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1

Physical properties of the R3Pt23Si11 compounds with volatile rare earth: Sm, Eu, Tm and Yb  

NASA Astrophysics Data System (ADS)

The new R3Pt23Si11 series, where R is a rare earth, has been completed with the synthesis of three new compounds with volatile rare earth: R=Eu, Sm, and Tm. The studies of their physical properties have been performed along with those of the Yb3Pt23Si11 compound. The X-ray powder diffraction patterns confirm that they all crystallize in the same face-centered cubic structure, space group Fm 3 bar m, as the rest of the series. The refinements of the diffraction patterns show an anomalously high lattice parameter in Eu3Pt23Si11 and Yb3Pt23Si11, indicating a divalent valence state for Eu and Yb. This 2+ valence state for Eu and Yb ions is confirmed by the magnetic measurements. A ferromagnetic order is observed at TC=5.540.07 K and 10.120.07 K in Eu3Pt23Si11 and Sm3Pt23Si11 respectively. In Tm3Pt23Si11 no magnetic order is found down to 0.36 K while Yb3Pt23Si11 reveals a diamagnetic behavior. At low temperatures the spontaneous moment, Ms, in Eu3Pt23Si11 is in agreement with a L=0, S=7/2 state for the Eu2+ ion. On the contrary in Sm3Pt23Si11, Ms is far below the 0.714?B expected for the saturated moment of the Sm3+ in the J=7/2 ground state multiplet.

Opagiste, C.; Barbier, C.; Haettel, R.; Galra, R. M.

2015-03-01

2

White light upconversion in Yb-sensitized (Tm, Ho)-doped KLu(WO4)2 nanocrystals: the effect of Eu incorporation.  

PubMed

Monoclinic Yb-sensitized (Tm, Ho)-doped KLu(WO4)2 nanocrystals of ~100 nm size have been synthesized by the modified Pechini sol-gel method. Their diode laser near-infrared (~980 nm) excited upconversion emission properties have been characterized at power densities in the range 30-355 W cm(-2). Bright white light composed of blue ~475 nm, green ~540 nm, and red ~650 nm emissions, corresponding to Tm(3+ 1)G4 ? (3)H6, Ho(3+ 5)S2, (5)F4 ? (5)I8, and Ho(3+ 5)F5 ? (5)I8 electronic transitions, respectively, was generated by adjusting the Yb, Tm, and Ho contents in KLu(WO4)2 nanocrystalline samples. Chromaticity coordinates of the emitted white light can be tuned by modifying the excitation power density. The effect of Tm and Ho on the luminescence dynamics has been described by analyzing the upconverted emission intensity dependence on the excitation power, as well as from Stokes and decay time measurements. The effect on upconversion properties of further codoping with Eu in these (Tm, Ho, Yb)-doped KLu(WO4)2 nanocrystals has also been studied. PMID:24322200

Barrera, E W; Pujol, M C; Carvajal, J J; Mateos, X; Sol, Rosa; Massons, J; Speghini, A; Bettinelli, M; Cascales, C; Aguil, M; Daz, F

2014-01-28

3

Multifunctional ScF3:Ln3+ (Ln = Tb, Eu, Yb, Er, Tm and Ho) nano/microcrystals: hydrothermal/solvothermal synthesis, electronic structure, magnetism and tunable luminescence properties  

NASA Astrophysics Data System (ADS)

A facile, hydrothermal/solvothermal route has been developed to synthesize a series of multifunctional lanthanide ion (Tb3+, Eu3+, Yb3+, Tm3+, Er3+ and Ho3+)-activated ScF3 nanocrystals. The morphology and size of ScF3 can be tuned in a controlled manner by altering the additives and volume ratios of H2O : EtOH in the initial solution. Under ultraviolet (UV), vacuum ultraviolet (VUV) or low-voltage electron-beam excitation, the as-obtained Tb3+, Eu3+ codoped ScF3 product exhibits multicolor photoluminescence (PL) and cathodoluminescence (CL), and possible luminescence mechanisms are discussed. Moreover, under 980 nm excitation, upconversion (UC) emissions have been achieved in Yb3+-Er3+, Yb3+-Tm3+, and Yb3+-Ho3+ codoped ScF3. Ferromagnetic property of ScF3 is detected due to the nanocrystal defects. The results obtained indicate that the lanthanide ion-doped ScF3 nanocrystals exhibit multicolor UV/VUV PL, CL, and UC luminescence as well as ferromagnetic properties. Thus, they may have potential applications in PL areas, field emission display devices, bioseparation and magnetic resonance imaging.A facile, hydrothermal/solvothermal route has been developed to synthesize a series of multifunctional lanthanide ion (Tb3+, Eu3+, Yb3+, Tm3+, Er3+ and Ho3+)-activated ScF3 nanocrystals. The morphology and size of ScF3 can be tuned in a controlled manner by altering the additives and volume ratios of H2O : EtOH in the initial solution. Under ultraviolet (UV), vacuum ultraviolet (VUV) or low-voltage electron-beam excitation, the as-obtained Tb3+, Eu3+ codoped ScF3 product exhibits multicolor photoluminescence (PL) and cathodoluminescence (CL), and possible luminescence mechanisms are discussed. Moreover, under 980 nm excitation, upconversion (UC) emissions have been achieved in Yb3+-Er3+, Yb3+-Tm3+, and Yb3+-Ho3+ codoped ScF3. Ferromagnetic property of ScF3 is detected due to the nanocrystal defects. The results obtained indicate that the lanthanide ion-doped ScF3 nanocrystals exhibit multicolor UV/VUV PL, CL, and UC luminescence as well as ferromagnetic properties. Thus, they may have potential applications in PL areas, field emission display devices, bioseparation and magnetic resonance imaging. Electronic supplementary information (ESI) available: The UV/VUV/CL spectra of nanocrystal defects in ScF3 and the calculation of electron penetration depths. See DOI: 10.1039/c4nr00512k

Han, Lili; Wang, Yuhua; Guo, Linna; Zhao, Lei; Tao, Ye

2014-05-01

4

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

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.

Gao, Yu, E-mail: gaoy777@126.com [College of Materials Science and Engineering, Shenyang University of Chemical Technology, Shenyang 110142 (China)] [College of Materials Science and Engineering, Shenyang University of Chemical Technology, Shenyang 110142 (China); Gong, Jian [Key Laboratory of Polyoxometalate Science of Ministry of Education, Department of Chemistry, Northeast Normal University, Changchun, Jilin 130024 (China)] [Key Laboratory of Polyoxometalate Science of Ministry of Education, Department of Chemistry, Northeast Normal University, Changchun, Jilin 130024 (China); Fan, Miaomiao [Department of Medical Pharmaceutical, Shenyang Chemical Industry School, Shenyang 110142 (China)] [Department of Medical Pharmaceutical, Shenyang Chemical Industry School, Shenyang 110142 (China); Fang, Qinghong; Wang, Na; Han, Wenchi; Xu, Zhenhe [College of Materials Science and Engineering, Shenyang University of Chemical Technology, Shenyang 110142 (China)] [College of Materials Science and Engineering, Shenyang University of Chemical Technology, Shenyang 110142 (China)

2012-12-15

5

Multifunctional ScF3:Ln3+ (Ln = Tb, Eu, Yb, Er, Tm and Ho) nano/microcrystals: hydrothermal/solvothermal synthesis, electronic structure, magnetism and tunable luminescence properties.  

PubMed

A facile, hydrothermal/solvothermal route has been developed to synthesize a series of multifunctional lanthanide ion (Tb(3+), Eu(3+), Yb(3+), Tm(3+), Er(3+) and Ho(3+))-activated ScF3 nanocrystals. The morphology and size of ScF3 can be tuned in a controlled manner by altering the additives and volume ratios of H2O?:?EtOH in the initial solution. Under ultraviolet (UV), vacuum ultraviolet (VUV) or low-voltage electron-beam excitation, the as-obtained Tb(3+), Eu(3+) codoped ScF3 product exhibits multicolor photoluminescence (PL) and cathodoluminescence (CL), and possible luminescence mechanisms are discussed. Moreover, under 980 nm excitation, upconversion (UC) emissions have been achieved in Yb(3+)-Er(3+), Yb(3+)-Tm(3+), and Yb(3+)-Ho(3+) codoped ScF3. Ferromagnetic property of ScF3 is detected due to the nanocrystal defects. The results obtained indicate that the lanthanide ion-doped ScF3 nanocrystals exhibit multicolor UV/VUV PL, CL, and UC luminescence as well as ferromagnetic properties. Thus, they may have potential applications in PL areas, field emission display devices, bioseparation and magnetic resonance imaging. PMID:24759954

Han, Lili; Wang, Yuhua; Guo, Linna; Zhao, Lei; Tao, Ye

2014-06-01

6

Tm3+ and Yb3+ in TmXO4 and Yb3+ in YbXO4 (X = from 169Tm and 170Yb Mssbauer measurements  

E-print Network

.70C - 76.83 1. Introduction. The rare earth compounds crystallizing in the zircon structure have been+ in the corresponding matrix. Spin-spin relaxation rates were measured in the paramagnetic YbXO4 and the origin of the rate in YbVO4 is discussed. Magnetic ordering is observed in YbVO4 below about 0.15 K and also in YbPO4

Paris-Sud XI, Université de

7

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

NASA Astrophysics Data System (ADS)

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

Grigorjeva, L.; Smits, K.; Millers, D.; Jankovi?a, Dz

2015-03-01

8

Synthesis and upconversion luminescence in highly crystalline YOF:Yb3+/Er3+ and Yb3+/Tm3+ microboxes  

NASA Astrophysics Data System (ADS)

Highly crystalline YOF:Ln3+ (Ln = Yb, Er, Tm) microboxes were successfully synthesized for the first time by using a mixed NaNO3-KNO3 flux cooling method at a holding temperature of 600 C for 2 h in air. The results indicated that the as-obtained products belonged to tetragonal system and exhibited microboxes morphology with side lengths of 0.5-2 ?m. The upconversion luminescence properties of as-prepared YOF:Yb3+/Er3+ and YOF:Yb3+/Tm3+ were investigated in detail. Under 980 nm laser diode (LD) excitation, the emission intensity and the corresponding luminescence colors of YOF:Yb3+/Er3+ and YOF:Yb3+/Tm3+ could be precisely adjusted by changing the doping concentration of Yb3+ ions. Furthermore, the paper also offers a new alternative in synthesizing such materials and opens the possibility to meet the increasing commercial demand.

Ding, Mingye; Lu, Chunhua; Cao, Linhai; Ni, Yaru; Xu, Zhongzi

2013-04-01

9

Solvothermal synthesis and upconversion properties of YF3:Ln (Ln = Yb/Er,Yb/Tm,Yb/Ho) nanoparticles.  

PubMed

YF3 nanoparticles with different morphology, dimension, and dispersity have been synthesized through a simple solvothermal method by using n-octanol and n-octylamine as a mixed solvent and lanthanide acetylacetonate as the RE3+ source. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), energy dispersive X-ray spectrum (EDS) and up-conversion (UC) photoluminescence spectra were used to characterize the samples. The results reveal that the morphology and dimension of the as-prepared nanoparticles can be regulated by adjusting n-octanol/ n-octylamine volume ratio in the initial system. Besides, by doping with different rare-earth elements (Yb/Er, Yb/Tm, Yb/Ho), the as-prepared YF3 samples can emit characteristic green, blue, and yellow light under 980 nm laser excitation. Additionally, when being co-doped with the activator ion-pairs Tm/Er and Tm/Ho, the color of the emission light can be further modified by adjusting the Yb3+ ion content. PMID:24734578

He, Fei; Wang, Lin; Niu, Na; Gai, Shili; Wang, Yan; Yang, Piaoping

2014-05-01

10

Enhanced 1.8 ?m emission in Yb3+/Tm3+ co-doped tellurite glass: Effects of Yb3+?Tm3+ energy transfer and back transfer  

NASA Astrophysics Data System (ADS)

The ~1.8 ?m emission characteristics of Tm3+ by a direct excitation and through an energy transfer process upon sensitization with Yb3+ ions in tellurite glass are reported. The spectroscopic properties of Tm3+ ions have been evaluated by applying Judd-Ofelt theory on the measured absorption spectrum. The obtained intensity parameters, ?2=7.15510-20 cm2, ?4=3.32510-20 cm2, ?6=1.27810-20 cm2 are used to estimate the radiative properties of Tm3+ ions in the present glass host. A ~10 fold enhancement in the Tm3+ 1.8 ?m emission observed with 16 fold reduced emission of Yb3+ ions (1008 nm) in co-doped sample on Yb3+ ions excitation illustrates the efficient energy transfer from Yb3+: 2F5/2?Tm3+: 3H5. The energy transfer process assisted by host phonon energy has been discussed by using relevant theoretical models and estimated the energy transfer micro-parameters. Effect of energy back transfer Tm3+?Yb3+ on NIR and upconversion emissions have been discussed. An efficient ~1.8 ?m with comparatively higher emission cross-section 1.11510-20 cm2 on account of reduced upconversion emissions has been achieved in the present tellurite glass.

Balaji, Sathravada; Biswas, Kaushik; Sontakke, Atul D.; Gupta, Gaurav; Annapurna, Kalyandurg

2014-11-01

11

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

NASA Astrophysics Data System (ADS)

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 950C 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.

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

2014-10-01

12

Upconversion luminescence and mechanisms of Tm(3+)/Yb(3+)-codoped oxyhalide tellurite glasses.  

PubMed

To obtain efficient blue upconversion laser glasses, upconversion luminescence and mechanisms of Tm(3+)/Yb(3+)-codoped oxyhalide tellurite glasses were investigated under 980 nm excitation. The results showed that upconversion blue and red emission intensities of Tm(3+) first increase, reach its maximum at Tm(2)O(3)%=0.1 mol %, and then decrease with increasing Tm(2)O(3) content. The effect of Tm(2)O(3) content on upconversion intensity is discussed, and possible effect mechanisms are evaluated. The investigated results were conducing to increase upconversion luminescence efficiency of Tm(3+). PMID:16257776

Xu, Shiqing; Fang, Dawei; Zhang, Zaixuan; Jiang, Zhonghong

2005-11-01

13

Yb3+ sensitized Tm3+ upconversion in tellurite lead oxide glass.  

PubMed

Triply ionized thulium/thulium--ytterbium doped/codoped TeO2-Pb3O4 (TPO) glasses have been fabricated by classical quenching method. The upconversion emission spectra in the Tm3+/Tm3+-Yb3+ doped/codoped glasses upon excitation with a diode laser lasing at ?980 nm has been studied. Effect of the addition of the Yb3+ on the upconversion emission intensity in the visible and near infrared regions of the Tm3+ doped in TPO glass has been studied and the processes involved explored. PMID:22265952

Mohanty, Deepak Kumar; Rai, Vineet Kumar; Dwivedi, Y

2012-04-01

14

Up-conversion emission in KGd(WO 4 ) 2 single crystals triply-doped with Er 3+ /Yb 3+ /Tm 3+ , Tb 3+ /Yb 3+ /Tm 3+ and Pr 3+ /Yb 3+ /Tm 3+ ions  

NASA Astrophysics Data System (ADS)

Triply-doped single crystals KGd(WO 4) 2:Er 3+/Yb 3+/Tm 3+, KGd(WO 4) 2:Tb 3+/Yb 3+/Tm 3+ and KGd(WO 4) 2:Pr 3+/Yb 3+/Tm 3+ were grown by the Top Seeded Solution Growth (TSSG) method, with an aim of getting efficient up-converted multicolored luminescence, which subsequently can be used for generation of white light. Such an aim determined the choice of the triply doped compounds: excitation of the Yb 3+ ions in the infrared spectral region is followed by red, green and blue emission from other dopants. It was shown that all these systems exhibit multicolor up-conversion fluorescence under 980 nm laser irradiation. Detailed spectroscopic studies of their absorption and luminescence spectra were performed. From the analysis of the dependence of the intensity of fluorescence on the excitation power the conclusion was made about significant role played by the host's conduction band and other possible defects of the KGd(WO 4) 2 crystal lattice in the up-conversion processes.

Kasprowicz, D.; Brik, M. G.; Majchrowski, A.; Michalski, E.; G?uchowski, P.

2011-09-01

15

[White light upconversion luminescence and its mechanism of Yb3+/Ho3+/Tm3+ co-doped tellurite glass].  

PubMed

Yb3+ /Ho3+, Yb3+ /Tm3+ and Yb3+ /Ho3+ /Tm3+ co-doped tellurite glasses were prepared by melt-quenching method. Under the excitation of 980 nm laser, Yb3+ /Ho3+/Tm3+ co-doped glass sample shows strong blue, green and red emissions, corresponding to the transitions 1G4 --> 3H6 of Tm3+, 5F4 (5S2) --> 5 I8 of Ho3+, as well as 5F5 -->5 I8 of Ho3+ and 1G4 --> 3F4 of Tm3+ ions, respectively. It was found that the integrated emission intensity ratio of the red to green in Yb3+/Ho3+ /Tm3+ co-doped sample (3.95) is greater than that in Yb3+/Ho3+ co-doped sample (1.69) due to the cross-relaxation between Ho3+ and Tm3+ ions : 3H4 (Tm3+) + 5 I6 (Ho3+) -->3F4 (Tm3+) + 5F5 (Ho3+), and 3F4 (Tm3+ ) + 5 I8 (Ho3+) --> 3H6 (Tm3+) +5 I7 (Ho3+). When the pump power density is 8.2 W x cm(-2), the calculated color coordinates of Yb3+ /Ho3+ /Tm3+ co-doped sample are x = 0.345, y = 0.338, which is very close to the equal energy white light (x = 0.333, y = 0.333). PMID:22512158

Pan, Xin-xiang; Zhong, Hai-yang; Xing, Ming-ming; Wang, Yi-zhuo

2012-02-01

16

Complexation of trivalent rare earth elements (Ce, Eu, Gd, Tb, Yb) by carbonate ions  

Microsoft Academic Search

Carbonate stability constants for five rare earth elements (Ce[sup 3+], Eu[sup 3+], Gd[sup 3+], Tb[sup 3+], and Yb[sup 3+]) have been determined at t = 25[degrees]C and 0.70 [plus minus] 0.02 M ionic strength through solvent exchange techniques. Estimated stability constants for Ce, Eu, and Yb are in close agreement with previous work. Analyses using Gd and Tb provide the

Jong Hyeon Lee; R. H. Byrne

1993-01-01

17

Upconversion properties of Er3+, Yb3+ and Tm3+ codoped fluorophosphate glasses.  

PubMed

Er3+, Yb3+ and Tm3+ codoped fluorophosphate glasses emitting blue, green and red upconversion luminescence at 970 nm laser diode excitation were studied. It was shown that Tm3+ behaves as the sensitizer to Er3+ for the green upconversion luminescence through the energy transfer process: Tm3+:3H4+Er3+:4I 15/2-->Er3+:4I 9/2+Tm3+:3H6, and for the red upconversion luminescence through the energy transfer process: Tm3+:3F4+Er3+:4I 11/2-->Tm3+:3H6+Er3+:4F 9/2. Moreover, Er3+ acts as quenching center for the blue upconversion luminescence of Tm3+. The sensitization of Tm3+ to Er3+ depends on the concentration of Yb3+. The intensity of blue, green and red emissions can be changed by adjusting the concentrations of the three kinds of rare earth ions. This research may provide useful information for the development of high color and spatial resolution devices and white light simulation. PMID:17329153

Liao, Meisong; Hu, Lili; Fang, Yongzheng; Zhang, Junjie; Sun, Hongtao; Xu, Shiqing; Zhang, Liyan

2007-11-01

18

Upconversion properties of Er 3+, Yb 3+ and Tm 3+ codoped fluorophosphate glasses  

NASA Astrophysics Data System (ADS)

Er 3+, Yb 3+ and Tm 3+ codoped fluorophosphate glasses emitting blue, green and red upconversion luminescence at 970 nm laser diode excitation were studied. It was shown that Tm 3+ behaves as the sensitizer to Er 3+ for the green upconversion luminescence through the energy transfer process: Tm 3+: 3H 4 + Er 3+: 4I 15/2 ? Er 3+: 4I 9/2 + Tm 3+: 3H 6, and for the red upconversion luminescence through the energy transfer process: Tm 3+: 3F 4 + Er 3+: 4I 11/2 ? Tm 3+: 3H 6 + Er 3+: 4F 9/2. Moreover, Er 3+ acts as quenching center for the blue upconversion luminescence of Tm 3+. The sensitization of Tm 3+ to Er 3+ depends on the concentration of Yb 3+. The intensity of blue, green and red emissions can be changed by adjusting the concentrations of the three kinds of rare earth ions. This research may provide useful information for the development of high color and spatial resolution devices and white light simulation.

Liao, Meisong; Hu, Lili; Fang, Yongzheng; Zhang, Junjie; Sun, Hongtao; Xu, Shiqing; Zhang, Liyan

2007-11-01

19

Intense red upconversion emission of Yb/Tm/Ho triply-doped tellurite glasses.  

PubMed

By conventional melting and quenching methods, 3Yb2O3-0.2Tm2O3-xHo2O3 (wt%, x=0.2~1.2) was doped into an easily fiberized tellurite glass with composition of 78TeO2-10ZnO-12Na2O (mol%) to form YTH-TZN78 glasses. Under 976 nm excitation, the direct sensitizing effect of Yb ions (Yb?Ho) and indirect sensitizing and self-depopulating effects of Tm ions (Yb?Tm?Ho) were found to present intense red upconversion emission at 657 nm (Red, Ho:5F5?5I8) and were responsible for the absence of the usually observed 484 nm emission (Blue, Tm:1G4?3H36). Regardless of the dopant concentration of Ho ions, the intensity of the red emission at 657 nm (Red, Ho:5F5?5I8) is about three times stronger than that of the green one at 543 nm (Green, Ho:5S2?5I8). For this certain red emission at 657 nm, 0.4 wt% Ho2O3-doped YTH-TZN78 glass was found to present the highest emission intensity and is therefore determined as a promising active tellurite glass for red fiber laser development. PMID:22614614

Zhan, Huan; Zhou, Zhiguang; He, Jianli; Lin, Aoxiang

2012-05-20

20

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

PubMed

Eu3+ and Yb3+ codoped Y2O3 phosphors were synthesized by the sol-gel method. The phosphors possess absorption in the region of 300-550 nm, exhibiting an intense NIR emission of Yb3+ around 1000 nm, which is suitable for matching the maximum spectral response of c-Si solar cells. The optimum composition of Eu3+ and Yb3+ codoped Y2O3 was (Y1.94Yb0.04Eu0.02)2O3. It is observed that two-step energy transfer occurs from the 5D2 level of Eu3+ situated around (466 nm) exciting two neighboring Yb3+ ions to the 2F5/2 level (1000 nm). The down-conversion material based on Eu(3+)- Yb3+ couple may have great potential applications in c-Si solar cells to enhance their photovoltaic conversion efficiency via spectral modification. PMID:24738417

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

2014-06-01

21

[Upconversion luminescence properties of ZBLAN : Nd3+, Tm3+, Yb3+].  

PubMed

The ZBLAN : Nd3+, Tm3+, Yb3+ upconversion materials were prepared by high-temperature solid method. The concentrations of Tm3+ and Yb3+ were 0.01% and 0.3% respectively. The concentration of Nd3+ changed in the range from 0.1% to 2%. The absorption spectrum of ZBLAN : Nd3+, Tm3+, Yb3 in all samples from 300 to 1 000 nm was measured at room temperature. The upconversion emission was observed when excited by 798 nm infrared light. The material samples emitted relatively strong multi-band (the red, blue and green color) visible light. Based on the experiment, the multi-band visible spectral lines were analyzed, and the energy level transition mechanism was given. The blue light results from the transition of 1G4 --> 3 H6 of Tm3+, the green light is from the transition of 2 H7/2 --> 4 I9/2 of Nd3+, and the red light originates from the transition of 2 H11/2 --> I9/2 of Nd3+. The results show that the upconversion mechanism includes excited state absorption, energy transfer, cross relaxation and so on. The energy transfer processes between Nd3+, Tm3+ and Yb3+ ions both forward and backward prove to be the origin of upconversion emissions. The effect of rare earth doping concentration on the energy upconversion efficiency was analyzed, according to the different upconversion light emitting intensity from samples with different Tm3+ mol concentrations. The upconversion luminescence increased with the Nd3+ concentration and got its peak at 1.5%. PMID:19810515

Yang, Zhi-Ping; Du, Hai-Yan; Sun, Jia-Yue; Wang, Wei

2009-06-01

22

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

NASA Astrophysics Data System (ADS)

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.

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

2015-02-01

23

Nanopatterned PMMA-Yb:Er/Tm:Lu2O3 composites with visible upconversion emissions.  

PubMed

Nanopillars, nanotubes and nanofibers of transparent polymethyl methacrylate (PMMA) polymer with Yb:Ln:Lu2O3 (Ln=Er or Tm) nanoparticles (NPs) (?30-35 nm average size) have been prepared by infiltration of anodized aluminum oxide hexagonally nanopatterned templates. The outer diameter of these nanostructures is in the 330-400 nm range, with lengths up to 50 ?m and a period distance of 430 nm. These nanostructures show visible upconversion (UC) emissions under excitation with 978 nm light. The steady state temperature of the polymer nanostructures is optically evidenced by the Er(3+) UC emission and optically controlled around the PMMA glass transition temperature by the excitation light, introducing a new method for NP storage in a solid and potential optically induced particle release. Full color emission is shown in tridoped (Yb:Er:Tm) samples. PMID:24784527

Han, X; Maiz, J; Mijangos, C; Zaldo, C

2014-05-23

24

Nanopatterned PMMA-Yb:Er/Tm:Lu2O3 composites with visible upconversion emissions  

NASA Astrophysics Data System (ADS)

Nanopillars, nanotubes and nanofibers of transparent polymethyl methacrylate (PMMA) polymer with Yb:Ln:Lu2O3 (Ln = Er or Tm) nanoparticles (NPs) (?30-35 nm average size) have been prepared by infiltration of anodized aluminum oxide hexagonally nanopatterned templates. The outer diameter of these nanostructures is in the 330-400 nm range, with lengths up to 50 ?m and a period distance of 430 nm. These nanostructures show visible upconversion (UC) emissions under excitation with 978 nm light. The steady state temperature of the polymer nanostructures is optically evidenced by the Er3+ UC emission and optically controlled around the PMMA glass transition temperature by the excitation light, introducing a new method for NP storage in a solid and potential optically induced particle release. Full color emission is shown in tridoped (Yb:Er:Tm) samples.

Han, X.; Maiz, J.; Mijangos, C.; Zaldo, C.

2014-05-01

25

Eu(3+), yb (3+) and eu (3+)-yb (3+) complexes with salicylic Acid and 1,10-phenanthroline: synthesis, photoluminescent properties and energy transfer.  

PubMed

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

Sharma, Garima; Narula, Anudeep Kumar

2015-03-01

26

Emission decay and energy transfer in Yb/Tm Y-codoped fibers based on nano-modified glass  

NASA Astrophysics Data System (ADS)

We report the results of an experimental investigation and theoretical analysis of luminescence decay in Yb/Tm Y-codoped fibers based on nano-modified glass. Based on the experimental results, numerical simulations allowed us to estimate the energy transfer efficiency between Yb3+ and Tm3+ ions. It was shown that yttria enhances the Yb/Tm energy transfer making fibers with Y-codoping a promising candidate for the development of light sources for laser applications and up-conversion emitters for visualization applications. These fibers demonstrate energy transfer efficiency of ?50%, which makes them attractive for diode-pumping of Yb-ions at a wavelength of 975 nm.

Klimentov, Dmitry; Dvoyrin, Vladislav V.; Halder, Arindam; Paul, Mukul Chandra; Das, Shyamal; Bhadra, Shyamal K.; Sorokina, Irina T.

2015-04-01

27

Strong visible up-conversion emission in Tb3+, Tm3+ and Tb3+-Tm3+ co-doped tellurite glasses sensitized by Yb3+.  

PubMed

Up-conversion luminescence characteristics under 975 nm excitation have been investigated with Tb3+/Tm3+/Yb3+ triply doped tellurite glasses. Here, green (547 nm: (5)D(4)-->(7)F(4)) and red (660 nm: (5)D(4)-->(7)F(2)) up-conversion (UC) luminescence originating from Tb3+ is observed strongly, because of the quadratic dependences of emission intensities on the excitation power. Especially, the UC luminescence was intensified violently with the energy transfer from the Tm3+ ions involves in the Tb3+ excitation. To the Tb3+/Tm3+/Yb3+ triply doped glass system, a novel up-conversion mechanism is proposed as follows: the energy of (3)G(4) level (Tm3+) was transferred to (5)D(4) (Tb(3+)) and the 477-nm UC luminescence of Tm3+ was nearly quenched. PMID:17110158

Wang, Xunsi; Liu, Liren; Nie, Qiuhua; Xu, Tiefeng; Shen, Xiang; Dai, Shixun; Zhang, Xianghua

2007-07-01

28

Multicolor upconversion emission and energy transfer mechanism in Er3+/Tm3+/Yb3+ codoped tellurite glasses  

NASA Astrophysics Data System (ADS)

A novel Er3+, Tm3+ and Yb3+ codoped tellurite glasses with composition of TeO2-Bi2O3-ZnO-Na2O was prepared by conventional melt-quenching technique to realize the multicolor upconversion (UC) emissions. The absorption spectrum, UC emission spectrum, Raman spectrum, X-ray diffraction (XRD) and differential scanning calorimeter (DSC) curves were measured to characterize the prepared glass samples. Under the excitation of 980 nm laser diode (LD), bright multicolor luminescence composed of red, green and/or blue UC emissions corresponding to the transitions 4F9/2?4I15/2, 2H11/2(4S3/2)?4I15/2 of Er3+ and 1G4?3H6 of Tm3+ were observed in the Er3+/Yb3+, Tm3+/Yb3+ and Er3+/Tm3+/Yb3+ codoped glass samples, which were mainly attributed to the successive energy transfers from Yb3+ to Er3+ and Tm3+, respectively. The energy transfer mechanisms from the Yb3+:2F5/2 level to Er3+:4I11/2 and Tm3+:3H5 levels were further investigated by quantitatively calculating the energy transfer micro-parameters and phonon contribution ratios. Meanwhile, the difference (?T=Tx-Tg) between the glass crystallization onset temperature (Tx) and the transition temperature (Tg) which increase slightly with rare-earth (RE) doped concentration, was larger than 140 C for all glass samples. Furthermore, the amorphous nature of glass structure was demonstrated by the measured XRD curves. The excellent thermal stability and multicolor luminescent characteristic indicate that the present investigated Er3+/Tm3+/Yb3+ codoped tellurite glasses could be used in the fields of solid state multicolor displays and other luminescent devices.

Peng, Shengxi; Yang, Fengjing; Wu, Libo; Qi, Yawei; Zheng, Shichao; Yin, Dandan; Wang, Xunsi; Zhou, Yaxun

2014-11-01

29

Optical parameters and upconversion fluorescence in Tm3+/Yb3+-doped alkali-barium-bismuth-tellurite glasses.  

PubMed

Tm(3+)/Yb(3+)-doped alkali-barium-bismuth-tellurite (LKBBT) glasses have been fabricated and characterized. Density, refractive index, optical absorption, absorption and emission cross-sections of Yb(3+), Judd-Ofelt parameters and spontaneous transition probabilities of Tm(3+) have been measured and calculated, respectively. Intense blue three-photon upconversion fluorescence and near-infrared two-photon upconversion fluorescence were investigated under the excitation of a 980 nm diode laser at room temperature. Wide infrared transmission window, high refractive index and strong blue three-photon upconversion emission of Tm(3+) indicate that Tm(3+)/Yb(3+) co-doped LKBBT glasses are promising upconversion optical and laser materials. PMID:16527521

Lin, Hai; Liu, Ke; Lin, Lin; Hou, Yanyan; Yang, Dianlai; Ma, Tiecheng; Pun, Edwin Yun Bun; An, Qingda; Yu, Jiayou; Tanabe, Setsuhisa

2006-11-01

30

Enhanced near-infrared upconversion luminescence of GdF3:Yb3+, Tm3+ by Li+.  

PubMed

GdF3:0.23Yb3+, 0.005Tm3+, x%Li+ (x = 0-7) NIR to NIR upconversion nanocrystals (UCNPs) were synthesized by a hydrothermal method. Their XRD patterns show that they are all orthorhombic phase despite of different Li+ ion concentrations. The detailed analysis indicates that lithium ions substitute Gd3+ sites at x < 3. As the Li+ content increases, more Li+ ions enter host lattice interstitially. The doped Li+ ions affect the crystal field symmetry around Tm3+ ions, which results in the change of the irradiation transition probabilities between their corresponding transition levels. Compared with GdF3:0.23Yb3+, 0.005Tm3+, the NIR to NIR upconversion emission intensity of GdF3:0.23Yb3+, 0.005Tm3+, 0.03Li+ nanocrystals (excitation at 980 nm, emission at 808 nm) increases 2.2 times. PMID:24734614

Chuai, Xiaohong; Liu, Zhenyu; Liu, Ye; He, Chunfeng; Qin, Weiping

2014-05-01

31

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

SciTech Connect

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.

Jia, Dongdong [Department of Materials Science and Engineering, Tsinghua University, Beijing, (China)] [Department of Materials Science and Engineering, Tsinghua University, Beijing, (China); Jia, Weiyi [Department of Physics, University of Puerto Rico, Mayaguez, Puerto Rico 00681 (Puerto Rico)] [Department of Physics, University of Puerto Rico, Mayaguez, Puerto Rico 00681 (Puerto Rico); Evans, D. R. [Department of Physics and Astronomy, University of Georgia, Athens, Georgia 30602 (United States)] [Department of Physics and Astronomy, University of Georgia, Athens, Georgia 30602 (United States); Dennis, W. M. [Department of Physics and Astronomy, University of Georgia, Athens, Georgia 30602 (United States)] [Department of Physics and Astronomy, University of Georgia, Athens, Georgia 30602 (United States); Liu, Huimin [Department of Physics, University of Puerto Rico, Mayaguez, Puerto Rico 00681 (Puerto Rico)] [Department of Physics, University of Puerto Rico, Mayaguez, Puerto Rico 00681 (Puerto Rico); Zhu, Jing [Department of Materials Science and Engineering, Tsinghua University, Beijing, (China)] [Department of Materials Science and Engineering, Tsinghua University, Beijing, (China); Yen, W. M. [Department of Physics and Astronomy, University of Georgia, Athens, Georgia 30602 (United States)] [Department of Physics and Astronomy, University of Georgia, Athens, Georgia 30602 (United States)

2000-09-15

32

Intense 2.0 ?m emission properties and energy transfer of Ho3+/Tm3+/Yb3+ doped fluorophosphate glasses  

NASA Astrophysics Data System (ADS)

Intense 2.0 ?m emission has been obtained from Ho3+/Tm3+/Yb3+ triply doped fluorophosphate glass pumped by a conventional 980 nm laser diode. The spectroscopic properties and energy transfer mechanisms between Ho3+, Tm3+ and Yb3+ are analyzed. Based on the absorption spectra, the Judd-Ofelt parameters, radiation emission rates, radiative lifetime and branching ratios of Ho3+ ions are calculated. It is also found that the 2.0 ?m emission of Ho3+ can be greatly enhanced under the excitation at 980 nm by incorporating Tm3+ and Yb3+ simultaneously. Additionally, the micro-parameters of the energy transfer processes are quantitatively analyzed. The energy transfer coefficient from Yb3+ to acceptors and from Tm3+ to Ho3+ can reach as high as 13.14 10-40 cm6/s and 23.39 10-40 cm6/s, respectively. This Ho3+/Tm3+/Yb3+ doped fluorophosphate glass possessing high energy transfer coefficient and excellent thermal stability is a promising candidate for efficient 2.0 ?m laser.

Tian, Ying; Xu, Rongrong; Hu, Lili; Zhang, Junjie

2011-08-01

33

Three- and two-photon upconversion luminescence switching in Tm/Yb-codoped sodium niobate nanophosphor  

NASA Astrophysics Data System (ADS)

Intense infrared-to-visible upconversion (UC) emission in Tm/Yb-codoped sodium niobate (NaNbO) nanocrystals under resonant excitation at 976 nm is presented. The results showed that by increasing the pump power/intensity, a strong reduction is observed at the 800/480 nm emitted intensity ratio, characterizing what can be denominated as laser pump power-induced color tunability or luminescent switching. The physical origin is discussed with a focus on tailoring of luminescent switchers to operate at a large pump power range and, indeed, it is intrinsically associated with the competition of the two- and three-photon UC processes and with highly efficient UC emissions in the investigated material. The effect of Yb-ion concentration along with the theoretical aspects on luminescence switching has been investigated. The results obtained here could be useful in the field of sensors and networks for optical processing and optical communications.

Kumar, Kagola Upendra; Silva, Wagner Ferreira; Venkata Krishnaiah, Kummara; Jayasankar, Chalicheemalapalli Kulala; Jacinto, Carlos

2014-01-01

34

Blue Upconversion Luminescence in Tm3+/Yb3+ Codoped CaWO4 Polycrystals  

NASA Astrophysics Data System (ADS)

We investigate the upconversion emission of CaWO4:Tm3+/Yb3+ polycrystals prepared by the high-temperature solid-state method. The crystal structure of the polycrystals is characterized by means of x-ray diffraction. Under the excitation of a 980 nm continuous wave diode laser, the samples show intense blue upconversion emissions centered at 473 nm, corresponding to the 1G4?3H6 transition of Tm3+. The dependence of the upconversion emission intensity on the pump power of a laser diode is measured, and the results indicate that the two-photon and three-photon processes contribute simultaneously to the blue upconversion emissions. The possible multi-photon upconversion process and upconversion mechanisms are discussed.

Xu, Yan-Ling; Wang, Yun-Long; Shi, Lian-Sheng; Tan, Xiang

2013-08-01

35

Intense ultraviolet upconversion emission from water-dispersed colloidal YF3:Yb3+/Tm3+ rhombic nanodisks  

NASA Astrophysics Data System (ADS)

Intense ultraviolet upconversion emission has been observed in water-dispersed uniform rhombic nanodisks (side length of ~14 nm and thickness of ~2.5 nm) of YF3 co-doped with Yb3+ sensitizer and Tm3+ activator ions, when excited at ~980 nm.Intense ultraviolet upconversion emission has been observed in water-dispersed uniform rhombic nanodisks (side length of ~14 nm and thickness of ~2.5 nm) of YF3 co-doped with Yb3+ sensitizer and Tm3+ activator ions, when excited at ~980 nm. Electronic supplementary information (ESI) available: Experimental and instrumental details, histograms of the YF3 nanodisk size; FT-IR spectra of YF3 nanocrystals before and after ligand exchange using PAA. XRD patterns of YF3:Yb3+/Tm3+ nanocrystals doped with Yb3+ ions of 0, 10, 30, 50, 70, 90, and 98 mol%; TEM images of YF3:(10, 30, 50, 70, 90, 98)% Yb3+/2% Tm3+ nanocrystals before and after ligand exchange and inductively coupled plasma atomic emission spectroscopy of YF3 nanocrystals. See DOI: 10.1039/c3nr04617f

Qiu, Hailong; Chen, Guanying; Fan, Rongwei; Yang, Liming; Liu, Cheng; Hao, Shuwei; Sailor, Michael J.; Ǻgren, Hans; Yang, Chunhui; Prasad, Paras N.

2013-12-01

36

Exchange Bias in Multiferroic RFe2O4 (R=Y, Er, Tm, Yb, Lu, and In)  

NASA Astrophysics Data System (ADS)

An exchange bias (EB) behavior has been observed for multiferroic RFe2O4 (R=Y, Er, Tm, Yb, Lu, and In). The materials with small R3+ ions (R=Tm, Yb, Lu, and In) exhibit large EB fields (?1 kOe) below 100{--}150 K. This property is rooted in a magnetically glassy state, arising from the competition between ferromagnetic and antiferromagnetic domain interactions. In addition, the EB field tends to be more enhanced for smaller R3+ ions. Hence, the EB is controlled by the substitution at the R-site in this series.

Yoshii, Kenji; Ikeda, Naoshi; Nishihata, Yasuo; Maeda, Daisuke; Fukuyama, Ryota; Nagata, Tomoko; Kano, Jun; Kambe, Takashi; Horibe, Yoichi; Mori, Shigeo

2012-03-01

37

Highly improved upconversion luminescence in NaGd(WO?)?:Yb?/Tm? inverse opal photonic crystals.  

PubMed

The upconversion luminescence (UCL) of rare earth (RE) ions doped nanomaterials has attracted extensive interest because of its wide and great potential applications. However, the lower UCL efficiency is still an obstacle for real applications. Photonic modulation is a novel way to improve the efficiency of UCL. In this work, NaGd(WO4)2:Yb(3+)/Tm(3+) inverse opal photonic crystals (IOPCs) were fabricated through the polymethylmethacrylate (PMMA) template and the modification of the IOPC structure on the emission spectra and dynamics of Tm(3+) ions was systemically studied. It is interesting to observe that in the IOPCs, the high-order UCL (1)D2-(3)H6/(3)F4 was relatively enhanced. At the same time, the local thermal effect induced by laser irradiation was suppressed. Furthermore, the overall intensity ratio of visible UCL to near-infrared (NIR) down-conversion luminescence (DCL) was 2.8-8 times improved than that of the grinded reference (REF) and independent of the photonic stop band (PSB). The studies on UCL dynamics indicated that the nonradiative transition rate of Tm(3+) was considerably suppressed. The facts above indicated that in the IOPCs the UCL efficiency of Tm(3+) was largely improved due to the periodic macroporous structure. PMID:25493336

Wang, Yunfeng; Xu, Wen; Cui, Shaobo; Xu, Sai; Yin, Ze; Song, Hongwei; Zhou, Pingwei; Liu, Xiaoyan; Xu, Lin; Cui, Haining

2015-01-28

38

White upconversion emission in Li+/Yb3+/Tm3+/Er3+-doped Gd6MoO12 phosphors  

NASA Astrophysics Data System (ADS)

The Yb3+/Er3+/Tm3+-doped Gd6MoO12 phosphors and Li+/Yb3+/Er3+/Tm3+-doped Gd6MoO12 phosphors were synthesized by the high-temperature solid-state method. Under 980 nm laser diode excitation, the Gd6MoO12:Li+/Yb3+/Er3+/Tm3+ phosphors show the white upconversion (UC) emission at the pump power of 200 mW/cm2, which is composed of the blue (1G4?3H6 of Tm3+), green (2H11/2, 4S3/2?4I15/2 of Er3+), and red (4F9/2?4I15/2 of Er3+) UC emissions. The calculated CIE color coordinates of Gd6MoO12:Tm3+/Er3+/Yb3+ phosphors changed from blue area to white area after the Li+ ion doping. Then, the effect of Li+ ions mixing on the emission was analysed. The relative UC mechanisms and properties were also investigated and proposed based on their spectral. The additional mixed Li+ ions enhanced the red and green upconversion emission largely in this phosphor and then formed the white UC emission, which indicated that the Li+ is a promising dopant for tuning white light luminescence in some case.

Sun, Jiayue; Xue, Bing; Du, Haiyan

2013-07-01

39

Thermodynamic properties of liquid alloys Ni-Eu and Ni-Yb  

NASA Astrophysics Data System (ADS)

Mixing enthalpies of melts of the binary Ni-Eu (0 < x Ni < 0.89) and Ni-Yb (0 < x Ni < 1) systems at 1300-1750 K were investigated using the isoperibolic calorimetry. They have alternating signs depending on the melt concentration. With the combined analysis of the data determined by us and in literature, the models of the liquid and solid alloys were obtained, and the phase diagrams were calculated.

Berezutskii, V. V.; Shevchenko, M. A.; Ivanov, M. I.; Sudavtsova, V. S.

2014-09-01

40

Effect of Metal Coating on NaYF4:Yb3+,Tm 3+ Upconversion Nanoparticles  

NASA Astrophysics Data System (ADS)

Upconversion is the process in which two or more low-energy photons are absorbed and emitted as one high-energy photon. This research reports on the effect of layer-by-layer polyelectrolytes and silver coating on hexagonal NaYF4:Yb3+,Tm3+ in an attempt to enhance the upconversion intensity. The synthesized upconversion nanoparticles were separated into two, 140 nm and a mixture of two populations, 250 nm and 25 nm. The former case observed enhancement, when silver coated on the upconversion nanoparticles using hydroquinone as the reducing agent, with no layers and with several layers (three, four and five) of polyelectrolytes. The size (140 nm) and morphology of the hexagonal NaYF4:Yb 3+,Tm3+ were similar. The enhancement was confirmed when sodium cyanide was added to remove the silver coating from the sample resulting in a decrease in the upconversion intensity. Quenching was observed in the latter case, when silver coating was unsuccessful and that there are two populations of upconversion nanoparticles (large 250 nm and small 25 nm).

Alazemi, Abdulrahman

41

Energy transfer processes in Yb3+ Tm3+ co-doped sodium alumino-phosphate glasses with improved 1.8 m emission  

NASA Astrophysics Data System (ADS)

Sodium alumino-phosphate glasses co-doped with Yb3+ and Tm3+ ions have been prepared with notably low OH- content, and characterized from the viewpoint of their spectroscopic properties. In these glasses, Yb3+ acts as an efficient sensitizer of excitation energy at 0.98 mwhich can be provided by high power and low cost diode lasers, and subsequently undergoes non-resonant energy transfer to Tm3+ ions (2F5/2, ^{3}\\mathrm {H}_{6 } \\to {}^{2} \\mathrm {F}_{7/ 2} , 3H5). Through this process, the emitting level 3F4 is rapidly populated, generating improved emission at 1.8 m (^{3} \\mathrm {F}_{4} \\to {}^{3}\\mathrm {H}_{6} ). In order to guarantee the efficiency of such favorable energy transfer, energy losses via multiphonon decay, Yb-Yb radiative trapping, and non-radiative transfer to OH- groups were evaluated, and minimized when possible. The dipole-dipole energy transfer microscopic parameters corresponding to \\mathrm {Yb}^{3+} \\to \\mathrm {Tm}^{3+ } , \\mathrm {Yb}^{3+} \\to \\mathrm {Yb}^{3+} and \\mathrm {Tm}^{3+} \\to \\mathrm {Tm}^{3+} transfers, calculated by the Frster-Dexter model, are CYb-Tm = 2.9 10-40 cm6 s-1, CYb-Yb = 42 10-40 cm6 s-1 and CTm-Tm = 43 10-40 cm6 s-1, respectively.

de Camargo, Andrea S. S.; Terra, Idelma A. A.; Nunes, Luiz Antonio de O.; Li, M. Siu

2008-06-01

42

Activation cross sections of the 169Tm( d, 2n) reaction for production of the therapeutic radionuclide 169Yb  

Microsoft Academic Search

Activation cross sections of deuteron induced nuclear reactions on 169Tm were measured up to 20MeV by using the stacked-foil technique. Special emphasis was on production of the internal radiotherapy related radionuclide 169Yb. No earlier experimental cross-section data on deuteron induced reactions on 169Tm were found in the literature. The experimental data were compared with the results of the nuclear model

F. Trknyi; A. Hermanne; S. Takcs; F. Ditri; I. Spahn; S. F. Kovalev; A. V. Ignatyuk; S. M. Qaim

2007-01-01

43

Synthesis and photoluminescence properties of heteroleptic Eu 3+, Tb 3+ and Tm 3+ complexes  

Microsoft Academic Search

Five Eu(III), four Tb(III) and two Tm(III) multichromophoric complexes (1-Eu, 1-Tb, 2-Eu, 3-Eu, 3-Tb, 3-Tm, 4-Tb, 4-Tm, 5-Eu, 6-Eu and 6-Tb; where 1=tris[dibenzoylmethanido] (4?-chloro-2,2?:6?,2??-terpyridine), 2=tris[dibenzoylmethanido] (4?-(9H-carbazol-9yl)-2,2?:6?,2??-terpyridine), 3=tris(1,1,1,5,5,5-hexafluoroacetylacetonato), 4=tris[1,1,1,5,5,5-hexafluoroacetylacetonato] (tripyridin-2-ylamine), 5=tris[dibenzoylmethanido][N-(4-(9H-carbazol-9-yl)butyl)-N-(dipyridin-2-yl)amine] and 6=tris[dibenzoylmethanido][N-(6-(9H-carbazol-9-yl)hexyl)-N-(dipyridin-2-yl)amine]) emitting in the blue (Tm), green (Tb) and red (Eu) spectral regions, have been synthesized and characterized. The complexes involve five different coordinating (2,2?:6?,2??-terpyridine (terpy); dibenzoylmethane (dbm); 1,1,1,5,5,5-hexafluoroacetylacetonato

Gianluca Accorsi; Nicola Armaroli; Franois Cardinali; Dong Wang; Youxuan Zheng

2009-01-01

44

h112 band in 159Tm and the second yrast crossing in 158Er and 160Yb  

NASA Astrophysics Data System (ADS)

All the members of the h112 rotational structure have been observed in 69159Tm up to spin 492+. The alignments of these bands relative to the core nuclei 68158Er90 and 70160Yb90 are presented. These data provide additional evidence that the second backbend of the yrast structure of the core results from an (h112)2 proton alignment. NUCLEAR REACTIONS 148Sm(14N,3n)159Tm, E=68 MeV; measured ?-? coin, ?(?). 159Tm deduced levels.

