lu{sub 2}O{sub 3}:Ln{sup 3+}; Multicolor emissions of SiO{sub 2}-Lu{sub 2}O{sub 3}:Ln{sup 3+} particles. Highlights: Black-Right-Pointing-Pointer The core-shell particles were realized by coating the phosphors onto the surface of SiO{sub 2} particles. Black-Right-Pointing-Pointer The sample consists of crystalline Lu{sub 2}O{sub 3} shells and amorphous SiO{sub 2} cores. Black-Right-Pointing-Pointer The particles show different light emission colors corresponding to Ln{sup 3+} ions. Black-Right-Pointing-Pointer They have potential applications in fluorescent lamps and field emission displays.

  18. Yb :CALGO as material for high power ultrafast laser and focus on thermal conductivity variation

    NASA Astrophysics Data System (ADS)

    Jaffrès, A.; Ricaud, S.; Suganuma, A.; Viana, B.; Loiseau, P.; Georges, P.; Druon, F.

    2013-03-01

    Thermal conductivity values of laser material Yb3+:CaGdAlO4 (CALGO) with various doping rate in Yb3+ were measured experimentally and compared to predictive values obtained by modelling. The observed variation of the thermal conductivity with the Yb3+ content could be explained by changing the ratio of site substitution Gd3+/Ca2+ by Yb3+. The influence of velocity sound and interionic distance values on thermal conductivity was also studied. Finally, laser results obtained with a 2%Yb:CALGO thin-disk were presented, strengthening the potential of Yb:CALGO for high power laser and ultra-short pulses generation.

  19. Creation of Yb2O3 Nanoprecipitates Through an Oxidation Process in Bulk Yb-Filled Skutterudites

    NASA Astrophysics Data System (ADS)

    Ding, Juan; Gu, Hui; Qiu, Pengfei; Chen, Xihong; Xiong, Zhen; Zheng, Qiang; Shi, Xun; Chen, Lidong

    2013-03-01

    An approach to introduce in situ nanoprecipitates into bulk filled skutterudites is developed through controlling the oxidation process of the fillers. Yb0.3Co4Sb12 is selected as the base material, and prolonged oxidation at high temperatures in sealed quartz tubes under a low pressure of oxygen leads to the formation of Yb2O3 nanoinclusions. Transmission electron microscopy shows that the Yb2O3 nanoprecipitates are created within the skutterudite crystal grains through an internal oxidation mechanism. With increased time of oxidation, the amount of Yb2O3 nanoprecipitates is increased and the nanoprecipitates are more uniformly distributed in the matrix. For the samples oxidized for 10 days, the lattice thermal conductivity is reduced by about 19% at 850 K compared with the Yb0.3Co4Sb12 matrix. The reduction in the lattice thermal conductivity originates from additional phonon scattering by the Yb2O3 nanoprecipitates, leading to a maximum ZT of 1.3.

  20. HSP60 interacts with YB-1 and affects its polysome association and subcellular localization

    SciTech Connect

    Ohashi, Sachiyo; Atsumi, Megumi; Kobayashi, Shunsuke

    2009-08-07

    YB-1 is a DNA/RNA-binding protein which, in the cytoplasm, associates with polysomes and regulates translation. However, YB-1 has a novel nuclear localization signal, and its nuclear accumulation is correlated with cancer induction. Here we designated the amino-acid sequence as YB-NLS and demonstrated that YB-NLS is necessary for the nuclear translocation of overexpressed YB-1 in NG108-15 cells. In addition, we found that a heat shock protein, HSP60, binds to YB-NLS in the cytoplasm. Interestingly, when HSP60 expression was repressed, an increase of polysome-associated YB-1 was observed in heavy-sedimenting fractions on a sucrose gradient. Overexpression of HSP60 resulted in a decrease of YB-1 in the heavy-sedimenting fractions and suppression of YB-NLS activity. Furthermore, the NLS-deleted YB-1 was apparently associated with the heavy-sedimenting polysomes. These results suggest that HSP60 interacts with YB-1 at the YB-NLS region and acts as a regulator of polysome association and the subcellular distribution of YB-1.

  1. 77 FR 71590 - Lock+TM

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-12-03

    ... From the Federal Register Online via the Government Printing Office DEPARTMENT OF ENERGY Federal Energy Regulatory Commission Lock+ TM Hydro Friends Fund XI, LLC; Notice of Preliminary Permit Application Accepted for Filing and Soliciting Comments, Motions To Intervene, and Competing Applications On October 1, 2012, Lock+ TM Hydro Friends Fund...

  2. Sun StorageTekTM Security Policy

    E-print Network

    Sun StorageTekTM T9840D Tape Drive Security Policy Part Number 316055201 Revision: AA Sun Microsystems, Inc. February 5, 2010 Copyright Sun Microsystems 2009. May be reproduced only in its original entirety [without revision]. #12;Sun Microsystems Sun StorageTek TM T9840D Tape Drive Security Policy

  3. A Review of "Integrity[TM]"

    ERIC Educational Resources Information Center

    Veldkamp, Bernard P.

    2008-01-01

    Integrity[TM], an online application for testing both the statistical integrity of the test and the academic integrity of the examinees, was evaluated for this review. Program features and the program output are described. An overview of the statistics in Integrity[TM] is provided, and the application is illustrated with a small simulation study.…

  4. Thermal and laser properties of Yb:LuAG for kW thin disk lasers.

    PubMed

    Beil, Kolja; Fredrich-Thornton, Susanne T; Tellkamp, Friedjof; Peters, Rigo; Kränkel, Christian; Petermann, Klaus; Huber, Günter

    2010-09-27

    Thin disk laser experiments with Yb:LuAG (Yb:Lu(3)Al(5)O(12)) were performed leading to 5 kW of output power and an optical-to-optical efficiency exceeding 60%. Comparative analyses of the laser relevant parameters of Yb:LuAG and Yb:YAG were carried out. While the spectroscopic properties were found to be nearly identical, investigations of the thermal conductivities revealed a 20% higher value for Yb:LuAG at Yb(3+)-doping concentrations of about 10%. Due to the superior thermal conductivity with respect to Yb:YAG, Yb:LuAG offers thus the potential of improved performance in high power thin disk laser applications. PMID:20940967

  5. Full phase stabilization of a Yb:fiber femtosecond frequency comb

    E-print Network

    of an amplified Yb:fiber femtosecond frequency comb using an intracavity electro-optic modulator and an acousto in a Yb:fiber oscillator [6] and broad bandwidth of electro-optical modulators (EOMs) in Er

  6. High-pressure synthesis, crystal structure, and structural relationship of the first ytterbium fluoride borate Yb{sub 5}(BO{sub 3}){sub 2}F{sub 9}

    SciTech Connect

    Haberer, Almut; Huppertz, Hubert

    2009-04-15

    Yb{sub 5}(BO{sub 3}){sub 2}F{sub 9} was synthesized under high-pressure/high-temperature conditions in a Walker-type multianvil apparatus at 7.5 GPa and 1100 deg. C, representing the first known ytterbium fluoride borate. The compound exhibits isolated BO{sub 3}-groups next to ytterbium cations and fluoride anions, showing a structure closely related to the other known rare-earth fluoride borates RE{sub 3}(BO{sub 3}){sub 2}F{sub 3} (RE=Sm, Eu, Gd) and Gd{sub 2}(BO{sub 3})F{sub 3}. Monoclinic Yb{sub 5}(BO{sub 3}){sub 2}F{sub 9} crystallizes in space group C2/c with the lattice parameters a=2028.2(4) pm, b=602.5(2) pm, c=820.4(2) pm, and beta=100.63(3){sup o} (Z=4). Three different ytterbium cations can be identified in the crystal structure, each coordinated by nine fluoride and oxygen anions. None of the five crystallographically independent fluoride ions is coordinated by boron atoms, solely by trigonally-planar arranged ytterbium cations. In close proximity to the above mentioned compounds RE{sub 3}(BO{sub 3}){sub 2}F{sub 3} (RE=Sm, Eu, Gd) and Gd{sub 2}(BO{sub 3})F{sub 3}, Yb{sub 5}(BO{sub 3}){sub 2}F{sub 9} can be described via alternating layers with the formal compositions 'YbBO{sub 3}' and 'YbF{sub 3}' in the bc-plane. - Graphical abstract: High-pressure/high-temperature synthesis (multianvil technique) led to the first ytterbium fluoride borate Yb{sub 5}(BO{sub 3}){sub 2}F{sub 9}, built up from isolated BO{sub 3}-groups. The compound shows structural relations to the known rare-earth fluoride borates RE{sub 3}(BO{sub 3}){sub 2}F{sub 3} (RE=Sm, Eu, Gd) and Gd{sub 2}(BO{sub 3})F{sub 3}.

  7. Spectroscopic properties of Er3+, Yb3 + and Er3 + /Yb3+ doped metaphosphate glasses.

    PubMed

    Speghini, A; Francini, R; Martinez, A; Tavernese, M; Bettinell, M

    2001-09-01

    The absorption and emission spectroscopies of Er3+ doped and Er3+/Yb3+ codoped Ca(PO3)2, Sr(PO3)2 and Ba(PO3)2 glasses have been studied. From the Judd-Ofelt intensity parameters, the spontaneous emission probabilities of some relevant transitions and the radiative lifetimes of several excited states of Er3+ have been calculated. The decay curves of the Er3+ emission at 1.5 microm have been measured at different temperatures. The data have been fitted using a stretched exponential function and the obtained experimental lifetimes have been compared with the calculated radiative lifetimes. The difference between the experimental and calculated lifetimes is attributed to the presence of traces of OH groups in the host glasses. The absolute OH content in some glasses has been determined from the infrared spectra. The emission spectra at 1.5 microm of the Er3+ ion in the codoped glasses have been measured at different temperatures. The integrated emission intensities decrease significantly on passing from room temperature to 13 K, suggesting a temperature dependence of the rate of the energy transfer process between Yb3+ and Er3+. PMID:11666080

  8. Preparation and characterization of Yb-doped YAG ceramics

    NASA Astrophysics Data System (ADS)

    Hostaša, Jan; Esposito, Laura; Alderighi, Daniele; Pirri, Angela

    2013-02-01

    This work presents the results of the preparation of polycrystalline Yb:YAG ceramics for laser sources with dopant concentration from 0 up to 20 at.% via solid state reactive sintering. Samples were prepared via cold isostatic pressing of spray dried mixture of pure oxide powders with TEOS as a sintering aid. Sintering was conducted under high vacuum and clean atmosphere. Various sintering cycles were tested, so that optimum conditions could be selected in dependence on Yb concentration. Samples with optical transmittance higher than 80% were prepared and their laser performance was examined. Slope efficiency as high as 73% and a maximum output power of 6 W were obtained for the sample doped with 10% Yb. Final microstructure of prepared samples was analyzed via optical microscopy, scanning and transmission electron microscopy, and EDS.

  9. 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.

  10. Wobbling excitations in 156Dy and 162Yb

    E-print Network

    Jan Kvasil; Rashid G. Nazmitdinov

    2006-11-16

    We study in the cranked Nilsson plus random phase approximation low-lying quadrupole excitations of positive parity and negative signature in 156Dy and 162Yb at high spins. Special attention is paid to a consistent description of wobbling excitations and their identification among excited states. A good agreement between available experimental data and the results of calculations is obtained. We found that in 156Dy the lowest odd spin gamma-vibrational states transform to the wobbling excitations after the backbending, associated with the transition from axially-symmetric to nonaxial shapes. Similar results are predicted for 162Yb. The analysis of electromagnetic transitions, related to the wobbling excitations, determines uniquely the sign of the gamma-deformation in 156Dy and 162Yb after the transition point.

  11. 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. PMID:26037219

  12. Growth and characterization of Yb 3+ doped garnet crystals for scintillator application

    NASA Astrophysics Data System (ADS)

    Ogino, Hiraku; Yoshikawa, Akira; Lee, Jong-Ho; Nikl, Martin; Solovieva, Natalia; Fukuda, Tsuguo

    2004-09-01

    Several concentration of Yb-doped Lu 3Al 5O 12 (Yb:LuAG) and Lu 3Ga 5O 12 (Yb:LGG) single crystals were grown by the micro-pulling-down method. The crystals were seeded-grown in the <1 1 1> direction and transparent and crack free crystals were obtained. Photoluminescence spectra and decay kinetics of these crystals were studied. Charge transfer luminescence of Yb 3+ was observed in both crystals. Mean decay time of about 25 ns at 90 K and strong thermal quenching at room temperature was measured for Yb 5%:LuAG. Radioluminescence intensity was compared to the standard BGO sample.

  13. High pressure synthesis of a new phase of YbAg2: Structure, valence of Yb and properties

    SciTech Connect

    Tsvyashchenko, A. V.; Menushenkov, A. P.; Sidorov, V. A.; Petrova, A. E.; Fomicheva, L. N.; Chernysheva, O. V.; Lebed, Yu. B.; Axenov, S. N.; Bud’ko, S. L.; Sun, Liling; Zhao, Zhongxian

    2015-08-05

    The new phase of YbAg2 was obtained using high-pressure and high-temperature reaction. YbAg2 crystallizes in the MgZn2 structure (the space group P63/mmc space group, No 194) with a = 5.68153(3) Å and c = 9.31995(7) Å and the unit cell volumeV = 260.54(3) Å3. 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 T2 term that supports the Fermi-liquid picture. Furthermore, the Kadowaki–Woods relation gives a low value of the degeneracy (N = 2).

  14. High pressure synthesis of a new phase of YbAg2: Structure, valence of Yb and properties

    DOE PAGESBeta

    Tsvyashchenko, A. V.; Menushenkov, A. P.; Sidorov, V. A.; Petrova, A. E.; Fomicheva, L. N.; Chernysheva, O. V.; Lebed, Yu. B.; Axenov, S. N.; Bud’ko, S. L.; Sun, Liling; et al

    2015-08-05

    The new phase of YbAg2 was obtained using high-pressure and high-temperature reaction. YbAg2 crystallizes in the MgZn2 structure (the space group P63/mmc space group, No 194) with a = 5.68153(3) Å and c = 9.31995(7) Å and the unit cell volumeV = 260.54(3) Å3. 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 T2 term that supports the Fermi-liquid picture. Furthermore, the Kadowaki–Woods relation gives a low value of the degeneracy (N = 2).

  15. Growth and scintillation properties of Yb doped aluminate, vanadate and silicate single crystals

    NASA Astrophysics Data System (ADS)

    Yoshikawa, A.; Ogino, H.; Shim, J. B.; Kochurikin, V. V.; Nikl, M.; Solovieva, N.; Ono, S.; Sarukura, N.; Kikuchi, M.; Fukuda, T.

    2004-09-01

    For the purpose of quick screening for charge transfer (CT) transitions of Yb 3+ in various hosts, (Lu 1- xYb x) 3Al 5O 12 (Yb:LuAG) with x=0.05, 0.15, 0.30 and (Y 1- xYb x)AlO 3 (Yb:YAP) with x=0.05, 0.10, 0.30 were grown by the micro-pulling-down method. (Y,Yb)VO 4 with strong wetting was grown by edge defined film-fed growth method and materials, which require moderate temperature gradient, such as Ca 8(La,Yb) 2(PO 4) 6O 2 and (Gd,Yb) 2SiO 5 were grown by Czochralski method. Strong dependence of the CT luminescence decay time and intensity on temperature was observed for Yb-doped LuAG and YAP. Super fast decay with 0.85 ns decay time was observed in Yb(30%) doped YAP at room temperature. Though the emission intensity is weak at room temperature, it exceeds several times that of PbWO 4. In addition, CT luminescence of Yb:YAP occurs at longer wavelength than in BaF 2, which enables the usage of glass-based photomultiplier for the detection. In addition, higher stopping power will be expected due to the higher density host compared with BaF 2.

  16. Thermoelectric properties of Yb-filled CoSb3 skutterudites

    NASA Astrophysics Data System (ADS)

    Park, Kwan-Ho; Seo, Won-Seon; Shin, Dong-Kil; Kim, Il-Ho

    2014-08-01

    Yb-filled skutterudites Yb z Co4Sb12 (z = 0, 0.1, 0.2, 0.3, 0.4) were prepared by encapsulated melting and hot pressing. The filling effects of Yb on the transport and the thermoelectric properties of the skutterudites were examined. In the case of z ? 0.3, a secondary phase (YbSb2) was formed, indicating that the filling fraction limit of Yb was z = 0.2 - 0.3. The intrinsic CoSb3 had a high positive Seebeck coefficient, but Yb-filled CoSb3 exhibited a negative Seebeck coefficient. In the case of z ? 0.1, the maximum absolute value of the Seebeck coefficient was | -231| ?VK-1, and in the case of z ? 0.2, the absolute value of the Seebeck coefficient increased with increasing temperature. The electrical conductivity increased and the Seebeck coefficient decreased with increasing Yb filling content due to the increased carrier concentration. The thermal conductivity was reduced significantly by Yb filling, mainly due to a decrease in the lattice thermal conductivity. Also, the lattice thermal conductivity decreased with increasing Yb filling content, indicating that the phonon scattering was caused by the rattling of Yb fillers in the voids of the skutterudite structure. Yb0.2Co4Sb12 showed the highest figure of merit of 1.0 at 823 K.

  17. ORNL/TM-13722 DESCRIPTION OF SURVEY

    E-print Network

    Pennycook, Steve

    ORNL/TM-13722 DESCRIPTION OF SURVEY DATA REGARDING THE CHEMICAL REPACKAGING PLANT ACCIDENT OF SURVEY DATA REGARDING THE CHEMICAL REPACKAGING PLANT ACCIDENT WEST HELENA, ARKANSAS Barbara Muller.1. SURVEY DATA........................................................................................... 13

  18. Influence of the melting atmosphere on Yb3+/Al3+ co-doped silica glass with powder melting technology

    NASA Astrophysics Data System (ADS)

    Wang, Chao; Zhou, Guiyao; Xia, Changming; Han, Ying; Zhao, Xingtao; Zhang, Wei; Wang, Wei

    2014-03-01

    We demonstrated the formation of Yb2+ ions in Yb3+/Al3+ co-doped silica glass using the powder melting technology based on the high-frequency plasma furnace. The Yb3+ ions can be deoxidated into Yb2+ ions under the atmosphere of N2 or Ar. The appearance and optical properties of the Yb3+/Al3+ co-doped silica glass are also changed.

  19. Local laser cooling of Yb:YLF to 110 K.

    PubMed

    Seletskiy, Denis V; Melgaard, Seth D; Epstein, Richard I; Di Lieto, Alberto; Tonelli, Mauro; Sheik-Bahae, Mansoor

    2011-09-12

    Minimum achievable temperature of ~110 K is measured in a 5% doped Yb:YLF crystal at ? = 1020 nm, corresponding to E4-E5 resonance of Stark manifold. This measurement is in excellent agreement with the laser cooling model and was made possible by employing a novel and sensitive implementation of differential luminescence thermometry using balanced photo-detectors. PMID:21935189

  20. Multimodal microscopy with sub-30 fs Yb fiber laser oscillator

    PubMed Central

    Nie, Bai; Saytashev, Ilyas; Chong, Andy; Liu, Hui; Arkhipov, Sergey N.; Wise, Frank W.; Dantus, Marcos

    2012-01-01

    Nonlinear optical microscopy with sub-30 fs pulses from an Yb-fiber laser, approximately three times shorter than typical fiber laser pulses, leads to an order of magnitude brighter third harmonic generation imaging. Multiphoton fluorescence, second and third harmonic generation modalities are compared on stained microspheres and unstained biological tissues. PMID:22808444

  1. Modeling Cr-to-Tm and Cr-to-Tm-to-Ho energy transfer in YAG crystals

    NASA Technical Reports Server (NTRS)

    Swetits, John J.

    1991-01-01

    A systematic analysis of energy transfer processes in crystals of YAG doped with varying concentrations of Cr and Tm is described. Both spectral measurements and measurements of the temporal response to pulsed excitation are used to give independent determinations of the microscopic interaction parameter for Cr to Tm transfer. The different factors in influencing the temperature dependence of the Cr to Tm transfer are discussed. The dependence of the Tm cross-relaxation rate on Tm concentration is determined.

  2. EU Space Awareness: Initial implemenation

    NASA Astrophysics Data System (ADS)

    Russo, Pedro

    2015-08-01

    EU Space Awareness uses the excitement of space to attract young people into science and technology and stimulate European and global citizenship. The project will show children and teenagers the opportunities offered by space science and engineering and inspire primary-school children when their curiosity is high and their value systems are being formed. EU Space Awareness, a 3-year project, has started in March 2015 with 10 partner organisations and 15 network nodes in 17 European countries and the IAU Office of Astronomy for Development. During this talk we will give a update about the intial implementation of the project and its relevant for astronomy for development.

  3. Gibbs energy of formation of Cu{sub 2}Yb{sub 2}O{sub 5} and thermodynamic stability of Cu{sub 2}R{sub 2}O{sub 5} (R = Tb-Lu)

    SciTech Connect

    Kale, G.M.

    1996-08-01

    The electromotive force (emf) of the solid oxide electrochemical cell, (-)Pt/Cu{sub 2}O + Yb{sub 2}O{sub 3} + Cu{sub 2}Yb{sub 2}O{sub 5}//(CaO)ZrO{sub 2}//O{sub 2}(P = 0.0212 MPa)/Pt(+), has been measured between 960 and 1320 K. Based on the measured emf of the above cell as a function of temperature, the Gibbs energy change for the reaction 2Cu{sub 2}O(s) + 2Yb{sub 2}O{sub 3}(s) + O{sub 2}(g) {yields} 2Cu{sub 2}Yb{sub 2}O{sub 5}(s) is obtained as {Delta}G{degrees} = {minus}231,225 + 151.847T ({plus_minus}200) J mol{sup {minus}1}. The Gibbs energy change for the above reaction when combined with that for Cu{sub 2}O + CuO equilibrium from the literature gives, for the reaction 2CuO(s) + Yb{sub 2}O{sub 3}(s) + Yb{sub 2}O{sub 3}(s) {yields} Cu{sub 2}Yb{sub 2}O{sub 5}(s), {Delta}G{degrees} = 17,128 {minus} 20.07T ({plus_minus}100) J mol{sup {minus}1}. It can be seen that the formation of Cu{sub 2}Yb{sub 2}O{sub 5} from the component oxides is endothermic. Since Cu{sub 2}Yb{sub 2}O{sub 5} is an entropy stabilized compound and its formation is endothermic from component oxides, Cu{sub 2}Yb{sub 2}O{sub 5} is thermodynamically unstable relative to its component oxides below 853 K. Earlier we reported the Gibbs energy of formation of Cu{sub 2}Dy{sub 2}O{sub 5}, Cu{sub 2}Ho{sub 2}O{sub 5}, and Cu{sub 2}Er{sub 2}O{sub 5} from CuO and R{sub 2}O{sub 3}(R = Dy, Ho, Er). Since Cu{sub 2}Yb{sub 2}O{sub 5} is also a member of the Cu{sub 2}R{sub 2}O{sub 5} family of compounds whose crystal structure belongs to a noncentrosymmetric space group P2{sub 1}nb, an attempt has been made to correlate their thermodynamic properties such as enthalpy and entropy of formation with the ionic radius of the trivalent rare-earth cation present in octahedral coordination. Based on this correlation, {Delta}H, {Delta}S, and {Delta}G for the formation of Cu{sub 2}Tb{sub 2}O{sub 5}, Cu{sub 2}Tm{sub 2}O{sub 5}, and Cu{sub 2}Lu{sub 2}O{sub 5} from the component oxides have been estimated.

  4. Nanocrystallization in Yb3+-doped oxyfluoride glasses for laser cooling

    NASA Astrophysics Data System (ADS)

    Kummara, Venkata Krishaniah; Ledemi, Yannick; Soares de Lima Filho, Elton; Messaddeq, Younes; Kashyap, Raman

    2015-03-01

    Glass-ceramics are composite materials consisting of crystals which are controllably grown within a glass matrix usually by applying an appropriate heat treatment. They possess outstanding optical properties with applications in solid state lasers, optical amplifiers, and now, laser induced cooling. For laser cooling, the material should exhibit specific properties like low phonon energy environment around the lanthanide ions, low background losses, high transparency and high photoluminescence quantum yield. In the present study, oxyfluoride glasses and ultra-transparent nano glassceramics doped with different concentrations (2, 5, 8, 12, 16 and 20 mol %) of Yb 3+ ions have been prepared by conventional melt-quenching and subsequent thermal treatments at different temperatures, respectively. Differential scanning calorimetry (DSC) and X-ray diffraction (XRD) measurements have been performed to characterize the thermal properties of the glass and the structural changes in the glass-ceramics, respectively. The XRD patterns confirm the growth of ?-PbF2 nanocrystals as well as progressive incorporation of Yb 3+ ions. This enhances the Yb 3+ ion emission intensity which depends on the doping concentration and ceramization temperatures. The size (20 nm) of the nanocrystallites was estimated from the Sherrer's formula and found to increase with increasing ceramization temperature, small enough to avoid scattering losses and ensure an excellent transparency of the glass-ceramics comparable with that of the parent glass. An enhancement of the luminescence properties of Yb 3+ ions surrounded by a crystalline low phonon environment is observed. Finally, the utilization of these heavily Yb 3+-doped ultra-transparent materials for laser cooling and solid state laser applications is discussed.

  5. 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 functional groups but also as a substrate inducing the nucleation of phosphate nanoparticles. Stable nano-sized Yb phosphate precipitates formed on yeast cell surfaces in the present study, which implies that this post-adsorption nano-particle formation process caused by microbial cells should be one of the important processes governing the long-term migration of heavy rare earth elements and presumably trivalent actinides in geological repository.

  6. COMPOSITE TECHNOLOGY DEVELOPMENT INC. CryoCoatTM UltraLightTM

    E-print Network

    McDonald, Kirk

    : Adhesives Thermal Insulation Protective Coatings Each layer can be optimized gives best system performance Change to LHe Stop LHe Flow Insulation Thickness Approx. 1 1/2" LN2 Pre-Cool Thermal Time HistoryCOMPOSITE TECHNOLOGY DEVELOPMENT INC. CTD CryoCoatTM UltraLightTM Insulation presented by: Michael

  7. Concurrent Validity of LibQUAL+[TM] Scores: What Do LibQUAL+[TM] Scores Measure?

    ERIC Educational Resources Information Center

    Thompson, Bruce; Cook, Colleen; Kyrillidou, Martha

    2005-01-01

    The present study investigated the validity of LibQUAL+[TM] scores, and specifically how total and subscale LibQUAL+[TM] scores are associated with self-reported, library-related satisfaction and outcomes scores. Participants included 88,664 students and faculty who completed the American English (n[AE] = 69,494) or the British English (n[BE] =…

  8. QCD For Intel(R) Xeon Phi(tm) and Xeon(tm) processors

    SciTech Connect

    2014-09-11

    This library provides a library containing highly optimized Wilson-Dslash, Wilson Clover operator and Krylov subspace solvers for Lattice QCD simulations. The library is targeted at Intel(R) Xeon Phi(tm), and Intel(R) Xeon(tm) processors.

  9. Conductor: A Framework for Distributed Adaptation ^TM ^TM Mark Yarvis, Peter Reiher, and Gerald J. Popek ~

    E-print Network

    California at Los Angeles, University of

    Conductor: A Framework for Distributed Adaptation ^TM ^TM Mark Yarvis, Peter Reiher, and Gerald J of multiple adapting agents at various points in a network can extend these benefits. Conductor demonstrates an approach toward selecting an appropriate set of adaptive agents and a plan for their deployment. Conductor

  10. Crystal growth of Yb 3+-doped oxide single crystals for scintillator application

    NASA Astrophysics Data System (ADS)

    Yoshikawa, Akira; Nikl, Martin; Ogino, Hiraku; Lee, Jong-Ho; Fukuda, Tsuguo

    2003-03-01

    Long emission wavelength scintillators are strongly required from the viewpoint of the practical use of silicon photo-diode, which has higher resolution with lower cost compared with photo-multipllier. Among the various scintillator emission centers, we regard emission from Yb 3+ charge-transitions state (CTS) as a candidate. In order to investigate proper hosts for Yb 3+ CTS, the yttrium gallium garnet host and lutetium aluminum garnet host were studied. Transparent and crack-free heavily Yb-doped YGG, i.e. {Y 1- xYb x} 3[Ga] 2(Ga) 3O 12 (Yb: YGG, x=0.15, 0.5, 1.0) and heavily Yb-doped LuAG, i.e. {Lu 1- xYb x} 3[Al] 2(Al) 3O 12 (Yb: LuAG, x=0.15, 0.5, 1.0) single crystals could be grown by the Modified Pulling Down method with <1 1 1> orientation. Emission, excitation spectra and decay kinetics were measured for these crystals. The CT transition of Yb 3+ in the yttrium gallium garnet host was discussed compared with the Yb 3+ one in the lutetium aluminum garnet host.

  11. Role of electron transfer in Ce3+ sensitized Yb3+ luminescence in borate glass

    NASA Astrophysics Data System (ADS)

    Sontakke, Atul D.; Ueda, Jumpei; Katayama, Yumiko; Zhuang, Yixi; Dorenbos, Pieter; Tanabe, Setsuhisa

    2015-01-01

    In a Ce3+-Yb3+ system, two mechanisms are proposed so far namely, the quantum cutting mechanism and the electron transfer mechanism explaining Yb3+ infrared luminescence under Ce3+ excitation. Among them, the quantum cutting mechanism, where one Ce3+ photon (ultraviolet/blue) gives rise to two Yb3+ photons (near infrared) is widely sought for because of its huge potential in enhancing the solar cell efficiency. In present study on Ce3+-Yb3+ codoped borate glasses, Ce3+ sensitized Yb3+ luminescence at ˜1 ?m have been observed on Ce3+ 5d state excitation. However, the intensity of sensitized Yb3+ luminescence is found to be very weak compared to the strong quenching occurred in Ce3+ luminescence in Yb3+ codoped glasses. Moreover, the absolute luminescence quantum yield also showed a decreasing trend with Yb3+ 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 Ce3+-Yb3+ ? Ce4+-Yb2+ 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.

  12. Preparation and Thermoelectric Properties of YbAl3 Thermoelectric Materials with Excessive Al

    NASA Astrophysics Data System (ADS)

    He, Dan-qi; Zhao, Wen-Yu; Mu, Xin; Zhou, Hong-yu; Zhang, Qing-jie

    2015-06-01

    A method to prepare YbAl3 sample with an accurate stoichiometric ratio has been developed by a melting, quenching, annealing and spark plasma sintering (SPS) method. A series of YbAl3 thermoelectric materials with nominal compositions YbAl3+ x ( x = 0-0.3, ? x = 0.1) have been prepared using the method. We have explored the effects of the excessive Al on phase compositions, microstructure and transport properties. The quenched samples are composed of YbAl3, YbAl2, Yb, and Al. All the annealed samples are composed of main phase YbAl3 and a trace of Al; some annealed samples with x = 0 and x = 0.1 still contain a trace of YbAl2. The SPSed samples with x ? 0.1 are composed of single-phase YbAl3, though a trace of YbAl2 still occured in the SPSed sample with x = 0. The electrical conductivity, Seebeck coefficient, power factor, thermal conductivity and ZT values are first increased with increasing x in the range of 0-0.2 and then decreased when x > 0.2. These thermoelectric properties evolutions originate from the change of densities and chemical composition induced by the excessive Al. The highest ZT value reaches 0.28 at 300 K for the SPSed sample with x = 0.2.

  13. High-efficiency wavelength and polarization selective grating-waveguide structures for Yb:YAG thin-disk lasers

    NASA Astrophysics Data System (ADS)

    Rumpel, Martin; Abdou Ahmed, Marwan; Voss, Andreas; Graf, Thomas

    2012-06-01

    We report on Grating Waveguide Structures (GWS) with a high diffraction efficiency used in Littrow configuration to select (and tune) the wavelength of an Yb:YAG thin-disk laser. The structures are composed of a multilayer HR coating, on which an additional low index layer (SiO2) and high index layer (Ta2O5) was deposited. A binary grating with a period of 580 nm is etched on top of the structure with a groove depth of 87 nm for GWS 1 and 72 nm for GWS 2. The simulation results show that the diffraction efficiency in the -1st order can reach a value of 99.99% for TE polarization, whereas it is only about 20% for TM polarization at 1030 nm. The grating was fabricated by standard interference lithography followed by a dry etching process to the desired groove depth. The spectroscopic measurement exhibited a diffraction efficiency of 99.6% for GWS 1 at 1030 nm and 99.7% for GWS 2 at 1048 nm. The devices were placed as end-mirror into the resonator of a Yb:YAG thin-disk laser. An output power of up to 110 W could be obtained from the laser in fundamental-mode operation (M2 ~ 1.2) with GWS 1, corresponding to an optical efficiency of ?oo = 36.2%. In multi-mode operation (M2 ~ 6) a power of 325 W with ?oo = 53.2% could be extracted. The spectral bandwidth of the emitted beam was measured using an Optical Spectrum Analyzer (OSA) to be less than 20 pm in fundamental-mode. We also showed a continuous wavelength tuning range of 46 nm for GWS 1 and of 38 nm for GWS 2. With a commercially available Stokes polarimeter the degree of linear polarization (DOLP) was measured to be higher than 98.6% over the whole power and wavelength tuning range.

  14. Ultrasensitive polarized up-conversion of Tm(3+)-Yb3+ doped ?-NaYF4 single nanorod.

    PubMed

    Zhou, Jiajia; Chen, Gengxu; Wu, E; Bi, Gang; Wu, Botao; Teng, Yu; Zhou, Shifeng; Qiu, Jianrong

    2013-05-01

    Up-conversion luminescence in rare earth ions (REs) doped nanoparticles has attracted considerable research attention for the promising applications in solid-state lasers, three-dimensional displays, solar cells, biological imaging, and so forth. However, there have been no reports on REs doped nanoparticles to investigate their polarized energy transfer up-conversion, especially for single particle. Herein, the polarized energy transfer up-conversion from REs doped fluoride nanorods is demonstrated in a single particle spectroscopy mode for the first time. Unique luminescent phenomena, for example, sharp energy level split and singlet-to-triplet transitions at room temperature, multiple discrete luminescence intensity periodic variation with polarization direction, are observed upon excitation with 980 nm linearly polarized laser. Furthermore, nanorods with the controllable aspect ratio and symmetry are fabricated for analysis of the mechanism of polarization anisotropy. The comparative experiments suggest that intraions transition properties and crystal local symmetry dominate the polarization anisotropy, which is also confirmed by density functional theory calculations. Taking advantage of the REs based up-conversion, potential application in polarized microscopic multi-information transportation is suggested for the polarization anisotropy from REs doped fluoride single nanorod or nanorod array. PMID:23611309

  15. Interactions of CT DNA with hexagonal NaYF4 co-doped with Yb(3+)/Tm(3+) upconversion particles.

    PubMed

    Yuan, Xiuxue; Gu, Wenchao; Xiao, Mengsi; Xie, Wenli; Wei, Shaohua; Zhou, Lin; Zhou, Jiahong; Shen, Jian

    2015-02-25

    The interaction of UCPs with CT DNA are studied in detail by zeta potential, Energy dispersive spectrometer (EDS) spectroscopy, Thermogravimetric (TGA) analysis, DNA melting determination and various spectroscopic techniques including Ultraviolet-Visible (UV-Vis) absorption, fluorescence, circular dichroism (CD), Fourier transform infrared (FTIR) and Raman spectroscopy. The results indicate that CT DNA can assemble on the surface of UCPs mainly by relative stronger hydrophobic force and electrostatic binding, and the predominant interaction site is the deoxyribosyl phosphate backbone of CT DNA. Moreover, after interacting with UCPs, the double helix structure of DNA is undamaged. PMID:25305602

  16. Electronic structure and f-orbital occupancy in Yb-substituted CeCoIn5

    SciTech Connect

    Booth, C. H.; Durakiewicz, T.; Capan, C.; Hurt, D.; Bianchi, A. D.; Joyce, J.J.; Fisk, Z.

