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Sample records for lu yb crystal

  1. Group delay dispersion measurement of Yb:Gd(2)SiO(5), Yb:GdYSiO(5) and Yb:LuYSiO(5)crystal with white-light interferometry.

    PubMed

    Yang, Weijian; Li, Jing; Zhang, Fan; Zhang, Yuanyang; Zhang, Zhigang; Zhao, Guangjun; Zheng, Lihe; Xu, Jun; Su, Liangbi

    2007-06-25

    We report the measured group delay dispersion (GDD) of new crystals Yb:Gd(2)SiO,(5)(Yb:GSO), Yb:GdYSiO(5) (Yb:GYSO) and Yb:LuYSiO(5) (Yb:LYSO) over wavelengths from 1000nm to 1200nm, with a white-light interferometer. Those GDD data should be useful for the dispersion compensation for femtosecond pulse generation in the lasers with these new crystals as the gain media.

  2. Tuning of structure and enhancement of upconversion luminescence in NaLuF4:Yb(3+),Ho(3+) crystals.

    PubMed

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

    2015-07-15

    A series of NaLuF4:Yb(3+),Ho(3+) nano/micro-crystals with different crystal structures were synthesized via a hydrothermal method using citric acid as a chelating agent. The influences of NaF content, Li(+) doping, reaction temperature and reaction time on the crystal structure and shape of the as-synthesized NaLuF4 crystals were systematically investigated. To the best of our knowledge, it is the first time to report Li(+) doped α-NaLuF4:Yb(3+),Ho(3+) nanocrystals and the phase transformation by introducing Li(+) in NaLuF4 crystals. As for Li(+) doped α-NaLuF4, UC luminescence intensities of green emission (538 nm) and red emission (644 nm) in α-NaLuF4:Yb(3+),Ho(3+) nanocrystals with 20 mol% Li(+) doping are enhanced by 20 and 3.5 times compared to their Li(+)-free counterpart. As for Li(+) doped α/β-mixed NaLuF4, with the increase of Li(+) content, the phase transforms from the α/β-mixed phase to hexagonal then to cubic. UC emissions of 538 nm and 644 nm in NaLuF4:Yb(3+),Ho(3+) crystals doped with 5 mol% Li(+) are enhanced by 26.5 and 23 times, respectively. Besides, it is found that with the higher temperature and prolonged time, the morphology of NaLuF4 changes from nanoparticles to microtubes, resulting in the dramatic increase of UC emission intensity. The effects of Li(+) doping, reaction temperature and reaction time on the enhancement of UC emission intensity are discussed in detail. This study provides an effective and facile approach to obtain nano/micro-crystals with controllable structures and excellent optical properties.

  3. Tuning of structure and enhancement of upconversion luminescence in NaLuF4:Yb(3+),Ho(3+) crystals.

    PubMed

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

    2015-07-15

    A series of NaLuF4:Yb(3+),Ho(3+) nano/micro-crystals with different crystal structures were synthesized via a hydrothermal method using citric acid as a chelating agent. The influences of NaF content, Li(+) doping, reaction temperature and reaction time on the crystal structure and shape of the as-synthesized NaLuF4 crystals were systematically investigated. To the best of our knowledge, it is the first time to report Li(+) doped α-NaLuF4:Yb(3+),Ho(3+) nanocrystals and the phase transformation by introducing Li(+) in NaLuF4 crystals. As for Li(+) doped α-NaLuF4, UC luminescence intensities of green emission (538 nm) and red emission (644 nm) in α-NaLuF4:Yb(3+),Ho(3+) nanocrystals with 20 mol% Li(+) doping are enhanced by 20 and 3.5 times compared to their Li(+)-free counterpart. As for Li(+) doped α/β-mixed NaLuF4, with the increase of Li(+) content, the phase transforms from the α/β-mixed phase to hexagonal then to cubic. UC emissions of 538 nm and 644 nm in NaLuF4:Yb(3+),Ho(3+) crystals doped with 5 mol% Li(+) are enhanced by 26.5 and 23 times, respectively. Besides, it is found that with the higher temperature and prolonged time, the morphology of NaLuF4 changes from nanoparticles to microtubes, resulting in the dramatic increase of UC emission intensity. The effects of Li(+) doping, reaction temperature and reaction time on the enhancement of UC emission intensity are discussed in detail. This study provides an effective and facile approach to obtain nano/micro-crystals with controllable structures and excellent optical properties. PMID:26144530

  4. Thermo-optic properties of Yb:Lu2O3 single crystals

    NASA Astrophysics Data System (ADS)

    Loiko, P. A.; Yumashev, K. V.; Schödel, R.; Peltz, M.; Liebald, C.; Mateos, X.; Deppe, B.; Kränkel, C.

    2015-09-01

    A detailed study of thermo-optic properties of 1.5 at.% Yb:Lu2O3 single crystal is performed. Thermo-optic dispersion formulas are derived for d n/d T coefficient and thermal coefficient of the optical path. At the wavelength of 1.03 μm, d n/d T = 5.8 × 10-6 K-1. High-precision temperature-dependent measurements of the thermal expansion coefficient α are performed. At the room temperature (RT), α = 5.880 ± 0.014 × 10-6 K-1. Temperature dependence of the bandgap is analyzed, yielding RT value of E g = 5.15 eV and d E g/d T = -3.7 × 10-4 eV/K. Sensitivity factor of the thermal lens is calculated for a diode-pumped Yb:Lu2O3 crystal versus the pump spot radius and crystal temperature.

  5. Yb:Lu2SiO5 crystal : characterization of the laser emission along the three dielectric axes

    NASA Astrophysics Data System (ADS)

    Toci, Guido; Pirri, Angela; Beitlerova, Alena; Shoji, Yasuhiro; Yoshikawa, Akira; Hybler, Jiri; Nikl, Martin; Vannini, Matteo

    2015-05-01

    Yb:doped Lu2SiO5 (Lutetium orthosilicate, LSO) is an optically biaxial crystal with laser emission in the range 1000- 1100 nm. It features different absorption and emission spectra for polarization along its three dielectric axes. In this work we have characterized the laser emission properties of Yb:LSO along all the three dielectric axis, evidencing differences that can be exploited in the design of ultrafast laser sources. The material was tested in a longitudinally pumped laser cavity. The laser emission efficiency was found similar along all the three dielectric axes, with slope efficiencies around 90% in most cases. Regarding the tuning range, for the most favourable polarization direction we obtained a continuously tunable emission between 993 and 1088 nm (i. e. 95 nm) peaked at 1040 nm. The tuning curves along the three dielectric axes spanned similar ranges but with relevant differences in the shape.

  6. Plate-shaped Yb:LuPO4 crystal for efficient CW and passively Q-switched microchip lasers

    NASA Astrophysics Data System (ADS)

    Liu, Junhai; Wang, Lisha; Han, Wenjuan; Xu, Honghao; Zhong, Degao; Teng, Bing

    2016-10-01

    It is demonstrated that plate-shaped crystals of Yb:LuPO4, which are grown from spontaneous nucleation by high-temperature solution method, can be utilized to make microchip lasers operating in continuous-wave (CW) or passively Q-switched mode. Efficient operation of such a microchip laser, which is built with a 0.3 mm thick crystal plate in a 2 mm long plane-parallel cavity, is realized at room temperature. With 2.37 W of pump power absorbed, 1.45 W of CW output power is generated with a slope efficiency of 73%. When passively Q-switched with a Cr4+:YAG crystal plate as saturable absorber, the laser produces a maximum pulsed output power of 0.53 W at 1013.3 nm, at a pulse repetition rate of 23.8 kHz, the resulting pulse energy, duration, and peak power are 22.3 μJ, 4.0 ns, and 5.6 kW, respectively.

  7. Optical properties of Yb3+ doped Lu3Al5O12 crystal fibers grown by μ-pulling down technique

    NASA Astrophysics Data System (ADS)

    Toncelli, Alessandra; Alshourbagy, Mohamed; Tonelli, Mauro

    2008-11-01

    Yb doped Lu3Al5O12 single crystal fibers has been grown with various Yb3+ ion concentrations: 2%, 5%, 10%, 15%, and 50% Yb doping levels. The diameter of the fibers is around 3mm and their length is up to 110mm. The fibers have been annealed in air at 1400°C for 24h to remove Yb2+ produced during the growth in the fibers. Structural characterization by x-ray diffraction method has been performed to confirm the monocrystalline phase and the orientation of the fibers. Absorption measurements have been performed on different pieces of the fibers to check the homogeneity of the distribution of Yb3+ along the fiber length. The results indicate that the distribution coefficient is close to 1. The fluorescence lifetime was measured for different Yb3+ concentrations. Results are in agreement with the literature and can be interpreted as a mixture of the radiation trapping and concentration quenching effects. The emission cross section has been calculated both from absorption spectra and from emission data. The two different independent methods give similar results, but emission data suffer from strong reabsorption effects on some of the lines. On the zero phonon line at high doping levels a central dip appears that can be interpreted with a reabsorption model.

  8. Yb doping concentration and temperature influence on Yb:LuAG thermal lensing

    NASA Astrophysics Data System (ADS)

    Veselský, Karel; Šulc, Jan; Jelínková, Helena; Nejezchleb, Karel; Škoda, Václav

    2016-03-01

    The aim of this study was to investigate whether refractive power of thermal lens for Yb:LuAG crystal at cryogenic temperatures depends on Yb doping concentration which has not been examined yet. The three measured Yb:LuAG laser rods samples (length of 3 mm, diameter 3 mm, AR @ 0.94 μm and 1.03 μm, doping concentration 5.4, 8.4 and 16.6 at. % Yb/Lu) were mounted in the temperature controlled copper holder of the liquid nitrogen cryostat. Samples were longitudinally pumped with fiber coupled CW laser diode at 0.930 μm with the focal point 0.4 mm in diameter. The 38 mm long semi-hemispherical laser resonator consisted of a flat pump mirror (HR @ 1.03 μm and HT 0.94 μm) and curved output coupler (r=500 mm) of reflectivity 94 % @ 1.06 μm. The refractive power of thermal lens was estimated indirectly by measuring of change in the position of focused laser beam focal point. The measurement was performed for constant absorbed power of 10 W in temperature range from 80 up to 240 K. It was observed that cryogenic cooling caused reduction of thermal lens power, which increased linearly with increasing temperature. For temperatures from 80 to 160 K refractive power was identical for all concentration. For higher temperature the refractive power of thermal lens increased with increasing Yb3+ concentration. Presented study shows that application of cryogenic temperature leads to reduction of thermal effect even for high dopant concentration in Yb:LuAG crystal. This is essential for reaching of high output power while maintaining high beam quality.

  9. Performance of the Yb:Lu2O3 laser crystal in diode-pumped femtosecond oscillators and high-power regenerative amplifiers

    NASA Astrophysics Data System (ADS)

    Caracciolo, E.; Pirzio, F.; Kemnitzer, M.; Guandalini, A.; Kienle, F.; Agnesi, A.; Aus der Au, J.

    2016-03-01

    We investigated the performance of the laser gain medium Yb:Lu2O3 in a low-power oscillator and a high-power regenerative amplifier. Almost Fourier transform limited 78-fs pulses were demonstrated in the low-power, SESAM mode-locked oscillator pumped with a single-mode fiber-coupled laser diode. Exploiting the excellent thermomechanical properties of Yb:Lu2O3, we were able to achieve up to 22.2 W of average output power at a repetition rate of 500 kHz and 670-fs long pulses with the regenerative bulk amplifier. Experiments on further power up-scaling and pulse duration shortening are in progress. Up to 65 W were already proved in preliminary tests in cw regime.

  10. Spectroscopic studies of Yb3+-doped rare earth orthosilicate crystals

    NASA Astrophysics Data System (ADS)

    Campos, S.; Denoyer, A.; Jandl, S.; Viana, B.; Vivien, D.; Loiseau, P.; Ferrand, B.

    2004-06-01

    Infrared transmission and Raman scattering have been used to study Raman active phonons and crystal-field excitations in Yb3+-doped yttrium, lutetium and scandium orthosilicate crystals (Y2SiO5 (YSO), Lu2SiO5 (LSO) and Sc2SiO5 (SSO)), which belong to the same C2h6 crystallographic space group. Energy levels of the Yb3+ ion 2F5/2 manifold are presented. In the three hosts, Yb3+ ions experience high crystal field strength, particularly in Yb:SSO. Satellites in the infrared transmission spectra have been detected for the first time in the Yb3+-doped rare earth orthosilicates. They could be attributed to perturbed Yb3+ sites of the lattices or to magnetically coupled Yb3+ pairs.

  11. New microarchitectures of (Er,Yb):Lu2O3 nanocrystals embedded in PMMA: synthesis, structural characterization, and luminescent properties

    NASA Astrophysics Data System (ADS)

    Galceran, Montserrat; Pujol, Maria Cinta; Carvajal, Joan Josep; Mateos, Xavier; Formentín, Pilar; Pallarès, Josep; Marsal, Lluis Francesc; Park, Kyung Ho; Rotermund, Fabian; Kim, Kihong; Aguiló, Magdalena; Díaz, Francesc

    2013-09-01

    We report the formation of two-dimensional disordered arrays of poly(methyl)methacrylate (PMMA) microcolumns with embedded single size distribution of Lu0.990Er0.520Yb0.490 nanocrystals, (Er,Yb):Lu2O3, using a disordered porous silicon template. The cubic (Er,Yb):Lu2O3 nanocrystals, which crystallize into the cubic system with [Equation not available: see fulltext.] space group, were synthesized using the modified Pechini method. Electronic microscopic techniques were used to study the distribution of the nanocrystals in the PMMA columns. Cathodoluminescence was used to observe the visible luminescence of the particles. Red emission attributed to 4 F9/2 → 4I15/2 erbium transition is predominant in these new composites.

  12. X-ray absorption spectroscopy study on h-LuFeO3 and h-YbFeO3

    NASA Astrophysics Data System (ADS)

    Xu, Xiaoshan; Cao, Shi; Paudel, Tula; Sinha, Kishan; Jiang, Xuanyuan; Wang, Wenbin; Wang, Jian; Tsymbal, Evgeny; Dowben, Peter

    2015-03-01

    We have studied the unoccupied electronic band structure of the hexagonal ferrites h-LuFeO3 and h-YbFeO3 using the absorption spectroscopy obtained with linearly polarized soft X-ray synchrotron radiation. The shapes of the spectra have been analyzed in terms of the splitting of atomic energy levels in various crystal fields corresponding to the local symmetry of the different atomic sites. Significant hybridization between O-2p and various iron and rare earth orbitals (such as Fe-3d, Lu/Yb-5d and Yb-4f) have been observed. The spectral weight contributions to the electronic states near the bottom of the conduction band are found to consist of Fe-3d, Lu/Yb-5d, and Yb-4f as relatively narrow bands, as well as a wide O-2p band covering much of the measured energy range. The results are consistent with the density functional theory calculation including onsite-Coulomb repulsion corrections in terms of Hubbard U. The project was supported by SRC-NRI Center under Task ID 2398.001, by NSF through Nebraska MRSEC DMR-0820521, DMR 0747704, and by Nebraska EPSCoR.

  13. An Yb3+-doped Lu2SiO5 mode-locked laser using a reflective graphene oxide absorber

    NASA Astrophysics Data System (ADS)

    Feng, Chao; Liu, Jie; Wang, Yonggang; Zheng, Lihe; Su, Liangbi; Xu, Jun

    2013-06-01

    Reflective graphene oxide played the part of the saturable absorber to achieve a continuous wave mode-locking (CWML) laser based on Yb3+:Lu2SiO5 (Yb:LSO) crystal for the first time. The laser operated at a repetition frequency of 87 MHz at a maximum average output power of 0.95 W with a single pulse energy of 10.9 nJ. A 9.8 ps ultra-short pulse was yielded at 1058 nm with a full width at half maximum (FWHM) of 2.09 nm, corresponding to a peak power of 1.11 kW.

  14. Near-infrared Downconversion in LuPO4: Tm3+, Yb3+ Phosphors.

    PubMed

    Li, Li; Wang, Yongjie; Shen, Jun; Chang, Wenxuan; Jin, Tianting; Wei, Xiantao; Tian, Ya

    2016-04-01

    Tm3+ and Yb3+ codoped LuPO4 phosphors were synthesized by the reverse-strike co-precipitation method. The obtained LuPO4:Tm3+,Yb3+ phosphors were characterized by X-ray diffraction (XRD), diffuse reflectance spectra, photoluminescence (PL) spectra, and decay lifetime to understand the observed near-infrared downconversion (DC) phenomena. The XRD results show that all the prepared phosphors can be readily indexed to the pure tetragonal phase of LuPO4 and exhibit good crystallinity. The experimental results showed that the strong visible emission around 649 nm from Tm3+(1G4 --> 3F4) and near-infrared (NIR) emission around 1003 nm from Yb3+(2F5/2 --> 2F7/2) of LuPO4:Tm3+,Yb3+ phosphors were observed under 468 nm excitation, respectively. The Yb3+ concentration dependence of luminescent properties and lifetimes of both the visible and NIR emissions have also been investigated. The quenching concentration of Yb3+ ions approaches 30 mol%. The DC mechanism is also discussed in detail. PMID:27451658

  15. Near-infrared Downconversion in LuPO4: Tm3+, Yb3+ Phosphors.

    PubMed

    Li, Li; Wang, Yongjie; Shen, Jun; Chang, Wenxuan; Jin, Tianting; Wei, Xiantao; Tian, Ya

    2016-04-01

    Tm3+ and Yb3+ codoped LuPO4 phosphors were synthesized by the reverse-strike co-precipitation method. The obtained LuPO4:Tm3+,Yb3+ phosphors were characterized by X-ray diffraction (XRD), diffuse reflectance spectra, photoluminescence (PL) spectra, and decay lifetime to understand the observed near-infrared downconversion (DC) phenomena. The XRD results show that all the prepared phosphors can be readily indexed to the pure tetragonal phase of LuPO4 and exhibit good crystallinity. The experimental results showed that the strong visible emission around 649 nm from Tm3+(1G4 --> 3F4) and near-infrared (NIR) emission around 1003 nm from Yb3+(2F5/2 --> 2F7/2) of LuPO4:Tm3+,Yb3+ phosphors were observed under 468 nm excitation, respectively. The Yb3+ concentration dependence of luminescent properties and lifetimes of both the visible and NIR emissions have also been investigated. The quenching concentration of Yb3+ ions approaches 30 mol%. The DC mechanism is also discussed in detail.

  16. Rare-earth metal gallium silicides via the gallium self-flux method. Synthesis, crystal structures, and magnetic properties of RE(Ga1–xSix)₂ (RE=Y, La–Nd, Sm, Gd–Yb, Lu)

    SciTech Connect

    Darone, Gregory M.; Hmiel, Benjamin; Zhang, Jiliang; Saha, Shanta; Kirshenbaum, Kevin; Greene, Richard; Paglione, Johnpierre; Bobev, Svilen

    2013-05-01

    Fifteen ternary rare-earth metal gallium silicides have been synthesized using molten Ga as a molten flux. They have been structurally characterized by single-crystal and powder X-ray diffraction to form with three different structures—the early to mid-late rare-earth metals RE=La–Nd, Sm, Gd–Ho, Yb and Y form compounds with empirical formulae RE(GaxSi1–x)₂ (0.38≤x≤0.63), which crystallize with the tetragonal α-ThSi₂ structure type (space group I4₁/amd, No. 141; Pearson symbol tI12). The compounds of the late rare-earth crystallize with the orthorhombic α-GdSi₂ structure type (space group Imma, No. 74; Pearson symbol oI12), with refined empirical formula REGaxSi2–x–y (RE=Ho, Er, Tm; 0.33≤x≤0.40, 0.10≤y≤0.18). LuGa₀.₃₂₍₁₎Si₁.₄₃₍₁₎ crystallizes with the orthorhombic YbMn₀.₁₇Si₁.₈₃ structure type (space group Cmcm, No. 63; Pearson symbol oC24). Structural trends are reviewed and analyzed; the magnetic susceptibilities of the grown single-crystals are presented. - Graphical abstract: This article details the exploration of the RE–Ga–Si ternary system with the aim to systematically investigate the structural “boundaries” between the α-ThSi₂ and α-GdSi₂-type structures, and studies of the magnetic properties of the newly synthesized single-crystalline materials. Highlights: • Light rare-earth gallium silicides crystallize in α-ThSi₂ structure type. • Heavy rare-earth gallium silicides crystallize in α-GdSi₂ structure type. • LuGaSi crystallizes in a defect variant of the YbMn₀.₁₇Si₁.₈₃ structure type.

  17. First laser operation and spectroscopic characterization of mixed garnet Yb:LuYAG ceramics

    NASA Astrophysics Data System (ADS)

    Toci, Guido; Pirri, Angela; Li, Jiang; Xie, Tengfei; Pan, Yubai; Nikl, Martin; Babin, Vladimir; Beitlerová, Alena; Vannini, Matteo

    2016-03-01

    We present the optical and spectroscopic characterization and the first example of laser operation of Yb doped LuYAG ceramics, with two different compositions, namely (Lu0.25Y0.75)3Al5O12 and (Lu0.50Y0.50)3Al5O12, both with 15% Yb doping. Ceramic samples were prepared by reactive sintering from high purity α-Al2O3, Lu2O3, Y2O3, Yb2O3 powders using Tetraethoxysilane (TEOS) and MgO as sintering aids. After ball milling, the slurry was dried, uniaxially pressed into 20 mm diameter pellets at 20 MPa, and then cold isostatically pressed at 200 MPa. Sintering was conducted at 1850°C for 30 h under vacuum, followed by annealing in air (1500 °C, 10 h) to remove the oxygen vacancies. Laser tests were carried out in a laser cavity end pumped by a fiber coupled diode laser emitting at 936 nm. A slope efficiency as high as 65.2% with a maximum output power of 8.7 W (in quasi-CW pumping conditions) was obtained from the sample with composition (Lu0.25Y0.75)3Al5O12, whereas the sample with composition (Lu0.50Y0.50)3Al5O12 had a maximum slope efficiency of 49.5% (due to the higher scattering losses), and 6.7 W of maximum output power. Furthermore we characterized the tuning range of the two samples.

  18. Spectroscopic and laser characterization of Yb0.15:(LuxY1-x)3Al5O12 ceramics with different Lu/Y balance.

    PubMed

    Pirri, Angela; Toci, Guido; Li, Jiang; Xie, Tengfei; Pan, Yubai; Babin, Vladimir; Beitlerova, Alena; Nikl, Martin; Vannini, Matteo

    2016-08-01

    We report a broad comparative analysis of the spectroscopic and laser properties of solid solution Lutetium-Yttrium Aluminum Garnet (LuYAG, (LuxY1-x)3Al5O12) ceramics doped with Yb. The investigation was mainly aimed to assess the impact of the Lu/Y ratio on the Yb optical and laser properties. Therefore we analyzed a set of samples with different Y/Lu balance, namely 25/75, 50/50 and 75/25, with 15% Yb doping. We found that the Yb absorption and emission spectra changed from YAG to LuAG when gradually increasing in Lu content. Regarding the laser emission, remarkable results were achieved with all samples. Maximum output power was 8.2 W, 7.3 W and 8.7 W for Y/Lu balance 25/75, 50/50 and 75/25 respectively, at 1030 nm; the slope efficiency and the optical-to-optical efficiencies approached or exceeded 60% and 50% respectively. The tuning range was investigated using an intracavity ZnSe prism. The broadest tuning range (998 nm to 1063 nm) was obtained with Y/Lu balance 75/25, whereas the emission of the other two samples extended from 1000 nm to 1058 nm. To the best of our knowledge, this is the first comparative analysis of Yb:LuYAG ceramics or crystals as laser host across such a broad range of Y/Lu ratios. PMID:27505750

  19. Morphology evolution and pure red upconversion mechanism of β-NaLuF4 crystals

    NASA Astrophysics Data System (ADS)

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

    2016-06-01

    A series of β-NaLuF4 crystals were synthesized via a hydrothermal method. Hexagonal phase microdisks, microprisms, and microtubes were achieved by simply changing the amount of citric acid in the initial reaction solution. Pure red upconversion (UC) luminescence can be observed in β-NaLuF4:Yb3+, Tm3+, Er3+ and Li+ doped β-NaLuF4:20% Yb3+, 1% Tm3+, 20% Er3+. Based on the rate equations, we report the theoretical model about the pure red UC mechanism in Yb3+/Tm3+/Er3+ doped system. It is proposed that the pure red UC luminescence is mainly ascribed to the energy transfer UC from Tm3+:3F4 → 3H6 to Er3+:4I11/2 → 4F9/2 and the cross-relaxation (CR) effect [Er3+:4S3/2 + 4I15/2 → 4I9/2 + 4I13/2] rather than the long-accepted mechanism [CR process among Er3+:4F7/2 + 4I11/2 → 4F9/2 + 4F9/2]. In addition, compared to the Li+-free counterpart, the pure red UC luminescence in β-NaLuF4:20% Yb3+, 1% Tm3+, 20% Er3+ with 15 mol% Li+ doping is enhanced by 13.7 times. This study provides a general and effective approach to obtain intense pure red UC luminescence, which can be applied to other synthetic strategies.

  20. Morphology evolution and pure red upconversion mechanism of β-NaLuF4 crystals.

    PubMed

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

    2016-01-01

    A series of β-NaLuF4 crystals were synthesized via a hydrothermal method. Hexagonal phase microdisks, microprisms, and microtubes were achieved by simply changing the amount of citric acid in the initial reaction solution. Pure red upconversion (UC) luminescence can be observed in β-NaLuF4:Yb(3+), Tm(3+), Er(3+) and Li(+) doped β-NaLuF4:20% Yb(3+), 1% Tm(3+), 20% Er(3+). Based on the rate equations, we report the theoretical model about the pure red UC mechanism in Yb(3+)/Tm(3+)/Er(3+) doped system. It is proposed that the pure red UC luminescence is mainly ascribed to the energy transfer UC from Tm(3+):(3)F4 → (3)H6 to Er(3+):(4)I11/2 → (4)F9/2 and the cross-relaxation (CR) effect [Er(3+):(4)S3/2 + (4)I15/2 → (4)I9/2 + (4)I13/2] rather than the long-accepted mechanism [CR process among Er(3+):(4)F7/2 + (4)I11/2 → (4)F9/2 + (4)F9/2]. In addition, compared to the Li(+)-free counterpart, the pure red UC luminescence in β-NaLuF4:20% Yb(3+), 1% Tm(3+), 20% Er(3+) with 15 mol% Li(+) doping is enhanced by 13.7 times. This study provides a general and effective approach to obtain intense pure red UC luminescence, which can be applied to other synthetic strategies. PMID:27306720

  1. Morphology evolution and pure red upconversion mechanism of β-NaLuF4 crystals

    PubMed Central

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

    2016-01-01

    A series of β-NaLuF4 crystals were synthesized via a hydrothermal method. Hexagonal phase microdisks, microprisms, and microtubes were achieved by simply changing the amount of citric acid in the initial reaction solution. Pure red upconversion (UC) luminescence can be observed in β-NaLuF4:Yb3+, Tm3+, Er3+ and Li+ doped β-NaLuF4:20% Yb3+, 1% Tm3+, 20% Er3+. Based on the rate equations, we report the theoretical model about the pure red UC mechanism in Yb3+/Tm3+/Er3+ doped system. It is proposed that the pure red UC luminescence is mainly ascribed to the energy transfer UC from Tm3+:3F4 → 3H6 to Er3+:4I11/2 → 4F9/2 and the cross-relaxation (CR) effect [Er3+:4S3/2 + 4I15/2 → 4I9/2 + 4I13/2] rather than the long-accepted mechanism [CR process among Er3+:4F7/2 + 4I11/2 → 4F9/2 + 4F9/2]. In addition, compared to the Li+-free counterpart, the pure red UC luminescence in β-NaLuF4:20% Yb3+, 1% Tm3+, 20% Er3+ with 15 mol% Li+ doping is enhanced by 13.7 times. This study provides a general and effective approach to obtain intense pure red UC luminescence, which can be applied to other synthetic strategies. PMID:27306720

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

    PubMed

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

    2014-05-23

    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 μm 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

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

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

    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 μm 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.

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

    PubMed

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

    2016-07-01

    Core-shell-shell heterostructures of α-NaLuF4:Yb/Er@NaLuF4:Yb@MF2 (M = Ca, Sr, Ba) have been successfully fabricated via the thermal decomposition method. Upconversion nanoparticles (UCNPs) were characterized by powder X-ray diffraction (XRD), transmission electron microscopy (TEM), upconversion luminescence (UCL) spectroscopy, etc. Under 980 nm excitation, the emission intensities of the UCNPs are remarkably enhanced after coating the MF2 (M = Ca, Sr, and Ba) shell. Among these samples, CaF2 coated UCNPs show the strongest overall emission, while BaF2 coated UCNPs exhibit the longest lifetime. These results demonstrate that alkaline earth metal fluorides are ideal materials to improve the UCL properties. Meanwhile, although the lattice mismatch between the ternary NaREF4 core and the binary MF2 (M = Sr and Ba) shell is relatively large, the successfully synthesized NaLuF4:Yb/Er@NaLuF4:Yb@MF2 indicates a new outlook on the fabrication of heterostructural core-shell UCNPs. PMID:27327414

  5. Growth and spectroscopic properties of Er,Yb : YCOB crystals

    NASA Astrophysics Data System (ADS)

    Yu, Young Moon; Jin Ju, Jung; Cha, Myoungsik

    2001-07-01

    High quality Yb 3+ and Er 3+ co-doped YCa 4O(BO 3) 3 crystals were grown by the Czochralski method. Phase relationships between Y 3+/Yb 3+/Er 3+ and Ca 2+/B 3+ in the vicinity of the stoichiometric composition of YCa 4O(BO 3) 3 were discussed. The calculated absorption and emission cross sections were estimated. Efficient energy transfer from the excited Yb 3+ to the Er 3+ leads to strong emissions in the wavelength range of 1510-1580 nm peaking at 1535 nm. Lifetime of Er- 4I 11/2 was measured to be 1.23 ms. The energy transfer efficiency of 97% for Er 0.02Yb 0.2Y 0.78Ca 4O(BO 3) 3 crystal was estimated from the reduced lifetimes of the Yb 3+- 2F 5/2 level.

  6. Diode-side-pumped, passively Q-switched Yb:LuAG laser

    NASA Astrophysics Data System (ADS)

    Kaskow, Mateusz; Galecki, Lukasz; Jabczynski, Jan K.; Skorczakowski, Marek; Zendzian, Waldemar; Sulc, Jan; Nemec, Michal; Jelinkova, Helena

    2015-10-01

    A high-gain, diode-side-pumped Yb:LuAG slab laser was designed and investigated for use at room temperature. Pumping occurred from a fast-axis collimated 2D laser diode stack emitting at a wavelength of 970 nm, with 0.8 J over a duration of 0.8 ms. The pump scheme, which enabled efficient mode matching and high gain, was analysed and experimentally verified for different dopant levels. An energy of 100 mJ with 23% slope efficiency in a near fundamental mode was achieved in the free-running regime. A peak power of 2.5 MW and a pulse energy of 10.1 mJ were demonstrated in passive Q-switching by means of a Cr:YAG saturable absorber with 39% initial transmission. The study defined the indications for optimizing such a system.

  7. Spin reorientation, magnetization reversal, and negative thermal expansion observed in R F e0.5C r0.5O3 perovskites (R =Lu ,Yb ,Tm )

    NASA Astrophysics Data System (ADS)

    Pomiro, Fernando; Sánchez, Rodolfo D.; Cuello, Gabriel; Maignan, Antoine; Martin, Christine; Carbonio, Raúl E.

    2016-10-01

    Three members of the perovskite family R F e0.5C r0.5O3 (R =Lu ,Yb , and Tm) have been synthesized and characterized. A systematic study of the crystal and magnetic structures was performed by neutron powder diffraction combined with magnetization measurements. All these compounds crystallize in a Pbnm orthorhombic unit cell and they are already antiferromagnetic at room temperature. The study of the magnetic structure vs temperature showed the occurrence of a progressive spin reorientation from Γ4TM to Γ2TM for the transition metal sublattice, and in the Tm-based sample, a long-range magnetic order of the T m3 + sublattice was found (Γ8R) . These results are in excellent agreement with the magnetic susceptibility measurements. No spin reorientation is observed in the Lu-based sample for which a magnetization reversal at a compensation temperature Tcomp= 225 K was detected. A clear magnetostrictive effect was observed in the samples with R =Yb and Tm associated with a negative thermal expansion and was assigned to a magnetoelastic effect produced by repulsion between the magnetic moments of neighboring transition metal ions.

  8. Syntheses, structures, and vibrational spectroscopy of the two-dimensional iodates Ln(IO{sub 3}){sub 3} and Ln(IO{sub 3}){sub 3}(H{sub 2}O) (Ln =Yb, Lu)

    SciTech Connect

    Assefa, Zerihun . E-mail: zassefa@ncat.edu; Ling Jie; Haire, Richard G.; Albrecht-Schmitt, Thomas E.; Sykora, Richard E. . E-mail: rsykora@jaguar1.usouthal.edu

    2006-12-15

    The reaction of Lu{sup 3+} or Yb{sup 3+} and H{sub 5}IO{sub 6} in aqueous media at 180 {sup o}C leads to the formation of Yb(IO{sub 3}){sub 3}(H{sub 2}O) or Lu(IO{sub 3}){sub 3}(H{sub 2}O), respectively, while the reaction of Yb metal with H{sub 5}IO{sub 6} under similar reaction conditions gives rise to the anhydrous iodate, Yb(IO{sub 3}){sub 3}. Under supercritical conditions Lu{sup 3+} reacts with HIO{sub 3} and KIO{sub 4} to yield the isostructural Lu(IO{sub 3}){sub 3}. The structures have been determined by single-crystal X-ray diffraction. Crystallographic data are (MoK{alpha}, {lambda}=0.71073 A): Yb(IO{sub 3}){sub 3}, monoclinic, space group P2{sub 1}/n, a=8.6664(9) A, b=5.9904(6) A, c=14.8826(15) A, {beta}=96.931(2){sup o}, V=766.99(13), Z=4, R(F)=4.23% for 114 parameters with 1880 reflections with I>2{sigma}(I); Lu(IO{sub 3}){sub 3}, monoclinic, space group P2{sub 1}/n, a=8.6410(9), b=5.9961(6), c=14.8782(16) A, {beta}=97.028(2){sup o}, V=765.08(14), Z=4, R(F)=2.65% for 119 parameters with 1756 reflections with I>2{sigma}(I); Yb(IO{sub 3}){sub 3}(H{sub 2}O), monoclinic, space group C2/c, a=27.2476(15), b=5.6296(3), c=12.0157(7) A, {beta}=98.636(1){sup o}, V=1822.2(2), Z=8, R(F)=1.51% for 128 parameters with 2250 reflections with I>2{sigma}(I); Lu(IO{sub 3}){sub 3}(H{sub 2}O), monoclinic, space group C2/c, a=27.258(4), b=5.6251(7), c=12.0006(16) A, {beta}=98.704(2){sup o}, V=1818.8(4), Z=8, R(F)=1.98% for 128 parameters with 2242 reflections with I>2{sigma}(I). The f elements in all of the compounds are found in seven-coordinate environments and bridged with monodentate, bidentate, or tridentate iodate anions. Both Lu(IO{sub 3}){sub 3}(H and Yb(IO{sub 3}){sub 3}(H{sub 2}O) display distinctively different vibrational profiles from their respective anhydrous analogs. Hence, the Raman profile can be used as a complementary diagnostic tool to discern the different structural motifs of the compounds. - Graphical abstract: Four new metal iodates, Yb(IO{sub 3

  9. Effect of Lu-to-Y ratio and Mo coactivation on scintillation properties of LuYAG:Pr and LuAG:Pr,Mo crystals

    NASA Astrophysics Data System (ADS)

    Drozdowski, W.; Brylew, K.; Witkowski, M. E.; Drewniak, A.; Masewicz, Z.; Wojtowicz, A. J.; Kisielewski, J.; Świrkowicz, M.

    2016-09-01

    In this paper the basic scintillation and thermoluminescence properties of LuYAG:Pr and LuAG:Pr,Mo crystals are reported. It is shown that, primarily, both materials display significantly higher scintillation yields than their prototype LuAG:Pr. The results of radioluminescence, low and high temperature thermoluminescence, and scintillation time profile measurements are analyzed quantitatively to allow us a better understanding of the scintillation process in LuYAG:Pr and LuAG:Pr,Mo, as well as to let us propose or verify possible explanations of the observed yield enhancement.

  10. Enhanced performances of diode-pumped sapphire/Er³⁺:Yb³⁺:LuAl₃(BO₃)₄/sapphire micro-laser at 1.5-1.6 μm.

    PubMed

    Chen, Yujin; Lin, Yanfu; Huang, Jianhua; Gong, Xinghong; Luo, Zundu; Huang, Yidong

    2015-05-01

    A sandwich-type sapphire/Er3+:Yb3+:LuAl3(BO3)4/sapphire micro-laser was fabricated by tightly pressing two sapphire crystals and a Er3+:Yb3+:LuAl3(BO3)4 microchip together, and directly depositing cavity mirrors onto the outside surfaces of the sapphire crystals. Pumped by a continuous-wave 976 nm diode laser, a 1543 nm laser with maximum output power of 1.17 W and slope efficiency of 33% with respect to incident pump power was realized in the sandwich-type micro-laser, whereas a laser with maximum output power of 0.46 W and slope efficiency of 17% was obtained in a monolithic Er3+:Yb3+:LuAl3(BO3)4 micro-laser. Furthermore, efficient 1521 nm continuous-wave and passively Q-switched pulse lasers were also demonstrated in the sandwich-type micro-laser.

  11. Enhanced performances of diode-pumped sapphire/Er³⁺:Yb³⁺:LuAl₃(BO₃)₄/sapphire micro-laser at 1.5-1.6 μm.

    PubMed

    Chen, Yujin; Lin, Yanfu; Huang, Jianhua; Gong, Xinghong; Luo, Zundu; Huang, Yidong

    2015-05-01

    A sandwich-type sapphire/Er3+:Yb3+:LuAl3(BO3)4/sapphire micro-laser was fabricated by tightly pressing two sapphire crystals and a Er3+:Yb3+:LuAl3(BO3)4 microchip together, and directly depositing cavity mirrors onto the outside surfaces of the sapphire crystals. Pumped by a continuous-wave 976 nm diode laser, a 1543 nm laser with maximum output power of 1.17 W and slope efficiency of 33% with respect to incident pump power was realized in the sandwich-type micro-laser, whereas a laser with maximum output power of 0.46 W and slope efficiency of 17% was obtained in a monolithic Er3+:Yb3+:LuAl3(BO3)4 micro-laser. Furthermore, efficient 1521 nm continuous-wave and passively Q-switched pulse lasers were also demonstrated in the sandwich-type micro-laser. PMID:25969325

  12. Improved Near-Infrared Up-Conversion Emission of Tm3+ Sensitized by Yb3+ and Ho3+ in LuF3 Nanocrystals.

    PubMed

    Xu, Xuhui; Wu, Yumei; Bian, Wenjuan; Yu, Xue; Zhang, Buhao; Li, Qianyue; Qiu, Jianbei; Liu, BiTao

    2016-04-01

    In the present work, mono-disperse and uniform orthorhombic lutetium fluoride (LuF3) nanocrystals with an average size of about 35 nm have been successfully synthesized by a simple ionothermal method without any template. The infrared (IR) to visible up-conversion (UC) photoluminescence of LuF3 doped with Yb3+, Tm3+, and Ho3+ under 980 nm excitation was systemically studied. The intensity of near infrared (NIR) to visible up-conversion emission of Tm3+ was improved efficiently by adding Yb3+ and Ho3+ in LuF3, especially for the broad NIR emission band located at 812 nm. Meanwhile, compared to the Yb3+ and Tm3+ co-doped LuF3, the ratio of red to green emission in the Yb3+, TmS+, and HoS+ co-doped LuF3 changed greatly, and a bright yellowish-green emission was observed under 980 nm laser excitation. It shows that Yb3+, Tm3+ and Ho3+ co-doped LuF3 nanocrystals provided a potential application in vitro and in vivo bio-imaging, color displays and optical storage. PMID:27451685

  13. Thermal evolution of the spin ordering at the concomitant spin-orbital rearrangement temperature in RVO3 (R=Lu, Yb and Tm)

    NASA Astrophysics Data System (ADS)

    Sarkar, Tapati; Ivanov, Sergey A.; Bazuev, G. V.; Nordblad, Per; Mathieu, Roland

    2016-07-01

    Synthesis, crystal structure and magnetization measurements of phase pure polycrystalline RVO3 (R=Lu, Yb and Tm) are reported. The compounds were stabilized in the orthorhombic structure by thermal treatment of the respective precursors (RVO4) in a reducing atmosphere. Special pressure treatment was carried out during the synthesis to ensure phase pure samples without secondary phases. Magnetization measurements reveal the presence of two spin ordering temperatures in the samples. Interestingly, at the lower spin ordering temperature, TSO2, the uncompensated excess moment of the antiferromagnetic spin structure has different field dependences above and below TSO2, causing a jump in the thermal evolution of the magnetization that changes sign with increasing field strength. This jump is associated with the reported magnetic and orbital rearrangement in the samples, and the different spin configurations in the C- and G-type antiferromagnetic structures.

  14. Crystal field excitations of YbMn2Si2

    NASA Astrophysics Data System (ADS)

    Mole, R. A.; Hofmann, M.; Adroja, D. T.; Moze, O.; Campbell, S. J.

    2013-12-01

    The crystal field excitations of the rare earth intermetallic compound YbMn2Si2 have been measured by inelastic neutron scattering over the temperature range 2.5-50 K. The YbMn2Si2 spectra exhibit three low energy excitations (~3-7 meV) in the antiferromagnetic AFil region above the magnetic phase transition at TN2 = 30(5) K. The crystal field parameters have been determined for YbMn2Si2 in the antiferromagnetic AFil region. A further two inelastic excitations (~9 meV, 17 meV) are observed below TN2=30(5) K, the temperature at which the high temperature antiferromagnetic structure is reported to exhibit doubling of the magnetic cell. Energy level diagrams have been determined for Yb3+ ions in the different sites above (single site) and below the magnetic transition temperature (two sites). The excitation energies for both sites are shown to be temperature independent with the temperature dependences of the transition intensities for the two sites described well by a simple Boltzmann model. The spectra below TN2 cannot be described fully in terms of molecular field models based on either a single Yb3+ site or two Yb3+ sites. This indicates that the magnetic behaviour of YbMn2Si2 is more complicated than previously considered. The inability to account fully for excitations below the magnetic phase transition may be due to an, as yet, unresolved structural transition associated with the magnetic transition.

  15. Charge transfer processes and ultraviolet induced absorption in Yb:YAG single crystal laser materials

    NASA Astrophysics Data System (ADS)

    Rydberg, S.; Engholm, M.

    2013-06-01

    Charge transfer (CT) transitions and UV induced color centers in Yb:YAG single crystals have been investigated. A simultaneous pair formation of a stable Yb2+ ion and a hole related (O-) color center (hole polaron) are observed through a CT-process. Slightly different types of hole related color centers are formed in Yb:YAG crystals containing small levels of iron impurities. Furthermore, excitation spectroscopy on the UV irradiated Yb:YAG samples could confirm an energy transfer process between Yb3+ and Yb2+ ions. The findings are important for an increased knowledge of the physical loss mechanisms observed in Yb-doped laser materials, such as the nonlinear decay process in Yb:YAG crystals as well as the photodarkening phenomenon in Yb-doped fiber lasers.

  16. Indirect Production of No Carrier Added (NCA) (177)Lu from Irradiation of Enriched (176)Yb: Options for Ytterbium/Lutetium Separation.

    PubMed

    Dash, Ashutosh; Chakravarty, Rubel; Knapp, Furn F Russ; Pillai, Ambikalmajan M R

    2015-01-01

    This article presents a concise review of the production of no-carrier-added (NCA) (177)Lu by the 'indirect' route by irradiating ytterbium-176 ((176)Yb)-enriched targets. The success of this production method depends on the ability to separate the microscopic amounts of NCA (177)Lu from bulk irradiated ytterbium targets. The presence of Yb(+3) from the target in the final processed (177)Lu will adversely affect the quality of (177)Lu by decreasing the specific activity and competing with Lu(+3) complexation since ytterbium will follow the same coordination chemistry. Ytterbium and lutetium are adjacent members of the lanthanide family with very similar chemical properties which makes the separation of one from the other a challenging task. This review provides a summary of the methods developed for the separation and purification of NCA (177)Lu from neutron irradiated (176)Yb-enriched targets, a critical assessment of recent developments and a discussion of the current status of this (177)Lu production method.

  17. Infrared-to-Visible Light Conversion in Er(3+) -Yb(3+) :Lu3 Ga5 O12 Nanogarnets.

    PubMed

    Rathaiah, Mamilla; Haritha, Pamuluri; Linganna, Kadathala; Monteseguro, Virginia; Martín, Inocencio Rafael; Lozano-Gorrín, Antonio Diego; Babu, Palamandala; Jayasankar, Chalicheemalapalli Kulala; Lavín, Victor; Venkatramu, Vemula

    2015-12-21

    Er(3+) -Yb(3+) co-doped Lu3 Ga5 O12 nanogarnets were prepared and characterized; their structural and luminescence properties were determined as a function of the Yb(3+) concentration. The morphology of the nanogarnets was studied by HRTEM. Under 488 nm excitation, the nanogarnets emit green, red, and near-infrared light. The decay curves for the ((4) S3/2 , (2) H11/2 ) and (4) F9/2 levels of the Er(3+) ions exhibit a non-exponential nature under resonant laser excitation and their effective lifetimes are found to decrease with an increase in the Yb(3+) concentration from 1.0 to 10.0 mol %. The non-exponential decay curves are well fitted to the Inokuti-Hirayama model for S=8, indicating that the mechanism of interaction for energy transfer between the optically active ions is of dipole-quadrupole type. Upon 976 nm laser excitation, an intense green upconverted emission is clearly observed by the naked eyes. A significant enhancement of the red-to-green intensity ratio of Er(3+) ions was observed with an increase in Yb(3+) concentration. The power dependence and the dynamics of the upconverted emission confirm the existence of two-photon upconversion processes for the green and red emissions. PMID:26467682

  18. Infrared-to-Visible Light Conversion in Er(3+) -Yb(3+) :Lu3 Ga5 O12 Nanogarnets.

    PubMed

    Rathaiah, Mamilla; Haritha, Pamuluri; Linganna, Kadathala; Monteseguro, Virginia; Martín, Inocencio Rafael; Lozano-Gorrín, Antonio Diego; Babu, Palamandala; Jayasankar, Chalicheemalapalli Kulala; Lavín, Victor; Venkatramu, Vemula

    2015-12-21

    Er(3+) -Yb(3+) co-doped Lu3 Ga5 O12 nanogarnets were prepared and characterized; their structural and luminescence properties were determined as a function of the Yb(3+) concentration. The morphology of the nanogarnets was studied by HRTEM. Under 488 nm excitation, the nanogarnets emit green, red, and near-infrared light. The decay curves for the ((4) S3/2 , (2) H11/2 ) and (4) F9/2 levels of the Er(3+) ions exhibit a non-exponential nature under resonant laser excitation and their effective lifetimes are found to decrease with an increase in the Yb(3+) concentration from 1.0 to 10.0 mol %. The non-exponential decay curves are well fitted to the Inokuti-Hirayama model for S=8, indicating that the mechanism of interaction for energy transfer between the optically active ions is of dipole-quadrupole type. Upon 976 nm laser excitation, an intense green upconverted emission is clearly observed by the naked eyes. A significant enhancement of the red-to-green intensity ratio of Er(3+) ions was observed with an increase in Yb(3+) concentration. The power dependence and the dynamics of the upconverted emission confirm the existence of two-photon upconversion processes for the green and red emissions.

  19. Diffusion of Excitation in GGG:Yb3+ Laser Crystal

    NASA Astrophysics Data System (ADS)

    Kisialiou, I. G.; Ivakin, E. V.

    2015-01-01

    The excitation diffusion coefficient DE is measured directly in laser crystals by the optical method of high-frequency dynamic gratings. DE for Gd3Ga5O12:Yb3+ (21 at.%) crystal is found to be 3·10-9 cm3/s at room temperature and 1.2·10-8 cm3/s at 190°C. In KYW:Yb3+ (20 at.%) crystal no excitation diffusion is observed under the same experimental conditions. It is shown that DE is affected by the activator concentration, the temperature, and the probability of radiationless energy exchange between neighboring active impurity ions, which depends on the minimal distance between donor and acceptor.

  20. Pressure-Induced Zircon-Type to Scheelite-Type Phase Transition in Orthophosphates YbPO4 and LuPO4

    SciTech Connect

    Zhang, F.; Maik, L; Ewing, R; Lian, J; Wang, Z; Hu, J; Boatner, L

    2008-01-01

    The tetragonal orthophosphates, YbPO4 and LuPO4, were studied by in situ X-ray diffraction (XRD) at pressures up to 52 and 43 GPa, respectively. A reversible phase transition from the zircon structure-type to the scheelite structure-type was found at not, vert, similar22 GPa for YbPO4 and 19 GPa for LuPO4. Coinciding with the transition from the zircon structure-type to the scheelite structure-type, there is a not, vert, similar 10% reduction in volume and a significant increase in the bulk modulus for both compounds.

  1. Intermediate valence in single crystals of (Lu{sub 1−x}Y b{sub x}){sub 3}Rh{sub 4}Ge{sub 13} (0 ≤ x ≤ 1)

    SciTech Connect

    Rai, Binod K.; Morosan, E.

    2015-04-01

    Single crystals of (Lu{sub 1−x}Y b{sub x}){sub 3}Rh{sub 4}Ge{sub 13} were characterized by magnetization, specific heat, and electrical resistivity measurements. Doping Yb into the non-magnetic Lu{sub 3}Rh{sub 4}Ge{sub 13} compound tunes this cubic system’s properties from a superconductor with disordered metal normal state (x < 0.05) to a Kondo for 0.05 ≤ x ≤0.2 and intermediate valence at the highest Yb concentrations. The evidence for intermediate Yb valence comes from a broad maximum in the magnetic susceptibility and X-ray photoelectron spectroscopy. Furthermore, the resistivity displays a local maximum at finite temperatures at intermediate compositions x, followed by apparent metallic behavior closest to the Yb end compound in the series.

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

    SciTech Connect

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

    2011-12-01

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

  3. Engineering lattice matching, doping level, and optical properties of KY(WO4)2:Gd, Lu, Yb layers for a cladding-side-pumped channel waveguide laser

    NASA Astrophysics Data System (ADS)

    Aravazhi, Shanmugam; Geskus, Dimitri; van Dalfsen, Koop; Vázquez-Córdova, Sergio A.; Grivas, Christos; Griebner, Uwe; García-Blanco, Sonia M.; Pollnau, Markus

    2013-05-01

    Single-crystalline KY1- x-y-z GdxLuyYbz(WO4)2 layers are grown onto undoped KY(WO4)2 substrates by liquid-phase epitaxy. The purpose of co-doping the KY(WO4)2 layer with suitable fractions of Gd3+ and Lu3+ is to achieve lattice-matched layers that allow us to engineer a high refractive-index contrast between waveguiding layer and substrate for obtaining tight optical mode confinement and simultaneously accommodate a large range of Yb3+ doping concentrations by replacing Lu3+ ions of similar ionic radius for a variety of optical amplifier or laser applications. Crack-free layers, up to a maximum lattice mismatch of ~0.08 %, are grown with systematic variations of Y3+, Gd3+, Lu3+, and Yb3+ concentrations, their refractive indices are measured at several wavelengths, and Sellmeier dispersion curves are derived. The influence of co-doping on the spectroscopy of Yb3+ is investigated. As evidenced by the experimental results, the lattice constants, refractive indices, and transition cross-sections of Yb3+ in these co-doped layers can be approximated with good accuracy by weighted averages of data from the pure compounds. The obtained information is exploited to fabricate a twofold refractive-index-engineered sample consisting of a highly Yb3+-doped tapered channel waveguide embedded in a passive planar waveguide, and a cladding-side-pumped channel waveguide laser is demonstrated.

  4. Diauxic growth and microstructure of grain interfaces in thermal bonding Yb:LuAG/LuAG ceramic

    NASA Astrophysics Data System (ADS)

    Zhou, Chunlin; Jiang, Benxue; Fan, Jintai; Mao, Xiaojian; Zhang, Long; Fang, Yongzheng

    2015-07-01

    Transparent composite Lutetium aluminum garnet (LuAG) ceramics were successfully synthesized by thermal diffusion bonding method. Three isothermal holding temperature of 1450°C, 1600°C, 1780°C for 10h under vacuum were used to study the changes of bonding interface morphology, Optical microscope, SEM and laser interferometer (GPI-XP,zygo) study show that diauxic growth of grain interface appears when the thermal bonding holding temperature increased. The sintering mechanism of diauxic growth of grain interface during the thermal diffusion bonding was also discussed using diffusion theory. The diauxic growth of grain interface provides us the possibility to get high quality composite laser ceramics as we designed.

  5. Study of 57 Fe Mössbauer effect in RFe2Zn20 ( R = Lu, Yb, Gd)

    DOE PAGESBeta

    Bud’ko, Sergey L.; Kong, Tai; Ma, Xiaoming; Canfield, Paul C.

    2015-08-04

    In this document we report measurements of 57Fe Mössbauer spectra for RFe2Zn20 (R = Lu, Yb, Gd) from ~ 4.5 K to room temperature. The obtained isomer shift values are very similar for all three compounds, their temperature dependence was analyzed within the Debye model and resulted in an estimate of the Debye temperatures of 450-500 K. The values of quadrupole splitting at room temperature change with the cubic lattice constant a in a linear fashion. For GdFe2Zn20, ferromagnetic order is seen as an appearance of a sextet in the spectra. The 57Fe site hyperfine field for T → 0more » was evaluated to be ~ 2.4 T.« less

  6. Synthesis, Structures, and Vibrational Spectroscopy of the Two-Dimensional Iodates Ln(IO)3 and Ln(IO3)3(H2O) (Ln-Yb,Lu)

    SciTech Connect

    Assefa, Zerihun; Ling, Jie; Haire, Richard {Dick} G; Albrecht-Schmitt, Thomas E.; Sykora, Richard E.

    2006-01-01

    The reaction of Lu3+ or Yb3+ and H5IO6 in aqueous media at 180 C leads to the formation of Yb(IO3)3(H2O) or Lu(IO3)3(H2O), respectively, while the reaction of Yb metal with H5IO6 under similar reaction conditions gives rise to the anhydrous iodate, Yb(IO3)3. Under supercritical conditions Lu3+ reacts with HIO3 and KIO4 to yield the isostructural Lu(IO3)3. The structures have been determined by single-crystal X-ray diffraction. Crystallographic data are (MoKa, {lambda}=0.71073 {angstrom}): Yb(IO3)3, monoclinic, space group P21/n, a=8.6664(9) {angstrom}, b=5.9904(6) {angstrom}, c=14.8826(15) {angstrom}, {beta}=96.931(2){sup o}, V=766.99(13), Z=4, R(F)=4.23% for 114 parameters with 1880 reflections with I>2s(I); Lu(IO3)3, monoclinic, space group P21/n, a=8.6410(9), b=5.9961(6), c=14.8782(16) {angstrom}, {beta}=97.028(2){sup o}, V=765.08(14), Z=4, R(F)=2.65% for 119 parameters with 1756 reflections with I>2s(I); Yb(IO3)3(H2O), monoclinic, space group C2/c, a=27.2476(15), b=5.6296(3), c=12.0157(7) {angstrom}, {beta}=98.636(1){sup o}, V=1822.2(2), Z=8, R(F)=1.51% for 128 parameters with 2250 reflections with I>2s(I); Lu(IO3)3(H2O), monoclinic, space group C2/c, a=27.258(4), b=5.6251(7), c=12.0006(16) {angstrom}, {beta}=98.704(2){sup o}, V=1818.8(4), Z=8, R(F)=1.98% for 128 parameters with 2242 reflections with I>2s(I). The f elements in all of the compounds are found in seven-coordinate environments and bridged with monodentate, bidentate, or tridentate iodate anions. Both Lu(IO3)3(H2O) and Yb(IO3)3(H2O) display distinctively different vibrational profiles from their respective anhydrous analogs. Hence, the Raman profile can be used as a complementary diagnostic tool to discern the different structural motifs of the compounds.

  7. Crystallization of BaF2-ZnF2-YbF3-ThF4 glass

    NASA Technical Reports Server (NTRS)

    Garcia, Roberto; Doremus, Robert H.; Ko, Sen-Hou; Margraf, Tracey; Bansal, Narottam P.

    1988-01-01

    The phases and the rates of crystallization in a Ba-Zn-Yb-Th fluoride glass were studied using differential scanning calorimetry, XRD, and observational and chemical SEM analyses. The crystallizing phases that were identified included a BaYbTh fluoride, ZnF2, and YbF3. The BaYbTh fluoride crystallized first at about 450 C, and ZnF2, which was excluded from this phase, crystallized at its surfaces. At higher temperatures, the BaYbTh fluoride phase decomposed partially to BaThF6 and YbF3 phases.

  8. Characterization of vapour-transport-equilibrated Yb(/Er):LiNbO3 crystals

    NASA Astrophysics Data System (ADS)

    Zhang, De-Long; Wong, W. H.; Pun, E. Y. B.

    2004-11-01

    Visible and infrared absorption, Raman scattering, x-ray powder diffraction and scanning electron microscope (SEM) have been used to characterize Er/Yb (0.6 mol%/0.3 mol%) codoped and singly Yb-doped (1.2 mol%) Z-cut LiNbO3 crystals that were vapour-transport-equilibrated (VTE) at 1110 and 1120 °C for 100, 120 and 220 h in a Li-rich atmosphere. Optical absorption edge and 153 cm-1 E(TO) phonon linewidth have been used to roughly evaluate the composition of the crystals. The results obtained show that the VTE treatment has brought all crystals towards stoichiometric composition. As a relatively strong VTE condition was adopted, the treatment results in the formation of submicron-sized ErNbO4 (+YbNbO4) and YbNbO4 flat polyhedron-like precipitates in the Er/Yb:LiNbO3 and Yb:LiNbO3 crystals, respectively. On the other hand, a relatively weak VTE procedure cannot induce the precipitation of both the singly and doubly doped crystals. The characteristic optical absorptions, characteristic x-ray diffractions, crystalline structure and crystallographic morphology of the ErNbO4 and YbNbO4 precipitates are discussed, summarized and compared with those of singly Er-doped LiNbO3 crystals reported previously. The absorption characteristics of the unprecipitated Er/Yb codoped and singly Yb-doped crystals are also summarized and compared with the case of singly Er doping. An atomic force microscope has been used to further verify the SEM results and to evaluate the roughness of the surface of precipitated crystals. Optical absorption measurement was also carried out on a precipitated Er/Yb codoped crystal with polished surfaces to verify that the precipitates grow not only on the surface of the crystal but also in the bulk.