Larabee, A. J.; Waddington, J. C.

1981-11-01

45

Y2O3:Tm,Yb nanophosphors for correlative upconversion luminescence and cathodoluminescence imaging.  

PubMed

We present a phosphor nanoparticle that shows both upconversion luminescence (UCL) and cathodoluminescence (CL). With this particle, low-autofluorescence, deep-tissue and wide-field fluorescence imaging can be achieved with nanometer-order high-spatial-resolution imaging. We synthesized Y2O3:Tm,Yb nanophosphors that emit visible and near-infrared UCL under 980 nm irradiation and blue CL via electron beam excitation. The phosphors were applied to fluorescent imaging of HeLa cells. The photostability of the phosphors was superior to that of a conventional organic dye. We show that after uptake by HeLa cells, the particles can be imaged with SEM and CL contrast in a cellular section. This indicates that correlative UCL and CL imaging of biological samples could be realized. PMID:25146422

Fukushima, Shoichiro; Furukawa, Taichi; Niioka, Hirohiko; Ichimiya, Masayoshi; Miyake, Jun; Ashida, Masaaki; Araki, Tsutomu; Hashimoto, Mamoru

2014-12-01

46

Broad-beam transmission data for new brachytherapy sources, Tm-170 and Yb-169.  

PubMed

The characteristics of the radionuclides (170)Tm and (169)Yb are highly interesting for their use as high dose-rate brachytherapy sources. The introduction of brachytherapy equipment containing these sources will lead to smaller required thicknesses of the materials used in radiation protection barriers compared with the use of conventional sources such as (192)Ir and (137)Cs. The purpose of this study is to determine the required thicknesses of protection material for the design of the protecting walls. Using the Monte Carlo method, transmission data were derived for broad-beam geometries through lead and concrete barriers, from which the first half value layer and tenth value layer are obtained. In addition, the dose reduction in a simulated patient was studied to determine whether transmission in the patient is a relevant factor in radiation protection calculations. PMID:16030058

Granero, Domingo; Prez-Calatayud, Jos; Ballester, Facundo; Bos, Adrie J J; Venselaar, Jack

2006-01-01

47

Luminescence of YAG doped with Eu, Yb, and Mn ions under VUV excitation  

NASA Astrophysics Data System (ADS)

Hydrothermal synthesis has been successfully used to obtain fine-crystalline powders of yttrium aluminum garnet (YAG) doped with manganese ions and codoped with cerium and manganese ions. Using the method of high-temperature solid-state synthesis, ceramic specimens of YAG that contain europium and ytterbium ions have been obtained. In synthesized YAG:Eu and YAG:Yb ceramics, no luminescence that can be attributed to 5 d-4 f transitions in Eu2+ or Yb2+ ions has been detected, even though the scheme of energy levels of these ions constructed with respect to YAG energy bands indicates that there is a potential possibility of the occurrence of 5 d-4 f luminescence for Eu2+ ions in YAG. At room temperature, the luminescence spectrum of hydrothermally synthesized YAG doped with manganese ions consists of two broad bands with maxima at 600 and 750 nm and does not contain any narrow bands in the red or IR range. Therefore, the spectrum contradicts to the properties of the luminescence of Mn2+, Mn3+, or Mn4+ ions in YAG described in the literature, even though the obtained hydrothermal specimens can contain noticeable concentrations only of Mn3+ ions.

Makhov, V. N.; Khaidukov, N. M.

2014-05-01

48

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

PubMed

Optical properties of Tm(3+)-doped SiO2-BaF2-ZnF2 glasses have been investigated on the basis of the Judd-Ofelt theory. Judd-Ofelt intensity parameters, radiative transition probabilities, fluorescence branching ratios and radiative lifetimes have been calculated for different glass compositions. Upconversion emissions were observed in Tm(3+)/Yb(3+)-codoped SiO2-BaF2-ZnF2 glasses under 980 nm excitation. The effects of composition, concentration of the doping ions, temperature, and excitation pump power on the upconversion emissions were also systematically studied. PMID:24051289

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

2014-01-24

49

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

NASA Astrophysics Data System (ADS)

Optical properties of Tm3+-doped SiO2-BaF2-ZnF2 glasses have been investigated on the basis of the Judd-Ofelt theory. Judd-Ofelt intensity parameters, radiative transition probabilities, fluorescence branching ratios and radiative lifetimes have been calculated for different glass compositions. Upconversion emissions were observed in Tm3+/Yb3+-codoped SiO2-BaF2-ZnF2 glasses under 980 nm excitation. The effects of composition, concentration of the doping ions, temperature, and excitation pump power on the upconversion emissions were also systematically studied.

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

2014-01-01

50

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

NASA Astrophysics Data System (ADS)

Single crystals of CaZn2Sb2, EuZn2Sb2, and YbZn2Sb2 were grown from melts of nominal composition AZn5Sb5 (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 1019 cm-3 to 1 1020 cm-3 are intrinsic to these materials. Also consistent with transport in polycrystalline materials, the carrier mobility is found to be lowest in CaZn2Sb2, 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 CaZn2Sb2 has the strongest coupling between the doping/defects and the electronic framework. Magnetization measurements reveal an antiferromagnetic transition near 13 K in EuZn2Sb2, 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 CaZn2Sb2 and YbZn2Sb2 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 CaZn2Sb2 displaying the largest Debye temperature and smallest mobility.

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

2012-02-01

51

Complexes of divalent lanthanides (Yb(ii), Eu(ii), Sm(ii)) with decaborates. (Reannouncement with new availability information)  

SciTech Connect

Decaborate complexes of divalent lanthanides are prepared through the reduction of B10H14 by elemental lanthanides in liquid NH3. The products are insoluble in liquid NH3. Extraction with CH3CN yields the complexes (CH3CH)6Yb(B10H14) and (CH3CN)xEu(B10H14), in which the boron cage is bound to the lanthanide dianion through Ln-H-B bonds. Solvent-separated decaborate anions (B10H13)- and (B10H15)- are also observed in the CH3CN extracts. Reductions of B10H14 by lanthanide amalgams, Ln(Hg) (Ln = Sm, Yb), in 1,2-dimethoxyethane (DME) produce small amounts of the DME-soluble salts containing the solvent-separated decaborate anions (B10H13)- and (B10H15)-. The major reaction product is insoluble in DME, but extraction with CH3CN yields salts with the solvent-separated (B10H13)- and (B10H15)-. Solvent-free Eu(B10B10) and Yb(B10B10) are prepared by decomposing in vacuum at 200 deg C NH3- and also CH3CN-solvated salts of Eu(B10H14) and Yb(B10H14). Further decomposition of Yb(B10H10) at temperatures above 600 deg C in vacuum leads to the formation of YbB6.

White, J.P.; Shore, S.G.

1992-12-31

52

Diode-pumped 2 ?m vibronic (Tm3+, Yb3+):KLu(WO4)2 laser.  

PubMed

We report on laser operation in a (6 at. % Tm, 5 at. % Yb):KLu(WO4)2 codoped crystal. The vibrational frequencies of KLu(WO4)2 are coupled to the electronic transitions of Tm3+ at 1946 nm, creating virtual final laser levels at higher energy than the ground level 3H6 of Tm3+. The longest recorded laser wavelength was 2039 nm, which is longer than permitted by a pure electronic transition in Tm3+ ions in KLu(WO4)2. We show that every laser wavelength can be explained with the electron-phonon coupling effect, where the vibration frequencies were determined through Raman spectroscopy. PMID:22614492

Segura, Martha; Mateos, Xavier; Pujol, Maria Cinta; Carvajal, Joan Josep; Aguil, Magdalena; Daz, Francesc; Griebner, Uwe; Petrov, Valentin

2012-05-10

53

Magnons and crystal-field transitions in hexagonal RMnO3 (R = Er, Tm, Yb, Lu) single crystals  

NASA Astrophysics Data System (ADS)

Far-infrared optical transmission spectra of the antiferromagnetic resonances, or magnons, and crystal-field (CF) transitions have been studied in hexagonal RMnO3 (R = Er, Tm, Yb, Lu) single crystals. The magnon and CF frequencies, their oscillator strengths, and effective g factors have been measured using external magnetic fields up to 9 T in the temperature range between 1.5 and 100 K. The magnon frequency increases systematically with a decrease of the R ion radius. The magnetic ordering of R ions (R = Er, Tm, Yb) was observed at low temperatures T<3.5 K and in strong external magnetic fields. The observed effects are analyzed taking into account the main magnetic interactions in the system including exchange of the Mn3+ spins with R3+ paramagnetic moments.

Standard, E. C.; Stanislavchuk, T.; Sirenko, A. A.; Lee, N.; Cheong, S.-W.

2012-04-01

54

Structural properties in RFe2O4 compounds (R=Tm, Yb, and Lu)  

NASA Astrophysics Data System (ADS)

We report a complete characterization of the crystal structure between 400 and 80 K for RFe2O4 (R = Rm, Yb, and Lu) compounds using high resolution x-ray synchrotron powder diffraction. The three samples have a hexagonal structure (space group R3m) characterized by a sequence of double layers of mixed valence iron and oxygen atoms forming two-dimensional triangular layers separated by a single R-O layer along the c axis. This structure is stable down to 80 K for TmFe2O4 and YbFe2O4 though a sudden expansion in the c axis is observed at around 300 K coupled to a variation in the electrical properties. However, LuFe2O4 exhibits two structural transitions upon cooling. The splitting of some reflections and the occurrence of superstructure peaks below 320 K reveal a structural phase transition. The unit cell is monoclinic (space group C2/m), and there are four nonequivalent Fe sites with a maximum charge disproportionation of 0.5 e. The hexagonal to monoclinic transition is characterized by a sudden expansion of the c axis on cooling, and it seems to be driven by the condensation of Y2 modes. At lower temperatures (170 K) additional splitting of several peaks indicate that the unit cell is no longer monoclinic but triclinic (space group P1). This transition is characterized by a contraction of the monoclinic ab plane, while the c axis remains almost unchanged. There are six nonequivalent Fe sites in the triclinic cell, and the charge disproportionation magnitude is little affected.

Blasco, J.; Lafuerza, S.; Garca, J.; Subas, G.

2014-09-01

55

Magnetic, thermodynamic, and electrical transport properties of ternary equiatomic ytterbium compounds YbTM (T=transition metal, M=Sn and Bi)  

NASA Astrophysics Data System (ADS)

Physical behavior of several YbTM intermetallics has been studied by means of x-ray powder diffraction, magnetization, dc magnetic susceptibility, heat capacity, and electrical resistivity measurements. The compounds YbTBi with T=Cu, Ag, Au and YbTSn with T=Ag, Au, Zn were shown to be nonmagnetic due to the presence of divalent ytterbium ions. The bismuthide YbPdBi as well as the stannides YbRhSn and YbPtSn were found to exhibit localized magnetism of almost trivalent Yb ions. The electrical behavior of these three phases is characteristic of dense Kondo systems, and their low-temperature specific heat data indicate a possible heavy fermion ground state.

Kaczorowski, D.; Leithe-Jasper, A.; Rogl, P.; Flandorfer, H.; Cichorek, T.; Pietri, R.; Andraka, B.

1999-07-01

56

Crystal field effects on the magnetic behavior of Yb 2V 2O 7 and Tm 2V 2O 7  

NASA Astrophysics Data System (ADS)

The bulk magnetic behaviors of the pyrochlores Yb 2V 2O 7 and Tm 2V 2O 7 were investigated. Calculated susceptibilities were adjusted to obtain the best fit to experimental data. A cubic crystal field Hamiltonian was used with B 4 = -0.633 and B 6 = 0.000705 K for Yb 3+ and B 4 = 0.0297 and B 6 = 0.000339 K for Tm 3+. The calculated susceptibility for Yb 3+ was found to be insensitive to the addition of an axial B 2 parameter to the cubic Hamiltonian.

Soderholm, Lynne; Stager, C. V.; Greedan, J. E.

1982-07-01

57

Multicolor upconversion luminescence in monodispersed Ba2LaF7:Ln3+ (Ln=Yb/Er and Yb/Tm) nanocrystals  

NASA Astrophysics Data System (ADS)

Lanthanide-doped Ba2LaF7 nanocrystals have been successfully synthesized via a modified liquid-solid-solution process. The yielded nanocrystals are determined to be pure cubic Ba2LaF7 phase and consist of nearly square-shaped nanoparticles with an average 14 nm in size. The Yb3+/Er3+ (Tm3+) co-doped Ba2LaF7 nanocrystals emit bright multicolor upconversion luminescence following the excitation of 980 nm laser diode. Proposed mechanisms for the emission were analyzed based on the emission spectra and their dependence on pumping power, as well as corresponding energy level diagram.

Li, Wenbin; Tan, Congbing; Zhang, Yutao

2013-02-01

58

Intense white light emission in Tm3+/Er3+/Yb3+ co-doped Y2O3-ZnO nano-composite  

NASA Astrophysics Data System (ADS)

The Tm3+/Er3+/Yb3+ co-doped Y2O3-ZnO nano-composite is synthesized using the solution combustion technique. The structural morphology is monitored using x-ray diffraction, transmission electron microscopy and scanning electron microscopy. The Yb3+/Tm3+ co-doped nano-phosphor emits intense blue as well as weak red emissions, while Yb3+/Er3+ co-doped nano-phosphor emits strong green along with red emissions on excitation with 976 nm laser. Joining these together (i.e. Tm3+/Er3+/Yb3+ co-doped phosphor) give very strong white light, which is further verified by CIE coordinates (0.32, 0.36). The addition of ZnO with Y2O3 phosphor gives further enhancement in the intensity of white light. The possible reason for this enhancement is the removal of optical quenching sites.

Yadav, R. S.; Verma, R. K.; Rai, S. B.

2013-07-01

59

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

NASA Astrophysics Data System (ADS)

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.

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

2014-11-01

60

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

SciTech Connect

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.

Roudebush, John H.; Grebenkemper, Jason; Hu, Yufei; Kazem, Nasrin [Department of Chemistry, University of California, Davis, CA 95616 (United States); Abdusalyamova, M.N. [The Institute of Chemistry of the Tajik Academy of Sciences, 229/2, Aini Street, 734063 Dushanbe (Tajikistan); Kauzlarich, Susan M., E-mail: smkauzlarich@ucdavis.edu [Department of Chemistry, University of California, Davis, CA 95616 (United States)

2014-03-15

61

Field-Induced Magnetic Properties in RCrO 4 Oxides ( R=Pr, Gd, Tb, Tm, and Yb)  

NASA Astrophysics Data System (ADS)

RCrO4 oxides (R=Pr, Gd, Tb, Tm, and Yb) have been synthesized at 773 K using the corresponding nitrates as precursors. X-ray diffraction data reveal that these samples are single phases and crystallize with the zircon-type structure, showing tetragonal symmetry, space group I41/amd. All the compounds are antiferromagnetic and the Nel temperature, which depends on the R3+ ion, takes values lower than 30 K. The presence of a canting appears to be responsible for the negative values of the magnetic susceptibility found below the compensation temperature. This uncommon phenomenon is named reversal of magnetization. It is field-dependent, being suppressed at 500 Oe for the TmCrO4 compound. The highest value of the compensation temperature (24 K) corresponds to the YbCrO4 oxide. A metamagnetic transition has been observed in all cases at critical fields ranging from 225 Oe (GdCrO4) to 1600 Oe (YbCrO4).

Jimnez, E.; Isasi, J.; Sez-Puche, R.

2002-03-01

62

MOLTEN SALT SYNTHESIS OF YF3:Yb3+/Ln3+(Ln = Er3+, Tm3+) MICROSHEETS WITH MULTICOLOR UPCONVERSION LUMINESCENCE  

NASA Astrophysics Data System (ADS)

In this paper, highly crystalline YF3:Yb3+/Ln3+(Ln = Er3+, Tm3+) microsheets were successfully synthesized by a surfactant-free molten salt method for the first time. The results indicated that the as-obtained samples belonged to orthorhombic system and exhibited microsheets morphology with side lengths of 30 to 80 ?m and wall thickness from 1 to 1.5 ?m. By changing the dopant's species (Ln3+), multicolor (yellow and blue) upconversion emission can be observed in YF3:Yb3+/Ln3+ microsheets under 980 nm laser diode (LD) excitation. The upconversion mechanisms in co-doping YF3 samples were analyzed in detail based on the emission spectra. Importantly, this approach not only proposes a new alternative in synthesizing such materials, but also opens the possibility to meet the increasing commercial demand.

Ding, Mingye; Lu, Chunhua; Cao, Linhai; Ni, Yaru; Xu, Zhongzi

2013-12-01

63

Highly improved upconversion luminescence in NaGd(WO4)2:Yb3+/Tm3+ inverse opal photonic crystals  

NASA Astrophysics Data System (ADS)

The upconversion luminescence (UCL) of rare earth (RE) ions doped nanomaterials has attracted extensive interest because of its wide and great potential applications. However, the lower UCL efficiency is still an obstacle for real applications. Photonic modulation is a novel way to improve the efficiency of UCL. In this work, NaGd(WO4)2:Yb3+/Tm3+ inverse opal photonic crystals (IOPCs) were fabricated through the polymethylmethacrylate (PMMA) template and the modification of the IOPC structure on the emission spectra and dynamics of Tm3+ ions was systemically studied. It is interesting to observe that in the IOPCs, the high-order UCL 1D2-3H6/3F4 was relatively enhanced. At the same time, the local thermal effect induced by laser irradiation was suppressed. Furthermore, the overall intensity ratio of visible UCL to near-infrared (NIR) down-conversion luminescence (DCL) was 2.8-8 times improved than that of the grinded reference (REF) and independent of the photonic stop band (PSB). The studies on UCL dynamics indicated that the nonradiative transition rate of Tm3+ was considerably suppressed. The facts above indicated that in the IOPCs the UCL efficiency of Tm3+ was largely improved due to the periodic macroporous structure.The upconversion luminescence (UCL) of rare earth (RE) ions doped nanomaterials has attracted extensive interest because of its wide and great potential applications. However, the lower UCL efficiency is still an obstacle for real applications. Photonic modulation is a novel way to improve the efficiency of UCL. In this work, NaGd(WO4)2:Yb3+/Tm3+ inverse opal photonic crystals (IOPCs) were fabricated through the polymethylmethacrylate (PMMA) template and the modification of the IOPC structure on the emission spectra and dynamics of Tm3+ ions was systemically studied. It is interesting to observe that in the IOPCs, the high-order UCL 1D2-3H6/3F4 was relatively enhanced. At the same time, the local thermal effect induced by laser irradiation was suppressed. Furthermore, the overall intensity ratio of visible UCL to near-infrared (NIR) down-conversion luminescence (DCL) was 2.8-8 times improved than that of the grinded reference (REF) and independent of the photonic stop band (PSB). The studies on UCL dynamics indicated that the nonradiative transition rate of Tm3+ was considerably suppressed. The facts above indicated that in the IOPCs the UCL efficiency of Tm3+ was largely improved due to the periodic macroporous structure. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr05688d

Wang, Yunfeng; Xu, Wen; Cui, Shaobo; Xu, Sai; Yin, Ze; Song, Hongwei; Zhou, Pingwei; Liu, Xiaoyan; Xu, Lin; Cui, Haining

2015-01-01

64

Controllable and white upconversion luminescence in LiNbO3:Ln3+ (Ln = Ho, Yb, Tm) single crystals  

NASA Astrophysics Data System (ADS)

Ho3+, Yb3+ and Tm3+ tri-doped LiNbO3 single crystals with various dopant concentrations were prepared by Czochralski method. Controllable and white upconversion emissions are generated under 980 nm excitation at room temperature. The variations of upconversion spectra and CIE coordinates with dopant concentrations and pump powers are studied in details on the basis of energy transfer processes. Ideal white-light emissions can be obtained even though the pump power is varied from 100 to 900 mW. Based on the present experiments, great inspirations are given in realizing the target color of interest by varying dopant concentrations and pump powers.

Xing, Lili; Xu, Yanling; Wang, Rui; Xu, Wei; Gu, Shuo; Wu, Xiaohong

2013-07-01

65

Tunable multicolor and white-light upconversion luminescence in Yb(3+) /Tm(3+) /Ho(3+) tri-doped NaYF4 micro-crystals.  

PubMed

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. Copyright 2014 John Wiley & Sons, Ltd. PMID:25377774

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

2014-11-01

66

Self-assembled RE2(MO4)3:Ln3+ (RE = Y, La, Gd, Lu; M = W, Mo; Ln = Yb/Er, Yb/Tm) hierarchical microcrystals: Hydrothermal synthesis and up-conversion luminescence  

NASA Astrophysics Data System (ADS)

RE2(MO4)3:Ln3+ (RE = Y, La, Gd, Lu; M = W, Mo; Ln = Yb/Er, Yb/Tm) microstructures with uniform shapes and sizes were synthesized via a hydrothermal method in the presence of hexadecyl trimethyl ammonium bromide (CTAB). The structure and morphology of the as-prepared microcrystals were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), selected area electron diffraction (SAED) and high-resolution transmission electron microscopy (HRTEM). The 3D hierarchical architectures of Y2(MoO4)3:Yb3+/Er3+ and Gd2(WO4)3:Yb3+/Er3+ are self-assembled by numerous nanoflakes. The up-conversion (UC) luminescence properties of these samples were investigated. Obvious differences in up-converted emission spectra among the as-obtained products were observed, and possible reasons were discussed. The corresponding up-conversion mechanism was also proposed.

Zhou, You; He, Xiang-Hong; Yan, Bing

2014-01-01

67

Up-conversion fluorescence and thermal optical bistability in Gd 2O 3: 10% Yb 3+, 0.5% Tm 3+  

NASA Astrophysics Data System (ADS)

Through a co-precipitation method Gd(OH) 3: 0.5% Tm 3+, 10% Yb 3+ powder was synthesized. After sintering at different temperatures, the as-prepared Gd(OH) 3: 0.5% Tm 3+, 10% Yb 3+ powder was changed into cubic and monoclinic phase Gd 2O 3: 0.5% Tm 3+, 10% Yb 3+ phosphors. Crystalline phases and morphologies of as-prepared powder and phosphors were characterized by X-ray diffraction (XRD) and field emission scanning electron microscope (FE-SEM). Up-conversion (UC) fluorescence spectra of Gd 2O 3: 0.5% Tm 3+, 10% Yb 3+ phosphors were recorded by a fluorescence spectrophotometer with a 980 nm continuous wave laser diode as the excitation source. Fluorescence decay behaviors of the phosphors were measured by exciting with 980 nm from an optical parametric oscillator (OPO) pumped by a pulsed Nd: YAG laser with a pulse duration of 10 ns and a repetition frequency of 10 Hz, and the signal was recorded using a monochromator and an oscillograph. Phase and excitation power dependent UC fluorescence properties of the phosphors were studied in detail in the article. Interestingly, the cubic phase phosphors presented thermal optical bistability phenomena. The fluorescence dynamic analysis indicated that rise and decay processes existed in the phosphor UC fluorescence.

Cao, Chunyan; Zhang, Xianmin; Chen, Minglun; Qin, Weiping; Zhang, Jisen

2010-09-01

68

Features of the formation of magnetic moments of Tm3+ and Yb3+ rare-earth ions in LuB12 cage glass  

NASA Astrophysics Data System (ADS)

The features of the formation of the magnetic moments of Tm3+ and Yb3+ ions in a metallic matrix of LuB12 cage glass have been studied in measurements of the magnetization and specific heat in the temperature range of 1.9-300 K in magnetic fields up to 90 kOe. It has been shown that a paramagnetic response from the localized moments of isolated ions Tm3+ (7.6?B) and Yb3+ (4.5?B) is observed at temperatures of 150-300 K. A transition to the cage glass phase at low temperatures ( T ? T* 60 K) is accompanied by disordering in the system of rare-earth ions and by formation of many-body states near Tm3+ and Yb3+ ions. At low temperatures near T m in low magnetic fields, the appearance of an additional spin polarization, which is suppressed with an increase in the field, has been observed. The effective moments and g-factors of Tm and Yb obtained in high fields imply both the binding of a small fraction of magnetic ions to antiferromagnetic dimers and the ?6 ground state of the 2 F 7/2 multiplet of the ytterbium ion. A scenario alternative to the Kondo-type behavior has been proposed to explain the nature of many-body states and the appearance of the spin polarization in rare-earth dodecaborides.

Sluchanko, N. E.; Azarevich, A. N.; Anisimov, M. A.; Bogach, A. V.; Voronov, V. V.; Gavrilkin, S. Yu.; Glushkov, V. V.; Demishev, S. V.; Kuznetsov, A. V.; Mitsen, K. V.; Filippov, V. B.; Shitsevalova, N. Yu.; Gabani, S.; Flachbart, K.

2014-12-01

69

Color control and white upconversion luminescence of LaOF:Ln3+ (Ln = Yb, Er, Tm) nanocrystals prepared by the sol-gel Pechini method.  

PubMed

A series of Yb(3+)-Er(3+) and Yb(3+)-Er(3+)-Tm(3+) codoped LaOF nanocrystals were synthesized via a modified sol-gel Pechini method. The phases and morphologies as well as the luminescence properties of the as-prepared samples were characterized by means of X-ray diffraction (XRD), scanning electron microscopy (SEM) and upconversion luminescence (UCL) spectra, respectively. Under 980 nm near infrared (NIR) excitation, the UCL properties and the corresponding luminescent colors of the samples could be precisely modulated by changing the annealing temperatures, the dopant concentrations and the pump densities. By regulating the intensities of blue, green and red emissions in Yb(3+)-Er(3+)-Tm(3+) codoped LaOF nanocrystals, an ideal white upconversion luminescence with chromaticity coordinates of (0.331, 0.368) is obtained in La0.885Yb0.1Er0.01Tm0.005OF nanocrystals for the first time. The blue, green and red components of the white light come from the (1)G4 ? (3)H6 transition of Tm(3+), (2)H11/2/(4)S3/2 ? (4)I15/2 transitions of Er(3+) and (4)F9/2 ? (4)I15/2 transition of the Er(3+) ions, respectively. The possible physical mechanisms involved in the different upconversion processes were discussed in detail. PMID:23403723

Zheng, Kezhi; Liu, Ye; Liu, Zhenyu; Chen, Zhe; Qin, Weiping

2013-04-14

70

Structural and magnetic phase transitions in mixed-valence cobalt oxides REBaCo 4O 7 (RE=Lu, Yb, Tm)  

NASA Astrophysics Data System (ADS)

New mixed valence Co oxides REBaCo 4O 7 (RE=Lu, Yb, Tm) show structural first-order phase transitions from hexagonal (P6 3mc) to orthorhombic (Cmc2 1 or lower) system below 170, 180, and 230 K, respectively. The low-temperature phases order magnetically at 47, 75, and 105 K, respectively.

Nakayama, N.; Mizota, T.; Ueda, Y.; Sokolov, A. N.; Vasiliev, A. N.

2006-05-01

71

A comparative study on the structural properties and electrical characteristics of thin HoTixOy, TmTixOy and YbTixOy dielectrics  

NASA Astrophysics Data System (ADS)

In this paper, the authors described the structural properties and electrical characteristics of thin HoTixOy, TmTixOy and YbTixOy dielectrics deposited on Si(1 0 0) substrates through reactive co-sputtering. X-ray diffraction, x-ray photoelectron spectroscopy, secondary ion mass spectrometry and atomic force microscopy were used to study the morphological and chemical features of these films as functions of the growth conditions (temperatures ranging from 600 to 800 C). The YbTixOy gate dielectric that had been annealed at 800 C exhibited the thinnest capacitance equivalent thickness and the best electrical characteristics (frequency dispersion, hysteresis voltage and interface-trapped charge in the capacitance-voltage curves). We attribute this behavior to the YbTixOy film forming the well-crystallized Yb2TiO5 structure and improving the surface roughness. This dielectric also shows almost negligible charge trapping under high constant voltage stress.

Pan, Tung-Ming; Yen, Li-Chen; Wu, Xin-Chang

2010-05-01

72

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

SciTech Connect

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}).

Assumpcao, Thiago A. A.; Silva, Davinson M. da [Departamento de Engenharia de Sistemas Eletronicos, Escola Politecnica da USP, 05508-900 Sao Paulo, SP (Brazil); Kassab, Luciana R. P. [Laboratorio de Vidros e Datacao, Faculdade de Tecnologia de Sao Paulo (FATEC-SP), CEETEPS/UNESP, 01124-060 Sao Paulo, SP (Brazil); Araujo, Cid B. de [Departamento de Fisica, Universidade Federal de Pernambuco, 50670-901 Recife, PE (Brazil)

2009-09-15

73

A bifunctional Cr/Yb/Tm:Ca3Ga2Ge3O12 phosphor with near-infrared long-lasting phosphorescence and upconversion luminescence.  

PubMed

Currently, upconversion nanocrystals and long-lasting phosphorescent particles have attracted extensive research interest for their possible applications as bioimaging probes. However, there are few reports concerning the achievement of both upconversion luminescence of lanthanide ions and long-lasting phosphorescence of transition metal ions in a sole host so far. Herein, we demonstrate a novel calcium gallium germanium garnet (Ca3Ga2Ge3O12) host where lanthanide ions such as Tm(3+)/Yb(3+) and transition metal ions such as Cr(3+) can be easily incorporated through substituting the Ca(2+) and Ga(3+) respectively. This Cr/Yb/Tm:Ca3Ga2Ge3O12 phosphor exhibits both broadband near-infrared long-lasting phosphorescence of Cr(3+) with an afterglow time of more than 7000 s and near-infrared to near-infrared upconversion luminescence of Tm(3+). Impressively, it is evidenced that the addition of Yb(3+)/Tm(3+) into Cr:Ca3Ga2Ge3O12 not only results in Tm(3+) upconversion luminescence but also greatly increases Cr(3+) afterglow time. Based on excitation/emission, three-dimensional thermoluminescence, and time-resolved luminescence spectra, the related long-lasting phosphorescence and upconversion luminescent mechanisms are systematically discussed as well. PMID:25068770

Chen, Daqin; Chen, Yan; Lu, Hongwei; Ji, Zhenguo

2014-08-18

74

Investigation on luminescence properties of Er3+-Yb3+-Tm3+ co-doped Gd2O3 hollow microspheres  

NASA Astrophysics Data System (ADS)

The Gd2O3 hollow microspheres have been successfully fabricated via carbonaceous polysaccharide microspheres as templates and urea as a precipitating agent, which involved the deposition of an inorganic coating on the surface of carbon microsphere, followed by heat treated 800C for 4h. The obtained high uniform Gd2O3 microspheres with a spherical shape and hollow structure are uniform in size and distribution. The possible mechanism of evolution from glucose to carbonaceous polysaccharide microspheres and the chemical reaction of each step to form the final hollow spheres are proposed. The rare earth ion Ln3+ doped Gd2O3 (Ln = Er, Yb and Tm) hollow microspheres show bright up-conversion luminescence with different colors coming from different activator ions under ultraviolet or 980 nm light excitation, which may open new possibilities to synthesize other hollow spherical materials and extend their applications.

Xu, Fang; Han, Wan-lei; Liu, Xiao-bo; Song, Ying-lin

2011-06-01

75

Preparation and upconversion luminescence of beta-NaYF4:Yb3+, Tm3+/ZnO nanoparticles.  

PubMed

Beta-NaYF4:Yb3+, Tm3+/ZnO core/shell nanoparticles (NPs) were synthesized via a high temperature thermal decomposition method. The as-synthesized core/shell NPs were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and upconversion luminescence spectra (UCL). Under 980 nm laser excitation, the measured intensity of upconversion luminescence (1I6 --> 3H6, 1I6 --> 3F4, and 1D2 --> 3H6) was different with and without ZnO. During the sample preparations, changing the ratio of the solvent affected the ZnO UV absorption efficiency. The results show that the NIR light can be used as the driving source to excite ZnO, thus extending utility rate to the NIR spectral region and enhancing the light harvest rate. PMID:24734622

Guo, Xingyuan; Song, Weiye; Wang, Jianshuo; Shi, Feng; Qin, Weiping

2014-05-01

76

Investigation on upconversion luminescence properties of Gd2O3: Ho3+/Yb3+/Tm3+ nanotubes  

NASA Astrophysics Data System (ADS)

Lanthanide doped oxides nano materials have novel optical, physical and structural properties. Cubic Ho3+-Yb3+-Tm3+ co-doped Gd2O3 nanotubes are synthetize by a simple wet-chemical route at low temperature and ambient pressure followed by subsequent annealing heat treatment in muffle furnace. Nanotubes are formed by adjusting the pH value of reacting solution. The introduction of Yb3+ leads to strong visible upconversion luminescence and change the intensity ratio of the green, blue and red luminescence. In trichromatic laser display, research of how to enhance blue light is in the bottleneck period. In the experiment, the blue emission has been successfully improved. In certain doping ratio, distinct enhancement of blue emission and obvious degradation of green light have been observed, which is discussed in detail. X-Ray powder diffraction (XRD), scanning electron microscope (SEM) and upconversion (UC) emission spectra are used to characterize the sample. Strong and adjusted upconversion luminescence determine that the nano material is a potential candidate for applications of biological probe, color displays, lighting and photonics.

Ye, Fei; Fang, Yu; Liu, Xiao-bo; Xu, Fang; Song, Ying-lin

2013-09-01

77

Hydrothermal synthesis and upconversion luminescence properties of ?-NaGdF4:Yb3+/Tm3+ and ?-NaGdF4:Yb3+/Ho3+ submicron crystals with regular morphologies.  

PubMed

Single phase ?-NaGdF(4):Yb(3+)/Tm(3+) and ?-NaGdF(4):Yb(3+)/Ho(3+) submicron crystals with various morphologies including hexagonal prisms, spindles, and spheres were synthesized via the one-step hydrothermal method by controlling the pH values and sort of chelators (EDTA and citric acid). The prepared products showed intense up-converted luminescence (UCL) pumped by infrared laser at 980 nm. The hexagonal prisms that meaning high degree crystallinity demonstrated strong UCL in comparison with other morphologies such as spindles and spheres. In ?-NaGdF(4):Yb(3+)/Tm(3+), UCL not only appeared transitions from (1)G(4), (1)D(2), and (1)I(6) states to the lower lying states of Tm(3+), but also (6)P(J)?(8)S(7/2) transition (310 nm) of Gd(3+). These UCL were responsible for three, five, and six photons processes determined by pump power dependence of UCL intensities. The observation of UCL of Gd(3+) implied occurrence of energy transfer from Tm(3+):(1)I(6) to Gd(3+):(6)P(J). PMID:23141700

Li, Jing; Hao, Zhendong; Zhang, Xia; Luo, Yongshi; Zhao, Jihong; L, Shaozhe; Cao, Jian; Zhang, Jiahua

2013-02-15

78

Spectral analysis of Er(3+)-, Er(3+)/Yb(3+)-and Er(3+)/Tm(3+)/Yb(3+)-doped TeO(2)-ZnO-WO(3)-TiO(2)-Na(2)O glasses.  

PubMed

In this paper, we present the spectroscopic properties of Er(3+)-, Er(3+)/Yb(3+)-and Er(3+)/Tm(3+)/Yb(3+)-doped novel tellurite glasses. From the measured absorption spectra, Judd-Ofelt (JO) intensity parameters (?(2), ?(4) and ?(6)) have been evaluated for the Er(3+)-doped glass. With 980nm excitation three strong upconversion emission bands centered at 505, 520 and 630nm were observed for both Er(3+)-and Er(3+)/Yb(3+)-codoped glasses and the characteristic near-infrared emission bands were spectrally centered at 1.535m. The near-infrared spectra of Er(3+)-and Er(3+)/Yb(3+)-doped glasses have shown full width at half-maxima (FWHM) around 100nm and 120nm for the erbium [Formula: see text] transition, respectively. The measured maximum decay times of the [Formula: see text] transition (at wavelength 1.535m) are about 7.24ms and 7.68ms for 1.0Er(3+) and 1.0Er(3+)/ 2Yb(3+) (mol%)-codoped glasses, respectively. The maximum stimulated emission cross sections for the [Formula: see text] transition of Er(3+) and Er(3+)/Yb(3+) are 8.64 10(-21) and 6.78 10(-21)cm(2). From 1Er(3+)/ 1Tm(3+)/ 2Yb(3+) (mol%)-codoped glass, broad near-infrared emission bands centered at 1510nm ([Formula: see text]) and 1637nm ([Formula: see text]) with full width at half-maxima (FWHM) around 52nm and 60nm, respectively, were observed. These glasses with broad near-infrared emissions should have potential applications in tunable lasers and broadband optical amplification at low-loss telecommunication windows. PMID:21694435

Lakshminarayana, G; Qiu, Jianrong; Brik, M G; Kumar, G A; Kityk, I V

2008-09-17

79

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

SciTech Connect

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.

Rakov, Nikifor [PG-Ciencia dos Materiais, Universidade Federal do Vale do Sao Francisco, 48902-300 Juazeiro, BA (Brazil); Amaral, Dayanne F.; Guimaraes, Renato B.; Maciel, Glauco S. [Instituto de Fisica, Universidade Federal Fluminense, 24210-346 Niteroi, RJ (Brazil)

2010-10-15

80

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

SciTech Connect

{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.

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

81

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

PubMed

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

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

2014-10-13

82

Bright white upconversion luminescence in Ho3+/Yb3+/Tm3+ triple doped CaWO4 polycrystals  

NASA Astrophysics Data System (ADS)

Ho3+/Yb3+/Tm3+ triple doped CaWO4 polycrystals are synthesized by a sample high temperature solid state method. The crystal structure of the polycrystals is characterized by means of X-ray diffraction.Under single-wavelength diode laser excitation of 980 nm, the bright white light consists of the blue, green, and red upconversion radiations which correspond to the transitions 1G4?3H6 of Tm3+ ions, 5S2/5F4?5I8 and 5F5?5I8 of Ho3+ ions, respectively. The pump power plays an important role in the blue upconversion emission intensity, and it helps to the adjustment of the white upconversion emission chrominance. The calculated color coordinates display that white light can be achieved by adjusting pump powers. The CIE coordinate close to (0.33, 0.33) is potentially suitable for the widely realistic application in the field of displays, lasers, and lighting technology. The possible upconversion mechanisms are investigated and discussed.

Xu, Yanling; Wang, Yunlong; Shi, Liansheng; Xing, Lili; Tan, Xiang

2013-12-01

83

Survey and research on up-conversion emission character and energy transition of Yb3+/Er3+/Tm3+ co-doped phosphate glass and glass ceramic  

NASA Astrophysics Data System (ADS)

By conventional high-temperature melting method, Yb3+/Er3+/Tm3+ co-doped phosphate glass was synthesized. After annealing the precursor glass, the phosphate glass ceramic (GC) was obtained. By measuring the X-ray diffraction (XRD) spectrum, it is proved that the LiYbP4O12 and Li6P6O18 nano-crystals have existed in the phosphate GC. The up-conversion (UC) emission intensity of the GC is obvious stronger compared to that of the glass. The reason is that the shorter distance between rare earth ions in the glass ceramic increases the energy transitions from the sensitized ions (Yb3+) to the luminous ions (Er3+ and Tm3+). By studying the dependence of UC emissions on the pump power, the 523 and 546 nm green emissions of Er3+ ions in the glass are two-photon processes. But in the glass ceramic, they are two/three-photon processes. The phenomenon implies that a three-photon process has participated in the population of the two green emissions. Using Dexter theory, we discuss the energy transitions of Er3+ and Tm3+. The results indicate the energy transition of Tm3+ to Er3+ is very strong in the GC, which changes the population mechanism of UC emissions of Er3+.

Yu, Yin; Song, Feng; Ming, Chengguo; Liu, Jiadong; Li, Wei; Liu, Yanling; Zhao, Hongyan

2012-11-01

84

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

NASA Astrophysics Data System (ADS)

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.

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

2014-02-01

85

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

PubMed

Synthesis of Eu(3+)- and Er(3+)/Yb(3+)-doped GdVO4 nanoparticles in reverse micelles and their multifunctional luminescence properties are presented. Using cyclohexane, Triton X-100, and n-pentanol as the oil, surfactant, and co-surfactant, respectively, crystalline nanoparticles with ~4?nm diameter are prepared at low temperatures. The particle size assessed using transmission electron microscopy is similar to the crystallite size obtained from X-ray diffraction measurements, suggesting that each particle comprises a single crystallite. Eu(3+)-doped GdVO4 nanoparticles emit red light through downconversion upon UV excitation. Er(3+)/Yb(3+)-doped GdVO4 nanoparticles exhibit several functions; apart from the downconversion of UV radiation into visible green light, they act as upconvertors, transforming near-infrared excitation (980?nm) into visible green light. The ratio of green emissions from (2)H11/2 ? (2)I15/2 and (4)S3/2 ? (4)I15/2 transitions is temperature dependent and can be used for nanoscale temperature sensing with near-infrared excitation. The relative sensor sensitivity is 1.11%K(-1), which is among the highest sensitivities recorded for upconversion-luminescence-based thermometers. PMID:24572638

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

2014-01-01

86

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

PubMed Central

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

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

2014-01-01

87

White upconversion luminescence in Tm3+/Ho3+/Yb3+ triply doped K+-Na+ ion-exchanged aluminum germanate glass channel waveguide  

NASA Astrophysics Data System (ADS)

Rare-earth ions doped K+-Na+ ion-exchanged aluminum germanate (NMAG) glass channel waveguides have been designed and fabricated. Under 980 nm laser pumping, an intense upconversion white light transmission trace was observed in Tm3+/Ho3+/Yb3+ triply doped NMAG glass channel waveguide and a high-brightness light spot was achieved from the output end of the fiber connected to the waveguide channel. The fluorescent colors were diverse and located within or near the white region in CIE chromaticity diagram under various pumping powers. These admirable results indicate that Tm3+/Ho3+/Yb3+ triply doped NMAG channel waveguide is a promising light source for medical and high-precision processing illumination.

Liu, Xiao; Chen, Baojie; Pun, Edwin Yue Bun; Lin, Hai

2013-01-01

88

Characteristics of rare earth (RE = Eu, Tb, Tm)-doped Y2O3 phosphors for thermometry.  

PubMed

The temperature-dependent photoluminescences of Y(2)O(3) : Eu (6% Eu), Y(2)O(3) : Tb (4% Tb) and Y(2)O(3) : Tm (1% Tm) were investigated for high-temperature phosphor thermometry. Two different phases, the monoclinic phase and cubic phase, were considered because the fluorescence spectra vary with the phase. To employ the intensity ratio method, we investigated their photoluminescence spectra under the excitation light of an Hg-Xe lamp as the temperature was elevated from room temperature to more than 1200 K. As a result, it was confirmed that the luminescence intensity of all of the phosphors varied with elevating temperature, i.e. thermal quenching, with the variations depending on the type of rare earth impurity and their phases. The results indicate that Y(2)O(3) : Eu phosphors are applicable to the intensity ratio method because they show appropriate variations in the intensity ratio of two emission lines, and they also have strong and sharp peak intensities without excessive optical noise or black body radiation over a wide range of temperatures. The intensity ratios for Y(2)O(3) : Tb provide such small variations with temperature that the temperature resolution is low, despite the strong emission intensities. As for Y(2) O(3) :Tm, the intensity ratios also have a low temperature resolution and their emission intensities are weak. Therefore, Y(2)O(3) : Tb and Y(2)O(3) : Tm are not appropriate for the intensity ratio method for phosphor thermometry. PMID:20737651

Ishiwada, Naohiro; Ueda, Toshihisa; Yokomori, Takeshi

2011-01-01

89

A spectroscopic analysis of blue and ultraviolet upconverted emissions from Gd3Ga5O12:Tm3+, Yb3+ nanocrystals.  

PubMed

The spectroscopic behavior of gadolinium gallium garnet (Gd3Ga5O12, GGG) nanocrystals codoped with 1% each of Tm3+ and Yb3+ prepared via a solution combustion synthesis procedure was investigated. Initial excitation of the codoped nanocrystals with 465.8 nm (into the 1G4 state) showed a dominant blue-green emission ascribed to the 1G4-3H6 transition as well as red and NIR emissions from the 1G4-3F4 and 1G4-3H5/3H4-3H6 transitions, respectively. Excitation at this wavelength (465.8 nm) showed the existence of a Tm3+ --> Yb3+ energy transfer process evidenced by the presence of the 2F5/2-2F7/2 Yb3+ emission in the NIR emission spectrum. The decay time constants proved that the transfer of energy occurred via the 3H4 state. Following excitation of the Yb3+ ion with 980 nm, intense upconverted emission was observed. Emissions in the UV (1D2-3H6), blue (1D2-3F4), blue-green (1G4-3H6), red (1G4-3F4), and NIR (1G4-3H5/3H4-3H6) were observed and were the direct result of subsequent transfers of energy from the Yb3+ ion to the Tm3+ ion. Power dependence studies showed a deviation from expected values for the number of photons involved in the upconversion thus indicating a saturation of the upconversion process. An energy transfer efficiency of 0.576 was determined experimentally. PMID:16853224

Pandozzi, Fabiano; Vetrone, Fiorenzo; Boyer, John-Christopher; Naccache, Rafik; Capobianco, John A; Speghini, Adolfo; Bettinelli, Marco

2005-09-22

90

A comparative study on the structural properties and electrical characteristics of thin HoTixOy, TmTixOy and YbTixOy dielectrics  

Microsoft Academic Search

In this paper, the authors described the structural properties and electrical characteristics of thin HoTixOy, TmTixOy and YbTixOy dielectrics deposited on Si(1 0 0) substrates through reactive co-sputtering. X-ray diffraction, x-ray photoelectron spectroscopy, secondary ion mass spectrometry and atomic force microscopy were used to study the morphological and chemical features of these films as functions of the growth conditions (temperatures

Tung-Ming Pan; Li-Chen Yen; Xin-Chang Wu

2010-01-01

91

Experimental study on the surface modification of Y2O3:Tm3+\\/Yb3+ nanoparticles to enhance upconversion fluorescence and weaken aggregation  

Microsoft Academic Search

In order to improve the solubility of doped nanoparticles in solutions, Y2O3:Tm3+\\/Yb3+ nanoparticles were synthesized using the Pechini-type solgel method, and their surfaces were modified with amino or carboxylic functional groups using ligand-capped and ligand-exchanging methods. The nanoparticles with modified surfaces were characterized by transmission electron microscopy (TEM), Fourier transform infrared (FT-IR) spectroscopy and zeta potential (?), and their photoluminescence

Qiang L; AiHua Li; FengYun Guo; Liang Sun; LianCheng Zhao

2008-01-01

92

Tuning upconversion luminescence of LiYF4:Yb3+,Er3+/Tm3+/Ho3+ microcrystals synthesized through a molten salt process.  

PubMed

In this paper, well-defined tetragonal-phase LiYF4:Yb3+,Er3+/Tm3+/Ho3+ micro-crystals with octahedral morphology were successfully prepared through a surfactant-free molten salt process for the first time. By gradually increasing the LiF content in the NaNO3-KNO3 reaction medium, the crystal phase transforms from a mixture of YF3 and LiYF4 to pure tetragonal-phase LiYF4. The possible formation process for the phase and morphology evolution is also presented. Moreover, upon 980 nm laser diode (LD) excitation, the lanthanide ions (Yb3+, Er3+/Tm3+/Ho3+) doped LiYF4 crystals exhibit intense upconversion emission lights. By tuning the sensitizer concentrations of Yb3+ ions in LiYF4:Yb3+,Er3+, the relative intensities of green and red emissions can be precisely adjusted under single wavelength excitation. Consequently, multicolor upconversion emissions can be obtained. On the other hand, UC mechanisms were also given based on the emission spectra and the plot of luminescence intensity to pump power. PMID:24734579

Niu, Na; He, Fei; Wang, Liuzhen; Wang, Lin; Wang, Yan; Gai, Shili; Yang, Piaoping

2014-05-01

93

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

SciTech Connect

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.

Sluchanko, N. E., E-mail: nes@lt.gpi.ru; Azarevich, A. N.; Bogach, A. V.; Glushkov, V. V.; Demishev, S. V. [Russian Academy of Sciences, Prokhorov General Physics Institute (Russian Federation); Levchenko, A. V.; Filippov, V. B.; Shitsevalova, N. Yu. [National Academy of Sciences of Ukraine, Institute of Problems of Materials Science (Ukraine)

2013-05-15

94

Structure, enhancement and white luminescence of multifunctional Lu?O?F?:20%Yb?,1%Er?(Tm?) nanoparticles via further doping with Li? under different excitation sources.  