    2011-05-03

    The local structure and 4f orbital occupancy have been investigated in Ce{sub 1?x}Yb{sub x}CoIn{sub 5} via Yb L{sub III}-edge extended x-ray absorption fine structure (EXAFS), Ce and Yb L{sub III}-edge x-ray absorption near-edge structure (XANES), and angle-resolved photoemission spectroscopy (ARPES) measurements. Yb(III) (4f{sup 13}) is the hole analog of Ce(III) (4f{sup 1}). Yb is found to be strongly intermediate-valent in Ce{sub 1?x}Yb{sub x}CoIn{sub 5} throughout the entire doping range, including pure YbCoIn{sub 5}, with an f-hole occupancy for Yb of n{sub f} ? 0.3 (i.e. Yb{sup 2.3+}), independent of Yb concentration and independent of temperature down to T = 20 K. In contrast, the f-electron orbital occupancy for Ce remains close to 1 for all Yb concentrations, suggesting that there is no mutual influence on n{sub f} between neighboring Ce and Yb sites. Likewise, ARPES measurements at 12 K have found that the electronic structure along {Gamma} ? X is not sensitive to the Yb substitution, suggesting that the Kondo hybridization of Ce f electrons with the conduction band is not affected by the presence of Yb impurities in the lattice. The emerging picture is that in Ce{sub 1?x}Yb{sub x}CoIn{sub 5} there are two networks, interlaced but independent, that couple to the conduction band: one network of Ce ions in the heavy-fermion limit, one network of Yb ions in the strongly intermediate-valent limit. The robustness of the local and electronic structure to doping suggests the absence of charge transfer between the Ce and Yb ions, and may explain the relative robustness of superconductivity for this Ce-site substitution as compared to the In-site substitution.

  17. Growth, structure, and spectroscopic properties of 5 at.% Yb:GdNbO4 laser crystal

    NASA Astrophysics Data System (ADS)

    Dou, Renqin; Zhang, Qingli; Luo, Jianqiao; Chen, Jiakang; Yang, Huajun; Liu, Wenpeng; Sun, Guihua; Sun, Dunlu

    2015-04-01

    A new crystal of Yb-doped gadolinium niobate, 5 at.% Yb:GdNbO4, is grown by Czochralski method for the first time. The structure of Yb:GdNbO4 is determined by Rietveld refinement to the X-ray powder diffraction data and it belongs to the monoclinic space group of I2/a. With the center of 955 nm, the FWHM of absorption spectra is 57 nm and the absorption cross section is calculated to be 0.97 × 10-20 cm2. Spectral parameters are calculated with absorption spectrum. In emission spectra, the strongest peak is at 1001 nm and the FWHM is 49 nm. In comparison with corresponding emission cross section of Yb:YSO and Yb:GSO, Yb:GdNbO4 exhibits a relatively larger emission cross section. In addition, a maximal output power of 270 mW is obtained and the slope efficiency is 7.5%.

  18. Diode pumped highly efficient Yb:Lu3Al5O12 ceramic laser

    NASA Astrophysics Data System (ADS)

    Xu, C. W.; Luo, D. W.; Zhang, J.; Yang, H.; Qin, X. P.; Tan, W. D.; Tang, D. Y.

    2012-01-01

    A diode pumped ytterbium-doped lutetium aluminum garnet (Yb:LuAG) ceramic laser is reported for the first time to our knowledge. Using the solid state reactive vacuum sintering technique we have successfully fabricated high optical quality Yb:LuAG ceramics. We show that even with an uncoated Yb:LuAG ceramic sample a maximum output power of 7 W could be achieved under 13 W absorbed pump power, and the laser has a slope efficiency as high as 63%. Considering that Yb:LuAG has higher thermal conductivity than Yb:YAG under heavy doping situation, Yb:LuAG ceramic could be an attractive laser gain medium for the high power solid state lasers applications.

  19. Synthesis and characterization of Er:Yb3Al5O12 nanopowder

    NASA Astrophysics Data System (ADS)

    Li, Chun; Xu, Jialin; Liu, Wang; Lin, Hai; Liu, Yu; Wang, Dan; Zhai, Jian; Fu, Tiehan; Zhou, Hu; Li, Yusheng; Liu, Jinghe; Zeng, Fanming

    2015-12-01

    Er:Yb1Al5O12 (Er:YbAG) nanopowder was prepared by carbonate coprecipitation method. Highpurity Er:YbAG powder was obtained after calcination at as low as 1000°C with an average particle size of 70 nm. The Al-O-Yb phonon vibrations were investigated and the absorption band arisen from interaction between lattice vibration and photon in YbAG is located around 610 cm-1. A strong emission peak of powder was observed at 1.53 µm with 980 nm laser excitation. An energy transfer mechanism between Yb3+ and Er3+ states responsible for the peak emission was proposed. An optimum Er3+ dopant concentration was determined.

  20. Optical spectroscopy of Yb(3)Al(5)O(12) single crystal.

    PubMed

    Xu, Xiaodong; Zhao, Zhiwei; Song, Pingxin; Jiang, Benxue; Zhou, Guoqing; Xu, Jun; Deng, Peizhen

    2005-11-01

    Yb(3)Al(5)O(12) single crystal has been grown by Czochralski (CZ) method. The absorption spectrum was investigated at low temperature and the electronic energy levels for (2)F(5/2) multiplet of Yb(3+) in YbAG was proposed. The up-conversion emission of the crystal under 940 nm diode pumping and the X-ray excited luminescence (XEL) features of the crystal were also studied. PMID:16257771

  1. Physica B 378380 (2006) 752753 Anisotropic intermediate valence in Yb2Rh3Ga9

    E-print Network

    Lawrence, Jon

    2006-01-01

    Physica B 378­380 (2006) 752­753 Anisotropic intermediate valence in Yb2Rh3Ga9 A.D. Christiansona for the anisotropic intermediate valence system Yb2Rh3Ga9. Calculations for the Anderson impurity model with crystal are important to the physics of Yb2Rh3Ga9. r 2006 Elsevier B.V. All rights reserved. Keywords: Intermediate

  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. Optical amplification in Er/Yb silicate slot waveguide.

    PubMed

    Guo, Ruimin; Wang, Bing; Wang, Xingjun; Wang, Lei; Jiang, Lingjun; Zhou, Zhiping

    2012-05-01

    Active slot waveguides were fabricated by embedding low-index Er/Yb silicate material in high-index silicon. A 1.7 dB signal enhancement at 1.53 µm in a 6 mm-long slot waveguide was observed through 1476 nm pumping. The peak Er emission cross-section is determined as 7.53×10(-21)??cm2 and the excited Er ion fraction is 0.17. Our experiment shows that the defects in upper c-Si of Si-on-insulator (SOI) and deposited ?-Si distorts photoluminescence spectrum and prevents further optical amplification. This negative effect can be partly corrected through annealing treatment, which allows better propagation of the pump light, therefore, stronger excitation in the sandwiched Er/Yb silicate. The defects also affect the 1.53 µm decay curve and are the dominant lifetime reduction mechanism in the active slot waveguide. PMID:22555693

  4. CCRS proposal for evaluating LANDSAT-4 MSS and TM data

    NASA Technical Reports Server (NTRS)

    Strome, W. M.; Cihlar, J.; Goodenough, D. G.; Guertin, F. E. (principal investigators); Guindon, B.; Murphy, J.; Butlin, J. M.; Duff, P.; Fitzgerald, A.; Grieve, G.

    1984-01-01

    The measurement of registration errors in LANDSAT MSS data is discussed as well as the development of a revised algorithm for the radiometric calibration of TM data and the production of a geocoded TM image.

  5. ORNL/TM-2008/048 Uranyl Nitrate Flow Loop

    E-print Network

    Pennycook, Steve

    ORNL/TM-2008/048 Uranyl Nitrate Flow Loop October 2008 Jennifer L. Ladd-Lively #12;DOCUMENT Government or any agency thereof. #12;ORNL/TM-2008/048 Nuclear Science and Technology Division URANYL NITRATE

  6. X-RAY ABSORPTION SPECTROSCOPY OF YB3+-DOPED OPTICAL FIBERS

    SciTech Connect

    Citron, Robert; Kropf, A.J.

    2008-01-01

    Optical fibers doped with Ytterbium-3+ have become increasingly common in fiber lasers and amplifiers. Yb-doped fibers provide the capability to produce high power and short pulses at specific wavelengths, resulting in highly effective gain media. However, little is known about the local structure, distribution, and chemical coordination of Yb3+ in the fibers. This information is necessary to improve the manufacturing process and optical qualities of the fibers. Five fibers doped with Yb3+ were studied using Extended X-ray Absorption Fine Structure (EXAFS) spectroscopy and X-ray Absorption Near Edge Spectroscopy (XANES), in addition to Yb3+ mapping. The Yb3+ distribution in each fiber core was mapped with 2D and 1D intensity scans, which measured X-ray fluorescence over the scan areas. Two of the five fibers examined showed highly irregular Yb3+ distributions in the core center. In four of the five fibers Yb3+ was detected outside of the given fiber core dimensions, suggesting possible Yb3+ diffusion from the core, manufacturing error, or both. X-ray absorption spectroscopy (XAS) analysis has so far proven inconclusive, but did show that the fibers had differing EXAFS spectra. The Yb3+ distribution mapping proved highly useful, but additional modeling and examination of fiber preforms must be conducted to improve XAS analysis, which has been shown to have great potential for the study of similar optical fi bers.

  7. The Cold Shock Domain of YB-1 Segregates RNA from DNA by Non-Bonded Interactions

    PubMed Central

    Kljashtorny, Vladislav; Nikonov, Stanislav; Ovchinnikov, Lev; Lyabin, Dmitry; Vodovar, Nicolas; Curmi, Patrick; Manivet, Philippe

    2015-01-01

    The human YB-1 protein plays multiple cellular roles, of which many are dictated by its binding to RNA and DNA through its Cold Shock Domain (CSD). Using molecular dynamics simulation approaches validated by experimental assays, the YB1 CSD was found to interact with nucleic acids in a sequence-dependent manner and with a higher affinity for RNA than DNA. The binding properties of the YB1 CSD were close to those observed for the related bacterial Cold Shock Proteins (CSP), albeit some differences in sequence specificity. The results provide insights in the molecular mechanisms whereby YB-1 interacts with nucleic acids. PMID:26147853

  8. Thermoelectric and Transport Properties of Yb z Fe4- x Ni x Sb12 Skutterudites

    NASA Astrophysics Data System (ADS)

    Lee, Woo-Man; Shin, Dong-Kil; Kim, Il-Ho

    2015-06-01

    p-Type Yb z Fe4- x Ni x Sb12 (0.8 ? z ?1.0, and 0.25 ? x ?0.5) skutterudites were prepared, and the effects of Yb filling and Ni substitution on the thermoelectric properties were examined. X-ray diffraction patterns revealed that Yb z Fe4- x Ni x Sb12 skutterudites were synthesized, but small amounts of secondary phases (FeSb2 and Sb) were produced, except for the YbFe3.5Ni0.5Sb12 specimen. This meant that the charge compensation with Ni and the amount of Yb filling should be sufficient to stabilize the skutterudite structure. All specimens had positive Hall coefficients and Seebeck coefficients, and the carrier concentration ranged from 9.80 × 1020 cm-3 to 3.37 × 1021 cm-3. The electrical conductivity decreased and the Seebeck coefficient increased with increasing Yb and Ni contents due to the decreased carrier concentration. The thermal conductivity decreased with increasing Yb and Ni contents, and YbFe3.5Ni0.5Sb12 showed the lowest thermal conductivity. The maximum dimensionless figure of merit achieved was of 0.62 at 723 K for YbFe3.5Ni0.5Sb12, based on the high power factor (2.6 mWm-1 K-2) and the low thermal conductivity (2.9 Wm-1 K-1).

  9. Thermoelectric and Transport Properties of Yb z Fe4-x Ni x Sb12 Skutterudites

    NASA Astrophysics Data System (ADS)

    Lee, Woo-Man; Shin, Dong-Kil; Kim, Il-Ho

    2014-09-01

    p-Type Yb z Fe4-x Ni x Sb12 (0.8 ? z ?1.0, and 0.25 ? x ?0.5) skutterudites were prepared, and the effects of Yb filling and Ni substitution on the thermoelectric properties were examined. X-ray diffraction patterns revealed that Yb z Fe4-x Ni x Sb12 skutterudites were synthesized, but small amounts of secondary phases (FeSb2 and Sb) were produced, except for the YbFe3.5Ni0.5Sb12 specimen. This meant that the charge compensation with Ni and the amount of Yb filling should be sufficient to stabilize the skutterudite structure. All specimens had positive Hall coefficients and Seebeck coefficients, and the carrier concentration ranged from 9.80 × 1020 cm-3 to 3.37 × 1021 cm-3. The electrical conductivity decreased and the Seebeck coefficient increased with increasing Yb and Ni contents due to the decreased carrier concentration. The thermal conductivity decreased with increasing Yb and Ni contents, and YbFe3.5Ni0.5Sb12 showed the lowest thermal conductivity. The maximum dimensionless figure of merit achieved was of 0.62 at 723 K for YbFe3.5Ni0.5Sb12, based on the high power factor (2.6 mWm-1 K-2) and the low thermal conductivity (2.9 Wm-1 K-1).

  10. Energy transfer mechanisms in Yb3+ doped YVO4 near-infrared downconversion phosphor

    NASA Astrophysics Data System (ADS)

    Wei, XianTao; Huang, Shan; Chen, YongHu; Guo, ChangXin; Yin, Min; Xu, Wu

    2010-05-01

    Upon ultraviolet (UV) light excitation, an intense near-infrared (NIR) emission of Yb3+ (F25/2?F27/2) around 980 nm is observed in YVO4:Yb3+ phosphors. Owing to host absorption of YVO4, a broad excitation band ranging from 250 to 350 nm is recorded when the Yb3+ emission was monitored, which suggests an efficient energy transfer from host to Yb3+ ions. The Yb3+ concentration dependence of the visible vanadate emission as well as the Yb3+ emission is investigated. The decay curve of vanadate emission is measured under the excitation of a 266 nm pulsed laser. The decay time of the vanadate emission at 500 nm is remarkably reduced by introducing Yb3+ ions, further verifying that the energy transfer from the vanadate host to the Yb3+ ions is very efficient. Cooperative energy transfer (CET) is discussed as a possible mechanism for the NIR emission. The YVO4:Yb3+ phosphor can convert each UV photon into two NIR photons via CET, which has potential application in the high efficiency silicon-based solar cells.

  11. Improvement of Yb 3+ doped optical fiber preforms by using MCVD method

    NASA Astrophysics Data System (ADS)

    Petit, V.; Sekiya, E. H.; Okazaki, T.; Bacus, R.; Barua, P.; Yao, B.; Ohsono, K.; Saito, K.

    2008-04-01

    This communication describes the fabrication of Yb doped silica preforms by modified chemical vapor deposition (MCVD) method using Yb(C 11H 19O II) 3 and AlCl 3 in vapor phase. In order to investigate the optical quality of the preforms a systematic spectroscopic study was carefully carried out on various samples with different Yb and Al doping levels. In this way, the influence of the preforms composition on the Yb spectroscopic properties was studied in details, allowing the prediction of the composition favoring the laser emission with the highest efficiency. The predictions have then been validated after pulling the preforms in large mode area fibers (LMA).

  12. Yb-based heavy fermion compounds and field tuned quantum chemistry

    SciTech Connect

    Mun, Eundeok

    2010-07-23

    The motivation of this dissertation was to advance the study of Yb-based heavy fermion (HF) compounds especially ones related to quantum phase transitions. One of the topics of this work was the investigation of the interaction between the Kondo and crystalline electric field (CEF) energy scales in Yb-based HF systems by means of thermoelectric power (TEP) measurements. In these systems, the Kondo interaction and CEF excitations generally give rise to large anomalies such as maxima in {rho}(T) and as minima in S(T). The TEP data were use to determine the evolution of Kondo and CEF energy scales upon varying transition metals for YbT{sub 2}Zn{sub 20} (T = Fe, Ru, Os, Ir, Rh, and Co) compounds and applying magnetic fields for YbAgGe and YbPtBi. For YbT{sub 2}Zn{sub 20} and YbPtBi, the Kondo and CEF energy scales could not be well separated in S(T), presumably because of small CEF level splittings. A similar effect was observed for the magnetic contribution to the resistivity. For YbAgGe, S(T) has been successfully applied to determine the Kondo and CEF energy scales due to the clear separation between the ground state and thermally excited CEF states. The Kondo temperature, T{sub K}, inferred from the local maximum in S(T), remains finite as magnetic field increases up to 140 kOe. In this dissertation we have examined the heavy quasi-particle behavior, found near the field tuned AFM quantum critical point (QCP), with YbAgGe and YbPtBi. Although the observed nFL behaviors in the vicinity of the QCP are different between YbAgGe and YbPtBi, the constructed H-T phase diagram including the two crossovers are similar. For both YbAgGe and YbPtBi, the details of the quantum criticality turn out to be complicated. We expect that YbPtBi will provide an additional example of field tuned quantum criticality, but clearly there are further experimental investigations left and more ideas needed to understand the basic physics of field-induced quantum criticality in Yb-based systems.

  13. Thermoluminescence properties of ZnO and ZnO:Yb nanophosphors

    SciTech Connect

    Pal, U.; Melendrez, R.; Chernov, V.; Barboza-Flores, M.

    2006-10-30

    ZnO and ZnO:Yb thermoluminescence nanophosphors have been developed and tested under beta radiation. Spherical nanoparticles of sizes ranging from 130 to 1200 nm were prepared through a glycol mediated chemical synthesis. The Yb doping had a thermoluminescence quenching effect compared to undoped ZnO. The 5% Yb concentration produced a low fading, a single thermoluminescence glow peak structure, and a dose linearity behavior adequate for thermoluminescence dosimetry applications. The ZnO:Yb nanophosphor has a great potential as a dosimeter for monitoring in ionizing radiation fields.

  14. Valence state change and defect centers induced by infrared femtosecond laser in Yb:YAG crystals

    SciTech Connect

    Wang, Xinshun Liu, Yang; Zhao, Panjuan; Guo, Zhongyi; Li, Yan; Qu, Shiliang

    2015-04-21

    The broad band upconversion luminescence in Yb{sup 3+}:YAG crystal has been observed in experiments under the irradiation of focused infrared femtosecond laser. The dependence of the fluorescence intensity on the pump power shows that the upconversion luminescence is due to simultaneous two-photon absorption process, which indicates that the broad emission bands at 365 and 463?nm could be assigned to the 5d ? 4f transitions of Yb{sup 2+} ions and the one at 692?nm could be attributed to the electron-hole recombination process on (Yb{sup 2+}-F{sup +}) centers. The absorption spectra of the Yb:YAG crystal samples before and after femtosecond laser irradiation, and after further annealing reveal that permanent valence state change of Yb ions from Yb{sup 3+} to Yb{sup 2+} and (Yb{sup 2+}-F{sup +}) centers have been induced by infrared femtosecond laser irradiation in Yb{sup 3+}:YAG crystal.

  15. Efficient lasing in Yb:(YLa)2O3 ceramics

    NASA Astrophysics Data System (ADS)

    Snetkov, I. L.; Mukhin, I. B.; Balabanov, S. S.; Permin, D. A.; Palashov, O. V.

    2015-02-01

    A high-optical-quality sample of Yb0.1Y1.7La0.2O3 ceramics is prepared using a recently developed technique of selfpropagating high-temperature synthesis of rare-earth-doped yttrium oxide nanopowder from acetate - nitrates of metals. Its optical and spectral characteristics are studied, and quasi-cw lasing at a wavelength of 1033 nm is achieved with a power of 7 W and a slope efficiency of 25%.

  16. Pioneers--The "Engineering byDesign[TM]" Network

    ERIC Educational Resources Information Center

    Burke, Barry N.

    2006-01-01

    This article discusses the standards-based instruction model, Engineering byDesign[TM] (EbD), and a network of teachers called the Engineering byDesign[TM] Network. Engineering byDesign[TM] is the only standards-based national model for Grades K-12 that delivers technological literacy which was developed by the International Technology Education…

  17. 2014 Invent Now, Inc. KartWheelTM

    E-print Network

    Missouri-Rolla, University of

    © 2014 Invent Now, Inc. KartWheelTM Ladies and gentlemen--start your inventions! Design a freestyle KartWheelTM racer. I Can Invent: Next Level GamersTM Take apart machines and use their high-tech guts and possibility. Design prototypes from scratch or gather invention inspiration by spinning the Design Challenge

  18. Effects of trisodium citrate on morphology of ?-NaGd1- x Yb x F4:Er3+ nanocrystals: role of Yb3+ concentration

    NASA Astrophysics Data System (ADS)

    Lü, Mengyun; Guan, Tengpeng; Li, Ai-Hua; Sun, Zhijun

    2015-10-01

    In solvothermal synthesis of Er3+-doped NaGd1- x Yb x F4 nanocrystals, morphology of the nanoparticles is dependent on the molar ratio of the chelating agent (e.g., trisodium citrate) to the lanthanide ions. Usually, addition of chelating agent is reported to be effective only when the molar ratio is below a critical value usually around 1 for the preparation of Er3+- and Yb3+-doped NaYF4 nanocrystals. In this work, we found that, by increasing the Yb3+ concentration, the critical molar ratio can be up to more than 4 in the preparation of Er3+-doped NaGd1- x Yb x F4 nanocrystals, which provides a new route to control the nanoparticles' size. The result is particularly useful for the synthesis of small Er3+-doped NaGd1- x Yb x F4 nanocrystals with high concentration of the Yb3+ dopant. We also investigated mechanisms on the formation of such particles ( ?-NaGd0.3Yb0.7F4:Er3+) with large size in a sub-micrometer scale, i.e., the aggregation-induced crystal growth. In addition, upconversion luminescence properties of the powdery samples were studied, which is shown to be dependent both on size of the nanoparticles and on dosage of the trisodium citrate.

  19. NASA/TM2013218033 Rewriting Modulo SMT

    E-print Network

    Muñoz, César A.

    NASA/TM­2013­218033 Rewriting Modulo SMT Camilo Rocha Escuela Colombiana de Ingenier´ia, Bogot´a, Colombia Jos´e Meseguer University of Illinois at Urbana-Champaign, Urbana, IL, USA C´esar A. Mu~noz NASA Langley Research Center, Hampton, VA, USA August 2013 #12;NASA STI Program . . . in Profile Since its

  20. NASA/TM2009215726 Formally Verified Practical

    E-print Network

    Muñoz, César A.

    NASA/TM­2009­215726 Formally Verified Practical Algorithms For Recovery From Loss of Separation of Aerospace, Hampton, Virginia June 2009 #12;The NASA STI Program Office . . . in Profile Since its founding, NASA has been dedicated to the advancement of aeronautics and space science. The NASA Scientific

  1. August 2002 NASA/TM--2002211612

    E-print Network

    Richardson, John

    August 2002 NASA/TM--2002­211612 Pickup Ions at Dione and Enceladus E. Sittler, R.E. Johnson, S. Jurac, J. Richardson, M. McGrath, F. Crary, D. Young, and J.E. Nordholt #12;The NASA STI Program Office ... in Profile Since its founding, NASA has been dedicated to the advancement of aeronautics and space science

  2. :>':. '*>3 1 /? ORNL/TM-8022

    E-print Network

    Oak Ridge National Laboratory

    Division THE STIRLING ENGINE WITH ONE ADIABATIC CYLINDER C. D. West Date Published: March 1982 DISCLAIMER #12;#12;THE STIRLING ENGINE WITH ONE ADIABATIC CYLINDER C. D. West This report shows that integration:>':. '*>3 1 /? ORNL/TM-8022 ^S] ~/ 3)/:: 60g7b6( Contract No. W-7405-eng-26 Engineering Technology

  3. E. coli PulserTM Transformation

    E-print Network

    Lai, Zhi-Chun

    E. coli PulserTM Transformation Apparatus Operating Instructions and Applications Guide Catalog or in the U.S. Call 1-800-4BIORAD (1-800-424-6723) #12;Warranty Bio-Rad Laboratories warrants the E. coli ....................................................................................2 Section 2 E. coli Pulser Apparatus Operating Instructions..............................2 Section 3

  4. Doors to Discovery [TM]. WWC Intervention Report

    ERIC Educational Resources Information Center

    What Works Clearinghouse, 2009

    2009-01-01

    Doors to Discovery[TM], an early childhood curriculum, focuses on the development of children's vocabulary and expressive and receptive language through a learning process called "shared literacy," where adults and children work together to develop literacy-related skills. Literacy activities, organized into thematic units, encourage children's…

  5. Instant-InTM Proctor Student Documentation

    E-print Network

    -InTM Proctor: · Biometric authentication of the test/exam taker. · Continuous streaming screen capture of all of the test/exam taker. · Random biometric authentication of the test/exam taker and logging of any anomalies: · Dashboard presentation of all student information including student name, photo ID snapshot, biometric

  6. Sun StorageTekTM Security Policy

    E-print Network

    Sun StorageTekTM T10000A Tape Drive Security Policy Part Number 316055001 Revision: AB Sun Microsystems, Inc. September 1, 2009 Copyright Sun Microsystems 2009. May be reproduced only in its original entirety [without revision]. #12;Sun Microsystems Sun StorageTek T10000A Tape Drive Security Policy

  7. Sun StorageTekTM Security Policy

    E-print Network

    Sun StorageTekTM T10000B Tape Drive Security Policy Part Number 316055101 Revision: AB Sun Microsystems, Inc. September 1, 2009 Copyright Sun Microsystems 2009. May be reproduced only in its original entirety [without revision]. #12;Sun Microsystems Sun StorageTek T10000B Tape Drive Security Policy

  8. Defying Gravity Using Jenga[TM] Blocks

    ERIC Educational Resources Information Center

    Tan, Yin-Soo; Yap, Kueh-Chin

    2007-01-01

    This paper describes how Jenga[TM] blocks can be used to demonstrate the physics of an overhanging tower that appears to defy gravity. We also propose ideas for how this demonstration can be adapted for the A-level physics curriculum. (Contains 8 figures and 1 table.)

  9. Home/EU Overseas Home/EU Overseas 13,400 6,700

    E-print Network

    Chittka, Lars

    Home/EU Overseas Home/EU Overseas £13,400 £6,700 £15,450 £7,725 £16,950 £8,475 £14,500 £7,250 S,250 £43,500 £21,750 Home/EU Overseas Home/EU Overseas £13,200 £6,600 £15,250 £7,625 £16,700 £8,350 £16/EU Overseas Home/EU Overseas £13,000 £6,500 £15,000 £7,500 £16,450 £8,225 £16,450 £8,225 £13,000 £6,500 £17

  10. including PhD and MD(Res) Home/EU Overseas Home/EU Overseas

    E-print Network

    Chittka, Lars

    including PhD and MD(Res) Home/EU Overseas Home/EU Overseas £13,000 £6,500 £15,000 £7,500 £16,250 £37,500 £18,750 £42,500 £21,250 Home/EU Overseas Home/EU Overseas £12,800 £6,400 £14,750 £7,375 £16,125 £37,250 £18,625 £42,250 £21,125 Home/EU Overseas Home/EU Overseas £12,750 £6,375 £14,550 £7,275 £15

  11. Visible to infrared energy conversion in Pr3+-Yb3+ co-doped fluoroindate glasses

    NASA Astrophysics Data System (ADS)

    Borrero-González, L. J.; Galleani, G.; Manzani, D.; Nunes, L. A. O.; Ribeiro, S. J. L.

    2013-10-01

    Processes involving visible to infrared energy conversion are presented for Pr3+-Yb3+ co-doped fluoroindate glasses. The emission in the visible and infrared regions, the luminescence decay time of the Pr3+:3P0 ? 3H4 (482 nm), Pr3+:1D2 ? 3H6 (800 nm), Yb3+:2F5/2 ? 2F7/2 (1044 nm) transitions and the photoluminescence excitation spectra were measured in Pr3+ samples and in Pr3+-Yb3+ samples as a function of the Yb3+ concentration. In addition, energy transfer efficiencies were estimated from Pr3+:3P0 and Pr3+:1D2 levels to Yb3+:2F7/2 level. Down-Conversion (DC) emission is observed due to a combination of two different processes: 1-a one-step cross relaxation (Pr3+:3P0 ? 1G4; Yb3+:2F7/2 ? 2F5/2) resulting in one photon emitted by Pr3+ (1G4 ? 3H5) and one photon emitted by Yb3+ (2F7/2 ? 2F5/2); 2-a resonant two-step first order energy transfer, where the first part of energy is transferred to Yb3+ neighbor through cross relaxation (Pr3+:3P0 ? 1G4; Yb3+:2F7/2 ? 2F5/2) followed by a second energy transfer step (Pr3+:1G4 ? 3H4; Yb3+:2F7/2 ? 2F5/2). A third process leading to one IR photon emission to each visible photon absorbed involves cross relaxation energy transfer (Pr3+:1D2 ? 3F4; Yb3+:2F7/2 ? 2F5/2).

  12. Fabrication and photoluminescence properties of Cr:YAG and Yb,Cr:YAG transparent ceramic

    NASA Astrophysics Data System (ADS)

    Chen, Xingtao; Lu, Tiecheng; Wei, Nian; Lu, Zhongwen; Chen, Lijia; Zhang, Qinghua; Cheng, Gang; Qi, Jianqi

    2015-11-01

    Cr:YAG and Yb/Cr:YAG transparent ceramics containing Ca as charge counter element were fabricated by vacuum sintering technique using the co-precipitation synthesis of raw powders. Their spectral and luminescence properties as well as the influence of Cr3+ concentration on the optical properties of Yb,Cr:YAG ceramic were investigated. Results show the transmittance of 10 at.% Yb, 0.25 at.% Cr:YAG and 0.25 at.% Cr:YAG reaches 83% at 1200 nm and 81% at 1400 nm, respectively. And the Yb,Cr:YAG ceramics exhibit a pore free structure with an average grain size of about 5 ?m. After annealing, most of Cr3+ ions transform into Cr4+. In the case of excitation wavelength of 440 nm, a sharp emission peak of 694 nm appeared in the Yb,Cr:YAG ceramic before annealing and the band enhanced with the increase of the Cr3+ concentration, which is attributed to the 4T2g-4A2g fluorescence transition. The emission spectrums and fluorescence decays manifest that both the luminescent intensity and the lifetimes of Yb,Cr:YAG are lower than Yb:YAG ceramic and the lifetimes of Yb,Cr:YAG and Yb:YAG are 0.93 and 2.38 ms, respectively. This results demonstrate the existence of the ground state absorption of Cr4+ in the Yb,Cr:YAG ceramic. Experimental evidence proved that Yb,Cr:YAG transparent ceramics could be a potential material for passive self-Q-switched solid-state laser.

  13. Reliability and Validity of the Zephyr[TM] BioHarness[TM] to Measure Respiratory Responses to Exercise

    ERIC Educational Resources Information Center

    Hailstone, Jono; Kilding, Andrew E.

    2011-01-01

    The Zephyr[TM] BioHarness[TM] (Zephyr Technology, Auckland, New Zealand) is a wireless physiological monitoring system that has the ability to measure respiratory rate unobtrusively. However, the ability of the BioHarness[TM] to accurately and reproducibly determine respiratory rate across a range of intensities is currently unknown. The aim of…

  14. Power scaling of Tm:YAG slab ceramic laser

    NASA Astrophysics Data System (ADS)

    Zhang, Shuaiyi; Zhou, Yan; Gao, Peng; Wang, Xia; Kong, Weijin; Xu, Jianqiu; Pan, Yubai

    2015-05-01

    We describe the high power operation of transparent Tm:YAG ceramic lasers end-pumped by a 80?W laser-diode bar at 782?nm. The optimization of the Tm3+-ion doping concentration and the laser configuration for high power Tm:YAG ceramic lasers are investigated. We obtain the continuous wave (CW) output power of 24.6?W with the slope efficiency of 38.2% from a 6?at.% Tm:YAG ceramic slab laser. This is, to the best of our knowledge, the highest output average-power of diode-bar end-pumped Tm:YAG ceramic lasers ever reported.

  15. Tuning the Kondo effect in YbFe1-xCoxZn20

    NASA Astrophysics Data System (ADS)

    Kong, Tai; Taufour, Valentin; Bud'Ko, Sergey; Canfield, Paul

    2015-03-01

    YbCo2Zn20 is a heavy fermion compound with a Sommerfeld coefficient, ? value, of about 8000 mJ/mol-K2 with an estimated single ion Kondo temperature, TK, of about 1.5 K. One the other hand, YbFe2Zn20 is less heavy with ? ~ 500 mJ/mol-K2 and TK ~ 30 K. From a generalized Kadowaki-Woods picture, degeneracies that relate to their Kondo phenomena are large while different: 8 for YbFe2Zn20 and 4 for YbCo2Zn20. In order to understand the effects of Fe-Co substitution on the Kondo effect, a family of YbFe1-xCoxZn20 were studied. We performed zero-field resistivity and specific heat measurements on single crystals of YbFe1-xCoxZn20 that were synthesized using a high-temperature solution growth technique. The Kondo characteristic temperatures do not change monotonically in between pure YbFe2Zn20andYbCo2Zn20. Data and a summarize phase diagram of characteristic temperatures as a function of Co doping will be presented and discussed. This work is supported by the US DOE, Basic Energy Sciences under Contract No. DE-AC02-07CH11358.

  16. 20 W single-mode Yb3+ -doped phosphate fiber laser

    E-print Network

    Byer, Robert L.

    20 W single-mode Yb3+ -doped phosphate fiber laser Y. W. Lee, S. Sinha, M. J. F. Digonnet, and R. L the demonstration of the first, to our knowledge, cladding-pumped continuous-wave Yb3+ -doped phosphate-glass fiber laser. Phosphate hosts are of interest because they can be much more heavily doped than silica

  17. Monolithic Q-switched Cr,Yb:YAG laser Yi Zhoua,*, Quang Thaia

    E-print Network

    Monolithic Q-switched Cr,Yb:YAG laser Yi Zhoua,*, Quang Thaia , Y.C. Chena , Shouhuan Zhoub; accepted 27 February 2003 Abstract We report the operation of a diode-pumped monolithic self-Q-switched Cr-power monolithic Q-switched solid-state laser based on a new chromium and ytterbium co- doped YAG crystal. Yb

  18. Formation of Yb nBa 2 nCu 3 n+1 O x ( n=3, 4) by oxidation of Yb?Ba?Cu?Ag metallic precursors

    NASA Astrophysics Data System (ADS)

    Kogure, T.; Otto, A.; Vander Sande, J. B.

    1989-01-01

    New structural variations on the 1-2-3 type high- Tc superconducting phase have been identified in oxidized Yb?Ba?Cu?Ag metallic precursors in which Yb 2Ba 4Cu 7O x (2-4-7) and Ag are the dominant phases. These new structures are generated by the placement of the copper oxide double layer in every three unit cells of the 1-2-3 structure yielding the chemical composition Yb 3Ba 6Cu 10O x or in every four unit cells yielding Yb 4Ba 8Cu 13O x. These discoveries lead to the conclusion that a large family of superconductors exists whose generic formula is Re nBa 2 nCu 3 n+1 O x, where Re represents rare-earth elements and n is between 1 and ? ( n=? generates the 1-2-3 phase).

  19. Properties of Yb-doped scintillators: YAG, YAP, LuAG

    NASA Astrophysics Data System (ADS)

    Belogurov, S.; Bressi, G.; Carugno, G.; Grishkin, Yu.

    2004-01-01

    A big number of Yb:YAG samples is analyzed. Emission and transmittance spectra are measured. Light output and decay time vs. temperature are measured for charge transfer (CT) and IR scintillation. Light yield (LY) of the best laser crystals is by a factor 2.4 higher than the value measured for the samples of typical scintillator quality. A pulse shape dependence on e-beam energy density is observed for the IR scintillation. A new efficient Yb doped scintillator is found—Yb:YAP. CT scintillation in a high Z material Yb:LuAG is confirmed. A new scintillation material, potentially interesting for neutrino physics, is proposed: Yb doped garnet or perovskite containing indium in the host lattice. Some prospective research directions are indicated.