  9. Crystal growth, polarized spectra, and laser performance of Yb:CaGdAlO4 crystal

    NASA Astrophysics Data System (ADS)

    Di, J. Q.; Xu, X. D.; Xia, C. T.; Zheng, L. H.; Aka, G.; Yu, H. H.; Sai, Q. L.; Guo, X. Y.; Zhu, L.

    2016-04-01

    In this paper, the crystal growth, polarized spectra, and laser performance of Yb:CaGdAlO4 crystal were reported. The segregation coefficient of Yb3+ ions was calculated to be 0.47. The cell parameters were determined to be a  =  b  =  0.3658 nm, c  =  1.1985 nm. The peak absorption cross-section was calculated to be 2.65  ×  10-20 cm2 at 979 nm and the peak stimulated emission cross-section was 2.23  ×  10-20 cm2 at 980 nm for the π polarization. The continuous-wave (CW) laser operations of uncoated Yb:CaGdAlO4 crystals with 5  ×  5  ×  3 mm3 in size were demonstrated. A maximum output power of 1.6 W at 1048 nm was obtained with a slope efficiency of 28%. The results show that Yb:CaGdAlO4 crystal is a promising laser medium.

  10. Spectroscopic and thermal characterizations of Yb:LaF3 single crystal

    NASA Astrophysics Data System (ADS)

    Hong, Jiaqi; Zhang, Lianhan; Hang, Yin; Xu, Min

    2016-10-01

    A Yb3+ doped LaF3 laser crystal was detailed investigated by both spectroscopic and thermal measurements. A peak absorption at 974 nm with FWHM broader than 60 nm makes the crystal suitable to InGaAs LDs. Fluorescence spectrum and calculated spectroscopic parameters show potential of Yb:LaF3 crystal to laser operations around 1009 nm. A relatively long fluorescence lifetime of 2.92 ms was detected for Yb3+:2F5/2 manifold. The thermal diffusivity and specific heat capacity in the range of 300-575 K were studied to calculate the thermal conductivity of Yb:LaF3. The results indicate that the Yb:LaF3 crystal is a good candidate for diode-pumped ∼1 μm solid-state laser applications.

  11. The Effect of Phase Structures on the Enhanced Red Upconversion Luminescence in NaLuF4:Yb-Er Nanocrystals.

    PubMed

    Guo, Xingyuan; Song, Weiye; Bi, Xueqing; Liu, Shushen; Yin, Shengyan; Qin, Weiping

    2016-04-01

    In this work, α-NaLuF4:Yb,Er (NLF) nanocomposites (NCs) and β-NLF NCs with diameter about ~13 nm were fabricated by a high temperature decomposition reaction method. The effects of NLF structure on the enhanced red upconversion luminescence performance were investigated. Under 980 nm excitation from a laser diode, the α-NLF emitted dominant red UC emission. Furthermore, the possible energy transfer mechanism was proposed on the basis of our experimental results. PMID:27451747

  12. One-pot synthesis of PEG modified BaLuF₅:Gd/Yb/Er nanoprobes for dual-modal in vivo upconversion luminescence and X-ray bioimaging.

    PubMed

    Rao, Ling; Lu, Wei; Zeng, Tianmei; Yi, Zhigao; Wang, Haibo; Liu, Hongrong; Zeng, Songjun

    2014-09-21

    Polyethylene glycol (PEG) modified BaLuF5:Gd/Yb/Er upconversion nanoparticles (UCNPs) were synthesized by a facile one-pot hydrothermal method for simultaneous synthesis and surface functionalization. The novel, excellently biocompatible and water-soluble bioprobes were used for simultaneous upconversion (UC) luminescence and X-ray bioimaging for the first time. The as-prepared BaLuF5:Gd/Yb/Er UCNPs possess a face-centered cubic structure with an average size of 23.7 ± 2.7 nm. Under 980 nm laser excitation, these UCNPs emitted intense UC luminescence via a two-photon process. In vitro bioimaging and localized luminescence spectra detected from HeLa cells and the background reveal that these UCNPs are ideal candidates for optical bioimaging in the absence of autofluorescence. Furthermore, the synergistic in vivo UC luminescence and X-ray bioimaging reveal that these PEG-modified BaLuF5:Gd/Yb/Er UCNPs can be successfully used as ideal dual-modal bioprobes. These results demonstrate that these PEG modified UCNPs are ideal multi-modal nanoprobes for bioimaging.

  13. Near-infrared to visible upconversion in Tm3+ and Yb3+ codoped Lu2O3 nanocrystals synthesized by hydrothermal method.

    PubMed

    Li, Li; Zhang, Xingli; Wei, Xiantao; Wang, Guangchuan; Guo, Changxin

    2014-06-01

    Lutetium oxide nanocrystals codoped with Tm3+ and Yb3+ have been successfully synthesized via adjusting the pH values of the precursor solution in a hydrothermal method followed by a subsequent calcination process. The samples were systematically characterized by X-ray diffraction, field-emission scanning microscopy, Fourier transform infrared transmittance spectroscopy, and upconversion luminescent spectra. The experimental results show that the pH values of the precursor solution have great effects on the structural, morphological, and upconversion luminescent properties of Lu2O3:2%Yb3+, 0.2%Tm3+ nanocrystals. The as-formed lutetium oxide precursors could transform to cubic Lu2O3 with the same morphology and a slight shrinkage in size after a calcination process. The upconversion emission intensity of Lu2O3:2%Yb3+, 0.2%Tm3+ nanocrystals obtained from the precursor solution with pH = 9 is the strongest. The enhancement of the upconversion luminescence is suggested to be the consequence of reducing the number of OH- groups and the enlarged nanocrystals size. Strong blue and weak red emissions from the prepared nanocrystals were observed under 980 nm laser excitation, which were attributed to the 1G4 --> 3H6 and 1G4 --> 3F4 transitions of Tm3+ ion, respectively.

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

    SciTech Connect

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

    2015-04-21

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

  15. Lattice vibration and absorbance of Er:Yb:YCOB single crystals

    NASA Astrophysics Data System (ADS)

    Lu, Gui-Wu; Li, Chun-Xi; Wang, Wen-Chuan; Wang, Zi-Hao; Xia, Hai-Rui; Zhang, Huai-Jin; Meng, Xian-Lin; Li, Li-Xia

    2003-01-01

    Er 3+- and Yb 3+-doped yttrium calcium oxoborate Er:Yb:YCa 4O(BO 3) 3 (Er:Yb:YCOB) crystallizes with a fluorapatite-type structure in the monoclinic system. Its lattice vibrational modes were calculated by using space group theory, and Raman spectra were measured at room temperature with different scattering geometry projects. The experiments show that the characteristic lattice vibrational modes of Er:Yb:YCOB crystal arise mainly from the internal vibrations of the BO3, CaO6, and YO 6 groups. The three-dimensional network structure of Er:Yb:YCOB crystal is identified, and its excellent nonlinear optical (NLO) properties are mainly attributed to the BO 3 clusters that connects all the distorted YO 6 and CaO 6 octahedral clusters together. The combination of the strong absorption at 976 nm and the strong emission at 1537 nm makes this material very promising for use in an infrared laser system.

  16. Growth of Yb{sup 3+}-doped Y{sub 2}O{sub 3} single crystal rods by the micro-pulling-down method

    SciTech Connect

    Mun, J.H. . E-mail: mjh73@mail.tagen.tohoku.ac.jp; Novoselov, A.; Yoshikawa, A.

    2005-08-11

    The rare-earth sesquioxides (RE{sub 2}O{sub 3}, RE = Lu, Y and Sc) are very promising host crystals for advanced laser diode (LD)-pumped Yb{sup 3+}-doped solid-state lasers due to unusual combination, almost unique of favourable structural, thermal and spectroscopic properties which are described. In spite of these favourable properties, the bulk single crystal growth technology for the rare-earth sesquioxides has not been established yet. The extremely high melting temperature at around 2400 deg. C has prevented it. However, we shall show that yttrium oxide crystals (Yb {sub x}Y{sub 1-x}){sub 2}O{sub 3}, x = 0.0, 0.005, 0.05, 0.08 and 0.15 of cylindrical shape as laser rods with 4.2 mm in diameter and 15-20 mm in length have been grown from rhenium crucibles by the micro-pulling-down method. The crystal quality characterisation of undoped Y{sub 2}O{sub 3} crystal was determined using X-ray rocking curve (XRC) analysis. Yb were homogeneously distributed in Y{sub 2}O{sub 3} host crystal.

  17. Optimization of the cooling profile to achieve crack-free Yb:S-FAP crystals

    NASA Astrophysics Data System (ADS)

    Fang, H. S.; Qiu, S. R.; Zheng, L. L.; Schaffers, K. I.; Tassano, J. B.; Caird, J. A.; Zhang, H.

    2008-08-01

    Yb:S-FAP [Yb 3+:Sr 5(PO 4) 3F] crystals are an important gain medium for diode-pumped laser applications. Growth of 7.0 cm diameter Yb:S-FAP crystals utilizing the Czochralski (CZ) method from SrF 2-rich melts often encounters cracks during the post-growth cool-down stage. To suppress cracking during cool-down, a numerical simulation of the growth system was used to understand the correlation between the furnace power during cool-down and the radial temperature differences within the crystal. The critical radial temperature difference, above which the crystal cracks, has been determined by benchmarking the simulation results against experimental observations. Based on this comparison, an optimal three-stage ramp-down profile was implemented, which produced high-quality, crack-free Yb:S-FAP crystals.

  18. Optimization of the cooling profile to achieve crack-free Yb:S-FAP crystals

    SciTech Connect

    Fang, H; Qiu, S; Kheng, L; Schaffers, K; Tassano, J; Caird, J; Zhang, H

    2007-08-20

    Yb:S-FAP [Yb{sup 3+}:Sr{sub 5}(PO{sub 4}){sub 3}F] crystals are an important gain medium for diode-pumped laser applications. Growth of 7.0 cm diameter Yb:S-FAP crystals utilizing the Czochralski (CZ) method from SrF{sub 2}-rich melts often encounter cracks during the post growth cool down stage. To suppress cracking during cool down, a numerical simulation of the growth system was used to understand the correlation between the furnace power during cool down and the radial temperature differences within the crystal. The critical radial temperature difference, above which the crystal cracks, has been determined by benchmarking the simulation results against experimental observations. Based on this comparison, an optimal three-stage ramp-down profile was implemented and produced high quality, crack-free Yb:S-FAP crystals.

  19. Crystallization-Dependent Luminescence Properties of Ce:LuPO4.

    PubMed

    Sun, Congting; Li, Xingxing; Wang, Hao; Xue, Dongfeng

    2016-03-21

    The luminescence properties of Ce:LuPO4 depend on both the Ce(3+) center and the host lattice. In this article, we studied the dependence of the luminescence properties of Ce:LuPO4 on both the doping concentration of Ce(3+) and the size and morphology of the LuPO4 matrix at micro- and nanosize regimes. The crystalline behavior of Ce:LuPO4, including its size and shape, was investigated via precursor transformation crystallization. On the basis of this crystallization approach, Ce:LuPO4 hollow nanospheres, nanorods, and regular tetrahedrons were obtained. For micro- and nanostructured Ce:LuPO4, the surface-induced chemical bonding architecture can be effectively varied by controlling the size of the crystalline material and its geometry. Our experimental observations demonstrate that one-dimensional Ce:LuPO4 nanorods doped with 0.1 mol % Ce(3+) possess the best performance among the as-prepared samples. The significant anisotropy of Ce:LuPO4 nanorods can result in a larger specific surface area and enhanced luminescence properties. Moreover, the improved luminescence property of Ce:LuPO4 nanostructures can also be optimized by increasing the preferential anisotropic chemical bonding architecture to regulate the 5d level of Ce(3+). Our work also shows that the photoluminescence emission intensity of Ce:LuPO4 nanorods is increased as the surface area normal to their axial direction increases. From the standpoint of crystallization, the luminescence properties of Ce(3+) in nano- and microsize matrixes can be well-optimized by controlling the crystalline behavior of the host lattice under proper synthesis conditions. PMID:26863291

  20. Crystallization-Dependent Luminescence Properties of Ce:LuPO4.

    PubMed

    Sun, Congting; Li, Xingxing; Wang, Hao; Xue, Dongfeng

    2016-03-21

    The luminescence properties of Ce:LuPO4 depend on both the Ce(3+) center and the host lattice. In this article, we studied the dependence of the luminescence properties of Ce:LuPO4 on both the doping concentration of Ce(3+) and the size and morphology of the LuPO4 matrix at micro- and nanosize regimes. The crystalline behavior of Ce:LuPO4, including its size and shape, was investigated via precursor transformation crystallization. On the basis of this crystallization approach, Ce:LuPO4 hollow nanospheres, nanorods, and regular tetrahedrons were obtained. For micro- and nanostructured Ce:LuPO4, the surface-induced chemical bonding architecture can be effectively varied by controlling the size of the crystalline material and its geometry. Our experimental observations demonstrate that one-dimensional Ce:LuPO4 nanorods doped with 0.1 mol % Ce(3+) possess the best performance among the as-prepared samples. The significant anisotropy of Ce:LuPO4 nanorods can result in a larger specific surface area and enhanced luminescence properties. Moreover, the improved luminescence property of Ce:LuPO4 nanostructures can also be optimized by increasing the preferential anisotropic chemical bonding architecture to regulate the 5d level of Ce(3+). Our work also shows that the photoluminescence emission intensity of Ce:LuPO4 nanorods is increased as the surface area normal to their axial direction increases. From the standpoint of crystallization, the luminescence properties of Ce(3+) in nano- and microsize matrixes can be well-optimized by controlling the crystalline behavior of the host lattice under proper synthesis conditions.

  1. New criteria to choose the best Yb3+-doped laser crystals

    NASA Astrophysics Data System (ADS)

    Brenier, A.; Boulon, G.

    2001-09-01

    Using a model for the quasi-three-level laser dealing with Gaussian waves, taking into account the saturation of the pump, the stimulated emission at the pump wavelength, the variation of the pump and laser waists along propagation (important for laser diode pumping) and the variation of the laser intensity along propagation, we evaluate the more promising Yb3+-doped crystals for laser applications: YAG, LNB, GdCOB, YCOB, YAB, C-FAP, S-FAP, CLYPA, KGdW, KYW, Sc2O3, Y2O3, Lu2O3. Our evaluation, established for the CW oscillator regime, differs from that of Deloach and coworkers valid for ns pulse extraction mode. KYW, KGdW and Sc2O3 are found to be the most efficient when considering the laser extracted power and S-FAP, C-FAP, YAG, KYW and KGdW are the most efficient when considering the small-signal gain of the amplifier regime.

  2. New Yb-doped crystals for high-power and ultrashort lasers

    NASA Astrophysics Data System (ADS)

    Druon, F.; Boudeile, J.; Zaouter, Y.; Hanna, M.; Balembois, F.; Georges, P.; Petit, J.; Goldner, P.; Viana, B.

    2006-09-01

    Since the beginning of the 90's, Titanium Sapphire has become the crystal of choice for the development of ultrashort laser system producing very short and powerful pulses using the Chirped Pulse Amplification technique. In parallel to these developments leading to commercial products, new laser crystals have been studied in order to reach directly other wavelength range and to overcome the need to develop cw or pulsed green laser to pump the Titanium Sapphire crystal. In order to be able to directly pump the crystals with very efficient and high power semiconductor laser, new crystals doped with ytterbium ions have been developed. Actually, in the field of femtosecond lasers, an intense interest has been shown for ytterbium-doped laser-crystals. These crystals are now well-known to be particularly suitable for very efficient, directly-diode-pumped, solid state femtosecond oscillators. However, it has been shown that the spectral properties of the Yb 3+ dopant strongly depend on the matrix host and a lot of works have been done to find the "ideal" matrix allowing both ultrashort-pulsed and high-power lasers. Firstly, in order to take advantage of the very high-power laser diodes available to pump Yb-doped materials, ideal crystals need to be able to hold high power pumping; so high thermal conductivity is required (>5W/m/K, typically). Secondly, to generate very short pulses (<100 fs) ideal crystals have to demonstrate very broad and smooth spectra. Among the numerous Yb-doped crystals already studied, many failed with one of these two contradictory criteria (contradictory because broad spectra are often synonymous of high disorder in the host lattice and the good thermal conductivity requires an ordered matrix to allow good propagation of phonons). In this paper, we are relating the performance of a new Yb-doped crystal: Yb:CaGdAlO4 (Yb:CALGO) and how it takes place in this quest of "ideal" crystal. Actually, this very new crystal allowed, to our best knowledge

  3. Enhancement of Tb-Yb quantum cutting emission by inverse opal photonic crystals

    NASA Astrophysics Data System (ADS)

    Wang, Qi; Qiu, Jianbei; Song, Zhiguo; Yang, Zhengwen; Yin, Zhaoyi; Zhou, Dacheng; Wang, Siqin

    2016-04-01

    Yb3+, Tb3+ co-doped YPO4 inverse opal photonic crystal was prepared directly by sol-gel technique in combination with self-assembly method. With the influence of the photonic band gap, quantum cutting emission of Tb3+, Yb3+ was investigated in photonic crystals by photoluminescence and fluorescence lifetime. The result clearly shows that, when the spontaneous emission of donor Tb3+ is inhibited by photonic band gap, Tb3+-Yb3+ quantum cutting quantum efficiency from Tb3+ to Yb3+ could be enhanced from 131.2% to 140.5%. The mechanisms for the influence of the photonic band gap on quantum cutting process of Tb3+ and Yb3+ are discussed. We believe that the present work will be valuable for the foundational study of quantum cutting energy transfer process and application of quantum cutting optical devices in spectral modification materials for silicon solar cells.

  4. Synthesis, crystal structure and physical properties of Yb11Bi10 -xSnx

    NASA Astrophysics Data System (ADS)

    Liang, Ying; Cardoso-Gil, Raul; Schnelle, Walter; Zhao, Jing-Tai; Grin, Yuri

    2013-04-01

    The intermetallic phase Yb11Bi10 -xSnx (x = 0 and 4.8) crystallizing in the Ho11Ge10 structure type was synthesized and characterized. The crystal structure was established by single-crystal X-ray diffraction data in the tetragonal space group I4/mmm (no.139), Pearson code tI84, Z = 4, a = 12.2043(4) Å, c = 17.7227(9) Å, and V = 2639.7(2) Å3, Rgt(F) = 0.040, 763 observed reflections for Yb11Bi10, and a = 12.0183(5) Å, c = 17.413(1) Å, and V = 2515.1(2) Å3, Rgt(F) = 0.027, 762 observed reflections for Yb11Bi5.2Sn4.8. The crystal structure of Yb11Bi10 contains three discrete anionic moieties: isolated Bi3- anions, Bi24- dimers and Bi44- squares. In Yb11Bi5.2Sn4.8, the square units are formed solely by Sn, and the structure shows a mixed Bi/Sn occupancy at the 8i and 16m Wyckoff sites. Magnetization measurements show that the title phase contains ytterbium exclusively in the 4f14 configuration up to 400 K. The Yb-LIII X-ray absorption spectrum attests also the presence of Yb with a 4f14 (Yb2+) configuration for Yb11Bi10, while the average valence of ytterbium was found to be 2.09 for Yb11Bi5.2Sn4.8.

  5. Synthesis and spectroscopic characterization of Yb3+ in Ca1-XYbXF2+X crystals

    NASA Astrophysics Data System (ADS)

    Ito, M.; Goutaudier, C.; Guyot, Y.; Lebbou, K.; Fukuda, T.; Boulon, G.

    2004-11-01

    Ca1-XYbXF2+X crystals were grown by two different methods: simple melting under CF{4} atmosphere and laser heated pedestal growth (LHPG) method under Ar atmosphere. Spectroscopic characterization has been carried out to separate different crystallographic site in Ca1-XYbXF2+X crystals and to identify Stark's levels of Yb3+ transitions. Experimental decay time dependence of Yb3+ concentration was analyzed by using concentration gradient fiber in order to understand concentration quenching mechanisms. Energy transfer to unexpected rare earth impurities observed by up-conversion emission spectra in visible region under IR Yb3+ ion pumping seems to be an efficient process.

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

    NASA Astrophysics Data System (ADS)

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

    2015-05-01

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

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

    SciTech Connect

    Sonnauer, Andreas

    2008-11-15

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

  8. Spectroscopic and laser characterization of Yb,Tm:KLu(WO4)2 crystal

    NASA Astrophysics Data System (ADS)

    Loiko, P. A.; Serres, J. M.; Mateos, X.; Demesh, M. P.; Yasukevich, A. S.; Yumashev, K. V.; Petrov, V.; Griebner, U.; Aguiló, M.; Díaz, F.

    2016-01-01

    We report on a comprehensive spectroscopic and laser characterization of monoclinic Yb,Tm:KLu(WO4)2 crystals. Stimulated-emission cross-section spectra corresponding to the 3F4 → 3H6 transition of Tm3+ ions are determined. The radiative lifetime of the 3F4 state of Tm3+ ions is 0.82 ms. The maximum Yb3+ → Tm3+ energy transfer efficiency is 83.9% for 5 at.% Yb - 8 at.% Tm doping. The fractional heat loading for Yb,Tm:KLu(WO4)2 is 0.45 ± 0.05. Using a hemispherical cavity and 5 at.% Yb - 6 at.% Tm doped crystal, a maximum CW power of 227 mW is achieved at 1.983-2.011 μm with a maximum slope efficiency η = 14%. In the microchip laser set-up, the highest slope efficiency is 20% for a 5 at.% Yb- 8 at.% Tm doped crystal with a maximum output power of 201 mW at 1.99-2.007 μm. Operation of Yb,Tm:KLu(WO4)2 as a vibronic laser emitting at 2.081-2.093 μm is also demonstrated.

  9. Optical waveguide formed in Yb:GdCOB and Yb:YCOB crystals by 3.0MeV O+ implantation

    NASA Astrophysics Data System (ADS)

    Jiao, Yang

    2013-07-01

    Planar optical waveguides were formed in Yb:GdCOB and Yb:YCOB crystals by 3.0 MeV O+ ion implantation at fluence of 2 × 1015 ions/cm2 at room temperature, respectively. The prism coupling method was performed to characterize the dark-mode property of the waveguides. The refractive index profiles in the waveguides were reconstructed by reflectivity calculation method (RCM). The results show that after the implantation, a 1.5 μm-wide region with enhanced refractive-index was formed beneath the sample surfaces to act as waveguide structures for both Yb:GdCOB and Yb:YCOB.

  10. Nanostructured crystals of the fluorite phases Sr{sub 1-x}R{sub x}F{sub 2+x}(R-rare-earth elements) and their ordering: II. Crystal structure of the ordered Sr{sub 4}Lu{sub 3}F{sub 17} phase

    SciTech Connect

    Sulyanova, E. A. Molchanov, V. N.; Verin, I. A.; Sulyanov, S. N.; Sobolev, B. P.

    2009-05-15

    The crystal structure of the ordered phase Sr{sub 4}Lu{sub 3}F{sub 17} prepared by directed crystallization of the melt has been investigated. The crystals have a trigonally distorted fluorite lattice (space group R3-bar, Z = 6, a = 10.615(2) A, c = 19.547(6) A). The Sr{sub 4}Lu{sub 3}F{sub 17} phase is isostructural to Ba{sub 4}R{sub 3}F{sub 17} (R = Y, Yb). The distortions of the fluorite cation sublattice manifest themselves in the splitting of the only mixed position (Sr, Lu) into three positions: Sr(1), Sr(2), and Lu. All Lu{sup 3+} atoms are displaced from the center of the [Sr{sub 8}{l_brace}Lu{sub 6}F{sub 36+1}{r_brace}F{sub 32}] octacubic cluster in the [001]{sub cub} direction, and the Sr(1) cations are displaced toward the center of the octacubic cluster in the [111]{sub cub} direction. The coordination numbers of the Lu, Sr(1), and Sr(2) cations are 8, 10, and 11, respectively. The distortions of the fluorite anion sublattice are caused by the incorporation of additional anions into both the center of the octacubic cluster and the {l_brace}F{sub 8}{r_brace} cubic holes outside the cluster.

  11. Solvothermal synthesis and upconversion properties of about 10 nm orthorhombic LuF₃: Yb³⁺, Er³⁺ rectangular nanocrystals.

    PubMed

    Xiang, Guotao; Zhang, Jiahua; Hao, Zhendong; Zhang, Xia; Pan, Guo-Hui; Chen, Li; Luo, Yongshi; Lü, Shaozhe; Zhao, Haifeng

    2015-12-01

    The Yb(3+) and Er(3+) codoped orthorhombic LuF3 rectangular nanocrystals (NCs) with the size of about 10nm were synthesized by a facile and effective solvothermal process. X-ray diffraction (XRD), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), upconversion (UC) luminescence spectra and decay curves were used to characterize the resulting samples. Compared with YF3 and α-NaYF4 NCs, owning the similar size and the same doping levels of Yb(3+) ions and Er(3+) ions as LuF3 NCs, the green UC emission of LuF3 NCs is 18.7 times and 5.1 times stronger than that of YF3 and α-NaYF4 NCs respectively; the red UC emission of LuF3 NCs is 13.2 times and 0.6 times stronger than that of YF3 and α-NaYF4 NCs respectively. Under 980 nm wavelength excitation, the decay curves of both (4)S3/2→(4)I15/2 transition and (4)F9/2→(4)I15/2 transition exhibit a single exponential function, resulting from the fast energy migrations among Yb(3+) ions caused by the high concentration of Yb(3+) ions (20 mol%). Meanwhile, at relatively low power density, the slopes of the linear plots between log(I) and log(P) for green UC and red UC are 1.7 and 1.9 respectively, which are less than 2 due to the quenching of the thermal effect, indicating a two-photon process for them. At high power density, the slopes are decreased caused by the saturation effect. In addition, we proved the existence of the thermal effect by the pump power dependence of the intensity ratio of (2)H11/2→(4)I15/2 transition to (4)S3/2→(4)I15/2 transition. PMID:26298284

  12. Method for preparing high specific activity 177Lu

    SciTech Connect

    Mirzadeh, Saed; Du, Miting; Beets, Arnold L.; Knapp, Jr., Furn F.

    2004-04-06

    A method of separating lutetium from a solution containing Lu and Yb, particularly reactor-produced .sup.177 Lu and .sup.177 Yb, includes the steps of: providing a chromatographic separation apparatus containing LN resin; loading the apparatus with a solution containing Lu and Yb; and eluting the apparatus to chromatographically separate the Lu and the Yb in order to produce high-specific-activity .sup.177 Yb.

  13. Crystal structure, physical properties and bond valence analysis of NaLuP2O7

    NASA Astrophysics Data System (ADS)

    Béjaoui, Anis; Horchani-Naifer, Karima; Hajji, Mounir; Férid, Mokhtar

    2014-05-01

    Single crystals of a diphosphate NaLuP2O7 have been synthesized by the flux method and characterized by single-crystal X-Ray diffraction. NaLuP2O7 crystallizes in the monoclinic system with P21/n space group with cell parameters: a = 8.9985(8) Å, b = 5.3473(5) Å, c = 12.756(1) Å, β = 103.174° (1), V = 597.67 (9) Å3, Z = 4. Its structure consists of a three-dimensional framework of P2O7 units that are corner-shared by LuO6 octahedra, forming tunnels running parallel to [010] which are occupied by Na atoms. NaLuP2O7 powder was characterized by XRD, SEM, FTIR and Raman spectroscopy. The activation energy of (1.49 eV) obtained by electrical measurements suggests the charge carriers to be the sodium cations. The activation energies obtained from impedance and loss spectra were analyzed in order to explain the mechanism of conduction. The correlation between ionic conductivity of NaLuP2O7 and its crystallographic structure was investigated and the most probable transport pathway model was determined.

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

    SciTech Connect

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

    2012-12-15

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

  15. [Study on Spectral Characteristics of Two Kinds of Home-Made Novel Yb-Doped Fluoride Laser Crystals].

    PubMed

    Xu, Wen-bin; Chai, Lu; Shi, Jun-kai; Song, You-jian; Hu, Ming-lie; Wang, Qing-yue; Su, Liang-bi; Jiang, Da-peng; Xu, Jun

    2015-09-01

    Yb-doped fluoride crystals are of important another Yb-doped laser materials besides Yb-doped oxide, which are becoming one of interests for developing tunable lasers and ultrafast lasers. In this paper, the systematic and contrastive experiments of the optical spectral characteristics are presented for two types of home-made novel Yb-doped fluoride laser crystals, namely, Yb-doped CaF2-SrF2 mixed crystal and co-doped Yb, Y:CaF2 single crystal. The fluorescent features of Yb-doped CaF2-SrF2 mixed crystal and co-doped Yb, Y:CaF2 single crystal are apparently different by the fluorescence experiment. The physical mechanism of these fluorescence spectra were analyzed and proposed. The influence of doping concentrations of active Yb(3+) ions or co-doping Y ions on the absorption of Yb-doped CaF2-SrF2 mixed crystal and co-doped Yb, Y:CaF2 single crystal was experimentally investigated, and the optimal values of doping concentrations of active Yb(3+) ions or co-doping Y ions in the two types of fluoride laser crystals were obtained. Continuous-wave laser operation for the two novel fluoride laser crystals has been achieved in three-mirror-folded resonator using a laser diode as the pump source. Therein, the laser operation for the co-doped Yb, Y:CaF2 crystal is demonstrated for the first time. For the two types of fluoride laser crystals (four samples), the input-output power relational curves, the optical slope efficiencies and the laser spectra were demonstrated by the laser experiments. By comparisons between the two types of fluoride laser crystals in the absorbability, fluorescence and laser spectra, laser threshold and slope efficiency of the continuous-wave laser operation, the results show that the best one of the four samples in spectral and laser characteristics is co-doped 3at%Yb, 6at% Y:CaF2 single crystal, which has an expected potential in the application. The research results provide available references for improving further laser performance of Yb

  16. Effects of gamma-irradiation and air annealing on Yb-doped Y3Al5O12 single crystal.

    PubMed

    Zeng, Xionghui; Xu, Xiaodong; Wang, Xiaodan; Zhao, Zhiwei; Zhao, Guangjun; Xu, Jun

    2008-03-01

    The effects of gamma-irradiation on the air-annealed 10at.% Yb:Y(3)Al(5)O(12) (YAG) and air annealing on the gamma-irradiated 10at.% Yb:YAG have been studied by the difference absorption spectra before and after treatment. The gamma-irradiation and air annealing led to opposite changes of the absorption properties of the Yb:YAG crystal. After air annealing, the gamma-irradiation induced centers were totally removed and the concentration of Fe(3+) and Yb(3+) were lightly increased. For the first time, the gamma-irradiation induced valence changes between Yb(3+) and Yb(2+) ions in Yb:YAG crystals have been observed.

  17. Passive mode-locking of acentric Yb-doped borate crystals

    NASA Astrophysics Data System (ADS)

    Petrov, V.; Mateos, X.; Schmidt, A.; Rivier, S.; Griebner, U.; Zhang, H.; Wang, J.; Li, J.; Liu, J.

    2010-05-01

    Passive mode locking of the self-frequency doubling Yb:YAB and Yb:YCOB crystals with a saturable absorber mirror is studied at the fundamental wavelength with diode pumping. All essential polarization orientations including the self-frequency doubling configuration are considered. For the first time sub-90 fs pulses at the fundamental are obtained with both materials and the improvement in terms of pulse length in comparison to previous work is about 2.3 times (Yb:YAB) and 2.8 times (Yb:YCOB). The Yb:YAB laser generates pulses as short as 87 fs at 1050 nm with a 0.4% output coupler. The shortest pulses (76 fs) are obtained with a Y-cut Yb:YCOB for E ∥ Z. With an output coupler of 0.4% the oscillation wavelength is 1056 nm. For E ∥ X the mode-locked Yb:YCOB laser operates on a different Stark transition (at longer wavelengths) than for E ∥ gg and E ∥ Z.

  18. Characterization of Pr:LuAG scintillating crystals for X-ray spectroscopy

    NASA Astrophysics Data System (ADS)

    Bertoni, R.; Bonesini, M.; Cervi, T.; Clemenza, M.; De Bari, A.; Falcone, A.; Mazza, R.; Menegolli, A.; Nastasi, M.; Rossella, M.

    2016-07-01

    The main features of the Pr doped Lu3Al5O12 (Pr:LuAG) scintillating crystals for X-ray spectroscopy applications have been studied using different radioactive sources and photo-detectors. Pr:LuAG is cheaper, compared to a Germanium detector, but with remarkable properties which make it useful for many applications, from fundamental physics measurements to the PET imaging for medical purposes: high density, elevate light yield, fast response, high energy resolution, no hygroscopicity. A sample of Pr:LuAG crystals with 14 mm×14 mm surface area and 13 mm thickness and a NaI crystal of the same surface and 26 mm thickness used as a reference have been characterized with several radioactive sources, emitting photons in the range 100-1000keV. Different light detectors were adopted for the Pr:LuAG studies, sensitive to its UV emission (peak at 310 nm): a 3 in. PMT (Hamamatsu R11065) and new arrays of Hamamatsu SiPM S13361, with siliconic resin as a window. Preliminary results are presented on the performance of the Pr:LuAG crystals, to be mounted in a 2 × 2 array to be tested in the 2015 run of the FAMU experiment at RIKEN-RAL muon facility. The goal is the detection of the X-rays (around 130 keV) emitted during the de-excitation processes of the muonic hydrogen after the excitation with an IR laser with wavelength set at the resonance of the hyperfine splitting, to measure the muonic atom proton radius with unprecedented precision.

  19. Spectroscopy and laser performance of Nd:Lu_2O_3 crystal

    NASA Astrophysics Data System (ADS)

    Hao, Liangzhen; Wu, Kui; Cong, Hengjiang; Yu, Haohai; Zhang, Huaijin; Wang, Zhengping; Wang, Jiyang

    2011-08-01

    The spectra of Nd3+:Lu2O3 crystal have been examined at room temperature. Judd-Ofelt theory was applied to calculate the spectral parameters of the crystal. With a laser diode as pump source, a continuous-wave laser output power of 2.81 W is achieved, which is the highest value ever reported in this crystals to our knowledge, and its wavelength is also found to be dual-wavelength. Because of the emission cross-section at 1076 nm and 1080 nm are almost identical, laser oscillation for such two wavelengths can be obtained simultaneously. All the properties show that Nd:Lu2O3 is an excellent crystal for laser applications.

  20. Purification of precursors of Yb3+-doped YLF crystals by solvent extraction and electrochemical processing

    NASA Astrophysics Data System (ADS)

    Boncher, William L.; Judge, Elizabeth; Sansinena, Jose-Maria; Dirmyer, Matthew R.; Hehlen, Markus P.

    2015-03-01

    Optical refrigeration by laser irradiation of YLiF4:Yb3+ (YLF:Yb) crystals has been shown to be strongly deteriorated by impurities, which absorb energy at the laser wavelength, and relax non-radiatively, negating cooling produced from anti-Stokes fluorescence. We aim to increase the efficiency of optical refrigeration through materials purification. We start with the purest sources commercially available and process them in a cleanroom environment. Our method proceeds through electrochemical purification, separating out the transition metal impurities by their redox potentials, and can be scaled up to produce the amounts of material needed for crystal growth.

  1. Origin of Quantum Criticality in Yb-Al-Au Approximant Crystal and Quasicrystal

    NASA Astrophysics Data System (ADS)

    Watanabe, Shinji; Miyake, Kazumasa

    2016-06-01

    To get insight into the mechanism of emergence of unconventional quantum criticality observed in quasicrystal Yb15Al34Au51, the approximant crystal Yb14Al35Au51 is analyzed theoretically. By constructing a minimal model for the approximant crystal, the heavy quasiparticle band is shown to emerge near the Fermi level because of strong correlation of 4f electrons at Yb. We find that charge-transfer mode between 4f electron at Yb on the 3rd shell and 3p electron at Al on the 4th shell in Tsai-type cluster is considerably enhanced with almost flat momentum dependence. The mode-coupling theory shows that magnetic as well as valence susceptibility exhibits χ ˜ T-0.5 for zero-field limit and is expressed as a single scaling function of the ratio of temperature to magnetic field T/B over four decades even in the approximant crystal when some condition is satisfied by varying parameters, e.g., by applying pressure. The key origin is clarified to be due to strong locality of the critical Yb-valence fluctuation and small Brillouin zone reflecting the large unit cell, giving rise to the extremely-small characteristic energy scale. This also gives a natural explanation for the quantum criticality in the quasicrystal corresponding to the infinite limit of the unit-cell size.

  2. Simultaneously optimizing fluorescent and paramagnetic properties of bifunctional NaGdF{sub 4}:Yb{sup 3+}/Er{sup 3+} nanocrystals by crystal field tuning

    SciTech Connect

    Wu, Xiaofeng; Hu, Shigang; Tan, Congbing; Liu, Yunxin

    2015-04-15

    Graphical abstract: Crystal field tuning is a powerful approach for simultaneously enhancing the optical and magnetic properties of lanthanide-doped NaGdF{sub 4} bi-functional nanocrystals. - Abstract: Here, we show the simultaneous enhancement of fluorescent and paramagnetic properties in bifunctional NaGdF{sub 4}:Yb{sup 3+}/Er{sup 3+} nanocrystals by crystal field tuning. The energy level splitting calculation indicates, that lanthanide ionic pairs La{sup 3+}/Lu{sup 3+} introduced into the NaGdF{sub 4} host can modify the crystal field around emitters (e.g., Er{sup 3+} and Tm{sup 3+}) and sensitizers (e.g., Yb{sup 3+}) that result in the broadening of crystal field splitting of energy levels and the abundant multi-site distribution of upconversion luminescence. The optimization of the paramagnetic properties in NaGdF{sub 4} doped with emitters and sensitizers is ascribed to the lowering of anti-ferromagnetic coupling.

  3. Scintillation properties of a La, Lu-admix gadolinium pyrosilicate crystal

    NASA Astrophysics Data System (ADS)

    Kurosawa, Shunsuke; Shishido, Toetsu; Suzuki, Akira; Sugawara, Takamasa; Nomura, Akiko; Yubuta, Kunio; Shoji, Yasuhiro; Yokota, Yuui; Pejchal, Jan; Ohashi, Yuji; Kamada, Kei; Yoshikawa, Akira

    2015-06-01

    In order to obtain new scintillator with higher effective atomic number, a pyrosilicate crystal with a composition (Ce0.01, Gd0.54, La0.25, Lu0.20)2Si2O7 (Ce:LaLu-GPS) was grown by the floating zone method. Emission wavelengths of this material were at 370 and 390 nm. Gamma-ray-excited pulse height and scintillation decay measurement showed that Ce:LaLu-GPS had a light output of 34,000±2000 photons/MeV, an FWHM energy resolution of 6.9±0.2%, and the decay time components of 59±1 ns (13%) and 570±20 ns (87%).

  4. Luminescent and lasing characteristics of heavily doped Yb{sup 3+}:KY(WO{sub 4}){sub 2} crystals

    SciTech Connect

    Kisel', V E; Troshin, A E; Shcherbitskii, V G; Kuleshov, N V; Pavlyuk, A A; Brunner, F; Paschotta, R; Morier-Genoud, F; Keller, U

    2006-04-30

    The luminescence decay times are measured taking into account reabsorption for KY(WO{sub 4}){sub 2}:Yb(KYW:Yb) crystals with atomic concentrations of active ions from 0.2% to 30%. The radiative lifetime of Yb{sup 3+} ions was measured to be 233 {mu}s. The cw output power of 1.46 and 1.62 W was achieved with the slope efficiency 52% and 47% for Yb:KYW lasers with the atomic concentration of Yb{sup 3+} ions equal to 10% and 30%, respectively. Using a semiconductor mirror with a saturable absorber (SESAM) in the passive mode-locking regime, pulses of duration 194 and 180 fs were obtained at wavelengths of 1042 and 1039 nm for crystals with Yb{sup 3+} concentrations equal to 10% and 30%, respectively, the average output power being 0.63 and 0.75 W. (lasers and amplifiers)

  5. Progress in the Growth of Yb:S-FAP Laser Crystals

    SciTech Connect

    Schaffers, K I; Tassano, J B; Waide, P A; Payne, S A; Morris, R C

    2000-07-01

    The crystal growth of Yb:S-FAP [Yb{sup 3+}:Sr{sub 5}(PO{sub 4}){sub 3}F] is being studied for 1.047-{micro}m laser operation. These crystals are not yet routinely available and the growth of high optical quality, low loss crystals poses a challenge due to a number of crystal growth issues, including, cloudiness, bubble core defects, anomalous absorption, low-angle grain boundaries, and cracking. At this time, a growth process has been formulated to simultaneously eliminate or greatly diminish each of the defects yielding high quality material. Laser slabs of dimension 4.0 x 6.0 x 0.75 cm are being fabricated from sub-scale pieces using the diffusion bonding technique.

  6. Characterization and comparison of 1% at Yb-doped Lu2O3 and Sc2O3 ceramics as laser gain media

    NASA Astrophysics Data System (ADS)

    Pirri, A.; Toci, G.; Vannini, M.

    2012-12-01

    We present the first laser oscillation achieved on Yb-doped Sc2O3 and Lu2O3 ceramics with a level of doping as low as 1 at %, under quasi-continuous wave pumping at 968 nm. Ceramic samples reached comparable performances in terms of tunability ranges, which exceeds 41 nm, and laser output powers. In particular, with the former sample emitting at 1040.5 nm we measured a maximum output power of 2.2 W with a corresponding slope efficiency of η = 59%. The latter medium delivered 1.8 W with a slope of η = 45% at 1032.5 nm while at 1078 nm we measured 1.5 W with η = 34%. Finally, we report the measured level of the Amplified Spontaneous Emission (ASE) for both samples, which was found to be less than 0.1 mW at the maximum pump power.

  7. Green up-converted luminescence in (Er3+-Yb3+) co-doped LiNbO3 crystals

    NASA Astrophysics Data System (ADS)

    Stoffel, M.; Rinnert, H.; Kokanyan, E.; Demirkhanyan, G.; Demirkhanyan, H.; Aillerie, M.

    2016-07-01

    Er3+ doped and (Er3+-Yb3+) co-doped LiNbO3 (LN) crystals grown by the Czochralski method are investigated by photoluminescence spectroscopy. Green up-converted luminescence is observed in Er3+ doped LN crystals under 980 nm excitation. This is explained by an energy transfer between two neighboring Er3+ ions. In (Er3+, Yb3+) co-doped LN crystals, the intensity of the green up-converted luminescence can be further enhanced suggesting that Yb3+ ions also contribute to the up-conversion process. Time resolved photoluminescence measurements clearly demonstrate that an efficient energy transfer occurs between Yb3+ and Er3+ ions. A theoretical model taking into account the contribution of both Er3+-Er3+ pairs and Yb3+-Er3+ pairs is able to describe correctly the decay of the up-converted luminescence.

  8. Quantum efficiency of energy transfers in non-uniformly doped crystals of Er, Yb: LiNbO3

    NASA Astrophysics Data System (ADS)

    Nalbantov, N. N.; Stroganova, E. V.; Galutskiy, V. V.

    2016-08-01

    Spatial and temporal distribution of quantum efficiency of energy transfers in crystals of lithium niobate with non-uniform concentration profiles of Er3+ and Yb3+ ions has been studied for the cases of Yb3+-Er3+ Foerster transfer and radiative decay of upper energy levels of erbium ions (green and red luminescence).

  9. PHOTONIC CRYSTAL SURFACE ENHANCED UPCONVERSION EMISSION OF YF3:Yb3+, Er3+ NANOPARTICLES

    NASA Astrophysics Data System (ADS)

    Shao, Bo; Yang, Zhengwen; Li, Jun; Liao, Jiayan; Lai, Shenfeng; Qiu, Jianbei; Song, Zhiguo; Yang, Yong; Zhou, Dacheng

    2015-11-01

    The opal photonic crystals made of polystyrene microspheres with 155, 230, 270 or 410 nm in diameter were used to enhance upconversion (UC) emission of YF3:Yb3+, Er3+ nanoparticles, respectively. The red or green UC emission of YF3:Yb3+, Er3+ nanoparticles can be selectively enhanced when the red or green UC emission wavelength overlapped with the photonic bandgaps of opals, which is attributed to Bragg reflection of photonic bandgap. In addition, when the 980 nm excitation light wavelength was in the region of the photonic bandgap, red and green UC emissions of YF3:Yb3+, Er3+ nanoparticles were enhanced due to the enhancement of excitation field.

  10. Microchip laser based on Yb:YAG/V:YAG monolith crystal

    NASA Astrophysics Data System (ADS)

    Nejezchleb, Karel; Šulc, Jan; Jelínková, Helena; Škoda, Václav

    2016-03-01

    V:YAG crystal was investigated as a passive Q-switch of longitudinally diode-pumped microchip laser, emitting radiation at wavelength 1030.5 nm. This laser was based on diffusion bonded monolith crystal (diameter 3 mm) which combines in one piece an active laser part (Yb:YAG crystal, 10 at.% Yb/Y, 3 mm long) and saturable absorber (V:YAG crystal, 2 mm long, initial transmission 86 % @ 1031 nm). The microchip resonator consisted of dielectric mirrors directly deposited on the monolith surfaces (pump mirror HT @ 968 nm and HR @ 1031 nm on Yb:YAG part, output coupler with reflection 55 % @ 1031 nm on the V:YAG part). For longitudinal CW pumping of Yb:YAG part, a fibre coupled (core diameter 100 μm, NA = 0.22, emission @ 968 nm) laser diode was used. The laser threshold was 3.8W. The laser slope efficiency for output mean in respect to incident pumping was 16 %. The linearly polarized generated transversal intensity beam profile was close to the fundamental Gaussian mode. The generated pulse length, stable and mostly independent on pumping power, was equal to 1.3 ns (FWHM). The single pulse energy was increasing with the pumping power and for the maximum pumping 9.7W it was 78 μJ which corresponds to the pulse peak-power 56 kW. The maximum Yb:YAG/V:YAG microchip laser mean output power of 1W was reached without observable thermal roll-over. The corresponding Q-switched pulses repetition rate was 13.1 kHz.

  11. Yb/Er co-doped phosphate all-solid single-mode photonic crystal fiber.

    PubMed

    Wang, Longfei; He, Dongbing; Feng, Suya; Yu, Chunlei; Hu, Lili; Qiu, Jianrong; Chen, Danping

    2014-01-01

    An all-solid Yb(3+)/Er(3+) co-doped single-mode phosphate photonic crystal fiber (PCF) with Watt-level output power and 20 μm core diameter is demonstrated for the first time. A PCF whose refractivity of the active core is lower than that of the background glass is suggested and theoretically confirmed to be in single-mode operation at 40 μm core diameter.

  12. Emission characteristics of near-stoichiometric Er/Yb-codoped LiNbO3 crystals

    NASA Astrophysics Data System (ADS)

    Zhang, De-Long; Pun, E. Y. B.

    2006-01-01

    Polarized visible, near-infrared, and 980-nm up-conversion emission characteristics in near-stoichiometric Z-cut Er(0.6 mol %)/Yb(0.3 mol %)-codoped LiNbO3 crystals, prepared by vapor-transport-equilibration (VTE) technique, were investigated and discussed in comparison with corresponding as-grown crystal, thermally calcined ErNbO4 powder, as well as Z-cut only Er(2.0 mol %)-doped LiNbO3 crystal that was subjected to the same VTE procedure as one of the Er/Yb-codoped crystals. The VTE-induced crystalline phase transformation is discussed in combination with optical absorption results reported previously. The percentage of Er3+ ions present in the crystals as the ErNbO4 phase is evaluated based upon the optical absorption and the emission data at 1.5 μm. An empirical expression for evaluating the Li composition in a near-stoichiometric Er(/Yb)-doped LiNbO3 crystal from the narrowing percentage of the σ- or α-polarized 1530 nm emission peak is established based upon the emission spectra of singly Er-doped VTE LiNbO3 crystals. From the measured absorption band areas and the Judd-Ofelt theory, the influence of the VTE treatment on the Er3+ spectroscopic property was studied. The experimentally observed VTE effect on the emission intensity is conducted with the theoretical results of the transition probability. Both the theoretical and experimental results reveal that the VTE treatment results in the lengthening of the 1.5 μm lifetime as much as 15%. A mechanism that the VTE treatment induces the crystalline phase transformation and the reduction of both OH- and intrinsic defect contents is proposed to explain the VTE effect on the lifetime.

  13. Conduction electron spin resonance in the α-Yb1-xFexAlB4 (0 ⩽ x ⩽ 0.50) and α-LuAlB4 compounds

    NASA Astrophysics Data System (ADS)

    Holanda, L. M.; Lesseux, G. G.; Magnavita, E. T.; Ribeiro, R. A.; Nakatsuji, S.; Kuga, K.; Fisk, Z.; Oseroff, S. B.; Urbano, R. R.; Rettori, C.; Pagliuso, P. G.

    2015-06-01

    β-YbAlB4 has become one of the most studied heavy fermion systems since its discovery due to its remarkable physical properties. This system is the first reported Yb-based heavy-fermion superconductor (HFS) for which the low-T superconducting state emerges from a non-fermi-liquid (NFL) normal state associated with quantum criticality Nakatsuji et al 2008 Nature 4 603. Additionally, it presents a striking and unprecedented electron spin resonance (ESR) signal which behaves as a conduction electron spin resonance (CESR) at high temperatures and acquires features of the Yb3+ local moment ESR at low temperatures. The latter, also named Kondo quasiparticles spin resonance (KQSR), has been defined as a 4f-ce strongly coupled ESR mode that behaves as a local probe of the Kondo quasiparticles in a quantum critical regime, Holanda et al 2011 Phys. Rev. Lett. 107 026402. Interestingly, β-YbAlB4 possesses a previously known structural variant, namely the α-YbAlB4, phase which is a paramagnetic Fermi liquid (FL) at low temperatures Macaluso et al 2007 Chem. Mater. 19 1918. However, it has been recently suggested that the α-YbAlB4 phase may be tuned to NFL behavior and/or magnetic ordering as the compound is doped with Fe. Here we report ESR studies on the α-Yb1-xFexAlB4 (0 ⩽ x ⩽ 0.50) series as well as on the reference compound α-LuAlB4. For all measured samples, the observed ESR signal behaves as a CESR in the entire temperature range (10 K ≲ T ≲ 300 K) in clear contrast with what has been observed for β-YbAlB4. This striking result indicates that the proximity to a quantum critical point is crucial to the occurrence of a KQSR signal.

  14. Crystal structures and magnetic properties of lanthanide containing borates LnM(BO{sub 3}){sub 2} (Ln=Y, Ho–Lu; M=Sc, Cr)

    SciTech Connect

    Doi, Yoshihiro Satou, Tatsuya; Hinatsu, Yukio

    2013-10-15

    The synthesis, crystal structures and magnetic properties of LnM(BO{sub 3}){sub 2} (Ln=Y, Ho–Lu; M=Sc, Cr) were investigated. The LnCr(BO{sub 3}){sub 2} compounds crystallize in the dolomite-type structure with space group R3{sup ¯}, in which the Ln and Cr ions occupy two octahedral sites. From the result of structural analysis, it was found that there is an anti-site disorder between these two sites and its chemical formula is more exactly Ln{sub 1−r}Cr{sub r}[Cr{sub 1−r}Ln{sub r}](BO{sub 3}){sub 2}. On the other hand, the LnSc(BO{sub 3}){sub 2} adopt the calcite-type structure with space group R3{sup ¯}c. The Ln and Sc ions randomly occupy an octahedral site and the chemical formula is represented as (Ln{sub 0.5}Sc{sub 0.5})BO{sub 3}. From the magnetic susceptibility and specific heat measurements, we found that all the LnCr(BO{sub 3}){sub 2} show an antiferromagnetic transition at 6.1–8.1 K. This transition is mainly due to the ordering of Cr{sup 3+} magnetic moments. Among the compounds with magnetic Ln{sup 3+} ions, only YbCr(BO{sub 3}){sub 2} shows an antiferromagnetic ordering of Ln{sup 3+} ion at 2.1 K. - Graphical abstract: The lanthanide containing borates LnM(BO{sub 3}){sub 2} (Ln=Y, Ho–Lu; M=Sc, Cr) have the dolomite-type (Ln=Cr) and calcite-type (Ln=Sc) structures. Both structures are similar to each other except for the difference in the partially or fully disordered arrangements of octahedral sites. At low temperatures, the LnCr(BO{sub 3}){sub 2} compounds show an antiferromagnetic transition due to a long-range ordering of Cr{sup 3+} moments. Among them only YbCr(BO{sub 3}){sub 2} shows an antiferromagnetic ordering of Ln{sup 3+} ion at 2.1 K. Display Omitted - Highlights: • Lanthanide containing borates LnM(BO{sub 3}){sub 2} (Ln=Y, Ho–Lu; M=Sc, Cr) have been synthesized. • LnCr(BO{sub 3}){sub 2} has the dolomite-type structure with an anti-site disorder between Ln and Cr sites. • LnSc(BO{sub 3}){sub 2} has the calcite

  15. 2.7 μm emission properties of Er3+/Yb3+/Eu3+: SrGdGa3O7 and Er3+/Yb3+/Ho3+: SrGdGa3O7 crystals

    NASA Astrophysics Data System (ADS)

    Xia, Houping; Feng, Jianghe; Ji, Yuexia; Sun, Yijian; Wang, Yan; Jia, Zhitai; Tu, Chaoyang

    2016-04-01

    Er3+/Yb3+/Eu3+: SrGdGa3O7 and Er3+/Yb3+/Ho3+: SrGdGa3O7 crystals were grown by Czochralski technology and detailed spectroscopic analyses were carried out. It was found that the spectra of Er3+/Yb3+/Eu3+: SrGdGa3O7 crystal show weaker near-infrared emission and stronger mid-infrared emission as compared with Er3+/Yb3+: SrGdGa3O7 crystal. Furthermore, the lifetime of the 4I13/2 state decreases from 10.58 ms in Er3+/Yb3+: SrGdGa3O7 crystal to 6.87 ms in Er3+/Yb3+/Eu3+: SrGdGa3O7 crystal, that is, the self-saturation for 2.7 μm laser in Er3+/Yb3+/Eu3+: SrGdGa3O7 crystal is suppressed greatly. These results indicate that the doping of Eu3+ in Er3+/Yb3+: SrGdGa3O7 crystal is beneficial to improve the 2.7 μm laser. In contrast, introducing Ho3+ in Er3+/Yb3+: SrGdGa3O7 crystal is adverse to realize Er3+-activated MIR laser operation. So Er3+/Yb3+/Eu3+: SrGdGa3O7 crystal could be a potential MIR gain media for enhanced 2.7 μm laser.

  16. Efficient OPSL-pumped mode-locked Yb:Lu2O3 laser with 67% optical-to-optical efficiency

    NASA Astrophysics Data System (ADS)

    Heuer, Alexander M.; Saraceno, Clara J.; Beil, Kolja; Huber, Günter; Kränkel, Christian

    2016-01-01

    We present a mode-locked Yb:Lu2O3 laser with up to 67% of optical-to-optical efficiency. By utilizing a high brightness optically pumped semiconductor laser (OPSL) as a pump source and using a semiconductor saturable absorber mirror (SESAM) we obtained self-starting mode locking. A pulse duration of 571 fs at 4.73 W of average output power with an optical-to-optical efficiency of 67% was achieved. In a slightly different cavity configuration the pulse duration was reduced to 313 fs at 2.16 W of average output power. In both cases the pulse duration was longer than the Fourier limit and the spectrum supports significantly shorter pulse durations. The laser wavelength is centered at 1034 nm and the repetition rate is 100.76 MHz in both cases. In continuous wave fundamental mode operation the optical-to-optical efficiency was as high as 78% with output powers exceeding 5 W.

  17. Efficient OPSL-pumped mode-locked Yb:Lu2O3 laser with 67% optical-to-optical efficiency.

    PubMed

    Heuer, Alexander M; Saraceno, Clara J; Beil, Kolja; Huber, Günter; Kränkel, Christian

    2016-01-01

    We present a mode-locked Yb:Lu2O3 laser with up to 67% of optical-to-optical efficiency. By utilizing a high brightness optically pumped semiconductor laser (OPSL) as a pump source and using a semiconductor saturable absorber mirror (SESAM) we obtained self-starting mode locking. A pulse duration of 571 fs at 4.73 W of average output power with an optical-to-optical efficiency of 67% was achieved. In a slightly different cavity configuration the pulse duration was reduced to 313 fs at 2.16 W of average output power. In both cases the pulse duration was longer than the Fourier limit and the spectrum supports significantly shorter pulse durations. The laser wavelength is centered at 1034 nm and the repetition rate is 100.76 MHz in both cases. In continuous wave fundamental mode operation the optical-to-optical efficiency was as high as 78% with output powers exceeding 5 W. PMID:26739546

  18. Efficient OPSL-pumped mode-locked Yb:Lu2O3 laser with 67% optical-to-optical efficiency

    PubMed Central

    Heuer, Alexander M.; Saraceno, Clara J.; Beil, Kolja; Huber, Günter; Kränkel, Christian

    2016-01-01

    We present a mode-locked Yb:Lu2O3 laser with up to 67% of optical-to-optical efficiency. By utilizing a high brightness optically pumped semiconductor laser (OPSL) as a pump source and using a semiconductor saturable absorber mirror (SESAM) we obtained self-starting mode locking. A pulse duration of 571 fs at 4.73 W of average output power with an optical-to-optical efficiency of 67% was achieved. In a slightly different cavity configuration the pulse duration was reduced to 313 fs at 2.16 W of average output power. In both cases the pulse duration was longer than the Fourier limit and the spectrum supports significantly shorter pulse durations. The laser wavelength is centered at 1034 nm and the repetition rate is 100.76 MHz in both cases. In continuous wave fundamental mode operation the optical-to-optical efficiency was as high as 78% with output powers exceeding 5 W. PMID:26739546

  19. High-efficiency broadband anti-Stokes emission from Yb3+-doped bulk crystals.

    PubMed

    Zhu, Siqi; Wang, Chunhao; Li, Zhen; Jiang, Wei; Wang, Yichuan; Yin, Hao; Wu, Lidan; Chen, Zhenqiang; Zhang, Ge

    2016-05-15

    We investigate the broadband anti-Stokes emission (BASE) from Yb3+-doped crystals with a laser diode (LD) pumping at 940 nm. Our experiment reveals that Yb3+-doped crystals with random cracks are able to generate bright BASE at room temperature and atmospheric pressure. By examining the various characteristics of the crystals and the emitted light, we supply a theory for interpreting the underlying physics for this variety of BASE. In particular, we take into consideration the effects of energy migration, avalanche process, and charge-transfer luminescence. This represents the first time, to the best of our knowledge, that BASE was obtained from Yb3+-doped bulk crystals with a high optical-optical efficiency. PMID:27176947

  20. Near infrared quantum cutting of Na+ and Eu2+-Yb3+ couple activated SrF2 crystal

    NASA Astrophysics Data System (ADS)

    Yagoub, M. Y. A.; Swart, H. C.; Dhlamini, M. S.; Coetsee, E.