PubMed

A series of Lu6O5F8:20%Yb(3+),1%Er(3+)(Tm(3+)),x%Li(+) (0 ? x ? 12) nanoparticles with average size from 20 to 320 nm upon increasing Li(+) concentration were prepared by a coprecipitation method. The detailed crystal structure of Lu6O5F8 as a new matrix is firstly analysed via retrieved refinement of the powder X-ray diffraction (XRD). In addition, the corresponding Powder Diffraction File card information was also obtained through indexing the XRD pattern of the host. Upconversion under excitation at 980 nm, downconversion with Xe lamp as excitation source and cathodoluminescence properties of Lu6O5F8:20%Yb(3+),1%Er(3+)(Tm(3+)),x%Li(+) (0 ? x ? 12) nanoparticles were compared and studied. It is worthwhile pointing out that according to the effects of Li(+) on emission intensity ratio, white UC emission was achieved in the Lu6O5F8:6%Yb(3+),0.3%Er(3+),0.4%Tm(3+),5%Li(+) compared to Li(+) free sample with the same activator concentration. The reasons behind this behavior were presented and discussed. All in all, Li(+) ion would be a wonderful luminescence intensifier for lanthanide ions, and the multifunctional lanthanide ion-doped Lu6O5F8 nanoparticles have potential application in photoluminescence areas and field emission display devices. PMID:23411671

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

2013-03-21

95

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

NASA Astrophysics Data System (ADS)

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.

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

2015-01-01

96

Cross-relaxation induced tunable emissions from the Tm(3+)/Er(3+)/Eu(3+) ions activated BaGd2O4 nanoneedles.  

PubMed

Tm(3+), Er(3+), Tm(3+)/Er(3+), Tm(3+)/Er(3+)/Eu(3+) single, double and triple activator ion/ions doped nanocrystalline BaGd2O4 (BG) phosphors were prepared by a Pechini type sol-gel process. After annealing at 1300 C, X-ray diffraction patterns confirmed their orthorhombic structure. Field-emission transmission electron microscope images of the BG sample indicated a nanoneedle-type morphology. Photoluminescence (PL) and cathodoluminescence (CL) measurements were utilized to establish the emission properties of rare-earth ions doped nanocrystalline BG host lattice. Under near-ultraviolet (NUV) excitations, BG:Tm(3+) and BG:Er(3+) exhibited their characteristic emissions in the blue and green regions, respectively, while BG:Tm(3+)/Er(3+) and BG:Tm(3+)/Er(3+)/Eu(3+) showed cyan and white light emissions, respectively, when doped with appropriate amounts of activator ions. In the PL, the cross-relaxation process is dominant rather than the energy transfer process. Due to the different mechanism from PL, the CL spectra showed different emission features of BG:Tm(3+)/Er(3+)/Eu(3+) phosphor. The CL spectra of BG:Tm(3+) and BG:Er(3+) established the high purity blue and green emissions, respectively. From the PL and CL investigations, the white-light emission was realized from the single-phase BG:Tm(3+)/Er(3+)/Eu(3+) phosphor under NUV and low voltage electron beam excitations. PMID:24846293

Seeta Rama Raju, G; Pavitra, E; Yu, Jae Su

2014-07-01

97

Syntheses, structures and photophysical properties of heterotrinuclear Zn2Ln clusters (Ln = Nd, Eu, Tb, Er, Yb).  

PubMed

Heterotrinuclear Zn(2)Ln (Ln = Nd 2, Eu 3, Tb 4, Er 5, Yb 6) clusters [(Znq(2))(2)](mu-CH(3)COO){Ln(hfac)(2)} (q = 8-hydroxylquinolinate, hfac = hexafluoroacetylacetonate) have been synthesized. The Zn(2)Ln framework is ligated by two q ligands featuring mu-phenoxo and two q ligands featuring mu(3)-phenoxo coordination modes, and one mu-CH(3)COO(-) anions. Since the short intramolecular separations of Zn...Ln (ca. 3.354-3.373 A) allow energy transfer from Znq(2)-based sensitizers to the Ln(III) centres through two energy transfer pathways, the lanthanide luminescence is indeed "lighted up" by excitation of the Znq(2)-based chromopores. Photophysical measurements revealed that these Zn(2)Ln complexes exhibit the so-called "dual emission" originating from both Znq(2)-based luminophores and lanthanide emitters. By virtue of the dual luminescence with complementary colours, the Znq(2)-based cyan emission and Eu(III)-centred red luminescence are combined to generate a white-light emission in the Zn(2)Eu (3) complex. PMID:20490402

Xu, Hai-Bing; Zhong, Ye-Teng; Zhang, Wei-Xiong; Chen, Zhong-Ning; Chen, Xiao-Ming

2010-06-28

98

Synthesis and luminescence properties of LaVO4:RE3+ (RE = Sm, Eu, Tb, Tm) phosphors.  

PubMed

Rare earth (RE)-doped lanthanide vanadate phosphors for multicolor display applications were synthesized with different activator ions by using a solid-state reaction method. The effects of activator ions on the structural, morphological, and optical properties of lanthanide vanadate phosphors were investigated. X-ray diffaction data exhibited that the main peak of the phosphors occurs at a (120) plane. Maximum grain size and hexagonal morphology are observed by incorporating Eu3+ activator ions into a host lattice. The emission spectra of RE ions-doped LaVO4 phosphors under excitation at 324 nm consist of multicolor emissions: the main red emission for Eu3+, Orange for Tm3+, green for Tb3+, and blue for Tm3+ activator ions. These results suggest that the multicolor emissions can be realized by controlling activator ions incorporated into host crystals. PMID:24245289

Cho, Shinho

2013-11-01

99

Luminescence properties of Tb3+, Eu3+, Tm3+ co-doped Na5La(MoO4)4 for white light-emitting diode.  

PubMed

Tb3+, Eu3+, Tm3+ co-doped Na5La(MoO4)4 phosphors were prepared by the conventional solid-state reaction. Under the excitation of UV light, Na5La(MoO4)4:Tm3+, Na5La(MoO4)4:Tb3+, and Na5La(MoO4)4:Eu3+ exhibit the characteristic emissions of Tm3+ (1D2 --> 3F4, blue), Tb3+ (5D4 --> 7F5, green), and Eu3+ (5D0 --> 7F2, red), respectively. By adjusting the doping concentration of rare earth ions in Na5La(MoO4)4:a Tm3+, b Tb3+, c Eu3+, a white emission in a single composition was obtained under the excitation of 362 nm. It might be a promising phosphor for the future applications. PMID:24734613

Jin, Ye; L, Wei; Zhang, Jiahua; Hao, Zhendong; Zhang, Xia

2014-05-01

100

(?h11/2)" States expected in 68150Er82, 69151Tm82 and 70152Yb82  

NASA Astrophysics Data System (ADS)

Predictions are made for the spectra associated with the ( ?h 11/2) n configuration when n=4, 5 and 6. Since{64/146}Gd82 acts as if it is a closed shell, these states are expected to be low-lying in the nuclei{68/150}Er82,{69/151}Tm82 and{70/152}Yb82. The residual h 11/2 interaction is taken from the experimental spectrum of{66/148}Dy82 and it is shown that this conserves seniority to a high degree. Arguments are given as to why configuration mixing may be hard to detect from a study of the energy levels alone. The M1 selection rule and the number dependence of the E2 transition rates within the identical nucleon h 11/2 configuration are discussed and it is pointed out that seniority isomers should be seen in these nuclei. This prediction provides a stringent test of the configuration assignment. Formulae are given and estimates are made for the energies of the ?g 7/2 and ?d 5/2-hole states.

Lawson, R. D.

1981-03-01

101

Structural and thermoelectric properties of BaRCo4O7 (R = Dy, Ho, Er, Tm, Yb, and Lu)  

NASA Astrophysics Data System (ADS)

The structure and thermoelectric properties of a series of barium lanthanide cobaltites, BaRCo4O7 (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 P63mc. The lattice parameters a and c range from 6.26279(2) to 6.31181(6) , and from 10.22468(6) to 10.24446(15) for R = Lu to Dy, respectively. The crystal structure of BaRCo4O7 is built up from Kagome sheets of CoO4 tetrahedra, linked by triangular layers of CoO4 tetrahedra. The values of figure of merit (ZT) of the BaRCo4O7 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.

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

2011-12-01

102

Square structures and photophysical properties of Zn(2)Ln(2) complexes (Ln = Nd, Eu, Sm, Er, Yb).  

PubMed

Heterotetranuclear Zn(2)Ln(2) (Ln = Nd , Eu , Sm , Er , Yb ) complexes {Zn(2)(Mq)(2)(tpyO)(2)}{(Ln(hfac)(3))(2)} (HMq = 2-methyl-8-hydroxylquinoline, tpyOH = [2,2':6'2'']terpyridin-4'-ol, hfac = hexafluoroacetylacetonate) display novel square structures ligated by bifunctional ligands tpyO (mono- and tridentate) and Mq (chelating and bridging mu-phenoxo). These compounds exhibit sensitized lanthanide emission upon photo-excitation of ZnMq/tpy antenna chromophores. By virtue of the dual luminescence with complementary colors, the ZnMq/tpyO-based cyan emission and Sm(III)-centered orange luminescence are combined to generate a white-light emission in Zn(2)Sm(2) (4) complex. PMID:20148210

Xu, Hai-Bing; Wen, Hui-Min; Chen, Zhong-Hui; Li, Jia; Shi, Lin-Xi; Chen, Zhong-Ning

2010-02-28

103

Novel heterometal-organic complexes as first single source precursors for up-converting NaY(Ln)F4 (Ln = Yb, Er, Tm) nanomaterials.  

PubMed

First heterometal-organic single source precursors for NaYF(4) nanomaterials as a host matrix for up-conversion emission are reported. These novel heterobimetallic derivatives NaY(TFA)(4)(diglyme) (1), [Na(triglyme)(2)][Y(2)(TFA)(7)(THF)(2)] (2) and Na(2)Y(TFA)(5)(tetraglyme) (3) (TFA = trifluoroacetate), which were fully characterized by elemental analysis, FT-IR and (1)H NMR spectroscopy, TG-DTA data as well as single crystal X-ray structures, are advantageous in terms of being anhydrous and having lower decomposition temperatures in comparison to the homometallic precursor Y(TFA)(3)(H(2)O)(3). In addition, they also contain chelating glyme ligands, which act as capping reagents during decomposition to control the NaYF(4) particle size and render them monodisperse in organic solvents. On decomposition in 1-octadecene, the molecular derivatives 1 and 3 are converted, in the absence of any surfactant or capping reagent, to cubic NaYF(4) nanocrystals at significantly lower temperatures (below 250 C). At higher temperature, a mixture of the cubic and hexagonal phases was obtained, the relative ratio of the two phases depending on the reaction temperature. A pure hexagonal phase, which is many folds more efficient for UC emission than the cubic phase, was obtained by calcining nanocrystals of mixed phase at 400 C. In order to co-dope this host matrix with up-converting lanthanide cations, analogous complexes NaLn(TFA)(4)(diglyme) [Ln = Er (4), Tm (5), Yb (6)] and Na(2)Ln(TFA)(5)(tetraglyme) [Ln = Er (7), Yb (8)] were also prepared and characterized. The decomposition in 1-octadecene of suitable combinations and appropriate molar ratios of these yttrium, ytterbium and erbium/thulium derivatives gave cubic and/or hexagonal NaYF(4): Yb(3+), Er(3+)/Tm(3+) nanocrystals (NCs) capped by diglyme or tetraglyme ligands, which were characterized by IR, TG-DTA data, EDX analysis and TEM studies. Surface modification of these NCs by ligand exchange reactions with poly acrylic acid (PAA) and polyethyleneglycol (PEG) diacid 600 was also carried out to render them water soluble. The THF solutions of suitable combinations of the diglyme derivatives were also used to elaborate the thin films of NaYF(4):Yb(3+), Er(3+)/Tm(3+) on a glass or Si wafer substrate by spin coating. The multicolour up-conversion fluorescence was successfully realized in the Yb(3+)/Er(3+) (green/red) and Yb(3+)/Tm(3+) (blue/violet) co-doped NaYF(4) nanoparticles and thin films, which demonstrates that they are promising UC nanophosphors of immense practical interest. The up-conversion excitation pathways for the Er(3+)/Yb(3+) and Tm(3+)/Yb(3+) co-doped materials are discussed. PMID:22134711

Mishra, Shashank; Ledoux, Gilles; Jeanneau, Erwann; Daniele, Stphane; Joubert, Marie-France

2012-02-01

104

Optical temperature sensing of NaYbF4: Tm3+@SiO2 core-shell micro-particles induced by infrared excitation.  

PubMed

NaYbF(4):Tm3+@SiO(2) core-shell micro-particles were synthesized by a hydrothermal method and subsequent ultrasonic coating process. Optical temperature sensing has been observed in NaYbF4: Tm(3+)@SiO(2)core-shell micro-particles with a 980 nm infrared laser as excitation source.The fluorescence intensity ratios, optical temperature sensitivity, and temperature dependent population re-distribution ability from the thermally coupled (1)D(2)/(1)G(4) and (3)F(2) /(3)H(4) levels of the Tm(3+) ion have been analyzed as a function of temperature in the range of 100~700 K in order to check its availability as a optical temperature sensor. A better behavior as a lowtemperature sensor has been obtained with a minimum sensitivity of 5.4 10(-4) K(-1) at 430 K. It exhibits temperature induced population re-distribution from (1)D(2) /(1)G(4) thermally coupled levels at higher temperature range. PMID:24104034

Wang, Xiangfu; Zheng, Jin; Xuan, Yan; Yan, Xiaohong

2013-09-01

105

Two-color Surface Plasmon Polariton Assisted Upconversion Luminescence in NaYF4:Yb:Tm on Au Nanopillar Arrays  

NASA Astrophysics Data System (ADS)

Spectroscopic imaging was used to study the surface plasmon polariton (SPP) enhanced upconversion luminescence of NaYF4:Tm:Yb nanoparticles embedded in PMMA supported on Au nanopillar arrays. Spatially-resolved upconversion spectra show enhancement in both the visible and near-infrared region of the spectrum, clearly associated with the plasmonic resonances of an engineered periodic array of nanopillars. The array has a lattice resonance associated with the SPP near 980nm, at the peak absorption of the Yb^3+ ion, while the local surface plasmon resonance (LSPR) of the individual pillars is seen to enhance the near-infrared emission of Tm^3+ near 800nm. The combined effect results in a significantly higher enhancement of the near-infrared emission when compared to the visible upconversion lines of Tm^3+, consistent with the interpretation of sequential surface plasmon assisted absorption and emission at two separate and disparate energies. The presence of SPP and LSPR were confirmed by spectrally resolved reflectivity, and the mechanism for luminescence enhancement was investigated by time resolved measurements of the luminescence decay. Reflectivity measurements are compared to finite difference time domain simulations (FDTD).

Smith, Steve; Anderson, Robert; Hor, Amy; Fisher, Jon; Bayat, Khadijeh; Baroughi, Mahdi; Lu, Quocahn; Stanely May, P.

2013-03-01

106

Stem Cell Labeling using Polyethylenimine Conjugated (?-NaYbF4:Tm3+)/CaF2 Upconversion Nanoparticles  

PubMed Central

We report on a polyethylenimine (PEI) covalently conjugated (?-NaYbF4:Tm3+)/CaF2 upconversion nanoparticle (PEI-UCNP) and its use for labeling rat mesenchymal stem cells (rMSCs). The PEI-UCNPs absorb and emit near-infrared light, allowing for improved in vivo imaging depth over conventional probes. We found that such covalent surface conjugation by PEI results in a much more stable PEI-UCNP suspension in PBS compared to conventional electrostatic layer by layer (LbL) self-assembling coating approach. We systematically examined the effects of nanoparticle dose and exposure time on rat mesenchymal stem cell (rMSC) cytotoxicity. The exocytosis of PEI-UCNPs from labeled rMSCs and the impact of PEI-UCNP uptake on rMSC differentiation was also investigated. Our data show that incubation of 100-g/mL PEI-UCNPs with rMSCs for 4 h led to efficient labeling of the MSCs, and such a level of PEI-UCNP exposure imposed little cytotoxicity to rMSCs (95% viability). However, extended incubation of PEI-UCNPs at the 100 g/mL dose for 24 hour resulted in some cytotoxicity to rMSCs (60% viability). PEI-UCNP labeled rMSCs also exhibited normal early proliferation, and the internalized PEI-UCNPs did not leak out to cause unintended labeling of adjacent cells during a 14-day transwell culture experiment. Finally, PEI-UCNP labeled rMSCs were able to undergo osteogenic and adipogenic differentiation upon in vitro induction, although the osteogenesis of labeled rMSCs appeared to be less potent than that of the unlabeled rMSCs. Taken together, PEI-UCNPs are promising agents for stem cell labeling and tracking. PMID:23606911

Zhao, Liang; Kutikov, Artem; Shen, Jie; Duan, Chunying; Song, Jie; Han, Gang

2013-01-01

107

Hydrothermal derived LaOF:Ln3+ (Ln = Eu, Tb, Sm, Dy, Tm, and/or Ho) nanocrystals with multicolor-tunable emission properties.  

PubMed

A series of LaOF:Ln(3+) (Ln = Eu, Tb, Sm, Dy, Tm, and/or Ho) nanocrystals with good dispersion have been successfully prepared by the hydrothermal method followed a heat-treatment process. Under ultraviolet radiation and low-voltage electron beam excitation, the LaOF:Ln(3+) nanocrystals show the characteristic f-f emissions of Ln(3+) (Ln = Eu, Tb, Sm, Dy, Tm, or Ho) and give red, blue-green, orange, yellow, blue, and green emission, respectively. Moreover, there exists simultaneous luminescence of Tb(3+), Eu(3+), Sm(3+), Dy(3+), Tm(3+), or Ho(3+) individually when codoping them in the single-phase LaOF host (for example, LaOF:Tb(3+), Eu(3+)/Sm(3+); LaOF:Tm(3+), Dy(3+)/Ho(3+); LaOF:Tm(3+), Ho(3+), Eu(3+) systems), which is beneficial to tune the emission colors. Under low-voltage electron beam excitation, a variety of colors can be efficiently adjusted by varying the doping ions and the doping concentration, making these materials have potential applications in field-emission display devices. More importantly, the energy transfer from Tm(3+) to Ho(3+) in the LaOF:Tm(3+), Ho(3+) samples under UV excitation was first investigated and has been demonstrated to be a resonant type via a quadrupole-quadrupole mechanism. The critical distance (R(Tm-Ho)) is calculated to be 28.4 . In addition, the LaOF:Tb(3+) and LaOF:Tm(3+) phosphors exhibit green and blue luminescence with better chromaticity coordinates, color purity, and higher intensity compared with the commercial green phosphor ZnO:Zn and blue phosphor Y(2)SiO(5):Ce(3+) to some extent under low-voltage electron beam excitation. PMID:23020114

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

2012-10-15

108

Experimental study on the surface modification of Y2O3:Tm3+/Yb3+ nanoparticles to enhance upconversion fluorescence and weaken aggregation  

NASA Astrophysics Data System (ADS)

In order to improve the solubility of doped nanoparticles in solutions, Y2O3:Tm3+/Yb3+ nanoparticles were synthesized using the Pechini-type sol-gel method, and their surfaces were modified with amino or carboxylic functional groups using ligand-capped and ligand-exchanging methods. The nanoparticles with modified surfaces were characterized by transmission electron microscopy (TEM), Fourier transform infrared (FT-IR) spectroscopy and zeta potential (?), and their photoluminescence was studied by fluorescence spectrophotometry. The results indicate that the upconversion fluorescence of amine- and carboxyl-modified nanoparticles was enhanced after the surfaces of nanoparticles were modified. Compared to the upconversion fluorescence intensity of non-modified nanoparticles, the upconversion fluorescence intensities of amine- and carboxyl-modified nanoparticles were enhanced by 9.4 and 1.4 times, respectively. These results are attributed to the formation of the chemical bonds between Y2O3:Tm3+/Yb3+ core and non-crystalline SiO2 shell via Y-O-Si bridges, which activate the 'dormant' Tm3+/Yb3+ ions on the surfaces of nanoparticles. The results of the solubility investigations for amine- and carboxyl-modified nanoparticles indicate that severe aggregation can be weakened by adhering amino or carboxylic functional groups to the surfaces of nanoparticles. It is therefore concluded that the good hydrophilicity resulting from active functional groups in solutions and more intense upconversion fluorescence enable the doped core-shell nanoparticles to have great potential to be used as fluorescence biolabels in the future.

L, Qiang; Li, Ai Hua; Guo, Feng Yun; Sun, Liang; Zhao, Lian Cheng

2008-04-01

109

Investigation on up-conversion luminescence properties of novel transparent Ho3+-Tm3+-Yb3+ co-doped oxyfluoride glass ceramics  

NASA Astrophysics Data System (ADS)

In the present letter, the transparent oxyfluoride glass ceramics containing Ho3+-Tm3+-Yb3+:NaYF4 were successfully prepared by melt-quenching at 1400C and subsequent heating at 650-680C for 1~2 hours . X-ray diffraction (XRD) with Cu K? radiation (?=0.154nm) investigation revealed that NaYF4 nano-crystals in the glass ceramics was fabricated. Their sizes were determined by Sherrer's equation. The emission spectra red green and blue up-conversion (UC) under 980nm laser diode (LD) pumping and absorption spectra were measured. Luminescence measurements confirmed the partition of RE ions in nano-crystals NaYF4. The blue red and green UC radiations correspond to the transitions 1G4-3H6, 1G4-3H4 of Tm3+, 5F4, 5S2-5I8, 5F5-5I8, of Ho3+ ions, respectively. This is similar to that in Tm3+-Yb3+ and/or Ho3+-Yb3+ co-doped glass ceramics. To obtain upconversion fluorescence mechanisms, upconversion fluorescence intensity versus LD pump power were analyzed in view of energy levels of rare earth. Up-conversion mechanisms were discussed and the ratio between red, green and blue UC emission bands was found to be varied as a function of temperature of heat treatment and pump power. This result could be mainly attributed to the cross-relaxation between Ho3+ ions. The excellent optical properties and its convenient, low-cost synthesis of the present glass ceramic imply that it is an excellent substitution material for the unobtainable bulk NaYF4 crystal and may have potentially applications in tunable visible laser or many other fields.

Liu, Xiao-bo; Han, Wan-lei; Xu, Fang; Song, Ying-lin

2011-06-01

110

Investigation on up-conversion luminescence properties of novel transparent Ho3+Tm3+Yb3+ co-doped oxyfluoride glass ceramics  

Microsoft Academic Search

In the present letter, the transparent oxyfluoride glass ceramics containing Ho3+-Tm3+-Yb3+:NaYF4 were successfully prepared by melt-quenching at 1400C and subsequent heating at 650-680C for 1~2 hours . X-ray diffraction (XRD) with Cu Kalpha radiation (lambda=0.154nm) investigation revealed that NaYF4 nano-crystals in the glass ceramics was fabricated. Their sizes were determined by Sherrer's equation. The emission spectra red green and blue

Xiao-Bo Liu; Wan-Lei Han; Fang Xu; Ying-Lin Song

2011-01-01

111

Synthesis of a New Cubic Conductive Cu6O8-yMX (M=Tb, Dy, Ho, Er, Tm, Yb, Lu, X=NO3, Cl) Family  

NASA Astrophysics Data System (ADS)

A new cubic Cu6O8-yMX family (M=Tb, Dy, Ho, Er, Tm, Yb, Lu, X=NO3, Cl) was prepared. These compounds showed metallic resistivity and paramagnetism. The Cu6O8-yMX compounds could be easily synthesized when a trivalent metal element (M) whose oxide (M2O3) has a cubic Tl2O3-type structure was used. These compounds were prepared in the thermal decomposition process of a mixed copper nitrate, copper chloride and metal element oxide solution. The lattice constants of the Cu6O8-yMX compounds were related to those of M2O3.

Sugise, Ryoji; Ohdan, Kyoji; Hamamoto, Toshikazu; Kashiwagi, Kouichi; Shirai, Masashi; Yazawa, Ichiro; Ihara, Hideo

1993-07-01

112

Influence of temperature on upconversion multicolor luminescence in Ho3+/Yb3+/Tm(3+)-doped LiNbO3 single crystal.  

PubMed

The temperature dependence of upconversion luminescence in Ho3+/Yb3+/Tm3+ tri-doped LiNbO3 single crystal was studied at different temperatures from 289 to 773 K under 980 nm excitation. The tri-doped LiNbO3 single crystal offers temperature-dependent color tuning properties, and the white-light emission can be obtained by simply tuning the temperature. In addition, the competition between nonradiative transition and thermal population plays an important role in the upconversion process with temperature increase. This research has implications in the extension of research for optical temperature sensors and multicolor variable temperature display materials. PMID:23939104

Xing, Lili; Xu, Yanling; Wang, Rui; Xu, Wei

2013-07-15

113

Facile fabrication and upconversion luminescence enhancement of LaF3:Yb3+/Ln3+@SiO2 (Ln = Er, Tm) nanostructures decorated with Ag nanoparticles.  

PubMed

A novel hybrid nanostructure, that is a Ag nanoparticle decorated LaF(3):Yb(3+)/Ln(3+)@SiO(2) nanosphere (Ln=Er, Tm), was constructed by a facile strategy, and characterized by XRD, TEM, FTIR, XPS and UV-vis-NIR absorption. Obvious spectral broadening and red-shift on the surface plasmon resonance were obtained by adjusting the size and configuration of Ag nanoparticles. Effective upconversion luminescence enhancements for Er(3+) and Tm(3+) containing samples were obtained. It is suggested that the luminescence enhancement results from both the excitation and emission processes, and the configuration of the studied hybrid nanostructure is an efficient system to enhance the luminescence emission of rare earth doped nanomaterials. It is believed that the enhancement from the hybrid nanostructure will find great potential in the development of photovoltaic solar cells. PMID:24398901

He, Enjie; Zheng, Hairong; Dong, Jun; Gao, Wei; Han, Qingyan; Li, Junna; Hui, Le; Lu, Ying; Tian, Huani

2014-01-31

114

Facile fabrication and upconversion luminescence enhancement of LaF3:Yb3+/Ln3+@SiO2 (Ln=Er, Tm) nanostructures decorated with Ag nanoparticles  

NASA Astrophysics Data System (ADS)

A novel hybrid nanostructure, that is a Ag nanoparticle decorated LaF3:Yb3+/Ln3+@SiO2 nanosphere (Ln=Er, Tm), was constructed by a facile strategy, and characterized by XRD, TEM, FTIR, XPS and UV-vis-NIR absorption. Obvious spectral broadening and red-shift on the surface plasmon resonance were obtained by adjusting the size and configuration of Ag nanoparticles. Effective upconversion luminescence enhancements for Er3+ and Tm3+ containing samples were obtained. It is suggested that the luminescence enhancement results from both the excitation and emission processes, and the configuration of the studied hybrid nanostructure is an efficient system to enhance the luminescence emission of rare earth doped nanomaterials. It is believed that the enhancement from the hybrid nanostructure will find great potential in the development of photovoltaic solar cells.

He, Enjie; Zheng, Hairong; Dong, Jun; Gao, Wei; Han, Qingyan; Li, Junna; Hui, Le; Lu, Ying; Tian, Huani

2014-01-01

115

Hydrothermal synthesis of NaLuF4:153Sm,Yb,Tm nanoparticles and their application in dual-modality upconversion luminescence and SPECT bioimaging.  

PubMed

Upconversion luminescence (UCL) properties and radioactivity have been integrated into NaLuF(4):(153)Sm,Yb,Tm nanoparticles by a facile one-step hydrothermal method, making these nanoparticles potential candidates for UCL and single-photon emission computed tomography (SPECT) dual-modal bioimaging invivo. The introduction of small amount of radioactive (153)Sm(3+) can hardly vary the upconversion luminescence properties of the nanoparticles. The as-designed nanoparticles showed very low cytotoxicity, no obvious tissue damage in 7 days, and excellent invitro and invivo performances in dual-modal bioimaging. By means of a combination of UCL and SPECT imaging invivo, the distribution of the nanoparticles in living animals has been studied, and the results indicated that these particles were mainly accumulated in the liver and spleen. Therefore, the concept of (153)Sm(3+)/Yb(3+)/Tm(3+) co-doped NaLuF(4) nanoparticles for UCL and SPECT dual-modality imaging invivo of whole-body animals may serve as a platform for next-generation probes for ultra-sensitive molecular imaging from the cellular scale to whole-body evaluation. It also introduces an easy methodology to quantify invivo biodistribution of nanomaterials which still needs further understanding as a community. PMID:23117216

Yang, Yang; Sun, Yun; Cao, Tianye; Peng, Juanjuan; Liu, Ying; Wu, Yongquan; Feng, Wei; Zhang, Yingjian; Li, Fuyou

2013-01-01

116

Synergistic extraction of Ce(III), Eu(III) and Tm(III) with a mixture of picrolonic acid and benzo-15-crown-5 in chloroform  

Microsoft Academic Search

SummaryThe synergistic mixture comprising picrolonic acid (HPA) and benzo-15-crown-5 (B15C5) in chloroform has been used for the\\u000a extraction of Ce(III), Eu(III) and Tm(III) as representatives of lanthanide(III) ions from pH 1-2 solutions having ionic strength\\u000a of 0.1 mol. dm-3(K+\\/H+, Cl-). The composition of the extracted species has been determined as M(PA)3. nB15C5 where M is Ce, Eu and Tm and

Akbar Ali; Jamil Anwar; Wasim Yawar

2006-01-01

117

Enhanced performance of Ca2Si5N8:Eu2+, Tm3+ reddish-orange afterglow phosphor by co-doping with Dy3+  

NASA Astrophysics Data System (ADS)

Two types of reddish-orange afterglow emitting nitride phosphors Ca2Si5N8:Eu2+, Tm3+ (CSN:E, T) and Ca2Si5N8:Eu2+, Tm3+, Dy3+ (CSN:E, T, D) were synthesized via a solid-state reaction route and were comparatively investigated. Comparing with the di-doped CSN:E, T phosphor, the tri-doped CSN:E, T, D samples show higher afterglow intensity and longer duration time which can be attributed to the balanced defect micro-environment caused by the presence of Dy3+.

Zhang, Haoran; Dong, Hanwu; Lei, Bingfu; Wang, Peng; Li, Jinfang; Liu, Yingliang; Wang, Jing; Xiao, Yong; Zheng, Mingtao; Meng, Jianxin

2014-09-01

118

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

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.

Liu, Chunyu; Chen, Huan; Zhao, Dan; Shen, Liang; He, Yeyuan; Guo, Wenbin, E-mail: guowb@jlu.edu.cn, E-mail: chenwy@jlu.edu.cn [State Key Laboratory on Integrated Optoelectronics, Jilin University, 2699 Qianjin Street, Changchun 130012 (China); Chen, Weiyou, E-mail: guowb@jlu.edu.cn, E-mail: chenwy@jlu.edu.cn [College of Electronic Science and Engineering, Jilin University, 2699 Qianjin Street, Changchun 130012 (China)

2014-08-04

119

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

PubMed

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 Nel temperature, TN, of 7-9 K. DFT calculations confirm the two different valence states of Se(2-) and Se2(2-) in Eu4O4Se3. PMID:25581725

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

2015-02-21

120

Controlled growth, intense upconversion emissions and concentration induced luminescence switching of bifunctional Tm3+ doped hexagonal NaYb0.55Gd0.45F4 nanorods  

NASA Astrophysics Data System (ADS)

Bifunctional hexagonal Tm3+ 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 980 nm 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 480 nm and 450 nm is observed by adjusting Tm3+ doping concentration. Based on power-dependent spectral analyses, it is found that with the increase of Tm3+ doping concentration, due to the suppressed saturation effect, the dominative UC process redistribute the populations at 1G4 and 1D2(Tm3+) states of Tm3+ 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.

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

2013-11-01

121

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

PubMed

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

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

2013-11-01

122

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

E-print Network

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.

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

2015-01-01

123

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

PubMed

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

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

124

Color-tunable upconversion luminescence of Yb3+, Er3+, and Tm3+ tri-doped ferroelectric BaTiO3 materials  

NASA Astrophysics Data System (ADS)

Tunable upconversion (UC) multicolor luminescence is observed from Yb3+, Er3+, and Tm3+ tri-doped ferroelectric BaTiO3 (BTO) materials. By control of dopant concentrations, the lanthanide-doped BTO powders are capable of generating various UC spectra and color tunability. A white-light emission is achieved through an optimal design. Strong UC luminescence is also observed in the lanthanide-doped BTO thin-films grown on Pt/TiO2/SiO2/Si substrate, which can retain well-defined hysteresis loops with a remnant polarization (2Pr) of 17.8 ?C/cm2. These findings open the possibility of lanthanide-doped BTO as multifunctional materials, in which both luminescent and ferroelectric properties co-exist.

Zhang, Yang; Hao, Jianhua

2013-05-01

125

A quantum chemistry investigation on the structure of lanthanide triflates Ln(OTf)3 where Ln = La, Ce, Nd, Eu, Gd, Er, Yb and Lu.  

PubMed

Density functional theory has been used to probe the electronic structure, coordination number, optical properties and the vibration spectra of monolanthanide trifluoromethane sulfonate Ln(OTf)(3) complexes where Ln = La, Ce, Nd, Eu, Gd, Er, Yb and Lu. The study reveals that the OTf group is bonded to Ln as a bidentate ligand. TDDFT calculations show that, for La(OTf)(3), MLTC and HOMO-LUMO transitions in the UV-vis are strongly bathochromically shifted compared to those of Lu(OTf)(3.). PMID:20354620

Hannachi, Douniazed; Ouddai, Nadia; Chermette, Henry

2010-04-21

126

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

PubMed

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 Gd(3+) doping, and the UCNRs ultimately transformed into small spheres (14.0 nm) with high monodispersity. Doping with Ce(3+) 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. PMID:23546176

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

2013-05-21

127

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

SciTech Connect

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.

Kyunghan Ahn

2007-05-09

128

Heterogeneous Mixed-Valence States in RPd3S4 (R=Eu and Yb) Viewed from Thermopower, Electrical Resistivity and Specific Heat  

NASA Astrophysics Data System (ADS)

Rare-earth palladium bronzes EuPd3S4 and YbPd3S4 with a crystal structure akin to that of the filled-skutterudite compounds are known to show the heterogeneous mixed-valence state scarcely observed among rare-earth intermetallics. In order to shed light on the state, we have measured the thermopower, electrical resistivity and specific heat. It is found that no enhancement of the density of states near the Fermi level occurs in either compound, unlike the case of homogeneous mixed-valence compounds. The thermopower of both systems is qualitatively interpreted using the two-carrier model of electrons and holes, consistently with the reported data of the Hall effect of EuPd3S4.

Kitagawa, Jiro; Takabatake, Toshiro; Matsuoka, Eiichi; Takahashi, Fumihisa; Abe, Kazuo; Ishikawa, Masayasu

2002-07-01

129

Luminescence Properties and Antibacterial Activity of [Ln2(NNA)6(Phen)2] nC3H7NO (Ln = Y, Eu, Gd, Pr, Sm, Tb, Yb, n = 0, 1, 2, NAA = 1-Naphthylacetic Acid, Phen = 1, 10-Phenanthroline)  

Microsoft Academic Search

Rare earth binuclear complexes, [Ln(NAA)3(phen)]2 nDMF (NAA = 1-naphthylacetic acid, phen = 1, 10-phenanthroline, Ln = Y, Eu, Gd, Pr, Sm, Tb, Yb, DMF = N,N?-dimethylformamide), have been prepared and have been characterized by elemental analysis, infrared spectra, electronic spectra, and X-ray crystallography. All complexes crystallize in the monoclinic system, space group P21\\/c(Eu, Gd, Sm, Tb, Y) and triclinic system,

Yu-Fen Liu; De-Fu Rong; Hai-Tao Xia; Da-Qi Wang; Ya-Ming Liu

2008-01-01

130

Upconversion Nanophosphors Naluf4:Yb,Tm for Lymphatic Imaging In Vivo by Real-Time Upconversion Luminescence Imaging under Ambient Light and High-Resolution X-ray CT  

PubMed Central

Lanthanide upconversion nanophosphor (UCNP) has attracted increasing attention for potential applications in bioimaging due to its excellence in deep and high contrast imaging. To date, most upconversion imaging applications were demonstrated in dark surroundings without ambient light for higher signal-to-noise ratio, which hindered the application of optical imaging guided surgery. Herein, the new established NaLuF4-based UCNP (NaLuF4:Yb,Tm, ~17 nm) with bright upconversion emission around 800 nm as imaging signal was used to realize imaging under ambient light to provide more convenient for clinician. Moreover, due to the existance of heavy element lutetium (Lu) in the host lattice, the NaLuF4:Yb,Tm nanoparticles can also be used as an X-ray CT imaging agent to enhance the imaging depth and in vivo imaging resolution. PMID:23650481

Sun, Yun; Peng, Juanjuan; Feng, Wei; Li, Fuyou

2013-01-01

131

Upconversion nanophosphors Naluf?:Yb,Tm for lymphatic imaging in vivo by real-time upconversion luminescence imaging under ambient light and high-resolution X-ray CT.  

PubMed

Lanthanide upconversion nanophosphor (UCNP) has attracted increasing attention for potential applications in bioimaging due to its excellence in deep and high contrast imaging. To date, most upconversion imaging applications were demonstrated in dark surroundings without ambient light for higher signal-to-noise ratio, which hindered the application of optical imaging guided surgery. Herein, the new established NaLuF?-based UCNP (NaLuF?:Yb,Tm, ~17 nm) with bright upconversion emission around 800 nm as imaging signal was used to realize imaging under ambient light to provide more convenient for clinician. Moreover, due to the existance of heavy element lutetium (Lu) in the host lattice, the NaLuF?:Yb,Tm nanoparticles can also be used as an X-ray CT imaging agent to enhance the imaging depth and in vivo imaging resolution. PMID:23650481

Sun, Yun; Peng, Juanjuan; Feng, Wei; Li, Fuyou

2013-01-01

132

Upconversion luminescence properties of Yb3+ and Tm3+ codoped amorphous fluoride ZrF4-BaF2-LaF3-AlF3-NaF thin film prepared by pulsed laser deposition.  

PubMed

The Yb3+ and Tm3+ co-doped 55.98ZrF4-28BaF2-2.5LaF3-4AlF3-7NaF-2.5YbF3-0.02TmF3 amorphous fluoride film was prepared by pulsed laser deposition. The spectroscopic properties and energy transfer analysis of this film were studies in detail. Ultraviolet and visible upconversion emissions were observed under the infrared excitation at 980 nm. In comparison with that of its target, the upconversion emissions of the film in the visible and ultraviolet range were greatly enhanced. The possible energy transfer mechanism of the emissions was given to understand the upconversion process. This kind of thin films has potential applications for the integrated optical waveguide amplifier and ultraviolet laser. PMID:24734646

He, Chunfeng; Qin, Guanshi; Zhao, Dan; Chuai, Xiaohong; Wang, Lili; Zheng, Kezhi; Qin, Weiping

2014-05-01

133

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

SciTech Connect

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.

Kuznetsov, A. S.; Nikitin, A.; Tikhomirov, V. K.; Shestakov, M. V.; Moshchalkov, V. V. [INPAC-Institute for Nanoscale Physics and Chemistry, KULeuven, Celestijnenlaan 200D, Heverlee, 3001 Leuven (Belgium)] [INPAC-Institute for Nanoscale Physics and Chemistry, KULeuven, Celestijnenlaan 200D, Heverlee, 3001 Leuven (Belgium)

2013-04-22

134

Passive Q-switching of a diode-pumped (Tm,Yb):KLu(WO4)2 laser near 2-?m with a Cr2+:ZnS saturable absorber  

NASA Astrophysics Data System (ADS)

Passive Q-switching of a diode-pumped (Tm,Yb):KLu(WO4)2 laser, operating between 1910 and 1950 nm, has been achieved using polycrystalline Cr2+:ZnS as a saturable absorber in a hemispherical L-shaped cavity. The dependence on the doping levels of Tm and Yb and the low-signal absorption of the saturable absorber has been studied. The highest average output power reached 272 mW at a repetition rate of 2.04 kHz corresponding to a pulse energy of 133 ?J. This was achieved with (8.8 at. % Tm, 2.3 at. % Yb):KLu(WO4)2 active element and a saturable absorber with 85% lowsignal transmission. The highest pulse energy, 148 ?J, was achieved with the same combination at lower (0.94 kHz) repetition rate. The obtained pulse energy with the different samples is compared with theoretical analysis and the pulse duration and peak power are estimated from the calculations.

Segura, Martha; Mateos, Xavier; Tyazhev, Aleksey; Pujol, Maria Cinta; Carvajal, Joan Josep; Aguil, Magdalena; Daz, Francesc; Griebner, Uwe; Petrov, Valentin

2012-03-01

135

Solvothermal synthesis and characterization of blue, green and red emitting Y2O3:Ln3+ (Ln3+ = Tm3+, Tb3+ and Eu3+) nanocrystals  

NASA Astrophysics Data System (ADS)

Lanthanide ions (Tm3+, Tb3+ and Eu3+) doped Y2O3 nanocrystals were prepared via solvothermal refluxing calcination method. Yttrium chloride hexahydrate and rare earth chloride (TmCl3, TbCl3 and EuCl3) were used as starting materials for the preparation of co-precipitated gel. The organic solvents such as ethylene glycol and polyethylene glycol (200#) were used to reflux co-precipitated gel and solvothermal refluxing reaction was carried out at 180C (ethylene glycol) and 240C (polyethylene glycol 200#) for 4 h. The samples were calcined at 800C and 1000C for 5 h to convert precursor materials into Y2O3 nanocrystals. The structure, morphology and thermal stability were characterized by XRD, TEM, FESEM, and TG-DTA analysis. The as prepared materials exhibited agglomerated and sphere like morphology with 20-30 nm in diameter depending on refluxing solvents used in the synthesis. The calcined samples after solvothermal reaction in polyethylene glycol exhibited sphere morphology with 30-80 nm in diameter. The photoluminescence results of Tm3+, Tb3+ and Eu3+ doped Y2O3 nanocrystals showed strong blue, green and red emission around 450, 540 and 610 nm under the excitation wavelength of 360, 304 and 254 nm respectively. The PL results were compared with reference sample prepared via co-precipitated calcination method.

Devaraju, M. K.; Yin, S.; Sato, T.

2009-02-01

136

The size confinement effect for Ln3+ (Ln = Tm or Eu) concentration quenching and energy transfer in Y2O3 nanocrystals.  

PubMed

Y2O3:Ln (Ln = Tm or Eu) nano-powders with different particle sizes and various doping concentrations were prepared by using a combustion method. The bulk powders doped with the same concentrations were obtained by annealing the nano-powders at high temperatures. Emission spectra of the phosphors were measured. The crystal structure and morphology of the phosphors were characterized by XRD (X-ray diffraction) and FE-SEM (field emission scanning electron microscopy), respectively. The concentration quenching of luminescent centers and energy transfer between luminescent centers in Y2O3:Ln nanocrystal powders were investigated. It is found that the behavior of luminescent concentration quenching for Eu3+ 5D0 --> 7F2 in nano-powders is similar to that in bulk powders. On the contrary, the quenching concentration for Tm3+ 1D2 --> 3H4 is distinctly higher than that in bulk powders. This owes to the size confinement effect which will restrain the electric dipole-dipole interaction as a long-rang interaction (e.g., energy transfer between Tm3+ ions), and will hardly affect the exchange interaction which is a short-rang interaction (e.g., energy transfer between Eu3+ ions). PMID:24734659

Wang, Changwen; Meng, Qingyu

2014-05-01

137

Rare-Earths Centers (Sm{sup 3+}, Eu{sup 3+}, Yb{sup 3+}) in MeF{sub 2}(Me = Ca, Sr, Ba, Cd) Crystals  

SciTech Connect

Rare-earth elements RE{sup 3+}(RE = Sm, Eu, Yb) form impurity centers in fluorite-like crystals MeF{sub 2}(Me = Ca, Sr, Ba, Cd). The crystal structure of cubic, trigonal and tetragonal centers in MeF{sub 2} has been investigated in the framework of shell model and pair potential approximation. The crystal field parameters were calculated with the exchange charges model, using the optimized geometry of the doped host matrix. With these parameters we have been calculated the optical spectra and spin-Hamiltonian (g-factors) of RE{sup 3+} in MeF{sub 2}, for some combination of R{sup 3+} and MeF{sup 2}. The obtained results were discussed and comparison with experimental data was made. A good agreement confirms the method and model of calculations.

Nikiforov, A. E.; Chernyshev, V. A.; Volodin, V. P. [Ural State University, 620083-Ekaterinburg, Lenin av. 51 (Russian Federation); Avram, N. M. [West University of Timisoara, Dept. of Physics, 300223-Timisoara, Bd. V. Parvan No. 4 (Romania); Academy of Romanian Scientists, Independentei 54, 050094-Bucharest (Romania); Avram, C. N.; Vaida, M. [West University of Timisoara, Dept. of Physics, 300223-Timisoara, Bd. V. Parvan No. 4 (Romania)

2010-08-04

138

Tunnel-diode Resonator Spectroscopy of Quantum Levels in Cr12Ln4 (Ln=Y,Eu,Gd,Tb,Dy,Ho,Yb) Magnetic Molecules  

NASA Astrophysics Data System (ADS)

The differential magnetic susceptibility for a series of Cr12Ln4 (Ln=Y,Eu,Gd,Tb,Dy,Ho,Yb) magnetic molecules was measured in static (up to 16 T) and pulsed (up to 45 T) magnetic fields using a rf tunnel-diode resonator (TDR). At low temperatures, the behavior of these finite spin systems is governed by discrete energy spectra of the individual molecules. In magnetic field, low-energy quantum levels Zeeman-split, crossing at field values where magnetization exhibits a step corresponding to switching between different spin states. In high fields, we detect multiple level crossings which allow for a detailed mapping of the energy diagram. We then perform quantum Monte Carlo (QMC) using a Heisenberg Hamiltonian with three adjustable exchange constants whose values are chosen so as to optimize agreement with the experimental energy spectrum. The variations in results for the studied molecules are correlated to the magnetic properties of the lanthanide ions.

Yeninas, Steven; Luban, Marshall; Prozorov, Ruslan; Coniglio, William A.; Agosta, Charles C.; Engelhardt, Larry; Timco, Grigore A.; Winnpenny, Richard E. P.

2011-03-01

139

Ln(IO3)3 (Ln = Ce, Nd, Eu, Gd, Er, Yb) polycrystals as novel photocatalysts for efficient decontamination under ultraviolet light irradiation.  

PubMed

Ln(IO3)3 (Ln = Ce, Nd, Eu, Gd, Er, Yb) polycrystals were hydrothermally synthesized using lanthanide nitrate or lanthanide oxide and iodic acid as precursors. X-ray diffraction was used to characterize the crystal structures of the Ln(IO3)3 products. Scanning electron microscopy was carried out to observe the microscopic morphologies. The lattice spacings were studied by high-resolution transmission electron microscopy and selected area electron diffraction. We evaluated the photocatalytic efficiency by decomposing methyl orange dye under ultraviolet light irradiation, and the Ln(IO3)3 products show excellent photocatalytic properties. To rule out the effect of photosensitization, 2,4-dichlorophenol was also photodegraded. As one of the key factors of photocatalysis, ultraviolet-visible diffuse reflectance spectra of the Ln(IO3)3 samples were also studied, and all products have strong absorption in the ultraviolet region. PMID:24796497

Wang, Wenjun; Cheng, Hefeng; Huang, Baibiao; Li, Xinru; Qin, Xiaoyan; Zhang, Xiaoyang; Dai, Ying

2014-05-19

140

Anisotropic exchange interactions in [Ln FeLS3+] dinuclear systems (Ln3+ = Dy, Tm, Yb): Magnetometry and Dual Mode X-band Electron Paramagnetic Resonance spectroscopic study  

NASA Astrophysics Data System (ADS)

A recently developed experimental and theoretical procedure is used in order to calculate the magnitude and anisotropy of interaction between a lanthanide and a 3d-metal ion. The general formula of the molecular compounds is [Ln(H 2O) 3(dmf) 4(?-CN)Fe-(CN) 5] nH 2O where 1 ? n ? 1,5 and dmf = N, N'-dimethylformamide, abbreviated as [LnFe] from now on. The main parts of this procedure are (a) the evaluation of the effective g-parameters of the lanthanide ion with the help of EPR measurements. (b) The use of dual mode EPR spectroscopy to define the anisotropic exchange interactions with the help of an anisotropic Hamiltonian model. (c) Use of the same magnetic model to fit magnetization and susceptibility data in order to verify the EPR findings. It was possible to define some trends concerning the exchange components of the [DyFe] dimer according to which the antiferromagnetic isotropic exchange constant is smaller than 4 cm -1 and the anisotropic components are [ Dexc, Eexc] = [?6(1), 0.0] cm -1. Also for the case of [TmFe] and [YbFe] dimers the antiferromagnetic isotropic exchange constant is smaller than 0.3 cm -1 while the anisotropic components are [ Dexc, Eexc] = [?12.0, 0.0] cm -1 and [ Dexc, Eexc] = [0.4(1), 0.0] cm -1, respectively.