  20. Reflection symmetry instability at high spins in 162,164Yb

    E-print Network

    R. G. Nazmitdinov; J. Kvasil; A. Tsvetkov

    2007-11-15

    A shape evolution of 162,164Yb in yrast states is traced using the self-consistent Skyrme Hartree-Fock calculations. We found that nonaxial octupole deformations (in particular, Y_{31} term) become favorable at large rotational frequencies (> 0.4 MeV) in 162Yb, while in 164Yb a nonaxial quadrupole shape is dominant at fast rotation. The cranked Nilsson model and random phase approximation are used to understand the dynamics of octupole correlations in both nuclei. We demonstrate that the disappearance of one of the octupole vibrational modes in the rotating frame gives rise to the nonaxial octupole deformations in 162Yb, while the octupole modes are nonzero in 164Yb.

  1. Growth and spectral characterization of Yb 3+:LiLa(WO 4) 2 crystal

    NASA Astrophysics Data System (ADS)

    Huang, Xinyang; Lin, Zhoubin; Hu, Zushu; Zhang, Lizhen; Tsuboi, Taiju; Wang, Guofu

    2006-12-01

    The growth and spectroscopic properties of Yb 3+:LiLa(WO 4) 2 crystal were investigated. Yb 3+:LiLa(WO 4) 2 crystal with dimension ?22 × 18 mm 2 has been grown by the Czochralski method. Yb 3+:LiLa(WO 4) 2 crystal has a larger FWHM of 10 nm at 976 nm. The absorption and emission cross-sections of Yb 3+:LiLa(WO 4) 2 crystal are 2.46 × 10 -20 cm 2 at 976 nm and 0.39 × 10 -20 cm 2 at 1039 nm, respectively. The radiative lifetime and fluorescence lifetime of Yb 3+:LiLa(WO 4) 2 crystal are 0.365 ms and 1.07 ms, respectively.

  2. Fabrication and characterization of highly transparent Yb3+: Y2O3 ceramics

    NASA Astrophysics Data System (ADS)

    Ning, Kaijie; Wang, Jun; Luo, Dewei; Ma, Jie; Zhang, Jian; Dong, Zhi Li; Kong, Ling Bing; Tang, Ding Yuan

    2015-12-01

    Highly transparent Yb3+ doped Y2O3 (Yb3+: Y2O3) ceramics was fabricated by a solid-state reaction method using ZrO2 and La2O3 as additives. The morphology of the prepared powder was investigated and the phase of the sintered Yb3+: Y2O3 ceramics sample was identified. The microstructure, transmittance spectrum, Vickers hardness and fracture toughness for the as-sintered Yb3+: Y2O3 ceramics were measured. The average grain size was about 9.11 ?m and the transmittance at the wavelength of 2000 nm was about 82.0%, which was 99% of the theoretical value. ZrO2 and La2O3 were useful additives for highly transparent Yb3+: Y2O3 ceramics fabrication and mechanical properties improvement.

  3. Comparative study of optical and scintillation properties of Tm3+:YAG, and Tm3+:LuAG single crystals

    NASA Astrophysics Data System (ADS)

    Fujimoto, Yutaka; Sugiyama, Makoto; Yanagida, Takayuki; Wakahara, Shingo; Suzuki, Shotaro; Kurosawa, Shunsuke; Chani, Valery; Yoshikawa, Akira

    2013-09-01

    The optical and scintillation properties of Tm3+-doped yttrium aluminum garnet Y3Al5O12 (YAG) and Tm3+-doped lutetium aluminum garnet Lu3Al5O12 (LuAG) are compared. The Tm3+-doped single crystals were grown by the micro-pulling down (?-PD) technique. Both crystals demonstrated some emission peaks originated from 4f-4f forbidden transition of Tm3+ under 241Am alpha-ray excitation. The scintillation decay time of Tm3+-doped YAG was similar to that of LuAG. When irradiated by the gamma-rays from a 137Cs source, the relative scintillation light yields of Tm:YAG was 90% greater than that of Tm:LuAG.

  4. TE/TM decomposition of electromagnetic sources

    NASA Technical Reports Server (NTRS)

    Lindell, Ismo V.

    1988-01-01

    Three methods are given by which bounded EM sources can be decomposed into two parts radiating transverse electric (TE) and transverse magnetic (TM) fields with respect to a given constant direction in space. The theory applies source equivalence and nonradiating source concepts, which lead to decomposition methods based on a recursive formula or two differential equations for the determination of the TE and TM components of the original source. Decompositions for a dipole in terms of point, line, and plane sources are studied in detail. The planar decomposition is seen to match to an earlier result given by Clemmow (1963). As an application of the point decomposition method, it is demonstrated that the general exact image expression for the Sommerfeld half-space problem, previously derived through heuristic reasoning, can be more straightforwardly obtained through the present decomposition method.

  5. Genome-wide analysis of YB-1-RNA interactions reveals a novel role of YB-1 in miRNA processing in glioblastoma multiforme.

    PubMed

    Wu, Shuai-Lai; Fu, Xing; Huang, Jinyan; Jia, Ting-Ting; Zong, Feng-Yang; Mu, Shi-Rong; Zhu, Hong; Yan, Yong; Qiu, Shuwei; Wu, Qun; Yan, Wei; Peng, Ying; Chen, Juxiang; Hui, Jingyi

    2015-09-30

    Altered miRNA expression is believed to play a crucial role in a variety of human cancers; however, the mechanisms leading to the dysregulation of miRNA expression remain elusive. In this study, we report that the human Y box-binding protein (YB-1), a major mRNA packaging protein, is a novel modulator of miRNA processing in glioblastoma multiforme (GBM). Using individual nucleotide-resolution crosslinking immunoprecipitation coupled to deep sequencing (iCLIP-seq), we performed the first genome-wide analysis of the in vivo YB-1-RNA interactions and found that YB-1 preferentially recognizes a UYAUC consensus motif and binds to the majority of coding gene transcripts including pre-mRNAs and mature mRNAs. Remarkably, our data show that YB-1 also binds extensively to the terminal loop region of pri-/pre-miR-29b-2 and regulates the biogenesis of miR-29b-2 by blocking the recruitment of microprocessor and Dicer to its precursors. Furthermore, we show that down-regulation of miR-29b by YB-1, which is up-regulated in GBM, is important for cell proliferation. Together, our findings reveal a novel function of YB-1 in regulating non-coding RNA expression, which has important implications in tumorigenesis. PMID:26240386

  6. 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.

  7. In Situ Growth of a Yb2O3 Layer for Sublimation Suppression for Yb14MnSb11 Thermoelectric Material for Space Power Applications

    NASA Astrophysics Data System (ADS)

    Nesbitt, James A.; Opila, Elizabeth J.; Nathal, Michael V.

    2012-06-01

    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 (˜3 × 10-3 g/cm2 h) 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.

  8. Characterization of Yb:YAG ceramics as laser media

    NASA Astrophysics Data System (ADS)

    Alderighi, Daniele; Pirri, Angela; Toci, Guido; Vannini, Matteo; Esposito, Laura; Costa, Anna Luisa; Piancastelli, Andreana; Serantoni, Marina

    2010-12-01

    We report the preparation and characterization of 9.8 at.% Yb 3+ doped YAG polycrystalline ceramics for laser applications. Reactive sintering of commercial powders in a clean atmosphere and under high vacuum has been used to achieve the YAG phase. The selected experimental conditions for the powder treatment, shaping and sintering are described and their influence on the optical quality of the obtained samples has been discussed. Microstructural, optical and laser characterization of the ceramics have been performed. In particular the influence of the pre-sintering (calcination) and sintering cycles has been investigated by laser characterization allowing to find unexpected loss mechanisms that cannot be revealed by standard optical characterization.

  9. [Crystal growth and spectroscopy of Er/Yb:KGW crystal].

    PubMed

    Zhu, Zhao-jie; Tu, Chao-yang; Li, Jian-fu; Wu, Bai-chang; Huang, Yan

    2005-09-01

    The Er3 /Yb3+:KGW crystal with the dimensions of 30 mm x 25 mm x 15 mm was grown from K2W2O7 solvent by modified Czochralski method. The absorption spectrum was measured at room temperature and its absorption peaks were assigned. The emission spectrum was obtained under the excitation of 980 nm. There are two broad emission bands at 1024 and 1535 nm, whose FHWM are 60 and 36 nm respectively. It shows that this crystal is suitable for InGaAs LD pumping, and may be a promising laser crystal tunable at near 1 024 and 1 535 nm. PMID:16379283

  10. Evaluating LANDSAT-4 MSS and TM data

    NASA Technical Reports Server (NTRS)

    Strome, W. M.; Cihlar, J.; Goodenough, D. G.; Guertin, F. E. (principal investigator); Murphy, J. M.; Grieve, G.; Simard, R.; Horler, D.; Ahern, F. J.

    1984-01-01

    Interband line pixel misregistrations were determined for the four MSS bands of the Mistassini, Ontario scene and multitemporal registration of LANDSAT-4 products were tested for two different geocoded scenes. Line and pixel misregistrations are tabulated as determined by the manual ground control points and the digital band to band correlation techniques. A method was developed for determining the spectral information content of TM images for forestry applications.

  11. Absolute calibration accuracy of L4 TM and L5 TM sensor image pairs

    USGS Publications Warehouse

    Chander, G.; Micijevic, E.

    2006-01-01

    The Landsat suite of satellites has collected the longest continuous archive of multispectral data of any land-observing space program. From the Landsat program's inception in 1972 to the present, the Earth science user community has benefited from a historical record of remotely sensed data. However, little attention has been paid to ensuring that the data are calibrated and comparable from mission to mission, Launched in 1982 and 1984 respectively, the Landsat 4 (L4) and Landsat 5 (L5) Thematic Mappers (TM) are the backbone of an extensive archive of moderate resolution Earth imagery. To evaluate the "current" absolute accuracy of these two sensors, image pairs from the L5 TM and L4 TM sensors were compared. The approach involves comparing image statistics derived from large common areas observed eight days apart by the two sensors. The average percent differences in reflectance estimates obtained from the L4 TM agree with those from the L5 TM to within 15 percent. Additional work to characterize the absolute differences between the two sensors over the entire mission is in progress.

  12. {Y 3- x,Yb x}[Ga] 2(Ga) 3O 12 and {Lu 2Yb 1}[Al] 2(Al) 3O 12 single crystals for scintillator application grown by the modified micro-pulling-down method

    NASA Astrophysics Data System (ADS)

    Yoshikawa, Akira; Akagi, Tadahiro; Nikl, Martin; Solovieva, Natalia; Lebbou, Kheirreddine; Dujardin, Christophe; Pédrini, Christian; Fukuda, Tsuguo

    2002-06-01

    In order to investigate proper hosts for charge transitions (CT) of Yb 3+, the gallium garnet host (YGG) and aluminium garnet host (LuAG) were studied. Transparent and crack-free heavily Yb-doped YGG, i.e. {Y 3- x,Yb x}[Ga] 2(Ga) 3O 12, x=0.15, 0.5, 1.0 and heavily Yb-doped LuAG, i.e. {Lu 2Yb 1}[Al] 2(Al) 3O 12 single crystals were grown by the modified pulling-down method with <1 1 1> orientation. Emission, excitation spectra and decay kinetics were measured for these crystals. The CT of Yb 3+ in the YGG host were discussed compared with the Yb 3+ one in the LuAG host.

  13. Comparative study on optical properties of Yb3+ doped LiNbO3: MgO and LiNbO3:ZnO laser crystals

    NASA Astrophysics Data System (ADS)

    Ning, Kaijie; Li, Baizhong; Zhang, Qingli; Hang, Yin; Shi, Zhenhua

    2015-08-01

    Yb3+ doped LiNbO3:MgO (Mg, Yb:LN) and Yb3+ doped LiNbO3:ZnO (Zn, Yb:LN) laser crystals were grown from congruent melt by Czochralski (Cz) method and polarized under electric field. The absorption and emission spectra, and decay curves were measured and analyzed. Zn, Yb:LN crystal shows relatively larger cross sections both for absorption and emission spectra. The comparative study indicates that Zn, Yb:LN crystal would be one better crystal on potential laser performance than Mg, Yb:LN crystal.

  14. Luminescence studies on Dy3+ and Dy3+:Eu3+ co-doped boro-phosphate glasses for WLED applications

    NASA Astrophysics Data System (ADS)

    Vijayakumar, M.; Uma, V.; Arunkumar, S.; Marimuthu, K.

    2015-06-01

    Dy3+ and Dy3+:Eu3+ co-doped boro-phosphate glasses have been prepared and optically characterized using absorption, luminescence and decay measurements. The Nephelauxetic ratios (?), Bonding parameters (?) and Judd-Ofelt (JO) intensity parameters ?? (? = 2, 4 and 6) were calculated to study the nature of the environment around the RE3+ ions in the prepared glasses. The yellow to blue (Y/B) intensity ratio and the chromaticity color coordinates were calculated from the luminescence measurements. The lifetimes of the 4F9/2 excited level were measured using decay curves and is found to decrease in the Dy3+:Eu3+ co-doped glass due to the occurrence of resonant energy transfer between Dy3+-Eu3+ ions and the non-exponential decay rates have been fitted with Inokuti-Hirayama (IH) model. The decay curves are well fitted for S= 6 suggesting that the interaction between active ions for the energy transfer is of dipole-dipole nature.

  15. Long-Range Magnetic Ordering in Pyrochlore Iridate Eu2Ir2O7

    NASA Astrophysics Data System (ADS)

    Zhao, S.; Mackie, J. M.; Maclaughlin, D. E.; Bernal, O. O.; Ohta, Y.; Nakatsuji, S.

    2010-03-01

    In the pyrochlore iridate Eu2Ir2O7 [1,,] Eu^3+ is nonmagnetic (L = S, J = 0) and S(Ir^4+) = 1/2 [1], so that it is a rare example of a frustrated S=1/2 pyrochlore. Spin-glass-like behavior at the metal-insulator transition (MIT) and no magnetic ordering down to 0.3 K have been reported for this compound [2,,]. We discuss ?SR measurements on Eu2Ir2O7 polycrystalline samples that yield strong evidence for long-range magnetic ordering. We observe well-defined muon spin precession frequencies below TM 120 K, consistent with the MIT temperature [2] but indicating long-range ordering instead of a spin-glass like transition. Significant dynamic muon spin relaxation persists to low temperatures, as is often the case in frustrated antiferromagnets. Work supported by NSF (U.S.), Grants 0801407 (UCR) and 0604105 (CSULA), and MEXT (Japan), Grants-in-Aid Nos. 17071003 and 19052003. [1] B. J. Kim et al., Phys. Rev.Lett. 101, 076402 (2008). [2] N. Taira et al., J. Phys.: Condens. Matter 13, 5527 (2001). [3] C. L. Chien and A. W. Sleight, Phys. Rev. B 18, 2031 (1978).

  16. p-wave optical Feshbach resonances in {sup 171}Yb

    SciTech Connect

    Goyal, Krittika; Deutsch, Ivan; Reichenbach, Iris

    2010-12-15

    We study the use of an optical Feshbach resonance to modify the p-wave interaction between ultracold polarized {sup 171}Yb spin-1/2 fermions. A laser exciting two colliding atoms to the {sup 1}S{sub 0}+{sup 3}P{sub 1} channel can be detuned near a purely-long-range excited molecular bound state. Such an exotic molecule has an inner turning point far from the chemical binding region, and thus, three-body recombination in the Feshbach resonance will be highly suppressed in contrast to that typically seen in a ground-state p-wave magnetic Feshbach resonance. We calculate the excited molecular bound-state spectrum using a multichannel integration of the Schroedinger equation, including an external perturbation by a magnetic field. From the multichannel wave functions, we calculate the Feshbach resonance properties, including the modification of the elastic p-wave scattering volume and inelastic spontaneous scattering rate. The use of magnetic fields and selection rules for polarized light yields a highly controllable system. We apply this control to propose a toy model for three-color superfluidity in an optical lattice for spin-polarized {sup 171}Yb, where the three colors correspond to the three spatial orbitals of the first excited p band. We calculate the conditions under which tunneling and on-site interactions are comparable, at which point quantum critical behavior is possible.

  17. Bonding and elastic properties of amorphous AlYB14

    NASA Astrophysics Data System (ADS)

    Music, Denis; Hensling, Felix; Pazur, Tomas; Bednarcik, Jozef; Hans, Marcus; Schnabel, Volker; Hostert, Carolin; Schneider, Jochen M.

    2013-09-01

    We have studied the bonding and elastic properties of amorphous AlYB14 using theoretical and experimental means. Based on pair distribution functions and Voronoi tessellation, the icosahedral bonding is expected. A rather large Young's modulus of 365 GPa is predicted for amorphous AlYB14. To verify these predictions, we have measured density, pair distribution functions, binding energy and elastic properties of Al-Y-B thin films synthesized by magnetron sputtering. The calculated and measured densities are with a deviation of 3.5% in good agreement. The measured binding energy and pair distribution functions are also consistent with icosahedral bonding. The measured Young's modulus is 305±19 GPa, which is 16% smaller than the theoretical value and hence in good agreement. Overall consistency between theory and experiments was obtained indicating that the computational strategy employed here is useful to describe correlations between bonding, elasticity, density as well as (chemical) short range order and may hence enable future knowledge-based design of these ternary borides which show great potential for surface protection applications.

  18. Optical Lattice Induced Light Shifts in an Yb Atomic Clock

    SciTech Connect

    Barber, Z. W.; Stalnaker, J. E.; Lemke, N. D.; Poli, N.; Oates, C. W.; Fortier, T. M.; Diddams, S. A.; Hollberg, L.; Hoyt, C. W.; Taichenachev, A. V.; Yudin, V. I.

    2008-03-14

    We present an experimental study of the lattice-induced light shifts on the {sup 1}S{sub 0}{yields}{sup 3}P{sub 0} optical clock transition ({nu}{sub clock}{approx_equal}518 THz) in neutral ytterbium. The 'magic' frequency {nu}{sub magic} for the {sup 174}Yb isotope was determined to be 394 799 475(35) MHz, which leads to a first order light shift uncertainty of 0.38 Hz. We also investigated the hyperpolarizability shifts due to the nearby 6s6p{sup 3}P{sub 0}{yields}6s8p{sup 3}P{sub 0}, 6s8p{sup 3}P{sub 2}, and 6s5f{sup 3}F{sub 2} two-photon resonances at 759.708, 754.23, and 764.95 nm, respectively. By measuring the corresponding clock transition shifts near these two-photon resonances, the hyperpolarizability shift was estimated to be 170(33) mHz for a linear polarized, 50 {mu}K deep, lattice at the magic wavelength. These results indicate that the differential polarizability and hyperpolarizability frequency shift uncertainties in a Yb lattice clock could be held to well below 10{sup -17}.

  19. Photoluminescence properties and energy levels of RE (RE?=?Pr, Sm, Er, Tm) in layered-CaZnOS oxysulfide

    SciTech Connect

    Zhang, Zhi-Jun; Feng, Ang; Chen, Xiang-Yang; Zhao, Jing-Tai

    2013-12-07

    RE{sup 3+} (RE?=?Pr, Sm, Er, Tm)-activated CaZnOS samples were prepared by a solid-state reaction method at high temperature, and their photoluminescence properties were investigated. Doping with RE{sup 3+} (RE?=?Pr, Sm, Er, Tm) into layered-CaZnOS resulted in typical RE{sup 3+} (RE?=?Pr, Sm, Er, Tm) f-f line absorptions and emissions, as well as the charge transfer band of Sm{sup 3+} at about 3.3?eV. The energy level scheme containing the position of the 4f and 5d levels of all divalent and trivalent lanthanide ions with respect to the valence and conduction bands of CaZnOS has been constructed based on the new data presented in this work, together with the data from literature on Ce{sup 3+} and Eu{sup 2+} doping in CaZnOS. The detailed energy level scheme provides a platform for interpreting the optical spectra and could be used to comment on the valence stability of the lanthanide ions in CaZnOS.

  20. Diode pumped Yb-lasers Q-switched by V:YAG saturable absorber

    NASA Astrophysics Data System (ADS)

    Šulc, Jan; Kaskow, Mateusz; Jelínková, Helena; Jabczynski, Jan K.

    2014-12-01

    V:YAG saturable absorber, developed mainly for 1.3 ?m lasers Q-switching, was used as a passive Q-switch for the 1.03 ?m Yb-doped YAG (10% Yb/Y, 3mm long) and LuAG (15% Yb/Lu, 1mm long) lasers. Longitudinally diode pumped gain medium together with the V:YAG crystal were placed inside the 22mm long hemispherical laser cavity. For Yb-doped crystal excitation fibre-coupled (fibre core diameter 100 ?m) laser diode (max power amplitude 20W, emission wavelength 968 nm) was used. The laser diode was operating in a pulsed regime (repetition rate 10 Hz, pumping pulse width 2 ms) to reduce parasitic thermal effects inside the gain medium. Stable Q-switching was obtained for laser output coupler reflectivity 70% and V:YAG initial transmission 70% at Yb laser emission wavelength. For the both tested active media the parameters of the generated giant pulses were similar. Pulses with duration of 2.5 ns (FWHM), energy about 0.3 mJ, and peak power up to 120kW were generated. The maximal Q-switched pulses repetition rate inside the single pumping pulse was 6.6 kHz in case of Yb:YAG and 8.6 kHz in case of Yb:LuAG. The beam transversal profile was close to the fundamental Gaussian mode. The output was partially polarized.

  1. Microstructure and luminescence of Yb{sup 3+}-doped fluorosilicate glass ceramics

    SciTech Connect

    Qiao, Xvsheng; Fan, Xianping; Pan, Yu; Lotnyk, Andriy; Kienle, Lorenz

    2012-01-15

    Highlights: Black-Right-Pointing-Pointer Fine nano-SrF{sub 2} lattices were observed in the fluorosilicate glass ceramics. Black-Right-Pointing-Pointer EDXS analysis showed Yb{sup 3+} was enriched into the SrF{sub 2} nanocrystals. Black-Right-Pointing-Pointer That deduced intense cooperative luminescence of the glass ceramics. Black-Right-Pointing-Pointer NIR emissions appeared large bandwidths and long lifetimes simultaneously. Black-Right-Pointing-Pointer Yb{sup 3+} can be an efficient upconversion sensitizer or NIR activator in this host. -- Abstract: Yb{sup 3+}-doped transparent glass ceramics containing cubic SrF{sub 2} nanocrystals were prepared by heat treating the precursor fluorosilicate glass. The precipitated crystals increase in size and the crystallinity decreases with increasing Yb{sup 3+} doping level. With high-resolution transmission electron microscopy and electron diffraction, the nano-sized nature of SrF{sub 2} was clearly observed. Owing to a significant change in the crystal-field effects with Yb{sup 3+} enriching in the SrF{sub 2} phase, the glass ceramics present near infrared emission with large bandwidths and long lifetimes, simultaneously. This indicates the glass ceramics have potential application in the efficient IR lasers pumping by InGaAs diodes. The glass ceramics can also emit blue upconversion luminescence, deriving from Yb{sup 3+} pairs' cooperative luminescence. It suggested that Yb{sup 3+} can be an efficient upconversion sensitizer for other rare earth ions.

  2. 78 FR 28258 - mPower\\TM\\ Design-Specific Review Standard

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-05-14

    ... COMMISSION mPower\\TM\\ Design-Specific Review Standard AGENCY: Nuclear Regulatory Commission. ACTION: Design-Specific Review Standard (DSRS) for the mPower\\TM\\ Design; request for comment. SUMMARY: The U.S. Nuclear... the mPower\\TM\\ design (mPower\\TM\\ DSRS). The purpose of the mPower\\TM\\ DSRS is to more fully...

  3. Optical Properties of Tm(3+) Ions in Alkali Germanate Glass

    NASA Technical Reports Server (NTRS)

    Walsh, Brian M.; Barnes, Norman P.; Reichle, Donald J.; Jiang, Shibin

    2006-01-01

    Tm-doped alkali germanate glass is investigated for use as a laser material. Spectroscopic investigations of bulk Tm-doped germanate glass are reported for the absorption, emission and luminescence decay. Tm:germanate shows promise as a fiber laser when pumped with 0.792 m diodes because of low phonon energies. Spectroscopic analysis indicates low nonradiative quenching and pulsed laser performance studies confirm this prediction by showing a quantum efficiency of 1.69.

  4. 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 (?R(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, ?, ?1, ?2, Im ?1-1, neff, ?eff) 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.

  5. Calibration of the EU Oxybarometer for Nakhlites

    NASA Technical Reports Server (NTRS)

    Makishima, J.; McKay, G.; Le, L.; Miyamoto; Mikouchi, T.

    2006-01-01

    Martian meteorites have various characteristics, which are direct clues to understanding the petrogenesis of Mars rocks. The variation in oxidation state among the Martian meteorites must have important implications for redox conditions of the Martian crust/mantle and overall differentiation on Mars. Wadhwa [1] and Herd et al. [2] reported that Martian basalts were formed under a range of oxidation states, suggesting complex petrogenesis processes. The nakhlites, which have rather different characteristics from basaltic shergottites, may give us additional clues to Martian petrogenesis. The oxidation states of meteorites are usually described by the oxygen fugacity (fO2) under which the meteorites crystallized. One of the methods to estimate the oxygen fugacity is the depth of Eu anomaly. Eu(2+)/Eu(3+) is determined by the oxygen fugacity and partitioning is different for Eu(2+) and Eu(3+). Therefore, the depth of Eu anomaly in a mineral is a function of the oxygen fugacity and the Eu2+/Eu3+ in the melt from which the mineral crystallized. This method has some advantages over another major method, the two-oxide oxybarometer [3], which can more easily be affected by subsolidus processes. The Eu oxybarometer can analyze the cores of the earliest formed crystals in Martian meteorites, which means it can give us a better indication of the oxygen fugacity of the parent melt. The calibration of the Eu oxybarometer has been done with the basaltic shergottites before [4]. However, it has never been applied to nakhlites (Oe et al. [5] measured the depth of Eu anomaly in the synthetic pyroxene only at QFM). Partition coefficients are strongly affected by phase compositions, especially pyroxene Ca content and melt Al content [e.g., 5,6]. The composition of nakhlite pyroxene is rather different from basaltic shergottite pyroxene. Thus, there may be problems in applying the Eu oxybarometer calibration for the basaltic shergottites [7] to nakhlites. Thus, we report in this abstract preliminary results of our experimental calibration of the depth of Eu anomaly in pyroxene vs. oxygen fugacity for nakhlites.

  6. Mechanism of tantalum adhesion on SiLK{sup TM}

    SciTech Connect

    Hu Yue; Yang Shuowang; Chen Xiantong; Lu Dong; Feng Yuanping; Wu Ping

    2005-09-19

    Tantalum adhesion on SiLK{sup TM} was investigated using first-principles method based on density functional theory. Phenylene groups were found to play a major role and the adjacent semi-benzene rings also contribute significantly to Ta adhesion on SiLK{sup TM}. In addition, the degradation effects of H{sub 2}/He reactive plasma clean on Ta adhesion on SiLK{sup TM} was investigated. Based on our findings, argon plasma treatment was suggested and implemented after reactive plasma cleaning process, which resulted in integration of SiLK{sup TM} with Cu up to seven metal layers.

  7. Phase stability regions in the Na 2CO 3-YbF 3-H 2O system at 190 °C. Crystal structures of two new fluoride carbonates, Na 2Yb(CO 3) 2F and Na 3Yb(CO 3) 2F 2

    NASA Astrophysics Data System (ADS)

    Ben Ali, Amor; Maisonneuve, Vincent; Leblanc, Marc

    2002-11-01

    Phase stability regions in the Na 2CO 3-YbF 3-H 2O system at T=190 °C, P=11×10 5 Pa, t=1 h, microwave heating, and the crystal structures of two new carbonate fluorides Na 2Yb(CO 3) 2F and Na 3Yb(CO 3) 2F 2 are presented. Five phases, obtained for [YbF 3]?0.75 M and [Na]/[Yb]<30, are characterized by powder or single crystal X-ray diffraction, thermogravimetric or chemical analyses: NaYb(CO 3)F 2, Na 2Yb(CO 3) 2F, Na 3Yb(CO 3) 2F 2, Na 5Yb(CO 3) 4·2H 2O, and Yb(CO 3)(OH,F)· xH 2O. NaYb(CO 3)F 2 ( a=6.897(7) Å, b=9.118(9) Å, c=6.219(6) Å) and Na 5Yb(CO 3) 4·2H 2O are isostructural with NaY(CO 3)F 2 (horvathite) and Na 5Sc(CO 3) 4·2H 2O, respectively; the other phases were still unknown. Na 2Yb(CO 3) 2F is monoclinic, C2/ c, with a=17.440(6) Å, b=6.100(2) Å, c=11.237(1) Å, ?=95.64(3)°; V=1189.7(4) Å 3; Z=8 (1729 unique reflections, R=0.034, Rw=0.087). Na 2Yb(CO 3) 2F is described from infinite [001] chains [YbO 5F] ? built up from [YbO 6F] 2 dimers. Na 3Yb(CO 3) 2F 2 is noncentrosymmetric, Cc, with a=7.127(2) Å, b=29.916(9) Å, c=6.928(4) Å, ?=112.56(3)°; V=1359(4) Å 3; Z=8 (1838 unique reflections, R=0.074, Rw=0.235). The structure is built up from [NaYb(CO 3) 2F 2] ? layers; Yb 3+ and Na + cations are alternatively ordered and disordered in successive (010) layers which are separated by other Na + cations.

  8. Cold beam of isotopically pure Yb atoms by deflection using 1D-optical molasses

    E-print Network

    Rathod, K D; Natarajan, Vasant

    2013-01-01

    We demonstrate generation of an isotopically pure beam of laser-cooled Yb atoms by deflection using 1D-optical molasses. Atoms in a collimated thermal beam are first slowed using a Zeeman Slower. They are then subjected to a pair of molasses beams inclined at $45^\\circ$ with respect to the slowed atomic beam. The slowed atoms are deflected and probed at a distance of 160 mm. We demonstrate selective deflection of the bosonic isotope $^{174}$Yb, and the fermionic isotope $^{171}$Yb. Using a transient measurement after the molasses beams are turned on, we find a longitudinal temperature of 41 mK.

  9. Cold beam of isotopically pure Yb atoms by deflection using 1D-optical molasses

    NASA Astrophysics Data System (ADS)

    Rathod, K. D.; Singh, P. K.; Natarajan, Vasant

    2014-09-01

    We demonstrate generation of an isotopically pure beam of laser-cooled Yb atoms by deflection using 1D-optical molasses. Atoms in a collimated thermal beam are first slowed using a Zeeman Slower. They are then subjected to a pair of molasses beams inclined at $45^\\circ$ with respect to the slowed atomic beam. The slowed atoms are deflected and probed at a distance of 160 mm. We demonstrate selective deflection of the bosonic isotope $^{174}$Yb, and the fermionic isotope $^{171}$Yb. Using a transient measurement after the molasses beams are turned on, we find a longitudinal temperature of 41 mK.

  10. Mode-locked operation of a diode-pumped femtosecond Yb:SrF2 laser.

    PubMed

    Druon, F; Papadopoulos, D N; Boudeile, J; Hanna, M; Georges, P; Benayad, A; Camy, P; Doualan, J L; Ménard, V; Moncorgé, R

    2009-08-01

    Femtosecond mode-locked operation is demonstrated for the first time, to our knowledge, with a Yb:SrF(2) crystal. The shortest pulse duration is 143 fs for an average power of 450 mW. The highest average power is 620 mW for a pulse duration of 173 fs. Since Yb:SrF(2) corresponds to the longest-lifetime Yb-doped crystal with which the mode-locking operation has been achieved, a detailed analysis is carried out to characterize the quality of the solitonlike regime. PMID:19649095

  11. Yb-doped silica preform precursor nanoparticles and the photodarkening in them

    NASA Astrophysics Data System (ADS)

    Xiong, Liangming; Sekiya, Edson H.; Saito, Kazuya

    2009-11-01

    A series of Yb-doped silica-based nanoparticles were fabricated in the MCVD process. Their compositions and doping levels were well controlled from 0 to 0.53 wt% for Yb and from 0 to 2.1 wt% for Al. The nanoparticles are of about 21.3 +/- 4.6 nm in size, but their sizes and NIR absorption are influenced by the Al concentration. At a fixed Al doping level, the NIR absorption depends on the Yb concentration. The nanoparticles exhibit a strong composition dependence of the photodarkening induced by the X-ray irradiation.

  12. Yb:FAP and related materials, laser gain medium comprising same, and laser systems using same

    DOEpatents

    Krupke, William F. (Pleasanton, CA); Payne, Stephen A. (Castro Valley, CA); Chase, Lloyd L. (Livermore, CA); Smith, Larry K. (Salida, CA)

    1994-01-01

    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.

  13. Continuous wave Yb:YCOB cyan lasers with KTP as the sum-frequency converter

    NASA Astrophysics Data System (ADS)

    Lan, Ruijun; Cheng, Hao; Yang, Guang

    2015-12-01

    All-solid-state cyan laser at 500 nm range are reported based on a Yb:YCa4O(BO3)3 (Yb:YCOB) crystal and a type-II phase matched KTiOPO4 (KTP) crystal. The 503 nm cyan laser is obtained by the sum-frequency mixing (SFM) of 974 nm pump wave and 1042 nm fundamental wave. To the best of our knowledge, this is the first cyan laser demonstrated with Yb-doped YCOB crystal. A dual-wavelength laser at 505 and 525 nm is also obtained, which origins from the simultaneous SFM and self-frequency doubling.

  14. Infrared spectroscopic and density functional theoretical study of tris(cyclopentadienyl)ytterbium (YbCp3) and acetone adduct molecules of YbCp3 in low-temperature matrices

    NASA Astrophysics Data System (ADS)

    Miyazaki, Jun; Sudo, Nao; Yamada, Yasuhiro

    2015-08-01

    Tris(cyclopentadienyl)ytterbium (YbCp3) was isolated in solid argon matrices, and the monomeric structure of YbCp3 was studied by means of infrared spectroscopy and density functional theory calculations. Compared with our previous study on the structure of tris(cyclopentadienyl)scandium (ScCp3) isolated in solid argon matrices, it was apparent that the monomeric structure of YbCp3 has three ?5-Cp bonds to the Yb atom, Yb(?5-Cp)3, analogous to the structure of matrix-isolated ScCp3. In addition, the stable dimer structures of YbCp3 were also predicted using density functional theory calculations. Furthermore, we produced the acetone adduct molecules of YbCp3 for the first time by co-condensing YbCp3 and an acetone/argon mixture gas on a cold substrate at 20 K. Molecules with Ybsbnd O bonding between YbCp3 and acetone were detected in low-temperature acetone/argon matrices. By using natural bond orbital (NBO) and curve fitting analysis, the structures of the acetone adduct molecules of YbCp3 were deduced.

  15. TE/TM Simulations of Interferometric Measurements

    NASA Technical Reports Server (NTRS)

    Houshmand, Bijan

    2000-01-01

    Interferometric synthetic aperture radar (IFSAR) measurements at X-, C-, L-, and P-band are used to derive ground topography at meter level resolution. Interpretation of the derived topography requires attention due to the complex interaction of the radar signal with ground cover. The presence of penetrable surfaces such as vegetation, and tree canopies poses a challenge since the depth of penetration depends on a number of parameters such as the operating radar frequency, polarization, incident angle, as well as terrain structure. The dependence of the reconstructed topography on polarization may lead to the characterization of the ground cover. Simulation of interferometric measurements is useful for interpretation of the derived topography (B. Houshmand, Proceedings of URSI, 314, 1997). In this talk , time domain simulations for interferometric measurement for TE- and TM- polarization are presented. Time domain simulation includes the effects of the surface material property as well geometry comparable the radar signal wavelength (B. Houshmand, Proceedings of the URSI, 25, 1998). The IFSAR simulation is carried out in two steps. First, the forward scattering data is generated based on full wave analysis. Next, the electromagnetic information is inverted to generate surface topography. This inversion is based on the well known IFSAR processing technique which is composed of signal compression, and formation of an interferogram. The full wave forward scattering data is generated by the scattered-field formulation of the FDTD algorithm. The simulation is carried out by exciting the computational domain by a radar signal. The scattered field is then computed and translated to the receiving interferometric antennas using the time-domain Huygen's principle. The inversion process starts by compressing the time-domain data. The range compressed data from both receivers are then coregistered to form an interferogram. The resulting interferogram is then related to the ground topography using the radar imaging geometry. In this talk, the simulation results are compared with the C-band TM IFSAR derived topography, and the TE/TM SAR images at L-Band.