    2016-10-01

    Na+ and Eu2+-Yb3+ couple activated SrF2 phosphor powders were synthesized by the co-precipitation method. The structure and luminescence properties of the system were investigated. X-ray diffraction data indicated that a mixture of cubic SrF2 and NaYbF4 phases gradually formed with an increase in the Yb3+ ion doping concentration. Diffuse reflectance has been used to confirm the existence of europium in the divalent state. The possibility of quantum cutting in the Eu2+-Yb3+ ions co-doped SrF2 crystal was discussed. Energy transfer that occurred subsequently from Eu2+ to Yb3+ was followed by an intense near-infrared (NIR) (∼1000 nm) emission spectral range. Emission spectra and the fluorescence decay measurements have been utilized to demonstrate the cooperative energy transfer in the Eu2+-Yb3+ couple ions. The energy transfer was completed at high concentration and the Yb3+ ions emission's intensity was reduced as a result of concentration quenching. In addition from the photoluminescence data it was also evident that Na+ induced a significant change to the NIR emission.

  1. Large-mode-area Yb3+-doped photonic crystal fiber laser

    NASA Astrophysics Data System (ADS)

    Yan, Pei-Guang; Zhang, Wei; Li, Yi-Gang; Zhu, Jianping; Ding, Lei; Chen, Sheng-Ping; Lu, Kecheng; Dong, Susan

    2005-01-01

    In this paper a large mode area Yb3+-doped double cladding photonic crystal fiber laser is reported. The laser's output power reaches as high as 4.3W. The slope efficiency and the maximum optical-to-optical efficiency of laser output are 69.4% and 59.7%, respectively, with respect to absorbed pump power. Single transverse mode operation is obtained at central wavelength of 1072.3nm and the measured mode distribution agrees with the simulation by using scalar beam propagation method.

  2. Crystal growth, frequency doubling, and infrared laser performance of Yb{sup 3+}:BaCaBO{sub 3}F

    SciTech Connect

    Schaffers, K.I.; DeLoach, L.D.; Payne, S.A.

    1996-05-01

    Yb:BaCaBO{sub 3}F (Yb:BCBF) has been investigated as a new laser crystal with potential for self-frequency doubling. Yb{sup 3+} in BCBF exhibits a minimum absorption cross section at 912 nm of 1.1 {times} 10{sup {minus}20} cm{sup 2} with a bandwidth (FWHM) of 19 nm. The maximum emission cross section at 1034 nm is 1.3 {times} 10{sup {minus}20} cm{sup 2} with a transition bandwidth of 24 nm. The measured emission lifetime of Yb{sup 3+} is 1.17 ms. An Yb:BCBF laser has been demonstrated with a Ti:sapphire pump source, and a measured slope efficiency of 38% has been obtained for the fundamental laser output. Single crystal powders of BCBF have been compared with KD*P for a relative measure of the second-harmonic generating potential, yielding d{sub eff} (BCBF) {approximately}0.26 pm/V. The phasematching angle has been estimated from the refractive index data for type 1 second-harmonic generation of 0.517 {micro}m light; the predicted angle is 37{degree} from the c-axis. The growth, spectroscopy, laser performance, and linear and nonlinear optical properties of Yb:BCBF are reported.

  3. Crystal structure and chemical bonding of the intermetallic Zintl phase Yb[subscript 11]AlSb[subscript 9

    SciTech Connect

    Kastbjerg, Sofie; Uvarov, Catherine A.; Kauzlarich, Susan M.; Chen, Yu-Sheng; Nishibori, Eiji; Spackman, Mark A.; Iversen, Bo Brummerstedt

    2012-10-09

    High resolution single crystal synchrotron X-ray diffraction data measured at 15(2) K were used to solve the structure of the complex intermetallic Zintl phase, Yb{sub 11}AlSb{sub 9} (space group Iba2), made up of Yb cations and polyanions along with isolated Sb anions. The 15(2) K cell parameters are a = 11.7383(4) {angstrom}, b = 12.3600(4) {angstrom}, c = 16.6796(6) {angstrom}. The temperature dependence of the structure was investigated through high resolution synchrotron powder X-ray diffraction (PXRD) data measured from 90 K to 1000 K. Rietveld refinements of the crystal structure revealed near linear thermal expansion of Yb{sub 11}AlSb{sub 9} with expansion coefficients of 1.49(2) x 10{sup -5} K{sup -1}, 1.71(3) x 10{sup -5} K{sup -1}, 1.13(1) x 10{sup -5} K{sup -1} for a, b and c, respectively. The chemical bonding in Yb{sub 11}AlSb{sub 9} was analyzed using atomic Hirshfeld surfaces, and the analysis supports the presence of the structural elements of Yb cations, [AlSb{sub 4}]{sup 9-} tetrahedra, [Sb{sub 2}]{sup 4-} dimers and isolated Sb{sup 3-} anions. However, indications of interatomic interactions between the Zintl anions and the Yb cations were also observed.

  4. Magnetic remanence in Yb14-xRExMnSb11 (RE=Tb, Dy, Ho) single crystals

    NASA Astrophysics Data System (ADS)

    Grebenkemper, Jason H.; Hu, Yufei; Abdusalyamova, M. N.; Makhmudov, F. A.; Kauzlarich, Susan M.

    2016-06-01

    Single crystals of Yb14-xRExMnSb11 (x~0.1, 0.4; RE = Tb, Dy, Ho) have been prepared as a solid solution by Sn flux reactions of the elements. They crystallize in the Ca14AlSb11 structure type in the I41/acd space group. The RE3+preferentially substitutes on the Yb(1) site which is the smallest volume Yb containing polyhedron. In the case of Ho3+, a small amount of Ho3+ also substitutes on the Yb(4) site. The ferromagnetic ordering temperature of Yb14MnSb11 is reduced from 53 K to 41 K as x increases and dependent on the identity of the RE. This is attributed to the reduction in carriers and reduced screening of the Mn2+ local moment. The effective moments, μeff, agree well with the calculated moments assuming the RE substitutes as a trivalent cation. The largest coercive field is observed for RE = Dy (1000 Oe). For the maximum x of Yb14-xRExMnSb11 there are enough carriers for the Ruderman-Kittel-Kasuya-Yosida (RKKY) mechanism of magnetic coupling via conduction electrons to still be valid in describing the ferromagnetic ordering.

  5. Rare-Earth Triangular Lattice Spin Liquid: A Single-Crystal Study of YbMgGaO4.

    PubMed

    Li, Yuesheng; Chen, Gang; Tong, Wei; Pi, Li; Liu, Juanjuan; Yang, Zhaorong; Wang, Xiaoqun; Zhang, Qingming

    2015-10-16

    YbMgGaO4, a structurally perfect two-dimensional triangular lattice with an odd number of electrons per unit cell and spin-orbit entangled effective spin-1/2 local moments for the Yb(3+) ions, is likely to experimentally realize the quantum spin liquid ground state. We report the first experimental characterization of single-crystal YbMgGaO4 samples. Because of the spin-orbit entanglement, the interaction between the neighboring Yb(3+) moments depends on the bond orientations and is highly anisotropic in the spin space. We carry out thermodynamic and the electron spin resonance measurements to confirm the anisotropic nature of the spin interaction as well as to quantitatively determine the couplings. Our result is a first step towards the theoretical understanding of the possible quantum spin liquid ground state in this system and sheds new light on the search for quantum spin liquids in strong spin-orbit coupled insulators.

  6. 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)

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

    2011-09-01

    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.

  7. White light emission from Dy3+-doped LiLuF4 single crystal grown by Bridgman method

    NASA Astrophysics Data System (ADS)

    Dong, Yan-ming; Xia, Hai-ping; Fu, Li; Li, Shan-shan; Gu, Xue-mei; Zhang, Jian-li; Wang, Dong-jie; Zhang, Yue-pin; Jiang, Hao-chuan; Chen, Bao-jiu

    2014-07-01

    Lithium lutetium fluoride (LiLuF4) single crystals doped with different Dy3+ ion concentrations were grown by Bridgman method. The Judd-Ofelt (J-O) strength parameters ( Ω 2, Ω 4, Ω 6) of Dy3+ in LiLuF4 crystal are calculated according to the measured absorption spectra and the J-O theory, by which the asymmetry of the Dy3+:LiLuF4 single crystal and the possibility of attaining stimulated emission from 4F9/2 level are analyzed. The capability of the Dy3+:LiLuF4 crystal in generating white light by simultaneous blue and yellow emissions under excitation with ultraviolet light is produced. The effects of excitation wavelength and doping concentration on chromaticity coordinates and photoluminescence intensity are also investigated. Favorable CIE coordinates, x=0.319 3 and y=0.349 3, can be obtained for Dy3+ ion in 2.701% molar doping concentration under excitation of 350 nm.

  8. High-power Yb:YAG single-crystal fiber amplifiers for femtosecond lasers in cylindrical polarization.

    PubMed

    Lesparre, Fabien; Gomes, Jean Thomas; Délen, Xavier; Martial, Igor; Didierjean, Julien; Pallmann, Wolfgang; Resan, Bojan; Eckerle, Michael; Graf, Thomas; Abdou Ahmed, Marwan; Druon, Frederic; Balembois, François; Georges, Patrick

    2015-06-01

    We demonstrate a three-stage diode-pumped Yb:YAG single-crystal-fiber amplifier to generate femtosecond pulses at high average powers with linear or cylindrical (i.e., radial or azimuthal) polarization. At a repetition rate of 20 MHz, 750-fs pulses were obtained at an average power of 85 W in cylindrical polarization and at 100 W in linear polarization. The report includes investigations on the use of Yb:YAG single-crystal fibers with different length/doping ratio and the zero-phonon pumping at a wavelength of 969 nm in order to optimize the performance. PMID:26030546

  9. Investigation on the structure and upconversion fluorescence of Yb3+/Ho3+ co-doped fluorapatite crystals for potential biomedical applications

    PubMed Central

    Li, Xiyu; Zhu, Jingxian; Man, Zhentao; Ao, Yingfang; Chen, Haifeng

    2014-01-01

    Rare-earth Yb3+ and Ho3+ co-doped fluorapatite (FA:Yb3+/Ho3+) crystals were prepared by hydrothermal synthesis, and their structure, upconversion properties, cell proliferation and imaging were investigated. The synthesized crystals, with a size of 16 by 286 nm, have a hexagonal crystal structure of classic FA and a Ca/Yb/Ho molar ratio of 100/16/2.1. Several reasonable Yb3+/Ho3+ -embedding lattice models along the fluorine channel of the FA crystal cell are proposed for the first time, such as models for (Ca7YbHo©)(PO4)6F2 and (Ca6YbHoNa2)(PO4)6F2. The activated FA:Yb3+/Ho3+ crystals were found to exhibit distinct upconversion fluorescence. The 543- and 654-nm signals in the emission spectra could be assigned, respectively, to the 5F4 (5S2) - 5I8 and 5F5 - 5I8 transitions of holmium via 980-nm near-infrared excitation and the energy transfer of ytterbium. After the surfaces were grafted with hydrophilic dextran, the crystals displayed clear fluorescent cell imaging. Thus, the prepared novel FA:Yb3+/Ho3+ upconversion fluorescent crystals have potential applications in the biomedical field. PMID:24658285

  10. Radiation effects on Yb:YLF crystals used in cryogenic optical refrigerators

    NASA Astrophysics Data System (ADS)

    Martin, K. W.; Melgaard, S.; Cowan, V. M.; Hubbs, J.; Fraser, T.; Sheik-Bahae, M.

    2015-09-01

    Optical cooling of solids is a promising and innovative method to provide cryogenic cooling to infrared sensors. Currently insulator crystals, specifically ytterbium-doped yttrium- lithium-fluoride (Yb:YLF), have shown the most promise for cooling to low temperatures. This method has demonstrated cooling below the National Institute of Standards and Technology (NIST) cryogenic temperature definition of less than 123 K. Optical refrigeration utilizes a phenomenon called anti-Stokes fluorescence to generate cooling power. Incident laser light is absorbed by the cooling crystal and photons are spontaneously emitted at a higher, and thus more energetic, frequency. The difference in frequency is proportional to the cooling power of the crystal. Anti-Stokes cooling is highly dependent on doping percentages and YLF crystal purity and structure. Space based infrared sensors and their coolers are operated in a radiation environment where protons, gamma, rays, heavy ions, and other radiation species are common and of varying severities depending on operational orbit. To ensure that radiative effects on cooling crystal performance are minimal, we irradiated two samples with 63 MeV protons to a total of ionized dose of 100 Krad (Si) and 1 Mrad (Si), and compared cooling crystal efficiency parameters before and after dosing.

  11. Anisotropic laser properties of Yb:Ca3La2(BO3)4 disordered crystal

    NASA Astrophysics Data System (ADS)

    Wang, Lisha; Xu, Honghao; Pan, Zhongben; Han, Wenjuan; Chen, Xiaowen; Liu, Junhai; Yu, Haohai; Zhang, Huaijin

    2016-08-01

    A study is carried out experimentally on the anisotropy in the laser action of Yb:Ca3La2(BO3)4 disordered crystal, demonstrated with the output coupling changed over a wide range from 0.5% to 40%. Complex polarization state variation with output coupling and evolution with pump power are observed in the laser operation achieved with a- and c-cut crystal samples. A maximum output power of 8.2 W is produced at wavelengths around 1043 nm, with an incident pump power of 24.9 W, the optical-to-optical efficiency being 33%. The polarized absorption and emission cross section spectra are also presented.

  12. Color Tunable and Upconversion Luminescence in Yb-Tm Co-Doped Yttrium Phosphate Inverse Opal Photonic Crystals.

    PubMed

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

    2016-04-01

    For this paper, YPO4: Tm, Yb inverse opals with the photonic band gaps at 475 nm and 655 nm were prepared by polystyrene colloidal crystal templates. We investigated the influence of photonic band gaps on the Tm-Yb upconversion emission which was in the YPO4: Tm Yb inverse opal photonic crystals. Comparing with the reference sample, significant suppression of both the blue and red upconversion luminescence of Tm3+ ions were observed in the inverse opals. The color purity of the blue emission was improved in the inverse opal by the suppression of red upconversion emission. Additionally, mechanism of upconversion emission in the inverse opal was discussed. We believe that the present work will be valuable for not only the foundational study of upconversion emission modification but also the development of new optical devices in upconversion lighting and display. PMID:27451700

  13. Color Tunable and Upconversion Luminescence in Yb-Tm Co-Doped Yttrium Phosphate Inverse Opal Photonic Crystals.

    PubMed

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

    2016-04-01

    For this paper, YPO4: Tm, Yb inverse opals with the photonic band gaps at 475 nm and 655 nm were prepared by polystyrene colloidal crystal templates. We investigated the influence of photonic band gaps on the Tm-Yb upconversion emission which was in the YPO4: Tm Yb inverse opal photonic crystals. Comparing with the reference sample, significant suppression of both the blue and red upconversion luminescence of Tm3+ ions were observed in the inverse opals. The color purity of the blue emission was improved in the inverse opal by the suppression of red upconversion emission. Additionally, mechanism of upconversion emission in the inverse opal was discussed. We believe that the present work will be valuable for not only the foundational study of upconversion emission modification but also the development of new optical devices in upconversion lighting and display.

  14. Lasing Yb3+ in crystals with a wavelength dependence anisotropy displayed from La2CaB10O19

    NASA Astrophysics Data System (ADS)

    Brenier, A.; Wu, Y.; Zhang, J.; Wu, Y.

    2012-04-01

    We report spectroscopic and laser properties for propagation directions outside the principal axes of Yb3+-doped low symmetry laser crystals with a special devotion to the wavelength dependence anisotropy. We illustrate our report with experimental data in the 900-1075 nm range of wavelengths from the Yb3+:La2CaB10O19 monoclinic crystal excited under laser diode pumping at 975 nm. This study, which makes easier the realization of Yb3+ lasers with an efficient free-running operation at the wavelength having the highest emission intensity or at a specified wavelength, or emitting two frequencies with a specified frequency difference, is of promising interest for applications.

  15. Ammonothermal Synthesis, Crystal Structure, and Properties of the Ytterbium(II) and Ytterbium(III) Amides and the First Two Rare-Earth-Metal Guanidinates, YbC(NH)3 and Yb(CN3H4)3.

    PubMed

    Görne, Arno L; George, Janine; van Leusen, Jan; Dück, Gerald; Jacobs, Philipp; Chogondahalli Muniraju, Naveen Kumar; Dronskowski, Richard

    2016-06-20

    We report the oxidation-controlled synthesis of the ytterbium amides Yb(NH2)2 and Yb(NH2)3 and the first rare-earth-metal guanidinates YbC(NH)3 and Yb(CN3H4)3 from liquid ammonia. For Yb(NH2)2, we present experimental atomic displacement parameters from powder X-ray diffraction (PXRD) and density functional theory (DFT)-derived hydrogen positions for the first time. For Yb(NH2)3, the indexing proposal based on PXRD arrives at R3̅, a = 6.2477(2) Å, c = 17.132(1) Å, V = 579.15(4) Å(3), and Z = 6. The oxidation-controlled synthesis was also applied to make the first rare-earth guanidinates, namely, the doubly deprotonated YbC(NH)3 and the singly deprotonated Yb(CN3H4)3. YbC(NH)3 is isostructural with SrC(NH)3, as derived from PXRD (P63/m, a = 5.2596(2) Å, c = 6.6704(2) Å, V = 159.81(1) Å(3), and Z = 2). Yb(CN3H4)3 crystallizes in a structure derived from the [ReO3] type, as studied by powder neutron diffraction (Pn3̅, a = 13.5307(3) Å, V = 2477.22(8) Å(3), and Z = 8 at 10 K). Electrostatic and hydrogen-bonding interactions cooperate to stabilize the structure with wide and empty channels. The IR spectra of the guanidinates are compared with DFT-calculated phonon spectra to identify the vibrational modes. SQUID magnetometry shows that Yb(CN3H4)3 is a paramagnet with isolated Yb(3+) (4f(13)) ions. A CONDON 2.0 fit was used to extract all relevant parameters. PMID:27248288

  16. Laser performance of in-band pumped Er : LiYF4 and Er : LiLuF4 crystals

    NASA Astrophysics Data System (ADS)

    Gorbachenya, K. N.; Kurilchik, S. V.; Kisel, V. E.; Yasukevich, A. S.; Kuleshov, N. V.; Nizamutdinov, A. S.; Korableva, S. L.; Semashko, V. V.

    2016-02-01

    Spectroscopic properties of Er : LiLuF4 and Er : LiYF4 crystals in the spectral region near 1.5 μm and the lasing characteristics of these crystals under in-band pumping at a wavelength of 1522 nm are studied. With the Er : LiLuF4 crystal, the maximum slope efficiency with respect to the absorbed pump power was 44% at a wavelength of 1609 nm. Continuous-wave operation of an inband pumped Er : LiYF4 laser is obtained for the first time. The output power at a wavelength of 1606 nm was 58 mW with a slope efficiency of 21%.

  17. Crystallization and preliminary X-ray diffraction analysis of the flax cytokinin oxidase LuCKX1.1

    PubMed Central

    Wan, Li; Williams, Simon J.; Zhang, Xiaoxiao; Ericsson, Daniel J.; Koeck, Markus; Dodds, Peter N.; Ellis, Jeffrey G.; Kobe, Bostjan

    2013-01-01

    The plant hormones cytokinins play a central role in regulating cell division and developmental events. Cytokinin oxidase regulates the levels of these plant hormones by catalyzing their irreversible oxidation, which contributes to the regulation of various morpho-physiological processes controlled by cytokinins. In this study, the crystallization and preliminary X-ray diffraction analysis of the flax cytokinin oxidase LuCKX1.1 are reported. Plate-like crystals of LuCKX1.1 were obtained using PEG 3350 as a precipitant and diffracted X-rays to 1.78 Å resolution. The protein crystals have the symmetry of space group C2 and are most likely to contain two molecules per asymmetric unit. PMID:24100555

  18. Crystal growth and luminescence properties of Yb2Si2O7 infra-red emission scintillator

    NASA Astrophysics Data System (ADS)

    Horiai, Takahiko; Kurosawa, Shunsuke; Murakami, Rikito; Pejchal, Jan; Yamaji, Akihiro; Shoji, Yasuhiro; Chani, Valery I.; Ohashi, Yuji; Kamada, Kei; Yokota, Yuui; Yoshikawa, Akira

    2016-08-01

    (CexYb1-x)2Si2O7 (x = 0.00, 0.01) single crystals were grown by the micro-pulling-down method to test the possibility of its application as infra-red scintillator for medical imaging. Powder X-ray diffraction analysis indicated that the crystals were single-phase materials. The radioluminescence spectra of the crystals demonstrated presence of two near infra-red emission peaks (at 1010 and 1030 nm). The emission peaks at 420 and 580 nm ascribed to defects were also observed in the crystals. The human body has maximum transmission in wavelength range from 650 to 1200 nm. Therefore, Yb2Si2O7 is expected to be used as efficient infra-red scintillator for medical applications.

  19. Electric polarization observed in single crystals of multiferroic Lu2MnCoO6

    NASA Astrophysics Data System (ADS)

    Chikara, S.; Singleton, J.; Bowlan, J.; Yarotski, D. A.; Lee, N.; Choi, H. Y.; Choi, Y. J.; Zapf, V. S.

    2016-05-01

    We report electric polarization and magnetization measurements in single crystals of double perovskite Lu2Mn Co O6 using pulsed magnetic fields and optical second harmonic generation in dc magnetic fields. We observe well-resolved magnetic field-induced changes in the electric polarization in single crystals and thereby resolve the question about whether multiferroic behavior is intrinsic to these materials or is an extrinsic feature of polycrystals. We find electric polarization along the crystalline b axis, that is suppressed by applying a magnetic fields along the c axis, and advance a model for the origin of magnetoelectric coupling. We furthermore map the phase diagram using both capacitance and electric polarization to identify regions of ordering and regions of magnetoelectric hysteresis. This compound is a rare example of coupled hysteretic behavior in the magnetic and electric properties. The ferromagneticlike magnetic hysteresis loop that couples to hysteretic electric polarization can be attributed not to ordinary ferromagnetic domains, but to the rich physics of magnetic frustration of Ising-like spins in the axial next-nearest-neighbor interaction model.

  20. Spectroscopic properties of KGd(WO 4) 2: (Er, Yb) single crystals studied by Brillouin scattering method

    NASA Astrophysics Data System (ADS)

    Kasprowicz, D.; Drozdowski, M.; Majchrowski, A.; Michalski, E.

    2007-09-01

    The study of KGW: (Er, Yb) was performed for the acoustic phonons [1 0 0], [0 0 1], [-1 0 1], [1 0 1], [1 1 0] and [0 1 1]. In some Brillouin spectra obtained at room temperature we observed additional modes connected with mixed polarization modes propagating as quasi-longitudinal or quasi-transverse phonons which is characteristic for low symmetry crystals. Moreover, it has been revealed, that the value of Brillouin shift and integral intensity of the longitudinal phonon [1 0 1] propagating in KGW: (Er, Yb) show the anomaly at about 175 K.

  1. SmZn{sub 11}-type derivative compound in the Yb-Zn-Al system: Crystal structure and magnetic properties

    SciTech Connect

    Stelmakhovych, O.; Stelmakhovych, B.; Uhlirova, K.; Maskova, S.; Havela, L.; Kalychak, Ya.

    2011-07-15

    Crystal structure and magnetic properties are reported for Yb{sub 3.50}Zn{sub 32.1}Al{sub 1.4} prepared in single-crystalline form. It adopts the SmZn{sub 11}-type of structure (SG P6/mmm) with lattice parameters a=0.90458(1), c=0.88547(1) nm. The phase composition was analyzed by XRD, chemical and electron microprobe analysis. The ytterbium atoms in this compound are in the non-magnetic 4f{sup 14} state. - Graphical abstract: Crystal structure and magnetic susceptibility of Yb{sub 3.50}Zn{sub 32.1}AI{sub 1.4}. Highlights: > Yb{sub 3.50}Zn{sub 32.1}Al{sub 1.4} single crystals were synthesized by flux-growth method. > The studied material is diamagnetic. > Magnetization measurements revealed divalent state of Yb atoms in this structure. > Data from EDAX, chemical and X-ray analysis show good correlation.

  2. Preparation and photoluminescence properties of RE:Na 3La 9O 3(BO 3) 8 ( RE=Er, Yb) crystals

    NASA Astrophysics Data System (ADS)

    Liu, Zuoliang; Zhang, Guochun; Zhang, Jianxiu; Bai, Xiaoyan; Fu, Peizhen; Wu, Yicheng

    2010-06-01

    Using Na 2CO 3-H 3BO 3-NaF as fluxes, transparent RE:Na 3La 9O 3(BO 3) 8 (abbr. RE:NLBO, RE=Er, Yb) crystals have been grown by the top seed solution growth (TSSG) method. The X-ray powder diffraction analysis shows that the RE:NLBO crystals have the same structure with NLBO. The element contents were determined by molar to be 0.64% Er 3+ in Er:NLBO, 2.70% Yb 3+ in Yb:NLBO, respectively. The polarized absorption spectra of RE:NLBO have been measured at room temperature and show that both Er:NLBO and Yb:NLBO have a strong absorption bands near 980 nm with wide FWHM (Full Wave at Half Maximum) (21 nm for Er:NLBO and 25 nm for Yb:NLBO). Fluorescence spectra have been recorded. Yb:NLBO has the emission peaks at 985 nm, 1028 nm and 1079 nm and the emission peak of Er:NLBO is at 1536 nm. Spectral parameters have been calculated by the Judd-Ofelt theory for Er:NLBO and the reciprocity method for Yb:NLBO, respectively. The calculated values show that Er:NLBO is a candidate of 1.55 μm laser crystals and Yb:NLBO is a candidate for self-frequency doubling crystal.

  3. Fabrication of waveguides in Yb:YCOB crystal by MeV oxygen ion implantation

    NASA Astrophysics Data System (ADS)

    Jiao, Yang; Chen, Feng; Wang, Xue-Lin; Wang, Ke-Ming; Wang, Lei; Wang, Liang-Ling; Zhang, Huai-Jin; Lu, Qing-Ming; Ma, Hong-Ji; Nie, Rui

    2007-07-01

    Oxygen ions with energies of 6.0 or 3.0 MeV were implanted into y-cut Yb:YCOB crystals at fluences ranging from 5.0 × 10 13 to 2.0 × 10 15 ions/cm 2 at room temperature, forming optical planar waveguide structures. Dark-mode line spectroscopy was applied at two wavelengths, 633 and 1539 nm, in various excitation configurations, showing strong enhancement of one of the indices ( nx) in the implanted near surface. The nx refractive index profile is reconstructed by a reflectivity calculation method and compared to the ion energy losses profiles deduced from SRIM-code simulation. Moreover, the near-field patterns were imaged by an end-fire coupling arrangement.

  4. EPR and optical study of Yb3+-doped β-PbF2 single crystals and nanocrystals of glass-ceramics

    NASA Astrophysics Data System (ADS)

    Dantelle, G.; Mortier, M.; Goldner, Ph; Vivien, D.

    2006-08-01

    β-PbF2 single crystals doped with YbF3 (0.2% and 2%) were studied by x-ray diffraction (XRD), electron paramagnetic resonance (EPR) and optical spectroscopy. EPR revealed the presence of only one kind of paramagnetic ion Yb3+, in a cubic symmetry site. The optical absorption, emission and excitation spectra enabled us to identify the transitions attributed to Yb3+ in the cubic site and to determine its energy level diagram. Site-selective laser spectroscopy also evidenced the presence of another type of Yb3+ ions, undetectable by classical EPR. This second type, which dominates in the 2%-doped crystal and exhibits cooperative luminescence, was attributed to Yb3+ ions forming clusters. Transparent oxyfluoride glass-ceramics, containing β-Pb1-yYbyF2+y nanocrystallites, were also synthesized and studied by XRD, EPR and optical spectroscopy. Two types of Yb3+ ions were found, as in β-PbF2 single crystals. The optical properties of the oxyfluoride glass-ceramics turn out to be similar to those of ytterbium activated β-PbF2 single crystals. Moreover, the Yb environments found in PbF2 single crystals seem to already occur in the parent glass. Therefore, these materials are expected to be good laser media, like the rare-earth doped fluorite crystals, either in bulk or fibre form.

  5. Nonequivalent Yb{sup 3+} centres in Y{sub 1-x}Yb{sub x}Al{sub 3}(BO{sub 3}){sub 4} laser crystals

    SciTech Connect

    Boldyrev, K N; Popova, Marina N; Bezmaternykh, L N; Betinelli, M

    2011-02-28

    The absorption spectra of nonlinear laser crystals Y{sub 1-x}Yb{sub x}Al{sub 3}(BO{sub 3}){sub 4} grown from bismuth-lithium-molybdate and potassium-molybdate solution-melts are comparatively studied by high-resolution Fourier spectroscopy. The differences observed in the fine structure of the absorption spectra are correlated with the variations in the solution-melt composition and in the concentrations of bismuth and molybdenum impurities in the crystals. It is shown that the concentration of the molybdenum impurity (the main factor hindering lasing in the UV spectral region) in the single crystals grown from the bismuth-lithium-molybdate solutions is more than an order of magnitude smaller than in the crystals grown using the potassium-molybdate solution-melt. The described method can be used for express analysis of the quality of UV laser crystals and for improving the solution-melt technologies of growth of laser crystals and crystals used for generation of the fourth harmonic of Nd:YAG laser radiation. (active media)

  6. Single crystal growth of Yb doped NaGd(WO{sub 4}){sub 2} and structural and spectroscopic studies

    SciTech Connect

    Singh, S. G.; Singh, A. K.; Desai, D. G.; Tiwari, B.; Tyagi, M.

    2014-04-24

    High quality single crystals of NaGd(WO{sub 4}){sub 2} doped with 5 mol % Yb and oriented along <001> have been grown by the Czochralski technique in Ar atmosphere. The tetragonal space group I41/a accounts for all the reflections observed in the powder X-ray diffraction analysis. Polarized optical spectroscopy at room temperature revealed a direction dependence of absorption at different wavelength. As a novel uniaxial laser host for Yb{sup 3+}, NaGd(WO{sub 4}){sub 2} is characterized with respect to its transparency and band-edge. The emission spectrum of Yb{sup 3+} (excitation: 980-990 nm diode laser) was also recorded.

  7. Lu-177 preparation for radiotherapy application.

    PubMed

    Park, Ul Jae; Lee, Jun-Sig; Choi, Kang Hyuk; Nam, Sung Soo; Yu, Kook Hyun

    2016-09-01

    A separation study using a (176)Yb target for the preparation of nca (177)Lu, which is a beta-emitting nuclide used not only in radioimmunotherapy applications but also in the treatment of various lesions, has been performed. A material having a better selectivity and separation efficiency for Lu than Yb was developed, and the separation conditions of (177)Lu were derived using this from a neutron irradiated (176)Yb target. The separation material was an organo-ceramic hybrid material containing a phosphate group. Adsorption behavior was determined through batch experiments, and (177)Lu separation from the Yb target was evaluated through column experiments. The Yb target, with a 99.72% in (176)Yb, was irradiated in the irradiation hole of HANARO, which has a thermal neutron flux of 1.6E+14ncm(-2)s(-1). The batch experiments revealed that the organo-ceramic hybrid material (Sol-POS) had a separation factor of 1.6 at 0.5M HCl. Separation was performed through extraction chromatography using a 5mg enriched Yb target, and the separation yield of the NCA (177)Lu was about 78%. If the amount of Yb target is increased to produce curies level (177)Lu, additional purification will be needed. PMID:27295512

  8. Transition from semiconducting to metallic-like conducting and weak antilocalization effect in single crystals of LuPtSb

    SciTech Connect

    Hou, Zhipeng; Wang, Yue; Xu, Guizhou; Zhang, Xiaoming; Liu, Enke; Xi, Xuekui; Wang, Wenhong Wu, Guangheng; Wang, Wenquan; Liu, Zhongyuan

    2015-03-09

    High quality half-Heusler single crystals of LuPtSb have been synthesized by a Pb flux method. The temperature dependent resistivity and Hall effects indicate that the LuPtSb crystal is a p-type gapless semiconductor showing a transition from semiconducting to metallic conducting at 150 K. Moreover, a weakly temperature-dependent positive magnetoresistance (MR) as large as 109% and high carrier mobility up to 2950 cm{sup 2}/V s are experimentally observed at temperatures below 150 K. The low-field MR data show evidence for weak antilocalization (WAL) effect at temperatures even up to 150 K. Analysis of the temperature and angle dependent magnetoconductance manifests that the WAL effect originates from the bulk contribution owing to the strong spin-orbital coupling.

  9. Neutron spectroscopic study of Crystal-field excitation in Yb2 (Ti2 - x Ybx) O7 -x/2

    NASA Astrophysics Data System (ADS)

    Gaudet, Jonathan; Maharaj, Dalini; Kermarrec, Edwin; Granroth, Garrett; Ross, Kate; Dabowska, Hanna; Gaulin, Bruce

    2015-03-01

    Among the rare-earth titanate pyrochlores, Yb2 Ti2O7 has attracted much attention as a potential realization of a quantum spin ice. While strong quantum effects are absent in classical spin ice compounds, they are thought to be significant in Yb2 Ti2O7 because of its effective spin S=1/2 and its XY spin anisotropy, quantities both determined by the Crystal-Electric Field (CEF) levels. However, a thorough neutron spectroscopy study of the CEF levels is still lacking. Here, we report time-of-flight inelastic neutron scattering measurements on Yb2 Ti2O7 . Our results lead to the unambiguous determination of the CEF levels, the ground-state wavefunction and therefore the nature of the spin anisotropy of the J=7/2 Yb3+ . A significant sample dependence in the low temperature heat capacity has been reported and attributed to an excess of Yb3+ (''stuffing'') in the structure. Our measurements, carried out on two well-characterized samples with different levels of stuffing, allow us to discuss the impact of such disorder on the CEF levels.

  10. Crystal growth by Bridgman and Czochralski method of the ferromagnetic quantum critical material YbNi4P2

    NASA Astrophysics Data System (ADS)

    Kliemt, K.; Krellner, C.

    2016-09-01

    The tetragonal YbNi4P2 is one of the rare examples of compounds that allow the investigation of a ferromagnetic quantum critical point. We report in detail on two different methods which have been used to grow YbNi4P2 single crystals from a self-flux. The first, a modified Bridgman method, using a closed crucible system yields needle-shaped single crystals oriented along the [001]-direction. The second method, the Czochralski growth from a levitating melt, yields large single crystals which can be cut in any desired orientation. With this crucible-free method, samples without flux inclusions and a resistivity ratio at 1.8 K of RR1.8K = 17 have been grown.

  11. Activation effect of Ho3+ at 2.84 μm MIR luminescence by Yb3+ ions in GGG crystal.

    PubMed

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

    2013-10-15

    The use of Yb(3+) co-doping for the enhancement of Ho(3+):(5)I(6)→(5)I(7) mid-IR (MIR) emissions was investigated in GGG crystal for the first time. It is established that Yb(3+) highly increases Ho(3+) 2.84 μm emissions by transforming pump energy from the Yb(3+):(2)F(5/2) level to the laser upper level (5)I(6) of Ho(3+). The energy-transfer efficiency from Yb(3+):(2)F(5/2) to Ho(3+):(5)I(6) is calculated to be 96.2%. The absorption cross section, emission cross section, and fluorescence quantum efficiency are estimated and discussed. It is concluded that the Yb, Ho:GGG crystal is promising material for an LD-pumped 2.84 μm laser application. PMID:24321901

  12. Polarized spectra calculation and continuous wave laser operation of Yb-doped disordered Ca3La2(BO3)4 crystal

    NASA Astrophysics Data System (ADS)

    Wang, Yeqing; Chen, Aixi; You, Zhenyu; Tu, Chaoyang

    2015-12-01

    A notable disorder crystal Yb:Ca3La2(BO3)4 crystal with Yb3+ ion doping concentration of 10 at.% was grown by the Czochralski method. The polarized absorption, polarized emission, and polarized gain cross sections were systematically calculated. The laser operations were investigated with Yb:Ca3La2(BO3)4 crystals cut along the a, b, and c crystallographic axes. The highest output power of 3.88 W was obtained by using the b-cut Yb:Ca3La2(BO3)4 crystal, with a slope efficiency of 62%. Additionally, it was confirmed that the output laser spectra were largely dependent on the output coupler.

  13. High-power efficient cw and pulsed lasers based on bulk Yb : KYW crystals with end diode pumping

    SciTech Connect

    Kim, G H; Yang, G H; Lee, D S; Kulik, Alexander V; Sall', E G; Chizhov, S A; Yashin, V E; Kang, U

    2012-04-30

    End-diode-pumped lasers based on one and two Yb : KYW crystals operating in cw and Q-switched regimes, as well as in the regime of mode-locking, are studied. The single-crystal laser generated stable ultrashort (shorter than 100 fs) laser pulses at wavelengths of 1035 and 1043 nm with an average power exceeding 1 W. The average output power of the two-crystal laser exceeded 18 W in the cw regime and 16 W in the Q-switched regime with a slope efficiency exceeding 30%.

  14. Yb 3+-doped oxide crystals for diode-pumped solid state lasers: crystal growth, optical spectroscopy, new criteria of evaluation and combinatorial approach

    NASA Astrophysics Data System (ADS)

    Boulon, G.

    2003-04-01

    Our recent scientific program has involved the general evaluation of Yb 3+-doped oxide crystals for diode-pumped solid state lasers. Among crystalline families which provide the best expected performances, some have been grown: sesquioxide, oxyapatite, niobate and garnet fibres pulled either from the Laser Heated Pedestal Growth (LHPG) or the Micro-Pulling Down ( μ-PD) technique, tungstates by the top nucleated floating crystal (TNFC) and garnet and oxiapatite by the Czochralski (CZ) technique. Optical spectra of all crystals have been performed. In addition, a combinatorial chemistry approach has been pointed out to study the radiative lifetime and the concentration quenching processes in these laser crystals.

  15. Growth and optical properties of Yb 3+-doped α-Ba 3Y(BO 3) 3 crystal

    NASA Astrophysics Data System (ADS)

    Pan, Shangke; Hu, Zhushu; Lin, Zhoubin; Wang, Guofu

    2004-03-01

    Crystal of Yb3+-doped α-Ba3Y(BO3)3 has been grown by the Czochralski method. The spectroscopic characterizations have been investigated at room temperature. Yb3+:α-Ba3Y(BO3)3 crystal exhibits the broad absorption at 976 nm with an FWHM of 5 nm and a large overall spitting of 2F7/2 manifold (912 cm-1). The absorption and emission cross-sections are 1.10×10-20 cm2 at 976 nm and 1.16×10-21 cm2 at 1060 nm, respectively. The fluorescence lifetime is 2.1 ms.

  16. Evaluation of spectroscopic properties of Er3+/Yb3+/Pr3+: SrGdGa3O7 crystal for use in mid-infrared lasers

    NASA Astrophysics Data System (ADS)

    Xia, Houping; Feng, Jianghe; Wang, Yan; Li, Jianfu; Jia, Zhitai; Tu, Chaoyang

    2015-09-01

    Er3+/Yb3+/Pr3+: SrGdGa3O7 crystal was firstly grown by Czochralski method. Detailed spectroscopic analyses of Er3+/Yb3+/Pr3+: SrGdGa3O7 were carried out. Besides better absorption characteristic, the spectra of Er3+/Yb3+/Pr3+: SrGdGa3O7 show weaker up-conversion and near-infrared emissions as well as superior mid-infrared emission in comparison to Er3+: SrGdGa3O7 and Er3+/Yb3+: SrGdGa3O7 crystals. Furthermore, the self-termination effect for Er3+ 2.7 μm laser is suppressed successfully because the fluorescence lifetime of the 4I13/2 lower level of Er3+ decreases markedly while that of the upper 4I11/2 level changes slightly in Er3+/Yb3+/Pr3+: SrGdGa3O7 crystal. The sensitization effect of Yb3+ and deactivation effect of Pr3+ ions as well as the energy transfer mechanism in Er3+/Yb3+/Pr3+: SrGdGa3O7 crystal were also studied in this work. The introduction of Yb3+ and Pr3+ is favorable for achieving an enhanced 2.7 μm emission in Er3+/Yb3+/Pr3+: SrGdGa3O7 crystal which can act as a promising candidate for mid-infrared lasers.

  17. Evaluation of spectroscopic properties of Er3+/Yb3+/Pr3+: SrGdGa3O7 crystal for use in mid-infrared lasers

    PubMed Central

    Xia, Houping; Feng, Jianghe; Wang, Yan; Li, Jianfu; Jia, Zhitai; Tu, Chaoyang

    2015-01-01

    Er3+/Yb3+/Pr3+: SrGdGa3O7 crystal was firstly grown by Czochralski method. Detailed spectroscopic analyses of Er3+/Yb3+/Pr3+: SrGdGa3O7 were carried out. Besides better absorption characteristic, the spectra of Er3+/Yb3+/Pr3+: SrGdGa3O7 show weaker up-conversion and near-infrared emissions as well as superior mid-infrared emission in comparison to Er3+: SrGdGa3O7 and Er3+/Yb3+: SrGdGa3O7 crystals. Furthermore, the self-termination effect for Er3+ 2.7 μm laser is suppressed successfully because the fluorescence lifetime of the 4I13/2 lower level of Er3+ decreases markedly while that of the upper 4I11/2 level changes slightly in Er3+/Yb3+/Pr3+: SrGdGa3O7 crystal. The sensitization effect of Yb3+ and deactivation effect of Pr3+ ions as well as the energy transfer mechanism in Er3+/Yb3+/Pr3+: SrGdGa3O7 crystal were also studied in this work. The introduction of Yb3+ and Pr3+ is favorable for achieving an enhanced 2.7 μm emission in Er3+/Yb3+/Pr3+: SrGdGa3O7 crystal which can act as a promising candidate for mid-infrared lasers. PMID:26369289

  18. Z-scan measurements of the nonlinear refractive indices of novel Yb-doped laser crystal hosts

    NASA Astrophysics Data System (ADS)

    Major, A.; Aitchison, J. S.; Smith, P. W. E.; Druon, F.; Georges, P.; Viana, B.; Aka, G. P.

    2005-02-01

    We report on the z-scan characterization of the nonlinear refractive indices of three borate crystals (GdCOB, YCOB, and BOYS), which are new promising Yb-doped laser hosts. The results indicate the possibility of substantial Kerr-lensing and self-phase modulation effects in femtosecond oscillators and amplifiers. High values of the nonlinear refractive indices suggest possible KLM operation of such lasers.

  19. Resolution of the discrepancy between the variation of the physical properties of Ce1-xYbxCoIn5 single crystals and thin films with Yb composition

    SciTech Connect

    Jang, S.; White, B. D.; Lum, I. K.; Kim, H.; Tanatar, M. A.; Straszheim, W. E.; Prozorov, R.; Keiber, T.; Bridges, F.; Shu, L.; Baumbach, R. E.; Janoschek, M.; Maple, M. B.

    2014-11-18

    The extraordinary electronic phenomena including an Yb valence transition, a change in Fermi surface topology, and suppression of the heavy fermion quantum critical field at a nominal concentration x≈0.2 have been found in the Ce1-xYbxCoIn5 system. These phenomena have no discernable effect on the unconventional superconductivity and normal-state non-Fermi liquid behaviour that occur over a broad range of x up to ~0.8. However, the variation of the coherence temperature T* and the superconducting critical temperature Tc with nominal Yb concentration x for bulk single crystals is much weaker than that of thin films. To determine whether differences in the actual Yb concentration of bulk single crystals and thin film samples might be responsible for these discrepancies, we employed Vegard’s law and the spectroscopically determined values of the valences of Ce and Yb as a function of x to determine the actual composition xact of bulk single crystals. This analysis is supported by energy-dispersive X-ray spectroscopy, wavelength-dispersive X-ray spectroscopy, and transmission X-ray absorption edge spectroscopy measurements. The actual composition xact is found to be about one-third of the nominal concentration x up to x~0.5, and resolves the discrepancy between the variation of the physical properties of Ce1-xYbxCoIn5 single crystals and thin films with Yb concentration.

  20. Rare-Earth Triangular Lattice Spin Liquid: A Single-Crystal Study of YbMgGaO4.

    PubMed

    Li, Yuesheng; Chen, Gang; Tong, Wei; Pi, Li; Liu, Juanjuan; Yang, Zhaorong; Wang, Xiaoqun; Zhang, Qingming

    2015-10-16

    YbMgGaO4, a structurally perfect two-dimensional triangular lattice with an odd number of electrons per unit cell and spin-orbit entangled effective spin-1/2 local moments for the Yb(3+) ions, is likely to experimentally realize the quantum spin liquid ground state. We report the first experimental characterization of single-crystal YbMgGaO4 samples. Because of the spin-orbit entanglement, the interaction between the neighboring Yb(3+) moments depends on the bond orientations and is highly anisotropic in the spin space. We carry out thermodynamic and the electron spin resonance measurements to confirm the anisotropic nature of the spin interaction as well as to quantitatively determine the couplings. Our result is a first step towards the theoretical understanding of the possible quantum spin liquid ground state in this system and sheds new light on the search for quantum spin liquids in strong spin-orbit coupled insulators. PMID:26550899

  1. Synthesis, crystal structure, and magnetism of A2Co12As7 (A=Ca, Y, Ce-Yb)

    NASA Astrophysics Data System (ADS)

    Tan, Xiaoyan; Ovidiu Garlea, V.; Chai, Ping; Geondzhian, Andrey Y.; Yaroslavtsev, Alexander A.; Xin, Yan; Menushenkov, Alexey P.; Chernikov, Roman V.; Shatruk, Michael

    2016-04-01

    Ternary intermetallics, A2Co12As7 (A=Ca, Y, Ce-Yb), have been synthesized by annealing mixtures of elements in molten Bi at 1223 K. The materials obtained crystallize in the P63/m variant of the Zr2Fe12P7 structure type. The unit cell volume shows a monotonic decrease with the increasing atomic number of the rare-earth metal, with the exception of Ce-, Eu-, and Yb-containing compounds. An examination of these outliers with X-ray absorption near edge structures (XANES) spectroscopy revealed mixed valence of Ce, Eu, and Yb, with the average oxidation states of +3.20(1), +2.47(5), and +2.91(1), respectively, at room temperature. Magnetic behavior of A2Co12As7 is generally characterized by ferromagnetic ordering of Co 3d moments at 100-140 K, followed by low-temperature ordering of rare-earth 4f moments. The 3d-4f magnetic coupling changes from antiferromagnetic for A=Pr-Sm to ferromagnetic for A=Ce and Eu-Yb. Polarized neutron scattering experiments were performed to support the postulated ferro- and ferrimagnetic ground states for Ce2Co12As7 and Nd2Co12As7, respectively.

  2. Synthesis, crystal structure, and magnetism of A2Co12As7 (A=Ca, Y, Ce–Yb)

    DOE PAGESBeta

    Tan, Xiaoyan; Ovidiu Garlea, V.; Chai, Ping; Geondzhian, Andrey Y.; Yaroslavtsev, Alexander A.; Xin, Yan; Menushenkov, Alexey P.; Chernikov, Roman V.; Shatruk, Michael

    2015-08-28

    In this study, ternary intermetallics, A2Co12As7 (A=Ca, Y, Ce–Yb), have been synthesized by annealing mixtures of elements in molten Bi at 1223 K. The materials obtained crystallize in the P63/m variant of the Zr2Fe12P7 structure type. The unit cell volume shows a monotonic decrease with the increasing atomic number of the rare-earth metal, with the exception of Ce-, Eu-, and Yb-containing compounds. An examination of these outliers with X-ray absorption near edge structures (XANES) spectroscopy revealed mixed valence of Ce, Eu, and Yb, with the average oxidation states of +3.20(1), +2.47(5), and +2.91(1), respectively, at room temperature. Magnetic behavior ofmore » A2Co12As7 is generally characterized by ferromagnetic ordering of Co 3d moments at 100–140 K, followed by low-temperature ordering of rare-earth 4f moments. The 3d-4f magnetic coupling changes from antiferromagnetic for A=Pr–Sm to ferromagnetic for A=Ce and Eu–Yb. Finally, polarized neutron scattering experiments were performed to support the postulated ferro- and ferrimagnetic ground states for Ce2Co12As7 and Nd2Co12As7, respectively.« less

  3. Growth and optical properties of Yb3+ and Tb3+ codoped BaB2O4 crystals

    NASA Astrophysics Data System (ADS)

    Solntsev, V. P.; Yelisseyev, A. P.; Bekker, T. B.; Kokh, A. E.; Stonoga, S. Yu.; Davydov, A. V.; Maillard, A.

    2012-11-01

    Optical absorption and luminescence spectra of ytterbium and terbium codoped BaB2O4 (β-BBO and α-BBO) crystals grown in different conditions have been studied. Low-temperature absorption peaks were observed in all samples. Features related to rare earth ions were observed in absorption and luminescence spectra. Absorption and emission in the range 860-1000 nm are caused by 2F5/2↔2F7/2 transitions in Yb3+ ions. Emission peaks at 500, 550, 590 and 630 nm correspond to 5D4→7F6, 7F5, 7F4, and 7F3 transitions of Tb3+ ions, respectively. The probable reasons of variations in spectroscopic features related to Yb in BBO host are discussed. It has been shown that the replacement of Ва2+ by Yb3+ in the lattice of ВаВ2О4 results in the decrease in the symmetry of oxygen surrounding of Yb3+.

  4. Characterization of bubble core and cloudiness in Yb3+:Sr5(PO4)3F crystals using Micro-Raman spectroscopy

    SciTech Connect

    Cui, Y; Roy, U N; Bai, L; Burger, A; Qiu, S R; Schaffers, K

    2006-11-15

    Ytterbium doped strontium fluoroapatite Yb{sup 3+}:Sr{sub 5}(PO{sub 4}){sub 3}F (Yb: S-FAP) crystals have been used in High Average Power Laser systems as gain medium. Growth induced defects associated with the crystal often affect their performance. In order to improve the crystal quality and its optical applications, it is imperative to understand the nature of these defects. In this study, we utilize Micro-Raman spectroscopy to characterize two common growth-induced defects: bubble core and cloudiness. We find the bubble core consist of voids and microcrystals of Yb: S-FAP. These microcrystals have very different orientation from that of the pure crystal outside the bubble core. In contrast to a previous report, neither Sr{sub 3}(PO{sub 4}){sub 2} nor Yb{sub 2}O{sub 3} are observed in the bubble core regions. On the other hand, the cloudy regions are made up of the host materials blended with a structural deformation along with impurities which include CaCO{sub 3}, YbPO{sub 4}, SrHPO{sub 4} and Sr{sub 2}P{sub 2}O{sub 7}. The impurities are randomly distributed in the cloudy regions. This analysis is necessary for understanding and eliminating these growth defects in Yb:S-FAP crystals.

  5. Study of 57 Fe Mössbauer effect in RFe2Zn20 ( R = Lu, Yb, Gd)

    SciTech Connect

    Bud’ko, Sergey L.; Kong, Tai; Ma, Xiaoming; Canfield, Paul C.

    2015-08-04

    In this document we report measurements of 57Fe Mössbauer spectra for RFe2Zn20 (R = Lu, Yb, Gd) from ~ 4.5 K to room temperature. The obtained isomer shift values are very similar for all three compounds, their temperature dependence was analyzed within the Debye model and resulted in an estimate of the Debye temperatures of 450-500 K. The values of quadrupole splitting at room temperature change with the cubic lattice constant a in a linear fashion. For GdFe2Zn20, ferromagnetic order is seen as an appearance of a sextet in the spectra. The 57Fe site hyperfine field for T → 0 was evaluated to be ~ 2.4 T.

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

    SciTech Connect

    Barandiarán, Zoila Seijo, Luis

    2014-12-21

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

  7. Growth and Characterization of Lu2O3:Eu3+ Thin Films on Single-Crystal Yttria-Doped Zirconia

    NASA Astrophysics Data System (ADS)

    Roy, Sudesna; Topping, Stephen; Sarin, Vinod

    2013-04-01

    Lu2O3 doped with Eu3+ has been established as an excellent scintillator material for numerous applications such as lasers, optical lenses, and radiography. The material is typically manufactured via hot pressing. This process, apart from being prohibitively expensive, can also introduce major structural defects because it requires grinding/polishing to achieve high transparency and spatial resolution. To overcome these process limitations that have restricted the commercial viability of Lu2O3:Eu3+ scintillators, a technique to deposit thin films (1-10 μm) of Lu2O3:Eu3+ has been developed. This investigation characterized the growth of such thin films by radio frequency (RF) magnetron sputtering on single-crystal cubic yttria doped zirconia (YSZ) substrates. At a deposition rate of 3.3 Å/s, the effects of substrate heating and orientation on coating structure property and the resultant effect on performance were evaluated. Additionally, the effect of deposition parameters and growth conditions on the radioluminescence of the coatings, excited by x-rays, was systematically examined.

  8. 2.0-μm emission and energy transfer of Ho3+/Yb3+ co-doped LiYF4 single crystal excited by 980 nm

    NASA Astrophysics Data System (ADS)

    Yang, Shuo; Xia, Hai-Ping; Jiang, Yong-Zhang; Zhang, Jia-Zhong; Jiang, Dong-Sheng; Wang, Cheng; Feng, Zhi-Gang; Zhang, Jian; Gu, Xue-Mei; Zhang, Jian-Li; Jiang, Hao-Chuan; Chen, Bao-Jiu

    2015-06-01

    Ho3+/Yb3+ co-doped LiYF4 single crystals with various Yb3+ concentrations and ˜ 0.98 mol% Ho3+ concentration are grown by the Bridgman method under the conditions of taking LiF and YF3 as raw materials and a temperature gradient (40 °C/cm-50 °C/cm) for the solid-liquid interface. The luminescent performances of the crystals are investigated through emission spectra, infrared transmittance spectrum, emission cross section, and decay curves under excitation by 980 nm. Compared with the Ho3+ single-doped LiYF4 crystal, the Ho3+/Yb3+ co-doped LiYF4 single crystal has an obviously enhanced emission band from 1850 nm to 2150 nm observed when excited by a 980-nm diode laser. The energy transfer from Yb3+ to Ho3+ and the optimum fluorescence emission around 2.0 μm of Ho3+ ions are investigated. The maximum emission cross section of the above sample at 2.0 μm is calculated to be 1.08×10-20 cm2 for the LiYF4 single crystal of 1-mol% Ho3+ and 6-mol% Yb3+ according to the measured absorption spectrum. The high energy transfer efficiency of 88.9% from Yb3+ to Ho3+ ion in the sample co-doped by Ho3+ (1 mol%) and Yb3+ (8 mol%) demonstrates that the Yb3+ ions can efficiently sensitize the Ho3+ ions. Project supported by the National Natural Science Foundation of China (Grant Nos. 51472125 and 51272109) and the K.C. Wong Magna Fund in Ningbo University, China (Grant No. NBUWC001).

  9. Large electric polarization in high pressure synthesized orthorhombic manganites RMnO3 (R=Ho,Tm,Yb and Lu) by using the double-wave PE loop measurements

    NASA Astrophysics Data System (ADS)

    Chai, Y. S.; Oh, Y. S.; Manivannan, N.; Yang, Y. S.; Kim, Kee Hoon; Feng, S. M.; Wang, L. J.; Jin, C. Q.

    2009-03-01

    The magnitude of electric polarization via the conventional pyroelectric current and/or PE loop measurements often is ambiguous due to resistive components of the sample. To avoid this, a new technique called the double-wave method has been recently developed [1], in which only hysteretic PE components can be measured. Using this technique, we have measured the ferroelectric polarization of the orthorhombic RMnO3 (R=Ho, Tm, Yb, and Lu) synthesized under high pressure. Large remnant polarization Pr up to 920 μC/m^2 is observed at 10 K for LuMnO3. Furthermore, the Pr vs. temperature data from the PE loop has shown consistency with that measured through the pyroelectric current measurements, supporting a theoretical prediction of large polarization in the E-type spin structure in this system [2]. We also discuss the influence of thermal histories on the ferroelectric domain dynamics and possible internal bias field effects originating from oxygen vacancies in RMnO3. [1] M. Fukunaga, et al. J. Phys. Soc. Jpn. 77, 064706 (2008). [2] I. A. Sergienko, et al. Phys. Rev. Lett., 97, 227204 (2006)

  10. Dextran-coated fluorapatite crystals doped with Yb3+/Ho3+ for labeling and tracking chondrogenic differentiation of bone marrow mesenchymal stem cells in vitro and in vivo.

    PubMed

    Hu, Xiaoqing; Zhu, Jingxian; Li, Xiyu; Zhang, Xin; Meng, Qingyang; Yuan, Lan; Zhang, Jiying; Fu, Xin; Duan, Xiaoning; Chen, Haifeng; Ao, Yingfang

    2015-06-01

    Upconversion fluorescent nanoparticles are becoming more widely used as imaging contrast agents, owing to their high resolution and penetration depth, and avoidance of tissue auto-fluorescence and photodamage to cells. Here, we synthesized upconversion fluorescent crystals from rare-earth Yb3+ and Ho3+ co-doped fluorapatite (FA:Yb3+/Ho3+) suitable for long-term tracking and monitoring cartilage development (chondrogenesis) in bone marrow mesenchymal stem cells (BMSCs) in vitro and in vivo. We initially determined the structure, morphology and luminescence of the products using X-ray powder diffraction, transmission electron microscopy and two-photon confocal microscopy. When excited at 980 nm, FA:Yb3+/Ho3+ crystals exhibited distinct upconversion fluorescence peaks at 543 nm and 654 nm. We then conjugated FA:Yb3+/Ho3+ crystals with dextran to enhance hydrophilicity, biocompatibility and cell penetration. Next, we employed the dextran-coated FA:Yb3+/Ho3+ crystals in labeling and tracking chondrogenic differentiation processes in BMSCs stably expressing green fluorescent protein (BMSCsGFP) in vitro and in vivo. Labeled BMSCsGFP were shown to reproducibly exhibit chondrogenic differentiation potential in RT-PCR analysis, histological assessment and immunohistochemistry. We observed continuous luminescence from the FA:Yb3+/Ho3+ upconversion crystals at 4 weeks and 12 weeks post transplantation in BMSCsGFP, while GFP fluorescence in both control and crystal-treated groups significantly decreased at 12 weeks after BMSCsGFP transplantation. We therefore demonstrate the high biocompatibility and stability of FA:Yb3+/Ho3+ crystals in tracking and monitoring BMSCs chondrogenesis in vitro and in vivo, highlighting their excellent cell labeling potential in cartilage tissue engineering. PMID:25818450

  11. Dextran-coated fluorapatite crystals doped with Yb3+/Ho3+ for labeling and tracking chondrogenic differentiation of bone marrow mesenchymal stem cells in vitro and in vivo.