Tangoulis, Vassilis; Figuerola, Albert

2007-11-01

141

Far-IR spectra of magnons, crystal field transitions, and phonons in hexagonal REMnO3 (RE=Er, Tm, Yb, Lu) single crystals  

NASA Astrophysics Data System (ADS)

Far-IR spectra of hexagonal REMnO3 (RE=Er, Tm, Yb, Lu) single crystals have been studied between T=1.6 K and 300 K using transmission in high magnetic field and rotating analyzer ellipsometry. The symmetry of the IR optical phonons and their oscillator strengths were determined for compounds with different RE ions. The temperature dependence of the phonon frequencies revealed a strong spin-phonon interaction in the temperature range below TN70 K. The effective g-factors have been determined for the AFM resonances and crystal field transitions using external magnetic fields up to 10 T. The frequency of the AFM resonances around 50 cm-1 increases systematically with a decrease of the RE ion radius. The observed effects are analyzed taking into account main magnetic interactions in the system including exchange of the Mn^3+ spins with RE^3+ paramagnetic moments. The magnetic ordering of RE ions was observed at low temperatures T<3.5 K and in strong magnetic fields.

Standard, E. C.; Stanislavchuk, T. N.; Basistyy, R.; Sirenko, A. A.; Kang, T. D.; Lee, N.; Cheong, S.-W.

2012-02-01

142

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

SciTech Connect

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.

Wong-Ng, W.; Yan, Y.; Liu, G. [Ceramics Division, NIST, Gaithersburg, Maryland 20899 (United States); Xie, W.; Tritt, T. [Department of Physics, Clemson University, Greensville, South Carolina 29634 (United States); Kaduk, J. [Illinois Institute of Technology, Chicago, Illinois 60616 (United States); Thomas, E. [Air Force Research Laboratory, Wright Pattersen, Ohio 45433 (United States)

2011-12-01

143

Core-shell Fe3O4@NaLuF4:Yb,Er/Tm nanostructure for MRI, CT and upconversion luminescence tri-modality imaging.  

PubMed

Core-shell Fe(3)O(4)@NaLuF(4):Yb,Er/Tm nanostructure (MUCNP) with multifunctional properties has been developed using a step-wise synthetic method. The successful fabrication of MUCNP has been confirmed by transmission electron microscopy, powder X-ray diffraction, energy-dispersive X-ray analysis and X-ray photoelectron spectroscopy. The MUCNP exhibits superparamagnetic property with saturation magnetization of 15 emu g(-1), and T(2)-enhanced magnetic resonance (MR) effect with an r(2) value of 21.63 s(-1) mM(-1) at 0.5 T, resulting from the Fe(3)O(4) cores. Moreover, the NaLuF(4)-based MUCNP provides excellent X-ray attenuation and upconversion luminescence (UCL) emission under excitation at 980 nm. In vivo MR, computed tomography (CT) and UCL images of tumor-bearing mice show that the MUCNP can be successfully used in multimodal imaging. In vitro tests reveal that the MUCNP is non-cytotoxic. These results suggest that the developed MUCNP could be served as an MR, CT and UCL probe for tri-modality imaging. PMID:22444645

Zhu, Xingjun; Zhou, Jing; Chen, Min; Shi, Mei; Feng, Wei; Li, Fuyou

2012-06-01

144

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)

It was found that the manganese perovskite oxides Ln0.5Ca 0.5MnO 3 ( 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-3 d 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 Ca 2+, and a lowering of electron transfer. The charge-ordering transition was not clearly observed only for Lu 0.5Ca 0.5MnO 3 containing the smallest lanthanide ion, plausibly due to a large randomness of magnetic interactions arising from the ionic radii difference of Lu 3+ and Ca 2+. In addition, preliminary measurements of AC dielectric response suggested that these manganites belong to a so-called multiferroic system.

Yoshii, Kenji; Abe, Hideki; Ikeda, Naoshi

2005-12-01

145

Heterobinuclear Zn-Ln (Ln?=?La, Nd, Eu, Gd, Tb, Er and Yb) complexes based on asymmetric Schiff-base ligand: synthesis, characterization and photophysical properties.  

PubMed

With a novel asymmetric Schiff-base zinc complex ZnL (H2 L?=?N-(3-methoxysalicylidene)-N'-(5-bromo-3-methoxysalicylidene)phenylene-1,2-diamine), obtained from phenylene-1,2-diamine, 3-methoxysalicylaldehyde and 5-bromo-3-methoxysalicylaldehyde, as the precursor, a series of heterobinuclear Zn-Ln complexes [ZnLnL(NO3 )3 (CH3 CN)] (Ln?=?La, 1; Ln?=?Nd, 2; Ln?=?Eu, 3; Ln?=?Gd, 4; Ln?=?Tb, 5; Ln?=?Er, 6; Ln?=?Yb, 7) were synthesized by the further reaction with Ln(NO3 )3 6H2 O, and characterized by Fourier transform-infrared, fast atom bombardment mass spectroscopy and elemental analysis. Photophysical studies of these complexes show that the strong and characteristic near-infrared luminescence of Nd(3+) , Yb(3+) and Er(3+) with emissive lifetimes in the microsecond range has been sensitized from the excited state of the asymmetric Schiff-base ligand due to effective intramolecular energy transfer; the other complexes do not show characteristic emission due to the energy gap between the chromophore and lanthanide ions. PMID:23001932

Zhao, Shunsheng; Liu, Xiangrong; L, Xingqiang; Wong, Wai-Kwok

2013-01-01

146

Single-component and warm-white-emitting phosphor NaGd(WO4)2:Tm3+, Dy3+, Eu3+: synthesis, luminescence, energy transfer, and tunable color.  

PubMed

Tm(3+), Dy(3+), and Eu(3+) codoped NaGd(WO4)2 phosphors were prepared by a facile hydrothermal process; they were characterized by X-ray diffraction (XRD), field emission scanning electron microscope (FESEM), energy-dispersive X-ray spectrometer (EDS), photoluminescence spectra, and fluorescence lifetime. The results show that the novel octahedral microcrystals with a mean side length of 2 ?m are obtained. Under the excitation of ultraviolet, individual RE(3+) ion (Tm(3+), Dy(3+), and Eu(3+)) activated NaGd(WO4)2 phosphors exhibit excellent emission properties in their respective regions. Moreover, when codoping Dy(3+) and Eu(3+)/Tm(3+) in the single component, the energy migration from Dy(3+) to Eu(3+) has been demonstrated to be a resonant type via a dipole-quadrupole mechanism as well as that from Tm(3+) to Dy(3+) ions, of which the critical distance (R(Dy-Eu)) is calculated to be 11.08 . More significantly, in the Tm(3+), Dy(3+), and Eu(3+) tridoped NaGd(WO4)2 phosphors, the energy migration of Tm(3+)-Dy(3+)-Eu(3+), utilized for sensitizing Eu(3+) ions besides compensating the red component at low Eu(3+) doping concentration, has been discussed first. In addition, under 365 nm near-ultraviolet radiation (nUV), the color-tunable emissions in octahedral NaGd(WO4)2 microcrystals are realized by giving abundant blue, green, white, yellow, and red emissions, especially warm white emission, and could be favorable candidates in full-color phosphors for nUV-LEDs. PMID:25303406

Liu, Yan; Liu, Guixia; Wang, Jinxian; Dong, Xiangting; Yu, Wensheng

2014-11-01

147

Structure, enhancement and white luminescence of multifunctional Lu6O5F8:20%Yb3+,1%Er3+(Tm3+) nanoparticles via further doping with Li+ under different excitation sources  

NASA Astrophysics Data System (ADS)

A series of Lu6O5F8:20%Yb3+,1%Er3+(Tm3+),x%Li+ (0 <= x <= 12) nanoparticles with average size from 20 to 320 nm upon increasing Li+ concentration were prepared by a coprecipitation method. The detailed crystal structure of Lu6O5F8 as a new matrix is firstly analysed via retrieved refinement of the powder X-ray diffraction (XRD). In addition, the corresponding Powder Diffraction File card information was also obtained through indexing the XRD pattern of the host. Upconversion under excitation at 980 nm, downconversion with Xe lamp as excitation source and cathodoluminescence properties of Lu6O5F8:20%Yb3+,1%Er3+(Tm3+),x%Li+ (0 <= x <= 12) nanoparticles were compared and studied. It is worthwhile pointing out that according to the effects of Li+ on emission intensity ratio, white UC emission was achieved in the Lu6O5F8:6%Yb3+,0.3%Er3+,0.4%Tm3+,5%Li+ compared to Li+ free sample with the same activator concentration. The reasons behind this behavior were presented and discussed. All in all, Li+ ion would be a wonderful luminescence intensifier for lanthanide ions, and the multifunctional lanthanide ion-doped Lu6O5F8 nanoparticles have potential application in photoluminescence areas and field emission display devices.A series of Lu6O5F8:20%Yb3+,1%Er3+(Tm3+),x%Li+ (0 <= x <= 12) nanoparticles with average size from 20 to 320 nm upon increasing Li+ concentration were prepared by a coprecipitation method. The detailed crystal structure of Lu6O5F8 as a new matrix is firstly analysed via retrieved refinement of the powder X-ray diffraction (XRD). In addition, the corresponding Powder Diffraction File card information was also obtained through indexing the XRD pattern of the host. Upconversion under excitation at 980 nm, downconversion with Xe lamp as excitation source and cathodoluminescence properties of Lu6O5F8:20%Yb3+,1%Er3+(Tm3+),x%Li+ (0 <= x <= 12) nanoparticles were compared and studied. It is worthwhile pointing out that according to the effects of Li+ on emission intensity ratio, white UC emission was achieved in the Lu6O5F8:6%Yb3+,0.3%Er3+,0.4%Tm3+,5%Li+ compared to Li+ free sample with the same activator concentration. The reasons behind this behavior were presented and discussed. All in all, Li+ ion would be a wonderful luminescence intensifier for lanthanide ions, and the multifunctional lanthanide ion-doped Lu6O5F8 nanoparticles have potential application in photoluminescence areas and field emission display devices. Electronic supplementary information (ESI) available. See DOI: 10.1039/c2nr33577h

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

2013-02-01

148

Hydrothermal synthesis and luminescence properties of hierarchical SrF{sub 2} and SrF{sub 2}:Ln{sup 3+} (Ln = Er, Nd, Yb, Eu, Tb) micro/nanocomposite architectures  

SciTech Connect

Graphical abstract: Uniform SrF{sub 2} and SrF{sub 2}:Ln{sup 3+} (Ln = Er, Nd, Yb, Eu, Tb) hierarchical microsphere assembled by numerous nanoplates have been successfully synthesized via a facile hydrothermal process in the presence of chelating reagent. Highlights: Black-Right-Pointing-Pointer Uniform SrF{sub 2} and SrF{sub 2}:Ln{sup 3+} (Ln = Er, Nd, Yb, Eu, Tb) hierarchical microsphere were obtained by a simple hydrothermal method. Black-Right-Pointing-Pointer The reaction time, chelating reagent and F source play important roles for the formation of hierarchical microspheres. Black-Right-Pointing-Pointer The luminescence properties of lanthanide ion-doped SrF{sub 2} hierarchical microstructures were discussed. -- Abstract: Highly uniform SrF{sub 2} and SrF{sub 2}:Ln{sup 3+} (Ln = Er, Nd, Yb, Eu, Tb) hierarchical microspheres assembled by 2D nanoplates have been successfully synthesized by a facile and friendly hydrothermal route. X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and photoluminescence (PL) spectra were used to characterize the samples. The experimental results indicate that reaction time and chelating reagent play a key role in forming the hierarchical microspheres. The formation mechanism was proposed based on the evolution of this morphology as a function of hydrothermal time. The near-infrared luminescence of lanthanide ions (Er, Nd, and Yb) doped SrF{sub 2} microspheres were discussed in detail. In addition, the as-obtained SrF{sub 2}:Eu{sup 3+} sample exhibits orange-red emission centered at 590 nm under excitation at 393 nm, while the SrF{sub 2}:Tb{sup 3+} exhibits a strong green emission at 540 nm. The as-synthesized SrF{sub 2}:Ln{sup 3+} luminescent microspheres might find some potential applications in areas of photoluminescence, telecommunication and laser emission.

Peng, Jing; Hou, Suying; Liu, Xianchun [College of Chemistry, Northeast Normal University, Changchun 130024 (China)] [College of Chemistry, Northeast Normal University, Changchun 130024 (China); Feng, Jing [State Key Laboratory of Rare Earth Resource Utilizations, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022 (China)] [State Key Laboratory of Rare Earth Resource Utilizations, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022 (China); Yu, Xiaodan [College of Chemistry, Northeast Normal University, Changchun 130024 (China)] [College of Chemistry, Northeast Normal University, Changchun 130024 (China); Xing, Yan, E-mail: xingy202@nenu.edu.cn [College of Chemistry, Northeast Normal University, Changchun 130024 (China)] [College of Chemistry, Northeast Normal University, Changchun 130024 (China); Su, Zhongmin [College of Chemistry, Northeast Normal University, Changchun 130024 (China)] [College of Chemistry, Northeast Normal University, Changchun 130024 (China)

2012-02-15

149

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

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.

Asiri Naidu, S.; Boudin, S. [Laboratoire de Cristallographie et Sciences des Materiaux, ENSICAEN, Universite de Caen, CNRS, 6 Bd Marechal Juin, F-14050 Caen (France); Varadaraju, U.V. [Department of Chemistry, Indian Institute of Technology Madras, Chennai 600036 (India); Raveau, B., E-mail: bernard.raveau@ensicaen.fr [Laboratoire de Cristallographie et Sciences des Materiaux, ENSICAEN, Universite de Caen, CNRS, 6 Bd Marechal Juin, F-14050 Caen (France)

2012-01-15

150

Lanthanoid single-ion magnets based on polyoxometalates with a 5-fold symmetry: the series [LnP5W30O110]12- (Ln3+ = Tb, Dy, Ho, Er, Tm, and Yb).  

PubMed

A robust, stable and processable family of mononuclear lanthanoid complexes based on polyoxometalates (POMs) that exhibit single-molecule magnetic behavior is described here. Preyssler polyanions of general formula [LnP(5)W(30)O(110)](12-) (Ln(3+) = Tb, Dy, Ho, Er, Tm, and Yb) have been characterized with static and dynamic magnetic measurements and heat capacity experiments. For the Dy and Ho derivatives, slow relaxation of the magnetization has been found. A simple interpretation of these properties is achieved by using crystal field theory. PMID:22894703

Cardona-Serra, S; Clemente-Juan, J M; Coronado, E; Gaita-Ario, A; Camn, A; Evangelisti, M; Luis, F; Martnez-Prez, M J; Ses, J

2012-09-12

151

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

SciTech Connect

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=10501100 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 FTa{sub 2}O{sub 5} [Zibrov et al. Russ. J. Inorg. Chem. 48 (2003) 464471] [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) , V=532.90(1) {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) , V=528.80(2) {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) , V=532.21(1) {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 FTa{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 REO distances.

Zibrov, Igor P., E-mail: zibrov@mail.ru [Institute for High Pressure Physics, Russian Academy of Sciences, Kaluzhskoe Highway 14, Troitsk, Moscow 142190 (Russian Federation); Filonenko, Vladimir P., E-mail: filv@hppi.troitsk.ru [Institute for High Pressure Physics, Russian Academy of Sciences, Kaluzhskoe Highway 14, Troitsk, Moscow 142190 (Russian Federation); Zakharov, Nikolai D., E-mail: zakharov@mpi-halle.mpg.de [Max Planck Institute for Microstructure Physics, Weinberg 2, D-06120 Halle/Saale (Germany); Werner, Peter, E-mail: werner@mpi-halle.mpg.de [Max Planck Institute for Microstructure Physics, Weinberg 2, D-06120 Halle/Saale (Germany); Drobot, Dmitrii V., E-mail: dvdrobot@mail.ru [Lomonosov Moscow University of Fine Chemical Technology, Prospect Vernadskogo 86, Moscow 119571 (Russian Federation); Nikishina, Elena E.; Lebedeva, Elena N., E-mail: helena_nick@mail.ru [Lomonosov Moscow University of Fine Chemical Technology, Prospect Vernadskogo 86, Moscow 119571 (Russian Federation)

2013-07-15

152

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

PubMed

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 while c?15.99-20.54 . 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

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

153

Critical behavior of the paramagnetic to antiferromagnetic transition in orthorhombic and hexagonal phases of RMnO3 (R=Sm, Tb, Dy, Ho, Er, Tm, Yb, Lu, Y)  

NASA Astrophysics Data System (ADS)

The critical behavior of the paramagnetic to antiferromagnetic transition in RMnO3 (R = Sm, Tb, Dy, Ho, Er, Tm, Yb, Lu, Y) has been studied with an ac photopyroelectric calorimeter, which gives simultaneously the thermal diffusivity and specific heat as a function of temperature with high resolution around the Nel temperature. RMnO3 (R = Sm, Tb, Dy) has an orthorhombic perovskite structure, whereas the other manganites are hexagonal, thus revealing a strong thermal anisotropy. SmMnO3 with type-A antiferromagnetic ordering exhibits a 3D-XY critical behavior, which could be attributed to the peculiar site anisotropy of Sm3+ and the exchange interaction between Mn3+ and Sm3+ ions. The sinusoidal spin ordering in TbMnO3 and DyMnO3 can be phenomenologically described by the 3D-Heisenberg model. Finally, the hexagonal manganites RMnO3 (R = Ho, Er, Tm, Yb, Lu, Y) are close to the 3D-Heisenberg universality class, ruling out the chiral models predicted by the renormalization group theory.

Oleaga, A.; Salazar, A.; Prabhakaran, D.; Cheng, J.-G.; Zhou, J.-S.

2012-05-01

154

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

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.

Gribanov, Alexander [Institute of Physical Chemistry, University of Vienna, Waehringerstrasse 42, A-1090 Wien (Austria); Chemistry Department of the Moscow State University, Leninskie Gory, GSP-1, 119991 Moscow (Russian Federation); Grytsiv, Andriy [Institute of Physical Chemistry, University of Vienna, Waehringerstrasse 42, A-1090 Wien (Austria); Rogl, Peter, E-mail: peter.franz.rogl@univie.ac.a [Institute of Physical Chemistry, University of Vienna, Waehringerstrasse 42, A-1090 Wien (Austria); Seropegin, Yurii [Chemistry Department of the Moscow State University, Leninskie Gory, GSP-1, 119991 Moscow (Russian Federation); Giester, Gerald [Institute of Mineralogy and Crystallography, University of Vienna, Althanstrasse 14, A-1090 Wien (Austria)

2009-07-15

155

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

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.

Sonnauer, Andreas [Institute of Inorganic Chemistry, Christian-Albrechts-University, Otto-Hahn-Platz 6/7, D 24118 Kiel (Germany); Stock, Norbert [Institute of Inorganic Chemistry, Christian-Albrechts-University, Otto-Hahn-Platz 6/7, D 24118 Kiel (Germany)], E-mail: stock@ac.uni-kiel.de

2008-11-15

156

Low-temperature superstructures of a series of Cd6M (M = Ca, Y, Sr, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu) crystalline approximants.  

PubMed

The low-temperature (LT) superstructure and the phase transition temperature have been investigated for a series of Cd6M crystalline approximants by transmission electron microscopy as well as electrical resistivity measurements. Except for M = Lu, Cd6M is found to undergo a phase transition to a monoclinic phase at a low temperature and the transition temperature (Tc) scales well with the size of the M atom. For M = Ca, Y, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er and Tm the LT superstructure is explained by a ?2a a ?2a lattice with the space group C2/c, and for M = Sr and Yb a ?2a 2a ?2a monoclinic lattice with P2/m. On the other hand, no phase transition is observed for M = Lu, indicating that a Cd4 tetrahedron at the cluster center remains disordered down to the lowest temperature, i.e. 16 K. It is shown that the volume inside the Cd20 dodecahedron plays a crucial role in the occurrence of the phase transition, and long-term aging in particular promotes the phase transition for late rare-earth elements such as Ho, Er and Tm, suggesting that the transition is sensitive to and is even hindered by disorder such as atomic vacancies. The absence of the transition for M = Lu is attributed to the highest activation energy for the transition due to the smallest volume inside the Cd20 dodecahedron. PMID:23685563

Nishimoto, Kazue; Sato, Takeru; Tamura, Ryuji

2013-06-12

157

Laser-diode-excited blue upconversion in Tm3+/Yb3+ -codoped TeO2-Ga2O3-R2O (R=Li, Na, K) glasses.  

PubMed

This paper reports on intense blue upconversion in Tm(3+)/Yb(3+) codoped TeO(2)-Ga(2)O(3)-R(2)O(R=Li, Na, K) glasses upon excitation with commercial available laser diode (LD). Effects of alkali ions on the Raman spectra, thermal stability and spectroscopic properties of the tellurite-gallium glasses have also been investigated. Energy transfer and the involved upconversion mechanisms have been discussed. Intense blue upconversion emission centered at 476 nm along with a weak red emission at 650 nm has been observed upon excitation of 977 nm LD, assigned to the transitions of 1G4-->3H6, and 1G4-->3H4 and/or 3F(2,3)-->3H6 of Tm(3+), respectively. The blue upconversion intensity has a cubelike dependence on incident pump laser power, indicating a three-photon process. However, a quadratic dependence of the 476 nm upconversion intensity on the incident pump laser power has been observed when samples under excitation of 808 nm LD due to a two-photon absorption process. Enhanced upconversion luminescence have been observed with replacing K(+) for Na(+) and Li(+). PMID:17823854

Zhao, Chun; Zhang, Qinyuan; Yang, Gangfeng; Jiang, Zhonghong

2008-01-01

158

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)

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.

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

2014-05-01

159

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

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.

Hu, Yuebo [Faculty of Mechanical and Electrical Engineering, Kunming University of Science and Technology, Kunming 650500 (China); Qiu, Jianbei, E-mail: qiu@kmust.edu.cn; Song, Zhiguo; Zhou, Dacheng [Key Laboratory of Advanced Materials in Rare and Precious and Non-ferrous Metals, Ministry of Education, Key Laboratory of Advanced Materials of Yunnan Province, Faculty of Materials Science and Engineering, Kunming University of Science and Technology, Kunming 650093 (China)

2014-02-28

160

Anomalous Hall Effect in Three Ferromagnets: EuFe4Sb12, Yb14MnSb11, and Eu8Ga16Ge30  

SciTech Connect

The Hall resistivity ({rho}{sub xy}), resistivity ({rho}{sub xx}), and magnetization of three metallic ferromagnets are investigated as a function of magnetic field and temperature. The three ferromagnets, EuFe{sub 4}Sb{sub 12} (T{sub c}{approx}84 K), Yb{sub 14}MnSb{sub 11} (T{sub c}{approx}53 K), and Eu{sub 8}Ga{sub 16}Ge{sub 30} (T{sub c}{approx}36 K) are Zintl compounds with carrier concentrations between 1 x 10{sup 21} and 3.5 x 10{sup 21} cm{sup -3}. The relative decrease in {rho}{sub xx} below T{sub c} [{rho}{sub xx}(T{sub c})Y{rho}{sub xx}(2 K)] is 28, 6.5, and 1.3 for EuFe{sub 4}Sb{sub 12}, Yb{sub 14}MnSb{sub 11}, and Eu{sub 8}Ga{sub 16}Ge{sub 30}, respectively. The low carrier concentrations coupled with low magnetic anisotropies allow a relatively clean separation between the anomalous ({rho}{sub xy}), and normal contributions to the measured Hall resistivity. For each compound the anomalous contribution in the zero field limit is fit to a{rho}{sub xx}+{sigma}{sub xy}{rho}{sub xx}{sup 2} for temperatures TEuFe{sub 4}Sb{sub 12}, Yb{sub 14}MnSb{sub 11}, and Eu{sub 8}Ga{sub 16}Ge{sub 30}, respectively, and is independent of temperature for T

Sales, Brian C [ORNL; Jin, Rongying [ORNL; Mandrus, David [ORNL; Khalifah, Peter [ORNL

2006-01-01

161

Electronic states of R F e2O4(R =Lu ,Yb ,Tm ,Y ) mixed-valence compounds determined by soft x-ray absorption spectroscopy and x-ray magnetic circular dichroism  

NASA Astrophysics Data System (ADS)

We here report an investigation of the electronic states in the R F e2O4(R =Lu ,Yb ,Tm ,Y ) mixed-valence ferrites by means of soft x-ray absorption spectroscopy (XAS) and x-ray magnetic circular dichroism (XMCD) measurements together with ab initio theoretical calculations. The presence of Fe+2 and Fe+3 pure ionic species is discarded in the XAS spectra at the O K edge in both experimental data and simulations based on the multiple scattering theory. Similarly, no trace of F e+2/F e+3 contributions is detected in the XMCD spectra at the Fe K edge. On the other hand, the XAS and XMCD spectra at the Fe L2 ,3 edges can be well described in terms of F e+2/F e+3 contributions, and are also supported by multiplet calculations. This finding can be interpreted as the existence of a mixture of 3 d5/3 d6 configurations at the Fe atoms. Alternative ferrimagnetic spin orderings based on a trimodal Fe valence distribution are also proposed and discussed. Finally, a possible explanation for the strong dependence of the Fe L2 ,3 edges XMCD signal magnitude on both the sample surface preparation and detection method is presented.

Lafuerza, Sara; Garca, Joaqun; Subas, Gloria; Blasco, Javier; Herrero-Martn, Javier; Pascarelli, Sakura

2014-12-01

162

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

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.

Yoshii, Kenji [Japan Atomic Energy Research Institute, Mikazuki, Hyogo 679-5148 (Japan)]. E-mail: yoshiike@spring8.or.jp; Abe, Hideki [National Institute for Materials Science, Tsukuba, Ibaraki 305-0047 (Japan); Ikeda, Naoshi [Japan Synchrotron Radiation Research Institute, Mikazuki, Hyogo 679-5198 (Japan)

2005-12-15

163

Folic acid-conjugated LaF3:Yb,Tm@SiO2 nanoprobes for targeting dual-modality imaging of upconversion luminescence and X-ray computed tomography.  

PubMed

Development of multimodal contrast agents for in vivo simultaneous multimodality imaging is an emerging interdiscipline that is paving the avenue toward the goal of personalized medicine. Herein, folic acid-conjugated silica-modified LaF(3):Yb,Tm upconversion nanoparticles (UCNPs@SiO(2)-FA) with high La content in a single particle were strategically designed and prepared for simultaneously targeting dual-modality imaging of upconversion luminescence (UCL) and X-ray computed tomography (CT). LaF(3) UCNPs were synthesized by a novel oleic acid (OA)/ionic liquid (IL) two-phase system. Afterward, a folic acid molecule was covalently anchored on the surface of UCNPs with a silane coupling agent. The UCNPs@SiO(2)-FA exhibits good stability, water dispersibility and solubility, low cytotoxicity, good biocompatibility, highly selective targeting, excellent X-ray attenuation, and UCL emission under excitation at 980 nm. In vivo UCL and CT images of mice show the UCNPs@SiO(2)-FA can be used in targeting dual-modality imaging. These results suggest that the as-prepared nanoprobe is a good candidate with excellent imaging and targeting ability for targeting dual-modality imaging of UCL and CT. PMID:23134318

Ma, Jiebing; Huang, Peng; He, Meng; Pan, Liyuan; Zhou, Zhijun; Feng, Lili; Gao, Guo; Cui, Daxiang

2012-12-01

164

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

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 980nm. Moreover, MUC-OCC nanorods display high transverse (r2) relaxivities invitro. The application of low-dose MUC-OCC nanorods for NIR-to-NIR UCL and MR dual-modality invivo 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

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

2014-11-01

165

Correlation between slow magnetic relaxation and the coordination structures of a family of linear trinuclear Zn(II)-Ln(III)-Zn(II) complexes (Ln = Tb, Dy, Ho, Er, Tm and Yb).  

PubMed

Six linear trinuclear [Ln{Zn(L)(AcO)}(2)]BPh(4) complexes (H(2)L denotes the Schiff-base ligand formed by a condensation reaction between ethylenediamine and two equivalents of o-vanillin), including Ln = Tb (1), Dy (2), Ho (3), Er (4), Tm (5) and Yb (6) were synthesized and were confirmed to be isostructural via X-ray crystallographic analyses. The Ln(III) ion in each complex is deca-coordinated by four equatorial oxygen donors from the methoxo groups of the Schiff-base ligands, two oxygen donors from the acetate anions and four axial oxygen donors from the phenoxo groups of the Schiff-base ligands. AC susceptibility measurements, with an oscillating frequency of 10 to 10,000 Hz, revealed that 1, 2, 4 and 6 show slow magnetic relaxation under a 1000 Oe DC bias field, which occurs via a single process, as confirmed by the semi-circular Cole-Cole plots. These complexes are considered to be field-induced single-molecule magnets under these conditions. The presence or absence of the slow magnetic relaxation process is discussed by correlating the characteristic magnetic anisotropy of each Ln(III) ion with the ligand field anisotropy. PMID:22898750

Maeda, Moe; Hino, Shiori; Yamashita, Kei; Kataoka, Yumiko; Nakano, Motohiro; Yamamura, Tomoo; Kajiwara, Takashi

2012-11-28

166

Direct synthesis of hexagonal NaGdF? nanocrystals from a single-source precursor: upconverting NaGdF? :Yb? ,Tm? and its composites with TiO? for near-IR-driven photocatalysis.  

PubMed

A novel single-source precursor NaGd(TFA)4 (diglyme) (TFA=trifluoroacetate) was synthesized, characterized thoroughly, and used to obtain the hexagonal phase of NaGdF4 nanoparticles as an efficient matrix for lanthanide-doped upconverting nanocrystals (NCs) that convert near-infrared radiation into shorter-wavelength UV/visible light. These NCs were then used to prepare well-characterized TiO2@NaGdF4:Yb(3+),Tm(3+) nanocomposites to extend the absorption range of the TiO2 photocatalyst from the UV to the IR region. While the visible/near IR part of the photoluminescent spectra remains almost unaffected by the presence of TiO2, the UV part is strongly quenched due to the absorption of TiO2 above its gap at approximately 380?nm by energy transfer or FRET. Preliminary results on the photocatalytic activity of the above obtained nanocomposites are presented. PMID:24910325

Chen, Ying; Mishra, Shashank; Ledoux, Gilles; Jeanneau, Erwann; Daniel, Marlene; Zhang, Jinlong; Daniele, Stphane

2014-09-01

167

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

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 4f5d 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 130157 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 OZr 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.

Zhang, Zhi-Jun, E-mail: zhangzj@mail.sic.ac.cn [Key Laboratory of Transparent Opto-Functional Inorganic Materials of Chinese Academy of Sciences, Shanghai Institute of Ceramics, Shanghai, 200050 (China)] [Key Laboratory of Transparent Opto-Functional Inorganic Materials of Chinese Academy of Sciences, Shanghai Institute of Ceramics, Shanghai, 200050 (China); Lin, Xiao [Key Laboratory of Transparent Opto-Functional Inorganic Materials of Chinese Academy of Sciences, Shanghai Institute of Ceramics, Shanghai, 200050 (China) [Key Laboratory of Transparent Opto-Functional Inorganic Materials of Chinese Academy of Sciences, Shanghai Institute of Ceramics, Shanghai, 200050 (China); Graduate School of Chinese Academy of Science, Beijing, 100039 (China); Zhao, Jing-Tai [Key Laboratory of Transparent Opto-Functional Inorganic Materials of Chinese Academy of Sciences, Shanghai Institute of Ceramics, Shanghai, 200050 (China)] [Key Laboratory of Transparent Opto-Functional Inorganic Materials of Chinese Academy of Sciences, Shanghai Institute of Ceramics, Shanghai, 200050 (China); Zhang, Guo-Bin [National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, 230026 (China)] [National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, 230026 (China)

2013-02-15

168

Ce{sub 2}AgYb{sub 5/3}Se{sub 6}, La{sub 2}CuErTe{sub 5}, and Ce{sub 2}CuTmTe{sub 5}: Three new quaternary interlanthanide chalcogenides  

SciTech Connect

Three new ordered quaternary interlanthanide chalcogenides, Ce{sub 2}AgYb{sub 5/3}Se{sub 6}, La{sub 2}CuErTe{sub 5}, and Ce{sub 2}CuTmTe{sub 5}, have been prepared by direct reaction of the elements in molten NaBr at 900 Degree-Sign C. Each compound forms a new structure-type. The Ce{sub 2}AgYb{sub 5/3}Se{sub 6} structure consists of {infinity}{sup 2}{l_brace} [AgYb{sub 5/6}Se{sub 6}]{sup 6-}{r_brace} layers intercalated by Ce{sup 3+} cations. These layers are composed of {infinity}{sup 1}{l_brace} [Yb{sub 5/3}Se{sub 6}]{sup 7-}{r_brace} quadruplet ribbons of [YbSe{sub 6}]{sup 9-} octahedra and infinite {infinity}{sup 1}{l_brace} [AgSe{sub 6}]{sup 11-}{r_brace} double chains of [AgSe{sub 5}]{sup 9-}. The La{sub 2}CuErTe{sub 5} structure is made of one-dimensional {infinity}{sup 1}{l_brace} [CuErTe{sub 5}]{sup 6-}{r_brace} ribbons separated by La{sup 3+} cations. These ribbons are formed by cis-edge sharing {infinity}{sup 1}{l_brace} [CuTe{sub 2}]{sup 3-}{r_brace} tetrahedral chains and trans-edge sharing {infinity}{sup 1}{l_brace} [ErTe{sub 4}]{sup 5-}{r_brace} chains. While La{sub 2}CuErTe{sub 5} crystallizes in the orthorhombic space group Pnma, Ce{sub 2}CuTmTe{sub 5} crystallizes in the monoclinic space group C2/m. The latter crystal structure is assembled from {infinity}{sup 2}{l_brace} [CuTmTe{sub 5}]{sup 6-}{r_brace} layers intercalated by Ce{sup 3+} cations. These layers consist of single {infinity}{sup 1}{l_brace} [TmTe{sub 4}]{sup 5-}{r_brace} chains connected to each other through dimers or pseudo-double chains. - Graphical abstract: [CuTe{sub 4}]{sup 7-} tetrahedra sharing cis-edges to yield chains in the La{sub 2}CuErTe{sub 5}. Highlights: Black-Right-Pointing-Pointer New ordered interlanthanide tellurides. Black-Right-Pointing-Pointer New quaternary chalcogenides. Black-Right-Pointing-Pointer Low-dimensional lanthanide chalcogenide substructures. Black-Right-Pointing-Pointer Flux synthesis of new chalcogenides.

Babo, Jean-Marie [Department of Civil Engineering and Geological Sciences, University of Notre Dame, Notre Dame, IN 46556 (United States); Albrecht-Schmitt, Thomas E., E-mail: talbrec1@nd.edu [Department of Chemistry and Biochemistry, University of Notre Dame, 156 Fitzpatrick Hall, Notre Dame, IN 46556 (United States)

2013-01-15

169

Decay of mass-separated 156Yb  

NASA Astrophysics Data System (ADS)

The isotope 156Yb was produced via the 147Sm(16O, 7n) reaction and was mass separated with an on-line isotope separator. Its decay properties were studied by using ?-ray, x-ray, and ?-particle detectors. The half-life and ? decay energy extracted were found to agree with values from earlier ?-decay investigations. In addition, the (EC+?+) decay of 156Yb was identified for the first time. This decay to 156Tm is accompanied by only one strong ? ray, an E1 transition of 115.2+/-0.2 keV. It is proposed that, as in the case of the 148,150,152Dy decays to odd-odd terbium nuclei, essentially all of the 156Yb ? decay proceeds to a 1+ level in 156Tm at ~ 115 keV by an allowed transition, ft~3.9. This 1+ level then depopulates to a 2- at or near the ground state. Alpha-decay branching ratios were deduced for 156Yb, 156Tm, 152Er, and 152Ho. RADIOACTIVITY 156Yb, 156Tm, 152Er, 152Ho [from 147Sm(16O, 7n)] measured T12, E?, I?, E?, I?, Ix; deduced ft, spins, parities, multipolarities, ?-branching ratios. Mass-separated samples, enriched target.

Mlekodaj, R. L.; Spejewski, E. H.; Toth, K. S.; Ellis-Akovali, Y. A.

1983-03-01

170

Rapid, large-scale, morphology-controllable synthesis of YOF:Ln3+ (Ln = Tb, Eu, Tm, Dy, Ho, Sm) nano-/microstructures with multicolor-tunable emission properties.  

PubMed

YOF:Ln(3+) (Ln = Tb, Eu, Tm, Dy, Ho, Sm) nano-/microstructures with a variety of novel and well-defined morphologies, including nanospheres, nanorod bundles, and microspindles, have been prepared through a convenient modified urea-based homogeneous precipitation (UBHP) technique followed by a heat treatment. The sizes and morphologies of the YOF products could be easily modulated by changing the pH values and fluoride sources. XRD, TG-DTA, FT-IR, SEM, and TEM, as well as photoluminescence (PL) and cathodoluminescence (CL) spectra, were used to characterize the prepared samples. The YOF:Ln(3+) nanospheres show the characteristic f-f transitions of Ln(3+) (Ln = Tb, Eu, Tm, Dy, Ho, Sm) ions and give bright green, red, blue, yellow, blue-green, and yellow-orange emission, respectively, under UV light and low-voltage electron beam excitation. Furthermore, YOF:0.03Tb(3+) phosphors exhibit green luminescence with superior properties in comparison with the commercial phosphor ZnO:Zn to a degree, which is advantageous for improving display quality. Because of the simultaneous luminescence of Ln(3+) in the YOF host, the luminescence colors of YOF:Ln(3+) phosphors can be precisely adjusted by changing the doped Ln(3+) ions and corresponding concentrations, which makes these materials hold great promise for applications in field-emission displays. PMID:24195545

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

2013-11-18

171

Crystal structures and reference powder patterns of BaR{sub 2}ZnO{sub 5} (R = La, Nd, Sm, Eu, Gd, Dy, Ho, Y, Er, and Tm)  

SciTech Connect

Reference x-ray powder patterns and the crystal structures of the lanthanide compounds, BaR{sub 2}ZnO{sub 5}, in which R = La, Nd, Sm, Eu, Gd, Dy, Ho, Y, Er, or Tm were determined by the x-ray Rietveld refinement technique. A structural trend was confirmed for this series of compounds. The compounds with smaller ionic radii (R = Sm, Eu, Gd, Dy, Ho, Y, Er, or Tm) are isostructural to the orthorhombic green phase (BaY{sub 2}CuO{sub 5}). The lattice parameters for compounds with R = Tm to Sm range from a = 7.01855(9) {angstrom} to 7.20452(14) {angstrom}, b = 12.25445(17) {angstrom} to 12.5882(2) {angstrom}, and c = 5.6786(14) {angstrom} to 5.81218(11) {angstrom}, respectively. R is sevenfold coordinated inside a monocapped trigonal prism. These prisms share edges to form wave-like chains parallel to the long b-axis. The BaR{sub 2}ZnO{sub 5} compounds which contain larger size R (La and Nd) crystallize in the tetragonal space group 14/mcm. The lattice parameters are a = 6.90982(10) and c = 11.5977(2) {angstrom} for BaLa{sub 2}ZnO{sub 5}, and a = 6.75979(5) {angstrom} and c = 11.54560(12) {angstrom} for BaNd{sub 2}ZnO{sub 5}. The structure consists of ZnO{sub 4} tetrahedra (instead of planar CuO{sub 4} groups as found in BaR{sub 2}CuO{sub 5}) with 10-fold coordinated bicapped square prismatic Ba and 8-fold coordinated bicapped trigonal prismatic R ions between them. The reference x-ray powder patterns will be submitted to the Powder Diffraction File (PDF).

Kaduk, J.A. [Amoco Corp., Naperville, IL (United States); Wong-Ng, W.; Toby, B.H. [National Inst. of Standards and Technology, Gaithersburg, MD (United States); Greenwood, W.; Dillingham, J. [Univ. of Maryland, College Park, MD (United States). Geology Dept.

1999-03-01

172

(BMI)3LnCl6 crystals as models for the coordination environment of LnCl3 (Ln = Sm, Eu, Dy, Er, Yb) in 1-butyl-3-methylimidazolium chloride ionic-liquid solution.  

PubMed

A series of (BMI)3LnCl6 (Ln = Sm, Eu, Dy, Er, Yb) crystals was prepared from solutions of LnCl3 dissolved in the ionic liquid, 1-butyl-3-methylimidazolium chloride (BMICl). Crystals with Ln = 5% Sm + 95% Gd and with Ln = 5% Dy + 95% Gd were also grown to assess the importance of cross-relaxation in the Sm and Dy samples. The crystals are isostructural, with monoclinic space group P21/c and four formula units per unit cell. The first coordination sphere of Ln(3+) consists of six Cl(-) anions forming a slightly distorted octahedral LnCl6(3-) center. The second coordination sphere is composed of nine BMI(+) cations. The emission spectra and luminescence lifetimes of both (BMI)3LnCl6 crystals and LnCl3 in BMICl solution were measured. The spectroscopic similarities suggest that crystalline (BMI)3LnCl6 provides a good model of the Ln(3+) coordination environment in BMICl solution. PMID:24849287

Han, Yulun; Lin, Cuikun; Meng, Qingguo; Dai, Fengrong; Sykes, Andrew G; Berry, Mary T; May, P Stanley

2014-06-01

173

Power Scaling of Tm:fiber Lasers to the kW Level Peter F. Moulton  

E-print Network

Power Scaling of Tm:fiber Lasers to the kW Level Peter F. Moulton Q-Peak, Inc. CREOL Industrial · Fundamentals of Tm:silica fiber lasers · Fiber laser setup and results Support: HEL-JTO Contract Nos. FA9451 advances in Tm-doped fiber-laser efficiencies show levels approaching Yb fibers #12;Fundamentals of Tm

Van Stryland, Eric

174

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

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.

Babo, Jean-Marie [Department of Civil Engineering and Geological Sciences and Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556 (United States); Albrecht-Schmitt, Thomas E., E-mail: talbrec1@nd.edu [Department of Civil Engineering and Geological Sciences and Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556 (United States)

2012-03-15

175

Terpyridine-Based Heteroditopic Ligand for Ru(II)Ln3(III) Metallostar Architectures (Ln = Gd, Eu, Nd, Yb) with MRI/Optical or Dual-Optical Responses.  

PubMed

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

Boulay, Alexandre; Deraeve, Cline; Vander Elst, Luce; Leygue, Nadine; Maury, Olivier; Laurent, Sophie; Muller, Robert N; Mestre-Voegtl, Batrice; Picard, Claude

2015-02-16

176

Materials Science and Engineering B105 (2003) 9196 Photoluminescence studies of rare earth (Er, Eu, Tm) in situ doped GaN  

E-print Network

doping of wide band-gap semiconductors such as GaN, AlN, and SiC has led to the observation of intense RE, Tm) in situ doped GaN U. Hömmericha,, Ei Ei Nyeina, D.S. Leeb, J. Heikenfeldb, A.J. Stecklb, J The emission properties of rare earth (RE)-doped GaN are of significant current interest for applications

Steckl, Andrew J.

177

High-temperature resistivity of RBa/sub 2/Cu/sub 3/O/sub 7-//sub y/, where R = La, Pr, Nd, Sm, Eu, Dy, Ho, Er, and Tm  

SciTech Connect

The electrical resistivity rho of RBa/sub 2/Cu/sub 3/O/sub 7-//sub y/, where R = La, Pr, Nd, Eu, Dy, Ho, Er, Sm, and Tm has been measured from room temperature up to 900 K. No essential difference in the transport properties was found except for LaBa/sub 2/Cu/sub 3/O/sub 7-//sub y/ and PrBa/sub 2/Cu/sub 3/O/sub 7-//sub y/ which shows an anomaly in the electrical resistivity. SmBa/sub 2/Cu/sub 3/O/sub 7-//sub y/ samples with various oxygen contents are studied in detail. Metallic behavior and linear temperature dependence of rho have been found for SmBa/sub 2/Cu/sub 3/O/sub 7-//sub y/ with 0

Yang, H.C.; Hsieh, M.H.; Sung, H.H.; Chen, C.H.; Horng, H.E.; Kan, Y.S.; Chen, H.C.; Jao, J.C.

1989-05-01

178

Theoretical Study on Structural Stability of Fully Filled p-Type Skutterudites RETM4Sb12 ( RE = Rare Earth; TM = Fe, Ru)  

NASA Astrophysics Data System (ADS)

The structural stability of filled p-type skutterudites RETM4Sb12 ( RE = rare earth; TM = Fe, Ru) was studied via ab initio calculations. Most of the RE metals (La-Ho and Yb) could be filled into the cages (voids) of Fe4Sb12 to form stable filled skutterudites. However, only a few RE metals (La-Nd and Eu) could be stably filled into the cage of Ru4Sb12-based skutterudites. Systematic analysis of bonding energy showed that the structural stability could be attributed to ionic radius and effective charge state differences of the RE fillers. Resonant rattling frequencies of the fillers in both Fe4Sb12- and Ru4Sb12-based skutterudites were also studied.

Chen, Zhuo; Yang, Jiong; Liu, Ruiheng; Xi, Lili; Zhang, Wenqing; Yang, Jihui

2013-08-01

179

Upconversion luminescence enhancement of Yb(3+), Nd(3+) sensitized NaYF4 core-shell nanocrystals on Ag grating films.  

PubMed

Here, we report the wavelength-dependent and angle-dependent upconversion luminescence (UCL) enhancement of NaYF4:Yb(3+),Tm(3+)@NaYF4:Yb(3+),Nd(3+) core-shell nanocrystals (NCs) resulting from Ag grating structures, which provides a novel insight for improving UCL. PMID:25502851

Xu, Wen; Song, Hongwei; Chen, Xu; Wang, Haiyu; Cui, Shaobo; Zhou, Donglei; Zhou, Pingwei; Xu, Sai

2015-01-28

180

M-shell x-ray production cross sections for 19 elements in the range Z=54-92 by H/sup +/, He/sup +/ and He/sup + +/ ions from 300 keV to 40 MeV. [Xe, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Yb, Hf, Ta, W, Pt, Au, Hg, Pb, Bi, and U  

SciTech Connect

In this report, the measurements done over the last three decades at various laboratories are surveyed. The elements studied were Xe, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Yb, Hf, Ta, W, Pt, Au, Hg, Pb, Bi, and U. The projectile energies investigated range from 300 keV to 40 MeV for the protons and 250 keV to 2.5 MeV for He/sup +/ ions. Also reported are the M-shell x-ray production cross sections of some rare-earth elements recently measured at NTSU. For these measurements the energy of incident /sup 1/H/sup +/ and /sup 4/He/sup +/ ions ranged from 0.25 to 2.5 MeV. The experimental data are compared to the M-shell ionization cross section predictions of first Born approximation, i.e. the PWBA for direct ionization plus the OBK of Nikolaev for electron capture. Comparison is also made with the theory by Brandt and Lapicki that goes beyond the first Born approximation, i.e. the ECPSSR approach which accounts for the Energy loss, Coulomb deflection and Relativistic effects in the Perturbed Stationary State theory.

Mehta, R.; Duggan, J.L.; Kocur, P.M.; Lapicki, G.; McDaniel, F.D.; Price, J.L.

1983-04-01

181

EU Business  

NSDL National Science Digital Library

EU Business is provided by Europanet. It aims to provide selected business information to the busy business person. Information available at the site includes European Union (EU) law, business developments in Europe, finance and EU programs. The site also keeps track of European Commission proposals and the progress of draft legislation. Users interested in doing business in Europe will find this site a useful guide to facilitate the process.