  16. Graphing Calculators, the CBL2[TM] and TI-Interactive[TM] in High School Science.

    ERIC Educational Resources Information Center

    Molnar, Bill

    This collection of activities is designed to show how TI-Interactive[TM] and Calculator-based Laboratories (CBL) can be used to explore topics in high school science. The activities address such topics as specific heat, Boyle's Law, Newton's Law of Cooling, and Antarctic Ozone Levels. Teaching notes and calculator instructions are included as are…

  17. Suppression of the anti-trimellityl (TM) IgE response in mice by conjugates of TM with polyvinyl alcohol.

    PubMed

    Wei, B Y; Holford-Strevens, V; Carter, B G; Sehon, A H

    1984-04-01

    The i.p. injection of 1 microgram of TM3-OA or TM9-OA with 1 mg of A1(OH)3 into B6D2F1 mice elicited the production of antibodies of the IgE and other classes to the trimellityl (TM) group and ovalbumin (OA). The induction of anti-TM antibodies belonging to the IgE and other immunoglobulin classes was specifically suppressed by the administration of tolerogenic conjugates prepared by coupling trimellitic anhydride (TMA) to the hydrophilic non-immunogenic polymer, polyvinyl alcohol (PVA), prior to immunization with TM-OA conjugates. More importantly, established anti-TM responses were also suppressed by these TM-PVA conjugates. By contrast, however, treatment with TM-PVA conjugates did not affect either the primary or the established anti-OA antibody response. The tolerogenic effects of the PVA conjugates were dose-dependent and appeared also to be dependent on the epitope density. Treatment with these conjugates also prevented immunized mice from showing any symptoms of systemic anaphylaxis on challenge with polyvalent TM-protein conjugates. These findings indicate that these conjugates may have the potential of useful therapeutic agents for the treatment of TMA-induced pulmonary hypersensitivity diseases. PMID:6706377

  18. Crossover from a heavy fermion to intermediate valence state in noncentrosymmetric Yb2Ni12(P,As)7.

    PubMed

    Jiang, W B; Yang, L; Guo, C Y; Hu, Z; Lee, J M; Smidman, M; Wang, Y F; Shang, T; Cheng, Z W; Gao, F; Ishii, H; Tsuei, K D; Liao, Y F; Lu, X; Tjeng, L H; Chen, J M; Yuan, H Q

    2015-01-01

    We report measurements of the physical properties and electronic structure of the hexagonal compounds Yb2Ni12Pn7 (Pn?=?P, As) by measuring the electrical resistivity, magnetization, specific heat and partial fluorescence yield x-ray absorption spectroscopy (PFY-XAS). These demonstrate a crossover upon reducing the unit cell volume, from an intermediate valence state in Yb2Ni12As7 to a heavy-fermion paramagnetic state in Yb2Ni12P7, where the Yb is nearly trivalent. Application of pressure to Yb2Ni12P7 suppresses TFL, the temperature below which Fermi liquid behavior is recovered, suggesting the presence of a quantum critical point (QCP) under pressure. However, while there is little change in the Yb valence of Yb2Ni12P7 up to 30?GPa, there is a strong increase for Yb2Ni12As7 under pressure, before a near constant value is reached. These results indicate that any magnetic QCP in this system is well separated from strong valence fluctuations. The pressure dependence of the valence and lattice parameters of Yb2Ni12As7 are compared and at 1?GPa, there is an anomaly in the unit cell volume as well as a change in the slope of the Yb valence, indicating a correlation between structural and electronic changes. PMID:26626431

  19. Investigation of continuous-wave and Q-switched microchip laser characteristics of Yb:YAG ceramics and crystals

    NASA Astrophysics Data System (ADS)

    Dong, Jun; Xu, Guozhang; Ma, Jian; Cao, Mengjun; Cheng, Ying; Ueda, Ken-ichi; Yagi, Hideki; Kaminskii, Alexander A.

    2012-04-01

    Continuous-wave and passively Q-switched microchip laser performance of Yb:YAG ceramics and single-crystals was investigated. Highly efficient continuous-wave Yb:YAG laser performance was observed at 1030 nm and 1049 nm for both Yb:YAG ceramics and crystals with different transmissions of output couplers. The laser performance of Yb:YAG ceramic is comparable to that of Yb:YAG single crystal. Meanwhile, the laser performance of laser-diode pumped Yb:YAG/Cr4+:YAG all-ceramics- and all-crystals-combination passively Q-switched microchip lasers were investigated. Sub-nanosecond laser pulses with peak power over 150 kW were obtained with different Yb:YAG/Cr4+:YAG combinations. Linearly polarized laser was observed in Yb:YAG/Cr4+:YAG all-crystals combination and circular polarized laser was obtained in Yb:YAG/Cr4+:YAG all-ceramics combination. The best laser performance was obtained with Yb:YAG/Cr4+:YAG all-crystals combination.

  20. Crossover from a heavy fermion to intermediate valence state in noncentrosymmetric Yb2Ni12(P,As)7

    PubMed Central

    Jiang, W. B.; Yang, L.; Guo, C. Y.; Hu, Z.; Lee, J. M.; Smidman, M.; Wang, Y. F.; Shang, T.; Cheng, Z. W.; Gao, F.; Ishii, H.; Tsuei, K. D.; Liao, Y. F.; Lu, X.; Tjeng, L. H.; Chen, J. M.; Yuan, H. Q.

    2015-01-01

    We report measurements of the physical properties and electronic structure of the hexagonal compounds Yb2Ni12Pn7 (Pn?=?P, As) by measuring the electrical resistivity, magnetization, specific heat and partial fluorescence yield x-ray absorption spectroscopy (PFY-XAS). These demonstrate a crossover upon reducing the unit cell volume, from an intermediate valence state in Yb2Ni12As7 to a heavy-fermion paramagnetic state in Yb2Ni12P7, where the Yb is nearly trivalent. Application of pressure to Yb2Ni12P7 suppresses TFL, the temperature below which Fermi liquid behavior is recovered, suggesting the presence of a quantum critical point (QCP) under pressure. However, while there is little change in the Yb valence of Yb2Ni12P7 up to 30?GPa, there is a strong increase for Yb2Ni12As7 under pressure, before a near constant value is reached. These results indicate that any magnetic QCP in this system is well separated from strong valence fluctuations. The pressure dependence of the valence and lattice parameters of Yb2Ni12As7 are compared and at 1?GPa, there is an anomaly in the unit cell volume as well as a change in the slope of the Yb valence, indicating a correlation between structural and electronic changes. PMID:26626431

  1. Pressure-Induced Valance change in Ytterbium Organometallic Molecule Cp*2Yb(4,4'-Me2-bipy) and Ytterbium intermetallic YbCuGa

    NASA Astrophysics Data System (ADS)

    Nasreen, Farzana; Antonio, Daniel; Cornelius, Andrew; Booth, Corwin; Torikachvili, Milton; Xiao, Yuming

    2013-06-01

    We report on high pressure (0-15.3 GPa) x-ray absorption measurements in partial fluorescence yield mode (PFY-XAS) on two different kinds of Kondo systems - an organometallic molecular system Cp*2Yb(4,4'-Me2-bipy)[Cp*=C5Me5, bipy=(NC5H4)2 and Me = CH3] and an intermetallic YbCuGa system. In the organometallic system, similar to the mixed valency in intermetallic Yb Kondo systems, the CASSCF calculations indicate that the intermediate valence in the ground state is due to a configuration interaction between the open-shell [4f?13??* 1 ] and the closed-shell [4f??14?*0 ] spin-singlet states. Our analysis for Cp*2Yb(4,4'-Me2-bipy) shows that with increase in pressure the overall valency increases from 2.77 at 2.7 GPa to 2.97 at 15.3 GPa. A considerable change in the slope of valency as function of pressure is observed at ~3.26 GPa suggesting a valance transition. The Kondo effect in such molecular compounds is intrinsic and provides a well defined nanoscale system to test the effect of size on the strongly correlated behavior. In the YbCuGa bulk system, the increase in pressure delocalizes the system and pushes it from valency of ~2.68 at ambient pressure to ~2.9 at 14.0 GPa.

  2. Comparative 3-D Modeling of tmRNA

    PubMed Central

    Burks, Jody; Zwieb, Christian; Müller, Florian; Wower, Iwona; Wower, Jacek

    2005-01-01

    Background Trans-translation releases stalled ribosomes from truncated mRNAs and tags defective proteins for proteolytic degradation using transfer-messenger RNA (tmRNA). This small stable RNA represents a hybrid of tRNA- and mRNA-like domains connected by a variable number of pseudoknots. Comparative sequence analysis of tmRNAs found in bacteria, plastids, and mitochondria provides considerable insights into their secondary structures. Progress toward understanding the molecular mechanism of template switching, which constitutes an essential step in trans-translation, is hampered by our limited knowledge about the three-dimensional folding of tmRNA. Results To facilitate experimental testing of the molecular intricacies of trans-translation, which often require appropriately modified tmRNA derivatives, we developed a procedure for building three-dimensional models of tmRNA. Using comparative sequence analysis, phylogenetically-supported 2-D structures were obtained to serve as input for the program ERNA-3D. Motifs containing loops and turns were extracted from the known structures of other RNAs and used to improve the tmRNA models. Biologically feasible 3-D models for the entire tmRNA molecule could be obtained. The models were characterized by a functionally significant close proximity between the tRNA-like domain and the resume codon. Potential conformational changes which might lead to a more open structure of tmRNA upon binding to the ribosome are discussed. The method, described in detail for the tmRNAs of Escherichia coli, Bacillus anthracis, and Caulobacter crescentus, is applicable to every tmRNA. Conclusion Improved molecular models of biological significance were obtained. These models will guide in the design of experiments and provide a better understanding of trans-translation. The comparative procedure described here for tmRNA is easily adopted for the modeling the members of other RNA families. PMID:15958166

  3. 76 FR 38618 - Proposed Information Collection; Comment Request; StormReadyTM

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-07-01

    ...Ready\\TM\\, TsunamiReady\\TM\\ and StormReady/TsunamiReady\\TM\\ Application Forms AGENCY: National Oceanic... TsunamiReady and StormReady/TsunamiReady programs also in this information collection, is a...

  4. 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(?) 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. PMID:24495311

  5. Field-dependent Collective ESR Mode in YbRh2Si2

    SciTech Connect

    Petrovic, C.; Holanda, L.M.; Duque, J.G.S.; Bittar, E.M.; Adriano, C.; Pagliuso, P.G.; Rettori, C.; Hub, R.W.; Maquilon, S.; Fisk, Z.; Huber, D.L.; Oseroff, S.B.

    2009-10-15

    Electron spin resonance (ESR) experiments in YbRh{sub 2}Si{sub 2} Kondo lattice (T{sub K} {approx_equal} 25 K) at different field/frequencies (4.1 {le} v {le} 34.4 GHz) and H{sub {perpendicular}c} revealed: (i) a strong field dependent Yb{sup 3+} spin-lattice relaxation, (ii) a weak field and T-dependent effectiveg-value, (iii) a suppression of the ESR intensity beyond 15% of Lu-doping, and (iv) a strong sample and Lu-doping ({le}15%) dependence of the ESR data. These results suggest that the ESR signal in YbRh{sub 2}Si{sub 2} may be due to a coupled Yb{sup 3+}-conduction electron resonant collective mode with a subtle field-dependent spins dynamic.

  6. Influence of Yb3+ concentration on upconversion luminescence of Ho3+

    E-print Network

    Cao, Wenwu

    acid was added into the solution with a 1:3 mole ratio of (Y+ Ho+Yb) to citric acid. After complete nitrates in corresponding molar ratios were completely dissolved in de-ionized water. Subsequently, citric

  7. Growth and scintillation properties of Yb-doped Lu 3Al 5O 12 crystals

    NASA Astrophysics Data System (ADS)

    Ogino, Hiraku; Yoshikawa, Akira; Lee, Jong-Ho; Nikl, Martin; Solovieva, Natalia; Fukuda, Tsuguo

    2003-06-01

    Yb-doped Lu 3Al 5O 12 (Yb:LuAG) single crystals were grown by the micro-pulling-down (?-PD) method. The crystals were seeded-grown in the <1 1 1> direction and dimensions up to 300 mm in length and 5 mm in diameter were achieved. Photoluminescence spectra and decay kinetics of Yb:LuAG were studied after annealing. Under 225 nm excitation the double-peak emission at 335 and 480 nm was observed. Photoluminescence decay time of 23.9 ns was evaluated at 340 nm and T=80 K. Similar emission properties as those reported earlier for Yb-doped YAG crystal were obtained.

  8. Spectroscopic and Crystal Field Consequences of Fluoride Binding by [Yb?DTMA]3+ in Aqueous Solution

    PubMed Central

    Blackburn, Octavia A; Chilton, Nicholas F; Keller, Katharina; Tait, Claudia E; Myers, William K; McInnes, Eric J L; Kenwright, Alan M; Beer, Paul D; Timmel, Christiane R; Faulkner, Stephen

    2015-01-01

    Yb?DTMA forms a ternary complex with fluoride in aqueous solution by displacement of a bound solvent molecule from the lanthanide ion. [Yb?DTMA?F]2+ and [Yb?DTMA?OH2]3+ are in slow exchange on the relevant NMR timescale (<2000 s?1), and profound differences are observed in their respective NMR and EPR spectra of these species. The observed differences can be explained by drastic modification of the ligand field states due to the fluoride binding. This changes the magnetic anisotropy of the YbIII ground state from easy-axis to easy-plane type, and this change is easily detected in the observed magnetic anisotropy despite thermal population of more than just the ground state. The spectroscopic consequences of such drastic changes to the ligand field represent important new opportunities in developing fluoride-responsive complexes and contrast agents. PMID:26223970

  9. Spectroscopic properties and continuous-wave laser operation of Yb:Bi? Si? O?? crystal.

    PubMed

    Wang, Han; Chen, Yujin; Huang, Jianhua; Gong, Xinghong; Lin, Yanfu; Luo, Zundu; Huang, Yidong

    2014-09-01

    Yb3+:Bi4Si3O12 single crystal with Yb3+ concentration of 5.7 at.% has been grown successfully by the Czochralski method. The energy level positions of Yb3+ in Bi4Si3O12 crystal were determined based on the absorption and fluorescence spectra. The peak absorption cross-section is 0.98 × 10?20 cm2 at 976 nm and the peak emission cross-section is 0.57 × 10?20 cm2 at 1035 nm. The fluorescence lifetime of the excited multiplet is 1.26 ms. Diode-pumped continuous-wave laser operation around 1038 nm has been demonstrated in the Yb3+:Bi4Si3O12 crystal with a slope efficiency of 27% and maximum output power of 240 mW. PMID:25321561

  10. Optimization of the cooling profile to achieve crack-free Yb:S-FAP crystals

    SciTech Connect

    Fang, H; Qiu, S; Kheng, L; Schaffers, K; Tassano, J; Caird, J; Zhang, H

    2007-08-20

    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 this comparison, an optimal three-stage ramp-down profile was implemented and produced high quality, crack-free Yb:S-FAP crystals.

  11. New universality class of quantum criticality in Ce- and Yb-based heavy fermions.

    PubMed

    Watanabe, Shinji; Miyake, Kazumasa

    2012-07-25

    A new universality class of quantum criticality emerging in itinerant electron systems with strong local electron correlations is discussed. The quantum criticality of a Ce- or Yb-valence transition gives us a unified explanation for unconventional criticality commonly observed in heavy fermion metals such as YbRh(2)Si(2), ?-YbAlB(4), YbCu(5-x)Al(x), and CeIrIn(5). The key origin is due to the locality of the critical valence fluctuation mode emerging near the quantum critical end point of the first-order valence transition, which is caused by strong electron correlations for f electrons. The wider relevance of this new criticality and important future measurements to uncover its origin are also discussed. PMID:22771583

  12. Large core Yb-doped optical fiber through vapor phase doping technique

    NASA Astrophysics Data System (ADS)

    Saha, Maitreyee; Pal, Atasi; Pal, Mrinmay; Sen, Ranjan

    2013-05-01

    Rare earth (RE) doped optical fibers have shown tremendous progress for producing high power fiber lasers for industrial, medical and strategic applications. However, fabrication of large core, high Yb-doped fiber is still a challenge through conventional process due to poor repeatability and limitation regarding core size. This paper presents successful fabrication of Yb-doped fibers through vapor phase doping technique. Preform fabrication was carried out using a specially constructed MCVD system containing High Temperature Vapor Delivery Unit with sublimators for Al and Yb precursors. The novelty of the present work lies in deposition of Al2O3 and Yb2O3 in vapor phase simultaneously with silica during formation of sintered core layer which result in uniform dopants distribution in the preform. The fibers exhibited lasing efficiency of 76% with low `photodarkening effect'.

  13. Optical properties of Yb-doped fibers prepared by gas phase doping

    NASA Astrophysics Data System (ADS)

    Lindner, F.; Aichele, C.; Schwuchwo, A.; Leich, M.; Scheffel, A.; Unger, S.

    2014-03-01

    The active core diameter in silica preforms can be significantly increased by the deposition of ytterbium (Yb) and the most important codopant aluminum (Al) in the gas phase through the high-temperature evaporation of an Yb chelate compound and Al chloride in the Modified Chemical Vapor Deposition (MCVD) process. Here, we report on systematic investigations of the incorporation of Yb and Al into silica by gas phase doping technique. Preforms and fibers were prepared in a wide range of Yb and Al concentrations. The samples were characterized concerning the radial distribution of the refractive index and dopant concentrations, the efficiency of the deposition, and the absorption and emission properties in the NIR region. First laser experiments have demonstrated a slope efficiency of 80%, which is comparable to fibers made by MCVD/ solution doping and powder sinter technology.

  14. Loading a planar RF Paul Trap from a cold Yb? source

    E-print Network

    Shields, Brendan John

    2006-01-01

    In this thesis, we demonstrate a functioning planar radio frequency, three-rod Paul Trap, loaded with Yb+ ions that have been photoionized from a source of neutral atoms, which were cooled in a magneto-optical trap. Planar ...

  15. Continuous beam of laser-cooled Yb atoms

    NASA Astrophysics Data System (ADS)

    Rathod, K. D.; Singh, Alok K.; Natarajan, Vasant

    2013-05-01

    We demonstrate the launching of laser-cooled Yb atoms in a continuous atomic beam. The continuous cold beam has significant advantages over the more-common pulsed fountain, which was also demonstrated by us recently. The cold beam is formed in the following steps: i) atoms from a thermal beam are first Zeeman-slowed to a small final velocity; ii) the slowed atoms are captured in a two-dimensional magneto-optic trap (2D-MOT); and iii) atoms are launched continuously in the vertical direction using two sets of moving-molasses beams, inclined at ±15° to the vertical. The cooling transition used is the strongly allowed {^1S}_0 \\rightarrow {^1P}_1 transition at 399 nm. We capture about 7 × 106 atoms in the 2D-MOT, and then launch them with a vertical velocity of 13 m/s at a longitudinal temperature of 125(6) mK.

  16. Progress toward 174Yb BEC realization for Quantum Simulation

    NASA Astrophysics Data System (ADS)

    Mun, Jongchul; Lee, Jeongwon; Lee, Jae Hoon; Noh, Jiho

    2015-05-01

    We report the progress in building our experimental setup for 174Yb BEC. The experimental setup consists of the conventional Zeeman slower and new type of magneto-optical trap(MOT), which we propose and demonstrate for alkaline-earth-metal-like atoms. This new type of MOT, which we call core-shell MOT, utilizes both the broad 1S0 -->1P1 transition and the narrow 1S0 -->3P1 transition in two spatialy seperated regions. Experimental implementation of this scheme showed both faster loading and high atom numbers, by more than two orders and one order of magnitude respectively, compared to conventional MOT schemes. We plan to further cool and transfer the atomic sample into a science chamber by displacing an optical dipole trap using an optically compensated zoom-lens. The atoms will be loaded into an optical lattice for quantum simulations.

  17. TM Digital Image Products for Applications

    NASA Technical Reports Server (NTRS)

    Barker, J. L.; Gunther, F. J.; Abrams, R. B.; Ball, D. L.

    1984-01-01

    LANDSAT-4 Thematic Mapper (TM) digital image products recorded onto computer compatible tapes (CCTs), which were available for internal research purposes prior to August, 1983, are reviewed. The SCROUNGE image processing system at Goddard Space Flight Centr generated in tape formats: (1) raw band-sequential data (CCT-BT), generally used for internal transportation of digital data from one ground processing system to another; (2) calibrated data (CCT-AT), useful for reseachers doing radiometric characterization; and (3) geometrically resampled data (CCT-PT), the final product. The formats represent different steps in the process of producing fully-corrected TM data. The CCT-BT images are re-sequenced from telemetry format to image format, but are uncorrected radiometrically and geometrically. The CCT-AT images had data from two faulty data channels replaced and all data radiometrically calibrated. The CCT-PT images were resampled by cubic convolution procedures to provide a geometrically corrected image using satellite ephemeris and altitude data and scan-mirror correction data. The final product, the CCT-PT, is the one to which all of the radiometric and geometric corrections were applied.

  18. Accelerated Math[TM]. What Works Clearinghouse Intervention Report

    ERIC Educational Resources Information Center

    What Works Clearinghouse, 2011

    2011-01-01

    "Accelerated Math"[TM], published by Renaissance Learning, is a software tool used to customize assignments and monitor progress in math for students in grades 1-12. The "Accelerated Math"[TM] software creates individualized assignments aligned with state standards and national guidelines, scores student work, and generates reports on student…

  19. Relative radiometric calibration of LANDSAT TM reflective bands

    NASA Technical Reports Server (NTRS)

    Barker, J. L.

    1984-01-01

    A common scientific methodology and terminology is outlined for characterizing the radiometry of both TM sensors. The magnitude of the most significant sources of radiometric variability are discussed and methods are recommended for achieving the exceptional potential inherent in the radiometric precision and accuracy of the TM sensors.

  20. ISI TechnicalManual ISI/TM-88-197

    E-print Network

    Robins, Gabriel

    ISI TechnicalManual ISI/TM-88-197 February1988 University ofSouthern California Gabriel Robins %% ... ... .. The ISI Grapher Manual INFORMATION SCIENCES 213/822-1511 INSTITUTEJ f-"-676 292-t5466Admiralty Way. MONITORING ORGANIZATION REPORT NUMBER(S) ISI/TM-88-197 6a. NAME OF PERFORMING ORGANIZATION USC

  1. UNREL(TM) -REL to ASM translator Table of Contents

    E-print Network

    Mann, Tim

    . UNREL, DEDCODREL, SPLITLIB: Copyright O 1986/7Riclin Computer Products, All rights reserved. CP/M is a trademark of Digital Research Incorporated LDOS is a trademark of MISOSYS, Inc. LS-DOS a trademark on both the UNREL-T80 product (usable on a TRS-80 with either LDOS(TM) 5.x or LS-DOS(TM) 6.x

  2. Inside Linden Lab: Second Life [TM] for Educators

    ERIC Educational Resources Information Center

    Atkinson, Tom

    2008-01-01

    A new culture called Second Life [TM] has emerged that promises innovative strategies for everything from social interactions to business. Some educators believe it may hold new and unique opportunities for teaching and learning. Second Life [TM] (SL) is the creation of Linden Labs, a San Francisco-based corporation defined by its creators as "an…

  3. Utilising eduroam[TM] Architecture in Building Wireless Community Networks

    ERIC Educational Resources Information Center

    Huhtanen, Karri; Vatiainen, Heikki; Keski-Kasari, Sami; Harju, Jarmo

    2008-01-01

    Purpose: eduroam[TM] has already been proved to be a scalable, secure and feasible way for universities and research institutions to connect their wireless networks into a WLAN roaming community, but the advantages of eduroam[TM] have not yet been fully discovered in the wireless community networks aimed at regular consumers. This aim of this…

  4. Doors to Discovery[TM]. What Works Clearinghouse Intervention Report

    ERIC Educational Resources Information Center

    What Works Clearinghouse, 2007

    2007-01-01

    "Doors to Discovery"[TM] is an early childhood curriculum that uses thematic units to engage young children and support them as they build an understanding of their world. "Doors to Discovery"[TM] literacy activities are used to encourage children's development in a number of areas identified by research as the foundation for early literacy…

  5. LIBQUAL+TM LIBRARY SURVEY 2007 EXECUTIVE SUMMARY

    E-print Network

    Leung, Naichung Conan

    The University Library System conducted a library survey from November 1-30, 2007. The survey, called Lib1 LIBQUAL+TM LIBRARY SURVEY 2007 EXECUTIVE SUMMARY · The LibQual+TM Library Survey was conducted in November 2007. The Library received 2,928 valid responses and half of the respondents supplied written

  6. 75 FR 61480 - Cobscook Bay OCGenTM

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-10-05

    ... Energy Regulatory Commission Cobscook Bay OCGen\\TM\\ Power; Notice of Preliminary Permit Application..., pursuant to section 4(f) of the Federal Power Act, proposing to study the feasibility of the Cobscook Bay OCGen\\TM\\ Power Project, located in the Cobscook Bay, near the City of Eastport, Washington...

  7. 75 FR 61479 - Western Passage OCGenTM

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-10-05

    ... Energy Regulatory Commission Western Passage OCGen\\TM\\ Power Project; Notice of Preliminary Permit... permit, pursuant to section 4(f) of the Federal Power Act, proposing to study the feasibility of the Western Passage OCGen\\TM\\ Power Project, located in Western Passage, in the vicinity of the City...

  8. Social Stories[TM] for Children with Disabilities

    ERIC Educational Resources Information Center

    Reynhout, Georgina; Carter, Mark

    2006-01-01

    A review of the empirical research literature on Social Stories[TM] is presented, including a descriptive review and single-subject meta-analysis of appropriate studies. Examination of data suggests the effects of Social Stories[TM] are highly variable. Interpretations of extant studies are frequently confounded by inadequate participant…

  9. Full Immersive Virtual Environment Cave[TM] in Chemistry Education

    ERIC Educational Resources Information Center

    Limniou, M.; Roberts, D.; Papadopoulos, N.

    2008-01-01

    By comparing two-dimensional (2D) chemical animations designed for computer's desktop with three-dimensional (3D) chemical animations designed for the full immersive virtual reality environment CAVE[TM] we studied how virtual reality environments could raise student's interest and motivation for learning. By using the 3ds max[TM], we can visualize…

  10. Innovations: Simulation in Nursing Education Smart HospitalTM Innovation

    E-print Network

    Huang, Haiying

    Innovations: Simulation in Nursing Education ­ Smart HospitalTM Innovation *An innovation to the particular nursing program or may be new to nursing education in general; a response to the needs at Arlington College of Nursing Simulation in Nursing Education ­ Smart HospitalTM 2. Type of Nursing

  11. Fictive temperature dependences of optical properties in Yb-doped silica glass

    NASA Astrophysics Data System (ADS)

    Saito, K.; Yamamoto, R.; Kamiya, N.; Sekiya, E. H.; Barua, P.

    2008-04-01

    Correlation between Yb 3+ optical properties and structural disorder of glass network has been investigated by using good quality Yb-doped silica glasses fabricated by MCVD method. Absorption spectra strongly depend on the fictive temperature, which is a good indicator of structural disorder in silica glass. Their dependences are affected by the codopants (Al and F). Fictive temperature dependence of refractive index has been also elucidated.

  12. Synthesis, Structure, and Transport Properties of YbSb2Te4 and YbSb4Te7 for Thermoelectric Applications

    NASA Technical Reports Server (NTRS)

    Guloy, Amado S.

    2005-01-01

    Very little work has been done in the Yb-Sb-Te system of compounds. Exploratory synthesis of various compounds in the system has been performed in the search for new thermoelectric materials. The compounds in the system were examined due to the fact that the system is known to act as a concentrated Kondo system, a heavy fermion. Heavy fermions are known to possess high densities of state which are useful in thermoelectric applications. TWO compounds in the system, YbSb2Te4 and YbSb4Te7, have been successfully synthesized in bulk by two methods: low temperature mechanical alloying and high temperature direct synthesis. The Hall mobility, Seebeck coefficient, electrical resistivity, and thermal conductivity were measured on both the unannealed and annealed compounds up to 550 C to determine the dimensionless thermoelectric figure of merit, ZT. The results indicate that both compounds make promising candidates for use in thermoelectric devices.

  13. Optimization of signal gain and core composition for low photodegradation in Yb-doped fiber amplifiers

    NASA Astrophysics Data System (ADS)

    Laperle, Pierre; Desbiens, Louis; Zheng, Huimin; Le Foulgoc, Karine; Drolet, Mathieu; Deladurantaye, Pascal; Proulx, Antoine; Taillon, Yves

    2009-06-01

    Photodarkening and photobleaching processes affect the level of photodegradation of Yb-doped fibers. Characterization and modeling of each process is crucial to understand how to optimize the operating conditions of fiber amplifiers and lasers to obtain acceptable output power degradation. We show that photobleaching is a key factor in the modeling and simulation of a 10-ns pulsed Yb-doped LMA fiber amplifier. Each parameter of the model was separately determined from induced excess loss measurements under selective pump and wavelength excitations. The model was used to simulate accurately the measured fiber amplifier degradation. Optimized fiber length and gain were calculated to improve the output power stability over time and increase the fiber lifetime. Furthermore, eight fibers have been fabricated with various Yb, Al, and P content using the MCVD process to optimize the core composition. The level of photodarkening in each fiber was evaluated by measuring separately rate coefficient and excess loss. It was found that all fibers followed a similar inversion-dependent rate while the maximum excess loss was dependent on the ratios [Al]/[Yb] and [P]/[Yb]. The proposed model allows for rapid evaluation and optimization of fiber parameters and operation conditions to assist Yb-doped laser system design in achieving the desired performance with low photodegradation.

  14. Lanthanide near infrared imaging in living cells with Yb3+ nano metal organic frameworks

    PubMed Central

    Foucault-Collet, Alexandra; Gogick, Kristy A.; White, Kiley A.; Villette, Sandrine; Pallier, Agnès; Collet, Guillaume; Kieda, Claudine; Li, Tao; Geib, Steven J.; Rosi, Nathaniel L.; Petoud, Stéphane

    2013-01-01

    We have created unique near-infrared (NIR)–emitting nanoscale metal-organic frameworks (nano-MOFs) incorporating a high density of Yb3+ lanthanide cations and sensitizers derived from phenylene. We establish here that these nano-MOFs can be incorporated into living cells for NIR imaging. Specifically, we introduce bulk and nano-Yb-phenylenevinylenedicarboxylate-3 (nano-Yb-PVDC-3), a unique MOF based on a PVDC sensitizer-ligand and Yb3+ NIR-emitting lanthanide cations. This material has been structurally characterized, its stability in various media has been assessed, and its luminescent properties have been studied. We demonstrate that it is stable in certain specific biological media, does not photobleach, and has an IC50 of 100 ?g/mL, which is sufficient to allow live cell imaging. Confocal microscopy and inductively coupled plasma measurements reveal that nano-Yb-PVDC-3 can be internalized by cells with a cytoplasmic localization. Despite its relatively low quantum yield, nano-Yb-PVDC-3 emits a sufficient number of photons per unit volume to serve as a NIR-emitting reporter for imaging living HeLa and NIH 3T3 cells. NIR microscopy allows for highly efficient discrimination between the nano-MOF emission signal and the cellular autofluorescence arising from biological material. This work represents a demonstration of the possibility of using NIR lanthanide emission for biological imaging applications in living cells with single-photon excitation. PMID:24108356

  15. Neutron diffraction and /sup 170/Yb Moessbauer investigation of the perovskite ytterbium titanium oxide

    SciTech Connect

    Greedan, J.E.; Soderholm, L.; Friedt, J.M.

    1985-09-02

    A phase with the perovskite structure (Pbnm) and a composition YbTiO/sub 2.95/ has been prepared by a high-temperature carbothermic method. Neutron diffraction shows a colinear ferrimagnetic structure at 7 K with Yb and Ti moments antiparallel along the c-axis of the orthorhombic cell and a Yb moment of 1.8(3) ..mu../sub B/. /sup 170/Yb Moessbauer measurements find a more precise and accurate value of 2.0(1)..mu../sub B/ from the maximum hyperfine field. From the temperature dependence of the hyperfine field a T/sub c/ = 42(1) K is found. The Yb sublattice magnetization below T/sub c/ follows a Brillouin function. At low temperature a distribution of hyperfine fields is observed which is attributed to a random distribution of defects surrounding the Yb sites. The magnetic structure is discussed in relation to possible values of the crystal field parameters, especially B/sub 0//sup 2/. 24 references, 4 figures, 3 tables.

  16. EU Agricultural Policy Analysis1 The EU policy that has had the greatest role in the olive oil sector

    E-print Network

    Zaferatos, Nicholas C.

    EU Agricultural Policy Analysis1 The EU policy that has had the greatest role in the olive oil by the Mediterranean EU Member States to be a competitive producer in olive oil, payment support schemes were competition. This policy regime was meant to equip EU agriculturalists (specifically in this analysis, olive

  17. Undoped and Yb 3+-doped Al 2(WO 4) 3: crystal growth and spectroscopy of new optical materials

    NASA Astrophysics Data System (ADS)

    Gallucci, E.; Ermeneux, S.; Goutaudier, C.; Cohen-Adad, M. Th.; Boulon, G.

    2001-02-01

    Pure and Yb 3+-doped Al 2(WO 4) 3 single crystals of good quality and purity were grown using the Bridgman-Stockbarger method. This is the first time that Al 3+ is substituted with big cations such as lanthanide ones. Undoped, this compound has attractive properties as a non-linear ?(3) material ( ?1=1049 cm -1). When doped with Yb 3+, it also has interesting spectroscopic properties. Yb 3+ absorption, emission spectra and lifetime have been measured. The Yb 3+2F 7/2 level splitting was found to be 856 cm -1 (higher than Yb-YAG: 628), and its 2F 5/2 excited level lifetime is 1.4 ms. However, the Yb absorption cross-sections are weak.

  18. Magnetic properties of nanocrystalline mechanically alloyed Fe?TM?C powder (TM = Ta, Hf, W, Mo, Nb, Zr, and Ti)

    NASA Astrophysics Data System (ADS)

    Kuhrt, C.

    1996-05-01

    Two-phase nanocomposites of ?-Fe and a transition metal (TM) carbide were prepared by mechanical alloying and annealing of elemental Fe80TM10C10 powder blends. The soft magnetic properties remain generally limited (coercivity ? 300 A/m), presumably caused by a 'coarse' grain fraction (> 20 nm) originating from inhomogeneities in the mechanically alloyed precursor.

  19. Concerning the effect of certain admixtures on properties of LaOBr - Tb-luminophor

    SciTech Connect

    Golovkova, S.I.; Gurvich, A.M.; Kra, G.; Bel'shtedt, K.; Birman, T.A.; Katomina, R.V.

    1985-08-01

    It is shown that among lanthanides the most strong effect on the LaOBr - Tb X-ray phosphor luminescence is exerted by Ce (phosphorogen and sensitizer), Sm (luminescence killer), Eu and Yb (phosphorescence killers). The Nd, Dy, Tm, Yb, Fe and Ni impurities in concentration of about 10/sup -5/ g-atom/mol intensify the roentgenoluminescence of LaOBr - Tb. The luminescent-photographic method makes it possible to detect traces of radioactive impurities which accompany lanthanum.

  20. First principle investigations on structural, mechanical, spin polarized electronic and magnetic properties of TmZn and TmCd

    NASA Astrophysics Data System (ADS)

    Chand, Satish; Singh, R. P.; Govindan, A.