    PubMed

    Hu, Xiaoqing; Zhu, Jingxian; Li, Xiyu; Zhang, Xin; Meng, Qingyang; Yuan, Lan; Zhang, Jiying; Fu, Xin; Duan, Xiaoning; Chen, Haifeng; Ao, Yingfang

    2015-06-01

    Upconversion fluorescent nanoparticles are becoming more widely used as imaging contrast agents, owing to their high resolution and penetration depth, and avoidance of tissue auto-fluorescence and photodamage to cells. Here, we synthesized upconversion fluorescent crystals from rare-earth Yb3+ and Ho3+ co-doped fluorapatite (FA:Yb3+/Ho3+) suitable for long-term tracking and monitoring cartilage development (chondrogenesis) in bone marrow mesenchymal stem cells (BMSCs) in vitro and in vivo. We initially determined the structure, morphology and luminescence of the products using X-ray powder diffraction, transmission electron microscopy and two-photon confocal microscopy. When excited at 980 nm, FA:Yb3+/Ho3+ crystals exhibited distinct upconversion fluorescence peaks at 543 nm and 654 nm. We then conjugated FA:Yb3+/Ho3+ crystals with dextran to enhance hydrophilicity, biocompatibility and cell penetration. Next, we employed the dextran-coated FA:Yb3+/Ho3+ crystals in labeling and tracking chondrogenic differentiation processes in BMSCs stably expressing green fluorescent protein (BMSCsGFP) in vitro and in vivo. Labeled BMSCsGFP were shown to reproducibly exhibit chondrogenic differentiation potential in RT-PCR analysis, histological assessment and immunohistochemistry. We observed continuous luminescence from the FA:Yb3+/Ho3+ upconversion crystals at 4 weeks and 12 weeks post transplantation in BMSCsGFP, while GFP fluorescence in both control and crystal-treated groups significantly decreased at 12 weeks after BMSCsGFP transplantation. We therefore demonstrate the high biocompatibility and stability of FA:Yb3+/Ho3+ crystals in tracking and monitoring BMSCs chondrogenesis in vitro and in vivo, highlighting their excellent cell labeling potential in cartilage tissue engineering.

  12. Transport and superconducting properties of RNi2B2C (R=Y,nLu) single crystals

    NASA Astrophysics Data System (ADS)

    Rathnayaka, K. D. D.; Bhatnagar, A. K.; Parasiris, A.; Naugle, D. G.; Canfield, P. C.; Cho, B. K.

    1997-04-01

    The in-plane resistivity, in-plane absolute thermopower, and upper critical field measurements are reported for single-crystal samples of YNi2B2C and LuNi2B2C superconductors. The in-plane resistivity shows metallic behavior and varies approximately linearly with temperature near room temperature (RT) but shows nearly quadratic behavior in temperature at low temperatures. The YNi2B2C and LuNi2B2C single-crystal samples exhibit large transverse magnetoresistance (~6-8 % at 45 kOe) in the ab plane. The absolute thermopower S(T) is negative from RT to the superconducting transition temperature Tc. Its magnitude at RT is a few times of the value for a typical good metal. S(T) is approximately linear in temperature between ~150 K and RT. Extrapolation to T=0 gives large intercepts (few μV/K) for both samples suggesting the presence of a much larger 'knee' than would be expected from electron-phonon interaction renormalization effects. The upper critical fields for H parallel and perpendicular to the c axis and the superconducting parameters derived from it do not show any anisotropy for the YNi2B2C single-crystal samples in agreement with magnetization and torque magnetometry measurements, but a small anisotropy is observed for the LuNi2B2C single crystals. The analysis shows that these are moderately strong-coupling type-II superconductors (similar to the A-15 compounds) with a value of the electron-phonon coupling parameter λ(0) approximately equal to 1.2 for YNi2B2C and 1.0 for LuNi2B2C, the Ginzburg-Landau coherence length ξ(0) approximately equal to 70 Å, and Hc2(0)~60-70 kOe. The temperature dependence of the upper critical field shows a positive curvature near Tc in disagreement with the Werthamer, Helfand, Hohenberg, and Maki (WHHM) theory but in agreement with a recent solution of the Gor'kov equation using a basis formed by Landau levels (Bahcall); however, the data show a severe disagreement between the observed low-temperature behavior of Hc2(T) and that

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

    PubMed

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

    2013-10-01

    Eu(2+)-Yb(3+) co-doped transparent glass-ceramic containing nano-Ca5(PO4)3F (FAP) was prepared in reducing atmosphere. XRD and TEM analysis indicated that nano-FAP about 40 nm precipitated homogeneously in glass matrix after heat treatment. Confirmed by spectroscopy measurements, the crystal-like absorption and emission of Eu(2+) indicated the partition of Eu(2+) into FAP nanocrystals in glass ceramic. NIR emission due to the transition (2)F5/2→(2)F7/2 of Yb(3+) ions (about 980-1100 nm) was observed from glasses under ultraviolet excitation, ascribed to downconversion from Eu(2+) to Yb(3+), which can be enhanced by precipitating nano-FAP crystals. The results indicated that Eu(2+)-Yb(3+) co-doped glass-ceramic embedding with nano-FAP is a promising candidate as downconversion materials for enhancing conversion efficiency of solar cells.

  14. Influence of some impurities on the emission properties of CaF2:YbF3 crystals

    NASA Astrophysics Data System (ADS)

    Stef, Marius; Nicoara, Irina; Cirlan, Florina; Para, Irina; Velazquez, Matias; Buse, Gabriel

    2015-12-01

    Various concentrations of YbF3 -doped and NaF or PbF2 co-doped CaF2 crystals were grown using the conventional Bridgman method. Transparent colorless crystals were obtained in graphite crucible in vacuum using a shaped graphite furnace. The crystals have been cooled to room temperature using an established procedure. Room temperature absorption spectra have been obtained using a Shimadzu 1650PC spectrophotometer. Photoluminescent properties in IR spectral range were analyzed using a spectrofluorimeter Horiba Fluorolog 3. An IR laser diode at 932 nm was also used an directly injected in the equipment. The emission spectra are influenced by the concentration of co-dopant added to the melt, and the excitation wavelength. The high emission peak at 979 nm overlaps with the absorption peak. The highest intensity in the IR emission (around 1029 nm) is obtained for CaF2:0.72 mol% YbF3 crystal by excitation at 932 nm (diode lamp).

  15. Energy transfer and visible-infrared quantum cutting photoluminescence modification in Tm-Yb codoped YPO(4) inverse opal photonic crystals.

    PubMed

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

    2015-08-01

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

  16. Energy transfer and visible-infrared quantum cutting photoluminescence modification in Tm-Yb codoped YPO(4) inverse opal photonic crystals.

    PubMed

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

    2015-08-01

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

  17. Structural analysis and crystal-field calculations of Nd3+ in GdxLu1-xTaO4 (x = 0.85) polycrystalline

    NASA Astrophysics Data System (ADS)

    Gao, Jin-Yun; Zhang, Qing-Li; Yang, Hua-Jun; Zhou, Peng-Yu; Sun, Dun-Lu; Yin, Shao-Tang; He, Ye

    2012-10-01

    The crystal structural parameters of Nd3+-doped rare earth orthotantalate GdxLu1-xTaO4 (x = 0.85) are determined by applying the Rietveld refinement to its X-ray diffraction, and its emission and excitation spectra at 77 K are analysed. The relativistic model of ab initio self-consistent DV-Xα method, which is applied to the cluster NdO8 in GdxLu1-xTaO4, and the effective Hamiltonian model are used to investigate its spin—orbit and crystal-field parameters. The free-ions and crystal-field parameters are fitted to the experimental energy levels at 77 K with a root-mean-square deviation of 14.92 cm-1. According to the crystal-field calculations, 96 levels of Nd3+ are assigned. Finally, the fitting results of free-ions and crystal-field parameters are compared with those already reported for Nd3+:YAlO3. The results indicate that the free-ion parameters are similar to those of the Nd3+ in GdxLu1-xTaO4 and YAlO3 hosts, and the crystal-field interaction of Nd3+ in GdxLu1-xTaO4 is stronger than that in YAlO3.

  18. Effects of scandium substitution on the crystal structure and luminescence properties of LuBO{sub 3}: Ce{sup 3+}

    SciTech Connect

    Wu, Yuntao; Ren, Guohao; Ding, Dongzhou; Pan, Shangke; Yang, Fan

    2012-10-15

    The calcite phase of LuBO{sub 3} and ScBO{sub 3} polycrystalline powders were synthesized by solid state reaction method, and the Lu{sub 1-x}Sc{sub x}BO{sub 3}:Ce (x=0.2, 0.5, 0.7) single crystals were grown by the Czochralski method. A large composition deviation between the initial polycrystalline powders and final single crystal was confirmed by electron probe micro-analysis. Raman spectroscopy revealed that moderate lattice disorder was induced by scandium substitution. However, based on the single crystal X-ray study, we finally concluded that the crystal structure of lutetium scandium orthoborate still crystallized in the rhombohedral system belonging to R3{sup -}c. Furthermore, the relationship between the energies of the five 5d levels of Ce{sup 3+} and the crystalline environment was revealed. The total redshift, total crystal field splitting, and centroid shift of Lu{sub 1-x}Sc{sub x}BO{sub 3}:Ce{sup 3+} were calculated based on their VUV excitation spectra. The variations trend of these observed spectroscopic parameters was in accordance with the predicted ones. - Graphical abstract: The crystal structure of Lu{sub 1-x}Sc{sub x}BO{sub 3}:Ce is rhombohedral system with R3{sup -}c space group. The relationship between the energies of the five Ce{sup 3+} 5d levels and the crystalline environment is established. Highlights: Black-Right-Pointing-Pointer Moderate lattice disorder is induced by scandium doping. Black-Right-Pointing-Pointer The crystal structure of Lu{sub 1-x}Sc{sub x}BO{sub 3}:Ce is rhombohedral system with R3{sup -}c space group. Black-Right-Pointing-Pointer Relationship between energies of Ce{sup 3+} 5d levels and crystalline environment is established. Black-Right-Pointing-Pointer The spectroscopic parameters are experimentally and theoretically calculated.

  19. CW lasing in Yb{sup 3+} : GGG crystals pumped at 0.925 {mu}m

    SciTech Connect

    Belovolov, A M; Belovolov, M I; Dianov, Evgenii M; Dudin, V V; Timoshechkin, M I E-mail: dianov@fo.gpi.r

    2006-07-31

    Single-mode cw lasing was obtained for the first time in Yb{sup 3+} : GGG crystals at room temperature at 1.030 and 1.037 {mu}m upon pumping Yb{sup 3+} ions by a 0.925-{mu}m neodymium-doped fibre laser. Lasing was observed at the transitions between the lower Stark sublevel of the {sup 2}F{sub 5/2} level and the upper Stark sublevels of the {sup 2}F{sub 7/2} ground state of Yb{sup 3+} ions. The study of lasing characteristic showed that lasing occurs according to the four-level scheme. The lasing threshold with respect to the absorbed power was 85 mW and the slope lasing efficiency was 20%. Upon 1.7-W pumping, the output power of 310 mW was achieved with the output resonator mirror with the transmission coefficient of 1%. The effective cross section of the lasing transition was 0.9x10{sup -20} cm{sup 2}. (special issue devoted to the 90th anniversary of a.m. prokhorov)

  20. Synthesis and luminescence investigation of Tb3+-Yb3+ codoped CdF2 single crystals

    NASA Astrophysics Data System (ADS)

    Cheddadi, A.; Boubekri, H.; Labbaci, K.; Diaf, M.; Guerbous, L.; Duvaut, T.; Jouart, J. P.

    2014-03-01

    Tb3+ (1%), Yb3+ (5%):CdF2 single crystals with good optical quality are grown by the standard Bridgman method. The crystal structure is checked by means of X-ray diffraction analysis. Absorption, excitation and fluorescence spectra are carried out at room temperature. The standard Judd-Ofelt (JO) model is applied to absorption intensities of Tb3+ to obtain the three phenomenological intensity parameters by the least square fit procedure. The values obtained are Ω2=2.40, Ω4=2.03 and Ω6=3.60 in 10-20 cm2 units, with root mean square of δ=0.1×10-20 cm2. These JO intensity parameters are then applied to determine the radiative transition probabilities (AJJ'), radiative lifetimes (τrad) and branching ratios (βJJ') of Tb3+ transitions. We focused on the blue and green transitions from 5D3 and 5D4 levels which occur with relatively high transition probabilities and branching ratios. The fluorescence spectrum exhibits two groups of lines well resolved from 5D3 and 5D4 manifolds (5D3, 5D4→7FJ, J=6, 5, 4, 3, 2). This spectrum is characterized by two strong lines corresponding to 5D3→7F5 (violet/blue line) and 5D4→7F5 (green line) transitions. For the main transitions, there is a good agreement between the fluorescence spectrum and the spontaneous emission probabilities given by the JO analysis. We also performed fluorescence decay spectra and measured the lifetime of 5D3 and 5D4 levels. This have led us to obtain the quantum efficiency of the two transitions 5D3, 5D4→7F5. For the green transition, the value of radiative quantum efficiency obtained is high, which reflects that multiphonon relaxation is limited. The reduced quantum efficiency of the transition from 5D3 manifold shows the happening of a cross relaxation process between Tb3+ ions as follows: 5D3+7F6→5D4+7F0, because of the closely matched energy difference between (5D3, 5D4), and (7F6, 7F0) levels. These parameters suggest that the studied host has the potential to produce intense green emission.

  1. Thermal modeling of gain competition in Yb-doped large-mode-area photonic-crystal fiber amplifier.

    PubMed

    Rosa, Lorenzo; Coscelli, Enrico; Poli, Federica; Cucinotta, Annamaria; Selleri, Stefano

    2015-07-13

    We propose a new model for gain competition effects in high-power fiber amplifiers, which accounts for the thermal effects of heat load on the doped core overlap of the propagating light field. The full-vectorial nature of the fiber modes is modeled by an embedded finite-element method modal solver, and the temperature profile is calculated by a simple and efficient radial heat propagation solver. The model is applied to a Yb³⁺-doped LPF45 air-clad photonic-crystal fiber amplifier for coand counter-propagating pumping setups, showing gain competition in conditions of severe heat load. PMID:26191922

  2. Resolution of the discrepancy between the variation of the physical properties of Ce1-xYbxCoIn5 single crystals and thin films with Yb composition

    DOE PAGESBeta

    Jang, S.; White, B. D.; Lum, I. K.; Kim, H.; Tanatar, M. A.; Straszheim, W. E.; Prozorov, R.; Keiber, T.; Bridges, F.; Shu, L.; et al

    2014-11-18

    The extraordinary electronic phenomena including an Yb valence transition, a change in Fermi surface topology, and suppression of the heavy fermion quantum critical field at a nominal concentration x≈0.2 have been found in the Ce1-xYbxCoIn5 system. These phenomena have no discernable effect on the unconventional superconductivity and normal-state non-Fermi liquid behaviour that occur over a broad range of x up to ~0.8. However, the variation of the coherence temperature T* and the superconducting critical temperature Tc with nominal Yb concentration x for bulk single crystals is much weaker than that of thin films. To determine whether differences in the actualmore » Yb concentration of bulk single crystals and thin film samples might be responsible for these discrepancies, we employed Vegard’s law and the spectroscopically determined values of the valences of Ce and Yb as a function of x to determine the actual composition xact of bulk single crystals. This analysis is supported by energy-dispersive X-ray spectroscopy, wavelength-dispersive X-ray spectroscopy, and transmission X-ray absorption edge spectroscopy measurements. The actual composition xact is found to be about one-third of the nominal concentration x up to x~0.5, and resolves the discrepancy between the variation of the physical properties of Ce1-xYbxCoIn5 single crystals and thin films with Yb concentration.« less

  3. Comparison of actively Q-switched laser performance of disordered Yb:Ca3La2(BO3)4 crystals cut along the crystallographic axes.

    PubMed

    Wang, Yeqing; Chen, Aixi; Tu, Chaoyang

    2015-03-10

    In this paper, actively Q-switched laser operation with an acousto-optic switch has been demonstrated by using Yb:Ca3La2(BO3)4 crystals cut along the a, b, and c crystallographic axes. The most efficient Q-switched laser operation was obtained by using b-cut Yb:Ca3La2(BO3)4 crystal with 1 kHz pulse repetition frequency, generating laser pulses of 0.5 mJ, 42.56 KW peak power and 9 ns pulse width, when the output couplings were 3%, 5%, and 5%, respectively. Pulse performances and output laser spectra of the a-, b-, and c-cut Yb:Ca3La2(BO3)4 crystals were compared under similar experimental conditions. PMID:25968384

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

    SciTech Connect

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

    2014-10-31

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

  5. Ionic conductivity of crystallization products of Ba1- x Yb x F2 + x melts ( x = 0.1, 0.2, 0.25)

    NASA Astrophysics Data System (ADS)

    Sorokin, N. I.; Sul'yanova, E. A.; Sobolev, B. P.

    2016-05-01

    The ionic conductivity σ of the crystallization products of Ba1 - x Yb x F2 + x melts with 10, 20 and 25 mol % YbF3 has been studied. A Ba0.9Yb0.1F2.1 sample is a solid solution with the CaF2 structure type, sp. gr. Fmoverline 3 m. A Ba0.8Yb0.2F2.2 sample contains two cubic forms with sp. gr. Fmoverline 3 m and Pmoverline 3 m. The σ values for Ba0.9Yb0.1F2.1 and Ba0.8Yb0.2F2.2 coincide and are equal to 3 × 10-5 S/cm at 500 K. A Ba0.75Yb0.25F2.25 sample is heterogeneous, despite its monolithic nature and transparency. A greater part of its volume has a cubic lattice with sp. gr. Pmoverline 3 m, while the smaller part is a phase crystallizing in the orthorhombic system. A change of composition from x = 0.2 to 0.25 leads to a change in the symmetry group and type of the cluster defects in the Ba1 - x Yb x F2 + x phase. The sp. gr. Fmoverline 3 m is replaced by the sp. gr. Pmoverline 3 m, and octahedral‒cubic {Ba8Yb6F69} clusters are transformed into "inverse" octahedral‒cubic {Yb8Ba6F71} clusters. These changes in the defect structure lead to an increase in conductivity by a factor of about 100. The fluorine-ionic conductivity of Ba0.75Yb0.25F2.25 is 2.5 × 10-3 S/cm at 500 K. This value exceeds the conductivity of Ba0.69La0.31F2.31 crystal by a factor of 15 (Ba0.69La0.31F2.31 has the best conducting properties among the fluorite phases of the Ba1 - x R x F2 + x family, for which σ was found to increase with a decrease in the atomic number of rare earth element (REE)).

  6. Peculiarities of thermoelectric half-Heusler phase formation in Gd-Ni-Sb and Lu-Ni-Sb ternary systems

    NASA Astrophysics Data System (ADS)

    Romaka, V. V.; Romaka, L.; Horyn, A.; Rogl, P.; Stadnyk, Yu; Melnychenko, N.; Orlovskyy, M.; Krayovskyy, V.

    2016-07-01

    The phase equilibria in the Gd-Ni-Sb and Lu-Ni-Sb ternary systems were studied at 873 K by X-ray and metallographic analyses in the whole concentration range. The interaction of the elements in the Gd-Ni-Sb system results the formation of five ternary compounds at investigated temperature: Gd5Ni2Sb (Mo5SiB2-type), Gd5NiSb2 (Yb5Sb3-type), GdNiSb (MgAgAs-type), Gd3Ni6Sb5 (Y3Ni6Sb5-type), and GdNi0.72Sb2 (HfCuSi2-type). At investigated temperature the Lu-Ni-Sb system is characterized by formation of the LuNiSb (MgAgAs-type), Lu5Ni2Sb (Mo5SiB2-type), and Lu5Ni0.56Sb2.44 (Yb5Sb3-type) compounds. The disordering in the crystal structure of half-Heusler GdNiSb and LuNiSb was revealed by EPMA and studied by means of Rietveld refinement and DFT modeling. The performed electronic structure calculations are in good agreement with electrical transport property studies.

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

    NASA Astrophysics Data System (ADS)

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

    2014-10-01

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

  8. Preparation and upconversion emission modification of Yb, Er co-doped Y2SiO5 inverse opal photonic crystals.

    PubMed

    Yan, Dong; Zhu, Jialun; Yang, Zhengwen; Wu, Hangjun; Wang, Rongfei; Qiu, Jianbei; Song, Zhiguo; Zhou, Dacheng; Yang, Yong; Yin, Zhaoyi

    2014-05-01

    Yb, Er co-doped Y2SiO5 inverse opal photonic crystals with three-dimensionally ordered macroporous were fabricated using polystyrene colloidal crystals as the template. Under 980 nm excitation, the effect of the photonic stopband on the upconversion luminescence of Er3+ ions has been investigated in the Y2SiO5:Yb, Er inverse opals. Significant suppression of the green or red UC emissions was detected if the photonic band-gap overlaps with the Er3+ ions emission band. PMID:24734639

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

    PubMed

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

    2015-09-01

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

  10. K{sub 3}YB{sub 6}O{sub 12}: A new nonlinear optical crystal with a short UV cutoff edge

    SciTech Connect

    Zhao, Sangen; Zhang, Guochun; Yao, Jiyong; Wu, Yicheng

    2012-11-15

    Graphical abstract: Display Omitted Highlights: ► A new non-centrosymmetric borate, K{sub 3}YB{sub 6}O{sub 12}, has been synthesized. ► A K{sub 3}YB{sub 6}O{sub 12} crystal with dimensions of ∼40 mm × 30 mm × 10 mm was successfully grown. ► K{sub 3}YB{sub 6}O{sub 12} exhibits a short UV cutoff edge at 195 nm. ► Powder SHG effect of K{sub 3}YB{sub 6}O{sub 12} is weaker than that of KH{sub 2}PO{sub 4} (KDP). -- Abstract: A new non-centrosymmetric borate, K{sub 3}YB{sub 6}O{sub 12}, has been synthesized by solid state reaction techniques, and a K{sub 3}YB{sub 6}O{sub 12} crystal with dimensions of ∼40 mm × 30 mm × 10 mm was successfully grown by the top-seeded solution growth method using a K{sub 2}O–B{sub 2}O{sub 3}–KBF{sub 4} flux. K{sub 3}YB{sub 6}O{sub 12} crystallizes in the trigonal space group R32 with cell parameters of a = 13.2202(19) Å, c = 30.281(6) Å, and Z = 15. In the structure of K{sub 3}YB{sub 6}O{sub 12}, B{sub 5}O{sub 10} groups are bridged by Y{sub 3}O{sub 12} chains and discrete YO{sub 6} octahedra via corner-sharing, constructing columns packed side by side in a hexagonal motif along the c-axis to form a three-dimensional framework. The three-dimensional framework affords one-dimensional tunnels of 8-membered rings along the b-axis which are occupied by K atoms. K{sub 3}YB{sub 6}O{sub 12} melts incongruently at 941 °C, and exhibits a short UV cutoff edge at 195 nm. The second harmonic generation effect of K{sub 3}YB{sub 6}O{sub 12} is weaker than that of KH{sub 2}PO{sub 4}.

  11. CW and passively Q-switched laser performance of Nd:Lu2SiO5 crystal

    NASA Astrophysics Data System (ADS)

    Xu, Xiaodong; Di, Juqing; Zhang, Jian; Tang, Dingyuan; Xu, Jun

    2016-01-01

    We demonstrated an efficient and controllable dual-wavelength continuous-wave (CW) laser of Nd:Lu2SiO5 (Nd:LSO) crystal. The maximum output power was 3.02 W at wavelength of 1075 nm and 1079 nm, and with increasing of absorbed pump power, the ratio of 1079 nm laser rose. The slope efficiency of 65.6% and optical-to-optical conversion efficiency of 63.3% were obtained. The passively Q-switched laser properties of Nd:LSO were investigated for the first time. The shortest pulse, maximum pulse energy and peak power were 11.58 ns, 29.05 μJ and 2.34 kW, respectively.

  12. Syntheses and crystal structures of the rare-earth metal(III) bromide ortho-oxidotungstates(VI) with the formula REBr[WO4] (RE = Y, Gd-Yb)

    NASA Astrophysics Data System (ADS)

    Schustereit, Tanja; Schleid, Thomas; Hartenbach, Ingo

    2015-10-01

    The rare-earth metal(III) bromide ortho-oxidotungstates(VI) with the formula REBr[WO4] crystallize triclinically in space group P 1 bar (a = 689-693, b = 715-728, c = 1074-1107 pm, α = 103-106, β ≈ 108 and γ = 93-95°, Z = 4) for RE = Y, Gd-Yb. Their crystal structure is isotypic with the most examples of the formally analogous lanthanoid(III) bromide oxidomolybdates(VI) REBr[MoO4] with RE = Y, Pr, Nd, Sm, Gd-Lu. It contains two crystallographically different rare-earth metal(III) cations with coordination numbers of seven plus one for (RE1)3+ and seven for (RE2)3+. The (RE1)3+ cations are surrounded by three Br- and four plus one O2- anions forming distorted trigonal dodecahedra, while the (RE2)3+ cations exhibit a coordination environment of one Br- and six O2- anions in the shape of a monocapped trigonal prism. Furthermore, the structure contains two crystallographically independent, isolated tetrahedral [WO4]2- units. All these polyhedra are fused together to form 1 ∞ {REBr[WO4]} chains running along [012]. Since the title compounds, synthesized by solid-state reactions from the underlying binaries, emerge as pure phases according to X-ray powder diffractometry, spectroscopic and magnetic measurements were performed.

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

    SciTech Connect

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

    2011-08-15

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

  14. Simultaneous tri-wavelength laser operation at 916, 1086, and 1089 nm of diode-pumped Nd:LuVO4 crystal

    NASA Astrophysics Data System (ADS)

    Shen, Bingjun; Jin, Lihong; Zhang, Jiajia; Tian, Jian

    2016-09-01

    We report a diode-pumped continuous-wave tri-wavelength Nd:LuVO4 laser operating at 916, 1086, and 1089 nm. A theoretical analysis has been introduced to determine the threshold conditions for simultaneous tri-wavelength laser operation. Using a T-shaped cavity, we realized efficient tri-wavelength operation at 4F3/2  →  4I9/2 and 4F3/2  →  4I11/2 transitions for Nd:LuVO4 crystal, simultaneously. The maximum output power was 2.8 W, which included 916, 1086, and 1089 nm, and the optical conversion efficiency was 15.1%. To our knowledge, this is the first work that realizes simultaneous tri-wavelength Nd:LuVO4 laser operation.

  15. Growth, Thermal and Spectral Properties of Er3+-Doped and Er3+/Yb3+-Codoped Li3Ba2La3(WO4)8 Crystals

    PubMed Central

    Xiao, Bin; Lin, Zhoubin; Zhang, Lizhen; Huang, Yisheng; Wang, Guofu

    2012-01-01

    This paper reports the growth and spectral properties of Er3+-doped and Er3+/Yb3+-codoped Li3Ba2La3(WO4)8 crystals. The Er3+: Li3Ba2La3(WO4)8 crystal with dimensions of 56 mm×28 mm×9 mm and Er3+/Yb3+: Li3Ba2La3(WO4)8 crystal with dimensions of 52 mm×24 mm×8 mm were obtained by the top-seeded solution growth (TSSG) method. Thermal expansion coefficients and thermal conductivity of both crystals were measured. The spectroscopic characterizations of both crystals were investigated. The spectroscopic analysis reveals that the Er3+/Yb3+: Li3Ba2La3(WO4)8 crystal has much better optical properties than the Er3+: Li3Ba2La3(WO4)8 crystal, thus it may become a potential candidate for solid-state laser gain medium material. PMID:22808214

  16. Magneto-optical spectroscopy and optical detection of EPR spectra of Yb3+ paramagnetic centers with cubic symmetry in single crystals MeF2 ( Me = Cd, Ca, Pb)

    NASA Astrophysics Data System (ADS)

    Gerasimov, K. I.; Falin, M. L.

    2009-04-01

    Cubic paramagnetic centers formed by Yb3+ impurity ions in fluorite-type crystals MeF2 ( Me = Cd, Ca, Pb) have been investigated using electron paramagnetic resonance, magnetic circular dichroism, magnetic circular polarization of luminescence, Zeeman splitting of optical absorption and luminescence lines, and optical detection of electron paramagnetic resonance. The g factors of the 2Γ7 state in the excited multiplet 2 F 5/2 of Yb3+ ions in Me F2 crystals, the hyperfine interaction constant 171 A (171Yb) for the excited multiplet 2 F 5/2 in the CaF2 crystal, and the energies and symmetry properties of all energy levels of Yb3+ ions in MeF2 crystals are determined. The crystal-field parameters for the crystals under investigation are calculated.

  17. Crystal growth and characterization of Yb{sup 3+}-doped Gd{sub 3}Ga{sub 5}O{sub 12}

    SciTech Connect

    Novoselov, A. . E-mail: anvn@tagen.tohoku.ac.jp; Kagamitani, Y.; Kasamoto, T.; Guyot, Y.; Shibata, H.; Yoshikawa, A.; Boulon, G.

    2007-01-18

    Single crystals of (Yb {sub x}Gd{sub 1-x}){sub 3}Ga{sub 5}O{sub 12} (0.0 {<=} x {<=} 1.0) have been grown by the micro-pulling-down method. Formation of continuous solid solutions with a garnet structure was confirmed. Composition dependence of the lattice constant, thermal diffusivity, specific heat capacity and thermal conductivity was investigated. Assignment of the Yb{sup 3+}-energy levels in Gd{sub 3}Ga{sub 5}O{sub 12}-host lattice has been performed by using absorption, emission and Raman spectroscopy measurements at both, room temperature and at 12 K.

  18. Energy Transfer and 1.8 µm Emission in Tm³⁺/Yb³⁺ Co-Doped LiYF₄Crystal.

    PubMed

    Yang, Shuo; Xia, Haiping; Zhang, Jiazhong; Jiang, Yongzhang; Gu, Xuemei; Zhang, Jianli; Wang, Dongjie; Jiang, Haochuan; Chen, Baojiu

    2016-01-01

    LiYF₄ single crystals co-doped with various Tm³⁺/Yb³⁺ concentrations were grown using the Bridg- man method. The luminescent properties of the crystals were investigated through emission spectra, emission cross section, and decay curves under excitation by 980 nm. Compared with the Tm³⁺ single-doped LiYF₄ crystal, an enhanced emission band from 1600 to 2150 nm was observed upon excitation of a 980 nm laser diode. The energy transfer from Yb³⁺ to Tm³⁺ and the optimum fluo- rescence emission around 1.80 µm of Tm³⁺ ion were investigated. The maximum emission cross section at 1.8 µm was calculated to be 1.48 x 10⁻²⁰ cm² according to the measured absorption spectrum. The high energy transfer efficiency of 86.5% from Yb³⁺ to Tm³⁺ ion demonstrate that the Yb³⁺ ions can efficiently sensitize the Tm³⁺ ions. PMID:27398484

  19. Polarized infra-red and Raman spectra of monoclinic α-KLn(WO 4) 2 single crystals (Ln = Sm—Lu, Y)

    NASA Astrophysics Data System (ADS)

    Hanuza, J.; Macalik, L.

    The polarized i.r. and Raman spectra for single crystals of α-KLn(WO 4) 2 family were measured, where Ln = Y and lanthanides from Sm to Lu. The molecular and crystal structures were analysed in terms of C 2/ c = C62 h (Z = 4) monoclinic unit cell. A comparison of vibrational spectra measured for isomorphic crystals of several RE elements was used to describe the internal and external optic modes. On that basis the hexacoordination of tungsten atoms and polymeric (W 2O 10) n clusters with ? and ? bridge systems were discussed.

  20. Octave-spanning spectrum generation in tapered silica photonic crystal fiber by Yb:fiber ring laser above 500 MHz.

    PubMed

    Jiang, Tongxiao; Wang, Guizhong; Zhang, Wei; Li, Chen; Wang, Aimin; Zhang, Zhigang

    2013-02-15

    We report octave-spanning spectrum generated in a tapered silica photonic crystal fiber by a mode-locked Yb:fiber ring laser at a repetition rate as high as 528 MHz. The output pulses from this laser were compressed to 62 fs. By controlling the hole expansion and core diameter, a silica PCF was tapered to 20 cm with an optimal d/Λ ratio of 0.6. Pulses with the energy of 280 pJ and the peak power of 4.5 kW were injected into the tapered fiber and the pulse spectrum was expanded from 500 to 1600 nm at the level of -30 dB.

  1. Yb:YAG single-crystal fiber amplifiers for picosecond lasers using the divided pulse amplification technique.

    PubMed

    Lesparre, Fabien; Gomes, Jean Thomas; Délen, Xavier; Martial, Igor; Didierjean, Julien; Pallmann, Wolfgang; Resan, Bojan; Druon, Frederic; Balembois, François; Georges, Patrick

    2016-04-01

    A two-stage master-oscillator power-amplifier (MOPA) system based on Yb:YAG single-crystal-fiber (SCF) technology and designed for high peak power is studied to significantly increase the pulse energy of a low-power picosecond laser. The first SCF amplifier has been designed for high gain. Using a gain medium optimized in terms of doping concentration and length, an optical gain of 32 dB has been demonstrated. The second amplifier stage designed for high energy using the divided pulse technique allows us to generate a recombined output pulse energy of 2 mJ at 12.5 kHz with a pulse duration of 6 ps corresponding to a peak power of 320 MW. Average powers ranging from 25 to 55 W with repetition rates varying from 12.5 to 500 kHz have been demonstrated. PMID:27192304

  2. Generation of radially and azimuthally polarized beams in Yb:YAG laser with intra-cavity lens and birefringent crystal.

    PubMed

    Thirugnanasambandam, Manasadevi P; Senatsky, Yuri; Ueda, Ken-ichi

    2011-01-31

    We demonstrated the operation of cw diode-pumped Yb:YAG laser in radial or azimuthal polarized (RP or AP) beams using a combination of birefringent uniaxial crystal (c-cut YVO4 or α-BBO) and lens as intra-cavity elements. RP and AP doughnut modes (M2 = 2-2.5, polarization extinction ratio 50-100:1) with output power up to 60 mW were generated. Apart from doughnut modes, RP or AP ring-like off-axis oscillations and multi-ring beams with mixed RP and AP were also observed at the output of this laser scheme. Using intra-cavity short focus lenses with spherical aberrations AP or RP modes of higher orders was obtained. Mechanism of mode selection in the laser is discussed. The large variety of beams with axially symmetric polarizations from the output of the proposed laser scheme may find applications in different fields.

  3. Structural characterization of Lu{sub 1.8}Y{sub 0.2}SiO{sub 5} crystals

    SciTech Connect

    Chiriu, Daniele; Faedda, Nicola; Lehmann, Alessandra Geddo; Ricci, Pier Carlo; Anedda, Alberto; Desgreniers, Serge; Fortin, Emery

    2007-08-01

    The structural and vibrational properties of Lu{sub 1.8}Y{sub 0.2}SiO{sub 5} (LYSO) single crystals were investigated by means of Raman spectroscopy and x-ray diffraction measurements. Unit cell parameters and bond lengths were determined by Rietveld refinement of the collected x-ray diffraction powder spectra. By comparison with the vibrational spectra of the parent compounds Lu{sub 2}SiO{sub 5} and Y{sub 2}SiO{sub 5} and by using polarized Raman measurements, we propose the assignment of the principal vibrational modes of LYSO crystals. The strict connection of Raman spectra of the LYSO solid solution and of the pure lutetium and yttrium crystals, as well as the analysis of the polarized measurements, confirms that LYSO structure adopts the C2/c space group symmetry. The structural analogies of LYSO with the pure compound Lu{sub 2}SiO{sub 5} are further shown by means of high pressure Raman spectroscopy, and the possibility of considering the LYSO crystal analogous to the LSO structure with a tensile stress between 0.25 and 0.80 GPa is discussed.

  4. Crystal growth, optical properties, and continuous-wave laser operation of Nd3+-doped Lu2SiO5 crystal

    NASA Astrophysics Data System (ADS)

    Li, D. Z.; Xu, X. D.; Zhou, D. H.; Xia, C. T.; Wu, F.; Xu, J.; Cong, Z. H.; Zhang, J.; Tang, D. Y.

    2011-01-01

    High quality Nd3+-doped Lu2SiO5 (Nd:LSO) crystal has been grown by the Czochralski technique. The cell parameters were analyzed with X-ray diffraction (XRD). Room temperature absorption and fluorescence spectra and fluorescence lifetime of the Nd:LSO crystal were measured and analyzed. The Judd-Ofelt intensity parameters Ω2,4,6 were obtained to be 2.59, 4.90, and 5.96×10-20 cm2, respectively. The absorption and emission cross sections and the branching ratios were calculated. The peak emission cross section is 5.8 and 6.6×10-20 cm2 at 1075 and 1079 nm, respectively, with full width at half maximum (FWHM) of 2.8 and 5.1 nm in turn. Pumped by a laser diode, a maximum 2.54 W continuous-wave laser output has been obtained with a slope efficiency of 32%. All the results show that this crystal is a promising laser material.

  5. Dual-modal upconversion fluorescent/X-ray imaging using ligand-free hexagonal phase NaLuF4:Gd/Yb/Er nanorods for blood vessel visualization.

    PubMed

    Zeng, Songjun; Wang, Haibo; Lu, Wei; Yi, Zhigao; Rao, Ling; Liu, Hongrong; Hao, Jianhua

    2014-03-01

    Visualization of blood vessel of lung can improve the detection of the lung and pulmonary vascular diseases. However, research on visualization of blood vessel of lung using the new generation upconversion nanoprobes is still scarce. Herein, high quality hexagonal phase NaLuF4:Gd/Yb/Er nanorods were synthesized by a simple hydrothermal method through doping Gd(3+). Doping Gd can not only promote the phase transformation from cubic to hexagonal and the shape evolution from microtube to rod-like, but also provide an additional magnetic properties for biomedical application. The as-prepared nanorods were further converted to water solubility by treating with HCl for eliminating the capped oleic acid. The ligand-free nanorods were successfully used for high-contrast upconversion fluorescent bioimaging of HeLa cells. Moreover, the in vivo synergistic upconversion fluorescent and X-ray imaging of nude mice were demonstrated by subcutaneously and intravenously administrated the ligand-free nanorods. The X-ray signals were matched well with the upconversion signal, indicating the successfully synergistic bioimaging. The ex-vivo X-ray and upconversion fluorescent imaging of various organs revealed that the nanorods were mainly accumulated in liver and lung. More importantly, the blood vessel of the lung can be readily visualized when these ligand-free nanorods are intravenously injected. Apart from the synergistic X-ray and upconversion bioimaging, the ligand-free nanorods can also possess excellent paramagnetic property for potential magnetic resonance imaging contrast agent. Our results have demonstrated the enhanced visualization of blood vessel of lung performed by dual-modal bioimaging of X-ray and upconversion fluorescence, revealing the great promise of these nanoprobes in angiography imaging. Such a new technique enables the integration of the two bioimaging techniques by combining their collective strengths and minimizing their shortcomings.

  6. Study of energy transfer in gadolinium-gallium garnet crystals doped with Yb{sup 3+} and Ho{sup 3+} ions

    SciTech Connect

    Belovolov, A M; Belovolov, M I; Dianov, Evgenii M; Ivanov, M A; Kochurikhin, V V; Randoshkin, V V

    2006-08-31

    The luminescence kinetics of Yb{sup 3+} donors and Ho{sup 3+} acceptors is quantitatively studied in gallium-gadolinium garnet (GGG) crystals doped with Yb{sup 3+} and Ho{sup 3+} ions. It is shown that the sensitisation of transitions in Ho{sup 3+} ions occurs due to migration-accelerated (hopping) energy transfer. The microparameters of donor-donor energy transfer are determined at 300 and 77 K. The microparameters of donor-acceptor energy transfer are found at the same temperatures at the first stage of successive sensitisation (resulting in the population of the {sup 5}I{sub 6} state of Ho{sup 3+} ions) and at the second stage of successive sensitisation of the {sup 5}S{sub 2}, {sup 5}F{sub 4{yields}}{sup 5}I{sub 8} transition in Ho{sup 3+} ions. At the second stage of sensitisation, the values of the microparameter of reverse energy transfer are also determined. The possibility of obtaining lasing at sensitised transitions in Ho{sup 3+} ions in Yb{sup 3+}:Ho{sup 3+}:GGG crystals pumped into the absorption band of Yb{sup 3+} ions is discussed. (papers devoted to the 90th anniversary of a.m.prokhorov)

  7. Coupling of Ag Nanoparticle with Inverse Opal Photonic Crystals as a Novel Strategy for Upconversion Emission Enhancement of NaYF4: Yb(3+), Er(3+) Nanoparticles.

    PubMed

    Shao, Bo; Yang, Zhengwen; Wang, Yida; Li, Jun; Yang, Jianzhi; Qiu, Jianbei; Song, Zhiguo

    2015-11-18

    Rare-earth-ion-doped upconversion (UC) nanoparticles have generated considerable interest because of their potential application in solar cells, biological labeling, therapeutics, and imaging. However, the applications of UC nanoparticles were still limited because of their low emission efficiency. Photonic crystals and noble metal nanoparticles are applied extensively to enhance the UC emission of rare earth ions. In the present work, a novel substrate consisting of inverse opal photonic crystals and Ag nanoparticles was prepared by the template-assisted method, which was used to enhance the UC emission of NaYF4: Yb(3+), Er(3+) nanoparticles. The red or green UC emissions of NaYF4: Yb(3+), Er(3+) nanoparticles were selectively enhanced on the inverse opal substrates because of the Bragg reflection of the photonic band gap. Additionally, the UC emission enhancement of NaYF4: Yb(3+), Er(3+) nanoparticles induced by the coupling of metal nanoparticle plasmons and photonic crystal effects was realized on the Ag nanoparticles included in the inverse opal substrate. The present results demonstrated that coupling of Ag nanoparticle with inverse opal photonic crystals provides a useful strategy to enhance UC emission of rare-earth-ion-doped nanoparticles. PMID:26496243

  8. Coupling of Ag Nanoparticle with Inverse Opal Photonic Crystals as a Novel Strategy for Upconversion Emission Enhancement of NaYF4: Yb(3+), Er(3+) Nanoparticles.

    PubMed

    Shao, Bo; Yang, Zhengwen; Wang, Yida; Li, Jun; Yang, Jianzhi; Qiu, Jianbei; Song, Zhiguo

    2015-11-18

    Rare-earth-ion-doped upconversion (UC) nanoparticles have generated considerable interest because of their potential application in solar cells, biological labeling, therapeutics, and imaging. However, the applications of UC nanoparticles were still limited because of their low emission efficiency. Photonic crystals and noble metal nanoparticles are applied extensively to enhance the UC emission of rare earth ions. In the present work, a novel substrate consisting of inverse opal photonic crystals and Ag nanoparticles was prepared by the template-assisted method, which was used to enhance the UC emission of NaYF4: Yb(3+), Er(3+) nanoparticles. The red or green UC emissions of NaYF4: Yb(3+), Er(3+) nanoparticles were selectively enhanced on the inverse opal substrates because of the Bragg reflection of the photonic band gap. Additionally, the UC emission enhancement of NaYF4: Yb(3+), Er(3+) nanoparticles induced by the coupling of metal nanoparticle plasmons and photonic crystal effects was realized on the Ag nanoparticles included in the inverse opal substrate. The present results demonstrated that coupling of Ag nanoparticle with inverse opal photonic crystals provides a useful strategy to enhance UC emission of rare-earth-ion-doped nanoparticles.

  9. High-pressure high-temperature synthesis and crystal structure of the isotypic rare earth (RE)-thioborate-sulfides RE{sub 9}[BS{sub 3}]{sub 2}[BS{sub 4}]{sub 3}S{sub 3}, (RE=Dy-Lu)

    SciTech Connect

    Borna, Marija; Hunger, Jens; Ormeci, Alim; Zahn, Dirk; Burkhardt, Ulrich; Carrillo-Cabrera, Wilder; Cardoso-Gil, Raul; Kniep, Ruediger

    2011-02-15

    Application of high-pressure high-temperature conditions (3.5 GPa at 1673 K for 5 h) to mixtures of the elements (RE:B:S=1:3:6) yielded crystalline samples of the isotypic rare earth-thioborate-sulfides RE{sub 9}[BS{sub 3}]{sub 2}[BS{sub 4}]{sub 3}S{sub 3}, (RE=Dy-Lu), which crystallize in space group P6{sub 3} (Z=2/3) and adopt the Ce{sub 6}Al{sub 3.33}S{sub 14} structure type. The crystal structures were refined from X-ray powder diffraction data by applying the Rietveld method. Dy: a=9.4044(2) A, c=5.8855(3) A; Ho: a=9.3703(1) A, c=5.8826(1) A; Er: a=9.3279(12) A, c=5.8793(8) A; Tm: a=9.2869(3) A, c=5.8781(3) A; Yb: a=9.2514(5) A, c=5.8805(6) A; Lu: a=9.2162(3) A, c=5.8911(3) A. The crystal structure is characterized by the presence of two isolated complex ions [BS{sub 3}]{sup 3-} and [BS{sub 4}]{sup 5-} as well as [{open_square}(S{sup 2-}){sub 3}] units. -- Graphical abstract: Isotypic rare earth-thioborate-sulfides RE{sub 9}[BS{sub 3}]{sub 2}[BS{sub 4}]{sub 3}S{sub 3}, (RE=Dy-Lu) were prepared by application of high-pressure high-temperature conditions to mixtures of the elements. Their crystal structures are characterized by presence of the two isolated complex ions [BS{sub 3}]{sup 3-} and [BS{sub 4}]{sup 5-} as well as [{open_square}(S{sup 2-}){sub 3}] units. Quantum mechanical calculations revealed the arrangement of the intrinsic vacancies. Display Omitted Research Highlights: {yields} Application of high-pressure high-temperature conditions to mixtures of the elements yields crystalline samples of the isotypic rare earth-thioborate-sulfides RE{sub 9}[BS{sub 3}]{sub 2}[BS{sub 4}]{sub 3}S{sub 3}, (RE=Dy-Lu). {yields} RE{sub 9}[BS{sub 3}]{sub 2}[BS{sub 4}]{sub 3}S{sub 3}, (RE=Dy-Lu) crystallize in space group P6{sub 3} (Z=2/3) and adopt the Ce{sub 6}Al{sub 3.33}S{sub 14} structure type. {yields} The crystal structure of RE{sub 9}[BS{sub 3}]{sub 2}[BS{sub 4}]{sub 3}S{sub 3}, (RE=Dy-Lu) is characterized by the presence of two isolated complex ions [BS{sub 3

  10. Upconversion luminescence in Yb 3+-doped yttrium aluminum garnets

    NASA Astrophysics Data System (ADS)

    Xu, Xiaodong; Zhao, Zhiwei; Song, Pingxin; Jiang, Benxue; Zhou, Guoqing; Xu, Jun; Deng, Peizhen; Bourdet, Gilbert; Christophe Chanteloup, Jean; Zou, Ji-Ping; Fulop, Annabelle

    2005-03-01

    In this paper, we present results on upconversion luminescence performed on Yb 3+-doped yttrium aluminum garnets under 940 nm excitation. The upconversion luminescence was ascribed to Yb 3+ cooperative luminescence and the presence of rare earth impurity ions. The cooperative luminescence spectra as a function of Yb concentration were measured and the emission intensity variation with Yb concentration was discussed. Yb 3+ energy migration quenched the cooperative luminescence of Yb:YAG crystals with doping level over 15 at%.

  11. Nanostructured crystals of fluorite phases Sr{sub 1−x}R{sub x}F{sub 2+x} (R Are Rare Earth Elements) and their ordering: 10. Ordering under spontaneous crystallization and annealing of Sr{sub 1−x}R{sub x}F{sub 2+x} Alloys (R = Tb-Lu, Y) with 23.8–36.1 mol % RF{sub 3}

    SciTech Connect

    Sulyanova, E. A. Karimov, D. N.; Sulyanov, S. N.; Zhmurova, Z. I.; Golubev, A. M.; Sobolev, B. P.

    2015-01-15

    The products of spontaneous crystallization (at a cooling rate of ∼200 K/min) of Sr{sub 1−x}R{sub x}F{sub 2+x} melts in the homogeneity range of the fluorite phase have been investigated. Thirty-two irrational compositions with 23.8–36.1 mol % RF{sub 3} and eight rational Sr{sub 2}RF{sub 7} compositions are obtained. With respect to the RF{sub 3} content, these compositions form five groups: (1) Sr{sub 0.762}R{sub 0.238}F{sub 2.238} (23.8% RF{sub 3}), (2) Sr{sub 0.744}R{sub 0.256}F{sub 2.256} (25.6%), (3) Sr{sub 0.718}R{sub 0.282}F{sub 2.282} (28.2%), (4) Sr{sub 2}RF{sub 7} (33.3%), and (5) Sr{sub 0.639}R{sub 0.361}F{sub 2.361} (36.1%). R = Tb-Lu, Y for all groups. Quenching melts of group 5 with R = Tb, Dy, and Ho leads to the formation of ordered phases with the trigonal distortion of the rhβ-Na{sub 7}Zr{sub 6}F{sub 31} type, while for melts of group 5 with R = Lu, quenching yields a phase of the trigonal rhα′-Sr{sub 4}Lu{sub 3}F{sub 17} type. In group 5 with R = Y, Er, Tm, or Yb and in groups 1–4 with all REEs, fluorite phases are formed. Annealing at 900 ± 20°C for 96 h with subsequent cooling at a rate of ∼200 K/min expands the variety of ordered phases: a phase with a new r type of orthorhombic distortion is formed in group 1 with R = Lu, in group 2 with R = Tm or Lu, and in group 3 with R = Ho-Lu, Y; a t-Sr{sub 2}RF{sub 7} phase with tetragonal distortion is formed in group 4 with R = Tb-Er, Y; and a phase of trigonal rhα′ type is formed in group 5 with R = Y, Yb, or Lu. A fluorite phase arises in group 1 with R = Tb-Lu, Y as a result of quenching and annealing. The tendency to ordering becomes more pronounced with an increase in the RF{sub 3} content and REE atomic number. The annealing conditions do not provide equilibrium or the completely ordered state of all alloys.

  12. Transparent oxyfluoride glass ceramics co-doped with Er{sup 3+} and Yb{sup 3+} - Crystallization and upconversion spectroscopy

    SciTech Connect

    Gugov, I.; Mueller, M.; Ruessel, C.

    2011-05-15

    Transparent glass ceramics in the system SiO{sub 2}-B{sub 2}O{sub 3}-PbO-CdO-PbF{sub 2}-CdF{sub 2}-YbF{sub 3}-ErF{sub 3} showing infrared to visible anti-Stokes (upconversion) luminescence are studied in the present work. The glass compositions have been optimized in order to reduce the melting temperature and, hence, to obtain laboratory scale samples with good optical quality. Erbium-doped nanoscale Pb{sub 4}Yb{sub 3}F{sub 17} crystals are precipitated in the precursor glasses during annealing at temperatures 30-40 K above T{sub g}. A kinetically self-constrained growth explains the nano sizes of the crystals. Both the Stokes and anti-Stokes luminescence spectra of glasses could be explained with clustering of the Yb{sup 3+} and Er{sup 3+} ions in fluorine-rich regions. At the annealing temperature these regions act as nucleation precursors. The crystal growth further enhances the local concentration of these ions. Consequently, a series of energy transfer and energy cross relaxation processes occurs between adjacent rare earth ions leading to the observed luminescence spectra of the glass ceramics studied. -- Graphical abstract: A highly viscous shell (shown in the picture in dark blue) is build around the growing crystal (white circles). When the shell's T{sub g} approaches the annealing temperature, the crystal growth is fully suppressed for kinetic reasons. The upconversion luminescence, resulting from the simultaneous absorption of two and even three infrared photons, is depicted schematically in the right part of the figure. Display Omitted Highlights: {yields} New oxyfluoride glass compositions with reduced melting temperature are formulated. {yields} The phase Pb{sub 4}Yb{sub 3}F{sub 17} doped with Er{sup 3+} ions crystallizes in these glasses. {yields} A kinetically self-constrained growth explains the nano sizes of the crystals. {yields} Clustering of Yb{sup 3+}, Er{sup 3+} and Pb{sup 2+} ions into fluorine-rich glass regions is observed. {yields} The

  13. Electronic excitations and defect creation in wide-gap MgO and Lu3Al5O12 crystals irradiated with swift heavy ions

    NASA Astrophysics Data System (ADS)

    Lushchik, A.; Kärner, T.; Lushchik, Ch.; Schwartz, K.; Savikhin, F.; Shablonin, E.; Shugai, A.; Vasil'chenko, E.

    2012-09-01

    A comparative study of radiation effects in two groups of single crystals with an energy gap of about 8 eV possessing drastically different lattice and electron energy structures - fcc MgO and Lu3Al5O12 with 160 atoms per a unit cell - has been performed using crystal irradiation with vacuum ultraviolet radiation, electrons, fast fission neutrons and, in particular, ˜2.2 GeV uranium ions. In MgO with the absence of self-trapping for valence holes, the localization of holes near impurity ions or bivacancies (both as-grown or induced by a plastic stress) has been detected. In LuAG, the peculiarities of the motion of hole polarons and excitons, the radius of which is smaller than the size of a unit cell, have been revealed and analysed. The irradiation of MgO and LuAG with swift heavy ions providing an extremely high density of electronic excitations causes also the nonimpact creation of long-lived Frenkel defects in an oxygen sublattice.

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

    NASA Astrophysics Data System (ADS)

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

    2015-01-01

    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

  15. Crystal field disorder effects in the optical spectra of Nd{sup 3+} and Yb{sup 3+}-doped calcium lithium niobium gallium garnets laser crystals and ceramics

    SciTech Connect

    Lupei, V.; Lupei, A.; Gheorghe, C.; Gheorghe, L.; Achim, A.; Ikesue, A.

    2012-09-15

    The optical spectroscopic properties of RE{sup 3+} (Nd, 1 at. % or Yb, 1 to 10 at. %)-doped calcium-lithium-niobium-gallium garnet (CLNGG) single crystals and ceramics in the 10 K-300 K range are analyzed. In these compositionally disordered materials, RE{sup 3+} substitute Ca{sup 2+} in dodecahedral sites and the charge compensation is accomplished by adjusting the proportion of Li{sup +}, Nb{sup 5+}, and Ga{sup 3+} to the doping concentration. The crystals and ceramics show similar optical spectra, with broad and structured (especially at low temperatures) bands whose shape depends on temperature and doping concentration. At 10 K, the Nd{sup 3+4}I{sub 9/2}{yields}{sup 4}F{sub 3/2,5/2} and Yb{sup 3+2}F{sub 7/2}{yields}{sup 2}F{sub 5/2} absorption bands, which show prospect for diode laser pumping, can be decomposed in several lines that can be attributed to centers with large differences in the crystal field. The positions of these components are the same, but the relative intensity depends on the doping concentration and two main centers dominate the spectra. Non-selective excitation evidences broad emission bands, of prospect for short-pulse laser emission, whereas the selective excitation reveals the particular emission spectra of the various centers. The modeling reveals that the nonequivalent centers correspond to RE{sup 3+} ions with different cationic combinations in the nearest octahedral and tetrahedral coordination spheres, and the most abundant two centers have 4Nb and, respectively, 3Nb1Li in the nearest octahedral sphere. At 300 K, the spectral resolution is lost. It is then inferred that the observed optical bands are envelopes of the spectra of various structural centers, whose resolution is determined by the relative contribution of the temperature-dependent homogeneous broadening and the effects of crystal field disordering (multicenter structure, inhomogeneous broadening). The relevance of spectroscopic properties for selection of pumping

  16. Intermediate valence to heavy fermion through a quantum phase transition in Yb3(Rh 1 -xTx )4Ge13 (T =Co ,Ir ) single crystals

    NASA Astrophysics Data System (ADS)

    Rai, Binod K.; Oswald, Iain W. H.; Chan, Julia Y.; Morosan, E.

    2016-01-01

    Single crystals of Yb3(Rh 1 -xTx )4Ge13 (T =Co ,Ir ) have been grown using the self-flux method. Powder x-ray diffraction data on these compounds are consistent with the cubic structure with space group P m 3 ¯n . Intermediate-valence behavior is observed in Yb3(Rh 1 -xTx )4Ge13 upon T = Co doping, while T = Ir doping drives the system into a heavy-fermion state. Antiferromagnetic order is observed in the Ir-doped samples Yb3(Rh 1 -xTx )4Ge13 for 0.5 Yb3Ir 4Ge13 . With decreasing x , the magnetic order is suppressed towards a quantum critical point around xc = 0.5, accompanied by non-Fermi-liquid behavior evidenced by logarithmic divergence of the specific heat and linear temperature dependence of the resistivity. The Fermi-liquid behavior is recovered with the application of large magnetic fields.

  17. Intermediate valence to heavy fermion through a quantum phase transition in Yb3(Rh1-xTx)4Ge13 (T = Co, Ir) single crystals

    NASA Astrophysics Data System (ADS)

    Rai, Binod; Morosan, Emilia

    Single crystals of Yb3(Rh1-x Tx)4Ge13 (T = Co, Ir) have been grown using the self-flux method. Powder X-ray diffraction data on these compounds are consistent with the cubic structure with space group Pm 3 n . Intermediate valence behavior is observed in Yb3(Rh1-x Tx)4Ge13 upon T = Co doping, while T = Ir doping drives the system into a heavy fermion state. Antiferromagnetic order is observed in the Ir-doped samples Yb3(Rh1-x Tx)4Ge13 for 0.5 < x <= 1 with TN = 0.96 K for Yb3Ir4Ge13. With decreasing x, the magnetic order is suppressed towards a quantum critical point around xc = 0.5, accompanied by non-Fermi liquid behavior evidenced by logarithmic divergence of the specific heat and linear temperature dependence of the resistivity. The Fermi liquid behavior is recovered with the application of large magnetic fields. Gordon and Betty Moore Foundation EPiQS initiative through Grant GBMF4417 and Welch Foundation.

  18. Preparation and photoluminescence properties of RE:Na{sub 3}La{sub 9}O{sub 3}(BO{sub 3}){sub 8} (RE=Er, Yb) crystals

    SciTech Connect

    Liu Zuoliang; Zhang, Guochun; Zhang Jianxiu; Bai Xiaoyan; Fu Peizhen; Wu Yicheng

    2010-06-15

    Using Na{sub 2}CO{sub 3}-H{sub 3}BO{sub 3}-NaF as fluxes, transparent RE:Na{sub 3}La{sub 9}O{sub 3}(BO{sub 3}){sub 8} (abbr. RE:NLBO, RE=Er, Yb) crystals have been grown by the top seed solution growth (TSSG) method. The X-ray powder diffraction analysis shows that the RE:NLBO crystals have the same structure with NLBO. The element contents were determined by molar to be 0.64% Er{sup 3+} in Er:NLBO, 2.70% Yb{sup 3+} in Yb:NLBO, respectively. The polarized absorption spectra of RE:NLBO have been measured at room temperature and show that both Er:NLBO and Yb:NLBO have a strong absorption bands near 980 nm with wide FWHM (Full Wave at Half Maximum) (21 nm for Er:NLBO and 25 nm for Yb:NLBO). Fluorescence spectra have been recorded. Yb:NLBO has the emission peaks at 985 nm, 1028 nm and 1079 nm and the emission peak of Er:NLBO is at 1536 nm. Spectral parameters have been calculated by the Judd-Ofelt theory for Er:NLBO and the reciprocity method for Yb:NLBO, respectively. The calculated values show that Er:NLBO is a candidate of 1.55 {mu}m laser crystals and Yb:NLBO is a candidate for self-frequency doubling crystal. - Graphical abstract: Fluorescence spectra show the emission peaks at 985, 1028 and 1079 nm of Yb:NLBO and at 1536 nm of Er:NLBO.