182

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

PubMed

Using a high-temperature solid-state reaction, the chlorine in Ba2 YB2 O6 Cl is gradually replaced by F, and a new compound with the nominal chemical formula Ba2 YB2 O6 F and two phosphors doped with Ce(3+) and Eu(3+) , respectively, are obtained. X-Ray diffraction and photoluminescence spectroscopy are used to characterize the as-synthesized samples. The as-synthesized Ba2 YB2 O6 Cl exhibits bright blue emission in the spectral range?~?330-410?nm with a maximum around 363?nm under X-ray or UV excitation. Ba2 YB2 O6 F:0.01Ce(3+) exhibits blue emission in the range?~?340-570?nm with a maximum around 383?nm. Ba2 YB2 O6 F:0.01Eu(3+) exhibits a predominantly (5) D0 -(7) ?F2 emission (~610?nm) and the relative intensities of the (5) D0 -(7) ?F0,1,2 emissions are tunable under different wavelength UV excitation. The luminescence behaviors of the two phosphors are explained simply in terms of the host composition and site occupancy probability of Ce(3+) and Eu(3+) , respectively. The results indicate that these phosphors have potential application as a blue phosphor or as a red phosphor. Copyright 2014 John Wiley & Sons, Ltd. PMID:24954091

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

2015-05-01

183

K-shell absorption jump factors and jump ratios in elements between Tm ( Z = 69) and Os ( Z = 76) derived from new mass attenuation coefficient measurements  

Microsoft Academic Search

The K-shell absorption jump factors and jump ratios were derived from new mass attenuation coefficients measured using an energy dispersive X-ray fluorescence (EDXRF) spectrometer for Tm, Yb elements being Tm2O3, Yb2O3 compounds and pure Lu, Hf, Ta, W, Re and Os. The measurements, in the region 5677keV, were done in a transmission geometry utilizing the K?1, K?2, K?1 and K?2

Necati Kaya; Engin Tirasoglu; Gkhan Apaydin; Volkan Aylikci; Erhan Cengiz

2007-01-01

184

Seniority isomerism in the N]=82 isotone152Yb; Favoured ? transitions ?h 11/2? vh 9/2  

NASA Astrophysics Data System (ADS)

The reaction58Ni?96Ru has been investigated with ? spectroscopic methods and pulsed-beam techniques. A level scheme of the magic nucleus152Yb has been established. The half-life of the isomeric 10+ state was found to be 395 ?s. The result is discussed in the frame-work of the seniority scheme. Theory and experiment show excellent agreement for the half-lives of the 10+ states in the N=82 isotones148Dy,150Er and [152Yb. A level scheme of151Tm, consisting of ten excited states, has been established. ?-decay schemes of [152Yb (3.20.3 s),152Tm( m) (8.01.0 s) and151Tm (3.80.8 s) have been derived. The log ft value of the ? transition152Yb (00)?152Tm (1+) has been determined to be about 3.4. It was found that the ft values of the favoured ? transitions 0+?1+ in the ? decays of [148Dy,150Er and152Yb are almost inversely proportional to the numbers of protons out of the h 11/2 subshell.

Nolte, E.; Korschinek, G.; Setzensack, Ch.

1982-03-01

185

Damping in Yb nuclei  

SciTech Connect

In a mixture of three Yb nuclei, we find the rotational damping widths vary from 180 keV at 1.1 MeV {gamma}-ray energy to 290 keV at 1.5 MeV, and the average compound damping widths (or spreading widths) vary from 40 keV at 1.1 MeV {gamma}-ray energy to 60 keV at 1.3 MeV. The simulations also suggest extensive motional narrowing.

Stephens, F.S.; Deleplanque, M.A.; Lee, I.Y.; Ward, D.; Fallon, P.; Cromaz, M.; Macchiavelli, A.O.; Clark, R.M.; Diamond, R.M.; Gorgen, A.

2002-07-01

186

Valences of dopants in Eu2+ persistent luminescence materials  

NASA Astrophysics Data System (ADS)

The existence and effect of different rare earth (R2+/3+/IV) ions in SrAl2O4:Eu2+,R3+ and M2MgSi2O7:Eu2+,R3+ (M: Sr, Ba) persistent luminescence materials was studied with XANES (x-ray absorption near edge structure) measurements at HASYLAB/DESY (Hamburg, Germany) and MAX-lab (Lund, Sweden). The experiments were carried out at 298 K for selected rare earth (co-)dopants (Eu2+; Ce3+, Nd3+, Sm3+, Dy3+ and Yb3+). The co-existence of Eu2+ and Eu3+ was observed in all materials. The co-dopants were always in the trivalent form.

Lastusaari, M.; Brito, H. F.; Carlson, S.; Hls, J.; Laamanen, T.; Rodrigues, L. C. V.; Welter, E.

2014-04-01

187

A dosimetric comparison of {sup 169}Yb versus {sup 192}Ir for HDR prostate brachytherapy  

SciTech Connect

For the purpose of evaluating the use of {sup 169}Yb for prostate High Dose Rate brachytherapy (HDR), a hypothetical {sup 169}Yb source is assumed with the exact same design of the new microSelectron source replacing the {sup 192}Ir active core by pure {sup 169}Yb metal. Monte Carlo simulation is employed for the full dosimetric characterization of both sources and results are compared following the AAPM TG-43 dosimetric formalism. Monte Carlo calculated dosimetry results are incorporated in a commercially available treatment planning system (SWIFT{sup TM}), which features an inverse treatment planning option based on a multiobjective dose optimization engine. The quality of prostate HDR brachytherapy using the real {sup 192}Ir and hypothetical {sup 169}Yb source is compared in a comprehensive analysis of different prostate implants in terms of the multiobjective dose optimization solutions as well as treatment quality indices such as Dose Volume Histograms (DVH) and the Conformal Index (COIN). Given that scattering overcompensates for absorption in intermediate photon energies and distances in the range of interest to prostate HDR brachytherapy, {sup 169}Yb proves at least equivalent to {sup 192}Ir irrespective of prostate volume. This has to be evaluated in view of the shielding requirements for the {sup 169}Yb energies that are minimal relative to that for {sup 192}Ir.

Lymperopoulou, G.; Papagiannis, P.; Sakelliou, L.; Milickovic, N.; Giannouli, S.; Baltas, D. [Nuclear and Particle Physics Section, Physics Department, University of Athens, Panepistimioupolis, Ilisia, 157 71 Athens (Greece); Department of Medical Physics and Engineering, Strahlenklinik, Klinikum Offenbach, 63069 Offenbach (Germany); Pi-Medical Ltd., Research and Development Dept., Gennimata 2 Str., 115 24, Ampelokipoi, Athens (Greece); Department of Medical Physics and Engineering, Strahlenklinik, Klinikum Offenbach, 63069 Offenbach (Germany) and Nuclear and Particle Physics Section, Physics Department, University of Athens, Panepistimioupolis, Ilisia, 157 71 Athens (Greece)

2005-12-15

188

Power scaling of resonantly pumped Yb-free Er-doped fiber laser  

NASA Astrophysics Data System (ADS)

Even though Yb-doped fiber lasers are known to be the most powerful and most efficient among all fiber lasers, recent successes in the eye-safe ~1.5?m Yb-Er-doped fiber lasers (where Er is excited through Yb-Er energy transfer) are quite impressive. Output power of Yb-Er fiber lasers reached ~300 W level and their optical-to-optical efficiency, for somewhat lower power levels, is exceeding 40% [2]. Nevertheless, as far as real eye safety is concerned, multi-hundred Watt Yb-Er fiber lasers typically carry in their output a significant fraction of competing 1-?m Yb emission, which totally compromises an eye-safe side of the application. Ultimate efficiency and thermal management of Yb-Er approach are also suffering due to: (i), inefficiency of Yb-Er energy transfer and, (ii), gigantic ~40% quantum defect of Er-doped fiber pumped at 9XX-nm. Presented here are very recent and successful results on power scaling of resonantly pumped Yb-free Er-doped fiber lasers and amplifiers. We are reporting an Ybfree Er-doped cladding-pumped fiber power scaling to ~50 W with ~57% optical-tooptical efficiency [6] in a few first experimental steps. This is clear manifestation of scaling potential of this most efficient approach to high power eye-safe fiber laser. The only competing approach to scalable eye-safe fiber laser implements Tm3+-doped fibers pumped at ~790 nm while relying on well known "2-for-1" process leading to quite efficient excitation of the ~2?m Tm3+ laser operation [4]. This approach has operational optical-to-optical efficiency quantum limit of ~75% [4], while resonantly pumped Ybfree Er-doped fiber laser's optical-to-optical efficiency quantum limit exceeds 95% due to its low-quantum-defect (QD) pump-lase scheme. Significant scaling potential of resonantly-pumped Yb-free Er-doped fiber lasers and amplifiers sets a path to an eye-safe fiber laser concept with drastically relaxed thermal management and nearly diffraction limited beam quality at ~kW-=-class power levels as well as high electrical to optical efficiency.

Dubinskii, M.; Zhang, J.; Ter-Mikirtychev, V.

2009-05-01

189

Yb:S-FAP lasers  

NASA Astrophysics Data System (ADS)

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

Schaffers, Kathleen I.

2004-09-01

190

Effect of Yb3+ concentration on optical properties of Yb:CaF2 transparent ceramics  

E-print Network

Effect of Yb3+ concentration on optical properties of Yb:CaF2 transparent ceramics Andras Lyberis Keywords: CaF2 Ytterbium Transparent ceramics Spectroscopy a b s t r a c t In Yb:CaF2, the coordination, and fluorescence lifetime of 0.1, 1, 5, and 10 at% Yb:CaF2 ceramics to determine whether Yb3+ substitutes

191

Norton GhostTM User's Guide Norton GhostTM  

E-print Network

Norton GhostTM User's Guide #12;Norton GhostTM User's Guide The software described in this book. Trademarks Symantec, the Symantec logo, Norton Ghost, Ghost Walker, Ghost Explorer, and GDisk are trademarks

Kleinfeld, David

192

Structure and properties of RELiGe2 (RE = La-Nd, Sm-Gd, Yb) compounds  

NASA Astrophysics Data System (ADS)

Single phase samples of RELiGe2 (RE = La-Nd, Sm-Gd, Yb) were synthesized in niobium tubes by high-frequency (HF) heating method. RELiGe2 compounds crystallize in the CaLiSi2 type structure, space group Pnma. LaLiGe2 is diamagnetic, while PrLiGe2, NdLiGe2, EuLiGe2, GdLiGe2 and YbLiGe2 follow Curie-Weiss behavior above 50 K. All compounds are metallic conductors with a specific resistivity at room temperature within the range of 250-900 ??cm.

Iyer, Abishek K.; Subbarao, Udumula; Peter, Sebastian C.

2013-02-01

193

GEOMAG[TM] Paradoxes  

ERIC Educational Resources Information Center

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,

Defrancesco, Silvia; Logiurato, Fabrizio; Karwasz, Grzegorz

2007-01-01

194

CLEO 2007: CFJ -Yb Lasers Low-threshold On-chip Yb3+ Silica Laser  

E-print Network

CLEO 2007: CFJ - Yb Lasers Low-threshold On-chip Yb3+ Silica Laser Eric Ostby, Lan Yang*, and Kerry University #12;CLEO 2007: CFJ - Yb Lasers Low-Threshold Yb3+ Lasers · Fabry-Perot type Pth Finesse · Microchip lasers - 71 mW 50 · Fiber lasers - 230 µW 500 · Ring type · Microtoroid - ? 10,000 · High Quality

195

Probing dual mode emission of Eu3+ in garnet phosphor  

NASA Astrophysics Data System (ADS)

Eu3+ doped and Eu3+, Yb3+ co-doped Gd3Ga5O12 phosphors have been developed by facile solid state reaction method which can be easily scaled-up in large quantity. The synthesis has been optimized to get a single phase material at 1300 C. The phase and crystal parameters have been analyzed by using X-ray diffraction measurement. Photoluminescence excitation (monitored for the 5D0 ? 7F1 transition of Eu3+) depicts that the active ion (Eu3+) can be excited through direct excitation into 4f band of Eu3+, through charge transfer band (Eu3+-O2-) excitation and also through the excitation into 8S7/2 ? 6IJ intra f-f transition of Gd3+ ion, which significantly all together cover a broad excitation region in 200-420 nm. In addition, in the presence of Yb3+ ions, the emission is also achieved by near infrared excitation (976 nm), through a typical upconversion (UC) process. Thus, the material efficiently behaves as a dual mode emitting phosphor (emission is achieved both through normal fluorescence and through UC process). The conversion efficiency of silicon solar cells is only 15% of terrestrial solar energy for 200-400 nm region and also the sub-band gap energy (in infrared region) is lost as heat; therefore, this kind of dual mode phosphors may be used to overcome the above mentioned incomplete utilization of the solar spectrum and can open realm of new possibilities for energy harvesting.

Singh, S. K.; Gi Lee, Dong; Soo Yi, Soung; Jang, Kiwan; Shin, Dong-Soo; Hyun Jeong, Jung

2013-05-01

196

Phase equilibrium and intermediate phases in the Eu-Sb system  

SciTech Connect

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}.

Abdusalyamova, M.N. [Institute of Chemistry of Tajik Academy of Sciences, Ajni Str. 299/2, 734063 Dushanbe (Tajikistan); Vasilyeva, I.G., E-mail: kamarz@niic.nsc.ru [Nikolaev Institute of Inorganic Chemistry, Russian Academy of Sciences, Siberian Branch, Lavrentiev Avenue, 3, 630090 Novosibirsk (Russian Federation)

2011-10-15

197

Ceramic Yb: YAG microchip laser  

NASA Astrophysics Data System (ADS)

An efficient microchip laser utilizing domestically fabricated ceramic Yb:YAG is presented. In continuous-wave (cw) and Q-switched operation, the laser maintains linear polarization with 22 dB extinction and oscillates in the fundamental TEM 00 mode. In cw mode, the ceramic laser has an output power of 2.25 W and a slope efficiency of 66%. When passively Q-switched at 11.4 kHz repetition rate using Cr:YAG, the 1.9 ns pulse has an average power of 0.72 W and a slope efficiency of 46%. To our knowledge, this is currently the highest reported power from a ceramic Yb:YAG laser. The laser performance of the 5-at.% ceramic is compared to a 10-at.% single crystal, and we discuss how the scattering loss and storage efficiency of the ceramic medium affect its laser characteristics.

Ostby, Eric P.; Ackerman, Richard A.; Huie, Jean C.; Gentilman, Richard L.

2007-05-01

198

Upconversion emission in (Ln,Yb):KLu(WO4)2 nanocrystals for white light generation  

NASA Astrophysics Data System (ADS)

Optical active lanthanides ions in double tungstates exhibit high emission cross section with low concentration quenching. Production of double tungstates nanocrystals doped with lanthanide ions is suitable for applications in white light emitters if high quantum yield is reached. In this work lanthanide doped (Ln:Yb):KLu(WO4)2 nanocrystals (Ln = Er, Tm, Ho) upconversion emission properties have been study after 980 nm diode laser excitation at 14-334 W/cm2. From CIE chromaticity theory a possible mixture weight ratio to obtain a white light emitter powder was predicted. Luminescence under 980 nm of the (Ln:Yb):KLu(WO4)2 nanocrystals was study and decay times under 460 nm was measured. Reduction of the upconversion quantum yield was observed in the case of physical mixture of nanocrystals.

Barrera, E. W.; Pujol, M. C.; Carvajal, J. J.; Mateos, X.; Sol, R.; Massons, J.; Speghini, A.; Bettinelli, M.; Cascales, C.; Aguil, M.; Daz, F.

2014-04-01

199

Effects of Yb3+ in Er3+/Yb3+ Codoped Fluorophosphate Glasses  

NASA Astrophysics Data System (ADS)

For the Er3+/Yb3+ codoped fluorophosphate glasses, Judd-Ofelt theory is used to analyse the influence of YbF3 as not a sensitizer but an average component on the spectroscopic properties around 1530 nm emission. The double roles of Yb3+, as a sensitizer and as an average component, are discussed. It is found that Yb3+ as an average component contributes to the increase of fluorescence lifetime, and Yb3+ as a sensitizer has the best sensitization when its concentration is 2.4 mol%.

Liao, Mei-Song; Fang, Yong-Zheng; Hu, Li-li; Zhang, Li-Yan; Xu, Shi-Qing

2007-04-01

200

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

PubMed

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

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

2015-04-01

201

High-Repetition-Rate Femtosecond Yb  

E-print Network

pending covering the Yb-fibre laser system and a high-energy optical parametric oscillator (OPO) system systems are available to purchase from the university commercialisation office ­ prices & full, up to 500 MHz · No water cooling required TECHNOLOGY The laser design utilizes a highly- doped Yb

Painter, Kevin

202

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

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

White, J.P. III; Deng, H.; Boyd, E.P.; Gallucci, J.; Shore, S.G. (Ohio State Univ., Columbus, OH (United States))

1994-04-13

203

Neutron-diffraction study of the magnetic and orbital ordering in 154SmNiO3 and 153EuNiO3  

Microsoft Academic Search

Neutron-powder-diffraction experiments on 154SmNiO3 and 153EuNiO3 at different temperatures have been performed. At variance with the case of Pr and Nd nickelates, the metal-insulator transition temperature in these compounds are different from the Nel temperature (TM-I~400 K, TN~230 K for Sm and TM-I~480 K, TN~220 K for Eu) so that the magnetic ordering develops upon cooling in an insulating matrix.

J. Rodrguez-Carvajal; S. Rosenkranz; M. Medarde; P. Lacorre; M. T. Fernandez-Daz; F. Fauth; V. Trounov

1998-01-01

204

Facing the Future (TM)  

NSDL National Science Digital Library

Facing the Future(TM) provides educational materials and professional development opportunities for educators that address environmental issues such as population growth, poverty and equity, consumption trends, peace and conflict, health, climate change, and sustainability. These materials include textbooks for students, service learning and action projects, and curriculum units with activities and lesson plans that meet educational standards. The organization's web site provides information on downloading and/or purchasing these materials, information on a featured curriculum unit, news and event announcements, and information on professional development opportunities for in-service and pre-service educators.

205

Structural, morphological and spectroscopic properties of Eu{sup 3+}-doped rare earth fluorides synthesized by the hydrothermalmethod  

SciTech Connect

Rare earth fluorides (REF{sub 3}, RE=Y, La, Gd or Yb) doped with 5% of Eu{sup 3+} ions were synthesized via the hydrothermal method and their physicochemical properties were compared. The synthesis was carried out in an aqueous medium at elevated pressure and temperature. The reaction was performed in situ, with use of NaBF{sub 4} as a source of fluoride ions. Structural and morphological properties of obtained nanophosphors were characterized with the use of powder X-ray diffraction (XRD), transmission electron microscopy (TEM) and Raman spectroscopy. Synthesized products were nanocrystalline with hexagonal or orthorhombic crystal structures. They showed different morphology, from nanoplates to nanorings, depending on the used REF{sub 3} fluoride as the host for the Eu{sup 3+} ions. The elemental composition was confirmed by the energy-dispersive X-ray spectroscopy (EDX) results. Spectroscopic properties were investigated by measuring the excitation and emission spectra. Also luminescence lifetimes were determined. The synthesized materials showed bright red luminescence, due to the presence of Eu{sup 3+} ions in their structure. - Graphical abstract: Luminescence spectra of the REF{sub 3}:Eu{sup 3+} (RE=Y, La, Gd and Yb) fluorides and their TEM images as background. Highlights: ? Nanocrystalline fluorides were synthesized using modified hydrothermal method. ? Structural and morphological properties of in situ prepared nanomaterials were studied. ? Luminescence properties of REF{sub 3}:Eu{sup 3+} (RE=Y, La, Gd, Yb) were compared and investigated.

Grzyb, Tomasz, E-mail: tgrzyb@amu.edu.pl [Department of Rare Earths, Faculty of Chemistry, Adam Mickiewicz University, Grunwaldzka 6, Pozna? 60-780 (Poland); Runowski, Marcin [Department of Rare Earths, Faculty of Chemistry, Adam Mickiewicz University, Grunwaldzka 6, Pozna? 60-780 (Poland); Szczeszak, Agata [Institute of Molecular Physics, Polish Academy of Sciences, M. Smoluchowskiego 17, Pozna? 60-179 (Poland); Lis, Stefan [Department of Rare Earths, Faculty of Chemistry, Adam Mickiewicz University, Grunwaldzka 6, Pozna? 60-780 (Poland)

2013-04-15

206

The tmRNA website  

PubMed Central

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. PMID:25378311

Hudson, Corey M.; Williams, Kelly P.

2015-01-01

207

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

PubMed

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 Yb(3+)/Er(3+), Yb(3+)/Ho(3+) and Yb(3+)/Tm(3+) co-doped YOF nanospheres. The MTT assay indicates that YOF nanospheres exhibit good biocompatibility. Especially, the emission spectrum of YOF: 0.20Yb(3+), 0.04Er(3+) nanospheres is dominated by a single red emission at 660 nm, which falls into the "optical window" of biological tissues. The application of YOF: 0.20Yb(3+), 0.04Er(3+) nanospheres in the cell imaging is also investigated, which shows a bright-red emission without background noise. PMID:24827577

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

2014-06-21

208

NanoKids(TM)  

NSDL National Science Digital Library

NanoKids(TM) is an education and outreach program for intermediate-level (middle-school) students intended to increase their knowledge of nanotechnology and emerging research and technology in this field, which involves working with objects on the molecular and atomic scale (as small as one-billionth of a meter). Site materials include a series of self-contained lessons accompanied by animated videos and an online workbook for students. There is also a sample test and additional resources for teachers (slide presentations, games, and other materials). The site also offers an overview of the project and its participants, biographical "sketches" of the characters used in the animations, and one-page features that explain the nanometer scale, the countries and scientists involved in nanotechnology, and atoms, molecules, and bondng. Some materials on the site are available in Spanish.

209

Localized Electron Magnetism in the Icosahedral AuAlTm Quasicrystal and Crystalline Approximant  

NASA Astrophysics Data System (ADS)

We report the magnetic, thermal, and transport properties of the Au-Al-Tm quasicrystal, which is isostructural to the first and only quasicrystal Au-Al-Yb that shows a novel quantum critical behavior. The Tm-based quasicrystal undergoes a spin-glass-like freezing below Tf 0.4 K. We also synthesize the Au-Al-Tm approximant to the quasicrystal and find that it shows a similar spin-glass-like freezing below Tf 0.3 K. Both the quasicrystal and the approximant follow the Curie-Weiss law in a wide temperature range above Tf, indicating that the 4f electrons are well localized on the vertices of the icosahedron. The interspin interaction is antiferromagnetic and its magnitude is as small as 1 K. The spin-glass-like freezing is presumably driven by the combined effect of the chemical disorder of Au/Al ions and the frustrated nature of the icosahedron. On the basis of these results, we discuss a possible origin of the unusual quantum criticality observed in the Yb-based system.

Nakayama, Mika; Tanaka, Katsumasa; Matsukawa, Shuya; Deguchi, Kazuhiko; Imura, Keiichiro; Ishimasa, Tsutomu; Sato, Noriaki K.

2015-02-01

210

Crystal structures and magnetic properties of novel rare-earth copper sulfides, EuRCuS3 (R = Y, Gd Lu)  

NASA Astrophysics Data System (ADS)

Novel quaternary rare-earth copper sulfides EuRCuS3 (R = Y, Gd-Lu excluding Ho, Er) have been investigated by means of x-ray diffraction, magnetic susceptibility, magnetization, and specific heat measurements. These compounds crystallize in the Eu2CuS3-type structure for R = Y, Gd-Dy and in the KZrCuS3-type structure for R = Tm-Lu. Both EuY CuS3 and EuLuCuS3 show a ferromagnetic transition and the other EuRCuS3 compounds show a ferrimagnetic transition at around 5.0 K.

Wakeshima, Makoto; Furuuchi, Fumito; Hinatsu, Yukio

2004-08-01

211

Structure and magnetic properties of sulfides of the type Cd RE2S 4 and Mg(Gd xYb 1- x) 2S 4  

NASA Astrophysics Data System (ADS)

Cd RE2S 4 ( RE = Gd, Tb, Dy, Ho, Er, Tm, and Yb) and Mg(Gd xYb 1- x) 2S 4 were prepared by solid-state reactions. All the cadmium-containing compounds are cubic, i.e., the Th 3P 4 structure for Gd, Tb, and Dy and the spinel type for all the others. The first three compounds were deficient in CdS. In the case of the Mg system, for x = 1 the system is cubic Th 3P 4, for x = 0 cubic spinel, and for 0 < x < 1 orthorhombic MnY 2S 4 (Cmc2 1). All the materials studied are paramagnetic above 77 K. Below 77 K in the magnesium family both cubic materials are paramagnetic down to 4.2 K and the orthorhombic materials show magnetic ordering. In the cadmium family all but CdTm 2S 4 show exchange coupling.

Ben-Dor, L.; Shilo, I.

1980-11-01

212

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

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.

Kazei, Z. A., E-mail: kazei@plms.phys.msu.ru; Snegirev, V. V.; Andreenko, A. S. [Moscow State University (Russian Federation); Kozeeva, L. P. [Russian Academy of Sciences, Nikolaev Institute of Inorganic Chemistry, Siberian Branch (Russian Federation)

2011-08-15

213

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)

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

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

2014-05-01

214

Yb_14ZnSb_11: an intermediate Yb valence compound  

NASA Astrophysics Data System (ADS)

Results are presented of thermodynamic, transport and x-ray diffraction measurements of the compound Yb_14ZnSb_11. This compound is isostructural with a series of A_14MPn_11 Zintl compounds, which are characterised by a small semiconducting gap (A = a divalent metal ion, M = a trivalent metal ion, Pn =3D a pnictide group element). However, Yb_14ZnSb_11 appears to be metallic. Furthermore, the above data are all consistent with an intermediate Yb valence (homogeneous mixed valence) scenario, with a spin fluctuation temperature of approximately 85 K. The driving force behind this situation is a competition between the electron affinities of divalent Yb and Zn: a competition that Yb^2+ cannot hope to win. Requiring charge balance accounts for the fractional formal Yb valence. That is to say that the charge balance arguements that work for other 14-1-11 semiconducting compounds with the same structure, such as Yb_14AlSb_11, also appear to work when extended into the weakly metallic regime of Yb_14ZnSb_11.

Fisher, I. R.; Bud'Ko, S. L.; Song, C.; Canfield, P. C.; Ozawa, T. C.; Kauzlarich, S. M.

2000-03-01

215

The formation of Yb silicates and its luminescence in Yb heavily doped silicon oxides after high temperature annealing  

NASA Astrophysics Data System (ADS)

We report on the formation of ytterbium (Yb) silicates and its photoluminescence (PL) properties for heavily Yb doped Si oxide films after various annealings. X-ray diffraction patterns and transmission electron microscopy indicate that different Yb silicates have formed in the oxides upon 1100 and 1200 C annealing. The Yb PL intensities after the high temperature annealings are much stronger than those after lower temperatures, which indicates that the Yb silicates have higher emission efficiency than the Yb configurations found for lower temperature annealing. The PL intensities of the films can be altered considerably by secondary oxidizing or annealing in forming gas (N2 + 7% H2) ambience.

Heng, C. L.; Li, J. T.; Su, W. Y.; Han, Z.; Yin, P. G.; Finstad, T. G.

2015-04-01

216

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

PubMed

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

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

2015-02-01

217

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

E-print Network

, nominally nonmagnetic Eu3+ ions 4f6 , S=3, L=3, J=0 within the context of the rocksalt structure compounds EuN and EuP. Both compounds are ionic Eu3+ ; N3- and P3- semimetals similar to isovalent Gd 2005 We consider the electronic structure of, and magnetic exchange spin interactions between

Pickett, Warren

218

LiquichekTM Diabetes Control  

E-print Network

LiquichekTM Diabetes Control Bio-Rad Laboratories D I A B E T E S / H E M O G L O B I N C O N T R O L S #12;LiquichekTM Diabetes Control Hemoglobin A1C Hemoglobin, Total A liquid human whole blood based product designed to monitor the performance of hemoglobin tests associated with diabetes

Rodriguez, Carlos

219

Strategy for thermometry via Tm?-doped NaYF? core-shell nanoparticles.  

PubMed

Optical thermometers usually make use of the fluorescence intensity ratio of two thermally coupled energy levels, with the relative sensitivity constrained by the limited energy gap. Here we develop a strategy by using the upconversion (UC) emissions originating from two multiplets with opposite temperature dependences to achieve higher relative temperature sensitivity. We show that the intensity ratio of the two UC emissions, F(2,3) and G?, of Tm? in ?-NaYF?:20%Yb?, 0.5%Tm?/NaYF?:1%Pr? core-shell nanoparticles under 980 nm laser excitation exhibits high relative temperature sensitivity between 350 and 510 K, with a maximum of 1.53%??K? at 417 K. This demonstrates the validity of the strategy, and that the studied material has the potential for high-performance optical thermometry. PMID:25490653

Zhou, Shaoshuai; Jiang, Guicheng; Li, Xinyue; Jiang, Sha; Wei, Xiantao; Chen, Yonghu; Yin, Min; Duan, Changkui

2014-12-01

220

Yb:S-FAP laser performance  

NASA Astrophysics Data System (ADS)

We have demonstrated the highest long-pulse efficiency and highest Q-switched energy reported to date for a Yb:S-FAP laser. THe Yb:S-FAP laser was pumped with a flashlamp pumped, free-running Cr:LiSAF laser. Threshold pump energy was extremely low, typically 30 mJ. Maximum output energy was 370 mJ at 1.047 micrometers with 650 mJ of pump incident on the Yb:S-FAP crystal. We obtained total optical-to-optical conversion efficiency of up to 57 percent in the long pulse mode. This is the highest conversion efficiency ever reported for this material in high energy, pulsed mode. Three samples of Yb:S-FAP of differing dimensions, doping, and crystal quality were tested. Two of the Yb:S-FAP crystals showing crystal defects experienced bulk damage during Q-switched mode of operation. The remaining crystal had the lowest dopant concentration of all the crystals, limiting the stored energy. Up to 65 mJ of output was obtained in this high-quality crystal, the highest ever reported in Q-switched mode with this laser material. Conversion efficiency at this energy level was 11.8 percent. However, the maximum efficiency obtained was 16.3 percent before pump bleaching effects started to occur due to low dopant concentration in this crystal sample.

Pierce, Jeffrey W.; Mead, Roy D.

1997-03-01

221

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

PubMed

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

Gumeniuk, R; Schneich, 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

2015-03-10

222

Rare earth-copper-magnesium compounds RECu{sub 9}Mg{sub 2} (RE=Y, La-Nd, Sm-Ho, Yb) with ordered CeNi{sub 3}-type structure  

SciTech Connect

A series of ternary compounds RECu{sub 9}Mg{sub 2} (RE=Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Yb) have been synthesized via induction melting of elemental metal ingots followed by annealing at 400 deg. C for 4 weeks. Scanning electron microscopy (SEM) coupled with energy dispersive X-ray spectroscopy (EDXS) was used for examining microstructure and phase composition. These phases crystallize with an ordered version of the binary hexagonal structure type first reported for CeNi{sub 3}. The crystal structure was solved for TbCu{sub 9}Mg{sub 2} from single crystal X-ray counter data (TbCu{sub 9}Mg{sub 2}-structure type, P6{sub 3} /mmc-space group, hP24-Pearson symbol, a=0.49886 (7) nm, c=1.61646 (3) nm, R {sub F}=0.0474 for 190 unique reflections). The Rietveld refinement of the X-ray powder diffraction patterns of RECu{sub 9}Mg{sub 2} confirmed the same crystal structure for the reported rare earth metals. The unit cell volumes for RECu{sub 9}Mg{sub 2} smoothly follow the lanthanide contraction. The existence of a RECu{sub 9}Mg{sub 2} phase was excluded for RE=Er Tm under the investigated experimental conditions. - Graphical abstract: The perspective view of the arrangement of the icosahedrons and anti-cubooctahedrons in the structure of TbCu{sub 9}Mg{sub 2}.

Solokha, P. [Department of Inorganic Chemistry, Ivan Franko National University of Lviv, Kyryl and Mefodiy str. 6, 79005 Lviv (Ukraine)]. E-mail: solokha_pavlo@yahoo.com; Pavlyuk, V. [Department of Inorganic Chemistry, Ivan Franko National University of Lviv, Kyryl and Mefodiy str. 6, 79005 Lviv (Ukraine); Jan Dlugosz University of Czestochowa, Institute of Chemistry and Environmental Protection, al. Armii Krajowej 13/15, 42200, Czestochowa (Poland); Saccone, A. [Dipartimento di Chimica e Chimica Industriale, Sezione di Chimica Inorganica e Metallurgia, Universita di Genova, Via Dodecaneso 31, I-16146 Genova (Italy); De Negri, S. [Dipartimento di Chimica e Chimica Industriale, Sezione di Chimica Inorganica e Metallurgia, Universita di Genova, Via Dodecaneso 31, I-16146 Genova (Italy); Prochwicz, W. [Jan Dlugosz University of Czestochowa, Institute of Chemistry and Environmental Protection, al. Armii Krajowej 13/15, 42200, Czestochowa (Poland); Marciniak, B. [Jan Dlugosz University of Czestochowa, Institute of Chemistry and Environmental Protection, al. Armii Krajowej 13/15, 42200, Czestochowa (Poland); Rozycka-Sokolowska, E. [Jan Dlugosz University of Czestochowa, Institute of Chemistry and Environmental Protection, al. Armii Krajowej 13/15, 42200, Czestochowa (Poland)

2006-10-15

223

Study of encapsulated {sup 170}Tm sources for their potential use in brachytherapy  

SciTech Connect

Purpose: High dose-rate (HDR) brachytherapy is currently performed with {sup 192}Ir sources, and {sup 60}Co has returned recently into clinical use as a source for this kind of cancer treatment. Both radionuclides have mean photon energies high enough to require specific shielded treatment rooms. In recent years, {sup 169}Yb has been explored as an alternative for HDR-brachytherapy implants. Although it has mean photon energy lower than {sup 192}Ir, it still requires extensive shielding to deliver treatment. An alternative radionuclide for brachytherapy is {sup 170}Tm (Z=69) because it has three physical properties adequate for clinical practice: (a) 128.6 day half-life, (b) high specific activity, and (c) mean photon energy of 66.39 keV. The main drawback of this radionuclide is the low photon yield (six photons per 100 electrons emitted). The purpose of this work is to study the dosimetric characteristics of this radionuclide for potential use in HDR-brachytherapy. Methods: The authors have assumed a theoretical {sup 170}Tm cylindrical source encapsulated with stainless steel and typical dimensions taken from the currently available HDR {sup 192}Ir brachytherapy sources. The dose-rate distribution was calculated for this source using the GEANT4 Monte Carlo (MC) code considering both photon and electron {sup 170}Tm spectra. The AAPM TG-43 U1 brachytherapy dosimetry parameters were derived. To study general properties of {sup 170}Tm encapsulated sources, spherical sources encapsulated with stainless steel and platinum were also studied. Moreover, the influence of small variations in the active core and capsule dimensions on the dosimetric characteristics was assessed. Treatment times required for a {sup 170}Tm source were compared to those for {sup 192}Ir and {sup 169}Yb for the same contained activity. Results: Due to the energetic beta spectrum and the large electron yield, the bremsstrahlung contribution to the dose was of the same order of magnitude as from the emitted gammas and characteristic x rays. Moreover, the electron spectrum contribution to the dose was significant up to 4 mm from the source center compared to the photon contribution. The dose-rate constant {Lambda} of the cylindrical source was 1.23 cGy h{sup -1} U{sup -1}. The behavior of the radial dose function showed promise for applications in brachytherapy. Due to the electron spectrum, the anisotropy was large for r<6 mm. Variations in manufacturing tolerances did not significantly influence the final dosimetry data when expressed in cGy h{sup -1} U{sup -1}. For typical capsule dimensions, maximum reference dose rates of about 0.2, 10, and 2 Gy min{sup -1} would then be obtained for {sup 170}Tm, {sup 192}Ir, and {sup 169}Yb, respectively, resulting in treatment times greater than those for HDR {sup 192}Ir brachytherapy. Conclusions: The dosimetric characteristics of source designs exploiting the low photon energy of {sup 170}Tm were studied for potential application in HDR-brachytherapy. Dose-rate distributions were obtained for cylindrical and simplified spherical {sup 170}Tm source designs (stainless steel and platinum capsule materials) using MC calculations. Despite the high activity of {sup 170}Tm, calculated treatment times were much longer than for {sup 192}Ir.

Ballester, Facundo; Granero, Domingo; Perez-Calatayud, Jose; Venselaar, Jack L. M.; Rivard, Mark J. [Department of Atomic, Molecular and Nuclear Physics, University of Valencia, E-46100 Burjassot (Spain) and IFIC, CSIC, University of Valencia, E-46100 Burjassot (Spain); Department of Radiation Oncology, ERESA, Hospital General Universitario, E-46014 Valencia (Spain); Department of Radiation Oncology, La Fe University Hospital, E-46009 Valencia (Spain); Department of Medical Physics, Instituut Verbeeten, Tilburg 5000LA (Netherlands); Department of Radiation Oncology, Tufts University School of Medicine, Boston, Massachusetts 02111 (United States)

2010-04-15

224

Twist promotes tumor cell growth through YB-1 expression.  

PubMed

YB-1 controls gene expression through both transcriptional and translational mechanisms and is involved in various biological activities such as brain development, chemoresistance, and tumor progression. We have previously shown that YB-1 is overexpressed in cisplatin-resistant cells and is involved in resistance against DNA-damaging agents. Structural analysis of the YB-1 promoter reveals that several E-boxes may participate in the regulation of YB-1 expression. Here, we show that the E-box-binding transcription factor Twist is overexpressed in cisplatin-resistant cells and that YB-1 is a target gene of Twist. Silencing of either Twist or YB-1 expression induces G(1) phase cell cycle arrest of tumor cell growth. Significantly, reexpression of YB-1 led to increase colony formation when Twist expression was down-regulated by small interfering RNA. However, cotransfection of Twist expression plasmid could not increase colony formation when YB-1 expression was down-regulated. Collectively, these data suggest that YB-1 is a major downstream target of Twist. Both YB-1 and Twist expression could induce tumor progression, promoting cell growth and driving oncogenesis in various cancers. Thus, both YB-1 and Twist may represent promising molecular targets for cancer therapy. PMID:18172301

Shiota, Masaki; Izumi, Hiroto; Onitsuka, Takamitsu; Miyamoto, Naoya; Kashiwagi, Eiji; Kidani, Akihiko; Yokomizo, Akira; Naito, Seiji; Kohno, Kimitoshi

2008-01-01

225

From Biology to DiscoveryTM LipodinProTM  

E-print Network

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 approaches. Several technologies based on the use of peptide transduction domain (PTD) were developed

Lebendiker, Mario

226

Semiconducting properties of Tm doped Yb-ZnO films by spray pyrolysis  

NASA Astrophysics Data System (ADS)

In this work, we have investigated the structural, optical and electrical properties of rare earth co-doped zinc oxide thin films prepared by spray pyrolysis technique. X-ray diffraction has shown that the films are polycrystalline and textured with the c-axis of the wurtzite structure along the growth direction. Scanning electronic microscopy and transmission electronic microscopy were used to study the films composition and morphology. Photoluminescence measurements showed that all the films have a strong emission band at around 380 nm. Layers with electrical resistivity values as low as 5.7 10-2 ? cm were obtained.

Chaki, Imane; Belayachi, Azzam; El Bahraoui, Toufik; Regragui, Mohamed; Abd-Lefdil, Mohamed

2014-12-01

227

Stability, structural, and electronic properties of atomic chains on Yb/Ge(111)32 studied by STM and STS  

NASA Astrophysics Data System (ADS)

By means of scanning tunneling microscopy and spectroscopy (STM/STS), we have investigated the stability and the structure of atomic chains on Yb/Ge(111)32 . STM allows the identification of different building blocks of this reconstruction, depending on the bias polarity and voltage, and validates the honeycomb chain-channel (HCC) structure with the Ge?Ge double bond and metal coverage of 1/6 ML for Yb/Ge(111)32 , in agreement with the recent photoemission study [Kuzmin , Phys. Rev. B 75, 165305 (2007)]. The Yb atoms are found to be adsorbed on similar sites in the well-defined 2 rows. Locally, such rows are distorted, leading to the 4 periodicity, where the Yb atoms are adsorbed on two different sites that are well consistent with T4 and H3 sites. It is also assumed that Yb atoms can fluctuate rapidly between the neighboring T4 and H3 sites, leading to continuous rows observed together with the 2 rows in STM images. The stability of Ge honeycomb chain is controlled by the presence of Yb atom per two (31) surface units in average, which results in the donation of one electron from Yb to the surface per (31) unit. When this density is locally changed, the Ge honeycomb chain is found to be broken. The inner structure of the Ge honeycomb chain is visualized in STM and shows dimerized features without any apparent buckling. The STM observations also account for why the double periodicity is missing in the low-energy electron diffraction pattern from Yb/Ge(111)32 . The local electronic structure of this reconstruction, namely the Yb rows and Ge honeycomb chains, is studied by STS. The results support the HCC structure with the Ge?Ge double bond. It is believed that the present study elucidates the difference between the (32) reconstructions of Yb and Eu on Ge(111) and those of alkaline-earth and rare-earth metals on Si(111).

Kuzmin, M.; Laukkanen, P.; Perl, R. E.; Punkkinen, M. P. J.; Ahola-Tuomi, M.; Lng, J.; Vyrynen, I. J.

2010-04-01

228

Optical properties and laser performance of Yb-doped vanadates grown by floating zone method  

NASA Astrophysics Data System (ADS)

We grew high-quality Yb:LuVO4, Yb:GdVO4, and Yb:YVO4 by the floating zone (FZ) method. It was found by measurement that these crystals had favorable optical properties. A maximum absorption coefficient of 27 cm-1 (FWHM) and a fluorescence bandwidth with a 20 nm (FWHM) were observed for Yb:LuVO4 at a Yb doping level of 4 at. %. Finally, we demonstrated the lasing performances of Yb:LuVO4, Yb:GdVO4, and Yb:YVO4. To our knowledge, this is the first time that a Yb-doped vanadate grown by the FZ method has been used as a laser, and 4 at.% Yb doping of the Yb:LuVO4 and Yb:YVO4 is the highest level of doping at which laser oscillation occurs among the Yb-doped vanadates.

Nakamura, Shinki; Agata, Taishi; Ogawa, Takayo; Wada, Satoshi; Higuchi, Mikio

2013-09-01

229

Listening and Legos[TM  

ERIC Educational Resources Information Center

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?

Morris, Pamela

2012-01-01

230

The new binary intermetallic YbGe 2.83  

NASA Astrophysics Data System (ADS)

The new compound YbGe 2.83 was obtained from the reaction of Yb and Ge in liquid indium. The crystal structure of YbGe 2.83 adopts the trigonal, P3 m1 space group with a= b=8.3657(12) and c=7.0469(14) . The structure of YbGe 2.83 is a variant of the CaAl 2Si 2 structure type with ordered vacancies. Germanium atoms form double layers of puckered hexagons creating slabs that sandwich the Yb atoms. YbGe 2.83 can be classified as a Zintl compound with the formula Yb (2+ x)+ (Ge 2.83) (2+ x)- . The deficiencies at the Ge sites cause a mixed/intermediate valent state of ytterbium (Yb 2.35+). Valence bond sum calculations suggest an average valence of Yb ions in YbGe 2.83 of 2.51 consistent with an intermediate valence compound.

Peter Sebastian, C.; Kanatzidis, Mercouri G.

2010-09-01

231

Standardization of 152Eu.  

PubMed

152Eu was standardized within the frame of a BIPM international comparison. The solution was prepared and bottled by PTB. The ampoules were measured at BIPM in the SIR ionization chambers and then dispatched to the participating laboratories. In the Radionuclide Metrology Laboratory of IFIN-HH, the solution was standardized using a coincidence method with "beta-efficiency extrapolation" by foil absorption. A simple 4pi beta-gamma-coincidence system was used, with NaI(Tl) and 4piPC detectors. No significant impurities were found apart for 0.5% 154Eu. To obtain linear extrapolation plots, a "gamma-window" of 180-1500 keV was chosen. Dead-times of 10 micros were used. A combined uncertainty of 0.24% was obtained, mainly from the extrapolation procedure component. PMID:11839052

Grigorescu, E L; Razdolescu, Anamaria Cristina; Sahagia, Maria; Luca, A; Ivan, C; Tanase, G

2002-01-01

232

Nd3+, Yb3+ and Nd3+/Yb3+: doped borosilicate glasses for luminescent thermometry  

NASA Astrophysics Data System (ADS)

The article presents influence of temperature on luminescent properties of borosilicate glasses with molar composition: SiO2-B2O3-Al2O3-Na2O-K2O doped with Nd3+, Yb3+ and co-doped with Nd3+/Yb3+ ions. In the range from 60 to 300C the quenching of luminescence signal versus increase of temperature was observed. In case of glasses doped with Nd3+ and Yb3+ ions the sensitivity was determinated to be 0.0016 [1/K] at 1.06?m and 0.001 [1/K] at 1.02?m, respectively. Fabricated glass co-doped with Nd3+/Yb3+ ions is characterized by the highest sensitivity and maximum value 0.003 [1/K] was observed at the wavelength of 1020nm, corresponding to the Yb3+: 2F5/2 --> 2F7/2 transition in energy levels structure of ions.

Bykowski, Kamil; Bruszewski, Artur; Cimaszewski, Dominik; Zmojda, Jacek; Kochanowicz, Marcin; Dorosz, Dominik

2014-11-01

233

RbYb(PO3)4  

PubMed Central

Rubidium ytterbium(III) tetrakis(polyphosphate), RbYb(PO3)4, was synthesized by solid-state reaction. It adopts structure type IV of the MRE(PO3)4 (M = alkali metal and RE = rare earth metal) family of compounds. The structure is composed of a three-dimensional framework made up from double spiral polyphosphate chains parallel to [10-1] and irregular [YbO8] polyhedra. There are eight PO4 tetrahedra in the repeat unit of the polyphosphate chains. The Rb+ cation is located in channels extending along [100] that are delimited by the three-dimensional framework. It is surrounded by 11 O atoms, defining an irregular polyhedron. PMID:23476312

Zhu, Jing; Chen, Hui

2013-01-01

234

Ceramic Yb:YAG microchip laser  

NASA Astrophysics Data System (ADS)

An efficient microchip laser utilizing domestically fabricated ceramic Yb:YAG is presented. In continuous-wave (cw) and Q-switched operation, the laser maintains linear polarization with 22 dB extinction and oscillates in the fundamental TEM 00 mode. In cw mode, the ceramic laser has an output power of 2.25 W and a slope efficiency of 66%. When passively Q-switched at 11.4 kHz repetition rate using Cr:YAG, the 1.9 ns pulse has an average power of 0.72 W and a slope efficiency of 46%. To our knowledge, this is currently the highest reported power from a ceramic Yb:YAG laser. The laser performance of the 5-at.% ceramic is compared to a 10-at.% single crystal, and we discuss how the scattering loss and storage efficiency of the ceramic medium affect its laser characteristics.

Ostby, Eric P.; Ackerman, Richard A.; Huie, Jean C.; Gentilman, Richard L.

2006-02-01

235

Scaling of Yb-Fiber Frequency Combs  

NASA Astrophysics Data System (ADS)

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).

Ruehl, Axel; Marcinkevicius, Andrius; Fermann, Martin E.; Hartl, Ingmar

2010-06-01

236

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

SciTech Connect

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{sub 3}F{sub 4}S{sub 2} instead. With Eu{sub 3}F{sub 4}S{sub 2} another isotypic representative has now been synthesized. Eu{sub 3}F{sub 4}S{sub 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 deg. 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{sub 2}-type EuF{sub 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{sup 2+}) is coordinated by eight fluoride anions in a cubic fashion, the other one (Eu{sup 3+}) exhibits a monocapped square antiprismatic coordination sphere with four F{sup -} and five S{sup 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{sub 3}F{sub 4}S{sub 2} show Curie-Weiss behavior with an experimental magnetic moment of 8.19(5) mu{sub 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{sup II})(Eu{sup III}){sub 2}F{sub 4}S{sub 2} only one third of the europium centers in Eu{sub 3}F{sub 4}S{sub 2} carry permanent magnetic moments. {sup 151}Eu-Moessbauer 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{sup 2+} and Eu{sup 3+}, respectively. The spectra at 78 and 298 K are similar, thus no change in the Eu{sup 2+}/Eu{sup 3+} fraction can be detected. - Graphical abstract: Crystal structure and {sup 151}Eu-Moessbauer spectra of mixed-valent Eu{sub 3}F{sub 4}S{sub 2}.