    2015-09-01

    Structural, mechanical, spin polarized electronic and magnetic properties of TmZn and TmCd intermetallic compounds have been studied using the full-potential linearize augmented plane-wave plus local orbital method. The structural and mechanical properties have been studied in terms of lattice parameter ( a 0), bulk modulus ( B 0) and its first-order pressure derivative (B0^' }), elastic constants ( C ij ), Young's modulus ( Y), shear modulus ( G) and Poisson's ratio (\\upsilon) in equilibrium state which are found to be consistent with available experimental/theoretical values. Spin polarized electronic properties have been investigated in terms of band structure and density of state histograms for spin up and spin down channel. Electronic behavior of TmZn and TmCd shows that studied materials are metallic ferromagnets with high spin polarization in which Tm-f state electrons have dominant character.

  1. Microwave-assisted solvothermal synthesis and upconversion luminescence of CaF2:Yb3+/Er3+ nanocrystals.

    PubMed

    Zhao, Jing; Zhu, Ying-Jie; Wu, Jin; Chen, Feng

    2015-02-15

    Water-dispersible CaF2 and Yb(3+)/Er(3+) codoped CaF2 (CaF2:Yb(3+)/Er(3+)) nanocrystals with different sizes and different Yb(3+) and Er(3+) dopant concentrations were synthesized using ionic liquid 1-n-butyl-3-methyl imidazolium tetrafluoroborate as a fluorine source by the rapid microwave-assisted solvothermal method. It was found that the morphology, size and crystallinity of CaF2:Yb(3+)/Er(3+) nanocrystals could be adjusted by using adenosine 5'-triphosphate disodium salt (ATP). Yb(3+) and Er(3+) ions were doped into CaF2 nanocrystals to enable upconversion luminescence emission, and the as-prepared CaF2:Yb(3+)/Er(3+) samples exhibited upconversion luminescence upon excitation at 980 nm. Confocal laser scanning microscopy images showed that the CaF2:Yb(3+)/Er(3+) nanocrystals could be used for efficient labeling of human gastric carcinoma cells. Moreover, in vitro cytotoxicity experiments indicated that the as-prepared CaF2:Yb(3+)/Er(3+) nanocrystals had essentially little cytotoxicity. These results indicate that the as-prepared CaF2:Yb(3+)/Er(3+) nanocrystals are promising for the application as a luminescent label material in biological imaging. PMID:25460687

  2. Diode-pumped efficient continuous-wave Yb:Y3Ga5O12 laser at 1035?nm.

    PubMed

    Zhang, Yongdong; Wei, Zhiyi; Wang, Qing; Li, Dehua; Zhang, Zhiguo; Yu, Haohai; Zhang, Huaijin; Wang, Jiyang; Lv, Liang

    2011-02-15

    An efficient diode-pumped Yb:Y3Ga5O12 (Yb:YGG) laser was demonstrated by using a high-quality Yb:YGG crystal grown by the optical floating zone method. Continuous-wave laser power up to 2.65?W had been obtained under an incident pump power of 6.71?W at 970?nm, corresponding to an optical-to-optical efficiency of 39.5% and maximum slope efficiency of 84.5%. A modeling calculation of the Yb:YGG laser was also performed, and the theoretical results were consistent with the experimental results. PMID:21326426

  3. 31. Blow-up equation with eu nonlinearity The equation ut = r2u + eu

    E-print Network

    Trefethen, Nick

    solutions of the steady problem ex- ist, two in 1D and 2D and in nitely many in 3D. In the simple 1D case31. Blow-up equation with eu nonlinearity The equation ut = r2u + eu arises in mathematical models of heat transfer in reacting media: in combustion theory and chemical reactor theory, for example. It also

  4. Perceived Distributive Fairness of EU Transfer Payments, Outcome Favorability, Identity, and EU-Tax Compliance.

    PubMed

    Hartner, Martina; Rechberger, Silvia; Kirchler, Erich; Wenzel, Michael

    2011-01-01

    In a representative UK study (N = 1000) the link between distributive fairness perceptions, outcome favorability, identity, and tax compliance was researched in the context of European transfer payments. Results showed that both forms of tax compliance (i.e., individual and collective EU-tax compliance) were influenced by perceived distributive fairness judgments of EU transfer payments. Fairness itself was related to perceived outcome favorability (i.e., whether their own nation benefits from the EU in financial as well as socio-political terms). Additionally, national identifiers (i.e., people identifying with their own nation, but not with Europe) perceived EU membership as unbeneficial in financial as well as in socio-political terms and thus considered the transfer payments as less fair. Dual identifiers (i.e., people identifying with their own nation and with Europe) perceived the socio-political outcomes from EU membership as more beneficial and thus evaluated the transfer payments as fairer. PMID:21412442

  5. Photoelectron spectra of thulium atoms encapsulated C82 fullerene, Tm2@C82 (III) and Tm2C2@C82 (III)

    NASA Astrophysics Data System (ADS)

    Miyazaki, Takafumi; Tokumoto, Youji; Sumii, Ryohei; Yagi, Hajime; Izumi, Noriko; Shinohara, Hisanori; Hino, Shojun

    2014-03-01

    Ultraviolet photoelectron spectra (UPS) and X-ray photoelectron spectra (XPS) of two thulium atoms and thulium-carbide cluster entrapped fullerenes, Tm2@C82 (III) and Tm2C2@C82 (III), were measured using synchrotron radiation and MgK? X-ray light sources. The UPS spectral onset energy of these endohedral fullerenes is around 0.9 eV, which is smaller than that of 1.2 eV of empty C82. The UPS of Tm2@C82 (III) and Tm2C2@C82 (III) resemble each other. Further, the UPS of Tm2@C82 (III), Y2@C82-C3v and Er2@C82-C3v are almost identical and as well as are Tm2C2@C82 (III), Y2C2@C82-C3v and Er2C2@C82-C3v. The XPS Tm4d5/2 peaks of Tm2@C82 and Tm2C2@C82 appear at higher binding energy region than that of Tm@C82, which suggests the oxidation states of Tm atoms in Tm2@C82 (III) and Tm2C2@C82 are higher than that in Tm@C82.

  6. Coinage metals binding as main group elements: structure and bonding of the carbene complexes [TM(cAAC)2] and [TM(cAAC)2](+) (TM = Cu, Ag, Au).

    PubMed

    Jerabek, Paul; Roesky, Herbert W; Bertrand, Guy; Frenking, Gernot

    2014-12-10

    Quantum chemical calculations using density functional theory have been carried out for the cyclic (alkyl)(amino)carbene (cAAC) complexes of the group 11 atoms [TM(cAAC)2] (TM = Cu, Ag, Au) and their cations [TM(cAAC)2](+). The nature of the metal-ligand bonding was investigated with the charge and energy decomposition analysis EDA-NOCV. The calculations show that the TM-C bonds in the charged adducts [TM(cAAC)2](+) are significantly longer than in the neutral complexes [TM(cAAC)2], but the cations have much higher bond dissociation energies than the neutral molecules. The intrinsic interaction energies ?Eint in [TM(cAAC)2](+) take place between TM(+) in the (1)S electronic ground state and (cAAC)2. In contrast, the metal-ligand interactions in [TM(cAAC)2] involve the TM atoms in the excited (1)P state yielding strong TM p(?) ? (cAAC)2 ? backdonation, which is absent in the cations. The calculations suggest that the cAAC ligands in [TM(cAAC)2] are stronger ? acceptors than ? donors. The trends of the intrinsic interaction energies and the bond dissociation energies of the metal-ligand bonds in [TM(cAAC)2] and [TM(cAAC)2](+) give the order Au > Cu > Ag. Calculations at the nonrelativistic level give weaker TM-C bonds, particularly for the gold complexes. The trend for the bond strength in the neutral and charged adducts without relativistic effects becomes Cu > Ag > Au. The EDA-NOCV calculations suggest that the weaker bonds at the nonrelativistic level are mainly due to stronger Pauli repulsion and weaker orbital interactions. The NBO picture of the C-TM-C bonding situation does not correctly represent the nature of the metal-ligand interactions in [TM(cAAC)2]. PMID:25394669

  7. Investigation of Yb:LuAG crystals with high doping concentration

    NASA Astrophysics Data System (ADS)

    Šulc, Jan; Hubka, Zbyn?k.; Jelenková, Helena; Nejezchleb, Karel; Škoda, Václav

    2013-05-01

    Two Yb:LuAG (Yb:Lu3Al5O12) plates (thickness 1.05 mm, diameter 3 mm, AR/AR @ 0.9 - 1.1 ?m, Yb-doping c = 15% and 20 %) were prepared for laser experiments. For Yb:LuAG pumping, fibre coupled laser diode operating in pulsed regime was used (fibre core diameter 100 ?m, emission wavelength 968 nm, pulse length 2 ms, repetition rate 10 Hz, maximum energy 40 mJ). The longitudinally pumped Yb:LuAG was placed inside the 148mm long resonator formed by a flat pumping mirror (HR @ 1.0 - 1.1 ?m, HT @ 0.97 ?m) and by a curved output coupler (radius of curvature 150 mm). Set of output couplers with reflectivity R = 70 - 97% @ 1.0-1.1 ?m was used and the output power amplitude was measured in dependence on absorbed pumping power amplitude. It was found that for both samples the output coupler reflectivity had only minor influence on laser output parameters expect emission wavelength (1048nm for R < 90% and otherwise 1031 nm). The sample with lower concentration had a lower threshold (˜ 2.5W for c = 15% and ˜ 3.0W for c = 20%) and higher slope efficiency (˜ 61% for c = 15% and ˜ 50% for c = 20 %). The maximum output power amplitude 6.7W was obtained using Yb:LuAG with c = 20% and R = 92% for pumping power amplitude 14W. Obtained results confirmed the good quality of newly grown highly doped Yb:LuAG crystals.

  8. Enhanced high-temperature thermoelectric performance of Yb(14-x)Ca(x)MnSb11.

    PubMed

    Uvarov, Catherine A; Ortega-Alvarez, Francisco; Kauzlarich, Susan M

    2012-07-16

    The high temperature p-type thermoelectric material Yb(14)MnSb(11) has been of increasing research interest since its high temperature thermoelectric properties were first measured in 2006. Subsequent substitutions of Zn, Al, and La into the structure have shown that this material can be further optimized by altering the carrier concentration or by reduction of spin-disorder scattering. Here the properties of the Yb(14-x)Ca(x)MnSb(11) solid solution series where isovalent Ca(2+) is substituted for Yb(2+) will be presented. Crystals of the Yb(14-x)Ca(x)MnSb(11) solid solution series were made by Sn-flux (x = 2, 4, 6, 8) with the following ratio of elements: (14-x)Yb: xCa: 6 Mn: 11Sb: 86Sn, and their structures determined by single crystal X-ray diffraction. The density of the material significantly decreases by over 2 g/cm(3) as more Ca is added (from x = 1 to 8), because of the lighter mass of Ca. The resulting lower density is beneficial from a device manufacturing perspective where there is often a trade-off with the specific power per kilogram. The compounds crystallize in the Ca(14)AlSb(11) structure type. The Ca substitution contributes to systematic lengthening the Mn-Sb bond while shortening the Sb-Sb bond in the 3 atom linear unit with increasing amounts of Ca. Temperature dependent thermoelectric properties, Seebeck, electrical resistivity, and thermal conductivity were measured from room temperature to 1273 K. Substitution of Yb with Ca improves the Seebeck coefficient while decreasing the thermal conductivity, along with decreasing the carrier concentration in this p-type material resulting in an enhanced thermoelectric figure of merit, zT, compared to Yb(14)MnSb(11). PMID:22755507

  9. Quasi four-level Tm:LuAG laser

    NASA Technical Reports Server (NTRS)

    Jani, Mahendra G. (Inventor); Barnes, Norman P. (Inventor); Hutcheson, Ralph L. (Inventor); Rodriguez, Waldo J. (Inventor)

    1997-01-01

    A quasi four-level solid-state laser is provided. A laser crystal is disposed in a laser cavity. The laser crystal has a LuAG-based host material doped to a final concentration between about 2% and about 7% thulium (Tm) ions. For the more heavily doped final concentrations, the LuAG-based host material is a LuAG seed crystal doped with a small concentration of Tm ions. Laser diode arrays are disposed transversely to the laser crystal for energizing the Tm ions.

  10. Stimulated Raman adiabatic passage in Tm{sup 3+}:YAG

    SciTech Connect

    Alexander, A. L.; Lauro, R.; Louchet, A.; Chaneliere, T.; Le Goueet, J. L.

    2008-10-01

    We report on the experimental demonstration of stimulated Raman adiabatic passage in a Tm{sup 3+}:YAG crystal. Tm{sup 3+}:YAG is a promising material for use in quantum information processing applications, but as yet there are few experimental investigations of coherent Raman processes in this material. We investigate the effect of inhomogeneous broadening and Rabi frequency on the transfer efficiency and the width of the two-photon spectrum. Simulations of the complete Tm{sup 3+}:YAG system are presented along with the corresponding experimental results.

  11. Review of Tm and Ho Materials; Spectroscopy and Lasers

    NASA Technical Reports Server (NTRS)

    Walsh, Brian M.

    2008-01-01

    A review of Tm and Ho materials is presented, covering some fundamental aspects on the spectroscopy and laser dynamics in both single and co-doped systems. Following an introduction to 2- m lasers, applications and historical development, the physics of quasi-four level lasers, energy transfer and modeling are discussed in some detail. Recent developments in using Tm lasers to pump Ho lasers are discussed, and seen to offer some advantages over conventional Tm:Ho lasers. This article is not intended as a complete review, but as a primer for introducing concepts and a resource for further study.

  12. Tm:germanate Fiber Laser: Tuning And Q-switching

    NASA Technical Reports Server (NTRS)

    Barnes, Norman P.; Walsh, Brian M.; Reichle, Donald J.; DeYoung, R. J.; Jiang, Shibin

    2007-01-01

    A Tm:germanate fiber laser produced >0.25 mJ/pulse in a 45 ns pulse. It is capable of producing multiple Q-switched pulses from a single p ump pulse. With the addition of a diffraction grating, Tm:germanate f iber lasers produced a wide, but length dependent, tuning range. By s electing the fiber length, the tuning range extends from 1.88 to 2.04 ?m. These traits make Tm:germanate lasers suitable for remote sensin g of water vapor.

  13. Relative Radiometric Calibration of LANDSAT TM Reflective Bands

    NASA Technical Reports Server (NTRS)

    Barker, J. L.

    1985-01-01

    Results and recommendations pertaining to the characterization of the relative radiometric calibration of the protoflight thematic mapper (TM/PF) on the LANDSAT-4 satellite are presented. Some preliminary pre-launch and in-orbit results are also included from the flight model (TM/F) on LANDSAT-5. A common scientific methodology and terminology is outlined for characterizing the radiometry of both TM sensors. The magnitude of the most significant sources of radiometric variability are discussed and methods are recommended for achieving the exceptional potential inherent in the radiometric precision and accuracy of the sensors.

  14. Anomalously slow spin dynamics and short-range correlations in the quantum spin ice systems Yb2Ti2O7 and Yb2Sn2O7

    NASA Astrophysics Data System (ADS)

    Maisuradze, A.; Dalmas de Réotier, P.; Yaouanc, A.; Forget, A.; Baines, C.; King, P. J. C.

    2015-09-01

    We report a positive muon spin relaxation and rotation (? SR ) study of the quantum spin ice materials Yb2Ti2O7 and Yb2Sn2O7 focusing on the low field response. In agreement with earlier reports, data recorded in small longitudinal fields evidence anomalously slow spin dynamics in the microsecond range below the temperature Tc at which the specific heat displays an intense peak, namely Tc=0.24 K and 0.15 K, respectively, for the two systems. We found that slow dynamics extends above Tc up to at least 0.7 K for both compounds. The conventional dynamical Gaussian Kubo-Toyabe model describes the ? SR spectra recorded above Tc. At lower temperatures a published analytical extension of the Gaussian Kubo-Toyabe model provides a good description, consistent with the existence of short-range magnetic correlations. While the physical response of the two systems is qualitatively the same, Yb2Ti2O7 exhibits a much larger local magnetic susceptibility than Yb2Sn2O7 below Tc. Considering previously reported ac susceptibility, neutron scattering, and ? SR results, we suggest the existence of anomalously slow spin dynamics to be a common physical property of pyrochlore magnetic materials. The possibility of molecular spin substructures to be associated to the slow dynamics and therefore the short-range correlations is mentioned. The slow spin dynamics observed under field does not exclude the presence of much faster dynamics detected in extremely low or zero field.

  15. Growth and spectroscopic properties of Yb:Lu 1.5Y 1.5Al 5O 12 mixed crystal

    NASA Astrophysics Data System (ADS)

    Cheng, Shishu; Xu, Xiaodong; Li, Dongzhen; Zhou, Dahua; Wu, Feng; Zhao, Zhiwei; Xu, Jun

    2010-11-01

    Yb 3+-doped (Lu 0.5Y 0.5) 3Al 5O 12 (Yb:LuYAG) single crystal has been grown by the Czochralski method. The segregation coefficient of Yb 3+ was studied by the inductively coupled plasma atomic emission spectrometry (ICP-AES) method. The crystal structure has been determined by X-ray diffraction analysis. The absorption and emission spectra and fluorescence lifetime of Yb:LuYAG crystal were measured at room temperature. The spectroscopic parameters of Yb:LuYAG crystal were compared with those of Yb:YAG and Yb:LuAG crystals with the same doping level. The results indicate that Yb:LuYAG crystals are potential candidates for high-power ultrashort pulse lasers.

  16. Effects of Eu concentration control on crystal growth and scintillation properties for Eu:LiSrAlF6 crystals

    NASA Astrophysics Data System (ADS)

    Suzuki, S.; Yokota, Y.; Yamaji, A.; Kurosawa, S.; Kamada, K.; Yoshikawa, A.

    2014-10-01

    Eu doped LiSrAlF6 (Eu:LiSAF) crystals with various Eu concentrations were grown by a micro-pulling-down (?-PD) method and the effects of Eu concentration control on crystal growth and scintillation properties for Eu:LiSAF crystals were investigated as a neutron scintillator. As-grown Eu0.3%:LiSAF crystal had no visible inclusion while milky parts were observed in the crystals with higher Eu contents. The secondary phases with the chemical composition of EuF2 or EuF3 in the Eu:LiSAF matrix were observed for the crystals with high Eu contents while the secondary phase couldn’t be observed in the powder XRD patterns. In the radioluminescence spectra of Eu:LiSAF crystals under ?-ray irradiation, emission peaks around 375 nm originated from 5d-4f transition of Eu2+ ion were observed. The light yields systematically increased with an increase of actual Eu contents in the crystals and the decay times were 1490-1620 ns.

  17. First-principles study of one-dimensional sandwich wires [(P)?TM]? (TM = Ti, V, Cr, Mn, Fe, Co).

    PubMed

    Ma, Yandong; Dai, Ying; Li, Xinru; Li, Zhujie; Huang, Baibiao

    2013-10-01

    Since the discovery of ferrocene, many one-dimensional metallic sandwich molecular wires have been identified. However, most of the known systems are assembled from organic molecules. Suffering from many drawbacks has, however, hampered their widespread applications. With the goal of breaking this logjam, we provide a blueprint for the designing of a variety of novel sandwich molecular wires ([(P)5TM]?, TM = Ti, V, Cr, Mn, Fe, and Co) assembled from ferrocene-like inorganic molecules (P)5TM, offering evidence of the existence of inorganic molecular wires in this class. We present first-principles calculations to investigate systematically the electronic and magnetic properties of such novel inorganic sandwich molecular wires. Compared with the organic molecular wires, all the inorganic [(P)5TM]? wires are of large magnetic moment. Among them, we find that [(P)5V]?, [(P)5Cr]? and [(P)5Mn]? display ferromagnetic character, while for [(P)5Ti]?, [(P)5Fe]? and [(P)5Co]?, the magnetic coupling is antiferromagnetic. More remarkably, the TM atoms distributed in these wires show regular docking and lead to structures with ordered spin signals, which is a long-term dream of spintronics. We propose that the difference in magnetic coupling for the studied systems is related to the competition between two exchange interactions of TM atoms. Specifically, we propound that the general mechanism for the formation of stable 1D [(P)5TM]? involves the transfer of one electron from the TM atom to the P5 ligand forming [Formula: see text] and TM(+) alternating structure. PMID:24002217

  18. Zeeman relaxation of magnetically trapped Eu atoms

    SciTech Connect

    Suleimanov, Yury V.

    2010-02-15

    We perform rigorous quantum mechanical calculations for collisions between magnetically trapped Eu atoms to elucidate the results of recent experimental studies. We show that the relaxation from the maximally stretched m{sub s}=7/2 level is entirely determined by the magnetic dipole-dipole interaction and analyze the role of the electronic spin-exchange interaction in transitions from the lower-energy Zeeman levels. The relaxation of the m{sub s}=5/2 state is shown to be very sensitive to the spin-exchange parameter that determines the splitting between the lowest electronic states of the Eu dimer. We suggest that cold collision experiments with trapped atoms can be used as a tool for obtaining accurate information on the electronic spin anisotropy in complex molecules such as Eu{sub 2}.

  19. Importance of suppression of Yb(3+) de-excitation to upconversion enhancement in ?-NaYF4: Yb(3+)/Er(3+)@?-NaYF4 sandwiched structure nanocrystals.

    PubMed

    Xiang, Guotao; Zhang, Jiahua; Hao, Zhendong; Zhang, Xia; Pan, Guo-Hui; Luo, Yongshi; Lü, Wei; Zhao, Haifeng

    2015-04-20

    Nanosized Yb(3+) and Er(3+) co-doped ?-NaYF4 cores coated with multiple ?-NaYF4 shell layers were synthesized by a solvothermal process. X-ray diffraction and scanning electron microscopy were used to characterize the crystal structure and morphology of the materials. The visible and near-infrared spectra as well as the decay curves were also measured. A 40-fold intensity increase for the green upconversion and a 34-fold intensity increase for the red upconversion were observed as the cores are coated with three shell layers. The origin of the upconversion enhancement was studied on the basis of photoluminescence spectra and decay times. Our results indicate that the upconversion enhancement in the sandwiched structure mainly originates from the suppression of de-excitation of Yb(3+) ions. We also explored the population of the Er(3+4)F9/2 level. The results reveal that energy transfer from the lower intermediate Er(3+4)I13/2 level is dominant for populating the Er(3+4)F9/2 level when the nanocrystal size is relatively small; however, with increasing nanocrystal size, the contribution of the green emitting Er(3+4)S3/2 level for populating the Er(3+4)F9/2 level, which mainly comes from the cross relaxation energy transfer from Er(3+) ions to Yb(3+) ions followed by energy back transfer within the same Er(3+)-Yb(3+) pair, becomes more and more important. Moreover, this mechanism takes place only in the nearest Er(3+)-Yb(3+) pairs. This population route is in good agreement with that in nanomaterials and bulk materials. PMID:25848860

  20. Thermal lens measurements in Yb-doped YAG, LuAG, Lu2O3, Sc2O3 ceramic lasers

    NASA Astrophysics Data System (ADS)

    Pirri, A.; Toci, G.; Ciofini, M.; Lapucci, A.; Gizzi, L. A.; Labate, L.; Esposito, L.; Hostaša, J.; Vannini, M.

    2014-04-01

    we report the last experimental results obtained measuring the thermal lens effect in Yb(1at.%):Lu2O3, Yb(1at.%):Sc3O3, Yb(10at.%):LuAG and Yb(10at.%):YAG ceramics. The experimental set-up apparatus using a Shack-Hartmann wavefront sensor allows the comparison of the thermal lens obtained under lasing and non lasing conditions, in order to highlight differences in the thermal loading.

  1. YB-1 dependent oncolytic adenovirus efficiently inhibits tumor growth of glioma cancer stem like cells

    PubMed Central

    2013-01-01

    Background The brain cancer stem cell (CSC) model describes a small subset of glioma cells as being responsible for tumor initiation, conferring therapy resistance and tumor recurrence. In brain CSC, the PI3-K/AKT and the RAS/mitogen activated protein kinase (MAPK) pathways are found to be activated. In consequence, the human transcription factor YB-1, knowing to be responsible for the emergence of drug resistance and driving adenoviral replication, is phosphorylated and activated. With this knowledge, YB-1 was established in the past as a biomarker for disease progression and prognosis. This study determines the expression of YB-1 in glioblastoma (GBM) specimen in vivo and in brain CSC lines. In addition, the capacity of Ad-Delo3-RGD, an YB-1 dependent oncolytic adenovirus, to eradicate CSC was evaluated both in vitro and in vivo. Methods YB-1 expression was investigated by immunoblot and immuno-histochemistry. In vitro, viral replication as well as the capacity of Ad-Delo3-RGD to replicate in and, in consequence, to kill CSC was determined by real-time PCR and clonogenic dilution assays. In vivo, Ad-Delo3-RGD-mediated tumor growth inhibition was evaluated in an orthotopic mouse GBM model. Safety and specificity of Ad-Delo3-RGD were investigated in immortalized human astrocytes and by siRNA-mediated downregulation of YB-1. Results YB-1 is highly expressed in brain CSC lines and in GBM specimen. Efficient viral replication in and virus-mediated lysis of CSC was observed in vitro. Experiments addressing safety aspects of Ad-Delo3-RGD showed that (i) virus production in human astrocytes was significantly reduced compared to wild type adenovirus (Ad-WT) and (ii) knockdown of YB-1 significantly reduced virus replication. Mice harboring othotopic GBM developed from a temozolomide (TMZ)-resistant GBM derived CSC line which was intratumorally injected with Ad-Delo3-RGD survived significantly longer than mice receiving PBS-injections or TMZ treatment. Conclusion The results of this study supported YB-1 based virotherapy as an attractive therapeutic strategy for GBM treatment which will be exploited further in multimodal treatment concepts. PMID:24044901

  2. Detailed spectroscopy of quadrupole and octupole states in 168Yb

    NASA Astrophysics Data System (ADS)

    Pascu, S.; Bucurescu, D.; C?ta-Danil, Gh.; Derya, V.; Elvers, M.; Filipescu, D.; Ghiţ?, D. G.; Glodariu, T.; Hennig, A.; Mihai, C.; M?rginean, N.; M?rginean, R.; Negret, A.; Netterdon, L.; Pickstone, S. G.; Sava, T.; Spieker, M.; Stroe, L.; Zamfir, N. V.; Zilges, A.

    2015-03-01

    The low-lying positive- and negative-parity states in 168Yb have been investigated by means of the (? ,2 n ? ) fusion evaporation reaction. Using the coincidence method, the level scheme was corrected and extended up to 3 MeV, for both the positive- and negative-parity states. Using the new branching ratios determined in the present experiment, the K quantum number was proposed for two negative-parity bands by direct comparison with the Alaga rule. Like in some other nuclei, one negative-parity band was established, decaying predominantly to the ? -vibrational band. In a second experiment, the lifetimes of the low-lying excited states up to J?=6+ in the ground-state band were measured by using the in-beam fast-timing method with the Bucharest mixed high-purity germanium (HPGe) and LaBr3:Ce detector array using the triple-? coincidence method. Reduced E 2 transition probabilities were extracted from the measured lifetimes and compared with the corresponding observables in neighboring isotopes, showing a smooth behavior with increasing mass. The positive- and negative-parity states as well as E 1 and E 2 transition probability ratios revealed by these experiments are compared with the interacting boson model in the s d and s p d f boson space, and with the confined beta-soft rotor model, and are found to be in good agreement.

  3. Modeling of Yb3+/Er3+-codoped microring resonators

    NASA Astrophysics Data System (ADS)

    Vallés, Juan A.; G?l?tu?, Ramona

    2015-03-01

    The performance of a highly Yb3+/Er3+-codoped phosphate glass add-drop microring resonator is numerically analyzed. The model assumes resonant behaviour of both pump and signal powers and the dependences of pump intensity build-up inside the microring resonator and of the signal transfer functions to the device through and drop ports are evaluated. Detailed equations for the evolution of the rare-earth ions levels population densities and the propagation of the optical powers inside the microring resonator are included in the model. Moreover, due to the high dopant concentrations considered, the microscopic statistical formalism based on the statistical average of the excitation probability of the Er3+ ion in a microscopic level has been used to describe energy-transfer inter-atomic mechanisms. Realistic parameters and working conditions are used for the calculations. Requirements to achieve amplification and laser oscillation within these devices are obtainable as a function of rare earth ions concentration and coupling losses.

  4. mRNA and DNA selection via protein multimerization: YB-1 as a case study

    PubMed Central

    Kretov, Dmitry A.; Curmi, Patrick A.; Hamon, Loic; Abrakhi, Sanae; Desforges, Bénédicte; Ovchinnikov, Lev P.; Pastré, David

    2015-01-01

    Translation is tightly regulated in cells for keeping adequate protein levels, this task being notably accomplished by dedicated mRNA-binding proteins recognizing a specific set of mRNAs to repress or facilitate their translation. To select specific mRNAs, mRNA-binding proteins can strongly bind to specific mRNA sequences/structures. However, many mRNA-binding proteins rather display a weak specificity to short and redundant sequences. Here we examined an alternative mechanism by which mRNA-binding proteins could inhibit the translation of specific mRNAs, using YB-1, a major translation regulator, as a case study. Based on a cooperative binding, YB-1 forms stable homo-multimers on some mRNAs while avoiding other mRNAs. Via such inhomogeneous distribution, YB-1 can selectively inhibit translation of mRNAs on which it has formed stable multimers. This novel mechanistic view on mRNA selection may be shared by other proteins considering the elevated occurrence of multimerization among mRNA-binding proteins. Interestingly, we also demonstrate how, by using the same mechanism, YB-1 can form multimers on specific DNA structures, which could provide novel insights into YB-1 nuclear functions in DNA repair and multi-drug resistance. PMID:26271991

  5. YB-1 regulates stress granule formation and tumor progression by translationally activating G3BP1

    PubMed Central

    Somasekharan, Syam Prakash; El-Naggar, Amal; Leprivier, Gabriel; Cheng, Hongwei; Hajee, Shamil; Grunewald, Thomas G.P.; Zhang, Fan; Ng, Tony; Delattre, Olivier; Evdokimova, Valentina; Wang, Yuzhuo; Gleave, Martin

    2015-01-01

    Under cell stress, global protein synthesis is inhibited to preserve energy. One mechanism is to sequester and silence mRNAs in ribonucleoprotein complexes known as stress granules (SGs), which contain translationally silent mRNAs, preinitiation factors, and RNA-binding proteins. Y-box binding protein 1 (YB-1) localizes to SGs, but its role in SG biology is unknown. We now report that YB-1 directly binds to and translationally activates the 5? untranslated region (UTR) of G3BP1 mRNAs, thereby controlling the availability of the G3BP1 SG nucleator for SG assembly. YB-1 inactivation in human sarcoma cells dramatically reduces G3BP1 and SG formation in vitro. YB-1 and G3BP1 expression are highly correlated in human sarcomas, and elevated G3BP1 expression correlates with poor survival. Finally, G3BP1 down-regulation in sarcoma xenografts prevents in vivo SG formation and tumor invasion, and completely blocks lung metastasis in mouse models. Together, these findings demonstrate a critical role for YB-1 in SG formation through translational activation of G3BP1, and highlight novel functions for SGs in tumor progression. PMID:25800057

  6. Obligate anaerobic Salmonella typhimurium strain YB1 treatment on xenograft tumor in immunocompetent mouse model

    PubMed Central

    YU, BIN; SHI, LEI; ZHANG, BAO-ZHONG; ZHANG, KE; PENG, XIAO; NIU, HAN-BEN; QU, JUN-LE

    2015-01-01

    The present authors have previously reported a novel approach to genetically engineer Salmonella typhimurium for the medically important therapeutic strategy of using bacterial agents to target malignant tumors in a breast cancer tumor-bearing nude mouse model. However, studying an immunocompromised mouse model for cancer therapy is insufficient, as certain crucial information about the influence of the immune system may be missing. In the present study, inoculation of the Salmonella strain, YB1, into a colon cancer tumor-bearing immunocompetent mouse model was investigated. The present study determined the tumor targeting efficiency, antitumor potential, the effects of multiple treatments and the systemic toxicity. Intravenous inoculation of YB1 in BALB/c mice exhibited high antitumor effects and also greatly increased the tumor targeting ability and safety compared with the previously-reported nude mouse model. In addition, repeated administration of YB1 further enhanced this effect. Furthermore, no marked toxicity was observed with YB1 treatment, while the VNP20009 and SL7207 strains demonstrated certain adverse effects. The findings of the present study indicate that the YB1 strain is effective and safe in targeting a colon cancer tumor in an immunocompetent mouse model.

  7. Gain dynamics in Er(3+):Yb(+) co-doped fiber amplifiers.

    PubMed

    Steinke, M; Neumann, J; Kracht, D; Wessels, P

    2015-06-01

    Understanding the gain dynamics of fiber amplifiers is essential for the implementation and active stabilization of low noise amplifiers or for coherent beam combining schemes. The gain dynamics of purely Er3+ or Yb3+ doped fiber amplifiers are well studied, whereas no analysis for co-doped systems, especially for Er3+:Yb3+ co-doped fiber amplifiers has been performed, so far. Here, we analyze for the first time the gain dynamics of Er3+:Yb3+ co-doped fiber amplifiers theoretically and experimentally. It is shown that due to the energy transfer between the Yb3+ and Er3+ ions a full analytical solution is not possible. Thus, we used numerical simulations to gain further insights. Comparison of experimental and numerical results shows good qualitative agreement. In addition, we were able to determine the Yb3+-Er3+ transfer function of the energy transfer experimentally. PMID:26072851

  8. Improvements in the production of Yb:YAG transparent ceramic materials: Spray drying optimisation

    NASA Astrophysics Data System (ADS)

    Serantoni, Marina; Piancastelli, Andreana; Costa, Anna Luisa; Esposito, Laura

    2012-04-01

    Spray drying parameters have been optimized for the preparation of granulated stoichiometric mixture of oxides. These oxides are used in the production of Yb:YAG laser grade ceramic materials by reactive sintering. The selected compositions were Yb0.294Y2.706Al5O12 and Yb0.03Y2.97Al5O12, i.e. YAG doped with 9.8 and 1.0 at% of Yb with respect to the overall Y + Yb amount. The influence of solid content, drying medium flux, temperature and aspiration rate of the spray drying process on the transparency of the sintered materials has been evaluated. Sintering was conducted under high vacuum and clean atmosphere in the temperature range of 1650-1735 °C and with a soaking time of 16 h. SEM analysis of the microstructure of granulated powders and sintered materials, as well as the transmittance measurement, were used as tools to guide the selection of the best spray drying parameters.

  9. 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.

  10. Fine and hyperfine interactions in cold YbF-He collisions in electromagnetic fields

    SciTech Connect

    Tscherbul, T. V.; Krems, R. V.; Klos, J.; Rajchel, L.

    2007-03-15

    We present a rigorous study of cold and ultracold collisions of YbF({sup 2}{sigma}) molecules with He atoms in external electric and magnetic fields based on an accurate calculation of the interaction potential surface and quantum theory of atom-molecule scattering. We analyze the mechanisms of collisional depolarization of the electron and nuclear spins of YbF and demonstrate that the rate constants for elastic and inelastic collisions of YbF with He are sensitive to the magnitudes of the applied fields. Collisions of heavy polar molecules like YbF may thus be easily manipulated with external electromagnetic fields. We show that collisional spin relaxation of YbF molecules in rotationally excited states is suppressed by electric fields much more significantly than the spin relaxation in the ground rotational state. We explain this by the influence of electric-field-induced Feshbach resonances, which occur at much lower collision energies when the molecule is rotationally excited. Our results suggest that heavy polar molecules may be amenable to magnetic trapping in a buffer gas of He, which could greatly enhance the sensitivity of spectroscopic experiments to measure the electric dipole moment of the electron.