  19. Polymorphism and phase transitions of K_3Lu(PO_4)_2

    NASA Astrophysics Data System (ADS)

    Farmer, J. Matt; Boatner, Lynn A.; Chakoumakos, Bryan C.; Mandrus, David; Jin, Rongying

    2001-03-01

    Alkali lanthanide double phosphates have been studied for uses as long-wavelength scintillators for γ-ray detection using Si photodiodes. This family of compounds exhibits layered crystal structures, in the sequence lanthanide, phosphate alkali, alkali, alkali - phosphate. Current research has focused on K_3Lu(PO_4)_2. At room temperature, this compound is hexagonal, P 3 space group symmetry. The Lu ion is six-coordinated to the oxygen atoms of the phosphate groups. Our group has recently characterized two lower-temperature phases of K_3Lu(PO_4)2 using single-crystal XRD and powder neutron diffraction. The first transition occurs at 230 K, with a transformation to monoclinic P 2_1/m space group symmetry, and the Lu still retains six coordination. Another transition occurs at 130 K, with a small change in the cell volume, keeping the same P 2_1/m space group symmetry; however, one of the phosphate groups rotates to increase the coordination of the Lu ion to seven. This new structure is isostructural with the room-temperature form of K_3Yb(PO_4)_2. A heat capacity versus temperature study of K_3Lu(PO_4)2 confirms the transformations and indicates a large thermal hysteresis as the crystals are thermally cycled between 15 and 295 K. Research sponsored by the U.S. Department of Energy under contract DE-AC05-00OR22725 with the Oak Ridge National Laboratory, managed by UT-Battelle, LLC.

  20. Crystal structure and properties of high-pressure-synthesized BiRhO{sub 3}, LuRhO{sub 3}, and NdRhO{sub 3}

    SciTech Connect

    Yi, Wei; Liang, Qifeng; Matsushita, Yoshitaka; Tanaka, Masahiko; Hu, Xiao; Belik, Alexei A.

    2013-04-15

    GdFeO{sub 3}-type orthorhombic perovskite compounds BiRhO{sub 3}, LuRhO{sub 3}, and NdRhO{sub 3} were prepared using a high-pressure and high-temperature technique at 6 GPa and 1300–1600 K. Their crystal structures were investigated using synchrotron X-ray powder diffraction data: a=5.8098(3) Å, b=7.7720(4) Å, and c=5.3510(3) Å for BiRhO{sub 3}; a=5.75519(1) Å, b=7.77218(2) Å, and c=5.37572(1) Å for NdRhO{sub 3}, and a=5.66981(1) Å, b=7.51205(2) Å, and c=5.18520(1) Å for LuRhO{sub 3}. BiRhO{sub 3} crystallizes in the centrosymmetric space group Pnma (No. 62) similar to LuRhO{sub 3} and NdRhO{sub 3} despite the presence of the lone electron pair of Bi{sup 3+} and the non-magnetic ground state of Rh{sup 3+}. BiRhO{sub 3} and LuRhO{sub 3} are non-magnetic, and NdRhO{sub 3} shows paramagnetic behavior from Nd{sup 3+} ions. The specific heat of BiRhO{sub 3}, LuRhO{sub 3}, and NdRhO{sub 3} in different applied magnetic fields was also investigated. An energy gap of BiRhO{sub 3} was estimated to be about 1.3 eV from diffuse reflectance spectra and 0.95 eV from first-principle calculations with U=3.5 eV. - Graphical abstract: A fragment of the crystal structure of BiRhO{sub 3} in the Pnma (along b axis) model, 2×2×2 unit cell. The RhO{sub 6} octahedra are shown in gray. The Bi atoms are shown by big black circles. Highlights: ► BiRhO{sub 3}, LuRhO{sub 3}, and NdRhO{sub 3} were prepared using a high-pressure technique. ► Structure of three compounds was determined: centrosymmetric space group Pnma. ► BiRhO{sub 3} and LuRhO{sub 3} are non-magnetic, and NdRhO{sub 3} shows paramagnetic behavior. ► Specific heat of BiRhO{sub 3}, LuRhO{sub 3}, and NdRhO{sub 3} was investigated. ► BiRhO{sub 3} has an energy gap of about 1.3 eV.

  1. Synthesis, chemical bonding and physical properties of RERhB{sub 4} (RE=Y, Dy-Lu)

    SciTech Connect

    Veremchuk, I.; Mori, T.; Prots, Yu.; Schnelle, W.; Leithe-Jasper, A.; Kohout, M.; Grin, Yu.

    2008-08-15

    The compounds of rare-earth metals with rhodium and boron RERhB{sub 4} (RE=Y, Dy-Lu) crystallize with the orthorhombic structure type YCrB{sub 4} (space group Pbam, Pearson symbol oP24). The crystal structures of the compounds with RE=Y, Er, Tm and Yb were refined by using single-crystal diffraction data. Analysis of chemical bonding for YRhB{sub 4} and YbRhB{sub 4} was performed by electron localizability indicator and by calculation of quantum chemical charges (quantum theory of atoms in molecules). Boron and rhodium form the 3-D polyanion containing planar nets of three-bonded boron atoms interconnected by rhodium along [001]. The interaction of the RE species with the rhodium-boron polyanion is predominantly ionic. Magnetic susceptibility data of TmRhB{sub 4} and YbRhB{sub 4} showed that the RE species are in 4f{sup 12} (Tm) and 4f{sup 13} (Yb) electronic states, respectively. In the low-temperature region, the specific heat revealed a Schottky anomaly for TmRhB{sub 4} while an antiferromagnetic transition is observed at 3.5 K for YbRhB{sub 4}. X-ray absorption measurement at the Yb L{sub III} edge for YbRhB{sub 4} reveals the 4f{sup 13} state of ytterbium. - Graphical abstract: The compounds of rare-earth metals with rhodium and boron RERhB{sub 4} (RE=Y, Dy-Lu) crystallize with the orthorhombic structure type YCrB{sub 4}. Analysis of chemical bonding for YRhB{sub 4} and YbRhB{sub 4} was performed by electron localizability indicator and by calculation of quantum chemical charges (quantum theory of atoms in molecules). Boron and rhodium form the 3-D polyanion containing planar nets of three-bonded boron atoms interconnected by rhodium along [001]. The interaction of the RE species with the rhodium-boron polyanion is predominantly ionic.

  2. Electronic structure of U3+ in Cs3Lu2Cl9 and Cs3Y2I9 single crystals.

    PubMed

    Karbowiak, Mirosław; Mech, Agnieszka; Drozdzyński, Janusz; Ryba-Romanowski, Witold; Reid, Michael F

    2005-01-13

    Low-temperature emission and polarized absorption spectra have been recorded for U(3+) ions diluted in Cs(3)Lu(2)Cl(9) and Cs(3)Y(2)I(9) host crystals. The experimental crystal-field levels were fitted to 13 parameters of a semiempirical Hamiltonian representing the combined atomic, one-electron crystal field (CF) as well as two-particle correlation crystal-field (CCF) operators. The red shift of the first f-d transitions from approximately 14,800 cm(-1) in the spectrum of U(3+):Cs(3)Lu(2)Cl(9) to as low as 11,790 cm(-1) in that of U(3+):Cs(3)Y(2)I(9) has been attributed to an increase in the covalence of the U(3+)-X(-) bonds. Comparison of the differences in the Coulomb repulsion strength between U(3+) and Er(3+) ions in Cs(3)Lu(2)Cl(9) and Cs(3)Y(2)I(9) crystals suggests that the 5f electrons of U(3+) ions are more 3d-like than 4f. The CF splitting of the (2)H(9/2) and (4)F(5/2) multiplets is unexpectedly larger for U(3+):Cs(3)Y(2)I(9) than for U(3+):Cs(3)Lu(2)Cl(9), which may be viewed as a result of the proximity of f-d states. For a correct description of the energy level structure of the (2)H(9/)(2) and (4)F(5/2) multiplets, the inclusion of CCF terms in the parametric Hamiltonian has proved to be essential. The larger f-f transition intensities for U(3+):Cs(3)Y(2)I(9) were also considered to be a consequence of the red shift of the first f-d states. The inadequacy in determination of the minor atomic parameters (other than parameters for Coulomb and spin-orbit interactions) and the insufficient inclusion of the influence of excited configuration in the applied CF Hamiltonian are assumed to be the main deficiencies preventing a better agreement between the experimental and calculated energies of CF levels.

  3. Crystal fields, disorder, and antiferromagnetic short-range order in (Yb{sub 0.24}Sn{sub 0.76})Ru

    SciTech Connect

    Klimczuk, T; Wang, C H; Lawrence, J M; Xu, Q; Durakiewicz, T; Ronning, F; Llobet, A; Trouw, F; Kurita, N; Tokiwa, Y; Lee, Han-oh; Booth, C H; Gardner, J S; Bauer, E D; Joyce, J J; Zandbergen, H W; Movshovich, R; Cava, R J; Thompson, J D

    2011-07-18

    We report extensive measurements on a new compound (Yb{sub 0.24}Sn{sub 0.76})Ru that crystallizes in the cubic CsCl structure. Valence band photoemission and L{sub 3} x-ray absorption show no divalent component in the 4f configuration of Yb. Inelastic neutron scattering (INS) indicates that the eight-fold degenerate J-multiplet of Yb{sup 3+} is split by the crystalline electric field (CEF) into a Γ{sub 7} doublet ground state and a Γ{sub 8} quartet at an excitation energy 20 meV. The magnetic susceptibility can be fit very well by this CEF scheme under the assumption that a Γ{sub 6} excited state resides at 32 meV; however, the Γ{sub 8}/Γ{sub 6} transition expected at 12 meV was not observed in the INS. The resistivity follows a Bloch-Grüneisen law shunted by a parallel resistor, as is typical of systems subject to phonon scattering with no apparent magnetic scattering. All of these properties can be understood as representing simple local moment behavior of the trivalent Yb ion. At 1 K, there is a peak in specific heat that is too broad to represent a magnetic phase transition, consistent with absence of magnetic reflections in neutron diffraction. On the other hand, this peak also is too narrow to represent the Kondo effect in the Γ{sub 7} ground state doublet. On the basis of the field-dependence of the specific heat, we argue that antiferromagnetic shortrange order (possibly co-existing with Kondo physics) occurs at low temperatures. The long-range magnetic order is suppressed because the Yb site occupancy is below the percolation threshold for this disordered compound.

  4. Growth, structure, defects and polarized absorption spectral properties of Er:Yb:YCa4O(BO3)3 crystals

    NASA Astrophysics Data System (ADS)

    Zhong, Degao; Teng, Bing; Kong, Weijin; Zhang, Shiming; Li, Yuyi; Li, Jianhong; Yang, Liting; Cao, Lifeng; Van Smaalen, Sander

    2016-01-01

    YCa4O(BO3)3 (YCOB) crystals co-doped with 3 at% Er3+ and 20 at% Yb3+ were successfully grown by the Czochralski method. X-ray powder diffraction (XRPD) results show that the as-grown Er:Yb:YCOB crystal belongs to the monoclinic system with space group Cm. And the lattice parameters are a=8.076(8) Å, b=16.023(7) Å, c=3.528(4) Å and β=101.15(4)°. Crystal defects were revealed by chemical etching experiments. The density of etch pits, attributed to dislocations and observed on (010) planes, was found to be not uniform along the crystal diameter. The detailed polarized absorption spectra were measured. The polarized absorption cross sections at 977 nm are 1.01×10-20, 1.22×10-20 and 1.05×10-20 cm2 for E//X, E//Y and E//Z, respectively. And the polarized absorption cross sections at 1538 nm is about 1.86×10-20 cm2 for both E//X and E//Z, but for E//Y the result is 1.03×10-20 cm2, which is much smaller. The relationship between the crystal structure and absorption spectra was discussed.

  5. Self assembly of three-dimensional Lu2O3:Eu3+ inverse opal photonic crystals, their modified emissions and dual-functional refractive index sensing.

    PubMed

    Wang, Yunfeng; Zhu, Yongsheng; Xu, Wen; Song, Hongwei; Xu, Sai; Wang, Jing; Cui, Haining

    2013-10-14

    In this study, Lu2O3:Eu(3+) inverse-opal-photonic crystals (IOPCs) with controllable lattice constants were fabricated using a polymethylmethacrylate (PMMA) template. The modification effect of PC on the (5)D0-(7)F(J) and (5)D1-(7)F(J) (J = 1-6) transitions were systemically studied by emission spectra, luminescent dynamics and the temperature-dependence. It is significant to observe that the increase of (5)D0-(7)F(J) radiative lifetime for Eu(3+) ions (30%) in contrast to the reference sample was mainly due to modulation of the effective refractive index, rather than the density of optical states. The spontaneous decay rate in (5)D1 increased linearly with the decreasing lattice constants, which was due to the change in (5)D1-(5)D0 nonradiative relaxation of the IOPC samples. The temperature quenching of Eu(3+) ions in the IOPCs could be suppressed considerably more than the reference. On this basis, dual functional refractive index detection with infiltrated solutions was realized by monitoring the variation in the photonic stop band (PSB) and the lifetime of (5)D0-(7)F2 transition of the Lu2O3:Eu(3+) IOPCs. This work shows that the Lu2O3:Eu(3+) IOPCs present highly modified photoluminescence properties and are promising candidates for dual-functional refractive index sensing application. PMID:23933999

  6. LiY0.3Lu0.7F4: Ce3+,Pr3+ Mixed Crystal as a Perspective Up-Conversionally Pumped UV Active Medium

    NASA Astrophysics Data System (ADS)

    Gorieva, V. G.; Semashko, V. V.; Korableva, S. L.; Marisov, M. A.; Pavlov, V. V.

    2015-09-01

    Investigation results of effective population of states of 5d-configuration of Ce3+ ions by energy transfer from Pr3+ ions in LiY0.3Lu0.7F4 (LYLF) crystals are discussed. The real concentrations of Pr3+ and Ce3+ ions in LYLF crystals are determined. Such parameters as excited 4f-5d state photoionization cross-section of Pr3+ ions, ground state cross-section of Ce3+ ions at 266 nm wavelengths and energy transfer coefficients of energy transfer from Pr3+ to Ce3+ ions were estimated. The results of pump-probe experiments on 5d-4f transitions of Ce3+ ions in LYLF crystals are presented. The optimal parameters for getting maximal gain on 5d-4f transitions of Ce3+ ions were determined by mathematical modeling.

  7. Metal-to-metal charge transfer between dopant and host ions: Photoconductivity of Yb-doped CaF2 and SrF2 crystals.

    PubMed

    Barandiarán, Zoila; Seijo, Luis

    2015-10-14

    Dopant-to-host electron transfer is calculated using ab initio wavefunction-based embedded cluster methods for Yb/Ca pairs in CaF2 and Yb/Sr pairs in SrF2 crystals to investigate the mechanism of photoconductivity. The results show that, in these crystals, dopant-to-host electron transfer is a two-photon process mediated by the 4f(N-1)5d excited states of Y b(2+): these are reached by the first photon excitation; then, they absorb the second photon, which provokes the Y b(2+) + Ca(2+) (Sr(2+)) → Y b(3+) + Ca(+) (Sr(+)) electron phototransfer. This mechanism applies to all the observed Y b(2+) 4f-5d absorption bands with the exception of the first one: Electron transfer cannot occur at the first band wavelengths in CaF2:Y b(2+) because the Y b(3+)-Ca(+) states are not reached by the two-photon absorption. In contrast, Yb-to-host electron transfer is possible in SrF2:Y b(2+) at the wavelengths of the first 4f-5d absorption band, but the mechanism is different from that described above: first, the two-photon excitation process occurs within the Y b(2+) active center, then, non-radiative Yb-to-Sr electron transfer can occur. All of these features allow to interpret consistently available photoconductivity experiments in these materials, including the modulation of the photoconductivity by the absorption spectrum, the differences in photoconductivity thresholds observed in both hosts, and the peculiar photosensitivity observed in the SrF2 host, associated with the lowest 4f-5d band. PMID:26472390

  8. Metal-to-metal charge transfer between dopant and host ions: Photoconductivity of Yb-doped CaF{sub 2} and SrF{sub 2} crystals

    SciTech Connect

    Barandiarán, Zoila Seijo, Luis

    2015-10-14

    Dopant-to-host electron transfer is calculated using ab initio wavefunction-based embedded cluster methods for Yb/Ca pairs in CaF{sub 2} and Yb/Sr pairs in SrF{sub 2} crystals to investigate the mechanism of photoconductivity. The results show that, in these crystals, dopant-to-host electron transfer is a two-photon process mediated by the 4f{sup N−1}5d excited states of Y b{sup 2+}: these are reached by the first photon excitation; then, they absorb the second photon, which provokes the Y b{sup 2+} + Ca{sup 2+} (Sr{sup 2+}) → Y b{sup 3+} + Ca{sup +} (Sr{sup +}) electron phototransfer. This mechanism applies to all the observed Y b{sup 2+} 4f–5d absorption bands with the exception of the first one: Electron transfer cannot occur at the first band wavelengths in CaF{sub 2}:Y b{sup 2+} because the Y b{sup 3+}–Ca{sup +} states are not reached by the two-photon absorption. In contrast, Yb-to-host electron transfer is possible in SrF{sub 2}:Y b{sup 2+} at the wavelengths of the first 4f–5d absorption band, but the mechanism is different from that described above: first, the two-photon excitation process occurs within the Y b{sup 2+} active center, then, non-radiative Yb-to-Sr electron transfer can occur. All of these features allow to interpret consistently available photoconductivity experiments in these materials, including the modulation of the photoconductivity by the absorption spectrum, the differences in photoconductivity thresholds observed in both hosts, and the peculiar photosensitivity observed in the SrF{sub 2} host, associated with the lowest 4f–5d band.

  9. Geochemical test for branching decay of 176Lu

    NASA Astrophysics Data System (ADS)

    Amelin, Y.; Davis, W. J.

    2005-01-01

    Two different groups of values for the 176Lu decay constant have been determined by recent high-precision experiments. The λ 176Lu values of 1.86-1.87 × 10 -11 a -1 were determined by age comparisons using terrestrial minerals of Proterozoic and late Archean age, whereas values of ˜1.94 × 10 -11 a -1 were determined in age comparison studies of meteorites. A possible branched decay of 176Lu could be the cause of this discrepancy. The β + decay of 176Lu to 176Yb was detected in the early studies of radioactivity of 176Lu, with reported values of λβ +/(λβ + + λβ -) in the total 176Lu ranging from less than 0.03 to 0.67. If the β + decay fraction is close to the upper limit of the reported values, it can explain the 4%-6% difference between the apparent λ 176Lu values. To get a reliable estimate for the β + decay of 176Lu, we have measured Yb isotopic composition in 2.7 Ga zircons with Lu/Yb N (chondrite-normalized) ratios of 1.40 and 1.45, in 1.0 Ga xenotime with Lu/Yb N = 1.23, using Yb from the 28.4 Ma Fish Canyon Tuff (FCT) zircon and titanite as the modern reference value. Multiple analyses yielded the following weighted mean values (± 2σ) for the 176Yb/ 174Yb ratio: 0.4022134 ± 0.0000017 for the FCT zircon and titanite, 0.4022134 ± 0.0000019 for the 1.0 Ga xenotime, and 0.4022124 ± 0.0000033 for the 2.7 Ga zircons. These data yield λβ +/(λβ + + λβ -) = -0.005 ± 0.015 (2σ) and establish an upper limit of 0.9% of total decays for the β + decay branch. Branching decay can therefore be eliminated as the cause of the discrepancy in 176Lu decay constant estimates. We discuss other possible causes of the λ 176Lu terrestrial vs. meteorite discrepancy.

  10. Polarized spectroscopic properties of Er3+:Gd2SiO5 crystal and evaluation of Er3+:Yb3+:Gd2SiO5 crystal as a 1.55 μm laser medium

    NASA Astrophysics Data System (ADS)

    Wang, H.; Huang, J. H.; Gong, X. H.; Chen, Y. J.; Lin, Y. F.; Luo, Z. D.; Huang, Y. D.

    2016-10-01

    An Er3+-doped Gd2SiO5 single crystal with high optical quality has been grown by the Czochralski method. Polarized absorption and fluorescence spectra and fluorescence lifetime of the crystal were measured at room temperature. Intensity parameters, spontaneous emission probabilities, fluorescence branching ratios, and radiative lifetimes were estimated on the basis of the Judd-Ofelt theory. Besides, potentiality of 1.55 μm laser emission in an Er3+-Yb3+ co-doped Gd2SiO5 crystal was evaluated.

  11. Syntheses, crystal structures, and resistivities of the two new ternary uranium selenides, Er3USe8 and Yb3USe8

    NASA Astrophysics Data System (ADS)

    Prakash, Jai; Mesbah, Adel; Beard, Jessica C.; Malliakas, Christos D.; Ibers, James A.

    2016-01-01

    Two new ternary lanthanide (Ln) uranium selenides, Er3USe8 and Yb3USe8, were synthesized at 1198 K using NaI as a flux. Single-crystal X-ray studies show these two compounds to be isostructural and to crystallize in space group D2h 11 -Pbcm of the orthorhombic crystal system. The Ln and U atoms are disordered on the same crystallographic site in these crystal structures. Each Ln/U atom is coordinated to eight Se atoms in a bicapped trigonal prism, and sharing of these (Ln/U)Se8 units creates a three-dimensional network. Se2 atoms are connected to each other to form infinite one-dimensional chains along the c axis. In these chains, the two Se atoms are separated by about 2.74 Å, a distance intermediate to those of a Se-Se single bond and a van der Waals interaction. Temperature-dependent resistivity measurements show that Er3USe8 and Yb3USe8 are semiconductors with activation energies of 0.08(1) and 0.17(1) eV, respectively.

  12. Physical optimization of production by deuteron irradiation of high specific activity (177g)Lu suitable for radioimmunotherapy.

    PubMed

    Manenti, Simone; Bonardi, Mauro L; Gini, Luigi; Groppi, Flavia

    2014-01-01

    Deuteron-induced nuclear reactions for generation of no-carrier-added (NCA) Lu isotopes were investigated using the stacked-foil activation technique on natural Yb targets at energies up to Ed=18.18MeV. The decay curve of ¹⁷⁷Yb, the growth curve of the cumulative (direct and indirect) and the direct production of (177g)Lu were determined. The analysis of these curves conducts to the evidence that the predominant route for the production of (177g)Lu is the indirect reaction ¹⁷⁶Yb(d,p)¹⁷⁷Yb, which decays to (177g)Lu. In the spectra acquired one year from the EOB the γ lines of (177m)Lu are not evident. A comparison between the calculated activity of (177g)Lu produced with a cyclotron and with a nuclear reactor is given.

  13. Magnetic and electrical properties of flux grown single crystals of Ln{sub 6}M{sub 4}Al{sub 43} (Ln=Gd, Yb; M=Cr, Mo, W)

    SciTech Connect

    Kangas, Michael J.; Treadwell, LaRico J.; Haldolaarachchige, Neel; McAlpin, Jacob D.; Young, David P.; Chan, Julia Y.

    2013-01-15

    Millimeter-sized single crystals of Ln{sub 6}M{sub 4}Al{sub 43} (Ln=Gd, Yb; M=Cr, Mo, W) were successfully grown with a molten aluminum flux. Synthetic conditions and physical properties for single crystals of all six analogs are discussed. The compounds exhibit metallic resistivity with room temperature values between 0.1 and 0.6 m{Omega}-cm. The Yb analogs are Pauli paramagnets with the Yb ion adopting the nonmagnetic divalent configuration (Yb{sup 2+}). Gd{sub 6}Cr{sub 4}Al{sub 43}, Gd{sub 6}Mo{sub 4}Al{sub 43}, and Gd{sub 6}W{sub 4}Al{sub 43} appear to order antiferromagnetically at 19, 15, and 15 K, respectively. - Graphical abstract: The crystal structure of Yb{sub 6}Cr{sub 4}Al{sub 43}. The light and dark green polyhedra show the chromium sublattice. Highlights: Black-Right-Pointing-Pointer Single crystals up to 0.5 cm in length were grown with a molten aluminum flux. Black-Right-Pointing-Pointer Physical property measurements were conducted on single crystals. Black-Right-Pointing-Pointer Gadolinium analogs appear to order antiferromagnetically with positive {theta}. Black-Right-Pointing-Pointer All analogs show metallic resistivity.

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

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

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

  15. UV and VUV spectroscopic study of Na0.4Y0.6F2.2 crystals doped with rare-earth ions

    NASA Astrophysics Data System (ADS)

    Bezhanov, V. A.; Mikhaĭlin, V. V.; Chernov, S. P.; Karimov, D. N.; Sobolev, B. P.

    2006-10-01

    The short-wavelength transmission spectra of Na0.4 R 0.6F2.2 crystals with R = Y, Yb, or Lu have been investigated. For these crystals, the VUV transmission cutoffs are 78750, 58820, and 75200 cm-1, respectively. The 4 f n-4 f n-15 d absorption and excitation spectra of Na0.4Y0.6F2.2 crystals activated with Ce3+, Pr3+, Nd3+, Er3+, Tm3+, and Yb3+ ions have been analyzed in the range 30000-80000 cm-1. The energy positions of the lowest levels of the 4 f n-15 d configurations of these ions in the fluorite crystal matrix Na0.4Y0.6F2.2 are determined. The absorption band in the spectral range 60600-70000 cm-1 in Na0.4(Y, Yb)0.6F2.2 crystals is due to the charge transfer from F- to Yb3+. It is shown that the environmental symmetry of Ce3+ ions in Na0.4R0.6F2.2 ( R = Y, Yb, Lu) crystals is almost identical.

  16. Crystal structures of orthorhombic, hexagonal, and cubic compounds of the Sm{sub (x)}Yb{sub (2−x)}TiO{sub 5} series

    SciTech Connect

    Aughterson, Robert D.; Lumpkin, Gregory R.; Reyes, Massey de los; Sharma, Neeraj; Ling, Christopher D.; Gault, Baptiste; Smith, Katherine L.; Avdeev, Maxim; Cairney, Julie M.

    2014-05-01

    A series of single phase compounds with nominal stoichiometry Sm{sub (x)}Yb{sub (2−x)}TiO{sub 5} (x=2, 1.4, 1, 0.6, and 0) have been successfully fabricated to generate a range of crystal structures covering the most common polymorphs previously discovered in the Ln{sub 2}TiO{sub 5} series (Ln=lanthanides and yttrium). Four of the five samples have not been previously fabricated in bulk, single phase form so their crystal structures are refined and detailed using powder synchrotron and single crystal x-ray diffraction, neutron diffraction and transmission electron microscopy. Based on the phase information from diffraction data, there are four crystal structure types in this series; orthorhombic Pnma, hexagonal P6{sub 3}/mmc, cubic (pyrochlore-like) Fd-3m and cubic (fluorite-like) Fm-3m. The cubic materials show modulated structures with variation between long and short range ordering and the variety of diffraction techniques were used to describe these complex crystal structure types. - Graphical abstract: A high resolution image of the compound Sm{sub 0.6}Yb{sub 1.4}TiO{sub 5} showing contrast from lattice fringes and the corresponding fast Fourier transform (FFT) of the HREM image with pyrochlore related diffraction spots marked “P” and fluorite marked “F”. The crystal is oriented down the [1 1 0] zone axis based on the Fd-3m structure. The ideal crystal structure (no vacancies) of the cubic, pyrochlore-like (Sm{sub 0.6}Yb{sub 1.4}TiO{sub 5}). - Highlights: • First fabrication of bulk single-phase material with stoichiometry Sm{sub 2}TiO{sub 5}. • Systematic study of crystal structure types within Ln{sub 2}TiO{sub 5} series (Ln=lanthanides). • A novel technique using IFFT of HREM images to study cubic structures.

  17. SPECIAL ISSUE DEVOTED TO THE 90TH ANNIVERSARY OF A.M. PROKHOROV: CW lasing in Yb3+ : GGG crystals pumped at 0.925 μm

    NASA Astrophysics Data System (ADS)

    Belovolov, A. M.; Belovolov, M. I.; Dianov, Evgenii M.; Dudin, V. V.; Timoshechkin, M. I.

    2006-07-01

    Single-mode cw lasing was obtained for the first time in Yb3+ : GGG crystals at room temperature at 1.030 and 1.037 μm upon pumping Yb3+ ions by a 0.925-μm neodymium-doped fibre laser. Lasing was observed at the transitions between the lower Stark sublevel of the 2F5/2 level and the upper Stark sublevels of the 2F7/2 ground state of Yb3+ ions. The study of lasing characteristic showed that lasing occurs according to the four-level scheme. The lasing threshold with respect to the absorbed power was 85 mW and the slope lasing efficiency was 20%. Upon 1.7-W pumping, the output power of 310 mW was achieved with the output resonator mirror with the transmission coefficient of 1%. The effective cross section of the lasing transition was 0.9×10-20 cm2.

  18. White upconversion of rare-earth doped ZnO nanocrystals and its dependence on size of crystal particles and content of Yb3+ and Tm3+

    NASA Astrophysics Data System (ADS)

    Liu, Yunxin; Xu, Changfu; Yang, Qibin

    2009-04-01

    Rare earth (RE) doped ZnO nanocrystals were synthesized by chemical combustion method. Bright white upconversion (UC) luminescence with the CIE coordinates close to (0.33, 0.33) was obtained in Er+Tm+Yb tridoped ZnO nanocrystals under the excitation of a cost-effective 980 nm single-wavelength laser diode. The overall and relative UC luminescence intensities of RE doped ZnO nanocrystals were found to be depended highly on the diameter of crystal particles and the concentration of Yb3+ and Tm3+, for which the involved mechanisms were demonstrated. The investigation based on UC spectra, simplified energy level diagram, and excitation power dependence indicated that the remarkable enhancement of the green emission of the RE tridoped sample was due to a dual sensitization of Er3+ by Yb3+ and Tm3+ ions. The RE tridoped ZnO nanocrystals with the CIE coordinates close to (0.33, 0.33) are potentially suitable for the widely realistic application as the multicolor fluorescent labels, due to a fact that they could be cheaply and easily obtained and excited cost effectively.

  19. Phosphate Yb3+ photonic crystal fiber single-mode laser with enormous high pump absorption

    NASA Astrophysics Data System (ADS)

    Franczyk, M.; Stepien, R.; Pysz, D.; Kujawa, I.; Buczynski, R.

    2014-08-01

    We demonstrate a single-mode 6 cm long, phosphate fiber laser with maximum power of 9.0 W. Laser action output power per fiber length of 150 W m-1 was achieved and this is the highest value ever reported in a single-mode fiber laser using a phosphate glass fiber. The slope efficiency of the laser was 36.2% and lasing wavelength was 1028 nm. We used a 6% mol ytterbium-doped, air-clad photonic crystal fiber with the core of 30 µm in diameter. Estimated pump absorption in the fiber exceeded 400 dB m-1.

  20. Synthesis, crystal structure, and magnetism of A2Co12As7 (A=Ca, Y, Ce–Yb)

    SciTech Connect

    Tan, Xiaoyan; Ovidiu Garlea, V.; Chai, Ping; Geondzhian, Andrey Y.; Yaroslavtsev, Alexander A.; Xin, Yan; Menushenkov, Alexey P.; Chernikov, Roman V.; Shatruk, Michael

    2015-08-28

    In this study, ternary intermetallics, A2Co12As7 (A=Ca, Y, Ce–Yb), have been synthesized by annealing mixtures of elements in molten Bi at 1223 K. The materials obtained crystallize in the P63/m variant of the Zr2Fe12P7 structure type. The unit cell volume shows a monotonic decrease with the increasing atomic number of the rare-earth metal, with the exception of Ce-, Eu-, and Yb-containing compounds. An examination of these outliers with X-ray absorption near edge structures (XANES) spectroscopy revealed mixed valence of Ce, Eu, and Yb, with the average oxidation states of +3.20(1), +2.47(5), and +2.91(1), respectively, at room temperature. Magnetic behavior of A2Co12As7 is generally characterized by ferromagnetic ordering of Co 3d moments at 100–140 K, followed by low-temperature ordering of rare-earth 4f moments. The 3d-4f magnetic coupling changes from antiferromagnetic for A=Pr–Sm to ferromagnetic for A=Ce and Eu–Yb. Finally, polarized neutron scattering experiments were performed to support the postulated ferro- and ferrimagnetic ground states for Ce2Co12As7 and Nd2Co12As7, respectively.

  1. Crystallization kinetics and spectroscopic investigations on Tb{sup 3+} and Yb{sup 3+} codoped glass ceramics containing CaF{sub 2} nanocrystals

    SciTech Connect

    Huang Lihui; Qin Guanshi; Arai, Yusuke; Jose, Rajan; Suzuki, Takenobu; Ohishi, Yasutake; Yamashita, Tatsuya; Akimoto, Yusuke

    2007-11-01

    Transparent Tb{sup 3+} and Yb{sup 3+} codoped oxyfluoride glass ceramics containing CaF{sub 2} nanocrystals were prepared by melt quenching and subsequent heat treatment. Crystallization kinetics of CaF{sub 2} nanocrystals was investigated by differential scanning calorimetric method. The average apparent activation energy E{sub a} of the crystallization was {approx}498 kJ/mol. Moreover, the value of the Avrami exponent n was 1.01. These results suggest that the crystallization mechanism of CaF{sub 2} is a diffusion controlled growth process of needles and plates of finite long dimensions. X-ray diffraction patterns and transmission electron microscopy image confirmed the CaF{sub 2} nanocrystals in the glass ceramic. Ultraviolet (UV) and visible emission spectra of the as-made glass and the glass ceramic with an excitation of a 974 nm laser diode were recorded at room temperature. An intense UV emission at 381 nm was observed in the glass ceramic. The origin of the enhancement of the emission at 381 nm was investigated using spectroscopic technique and Judd-Ofelt analysis. The enhancement of the emission at 381 nm could be attributed to the change of the ligand field of Tb{sup 3+} ions due to the incorporation of some Tb{sup 3+} and Yb{sup 3+} ions into CaF{sub 2} nanocrystals in the glass ceramic.

  2. Growth and spectral properties of a promising laser crystal Yb3+/Er3+:Ca9La(VO4)7

    NASA Astrophysics Data System (ADS)

    Li, Ming; Sun, Shijia; Zhang, Lizhen; Yuan, Feifei; Huang, Yisheng; Lin, Zhoubin

    2016-10-01

    A new crystal of Er3+/Yb3+:Ca9La(VO4)7 was grown successfully by the Czochralski method. Its spectral properties were investigated in detail. The crystal has a strong absorption band near 980 nm with a full-width at half-maximum of 33 nm, which means that it is very suitable for InGaAs laser diode pumping. Based on the Judd-Ofelt theory, the intensity parameters and radiative lifetime were obtained. The fluorescence lifetime of the 4I13/2 level of the Er3+ ion is 4.28 ms. The emission cross sections of the Er3+ ion at 1533 nm calculated by the Füchtbauer-Ladenburg method are 0.86 × 10-20 cm2 and 1.08 × 10-20 cm2 for σ- and π- polarization, respectively. The results indicate that Er3+/Yb3+:Ca9La(VO4)7 crystal is a potential 1.5-1.6 μm laser material.

  3. Highly Efficient LiYF4:Yb(3+), Er(3+) Upconversion Single Crystal under Solar Cell Spectrum Excitation and Photovoltaic Application.

    PubMed

    Chen, Xu; Xu, Wen; Song, Hongwei; Chen, Cong; Xia, Haiping; Zhu, Yongsheng; Zhou, Donglei; Cui, Shaobo; Dai, Qilin; Zhang, Jiazhong

    2016-04-13

    Luminescent upconversion is a promising way to harvest near-infrared (NIR) sunlight and transforms it into visible light that can be directly absorbed by active materials of solar cells and improve their power conversion efficiency (PCE). However, it is still a great challenge to effectively improve the PCE of solar cells with the assistance of upconversion. In this work, we demonstrate the application of the transparent LiYF4:Yb(3+), Er(3+) single crystal as an independent luminescent upconverter to improve the PCE of perovskite solar cells. The LiYF4:Yb(3+), Er(3+) single crystal is prepared by an improved Bridgman method, and its internal quantum efficiency approached to 5.72% under 6.2 W cm(-2) 980 nm excitation. The power-dependent upconversion luminescence indicated that under the excitation of simulated sunlight the (4)F(9/2)-(4)I(15/2) red emission originally results from the cooperation of a 1540 nm photon and a 980 nm photon. Furthermore, when the single crystal is placed in front of the perovskite solar cells, the PCE is enhanced by 7.9% under the irradiation of simulated sunlight by 7-8 solar constants. This work implies the upconverter not only can serve as proof of principle for improving PCE of solar cells but also is helpful to practical application.

  4. Trace element systematics and 147Sm- 143Nd and 176Lu- 176Hf ages of Larkman Nunatak 06319: Closed-system fractional crystallization of an enriched shergottite magma

    NASA Astrophysics Data System (ADS)

    Shafer, J. T.; Brandon, A. D.; Lapen, T. J.; Righter, M.; Peslier, A. H.; Beard, B. L.

    2010-12-01

    Combined 147Sm- 143Nd and 176Lu- 176Hf chronology of the martian meteorite Larkman Nunatak (LAR) 06319 indicates an igneous crystallization age of 193 ± 20 Ma (2 σ weighted mean). The individual 147Sm- 143Nd and 176Lu- 176Hf internal isochron ages are 183 ± 12 Ma and 197 ± 29 Ma, respectively, and are concordant with two previously determined 147Sm- 143Nd and 87Rb- 87Sr internal isochron ages of 190 ± 26 Ma and 207 ± 14 Ma, respectively ( Shih et al., 2009). With respect to the 147Sm- 143Nd isotope systematics, maskelynite lies above the isochron defined by primary igneous phases and is therefore not in isotopic equilibrium with the other phases in the rock. Non-isochronous maskelynite is interpreted to result from shock-induced reaction between plagioclase and partial melts of pyroxene and phosphate during transformation to maskelynite, which resulted in it having unsupported 143Nd relative to its measured 147Sm/ 144Nd ratio. The rare earth element (REE) and high field strength element (HFSE) compositions of major constituent minerals can be modeled as the result of progressive crystallization of a single magma with no addition of secondary components. The concordant ages, combined with igneous textures, mineralogy, and trace element systematics indicate that the weighted average of the radiometric ages records the true crystallization age of this rock. The young igneous age for LAR 06319 and other shergottites are in conflict with models that advocate for circa 4.1 Ga crystallization ages of shergottites from Pb isotope compositions, however, they are consistent with updated crater counting statistics indicating that young volcanic activity on Mars is more widespread than previously realized ( Neukum et al., 2010).

  5. Lasing in a Tm:Ho:Yb3Al5O12 crystal pumped into the 3H6 - 3F4 transition

    NASA Astrophysics Data System (ADS)

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

    2016-03-01

    A growth technology has been developed, and a Tm:Ho:Yb3Al5O12 laser crystal of high optical quality has been grown by Czochralski method. Its spectral and luminescent characteristics are studied. Lasing at a wavelength of 2100 nm is obtained under pumping into the absorption line on the 3H6 - 3F4 transition of the Tm3+ ion at a wavelength of 1678 nm. The slope and total (optical) efficiencies of the laser at an output power of up to 320 mW reach 41% and 30%, respectively.

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

    SciTech Connect

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

    2008-12-15

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

  7. Yb:S-FAP Lasers

    SciTech Connect

    Schaffers, K I

    2004-01-20

    It has recently been reported that several high power, diode-pumped laser systems have been developed based on crystals of Yb:S-FAP [Yb{sup 3+}:Sr{sub 5}(PO{sub 4}){sub 3}F]. The Mercury Laser, at Lawrence Livermore National Laboratory, is the most prominent system using Yb:S-FAP and is currently producing 23J at 5 Hz in a 15 nsec pulse, based on partial activation of the system. In addition, a regenerative amplifier is being developed at Waseda University in Japan and has produced greater than 12 mJ with high beam quality at 50Hz repetition rate. Q-peak has demonstrated 16 mJ of maximum energy/output pulse in a multi-pass, 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.

  8. Up-conversion emission in triply-doped Ho3+/Yb3+/Tm3+ KGd(WO4)2 single crystals

    NASA Astrophysics Data System (ADS)

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

    2011-06-01

    Detailed spectroscopic studies of the triply doped KGd(WO4)2:Ho3+/Yb3+/Tm3+ single crystals (which exhibit multicolor up-conversion fluorescence) are reported for the first time. The absorption spectra of crystals were measured at 10 and 300 K; the room temperature luminescence spectra were excited at 980 nm wavelength. The dependence of the intensity of luminescence on the excitation power for three different concentration of Ho3+, Yb3+ and Tm3+ ions was investigated. Efficient green and red up-converted luminescence of Ho3+ ions and weak blue up-conversion luminescence of Tm3+ ions were observed in spectra. The red emission of Ho3+ ions is more intensive than their green emission. Dependence of the up-conversion luminescence intensity on the excitation power and impurities concentration was also studied; the number of phonon needed for efficient up-conversion was determined for each case. All possible energy transfer processes between different pairs of the impurity ions' energy levels are also discussed.

  9. The crystal structure and luminescence of Ce3+, Tb3+ and Eu3+ in KBaLn3+(BO3)2 [Ln3+ = Sc, Y, Lu, Gd

    NASA Astrophysics Data System (ADS)

    Camardello, S. J.; Her, J. H.; Toscano, P. J.; Srivastava, A. M.

    2015-11-01

    The structure of KBaLn3+(BO3)2 [Ln3+ = Sc, Lu, Gd] was solved by Rietveld refinement of the powder X-ray diffraction data. The materials crystallize with the mineral Buetschliite [K2Ca(CO3)2] structure. The lattice parameters of KBaLn3+(BO3)2 [Ln3+ = Sc, Lu, Gd] increased with increasing ionic radius of the Ln3+ cation. In this structure, the Ln3+ cations are octahedrally coordinated. The phase formation region is dependent on the ionic radii of the Ln3+ cation. The optical properties of Ce3+, Tb3+ and Eu3+ and their dependence on the host lattice composition are investigated and discussed. It is noteworthy that the optical properties of these ions are independent of the Ln3+ cation in KBaLn3+(BO3)2. It is concluded that in this family of materials, the crystalline field strength and the covalence at the rare earth site is independent of the host lattice composition.

  10. Optical and magneto-optical properties of single crystals of RFe{sub 2} (R = Gd, Tb, Ho, and Lu) and GdCo{sub 2} intermetallic compounds

    SciTech Connect

    Lee, S.J.

    1999-02-12

    The author has studied the diagonal and off-diagonal optical conductivity of RFe{sub 2}(R = Gd, Tb, Ho, Lu) and GdCo{sub 2} single crystals grown by the flux method. Using spectroscopic ellipsometry the author has measured the dielectric function from 1.5 to 5.5 eV. The magneto-optical Kerr spectrometer at temperatures between 7 and 295 K and applied magnetic fields between 0.5 to 1.6 T. The apparatus and calibration method are described in detail. Using magneto-optical data and optical constants he derives the experimental value of the off-diagonal conductivity components. Theoretical calculations of optical conductivities and magneto-optical parameters were performed using the tight binding-linear muffin tin orbitals method within the local spin density approximation. He applied this TB-LMTO method to LuFe{sub 2}. The theoretical results obtained agree well with the experimental data. The oxidation effects on the diagonal part of the optical conductivity were considered using a three-phase model. The oxidation effects on the magneto-optical parameters were also considered by treating the oxide layer as a nonmagnetic thin transparent layer. These corrections change not only the magnitude but also the shape of the optical conductivity and the magneto-optical parameters.

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

    SciTech Connect

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

    2009-07-15

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

  12. Spectroscopic properties and high-power laser operation of Yb0.14:Y0.77Gd0.09Ca4O(BO3)3 mixed crystal

    NASA Astrophysics Data System (ADS)

    Chen, Xiaowen; Xu, Honghao; Han, Wenjuan; Wang, Lisha; Liu, Junhai; Yu, Haohai; Zhang, Huaijin

    2016-05-01

    We report, for the first time to our knowledge, on the spectroscopic properties and continuous-wave laser performance of Yb0.14:Y0.77Gd0.09Ca4O(BO3)3, a mixed rare earth calcium oxyborate Yb-ion crystal. Under simple end-pumping conditions with a 976-nm diode, efficient CW laser operation was demonstrated at room temperature, producing an output power of 14.1 W at 1084.4 nm with an optical-to-optical efficiency of 48%; while operating around 1045 nm, the laser could generate an output power as high as 23.0 W, with optical-to-optical and slope efficiencies amounting, respectively, to 57% and 70% with respect to incident pump power. The polarized absorption and emission cross sections are also presented. The impressive results demonstrated reveal the great potential of these mixed oxyborates in developing new promising Yb-ion laser crystals.

  13. Fluorescence spectra of Na5Lu9F32 single crystals co-doped with Ho3+/Tm3+ grown by Bridgman method

    NASA Astrophysics Data System (ADS)

    Feng, Zhigang; Xia, Haiping; Wang, Cheng; Zhang, Zhixiong; Jiang, Dongsheng; Zhang, Jian; He, Shinan; Tang, Qingyang; sheng, Qiguo; Gu, Xuemei; Zhang, Yuepin; Chen, Baojiu; Jiang, Haochuan

    2016-05-01

    This work presents the luminescent properties of Ho3+/Tm3+ co-doped Na5Lu9F32 single crystals that were grown by an improved Bridgman method for the first time. The J-O intense parameters of Ho3+ ions were calculated. An intense 2.0 μm emission was achieved with Tm3+ ions sensitizing Ho3+ ions by the processing of energy transfer from Tm3+ ions to Ho3+ ions under excitation of 800 nm LD. The maximum emission intensity at 2.0 μm is obtained, and the cross sections of Tm3+ ions and Ho3+ ions were calculated. The physical mechanism for energy transfer from Tm3+ to Ho3+ ions was analyzed by using Inokuti-Hirayama's model.

  14. Excitation function for deuteron induced nuclear reactions on natural ytterbium for production of high specific activity 177g Lu in no-carrier-added form for metabolic radiotherapy.

    PubMed

    Manenti, Simone; Groppi, Flavia; Gandini, Andrea; Gini, Luigi; Abbas, Kamel; Holzwarth, Uwe; Simonelli, Federica; Bonardi, Mauro

    2011-01-01

    Deuteron-induced nuclear reactions for generation of no-carrier-added Lu radionuclides were investigated using the stacked-foil activation technique on natural Yb targets at energies up to E(d)=18.18 MeV. Excitation functions of the reactions (nat)Yb(d,xn)(169,170,171,172,173,174g,174m,176m,177g)Lu and (nat)Yb(d,pxn)(169,175,177)Yb have been measured, among them three ((169)Lu, (174m)Lu and (176m)Lu) are reported for the first time. The upper limit of the contamination from the long-lived metastable level (177m)Lu was evaluated too. Thick-target yields for all investigated radionuclides are calculated.

  15. Hydrogen in polar intermetallics: Syntheses and structures of the ternary Ca5Bi3D0.93, Yb5Bi3Hx, and Sm5Bi3H~1 by powder neutron or single crystal X-ray diffraction

    SciTech Connect

    Leon-Escamilla, E. Alejandro; Dervenagas, Panagiotis; Stasis, Constantine; Corbett, John D.

    2010-01-01

    The syntheses of the title compounds are described in detail. Structural characterizations from refinements of single crystal X-ray diffraction data for Yb{sub 5}Bi{sub 3}H{sub x} and Sm{sub 5}Bi{sub 3}H{sub 1} and of powder neutron diffraction data for Ca{sub 5}Bi{sub 3}D{sub 0.93(3)} are reported. These confirm that all three crystallize with the heavy atom structure type of {beta}-Yb{sub 5}Sb{sub 3}, and the third gives the first proof that the deuterium lies in the center of nominal calcium tetrahedra, isostructural with the Ca{sub 5}Sb{sub 3}F-type structure. These Ca and Yb phases are particularly stable with respect to dissociation to Mn{sub 5}Si{sub 3}-type product plus H{sub 2}. Some contradictions in the literature regarding Yb{sub 5}Sb{sub 3} and Yb{sub 5}Sb{sub 3}H{sub x} phases are considered in terms of adventitious hydrogen impurities that are generated during reactions in fused silica containers at elevated temperatures.

  16. Room-temperature diode-pumped continuous-wave SrY4(SiO4)3O: Yb3 + , Er3 + crystal laser at 1554 nm

    NASA Astrophysics Data System (ADS)

    Souriau, J. C.; Romero, R.; Borel, C.; Wyon, C.; Li, C.; Moncorgé, R.

    1994-03-01

    Continuous-wave (cw) laser operation at room temperature of an Yb3+, Er3+ doped oxyapatite single crystal SrY4(SiO4)3O pumped at 980 nm by an InGaAs diode laser has been achieved around the eye-safe laser wavelength of 1554 nm.

  17. Modelling of thermal effects and gain competition in Yb-doped large mode area photonic crystal fibers

    NASA Astrophysics Data System (ADS)

    Coscelli, Enrico; Poli, Federica; Rosa, Lorenzo; Cucinotta, Annamaria; Selleri, Stefano

    2016-04-01

    In the last few years Yb-doped double cladding fibers have become the key component for the development of reliable and high-performance lasers. Despite an effective cooling of the fiber medium, a significant heat load is generated when high pump power is involved, which alters the mode propagation characteristics, causing unwanted coupling among the modes and destroying the output beam quality. This work presents a new tool for the analysis of the amplification and modal properties of Yb-doped double-cladding fibers, which comprises a full-vector modal solver, based on the finite-element method, an amplifier model and a thermal one. Simulation results, shown for two large pitch fiber designs, both in co-propagating and counter-propagating pumping schemes, have demonstrated the influence of the generated heat load on the overlap integral and on the power evolution of the guided modes.

  18. Enhanced upconversion emission in crystallization-controllable glass-ceramic fiber containing Yb(3+)-Er(3+) codoped CaF2 nanocrystals.

    PubMed

    Peng, Wencai; Fang, Zaijin; Ma, Zhijun; Qiu, Jianrong

    2016-10-01

    Functional nanocrystal-containing materials have been a hot topic in recent years. However, few researches have focused on functional nanocrystals contained in optical glass fibers. In this research, transparent CaF2 glass-ceramic was prepared by a melt-quenching method. Greatly enhanced upconversion luminescence was observed after heat treatment. By applying a novel method called melt-in-tube, precursor fiber free of crystals was fabricated at the drawing temperature where the clad was softened while the core was melted. Glass-ceramic fiber with fiber core containing Yb(3+)-Er(3+) codoped CaF2 nanocrystals was obtained after heat treatment at a relatively low temperature. Electron probe micro-analyzer measurement shows no obvious element diffusion between the core and clad. Greatly enhanced upconversion emission was detected in the glass-ceramic fiber excited by a 980 nm laser, suggesting the developed glass-ceramic fiber is a promising material for upconversion laser. PMID:27576586

  19. High-power passively Q-switched Yb:YCa4O(BO3)3 laser with a GaAs crystal plate as saturable absorber.

    PubMed

    Chen, Xiaowen; Han, Wenjuan; Xu, Honghao; Jia, Minghui; Yu, Haohai; Zhang, Huaijin; Liu, Junhai

    2015-04-10

    We report on efficient high-power passively Q-switched operation of a Yb:YCa4O(BO3)3 laser with a GaAs crystal plate acting as the saturable absorber. An average output power of 5.7 W at 1032 nm is generated at a pulse repetition rate of 166.7 kHz when the incident pump power is 26.8 W, with a slope efficiency determined to be 24.5%. The averaged pulse energy achieved is roughly 30 μJ and is increased to about 40 μJ when the output coupling used changes from 30% to 50%, while the shortest pulse width is measured to be 153 ns.

  20. Acousto-optic Q-switching laser performance of Yb:GdCa(4)O(BO(3))(3)crystal.

    PubMed

    Chen, Xiaowen; Xu, Honghao; Guo, Yunfeng; Han, Wenjuan; Yu, Haohai; Zhang, Huaijin; Liu, Junhai

    2015-08-20

    We report on the active Q-switching laser performance of Yb:GdCa4O(BO3)3 crystal, demonstrated by employing an acousto-optic Q-switch in a compact plano-concave resonator. Stable repetitively Q-switched operation is achieved with pulse repetition rates varying from 30 to 0.2 kHz, producing an average output power of 10.2 W at 1027.5 nm at 30 kHz of repetition rate, with an optical-to-optical efficiency of 30%. The maximum pulse energy generated at the lowest repetition rate of 0.2 kHz is 4.75 mJ, with a pulse width being 11 ns, gives rise to a peak power that amounts to 432 kW. PMID:26368745

  1. Enhanced upconversion emission in crystallization-controllable glass-ceramic fiber containing Yb3+-Er3+ codoped CaF2 nanocrystals

    NASA Astrophysics Data System (ADS)

    Peng, Wencai; Fang, Zaijin; Ma, Zhijun; Qiu, Jianrong

    2016-10-01

    Functional nanocrystal-containing materials have been a hot topic in recent years. However, few researches have focused on functional nanocrystals contained in optical glass fibers. In this research, transparent CaF2 glass-ceramic was prepared by a melt-quenching method. Greatly enhanced upconversion luminescence was observed after heat treatment. By applying a novel method called melt-in-tube, precursor fiber free of crystals was fabricated at the drawing temperature where the clad was softened while the core was melted. Glass-ceramic fiber with fiber core containing Yb3+-Er3+ codoped CaF2 nanocrystals was obtained after heat treatment at a relatively low temperature. Electron probe micro-analyzer measurement shows no obvious element diffusion between the core and clad. Greatly enhanced upconversion emission was detected in the glass-ceramic fiber excited by a 980 nm laser, suggesting the developed glass-ceramic fiber is a promising material for upconversion laser.

  2. Enhanced upconversion emission in crystallization-controllable glass-ceramic fiber containing Yb(3+)-Er(3+) codoped CaF2 nanocrystals.

    PubMed

    Peng, Wencai; Fang, Zaijin; Ma, Zhijun; Qiu, Jianrong

    2016-10-01

    Functional nanocrystal-containing materials have been a hot topic in recent years. However, few researches have focused on functional nanocrystals contained in optical glass fibers. In this research, transparent CaF2 glass-ceramic was prepared by a melt-quenching method. Greatly enhanced upconversion luminescence was observed after heat treatment. By applying a novel method called melt-in-tube, precursor fiber free of crystals was fabricated at the drawing temperature where the clad was softened while the core was melted. Glass-ceramic fiber with fiber core containing Yb(3+)-Er(3+) codoped CaF2 nanocrystals was obtained after heat treatment at a relatively low temperature. Electron probe micro-analyzer measurement shows no obvious element diffusion between the core and clad. Greatly enhanced upconversion emission was detected in the glass-ceramic fiber excited by a 980 nm laser, suggesting the developed glass-ceramic fiber is a promising material for upconversion laser.

  3. Design of very large-mode-area Yb-doped photonic crystal fiber for high-energy pulsed laser output with squared shape

    NASA Astrophysics Data System (ADS)

    Meng, Kuo; Zhu, Lianqing; Yan, Guang; Luo, Fei

    2015-05-01

    The rare earth-doped active fibers owning ten thousands of square-micron core-area but also delivering laser with high beam quality have little been reported. In this paper, we have designed a large-mode-area Yb3+-doped photonic crystal fiber in the cladding region with square-array air holes. Simulations demonstrate that only fundamental mode (FM) with mode-field-area (MFA) of ~15500 μm2 can be amplified and propagated at the gain saturation, and the beam quality M2 is less than 1.5. It is predicted that almost 58 mJ per-pulse can be available from such a 1.0 meter-length fiber, and the beam shape of amplified laser is near squared. It will be potential for so huge pulse-energy output from the VLMA LPF to be applied in the remote detecting, high-intensive welding and so on.

  4. Single crystal growth and heat capacity measurements of triangular lattice R2Pt6Ga15 (R =rare earth)

    NASA Astrophysics Data System (ADS)

    Matsumoto, Y.; Ueda, T.; Ohara, S.

    2016-02-01

    We have succeeded in synthesizing the single crystal of R2Pt6Ga15 (R=La-Nd, Sm- Lu) with hexagonal Sc0.67Fe2Si5-type structure using Ga self flux method. The crystal structure was confirmed by the powder X-ray method. The unit-cell volume V of R2Pt6Ga15 follows the lanthanide concentration except R = Ce, Eu and Yb, indicating that the valences of R = La, Pr, Nd, Sm, Gd-Tm, and Lu ion are trivalent, whereas those of R = Ce, Eu and Yb ion are deviate from trivalent. We have measured the specific heat C(T) of R2Pt6Ga15. It is found that the magnetic order takes place in R2Pt6Ga15 (R=Pr, Nd, Sm-Tm). Moreover, the multiple phase transitions were observed in R2Pt6Ga15 (R = Nd, Eu, Gd and Ho).

  5. Efficient laser operation at 1.06 μm in co-doped Lu3+, Nd3+:GdCa4O(BO3)3 single crystal

    NASA Astrophysics Data System (ADS)

    Brandus, C. A.; Gheorghe, L.; Dascalu, T.

    2015-04-01

    Efficient laser emission at 1.06 μm was obtained from a diode-laser quasi-continuous wave pumped Nd0.04Gd0.86Lu0.10Ca4O(BO3)3 (Nd:GdLuCOB) single crystal. An uncoated, 6.0-mm long, ZX-cut Nd:GdLuCOB medium yielded laser pulses with 1.76 W peak power for absorbed pump pulses of 5.49 W peak power, corresponding to an overall optical-to-optical efficiency ηoa = 0.32; the slope efficiency was ηsa = 0.44. Comparison is made with an uncoated XY-cut Nd:GdCOB medium (4.0-at.% Nd doping and 6.8-mm length) from which laser pulses with 1.74 W peak power (at optical efficiency ηoa = 0.25) and 0.31 slope efficiency were obtained. The improvements in laser emission of Nd:GdLuCOB at the fundamental wavelength are important for future self-frequency doubling in ZX principal plane of this crystal.

  6. High-power and high-efficiency diode-pumped Nd:LuYAG mixed crystal lasers operating at 939 and 946  nm.

    PubMed

    Cui, Qin; Lan, Jinglong; Lin, Zhi; Xu, Bin; Xu, Huiying; Cai, Zhiping; Xu, Xiaodong; Zhang, Jian; Xu, Jun

    2016-09-10

    We report on high-performance infrared lasers at 0.94 μm based on quasi-three-level transition of F3/24→I9/24 in Nd:LuYAG mixed crystal, for the first time to our knowledge. The maximum output power was achieved to 5.64 W with slope efficiency of approximately 52.5% at 946 nm. The simultaneous dual-wavelength laser at 939 and 946 nm is also obtained with maximum output power of 3.61 W and slope efficiency of 34.8% by introducing a glass etalon into the cavity. Moreover, a 2.0-W single-wavelength laser at 939 nm can be further attained by suitably tilting the etalon. Using a Cr:YAG saturable absorber, Q-switched laser operation is realized with maximum average output power of 0.68 W and the narrowest pulse width of 8.4 ns, which results in the maximum single pulse energy of approximately 55.3 μJ and the maximum pulse peak power of approximately 6.15 kW. Finally, thermal focal length of the laser crystal is estimated by using a flat-flat laser cavity. PMID:27661387

  7. Effects of disorder and isotopic substitution in the specific heat and Raman scattering in LuB{sub 12}

    SciTech Connect

    Sluchanko, N. E. Azarevich, A. N.; Bogach, A. V.; Vlasov, I. I.; Glushkov, V. V.; Demishev, S. V.; Maksimov, A. A.; Tartakovskii, I. I.; Filatov, E. V.; Flachbart, K.; Gabani, S.; Filippov, V. B.; Shitsevalova, N. Yu.; Moshchalkov, V. V.