Grossholz, Hagen; Hartenbach, Ingo [Institut fuer Anorganische Chemie, Universitaet Stuttgart, Pfaffenwaldring 55, 70569 Stuttgart (Germany); Kotzyba, Gunter [Institut fuer Anorganische und Analytische Chemie, Westfaelische Wilhelms-Universitaet Muenster, Corrensstrasse 30, 48149 Muenster (Germany); Poettgen, Rainer, E-mail: pottgen@uni-muenster.d [Institut fuer Anorganische und Analytische Chemie, Westfaelische Wilhelms-Universitaet Muenster, Corrensstrasse 30, 48149 Muenster (Germany); Trill, Henning; Mosel, Bernd D. [Institut fuer Physikalische Chemie, Westfaelische Wilhelms-Universitaet Muenster, Corrensstrasse 30, 48149 Muenster (Germany); Schleid, Thomas, E-mail: schleid@iac.uni-stuttgart.d [Institut fuer Anorganische Chemie, Universitaet Stuttgart, Pfaffenwaldring 55, 70569 Stuttgart (Germany)

2009-11-15

237

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

PubMed

The new intermetallic compound Yb7Ni4InGe12 was obtained as large silver needle shaped single crystals from reactive indium flux. Single crystal X-ray diffraction suggests that Yb7Ni4InGe12 crystallizes in the Yb7Co4InGe12 structure type, and tetragonal space group P4/m and lattice constants are a = b = 10.291(2) and c = 4.1460(8) . The crystal structure of Yb7Ni4InGe12 consists of columnar units of three different types of channels filled with the Yb atoms. The crystal structure of Yb7Ni4InGe12 is closely related to Yb5Ni4Ge10. The effective magnetic moment obtained from the magnetic susceptibility measurements in the temperature range 200-300 K is 3.66?B/Yb suggests mixed/intermediate valence behavior of ytterbium atoms. X-ray absorption near edge spectroscopy (XANES) confirms that Yb7Ni4InGe12 exhibits mixed valence. PMID:25714934

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

2015-03-10

238

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

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) , b=15.925(3) , c=7.3008(12) ), 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) , b=4.127(1)/4.445(4) , c=11.552(4)/12.311(1) 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 5300 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.

Wang, Jian [State Key Laboratory of Crystal Materials, Institute of Crystal Materials, Shandong University, Jinan, Shandong 250100 (China); Xia, Sheng-Qing, E-mail: shqxia@sdu.edu.cn [State Key Laboratory of Crystal Materials, Institute of Crystal Materials, Shandong University, Jinan, Shandong 250100 (China); Tao, Xu-Tang [State Key Laboratory of Crystal Materials, Institute of Crystal Materials, Shandong University, Jinan, Shandong 250100 (China); Schfer, Marion C. [Department of Chemistry and Biochemistry, University of Delaware, Newark, DE 19716 (United States); Bobev, Svilen, E-mail: bobev@udel.edu [Department of Chemistry and Biochemistry, University of Delaware, Newark, DE 19716 (United States)

2013-09-15

239

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

SciTech Connect

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.

Myers, Kenneth D.

1999-11-08

240

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

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.

Xu, Zhenhe, E-mail: xuzh056@163.com [College of Applied Chemistry, Shenyang University of Chemical Technology, Shenyang 100142 (China)] [College of Applied Chemistry, Shenyang University of Chemical Technology, Shenyang 100142 (China); Feng, Bin [China National Aviation Fuel Group Corporation, Planning and Development Department, Beijing 100088 (China)] [China National Aviation Fuel Group Corporation, Planning and Development Department, Beijing 100088 (China); Bian, Shasha; Liu, Tao; Wang, Mingli; Gao, Yu; Sun, Di; Gao, Xin [College of Applied Chemistry, Shenyang University of Chemical Technology, Shenyang 100142 (China)] [College of Applied Chemistry, Shenyang University of Chemical Technology, Shenyang 100142 (China); Sun, Yaguang, E-mail: yaguangsun@yahoo.com.cn [College of Applied Chemistry, Shenyang University of Chemical Technology, Shenyang 100142 (China)] [College of Applied Chemistry, Shenyang University of Chemical Technology, Shenyang 100142 (China)

2012-12-15

241

LiquichekTM Tumor Marker Control  

E-print Network

LiquichekTM Tumor Marker Control Bio-Rad Laboratories T U M O R M A R K E R C O N T R O L S #12;T U M O R M A R K E R C O N T R O L S LiquichekTM Tumor Marker Control LiquichekTM Tumor Marker Control is a liquid, human serum based, third party control for monitoring the precision of tumor marker testing

Rodriguez, Carlos

242

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

DOEpatents

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.

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

1986-03-06

243

Upconversion properties of Tb3+-Yb3+ codoped fluorophosphate glasses  

NASA Astrophysics Data System (ADS)

Tb3+-Yb3+ codoped fluorophosphate glasses were synthesized and properties of the visible emission at 0.54 ?m were investigated. The upconversion excitation efficiency from Yb3+ to Tb3+ was studied by evaluation of the cooperative energy transfer efficiency from Yb3+ to Tb3+ (?CET) and the back-transfer efficiency from Tb3+ to Yb3+(?BT), which gave a positive and negative contribution to upconversion excitation, respectively. The ?CET was as high as 30% and the ?BT was less than 1% in the fluorophosphate glass. This indicates that Tb3+-Yb3+ codoped fluorophosphate glass is promising as laser and gain medium in the 0.54 ?m band.

Arai, Yusuke; Yamashidta, Tatsuya; Suzuki, Takenobu; Ohishi, Yasutake

2009-04-01

244

Stereocorrelation of Landsat TM images  

NASA Technical Reports Server (NTRS)

A digital elevation model (DEM) developed from Landsat TM images of a rugged terrain area in north Georgia by automated stereocorrelation techniques yielded an rms error (z), RMSE(z), value of + or - 42 m. Based on the B/H ratio of 0.18 for the Landsat data, this Z-error corresponds to a planimetric correlation accuracy of about + or - 0.3 pixels, confirming that precise correlation can be achieved with operational satellite data. Contours at a 100-m interval interpolated from the DEM show a deviation of + or - 33 m from reference contours obtained from existing 1:24,000-scale maps. The 28.5-m pixel resolution and the weak B/H ratio impose limitations on the accuracy that can be achieved with Landsat TM data. However, it is anticipated that RMSE(z) values of + or - 10 m or less can be achieved with SPOT-1 panchromatic stereo images of 10-m resolution recorded at B/H ratios of 0.5 to 1.0. DEMs generated by stereocorrelation techniques can be used to create orthoimages, perspective views, and topographic map products.

Ehlers, Manfred; Welch, R.

1987-01-01

245

Energy transfer properties of Nd3+?Yb3+ in Nd:Yb:LiNbO3 crystals  

NASA Astrophysics Data System (ADS)

Nd:Yb:LiNbO3 nonlinear laser crystal is a candidate for NIR laser around 1000 nm and self-frequency-doubling laser around 500 nm, with mature pump technique using ~808-nm diode laser, via Nd3+ absorption and efficient Nd3+?Yb3+ energy transfer. High-quality Nd:Yb:LiNbO3 crystals were grown by Czochralski method, and the main spectroscopic properties of Nd3+?Yb3+ (Nd3+:4F3/2+Yb3+:2F7/2?Nd3+:4I9/2+Yb3+:2F5/2) energy transfer in LiNbO3 crystals were studied systemically based on emission spectra and luminescence decay curves. Energy transfer efficiency as high as 86% was obtained in a Nd3+ (0.8 mol%) and Yb3+ (2.0 mol%) codoped sample, so Nd:Yb:LiNbO3 laser with a higher efficiency than that of Nd:LiNbO3 laser might be achieved under identical pump conditions.

Sun, Ting; Li, Ai-Hua; Xu, Chao; Xu, Yu-Heng; Wang, Rui

2014-03-01

246

Effect of Yb3+ Concentrations on the Upconversion Luminescence Properties of ZrO2:Er3+,Yb3+ Phosphors  

NASA Astrophysics Data System (ADS)

ZrO2:Er3+ and ZrO2:Er3+,Yb3+ phosphors were synthesized via a solvothermal reaction method. For low concentrations of Yb3+, the crystalline structure changed from the tetragonal to monoclinic phase as sintering temperature increased. As the Yb3+ concentration increased to a value above 0.05 mol, ZrO2 phosphors displayed a very stable tetragonal phase. The green and red upconversion emissions of ZrO2:Er3+,Yb3+ phosphors were measured under the excitation with a 975 nm continuous wave diode laser, and the pump power dependence of upconversion intensity was investigated. As the Yb3+ concentration increased from 0 to 0.05 mol, the red upconversion emission intensity increased more rapidly than the green emission intensity. This is attributed to the energy transfer (4I11/2?4I15/24I13/2?4F9/2) between Er3+ ions and the energy back transfer [4S3/24I13/2(Er3+)?2F7/22F5/2(Yb3+)] between the Er3+ and Yb3+ ions. In this case, the pump power dependence of red emission intensity changed from quadratic to linear as Yb3+ concentration increased.

Noh, Hyeon Mi; Yang, Hyun Kyoung; Moon, Byung Kee; Choi, Byung Chun; Jeong, Jung Hyun; Choi, Haeyoung; Kim, Jung Hwan

2013-01-01

247

Spectroscopic properties of Eu3+, Dy3+ and Tb3+ ions in lead silicate glasses obtained by the conventional high-temperature melt-quenching technique  

NASA Astrophysics Data System (ADS)

The luminescence properties of selected rare-earth ions in lead silicate glasses have been studied. Europium, dysprosium and terbium ions were chosen as active dopants. Based on excitation and emission measurements as well as luminescence decay analysis, some spectroscopic parameters for these lanthanide ions were determined. In particular, the intensity ratios R/O (Eu3+), Y/B (Dy3+) and G/B (Tb3+) were calculated. Luminescence lifetimes for the 5D0 state of Eu3+ ions, the 4F9/2 state of Dy3+ ions and the 5D4 state of Tb3+ ions were also determined.

?ur, L.; Janek, J.; So?tys, M.; Pisarska, J.; Pisarski, W. A.

2013-11-01

248

Yb-, Er-Yb-, and Nd-doped fibre lasers based on multi-element first cladding fibres  

SciTech Connect

Single-mode cw Yb-, Er-Yb, and Nd-doped fibre lasers are fabricated by using fibres of a complicated structure (a few silica fibres in optical contact with each other are surrounded by a polymer jacket). Such a structure allows the coupling of radiation from several pump sources into one active fibre, providing an increase in the output power of the fibre laser. The Yb-doped fibre lasers with the output power above 50 W and efficiency {approx}65% and the 1.608-{mu}m Er-Yb-doped fibre laser pumped to the absorption band of Yb are fabricated and studied. The Nd-doped fibre lasers based on such fibres and emitting at 0.92 and 1.06 {mu}m are manufactured for the first time. (lasers)

Bufetov, Igor' A; Bubnov, M M; Mel'kumov, Mikhail A; Dudin, V V; Shubin, Aleksei V; Semenov, S L; Kravtsov, K S; Dianov, Evgenii M [Fiber Optics Research Center, Russian Academy of Sciences, Moscow (Russian Federation); Gur'yanov, A N; Yashkov, M V [Institute of Chemistry of High-Purity Substances, Russian Academy of Sciences, Nizhnii Novgorod (Russian Federation)

2005-04-30

249

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

PubMed

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

Subhan, Md Abdus; Nakata, Hiroyasu

2014-09-15

250

A Review of "Integrity[TM]"  

ERIC Educational Resources Information Center

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.

Veldkamp, Bernard P.

2008-01-01

251

YB-1 overexpression promotes a TGF-?1-induced epithelial-mesenchymal transition via Akt activation.  

PubMed

The Y-box binding protein-1 (YB-1) is a transcription/translation regulatory protein, and the expression thereof is associated with cancer aggressiveness. In the present study, we explored the regulatory effects of YB-1 during the transforming growth factor-?1 (TGF-?1)-induced epithelial-to-mesenchymal transition (EMT) in lung adenocarcinoma cells. Downregulation of YB-1 increased E-cadherin promoter activity, and upregulation of YB-1 decreased promoter activity, suggesting that the YB-1 level may be correlated with the EMT. TGF-?1 induced YB-1 expression, and TGF-?1 translocated cytosolic YB-1 into the nucleus. YB-1 overexpression promoted TGF-?1-induced downregulation of epithelial markers, upregulation of mesenchymal markers, and cell migration. Moreover, YB-1 overexpression enhanced the expression of E-cadherin transcriptional repressors via TGF-?1-induced Akt activation. Our findings afford new insights into the role played by YB-1 in the TGF-?1 signaling pathway. PMID:25645014

Ha, Bin; Lee, Eun Byul; Cui, Jun; Kim, Yosup; Jang, Ho Hee

2015-03-01

252

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

Microsoft Academic Search

Upon ultraviolet (UV) light excitation, an intense near-infrared (NIR) emission of Yb3+ (2F5\\/2-->2F7\\/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

Xiantao Wei; Shan Huang; Yonghu Chen; Changxin Guo; Min Yin; Wu Xu

2010-01-01

253

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

PubMed

The superbulky deca-aryleuropocene [Eu(Cp(BIG))2], Cp(BIG) = (4-nBu-C6H4)5-cyclopentadienyl, was prepared by reaction of [Eu(dmat)2(thf)2], DMAT = 2-Me2N-?-Me3Si-benzyl, with two equivalents of Cp(BIG)H. Recrystallizyation from cold hexane gave the product with a surprisingly bright and efficient orange emission (45% quantum yield). The crystal structure is isomorphic to those of [M(Cp(BIG))2] (M = Sm, Yb, Ca, Ba) and shows the typical distortions that arise from Cp(BIG)???Cp(BIG) attraction as well as excessively large displacement parameter for the heavy Eu atom (U(eq) = 0.075). In order to gain information on the true oxidation state of the central metal in superbulky metallocenes [M(Cp(BIG))2] (M = Sm, Eu, Yb), several physical analyses have been applied. Temperature-dependent magnetic susceptibility data of [Yb(Cp(BIG))2] show diamagnetism, indicating stable divalent ytterbium. Temperature-dependent (151)Eu Mssbauer effect spectroscopic examination of [Eu(Cp(BIG))2] was examined over the temperature range 93-215?K and the hyperfine and dynamical properties of the Eu(II) species are discussed in detail. The mean square amplitude of vibration of the Eu atom as a function of temperature was determined and compared to the value extracted from the single-crystal X-ray data at 203?K. The large difference in these two values was ascribed to the presence of static disorder and/or the presence of low-frequency torsional and librational modes in [Eu(Cp(BIG))2]. X-ray absorbance near edge spectroscopy (XANES) showed that all three [Ln(Cp(BIG))2] (Ln = Sm, Eu, Yb) compounds are divalent. The XANES white-line spectra are at 8.3, 7.3, and 7.8?eV, for Sm, Eu, and Yb, respectively, lower than the Ln2O3 standards. No XANES temperature dependence was found from room temperature to 100?K. XANES also showed that the [Ln(Cp(BIG))2] complexes had less trivalent impurity than a [EuI2(thf)x] standard. The complex [Eu(Cp(BIG))2] shows already at room temperature strong orange photoluminescence (quantum yield: 45?%): excitation at 412?nm (24,270?cm(-1)) gives a symmetrical single band in the emission spectrum at 606?nm (?max =16495?cm(-1), FWHM: 2090?cm(-1), Stokes-shift: 2140?cm(-1)), which is assigned to a 4f(6)5d(1) ? 4f(7) transition of Eu(II). These remarkable values compare well to those for Eu(II)-doped ionic host lattices and are likely caused by the rigidity of the [Eu(Cp(BIG))2] complex. Sharp emission signals, typical for Eu(III), are not visible. PMID:23907896

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

2013-09-01

254

ESA + EU: Ideology or pragmatic task sharing?  

Microsoft Academic Search

This paper analyses the different positions in the debate about the institutional integration of ESA and the EU. In particular it considers previous articles published in Space Policy on both sides of the argument, i.e. ESA incorporation into the EU or EU membership in ESA. ESA becoming the space agency of the EU seems to be the compromise position. The

Thomas Hoerber

2009-01-01

255

Serviceleinrichtungen Aueninstitut EU Forschungsmanagement Unit  

E-print Network

and international research institutions Contact:Contact:Contact:Contact: Head of Unit DI Siegfried HUEMER EU funding Information Administrator siegfried.huemer@tuwien.ac.at tel. 41553; Mon - Fri 08.30 - 16.30 h Adviser Mag

Fuchs, Clemens

256

Magnetic and transport properties of the narrow-gap semiconductor Yb5Si4  

NASA Astrophysics Data System (ADS)

We report the synthesis and basic properties of the binary compound Yb5Si4. In this compound, Yb ions occupy three different crystallographic sites, the multiplicity of which is represented by Yb1 : Yb2 : Yb3 = 1:2:2. The estimated effective magnetic moment and magnetic entropy can be explained by the proportion of Yb valence states, Yb3+ : Yb2+ = 2:3. This result suggests the possibility that Yb3+ ions occupy either Yb2 or Yb3 site. Yb5Si4 undergoes an antiferromagnetic transition at TN = 1.7 K. The extended high temperature tail in the temperature dependence of the specific heat just above TN has been observed. Yb5Si4 also exhibits the broad maximum peak around 2.3 K in the magnetic susceptibility, corresponding to the specific heat anomaly. We propose that these anomalies are possible to originate from magnetic fluctuations caused by low-dimensional Yb3+ networks. Electrical resistivity measurements on Yb5Si4 reveal semiconducting behavior at all temperatures. The small energy gap ? = 430 K has been obtained at room temperature estimated by the thermal activation model. The energy gap gradually decreases with decreasing temperature, and reaches about 3 K at low temperatures.

Kosaka, Masashi; Ottomo, Shingo; Machida, Ayumi; Kirigane, Tomoyuki; Numakura, Ryosuke; Katano, Susumu; Michimura, Shinji

2015-03-01

257

Er and Yb isotope fractionation in planetary materials  

NASA Astrophysics Data System (ADS)

Terrestrial planets are depleted in volatile elements relative to solar abundances. Little is known, however, about volatility at the high temperatures relevant to asteroidal collisions and to the giant lunar impact. Although refractory rare-earth elements have overall similar crystallochemical properties, some differ in their temperatures of condensation from the nebular gas. This is the case for Yb, which condenses at 1490K and in the vapor is mostly in elemental form. By contrast, Er, largely present as ErO, condenses at 1660K. We analyzed the Er and Yb isotopic compositions in 33 terrestrial basalts, garnets, different classes of chondrites and achondrites, and lunar samples by MC-ICP-MS. The range of mass-dependent isotope fractionation is larger for Yb (0.43 per amu) than Er (0.23) isotopes. For terrestrial rocks, a positive correlation between ?Yb and La/Yb suggests that the isotopic differences between Er and Yb can be accounted for by the presence of small fractions of Yb2+. Yb is isotopically heavy in kimberlite and light in garnets. Ytterbium behaves similarly to Fe, with Yb3+ being more incompatible than the much less abundant Yb2+. In addition, the coexistence of divalent and trivalent sites in the garnet structure and the preference of heavy isotopes for stable bonds makes Yb in garnet isotopically light. The deficit of heavy Yb isotopes in lunar basaltic samples relative to the Earth, chondrites, and eucrites provides new evidence that the Moon formed by the condensation of silicate vapor in the aftermath of the giant lunar impact. Separation of vapor from melt and of heavy from light isotopes is first expected during the adiabatic expansion of the initial vapor plume. Subsequently, friction between melt and gas tends to further enrich the Moon feeding zone in silicate vapor to compensate the inward migration of melt out of the pre-lunar disk. A major consequence of interpreting the present lunar data by vapor/melt segregation is that the relative abundances of refractory elements in the Moon are unlikely to be chondrite-like or even Earth-like. Erbium isotope ratios in lunar samples reflect the capture of neutrons produced by galactic cosmic rays. The first resonance of 167Er for neutron capture will help cover an energy range poorly covered by other nuclides.

Albalat, Emmanuelle; Telouk, Philippe; Albarde, Francis

2012-11-01

258

Optimization of Yb-Er microchip laser parameters  

NASA Astrophysics Data System (ADS)

Output parameters of microchip lasers based on Yb:Er co-doped phosphate glasses have been numerically calculated using a simplified 4-level model in order to optimize the Yb and Er concentrations and active medium length. It was shown that active media with Yb concentration ~21027 m-3 and length of the order of 1 mm were most appropriate to obtain the practically maximum slope efficiency and minimum threshold power. Simulation results indicated that the Er concentration could be much lower than those currently used in practice. The obtained results were in good agreement with available experimental data.

Burov, L. I.; Krylova, L. G.

2012-07-01

259

YbN: An intrinsic semiconductor with antiferromagnetic exchange  

NASA Astrophysics Data System (ADS)

We present a study of the structural, conducting, magnetic, and optical properties of YbN thin films. Magnetic measurements reveal an antiferromagnetic Curie-Weiss temperature dependence. We find the temperature-dependent resistivity and carrier concentration to be indicative of YbN being semiconducting in nature. Along with this we observe an absorption onset at 1.5 eV, found from optical transmission and reflection measurements. This apparent combination of antiferromagnetism and semiconductivity present in YbN makes it unique among the rare earth nitrides, a series dominated by ferromagnetic semiconductors.

Warring, H.; Ruck, B. J.; McNulty, J. F.; Anton, E.-M.; Granville, S.; Koo, A.; Cowie, B.; Trodahl, H. J.

2014-12-01

260

Monodisperse core-shell structured up-conversion Yb(OH)CO?@YbPO?:Er+ hollow spheres as drug carriers.  

PubMed

In this work, we report a facile solution-phase synthesis of monodisperse core-shell structured Yb(OH)CO?@YbPO? hollow spheres (size around 380 nm) by utilizing the colloidal sphere of Yb(OH)CO? as the sacrificial template via the Kirkendall effect. The Er+ doped Yb(OH)CO?@YbPO? core-shell hollow spheres can be prepared similarly, which exhibit strong green emission under 980 nm NIR laser excitation even after loading with drug molecules. Most importantly, the sample can be used as an effective drug delivery carrier. The biocompatibility test on L929 fibroblast cells using MTT assay reveals low cytotoxicity of the system. A typical anticancer drug, doxorubicin hydrochloride (DOX), is used for drug loading, and the release properties, cytotoxicity, uptake behavior and therapeutic effects were examined. It is found that DOX is shuttled into cell by core-shell hollow spheres carrier and released inside cells after endocytosis, and the DOX-loaded spheres exhibited greater cytotoxicity than free DOX. These results indicate that the core-shell Er+ doped Yb(OH)CO?@YbPO? hollow spheres have potential for drug loading and delivery into cancer cells to induce cell death. PMID:21435712

Xu, Zhenhe; Ma, Ping'an; Li, Chunxia; Hou, Zhiyao; Zhai, Xuefeng; Huang, Shanshan; Lin, Jun

2011-06-01

261

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

PubMed Central

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

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

2013-01-01

262

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

PubMed

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

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

2013-03-21

263

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

NASA Astrophysics Data System (ADS)

We studied the magnetic properties of single-crystal Yb2V2O7 using dc and ac susceptibility measurements, elastic and inelastic neutron-scattering measurements, and linear spin-wave theory. The experimental data show a ferromagnetic ordering of V4 + ions at 70 K, a short-range ordering of Yb3 + ions below 40 K, and finally a long-range noncollinear 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 increase the Yb ordering temperature to 15 K, the intra-sublattice Yb-Yb interactions, based on the pyrochlore lattice, still stabilize the Yb ions' noncollinear spin structure and spin flop transition.

Dun, Z. L.; Ma, J.; Cao, H. B.; Qiu, Y.; Copley, J. R. D.; Hong, T.; Matsuda, M.; Cheng, J. G.; Lee, M.; Choi, E. S.; Johnston, S.; Zhou, H. D.

2015-02-01

264

Quasiparticle alignment effects in rotational bands of sup 159 Yb  

Microsoft Academic Search

High-spin states in the transitional nucleus ¹⁵⁹Yb were measured by means of heavy-ion induced reactions. The three reactions used were ¹¹⁶Cd(⁴⁸Ti,5n)¹⁵⁹Yb at 220 MeV, ⁹⁸Mo(⁶⁴Ni,3n)¹⁵⁹Yb at 265 MeV, and ¹⁴⁷Sm(¹⁶O,4n)¹⁵⁹Yb at 90 MeV. The first two measurements were performed at the Holifield Heavy Ion Research Facility at Oak Ridge National Laboratory, using the Spin Spectrometer multi-detector array. The third reaction

1988-01-01

265

Harmonics generation from rod-type Yb doped fiber laser  

Microsoft Academic Search

We presents a compact diode pumped, Q-switched Yb doped rod-type fiber laser producing near diffraction limited frequency doubled and tripled beams with a conversion efficiency of respectively 62% and 38%.

R. Bello-Doua; F. Salin; E. Freysz

2008-01-01

266

EDGE-PUMP HIGH POWER MICROCHIP Yb:YAG LASER  

Microsoft Academic Search

This paper presents new concepts for pumping very thin active laser media at pump level of hundreds of watts, output performances obtained from Yb-based microchip laser. Continuous-wave (cw) laser operation at 1.03 ?m with slope efficiency of 0.40 in Yb:YAG and low thermal lens was realized using an edge-pump configuration and a laser diode emitting at 0.94 ?m. Over 90

TRAIAN DASCALU

2008-01-01

267

[Direct upconversion sensitization luminescence comparison of the ErYb co-doped oxyfluoride fluoride pentaphosphate glass].  

PubMed

This paper investigates the direct upconversion sensitization luminescence of the ErYb co-doped oxyfluoride glass (ErYb: FOG), fluoride glass (ErYb: ZBLAN) and pentaphosphate noncrystalline (ErYb: PP) excited by a 966 nm diode laser. The splendid upconversion luminescence phenomenon is found. It is resulted from that the Yb3+ concentration in rather high, the energy transfer among Er(3+)-Yb3+ and Yb(3+)-Yb3+ ions is rather strong. An important fact is found that the direct upconversion sensitization luminescence of ErYb: FOG is about 100-100,000 times greater than that of ErYb: PP. And meanwhile it is interesting that the upconversion luminescence intensity of ErYb: FOG is near to that of ErYb: ZBLAN. It is significant to enhance the comprehensive level of up-conversion luminescence. PMID:12939953

Chen, Xiao-bo; Chen, Luan; Zhao, Chen-yi; Sawanobori, N; Ma, Hui; Song, Zeng-fu

2003-02-01

268

Determination of the 151Eu(n,?)152Eu and 153Eu(n,?)154Eu Reaction Cross Sections at Thermal Neutron Energy  

NASA Astrophysics Data System (ADS)

We have measured partial ?-ray cross sections following neutron capture in enriched 151Eu and 153Eu targets at the cold-neutron-beam facility of the Budapest Research Reactor. The cross sections were standardized using a stoichiometric natEuCl3 target with the well-known 1951-keV ?-ray cross section from the 35Cl(n,?)36Cl reaction at the cold-neutron-beam facility of the Garching Research Reactor. The ?-ray cross sections were corrected for effective g-factors. These data were combined with the structural information of 152Eu and 154Eu given in the Evaluated Nuclear Structure Data File to produce capture ?-ray level schemes. The total radiative capture cross sections of the 151Eu(n,?)152Eu and 153Eu(n,?)154Eu reactions were determined by summing the experimental transition intensities from known levels with simulated intensities of transitions from higher excitations to the ground- or metastable-state. The individual 151Eu(n,?)152Eu and 151Eu(n,?)152gEu reaction cross sections disagree with values in the literature. However, the total cross section of the 151Eu(n,?)152Eu reaction does agree with those values. Also, our deduced cross section for the 153Eu(n,?)154Eu reaction closely follows the data in the literature. These results are supported by an earlier standardization experiment done at the Budapest Research Reactor using a target of Eu2O3 solution in H2SO4.

Basunia, M. S.; Firestone, R. B.; Rvay, Zs.; Choi, H. D.; Belgya, T.; Escher, J. E.; Hurst, A. M.; Krti?ka, M.; Szentmiklsi, L.; Sleaford, B.; Summers, N. C.

2014-05-01

269

Digital HREM imaging of yttrium atoms in YB{sub 56} with YB{sub 66} structure  

SciTech Connect

The arrangement of yttrium atoms in YB{sub 56} with YB{sub 66} structure was determined by high-resolution electron microscopy (HREM) using a slow-scan CCD camera. Digital HREM images recorded along the [100], [110], and [111] directions of the YB{sub 56} crystals showed averaged yttrium atom positions in the boron clusters, which were also confirmed by image simulation. Digital HREM images recorded from thin regions (<5 nm) directly showed the local yttrium atom arrangements in the YB{sub 56}. In particular, the Y-hole, which consists of a single yttrium vacancy and a single yttrium atom, was detected in the boron clusters. The calculated images based on the proposed local structure model for yttrium atom arrangements agreed well with the observed images.

Oku, Takeo; Carlsson, A.; Wallenberg, L.R.; Malm, J.O.; Bovin, J.O. [Lund Univ. (Sweden)] [Lund Univ. (Sweden); Higashi, Iwami [Riken, Wako, Saitama (Japan). Inst. of Physical and Chemical Research] [Riken, Wako, Saitama (Japan). Inst. of Physical and Chemical Research; Tanaka, Takaho; Ishizawa, Yoshio [National Inst. for Research in Inorganic Materials, Tsukuba, Ibaraki (Japan)] [National Inst. for Research in Inorganic Materials, Tsukuba, Ibaraki (Japan)

1998-02-01

270

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

NASA Astrophysics Data System (ADS)

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

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

2014-02-01

271

Growth of Yb: S-FAP [Yb 3+:Sr 5(PO 4) 3F] crystals for the Mercury laser  

Microsoft Academic Search

Crystals of Yb:S-FAP [Yb3+:Sr5(PO4)3F] will be used as the gain medium for the Mercury Laser, a gas-cooled amplifier system intended to yield 100J, 10Hz and 10% efficiency in 3ns when completed, for inertial fusion energy. Growing high optical quality crystals is a challenge due to a number of growth issues, including: cloudiness, bubble core defects, anomalous absorption, low-angle grain boundaries,

K. I. Schaffers; J. B. Tassano; A. B. Bayramian; R. C. Morris

2003-01-01

272

Beta-Decay Study of ^{150}Er, ^{152}Yb, and ^{156}Yb: Candidates for a Monoenergetic Neutrino Beam Facility  

SciTech Connect

The beta decays of ^{150}Er, ^{152}Yb, and ^{156}Yb nuclei are investigated using the total absorption spectroscopy technique. These nuclei can be considered possible candidates for forming the beam of a monoenergetic neutrino beam facility based on the electron capture (EC) decay of radioactive nuclei. Our measurements confirm that for the cases studied, the EC decay proceeds mainly to a single state in the daughter nucleus.

Estevez Aguado, M. E. [CSIC-Universidad de Valencia; Algora, A. [CSIC-Universidad de Valencia; Rubio, B. [CSIC-Universidad de Valencia; Bernabeu, J. [CSIC-Universidad de Valencia; Nacher, E. [CSIC-Universidad de Valencia; Tain, J. L. [CSIC-Universidad de Valencia; Gadea, A. [CSIC-Universidad de Valencia; Agramunt, J. [CSIC-Universidad de Valencia; Burkard, K. [Gesellschaft fur Schwerionenforschung (GSI), Germany; Hueller, W. [GSI-Hemholtzzentrum fur Schwerionenforschung, Darmstadt, Germany; Doring, J. [Gesellschaft fur Schwerionenforschung (GSI), Germany; Kirchner, R. [Gesellschaft fur Schwerionenforschung (GSI), Germany; Mukha, I. [Gesellschaft fur Schwerionenforschung (GSI), Germany; Plettner, C. [Gesellschaft fur Schwerionenforschung (GSI), Germany; Roeckl, E. [Gesellschaft fur Schwerionenforschung (GSI), Germany; Grawe, H. [GSI-Hemholtzzentrum fur Schwerionenforschung, Darmstadt, Germany; Collatz, R. [Gesellschaft fur Schwerionenforschung (GSI), Germany; Hellstrom, M. [Gesellschaft fur Schwerionenforschung (GSI), Germany; Cano-Ott, D. [CIEMAT, Madrid; Karny, M. [University of Warsaw; Janas, Z. [University of Warsaw; Gierlik, M. [University of Warsaw; Plochocki, A. [University of Warsaw; Rykaczewski, Krzysztof Piotr [ORNL; Batist, L. [Petersburg Nuclear Physics Institute, Gatchina, Russia; Moroz, F. [Petersburg Nuclear Physics Institute, Gatchina, Russia; Wittman, V. [Petersburg Nuclear Physics Institute, Gatchina, Russia; Blazhev, A. [University of Cologne; Valiente, J. J. [INFN, Laboratori Nazionali di Legnaro, Italy; Espinoza, C. [CFPT-IST, Lisbon

2011-01-01

273

Electrochemical formation of Al-Tm intermetallics in eutectic LiCl-KCl melt containing Tm and Al ions  

NASA Astrophysics Data System (ADS)

This work focuses on investigating the electrochemical formation of Al-Tm and Al-Li-Tm alloys in LiCl-KCl-AlCl3-Tm2O3 melt on both W and Al electrodes. Thermodynamic calculation and electrochemical behavior of LiCl-KCl melt containing both AlCl3 and Tm2O3 showed that AlCl3 can chlorinate Tm2O3 to release Tm(III) ions. Three kinds of Al-Tm intermetallics at about -1.26, -1.32 and -1.43 V were detected by means of various electrochemical measurement techniques, i.e. cyclic voltammetry, square wave voltammetry and open circuit chronopotentiometry. Potentiostatic and galvanostatic electrolysis were carried out on Al and W electrodes to prepare Al-Tm and Al-Li-Tm alloys, respectively. The composition of Al-Li-Tm alloys was analyzed by inductive coupled plasma atomic emission spectrometer (ICP-AES).

Li, Xing; Yan, Yong-De; Zhang, Mi-Lin; Tang, Hao; Ji, De-Bin; Han, Wei; Xue, Yun; Zhang, Zhi-Jian

2014-09-01

274

Unusual weak magnetic exchange in two different structure types: YbPt2Sn and YbPt2In  

NASA Astrophysics Data System (ADS)

We present the structural, magnetic, thermodynamic and transport properties of the two new compounds YbPt2Sn and YbPt2In. X-ray powder diffraction shows that they crystallize in different structure types, the hexagonal ZrPt2Al and the cubic Heusler type, respectively. Despite quite different lattice types, both compounds present very similar magnetic properties: a stable trivalent Yb3+, no evidence for a sizeable Kondo interaction and very weak exchange interactions with a strength below 1 K as deduced from specific heat C(T). Broad anomalies in C(T) suggest short range magnetic ordering at about 250 mK and 180 mK for YbPt2Sn and YbPt2In, respectively. The weak exchange and the low ordering temperature result in a large magnetocaloric effect as deduced from the magnetic field dependence of C(T), making these compounds interesting candidates for magnetic cooling. In addition we found in YbPt2In evidences for a charge density wave transition at about 290 K. The occurrence of such transitions within several RET2X compound series (RE = rare earth, T = noble metal, X = In, Sn) is analyzed.

Gruner, T.; Jang, D.; Steppke, A.; Brando, M.; Ritter, F.; Krellner, C.; Geibel, C.

2014-12-01

275

Unusual weak magnetic exchange in two different structure types: YbPt2Sn and YbPt2In.  

PubMed

We present the structural, magnetic, thermodynamic and transport properties of the two new compounds YbPt(2)Sn and YbPt(2)In. X-ray powder diffraction shows that they crystallize in different structure types, the hexagonal ZrPt(2)Al and the cubic Heusler type, respectively. Despite quite different lattice types, both compounds present very similar magnetic properties: a stable trivalent Yb(3+), no evidence for a sizeable Kondo interaction and very weak exchange interactions with a strength below 1 K as deduced from specific heat C(T). Broad anomalies in C(T) suggest short range magnetic ordering at about 250 mK and 180 mK for YbPt(2)Sn and YbPt(2)In, respectively. The weak exchange and the low ordering temperature result in a large magnetocaloric effect as deduced from the magnetic field dependence of C(T), making these compounds interesting candidates for magnetic cooling. In addition we found in YbPt(2)In evidences for a charge density wave transition at about 290 K. The occurrence of such transitions within several RET2X compound series (RE = rare earth, T = noble metal, X = In, Sn) is analyzed. PMID:25322667

Gruner, T; Jang, D; Steppke, A; Brando, M; Ritter, F; Krellner, C; Geibel, C

2014-12-01

276

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

NASA Technical Reports Server (NTRS)

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.

Swetits, John J.

1991-01-01

277

Gender differences in health of EU10 and EU15 populations: the double burden of EU10 men.  

PubMed

This study compares gender differences in Healthy Life Years (HLY) and unhealthy life years (ULY) between the original (EU15) and new member states (EU10). Based on the number of deaths, population and prevalence of activity limitations from the Statistics of Living and Income Conditions Survey (SILC) survey, we calculated HLY and ULY for the EU10 and EU15 in 2006 with the Sullivan method. We used decomposition analysis to assess the contributions of mortality and disability and age to gender differences in HLY and ULY. HLY at age 15 for women in the EU10 were 3.1years more than those for men at the same age, whereas HLY did not differ by gender in the EU15. In both populations ULY at age 15 for women exceeded those for men by 5.5years. Decomposition showed that EU10 women had more HLY because higher disability in women only partially offset (-0.8years) the effect of lower mortality (+3.9years). In the EU15 women's higher disability prevalence almost completely offset women's lower mortality. The 5.3 fewer ULY in EU10 men than in EU10 women mainly reflected higher male mortality (4.5years), while the fewer ULY in EU15 men than in EU15 women reflected both higher male mortality (2.9years) and higher female disability (2.6years). The absence of a clear gender gap in HLY in the EU15 thus masked important gender differences in mortality and disability. The similar size of the gender gap in ULY in the EU-10 and EU-15 masked the more unfavourable health situation of EU10 men, in particular the much stronger and younger mortality disadvantage in combination with the virtually absent disability advantage below age 65 in men. PMID:21212821

Nusselder, W J; Looman, C W N; Van Oyen, H; Robine, J M; Jagger, C

2010-12-01

278

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

SciTech Connect

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.

Ohashi, Sachiyo; Atsumi, Megumi [Research Unit of Biochemistry, College of Pharmacy, Nihon University, Narashinodai, Funabashi, Chiba 274-8555 (Japan)] [Research Unit of Biochemistry, College of Pharmacy, Nihon University, Narashinodai, Funabashi, Chiba 274-8555 (Japan); Kobayashi, Shunsuke, E-mail: kobayashi.shunsuke@nihon-u.ac.jp [Research Unit of Biochemistry, College of Pharmacy, Nihon University, Narashinodai, Funabashi, Chiba 274-8555 (Japan)] [Research Unit of Biochemistry, College of Pharmacy, Nihon University, Narashinodai, Funabashi, Chiba 274-8555 (Japan)

2009-08-07

279

Exchange-induced Tm magnetism in multiferroic h-TmMnO3  

NASA Astrophysics Data System (ADS)

Analysis of 169Tm Mssbauer spectra recorded for (hexagonal phase) h- TmMnO3 confirms that the Mn sublattice orders magnetically below TNMn = 82-83 K and reveals the growth of a local Tm moment at the 4b site that is induced by the Mn-Tm exchange interaction. The maximum hyperfine field recorded at the 169Tm nucleus is 312 T, which is just under half of the free ion value and corresponds to a saturation moment of 3.29 B. The temperature dependence of the fitted magnetic hyperfine interaction is closely represented by a simple two-singlet ground state model for the Tm3+ crystal field scheme. The saturation molecular field is deduced to lie in the range BMn-Tm(T = 0 K) = 1.2-2.3 T, dependent on the expectation value of the coupling ? = lang0|Jz|1rang between the two-singlet states. As observed elsewhere for other hexagonal manganites, there is no Mn-based exchange field at the second Tm site (the 2a site) which contributes a paramagnetic subspectrum down to the lowest experimental temperature of 4.2 K.

Salama, Hazar A.; Stewart, G. A.

2009-09-01

280

Quadrupole interaction at169Tm in orthorhombic TmF3  

NASA Astrophysics Data System (ADS)

Quadrupole interaction data recorded by Triplett et al for the C1hTm site in TmF3 are analysed via semi-empirical procedures, one of which employs rank 2 CF parameters derived from the155Gd: GdF3 Mssbauer results of Katila et al. The fitted crystal field interactions are compared with available optical spectroscopy results.

Stewart, G. A.

1990-07-01

281

TM-align: a protein structure alignment algorithm based on the TM-score  

Microsoft Academic Search

We have developed TM-align, a new algorithm to identify the best structural alignment between protein pairs that combines the TM-score rotation matrix and Dynamic Programming (DP). The algo- rithm is ? 4 times faster than CE and 20 times faster than DALI and SAL. On average, the resulting struc- ture alignments have higher accuracy and coverage than those provided by

Yang Zhang; Jeffrey Skolnick

2005-01-01

282

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

ERIC Educational Resources Information Center

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] =

Thompson, Bruce; Cook, Colleen; Kyrillidou, Martha

2005-01-01

283

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

SciTech Connect

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

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

2008-06-09

284

Breathing Oscillations in Bose - Fermi Mixing Gases with Yb atoms in the Largely Prolate Deformed Traps  

E-print Network

We study the breathing oscillations in bose-fermi mixtures with Yb isotopes in the largely prolate deformed trap, which are realized by Kyoto group. We choose the three combinations of the Yb isotopes, Yb170-Yb171, Yb170-Yb173 and Yb174-Yb173, whose boson-fermion interactions are weakly repulsive, strongly attractive and strongly repulsive. The collective oscillations in the deformed trap are calculated in the dynamical time-development approach, which is formulated with the time-dependent Gross-Pitaevskii and the Vlasov equations. We analyze the results in the time-development approach with the intrinsic oscillation modes of the deformed system, which are obtained using the scaling method, and show that the damping and forced-oscillation effects of the intrinsic modes give time-variation of oscillations, especially, in the fermion transverse mode.

Tomoyuki Maruyama; Hiroyuki Yabu

2014-03-06

285

Interwoven pair of open frameworks in the thiosphosphate K6Yb3(PS4)5.  

PubMed

K6Yb3(PS4)5 possesses two identical but interlocked three-dimensional frameworks. Each framework is realized by having Yb3+ atoms adopt both octahedral and trigonal prismatic sulfur coordination. PMID:15382898

Aitken, Jennifer A; Kanatzidis, Mercouri G

2004-09-29

286

Deposit Insurance During EU Accession  

Microsoft Academic Search

The paper presents a brief review of the systems of deposit insurance in accession countries, comparing their level of harmonization with the perspective of their EU integration. Studying the different practices of deposit insurance in the context of developing financial safety nets in future Europe we have found that: (i) there is overinsurance of deposits in accession countries, and (ii)

Nikolay Nenovsky; Kalina Dimitrova

2003-01-01

287

Possible origin of the higher magnetic phase transition in RuSr2 Eu1.5 Ce0.5 Cu2 O10  

NASA Astrophysics Data System (ADS)

Two magnetic transitions are observed in the magnetosuperconducting RuEu2-xCexSr2Cu2O10-? (Ru-1222), at TM160K and TM280K . Below TM2 the Ru moments are weak-ferromagnetically ordered and wide ferromagnetic hysteresis loops are observed; they become narrow and disappear at 60-70K . Above TM2 , (i) small antiferromagneticlike hysteresis loops reappear with a peak in the coercive fields around 120 K. (ii) A small peak at 120K is also observed in the dc and ac susceptibility curves. The two phenomena are absent in the non-SC x=1 samples. For x<1 , the decrease of the Ce4+ content is compensated by nonhomogeneous oxygen depletion, which may induce a reduction of Ru5+ ions to Ru4+ . The higher ordering temperature, TM , which does not change with x , may result from Ru4+ rich clusters, in which the Ru4+-Ru4+ exchange interactions are stronger than the Ru5+-Ru5+ interactions. In the superconducting Ru1-xMoxSr2Eu1.5Ce0.5Cu2O10 (x=0-0.4) system, TM2 shifts to low temperature with x (14 K for x=0.4 ), whereas TM is not affected by the Mo content, indicating again that TM may not correspond to the main phase. Two scenarios are suggested to explain the magnetic phenomena at TM2TM . (i) They are due to a small fraction of nanosize islands inside the crystal grains, in which the Ru4+ concentration is high and are magnetically ordered below TM . (ii) The presence of nanoparticles of a foreign minor extra Ru4+ magnetic phase of Sr-Cu-Ru-O3 , which orders at TM , in which Cu is distributed inhomogeneously in both the Ru and Sr sites. This second scenario is supported by Mssbauer spectroscopy of Fe57 doped in Sr-Cu-Ru-O3 systems.

Felner, I.; Galstyan, E.; Nowik, I.

2005-02-01

288

Temperature dependence of Eu 4f and Eu 5d spin magnetizations in the filled skutterudite EuFe4Sb12  

Microsoft Academic Search

The element specific and shell specific magnetism of Eu in the filled skutterudite ferrimagnet Eu0.95Fe4Sb12 has been investigated using Eu M4,5 and Eu L2,3 edge x-ray magnetic circular dichroism (XMCD) spectroscopy as a function of temperature. Eu L3 edge and Eu M5 edge x-ray absorption spectroscopy clearly show that Eu is in a mixed valence state. Sum rule analysis of

Vemuru Krishnamurthy; D. J. Keavney; D. Haskel; J. C. Lang; G. Srajer; Brian C Sales; Lee Robertson; David Mandrus

2009-01-01

289

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

NASA Astrophysics Data System (ADS)

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

?mojda, Jacek; Dorosz, Dominik; Kochanowicz, Marcin; Miluski, Piotr; Dorosz, Jan

290

Stable Bound States of Yb and Pr Negative Ions  

NASA Astrophysics Data System (ADS)

Andersen et al [1] concluded, through careful experimental investigation, that the electron affinity (EA) of Yb should be less than 3 meV and the accuracy of the theoretical calculations was deemed insufficient to provide a definitive answer to whether a stable bound state of the negative Yb ion exists. Such a small EA value for Yb is suitable for quenching Rydberg states, going through the formation of a temporary negative ion by ground state atoms with low EA's [2]. Our result obtained using the recent Regge- pole methodology [3] in which a Thomas-Fermi potential incorporates the important core- polarization potential, contradicts the conclusion in [1] by predicting a binding energy of 28 meV for the Yb^- ion with a d-orbital electron attachment, including a Ramsauer-Townsend minimum at 20 meV and an s-wave Wigner threshold behavior of the total elastic cross section. Results for the e^--Pr scattering will also be presented and contrasted with those for e^--Yb scattering. [1] H. H. Andersen, T. Andersen and U. V. Petersen, J. Phys. B 31, 2239 (1998)[2] I. I. Fabrikant and V. S. Lebedev, J. Phys. B 33, 1521 (2000)[3] D.Sokolovski et al, Phys. Rev. A 76, 012705 (2007)

Msezane, A. Z.; Felfli, Z.; Sokolovski, D.

2008-05-01

291

First-Order Antiferromagnetic Transition and Fermi Surfaces in Semimetal EuSn3  

NASA Astrophysics Data System (ADS)

We grew high-quality single crystals of the antiferromagnet EuSn3 with the AuCu3-type cubic crystal structure by the Sn self-flux method and measured the electrical resistivity, magnetic susceptibility, high-field magnetization, specific heat, thermal expansion, and de Haasvan Alphen (dHvA) effect, in order to study the magnetic and Fermi surface properties. We observed steplike changes in the electrical resistivity and magnetic susceptibility, and a sharp peak of the specific heat and thermal expansion coefficient at a Nel temperature TN = 36.4 K. The first-order nature of the antiferromagnetic transition was ascertained by the observation of thermal hysteresis as well as of latent heat at TN. The present antiferromagnetic transition is found to be not a typical second-order phase transition but a first-order one. From the results of dHvA experiment, we clarified that the Fermi surface is very similar to that of the divalent compound YbSn3, mainly consisting of a nearly spherical hole Fermi surface and eight ellipsoidal electron Fermi surfaces. EuSn3 is possibly a compensated metal, and the occupation of a nearly spherical hole Fermi surface is 3.5% in its Brillouin zone, indicating that EuSn3 is a semimetal.

Mori, Akinobu; Miura, Yasunao; Tsutsumi, Hiroki; Mitamura, Katsuya; Hagiwara, Masayuki; Sugiyama, Kiyohiro; Hirose, Yusuke; Honda, Fuminori; Takeuchi, Tetsuya; Nakamura, Ai; Hiranaka, Yuichi; Hedo, Masato; Nakama, Takao; ?nuki, Yoshichika

2014-02-01

292

TORR TM DE-OILING TECHNOLOGY  

E-print Network

he TORR TM de-oiling technology, with its small footprint and ability to replace less efficient de-oiling equipment, offers the best available process in the treatment of produced water for offshore producers and operators. The TORR TM technology exceeds todays discharge regulations and will address future regulations. The scaleable technology addresses future increases in water cut. Adding compact TORR TM vessels requires very little real estate when water cuts increase. FEATURES Small footprint and low weight 1000 ppm down to discharge regulation Better polishing for reinjection applications Removes and recovers oil droplets larger than 2 microns Maximum flow rate per vessel of 60,000 BWPF Same high de-oiling efficiency during production start-up periods No additional treatment required for recovered oil Minimal pressure drop and maintenance and minimal operation costs Recovered hydrocarbons can be <0.5 % BSW High flow rate turndown No moving internal parts No added heat or chemicals Operational temperatures up to 90?C Solids handing capabilities Reduced process complexityTECHNOLOGY The TORR TM process consists of two inline pressure vessels, and an optional third vessel can be used as a standby. Produced water enters the TORR TM unit for treatment and then passes through the core of multiple continuous coalescing elements. The continuous coalescing element adsorbs the small oil droplets, coalesces them to large oil globules and then desorbs them. Gravity separation principles remove these large coalesced globules, which then rise to the top of the vessel. Any solution gas accumulating with the oil at the top of the vessel will be safely recovered. The oil and/or gas collected at the top of the vessel are recuperated and returned to a suitable collection unit. The TORR TM technology treated produced water exceeds discharge regulations.