  11. Home/EU Overseas Home/EU Overseas 3,996 12,600 1,998 6,300

    E-print Network

    Chittka, Lars

    Home/EU Overseas Home/EU Overseas £3,996 £12,600 £1,998 £6,300 £3,996 £14,500 £1,998 £7,250 £3,996 £36,950 £1,998 £18,475 £3,996 £41,950 £1,998 £20,975 Home/EU Overseas Home/EU Overseas £3,996 £12,935 Home/EU Overseas Home/EU Overseas £3,996 £12,330 £1,998 £6,165 £3,996 £13,680 £1,998 £6,840 £3,996 £15

  12. Optimized Strings for the Java HotSpotTM

    E-print Network

    Mössenböck, Hanspeter

    Mössenböck Institute for System Software Christian Doppler Laboratory for Automated Software EngineeringOptimized Strings for the Java HotSpotTM Virtual Machine Christian Häubl Christian Wimmer Hanspeter

  13. High-spin states in odd-odd 168Tm

    SciTech Connect

    Cardona, M. A.; Hojman, D.; Davidson, J.; Davidson, M.; Kreiner, A. J.; Bazzacco, D.; Lenzi, S. M.; Rossi Alvarez, C.; Blasi, N.; Debray, M. E.; Levinton, G.; Marti, G.; De Poli, M.; Napoli, D. R.; Lo Bianco, G.

    2007-02-12

    High-spin states in 168Tm were investigated by means of {gamma}-ray spectroscopy techniques using the GASP multidetector array. Rotational bands have been established and identified in terms of their configurations.

  14. Spiral Bragg grating waveguides for TM mode silicon photonics.

    PubMed

    Chen, Zhitian; Flueckiger, Jonas; Wang, Xu; Zhang, Fan; Yun, Han; Lu, Zeqin; Caverley, Michael; Wang, Yun; Jaeger, Nicolas A F; Chrostowski, Lukas

    2015-09-21

    We demonstrate spiral Bragg grating waveguides (BGWs) on the silicon-on-insulator (SOI) platform for the fundamental transverse magnetic (TM) mode. We also compare TM spiral waveguides to equivalent transverse electric (TE) spiral waveguides and show that the TM spiral waveguides have lower propagation losses. Our spiral waveguides are space-efficient, requiring only areas of 131×131 µm2 to accommodate 4 mm long BGWs, and, thus, are less susceptible to fabrication non-uniformities. Due to the lengths and reduced susceptibility to fabrication non-uniformities, we were able to obtain narrow bandwidth, large extinction ratio (ER) devices, as narrow as 0.09 nm and as large as 52 dB, respectively. Finally, we demonstrate a 4 mm long TM chirped spiral Bragg grating waveguide with a negative, average, group delay slope of -11 ps/nm. PMID:26406726

  15. ORNL/TM-2013/221 Technical and Economic Feasibility

    E-print Network

    Post, Wilfred M.

    ORNL/TM-2013/221 Technical and Economic Feasibility Assessment of Small Hydropower Development Sciences Division TECHNICAL AND ECONOMIC FEASIBILITY ASSESSMENT OF SMALL HYDROPOWER DEVELOPMENT..................................................................................................................1 1.2 EXISTING HYDROPOWER FACILITIES IN THE DESCHUTES AND CROOKED BASINS

  16. ORNL/TM-2007/094 Integrated Analysis of Market

    E-print Network

    ORNL/TM-2007/094 Integrated Analysis of Market Transformation Scenarios with HyTrans June 2007 Science and Technology Division INTEGRATED ANALYSIS OF MARKET TRANSFORMATION SCENARIOS WITH HYTRANS David ........................................................................................ 7 4. FUEL CELL VEHICLE COSTS

  17. The crystal structure of Yb{sub 2}(SO{sub 4}){sub 3}.3H{sub 2}O and its decomposition product, {beta}-Yb{sub 2}(SO{sub 4}){sub 3}

    SciTech Connect

    Mills, Stuart J.; Petricek, Vaclav; Kampf, Anthony R.; Herbst-Imer, Regine; Raudsepp, Mati

    2011-09-15

    Yb{sub 2}(SO{sub 4}){sub 3}.3H{sub 2}O, synthesised by hydrothermal methods at 220(2) deg. C, has been investigated by single crystal X-ray diffraction. Yb{sub 2}(SO{sub 4}){sub 3}.3H{sub 2}O crystallises in space group Cmc2{sub 1} and is isostructural with Lu{sub 2}(SO{sub 4}){sub 3}.3H{sub 2}O. The crystal structure has been refined to R{sub 1}=0.0145 for 3412 reflections [F{sub o}>3{sigma}(F)], and 0.0150 for all 3472 reflections. The structure of Yb{sub 2}(SO{sub 4}){sub 3}.3H{sub 2}O is a complex framework of YbO{sub 6} octahedra, YbO{sub 8} and YbO{sub 5}(H{sub 2}O){sub 3} polyhedra and SO{sub 4} tetrahedra. Thermal data shows that Yb{sub 2}(SO{sub 4}){sub 3}.3H{sub 2}O decomposes between 120 and 190 deg. C to form {beta}-Yb{sub 2}(SO{sub 4}){sub 3}. The structure of a twinned crystal of {beta}-Yb{sub 2}(SO{sub 4}){sub 3} was solved and refined using an amplimode refinement in R3c with an R{sub 1}=0.0755 for 8944 reflections [F{sub o}>3{sigma}(F)], and 0.1483 for all 16,361 reflections. {beta}-Yb{sub 2}(SO{sub 4}){sub 3} has a unique structural topology based on a 3D network of pinwheels. - Graphical abstract: Octahedral-tetrahedral linkages found in Y{sub 2}(SO{sub 4}){sub 3} [and Er{sub 2}(SO{sub 4}){sub 3}] and ss-Yb{sub 2}(SO{sub 4}){sub 3}. Highlights: > The crystal structure and decomposition reactions of Yb{sub 2}(SO{sub 4}){sub 3}.3H{sub 2}O. > The crystal structure of a twinned crystal of {beta}-Yb{sub 2}(SO{sub 4}){sub 3}. > Comparison of the structures of {beta}-Yb{sub 2}(SO{sub 4}){sub 3} and Y{sub 2}(SO{sub 4}){sub 3}.

  18. Thermodynamic and transport properties of single crystalline RCo2Ge2 (R=Y, La–Nd, Sm–Tm)

    SciTech Connect

    Kong, Tai; Cunningham, Charles E.; Taufour, Valentin; Budko, Sergey L.; Buffon, Malinda L.C.; Lin, Xiao; Emmons, Heather; Canfield, Paul C.

    2014-05-01

    Single crystals of RCo2Ge2 (R=Y, La–Nd, Sm–Tm) were grown using a self-flux method and were characterized by room-temperature powder X-ray diffraction; anisotropic, temperature and field dependent magnetization; temperature and field dependent, in-plane resistivity; and specific heat measurements. In this series, the majority of the moment-bearing members order antiferromagnetically; YCo2Ge2 and LaCo2Ge2 are non-moment-bearing. Ce is trivalent in CeCo2Ge2 at high temperatures, and exhibits an enhanced electronic specific heat coefficient due to the Kondo effect at low temperatures. In addition, CeCo2Ge2 shows two low-temperature anomalies in temperature-dependent magnetization and specific heat measurements. Three members (R=Tb–Ho) have multiple phase transitions above 1.8 K. Eu appears to be divalent with total angular momentum L =0. Both EuCo2Ge2 and GdCo2Ge2 manifest essentially isotropic paramagnetic properties consistent with J =S =7/2. Clear magnetic anisotropy for rare-earth members with finite L was observed, with ErCo2Ge2 and TmCo2Ge2 manifesting planar anisotropy and the rest members manifesting axial anisotropy. The experimentally estimated crystal electric field (CEF) parameters B 20 were calculated from the anisotropic paramagnetic ? ab and ? c values and follow a trend that agrees well with theoretical predictions. The ordering temperatures, TNTN, as well as the polycrystalline averaged paramagnetic Curie–Weiss temperature, ?avg, for the heavy rare-earth members deviate from the de Gennes scaling, as the magnitude of both is the highest for Tb, which is sometimes seen for extremely axial systems. Except for SmCo2Ge2, metamagnetic transitions were observed at 1.8 K for all members that ordered antiferromagnetically.

  19. Lunar Sample Compendium C Meyer 2012

    E-print Network

    Rathbun, Julie A.

    / chondrite La Pr Sm Gd Dy Er Yb Ce Nd Eu Tb Ho Tm Lu 64535 glass anorthosite melt Figure 5: Ar/Ar plateau anorthosite with impact melt. In some cases they also have a thick black glass coating. See also et al. (1992) provide analyses of the anorthosite while McKinley et al. (1984) give an analysis

  20. Lightweight high performance ceramic material

    DOEpatents

    Nunn, Stephen D [Knoxville, TN

    2008-09-02

    A sintered ceramic composition includes at least 50 wt. % boron carbide and at least 0.01 wt. % of at least one element selected from the group consisting of Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy Ho, Er, Tm, Yb, and Lu, the sintered ceramic composition being characterized by a density of at least 90% of theoretical density.

  1. Quiet Spike (TM) Build-Up Ground Vibration Testing Approach

    NASA Technical Reports Server (NTRS)

    Spivey, Natalie D.; Herrera, Claudia; Truax, Roger; Pak, Chan-gi; Freund, Donald

    2007-01-01

    Flight tests of Gulfstream Aerospace Corporation s Quiet Spike(TM) hardware were recently completed on the NASA Dryden Flight Research Center F-15B airplane. NASA Dryden uses a modified F-15B airplane as a testbed aircraft to cost-effectively fly flight research experiments that are typically mounted underneath the F-15B airplane, along the fuselage centerline. For the Quiet Spike(TM) experiment, however, instead of a centerline mounting, a relatively long forward-pointing boom was attached to the radar bulkhead of the F-15B airplane. The Quiet Spike(TM) experiment is a stepping-stone to airframe structural morphing technologies designed to mitigate the sonic-boom strength of business jets over land. The Quiet Spike(TM) boom is a concept in which an aircraft's noseboom would be extended prior to supersonic acceleration. This morphing effectively lengthens the aircraft, thus reducing the peak sonic-boom amplitude, but is also expected to partition the otherwise strong bow shock into a series of reduced-strength, noncoalescing shocklets. Prior to flying the Quiet Spike(TM) experiment on the F-15B airplane several ground vibration tests were required to understand the Quiet Spike(TM) modal characteristics and coupling effects with the F-15B airplane. However, due to the flight hardware availability and compressed schedule requirements, a "traditional" ground vibration test of the mated F-15B Quiet Spike(TM) ready-for-flight configuration did not leave sufficient time available for the finite element model update and flutter analyses before flight testing. Therefore, a "nontraditional" ground vibration testing approach was taken. This paper provides an overview of each phase of the "nontraditional" ground vibration testing completed for the Quiet Spike(TM) project which includes the test setup details, instrumentation layout, and modal results obtained in support of the structural dynamic modeling and flutter analyses.

  2. Spectroscopic and lasing properties of Ho:Tm:LuAG

    NASA Technical Reports Server (NTRS)

    Barnes, Norman P.; Filer, Elizabeth D.; Naranjo, Felipe L.; Rodriguez, Waldo J.; Kokta, Milan R.

    1993-01-01

    Ho:Tm:LuAG has been grown, examined spectroscopically, and lased at 2.1 microns. Ho:Tm:LuAG was selected for this experimental investigation when quantum-mechanical modeling predicted that it would be a good laser material for Ho laser operation on one of the 5I7 to 5I8 transitions. Lasing was achieved at 2.100 microns, one of the three wavelengths predicted to be most probable for laser action.

  3. Flashlamp-pumped Ho:Tm:Cr:LuAG laser

    NASA Technical Reports Server (NTRS)

    Jani, Mahendra G. (Inventor); Barnes, Norman P. (Inventor); Murray, Keith E. (Inventor); Kokta, Milan R. (Inventor)

    1997-01-01

    A room temperature solid-state laser is provided. A laser crystal is disposed in a laser cavity. The laser crystal has a LuAG host material doped with a concentration of about 0.35% Ho ions, about 5.57% Tm ions and at least about 1.01% Cr ions. A broadband energizing source such as a flashlamp is disposed transversely to the laser crystal to energize the Ho ions, Tm ions and Cr ions.

  4. Cryogenic disk Yb : YAG laser with 120-mJ energy at 500-Hz pulse repetition rate

    SciTech Connect

    Perevezentsev, E A; Mukhin, I B; Kuznetsov, I I; Palashov, O V; Khazanov, Efim A

    2013-03-31

    A repetitively pulsed laser system based on cryogenically cooled Yb : YAG disks is developed. The creation of Yb : YAG/YAG composites and the use of an active liquid nitrogen cooling system made it possible to significantly decrease the effect of amplified spontaneous emission. The average output power of the system is 60 W. (extreme light fields and their applications)

  5. Down-shifting spectroscopic properties of Yb3+ doped BaGd2ZnO5 phosphors

    NASA Astrophysics Data System (ADS)

    Yang, Yanmin; Liu, Linlin; Li, Mingming; Mi, Chao; Liu, Yanzhou; Guo, Qinglin; Zhang, Yi; Fu, Xihong; Cai, Shuzhen; Mai, Yaohua

    2015-04-01

    Yb3+ doped BaGd2ZnO5 phosphor was synthesized via sol-gel method. X-ray diffraction, scanning electron microscopy and photoluminescence spectra were employed to characterize the as-obtained products. Upon 274 nm excitation, a single strong narrow-band emission from 2F5/2 ? 2F7/2 of Yb3+ ion around 977 nm was obtained in Yb3+ doped BaGd2ZnO5 phosphor, which was well suited to efficient absorption in a silicon solar cell. After adding Ce3+ into Yb3+-doped BaGd2ZnO5, the excitation spectra of samples monitored at 977 nm indicated that the excitation peaks were in the broad range from 230 nm to 400 nm, which covered ultraviolet and blue light with poor solar cell spectral response. Furthermore, Er3+ was introduced into Yb3+-doped BaGd2ZnO5 phosphor to prove the high energy transfer efficiency from Gd3+ ion to Yb3+ ion by comparing it with that of Er3+ ion to Yb3+ ion. With access to broad-band absorption, narrow-band emission as well as high energy transfer efficiency, Ce3+, Yb3+-codoped BaGd2ZnO5 may have potential applications in modifying the solar spectrum to enhance the efficiency of silicon solar cells.

  6. ASTROCULTURE (TM) root metabolism and cytochemical analysis

    NASA Technical Reports Server (NTRS)

    Porterfield, D. M.; Barta, D. J.; Ming, D. W.; Morrow, R. C.; Musgrave, M. E.

    2000-01-01

    Physiology of the root system is dependent upon oxygen availability and tissue respiration. During hypoxia nutrient and water acquisition may be inhibited, thus affecting the overall biochemical and physiological status of the plant. For the Astroculture (TM) plant growth hardware, the availability of oxygen in the root zone was measured by examining the changes in alcohol dehydrogenase (ADH) activity within the root tissue. ADH activity is a sensitive biochemical indicator of hypoxic conditions in plants and was measured in both spaceflight and control roots. In addition to the biochemical enzyme assays, localization of ADH in the root tissue was examined cytochemically. The results of these analyses showed that ADH activity increased significantly as a result of spaceflight exposure. Enzyme activity increased 248% to 304% in dwarf wheat when compared with the ground controls and Brassica showed increases between 334% and 579% when compared with day zero controls. Cytochemical staining revealed no differences in ADH tissue localization in any of the dwarf wheat treatments. These results show the importance of considering root system oxygenation in designing and building nutrient delivery hardware for spaceflight plant cultivation and confirm previous reports of an ADH response associated with spaceflight exposure.

  7. Non-Kondo-like electronic structure in the correlated rare-earth hexaboride YbB(6).

    PubMed

    Neupane, Madhab; Xu, Su-Yang; Alidoust, Nasser; Bian, Guang; Kim, D J; Liu, Chang; Belopolski, I; Chang, T-R; Jeng, H-T; Durakiewicz, T; Lin, H; Bansil, A; Fisk, Z; Hasan, M Z

    2015-01-01

    We present angle-resolved photoemission studies on the rare-earth-hexaboride YbB(6), which has recently been predicted to be a topological Kondo insulator. Our data do not agree with the prediction and instead show that YbB(6) exhibits a novel topological insulator state in the absence of a Kondo mechanism. We find that the Fermi level electronic structure of YbB(6) has three 2D Dirac cone like surface states enclosing the Kramers's points, while the f orbital that would be relevant for the Kondo mechanism is ?1??eV below the Fermi level. Our first-principles calculation shows that the topological state that we observe in YbB(6) is due to an inversion between Yb d and B p bands. These experimental and theoretical results provide a new approach for realizing novel correlated topological insulator states in rare-earth materials. PMID:25615485

  8. Cyclic MAM synthesis of SPION/BaMoO4:Er3+,Yb3+ composite and its optical properties

    NASA Astrophysics Data System (ADS)

    Lim, C. S.; Atuchin, V. V.

    2013-05-01

    Er3+/Yb3+ co-doped BaMoO4 (BaMoO4:Er3+/Yb3+) composites with superparamagnetic iron oxide nanoparticles (SPIONs) incorporated were successfully synthesized by a cyclic microwave-assisted metathetic (MAM) method followed by heat-treatment. The microstructure exhibited well-defined and homogeneous morphology with the BaMoO4:Er3+/Yb3+ particle size of 1-2 ?m and Fe3O4 particle size of 0.1-0.5 ?m. The Fe3O4 particles were self-preferentially crystallized and immobilized on the surface of BaMoO4:Er3+/Yb3+ particles. The synthesized SPION/BaMoO4:Er3+,Yb3+ composites were characterized by X-ray diffraction, scanning electron microscopy and energy-dispersive X-ray spectroscopy. Optical properties were examined using photoluminescence emission measurements and Raman spectroscopy.

  9. Spectroscopy and efficient laser emission of Yb 3+: LuAG single crystal grown by ?-PD

    NASA Astrophysics Data System (ADS)

    Veronesi, S.; Zhang, Y. Z.; Tonelli, M.; Agnesi, A.; Greborio, A.; Pirzio, F.; Reali, G.

    2012-02-01

    A LuAG shaped rod crystal, doped with Yb 3+, has been grown by ?-PD technique. The crystal diameter was about 3 mm and the length around 130 mm. A complete spectroscopic investigation in the temperature range 10-300 K is reported and data has been utilized to model the laser behavior. In the laser experiment the Yb:LuAG sample was placed in an X cavity and pumped longitudinally obtaining an efficient CW laser emission. The Yb:LuAG laser yielded a maximum output power of 23 mW with a slope efficiency of 32% and a threshold around 35 mW, at lasing wavelength of 1030 nm. No significant depolarization effects were observed, indicating a crystal growth with negligible stress. The output beam profile was investigated, yielding M 2 ? 1.0 in both directions, further confirming the good optical quality of the sample.

  10. 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. PMID:23037349

  11. Ohmic contact on n-type Ge using Yb-germanide

    SciTech Connect

    Zheng Zhiwei; Liu Ming; Ku, Teng-Chieh; Chin, Albert

    2012-11-26

    Poor ohmic contact by Fermi-level pinning to valence band (E{sub V}) edge is one of the major challenges for germanium (Ge) n-type metal-oxide-semiconductor field-effect transistor (nMOSFET). Using low work-function rare-earth ytterbium (Yb), good ohmic contact on n-type Ge with alleviated Fermi-level pinning was demonstrated. Such ohmic behavior depends strongly on the germanide formation condition, where much degraded ohmic contact at 600 Degree-Sign C rapid thermal annealing is due to the lower Yb/Ge composition found by energy-dispersive x-ray spectroscopy. The ohmic behavior of Yb-germanide/n-type-Ge has high potential for future high-performance Ge nMOSFET application.

  12. 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.

  13. Antiferromagnetic order in the pyrochlores R2Ge2O7 (R =Er ,Yb )

    NASA Astrophysics Data System (ADS)

    Dun, Z. L.; Li, X.; Freitas, R. S.; Arrighi, E.; Dela Cruz, C. R.; Lee, M.; Choi, E. S.; Cao, H. B.; Silverstein, H. J.; Wiebe, C. R.; Cheng, J. G.; Zhou, H. D.

    2015-10-01

    Elastic neutron scattering, ac susceptibility, and specific heat experiments on the pyrochlores Er2Ge2O7 and Yb2Ge2O7 show that both systems are antiferromagnetically ordered in the ?5 manifold. The ground state is a ?3 phase for the Er sample and a ?2 or ?3 phase for the Yb sample, which suggests "Order by Disorder" physics. Furthermore, we unify the various magnetic ground states of all known R2X2O7 (R =Er , Yb; X =Sn , Ti, Ge) compounds through the enlarged X Y -type exchange interaction J± under chemical pressure. The mechanism for this evolution is discussed in terms of the phase diagram proposed in the theoretical study by Wong et al. [Phys. Rev. B 88, 144402 (2013), 10.1103/PhysRevB.88.144402].

  14. Gadolinium ytterbium trifluoride, Gd0.81Yb0.19F3.

    PubMed

    Vasyliev, Valentyn; Villora, Encarnacion G; Nakamura, Masaru; Sato, Akira; Shimamura, Kiyoshi

    2011-02-01

    A new gadolinium ytterbium trifluoride has been grown for the first time by the Czochralski technique. Although GdF(3) and YbF(3) both present a high-temperature phase transition, the mixed compound Gd(0.81)Yb(0.19)F(3) maintains its crystallographic structure upon cooling to room temperature. Taking into account that both Gd(3+) and Yb(3+) ions are distributed randomly on a single site (Wyckoff position 4c), this is attributed to a mean cationic radius coincident with that of the Tb(3+) ion, so that the stability of the crystal structure resembles that of TbF(3). The grown crystal melts noncongruently at ?1413?K, it is transparent and colourless, and it has a high density. PMID:21285491

  15. Waveguiding properties in Yb:YAG crystals implanted with protons and carbon ions.

    PubMed

    Vázquez, G V; Ramírez, D; Márquez, H; Flores-Romero, E; Rickards, J; Trejo-Luna, R

    2012-08-01

    We report the fabrication and analysis of optical waveguides in Yb:YAG crystals using either proton or carbon ion implantation. Planar waveguides were obtained by implanting the whole surface of the crystals. Channel waveguides were defined using an electroformed mask with apertures of 10, 15, and 20 micrometers in width. The waveguiding properties of the structures were analyzed, showing good light confinement based on the transversal mode distribution and optical transmission measurements. The spectroscopic properties of the Yb ions in the YAG host are preserved after the implantation process, which demonstrates the potential of this technique for tailoring microcomponents for integrated optics applications. In particular, the Yb:YAG waveguides have the potential to operate as miniature lasers. PMID:22859050

  16. Optical properties of phosphate glasses co-doped with Yb3+ and silver nanoparticles

    NASA Astrophysics Data System (ADS)

    A. Vallejo H., M.; A. Martinez G., M.; V. Kiryanov, A.; L. Lucio M., J.

    2014-12-01

    We report the fabrication and spectroscopic characterization of Yb3+-doped phosphate glass, also containing silver nitrate. Scanning electron microscopy (SEM) provides the evidence of the formation of silver nano-particles (SNPs), which are formed as a consequence of melting and thermal decomposition of AgNO3. Absorption spectra of the samples in the visible-to-near-infrared spectral range reveal the presence of bands centered at 410 nm associated with the SNP-plasmon resonance, and at 976 nm due to the Yb3+. Under 916-nm laser-diode pumping, the effect of the SNP reflects that: i) the fluorescence in the 950-nm-1150-nm spectral range is strongly enhanced(~ 30 times), while the fluorescence decay time associated with the 2F5/2 ? 2F7/2 transition of Yb3+ increases 25%, and ii) the basic lasing properties (saturation pumping intensity, the emission and absorption cross sections) are substantially improved.

  17. A highly efficient Yb-doped silica laser fiber prepared by gas phase doping technology

    NASA Astrophysics Data System (ADS)

    Unger, Sonja; Lindner, Florian; Aichele, Claudia; Leich, Martin; Schwuchow, Anka; Kobelke, Jens; Dellith, Jan; Schuster, Kay; Bartelt, Hartmut

    2014-03-01

    In this paper we report on an alternative technique for the preparation of ytterbium (Yb)-doped silica fibers and their characteristics compared to the conventional modified chemical vapor deposition (MCVD) process in combination with solution doping and powder sinter technology (REPUSIL). In the case of the technique applied here, the active core diameter in the preform can be significantly increased via the deposition of Yb and the most important codopant, aluminum (Al), in the gas phase through the high-temperature evaporation of the Yb chelate compound and Al chloride in the MCVD process. The prepared preform shows a homogenous distribution of the refractive index and dopant concentration. The background loss of the drawn fiber was measured to be 25 dB km-1 at 1200 nm. Efficient lasing up to 200 W, showing a slope efficiency of about 80%, was demonstrated, which is comparable to fibers made via MCVD/solution doping and the REPUSIL technique.

  18. Ultraviolet-blue to near-infrared downconversion of Nd(3+)-Yb(3+) couple.

    PubMed

    Chen, Daqin; Yu, Yunlong; Lin, Hang; Huang, Ping; Shan, Zhifa; Wang, Yuansheng

    2010-01-15

    To reduce energy losses by thermalization of charge carriers in a silicon solar cell, quantum-cutting luminescent materials are desired for the efficient downconversion of UV-visible radiation into near-IR radiation. In this Letter, quantum cutting involving emission of two near-IR photons for each UV-blue photon absorbed is demonstrated in Nd(3+)/Yb(3+):beta-YF(3) nanocrystals embedded in transparent bulk-glass ceramics. Upon excitation of an Nd(3+) ion with a UV-blue photon, Yb(3+) ions emit two near-IR photons through an efficient two-step energy transfer from Nd(3+) to Yb(3+) with Nd(3+):(4)F(3/2) acting as the intermediate state. PMID:20081974

  19. Low temperature magnetic properties of magnesium substituted YbMnO{sub 3}

    SciTech Connect

    Sattibabu, Bhumireddi Bhatnagar, Anil K. Mohan, Dasari Das, Dibakar Sundararaman, Mahadevan; Siruguri, Vasudeva; Rayaprol, Sudhindra

    2014-04-24

    Structural and magnetic properties of polycrystalline Yb{sub 1?x}Mg{sub x}MnO{sub 3} (x = 0, 0.05 and 0.10) hexagonal compounds prepared by solid state method, have been studied. The structural analyses of the samples were carried out by Rietveld analysis of neutron diffraction data. With increasing Mg content, we find that the lattice parameter a decreases and c increases whereas the overall Mn-O bond length decreases. Magnetization measured as a function of magnetic field at 2.5 K exhibits hysteresis, which is attributed to ferromagnetic like ordering of Yb{sup 3+} sublattice. Temperature dependence of ac magnetic susceptibility, ?{sub ac}(T), shows no signature of spin-glass behavior. ?”(T) exhibits a sudden increase at low temperatures which is due to ordering of Yb{sup 3+} sublattice.

  20. Ion-exchanged waveguide lasers in Er3+/Yb3+ codoped silicate glass.

    PubMed

    Peters, P M; Funk, D S; Peskin, A P; Veasey, D L; Sanford, N A; Houde-Walter, S N; Hayden, J S

    1999-11-20

    We investigated an Er(3+)/Yb(3+) codoped silicate glass as a host material for waveguide lasers operating near 1.5 microm. Spectroscopic properties of the glass are reported. Waveguide lasers were fabricated by K(+)-ion exchange from a nitrate melt. The waveguides support a single transverse mode at 1.5 microm. An investigation of the laser performance as a function of the Yb:Er ratio was performed, indicating an optimal ratio of approximately 5:1. Slope efficiencies of as great as 6.5% and output powers as high as 19.6 mW at 1.54 microm were realized. The experimental results are compared with a waveguide laser model that is used to extract the Er(3+) upconversion coefficients and the Yb(3+)-Er(3+) cross-relaxation coefficients. The results indicate the possibility of obtaining high-performance waveguide lasers from a durable silicate host glass. PMID:18324230

  1. Grain size effect on magnetic and dielectric properties of hexagonal YbMnO3 nanoparticles

    NASA Astrophysics Data System (ADS)

    Han, Tai-Chun; Hsu, Hsin-Kai; Chu, Yih-Tsyr; Hu, Yu-Min

    2015-05-01

    We have synthesized a series of YbMnO3 nanoparticles with different grain sizes (25-450 nm) and study the effect of grain size on their structural, magnetic, and dielectric properties. The YbMnO3 nanoparticles crystallized in hexagonal perovskite-type structure. It shows that magnetic and dielectric properties are strongly dependent on the grain size. The magnetic characterization indicates that with increasing grain size, the antiferromagnetic (AFM) transition temperature increases from 70 to 86 K. A corresponding shift in the peak-positions of dielectric anomaly and AFM transition temperature is observed, indicating a strong correlation between the magnetic ordering and the electric polarization. As evidenced by the variation in the ab-plane lattice parameters and Mn-O bond lengths, the AFM interactions and dielectric anomalies of YbMnO3 can be effectively modulated by varying grain size.

  2. PHOTONIC CRYSTAL SURFACE ENHANCED UPCONVERSION EMISSION OF YF3:Yb3+, Er3+ NANOPARTICLES

    NASA Astrophysics Data System (ADS)

    Shao, Bo; Yang, Zhengwen; Li, Jun; Liao, Jiayan; Lai, Shenfeng; Qiu, Jianbei; Song, Zhiguo; Yang, Yong; Zhou, Dacheng

    2015-11-01

    The opal photonic crystals made of polystyrene microspheres with 155, 230, 270 or 410 nm in diameter were used to enhance upconversion (UC) emission of YF3:Yb3+, Er3+ nanoparticles, respectively. The red or green UC emission of YF3:Yb3+, Er3+ nanoparticles can be selectively enhanced when the red or green UC emission wavelength overlapped with the photonic bandgaps of opals, which is attributed to Bragg reflection of photonic bandgap. In addition, when the 980 nm excitation light wavelength was in the region of the photonic bandgap, red and green UC emissions of YF3:Yb3+, Er3+ nanoparticles were enhanced due to the enhancement of excitation field.

  3. Laser desorption/ionization mass spectrometry on nanostructured semiconductor substrates: DIOS(TM) and QuickMass(TM)

    NASA Astrophysics Data System (ADS)

    Law, K. P.

    2010-02-01

    In the era of systems biology, new analytical platforms are under demand. Desorption/ionization on silicon mass spectrometry (DIOS-MS) is a promising high throughput laser mass spectrometry approach that has attracted a lot of attention, and has been commercialized. Another substrate material manufactured by physical method has also been made commercially available under the trade name of QuickMass(TM). These two commercial substrates, DIOS(TM) and QuickMass(TM), were investigated independently from the manufacturers and were characterized by a number of advanced surface techniques. This work determined (1) the correlation between the substrate physicochemical properties and their LDI activity, (2) the feasibility of metabolic profiling from complex biological matrices and (3) the laser desorption/ionization mechanism. The DIOS(TM) substrate was characterized with a thick nano-sized porous layer, a high surface concentration of fluorocarbon and silicon oxides and super-hydrophobicity. In contrast, the QuickMass(TM) substrate consisted of a non-porous germanium thin-film. The relatively high ionization efficiency obtained from the DIOS(TM) substrate was contributed to the fluorosilane manufacturing processes and its porous morphology. Despite the QuickMass(TM) substrate being less effective, it was noted that the use of germanium affords a self-cleaning mechanism and suppresses background interference of mass spectra. The suitability of DIOS(TM) substrates for metabolic profiling of complex biological matrices was demonstrated. DIOS mass spectra of human blood plasma, human urine and animal liver tissue extracts were produced. Suitable extraction methods were found to be important, but relatively simplified approaches were sufficient. Further investigations of the DIOS desorption/ionization mechanism were carried out. The previously proposed sub-surface state reaction could be a molten-solid interfacial state reaction of the substrate and this had a significant effect toward the protonation reaction of amines.

  4. The EU Dimension to Soil Science in Schools

    ERIC Educational Resources Information Center

    Johnson, Sue

    2012-01-01

    The EU as a context for science lessons may be given scant attention but EU decision-making is a vital factor in everyday life. Lessons on the emergence of soil science with Charles Darwin's simple scientific experiments can be linked with competence through action, inclusion and argumentations in science lessons. Decisions about an EU Soil…

  5. Research and EU Liaison Office, Technology Transfer B. Guidelines

    E-print Network

    Nejdl, Wolfgang

    Department Research and EU Liaison Office, Technology Transfer 1/4 B. Guidelines I. General and EU Liaison Office, Technology Transfer 2/4 II. Structure of the Application 1. Project title 2;Department Research and EU Liaison Office, Technology Transfer 3/4 4.2. Application filed elsewhere For any

  6. 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

  7. Role of electron transfer in Ce{sup 3+} sensitized Yb{sup 3+} luminescence in borate glass

    SciTech Connect

    Sontakke, Atul D. Katayama, Yumiko; Zhuang, Yixi; Tanabe, Setsuhisa; Ueda, Jumpei; Dorenbos, Pieter

    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??m have been observed on Ce{sup 3+} 5d state excitation. However, the intensity of sensitized Yb{sup 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.

  8. 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. PMID:26220082

  9. Directly diode-pumped femtosecond laser based on an Yb:KYW crystal

    NASA Astrophysics Data System (ADS)

    Kim, G. H.; Yang, J.; Lee, D. S.; Kulik, A. V.; Sall', E. G.; Chizhov, S. A.; Yashin, V. E.; Kang, U.

    2012-01-01

    Ultrashort pulse laser systems are widely used in many areas such as microprocessing of various materials, the generation of terahertz radiation, nonlinear optics, medical tomography, chemistry, and biology due to the high peak power and large spectral width. For a practical usage of the femtosecond lasers, they must be fairly compact and stable. These conditions are most fully met when laser media are used that allow direct pumping with the radiation from semiconductor injection lasers, which are more compact, reliable, and inexpensive than pumping with solid-state lasers. Since Ytterbium-doped crystals have a broad luminescence band for generating femtosecond pulses less than 500 fs wide, they are attractive as materials for lasers with direct diode pumping. Moreover, the position of the central luminescence wavelength of Yb:KGW and Yb:KYW crystals makes them promising priming sources of femtosecond pulses for amplifiers that operate at wavelengths close to 1 ?m (Yb:KGW, Yb-glass, Nd-glass, Yb:YAG, etc.) We developed a femtosecond generator based on the Yb:KYW crystal with direct pumping by the radiation of a laser diode with fiber output of the pump radiation. The use of such pumping, as well as of chirped mirrors to compensate intracavity dispersion, made it possible to generate a continuous sequence of optical pulses 90 fs wide at a frequency of 87.8 MHz with a mean radiation power of more than 1 W. The product of the pulse width by the spectral width is close to the theoretical limit, and this indicates that there is no frequency modulation.

  10. 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.

  11. First demonstration of passively mode-locked Yb:CaF2 thin-disk laser

    NASA Astrophysics Data System (ADS)

    Dannecker, Benjamin; Délen, Xavier; Wentsch, Katrin S.; Weichelt, Birgit; Hönninger, Clemens; Voss, Andreas; Abdou Ahmed, Marwan; Graf, Thomas

    2015-02-01

    The need for ultra-short (sub-ps) pulsed laser systems with high power and high energy has advanced the mode-locked Ytterbium-doped thin-disk technology in the last decade. Therefore several research groups have made efforts to explore new laser crystals e.g. Yb:SSO, Yb:CAlGO or Yb:Lu2O3 for the generation of sub-500 fs pulses in thin-disk oscillators. Another promising and known candidate for ultra-short pulsed lasers is Yb:CaF2, which has been so far only used in bulk laser architecture. In this work, we present the first demonstration of a mode-locked Yb:CaF2 laser in thin-disk configuration. The resonator cavity was designed for eight passes through the disk per roundtrip at a repetition rate of 35 MHz. A saturable absorber mirror (SESAM) was used to obtain the soliton mode-locking. We achieved close-to transform-limited pulses with a pulse duration of less than 445 fs and an emission spectral width of 2.6 nm at FWHM (i.e. time-bandwidth product of 0.323). At the average output power of 6.6 W this corresponds to a peak-power of 430 kW and pulse energy of 190 nJ. To the best of our knowledge, this is the highest average output power and pulse energy using Yb:CaF2 as gain material reported to date. Taking into account the dispersion, self-phase modulation, pulse energy, output coupling ratio and laser gain, the pulse-duration estimated from the soliton-equation and our numerical calculations of pulse-propagation is in good agreement with the pulse-duration obtained in the experiment. Higher powers and shorter pulse-durations with this material are the subject of our future investigations.