    2011-09-15

    Precision measurements of the specific heat and spectral intensity I({omega}) of Raman scattering for Lu{sup N}B{sub 12} single crystal samples with various boron isotopes (N = 10, 11, nat) have been performed at low and intermediate temperatures. A boson peak in the low-frequency part of the I({omega}) spectrum has been observed for the first time for lutetium dodecaboride at liquid nitrogen temperatures. It has been shown that low-temperature anomalies in the specific heat, along with the features of Raman spectra, can be interpreted in terms of the transition to a cageglass state at T* = 50-70 K, which appears when Lu{sup 3+} ions are displaced from the centrosymmetric position in cavities of a rigid covalent boron sublattice towards the randomly located boron vacancies. The concentrations of various two-level systems that correspond to two types of vibrational clusters with correlation lengths of 12-15 and 18-22 A, respectively, have been estimated. The vibrational density of states of LuB{sub 12} has been calculated from Raman spectra in the model of soft atomic potentials. An approach has been proposed to explain the dielectrization of the properties of the YbB{sub 12} compound at T < T*, as well as the features of the formation of magnetic structures in RB{sub 12} antiferromagnets (R = Tb, Dy, Ho, Er, Tm) and the suppression of superconductivity in LuB{sub 12}.

  8. The radial distribution of dopant (Cr, Nd, Yb, or Ce) in yttrium aluminum garnet (Y 3Al 5O 12) single crystals grown by the micro-pulling-down method

    NASA Astrophysics Data System (ADS)

    Simura, Rayko; Yoshikawa, Akira; Uda, Satoshi

    2009-12-01

    Dopant distribution in yttrium aluminum garnet (YAG:Y 3Al 5O 12) shaped crystal grown via the micro-pulling-down method depends primarily on the distribution coefficient (k0). The solid-favoring dopants (k0>1.0), Cr and Yb, concentrated in the central core of the crystal, while the liquid-favoring dopants (k0<1.0), Nd and Ce, concentrated in the rim. Secondary rare-earth oxide phases were sometimes segregated and crystallized circumferentially with Nd and Ce dopant. The dopant distribution profile was also controlled by the position of the melt entrance hole in the crucible shaper, which was confirmed by SIMPLER calculation. Segregation/distribution coefficients for Cr, Yb, Nd, and Ce in YAG were found to be 1.5, 1.01, 0.1, and 0.01, respectively.

  9. New rare earth metal-rich indides RE14Ni 3In 3 ( RE=Sc, Y, Gd-Tm, Lu)—synthesis and crystal chemistry

    NASA Astrophysics Data System (ADS)

    Lukachuk, Mar'yana; Galadzhun, Yaroslav V.; Zaremba, Roman I.; Dzevenko, Mariya V.; Kalychak, Yaroslav M.; Zaremba, Vasyl I.; Rodewald, Ute Ch.; Pöttgen, Rainer

    2005-09-01

    The rare earth-nickel-indides RE14Ni 3In 3 ( RE=Sc, Y, Gd-Tm, Lu) were synthesized from the elements by arc-melting and subsequent annealing. The compounds were investigated on the basis of X-ray powder and single crystal data: Lu 14Co 2In 3 type, P4 2/ nmc, Z=4, a=888.1(1), c=2134.7(4), wR2=0.0653, 1381 F2 values, 63 variables for Sc 13.89Ni 3.66In 2.45; a=961.2(1), c=2316.2(5), wR2=0.0633, 1741 F2 values, 64 variables for Y 13.84Ni 3.19In 2.97; a=965.3(1), c=2330.5(5), wR2=0.0620, 1765 F2 values, 63 variables for Gd 14Ni 3.29In 2.71; a=956.8(1), c=2298.4(5), wR2=0.0829, 1707 F2 values, 64 variables for Tb 13.82Ni 3.36In 2.82; a=951.7(1), c=2289.0(5), wR2=0.0838, 1794 F2 values, 64 variables for Dy 13.60Ni 3.34In 3.06; a=948.53(7), c=2270.6(1), wR2=0.1137, 1191 F2 values, 64 variables for Ho 13.35Ni 3.17In 3.48; a=943.5(1), c=2269.1(5), wR2=0.0552, 1646 F2 values, 64 variables for Er 13.53Ni 3.14In 3.33; a=938.42(7), c=2250.8(1), wR2=0.1051, 1611 F2 values, 64 variables for Tm 13.47Ni 3.28In 3.25; a=937.3(1), c=2249.6(5), wR2=0.0692, 1604 F2 values, 64 variables for Tm 13.80Ni 3.49In 2.71; and a=933.4(1), c=2263.0(5), wR2=0.0709, 1603 F2 values, 64 variables for Lu 13.94Ni 3.07In 2.99. The RE14Ni 3In 3 indides show significant Ni/In mixing on the 4 c In1 site. Except the gadolinium compound, the RE14Ni 3In 3 intermetallics also reveal RE/In mixing on the 4 c RE1 site, leading to the refined compositions. Due to the high rare earth metal content, the seven crystallographically independent RE sites have between 9 and 10 nearest RE neighbors. The RE14Ni 3In 3 structures can be described as a complex intergrowth of rare earth-based polyhedra. Both nickel sites have a distorted trigonal-prismatic rare earth coordination. An interesting feature is the In2-In2 dumb-bell at an In2-In2 distance of 304 pm (for Gd 14Ni 3.29In 2.71). The crystal chemical peculiarities of the RE14Ni 3In 3 indides are briefly discussed.

  10. Comparative study of crystallographic, spectroscopic, and laser properties of Tm3+ in NaT(WO4)2 (T=La, Gd, Y, and Lu) disordered single crystals

    NASA Astrophysics Data System (ADS)

    Cano-Torres, J. M.; Rico, M.; Han, X.; Serrano, M. D.; Cascales, C.; Zaldo, C.; Petrov, V.; Griebner, U.; Mateos, X.; Koopmann, P.; Kränkel, C.

    2011-11-01

    Tetragonal double tungstate single crystals with formula NaT(WO4)2 have been grown by the Czochralski (T = Gd, La, Y) or by the top-seeded solution growth (T = Lu) methods with Tm concentration between 8 × 1018 and 7.85 × 1020 cm-3. The spectroscopic properties of Tm3+ in these crystals are related with the peculiarities of their I4¯ crystalline structure. Sixty-five percent of La ions in NaLa(WO4)2 are in the 2d site, while in the other crystal hosts, the lanthanide occupies preferentially the 2b site (59% in T = Gd, 74% in T = Y, and 58% in T = Lu). As a consequence, the linewidths of spectral bands associated with the electronic transitions are significantly narrower in NaLa(WO4)2 than in the rest of the isostructural crystals considered. Polarized spectroscopic measurements at 5 K and at higher temperatures, along with energy level simulation of the 4f12 configuration using a single-electron Hamiltonian, including free-ion and crystal field interactions, allowed us to determine the irreducible representation and energy of Stark levels up to the 3P0 multiplet and thus to obtain realistic partition functions (Z) used for emission cross-section calculations. In particular, for the 3F4(u) → 3H6(l) laser transition at λ ≈ 2 μm, this provides: Zl/Zu = 1.436 (T = Gd), 1.464 (T = La), 1.448 (T = Y), and 1.471 (T = Lu). Radiative lifetimes calculated by the Judd-Ofelt and Füchtbauer-Ladenburg methods are in agreement and decrease in the following order T = Gd, La, Y, and Lu, however, nonradiative losses are stronger for T = Gd and La crystals; therefore, experimental lifetimes of 1D2, 1G4, 3H4, and 3F4 Tm3+ multiplets do not change too much with crystal host. For 4.68 at.% Tm:NaY(WO4)2 crystal continuous-wave laser operation is obtained with ≈42% of slope efficiency and a record (for this crystal class) tuning capability of λ = 1847-2069 nm. The broad bandwidths, ΔλFWHM > 20 nm, of the free-running laser emission are promising for ultrafast (fs) mode

  11. Ternary rare earth silicides RE2M3Si4 (RE = Sc, Y, Lu; M = Mo, W): crystal structure, coloring and electronic properties.

    PubMed

    Nielsen, Morten B; Xie, Weiwei; Cava, Robert J

    2016-03-01

    The ternary compounds Sc2Mo3Si4, Y2Mo3Si4, Lu2Mo3Si4 and Sc2W3Si4 have been synthesized using arc melting and structurally characterized using single crystal X-ray diffraction. The compounds are isostructural with Gd5Si4 but with coloring (order of the rare earth and transition metals) on the Gd site. In contrast to group 4 and 5 ternaries of the same type, we observe no site mixing between the rare earth and transition metals. The Y compound displays a different, less common coloring from the others and through DFT calculations and investigation of the solid solution between Sc2Mo3Si4 and Y2Mo3Si4 it is shown that the different coloring of the latter is only marginally more stable. The electronic structures of the ternary compounds have been investigated using DFT calculations, yielding densities of states very similar to Gd5Si4. These predict metallic behavior and no magnetism, which is confirmed through resistivity and magnetization measurements. PMID:26817679

  12. Nanostructured crystals of fluorite phases Sr{sub 1-x}R{sub x}F{sub 2+x} and their ordering: 7. A procedure for cluster modeling of Sr{sub 1-x}R{sub x}F{sub 2+x} Based on the Structure of an Ordered Phase (R = Lu)

    SciTech Connect

    Sul'yanova, E. A. Verin, I. A.; Sobolev, B. P.

    2012-01-15

    Single crystals of the Sr{sub 1-x}Lu{sub x}F{sub 2+x} nonstoichiometric phase (x = 0.095 and 0.189), which crystallizes in the CaF{sub 2} structure type (space group Fm3-barm), are studied by X-ray diffraction. A procedure for the cluster modeling of Sr{sub 1-x}Lu{sub x}F{sub 2+x} based on the fine structural features of the Sr{sub 4}Lu{sub 3}F{sub 17} stoichiometric compound with a fluorite derivative structure (one of the ordered phases in the SrF{sub 2}-LuF{sub 3} system) is proposed. The description of the structure of the Sr{sub 1-x}Lu{sub x}F{sub 2+x} solid solutions is based on the octacubic configuration of the {l_brace}M{sub 14-n}R{sub n}F{sub 64+n}{r_brace} defect cluster. Structural data on the displacements of cations and anions in the ordered Sr{sub 4}Lu{sub 3}F{sub 17} phase (in relation to the undistorted fluorite phase) allow one to identify the distortions of the crystal lattice of the disordered (nonstoichiometric) Sr{sub 1-x}Lu{sub x}F{sub 2+x} phase.

  13. Size/morphology induced tunable luminescence in upconversion crystals: ultra-strong single-band emission and underlying mechanisms.

    PubMed

    Wang, Zhaofeng; Zeng, Songshan; Yu, Jingfang; Ji, Xiaoming; Zeng, Huidan; Xin, Shuangyu; Wang, Yuhua; Sun, Luyi

    2015-06-01

    In this work, we present a two-step method to controllably synthesize novel and highly efficient upconversion materials, Lu5O4F7:Er(3+),Yb(3+) nano/micro-crystals, and investigate their size/morphology induced tunable upconversion properties. In addition to the common phenomenon aroused by a surface quenching effect, direct experimental evidence for the regulation of phonon modes is obtained in nanoparticles. The findings in this work advance the existing mechanisms for the general explanation of size/morphology induced upconversion features. Because of the adjustment of phonon energy and density as well as the surface quenching effect, the biocompatible Lu5O4F7:Er(3+),Yb(3+) nanoparticles exhibit an ultra-strong single-band red upconversion, rendering them promising for biomedical applications.

  14. Quasi four-level Tm:LuAG laser

    NASA Technical Reports Server (NTRS)

    Jani, Mahendra G. (Inventor); Barnes, Norman P. (Inventor); Hutcheson, Ralph L. (Inventor); Rodriguez, Waldo J. (Inventor)

    1997-01-01

    A quasi four-level solid-state laser is provided. A laser crystal is disposed in a laser cavity. The laser crystal has a LuAG-based host material doped to a final concentration between about 2% and about 7% thulium (Tm) ions. For the more heavily doped final concentrations, the LuAG-based host material is a LuAG seed crystal doped with a small concentration of Tm ions. Laser diode arrays are disposed transversely to the laser crystal for energizing the Tm ions.

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

    PubMed

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

    2015-01-28

    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.

  16. High-power CW and passively Q-switched laser operation of Yb:GdCa4O(BO3)3 crystal

    NASA Astrophysics Data System (ADS)

    Chen, Xiaowen; Wang, Lisha; Liu, Junhai; Guo, Yunfeng; Han, Wenjuan; Xu, Honghao; Yu, Haohai; Zhang, Huaijin

    2016-05-01

    We demonstrate efficient high-power CW and passively Q-switched operations of Yb:GdCa4O(BO3)3 lasers. An output power of 18.2 W is generated at 1031.5 nm in CW mode, with optical-to-optical and slope efficiencies being respectively 55% and 70%, with respect to incident pump power. In passively Q-switched operation with a Cr4+:YAG crystal as saturable absorber, a maximum average output power of 15.6 W is produced at a pulse repetition rate of 91 kHz, with an optical-to-optical efficiency of 44%. Low-repetition-rate Q-switched action is also realized, generating an average output power of 4.2 W at 5.7 kHz, the resulting pulse energy and duration are 737 μJ and 3.6 ns, leading to a peak power amounting to 205 kW.

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

    PubMed

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

    2015-01-28

    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

  18. Dynamically Tuning the Up-conversion Luminescence of Er3+/Yb3+ Co-doped Sodium Niobate Nano-crystals through Magnetic Field

    NASA Astrophysics Data System (ADS)

    Xiao, Quanlan; Zhang, Yuanhao; Zhang, Han; Dong, Guoping; Han, Junbo; Qiu, Jianrong

    2016-08-01

    In this work, we show here that the up-conversion luminescence of NaNbO3:Er3+/Yb3+ nano-materials can be modulated by magnetic field and a enhancement of up-conversion intensities by a factor of about 2 for Er3+:4S3/2 → 4I15/2 obtained at 30 T and about 5.4 for Er3+:4F9/2 → 4I15/2 obtained at 20 T. The increased up-conversion luminescence are mainly interpreted in terms of the enhanced non-radiation transition from 4I11/2 to 4I13/2 of Er3+ ions and the spin-orbital coupling (that is “mixing” effect) in crystal field by an external magnetic field. Meanwhile, we observed continuously spectra broadening with growing the magnetic field intensity, which is ascribed to the “mixing” effect induced by magnetic field and the difference of g factor of sub-bands. This bi-functional material with controllable optical-magnetic interactions has various potential applications, such as optical detection of magnetic field, etc.

  19. Dynamically Tuning the Up-conversion Luminescence of Er(3+)/Yb(3+) Co-doped Sodium Niobate Nano-crystals through Magnetic Field.

    PubMed

    Xiao, Quanlan; Zhang, Yuanhao; Zhang, Han; Dong, Guoping; Han, Junbo; Qiu, Jianrong

    2016-08-09

    In this work, we show here that the up-conversion luminescence of NaNbO3:Er(3+)/Yb(3+) nano-materials can be modulated by magnetic field and a enhancement of up-conversion intensities by a factor of about 2 for Er(3+):(4)S3/2 → (4)I15/2 obtained at 30 T and about 5.4 for Er(3+):(4)F9/2 → (4)I15/2 obtained at 20 T. The increased up-conversion luminescence are mainly interpreted in terms of the enhanced non-radiation transition from (4)I11/2 to (4)I13/2 of Er(3+) ions and the spin-orbital coupling (that is "mixing" effect) in crystal field by an external magnetic field. Meanwhile, we observed continuously spectra broadening with growing the magnetic field intensity, which is ascribed to the "mixing" effect induced by magnetic field and the difference of g factor of sub-bands. This bi-functional material with controllable optical-magnetic interactions has various potential applications, such as optical detection of magnetic field, etc.

  20. Dynamically Tuning the Up-conversion Luminescence of Er(3+)/Yb(3+) Co-doped Sodium Niobate Nano-crystals through Magnetic Field.

    PubMed

    Xiao, Quanlan; Zhang, Yuanhao; Zhang, Han; Dong, Guoping; Han, Junbo; Qiu, Jianrong

    2016-01-01

    In this work, we show here that the up-conversion luminescence of NaNbO3:Er(3+)/Yb(3+) nano-materials can be modulated by magnetic field and a enhancement of up-conversion intensities by a factor of about 2 for Er(3+):(4)S3/2 → (4)I15/2 obtained at 30 T and about 5.4 for Er(3+):(4)F9/2 → (4)I15/2 obtained at 20 T. The increased up-conversion luminescence are mainly interpreted in terms of the enhanced non-radiation transition from (4)I11/2 to (4)I13/2 of Er(3+) ions and the spin-orbital coupling (that is "mixing" effect) in crystal field by an external magnetic field. Meanwhile, we observed continuously spectra broadening with growing the magnetic field intensity, which is ascribed to the "mixing" effect induced by magnetic field and the difference of g factor of sub-bands. This bi-functional material with controllable optical-magnetic interactions has various potential applications, such as optical detection of magnetic field, etc. PMID:27502356

  1. Dynamically Tuning the Up-conversion Luminescence of Er3+/Yb3+ Co-doped Sodium Niobate Nano-crystals through Magnetic Field

    PubMed Central

    Xiao, Quanlan; Zhang, Yuanhao; Zhang, Han; Dong, Guoping; Han, Junbo; Qiu, Jianrong

    2016-01-01

    In this work, we show here that the up-conversion luminescence of NaNbO3:Er3+/Yb3+ nano-materials can be modulated by magnetic field and a enhancement of up-conversion intensities by a factor of about 2 for Er3+:4S3/2 → 4I15/2 obtained at 30 T and about 5.4 for Er3+:4F9/2 → 4I15/2 obtained at 20 T. The increased up-conversion luminescence are mainly interpreted in terms of the enhanced non-radiation transition from 4I11/2 to 4I13/2 of Er3+ ions and the spin-orbital coupling (that is “mixing” effect) in crystal field by an external magnetic field. Meanwhile, we observed continuously spectra broadening with growing the magnetic field intensity, which is ascribed to the “mixing” effect induced by magnetic field and the difference of g factor of sub-bands. This bi-functional material with controllable optical-magnetic interactions has various potential applications, such as optical detection of magnetic field, etc. PMID:27502356

  2. CaF2:Yb laser ceramics

    NASA Astrophysics Data System (ADS)

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

    2013-01-01

    CaF2:Yb fluoride laser ceramics, prepared by hot-forming, exhibit the same optical properties as starting single crystals. Slope efficiency of the Сa0.95Yb0.05F2.05 is equal to 35% in the pulsed mode of laser operation. Decrease of ytterbium concentration in CaF2:Yb samples down to 3 mol.% resulted in the essential improvement of Сa0.97Yb0.03F2.03 thermal conductivity from 3.5 to 4.5 W/m K, but slightly decreased (down to 30%) slope efficiency of the samples under both pulsed and CW mode of operation. Alternative hot-pressing synthesis of CaF2:Yb fluoride laser ceramics provided materials with superior mechanical properties (microhardness Н = 3.2 GPa and fracture toughness К1С = 0.65 МPа m1/2) in comparison with hot-formed and/or single crystal CaF2:Yb specimens. For the first time, lasing has been observed for the novel aforementioned hot-pressed CaF2:Yb ceramics.

  3. Preparation, electrochemistry and crystal structure of a derivative of 18-tungstophosphate with Dawson structure: K 16H[Yb(α-2-P 2W 17O 61) 2]·44H 2O

    NASA Astrophysics Data System (ADS)

    Niu, Jingyang; Zhao, Junwei; Guo, Dongjie; Wang, Jingping

    2004-04-01

    The heteropolyanion [Yb(α-2-P 2W 17O 61) 2] 17- has been isolated as a potassium salt in ˜30% yield by five-day decreasing temperature-programmed from 60 °C to room temperature, in a potassium acetate buffer, formed by reaction of K 6P 2W 18O 62·10H 2O with Yb(NO 3) 3 and characterized by IR, UV spectra. Single crystal X-ray structural analysis of K 16H[Yb(α-2-P 2W 17O 61) 2]·44H 2O (triclinic, space group PI a=14.499(3), b=22.433(5), c=24.505(5) Å, α=95.36(3), β=102.67(3), γ=100.06(3)°, Z=2, 24,089 independent reflections, R1=0.0497) reveals that two chemically identical [α-2-P 2W 17O 61] 10- moieties are connected through one Yb atom, which is in a square antiprismatic coordination environment with eight oxygen atoms, four from each of the two [α-2-P 2W 17O 61] 10- moieties. The Yb(III) ion substitutes for two [W=O] 4+ units in the 'cap' regions of the tungsten-oxygen frameworks of the two parent Wells-Dawson ions. The point group symmetry of the title polyanion is C 2. In the extensive pH region from 10.5 to 1.60, the cyclic voltammograms for the title compound in the presence of 0.5 M NaCl aqueous solution as supporting electrolyte mainly illustrate nearly reversible one-electron reduction processes. The results of the thermogravimetric analysis of the title compound show one one-step slow weight loss and the framework decomposition of the polyanion in the title compound is at 560.0 °C.

  4. Upconversion, size analysis, and fiber filling of NaYF4: Ho3+, Yb3+ crystals and nanocolloids

    NASA Astrophysics Data System (ADS)

    Patel, Darayas; Lewis, Ashley; Wright, Donald; Velentine, Maucus; Lewis, Danielle; Valentine, Ruben; Sarkisov, Sergey

    2014-03-01

    Nano-colloids and nano-crystals doped with ions of rare-earth elements have recently attracted a lot of attention in the scientific community. This attention is due to unique physical, chemical and optical properties attributed to nanometer size of the particles. They have great potential of being used in applications spanning from new types of lasers, especially blue and UV ones, phosphorous display monitors, optical communications, and fluorescence imaging. In this paper we investigate the near-infrared upconversion luminescence in bulk crystals and nanocolloid filled photonic crystal fiber with ytterbium and holmium co-doped NaYF4 phosphor. The phosphor is prepared by using simple co-precipitation synthetic method. The initially prepared phosphor has very week upconversion fluorescence. The fluorescence significantly increased after the phosphor was annealed at a temperature of 600 °C. Nanocolloids of this phosphor were obtained using 1-propanol as solvent and they were utilized as laser filling medium in photonic crystal fibers. Under 980 nm diode laser excitation very strong upconversion signals were obtained for ytterbium and holmium co-doped phosphor at 541 nm, 646 nm and 751 nm. Pump power emissions, laser ablation and size analysis of the particles was conducted to understand the upconversion mechanisms. The particle sizes of the nanocolloids were analyzed using Atomic Force Microscope and Malvern Zetasizer instrument. The reported nanocolloids are good candidates for fluorescent biosensing applications and also as a new laser filling medium in fiber laser.

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

    SciTech Connect

    Haberer, Almut; Huppertz, Hubert

    2009-04-15

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

  6. Structure and bonding in Yb4MgGe4: Yb2+/Yb3+ mixed-valency and charge separation.

    PubMed

    Tobash, Paul H; Bobev, Svilen

    2006-03-22

    Reported are the synthesis and the structural characterization of a new derivative of the RE5Tt4 family (RE = Rare-earth; Tt = Tetrel, = Si, Ge, i.e., group 14 element), Yb5-xMgxGe4 (x approximately 1). Crystal data for Yb4.04(1)Mg0.96(1)Ge4 at 23 degrees C: orthorhombic, space group Pnma (No. 62), Z = 4; a = 7.155(2) A, b = 14.769(5) A, c = 7.688(2) A; V = 812.5(4) A3. This phase is an example of a substitution of lanthanide metal (Yb) with a nonmagnetic element (Mg) within this structure type. Its structure can alternatively be described as an intergrowth of the hypothetical Yb2MgGe2, which features flat infinite [MgGe2]4- layers and the hypothetical YbGe with [Ge2]6- dimers. The flat [MgGe2]4- layers propagate in two dimensions (a and c), and they are offset by a distance of 1/4.a with respect to one another and are interspaced with layers of [Ge2]6- dimers and Yb cations filling the space between them. According to the structural and physical property data, Yb4MgGe4 is a heterogeneous mixed-valent compound, i.e. a system where one of the two symmetry-inequivalent Yb sites has atoms in closed-shell Yb2+ configuration, whereas the Yb3+ cations occupy a different crystallographic site.

  7. Multiband electronic transport in α-Yb1-x Sr x AlB4 [x  =  0, 0.19(3)] single crystals.

    PubMed

    Ryu, Hyejin; Abeykoon, Milinda; Bozin, Emil; Matsumoto, Yosuke; Nakatsuji, S; Petrovic, C

    2016-10-26

    We report on the evidence for the multiband electronic transport in α-YbAlB4 and α-Yb0.81(2)Sr0.19(3)AlB4. Multiband transport reveals itself below 10 K in both compounds via Hall effect measurements, whereas anisotropic magnetic ground state sets in below 3 K in α-Yb0.81(2)Sr0.19(3)AlB4. Our results show that Sr(2+) substitution enhances conductivity, but does not change the quasiparticle mass of bands induced by heavy fermion hybridization. PMID:27541840

  8. Multiband electronic transport in α-Yb1-x Sr x AlB4 [x  =  0, 0.19(3)] single crystals

    NASA Astrophysics Data System (ADS)

    Ryu, Hyejin; Abeykoon, Milinda; Bozin, Emil; Matsumoto, Yosuke; Nakatsuji, S.; Petrovic, C.

    2016-10-01

    We report on the evidence for the multiband electronic transport in α-YbAlB4 and α-Yb0.81(2)Sr0.19(3)AlB4. Multiband transport reveals itself below 10 K in both compounds via Hall effect measurements, whereas anisotropic magnetic ground state sets in below 3 K in α-Yb0.81(2)Sr0.19(3)AlB4. Our results show that Sr2+ substitution enhances conductivity, but does not change the quasiparticle mass of bands induced by heavy fermion hybridization.

  9. Frequency mixing crystal

    DOEpatents

    Ebbers, Christopher A.; Davis, Laura E.; Webb, Mark

    1992-01-01

    In a laser system for converting infrared laser light waves to visible light comprising a source of infrared laser light waves and means of harmoic generation associated therewith for production of light waves at integral multiples of the frequency of the original wave, the improvement of said means of harmonic generation comprising a crystal having the chemical formula X.sub.2 Y(NO.sub.3).sub.5 .multidot.2 nZ.sub.2 o wherein X is selected from the group consisting of Li, Na, K, Rb, Cs, and Tl; Y is selected from the group consisting of Sc, Y, La, Ce, Nd, Pr, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Al, Ga, and In; Z is selected from the group consisting of H and D; and n ranges from 0 to 4.

  10. Nonlinear optical crystal optimized for ytterbium laser host wavelengths

    DOEpatents

    Ebbers, Christopher A.; Schaffers, Kathleen I.

    2007-08-21

    A material for harmonic generation has been made by substitutional changes to the crystal LaCa.sub.4(BO.sub.3).sub.3 also known as LaCOB in the form Re1.sub.xRe2.sub.yRe3.sub.zCa.sub.4(B0.sub.3).sub.3O where Re1 and Re2, (rare earth ion 1 and rare earth ion 2) are selected from the group consisting of Sc, Yttrium, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu; Re3 is Lanthanum; and x+y+z=1.

  11. Nonlinear optical crystal optimized for Ytterbium laser host wavelengths

    DOEpatents

    Ebbers, Christopher A.; Schaffers, Kathleen I.

    2008-05-27

    A material for harmonic generation has been made by substitutional changes to the crystal LaCa.sub.4 (BO.sub.3).sub.3 also known as LaCOB in the form Re1.sub.xRe2.sub.yRe3.sub.zCa.sub.4(B0.sub.3).sub.3O where Re1 and Re2, (rare earth ion 1 and rare earth ion 2) are selected from the group consisting of Sc, Yttrium, La, Ce, Pr, Nd, Sm, Eu, Gd, Th, Dy, Ho, Er, Tm, Yb, and Lu; Re3 is Lanthanum; and x+y+z=1.

  12. Nonlinear optical crystal optimized for Ytterbium laser host wavelengths

    DOEpatents

    Ebbers, Christopher A.; Schaffers, Kathleen I.

    2007-02-20

    A material for harmonic generation has been made by substitutional changes to the crystal LaCa.sub.4 (BO.sub.3).sub.3 also known as LaCOB in the form Re1.sub.xRe2.sub.yRe3.sub.zCa.sub.4(BO.sub.3).sub.3O where Re1 and Re2, (rare earth ion 1 and rare earth ion 2) are selected from the group consisting of Sc, Yttrium, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu; Re3 is Lanthanum; and x+y+z=1.

  13. Growth of lanthanide-doped LiGdF4 nanoparticles induced by LiLuF4 core as tri-modal imaging bioprobes.

    PubMed

    Zhai, Xuesong; Lei, Pengpeng; Zhang, Peng; Wang, Zhuo; Song, Shuyan; Xu, Xia; Liu, Xiuling; Feng, Jing; Zhang, Hongjie

    2015-10-01

    Multimodal imaging can compensate for the deficiencies and incorporate the advantages of individual imaging modalities. In this paper, we demonstrated the synthesis of core-shell nanocomposites LiLuF4@LiGdF4:Yb,Er/Tm constituted of tetragonal LiLuF4 nanoparticles as core and Yb,Er/Tm-codoped LiGdF4 as shell. LiLuF4@LiGdF4:Yb,Er/Tm nanoparticles display brighter upconversion luminescence (UCL) than NaGdF4:Yb,Er/Tm nanoparticles with the same size under continuous-wave excitation at 980 nm. The active shell layer of LiGdF4:Yb,Er/Tm not only provide the UCL center, but also serve as magnetic resonance (MR) imaging contrast agent. To further improve the UCL intensity, the inert LiGdF4 shell was coated on the LiLuF4@LiGdF4:Yb,Er/Tm nanoparticles. Furthermore, LiLuF4@LiGdF4:Yb,Tm@LiGdF4 nanoparticles have been successfully applied to UCL/X-ray computed tomography (CT)/MR tri-modal imaging on the modal of tumor-bearing mice. PMID:26148475

  14. High-energy passively Q-switched laser operation of Yb:Ca3La2(BO3)4 disordered crystal.

    PubMed

    Wang, Lisha; Han, Wenjuan; Pan, Zhongben; Xu, Honghao; Chen, Xiaowen; Liu, Junhai; Yu, Haohai; Zhang, Huaijin

    2016-05-01

    Efficient high-energy passively Q-switched laser operation was demonstrated with Yb:Ca3La2(BO3)4 disordered crystal, producing an average output power of 3.0 W at 1018.7 nm, at a pulse repetition frequency of 5.0 kHz; the resulting pulse energy, duration, and peak power were 600 μJ, 5.3 ns, and 113.2 kW, respectively. PMID:27140354

  15. Crystal structure and magnetism of YbFeMnO 5: A neutron diffraction and Mössbauer spectroscopy study

    NASA Astrophysics Data System (ADS)

    Martínez-Lope, M. J.; Retuerto, M.; Alonso, J. A.; García-Hernández, M.; Krezhov, K.; Spirov, I.; Ruskov, T.; Fernández-Díaz, M. T.

    2009-04-01

    We have studied the crystal structure and magnetic properties of Y bFeMnO 5 obtained by substituting Fe 3+ for Mn 3+ in the parent Y bMn 2O 5 compound, through x-ray (XRD) and neutron (NPD) powder diffraction, magnetometry and Mössbauer spectroscopy. The samples were prepared in polycrystalline form by a soft chemistry route, followed by thermal treatments under high-oxygen pressure. The Rietveld analysis of diffraction data shows that Y bFeMnO 5 is isostructural with the oxides of stoichiometry RMn 2O 5 (R=rare earth, Y or Bi); the crystal structure is orthorhombic, Pbam space group, formed by chains of edge-sharing Mn 4+O 6 octahedra linked together by dimer groups of square pyramids Fe 3+O 5 and Y b 3+O 8 scalenohedra. A low level of disorder was established between the two transition metal positions 4 f and 4 h, occupied ideally by Mn 4+ and by Fe 3+: about 6% of Mn cations is replaced by Fe and 16% of Fe by Mn. Mössbauer spectroscopy data confirm the existence of two distinct crystallographic sites for Fe 3+. One of them corresponds to almost regular octahedra (at 4 f positions), characterized by nearly equal Mn/Fe-O distances of 1.890 Å at RT (from NPD data), giving a quadrupole doublet in the Mössbauer spectra at RT, broadened by the Fe/Mn disorder over this site. The second environment for Fe 3+ contributes to a less broadened, but more intensive doublet in the Mössbauer spectra, which corresponds to a distorted square pyramid Fe 3+O 5 (at 4h sites), for which NPD data demonstrates an axial distortion with three sets of Fe-O distances at 2.010(2) Å, 1.859(5) Å and 1.925(3) Å. Magnetic studies and the thermal evolution of the NPD patterns show that below a transition temperature Tc˜178 K a long-range magnetic order is developed, resolved from NPD data as a ferrimagnetic structure with propagation vector k=0. The spin arrangements for the Mn 4+ ions ( 4f site) and Fe 3+ ions ( 4h site) are given by the basis vectors ( 0,0,Fz) and ( 0,0,Fz

  16. Structural and Crystal Chemical Properties of Alkali Rare-earth Double Phosphates

    SciTech Connect

    Farmer, James Matthew; Boatner, Lynn A.; Chakoumakos, Bryan C.; Rawn, Claudia J.; Richardson, Jim

    2016-01-01

    When appropriately activated, alkali rare-earth double phosphates of the form: M3RE(PO4)2 (where M denotes an alkali metal and RE represents either a rare-earth element or Y or Sc) are of interest for use as inorganic scintillators for radiation detection at relatively long optical emission wavelengths. These compounds exhibit layered crystal structures whose symmetry properties depend on the relative sizes of the rare-earth and alkali-metal cations. Single-crystal X-ray and powder neutron diffraction methods were used here to refine the structures of the series of rare-earth double phosphate compounds: K3RE(PO4)2 with RE = Lu, Er, Ho, Dy, Gd, Nd, Ce, plus Y and Sc - as well as the compounds: A3Lu(PO4)2, with A = Rb, and Cs. The double phosphate K3Lu(PO4)2 was reported and structurally refined previously. This material had a hexagonal unit cell at room temperature with the Lu ion six-fold coordinated with oxygen atoms of the surrounding phosphate groups. Additionally two lower-temperature phases were observed for K3Lu(PO4)2. The first phase transition to a monoclinic P21/m phase occurred at ~230 K, and the Lu ion retained its six-fold coordination. The second K3Lu(PO4)2 phase transition occurred at ~130 K. The P21/m space group symmetry was retained, however, one of the phosphate groups rotated to increase the oxygen coordination number of Lu from six to seven. This structure then became isostructural with the room-temperature form of the compound K3Yb(PO4)2 reported here that also exhibits an additional high-temperature phase which occurs at T = 120 °C with a transformation to hexagonal P-3 space group symmetry and a Yb-ion coordination number reduction from seven to six. This latter result was confirmed using EXAFS. The single-crystal

  17. Structural and Crystal Chemical Properties of Alkali Rare-earth Double Phosphates

    DOE PAGESBeta

    Farmer, James Matthew; Boatner, Lynn A.; Chakoumakos, Bryan C.; Rawn, Claudia J.; Richardson, Jim

    2016-01-01

    When appropriately activated, alkali rare-earth double phosphates of the form: M3RE(PO4)2 (where M denotes an alkali metal and RE represents either a rare-earth element or Y or Sc) are of interest for use as inorganic scintillators for radiation detection at relatively long optical emission wavelengths. These compounds exhibit layered crystal structures whose symmetry properties depend on the relative sizes of the rare-earth and alkali-metal cations. Single-crystal X-ray and powder neutron diffraction methods were used here to refine the structures of the series of rare-earth double phosphate compounds: K3RE(PO4)2 with RE = Lu, Er, Ho, Dy, Gd, Nd, Ce, plus Ymore » and Sc - as well as the compounds: A3Lu(PO4)2, with A = Rb, and Cs. The double phosphate K3Lu(PO4)2 was reported and structurally refined previously. This material had a hexagonal unit cell at room temperature with the Lu ion six-fold coordinated with oxygen atoms of the surrounding phosphate groups. Additionally two lower-temperature phases were observed for K3Lu(PO4)2. The first phase transition to a monoclinic P21/m phase occurred at ~230 K, and the Lu ion retained its six-fold coordination. The second K3Lu(PO4)2 phase transition occurred at ~130 K. The P21/m space group symmetry was retained, however, one of the phosphate groups rotated to increase the oxygen coordination number of Lu from six to seven. This structure then became isostructural with the room-temperature form of the compound K3Yb(PO4)2 reported here that also exhibits an additional high-temperature phase which occurs at T = 120 °C with a transformation to hexagonal P-3 space group symmetry and a Yb-ion coordination number reduction from seven to six. This latter result was confirmed using EXAFS. The single-crystal growth methods structural systematics, and thermal expansion properties of the present series of alkali rare-earth double phosphates, as determined by X-ray and neutron diffraction methods, are treated here.« less

  18. Optical properties of Yb-doped Y 2SiO 5 thin films

    NASA Astrophysics Data System (ADS)

    Denoyer, A.; Jandl, S.; Viana, B.; Guillot-Noël, O.; Goldner, P.; Pelenc, D.; Thibault, F.

    2007-11-01

    Yb-doped Y2SiO5 thin films Raman active phonons and crystal-field (CF) excitations have been studied by Raman spectroscopy and infrared transmission, and compared to the single crystals results. The thin films, grown on Y2SiO5 undoped substrate, have been co-doped with Ge, Gd or La in order to adjust the lattice mismatch. Raman active phonon bandwidths indicate that thin films present less strains and defects than single crystals. Interesting thin films properties, such as Yb3+ site occupancies and Yb3+-Yb3+ pair interaction types, may be adjusted by the co-dopants. Infrared absorption shows notably that La3+ is a good co-doping ion to enhance selectively one of the two Yb sites and pair satellite contributions. Ge and Gd co-dopants may also be used to form independently Yb3+-Yb3+ ion pairs with either ferromagnetic or antiferromagnetic dominant interactions.

  19. Heteroepitaxy of single-crystal LaLuO{sub 3} on GaAs(111)A by atomic layer deposition

    SciTech Connect

    Liu Yiqun; Heo, Jaeyeong; Gordon, Roy G.; Xu Min; Ye, Peide D.

    2010-10-18

    We demonstrate that LaLuO{sub 3} films can be grown epitaxially on sulfur-passivated GaAs(111)A substrates by atomic layer deposition (ALD). Transmission electron microscopy and x-ray diffraction analyses reveal that the oxide film exhibits a cubic structure with a lattice mismatch of -3.8% relative to GaAs. The epitaxial layer has a high degree of crystalline perfection and is relaxed. Electrical characterizations performed on this structure show interfaces with a low interface state density of {approx}7x10{sup 11} cm{sup -2} eV{sup -1}. The measured dielectric constant is around 30, which is close to its bulk crystalline value. In contrast, ALD LaLuO{sub 3} is polycrystalline on GaAs(100) and amorphous on Si(111).

  20. Crystal structure, magnetic and dielectric behavior of h-LuMnxO3±δ ceramics (0.95≤x≤1.04)

    NASA Astrophysics Data System (ADS)

    Baghizadeh, A.; Vieira, J. M.; Amaral, J. S.; Graça, M. P.; Soares, M. R.; Mota, D. A.; Amaral, V. S.

    2015-12-01

    Lattice constants, magnetic properties and dielectric behavior of h-LuMnxO3±δ solid solution (0.95≤x≤1.04) of bulk ceramic samples prepared by the solid state reaction method were studied to determine the role of stoichiometry changes on the crystalline structure and magneto-electric coupling. It is found that increasing of Mn content results in reduction of cell volume of h-LuMnxO3±δ ceramics mostly due to shrinkage of a-axis length. The antiferromagnetic interactions of Mn3+ ions weaken with cell volume contraction. A weak ferromagnetic contribution appeared in all samples and extends up to the Neel temperature, TN. Irreversibility in temperature dependent magnetic measurements already reported for stoichiometric compositions of hexagonal RMnO3 oxides appears for all h-LuMnxO3±δ samples right below Neel ordering transition. An increase of magnetic coercive field and magnetization on cooling below TN in samples is observed in field dependent magnetization and rises as x increases. In addition to the antiferromagnetic ordering transition at TN, two anomalies of the temperature dependent magnetic susceptibility and dielectric constant are identified below TN, centered at 69 K and 31 K respectively, being probably due to inhomogeneity of the crystalline structure inside ceramic grains. Changes of the dielectric constant at TN can be attributed to magneto-electric coupling in the off-stoichiometric hexagonal LuMnxO3±δ lattice. The behavior of the dielectric relaxation follows a thermally activated mechanism with activation energy values characteristic of polaron hoping.

  1. Analysis of vacuum ultraviolet electronic spectra of Ce3+ and Pr3+ ions in Ca9Lu(PO4)7: crystal-field calculations and simulation of optical spectra.

    PubMed

    Ma, C-G; Trevisani, M; Piccinelli, F; Ivanovskikh, K V; Bettinelli, M; Brik, M G

    2013-04-24

    The 4f-5d excitation and emission spectra of Ce(3+) and Pr(3+) ions in Ca9Lu(PO4)7 as recently reported (2012 J. Phys.: Condens. Matter 24 385502) were further analyzed and simulated by employing the effective Hamiltonian model for the 4f(N) and 4f(N-1)5d electronic configurations of impurity lanthanide ions and the exchange charge model of crystal-field theory. The multi-site effect on the 4f-5d transition spectra was explicitly discussed from the points of view of the local structure and site occupation ratios of lanthanide ions in Ca9Lu(PO4)7. An excellent agreement between the predicted and measured spectra confirms the validity of the performed calculations. Based on these energy level and intensity calculation results, the radiative lifetimes of the 5d-4f emissions of Ce(3+) and Pr(3+) ions have been modeled to show nearly independent temperature trends. Comparison with the measured lifetimes suggests the nonradiative relaxation process in this host is probably related to the intrinsic defect states. In addition to the studies of the 4f-5d transitions, a general theoretical scheme to calculate the lowest 4f-6s transition energy of the Ce(3+) ion was proposed for the first time on the basis of the ligand polarization model. The predicted 6s energy position of the Ce(3+) ion in Ca9Lu(PO4)7 is solid evidence corroborating our previous spectroscopic assignment.

  2. Structure and properties of Pb(Lu{sub 1/2}Nb{sub 1/2})O{sub 3}–0.2PbTiO{sub 3} relaxor ferroelectric crystal

    SciTech Connect

    Liu, Ying; Yang, Xiaoming; Lai, Fachun; Huang, Zhigao; Li, Xiuzhi; Wang, Zujian; He, Chao; Lin, Ju; Long, Xifa

    2015-07-15

    Graphical abstract: The relaxor state of the crystal was demonstrated by the dielectric behavior. - Highlights: • PLN–0.2PT ferroelectric crystal was obtained by the TSSG technique. • The super-lattice reflections were identified by XRD and TEM results. • The PLN–0.2PT crystal is a typical relaxor ferroelectric. - Abstract: Ferroelectric crystal Pb(Lu{sub 1/2}Nb{sub 1/2})O{sub 3}–0.2PbTiO{sub 3} (PLN–0.2PT) was successfully obtained by a top-seed solution growth technique. At room temperature the symmetry was orthorhomic according to X-ray diffraction (XRD). The super-lattice reflections were identified by XRD and transmission electron microscope (TEM). The micro-domain structure was detected by TEM. The temperature dependence of the dielectric constant (ϵ′) shows a typical relaxor behavior. The temperature dependence of coercive electric field and remnant polarizations were investigated, which also shows the relaxor feature.

  3. An investigation of structural parameters and magnetic and optical properties of EuLn{sub 2}Q{sub 4} (Ln=Tb-Lu, Q=S, Se)

    SciTech Connect

    Jin Gengbang; Choi, Eun Sang; Guertin, Robert P.; Albrecht-Schmitt, Thomas E.

    2008-01-15

    EuLn{sub 2}Q{sub 4} (Ln=Tb-Lu; Q=S, Se) has been synthesized using Sb{sub 2}Q{sub 3} (Q=S, Se) fluxes at 1000 deg. C. These compounds crystallize in a CaFe{sub 2}O{sub 4}-type three-dimensional channel structure that is built from edge-shared double rutile chains of [LnQ{sub 6}] octahedra running down the b-axis. Each double chain is connected at the vertices to four other double chains to form open channels where bicapped trigonal prismatic Eu{sup 2+} ions reside. All of these compounds show antiferromagnetic ordering with Neel temperatures, T{sub N}{approx}3-4 K. The optical band gaps for EuTb{sub 2}Se{sub 4}, EuDy{sub 2}Se{sub 4}, EuHo{sub 2}Se{sub 4}, EuEr{sub 2}Se{sub 4}, EuTm{sub 2}Se{sub 4}, EuYb{sub 2}Se{sub 4} EuLu{sub 2}Se{sub 4}, and EuYb{sub 2}S{sub 4} are found to be 2.0, 1.8, 1.8, 1.7, 1.8, 1.3, 1.7, and 1.6 eV, respectively. - Graphical abstract: A view of the three-dimensional channel structure of EuYb{sub 2}S{sub 4} down the b-axis.

  4. Hydrogen in polar intermetallics: Syntheses and structures of the ternary Ca{sub 5}Bi{sub 3}D{sub 0.93}, Yb{sub 5}Bi{sub 3}H{sub x}, and Sm{sub 5}Bi{sub 3}H{sub a}pprox{sub 1} by powder neutron or single crystal X-ray diffraction

    SciTech Connect

    Alejandro Leon-Escamilla, E.; Dervenagas, Panagiotis; Stassis, Constantine; Corbett, John D.

    2010-01-15

    The syntheses of the title compounds are described in detail. Structural characterizations from refinements of single crystal X-ray diffraction data for Yb{sub 5}Bi{sub 3}H{sub x} and Sm{sub 5}Bi{sub 3}H{sub a}pprox{sub 1} and of powder neutron diffraction data for Ca{sub 5}Bi{sub 3}D{sub 0.93(3)} are reported. These confirm that all three crystallize with the heavy atom structure type of beta-Yb{sub 5}Sb{sub 3}, and the third gives the first proof that the deuterium lies in the center of nominal calcium tetrahedra, isostructural with the Ca{sub 5}Sb{sub 3}F-type structure. These Ca and Yb phases are particularly stable with respect to dissociation to Mn{sub 5}Si{sub 3}-type product plus H{sub 2}. Some contradictions in the literature regarding Yb{sub 5}Sb{sub 3} and Yb{sub 5}Sb{sub 3}H{sub x} phases are considered in terms of adventitious hydrogen impurities that are generated during reactions in fused silica containers at elevated temperatures. - Graphical abstract: The structure of Ca{sub 5}Bi{sub 3}H{sub 0.93} occurs in the novel Ca{sub 5}Sb{sub 3}F structure type with D centered in the shaded calcium tetrahedra.

  5. Lu-Hf constraints on the evolution of lunar basalts

    SciTech Connect

    Fujimaki, H.; Tatsumoto, M.

    1984-02-15

    Very low Ti basalts andd green glass samples from the moon show high Lu/Hf ratios and low Hf concentrations. Low-Ti lunar basalts show high and variable Lu/Hf ratios and higher Hf concentrations, whereas high-Ti lunar basalts show low Lu/Hf ratios and high Hf concentrations. KREEP basalts have constant Lu/Hf ratios and high but variable Hf concentrations. Using the Lu-Hf behavior as a constraint, we propose a model for the mare basalts evolution. This constraint requires extensive crystallization of the primary lunar magma ocean prior to formation of the lunar mare basalt sources and the KREEP basalts. Mare basalts are produced by the melting of the cumulate rocks, and KREEP basalts represent the residual liquid of the magma ocean.

  6. Block LU factorization

    NASA Technical Reports Server (NTRS)

    Demmel, James W.; Higham, Nicholas J.; Schreiber, Robert S.

    1992-01-01

    Many of the currently popular 'block algorithms' are scalar algorithms in which the operations have been grouped and reordered into matrix operations. One genuine block algorithm in practical use is block LU factorization, and this has recently been shown by Demmel and Higham to be unstable in general. It is shown here that block LU factorization is stable if A is block diagonally dominant by columns. Moreover, for a general matrix the level of instability in block LU factorization can be founded in terms of the condition number kappa(A) and the growth factor for Gaussian elimination without pivoting. A consequence is that block LU factorization is stable for a matrix A that is symmetric positive definite or point diagonally dominant by rows or columns as long as A is well-conditioned.

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

    SciTech Connect

    Rao, Ling; Lu, Wei; Wang, Haibo; Yi, Zhigao; Zeng, Songjun; Li, Zheng

    2015-04-15

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

  8. Eleven new compounds in the RE-Cd-Ge systems (RE=Pr, Nd, Sm, Gd-Yb; Y): Crystal chemistry of the RE{sub 2}CdGe{sub 2} series

    SciTech Connect

    Guo Shengping; Meyers, John J.; Tobash, Paul H.; Bobev, Svilen

    2012-08-15

    A large new family of rare-earth metal-cadmium-germanides RE{sub 2}CdGe{sub 2} (RE=Y, Pr, Nd, Sm, Gd-Yb) has been synthesized and structurally characterized. All eleven structures have been established from single-crystal X-ray diffraction data and have been found to belong to the tetragonal Mo{sub 2}FeB{sub 2} structure type (ordered ternary variant of the U{sub 3}Si{sub 2} structure type-space group P4/mbm (No. 127), Z=2; Pearson symbol tP10). The structural variations among the three series of isostructural RE{sub 2}MgGe{sub 2}, RE{sub 2}InGe{sub 2}, and RE{sub 2}CdGe{sub 2} compounds are discussed, as well as the crystal chemistry changes as a function of the decreasing size of the rare-earth metals (lattice constants a=7.176(2)-7.4589(12) A and c=4.1273(14)-4.4356(13) A). The experimental results have been complemented by tight-binding linear muffin-tin orbital (TB-LMTO) electronic structure calculations. - Graphical abstract: More than 300 compounds have been reported to crystallize with the tetragonal U{sub 3}Si{sub 2} structure type, or the Mo{sub 2}FeB{sub 2} structure type, which is its ordered ternary variant. Among them, there are several large RE{sub 2}CdX{sub 2} classes, where the X-elements are typically late transition metals such as Cu, Ni, Au, Pd, Pt, and Rh. The new RE{sub 2}CdGe{sub 2} phases (RE=Y, Pr, Nd, Sm, Gd-Yb) increase the diversity and represent the first cadmium germanides. Highlights: Black-Right-Pointing-Pointer RE{sub 2}CdGe{sub 2} (RE=Y, Pr, Nd, Sm, Gd-Yb) are new ternary germanides. Black-Right-Pointing-Pointer Their structures can be recognized as a 1:1 intergrowth of CsCl- and AlB{sub 2}-like slabs. Black-Right-Pointing-Pointer The Ge atoms are covalently bound into Ge{sub 2} dumbbells. Black-Right-Pointing-Pointer Almost all RE{sub 2}CdGe{sub 2} phases are the first structurally characterized phases in the respective ternary RE-Cd-Ge systems.

  9. Crystal structures of new potassium silicates and aluminosilicates of Sm, Tb, Gd, and Yb and their relation to the armstrongite (CaZr(Si6O15)·3H2O) structure

    NASA Astrophysics Data System (ADS)

    Taroev, Vladimir K.; Kashaev, Anvar A.; Malcherek, Thomas; Goettlicher, Joerg; Kaneva, Ekaterina V.; Vasiljev, Alexander D.; Suvorova, Ludmila F.; Suvorova, Daria S.; Tauson, Vladimir L.

    2015-07-01

    Silicates of composition K7.81Sm3Si12O32(OH)0.81·0.77H2O and K7Tb3Si12O32·1.36H2O, with the space group P 1 bar and unit cell parameters of a=6.9218(3), b=11.4653(4), c=11.6215(4) Å, α=88.063(3)°, β=88.449(3)°, γ=79.266(3)° and a=6.872(3), b=11.440(5), c=11.542(6) Å, α=88.19(4)°, β=88.86(4)°, γ=79.65(4)°, respectively, were synthesized under hydrothermal conditions. Both crystal structures were determined from twinned crystals, and can be idealized to a composition of K7Ln3Si12O32 (KOH)x(H2O)(2-x) (Ln=Sm, Tb), which is closely related to K8Nd3Si12O32(OH). Crystals of the aluminosilicates K2GdAlSi4O12·0.25H2O and K2SmAlSi4O12·0.375H2O prepared by the same method possess monoclinic symmetry with the space group C2/c. The corresponding unit cell parameters are: a=26.67(1), b=7.294(3), c=14.835(6) Å, β=123.44(3)°; and a=26.7406(9), b=7.3288(2), c=14.8498 (6) Å, β=123.514(1)°, respectively. A new type of silicate anion that forms tubes was detected in the K4Yb2Si8O21 structure. K4Yb2Si8O21 is of monoclinic symmetry with the space group C2/c. The unit cell parameters are: a=17.440(2), b=11.786(1), c=12.802 (2) Å, and β=130.902(1)°. The structure is a mixed framework of tubes formed by silica-oxygen tetrahedra connected by pairs of edge sharing Yb-octahedra. The relation of the silicate layers and frameworks encountered in these compounds to the armstrongite silicate framework is discussed.

  10. Spectroscopic properties and laser performances of Yb:YCOB and potential of the Yb:LaCOB material

    NASA Astrophysics Data System (ADS)

    Aron, A.; Aka, G.; Viana, B.; Kahn-Harari, A.; Vivien, D.; Druon, F.; Balembois, F.; Georges, P.; Brun, A.; Lenain, N.; Jacquet, M.

    2001-02-01

    In order to increase the compacity of the Yb-doped lasers, YCOB (Ca 4Y(BO 3) 3) materials with high ytterbium concentration have been characterized. Large 15 at.% and 35 at.% ytterbium-doped single crystals were grown by the Czochralski pulling method. Spectroscopic and laser properties have been investigated and laser tests performed under titanium sapphire and diode pumping at 976 nm. Low thresholds under Ti:Sa pumping (50 mW) and high slope efficiency under diode pumping (66%) have been obtained. The optical quality and the distribution of Yb 3+ dopant through the highly doped crystals is discussed. First results on the Yb:LaCOB crystals grown by the Czochralski process, containing 46Yb 3+ at.%, are also presented.

  11. Crystal growth and magnetic properties of Ln-Mn-Al (Ln=Gd, Yb) compounds of the CaCr{sub 2}Al{sub 10} and ThMn{sub 12} structure types

    SciTech Connect

    Fulfer, Bradford W.; Haldolaarachchige, Neel; Young, David P.; Chan, Julia Y.

    2012-10-15

    We report the growth and characterization of LnMn{sub 2+x}Al{sub 10-x} (Ln=Gd, Yb) crystals adopting the CaCr{sub 2}Al{sub 10} and ThMn{sub 12} structure types. Single crystals of LnMn{sub 2+x}Al{sub 10-x} were synthesized via the self-flux method and characterized with single crystal X-ray diffraction. We compare LnMn{sub 2+x}Al{sub 10-x} compounds adopting the CaCr{sub 2}Al{sub 10} and ThMn{sub 12} structure types, and outline synthesis methods to obtain each polymorph. Magnetic susceptibility measurements show paramagnetic behavior down to 3 K for both CaCr{sub 2}Al{sub 10}- and ThMn{sub 12}-type compounds, with observed magnetic moments of 1.3{mu}{sub B} for compounds adopting the CaCr{sub 2}Al{sub 10} structure type to 4.2{mu}{sub B} for those adopting the ThMn{sub 12} structure type. Compounds of both structure type exhibit metallic resistivity, with upturns at low temperature attributed to Kondo scattering. - Graphical abstract: We report the growth and characterization of LnMn{sub 2+x}Al{sub 10-x} (Ln=Gd, Yb) crystals adopting the CaCr{sub 2}Al{sub 10} and ThMn{sub 12} structure types. Single crystals of LnMn{sub 2+x}Al{sub 10-x} were synthesized via the self-flux method and characterized with single crystal X-ray diffraction. We compare LnMn{sub 2+x}Al{sub 10-x} compounds adopting the CaCr{sub 2}Al{sub 10} and ThMn{sub 12} structure types, and outline synthesis methods to obtain each polymorph. Magnetic susceptibility measurements show paramagnetic behavior down to 3 K for both CaCr{sub 2}Al{sub 10}- and ThMn{sub 12}-type compounds, with observed magnetic moments of 1.3{mu}{sub B} for compounds adopting the CaCr{sub 2}Al{sub 10} structure type to 4.2{mu}{sub B} for those adopting the ThMn{sub 12} structure type. Compounds of both structure type exhibit metallic resistivity, with upturns at low temperature attributed to Kondo scattering. Highlights: Black-Right-Pointing-Pointer We have grown Ln (Mn,Al){sub 12} (Ln=Gd, Yb) single crystals of the ThMn{sub 12

  12. The Yb-doped aluminosilicate fibers photodarkening mechanism based on the charge-transfer state excitation

    NASA Astrophysics Data System (ADS)

    Rybaltovsky, A. A.; Bobkov, K. K.; Velmiskin, V. V.; Umnikov, A. A.; Shestakova, I. A.; Guryanov, A. N.; Likhachev, M. E.; Bubnov, M. M.; Dianov, E. M.

    2014-03-01

    We have studied the photodarkening effect in fiber preforms with an ytterbium-doped aluminosilicate glass core. The room-temperature stable Yb2+ ions formation in the glass matrix under both UV- and NIR-pumping irradiation was revealed by the method of absorption spectra analysis and the fluorescence spectroscopy technique. Comparative studies of preforms and crystals samples luminescence spectra, obtained under UV-excitation, were performed. A general mechanism of Yb2+ ions and aluminium oxygen-hole centers (Al-OHC) formation as a result of photoinduced process of Yb3+ ions excitation to "charge-transfer state" (CTS) was found for both Yb:YAG crystal and aluminosilicate glass.

  13. Accurate Determination of Radionuclidic Purity and Half-Life of Reactor Produced LU-177G for Metabolic Radioimmunotherapy

    NASA Astrophysics Data System (ADS)

    Groppi, F.; Canella, L.; Bonardi, M. L.; Zona, C.; Morzenti, S.; Menapace, E.; Alfassi, Z. B.; Chinol, M.; Papi, S.; Tosi, G.

    2006-04-01

    The accurate determination of radionuclidic purity and half-life of the beta emitter 177gLu used for metabolic radioimmunotherapy is presented. High-resolution gamma spectrometry, as well as deconvolution of beta decay curve measured by spectrometry with liquid scintillation counting, have been adopted for quality control of different samples available on the market. A simple method was developed to distinguish between the different methods available for production of 177gLu: i.e. either direct (n,γ) reactions of enriched 176Lu or indirect (n,γ) activation of enriched 176Yb followed by β- decay. In the first case, the long-lived metastable level 177mLu is present in the radioactive preparation and a low specific activity radionuclide is obtained, in the latter a very high purity and high specific activity 177gLu is produced.