Kompleks Antarabangsa

293

Reactivation of methionine synthase from Thermotoga maritima (TM0268) requires the downstream gene product TM0269.  

PubMed

The crystal structure of the Thermotoga maritima gene product TM0269, determined as part of genome-wide structural coverage of T. maritima by the Joint Center for Structural Genomics, revealed structural homology with the fourth module of the cobalamin-dependent methionine synthase (MetH) from Escherichia coli, despite the lack of significant sequence homology. The gene specifying TM0269 lies in close proximity to another gene, TM0268, which shows sequence homology with the first three modules of E. coli MetH. The fourth module of E. coli MetH is required for reductive remethylation of the cob(II)alamin form of the cofactor and binds the methyl donor for this reactivation, S-adenosylmethionine (AdoMet). Measurements of the rates of methionine formation in the presence and absence of TM0269 and AdoMet demonstrate that both TM0269 and AdoMet are required for reactivation of the inactive cob(II)alamin form of TM0268. These activity measurements confirm the structure-based assignment of the function of the TM0269 gene product. In the presence of TM0269, AdoMet, and reductants, the measured activity of T. maritima MetH is maximal near 80 degrees C, where the specific activity of the purified protein is approximately 15% of that of E. coli methionine synthase (MetH) at 37 degrees C. Comparisons of the structures and sequences of TM0269 and the reactivation domain of E. coli MetH suggest that AdoMet may be bound somewhat differently by the homologous proteins. However, the conformation of a hairpin that is critical for cobalamin binding in E. coli MetH, which constitutes an essential structural element, is retained in the T. maritima reactivation protein despite striking divergence of the sequences. PMID:17656578

Huang, Sha; Romanchuk, Gail; Pattridge, Katherine; Lesley, Scott A; Wilson, Ian A; Matthews, Rowena G; Ludwig, Martha

2007-08-01

294

Reactivation of methionine synthase from Thermotoga maritima (TM0268) requires the downstream gene product TM0269  

PubMed Central

The crystal structure of the Thermotoga maritima gene product TM0269, determined as part of genome-wide structural coverage of T. maritima by the Joint Center for Structural Genomics, revealed structural homology with the fourth module of the cobalamin-dependent methionine synthase (MetH) from Escherichia coli, despite the lack of significant sequence homology. The gene specifying TM0269 lies in close proximity to another gene, TM0268, which shows sequence homology with the first three modules of E. coli MetH. The fourth module of E. coli MetH is required for reductive remethylation of the cob(II)alamin form of the cofactor and binds the methyl donor for this reactivation, S-adenosylmethionine (AdoMet). Measurements of the rates of methionine formation in the presence and absence of TM0269 and AdoMet demonstrate that both TM0269 and AdoMet are required for reactivation of the inactive cob(II)alamin form of TM0268. These activity measurements confirm the structure-based assignment of the function of the TM0269 gene product. In the presence of TM0269, AdoMet, and reductants, the measured activity of T. maritima MetH is maximal near 80C, where the specific activity of the purified protein is ?15% of that of E. coli methionine synthase (MetH) at 37C. Comparisons of the structures and sequences of TM0269 and the reactivation domain of E. coli MetH suggest that AdoMet may be bound somewhat differently by the homologous proteins. However, the conformation of a hairpin that is critical for cobalamin binding in E. coli MetH, which constitutes an essential structural element, is retained in the T. maritima reactivation protein despite striking divergence of the sequences. PMID:17656578

Huang, Sha; Romanchuk, Gail; Pattridge, Katherine; Lesley, Scott A.; Wilson, Ian A.; Matthews, Rowena G.; Ludwig, Martha

2007-01-01

295

Eu III identification and Eu abundance in cool CP stars  

E-print Network

We report the first identification of the Eu III lambda 6666.317 line in optical spectra of CP stars. This line is clearly present in the spectra of HR 4816, 73 Dra, HR 7575, and beta CrB, while it is marginally present or absent in spectra of the roAp stars alpha Cir, gamma Equ, BI Mic, 33 Lib, and HD 24712.

T. Ryabchikova; N. Piskunov; I. Savanov; F. Kupka

1998-05-15

296

Yb:YAG Lasers for Space Based Remote Sensing  

NASA Technical Reports Server (NTRS)

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.

Ewing, J.J.; Fan, T. Y.

1998-01-01

297

Strong Eu2+ light emission in Eu silicate through Eu3+ reduction in Eu2O3/Si multilayer deposited on Si substrates  

PubMed Central

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

2013-01-01

298

CCRS proposal for evaluating LANDSAT-4 MSS and TM data  

NASA Technical Reports Server (NTRS)

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.

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

299

ORNL/TM-2008/048 Uranyl Nitrate Flow Loop  

E-print Network

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

Pennycook, Steve

300

Quantitative analysis of Eu 2+ and Eu 3+ in LiCl-KCl eutectic melt by spectrophotometry and electrochemistry  

NASA Astrophysics Data System (ADS)

The redox behavior of Eu 2+ and Eu 3+ in the LiCl-KCl eutectic at 773 K was investigated. Since the equilibrium potential of the melt is very close to the redox potential of the Eu 3+|Eu 2+ couple, the Eu 2+ and Eu 3+ species coexist. Quantitative analysis of Eu 2+ and Eu 3+ was performed by spectrophotometry and by potentiometry. Under the coexistence of Eu 2+ and Eu 3+, potentiometric titration of Eu ion using a yttria-stabilized zirconia membrane electrode (YSZME) was performed by changing the concentration of O 2-. The formation of the europium oxychloride, EuOCl, was confirmed by X-ray diffraction analysis, whiles no precipitation of the oxides, EuO and Eu 2O 3, was found. The equivalent point of the EuOCl formation ( x = [O 2-] added/[Eu] total) was shifted to a smaller value from the theoretical value ( x = 1) due to the coexisting Eu 2+. The contribution of the coexisting Eu 2+ to the formation of EuOCl was estimated by using [Eu 2+]/[Eu 3+] as determined by potentiometry and this was subtracted from the titration data. The solubility product of EuOCl was determined to be p ks(EuOCl) = 7.81 0.10.

Kim, Tack-Jin; Uehara, Akihiro; Nagai, Takayuki; Fujii, Toshiyuki; Yamana, Hajimu

2011-02-01

301

Heavy quasiparticles formed in the ferromagnetic Yb layers in the Kondo helical magnet YbNi3Al9 as revealed by specific-heat measurements  

NASA Astrophysics Data System (ADS)

We report specific-heat and magnetocaloric-effect studies on single-crystalline Kondo helical magnet YbNi3Al9. Molecular field analysis of a Schottky peak due to the Zeeman splitting of the Yb-ion doublet crystalline-field ground state demonstrates that the interlayer antiferromagnetic exchange interactions are 2 orders of magnitude smaller than that of the intralayer ferromagnetic coupling among Yb ions, reflecting realization of magnetically well separated Yb layers. The Sommerfeld coefficient ?, which is 110 mJ/K2mol in zero field, decreases smoothly with increasing field without any noticeable anomalies at the helical magnetic phase boundary. This fact confirms that heavy quasiparticles are formed on a part of the Fermi surface away from hot sheets that have nesting instabilities responsible for the helical magnetic structure. These results indicate that YbNi3Al9 is a novel system where heavy quasiparticles are confined within the two-dimensional Yb layers.

Miyazaki, Ryoichi; Aoki, Yuji; Higashinaka, Ryuji; Sato, Hideyuki; Yamashita, Testuro; Ohara, Shigeo

2012-10-01

302

Evaluation of Gamma-Ray Response of Tm: Single Crystals  

Microsoft Academic Search

Tm3+ doped BaF2 single crystal scintillator has been investigated. Undoped, 0.1, 0.5, and 1% Tm -doped BaF2 are compared in terms of their decay time, light yield, non-proportionality and energy resolution. The fast component of Tm doped BaF2 is characterized by a 5 ~ 6 ns decay time and it can be related to the Tm3+ 5d - 4f VUV

Naoto Abe; Yuui Yokota; Takayuki Yanagida; Noriaki Kawaguchi; Jan Pejchal; Akira Yoshikawa

2010-01-01

303

Er/Yb co-doped fiber amplifier with wavelength-tuned Yb-band ring resonator  

NASA Astrophysics Data System (ADS)

Erbium-ytterbium co-doped fiber amplifier with wavelength-tuned Yb-band loop resonator is presented. The amplified spontaneous emission (ASE) from Yb ions is utilized to stimulate a laser emission at several wavelengths from the 1 ?m band in the 1550 nm amplifier. The wavelength of this lasing is tuned by introducing a fiber Bragg grating (FBG). The results show, that the overall efficiency of the amplifier at nominal 1550 nm wavelength can be increased by introducing a feedback loop with 1040 nm and 1050 nm FBG. This loop also protects the Er/Yb amplifier from parasitic lasing at 1 ?m and allows significant output power scaling without risk of self-pulsing.

Sobon, Grzegorz; Sliwinska, Dorota; Kaczmarek, Pawel; Abramski, Krzysztof M.

2012-08-01

304

Investigation on luminescence properties of Er3+Yb3+Tm3+ co-doped Gd2O3 hollow microspheres  

Microsoft Academic Search

The Gd2O3 hollow microspheres have been successfully fabricated via carbonaceous polysaccharide microspheres as templates and urea as a precipitating agent, which involved the deposition of an inorganic coating on the surface of carbon microsphere, followed by heat treated 800C for 4h. The obtained high uniform Gd2O3 microspheres with a spherical shape and hollow structure are uniform in size and distribution.

Fang Xu; Wan-Lei Han; Xiao-Bo Liu; Ying-Lin Song

2011-01-01

305

The Neuroscience of PowerPoint[TM  

ERIC Educational Resources Information Center

Many concepts have been published relevant to improving the design of PowerPoint[TM] (PP) presentations for didactic purposes, including the redundancy, modality, and signaling principles of multimedia learning. In this article, we review the recent neuroimaging findings that have emerged elucidating the neural structures involved in many of these

Horvath, Jared Cooney

2014-01-01

306

August 2002 NASA/TM--2002211612  

E-print Network

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

Richardson, John

307

NASA/TM--2001210880 Photographic Analysis Technique  

E-print Network

NASA/TM--2001­210880 Photographic Analysis Technique for Assessing External Tank Foam Loss Events T'Farrell United Space Alliance, Huntsville, Alabama June 2001 #12;Since its founding, NASA has been dedicated to the advancement of aeronautics and space science. The NASA Scientific and Technical Information (STI) Program

Christian, Eric

308

August 2004 NASA/TM--2004212824  

E-print Network

August 2004 NASA/TM--2004­212824 Stress, Cognition, and Human Performance: A Literature Review and Conceptual Framework Mark A. Staal Ames Research Center, Moffett Field, California #12;The NASA STI Program Office ... in Profile Since its founding, NASA has been dedicated to the advancement of aeronautics

309

December 2003 NASA/TM--2003212809  

E-print Network

, California 94035 #12;Acknowledgments Funding for this work was provided by NASA's Aviation Safety Program Institutes for Research R. Key Dismukes NASA Ames Research Center Funding for this work was provided by NASADecember 2003 NASA/TM--2003­212809 A Gold Standards Approach to Training Instructors to Evaluate

310

:>':. '*>3 1 /? ORNL/TM-8022  

E-print Network

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

Oak Ridge National Laboratory

311

Defying Gravity Using Jenga[TM] Blocks  

ERIC Educational Resources Information Center

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.)

Tan, Yin-Soo; Yap, Kueh-Chin

2007-01-01

312

Operational Atmospheric Correction of Landsat TM Data  

Microsoft Academic Search

The recent algorithms developed for biophysical variables assessment require accurate surface reflectance measurements. This article describes algorithms used for atmospheric correction of Landsat Thematic Mapper (TM) data. Atmospheric corrections include Rayleigh scattering, gaseous absorption, and aerosol scattering in three visible channels (480 nm, 560 nm, and 660 nm), and the near-infrared channel (830 nm). Atmospheric constituents such as water vapor

Hassan Ouaidrari; Eric F. Vermote

1999-01-01

313

On the magnetic structure of RuEu1.5Ce0.5Sr2Cu2O10 (Ru-1222)  

NASA Astrophysics Data System (ADS)

Two magnetic transitions at TM~160 K and at TM2~80-100 K, are observed in the magneto-superconducting RuEu2-xCexSr2Cu2O10-? (TC = 32-50 K). Below TM2, the Ru5+ moments are weakly-ferromagnetically ordered and wide ferromagnetic hysteresis loops are observed, they become narrow and disappear at ~ 60-70 K. Dc magnetic studies on c-axis oriented epitaxial thin films of Ru-1222 on (100) SrTiO3 wafers show that the easy axis of the magnetization is in the basal plane and the Ru5+ ions are in their high-spin state. Above TM2, (i) small antiferromagnetic-like hysteresis loops reappear with a peak in the coercive fields around 120 K. (ii) A small peak at ~120 K is also observed in the dc and ac susceptibility curves. The two phenomena are absent in the non-superconducting RuEuCeSr2Cu2O10-? (x=1) samples. Two scenarios are suggested for the phenomena at TM2TM. (i) For x<1, the decrease of the Ce4+ content, is compensated by non-homogeneous oxygen depletion, which may induce a reduction of Ru5+ ions to Ru4+. The higher ordering temperature, TM, which does not change with x, may result from Ru4+ nano-size rich clusters, in which the Ru4+-Ru4+ exchange interactions are stronger than the Ru5+-Ru5+ interactions. Or alternatively,(ii) The presence of nanoparticles of a minor foreign extra Ru4+ magnetic phase, such as Sr-Cu-Ru-O3, in which Cu is distributed inhomogeneously in both the Ru and Sr sites.

Felner, I.

2005-08-01

314

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

ERIC Educational Resources Information Center

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

Burke, Barry N.

2006-01-01

315

Thermoelectric properties of Yb-filled CoSb3 skutterudites  

NASA Astrophysics Data System (ADS)

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.

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

2014-08-01

316

Growth of Yb: S-FAP [Yb 3+:Sr 5(PO 4) 3F] crystals for the Mercury laser  

NASA Astrophysics Data System (ADS)

Crystals of Yb:S-FAP [Yb 3+:Sr 5(PO 4) 3F] will be used as the gain medium for the Mercury Laser, a gas-cooled amplifier system intended to yield 100 J, 10 Hz and 10% efficiency in 3 ns when completed, for inertial fusion energy. Growing high optical quality crystals is a challenge due to a number of growth issues, including: cloudiness, bubble core defects, anomalous absorption, low-angle grain boundaries, cracking, and crystal inclusions. At this time, a growth process has been developed to simultaneously eliminate or diminish each of the defects.

Schaffers, K. I.; Tassano, J. B.; Bayramian, A. B.; Morris, R. C.

2003-06-01

317

Fabrication and XAFS analysis of Yb3+ doped yttrium lanthanum oxide transparent ceramics  

NASA Astrophysics Data System (ADS)

(YbxY0.90-xLa0.10)2O3 (x = 0.01-0.10) transparent ceramics were fabricated and their structural properties were investigated. The XRD showed our samples exhibited single cubic Y2O3 phase. The lattice parameters were refined with the Rietveld method. The compact structure and an average grain size of 40-50 ?m were revealed by the microstructure. The local fine structure around Yb ions was investigated by using the XAFS (X-ray absorption fine structure) technique. The results showed that: the local structure around Yb ions in the samples with different concentration of Yb ions was basically similar, and Yb ions replaced Y position to form the solid solution. The Yb ions were trivalent. With the concentration of Yb2O3 increased, the coordination number (N) and first shell Yb-O bond length (R) decreased, and the degree of disorder (?) increased.

Jiang, Cen; Yang, Qiuhong; Lu, Qing; Zhang, Haojia

2013-12-01

318

Special effects of YbF 3 on the structural changes for fluorophosphate glass  

NASA Astrophysics Data System (ADS)

From Raman and IR spectra, obvious differences of the glass structure were observed in non-Yb 3+-doped and Yb 3+-doped fluorophosphate glasses. Results showed that Yb 3+ ions can induce, in a better glass, polymerization and network uniformity. Compared with the monophosphate-mastered Yb 3+-free glass, Yb 3+-doped glass has a pyrophosphate environment. The main building blocks in Yb 3+-doped samples are metaphosphate groups, pyrophosphate groups (P 2(O,F) 7,PO 3F), Al[F 6]+Al[O,F] 6 and F 3Al-O-AlF 3 while those of the Yb 3+-free glasses are monophosphate groups P(O,F) 4, little pyrophosphate groups, Al[F 4]+Al[F 6]+Al[O,F] 4+Al[O,F] 6 and F 3Al-O-AlF 3. The DSC analysis also showed a slight increase in crystallization stability.

Zhang, Liyan; Sun, Hongtao; Xu, Shiqing; Zhang, Junjie; Hu, Lili

2005-10-01

319

Governance in EU illicit drugs policy.  

PubMed

This commentary represents the authors' views on EU governance in illicit drug policy, a field in which they were active for more than 10 years between them. EU drug policy has a narrow legal basis in the European Treaties and is mostly non-binding. The main policy instruments are 8-year EU Drug Strategies, underpinned by 4-year Action Plans which set out specific objectives at national, EU or international level. The approach that guides EU drug policy is known as the 'balanced approach'. It is remarkably restrained and reflects the reality that very few Member States have either the socio-political culture or the resources to consistently apply the punitive sanctions foreseen by the UN conventions. An important feature of EU governance in the field of drugs is the proactive support that is provided to non-governmental organisations both within the EU as well as in accession, associated or third countries. At a global level, the EU is a major financial aid donor also in this field. This position is not however reflected in corresponding political clout for the EU within the UN system. EU governance on drugs has made it possible for many of its Member States to accommodate the problem rather than to "solve" what by all the evidence from the last 100 years may well be insoluble, at least by means of criminalisation and prohibition. The big question is where EU drug policy is headed in the next few years. The EU has been promoting measures and practices that target real problems. It has done so without indulging too much in unhelpful rhetoric. However, like all successful formulae this one also has a sell-by date. EU governance in the field of drugs cannot afford to stand still. It needs to find a second wind. PMID:25060612

Edwards, Carel; Galla, Maurice

2014-09-01

320

LETTER TO THE EDITOR: Heterogeneous mixed valence in YbPd3S4: evidence from 170Yb Mssbauer and x-ray LIII-edge absorption measurements  

NASA Astrophysics Data System (ADS)

The intermetallic bronze YbPd3S4 is shown to be a heterogeneous mixed-valence system, by means of 170Yb Mssbauer spectroscopy and x-ray LIII-edge absorption and magnetic measurements. Two valence states coexist in this compound: Yb3+ and close-to-divalent Yb. The trivalent fraction (about 50%) undergoes a transition to magnetic ordering at about 2 K, with the Gamma7 doublet as the ground crystal field state. The possibility of charge (or valence) ordering is discussed.

Bonville, P.; Godart, C.; Alleno, E.; Takahashi, F.; Matsuoka, E.; Ishikawa, M.

2003-05-01

321

A Revised Periodic Table: With the Lanthanides Repositioned  

Microsoft Academic Search

The lanthanide elements from lanthanum to lutetium inclusive are incorporated into the body of the periodic table. They are\\u000a subdivided into three sub-groups according to their important oxidation states: La to Sm, Eu to Tm, Yb and Lu, so that Eu\\u000a and Yb fall directly below Ba; La, Gd, Lu form a column directly below Y; Ce and Tb fall

Michael Laing

2005-01-01

322

Investigation of loss processes of Tm and Tm,Ho in YAG  

NASA Technical Reports Server (NTRS)

The loss of excitation from various manifolds of Tm and Tm,Ho in YAG as a function of temperature and concentration is studied. Two probable loss mechanisms - a Tm up-conversion and a Ho up-conversion - are identified. A 785-nm CW diode laser with 400-nW peak power was focused to a small spot on the sample. The emission from the sample observed at 90 deg was monitored through a monochromator with slits open to 3 mm. Intensity of emission was measured by varying the power of the excitation source using a set of neutral density filters. Power is reported as the percentage of the peak power, and the intensity curves were normalized below 20 percent of transmission. The fact that there is emission above the pump energy indicates an up-conversion from excited manifolds. Nonlinear changes in the intensity of the emission from the Tm 3F4 manifold with the pump power reveals a loss of excitation from this manifold. The linear dependence of the 5I7 manifold emission with pump power at low Tm and high Ho concentrations and the gain of energy in the 5I6 manifold of Ho indicate that the 5I7 manifold loss is due to the coupling of Tm and Ho ions.

Armagan, G.; Buoncristiani, A. M.; Bair, C. H.; Inge, A. T.; Hess, R. V.

1991-01-01

323

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

ERIC Educational Resources Information Center

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

Hailstone, Jono; Kilding, Andrew E.

2011-01-01

324

Multiphoton imaging with sub-30 fs Yb fiber laser  

NASA Astrophysics Data System (ADS)

An Yb fiber laser oscillator with sub-30 fs pulses compressed by MIIPS is tested for multiphoton microscopy. It leads to greatly improved third harmonic generation images. Multiphoton fluorescence, second and third harmonic generation modalities are compared on stained microspheres and unstained biological tissues.

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

2012-03-01

325

Laser-radiofrequency double resonance spectroscopy of YbF  

SciTech Connect

The authors have measured electron spin flip transition frequencies in the X{sup 2}{Sigma}{sup +} ground state of YbF using laser-rf double resonance spectroscopy. This technique leads to significant improvement in accuracy compared with previous Doppler-free laser measurements of YbFs spin-rotation/hyperfine structure. YbF might be expected to resemble the alkaline earth fluorides, but the authors find its spin-rotation structure to be anomalous. Apart from its interest as a {open_quotes}single electron molecule{close_quotes}, YbF is expected to be an extremely sensitive system with which to search for a permanent electric dipole moment (edm) of the electron. The electron edm has important consequences for elementary particle physics. In particular, many extensions to the Standard Model of elementary particle physics predict the electron edm to be large enough to be measured in a sensitive experiment. The authors discuss the prospects for such a measurement in light of recent results.

Sauer, B.E.; Wang, Jun; Hinds, E.A. [Yale Univ., New Haven, CT (United States)

1995-12-31

326

Manganese-substituted rare-earth zinc arsenides RE(1-y)Mn(x)Zn(2-x)As2 (RE = Eu-Lu) and RE(2-y)Mn(x)Zn(4-x)As4 (RE = La-Nd, Sm, Gd).  

PubMed

Two series of Mn-substituted rare-earth zinc arsenides RE(1-y)Mn(x)Zn(2-x)As2 (RE = Eu-Lu) and RE(2-y)Mn(x)Zn(4-x)As4 (RE = La-Nd, Sm, Gd) were prepared by reaction of the elements at 750 C. Both series are derived from ideal empirical formula REM2As2 (M = Mn, Zn) and adopt crystal structures related to the trigonal CaAl2Si2-type (space group P3m1) in which hexagonal nets of RE atoms and [M2As2] slabs built up of edge-sharing M-centered tetrahedra are alternately stacked along the c-direction. For compounds with divalent RE components (Eu, Yb), the fully stoichiometric and charge-balanced formula REM2As2 is obtained, with Mn and Zn atoms statistically disordered within the same tetrahedral site. For compounds with trivalent RE components, the RE sites become deficient, and the Mn atoms are segregated from the Zn atoms in separate tetrahedral sites. Within the series RE(1-y)Mn(x)Zn(2-x)As2 (Gd-Tm, Lu), the parent CaAl2Si2-type structure is retained, and the Mn atoms are disordered within partially occupied interstitial sites above and below [Zn(2-x)As2] slabs. Within the series RE(2-y)Mn(x)Zn(4-x)As4 (RE = La-Nd, Sm, Gd), the c-axis becomes doubled as a result of partial ordering of Mn atoms between every other pair of [Zn(2-x)As2] slabs. Attempts to synthesize Gd-containing solid solutions with the charge-balanced formula Gd0.67Mn(x)Zn(2-x)As2 suggested that these phases could be formed with up to 50% Mn substitution. Band structure calculations reveal that a hypothetical superstructure model with the formula La1.33MnZn3As4 would have no gap at the Fermi level and that slightly lowering the electron count alleviates antibonding Mn-As interactions; a spin-polarized calculation predicts nearly ferromagnetic half-metallic behavior. X-ray photoelectron spectroscopy confirms the presence of divalent Mn in these compounds. PMID:25062093

Lin, Xinsong; Tabassum, Danisa; Rudyk, Brent W; Mar, Arthur

2014-08-18

327

LaVo4: Eu Phosphor Films with Enhanced Eu Solubility  

SciTech Connect

Eu doped rare-earth orthovanadates are known to be good red phosphor materials. In particular, LaVO{sub 4}:Eu is a promising candidate due to the low Eu-site point symmetry, and thus high dipole transition probability within Judd-Ofelt theory. However, the low solubility limit (< 3 mol %) of Eu in LaVO{sub 4} prevents its efficient use as a phosphor. We present optical evidence of enhanced Eu solubility as high as 10 mol % in LaVO{sub 4}:Eu thin films grown by pulsed laser deposition and postannealing. The photoluminescent intensity exceeded that of YVO{sub 4}:Eu thin films when excited below the host bandgap, indicating stronger direct emission of Eu in LaVO{sub 4}.

Hwang, Harold

2011-08-11

328

Contribution of Eu 4f states to the magnetic anisotropy of EuO  

SciTech Connect

Anisotropic x-ray magnetic linear dichroism (AXMLD) provides a novel element-, site-, shell-, and symmetry-selective techniques to study the magnetic anisotropy induced by a crystalline electric field. The weak Eu2+ M4,5 AXMLD observed in EuO(001) indicates that the Eu 4f states are not rotationally invariant and hence contribute weakly to the magnetic anisotropy of EuO. The results are contrasted with those obtained for 3d transition metal oxides.

Arenholz, E.; Schmehl, A.; Schlom, D.G.; van der Laan, G.

2008-09-11

329

On Yb:CaF2 and Yb:SrF2 : Review of spectroscopic and thermal properties and their  

E-print Network

). 5. A. Lucca, M. Jacquemet, F. Druon, F. Balembois, P. Georges, P. Camy, J.L. Doualan and R. Moncorg, High power tunable diode-pumped Yb3+ :CaF2 laser, Opt. Lett. 29 1879-1881 (2004) 6. A.Lucca, G. Debourg

Paris-Sud XI, Universit de

330

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

NASA Astrophysics Data System (ADS)

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.

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

2012-09-01

331

Internet: http://ue.eu.int E-mail: press.office@consilium.eu.int  

E-print Network

Internet: http://ue.eu.int E-mail: press.office@consilium.eu.int For further information call 32 2 references are given in the text are available on the Council's Internet site http://ue.eu.int. Acts adopted; these statements are available on the above mentioned Council Internet site or may be obtained from the Press

332

Preparation and Thermoelectric Properties of YbAl3 Thermoelectric Materials with Excessive Al  

NASA Astrophysics Data System (ADS)

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.

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

2015-01-01

333

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

NASA Astrophysics Data System (ADS)

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.

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

2015-01-01

334

Evolving Bot AI in UnrealTM  

Microsoft Academic Search

\\u000a This paper describes the design, implementation and results of an evolutionary bot inside the PC game UnrealTM, that is, an autonomous enemy which tries to beat the human player and\\/or some other bots. The default artificial intelligence\\u000a (AI) of this bot has been improved using two different evolutionary methods: genetic algorithms (GAs) and genetic programming\\u000a (GP). The first one has

Antonio Miguel Mora; Ramn Montoya; Juan Julin Merelo Guervs; Pablo Garca-Snchez; Pedro A. Castillo; Juan Lus Jimnez Laredo; Ana Isabel Martnez Garca; Anna Espacia

2010-01-01

335

Evaluating LANDSAT-4 MSS and TM data  

NASA Technical Reports Server (NTRS)

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.

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

336

Efficient sensitization of Yb3+ emission by Nd3+ in Y2O3 transparent ceramics and the prospect for high-energy Yb lasers.  

PubMed

Very efficient energy transfer from Nd3+ to Yb3+ in transparent Y2O3 ceramics in the temperature range 10-300 K is demonstrated. It is inferred that this shows potential for the construction of high-energy Yb3+ lasers under diode or flash-lamp excitation of Nd3+. PMID:19823528

Lupei, Voicu; Lupei, Aurelia; Gheorghe, Cristina; Hau, Stefania; Ikesue, Akio

2009-07-15

337

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

SciTech Connect

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.

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

2011-05-03

338

Alina Mungiu - EU Accession Is No \\  

Microsoft Academic Search

In the textbooks on democratic transition, Central and Eastern Europe provides the model of success. Yet in Brussels concern over the politics of the new EU members has been mounting. The day after accession, when conditionality has faded, the influence of the EU vanished like a short-term anesthetic. Political parties needed to behave during accession in order to reach this

Alina Mungiu-Pippidi

2007-01-01

339

Prospects for Ireland in an Enlarged EU  

Microsoft Academic Search

The CEEC share of Irish exports has grown fivefold since transition began, with export sales expanding in all sectors. Even at current income levels there remains scope for a further doubling of exports, and trade will grow even more substantially if accession facilitates the CEEC in converging more rapidly on EU living standards.Most analyses predict that the EU15 sectors that

Frank Barry

2004-01-01

340

EU Institute in Japan, Kansai Institute of  

E-print Network

Kansai University Wakayama University Kagawa University European Union Delegation of the European Union of the European Union to Japan, the EUIJ-Kansai collects and disseminates EU-related information through the EUIJ in Kansai and western Japan. EU Institute in Japan, Kansai 44 EUInstituteinJapan,Kansai #12;

Banbara, Mutsunori

341

Nernst effect of the intermediate valence compound YbAl3: revisiting the thermoelectric properties  

NASA Astrophysics Data System (ADS)

The Nernst effect and thermopower of the prototypical Yb-based intermediate valence compound YbAl3 were investigated. Different to the thermopower whose absolute values are enhanced with increasing temperature and assume a broad maximum at 175 K, the Nernst coefficient of YbAl3 is enhanced only below T ? 75 K. While the two quantities in the heavy-fermion compound CeCu2Si2 were recently found to be related by the anomalous Hall mobility due to the local asymmetric Kondo scattering, this theorem fails when being applied to YbAl3. Rather, the thermopower of YbAl3 is well described by a simple narrow-band model. We discuss the reason for this in terms of the intermediate valence nature of YbAl3 that is conceptually different from the local Kondo physics.

Wei, Beipei; Zhang, Jiahao; Sun, Peijie; Wang, Wenquan; Wang, Nanlin; Steglich, Frank

2015-03-01

342

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

NASA Astrophysics Data System (ADS)

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%.

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

2015-04-01

343

The relationship between viscosity and glass forming ability of Al-(Ni)-Yb alloy systems  

NASA Astrophysics Data System (ADS)

The dynamic viscosity of Al-Yb and Al-Ni-Yb superheated melts was measured using a torsional oscillation viscometer. The results show that the temperature dependence of viscosity fits the Arrhenius law well and the fitting factors are calculated. The amorphous ribbons of these alloys were produced by the melt spinning technique and the thermal properties were characterized by using a differential scanning calorimetry (DSC). E (the activation energy for viscous flow), which reflects the change rate of viscosity, has a good negative relation with the GFA in both Al-Yb and Al-Ni-Yb systems. However, there is no direct relation between liquidus viscosity ( ? L ) and GFA. The superheated fragility M can predict GFA in Al-Yb or Al-Ni-Yb alloy system.

Jia, Ran; Bian, Xiufang; L, Xiaoqian; Song, Kaikai; Li, Xuelian

2010-03-01

344

Antireflective downconversion ZnO:Er3+,Yb3+ thin film for Si solar cell applications  

NASA Astrophysics Data System (ADS)

Hexagonal wurtzite phased ZnO:Er3+/Yb3+ thin films with various Yb concentrations were deposited on Si(111) substrate by Aerosol Assisted Chemical Vapor Deposition process. Post-annealed films at 1000 C in air atmosphere showed a crystallinity enhancement. Yb3+ (4F7/2 ? 4F5/2) 1000 nm emission increased with the increase of Yb3+ concentration emanating from an Er-Yb energy transfer. The reflectance percentage of 12% was achieved in the [250-1000 nm] range, and the refractive index of 1.97 was obtained for 632 nm wavelength. These results suggest that the (3 mol. % Er, 9 mol. % Yb) codoped film is a highly efficient antireflective downconversion layer for enhancing Si solar cell efficiency.

Elleuch, R.; Salhi, R.; Deschanvres, J.-L.; Maalej, R.

2015-02-01

345

Distribution of 152Eu and 154Eu in the 'alluvial soil-rhizosphere-plant roots' system.  

PubMed

Accumulation of (152)Eu and (15)(4)Eu isotopes in bulk soil and rhizosphere soil in the near-field zone of influence of the Krasnoyarsk Mining and Chemical Combine was studied. An uneven distribution of specific activity of Eu isotopes was observed, with the gross specific activities of the isotopes in the bulk soil exceeding those of the rhizosphere. In the most contaminated locations the fine and the coarse granulometric fractions are enriched with the isotopes. A laboratory experiment indicated potential removal of soluble Eu isotopes by river flood waters may amount to 3% of the total Eu in both bulk and rhizosphere soils. The root system of plants growing in the contaminated territory accumulates (152)Eu and (154)Eu, although the isotopes were not discovered in aboveground parts of plants. Root-hairs were found to be the most contaminated. PMID:22305001

Kropatcheva, Marya; Chuguevsky, Alexei; Melgunov, Mikhail

2012-04-01

346

Measurement of isotope shift in Eu II  

E-print Network

The isotope shift between singly-charged ^Eu and ^Eu in the 4f^7(^8S^o)6s^9S_4-4f^7(^8S^o)6p_1/2>(J=4) transition at 4129 A has been measured using fast ion beam-laser technique. This Eu line has attracted interest in connection with efforts of obtaining a cosmochronometer based on observed Th/Eu abundance ratios. Knowledge of the isotope shift is of importance in order to check that contaminations from line blends do not contribute to the line intensity of Eu II. The measured value of the isotope shift -0.1527(2) cm-1 (= -4578 MHz) is consistent with the old spectroscopic value of Krebs and Winkler -0.1503(25) cm-1 using a Fabry Perot interferometer, while the accuracy is improved substantially.

Lars Brostrom; Sven Mannervik; Peder Royen; Anders Wannstrom

1995-02-06

347

Temperature dependence of Eu4f and Eu5d magnetizations in the filled skutterudite EuFe4Sb12  

Microsoft Academic Search

The element-specific and shell-specific magnetism of Eu in the filled skutterudite ferrimagnet Eu0.95Fe4Sb12 has been investigated using EuM4,5 - and EuL2,3 -edge x-ray magnetic circular dichroism (XMCD) spectroscopy as a function of temperature. EuL3 -edge x-ray absorption spectroscopy shows that Eu is mostly in the divalent state. EuM5 -edge x-ray absorption spectroscopy, measured by electron yield, shows nearly equal fractions

Vemuru Krishnamurthy; D. J. Keavney; D. Haskel; J. C. Lang; G. Srajer; Brian C Sales; David Mandrus; J. L. Robertson

2009-01-01

348

Independence(TM) iBOT(TM) 3000 Mobility System: a stair-climbing wheelchair.  

PubMed

Independence (TM) iBOT(TM) 3000 is a wheelchair that may be used to climb stairs, elevate the user to standing adult eye level and cross uneven terrain. Limited evidence indicates that the device may offer more mobility and freedom to users than conventional wheelchairs. The iBOT may be difficult to manoeuvre indoors due to the seat height, but it operates well outdoors. The use of this technology is limited by the high cost of ownership and uncertain incremental benefit for users. While the device is not yet licensed for use in Canada, it is approved by the Food and Drug Administration for use in the US. PMID:15164734

2004-05-01

349

Laser-induced bulk damage in Yb:S-FAP crystals  

NASA Astrophysics Data System (ADS)

The Mercury laser uses ytterbium-doped strontium fluorapatite (Yb:S-FAP) crystals as the gain medium with a nominal clear aperture of 4 x 6 cm. Recent damage test data have indicated the existence of bulk precursors in Yb:S-FAP that initiate damage starting at approximately 10 J/cm2 at 9 ns under 1064 nm irradiation. In this paper, we report on preliminary results on bulk damage studies on Yb:S-FAP crystals.

Liao, Zhi M.; Adams, John J.; Jarboe, Jeff; Menapace, Joe; Nielsen, Norm; Schrauth, Sam; Wolfe, Justin; Erlandson, Al; Schaffers, Kathleen; Stolz, Christopher; Bayramian, Andy; Carid, John

2007-01-01

350

High efficiency Yb:YAG crystalline fiber-waveguide lasers.  

PubMed

A laser diode (LD) cladding pumped single-mode 1030 nm laser has been demonstrated, in an adhesive-free bonded 40 ?m core Yb:YAG crystalline fiber waveguide (CFW). A laser output power of 13.2 W at a wavelength of 1.03 ?m has been achieved, for an input pump power of 39.5 W. The corresponded laser efficiency is 33.4%. The laser beam quality is confirmed to be near diffraction-limited, with a measured M2 = 1.02. A LD core pumped single-clad Yb:YAG CFW laser has also been demonstrated with a top-hat laser beam profile, with a laser output power of 28 W and a slope efficiency of 78%. PMID:25361347

Mu, Xiaodong; Meissner, Stephanie; Meissner, Helmuth; Yu, Anthony W

2014-11-01

351

New results from the YbF EDM experiment  

NASA Astrophysics Data System (ADS)

The standard model of particle physics predicts that, due to time reversal symmetry, the permanent electric dipole moment (EDM) of the electron is very nearly zero. Many extensions to the standard model predict an electron EDM or other T-violating effects just below current experimental limits, thus there is great interest in new experiments and in improving current experimental precision. I will discuss our recent measurement of the electron EDM using YbF molecules. YbF is particularly sensitive to the electron EDM. This experiment uses a form of laser-radiofrequency double resonance spectroscopy to search for very small energy differences between hyperfine levels in a strong electric field. In addition to describing the experimental and analysis techniques, I will give an overview of the techniques we use to check for systematic errors. I will also describe planned improvements to the experiment which promise several orders of magnitude improvement in sensitivity.

Sauer, B. E.

2013-04-01

352

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

SciTech Connect

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.

Zhang, Zhi-Jun, E-mail: zhangzj@mail.sic.ac.cn [Key Laboratory of Transparent Opto-Functional Inorganic Materials of Chinese Academy of Sciences, Shanghai Institute of Ceramics, Shanghai 200050 (China); Feng, Ang; Chen, Xiang-Yang [Key Laboratory of Transparent Opto-Functional Inorganic Materials of Chinese Academy of Sciences, Shanghai Institute of Ceramics, Shanghai 200050 (China); University of Chinese Academy of Sciences, Beijing 100039 (China); Zhao, Jing-Tai, E-mail: jtzhao@mail.sic.ac.cn [Key Laboratory of Transparent Opto-Functional Inorganic Materials of Chinese Academy of Sciences, Shanghai Institute of Ceramics, Shanghai 200050 (China); School of Materials Science and Engineering, Shanghai University, Shanghai 200072 (China)

2013-12-07

353

Factors governing Yb magnetism in Yb{sub 0.95}PtIn{sub 2} and other MgCuAl{sub 2}-type structures  

SciTech Connect

The ternary compound 'YbPtIn{sub 2}' has been synthesized and its crystal structure determined using single crystal X-ray diffraction techniques. The compound crystallizes in the MgCuAl{sub 2} structure, a ternary structure type often formed when rare earth metals, Group 10 transition metals, and indium are present in a 1:1:2 ratio. The unit cell is C-centered orthorhombic, space group Cmcm (no. 63) with lattice parameters of a=4.3410(1) A, b=10.3230(2) A, and c=7.8510(2) A. Evidence is found for a substantial non-stoichiometry on the Yb site, in contrast to the Pt and In sites which behave as expected, and it is believed that the stoichiometry of this compound is more properly described as Yb{sub 0.95}PtIn{sub 2}. Magnetic and resistivity measurements reveal that 'YbPtIn{sub 2}' is a weakly interacting, non-magnetic metal exclusively containing Yb{sup 2+}, and with a resistivity ({rho}) varying from 34 {mu}{Omega} cm at room temperature to a residual resistivity {rho}{sub 0} of 23 {mu}{Omega} cm at 1.8 K. Density functional theory calculations suggest that the observed diamagnetic Yb behavior is expected for this compound, but that certain substitutions on the Pt or In site could help stabilize magnetic Yb{sup 3+} and potentially induce heavy fermion behavior. - Graphical abstract: The crystal structure, magnetic behavior, and temperature-dependent resistivity of the new ternary compound Yb{sub 0.95}PtIn{sub 2.} Highlights: Black-Right-Pointing-Pointer Flux growth method used to produce Yb{sub 0.95}PtIn{sub 2} single crystals. Black-Right-Pointing-Pointer Found rare example of non-stoichiometry in a MgCuAl{sub 2}-type structure. Black-Right-Pointing-Pointer The resistivity and diamagnetic response of Yb{sub 0.95}PtIn{sub 2} were modeled. Black-Right-Pointing-Pointer DFT correctly predicts presence of Yb{sup 2+} in Yb{sub 0.95}PtIn{sub 2}. Black-Right-Pointing-Pointer COHP results suggest other MgCuAl{sub 2}-type indides that may contain paramagnetic Yb{sup 3+}.

Malingowski, Andrew C. [Department of Chemistry, State University of New York - Stony Brook, Stony Brook, NY 11794-3400 (United States)] [Department of Chemistry, State University of New York - Stony Brook, Stony Brook, NY 11794-3400 (United States); Kim, Moosung [Department of Physics and Astronomy, State University of New York - Stony Brook, Stony Brook, NY 11794-3800 (United States)] [Department of Physics and Astronomy, State University of New York - Stony Brook, Stony Brook, NY 11794-3800 (United States); Liu, Jue [Department of Chemistry, State University of New York - Stony Brook, Stony Brook, NY 11794-3400 (United States)] [Department of Chemistry, State University of New York - Stony Brook, Stony Brook, NY 11794-3400 (United States); Wu, Liusuo [Department of Physics and Astronomy, State University of New York - Stony Brook, Stony Brook, NY 11794-3800 (United States)] [Department of Physics and Astronomy, State University of New York - Stony Brook, Stony Brook, NY 11794-3800 (United States); Aronson, Meigan C. [Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, NY 11973-5000 (United States) [Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, NY 11973-5000 (United States); Department of Physics and Astronomy, State University of New York - Stony Brook, Stony Brook, NY 11794-3800 (United States); Khalifah, Peter G., E-mail: kpete@bnl.gov [Department of Chemistry, State University of New York - Stony Brook, Stony Brook, NY 11794-3400 (United States); Department of Chemistry, Brookhaven National Laboratory, Upton, NY 11973-5000 (United States)

2013-02-15

354

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

NASA Astrophysics Data System (ADS)

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.

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

2010-05-01

355

Single crystal growth and physical properties of YbPd2Si2  

NASA Astrophysics Data System (ADS)

We report the heat capacity and magnetic properties of single crystals of YbPd2Si2 grown from Sn flux. YbPd2Si2 is a non magnetic heavy fermion compound with electronic specific heat coefficient ? = 95 mJ/mol K2 and Pauli paramagnetic susceptibility ?0 = 0.0115 emu/mol. The density of states of single crystal YbPd2Si2 is approximately half that of polycrystalline YbPd2Si2 while the strength of the Kondo effect in the single crystal is approximately twice that of poly crystal.

Matsumoto, Y.; Hanya, K.; Haga, Y.; Fisk, Z.; Ohara, S.

2015-03-01

356

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

NASA Astrophysics Data System (ADS)

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).

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

2014-09-01

357

Dielectric properties of Yb3+ and Nb5+ doped RbTiOPO4 single crystals  

NASA Astrophysics Data System (ADS)

The influence of niobium and ytterbium doping in the electrical properties of the RbTiOPO4 (RTP) crystals has been analyzed along the three crystallographic axes. While Yb3+ does not change the ionic conductivity of RTP, Nb5+ increases it considerably. These effects are also observed for the activation energies of these samples doped with Yb3+ and Nb5+, and different relaxation mechanisms have been observed for the different dopants. RTP and Nb:RTP sample show a non-Debye relaxation mechanism, while Yb:RTP and Nb,Yb:RTP samples show a Debye relaxation mechanism.

Gavald, Jna.; Carvajal, J. J.; Mateos, X.; Aguil, M.; Daz, F.

2012-02-01

358

Yb-based heavy fermion compounds and field tuned quantum chemistry  

SciTech Connect

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.

Mun, Eundeok

2010-07-23

359

Energy transfer processes and heat generation in Yb3+-doped phosphate glasses  

NASA Astrophysics Data System (ADS)

In this work we present a study of energy transfer processes in Yb3+-doped phosphate glasses with different OH- contents and Yb3+ concentrations. Fluorescence and thermal lens (TL) techniques were used in order to analyze the Yb3+-OH- and Yb3+-other impurity interactions. The role of OH- groups is also presented and discussed. The results show that in the low concentration region up to 31020Ybions/cm3, the interaction between Yb3+ and OH radicals is the dominant process reducing the lifetime, increasing the TL dioptric power, and then endangering the performance of the system. For the high Yb3+ concentration limit, the Yb3+-other impurity interaction, which is favored by energy migration, is comparable to the Yb3+-OH- energy transfer, even for high OH- concentration. The nonradiative decay rate due to hydroxyl groups follows Frster-Dexter theory [Ann. Phys. 2, 55 (1948); J. Chem. Phys. 21, 836 (1953)] except at low Yb3+ concentration, being more active at low OH- levels, where quenching rate is probably due to several impurities.

Jacinto, C.; Oliveira, S. L.; Nunes, L. A. O.; Catunda, T.; Bell, M. J. V.

2006-12-01

360

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

SciTech Connect

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.

Citron, Robert; Kropf, A.J.

2008-01-01

361

Fluorescence dynamics and rate equation analysis in Er3+ and Yb3+ doped double tungstates  

Microsoft Academic Search

The fluorescence dynamics in Er3+ and Yb3+ doped KGd(WO4)2 and KY(WO4)2 has been investigated. Lifetimes have been measured for the Yb (2F5\\/2), Er (4I13\\/2), and Er (4S3\\/2) levels around 1, 1.5, and 0.55 mum, respectively. The Yb (2F5\\/2) lifetimes show a decreasing trend toward the limiting Er (4I11\\/2) lifetime with increasing Er-to-Yb concentration ratio, whereas the Er (4I13\\/2) lifetimes are

Stefan Bjurshagen; Jonas E. Hellstrm; Valdas Pasiskevicius; Maria Cinta Pujol; Magdalena Aguil; Francesc Daz

2006-01-01

362

Evolution of the decay modes of 158Yb with spin  

Microsoft Academic Search

The decay of the entry states in 158Yb populated in the reactions of 149 MeV 20Ne with 144,146Nd has been investigated with the Spin Spectrometer gated by a Ge counter. The average excitation energy, the gamma-ray spectra and the angular distributions as a function of multiplicity suggest a region of non-collective behavior at low spin. At higher spin collective characteristics

M. Jskelinen; D. G. Sarantites; F. A. Dilmanian; R. Woodward; H. Puchta; J. R. Beene; J. Hattula; M. L. Halbert; D. C. Hensley

1982-01-01

363

Soliton mode-locked Er:Yb:glass laser.  

PubMed

We report on a simple diode-pumped passively mode-locked Er:Yb:glass laser generating transform-limited 1536-nm solitons of 255-fs duration with a repetition rate of 50 MHz and average power of 58 mW. We also discuss timing jitter and the trade-off between short pulses and high output power in these lasers. PMID:15751879

Sphler, G J; Krainer, L; Innerhofer, E; Paschotta, R; Weingarten, K J; Keller, U

2005-02-01

364

Efficient lasing in Yb:(YLa)2O3 ceramics  

NASA Astrophysics Data System (ADS)

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%.

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

2015-02-01

365

Follow-up Photometry of iPTF14yb  

NASA Astrophysics Data System (ADS)

We observed the field around the GRB afterglow candidate iPTF14yb (Cenko et al. ATel #5924) with the DIAFI instrument mounted on the 2.7 m Harlan J. Smith Telescope at McDonald Observatory, Texas. A series of CCD frames using Sloan-g and Sloan-r filters were collected on Feb.27 08:25 UT. The transient has been successfully detected on all frames.

Vinko, J.; Silverman, J. M.; Pooley, D.; Szalai, T.; Robinson, E. L.; Wheeler, J. C.