  12. Modeling the photodegradation of large mode area Yb-doped fiber power amplifiers

    NASA Astrophysics Data System (ADS)

    Laperle, Pierre; Desbiens, Louis; Le Foulgoc, Karine; Drolet, Mathieu; Deladurantaye, Pascal; Proulx, Antoine; Taillon, Yves

    2009-02-01

    Photodarkening is presently a major concern for the long term reliability and efficiency of high power Yb-doped fiber lasers and amplifiers. This phenomenon has been associated with the formation of color centers in the fiber core of single-clad and large mode area Yb-doped fibers. However, its origin is still not well understood and to date no comprehensive model that could predict the lifetime of Yb-doped fiber-based devices has been put forward. A semi-empirical approach seems at the moment the best way to gain a better understanding of the growth behavior of photo-induced losses in Yb-doped fibers in the presence of both photodarkening and photobleaching processes. A rate equation describing the activation and deactivation of color centers involving stretched exponential functions has been developed. For this approach to be effective and reliable, a minimum of parameters is used, four to describe photodarkening and three for photobleaching. A large mode area Yb-doped fiber fabricated at INO using the MCVD process has been characterized. By properly choosing the initial pumping conditions, each parameter of the stretched exponential functions has been measured separately from the others. The model has then been used to simulate the power decay from a 1 kW, 10 ns-pulse, 100 kHz Yd-doped LMA fiber power amplifier. We show that the photodarkening behavior predicted by the model is in good agreement with the experimental results over more than 6000 hours. Such a model is general in its application but the stretched exponential parameters are unique to the type of fiber tested. The model will be a useful characterization tool for developing photodarkening-resistant fibers and for evaluating the lifetime of Yb-doped fiber-based devices affected by photodegradation.

  13. Eu(2+) and Eu(3+) co-activated LaAlO3 phosphor: synthesis and tuned luminescence.

    PubMed

    Chen, Wanping

    2015-10-28

    Sr(2+) and Si(4+) ion doped LaAlO3:Eu phosphors were synthesized through a high-temperature solid-state reaction route. Their phase component and photoluminescence properties were investigated. Under ultraviolet (UV) light excitation, the phosphors show simultaneously blue emission of the Eu(2+) ion and orange-red emission of the Eu(3+) ion. The relative emission intensity of both Eu(2+) and Eu(3+) ions can be tuned by changing the doping concentration of the Sr(2+), Si(4+) and Eu(3+) ions. In contrast to the Sr(2+) ion, the incorporation of Si(4+) ion can effectively enhance the emission of Eu(2+). The optimal doping concentration of the Eu(3+) and Si(4+) ions are about 0.02 and 0.03, respectively. The results indicate that the phosphor may be a potential candidate for white LED lighting applications. PMID:26394659

  14. Deposition of luminescent NaCl:Tm2+ thin films with a Tm concentration gradient using RF magnetron sputtering

    NASA Astrophysics Data System (ADS)

    de Jong, M.; Kesteloo, W.; van der Kolk, E.

    2015-08-01

    Luminescent thin films were deposited using magnetron sputtering of a NaCl single crystal and Tm-metal. By using a combinatorial approach, a single film with a thickness ranging from 3.1 ?m to 6.9 ?m and a Tm to Na ratio varying from 0.05 to 0.26 was obtained. XRD shows the formation of the simple cubic NaCl structure and SEM images display a mix of 0.50-0.75 ?m and 2-3 ?m cubic and needle-like structures when the substrate is not rotating during deposition. NIR transmission spectra reveal narrow absorption lines at 1134 nm and 1218 nm caused by 4f-4f absorption of divalent and trivalent Tm, respectively. Photoluminescence excitation and UV-VIS transmission spectra show broad bands between 275 nm and 700 nm, caused by the Tm2+ 4f13 ? 4f125d1 transitions. Excitation into these bands results in 2F5/2 ? 2F7/2 line emission by Tm2+ at 1134 nm. The broad absorption range covering the entire UV and VIS part of the solar spectrum and the absence of self-absorption of the sharp emission line makes NaCl:Tm2+ a promising material for luminescent solar concentrators as thin films on glass provided light scattering can be minimised.

  15. Ends of the line for tmRNA-SmpB

    PubMed Central

    Hudson, Corey M.; Lau, Britney Y.; Williams, Kelly P.

    2014-01-01

    Genes for the RNA tmRNA and protein SmpB, partners in the trans-translation process that rescues stalled ribosomes, have previously been found in all bacteria and some organelles. During a major update of The tmRNA Website (relocated to http://bioinformatics.sandia.gov/tmrna), including addition of an SmpB sequence database, we found some bacteria that lack functionally significant regions of SmpB. Three groups with reduced genomes have lost the central loop of SmpB, which is thought to improve alanylation and EF-Tu activation: Carsonella, Hodgkinia, and the hemoplasmas (hemotropic Mycoplasma). Carsonella has also lost the SmpB C-terminal tail, thought to stimulate the decoding center of the ribosome. We validate recent identification of tmRNA homologs in oomycete mitochondria by finding partner genes from oomycete nuclei that target SmpB to the mitochondrion. We have moreover identified through exhaustive search a small number of complete, but often highly derived, bacterial genomes that appear to lack a functional copy of either the tmRNA or SmpB gene (but not both). One Carsonella isolate exhibits complete degradation of the tmRNA gene sequence yet its smpB shows no evidence for relaxed selective constraint, relative to other genes in the genome. After loss of the SmpB central loop in the hemoplasmas, one subclade apparently lost tmRNA. Carsonella also exhibits gene overlap such that tmRNA maturation should produce a non-stop smpB mRNA. At least some of the tmRNA/SmpB-deficient strains appear to further lack the ArfA and ArfB backup systems for ribosome rescue. The most frequent neighbors of smpB are the tmRNA gene, a ratA/rnfH unit, and the gene for RNaseR, a known physical and functional partner of tmRNA-SmpB. PMID:25165464

  16. Synthesis and study of the heavy-fermion compound Yb5Pt9 M. S. Kim,1 M. C. Bennett,1 D. A. Sokolov,1 M. C. Aronson,1 J. N. Millican,2 Julia Y. Chan,2 Q. Huang,3

    E-print Network

    Aronson, Meigan

    , 71.27. a I. INTRODUCTION Heavy-fermion systems based on Ce and U intermetallic compounds have focused on Yb-based compounds, because the synthesis of Yb-intermetallic compounds is difficult due the synthesis of a Yb-based intermetallic compound, Yb5Pt9, and present the results of transport, magnetic

  17. Yb 3+-doped Ba 2NaNb 5O 15 (BNN) growth, characterization and spectroscopy

    NASA Astrophysics Data System (ADS)

    Romo, F. Carrillo; Goutaudier, C.; Guyot, Y.; Cohen-Adad, M. Th.; Boulon, G.; Lebbou, K.; Yoshikawa, A.; Fukuda, T.

    2001-02-01

    Low-temperature spectroscopy of host barium sodium niobate - Ba 2NaNb 5O 15 (BNN) crystal fibers doped with Yb 3+ ion has been studied. The fibers were grown by the laser-heated pedestal growth (LHPG) technique, and were characterized among others by X-ray diffraction, micro-Raman spectroscopy, X-ray fluorescence and optical microscopy. The results showed very homogeneous and defect-free materials with pseudotetragonal structure appropriate for optical applications. Absorption and emission spectroscopic studies at low temperature were used to determine the energy-level diagram of the Yb 3+ ion in host BNN.

  18. Thin-disk Raman laser operation of Yb:YVO4/YVO4 around 1120 nm

    NASA Astrophysics Data System (ADS)

    Yang, F. G.; Qiao, L.; Xia, Z. C.

    2015-12-01

    We present diode-pumped Yb:YVO4/YVO4 thin-disk Raman laser operation around 1120?nm. The thin-disk crystals, Yb:YVO4, and the Raman crystal, YVO4, are cut with 250 ?m and 20?mm, respectively. In multimode configurations, up to 0.91?W of Raman laser output power and a maximum slope efficiency of 10% are demonstrated corresponding to a pump power of 10?W. A continuous wavelength tuning range of 54?nm from 1096 to 1150?nm with a maximum output power of 320 mW at 1126?nm is confirmed.

  19. Sol-gel silica films embedding NIR- emitting Yb-quinolinolate complexes

    SciTech Connect

    Figus, Cristiana Quochi, Francesco Piana, Giacomo; Saba, Michele; Mura, Andrea; Bongiovanni, Giovanni; Artizzu, Flavia; Mercuri, Maria Laura; Serpe, Angela; Deplano, Paola

    2014-10-21

    Sol-gel silica thin films embedding an ytterbium quinolinolato complex (YbClQ{sub 4}) have been obtained using different alkoxides. Homogeneous, crack- and defect-free thin films of optical quality have been successfully deposited on glass substrate by dip-coating. The silica thin films have been characterized by time-resolved photoluminescence. The luminescence properties of the YbClQ{sub 4} are preserved in silica films prepared through an optimized sol-gel approach. The excited state lifetime of the lanthanide is comparable to those observed in bulk and longer than the corresponding ones in solution.

  20. [Frequency up-conversion properties of Er3+ /Yb3+ co-doped zinc oxide powders].

    PubMed

    Wu, Qun; Yang, Li-Wen; Liu, Yun-Xin; Xu, Chang-Fu; Shang, Zhen-Gang; Zhang, Yong; Yang, Qi-Bi

    2008-07-01

    Er3+ /Yb3+ co-doped ZnO powders were prepared by the high temperature sintering method with starting composition of (mol%) 95ZnF2-4. 8Yb2 O3-0. 2Er2 O3. Microstructure analysis by X-ray diffraction (XRD) showed that the sample consists of two phases, i. e. ZnO and YbF3, which verified that the ZnF2 was oxidized during the high temperatue sintering Composition analysis by scanning electron microscope (SEM) and spectroscopic measurements showed that the Er3+ and Yb3+ ons were successfully used in doping the lattice of ZnO, but most of Yb3+ ions were in the YbF3 phase. These results indicated that the up-conversion luminescence was emitted from ZnO, not from YbF3. Under the excitation of 980 nm diodelaser, four strong up-conversion emissions peaks centered at 658, 538, 522 and 409 nm, corresponding to the transitions 4F9/2 --> 4I15/2, 4S3/2 --> 4I15/2, 2 H11/2 --> 4I15/2 and 2 H9/2 --> I15/2, respectively, were observed. Especially, a strong red up-conversion emission was observed, which is different from that the green up-converted luminescence is dominated in glass and ceramics. Three important cross energy transfer (CRET) processes between Er3+ ions played an important role for this. Under 488 nm Ar+ laser excitation, intense violet (409 nm), weak blue (466, 450 nm) and ultraviolet (379 nm) up-conversion luminescence originating from the transitions 2 H9/2 --> 4I15/2, 2P3/2 --> 4I11/2, 4 F3/2 /4 F5/2 --> 4I15/ 2 and 4G11/2 --> 4 I15/2, respectively, were obtained. The dependence of up-conversion intensities on excitation power indicated that two-photon absorption processes were responsible for the violet luminescence under 488 nm excitation, and the violet up-converted luminescence was achieved through the forward and back energy transfer between Er3+ and Yb3+ ions. Our results show that ZnO as a host material has the potential applications in the up-conversion red phosphors and ultraviolet laser materials. PMID:18844142

  1. Low-power, miniature {sup 171}Yb ion clock using an ultra-small vacuum package

    SciTech Connect

    Jau, Y.-Y.; Schwindt, P. D. D.; Partner, H.; Prestage, J. D.; Kellogg, J. R.; Yu, N.

    2012-12-17

    We report a demonstration of a very small microwave atomic clock using the 12.6 GHz hyperfine transition of the trapped {sup 171}Yb ions inside a miniature, completely sealed-off 3 cm{sup 3} ion-trap vacuum package. In the ion clock system, all of the components are highly miniaturized with low power consumption except the 369 nm optical pumping laser still under development for miniaturization. The entire clock, including the control electronics, consumes <300 mW. The fractional frequency instability of the miniature Yb{sup +} clock reaches the 10{sup -14} range after a few days of integration.

  2. Dual nature of 3 d electrons in YbT 2 Zn 20 (T = Co; Fe) evidenced by electron spin resonance

    DOE PAGESBeta

    Ivanshin, V. A.; Litvinova, T. O.; Gimranova, K.; Sukhanov, A. A.; Jia, S.; Bud'ko, S. L.; Canfield, P. C.

    2015-03-18

    The electron spin resonance experiments were carried out in the single crystals YbFe2Zn20. The observed spin dynamics is compared with that in YbCo2Zn20 and Yb2Co12P7 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 YbFe2Zn20 and localized in YbCo2Zn20. Possible connection between spin paramagnetism of dense heavy fermion systems, quantum criticality effects, and ESR spectra is discussed.

  3. Nuclear Data Sheets for A = 151

    SciTech Connect

    Singh, B.; Szuecs, J. A.; Johns, M. W.

    1988-10-01

    The 1976 version of A = 151 mass chain (76Ha35) has been revised. The evaluated experimental data are presented for 14 known nuclides of A = 151 (Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu). Except for their isotopic identification, nothing much is known about 3 nuclides in this mass chain (Ce, Pr, and Lu) which are far off the stability line. High spin excitations are known for 9 nuclides (Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm and Yb). Particle transfer data are available for 5 nuclides (Nd, Pm, Sm, Eu and Gd). The neutron capture data are available for /sup 151/Sm and /sup 151/Nd. In terms of a variety of experimental studies, the /sup 151/Sm and /sup 151/Eu nuclides are the ones most extensively studied. copyright 1988 Academic Press, Inc.

  4. Traffic at the tmRNA Gene

    PubMed Central

    Williams, Kelly P.

    2003-01-01

    A partial screen for genetic elements integrated into completely sequenced bacterial genomes shows more significant bias in specificity for the tmRNA gene (ssrA) than for any type of tRNA gene. Horizontal gene transfer, a major avenue of bacterial evolution, was assessed by focusing on elements using this single attachment locus. Diverse elements use ssrA; among enterobacteria alone, at least four different integrase subfamilies have independently evolved specificity for ssrA, and almost every strain analyzed presents a unique set of integrated elements. Even elements using essentially the same integrase can be very diverse, as is a group with an ssrA-specific integrase of the P4 subfamily. This same integrase appears to promote damage routinely at attachment sites, which may be adaptive. Elements in arrays can recombine; one such event mediated by invertible DNA segments within neighboring elements likely explains the monophasic nature of Salmonella enterica serovar Typhi. One of a limited set of conserved sequences occurs at the attachment site of each enterobacterial element, apparently serving as a transcriptional terminator for ssrA. Elements were usually found integrated into tRNA-like sequence at the 3? end of ssrA, at subsites corresponding to those used in tRNA genes; an exception was found at the non-tRNA-like 3? end produced by ssrA gene permutation in cyanobacteria, suggesting that, during the evolution of new site specificity by integrases, tropism toward a conserved 3? end of an RNA gene may be as strong as toward a tRNA-like sequence. The proximity of ssrA and smpB, which act in concert, was also surveyed. PMID:12533482

  5. Effect of Eu-citrate complex composition on its cementation

    SciTech Connect

    Lebedev, V.M.; Kornilov, A.S.; Yadovin, A.A.

    1995-03-01

    The dependence of Eu cementation by sodium amalgam in a semicountercurrent regime from citrate solutions on the Eu complex composition is studied. The purity of the {sup 153}Gd product from radioactive Eu can be increased during cementation by introducing correcting solutions of citric acid and stable Eu. The selected conditions are verified by processing irradiated targets. The content of radioactive Eu in the {sup 153}Gd product is reduced from 0.01 to 0.0005% with respect to {gamma}-activity.

  6. Phases in the Al-Yb-Zn system between 25 and 50 at% ytterbium

    SciTech Connect

    Mazzone, Donata; Manfrinetti, Pietro; Fornasini, Maria L.

    2009-09-15

    Phases YbZn{sub 1-x}Al{sub x}, YbZn{sub 2-x}Al{sub x} and YbZn{sub 3-x}Al{sub x} were studied by electron microprobe analysis and X-ray single crystal and powder methods. The compound YbZn{sub 0.8}Al{sub 0.2} crystallizes with the CsCl-type, a=3.635(2) A. Four phases were investigated by single crystal X-ray diffraction: YbZn{sub 0.996(6)}Al{sub 1.004(6)}, MgNi{sub 2}-type, P6{sub 3}/mmc, a=5.573(1), c=18.051(3) A, Z=8, wR2=0.040 and YbZn{sub 0.88(3)}Al{sub 1.12(3)}, MgCu{sub 2}-type, Fd3-barm, a=7.860(2) A, Z=8, wR2=0.060, both showing mixed Zn/Al occupancy; YbZn{sub 2.50(1)}Al{sub 0.50(1)}, CeNi{sub 3}-type, P6{sub 3}/mmc, a=5.496(1), c=17.336(2) A, Z=6, wR2=0.036 and YbZn{sub 1.92(2)}Al{sub 1.08(2)}, PuNi{sub 3}- or NbBe{sub 3}-type, R3-barm, a=5.499(1), c=26.134(5) A, Z=9, wR2=0.053, where the zinc atoms are ordered in the CaCu{sub 5} segment, while share the sites with aluminium in the Laves phase segment. In the pseudobinary section YbZn{sub 2-x}Al{sub x} four structures occur in sequence with increasing the electron concentration: CeCu{sub 2} or KHg{sub 2} (x=0-0.3), MgZn{sub 2} (x=0.33-0.54), MgNi{sub 2} (x=0.68-1.01) and MgCu{sub 2} (x=1.12-2). This sequence agrees with the results of first-principles calculations, already reported in the literature for other similar series. In the YbZn{sub 3-x}Al{sub x} section CeNi{sub 3}-type compounds occur with x=0.40-0.88 followed by PuNi{sub 3}-type compounds with x=0.92-1.10. The stability ranges of these phases are related to the valence electron concentration. - Graphical abstract: In the pseudobinary section YbZn{sub 2-x}Al{sub x} four structures occur in sequence on increasing the aluminium content: CeCu{sub 2} (or KHg{sub 2}), MgZn{sub 2}, MgNi{sub 2} and MgCu{sub 2}. Volumes per atom vs. composition are reported in the figure.

  7. Small RNA analysis using the Genome SequencerTM The Genome SequencerTM FLX System from 454 Life SciencesTM and Roche Applied Science is a

    E-print Network

    Cai, Long

    454 Life SciencesTM and Roche Applied Science is a versatile sequencing platform suitable for a wide &Timothy Harkins2 1454 Life Sciences, 20 Commercial Street, Branford, Connecticut 06405, USA. 2Roche Diagnostics, Roche Applied Science, 9115 Hague Road, Indianapolis, Indiana 46250, USA. Correspondence should

  8. Spectroscopic characterization of dynamical processes for Tm,Ho:YAG lasers

    NASA Technical Reports Server (NTRS)

    Armagan, G.; Buoncristiani, A. M.; Edwards, W. C.; Inge, A. T.; Dibartolo, B.

    1991-01-01

    The energy transfer processes in Tm,Ho:YAG lasers were investigated in spectral studies and measurements of the temporal response to pulsed excitation. These processes include the population of the 3H4 pump band of Tm, cross-relaxation in Tm, the transfer of energy from Tm to Ho, and various loss mechanisms. It was found that the Tm cross-relaxation is due to a dipole-dipole interaction between Tm ions and that the rate of this process is a function of temperature and ion concentration.

  9. Thortveitite-type Tm2Si2O7

    PubMed Central

    Kahlenberg, Volker; Aichholzer, Paul

    2014-01-01

    Single crystals of dithulium disilicate, Tm2Si2O7, were obtained in flux synthesis experiments in the system SiO2–Tm2O3–LiF at ambient pressure. The compound belongs to the group of sorosilicates, i.e. it is based on [Si2O7]-units and crystallizes in the thortveitite (Sc2Si2O7) structure type. The Tm3+ cation (site symmetry .2.) occupies a distorted octa­hedral site, with Tm—O bond lengths in the range 2.217?(4)–2.289?(4)?Å. Each of the octa­hedra shares three of its edges with adjacent [TmO6] groups, resulting in the formation of layers parallel to (001). The individual [SiO4] tetra­hedra are more regular, i.e. the differences between the bond lengths between Si and the bridging and non-bridging O atoms are not very pronounced. The layers containing the octa­hedra and the sheets containing the [Si2O7] groups (point group symmetry 2/m) form an alternating sequence. Linkage is provided by sharing common oxygen vertices. PMID:25161507

  10. Pred?TM: A Novel ?-Transmembrane Region Prediction Algorithm

    PubMed Central

    Roy Choudhury, Amrita; Novi?, Marjana

    2015-01-01

    Predicting the transmembrane regions is an important aspect of understanding the structures and architecture of different ?-barrel membrane proteins. Despite significant efforts, currently available ?-transmembrane region predictors are still limited in terms of prediction accuracy, especially in precision. Here, we describe Pred?TM, a transmembrane region prediction algorithm for ?-barrel proteins. Using amino acid pair frequency information in known ?-transmembrane protein sequences, we have trained a support vector machine classifier to predict ?-transmembrane segments. Position-specific amino acid preference data is incorporated in the final prediction. The predictor does not incorporate evolutionary profile information explicitly, but is based on sequence patterns generated implicitly by encoding the protein segments using amino acid adjacency matrix. With a benchmark set of 35 ?-transmembrane proteins, Pred?TM shows a sensitivity and precision of 83.71% and 72.98%, respectively. The segment overlap score is 82.19%. In comparison with other state-of-art methods, Pred?TM provides a higher precision and segment overlap without compromising with sensitivity. Further, we applied Pred?TM to analyze the ?-barrel membrane proteins without defined transmembrane regions and the uncharacterized protein sequences in eight bacterial genomes and predict possible ?-transmembrane proteins. Pred?TM can be freely accessed on the web at http://transpred.ki.si/. PMID:26694538

  11. Ytterbium doped silicon clusters YbSin (n = 4-10) and their anions: Structures, thermochemistry, and electron affinities

    NASA Astrophysics Data System (ADS)

    Xie, Xiaohong; Hao, Dongsheng; Yang, Jucai

    2015-11-01

    The structures, electron affinities, dissociation energies, hardness, and dipole moments of YbSin (n = 4-10) and their anions were examined using B3LYP, TPSSh, PBE and wB97X methods. The lowest-energy structures can be regarded as replacing a Si of the ground-state structure of Sin+1 with a Yb atom. The theoretical adiabatic electron affinities (AEAs) of YbSin are in excellent agreement with experimental data. The average absolute errors from experiment are by 0.08, 0.07, 0.05 and 0.08 eV at the B3LYP, the TPSSh, the PBE and the wB97X levels, respectively. Theoretical AEAs of 2.33 ± 0.05 eV for YbSi9 are more reliable than the experimental value of 2.60 ± 0.05 eV. The hardness analysis reveals that doping Yb atom to Sin (n = 4-10) clusters raises the photochemical sensitivity. The dissociation energies of Yb atom from YbSin and their anions were calculated to examine relative stabilities.

  12. Synthesis, structure and charge transport properties of Yb(5)Al(2)Sb(6): a zintl phase with incomplete electron transfer.

    PubMed

    Todorov, Iliya; Chung, Duck Young; Ye, Linhui; Freeman, Arthur J; Kanatzidis, Mercouri G

    2009-06-01

    We report the synthesis, structure, spectroscopic properties, charge and thermal transport, and electronic structure of a new member of the Zintl family, Yb(5)Al(2)Sb(6). The compound crystallizes in the Ba(5)Al(2)Bi(6) structure type and requires the addition of Ge or Si in the synthesis, which appears to act as a catalyst. Yb(5)Al(2)Sb(6) has an anisotropic structure with infinite anionic double chains cross-linked by Yb(2+) ions. Polycrystalline ingots of Yb(5)Al(2)Sb(6) prepared in the presence of 0.5 mol equiv of Ge showed room-temperature conductivity, thermopower, and thermal conductivity of approximately 1100 S/cm, approximately 20 microV/K, and approximately 3.8 W/m.K, respectively. Investigations of other solid solutions of Yb(5)Al(2)Sb(6), doping effects, and chemical modifications are discussed. Sr only partially replaces Yb in the structure leading to Sr(0.85)Yb(4.15)Al(2)Sb(6). Electronic structure calculations performed using a highly precise full-potential linearized augmented plane wave method within the density functional theory scheme show the presence of a negative band gap and suggest incomplete electron transfer and a metallic character to the compound. PMID:19374366

  13. Evolution of Spinons with Magnetic Field in the One-Dimensional Heavy Fermion Yb2Pt2Pb

    NASA Astrophysics Data System (ADS)

    Gannon, W. J.; Wu, L.; Zaliznyak, I. A.; Demmel, F.; Aronson, M. C.

    2015-03-01

    The antiferromagnetic (AF) metal Yb2Pt2Pb has a layered crystal structure, with Yb ions arranged in chains along the c-axis, while pairs of chains form orthogonal dimers in the tetragonal a- b plane, an in-plane structure that is topologically equivalent to the Shastry-Sutherland lattice (SSL). In zero magnetic field, 70% of the magnetic spectral weight is static, consisting of AF Bragg peaks corresponding to moments that order at TN = 2 . 07 K, while fluctuations of the Yb moments, present even at T=0 are responsible for the remaining 30%. The low energy magnetic excitation spectrum observed in neutron scattering experiments is unambiguously one-dimensional, consisting exclusively of gapped, Heisenberg-like spinons that disperse along the Yb chain direction, while remaining dispersionless in the SSL layers. As field is increased, the static magnetic order is suppressed and a rapidly evolving set of longitudinal modes with dispersions both parallel and perpendicular to the Yb chains is observed, until the Yb moments are fully polarized at fields above 2.3 T. This places Yb2Pt2Pb very near but on the ordered side of the quantum critical point that links quantum mechanical Heisenberg and classical Ising physics in one dimension. This project was supported by NSF-DMR-1310008.

  14. Visible to near infrared conversion in Ce{sup 3+}-Yb{sup 3+} Co-doped YAG ceramics

    SciTech Connect

    Ueda, Jumpei; Tanabe, Setsuhisa

    2009-08-15

    In Ce{sup 3+}-Yb{sup 3+} co-doped Y{sub 3}Al{sub 5}O{sub 12} (YAG) ceramics, possibility of quantum cutting mechanism converting one visible photon into two NIR photons with optimum quantum efficiency approaching 200% have been investigated. In this material, Yb{sup 3+} emissions due to the {sup 2}F{sub 5/2}-{sup 2}F{sub 7/2} in the range of 1 mum were observed upon the excitation of 5d level of Ce{sup 3+}. In addition, excitation spectra of Yb{sup 3+} emission corresponded to that of Ce{sup 3+} emission completely. Lifetime of the 5d level of Ce{sup 3+} decreased with increasing Yb{sup 3+} content. These results indicate the energy transfer (ET) from the 5d levels of Ce{sup 3+} to the {sup 5}F{sub 5/2} level of Yb{sup 3+}. In (Y{sub 0.945}Ce{sub 0.005}Yb{sub 0.05}) {sub 3}Al{sub 5}O{sub 12} sample, the directly measured quantum yield (QY) of Yb{sup 3+} emission upon the excitation of 5d level of Ce{sup 3+} was about 12% and lower than QY (96%) that estimated from the ET efficiency which was calculated with the measured lifetime of Ce{sup 3+}.

  15. EPR and optical study of Yb3+-doped ?-PbF2 single crystals and nanocrystals of glass-ceramics

    NASA Astrophysics Data System (ADS)

    Dantelle, G.; Mortier, M.; Goldner, Ph; Vivien, D.

    2006-08-01

    ?-PbF2 single crystals doped with YbF3 (0.2% and 2%) were studied by x-ray diffraction (XRD), electron paramagnetic resonance (EPR) and optical spectroscopy. EPR revealed the presence of only one kind of paramagnetic ion Yb3+, in a cubic symmetry site. The optical absorption, emission and excitation spectra enabled us to identify the transitions attributed to Yb3+ in the cubic site and to determine its energy level diagram. Site-selective laser spectroscopy also evidenced the presence of another type of Yb3+ ions, undetectable by classical EPR. This second type, which dominates in the 2%-doped crystal and exhibits cooperative luminescence, was attributed to Yb3+ ions forming clusters. Transparent oxyfluoride glass-ceramics, containing ?-Pb1-yYbyF2+y nanocrystallites, were also synthesized and studied by XRD, EPR and optical spectroscopy. Two types of Yb3+ ions were found, as in ?-PbF2 single crystals. The optical properties of the oxyfluoride glass-ceramics turn out to be similar to those of ytterbium activated ?-PbF2 single crystals. Moreover, the Yb environments found in PbF2 single crystals seem to already occur in the parent glass. Therefore, these materials are expected to be good laser media, like the rare-earth doped fluorite crystals, either in bulk or fibre form.

  16. Bright orange upconversion in a ZnO-TiO2 composite containing Er3+ and Yb3+

    NASA Astrophysics Data System (ADS)

    Luitel, Hom Nath; Ikeue, Kazuya; Okuda, Risa; Chand, Rumi; Torikai, Toshio; Yada, Mitsunori; Watari, Takanori

    2014-01-01

    ZnO-TiO2 composite system containing Er3+ and Yb3+ were prepared by solid state reaction method and its upconversion (UC) luminescence excited by 980 nm laser was studied for the first time. The effects of firing temperature, ZnO/TiO2 composition and Er3+, Yb3+ concentrations on the UC emission behavior were examined. The ZnO-TiO2 composite product sintered at 1200 °C contained Zn2TiO4, TiO2 and RE2Ti2O7 (RE = Er3+ and Yb3+) phases and exhibited strong green and red emissions arising due to the 2H11/2, 4S3/2 ? 4I15/2 and 4F9/2 ? 4I15/2 transitions for Er3+ ion, respectively. Bright orange color by the mixing of green and red colors was observed in the 1ZnO-1TiO2 product doped with 2 at.% Er3+ and 6 at.% Yb3+. The ZnO-TiO2:Er3+, Yb3+ phosphor was compared to the brightest available phosphor, Y2O3:Er3+, Yb3+ and found to be 3-fold brighter than it. It suggests that ZnO-TiO2:Er3+, Yb3+ is a potential material for the orange upconversion phosphor.

  17. Expression of the multifunctional Y-box protein, YB-1, in myofibroblasts of the infarcted rat heart

    SciTech Connect

    Kamalov, German; Varma, Balwantkumar R.; Lu Li; Sun Yao; Weber, Karl T.; Guntaka, Ramareddy V. . E-mail: rguntaka@utmem.edu

    2005-08-19

    Intracellular signaling mechanisms regulating the turnover of {alpha}-SMA-positive myofibroblasts (myoFbs) at the site of myocardial infarction (MI) are poorly understood. Y-Box (YB)-1, a multifunctional protein, may be involved in regulation of proliferation, migration and apoptosis of myoFbs. Our objective was to study the expression of YB-1 in the infarcted rat heart and its localization in myoFbs. On days 3-28 following MI, we monitored YB-1 expression and its colocalization with {alpha}-SMA, and proliferation markers PCNA and Ki-67 in infarcted tissue by Western blot, immunohistochemistry, and immunofluorescent double-labeling. YB-1 is barely detectable in normal myocardium. At the infarct site, however, YB-1 is markedly elevated from day 3 post-MI concomitant with the induction of cell proliferation. MyoFbs are the major source of YB-1 and retain it up to day 28 post-MI. We suggest early expression of YB-1 promotes proliferation and migration of myoFbs, whereas prolonged expression may be responsible for scar formation.

  18. In situ dissolution or deposition of Ytterbium (Yb) metal in microhotplate wells for a miniaturized atomic clock.

    PubMed

    Manginell, Ronald P; Moorman, Matthew W; Anderson, John M; Burns, George R; Achyuthan, Komandoor E; Wheeler, David R; Schwindt, Peter D D

    2012-10-22

    Current atomic clocks are burdened by size, weight, power and portability limitations to satisfy a broad range of potential applications. One critical need in the fabrication of a miniaturized atomic clock is small, low-power metallic sources. Exploiting the relatively high vapor pressure of ytterbium (Yb) and its dissolution in anhydrous ammonia, we report two independent techniques for depositing Yb inside a well micromachined into a microhotplate. Subsequent in situ evaporation of Yb from the microhotplate well serves as a low-power metallic source suitable for atomic clocks. The deposition and evaporation of Yb were confirmed using a variety of physicochemical techniques including quartz crystal microbalance, scanning electron microscopy, energy dispersive X-ray spectroscopy, and laser fluorescence. We also describe the fabrication of the microhotplate device, an integral component of our Yb-based miniature atomic clock. The Yb deposition/evaporation on a microhotplate well is thus useful as a low power Yb source during the fabrication of a miniaturized atomic clock, and this technique could be used for other applications requiring a vapor of a metal that has a moderate vapor pressure. PMID:23187228

  19. Neutron spectroscopic study of crystalline electric field excitations in stoichiometric and lightly stuffed Yb2Ti2O7

    NASA Astrophysics Data System (ADS)

    Gaudet, J.; Maharaj, D. D.; Sala, G.; Kermarrec, E.; Ross, K. A.; Dabkowska, H. A.; Kolesnikov, A. I.; Granroth, G. E.; Gaulin, B. D.

    2015-10-01

    Time-of-flight neutron spectroscopy has been used to determine the crystalline electric field (CEF) Hamiltonian, eigenvalues and eigenvectors appropriate to the J =7 /2 Yb3 + ion in the candidate quantum spin ice pyrochlore magnet Yb2Ti2O7 . The precise ground state (GS) 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, ?2 % , of the nonmagnetic Ti4 + sites are occupied by excess Yb3 +. We have carried out neutron spectroscopic measurements on a stoichiometric powder sample of Yb2Ti2O7 , as well as a crushed single crystal with weak stuffing and an approximate composition of Yb2 +xTi2 -xO7 +y with x =0.046 . All samples display three CEF transitions out of the GS, and the GS doublet itself is identified as primarily composed of mJ=±1 /2 , as expected. However, stuffing at low temperatures in Yb2 +xTi2 -xO7 +y induces a similar finite CEF lifetime as is induced in stoichiometric Yb2Ti2O7 by elevated temperature. We conclude that an extended strain field exists about each local "stuffed" site, which produces a distribution of random CEF environments in the lightly stuffed Yb2 +xTi2 -xO7 +y , in addition to producing a small fraction of Yb ions in defective environments with grossly different CEF eigenvalues and eigenvectors.

  20. Neutron spectroscopic study of crystalline electric field excitations in stoichiometric and lightly stuffed Yb2Ti2O7

    DOE PAGESBeta

    Gaudet, J.; Maharaj, D. D.; Sala, G.; Kermarrec, E.; Ross, K. A.; Dabkowska, H. A.; Kolesnikov, A. I.; Granroth, G. E.; Gaulin, B. D.

    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 Yb3+ ion in the candidate quantum spin ice pyrochlore magnet Yb2Ti2O7. 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 Ti4+ sites are occupied by excess Yb3+. We have carried out neutron spectroscopic measurements on a stoichiometric powder sample of Yb2Ti2O7, as well as a crushed singlemore »crystal with weak stuffing and an approximate composition of Yb2+xTi2–xO7+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 mJ = ±1/2, as expected. However, stuffing at low temperatures in Yb2+xTi2–xO7+y induces a similar finite crystalline electric field lifetime as is induced in stoichiometric Yb2Ti2O7 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 Yb2+xTi2–xO7+y, in addition to producing a small fraction of Yb ions in defective environments with grossly different crystalline electric field eigenvalues and eigenvectors.« less

  1. Forty years of improvements in European air quality: the role of EU policy-industry interplay

    NASA Astrophysics Data System (ADS)

    Crippa, M.; Janssens-Maenhout, G.; Dentener, F.; Guizzardi, D.; Sindelarova, K.; Muntean, M.; Van Dingenen, R.; Granier, C.