  14. Two stages of zircon crystallization in the Jingshan monzogranite, Bengbu Uplift: Implications for the syn-collisional granites of the Dabie-Sulu UHP orogenic belt and the climax of movement on the Tan-Lu fault

    NASA Astrophysics Data System (ADS)

    Wang, X.; Chen, J.; Griffin, W. L.; O'Reilly, S. Y.; Huang, P. Y.; Li, X.

    2011-03-01

    The detailed study of zircon can provide vital clues about the petrogenetic environment of granitoid rocks. Morphological and chemical studies of zircon grains from the Jingshan monzogranite in the Bengbu Uplift (Anhui province, eastern China) identify three phases of growth. Zircon I is brown, translucent, ovoid, and occurs as inherited cores. It shows two groups of 206Pb/ 238U ages, corresponding to the country rock of the Jingshan monzogranite and the basement of the Bengbu Uplift. Zircon II is colorless, transparent and idiomorphic-hypidiomorphic with Ipr = 0.34-0.52, Ipy = 0.03-0.24 and Iel = 0.26-0.34. It shows a very bright CL due to high contents of trace elements (e.g., Y, U and Th), and the oscillatory zoning associated with sector zoning. It contains 1.40-1.66 wt.% HfO 2 with a mean ɛ Hf (t) of - 17.88. These features indicate the igneous crystallization of Zircon II from a peraluminous granite of mainly crustal origin. Based on the field geology, petrography, geochemical analysis, and especially a weighted mean age of 222 Ma for Zircon II, we argue that the Jingshan monzogranite is a syn-collisional granite of the Dabie UHP orogenic belt. This provides new evidence for the northward subduction of the South China Block beneath the North China Block just before 222 Ma, and allows quantitative estimates of the rate of post-UHP exhumation in the Dabie orogenic belt. Zircon III is also colorless and transparent, but is totally idiomorphic with Ipr = 0.41-1.00, Ipy = 0.88-1.00 and Iel = 0.39-0.83. It occurs only as overgrowths on Zircon II, and shows weak CL due to its depletion in trace elements. Zircon III has widely variable contents of HfO 2 (1.12 to 3.01 wt.%) and Hf-isotope compositions very similar to those of Zircon II. These features suggest crystallization of Zircon III from small volumes of leucosome, probably in the beginning stages of migmatisation. Zircon III has a weighted mean age of 156 Ma, interpreted as representing the climax of movement

  15. Synchrotron Radiation Diffraction Study of YbInCu4

    NASA Astrophysics Data System (ADS)

    Utsumi, Yuki; Sato, Hitoshi; Moriyoshi, Chikako; Kuroiwa, Yoshihiro; Namatame, Hirofumi; Taniguchi, Masaki; Hiraoka, Koichi; Kojima, Kenichi; Sugimoto, Kunihisa

    2011-05-01

    The structural change of an YbInCu4 single crystal has been investigated associated with the first-order valence-transition at TV = 42 K using synchrotron radiation diffraction. The Yb-Cu and In-Cu interatomic distances abruptly increase below TV, following the lattice expansion with no change in the C15b-type crystal structure. We find that the distance between Cu ions forming the Cu4 cluster in the crystal is almost unchanged across the valence transition. No abrupt change in the thermal rotational motion of the Cu4 cluster is observed at TV.

  16. Lu-Hf and PbSL geochronology of apatites from Proterozoic terranes: A first look at Lu-Hf isotopic closure in metamorphic apatite

    NASA Astrophysics Data System (ADS)

    Barfod, Gry Hoffmann; Krogstad, Eirik Jens; Frei, Robert; Albarède, Francis

    2005-04-01

    The mineral apatite is characterized by elevated and highly variable Lu/Hf ratios that, in some cases, allow for single-crystal dating by the Lu-Hf isotopic system. Apatites from the Adirondack Lowlands and Otter Lake area in the Grenville Province, and from the Black Hills, South Dakota, yield Lu-Hf ages that are consistently older than their respective Pb step leaching ages. Isotopic closure for the Lu-Hf system, therefore, occurs before U-Pb system closure in this mineral. In the Adirondack Lowlands, where H 2O activity was low, Lu-Hf systematics of cm-sized apatite crystals remained undisturbed during upper amphibolite facies metamorphism (˜700 to 675 °C) at 1170-1130 Ma. The relatively old Lu-Hf ages of 1270 and 1230 Ma observed for these apatites correlate with decreasing crystal size. In contrast, apatite from the fluid-rich Otter Lake area and Black Hills yields unrealistically low apparent Lu-Hf closure temperatures, implying that in these apatites, fluids facilitated late exchange. The Lu-Hf ages for the metamorphic apatites were thus controlled either by the prevailing temperature and grain size, or by fluid activity.

  17. Production of {sup 177}Lu, a potential radionuclide for diagnostic and therapeutic applications

    SciTech Connect

    Khandaker, Mayeen Uddin; Kassim, Hasan Abu; Haba, Hiromitsu

    2015-04-24

    {sup 177g}Lu (T{sub 1/2}=6.647d; E{sub β{sup −max}}=498.3KeV, I{sub β{sup −total}}=100%; E{sub γ} = 112.9498 keV, I{sub γ} = 6.17%; E{sub γ} = 208.3662 keV, I {sub γ} = 10.36%) is widely used in many clinical procedures due to its excellent decay characteristics. Production cross-sections of the {sup nat}Yb(d,x){sup 177g}Lu reactions have been measured from a 24-MeV deuteron energy down to the threshold by using a stacked-foil activation technique combined with high resolution γ-ray spectrometry. An overall good agreement is found with some of the earlier measurements, whereas a partial agreement is obtained with the theoretical data extracted from the TENDL-2013 library. Physical thick target yield for the {sup 177g}Lu radionuclide was deduced using the measured cross-sections. The deduced yield curves indicate that a low energy (<11 MeV) cyclotron and a highly enriched {sup 176}Yb target could be used to obtain {sup 177g}Lu with negligible impurity from {sup 177m}Lu.

  18. Crystal structure, morphotropic phase transition and luminescence in the new cyclosilicates Sr{sub 3}R{sub 2}(Si{sub 3}O{sub 9}){sub 2}, R=Y, Eu-Lu

    SciTech Connect

    Tyutyunnik, Alexander P.; Leonidov, Ivan I.; Surat, Ludmila L.; Berger, Ivan F.; Zubkov, Vladimir G.

    2013-01-15

    A new series of promising luminescent materials, cyclosilicates Sr{sub 3}R{sub 2}(Si{sub 3}O{sub 9}){sub 2}, R=Y, Eu-Lu, has been synthesized via a solid-state reaction. X-ray and neutron powder diffraction studies show that these oxides crystallize in the monoclinic crystal system (S.G. C2/c, Z=4) and have a morphotropic phase transition between Er and Tm compounds followed by a step-like change of the unit cell constants. Isolated [Si{sub 3}O{sub 9}] rings located in layers are basic building units and stack with Sr/R layers along the [1 0 1{sup Macron }] direction. The rare earth atoms are distributed among three independent Sr/R sites coordinated by 8, 7 and 6 oxygen atoms, and the Sr-R populations change from mixed to 0.5/0.5 over site (1) and full occupation of sites (2) and (3) by Sr and R, respectively, at the transition. Changes of the conformation and mutual arrangement of [Si{sub 3}O{sub 9}] rings, as well as exchange of oxygen atoms from the first and the second coordination sphere of two Sr/R sites also feature the phase transition. Luminescence in Sr{sub 3}Y{sub 2}(Si{sub 3}O{sub 9}){sub 2}:Eu{sup 3+} under ultraviolet (UV) excitation has been discussed. - Graphical abstract: The change of the [Si{sub 3}O{sub 9}] ring conformation in Sr{sub 3}R{sub 2}(Si{sub 3}O{sub 9}){sub 2}, R=Eu, Er, Tm and Lu. Highlights: Black-Right-Pointing-Pointer A new group of cyclosilicates Sr{sub 3}R{sub 2}(Si{sub 3}O{sub 9}){sub 2}, R=Y, Eu-Lu, was first synthesized. Black-Right-Pointing-Pointer Isolated [Si{sub 3}O{sub 9}] rings located in layers are basic building units and stack with Sr/R layers along the [1 0 1{sup Macron }] direction. Black-Right-Pointing-Pointer The rare earth atoms are distributed among three independent Sr/R sites coordinated by 6, 7 and 8 oxygen ligands. Black-Right-Pointing-Pointer A step-like change of the unit cell parameters is observed in the Sr{sub 3}R{sub 2}(Si{sub 3}O{sub 9}){sub 2} structure for R=Er{yields}Tm. Black

  19. Single- and dual-wavelength lasers of diode-pumped Nd:LuYAG mixed crystal on various 4F3/2  →  4I13/2 Stark-level transitions

    NASA Astrophysics Data System (ADS)

    Lan, Jinglong; Wang, Yi; Huang, Xiaoxu; Lin, Zhi; Xu, Bin; Xu, Huiying; Cai, Zhiping; Xu, Xiaodong; Xu, Jun

    2016-08-01

    A diode-end-pumped Nd:LuYAG mixed crystal laser in the 1.3 μm spectral domain using a simple and compact two-mirror laser cavity is reported for the first time to our knowledge. In the free-running laser operation, we obtain a simultaneous dual-wavelength laser at about 1319 and 1338 nm with a maximum output power of 2.92 W and a slope efficiency of about 26.7%. By inserting an undoped YAG etalon into the laser cavity, the two 1319 and 1338 nm lasers can be operated singly with the maximum output powers of 1.36 and 1.73 W. Moreover, three simultaneous dual-wavelength lasers at 1334.67 and 1340.93 nm, 1319.15 and 1354.57 nm, and 1335.54 and 1354.94 nm can also be yielded with maximum output powers of 1.02, 0.66, and 0.47 W as well as slope efficiencies of 12.3%, 8.9%, and 6.9%, respectively. These dual-wavelength laser sources provide potential THz wave generation by beat frequency.

  20. Flashlamp-pumped Ho:Tm:Cr:LuAG laser

    NASA Technical Reports Server (NTRS)

    Jani, Mahendra G. (Inventor); Barnes, Norman P. (Inventor); Murray, Keith E. (Inventor); Kokta, Milan R. (Inventor)

    1997-01-01

    A room temperature solid-state laser is provided. A laser crystal is disposed in a laser cavity. The laser crystal has a LuAG host material doped with a concentration of about 0.35% Ho ions, about 5.57% Tm ions and at least about 1.01% Cr ions. A broadband energizing source such as a flashlamp is disposed transversely to the laser crystal to energize the Ho ions, Tm ions and Cr ions.

  1. Atomic properties of Lu+

    NASA Astrophysics Data System (ADS)

    Paez, Eduardo; Arnold, K. J.; Hajiyev, Elnur; Porsev, S. G.; Dzuba, V. A.; Safronova, U. I.; Safronova, M. S.; Barrett, M. D.

    2016-04-01

    Singly ionized lutetium has recently been suggested as a potential clock candidate. Here we report a joint experimental and theoretical investigation of Lu+. Measurements relevant to practical clock operation are made and compared to atomic structure calculations. Calculations of scalar and tensor polarizabilities for clock states over a range of wavelengths are also given. These results will be useful for future work with this clock candidate.

  2. Efficient Yb³⁺:CaGdAlO₄ bulk and femtosecond-laser-written waveguide lasers.

    PubMed

    Hasse, Kore; Calmano, Thomas; Deppe, Bastian; Liebald, Christoph; Kränkel, Christian

    2015-08-01

    We report on, to the best of our knowledge, the first fs-laser-written waveguide laser in Yb3+:CaGdAlO4 (Yb:CALGO). With Yb:CALGO crystals grown in our labs, we obtained a slope efficiency of 69% and up to 2.4 W of continuous wave (cw) output power in a waveguide-laser configuration. Moreover, bulk laser experiments with Yb:CALGO were performed, and slope efficiencies up to 73%, optical-to-optical efficiencies of 65%, and maximum cw output powers of 3.3 W were reached. These are the highest efficiencies in the laser configuration with Yb:CALGO.

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

    NASA Astrophysics Data System (ADS)

    Lan, Ruijun; Cheng, Hao; Yang, Guang

    2015-12-01

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

  4. Glass-ceramic nuclear waste forms obtained by crystallization of SiO 2-Al 2O 3-CaO-ZrO 2-TiO 2 glasses containing lanthanides (Ce, Nd, Eu, Gd, Yb) and actinides (Th): Study of the crystallization from the surface

    NASA Astrophysics Data System (ADS)

    Loiseau, P.; Caurant, D.

    2010-07-01

    Glass-ceramic materials containing zirconolite (nominally CaZrTi 2O 7) crystals in their bulk can be envisaged as potential waste forms for minor actinides (Np, Am, Cm) and Pu immobilization. In this study such matrices are synthesized by crystallization of SiO 2-Al 2O 3-CaO-ZrO 2-TiO 2 glasses containing lanthanides (Ce, Nd, Eu, Gd, Yb) and actinides (Th) as surrogates. A thin partially crystallized layer containing titanite and anorthite (nominally CaTiSiO 5 and CaAl 2Si 2O 8, respectively) growing from glass surface is also observed. The effect of the nature and concentration of surrogates on the structure, the microstructure and the composition of the crystals formed in the surface layer is presented in this paper. Titanite is the only crystalline phase able to significantly incorporate trivalent lanthanides whereas ThO 2 precipitates in the layer. The crystal growth thermal treatment duration (2-300 h) at high temperature (1050-1200 °C) is shown to strongly affect glass-ceramics microstructure. For the system studied in this paper, it appears that zirconolite is not thermodynamically stable in comparison with titanite growing form glass surface. Nevertheless, for kinetic reasons, such transformation (i.e. zirconolite disappearance to the benefit of titanite) is not expected to occur during interim storage and disposal of the glass-ceramic waste forms because their temperature will never exceed a few hundred degrees.

  5. Optical properties of Yb ions in GaN epilayer

    NASA Astrophysics Data System (ADS)

    Jadwisienczak, W. M.; Lozykowski, H. J.

    2003-07-01

    In recent years, an important effort in semiconductor materials research has been devoted to III-nitrides semiconductors doped with rare earth ions due to the high potential of these materials in light-emitting device applications. Ytterbium (Yb 3+) is one of a few lanthanide ions which have not been investigated as an optically active center in these materials yet. In this paper we report the observation of luminescence from GaN films grown on sapphire (0 0 0 1) substrate by metal organic chemical vapor deposition and doped by implantation with Yb 3+ ions. The high resolution photo- and cathodoluminescence spectra of GaN:Yb 3+ were studied at different excitation conditions in temperatures ranging from 8 to 330 K and revealed weak thermal quenching. The luminescence emission lines are assigned to transitions between the spin-orbit levels 2F 5/2 → 2F 7/2 of Yb 3+ (4f 13). The analysis of the Yb luminescence spectra allowed us to suggest the energy level diagram of the crystal-field-split 4f 13 levels for the Yb ion center. The most probable lattice location of Yb in GaN is the substitutional Ga site. Furthermore, the luminescence kinetics of internal transitions of Yb 3+ incorporated in GaN was investigated by means of decay and time-resolved luminescence measurements. It was found that the ytterbium decay is non-exponential with dominant exponential term of ˜100 μs with little dependence on the ambient temperature. The results indicate that Yb-doped GaN epilayer may be suitable as a material for near infrared optoelectronic devices.

  6. Structure determination of KScS₂, RbScS₂ and KLnS₂ (Ln = Nd, Sm, Tb, Dy, Ho, Er, Tm and Yb) and crystal-chemical discussion.

    PubMed

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

    2015-07-01

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

  7. Lanthanide triangles sandwiched by tetranuclear copper complexes afford a family of hendecanuclear heterometallic complexes [Ln(III)3Cu(II)8] (Ln = La-Lu): synthesis and magnetostructural studies.

    PubMed

    Iasco, Olga; Novitchi, Ghenadie; Jeanneau, Erwann; Luneau, Dominique

    2013-08-01

    Reaction in ethanol of 3-hydroxymethylen-5-methylsalicylaldoxime (H3L) with CuCl2·2H2O and LnCl3·xH2O [Ln = La (1), Ce (2), Pr (3), Nd (4), Eu (5), Gd (6), Tb (7), Dy (8), Er (9), Yb (10), Lu (11), Ho (12)] allowed the synthesis of a family of hendecanuclear heterometallic copper(II)-lanthanide(III) clusters with general formula [Ln(III)3Cu(II)8(HL)6(μ4-O)2Cl6(H2O)8]Cl3 (1-12). According to the single-crystal X-ray diffraction investigation, the complexes are isomorphous and crystallize in the trigonal R32 group. The hendecanuclear cluster is formed by two tetrahedral μ4-oxo {Cu4} clusters assembled by three lanthanide ions sandwiched in between. Along the family, the separation between the {Cu4} moieties increases linearly from Lu to La in good correlation with ionic radius of the lanthanide ions. A comparative analysis of the magnetic data for the lanthanum (1) and lutetium (11) compounds shows the presence of ferromagnetic and antiferromagnetic interactions within the μ4-oxo {Cu4} moieties. For the gadolinium (6) and terbium (7) compounds, the magnetic interactions between the lanthanide and the copper ions are found to be ferromagnetic. The dysprosium (8) compound exhibits single-molecule magnet behavior.

  8. LU-HF Age and Isotope Systematics of ALH84001

    NASA Technical Reports Server (NTRS)

    Righter, M.; Lapen, T. J.; Brandon, A. D.; Beard, B. L.; Shafer, J. T.; Peslier, A. H.

    2009-01-01

    Allan Hills (ALH) 84001 is an orthopyroxenite that is unique among the Martian meteorites in having the oldest inferred crystallization age (approx..4.5 to 4.0 Gyr) [e.g., 1-6 and references therein 7]. Its ancient origin makes this stone a critical constraint on early history of Mars, in particular the evolution of different planetary crust and mantle reservoirs. However, because there is significant variability in reported crystallization ages, determination of initial isotope compositions is imprecise making assessment of planetary reservoirs difficult. Here we report a new Lu-Hf mineral isochron age, initial Hf-176/Hf-177 isotope composition, and inferred Martian mantle source compositions for ALH84001 that place constraints on longlived source reservoirs for the enriched shergottite suite of Martian meteorites including Shergotty, Zagami, NWA4468, NWA856, RBT04262, LAR06319, and Los Angeles. Sm-Nd isotope analyses are under way for the same mineral aliquots analyzed for Lu-Hf. The Lu-Hf system was utilized because Lu and Hf are both lithophile and refractory and are not easily redistributed during short-lived thermal pulses associated with shock metamorphism. Moreover, chromite has relatively modest Hf concentrations with very low Lu/Hf ratios [9] yielding tight constraints on initial Hf-176/Hf-177 isotope compositions

  9. Yb{sup 3+}:BaCaBO{sub 3}F: A potential new self-frequency-doubling laser material

    SciTech Connect

    Schaffers, K.I.; DeLoach, L.D.; Ebbers, C.A.; Payne, S.A.

    1995-03-09

    Yb:BaCaBO{sub 3}F (Yb:BCBF) has been investigated as a new laser crystal with potential for self-frequency-doubling. An YB:BCBF laser has been pumped at 912 mm, and a measured slope efficiency of 38% has been obtained for the fundamental laser output at 1034 nm. Single crystal powders of BCBF have been compared with K*P for a relative measure of the second harmonic generating potential, yielding d{sub eff}[BCBF]= (0-66)d{sub eff}[K*P]. The growth, spectroscopy, laser performance, and linear and nonlinear optical properties of YB:BCBF are reported here.

  10. High energy, single-polarized, single-transverse-mode, nanosecond pulses generated by a multi-stage Yb-doped photonic crystal fiber amplifier

    NASA Astrophysics Data System (ADS)

    Shen, Xinglai; Zhang, Haitao; Hao, He; Li, Dan; Li, Qinghua; Yan, Ping; Gong, Mali

    2015-06-01

    We report the construction of a cascaded fiber amplifier where a 40-μm-core-diameter photonic crystal fiber is utilized in the main amplifier stage. Single-transverse-mode, linearly-polarized, 7.5 ns pulses with 1.5 mJ energy, 123 kW peak power and 10 nm spectral bandwidth centered at 1062 nm are generated. To our knowledge, the pulse energy we obtain is the highest from 40-μm-core-diameter photonic crystal fibers, and also the highest for long pulses (>1 ns) with linear polarization and single transverse mode.

  11. Method for fabricating apatite crystals and ceramics

    DOEpatents

    Soules, Thomas F.; Schaffers, Kathleen I.; Tassano, Jr., John B.; Hollingsworth, Joel P.

    2013-09-10

    The present invention provides a method of crystallizing Yb:C-FAP [Yb.sup.3+:Ca.sub.5(PO.sub.4).sub.3F], by dissolving the Yb:C-FAP in an acidic solution, following by neutralizing the solution. The present invention also provides a method of forming crystalline Yb:C-FAP by dissolving the component ingredients in an acidic solution, followed by forming a supersaturated solution.

  12. Point-contact spectroscopy of YbBe13

    NASA Astrophysics Data System (ADS)

    Nowack, A.; Wasser, S.; Schlabitz, W.; Kvitnitskaya, O. E.; Fisk, Z.

    1997-12-01

    Among rare-earth and actinide Be13 intermetallic compounds, YbBe13 is anomalous, with evidence for mixed-valence and heavy-fermion behavior. The resistivity is comparatively low and the resulting large mean free path enables point-contact spectroscopy in the ballistic regime. In the d2V/dI2 characteristics of point contacts between YbBe13 and normal metals, measured at temperatures between 0.2 and 40 K, we find structures due to crystal-field and Kondo scattering. The characteristics show a pronounced asymmetry, which we explain by the enhanced effective electronic mass in YbBe13 and by a shift of the chemical potential in the contact region due to the nonthermal occupation of excited crystal-field levels.

  13. Multimode to single-mode conversion of a Yb-doped fiber amplifier with a photorefractive Rh:BaTiO3 crystal

    NASA Astrophysics Data System (ADS)

    Brignon, A.; Huignard, J.-P.; Lallier, E.

    2001-05-01

    We present a technique to convert a multimode-transverse beam obtained from a multimode large core fiber amplifier into a single-mode beam by means of two-wave mixing in an infrared-sensitive Rh:BaTiO3 crystal.

  14. Synthesis of NaYF4 and NaLuF4 Based Upconversion Nanocrystals and Comparison of Their Properties.

    PubMed

    Ouyang, Juan; Yin, Dongguang; Song, Kailin; Wang, Chengcheng; Liu, Bing; Wu, Minghong

    2015-04-01

    In this study, four kinds of upconversion nanocrystals (UCNs) have been successfully synthesized by a facile solvothermal method. The morphology, crystalline phase, composition, grain size, upconversion luminescence and cell image of the UCNs were investigated. The properties of the NaLuF4-based UCNs were compared with the counterparts of NaYF4-based UCNs. It is found that the NaLuF4-based UCNs are apt to form hexagonal phase structures, while NaYF4-based UCNs of NaYF4:Yb, Er and NaYF4:Gd, Yb, Er are cubic and hexagonal phases respectively. The upconversion emission intensities of the NaLuF4-based UCNs are higher than that of NaYF4-based UCNs, and Gd3+ presented UCNs are higher than that of Gd3+ absented UCNs. The bioimaging application of NaLuF4:Gd, Yb, Er shows that bright upconversion luminescence can be observed when UCNs-labeled HeLa cells are excited with 980 nm light. PMID:26353495

  15. Synthesis of NaYF4 and NaLuF4 Based Upconversion Nanocrystals and Comparison of Their Properties.

    PubMed

    Ouyang, Juan; Yin, Dongguang; Song, Kailin; Wang, Chengcheng; Liu, Bing; Wu, Minghong

    2015-04-01

    In this study, four kinds of upconversion nanocrystals (UCNs) have been successfully synthesized by a facile solvothermal method. The morphology, crystalline phase, composition, grain size, upconversion luminescence and cell image of the UCNs were investigated. The properties of the NaLuF4-based UCNs were compared with the counterparts of NaYF4-based UCNs. It is found that the NaLuF4-based UCNs are apt to form hexagonal phase structures, while NaYF4-based UCNs of NaYF4:Yb, Er and NaYF4:Gd, Yb, Er are cubic and hexagonal phases respectively. The upconversion emission intensities of the NaLuF4-based UCNs are higher than that of NaYF4-based UCNs, and Gd3+ presented UCNs are higher than that of Gd3+ absented UCNs. The bioimaging application of NaLuF4:Gd, Yb, Er shows that bright upconversion luminescence can be observed when UCNs-labeled HeLa cells are excited with 980 nm light.

  16. Laser tunability in Yb 3+:YCa 4O(BO 3) 3 {Yb:YCOB}

    NASA Astrophysics Data System (ADS)

    Shah, L.; Ye, Q.; Eichenholz, J. M.; Hammons, D. A.; Richardson, M.; Chai, B. H. T.; Peale, R. E.

    1999-08-01

    Tunable laser operation in Yb:YCOB from 1018 to 1087 nm pumped by 1.4 W from a Ti:Sapphire laser tuned to 900 nm is demonstrated. The combination of the ability to grow large crystals with high optical quality, broad infrared emission, diode pumpable absorption bands, and a significant non-linear coefficient makes this material very promising for use in tunable and ultrafast laser systems.

  17. Growth and characterization of high-Curie temperature Pb(Lu1/2Nb1/2)O3-Pb(Mg1/3Nb2/3)O3-PbTiO3 ternary single crystal by modified Bridgman technique

    NASA Astrophysics Data System (ADS)

    Chen, Jianwei; Li, Xiaobing; Zhao, Xiangyong; Zhang, Haiwu; Deng, Hao; Chen, Chao; Wang, Xi'an; Ren, Bo; Di, Wenning; Luo, Haosu

    2015-08-01

    A new relaxor-based ferroelectric ternary system Pb(Lu1/2Nb1/2)O3-Pb(Mg1/3Nb2/3)O3-PbTiO3 (PLN-PMN-PT), with a combination of a high-Curie temperature system Pb(Lu1/2Nb1/2)O3-PbTiO3 (PLN-PT) and a high piezoelectricity system Pb(Mg1/3Nb2/3)O3-PbTiO3 (PMN-PT), was investigated in this paper. Single crystal PLN-PMN-PT with dimensions of Φ20×45 mm3 was grown successfully by the modified Bridgman technique for the first time. The studies of structure and composition of the as-grown crystal showed structural consistency but compositional deviation along the growth direction. The <0 0 1>-oriented wafers of the PLN-PMN-PT single crystal showed excellent electrical properties at room temperature: ε33~4500, tanδ~0.5%, d33~2300 pC/N. The crystal was found to exhibit high Curie temperature (TC~176°C), rhombohedral-tetragonal phase transition temperature (TRT~108 °C) and coercive field (EC~8.1 kV/cm), superior to those of PMN-0.3PT single crystal. Studies of temperature dependence ferroelectric properties showed that high values of k33 and d33 could be maintained up to the TRT. These results showed that PLN-PMN-PT piezoelectric single crystal has a higher Curie temperature and coercive field with excellent electrical properties, making the crystal a promising candidate for high-power transducer applications in a broad temperature range.

  18. Czochralski growth of Yb doped oxyapatite for high power laser application

    NASA Astrophysics Data System (ADS)

    Yoshikawa, A.; Fujiwara, C.; Sato, H.; Nishi, T.; Ohta, H.; Fukuda, T.; Waseda, Y.; Boulon, G.; Ito, M.; Guyot, Y.; Lebbou, K.

    2004-09-01

    Ca 8(La,Yb) 2(PO 4) 6O 2 (Yb:CLPA) single crystals with the apatite-type structure could be grown from the melt using the Czochralski method. Grown crystal was 18 mm in diameter and 110 mm in length. It is transparent with slightly blue color. Neither visible inclusion nor crack was observed. Thermal conductivity of Yb:CLPA was calculated from the values of thermal diffusivity, heat capacity measurement and density. Luminescent characterization was carried out from the results of emission, absorption and Raman spectrum.

  19. Electronic structure of YbGa1.15Si0:85 and YbGaxGe2-x probed by resonant x-ray emission and photoelectron spectroscopies

    SciTech Connect

    Yamaoka, Hitoshi; Jarrige, Ignace; Tsujii, Naohito; Imai, Motoharu; Lin, Jung-Fu; Matsunami, Masaharu; Eguchi, Ritsuko; Arita, Masashi; Shimada, Kenya; Namatame, Hirofumi; Taniguchi, Masaki; Taguchi, Munetaka; Senba, Yasunori; Ohashi, Haruhiko; Hiraoka, Nozomu; Ishii, Hirofumi; Tsuei, Ku-Ding

    2011-03-31

    We performed an x-ray spectroscopic study combining resonant x-ray emission spectroscopy (RXES) and photoelectron spectroscopy on the superconducting ternary silicide YbGa 1.15 Si 0.85 and nonsuperconducting ternary germanide YbGax Ge2-x (x = 1.0 and 1.1). The Yb valence for all three compounds is found to be about 2.3. In YbGa1.15 Si0.85 no temperature dependence of the Yb valence is observed in the RXES spectra in the temperature range of 7–300 K, while the valence shows a drastic increase under pressure from the Yb2+ state partially including itinerant electrons to the localized Yb3+ state. Differences are observed in the valence-band spectra of the photoelectron spectroscopy between YbGa1.15 Si0.85 and YbGax Ge2-x , which may be attributed to the difference of crystal structure. We conclude that both the crystal structure of the planar GaSi layer in YbGa1.15 Si0.85 and the resultant electronic structure may have a crucial role in the occurrence of superconductivity.

  20. Growth, structural, thermal, electrical and nonlinear optical properties of Yb3+ doped KTiOPO4

    NASA Astrophysics Data System (ADS)

    Sadhasivam, S.; Perumal, Rajesh Narayana; Ramasamy, P.

    2016-07-01

    The KTiOPO4:Yb (KTP:Yb) crystal has been grown by flux growth at high temperature (~ 1243-1223K). KTP:Yb crystallizes in the orthorhombic crystal system with Pna21 space group. Ytterbium presence was analyzed in the grown crystal by EDAX analysis. The existence of Ti3+ color center has been evaluated using electron paramagnetic spin resonance spectrum. The Raman spectroscopic techniques were used to study the effect of Yb3+ in KTP crystal. Thermal diffusivity, thermal conductivity and specific heat capacity of grown crystal were studied. At low frequency, the dielectric constant decreases sharply in the frequency region of 104 Hz. The electrical conductivity along the [001] is low (9.0435×10-7 S/cm) for 60 kHz at 300 K. The temperature dependent variation of electric conductivity was found for [010] and [001] of KTP:Yb. The effect of Yb3+ doping in second harmonic generation of KTP was studied.

  1. Green and red luminescence in co-precipitation synthesized Pr:LuAG nanophosphor

    NASA Astrophysics Data System (ADS)

    Kumar, S. Arun; Kumar, K. Ashok; Gunaseelan, M.; Asokan, K.; Senthilselvan, J.

    2016-05-01

    Pr:LuAG nanophosphor is an effective candidate in magnetic resonance imaging coupled positron emission tomography (MRI-PET) for medical imaging and scintillator applications. LuAG:Pr (0.05, 0.15 mol%) nanoscale ceramic powders were synthesized by co-precipitation method using urea as precipitant. Effect of antisite defect on structure and luminescence behavior was investigated. Pr:LuAG nanoceramic powders are found crystallized in cubic structure by high temperature calcination at 1400 °C and it shows antisite defect. HR-SEM analysis revealed spherically shaped Pr:LuAG nanoceramic particulate powders with ˜100 nm size. By the excitation at 450 nm, Pr:LuAG nanophosphor exhibit green to red luminescence in the wavelength range of 520 to 680 nm, which is originated from multiplet transition of Pr3+ ions.

  2. Dual nature of 3 d electrons in YbT 2 Zn 20 (T = Co; Fe) evidenced by electron spin resonance

    DOE PAGESBeta

    Ivanshin, V. A.; Litvinova, T. O.; Gimranova, K.; Sukhanov, A. A.; Jia, S.; Bud'ko, S. L.; Canfield, P. C.

    2015-03-18

    The electron spin resonance experiments were carried out in the single crystals YbFe2Zn20. The observed spin dynamics is compared with that in YbCo2Zn20 and Yb2Co12P7 as well as with the data of inelastic neutron scattering and electronic band structure calculations. Our results provide direct evidence that 3d electrons are itinerant in YbFe2Zn20 and localized in YbCo2Zn20. Possible connection between spin paramagnetism of dense heavy fermion systems, quantum criticality effects, and ESR spectra is discussed.

  3. Unique magnetic structure of YbCo2Si2

    NASA Astrophysics Data System (ADS)

    Mufti, N.; Kaneko, K.; Hoser, A.; Gutmann, M.; Geibel, C.; Krellner, C.; Stockert, O.

    2016-07-01

    We report on the results of powder and single-crystal neutron diffraction to investigate the magnetic order in YbCo2Si2 below the Néel temperature TN=1.7 K in detail. Two different magnetically ordered phases can clearly be distinguished. At lowest temperatures a commensurate magnetic structure with a propagation vector k1=(0.25 0.25 1 ) is found, while the intermediate phase (T >0.9 K) is characterized by an incommensurate magnetic structure with k2=(0.25 0.086 1 ) . The magnetic structure in YbCo2Si2 is in marked contrast to all other known R Co2Si2 compounds (R = rare earth element) likely due to some itineracy of the Yb 4 f states being responsible for the magnetism.

  4. Damping in Yb nuclei

    SciTech Connect

    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

    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.

  5. Physical properties and superconductivity of skutterudite-related Yb3Co4.3Sn12.7 and Yb3Co4Ge13

    NASA Astrophysics Data System (ADS)

    Mudryk, Ya; Grytsiv, A.; Rogl, P.; Dusek, C.; Galatanu, A.; Idl, E.; Michor, H.; Bauer, E.; Godart, C.; Kaczorowski, D.; Romaka, L.; Bodak, O.

    2001-08-01

    Rietveld analysis was performed for the intermetallics Yb3Co4.3Sn12.7 and Yb3Co4Ge13 crystallizing with the closely related structure types, Yb3Rh4Sn13 and Yb3Co4Ge13. Below Tc = 3.4 K Yb3Co4.3Sn12.7 crosses over into a type-II superconducting ground state with Hc2(0)~2.5 T. Yb3Co4Ge13 stays in the normal state down to 300 mK. The γ value of 2.3(2) mJ gat-1 K-2 and the Debye temperature ΘD = 207(5) K deduced from the specific heat as well as Tc correspond to that of elementary Sn, thus indicating conventional BCS superconductivity. Hydrostatic pressure applied to Yb3Co4.3Sn12.7 reveals both an overall decrease of the absolute resistivity values, as well as a decrease of Tc, which vanishes for a critical pressure below 10 kbar. The magnetoresistance of both Yb-based compounds is positive at low temperature but does not exceed 8% in fields of 12 T. The Seebeck coefficient has a maximum value of about 18 µV K-1 at T~250 K. LIII and magnetic susceptibility measurements reveal intermediate valence: 2.66(3) and 2.18(3) for Yb3Co4Ge13 and Yb3Co4.3Sn12.7, respectively.

  6. Understanding the Interplay of Polar, Magnetic, and Electronic Order in Ferroic (LuFeO3)m /LuFe2O4 Superlattices

    NASA Astrophysics Data System (ADS)

    Rebola, Alejandro; Das, Hena; Fennie, Craig

    Multiferroics are not only important from a technological point of view but also because of the rich and complex physics that results from the interplay between spin, charge and structural distortions. Hexagonal LuFeO3 has recently been understood theoretical and experimentally, and shown to be an improper structural ferroelectric directly analogous to the hexagonal manganites. LuFe2O4 is structurally homologous to LuFeO3 -both are characterized by a FeO5 bipyramidal crystal field- but unlike the latter it exhibits a much larger magnetic moment and it is still a matter of debate whether it is ferroelectric. The double Fe-layer in LuFe2O4 is thought to be charge ordered and highly frustrated, resulting in possible polar, non-polar or anti-polar charge arrangements. Here we first investigate the relation between different charge and magnetic orders and structural distortions in bulk LuFe2O4 by DFT and Monte Carlo calculations. Then we concentrate on a system that combines both mechanisms -a structural improper ferroelectric and a charge frustrated polar structure- such as the (LuFeO3)m /LuFe2O4superlattices.

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

    DOE PAGESBeta

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

    2015-08-05

    The new phase of YbAg2 was obtained using high-pressure and high-temperature reaction. YbAg2 crystallizes in the MgZn2 structure (the space group P63/mmc space group, No 194) with a = 5.68153(3) Å and c = 9.31995(7) Å and the unit cell volume V = 260.54(3) Å3. The XANES analysis showed that the valence state of Yb is +2.8. The low-temperature dependences of the electrical resistivity and magnetic susceptibility can be adequately described by a T2 term that supports the Fermi-liquid picture. Furthermore, the Kadowaki–Woods relation gives a low value of the degeneracy (N = 2).

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

    SciTech Connect

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

    2015-08-05

    The new phase of YbAg2 was obtained using high-pressure and high-temperature reaction. YbAg2 crystallizes in the MgZn2 structure (the space group P63/mmc space group, No 194) with a = 5.68153(3) Å and c = 9.31995(7) Å and the unit cell volume V = 260.54(3) Å3. The XANES analysis showed that the valence state of Yb is +2.8. The low-temperature dependences of the electrical resistivity and magnetic susceptibility can be adequately described by a T2 term that supports the Fermi-liquid picture. Furthermore, the Kadowaki–Woods relation gives a low value of the degeneracy (N = 2).

  9. Diytterbium(II) lithium indium(III) digermanide, Yb2LiInGe2

    PubMed Central

    You, Tae-Soo; Bobev, Svilen

    2010-01-01

    The title compound, Yb2LiInGe2, a new ordered quaternary inter­metallic phase, crystallizes with the ortho­rhom­bic Ca2LiInGe2 type (Pearson code oP24). The crystal structure contains six crystallographically unique sites in the asymmetric unit, all in special positions with site symmetry .m.. The structure is complex and based on [InGe4] tetra­hedra, which share corners in two directions, forming layers parallel to (001). Yb atoms fill square-pyramidal (Yb1) and octa­hedral (Yb2) inter­stices between the [InGe4/2] layers, while the small Li+ atoms fill tetra­hedral sites. PMID:21578989

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

    DOEpatents

    Krupke, William F.; Payne, Stephen A.; Chase, Lloyd L.; Smith, Larry K.

    1994-01-01

    An ytterbium doped laser material remarkably superior to all others, including Yb:YAG, comprises Ytterbium doped apatite (Yb:Ca.sub.5 (PO.sub.4).sub.3 F) or Yb:FAP, or ytterbium doped crystals that are structurally related to FAP. The new laser material is used in laser systems pumped by diode pump sources having an output near 0.905 microns or 0.98 microns, such as InGaAs and AlInGaAs, or other narrowband pump sources near 0.905 microns or 0.98 microns. The laser systems are operated in either the conventional or ground state depletion mode.

  11. Lattice dynamics of LuPO{sub 4}

    SciTech Connect

    Nipko, J.C. |; Loong, C.-K.; Loewenhaupt, M.; Reichardt, W.; Braden, M.; Boatner, L.A.

    1996-06-01

    Lutetium orthophosphate is an important nonmagnetic host material for rare-earth-activated luminescence applications. We have measured the LuPO{sub 4} phonon density of states and dispersion curves along the [{xi}00],[{xi}{xi}0], and [00{xi}] symmetry directions by neutron spectroscopy using polycrystalline and single-crystal samples. A quantitative analysis of the neutron results was carried out using a lattice-dynamical shell model.

  12. Glass-ceramic nuclear waste forms obtained from SiO 2-Al 2O 3-CaO-ZrO 2-TiO 2 glasses containing lanthanides (Ce, Nd, Eu, Gd, Yb) and actinides (Th): study of internal crystallization

    NASA Astrophysics Data System (ADS)

    Loiseau, P.; Caurant, D.; Baffier, N.; Mazerolles, L.; Fillet, C.

    2004-10-01

    Glass-ceramic waste forms such as zirconolite (nominally CaZrTi 2O 7) based ones can be envisaged as good candidates for minor actinides or Pu immobilization. Such materials, in which the actinides (or lanthanides used as actinide surrogates) would be preferentially incorporated into zirconolite crystals homogeneously dispersed in a durable glassy matrix, can be prepared by controlled crystallization (nucleation + crystal growth) of parent glasses belonging to the SiO 2-Al 2O 3-CaO-ZrO 2-TiO 2 system. In this work we present the effects of the nature of the minor actinide surrogate (Ce, Nd, Eu, Gd, Yb, Th) on the structure, the microstructure and the composition of the zirconolite crystals formed in the bulk of the glass-ceramics. The amount of lanthanides and thorium incorporated into zirconolite crystals is discussed in relation with the capacity of the glass to accommodate these elements and of the crystals to incorporate them in the calcium and zirconium sites of their structure.

  13. Exchange interaction in the YbCrBr3-9 mixed dimer:  The origin of a strong Yb3+-Cr3+ exchange anisotropy

    NASA Astrophysics Data System (ADS)

    Mironov, V. S.; Chibotaru, L. F.; Ceulemans, A.

    2003-01-01

    The superexchange interaction between Yb3+ and Cr3+ ions in the mixed YbCrBr3-9 bioctahedral face-sharing dimer is quantitatively analyzed using a modified kinetic exchange theory, which is adapted to a realistic description of the electronic structure of lanthanide ions in solids. The general procedure of the calculation of the 4f-3d anisotropic exchange spin Hamiltonian is presented and applied to the YbCrBr3-9 dimer. The spin-Hamiltonian of the Yb3+-Cr3+ exchange interaction is found to be extremely anisotropic, H=JzSzYbSzCr+J⊥(SxYbSxCr+SyYbSyCr), with the antiferromagnetic Jz and ferromagnetic J⊥ parameters, where SμYb and SμCr (μ=x,y,z) are the components of the effective spin SYb=1/2 of the Yb3+ ion (corresponding to the ground Γ6 Kramers doublet) and the true spin SCr=3/2 of the Cr3+ ion, respectively. The calculated exchange parameters are quite consistent with the experimental data (Jz=-5.16 cm-1 and J⊥=+4.19 cm-1) at reasonable values of the Yb→Cr and Yb←Cr charge transfer energies. The contributions to the Jz and J⊥ exchange parameters from the individual states of the 4f12-3d4 and 4f14-3d2 charge transfer configurations are analyzed in detail and general regularities are established. Our results indicate that a very strong 4f-3d exchange anisotropy can appear even in the absence of the crystal-field anisotropy on the lanthanide ion.

  14. Direct diode-pumped 58 fs Yb:Sr3Y2(BO3)4 laser

    NASA Astrophysics Data System (ADS)

    Lou, Fei; Sun, Shijia; He, Jingliang; Zhao, Ruwei; Li, Jing; Su, Xiancui; Lin, Zhoubin; Zhang, Baitao; Yang, Kejian

    2016-05-01

    The ultrafast laser performance of Yb:Sr3Y2(BO3)4 (SYB) crystal has been demonstrated for the first time to the best of our knowledge. The Yb:SYB laser was driven to work in SESAM-assisted Kerr-lens mode-locking (KLM) operation, and 58 fs pulses were generated at the central wavelength of 1054.6 nm. A maximum average output power reached 400 mW with a slope efficiency of 13.5%. The experimental results indicated Yb:SYB crystal as a promising candidate for achieving ultrashort lasers.

  15. Disorder-Sensitive Superconductivity and Bonding Network in the Iron-Silicide Superconductor Lu2Fe3Si5

    NASA Astrophysics Data System (ADS)

    Watanabe, Tadataka; Okuyama, Hiroaki; Takase, Kouichi; Takano, Yoshiki; Yoshida, Fumiko; Moriyoshi, Chikako; Kuroiwa, Yoshihiro

    2010-03-01

    Iron silicide superconductor Lu2Fe3Si5 exhibits relatively high Tc = 6.0 K among Fe-based substances. Recent specific heat, penetration depth, and thermal conductivity measurements have provided evidences for the multigap superconductivity. We have studied non-magnetic and magnetic impurity effects on superconductivity in Lu2Fe3Si5 by investigating Tc variations in non-magnetic (Lu1-xScx)2Fe3Si5, (Lu1-xYx)2Fe3Si5 and magnetic (Lu1-xDyx)2Fe3Si5. Small amount of non-magnetic impurities (Sc and Y) on the Lu-site rapidly depresses Tc in accordance with the increase in the residual resistivity. Such a disorder-sensitive superconductivity strongly suggests the sign reversal of the superconducting order parameter. Lu2Fe3Si5 has a complicated crystal structure compared to other multigap superconductors such as MgB2 and iron pnictides. Thus it is important to map out the accurate bonding network in the crystal structure for the better understanding of the electronic structure. We have observed the charge density distribution of Lu2Fe3Si5 by analyzing the synchrotron radiation powder diffraction data using the maximum entropy method/Rietveld method.

  16. Kinetic control of structural and magnetic states in LuBaCo4O7.

    SciTech Connect

    Avci, S.; Chmaissem, O.; Zheng, H.; Huq, A.; Khalyavin, D.; Stephens, P.; Suchomel, M.; Manuel, P.; Mitchell, J.

    2012-01-01

    The RBaCo{sub 4}O{sub 7} (R = Ca, Y, Tb, Ho, Tm, Yb, Lu) compounds provide a novel topology for studying the competition between triangular geometry and magnetic order. Here, we report the structural and magnetic behavior of the Lu member of this series via neutron and synchrotron x-ray diffraction, magnetization, and resistivity measurements. We determined sequential phase transitions and a strong competition between a stable and a metastable low-temperature state that critically depends on controlled cooling rates and the associated heat removal kinetics. No evidence for long-range ordered magnetism was detected by neutron diffraction at any temperature. However, very slow spin dynamics are evidenced by time-dependent neutron diffraction measurements and can be explained by several competing magnetic phases with incommensurate short-range correlations coexisting in this material.

  17. Yb9+xCuMg4-x (x = 0.034): A κ-Phase Formed by Lanthanoids.

    PubMed

    De Negri, Serena; Romaka, Vitaliy; Solokha, Pavlo; Saccone, Adriana; Giester, Gerald; Michor, Herwig; Rogl, Peter F

    2016-08-15

    Atom order in the crystal structures of Yb2Cu2-xMg (x = 0.17; Mo2FeB2-type; P4/mbm; a = 0.75592(2) nm; c = 0.40282(1) nm) and Yb9+xCuMg4-x (x = 0.034; Hf9Mo4B-type; P63/mmc; a = 1.0169(5) nm; c = 1.0290(5) nm) was determined from powder and X-ray single-crystal counter data analyses supported by electron probe microanalyses. Among the group of the so-called κ-phases, Yb9+xCuMg4-x is the first representative formed by a lanthanoid element. The structure of this κ-phase can be viewed as a typical network of corner-connected empty Yb6-octahedra, which encompass Yb6Mg6-icosahedra (filled by a mix of Mg/Yb atoms) and Yb6-trigonal prisms centered by Cu atoms to complete the three-dimensional metal framework. From another point of view, the same structure is considered as built from infinite polyicosahedral columns of Yb9Mg4 composition with Cu atoms located in trigonal prismatic interstices, highlighting similarities with other Yb-rich Yb-Cu-Mg phases. Density functional theory (DFT) calculations classify Yb9CuMg4 as a polar intermetallic. Metallic-like behavior is inferred from the Sommerfeld constant, γ = 49.2 mJ/mol·K(2), derived from the electronic density of states, calculated at the Fermi level. DFT integration of the f-density of states indicates almost completely filled f-states, revealing 13.6 and 13.7 electrons in the valence band for Yb1 and Yb2 atoms, respectively, close to the Yb(2+) ground state ((1)S0) for both Yb atoms. Magnetic susceptibility data recorded on the same compound are consistent with a nonmagnetic divalent Yb(2+) state. Temperature-dependent heat capacity data display a metallic behavior characterized by a small Sommerfeld constant γ = 64.8 mJ/mol·K(2) and a rather low Debye temperature ΘD = 140 K as typical for soft materials. PMID:27463217

  18. Correlation between magnon and magnetic symmetries of hexagonal RMnO3 (R = Er, Ho, Lu)

    NASA Astrophysics Data System (ADS)

    Nguyen, Thi Minh Hien; Nguyen, Thi Huyen; Chen, Xiang-Bai; Park, Yeonju; Jung, Young Mee; Lee, D.; Noh, T. W.; Cheong, Sang-Wook; Yang, In-Sang

    2016-11-01

    The correlation between the magnon scattering and the magnetic symmetries of hexagonal RMnO3 (R = Er, Ho) thin films and LuMnO3 single crystal was studied through the 2D Correlation Spectroscopy (2D COS) and Perturbation-Correlation Moving Window 2D (PCMW2D) Correlation Spectroscopy which were performed on the temperature-dependent Raman spectra of RMnO3 (R = Er, Ho, Lu). From the Raman spectra, we observed much stronger intensity and more asymmetrical magnon peak in LuMnO3 single crystal than in ErMnO3 and HoMnO3 thin films. While the ratio between magnon and phonon's linewidth of LuMnO3 and HoMnO3 display an anomalous behavior, that ratio of ErMnO3 is almost stable. The result from PCMW2D also supports these results. In addition, our 2D COS analysis showed that there are more overlap peaks in broad four-spin flipping magnon peak in LuMnO3 than that in ErMnO3 and HoMnO3. The differences of hexagonal RMnO3 (R = Er, Ho, Lu) in magnon scattering are very similar to the actual differences of the magnetic symmetries of these compounds. Therefore, we suggest that the magnon scattering of hexagonal RMnO3 is strongly correlated with the magnetic symmetries of these materials.

  19. Search for compounds of the NaBaR(BO{sub 3}){sub 2} family (R = La, Nd, Gd, and Yb) and the new NaBaYb(BO{sub 3}){sub 2} orthoborate

    SciTech Connect

    Svetlyakova, T. N. Kokh, A. E.; Kononova, N. G.; Fedorov, P. P.; Rashchenko, S. V.; Maillard, A.

    2013-01-15

    A search for compounds of the NaBaR(BO{sub 3}){sub 2} composition (where R = La{sup 3+}, Nd{sup 3+}, Gd{sup 3+}, or Yb{sup 3+}) is performed by solid state synthesis and spontaneous crystallization. A new compound, NaBaYb(BO{sub 3}){sub 2}, is found in this series. It crystallizes in space group R3{sup -} and belongs to the family of sublayer complex orthoborates with isolated BO{sub 3} groups NaBaR(BO{sub 3}){sub 2} (R = Y, Sc, and Yb). Theoretical X-ray powder diffraction patterns of NaBaY(BO{sub 3}){sub 2}, NaBaSc(BO{sub 3}){sub 2}, and NaBaYb(BO{sub 3}){sub 2} are calculated based on single-crystal data.

  20. Consequences of meta-stable (177m)Lu admixture in (177)Lu for patient dosimetry.

    PubMed

    Konijnenberg, Mark W

    2015-01-01

    Lutetium-177 ((177)Lu) is a rare earth metal in the lanthanides series which decays by beta emission with a half life of 6.647 days to three excited states and the ground state of (177)Hf. When (177)Lu is produced by neutron capture in (176)Lu, inevitably an admixture is formed of the long-lived isomer (177)mLu. As its half-life of 160.4 days is so much longer than that of (177)Lu, concerns are raised on its possible enhancement in radiation dose to the patient treated with (177)Lu-DOTA-octreotate. This report evaluates this possible enhancement of the absorbed dose, based on the published pharmacokinetic profile of (177)Lu-DOTA-octreotate and assuming an admixture of 1 kBq (177)mLu /MBq (177)Lu (0.1%).

  1. External vs. ``internal'' pressure effect on the anti-ferromagnetic superexchange energy, J, in LnBa2Cu3O6 (Ln=La,Nd,...,Lu)

    NASA Astrophysics Data System (ADS)

    Mallett, Ben; Tallon, Jeffery; Williams, Grant; Wolf, Thomas

    2012-02-01

    What causes the difference between the effect of ``internal'' pressure, as caused by ionic substitution, and external pressure on Tc^max in the cuprates [1]? Is it the density of states, the pairing boson energy scale (φB), condensation energy (which governs fluctuations), or ...? Many models of high temperature superconductivity put the energy scale of φB as the anti-ferromagnetic super-exchange energy, J, between adjacent Cu(2) ions in the CuO2 plane. We therefore investigated Raman B1g two-magnon scattering in high quality LnBa2Cu3O6 (Ln123) single crystals, Ln(=La, Nd, Sm, Eu, Gd, Dy, Yb, Lu), at ambient pressure to determine the effect of internal pressure on J. Comparing with measurements of J under external pressure reveals that internal and external pressure have quantitatively the same effect on J. However, and most surprisingly, we find an anticorrelation between J and Tc^max when ion size or internal pressure is the implicit variable. Given the opposite effects of internal and external pressure on Tc^max, this result suggests that some energy scale other than short range anti-ferromagnetic interactions has a more dominant effect on Tc^max.[4pt] [1] e.g. M. Marezio, Physica C, 341-348, 375 (2000)

  2. NIR emission from Yb3+-Er3+ ions in Y2Sn2O7 host

    NASA Astrophysics Data System (ADS)

    Nigam, Sandeep; Sarkar, Kaustabh; Prasad, A. I.; Sudarsan, V.; Vatsa, R. K.

    2015-06-01

    Er and Yb-Er co-doped Y2Sn2O7 both in the bulk and nano-size dimensions were prepared via co-precipitation method and investigated for their photoluminescence properties. Characteristic near Infra-Red (NIR) emission at 1530 nm due to4I13/2→4I15/2 transition of Er3+ was observed in both bulk and nanoparticles of Er doped as well as Yb-Er co-doped Y2Sn2O7. Intensity of emission improves systematically with increase in heat treatment temperature and the bulk sample show improved luminescence with crystal field splitting. Co-doping Y2Sn2O7: Er with Yb3+ ions enhances the NIR emission intensity from Er3+ ion, which is attributed to energy transfer. Excitation spectra also revealed the back energy transfer from Er3+ to Yb3+ ion.

  3. Uniform and well-dispersed YbVO4 hierarchical nanoarchitectures: synthesis and luminescence properties.

    PubMed

    Xu, Zhenhe; Zhao, Qian; Liu, Tao; Wang, Liming; Bian, Shasha

    2013-01-01

    The YbVO4 micro-doughnuts were successfully fabricated by a facile hydrothermal method. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR) spectra, scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), and photoluminescence (PL) were used to characterize the resulting samples. The diameter and thickness of YbVO4 micro-doughnuts are around 750 nm and 480 nm, respectively. It is found that trisodium citrate (Na3Cit) is essential for obtaining YbVO4 microdoughnuts. Moreover, the crystal growth process was thoroughly discussed through a series of time-dependent experiments and a possible formation mechanism was proposed. Furthermore, the up-conversion (UC) luminescent properties as well as the emission mechanisms of YbVO4:Ln3+ (Ln3+ = Er3+, Tm3+ and Ho3+) microcrystals were systematically investigated.

  4. High Pressure Measurements of the Resistivity of β-YbAlB4

    NASA Astrophysics Data System (ADS)

    Tomita, T.; Kuga, K.; Uwatoko, Y.; Nakatsuji, S.

    2015-03-01

    The electric resistivity ρ(T) under hydrostatic pressure up to 8 GPa was measured above 2 K using a high-quality single crystal of the Yb-based heavy fermion system β-YbAlB4. We found pressure-induced magnetic ordering above the critical pressure Pc ≈ 2.4 GPa. This phase transition temperature TM is enhanced with pressure and reaches 30 K at a pressure of 8 GPa, which is the highest transition temperature for the Yb-based heavy fermion compounds. In contrast, the resistivity is insensitive to pressure below Pc and exhibits the T-linear behavior in the temperature range between 2 and 20 K. Our results indicate that quantum criticality for β-YbAlB4 is also located near Pc in addition to the ambient pressure.

  5. Polymorphism, phase transitions, and thermal expansion of K3Lu(PO4)2

    SciTech Connect

    Farmer, James Matthew; Boatner, Lynn A; Chakoumakos, Bryan C; Rawn, Claudia J.; Mandrus, D.; Bryan, Jeff C.

    2014-01-01

    Alkali rare-earth double phosphates have been studied for use as long-wavelength scintillators for -ray detection using Si photodiodes. Single-crystal and powder x-ray diffraction (XRD) and powder neutron diffraction have been used to study the structure as a function of temperature. K3Lu(PO4)2 crystallizes with a hexagonal unit cell at room temperature, space group P 3. The Lu ion is six-coordinated to the oxygen atoms of the phosphate groups. Two lower-temperature phases were characterized using single-crystal XRD and powder neutron diffraction. The first transition occurs at 230 K with a transformation to a monoclinic P21/m space group symmetry, and the Lu retains six coordination. The second phase transition occurs at 130 K, with a large change in the cell volume, keeping the same P21/m space group symmetry; however, one of the phosphate groups rotates to increase the coordination of the Lu ion to seven. This is an unusual example of an isosymmetric phase transition with a coordination change, driven by temperature. High-temperature powder neutron diffraction and high-temperature powder XRD have been used to study the thermal expansion of K3Lu(PO4)2 and indicate a large thermal expansion anisotropy. The crystallographic axes with largest changes account for the structural collapse, which rotates the phosphate group to increase the Lu coordination. The lowest temperature form of K3Lu(PO4)2 is the same as the room temperature form for all the lighter RE compounds of the same type, which is not surprising, given the lighter (larger) RE ions would prefer a higher coordination number.

  6. Cyclic MAM synthesis of SPION/BaMoO4:Er3+,Yb3+ composite and its optical properties

    NASA Astrophysics Data System (ADS)

    Lim, C. S.; Atuchin, V. V.

    2013-05-01

    Er3+/Yb3+ co-doped BaMoO4 (BaMoO4:Er3+/Yb3+) composites with superparamagnetic iron oxide nanoparticles (SPIONs) incorporated were successfully synthesized by a cyclic microwave-assisted metathetic (MAM) method followed by heat-treatment. The microstructure exhibited well-defined and homogeneous morphology with the BaMoO4:Er3+/Yb3+ particle size of 1-2 μm and Fe3O4 particle size of 0.1-0.5 μm. The Fe3O4 particles were self-preferentially crystallized and immobilized on the surface of BaMoO4:Er3+/Yb3+ particles. The synthesized SPION/BaMoO4:Er3+,Yb3+ composites were characterized by X-ray diffraction, scanning electron microscopy and energy-dispersive X-ray spectroscopy. Optical properties were examined using photoluminescence emission measurements and Raman spectroscopy.