2014-02-01

366

Bright white light through up-conversion of a single NIR source from sol-gel-derived thin film made with Ln3+-doped LaF3 nanoparticles.  

PubMed

White light was generated from a single silica thin film made with Yb0.75La0.2Eu0.05F3, La0.45Yb0.5Er0.05F3, and La0.75Yb0.2Tm0.05F3 nanoparticles by exciting with a single source near-infrared light (980 nm CW diode laser). Eu3+ and Tm3+ ions are responsible for red and blue emission, respectively. Er3+ ion is responsible for green as well as red emission. The Commission Internationale de l'Eclairage (CIE) coordinates of the resulting light were easily adjusted by controlling the concentration of Ln3+ (Eu3+, Er3+, Tm3+) ions in the nanoparticles as well as the concentration of Ln3+-doped nanoparticles in the sol-gel thin layer. PMID:16144374

Sivakumar, Sri; van Veggel, Frank C J M; Raudsepp, Mati

2005-09-14

367

Mechanism of tantalum adhesion on SiLK{sup TM}  

SciTech Connect

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.

Hu Yue; Yang Shuowang; Chen Xiantong; Lu Dong; Feng Yuanping; Wu Ping [Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117542 (Singapore); Institute of High Performance Computing, 1 Science Park Road, Singapore 117528 (Singapore); Institute of Microelectronics, 11 Science Park Road, Singapore 117685 (Singapore); Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117542 (Singapore); Institute of High Performance Computing, 1 Science Park Road, Singapore 117528 (Singapore)

2005-09-19

368

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

ERIC Educational Resources Information Center

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

Molnar, Bill

369

Tb3+-Yb3+ cooperative down and up conversion processes in Tb0.81Ca0.19F2.81:Yb3+ single crystals  

NASA Astrophysics Data System (ADS)

The energy transfer processes between Tb3+ and Yb3+ ions are studied in Tb-based fluoride single crystals. These are very transparent from the UV to the IR wavelength regions, except for the characteristic absorption lines of the rare-earth ions under study. In contrast with previously reported Tb3+-doped glasses and oxide powders, these crystals containing a high Tb3+ concentration present two major advantages for the study of the energy transfer processes in the Tb3+-Yb3+ ion pair. Firstly, the adverse influence of host defects is minimized with the use of high quality crystals. Secondly, the high Tb3+ concentration guarantees a much higher absorption cross-section of UV light, and consequently these crystals have real potential for practical applications. Photoluminescence spectra in the visible-IR wavelength region demonstrate the existence of efficient down and up conversion processes by crossed excitation and emission characteristics of Tb3+ and Yb3+ ions. In the down conversion process, Tb3+(5D4) ? 2Yb3+(2F5/2), two IR photons are emitted for each Tb3+ ion deexcited by second-order energy transfer to two Yb3+ ions. The total quantum efficiency of the down conversion process in the fluoride system is shown to increase linearly with the Yb3+ concentration, reaching its maximum at the Yb3+ solubility limit in the fluoride host. Further, efficient up conversion by two- and three-IR photon absorption is observed.

Molina, P.; Vasyliev, V.; Vllora, E. G.; Shimamura, K.

2011-12-01

370

Elevated serum dehydroepiandrosterone sulfate levels in practitioners of the Transcendental Meditation (TM) and TM-Sidhi programs  

Microsoft Academic Search

Serum dehydroepiandosterone sulfate (DHEA-S) levels were measured in 270 men and 153 women who were experienced practitioners of the Transcendental Meditation (TM) and TM-Sidhi programs, mental techniques practiced twice daily, sitting quietly with the eyes closed. These were compared according to sex and 5-year age grouping to 799 male and 453 female nonmeditators. The mean DHEA-S levels in the TM

Jay L. Glaser; Joel L. Brind; Joseph H. Vogelman; Michael J. Eisner; Michael C. Dillbeck; R. Keith Wallace; Deepak Chopra; Norman Orentreich

1992-01-01

371

Quasiparticle alignment effects in rotational bands of sup 159 Yb  

SciTech Connect

High-spin states in the transitional nucleus {sup 159}Yb were measured by means of heavy-ion induced reactions. The three reactions used were {sup 116}Cd({sup 48}Ti,5n){sup 159}Yb at 220 MeV, {sup 98}Mo({sup 64}Ni,3n){sup 159}Yb at 265 MeV, and {sup 147}Sm({sup 16}O,4n){sup 159}Yb at 90 MeV. The first two measurements were performed at the Holifield Heavy Ion Research Facility at Oak Ridge National Laboratory, using the Spin Spectrometer multi-detector array. The third reaction was performed at the McMaster University Tandem Accelerator Laboratory. The previously known i{sub 13/2} rotational band (Trautmann et al. 1975) has been extended up to 61/2 {Dirac h}, and possibly 69/2 {Dirac h}. Three new side bands have been established with spins and parities determined. All of the bands (structures) have been assigned intrinsic i{sub 13/2} and h{sub 9/2} neutron configurations. A systematic analysis of the neighboring transitional nuclei has been performed. The properties of these nuclei were compared at the 4-6 quasiparticle level, in order to learn about the shape-driving effects of quasiparticles at higher rotational frequencies. By contrast, earlier comparisons were done only at the 1-4 quasiparticle, level and at moderate rotational frequencies. Band crossings due to the rotational alignment of the secondary {nu}i{sub 13/2} pair and the primary {pi}h{sub 11/2} pair are seen in {sup 159}Yb. The primary neutron i{sub 13/2} crossing is not observed until after it has been completed. The crossing due to the secondary neutron pair and the proton pair are seen to be degenerate in the {nu}i{sub 13/2} band. In addition, a deficiency is observed in the alignment gain due to these two crossings. In order to understand these two features, Cranked Shell Model calculations and equilibrium shape calculations have been performed.

Courtney, L.H.

1988-01-01

372

75 FR 56140 - Comment Request for Information Collection for the YouthBuild (YB) Reporting System (OMB Control...  

Federal Register 2010, 2011, 2012, 2013, 2014

...Collection for the YouthBuild (YB) Reporting System (OMB Control No. 1205-0464), Extension...provided in the desired format, reporting burden (time and financial...collection of data about the YB Reporting System which expires on...

2010-09-15

373

Luminescence Properties of Yb-2,4-Dimethoxyhematoporphyrin IX, a Promising Compound for Diagnosis of Malignant Tumors  

NASA Astrophysics Data System (ADS)

The measured quantum yield of Yb-2,4-dimethoxyhematoporphyrin (Yb-DMHP) in DMSO was 0.8%. It was found that molecular oxygen did not quench luminescence of the metal ion in Yb-DMHP, which was a diagnostic advantage while using this complex in practice. The kinetic characteristics of IR luminescence of the Yb porphyrin complex in DMSO/H2O mixtures were measured. The average lifetime of Yb3+ (2F5/2) in DMSO was 9.7 ?s, which was an order of magnitude greater than that of the auto-fluorescence of biological tissues. Water molecules quenched effectively IR luminescence of Yb-DMHP. The integrated luminescence intensity of Yb3+ (2F5/2) depended non-linearly on the fraction of H2O in the DMSO/H2O mixtures. This was indicative of a complex quenching mechanism of Yb luminescence by surrounding molecules.

Stasheuski, A. S.; Knyukshto, V. N.; Ivanov, A. V.; Rumyantseva, V. D.; Shilov, I. P.; Galievsky, V. A.; Dzhagarov, B. M.

2015-01-01

374

Prognostic association of YB-1 expression in breast cancers: a matter of antibody.  

PubMed

The literature concerning the subcellular location of Y-box binding protein 1 (YB-1), its abundance in normal and cancer tissues, and its prognostic significance is replete with inconsistencies. An explanation for this could be due in part to the use of different antibodies in immunohistochemical and immunofluorescent labeling of cells and tissues. The inconsistencies could also be due to poor resolution of immunohistochemical data. We analyzed two cohorts of breast tumours for both abundance and subcellular location of YB-1 using three different antibodies; two targeting N-terminal epitopes (AB-a and AB-b) and another (AB-c) targeting a C-terminal epitope. We also investigated stress-induced nuclear translocation of YB-1 in cell culture. We report that both AB-a and AB-c detected increased YB-1 in the cytoplasm of high-grade breast cancers, and in those lacking estrogen and progesterone receptors; however the amount of YB-1 detected by AB-a in these cancers is significantly greater than that detected by AB-c. We confirm our previously published findings that AB-b is also detecting hnRNP A1, and cannot therefore be used to reliably detect YB-1 by immunohistochemistry. We also report that AB-a detected nuclear YB-1 in some tumour tissues and stress treated cells, whereas AB-c did not. To understand this, cancer cell lines were analyzed using native gel electrophoresis, which revealed that the antibodies detect different complexes in which YB-1 is a component. Our data suggest that different YB-1 antibodies show different staining patterns that are determined by the accessibility of epitopes, and this depends on the nature of the YB-1 complexes. It is important therefore to standardize the protocols if YB-1 is to be used reproducibly as a prognostic guide for different cancers. PMID:21695211

Woolley, Adele G; Algie, Michael; Samuel, Weini; Harfoot, Rhodri; Wiles, Anna; Hung, Noelyn A; Tan, Puay-Hoon; Hains, Peter; Valova, Valentina A; Huschtscha, Lily; Royds, Janice A; Perez, David; Yoon, Han-Seung; Cohen, Scott B; Robinson, Phillip J; Bay, Boon-Huat; Lasham, Annette; Braithwaite, Antony W

2011-01-01

375

Structural organization of mRNA complexes with major core mRNP protein YB-1.  

PubMed

YB-1 is a universal major protein of cytoplasmic mRNPs, a member of the family of multifunctional cold shock domain proteins (CSD proteins). Depending on its amount on mRNA, YB-1 stimulates or inhibits mRNA translation. In this study, we have analyzed complexes formed in vitro at various YB-1 to mRNA ratios, including those typical for polysomal (translatable) and free (untranslatable) mRNPs. We have shown that at mRNA saturation with YB-1, this protein alone is sufficient to form mRNPs with the protein/RNA ratio and the sedimentation coefficient typical for natural mRNPs. These complexes are dynamic structures in which the protein can easily migrate from one mRNA molecule to another. Biochemical studies combined with atomic force microscopy and electron microscopy showed that mRNA-YB-1 complexes with a low YB-1/mRNA ratio typical for polysomal mRNPs are incompact; there, YB-1 binds to mRNA as a monomer with its both RNA-binding domains. At a high YB-1/mRNA ratio typical for untranslatable mRNPs, mRNA-bound YB-1 forms multimeric protein complexes where YB-1 binds to mRNA predominantly with its N-terminal part. A multimeric YB-1 comprises about twenty monomeric subunits; its molecular mass is about 700 kDa, and it packs a 600-700 nt mRNA segment on its surface. PMID:15494450

Skabkin, Maxim A; Kiselyova, Olga I; Chernov, Konstantin G; Sorokin, Alexey V; Dubrovin, Evgeniy V; Yaminsky, Igor V; Vasiliev, Victor D; Ovchinnikov, Lev P

2004-01-01

376

High-gain amplification in Yb:CaF2 crystals pumped by a high-brightness Yb-doped 976 nm fiber laser  

NASA Astrophysics Data System (ADS)

We report on high single-pass gain in Yb:CaF2 crystal longitudinally pumped with a 40 W high-brightness fiber laser source based on an ytterbium-doped ultra-large core photonic crystal rod-type fiber operating at 976 nm. A single-pass small-signal gain of 3.2 has been achieved in a 6 % Yb-doped 10-mm-long CaF2 crystal at room temperature, outperforming any CW-diode-pumped scheme and paving the way towards very promising innovative lasers and amplifiers schemes merging the Yb-doped solid-state and fiber technologies.

Machinet, G.; Andriukaitis, G.; Svillano, P.; Lhermite, J.; Descamps, D.; Puglys, A.; Baltuka, A.; Cormier, E.

2013-05-01

377

Ferromagnetic behavior in mixed valence europium (Eu2+/Eu3+) oxide EuTi1-xMxO3 (M = Al3+ and Ga3+)  

NASA Astrophysics Data System (ADS)

We have investigated the Ti-site substitution effect on the magnetic properties of antiferromagnetic insulator EuTiO3 with a Nel temperature of 5 K. Partial substitution of Ti4+ with heterovalent Al3+ or Ga3+ turns the corresponding amount of magnetic Eu2+ into non-magnetic Eu3+. Both EuTi1-xAlxO3 (0.05 ? x ? 0.10) and EuTi1-xGaxO3 (0.05 ? x ? 0.10) exhibit ferromagnetic (FM) insulating behavior below 4 K. The Eu2+/Eu3+ mixed valence state probably contributes to the emergence of the FM behavior. Fine control of the magneto-electric (ME) phases of EuTi1-xAlxO3 and EuTi1-xGaxO3 would lead to intriguing ME phenomena such as giant ME effect.

Akahoshi, Daisuke; Horie, Hiroki; Sakai, Shingo; Saito, Toshiaki

2013-10-01

378

TM digital image products for applications  

NASA Technical Reports Server (NTRS)

LANDSAT-4 TM images recorded on computer compatible tapes (CCTs) are currently available in the following tape formats: (1) raw rectified data (CCT-BT); (2) calibrated data (CCT-AT); and (3) geometrically corrected data (CCT-PT). These formats represent different steps in the process of producing fully-corrected TM data. The CCT-BT images are rectified from telemetry format to image format, but are uncorrected radiometrically and geometrically; they are generally used for internal transportation of data from one ground processing system to another. The CCT-AT images have had data from faulty channels replaced and all data radiometrically calibrated to produce an archive image; they are available to researches for radiometric characterization. The final products, the CCT-PT images, have been resampled by cubic convolution procedures to provide a geometrically corrected image using satellite ephemeris data. The CCT-PT image is the one to which all of the various radiometric and geometric corrections have been applied; this is the product that is the product that is available to all users.

Barker, J. L.; Gunther, F. J.; Abrams, R. B.; Ball, D. L.

1985-01-01

379

TM Digital Image Products for Applications  

NASA Technical Reports Server (NTRS)

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.

Barker, J. L.; Gunther, F. J.; Abrams, R. B.; Ball, D. L.

1984-01-01

380

Laser operation of Yb3+ in the acentric RbTiOPO4 crystal codoped with Nb5+  

Microsoft Academic Search

The new bifunctional crystal, Yb-doped RbTiOPO4 or Yb:RTP, codoped with Nb for charge compensation, combines the lasing properties of the Yb-ion with the nonlinear properties of the well-known orthorhombic crystal RTP. It is interesting for the development of compact all-solid-state laser sources in the green, by self-frequency doubling. The extremely broad tunability achieved with Yb:Nb:RTP is also promising for mode-locking

X. Mateos; A. Pea; M. Aguilo; F. Diaz; V. Petrov; P. Segonds; B. Boulanger

2007-01-01

381

A historical perspective on developing foundations iInfo(TM) information systems: iConsult(TM) and iEntertain(TM) apps using iDescribers(TM) information integration for iOrgs(TM) information systems  

Microsoft Academic Search

Technology now at hand can integrate all kinds of digital information for individuals, groups, and organizations so their information usefully links together. iInfo(TM) information integration works by making connections including examples like the following: - A statistical connection between \\

Carl Hewitt

2009-01-01

382

77 FR 40364 - Announcement of Requirements and Registration for Million Hearts TM  

Federal Register 2010, 2011, 2012, 2013, 2014

...of Requirements and Registration for Million Hearts TM Caregiver Video Challenge AGENCY: Centers...Human Services, in partnership with Million Hearts TM announces the launch of The Million Hearts TM Caregiver Video Challenge. We invite...

2012-07-09

383

Anomalous Eu valence state and superconductivity in undoped Eu3Bi2S4F4.  

PubMed

We have synthesized a novel europium bismuth sulfofluoride, Eu3Bi2S4F4, by solid-state reactions in sealed evacuated quartz ampules. The compound crystallizes in a tetragonal lattice (space group I4/mmm, a = 4.0771(1) , c = 32.4330(6) , and Z = 2), in which CaF2-type Eu3F4 layers and NaCl-like BiS2 bilayers stack alternately along the crystallographic c axis. There are two crystallographically distinct Eu sites, Eu(1) and Eu(2) at the Wyckoff positions 4e and 2a, respectively. Our bond valence sum calculation, based on the refined structural data, indicates that Eu(1) is essentially divalent, while Eu(2) has an average valence of ??+2.64(5). This anomalous Eu valence state is further confirmed and supported, respectively, by Mssbauer and magnetization measurements. The Eu(3+) components donate electrons into the conduction bands that are mainly composed of Bi 6px and 6py states. Consequently, the material itself shows metallic conduction and superconducts at 1.5 K without extrinsic chemical doping. PMID:25314008

Zhai, Hui-Fei; Zhang, Pan; Wu, Si-Qi; He, Chao-Yang; Tang, Zhang-Tu; Jiang, Hao; Sun, Yun-Lei; Bao, Jin-Ke; Nowik, Israel; Felner, Israel; Zeng, Yue-Wu; Li, Yu-Ke; Xu, Xiao-Feng; Tao, Qian; Xu, Zhu-An; Cao, Guang-Han

2014-10-29

384

ORNL/TM-2007/224 BIOFUEL FEEDSTOCK ASSESSMENT FOR  

E-print Network

ORNL/TM-2007/224 BIOFUEL FEEDSTOCK ASSESSMENT FOR SELECTED COUNTRIES Keith L. Kline Gbadebo A Government or any agency thereof. #12;ORNL/TM-2007/224 BIOFUEL FEEDSTOCK ASSESSMENT FOR SELECTED COUNTRIES To Support the DOE study of Worldwide Potential to Produce Biofuels with a focus on U.S. Imports Keith L

Pennycook, Steve

385

Relative radiometric calibration of LANDSAT TM reflective bands  

NASA Technical Reports Server (NTRS)

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.

Barker, J. L.

1984-01-01

386

Full Immersive Virtual Environment Cave[TM] in Chemistry Education  

ERIC Educational Resources Information Center

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

Limniou, M.; Roberts, D.; Papadopoulos, N.

2008-01-01

387

Disability Awareness Night[TM]: 2006 Honorees, Sponsors, Teams  

ERIC Educational Resources Information Center

This article presents the 2006 honorees, sponsors, and teams for the Disability Awareness Night[TM]. Disability Awareness Night[TM] is a unique and powerful community outreach program. Its vision is to continue to raise awareness outside of the community of individuals with disabilities to continue the goal that this program will open doors to

Exceptional Parent, 2006

2006-01-01

388

Accelerated Math[TM]. What Works Clearinghouse Intervention Report  

ERIC Educational Resources Information Center

"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

What Works Clearinghouse, 2011

2011-01-01

389

ISI TechnicalManual ISI/TM-88-197  

E-print Network

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

Robins, Gabriel

390

Live, Learn, and Thrive TM Shanna Ivey, PhD  

E-print Network

Live, Learn, and Thrive TM Shanna Ivey, PhD College of Agricultural, Consumer and Environmental. To pro- vide a global assay of the metabolic flux in algae, CO2/O2 flux, electron flux, growth rates Research Laboratory Dr. Peter Lammers, (575) 646-7458, plammers@nmsu.edu Live, Learn, and Thrive TM NEW

Johnson, Eric E.

391

Inside Linden Lab: Second Life [TM] for Educators  

ERIC Educational Resources Information Center

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

Atkinson, Tom

2008-01-01

392

Social Stories[TM]: A Possible Theoretical Rationale  

ERIC Educational Resources Information Center

Social Stories[TM] are an intervention widely used with individuals with autism spectrum disorders (ASD). This paper discusses a possible theoretical rationale that might account for the purported efficacy of Social Stories[TM]. Attributes of individuals with ASD in relation to Social Story intervention including difficulties with theory of mind

Reynhout, Georgina; Carter, Mark

2011-01-01

393

Accelerated Reader[TM]. What Works Clearinghouse Intervention Report  

ERIC Educational Resources Information Center

"Accelerated Reader"[TM] is a guided reading intervention used to supplement regular reading instruction in K-12 classrooms. Its aim is to improve students' reading skills through reading practice and quizzes on the books students read. The "Accelerated Reader"[TM] program calls for students to select and read a book and then take a computerized

What Works Clearinghouse, 2010

2010-01-01

394

Social Stories[TM] for Children with Disabilities  

ERIC Educational Resources Information Center

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

Reynhout, Georgina; Carter, Mark

2006-01-01

395

Utilising eduroam[TM] Architecture in Building Wireless Community Networks  

ERIC Educational Resources Information Center

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

Huhtanen, Karri; Vatiainen, Heikki; Keski-Kasari, Sami; Harju, Jarmo

2008-01-01

396

Accelerated Math[TM]. What Works Clearinghouse Intervention Report  

ERIC Educational Resources Information Center

"Accelerated Math"[TM], published by Renaissance Learning, is a software tool used to customize assignments and monitor progress in mathematics for students in grades 1-12. "Accelerated Math"[TM] creates individualized assignments that align with state standards and national guidelines, scores student work, and generates formative feedback through

What Works Clearinghouse, 2010

2010-01-01

397

SpellRead[TM]. What Works Clearinghouse Intervention Report  

ERIC Educational Resources Information Center

"SpellRead"[TM], formerly known as "SpellRead Phonological Auditory Training"[R], is a small-group literacy program for struggling readers in grades 2-12. "SpellRead"[TM] integrates the auditory and visual aspects of the reading process and emphasizes specific skill mastery through systematic and explicit instruction. Students are taught to

What Works Clearinghouse, 2013

2013-01-01

398

Production of a highly enriched Yb isotope in weight amounts by the atomic-vapour laser isotope separation method  

Microsoft Academic Search

The production of a highly enriched Yb isotope in weight amounts by the atomic-vapour laser isotope separation method is reported. The content of Yb achieved in the experimental samples of the enriched material was 99%. For a commercial production of about 20 mg h, the concentration of this isotope is about 88% with about 5% of the 'harmful' isotope Yb.

O I Andreev; V I Derzhiev; V M Dyakin; A G Egorov; L A Mikhaltsov; V A Tarasov; A I Tolkachev; Yu G Toporov; S A Chaushanskii; Sergei I Yakovlenko

2006-01-01

399

Efficient laser operation of an Yb:S-FAP crystal Sylvie Yiou, Franc ois Balembois, Kathleen Schaffers, and Patrick Georges  

E-print Network

quality for the pumping of erbium- doped fiber amplifiers. Several ways have already been successfully around 985 nm is to use ytterbium-doped Yb-doped materials. De- pending on the host material, the Yb than the transition around 980 nm and is to be suppressed. Efficient operation of a Yb-doped silica-fiber

Boyer, Edmond

400

Magic mode switching in Yb:CaGdAlO4 laser under high pump power  

E-print Network

to be problematic in Yb:CALGO. Nevertheless, the analysis of the thermal lens in CALGO has never been carried out by the particular spectroscopic and thermal properties of Yb:CALGO crystal. This atypical and unexpected behavior bandwidth and good thermal prop- erties, it permits us to demonstrate ultra-short pulses [1,2] and high

401

An extended cavity diode-pumped femtosecond Yb:KGW laser for applications in optical DNA  

E-print Network

, and J. G. Fujimoto, "Cavity-dumped femtosecond Kerr-lens mode- locked Ti:A12O3 laser," Opt. Lett. 18. Fallnich, "High-peak- power pulses from a cavity-dumped Yb:KY(WO4)2 oscillator," Opt. Lett. 30, 1891An extended cavity diode-pumped femtosecond Yb:KGW laser for applications in optical DNA sensor

Major, Arkady

402

Spectrum-, pulsewidth-, and wavelength-switchable all-fiber mode-locked Yb laser with  

E-print Network

Spectrum-, pulsewidth-, and wavelength- switchable all-fiber mode-locked Yb laser with fiber based and wavelength of the output from an all-fiber Yb laser mode-locked by carbon nanotubes. It is shown that a segment of polarization maintaining (PM) fiber inserted into a standard single mode fiber based laser

Turitsyn, Sergei K.

403

Theory of the thermoelectricity of intermetallic compounds with Ce or Yb ions and R. Monnier2  

E-print Network

Theory of the thermoelectricity of intermetallic compounds with Ce or Yb ions V. Zlati1 and R received 19 January 2005; published 14 April 2005 The thermoelectric properties of intermetallic compounds and Yb intermetallics. Calculating the effect of pressure on various characteristic energy scales

Freericks, Jim

404

Influence of Yb3+ concentration on upconversion luminescence of Ho3+  

E-print Network

Influence of Yb3+ concentration on upconversion luminescence of Ho3+ Ying Yua, , Yangdong Zhenga ceramics under infrared (IR) excitation at 976 nm. The intensity of the UC luminescence centered at 554 the UC luminescence centered at 392, 428 and 667 nm increased with Yb3+ concentration from 2 to 11 mol

Cao, Wenwu

405

Line competition in an intracavity diode-pumped Yb:KYW laser operating at 981 nm  

E-print Network

Optical Society of America OCIS codes: 140.3480, 140.3580, 140.3430, 140.3615, 140.3530. 1. INTRODUCTION to their wide range of ap- plications. Moreover, the possibility of second harmonic generation (SHG) for a blue wavelength and more widely used are the ytterbium-doped tungstate crystals family, such as Yb : KYWO42 (Yb

Paris-Sud XI, Universit de

406

Modeling of quasi-three-level lasers and operation of cw Yb:YAG lasers  

E-print Network

Modeling of quasi-three-level lasers and operation of cw Yb:YAG lasers Takunori Taira, William M. Tulloch, and Robert L. Byer We present modeling studies of quasi-three-level laser oscillators, the validity of which was revealed by Ti:Al2O3-pumped Yb:YAG laser experiments, and these results are shown

Byer, Robert L.

407

Relativistic effects in E1 transition oscillator strengths along the Yb+ isoelectronic sequence  

NASA Astrophysics Data System (ADS)

Electric dipole transition oscillator strengths have been computed for low-lying transitions in the Yb+ isoelectronic sequence (through Ra19 +) in fully relativistic and non-relativistic-limit approximations. Relativistic effects were carefully investigated and efforts were undertaken to establish systematic trends in relativistic contributions to oscillator strengths along the Yb+ isoelectronic sequence.

Migdalek, J.; Siegel, W.

2014-04-01

408

Luminescence in Li? Al ? (PO?)? :Eu(2+).  

PubMed

A series of efficient Li? Al ? (PO?)? :Eu(2+) novel phosphors were synthesized by the facile combustion method. The effects of dopant on the luminescence behavior of Li? Al ? (PO?)? phosphor were also investigated. The phosphors were characterized by X-ray diffraction, field emission scanning electron microscope and photoluminescence techniques. The result shows that all samples can be excited efficiently by near-ultraviolet excitation under 310?nm. The emission was observed for Li? Al ? (PO?)? :Eu(2+) phosphor at 425?nm, which corresponded to the d ? f transition. The concentration quenching of Eu(2+) was observed in Li? Al ? (PO?)? :Eu(2+) when the Eu concentration was at 0.5?mol%. The prepared powders exhibited intense blue emission at the 425?nm owing to the Eu(2+) ion by Hg-free excitation at 310?nm (i.e., solid-state lighting excitation). Consequently, the availability of such a phosphor will significantly help in the development of blue-emitting solid-state lighting applications. PMID:23019178

Shinde, K N; Park, K

2013-01-01

409

EurActiv: EU News and Policy Positions  

NSDL National Science Digital Library

This site is an independent media portal fully dedicated to European Union (EU) affairs. This extensive site is an online platform for EU policies, complementing existing EU media and institutional websites. The site's coverage of EU affairs concentrates on policy positions by EU members, focusing on the policy debates that occur before decisions are made. The website covers many topics such as energy, environmental issues, science and research and sustainable development.

EurActiv

410

High-energy diode-pumped D2O-cooled multislab Yb:YAG and Yb:QX-glass lasers.  

PubMed

We investigated the lasing performance of a multislab Yb:QX and Yb:YAG laser amplifiers using a facet-cooled design. Di-deuterium oxide (D2O) was used as the coolant flowing between the active slabs with the pump and laser light passing through the very low absorbing heavy-water films. A square pump profile at a maximum intensity of 40??kW/cm2 drove the amplifier with a peak fluence of 5.5??J/cm2 and a pulse duration of 6 ns. We demonstrated a maximum pulse energy of 1 J for each gain medium as well as a repetition rate of 10 Hz for Yb:YAG and 1 Hz for Yb:QX glass, thus showing the feasibility and scalability of directly water-cooled, diode-pumped, high-energy short-pulse lasers. PMID:24978549

Siebold, Mathias; Loeser, Markus; Harzendorf, Gunter; Nehring, Harald; Tsybin, Igor; Roeser, Fabian; Albach, Daniel; Schramm, Ulrich

2014-06-15

411

Yb band parasitic lasing suppression in Er/Yb-co-doped pulsed fiber amplifier based on all-solid photonic bandgap fiber  

NASA Astrophysics Data System (ADS)

A novel kind of all-solid photonic bandgap fiber (AS-PBGF) has been used in the master oscillator power amplifier structured Er/Yb-co-doped pulsed fiber amplifier to suppress the Yb band parasitic lasing for the power scaling and safety operation. To the best of our knowledge, this is the first time to report the use of AS-PBGF to suppress the Yb band parasitic lasing. The experimental results show that the Yb band parasitic lasing has been suppressed efficiently and the amplifier power has been raised dramatically with the utilization of AS-PBGF. An output power of 2.66 W was finally obtained without any unwanted parasitic lasing.

Ouyang, Deqin; Guo, Chunyu; Ruan, Shuangchen; Yan, Peiguang; Wei, Huifeng; Luo, Jie

2014-03-01

412

EPR, ENDOR and optical spectroscopy of Yb3+ ion in KZnF3 single crystals  

NASA Astrophysics Data System (ADS)

The paramagnetic center of tetragonal symmetry formed by the Yb3+ ion in the KZnF3 crystal has been studied using methods of EPR, ENDOR and optical spectroscopy. The location of the impurity ion and the structural model of the complex differing from the model of the Yb3+ center in KMgF3 have been established. The empirical scheme of the energy levels of the Yb3+ ion has been found. The parameters of its interaction with the crystal electrostatic field and the hyperfine interaction with ligands of the nearest environment have been determined. The parameters of the crystal field were used for the analysis of the distortions of the crystal lattice in the vicinity of Yb3+. The parameters of the transferred hyperfine interaction have been calculated for the distances between Yb3+ and F- ions of the nearest environment obtained taking into account the found distortions. They are in good agreement with the experimental values.

Falin, M. L.; Gerasimov, K. I.; Latypov, V. A.; Leushin, A. M.; Schweizer, S.; Spaeth, J.-M.

2015-02-01

413

Visible emission of Tb 3+-Yb 3+ co-doped fluorophosphate glasses  

NASA Astrophysics Data System (ADS)

Visible lasers and amplifiers have potential applications in the fields of optical data storage, spectroscopy, biomedical and optical local area networks. In this study, Tb 3+-Yb 3+ co-doped fluorophosphate glasses were synthesized and properties of the visible emission at 0.54 µm were investigated. A upconversion excitation efficiency from Yb 3+ to Tb 3+ was studied by evaluations of a cooperative energy transfer efficiency from Yb 3+ to Tb 3+ (?CET) and a back-transfer efficiency from Tb 3+ to Yb 3+ (?BT ) which give positive and negative contribution to upconversion excitation, respectively. The ?CET was as high as 25 %, and the ?BT was less than 1 % in the fluorophosphate glass. This indicates that Tb 3+-Yb 3+ co-doped fluorophosphate glass is promising as new laser and gain media in the 0.54 ?m band.

Arai, Yusuke; Yamashita, Tatsuya; Horiguchi, Shin; Suzuki, Takenobu; Ohishi, Yasutake

2008-02-01

414

YbCl? electrode in alkaline aqueous electrolyte with high pseudocapacitance.  

PubMed

Inorganic pseudocapacitors often select synthetic solid materials as electrode materials, which show low utilization of pseudocapacitive metal cations. We reported the crystallization transformation of YbCl3 pseudocapacitor electrodes in alkaline electrolytes, which can show high cation utilization ratio. The electrochemical reactive YbOOH colloids were crystallized through the chemical coprecipitation and Faradaic redox reactions. The effect of crystallization kinetics on electrochemical performances of YbCl3 pseudocapacitor was studied. YbCl3 pseudocapacitor can show ultrahigh specific capacitance of 2210 F/g, where the commercial YbCl3 salts were used directly as pseudocapacitor electrodes in an aqueous electrolyte neglecting the complex synthesis procedures. The present strategy provides a novel route to crystallize electrochemical active compounds with unusual reactivity toward Faradaic redox reaction. The development of ion-based pseudocapacitors can advance the understating of the redox mechanism of active cations. PMID:24767502

Chen, Kunfeng; Xue, Dongfeng

2014-06-15

415

In-Situ Growth of Yb2O3 Layer for Sublimation Suppression for Yb14MnSb11 Thermoelectric Material for Space Power Applications  

NASA Technical Reports Server (NTRS)

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.

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

2012-01-01

416

Octave-spanning super-continuum from a silica photonic crystal fiber pumped by a 386 MHz Yb:fiber laser  

E-print Network

, mode-locked all-normal dispersion Yb:fiber laser. The laser achieved 45% optical-to-optical efficiency of highly doped Yb fiber has extended the operation of femtose- cond Yb fiber ring lasers beyondOctave-spanning super-continuum from a silica photonic crystal fiber pumped by a 386 MHz Yb:fiber

417

Optical Lattice Induced Light Shifts in an Yb Atomic Clock  

Microsoft Academic Search

We present an experimental study of the lattice-induced light shifts on the S01-->P03 optical clock transition (nuclock≈518THz) in neutral ytterbium. The ``magic'' frequency numagic for the Yb174 isotope was determined to be 394799475(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 6s6pP03-->6s8pP03, 6s8pP23, and 6s5fF23 two-photon

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

2008-01-01

418

Thin-rod Yb:YAG regenerative laser amplifier  

NASA Astrophysics Data System (ADS)

High-average-power, high-repetition-rates picosecond-pulsed regenerative ytterbium-doped yttrium aluminum garnet (Yb:YAG) laser amplifiers were developed. The architecture used in the amplifiers, which are named as thin-rod, has a unique cooling scheme like slab lasers and also has a unique pumping scheme like photonic crystal fiber lasers, is suitable for high-average power Ytterbium lasers. This architecture also has high gain characteristics which is appropriate for the regenerative spectral and pulse shaping on high-repetition-rate, ultrashort-pulse amplifications.

Maruko, A.; Nishio, M.; Matsubara, S.; Tanaka, M.; Takama, M.; Yoshida, T.; Kyomoto, K.; Okunishi, H.; Kato, K.; Shimabayashi, K.; Morioka, M.; Inayoshi, S.; Yamagata, S.; Kawato, S.

2014-09-01

419

Atomic Mass and Nuclear Binding Energy for Yb-148 (Ytterbium)  

NASA Astrophysics Data System (ADS)

This document is part of the Supplement containing the complete sets of data of Subvolume B `Nuclei with Z = 55 - 100' of Volume 22 `Nuclear Binding Energies and Atomic Masses' of Landolt-Brnstein - Group I `Elementary Particles, Nuclei and Atoms', and additionally including data for nuclei with Z = 101 - 130. It provides atomic mass, mass excess, nuclear binding energy, nucleon separation energies, Q-values, and nucleon residual interaction parameters for atomic nuclei of the isotope Yb-148 (Ytterbium, atomic number Z = 70, mass number A = 148).

Sukhoruchkin, S. I.; Soroko, Z. N.

420

Facebook and its EU users Applicability of the EU data protection law  

E-print Network

Facebook and its EU users ­ Applicability of the EU data protection law to US based SNS* Aleksandra (SNS). The analysis will be conducted on the example of Facebook, which is one of the most popular SNS. The goal of the paper is to examine whether European users of Facebook can rely on their national data

Boyer, Edmond

421

EU Support Application Guidance Funding is available to support EU programmes only.  

E-print Network

EU Support ­ Application Guidance Guidelines · Funding is available to support EU programmes only in mainland Europe to support bid development activity. · Funding is available to support current members of staff. · Funding should only be sought where an alternative source (eg Faculty or Department

Doran, Simon J.

422

Internet: http://ue.eu.int/ E-mail: press.office@consilium.eu.int  

E-print Network

Internet: http://ue.eu.int/ E-mail: press.office@consilium.eu.int For further information call 32 2 marks. The documents whose references are given in the text are available on the Council's Internet Internet site or may be obtained from the Press Office. #12;PROVISIONAL VERSION 11.III.2004 6648/04 (Presse

423

Internet: http://ue.eu.int/ E-mail: press.office@consilium.eu.int  

E-print Network

Internet: http://ue.eu.int/ E-mail: press.office@consilium.eu.int For further information call 32 2. The documents whose references are given in the text are available on the Council's Internet site http by an asterisk; these statements are available on the above mentioned Council Internet site or may be #12;22.IX

424

Internet: http://ue.eu.int/ E-mail: press.office@consilium.eu.int  

E-print Network

Internet: http://ue.eu.int/ E-mail: press.office@consilium.eu.int For further information call 32 2. A The documents whose references are given in the text are available on the Council's Internet site http by an asterisk; these statements are available on the above mentioned Council Internet site or may be obtained

425

Internet: http://ue.eu.int/Newsroom E-mail: press.office@consilium.eu.int  

E-print Network

Internet: http://ue.eu.int/Newsroom E-mail: press.office@consilium.eu.int PRE 052/04 (Presse) EN of the European Union (COMPETITIVENESS - Internal market, Industry and Research) will take place on 24 September and competitiveness = Information from the Presidency - Industrial policy and structural change Commission

426

Identification of the tropomyosin (HL-Tm) in Haemaphysalis longicornis.  

PubMed

Haemaphysalis longicornis tropomyosin (HL-Tm) was amplified by RT-PCR. The cDNA contained a 825 bp open reading frame coding for 274 amino acids with a predicted theoretical isoelectric point (pI) of 4.55 and molecular weight of 31.7 kDa. Real-time RT-PCR analysis showed that the expression levels of the HL-Tm in the unfed-females were significantly higher than in other tested developmental stages (eggs, unfed-larvae and unfed-nymphs). Western blot analysis showed that rabbit anti-serum against H. longicornis unfed-adult ticks recognized the recombinant HL-Tm protein (rHL-Tm). Immunization of rabbits with the rHL-Tm resulted in a statistically significant reduction of female engorgement and oviposition. Silencing of HL-Tm by RNAi showed a decrease in tick engorgement and oviposition, which is consistent with the effect of recombinant protein vaccine on the adults. These results showed that tick HL-Tm might be involved in the regulation of ticks blood-feeding, growth and oviposition. PMID:25535026

Tian, Meiyuan; Tian, Zhancheng; Luo, Jin; Xie, Junren; Yin, Hong; Zeng, Qiaoying; Shen, Hui; Chai, Huiping; Yuan, Xiaosong; Wang, Fangfang; Liu, Guangyuan

2015-01-30

427

Mycobacteriophage TM4: genome structure and gene expression.  

PubMed

Mycobacteriophage TM4 is a dsDNA-tailed phage that infects both fast-growing and slow-growing strains of mycobacteria. While TM4 has been used extensively for the construction of mycobacterial shuttle phasmids and for the delivery of reporter genes and transposons into mycobacterial cells, little is known about its genetics or molecular biology. We describe here the complete 52,797 bp genome sequence of TM4 and a map of its genome organization. While not a close relative of other mycobacteriophages, TM4 encodes several proteins with sequence similarity to those of other bacteriophages--including L5 and D29--indicating that they have common ancestry. In addition, TM4 encodes proteins with similarity to haloperoxidases, glutaredoxins and the WhiB family of transcriptional regulators. Following infection, TM4 genes are expressed in a defined temporal pattern, with the virion structural proteins expressed late in the phage growth cycle. Understanding the genetics of TM4 will greatly facilitate its use as a tool for the genetic manipulation of the mycobacteria. PMID:10645443

Ford, M E; Stenstrom, C; Hendrix, R W; Hatfull, G F

1998-01-01

428

Yb integrates piRNA intermediates and processing factors into perinuclear bodies to enhance piRISC assembly.  

PubMed

PIWI-interacting RNAs (piRNAs) direct Piwi to repress transposons and maintain genome integrity in Drosophila ovarian somatic cells. piRNA maturation and association with Piwi occur at perinuclear Yb bodies, the centers of piRNA biogenesis. Here, we show that piRNA intermediates arising from the piRNA cluster flamenco (flam) localize to perinuclear foci adjacent to Yb bodies, termed Flam bodies. RNAi-based screening of piRNA factors revealed that Flam body formation depends on Yb, the core component of Yb bodies, while Piwi and another Yb body component, Armitage, are dispensable for formation. Abolishing the RNA-binding activity of Yb disrupts both Flam bodies and Yb bodies. Yb directly binds flam, but not transcripts from neighboring protein-coding genes. Thus, Yb integrates piRNA intermediates and piRNA processing factors selectively into Flam bodies and Yb bodies, respectively. We suggest that Yb is a key upstream factor in the cytoplasmic phase of the piRNA pathway in ovarian somatic cells. PMID:24953657

Murota, Yukiko; Ishizu, Hirotsugu; Nakagawa, Shinichi; Iwasaki, Yuka W; Shibata, Shinsuke; Kamatani, Miharu K; Saito, Kuniaki; Okano, Hideyuki; Siomi, Haruhiko; Siomi, Mikiko C

2014-07-10

429

Redetermination of EuScO3  

PubMed Central

Single crystals of europium(III) scandate(III), with ideal formula EuScO3, were grown from the melt using the micro-pulling-down method. The title compound crystallizes in an orthorhombic distorted perovskite-type structure, where Eu occupies the eightfold coordinated A sites (site symmetry m) and Sc resides on the centres of corner-sharing [ScO6] octahedra (B sites with site symmetry ). The structure of EuScO3 has been reported previously based on powder diffraction data [Liferovich & Mitchell (2004). J. Solid State Chem. 177, 21882197]. The results of the current redetermination based on single-crystal diffraction data shows an improvement in the precision of the structral and geometric parameters and reveals a defect-type structure. Site-occupancy refinements indicate an Eu deficiency on the A site coupled with O defects on one of the two O-atom positions. The crystallochemical formula of the investigated sample may thus be written as A(?0.032Eu0.968)BScO2.952. PMID:21581742

Kahlenberg, Volker; Maier, Dirk; Veli?kov, Boa

2009-01-01

430

Review of Tm and Ho Materials; Spectroscopy and Lasers  

NASA Technical Reports Server (NTRS)

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.

Walsh, Brian M.

2008-01-01

431

Review of Tm and Ho materials; spectroscopy and lasers  

NASA Astrophysics Data System (ADS)

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.

Walsh, B. M.

2009-04-01

432

Tm:germanate Fiber Laser: Tuning And Q-switching  

NASA Technical Reports Server (NTRS)

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.

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

2007-01-01

433

Quasi four-level Tm:LuAG laser  

NASA Technical Reports Server (NTRS)

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.

Jani, Mahendra G. (Inventor); Barnes, Norman P. (Inventor); Hutcheson, Ralph L. (Inventor); Rodriguez, Waldo J. (Inventor)

1997-01-01

434

Optical Lattice Induced Light Shifts in an Yb Atomic Clock  

SciTech Connect

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}.

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. [National Institute of Standards and Technology, 325 Broadway, Boulder, Colorado 80305 (United States); Institute of Laser Physics SB RAS, Novosibirsk 630090 (Russian Federation); Novosibirsk State University, Novosibirsk 630090 (Russian Federation)

2008-03-14

435

Structure and interactions of ultracold Yb ions and Rb atoms  

E-print Network

In order to study ultracold charge-transfer processes in hybrid atom-ion traps, we have mapped out the potential energy curves and molecular parameters for several low lying states of the Rb, Yb$^+$ system. We employ both a multi-reference configuration interaction (MRCI) and a full configuration interaction (FCI) approach. Turning points, crossing points, potential minima and spectroscopic molecular constants are obtained for the lowest five molecular states. Long-range parameters, including the dispersion coefficients are estimated from our {\\it ab initio} data. The separated-atom ionization potentials and atomic polarizability of the ytterbium atom ($\\alpha_d=128.4$ atomic units) are in good agreement with experiment and previous calculations. We present some dynamical calculations for (adiabatic) scattering lengths for the two lowest (Yb,Rb$^+$) channels that were carried out in our work. However, we find that the pseudo potential approximation is rather limited in validity, and only applies to nK temperatures. The adiabatic scattering lengths for both the triplet and singlet channels indicate that both are large and negative in the FCI approximation.

H. D. L. Lamb; J. F. McCann; B. M. McLaughlin; J. Goold; N. Wells; I. Lane

2012-07-23

436

Ag+ planar waveguides in novel Er Yb silicate glasses  

NASA Astrophysics Data System (ADS)

Planar waveguides were prepared by silver ? sodium ion-exchange in a set of specially designed europium ytterbium-doped silicate glasses. In this study, we focused on the influence of co-doping glasses with ytterbium ions on their final behaviour. First, a suitable molar ratio between Er3+/Yb3+ ions was searched in order to maximize the efficiency of absorption of the pumping signal at 980 nm and consequently to increase the intensity of the emitted signal at 1550 nm. Transmission spectra at 980 and 1550 nm and emission spectra at 1550 nm of these new glasses are given. Second, effect of ytterbium ions on permeability of a glass network structure during the ion-exchange process of waveguides fabrication was also studied. Properties of the fabricated planar waveguides were characterized by scanning electron microscopy (SEM) in order to gain information about chemical composition of the active layer prepared in Er3+/Yb3+ substrate and dark mode spectroscopy at 671 nm to obtain information about the optical properties (e.g. number of guided modes, refractive index profiles and depth of waveguide active layer).

Jankov, Stanislava; vecov, Blanka; Salavcov, Linda; pirkov, Jarmila; Mka, Martin; Oswald, Jiri

2007-05-01

437

(Gd,Yb,Tb)PO4 up-conversion nanocrystals for bimodal luminescence-MR imaging  

NASA Astrophysics Data System (ADS)

Up-conversion (Gd,Yb,Tb)PO4 materials and their potential for bimodal imaging have received little attention in the literature. Herein, we report the first study on the up-conversion emission of (Gd,Yb,Tb)PO4 nanocrystals synthesized via a hydrothermal method at 150 C. These materials exhibit ultraviolet, blue and green up-conversion emissions upon excitation with a 980 nm continuous wave laser diode. The intensity of the blue-emission band at 479 nm, ascribed to the cooperative up-conversion emission of a pair of excited Yb3+ ions, depends on the Yb3+/Tb3+ concentration ratio, calcination temperature and particle size. Strong green up-conversion emission of Tb3+ is observed at 543 nm for the 5D4 --> 7F5 transition. Relaxometry measurements reveal that the nanocrystals are efficient T2-weighted (negative) contrast agents which, combined with visible-light emission generated by infrared excitation, affords them considerable potential for being used in bimodal, photoluminescence-magnetic resonance, imaging.Up-conversion (Gd,Yb,Tb)PO4 materials and their potential for bimodal imaging have received little attention in the literature. Herein, we report the first study on the up-conversion emission of (Gd,Yb,Tb)PO4 nanocrystals synthesized via a hydrothermal method at 150 C. These materials exhibit ultraviolet, blue and green up-conversion emissions upon excitation with a 980 nm continuous wave laser diode. The intensity of the blue-emission band at 479 nm, ascribed to the cooperative up-conversion emission of a pair of excited Yb3+ ions, depends on the Yb3+/Tb3+ concentration ratio, calcination temperature and particle size. Strong green up-conversion emission of Tb3+ is observed at 543 nm for the 5D4 --> 7F5 transition. Relaxometry measurements reveal that the nanocrystals are efficient T2-weighted (negative) contrast agents which, combined with visible-light emission generated by infrared excitation, affords them considerable potential for being used in bimodal, photoluminescence-magnetic resonance, imaging. Electronic supplementary information (ESI) available: A schematic representation for the synthesis of up-conversion monoclinic (Gd,Yb,Tb)PO4 nanocrystals (Fig. S1); XRD patterns of as-synthesized (Gd,Yb,Tb)PO4.2.5H2O and calcined (Gd,Yb,Tb)PO4 samples (Fig. S2) and of dextran-coated and uncoated Gd0.87Yb0.10Tb0.03PO4 nanocrystals (Fig. S3); TEM images of (Gd,Yb,Tb)PO4.2.5H2O and (Gd,Yb,Tb)PO4 samples (Fig. S5 and S6); FT-IR spectra of (Gd,Yb,Tb)PO4.2.5H2O and (Gd,Yb,Tb)PO4 samples (Fig. S7); pump-power dependence of the up-conversion emission intensities (Fig. S8); comparison of the up-conversion emission for dextran-coated and uncoated monoclinic Gd0.87Yb0.10Tb0.03PO4 nanocrystals (Fig. S9); up-conversion emission spectra of monoclinic Gd0.85Yb0.10Tb0.05PO4 nanocrystals calcined for 3