    2015-07-01

    The EDGAR (Emissions Database for Global Atmospheric Research) v4.3 global anthropogenic emissions inventory of several gaseous (SO2, NOx, CO, non-methane volatile organic compounds (NMVOCs) and NH3) and particulate (PM10, PM2.5, black and organic carbon (BC and OC)) air pollutants for the period 1970-2010 is used to develop retrospective air pollution emission scenarios to quantify the roles and contributions of changes in fuels consumption, technology, end-of-pipe emission reduction measures and their resulting impact on health and crop yields. This database presents changes in activity data, fuels and air pollution abatement technology for the past 4 decades, using international statistics and following guidelines for bottom-up emission inventory at the Tier 1 and Tier 2 levels with region-specific default values. With two further retrospective scenarios we assess (1) the impact of the technology and end-of-pipe (EOP) reduction measures in the European Union (EU) by considering a stagnation of technology with constant emission factors from 1970 and with no further abatement measures and improvement in European emissions standards, but fuel consumption occurring at historical pace, and (2) the impact of increased fuel consumption by considering unchanged energy use with constant fuel consumption since 1970, but technological development and end-of-pipe reductions. Our scenario analysis focuses on the three most important and most regulated sectors (power generation, the manufacturing industry and road transport), which are subject of multi-pollutant EU Air Quality regulations. If technology and European EOP reduction measures had stagnated at 1970 levels, EU air quality in 2010 would have suffered from 129 % higher SO2, 71 % higher NOx and 69 % higher PM2.5 emissions, demonstrating the large role of technology in reducing emissions in 2010. However, if fuel consumption had remained constant starting in 1970, the EU would have benefited from current technology and emission control standards, with reductions in NOx by even 13 % more. Such further savings are not observed for SO2 and PM2.5. If the EU consumed the same amount of fuels as in 1970 but with the current technology and emission control standards, then the emissions of SO2 and PM2.5 would be 42 % respectively 10 % higher. This scenario shows the importance for air quality of abandoning heavy residual fuel oil and shifting fuel types (from, e.g., coal to gas) in the EU. A reduced-form TM5-FASST (Fast Screening Scenario Tool based on the global chemical Transport Model 5) is applied to calculate regional and global levels of aerosol and ozone concentrations and to assess the impact of air quality improvements on human health and crop yield loss, showing substantial impacts of export of EU technologies and standards to other world regions.

  2. 100-W Q-switched Cryogenically Cooled Yb:YAG Laser

    E-print Network

    Hybl, John D.

    This work describes a cryogenic, electro-optically Q-switched Yb:YAG laser that generates 114-W average TEM[subscript 00] power with 47% optical-to-optical efficiency. Pulse repetition frequency is 5 kHz, pulse duration ...

  3. High brightness continuous wave ceramic Yb:LuAG thin-disk laser.

    PubMed

    Peng, Yuan Han; Cheng, James; Cheah, Yan Ying; Lai, Kin Seng; Lau, Ernest; Ang, Seok Khim

    2015-07-27

    We report on a ceramic Yb:LuAG thin-disk laser in continuous wave operation. The Yb:LuAG ceramic was fabricated using solid-state reactive sintering method. In multi-mode operation in open-air, an output power of 1.74 kW with an optical-to-optical efficiency of 65.0% and slope efficiency of 71.2% was obtained. In near-fundamental mode operation we obtained an output power of 1.29 kW and an average beam quality factor of M2 = 1.44 with an optical-to-optical efficiency of 48.2%. The near-fundamental mode result was realized with a simple evacuated, stable resonator cavity with just the thin-disk gain medium and output coupler. To the best of the authors' knowledge, this is not only the first time more than 1 kW has been demonstrated from a ceramic Yb:LuAG medium, but this is also currently the brightest continuous wave Yb-doped ceramic laser. PMID:26367619

  4. SESAM modelocked Yb:CaGdAlO4 laser in the soliton modelocking regime

    E-print Network

    Keller, Ursula

    SESAM modelocked Yb:CaGdAlO4 laser in the soliton modelocking regime with positive intracavity SESAM modelocking in the near-infrared by using cascaded quadratic nonlinearities (phase mirrors (SESAM's) for femtosecond to nanosecond pulse generation in solid-state lasers," Selected Topics

  5. Photoelectron Spectroscopy of YbInCu{sub 4}: Direct Testing of Correlated Electron Models

    SciTech Connect

    Joyce, J.J.; Arko, A.J.; Sarrao, J.L.; Fisk, Z.

    1997-12-31

    The electronic properties of single crystal YbInCu{sub 4} have been investigated by means of high resolution photoelectron spectroscopy. A first order, isostructural phase transition for YbInCu{sub 4} at T{sub v}=42 K leads to changes in the Kondo temperature of more than an order of magnitude (27 K vs. 400 K). This phase transition and accompanying Kondo temperature change provide the most direct test of the single impurity model (SIM) to date. Particle hole symmetry allows the SIM to be used for Yb compounds as well as Ce heavy fermions with the great advantage that the predicted Kondo resonance is found on the occupied side of the spectral weight function for Yb materials and is thus directly observable in photoemission. The photoemission results are incongruous with the single impurity model predictions for temperature dependence, binding energy and 4f occupancy, encouraging a reevaluation of the single impurity model. The experiments were conducted using the PGM undulator and 4 meter NIM beamlines at SRC. The spectra were taken at photon energies of 40 eV and 90 eV and the combined energy resolution of the analyzer and monochromator was 45- 85 meV.

  6. Multi-Frequency Soliton Complex in Er/Yb-Doped Fiber Amplifier

    NASA Technical Reports Server (NTRS)

    Kang, Jin U.; Kim, Do-Hyun; Khurgin, Jacob B.; Akhmediev, Nail N.; Han, Haewook; Shaw, Harry; Day, John H. (Technical Monitor)

    2001-01-01

    We experimentally investigated presence of multi-frequency soliton complex that exist in high power Er/Yb-doped Fiber Amplifier. The complex with the spectral bandwidth in excess of 100 nm is bound by the Kerr nonlinearity and exhibit stable propagation.

  7. Inhibition of bacterial RNase P by aminoglycoside^arginine conjugates Timothy D. EubankaYb

    E-print Network

    Gopalan, Venkat

    Inhibition of bacterial RNase P by aminoglycoside^arginine conjugates Timothy D. EubankaYb , Roopa, a hexa-arginine derivative of neomycin (NeoR) and a tri-arginine derivative of gentamicin (R3G) were. Published by Elsevier Science B.V. All rights reserved. Key words: Aminoglycoside^arginine conjugate; RNase

  8. HACE1 mediated K27 ubiquitin linkage leads to YB-1 protein secretion.

    PubMed

    Palicharla, Vivek Reddy; Maddika, Subbareddy

    2015-12-01

    Ubiquitination is an important post-translational modification that is implicated in controlling almost every biological process by targeting cellular proteins to degradation. While the importance of ubiquitination in controlling the fate and the intracellular functions of various proteins was widely studied, its role in extracellular protein secretion has been unexplored so far. In this study, by using YB-1 (Y-box Binding protein 1) as a model protein, we showed that ubiquitination is required for its extracellular secretion. We also identified HACE1 as a specific E3 ligase that polyubiquitinates YB-1 through non-canonical K27 linked ubiquitin chains. Formation of these ubiquitin linkages on YB-1 is necessary for its interaction with Tumor Susceptibility Gene 101 (TSG101), a component of the Multi-Vesicular Body (MVB) pathway, which facilitates its secretion. Finally, we demonstrated that extracellular secreted YB-1 is a functional protein that acts to inhibit Transforming Growth Factor-Beta mediated epithelial to mesenchymal transition. In summary, we identified a novel functional role for non-canonical ubiquitin linkages in mediating protein secretion. PMID:26343856

  9. Ion diffusion at the bonding interface of undoped YAG/Yb:YAG composite ceramics

    NASA Astrophysics Data System (ADS)

    Fujioka, Kana; Sugiyama, Akira; Fujimoto, Yasushi; Kawanaka, Junji; Miyanaga, Noriaki

    2015-08-01

    Cation diffusion across a boundary between ytterbium (Yb)-doped and undoped yttrium aluminum garnet (YAG) ceramics was examined by electron microprobe analysis (EPMA). Polished Yb:YAG and undoped YAG ceramics were bonded by surface treatment with argon fast atom beam, and then heat-treated at 1400 or 1600 °C for 50 h or at 1400 °C for 10 h under vacuum. We obtained EPMA mapping images of the bonded samples that clearly showed the bulk and grain-boundary diffusion of Y and Yb ions. The number density profiles showed that the total diffusion distances of Yb and Y ions were almost equal and approximately 2 and 15 ?m at 1400 and 1600 °C, respectively, and the dependence of diffusion distance on heating time was weak. The diffusion curves were well modeled by Harrison type B kinetics including bulk and grain-boundary diffusion. In addition, it was found that Si ions added to the samples as a sintering aid might be segregated at the grain boundary by heat treatment, and diffused only along grain boundaries.

  10. Magnetic ground state at the ytterbium site in YbNiAl4 Banchachit Saensunon,1

    E-print Network

    Ryan, Dominic

    are presented for polycrystalline YbNiAl4. Although the low temperature specific heat data are consistent. There is no evidence for magnetic order down to the base temperature of 2 K. However, the low temperature inverse. The low temperature inverse suscepti

  11. Frequency ratio measurement of 171Yb and 87Sr optical lattice clocks

    E-print Network

    Akamatsu, Daisuke; Inaba, Hajime; Hosaka, Kazumoto; Tanabe, Takehiko; Onae, Atsushi; Hong, Feng-Lei

    2014-01-01

    The frequency ratio of the 1S0(F=1/2)-3P0(F=1/2) clock transition in 171Yb and the 1S0(F=9/2)-3P0(F=9/2) clock transition in 87Sr is measured by an optical-optical direct frequency link between two optical lattice clocks. We determined the ratio (\

  12. Synthesis, structural and magnetic characterization of polycrystalline Yb2Ti2O7

    NASA Astrophysics Data System (ADS)

    Juyal, Abhishek; Mukhopadhyay, Soumik; Barman, Kalyani

    2015-06-01

    The discovery of the Yb2Ti2O7 is among the most significant findings in magnetic materials in over a decade. The spin-ice model is based on an ingenious analogy to Pauling's model of geometrical frustration in water ice, which is confirmed by various experiments. Here we present the characteristics of Yb2Ti2O7 studied by X-ray diffraction and magnetic measurements. Polycrystalline sample of Yb2Ti2O7 was prepared by sol-gel synthesis followed by thermal annealing at 1400 ° C for 36 hours. We calculated the change in the magnetic entropy from isothermal magnetization curves. We find no evidence of plateau at Pauling residual entropy. Temperature dependence of the inverse magnetic susceptibility reveals Curie-Wiess temperature ?cw = 156mK and paramagnetic moment ?eff ? 3.58 µB, indicating weak ferromagnetic interaction. Using Arrott plot we conclude that Yb2Ti2O7 possibly enters a magnetic ground state below Tc~140 mK.

  13. Large magnetocaloric effect and adiabatic demagnetization refrigeration with YbPt2Sn

    NASA Astrophysics Data System (ADS)

    Jang, Dongjin; Gruner, Thomas; Steppke, Alexander; Mitsumoto, Keisuke; Geibel, Christoph; Brando, Manuel

    2015-10-01

    Adiabatic demagnetization is currently gaining strong interest in searching for alternatives to 3He-based refrigeration techniques for achieving temperatures below 2 K. The main reasons for that are the recent shortage and high price of the rare helium isotope 3He. Here we report the discovery of a large magnetocaloric effect in the intermetallic compound YbPt2Sn, which allows adiabatic demagnetization cooling from 2 K down to 0.2 K. We demonstrate this with a home-made refrigerator. Other materials, for example, paramagnetic salts, are commonly used for the same purpose but none of them is metallic, a severe limitation for low-temperature applications. YbPt2Sn is a good metal with an extremely rare weak magnetic coupling between the Yb atoms, which prevents them from ordering above 0.25 K, leaving enough entropy free for use in adiabatic demagnetization cooling. The large volumetric entropy capacity of YbPt2Sn guarantees also a good cooling power.

  14. 15 November 2011 15:26 YB2012[001-090].tex 52 Darwin's bark spider

    E-print Network

    Agnarsson, Ingi

    15 November 2011 15:26 YB2012[001-090].tex 52 Darwin's bark spider Future outlook. It is expected, combinatorial associations and metabolic functions, Biochem. J., 416:161­177, 2008. Darwin's bark spider Spiders dense orb web (left), and a river-crossing web (right) of a female Darwin's bark spider, Caerostris

  15. Growth and spectral characteristics of Yb 3+-doped LiLa(MoO 4) 2 crystal

    NASA Astrophysics Data System (ADS)

    Huang, Xinyang; Lin, Zhoubin; Zhang, Lizhen; Wang, Guofu

    2007-08-01

    A Yb 3+-doped LiLa(MoO 4) 2 crystal with dimension of ?20×35 mm 3 has been grown by the Czochralski method. The polarized optical absorption and emission spectra of the crystal have been investigated. The Yb 3+:LiLa(MoO 4) 2 crystal has a broad absorption FWHM of 29 nm at 977 nm. The absorption cross-sections of the crystals are 1.93×10 -20 cm 2 and 1.56×10 -20 cm 2 at 977 nm for ?- and ?-polarization, respectively. The emission cross-sections of the crystals are 1.53×10 -20 and 1.00×10 -20 cm 2 at 1011 nm for ?- and ?-polarization, respectively. The radiative lifetime and fluorescence lifetime of the Yb 3+:LiLa(MoO 4) 2 crystal are 391 and 636 ?s, respectively. The laser performance parameters ?min, Ipast, and Imin of the crystal have been calculated. The investigated results shown the Yb 3+:LiLa(MoO 4) 2 crystal is expected as a potential solid-state laser crystal materials.

  16. Quantum cutting mechanism in NaYF4:Tb3, Yb3 Qianqian Duan,1

    E-print Network

    Cao, Wenwu

    Quantum cutting mechanism in NaYF4:Tb3, Yb3 Qianqian Duan,1 Feng Qin,1,2 Zhiguo Zhang,1); published February 8, 2012 A quantum cutting mechanism for the sublinear near-IR power dependence property analyzed by Monte Carlo simulation method and the cooperative quantum cutting mechanism was de- monstrated

  17. Thermal, magnetic and electronic properties of non-centrosymmetric YbPt?B.

    PubMed

    Khan, R T; Kneidinger, F; Hilscher, G; Sidorenko, A; Sologub, O; Michor, H; Bauer, E; Rogl, P; Giester, G

    2015-04-15

    Ternary YbPt2B crystallizes in the non-centrosymmetric hexagonal CePt2B-type structure (space group P6(2)22). Electrical resistivity, specific heat and magnetic measurements reveal a magnetic instability at 5.6 K. Furthermore, a spin-reorientation of presumably a ferromagnetic type occurs around 1.5 K. The behaviour at low temperature is governed by a rather weak Kondo effect, T(K) ? 1 K, in the presence of strong crystalline electric field splitting, with a doublet ground state. Besides, the complex magnetic behaviour presumably results from a Dzyaloshinskii-Moriya interaction triggered by the absence of inversion symmetry in the crystal structure. Scaling according to the de Gennes factor traces back magnetic ordering in YbPt2B to the Rudermann-Kittel-Kasuya-Yoshida (RKKY) interaction and the smooth evolution of the lattice constants and the unit cell volume of REPt2B (RE = rare earths) refers to the 4f(13) electronic configuration of Yb in YbPt2B. PMID:25786543

  18. High-energy, kHz, picosecond hybrid Yb-doped chirped-pulse amplifier.

    PubMed

    Chang, Chun-Lin; Krogen, Peter; Hong, Kyung-Han; Zapata, Luis E; Moses, Jeffrey; Calendron, Anne-Laure; Liang, Houkun; Lai, Chien-Jen; Stein, Gregory J; Keathley, Phillip D; Laurent, Guillaume; Kärtner, Franz X

    2015-04-20

    We report on a diode-pumped, hybrid Yb-doped chirped-pulse amplification (CPA) laser system with a compact pulse stretcher and compressor, consisting of Yb-doped fiber preamplifiers, a room-temperature Yb:KYW regenerative amplifier (RGA), and cryogenic Yb:YAG multi-pass amplifiers. The RGA provides a relatively broad amplification bandwidth and thereby a long pulse duration to mitigate B-integral in the CPA chain. The ~1030-nm laser pulses are amplified up to 70 mJ at 1-kHz repetition rate, currently limited by available optics apertures, and then compressed to ~6 ps with high efficiency. The near-diffraction-limited beam focusing quality is demonstrated with M(x)(2) = 1.1 and M(y)(2) = 1.2. The shot-to-shot energy fluctuation is as low as ~1% (rms), and the long-term energy drift and beam pointing stability for over 8 hours measurement are ~3.5% and <6 ?rad (rms), respectively. To the best of our knowledge, this hybrid laser system produces the most energetic picosecond pulses at kHz repetition rates among rod-type laser amplifiers. With an optically synchronized Ti:sapphire seed laser, it provides a versatile platform optimized for pumping optical parametric chirped-pulse amplification systems as well as driving inverse Compton scattered X-rays. PMID:25969056

  19. Mitochondrial proton leak and the uncoupling protein 1 homologues J.A. Stuart aYb

    E-print Network

    Stuart, Jeffrey A.

    Review Mitochondrial proton leak and the uncoupling protein 1 homologues J.A. Stuart aYb , S 2000 Abstract Mitochondrial proton leak is the largest single contributor to the standard metabolic rate (SMR) of a rat, accounting for about 20% of SMR. Yet the mechanisms by which proton leak occurs

  20. Inhibited local thermal effect in upconversion luminescence of YVO?:Yb³?, Er³? inverse opals.

    PubMed

    Zhu, Yongsheng; Xu, Wen; Zhang, Hanzhuang; Xu, Sai; Wang, Yunfeng; Dai, Qinlin; Dong, Biao; Xu, Lin; Song, Hongwei

    2012-12-31

    Upconversion Luminescence (UCL) of YVO?:Yb³?, Er³? inverse opal photonic crystals (IOPCs) was investigated in contrast to the references under the excitation of a 980-nm laser diode. Besides the traditional modification on UCL and dynamics, it is significant to observe that in the IOPCs the temperature quenching and local thermal effect was greatly suppressed. PMID:23388795

  1. Large magnetocaloric effect and adiabatic demagnetization refrigeration with YbPt2Sn.

    PubMed

    Jang, Dongjin; Gruner, Thomas; Steppke, Alexander; Mitsumoto, Keisuke; Geibel, Christoph; Brando, Manuel

    2015-01-01

    Adiabatic demagnetization is currently gaining strong interest in searching for alternatives to (3)He-based refrigeration techniques for achieving temperatures below 2?K. The main reasons for that are the recent shortage and high price of the rare helium isotope (3)He. Here we report the discovery of a large magnetocaloric effect in the intermetallic compound YbPt2Sn, which allows adiabatic demagnetization cooling from 2?K down to 0.2?K. We demonstrate this with a home-made refrigerator. Other materials, for example, paramagnetic salts, are commonly used for the same purpose but none of them is metallic, a severe limitation for low-temperature applications. YbPt2Sn is a good metal with an extremely rare weak magnetic coupling between the Yb atoms, which prevents them from ordering above 0.25?K, leaving enough entropy free for use in adiabatic demagnetization cooling. The large volumetric entropy capacity of YbPt2Sn guarantees also a good cooling power. PMID:26493166

  2. Contribution of Eu ions on the precipitation of silver nanoparticles in Ag-Eu co-doped borate glasses

    SciTech Connect

    Jiao, Qing; Qiu, Jianbei; Zhou, Dacheng; Xu, Xuhui

    2014-03-01

    Graphical abstract: - Highlights: • Silver nanoparticles are precipitated from the borate glasses during the melting process without any further heat treatment. • The reduction of Eu{sup 3+} ions to Eu{sup 2+} ions is presented in this material. • The intensity of Ag{sup +} luminescence. • The introduction of Eu ions accelerated the reaction between Eu{sup 2+} ions and silver ions inducing the silver clusters formation. - Abstract: Ag{sup +} doped sodium borate glasses with different Eu ions concentration were prepared by the melt-quenching method. The absorption at about 410 nm which was caused by the surface plasmon resonance (SPR) of Ag nanoparticles (NPs) is promoted with increasing of Eu ions concentration. Meanwhile, the luminescent spectra showed that the emission intensity of Ag{sup +} decreased while that of the Ag aggregates increased simultaneously. The results indicated that the Ag ions intend to form the high-polymeric state such as Ag aggregates and nanoparticles with increasing of europium ions. Owing to the self-reduction of Eu{sup 3+} to Eu{sup 2+} in our glass system, it revealed that Ag{sup +} has been reduced by the neighboring Eu{sup 2+} which leads to the formation of Ag aggregates and the precipitation of Ag NPs in the matrix. In addition, energy transfer (ET) process from Ag{sup +}/Ag aggregates to the Eu{sup 3+} was investigated for the enhancement of Eu{sup 3+} luminescence.

  3. Induced spin-polarization of EuS at room temperature in Ni/EuS multilayers

    SciTech Connect

    Poulopoulos, P.; Goschew, A.; Straub, A.; Fumagalli, P.; Kapaklis, V.; Wolff, M.; Delimitis, A.; Wilhelm, F.; Rogalev, A.; Pappas, S. D.

    2014-03-17

    Ni/EuS multilayers with excellent multilayer sequencing are deposited via e-beam evaporation on the native oxide of Si(100) wafers at 4?×?10{sup ?9} millibars. The samples have very small surface and interface roughness and show sharp interfaces. Ni layers are nanocrystalline 4–8?nm thick and EuS layers are 2–4?nm thick and are either amorphous or nanocrystalline. Unlike for Co/EuS multilayers, all Eu ions are in divalent (ferromagnetic) state. We show a direct antiferromagnetic coupling between EuS and Ni layers. At room temperature, the EuS layers are spin-polarized due to the proximity of Ni. Therefore, Ni/EuS is a candidate for room-temperature spintronics applications.

  4. Framing the EU as Common Project vs. Common Heritage: Effects on Attitudes Towards the EU Deepening and Widening.

    PubMed

    La Barbera, Francesco

    2015-01-01

    The present study investigated the effects of framing the European Union (EU) as a common project vs. a common heritage on participants' attitude towards EU integration (Experiment 1) and EU enlargement (Experiment 2). An additional aim was exploring whether the different frames affected the strength of identification with the EU, and if the framing effect on attitudes was mediated by participants' identification with the EU and/or by their message evaluation (Experiment 3). Results showed that a common project-based frame was more effective than a common heritage-based frame in promoting positive attitude toward EU integration and enlargement, as well as participants' identification with the EU, which mediated the framing effect on both attitudes; the mediation of participants' message evaluation was not significant. The procedure of the last experiment was replicated on a British sample (Experiment 4), showing a similar pattern of results. PMID:25898068

  5. TM digital image products for applications. [computer compatible tapes

    NASA Technical Reports Server (NTRS)

    Barker, J. L.; Gunther, F. J.; Abrams, R. B.; Ball, D.

    1984-01-01

    The image characteristics of digital data generated by LANDSAT 4 thematic mapper (TM) are discussed. Digital data from the TM resides in tape files at various stages of image processing. Within each image data file, the image lines are blocked by a factor of either 5 for a computer compatible tape CCT-BT, or 4 for a CCT-AT and CCT-PT; in each format, the image file has a different format. Nominal geometric corrections which provide proper geodetic relationships between different parts of the image are available only for the CCT-PT. It is concluded that detector 3 of band 5 on the TM does not respond; this channel of data needs replacement. The empty bin phenomenon in CCT-AT images results from integer truncations of mixed-mode arithmetric operations.

  6. Hydrological planning studies using Landsat-4 Thematic Mapper (TM)

    NASA Technical Reports Server (NTRS)

    Gervin, J. C.; Mulligan, P. J.; Lu, Y. C.; Marcell, R. F.

    1984-01-01

    NASA, in cooperation with the U.S. Army Corps of Engineers, is evaluating the capabilities of Landsat 4 Thematic Mapper (TM) data for environmental and hydrological applications. Attention is given to the results of studies conducted at the Clinton River Basin in Michigan and the eastern shore of the Chesapeake Bay in Maryland. In the former, the evaluation conducted was for the band combinations: (1) 2, 3, and 4; (2) 3, 4, and 5; (3) 3, 4, 5, and 6; and (4) all seven bands. In the latter case, Multispectral Scanner (MSS) and TM data were classified for combinations (1), (3) and (4). Wetland classification accuracy for the 7-band TM data in this study was found to be 9 percent higher than with MSS data, allowing more reliable and accurate monitoring.

  7. 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.

  8. Energy gap engineering of polymeric carbon nitride nanosheets for matching with NaYF4:Yb,Tm: enhanced visible-near infrared photocatalytic activity.

    PubMed

    Li, Xuefeng; Ren, Hao; Zou, Zhijuan; Sun, Jiaojiao; Wang, Jingyu; Liu, Zhihong

    2016-01-11

    Molecularly grafted carbon nitride (CN) nanosheets, matching well with the emission energy of upconversion phosphors (UCPs), were acquired for the first time. As a result of energy gap engineering, the assembled composites successfully realized the full use of visible-NIR light and afforded much higher activity than any CN- or UCP-based photocatalyst ever reported. PMID:26462975

  9. Measurements of total atomic attenuation cross sections of Tm, Yb, Lu, Hf, Ta, W, Re and Os Elements at 122keV and 136keV

    SciTech Connect

    Kaya, N.; Tirasoglu, E.; Apaydin, G.; Kobya, A. I.

    2007-04-23

    The aim of this study was to measure the total atomic attenuation cross sections ({sigma}t) in eighth elements (69{<=}Z{<=}76) at 122 keV and 136 keV. The experimental values of the cross sections were determined using the transmission geometry. Measurements have been performed using an annular source (Co-57) and Ultra-LEGe solid state detector with a resolution of 150 eV at 5.9 keV. Experimental results have been compared with theoretically calculated values and other available experimental results. Good agreement was observed among the experimental, theoretical and other experimental values.

  10. Enhancing upconversion emissions of NaTm0.02YbxY0.98xF4 nanocrystals through increasing Yb3

    E-print Network

    Cao, Wenwu

    ,c,nn a Department of Physics, Harbin Institute of Technology, 150001 Harbin, P.R. China b Laboratory of Sono- and photo- theranostic Technology, Harbin Institute of Technology, 150001 Harbin, P.R. China c Materials with size about 10 nm, the intensities of near infrared (800 nm) and blue (470 nm) upconversion (UC

  11. 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 ?m, 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 ?m, HT @ 0.97 ?m) and curved (r = 150mm) output coupler with a reflectivity of ˜ 97% @ 1.01 - 1.09 ?m. 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%.

  12. High thermoelectric performance of In, Yb, Ce multiple filled CoSb{sub 3} based skutterudite compounds

    SciTech Connect

    Ballikaya, Sedat; Department of Physics, University of Michigan, Ann Arbor, MI, 48109 ; Uzar, Neslihan; Yildirim, Saffettin; Salvador, James R.; Uher, Ctirad

    2012-09-15

    Filling voids with rare earth atoms is an effective way to lowering thermal conductivity which necessarily enhances thermoelectric properties of skutterudite compounds. Yb atom is one of the most effective species among the rare earth atoms for filling the voids in the skutterudite structure due to a large atomic mass, radius and it is intermediate valence state. In this work, we aim to find the best filling partners for Yb using different combinations of Ce and In as well as to optimize actual filling fraction in order to achieve high values of ZT. The traditional method of synthesis relying on melting-annealing and followed by spark plasma sintering was used to prepare all samples. The thermoelectric properties of four samples of Yb{sub 0.2}In{sub 0.2}Co{sub 4}Sb{sub 12}, Yb{sub 0.2}Ce{sub 0.15}Co{sub 4}Sb{sub 12}, Yb{sub 0.2}Ce{sub 0.15}In{sub 0.2}Co{sub 4}Sb{sub 12}, and Yb{sub 0.3}Ce{sub 0.15}In{sub 0.2}Co{sub 4}Sb{sub 12} (nominal) were examined based on the Seebeck coefficient, electrical conductivity, thermal conductivity, and Hall coefficient. Hall coefficient and Seebeck coefficient signs confirm that all samples are n-type skutterudite compounds. Carrier density increases with the increasing Yb+Ce content. A high power factor value of 57.7 {mu}W/K{sup 2}/cm for Yb{sub 0.2}Ce{sub 0.15}Co{sub 4}Sb{sub 12} and a lower thermal conductivity value of 2.82 W/m/K for Yb{sub 0.2}Ce{sub 0.15}In{sub 0.2}Co{sub 4}Sb{sub 12} indicate that small quantities of Ce with In may be a good partner to Yb to reduce the thermal conductivity further and thus enhance the thermoelectric performance of skutterudites. The highest ZT value of 1.43 was achieved for Yb{sub 0.2}Ce{sub 0.15}In{sub 0.2}Co{sub 4}Sb{sub 12} triple-filled skutterudite at 800 K. - Graphical abstract: Thermoelectric figure of merit of Yb{sub x}In{sub y}Ce{sub z}Co{sub 4}Sb{sub 12} (0{<=}x,y,z{<=}0.18 actual) compounds versus temperature. Highlights: Black-Right-Pointing-Pointer TE properties of Yb,In,Ce multiple-filled Yb{sub x}In{sub y}Ce{sub z}Co{sub 4}Sb{sub 12} skutterudites were investigated. Black-Right-Pointing-Pointer Thermal conductivity is strongly suppressed by multiple filling of Yb, Ce and In. Black-Right-Pointing-Pointer Small amounts of Ce and In with Yb are beneficial for the enhancement of TE performance. Black-Right-Pointing-Pointer The highest ZT=1.43 was achieved with Yb{sub 0.07}In{sub 0.094}Ce{sub 0.065}Co{sub 4}Sb{sub 11.92} at 800 K.

  13. Fiber-optic thermometer application of thermal radiation from rare-earth end-doped SiO{sub 2} fiber

    SciTech Connect

    Katsumata, Toru Morita, Kentaro; Komuro, Shuji; Aizawa, Hiroaki

    2014-08-15

    Visible light thermal radiation from SiO{sub 2} glass doped with Y, La, Ce, Pr, Nd, Eu, Tb, Dy, Ho, Er, Tm, Yb, and Lu were studied for the fiber-optic thermometer application based on the temperature dependence of thermal radiation. Thermal radiations according to Planck's law of radiation are observed from the SiO{sub 2} fibers doped with Y, La, Ce, Pr, Eu, Tb, and Lu at the temperature above 1100 K. Thermal radiations due to f-f transitions of rare-earth ions are observed from the SiO{sub 2} fibers doped with Nd, Dy, Ho, Er, Tm, and Yb at the temperature above 900 K. Peak intensities of thermal radiations from rare-earth doped SiO{sub 2} fibers increase sensitively with temperature. Thermal activation energies of thermal radiations by f-f transitions seen in Nd, Dy, Ho, Er, Tm, and Yb doped SiO{sub 2} fibers are smaller than those from SiO{sub 2} fibers doped with Y, La, Ce, Pr, Eu, Tb, and Lu. Thermal radiation due to highly efficient f-f transitions in Nd, Dy, Ho, Er, Tm, and Yb ions emits more easily than usual thermal radiation process. Thermal radiations from rare-earth doped SiO{sub 2} are potentially applicable for the fiber-optic thermometry above 900 K.

  14. SPACEWAY(TM) Providing Afordable and Versatile Telecommunication Solutions

    NASA Technical Reports Server (NTRS)

    Fitzpatrick, Edward James

    1996-01-01

    This paper presents a summary description of SPACEWAY(TM), a network of Ka band geostationary satellites being developed by Hughes Communications, Inc. to provide worldwide interactive telecommunications services to small, low cost user terminals. By the end of this decade SPACEWAY(TM), using relatively few satellites and tightly focused spot beams, will provide affordable interactive 'bandwidth on demand' communication services on a global basis to consumer and commercial end users. This paper describes the system concept, details the space and ground segment characteristics, and discusses communication links.

  15. Preliminary study of Kelso Dunes using AVIRIS, TM, and AIRSAR

    NASA Technical Reports Server (NTRS)

    Xu, Pung; Blumberg, Dan G.; Greeley, Ronald

    1995-01-01

    Remote sensing of sand dunes helps in the understanding of aeolian process and provides important information about the regional geologic history, environmental change, and desertification. Remotely sensed data combined with field studies are valuable in studying dune morphology, regional aeolian dynamics, and aeolian depositional history. In particular, active and inactive sands of the Kelso Dunes have been studied using landsat TM and AIRSAR. In this report, we describe the use of AVIRIS data to study the Kelso dunes and to compare the AVIRIS information with that from TM and AIRSAR.

  16. TM digital image products for applications. [computer compatible tapes

    NASA Technical Reports Server (NTRS)

    Barker, J. L.; Gunther, F. J.; Abrams, R. B.; Ball, D.

    1984-01-01

    Computer compatible tapes (CCTs) of LANDSAT 4 thematic mapper (TM) digital image products are compared and reviewed. The following tape formats are discussed: (1) raw band-sequential data (CCT-BT); (2) calibrated data (CCT-AT); and (3) geometrically resampled data (CCT-PT). Each format represents different steps in the process of producing fully corrected TM data. The CCT-BT images are uncorrected radiometrically or geometrically, CCT-AT data are radiometrically calibrated, and CCT-PT images are both radiometrically and geometrically corrected.

  17. Enhanced rock discrimination using Landsat-5 Thematic Mapper (TM) data

    NASA Technical Reports Server (NTRS)

    Blodget, H. W.; Andre, C. G.; Marcell, R. F.

    1985-01-01

    The application of TM data to rock discrimination is discussed. Sixteen specific terrains derived from geologic maps are examined on TM images of the Arabian shield obtained on Apr. 14, 1984; visual enhancement procedures are applied to the images. The rock types observed in the test site are described; the major sedimentary formations in the test area are laterite and sandstone. The data reveal that the layered rocks in the outcrop consist of a variety of metamorphosed volcanics, metamorphosed sediments, and amphibolite, and the intrusive complex is composed of several classes of mafic and acidic rocks.

  18. 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 and in Ba/Ce (>8) relative to the OIV field. There are some exceptions, also, for IAV that plot outside the IAV field. The values of Ce/Yb in Mariana Islands samples, for example, are exceptionally low for the IAV (Ce/Yb <5 with many samples <2). Examples of two cross-chain Kasuga Islands, however, have average, values of Ce/Yb considerably greater than for any other Mariana Islands data, and individual samples extend from within the IAV field into the OIV field, which may indicate a mixture of IAV and OIV sources (rather than involvement of a hotspot, these island volcanics have been interpreted as magma of OIV entrapped "plums" in an IAV "pudding" by Stern et al., 1993). Not Surprisingly, continental are volcanics, (CAV) are generally similar to IAV, but with somewhat greater dispersion in Ce/Yb, perhaps representing a larger contribution of continental materials to the volcanics. Continental rift volcanics (CRV) are complex. The Antarctic rift data fall in the OIV field, and clearly define a hotspot origin for the rift with little contamination in the continental lithosphere, but most CRV data fall in the IAV field (Rio Grande rift tholeiites, Yellowstone Plateau basalts, Columbia River basalts. East African rift hasalts). The Yellowstone basalt samples judged to be least crustally contaminated from other considerations (e.g., through Pb and Sr isotopes) approach closest to the OIV or hotspot field in the Ce/Yb vs. Ba/Ce plot, compatible with a hotspot origin with variable continental lithosphere interactions. The data from the Rio Grande rift have no such trend in Ce/Yb vs. Ba/Ce. Other trace element and isotopic data are suggestive of a different kind of origin, perhaps melting in the continental lithosphere from pressure release or other causes as suggested in the literature. Carbonatites, kimberlites, and ultrap

  19. 78 FR 52804 - mPower\\TM\\ Design-Specific Review Standard

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-08-26

    ...COMMISSION [NRC-2013-0089] mPower\\TM\\ Design-Specific Review Standard AGENCY: Nuclear Regulatory Commission. ACTION: Design-Specific Review Standard (DSRS) for the mPower\\TM\\ Design; re-opening of comment...

  20. 78 FR 59363 - New Agency Information Collection Activity Under OMB Review: TSA Pre?TM

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-09-26

    ...who TSA determines are ineligible for the TSA Pre[check] TM Application Program will continue to be screened at airport security checkpoints according to TSA standard screening protocols. TSA Pre[check] TM will enhance aviation security...