  7. Rare earth metal-rich indides RE14Rh 3-xIn 3 ( RE=Y, Dy, Ho, Er, Tm, Lu)

    NASA Astrophysics Data System (ADS)

    Zaremba, Roman; Pöttgen, Rainer

    2007-09-01

    The rare earth ( RE) metal-rich indides RE14Rh 3-xIn 3 ( RE=Y, Dy, Ho, Er, Tm, Lu) can be synthesized from the elements by arc-melting or induction melting in tantalum crucibles. They were investigated by X-ray diffraction on powders and single crystals: Lu 14Co 3In 3 type, space group P4 2/ nmc, Z=4, a=961.7(1), c=2335.5(5) pm, w R2=0.052, 2047 F2 values, 62 variables for Y 14Rh 3In 3, a=956.8(1), c=2322.5(5) pm, w R2=0.068, 1730 F2 values, 63 variables for Dy 14Rh 2.89(1)In 3, a=952.4(1), c=2309.2(5) pm, w R2=0.041, 1706 F2 values, 63 variables for Ho 14Rh 2.85(1)In 3, a=948.6(1), c=2302.8(5) pm, w R2=0.053, 1977 F2 values, 63 variables for Er 14Rh 2.86(1)In 3, a=943.8(1), c=2291.5(5) pm, w R2=0.065, 1936 F2 values, 63 variables for Tm 14Rh 2.89(1)In 3, and a=937.8(1), c=2276.5(5) pm, w R2=0.050, 1637 F2 values, 63 variables for Lu 14Rh 2.74(1)In 3. Except Yb 14Rh 3In 3, the 8 g Rh1 sites show small defects. Striking structural motifs are rhodium-centered trigonal prisms formed by the RE atoms with comparatively short Rh- RE distances (271-284 pm in Y 14Rh 3In 3). These prisms are condensed via common corners and edges building two-dimensional polyhedral units. Both crystallographically independent indium sites show distorted icosahedral coordination. The icosahedra around In2 are interpenetrating, leading to In2-In2 pairs (309 pm in Y 14Rh 3In 3).

  8. Nine members of a family of nine-membered cyclic coordination clusters; Fe6Ln3 wheels (Ln = Gd to Lu and Y).

    PubMed

    Kühne, Irina A; Mereacre, Valeriu; Anson, Christopher E; Powell, Annie K

    2016-01-18

    We report a family of isostructural nonanuclear Fe(III)-Ln(III) cyclic coordination clusters [Fe(III)(6)Ln(III)(3)(μ-OMe)9(vanox)6(benz)6]. (Ln = Tb (1), Dy (2), Ho (3), Er (4), Tm (5), Yb (6), Lu (7), Y (8) and Gd (9)), containing an odd number of metal ions. The planar cyclic coordination cluster cores are built up from three [Fe2Ln] subunits.

  9. A diagonally inverted LU implicit multigrid scheme

    NASA Technical Reports Server (NTRS)

    Yokota, Jeffrey W.; Caughey, David A.; Chima, Rodrick V.

    1988-01-01

    A new Diagonally Inverted LU Implicit scheme is developed within the framework of the multigrid method for the 3-D unsteady Euler equations. The matrix systems that are to be inverted in the LU scheme are treated by local diagonalizing transformations that decouple them into systems of scalar equations. Unlike the Diagonalized ADI method, the time accuracy of the LU scheme is not reduced since the diagonalization procedure does not destroy time conservation. Even more importantly, this diagonalization significantly reduces the computational effort required to solve the LU approximation and therefore transforms it into a more efficient method of numerically solving the 3-D Euler equations.

  10. Syntheses, Structure, Magnetism, and Optical Properties of the Ordered Interlanthanide Copper Chalcogenides Ln{sub 2}YbCuQ{sub 5} (Ln = La, Ce, Pr, Nd, Sm; Q = S, Se): Evidence for Unusual Magnetic Ordering in Sm{sub 2}YbCuS{sub 5}

    SciTech Connect

    Jin, Geng Bang; Choi, Eun Sang; Guertin, Robert P.; Booth, Corwin H.; Albrecht-Schmitt, Thomas E.

    2010-11-19

    Ln{sub 2}YbCuQ{sub 5} (Ln = La, Ce, Pr, Nd, Sm; Q = S, Se) have been prepared by direct reaction of the elements in Sb{sub 2}Q{sub 3} (Q = S, Se) fluxes at 900 °C. All compounds have been characterized by single-crystal X-ray diffraction methods and they are isotypic. The structure of Ln{sub 2}YbCuQ{sub 5} consists of one-dimensional {sup 1}{sub {infinity}} [YbCuQ{sub 5}]{sup 6-} ribbons extending along the b axis that are connected by larger Ln{sup 3+} ions. Each ribbon is constructed from two single chains of [YbQ{sub 6}] octahedra with one double chain of [CuQ{sub 5}] trigonal bipyramids in the middle. All three chains connect with each other via edge-sharing. There are two crystallographically unique Ln atoms, one octahedral Yb site, and two disordered Cu positions inside of distorted Q{sub 5} trigonal bipyramids. Both Ln atoms are surrounded by eight Q atoms in bicapped trigonal prisms. The magnetic properties of Ln{sub 2}YbCuQ{sub 5} have been characterized using magnetic susceptibility and heat capacity measurements, while their optical properties have been explored using UV-vis-NIR diffuse reflectance spectroscopy. Cesub 2}YbCuSe{sub 5}, La{sub 2}YbCuS{sub 5}, Ce{sub 2}YbCuS{sub 5}, and Pr{sub 2}YbCuS{sub 5} are Curie-Weiss paramagnets. La{sub 2}YbCuSe{sub 5} and Nd{sub 2}YbCuS{sub 5} show evidence for short-range antiferromagnetic ordering at low temperatures. Sm{sub 2}YbCuS{sub 5} shows magnetic ordering at 5.9 K, followed by negative magnetization at low external fields. The band gaps of La{sub 2}YbCuSe{sub 5}, Ce{sub 2}YbCuSe{sub 5}, La{sub 2}YbCuS{sub 5}, Ce{sub 2}YbCuS{sub 5}, Pr{sub 2}YbCuS{sub 5}, Nd{sub 2}YbCuS{sub 5},and Sm{sub 2}YbCuS{sub 5} are 1.15 eV, 1.05 eV, 1.45 eV, 1.37 eV, 1.25 eV, 1.35 eV, and 1.28 eV respectively.

  11. Fabrication of Yb-123 Tapes

    SciTech Connect

    Athur, S.; Balachandran, U.; Salama, K.

    2000-11-15

    While Bi-2223 tapes have been the workhorses of the superconductor industry, their poor performance in applied magnetic fields restrict their use to below 30 K. Melt-processing of Ag-clad Yb-123 PIT tapes offers a simple and scalable technique for fabricating long-length HTS conductors capable of being used at 77 K. Under reduced oxygen partial pressure, the peritectic temperature of Yb-123 is below the melting point of Ag, and this facilitates the adaptation of melt-texturing methods for fabricating these tapes. The effect of melt-processing temperature on current density was also explored; a temperature of 965 C yielded optimal critical current values. The critical current density achieved at 4.2 K was 20,000 A/cm{sup 2}, corresponding to a critical current of 52 A. Based on the above results, an optimal processing zone for melt-processing of Ag-clad Yb-123 tapes was determined. These results hold promise for melt-processing of Ag-clad Yb-123 tapes as an alternative to Bi-2223 PIT technology.

  12. Athermal distributed Brillouin sensors utilizing all-glass optical fibers fabricated from rare earth garnets: LuAG

    NASA Astrophysics Data System (ADS)

    Dragic, P. D.; Pamato, M. G.; Iordache, V.; Bass, J. D.; Kucera, C. J.; Jones, M.; Hawkins, T. W.; Ballato, J.

    2016-01-01

    An all-glass optical fiber derived from single-crystal LuAG is investigated for its potential use in athermal Brillouin distributed strain sensors. Such sensor systems are comprised of fiber whose Brillouin frequency shift is independent of temperature, but not independent of strain. Bulk Brillouin spectroscopy measurements on the precursor LuAG crystal are performed to gain insight into the crystal-to-glass transition. Results suggest that both the mass density and acoustic velocity are reduced relative to the crystal phase, in common with the other rare earth aluminosilicates. Advantages of the LuAG derived fiber over other rare earth garnet-derived fibers for the sensing application are a stronger strain response and larger Brilloun gain with narrower Brillouin spectral width.

  13. Effects of Sc and Y substitution on the structure and thermoelectric properties of Yb14MnSb11

    NASA Astrophysics Data System (ADS)

    Grebenkemper, Jason H.; Klemenz, Sebastian; Albert, Barbara; Bux, Sabah K.; Kauzlarich, Susan M.

    2016-10-01

    Yb14MnSb11 is the most efficient bulk p-type thermoelectric material for high temperature applications. Materials with Y and Sc substitutions in Yb14MnSb11 were made both in Sn-flux and by ball milling. These small 3+ rare earth (RE) cations were introduced with the goal of providing chemical pressure on the structure. The RE3+ cation is smaller than Yb2+ and also donates one additional electron to this p-type semiconductor. In Yb14-xRExMnSb11 (RE = Sc, Y) the maximum x was about 0.5. X-ray diffraction experiments on the single crystals obtained from Sn-flux showed that Sc preferentially substitutes for Yb(1) and Yb(3), and decreases the size of the unit cell by about 0.3%. Y substitutes on all Yb sites and increases the size of the unit cell by about 0.2%. Samples with Yb14-xRExMnSb11 (x~0.3) were prepared via powder metallurgy and spark plasma sintering for transport and thermal conductivity measurements. Electron microprobe of the Sc-substituted sample showed small regions (≤1 μ m) containing greater amounts of Sc, and X-ray powder diffraction of the ball milled Sc sample could be fitted as phase pure Yb14-xScxMnSb11. Y-substituted samples showed larger regions of excess Y in electron microprobe, and small amounts of Yb4Sb3 in X-ray powder diffraction. The Sc sample has slightly reduced carrier concentration over optimized Yb14MnSb11, while the Y samples have even lower carrier concentrations. These carrier concentrations lead to comparable resistivity to Yb14MnSb11 in the Sc-substituted material, and higher resistivities in the Y-substituted material. All materials had similar Seebeck coefficients that slightly exceed Yb14MnSb11 at high temperatures, with the Sc-substituted sample having the highest despite having a higher carrier concentration. Sc-substituted samples also had a slightly higher thermal conductivity over the Y-substituted samples, which had comparable thermal conductivity to Yb14MnSb11. The zT values of the Sc and Y substituted samples are

  14. Effect of concentration of Sm2O3 and Yb2O3 and synthesizing temperature on electrical and crystal structure of (Bi2O3)1-x-y(Sm2O3)x(Yb2O3)y electrolytes fabricated for IT-SOFCs

    NASA Astrophysics Data System (ADS)

    Kayalı, Refik; Özen, Mürivet Kaşıkcı; Bezir, Nalan Çiçek; Evcin, Atilla

    2016-05-01

    For intermediate temperature solid oxide fuel cells (IT-SOFCs), (Bi2O3)1-x-y(Sm2O3)x(Yb2O3)y ternary systems (x=0.01 and y= 0.11), (x=0.05 and y= 0.07), (x=0.07 and y=0.05), and (x=0.11 and y=0.01) as electrolytes have been fabricated at different temperatures (700, 750, and 800 °C) by solid state ceramic technique (SST). The characterization of the samples has been performed by X-ray powder diffractometer (XRD), scanning electron microscopy (SEM), four point-probe method (FPPM), X-ray energy diffraction spectroscopy (EDX), and differential thermal analysis (DTA). XRD measurements have shown that only the samples (Bi2O3)1-x-y(Sm2O3)x(Yb2O3)y (x=0.01, y=0.11 synthesized at 700, 750, and 800 °C) and (x=0.05, y=0.07 synthesized at 800 °C) have stable fluorite type face centered cubic (FCC) δ-phase. SEM images have shown the morphology of the stable samples. The conductivity and the operation temperature region of the samples have been determined from Arrhenius curves obtained from the FPPM measurements data and they vary from 1.83 to 9.95×10-1 S cm-1. Moreover, activation energy of the samples have been calculated by means of Arrhenius curves of the samples and relationships between them and the conductivity of the samples have been investigated in detail. The results obtained from XRD and FPPM measurements were confirmed by the DTA measurements.

  15. Yb(3+):BaCaBO3F: A potential new self-frequency-doubling laser material

    NASA Astrophysics Data System (ADS)

    Schaffers, K. I.; Deloach, L. D.; Ebbers, C. A.; Payne, S. A.

    1995-03-01

    Yb:BaCaBO3F (Yb:BCBF) has been investigated as a new laser crystal with potential for self-frequency-doubling. A Yb:BCBF laser has been pumped at 912 mm, and a measured slope efficiency of 38% has been obtained for the fundamental laser output at 1034 nm. Single crystal powders of BCBF have been compared with KD*P (KD2PO4) for a relative measure of the second harmonic generating potential, yielding d(sub eff)(BCBF) = (0.66)d(sub eff)(KD*P). The growth, spectroscopy, laser performance, and linear and nonlinear optical properties of Yb:BCBF are reported here.

  16. Diode pumped Yb:CN laser at 1082 nm and intracavity doubling to the green spectral range

    NASA Astrophysics Data System (ADS)

    Liu, B.; Li, Y. L.; Jiang, H. L.

    2011-08-01

    A diode pumped Yb:CaNb2O6 (Yb:CN) laser at 1082 nm with a maximum output of 1.35 W at 13.3 W pump power has been demonstrated. The slope efficiency was 12.4%. Moreover, intracavity second-harmonic generation (SHG) has also been achieved with a maximum green power of 374 mW by using a LiB3O5 (LBO) nonlinear crystal. To the best of our knowledge, this is the first report on continuous wave (CW) green generation by intracavity frequency doubling Yb:CN laser.

  17. Spectral and structural features of Lu1 - x RE x BO3 compounds

    NASA Astrophysics Data System (ADS)

    Shmurak, S. Z.; Kedrov, V. V.; Kiselev, A. P.; Fursova, T. N.; Shmyt'ko, I. M.

    2015-08-01

    The luminescence spectra, luminescence excitation spectra, IR absorption spectra, and crystal structure of orthoborates Lu1 - x RE x BO3 ( RE = Eu, Gd, Tb, Y, Dy) have been investigated. It has been found that the solid solution consisting of a LuBO3 orthoborate, which has two stable structural modifications (calcite and vaterite), and an REBO3 orthoborate, which has one structural modification (vaterite), crystallizes only in the vaterite structure when the concentration of a rare-earth ion substituting for lutetium exceeds 15-20 at %. The investigation of the photoluminescence spectra has demonstrated that, for rare-earth ions Lu3+, Eu3+, Y3+, and Gd3+ in the vaterite modification of Lu1 - x RE x BO3 orthoborates, there are at least two positions that are not equivalent in the symmetry of the local environment. It has been established that the maximum intensity of the luminescence of the vaterite modification of Lu1 - x Tb x BO3 compounds synthesized at 970°C, which is observed at a terbium concentration of 15 at %, is several times higher than the maximum intensity of the luminescence of the calcite modification.

  18. Raman and structural characterization of LuAlO{sub 3}

    SciTech Connect

    Casu, Alberto; Ricci, Pier Carlo

    2011-11-15

    The structural and vibrational properties of lutetium orthoaluminate perovskite (LuAlO{sub 3}) were investigated by means of Raman spectroscopy and EXAFS measurements. The analysis of Raman spectra taken in four different polarized configurations along the principal axes at 20 K and room temperature conditions permits to assign the principal vibrational modes in LuAP single crystals and to confirm the belonging to the D{sub 2h}{sup 16} space group. EXAFS measurements were performed at room temperature in order to obtain local structural informations on the first and next nearest neighbors around lutetium absorptions sites. Unit cell parameters and bond lengths were determined by the analysis of the EXAFS spectroscopy at the L{sub 3} absorption edge of lutetium. The informations thus gathered on this compound can offer a useful addition in the framework of a full structural characterization of LuAlO{sub 3}. - Graphical abstract: Raman active mode in LuAP crystal. Highlights: > Structural characterization of LuAlO{sub 3} is obtained by Raman and EXAFS spectroscopies. > Vibrational modes, temperature-dependent variations studied by Raman spectroscopy. > Cell parameters and local characterization obtained by EXAFS spectroscopy.

  19. 430mW diode-pumped Yb:GdCOB laser and its thermal effect

    NASA Astrophysics Data System (ADS)

    Hu, Jianghai; Song, Yanrong; Yu, Weiming; Wang, Yonggang; Zhuo, Zhuang; Zhang, Zhigang

    2006-06-01

    In this paper, we report a diode end pumped laser with a Yb 3+-doped Ca 4GdO(BO 3) 3 crystal (Yb:GdCOB). The dopant concentration of the crystal was 7%. The crystal was pumped longitudinally at 976nm by a fiber-coupled diode laser. The maximum output power of the laser emitted at 1.055um was 430mW, and the laser slope efficiency was 75% with respect to the absorbed pump power. We also observed that the output power still increased when the crystal no longer absorbed more pumped power (the crystal had been saturated). The possible reason may be that the thermal lens effect changed the distribution of the laser mode. This will be discussed in part 3.

  20. SuperLU users' guide

    SciTech Connect

    Demmel, James W.; Gilbert, John R.; Li, Xiaoye S.

    1999-11-01

    This document describes a collection of three related ANSI C subroutine libraries for solving sparse linear systems of equations AX = B: Here A is a square, nonsingular, n x n sparse matrix, and X and B are dense n x nrhs matrices, where nrhs is the number of right-hand sides and solution vectors. Matrix A need not be symmetric or definite; indeed, SuperLU is particularly appropriate for matrices with very unsymmetric structure. All three libraries use variations of Gaussian elimination optimized to take advantage both of sparsity and the computer architecture, in particular memory hierarchies (caches) and parallelism.

  1. Recent advancements in transparent ceramics and crystal fibers for high power lasers

    NASA Astrophysics Data System (ADS)

    Kim, W.; Baker, C.; Villalobos, G.; Florea, C.; Gibson, D.; Shaw, L. B.; Bowman, S.; Bayya, S.; Sadowski, B.; Hunt, M.; Askins, C.; Peele, J.; Aggarwal, I. D.; Sanghera, J. S.

    2013-05-01

    In this paper, we present our recent progress in the development of rare-earth (Yb3+ or Ho3+) doped Lu2O3 and Y2O3 sesquioxides for high power solid state lasers. We have fabricated high quality transparent ceramics using nano-powders synthesized by a co-precipitation method. This was accomplished by developments in high purity powder synthesis and low temperature scalable sintering technology developed at NRL. The optical, spectral and morphological properties as well as the lasing performance from our highly transparent ceramics are presented. In the second part of the paper, we discuss our recent research effort in developing cladded-single crystal fibers for high power single frequency fiber lasers has the potential to significantly exceed the capabilities of existing silica fiber based lasers. Single crystal fiber cores with diameters as small as 35μm have been drawn using high purity rare earth doped ceramic or single crystal feed rods by the Laser Heated Pedestal Growth (LHPG) process. Our recent results on the development of suitable claddings on the crystal fiber core are discussed.

  2. Growth of LGSO: Ce crystals by the Czochralski method

    SciTech Connect

    Sidletskiy, O. Ts.; Bondar, V. G. Grynyov, B. V.; Kurtsev, D. A.; Baumer, V. N.; Belikov, K. N.; Shtitelman, Z. V.; Tkachenko, S. A.; Zelenskaya, O. V.; Starzhinsky, N. G.; Tarasov, V. A.

    2009-12-15

    Single crystals of Lu{sub 2x}Gd{sub 2-2x}SiO{sub 5}: Ce (0 < x < 1) compounds with different atomic ratios Lu/(Lu + Gd) have been grown by the Czochralski method. It has been shown that a change in the spatial symmetry from P2{sub 1}/c to C2/c in the course of substitution of lutetium for gadolinium occurs at the ratio Lu/(Lu + Gd) = 0.1. The lattice thus formed with symmetry C2/c in the structure of Lu{sub 2x}Gd{sub 2-2x}SiO{sub 5}: Ce crystals favors the maximum possible incorporation of Ce{sup 3+} ions into the sevenfold-coordinated position with respect to oxygen. This explains the substantial improvement of the scintillation characteristics of the grown crystals.

  3. Continuous wave and tunable laser operation of Yb3+ in disordered NaLa(MoO4)2

    NASA Astrophysics Data System (ADS)

    Rico, M.; Liu, J.; Cano-Torres, J. M.; García-Cortés, A.; Cascales, C.; Zaldo, C.; Griebner, U.; Petrov, V.

    2005-09-01

    Continuous-wave Yb3+ laser operation is studied in single crystals of disordered NaLa(MoO4)2 at room temperature. The sample used was grown by the Czochralski technique and incorporates an Yb ion density of 3.1×1020 cm-3. The effect of the Yb concentration on some of the crystal properties is described as well as the spectroscopic Yb3+ properties at 5 K. Maximum slope efficiencies of about 40% for π and 38% for σ polarization were obtained under Ti:sapphire laser pumping near 976 nm, respectively. The maximum output power for the π polarization was 400 mW at 1039.5 nm, the threshold in this case amounted to 240 mW (absorbed pump power). The laser emission was tunable between 1016 and 1064 nm with a Lyot filter. Lasing was also realized by pumping with a fiber-coupled diode laser module. Maximum output power of 900 mW at 1035 nm was achieved in this case for the π polarization and the threshold was 280 mW. The results, in terms of output power and tunability, are superior in comparison to all previous reports on Yb-doped disordered double tungstate or molybdate crystals and represent a significant improvement in comparison to earlier experiments with low-doped Yb:NaLa(MoO4)2.

  4. Gapless quantum excitations from an icelike splayed ferromagnetic ground state in stoichiometric Yb2Ti2O7

    DOE PAGESBeta

    Gaudet, J.; Ross, K. A.; Kermarrec, E.; Butch, N. P.; Ehlers, G.; Dabkowska, H. A.; Gaulin, B. D.

    2016-02-03

    We know the ground state of the quantum spin ice candidate magnet Yb2Ti2O7 to be sensitive to weak disorder at the similar to 1% level which occurs in single crystals grown from the melt. Powders produced by solid state synthesis tend to be stoichiometric and display large and sharp heat capacity anomalies at relatively high temperatures, T-C similar to 0.26 K. We have carried out neutron elastic and inelastic measurements on well characterized and equilibrated stoichiometric powder samples of Yb2Ti2O7 which show resolution-limited Bragg peaks to appear at low temperatures, but whose onset correlates with temperatures much higher than T-C.more » The corresponding magnetic structure is best described as an icelike splayed ferromagnet. In the spin dynamics of Yb2Ti2O7 we see the gapless on an energy scale <0.09 meV at all temperatures and organized into a continuum of scattering with vestiges of highly overdamped ferromagnetic spin waves present. These excitations differ greatly from conventional spin waves predicted for Yb2Ti2O7's mean field ordered state, but appear robust to weak disorder as they are largely consistent with those displayed by nonstoichiometric crushed single crystals and single crystals, as well as by powder samples of Yb2Ti2O7's sister quantum magnet Yb2Ti2O7.« less

  5. Gapless quantum excitations from an icelike splayed ferromagnetic ground state in stoichiometric Yb2Ti2O7

    NASA Astrophysics Data System (ADS)

    Gaudet, J.; Ross, K. A.; Kermarrec, E.; Butch, N. P.; Ehlers, G.; Dabkowska, H. A.; Gaulin, B. D.

    2016-02-01

    The ground state of the quantum spin ice candidate magnet Yb2Ti2O7 is known to be sensitive to weak disorder at the ˜1 % level which occurs in single crystals grown from the melt. Powders produced by solid state synthesis tend to be stoichiometric and display large and sharp heat capacity anomalies at relatively high temperatures, TC˜0.26 K. We have carried out neutron elastic and inelastic measurements on well characterized and equilibrated stoichiometric powder samples of Yb2Ti2O7 which show resolution-limited Bragg peaks to appear at low temperatures, but whose onset correlates with temperatures much higher than TC. The corresponding magnetic structure is best described as an icelike splayed ferromagnet. The spin dynamics in Yb2Ti2O7 are shown to be gapless on an energy scale <0.09 meV at all temperatures and organized into a continuum of scattering with vestiges of highly overdamped ferromagnetic spin waves present. These excitations differ greatly from conventional spin waves predicted for Yb2Ti2O7 's mean field ordered state, but appear robust to weak disorder as they are largely consistent with those displayed by nonstoichiometric crushed single crystals and single crystals, as well as by powder samples of Yb2Ti2O7 's sister quantum magnet Yb2Sn2O7 .

  6. Theory of low energy excitations in resonant inelastic x-ray scattering for rare-earth systems: Yb compounds as typical examples

    NASA Astrophysics Data System (ADS)

    Kotani, A.

    2011-04-01

    Theoretical predictions are given for low energy excitations, such as crystal field excitations and Kondo resonance excitations, to be detected by high-resolution measurements of resonant inelastic x-ray scattering (RIXS) of rare-earth materials with Yb compounds as typical examples. Crystal field excitations in the Yb 3d RIXS of a Yb3+ ion in the cubic crystal field are formulated, and the calculation of RIXS spectra for YbN is done. Kondo resonance excitations revealed in the Yb 3d RIXS spectra are calculated for mixed-valence Yb compounds, Yb1-xLuxAl3, in the leading term approximation of the 1/Nf expansion method with a single impurity Anderson model. It is emphasized that the high-resolution RIXS with polarization dependence is a powerful tool to study the crystal field levels together with their symmetry and also the Kondo bound state in rare-earth compounds. Some in-depth discussions are given on the polarization effects of RIXS, including 4d and 2p RIXS spectra, the coherence effect of the Kondo bound states, and the importance of the high-resolution RIXS spectra for condensed matter physics under extreme conditions.

  7. Neutron spectroscopic study of crystalline electric field excitations in stoichiometric and lightly stuffed Yb2Ti2O7

    DOE PAGESBeta

    Gaudet, J.; Maharaj, D. D.; Sala, G.; Kermarrec, E.; Ross, K. A.; Dabkowska, H. A.; Kolesnikov, A. I.; Granroth, G. E.; Gaulin, B. D.

    2015-10-27

    Time-of-flight neutron spectroscopy has been used to determine the crystalline electric field Hamiltonian, eigenvalues and eigenvectors appropriate to the J=7/2 Yb3+ ion in the candidate quantum spin ice pyrochlore magnet Yb2Ti2O7. The precise ground state of this exotic, geometrically frustrated magnet is known to be sensitive to weak disorder associated with the growth of single crystals from the melt. Such materials display weak “stuffing,” wherein a small proportion, approximately 2%, of the nonmagnetic Ti4+ sites are occupied by excess Yb3+. We have carried out neutron spectroscopic measurements on a stoichiometric powder sample of Yb2Ti2O7, as well as a crushed singlemore » crystal with weak stuffing and an approximate composition of Yb2+xTi2–xO7+y with x = 0.046. All samples display three crystalline electric field transitions out of the ground state, and the ground state doublet itself is identified as primarily composed of mJ = ±1/2, as expected. However, stuffing at low temperatures in Yb2+xTi2–xO7+y induces a similar finite crystalline electric field lifetime as is induced in stoichiometric Yb2Ti2O7 by elevated temperature. In conclusion, an extended strain field exists about each local “stuffed” site, which produces a distribution of random crystalline electric field environments in the lightly stuffed Yb2+xTi2–xO7+y, in addition to producing a small fraction of Yb ions in defective environments with grossly different crystalline electric field eigenvalues and eigenvectors.« less

  8. Neutron spectroscopic study of crystalline electric field excitations in stoichiometric and lightly stuffed Yb2Ti2O7

    NASA Astrophysics Data System (ADS)

    Gaudet, J.; Maharaj, D. D.; Sala, G.; Kermarrec, E.; Ross, K. A.; Dabkowska, H. A.; Kolesnikov, A. I.; Granroth, G. E.; Gaulin, B. D.

    2015-10-01

    Time-of-flight neutron spectroscopy has been used to determine the crystalline electric field (CEF) Hamiltonian, eigenvalues and eigenvectors appropriate to the J =7 /2 Yb3 + ion in the candidate quantum spin ice pyrochlore magnet Yb2Ti2O7 . The precise ground state (GS) of this exotic, geometrically frustrated magnet is known to be sensitive to weak disorder associated with the growth of single crystals from the melt. Such materials display weak "stuffing," wherein a small proportion, ≈2 % , of the nonmagnetic Ti4 + sites are occupied by excess Yb3 +. We have carried out neutron spectroscopic measurements on a stoichiometric powder sample of Yb2Ti2O7 , as well as a crushed single crystal with weak stuffing and an approximate composition of Yb2 +xTi2 -xO7 +y with x =0.046 . All samples display three CEF transitions out of the GS, and the GS doublet itself is identified as primarily composed of mJ=±1 /2 , as expected. However, stuffing at low temperatures in Yb2 +xTi2 -xO7 +y induces a similar finite CEF lifetime as is induced in stoichiometric Yb2Ti2O7 by elevated temperature. We conclude that an extended strain field exists about each local "stuffed" site, which produces a distribution of random CEF environments in the lightly stuffed Yb2 +xTi2 -xO7 +y , in addition to producing a small fraction of Yb ions in defective environments with grossly different CEF eigenvalues and eigenvectors.

  9. Feasibility study of CaSO4:Tb,Yb as a thermoluminescent dosimeter

    NASA Astrophysics Data System (ADS)

    Junot, Danilo O.; Santos, Max A.; Chagas, Marcos A. P.; Couto dos Santos, Marcos A.; Nunes, Luiz A. O.; Souza, Divanizia N.

    2014-02-01

    A new composite based on CaSO4, using terbium as dopant and ytterbium as co-dopant (CaSO4:Tb,Yb), was developed for employment as a thermoluminescent (TL) dosimeter. The crystals used in this work were grown using a production route based on the Yamashita method (Yamashita et al., 1968). Crystal powder was calcined at 600 °C for 1 h. Pellets were made by adding commercial and colorless glass to improve physical resistance and sintered at 700 °C for 6 h. All samples were irradiated by a beta source (90Sr/90Y) and received doses from 1 Gy to 5 Gy. TL analyses have been performed and characteristics such as sensitivity, reproducibility, linearity, and fading have been studied. The CaSO4:Tb,Yb pellets glow curves presented two peaks, the first at around 115 °C, and the second at around 200 °C. The highest intensity was shown for CaSO4:Tb,Yb with a concentration of 0.1 mol% of Tb and Yb together. In all the samples the TL response was proportional to the absorbed dose. Therefore, the CaSO4:Tb,Yb has potential to be used as a thermoluminescent dosimeter.

  10. Structural and dielectric properties of the lutetium (Lu) and yttrium (Y) doped nickel ferrite

    SciTech Connect

    Ugendar, Kodam Markandeyulu, G.

    2014-04-24

    The structural and dielectric characteristics of NiFe{sub 1.925}R{sub 0.075}O{sub 4} (R=Lu,Y) were investigated. The material crystallize in the cubic inverse spinel phase with a very small amount of RFeO{sub 3} (R=Lu,Y) as the additional phase. Frequency variation of the dielectric constant shows the dispersion that can be modeled with a modified Debye's function, which considers the possibility of more than one ion, contributing to the relaxation. Impedance spectroscopic analysis indicates the different relaxation mechanisms, bulk grain and grain-boundary contributions to the electrical conductivity and capacitance of these materials.

  11. Three-dimensional magnetic correlations in multiferroic LuFe2O4

    SciTech Connect

    Christianson, Andrew D; Lumsden, Mark D; Angst, Manuel; Yamani, Z.; Tian, Wei; Jin, Rongying; Payzant, E Andrew; Nagler, Stephen E; Sales, Brian C; Mandrus, David

    2008-01-01

    We present single crystal neutron diffraction measurements on multiferroic LuFe{sub 2}O{sub 4}. Magnetic reflections are observed below transitions at 240 and 175 K indicating that the magnetic interactions in LuFe{sub 2}O{sub 4} are three-dimensional in character. The magnetic structure is refined as a ferrimagnetic spin configuration below the 240 K transition. Below 175 K a significant broadening of the magnetic peaks is observed along with the buildup of a diffuse component to the magnetic scattering.

  12. 1.21 W passively mode-locked Tm:LuAG laser.

    PubMed

    Feng, T; Yang, K; Zhao, J; Zhao, S; Qiao, W; Li, T; Dekorsy, T; He, J; Zheng, L; Wang, Q; Xu, X; Su, L; Xu, J

    2015-05-01

    A watt-level output passively mode-locked Tm:LuAG bulk laser with an InGaAs semiconductor saturable absorber mirror (SESAM) is demonstrated for the first time. A maximum average output power of 1.21 W at 2022.9 nm has been achieved with a pulse duration of 38 ps and a repetition rate of 129.2 MHz. The results indicate the potential of Tm:LuAG crystals as candidate for realizing high power ultrafast lasers at 2 μm. PMID:25969273

  13. Surface and electronic structure of epitaxial PtLuSb (001) thin films

    SciTech Connect

    Patel, Sahil J.; Kawasaki, Jason K.; Logan, John; Schultz, Brian D.; Adell, J.; Thiagarajan, B.; Mikkelsen, A.; Palmstrøm, Chris J.

    2014-05-19

    The surface and electronic structure of single crystal thin films of PtLuSb (001) grown by molecular beam epitaxy were studied. Scanning tunneling spectroscopy (STS), photoemission spectroscopy, and temperature dependent Hall measurements of PtLuSb thin films are consistent with a zero-gap semiconductor or semi-metal. STS and photoemission measurements show a decrease in density of states approaching the Fermi level for both valence and conduction bands as well as a slight shift of the Fermi level position into the valence band. Temperature dependent Hall measurements also corroborate the Fermi level position by measurement of p-type carriers.

  14. Optical refrigeration of Yb3+:YAG nanocrystals

    NASA Astrophysics Data System (ADS)

    Nemova, Galina; Kashyap, Raman

    2015-03-01

    We have theoretically investigated the laser cooling process in Yb3+:YAG nanocrystals. We have developed an approach, which permits not only estimate the cooling process in Yb3+:YAG nanocrystals but compare this process with the laser cooling of the Yb3+:YAG bulk samples. The temperature dependences of all parameters of the system are taken into account. The cooperative effects such as re-absorption, the energy migration and cooperative luminescence have been considered.

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

    SciTech Connect

    Ahn, Kyunghan

    2007-01-01

    The family of R5SixGe4-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, R5SixGe4-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 R5SixGe4-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 R5SixGe4-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 Yb5SixGe4-xand Sm5SixGe4-x pseudobinary systems, which may exhibit mixed valence states. The crystallography, phase relationships, and physical properties of Yb5SixGe4-x alloys with 0 ≤ x ≤ 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 R5SixGe4-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 Gd5Si4-type structure. The magnetic properties of Yb5SixGe4-x materials are nearly composition

  16. Synthesis, crystal structure and properties of Mg{sub 3}B{sub 36}Si{sub 9}C and related rare earth compounds RE{sub 3−x}B{sub 36}Si{sub 9}C (RE=Y, Gd–Lu)

    SciTech Connect

    Ludwig, Thilo; Pediaditakis, Alexis; Sagawe, Vanessa; Hillebrecht, Harald

    2013-08-15

    We report on the synthesis and characterisation of Mg{sub 3}B{sub 36}Si{sub 9}C. Black single crystals of hexagonal shape were yielded from the elements at 1600 °C in h-BN crucibles welded in Ta ampoules. The crystal structure (space group R3{sup ¯}m, a=10.0793(13) Å, c=16.372(3) Å, 660 refl., 51 param., R{sub 1}(F)=0.019; wR{sub 2}(F{sup 2})=0.051) is characterized by a Kagome-net of B{sub 12} icosahedra, ethane like Si{sub 8}-units and disordered SiC-dumbbells. Vibrational spectra show typical features of boron-rich borides and Zintl phases. Mg{sub 3}B{sub 36}Si{sub 9}C is stable against HF/HNO{sub 3} and conc. NaOH. The micro-hardness is 17.0 GPa (Vickers) and 14.5 GPa (Knoop), respectively. According to simple electron counting rules Mg{sub 3}B{sub 36}Si{sub 9}C is an electron precise compound. Band structure calculations reveal a band gap of 1.0 eV in agreement to the black colour. Interatomic distances obtained from the refinement of X-ray data are biased and falsified by the disorder of the SiC-dumbbell. The most evident structural parameters were obtained by relaxation calculation. Composition and carbon content were confirmed by WDX measurements. The small but significant carbon content is necessary by structural reasons and frequently caused by contaminations. The rare earth compounds RE{sub 3−x}B{sub 36}Si{sub 9}C (RE=Y, Dy–Lu) are isotypic. Single crystals were grown from a silicon melt and their structures refined. The partial occupation of the RE-sites fits to the requirements of an electron-precise composition. According to the displacement parameters a relaxation should be applied to obtain correct structural parameters. - Graphical abstract: Single crystals of the new boridesilicide Mg{sub 3}B{sub 36}Si{sub 9}C were obtained from the elements in a Si-melt. Besides B{sub 12}-icosahedra and ethan-like Si{sub 8}-units it contains a disordered SiC-dumbbell. Correct distances were obtained by relaxation calculation based on the X-ray data

  17. jShyLU Scalable Hybrid Preconditioner and Solver

    2012-09-11

    ShyLU is numerical software to solve sparse linear systems of equations. ShyLU uses a hybrid direct-iterative Schur complement method, and may be used either as a preconditioner or as a solver. ShyLU is parallel and optimized for a single compute Solver node. ShyLU will be a package in the Trilinos software framework.

  18. In situ dissolution or deposition of Ytterbium (Yb) metal in microhotplate wells for a miniaturized atomic clock.

    PubMed

    Manginell, Ronald P; Moorman, Matthew W; Anderson, John M; Burns, George R; Achyuthan, Komandoor E; Wheeler, David R; Schwindt, Peter D D

    2012-10-22

    Current atomic clocks are burdened by size, weight, power and portability limitations to satisfy a broad range of potential applications. One critical need in the fabrication of a miniaturized atomic clock is small, low-power metallic sources. Exploiting the relatively high vapor pressure of ytterbium (Yb) and its dissolution in anhydrous ammonia, we report two independent techniques for depositing Yb inside a well micromachined into a microhotplate. Subsequent in situ evaporation of Yb from the microhotplate well serves as a low-power metallic source suitable for atomic clocks. The deposition and evaporation of Yb were confirmed using a variety of physicochemical techniques including quartz crystal microbalance, scanning electron microscopy, energy dispersive X-ray spectroscopy, and laser fluorescence. We also describe the fabrication of the microhotplate device, an integral component of our Yb-based miniature atomic clock. The Yb deposition/evaporation on a microhotplate well is thus useful as a low power Yb source during the fabrication of a miniaturized atomic clock, and this technique could be used for other applications requiring a vapor of a metal that has a moderate vapor pressure.

  19. In situ dissolution or deposition of Ytterbium (Yb) metal in microhotplate wells for a miniaturized atomic clock.

    PubMed

    Manginell, Ronald P; Moorman, Matthew W; Anderson, John M; Burns, George R; Achyuthan, Komandoor E; Wheeler, David R; Schwindt, Peter D D

    2012-10-22

    Current atomic clocks are burdened by size, weight, power and portability limitations to satisfy a broad range of potential applications. One critical need in the fabrication of a miniaturized atomic clock is small, low-power metallic sources. Exploiting the relatively high vapor pressure of ytterbium (Yb) and its dissolution in anhydrous ammonia, we report two independent techniques for depositing Yb inside a well micromachined into a microhotplate. Subsequent in situ evaporation of Yb from the microhotplate well serves as a low-power metallic source suitable for atomic clocks. The deposition and evaporation of Yb were confirmed using a variety of physicochemical techniques including quartz crystal microbalance, scanning electron microscopy, energy dispersive X-ray spectroscopy, and laser fluorescence. We also describe the fabrication of the microhotplate device, an integral component of our Yb-based miniature atomic clock. The Yb deposition/evaporation on a microhotplate well is thus useful as a low power Yb source during the fabrication of a miniaturized atomic clock, and this technique could be used for other applications requiring a vapor of a metal that has a moderate vapor pressure. PMID:23187228

  20. Thermoluminescence responses of the Yb- and Yb-Tb-doped SiO2 optical fibers to 6-MV photons.

    PubMed

    Sahini, M H; Hossain, I; Wagiran, H; Saeed, M A; Ali, H

    2014-09-01

    Characteristics of the thermoluminescence (TL) responses of Yb- and Yb-Tb-doped optical fibers irradiated with 6MV photons are reported. The concentration of Yb in the Yb-doped optical fiber was 0.26mol%; the concentrations of Yb and Tb in the Yb-Tb-doped optical fiber were 0.62 and 0.2mol%, respectively. The TL dose responses are linear in the dose range 0.5-4Gy. The radiation sensitivity of the Yb-Tb material is almost two orders of magnitude higher than the sensitivity of the material doped with Yb alone.

  1. Incommensurate Magnetic Order in Ce(1-x)Yb(x)RhIn(5)

    NASA Astrophysics Data System (ADS)

    Disseler, Steven; Jang, S.; White, B. D.; Zhao, Yang; Lynn, Jeff; Maple, M. B.

    2014-03-01

    We present a detailed study of a series of Yb-doped CeRhIn5 single crystals through measurements of the bulk magnetic properties and elastic neutron scattering. We find that all samples up to x = 0.8 undergo a magnetic ordering transition below 4 K, despite observations that the Yb-valence rapidly decreases toward a non-magnetic state at high concentrations. Furthermore, we find that this magnetically ordered state is described by an incommensurate structure similar to the parent compound, and with a propagation wave vector that is weakly dependent on concentration. The authors acknowledge funding source US DOE DE-FG02-04-ER46105.

  2. Yb{sub 5}Ni{sub 4}Sn{sub 10} and Yb{sub 7}Ni{sub 4}Sn{sub 13}: New polar intermetallics with 3D framework structures

    SciTech Connect

    Lei Xiaowu; Sun Zhongming; Li Longhua; Zhong Guohua; Hu Chunli; Mao Jianggao

    2010-04-15

    The title compounds have been obtained by solid state reactions of the corresponding pure elements at high temperature, and structurally characterized by single-crystal X-ray diffraction studies. Yb{sub 5}Ni{sub 4}Sn{sub 10} adopts the Sc{sub 5}Co{sub 4}Si{sub 10} structure type and crystallizes in the tetragonal space group P4/mbm (No. 127) with cell parameters of a=13.785(4) A, c=4.492 (2) A, V=853.7(5) A{sup 3}, and Z=2. Yb{sub 7}Ni{sub 4}Sn{sub 13} is isostructural with Yb{sub 7}Co{sub 4}InGe{sub 12} and crystallizes in the tetragonal space group P4/m (No. 83) with cell parameters of a=11.1429(6) A, c=4.5318(4) A, V=562.69(7) A{sup 3}, and Z=1. Both structures feature three-dimensional (3D) frameworks based on three different types of one-dimensional (1D) channels, which are occupied by the Yb atoms. Electronic structure calculations based on density functional theory (DFT) indicate that both compounds are metallic. These results are in agreement with those from temperature-dependent resistivity and magnetic susceptibility measurements. - Graphical abstract: Two new ytterbium nickel stannides, namely, Yb{sub 5}Ni{sub 4}Sn{sub 10} and Yb{sub 7}Ni{sub 4}Sn{sub 13}, have been synthesized and structurally characterized by single-crystal X-ray diffraction studies. Both their structures feature three-dimensional (3D) frameworks based on three different types of one-dimensional (1D) channels, which are situated by all the Yb atoms. Electronic structure calculations based on density functional theory (DFT) indicate that both compounds are metallic, which are in accordance with the results from temperature-dependent resistivity and magnetic susceptibility measurements.

  3. THE LU ISOTOPIC COMPOSITION OF ACHONDRITES: CLOSING THE CASE FOR ACCELERATED DECAY OF {sup 176}LU

    SciTech Connect

    Wimpenny, Josh; Yin, Qing-zhu; Amelin, Yuri

    2015-10-10

    Studies of Lu–Hf isotope systematics in meteorites have produced apparent “ages” that are older than Pb–Pb ages and older than the estimated age of our solar system. One proposed explanation for this discrepancy is that irradiation by cosmic rays caused excitation of {sup 176}Lu to its short-lived isomer that then underwent rapid decay to {sup 176}Hf. This explanation can account for apparent excesses in {sup 176}Hf that correlate with Lu/Hf ratio. Mass balance requires that samples with measurable excess in {sup 176}Hf should also have measurable deficiencies in {sup 176}Lu on the order of 1‰–3‰. To unambiguously test the accelerated decay hypothesis, we have measured the {sup 176}Lu/{sup 175}Lu ratio in terrestrial materials and achondrites to search for evidence of depletion in {sup 176}Lu. To a precision of 0.1‰ terrestrial standards, cumulate and basaltic eucrites and angrites all have the same {sup 176}Lu/{sup 175}Lu ratio. Barring a subsequent mass-dependent fractionation event, these results suggest that the apparent excesses in {sup 176}Hf are not caused by accelerated decay of {sup 176}Lu, and so another hypothesis is required to explain apparently old Lu–Hf ages.

  4. Magnetic order in Dy/Lu superlattices

    NASA Astrophysics Data System (ADS)

    Beach, R. S.; Borchers, J. A.; Erwin, R. W.; Flynn, C. P.; Matheny, A.; Rhyne, J. J.; Salamon, M. B.

    1992-02-01

    Several superlattices containing alternate layers of the rare earth elements dysprosium and lutetium were grown by molecular beam epitaxy. Neutron diffraction shows that these samples develop a helical phase in the (≈40 Å) Dy layers at TN = 178 K which propagates coherently across the nonmagnetic Lu (20-55 Å thick). The Dy layers order ferromagnetically at temperatures which vary from 140 to 160 K (the ferromagnetic phase in the bulk material appears at 85 K). Below TC the ferromagnetic Dy layers may be either aligned or anti-aligned. The transition is accompanied by a distortion of the superlattice basal plane comparable to that which occurs in bulk Dy. We also observe an approximately 80 K increase in TC in thin Lu/Dy(< 150 Å)/Lu films. We discuss how the observed high TC may be related to the elastic coupling of the Dy to Lu.

  5. MueLu Multigrid Preconditioning Package

    2012-09-11

    MueLu is intended for the research and development of multigrid algorithms used in the solution of sparse linear systems arising from systems of partial differential equations. The software provides multigrid source code, test programs, and short example programs to demonstrate the various interfaces for creating, accessing, and applying the solvers. MueLu currently provides an implementation of smoothed aggregation algebraic multigrid method and interfaces to many commonly used smoothers. However, the software is intended to bemore » extensible, and new methods can be incorporated easily. MueLu also allows for advanced usage, such as combining multiple methods and segregated solves. The library supports point and block access to matrix data. All algorithms and methods in MueLu have been or will be published in the open scientific literature.« less

  6. Dual nature of 3 d electrons in YbT 2 Zn 20 (T = Co; Fe) evidenced by electron spin resonance

    SciTech Connect

    Ivanshin, V. A.; Litvinova, T. O.; Gimranova, K.; Sukhanov, A. A.; Jia, S.; Bud'ko, S. L.; Canfield, P. C.

    2015-03-18

    The electron spin resonance experiments were carried out in the single crystals YbFe2Zn20. The observed spin dynamics is compared with that in YbCo2Zn20 and Yb2Co12P7 as well as with the data of inelastic neutron scattering and electronic band structure calculations. Our results provide direct evidence that 3d electrons are itinerant in YbFe2Zn20 and localized in YbCo2Zn20. Possible connection between spin paramagnetism of dense heavy fermion systems, quantum criticality effects, and ESR spectra is discussed.

  7. Continuous-wave laser action of Yb3+-doped lanthanum scandium borate

    NASA Astrophysics Data System (ADS)

    Romero, J. J.; Johannsen, J.; Mond, M.; Petermann, K.; Huber, G.; Heumann, E.

    2005-02-01

    Lanthanum scandium borate (LSB) has been proved to be an interesting laser matrix when doped with Nd3+ and Er3+ ions. In this paper, we demonstrate that it is also a very efficient laser material when doped with Yb3+ ions. The main spectroscopic characteristics of the system are presented, showing very broad absorption and emission bands, comparable to those found in Yb-doped GdCOB and YCOB crystals. From spectroscopic measurements the relevant laser parameters have been obtained, and a tunability of about 50 nm could be deduced. Room-temperature, continuous-wave laser action of Yb-doped LSB is demonstrated at a wavelength of 1045 nm with a slope efficiency as high as 64%.

  8. Grain size effect on magnetic and dielectric properties of hexagonal YbMnO3 nanoparticles

    NASA Astrophysics Data System (ADS)

    Han, Tai-Chun; Hsu, Hsin-Kai; Chu, Yih-Tsyr; Hu, Yu-Min

    2015-05-01

    We have synthesized a series of YbMnO3 nanoparticles with different grain sizes (25-450 nm) and study the effect of grain size on their structural, magnetic, and dielectric properties. The YbMnO3 nanoparticles crystallized in hexagonal perovskite-type structure. It shows that magnetic and dielectric properties are strongly dependent on the grain size. The magnetic characterization indicates that with increasing grain size, the antiferromagnetic (AFM) transition temperature increases from 70 to 86 K. A corresponding shift in the peak-positions of dielectric anomaly and AFM transition temperature is observed, indicating a strong correlation between the magnetic ordering and the electric polarization. As evidenced by the variation in the ab-plane lattice parameters and Mn-O bond lengths, the AFM interactions and dielectric anomalies of YbMnO3 can be effectively modulated by varying grain size.

  9. Passively mode-locked Yb:KLu(WO4)2 oscillators.

    PubMed

    Griebner, U; Rivier, S; Petrov, V; Zorn, M; Erbert, G; Weyers, M; Mateos, X; Aguiló, M; Massons, J; Díaz, F

    2005-05-01

    We demonstrate passive mode locking based on the novel monoclinic double tungstate crystal Yb:KLu(WO4)2. We report the shortest pulses ever produced with an Yb-doped tungstate laser using a semiconductor saturable absorber. A pulse duration of 81 fs has been achieved for an average power of 70 mW at 1046 nm. We compare the performance of the polarization oriented parallel to the Nm- and Np-crystallo-optic axes. Results in the femtosecond and picosecond regime are presented applying either Ti:sapphire or diode laser pumping. The great potential of Yb:KLu(WO4)2 as an active medium for ultrashort pulses is demonstrated for the first time, to our knowledge.

  10. T /B scaling without quasiparticle mass divergence: YbCo2Ge4

    NASA Astrophysics Data System (ADS)

    Sakai, Akito; Kitagawa, Kentaro; Matsubayashi, Kazuyuki; Iwatani, Makoto; Gegenwart, Philipp

    2016-07-01

    YbCo2Ge4 is a clean paramagnetic Kondo lattice which displays non-Fermi-liquid behavior. We report a detailed investigation of the specific heat, magnetic Grüneisen parameter (Γmag), and temperature derivative of the magnetization (M ) on a high-quality single crystal at temperatures down to 0.1 K and magnetic fields up to 7 T. Γmag and d M /d T display a divergence upon cooling and obey T /B scaling. Similar behavior has previously been found in several other Yb-based Kondo lattices and related to a zero-field quantum critical point without fine tuning of pressure or composition. However, in the approach of B →0 the electronic heat capacity coefficient of YbCo2Ge4 saturates at low T , excluding ferromagnetic quantum criticality. This indicates that T /B scaling is insufficient to prove a zero-field quantum critical point.

  11. Near-infrared supercontinnum generation in single-mode nonlinear Yb(3+)-doped fiber amplifier.

    PubMed

    Lin, Ja-Hon; Lee, Yin-Wen; Lin, Ting-Chun; Lai, Beng-Cheng; Pal, Mrinmay; Das, Shyamal; Dhar, Anirban; Paul, Mukul Chandra

    2014-06-30

    Near-infrared supercontinnum (SC) generation, accompanied with several emission bands at visible and ultraviolet, is experimentally investigated in an all-fiber single-mode Yb(3+)-doped silica fiber MOPA. The seed is an all-normal-dispersion mode-locked Yb(3+)-doped single-mode fiber laser using a nonlinear polarization evolution mechanism. With the pump power of several hundreds of milliwatts, SC spanning of 1010 nm to 1600 nm was generated in a 20-m single-mode germano-zirconia-silica Yb(3+)-doped fiber amplifier. The intensive nonlinear effects, namely stimulated Raman scattering, four wave mixing, and self-phase modulation, enable the SC generation in the small-core fiber amplifier without the use of photonic crystal fibers or tapered fibers. Such a compact and cost-effective SC generation system enables applications in optical coherent tomography, optical metrology, and nonlinear microscopy. PMID:24977865

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

    DOEpatents

    Krupke, W.F.; Payne, S.A.; Chase, L.L.; Smith, L.K.

    1994-01-18

    An ytterbium doped laser material remarkably superior to all others, including Yb:YAG, comprises ytterbium doped apatite (Yb:Ca[sub 5](PO[sub 4])[sub 3]F) or Yb:FAP, or ytterbium doped crystals that are structurally related to FAP. The new laser material is used in laser systems pumped by diode pump sources having an output near 0.905 microns or 0.98 microns, such as InGaAs and AlInGaAs, or other narrowband pump sources near 0.905 microns or 0.98 microns. The laser systems are operated in either the conventional or ground state depletion mode. 9 figures.

  13. Anisotropic magnetic properties and magnetic structure of YbPdSi

    NASA Astrophysics Data System (ADS)

    Tsujii, Naohito; Keller, Lukas; Dönni, Andreas; Kitazawa, Hideaki

    2016-08-01

    YbPdSi with orthorhombic crystal structure (space group Pmmn) exhibits a magnetic transition at {{T}\\text{m}}=8 K, below which a ferromagnetic moment develops with an enhanced electronic specific-heat coefficient γ ∼ 200 mJ K‑2 mol‑1. We have investigated the magnetization, electrical resistivity, and specific heat of YbPdSi using single crystalline samples as functions of temperature and magnetic field. It has been found that the ferromagnetic moment points to the c-direction, although the magnetic moments have an Ising-like anisotropy along the b-direction above the magnetic-transition temperature. Field dependence of the magnetization and electrical resistivity shows a metamagnetic-like transition at {{H}\\text{m}}=0.3 T when field is applied along the b-axis below T  =  3 K, suggesting the existence of an antiferromagnetic component along this direction. The magnetic structure has been investigated by neutron diffraction using powder samples. The magnetic unit cell is identical to the crystal unit cell. The Rietveld fitting has revealed that Yb at the 2a and 2b positions exhibit a collinear ferromagnetic order along the c-axis, whereas Yb at the 4e position undergoes a non-collinear order, involving the ferromagnetic moment along the c-axis and an antiferromagnetic component along the b-axis. The ferromagnetic moments determined by the neutron diffraction are 0.26, 1.3, and 0.15 {μ\\text{B}} for Yb at the 4e, 2b, and 2a sites, respectively. The reduced moments for the 4e and the 2a sites suggest that the Kondo screening effect is important in YbPdSi.

  14. Magnetic structure of Yb2Pt2Pb: Ising moments on the Shastry-Sutherland lattice

    DOE PAGESBeta

    Miiller, W.; Zaliznyak, I.; Wu, L. S.; Kim, M. S.; Orvis, T.; Simonson, J. W.; Gamza, M.; McNally, D. M.; Nelson, C. S.; Ehlers, G.; et al

    2016-03-22

    Neutron diffraction measurements were carried out on single crystals and powders of Yb2Pt2Pb, where Yb moments form two interpenetrating planar sublattices of orthogonal dimers, a geometry known as Shastry-Sutherland lattice, and are stacked along the c axis in a ladder geometry. Yb2Pt2Pb orders antiferromagnetically at TN=2.07K, and the magnetic structure determined from these measurements features the interleaving of two orthogonal sublattices into a 5×5×1 magnetic supercell that is based on stripes with moments perpendicular to the dimer bonds, which are along (110) and (–110). Magnetic fields applied along (110) or (–110) suppress the antiferromagnetic peaks from an individual sublattice, butmore » leave the orthogonal sublattice unaffected, evidence for the Ising character of the Yb moments in Yb2Pt2Pb that is supported by point charge calculations. Furthermore, specific heat, magnetic susceptibility, and electrical resistivity measurements concur with neutron elastic scattering results that the longitudinal critical fluctuations are gapped with ΔE≃0.07meV.« less

  15. Structural and crystal chemical properties of rare-earth double phosphates and rare-earth titanate pyrochlores

    NASA Astrophysics Data System (ADS)

    Farmer, J. Matt

    Alkali rare-earth double phosphates have been studied for use as long-wavelength scintillators for gamma-ray detection using Si photodiodes. These compounds exhibit layered crystal structures, built from roughly hexagonal atomic layers in the sequence lanthanide, phosphate-alkali, alkali, alkali-phosphate. Details of the crystal symmetry depend on the relative sizes of the rare-earth and alkali metal ions. Single-crystal X-ray diffraction (SXRD) has been used to study these structures at room temperature for K3RE(PO4) 2 (where RE = Lu-Ce, Y, and Sc). The compound K3Lu(PO 4)2 crystallizes with a hexagonal unit cell, space group P-3. The Lu ion is six-coordinated to the oxygen atoms of the phosphate groups. Two lower-temperature phases of K3Lu(PO4) 2 were observed and characterized. The lower-temperature transition results in an increase in coordination of the Lu ion to seven fold. This new structure is isostructural with the room-temperature form of K3Yb(PO 4)2. High-temperature powder neutron diffraction and high-temperature powder XRD have revealed a large thermal expansion anisotropy for K3Lu(PO4)2. The K3RE(PO 4)2 formation enthalpies were determined using high-temperature oxide-melt solution calorimetry. The formation enthalpy from oxides becomes more exothermic with increasing rare-earth radius. Rare-earth titanates, RE2Ti2O7 (where RE = a rare-earth), with the pyrochlore structure are currently being studied for use as potential nuclear, actinide-rich waste forms. Single-crystals were synthesized using a high-temperature flux technique and characterized using single-crystal X-ray diffraction. The cubic lattice parameters display an approximately linear correlation with the RE-site cation radius. The Sm and Eu titanates exhibit a covalency increase between the REO8 and TiO6 polyhedra resulting in a deviation from the increasing linear lattice parameter through the series. Gd2Ti2O7 exhibits the lowest 48f oxygen positional parameter, an effect that can be

  16. Comparative study of intrinsic luminescence in undoped transparent ceramic and single crystal garnet scintillators

    NASA Astrophysics Data System (ADS)

    Fujimoto, Yutaka; Yanagida, Takayuki; Yagi, Hideki; Yanagidani, Takagimi; Chani, Valery

    2014-10-01

    Scintillation properties associated with intrinsic lattice defects of undoped Y3A5O12 (YAG) and Lu3A5O12 (LuAG) transparent ceramics and single crystals are compared. The ceramics excited with X-ray demonstrated relatively low emission intensity when compared with that of the single crystals. Decay times of the ceramics and the single crystals were similar. These parameters were approximately 430 ns (YAG ceramic), 460 ns (YAG single crystal), 30 ns and 1090 ns (LuAG ceramic), and 25 ns and 970 ns (LuAG single crystal). According to the pulse height spectra recorded under 137Cs gamma-ray irradiation, the scintillation light yield of the both ceramics were about 2950 ± 290 ph/MeV. However, the single crystals had greater kight yield of about about 14,300 ± 1430 ph/MeV for YAG and 8350 ± 830 ph/MeV for LuAG.

  17. Isotope effect in charge transport of LuB{sub 12}

    SciTech Connect

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

    2010-08-15

    The galvanomagnetic properties of single-crystal samples with various isotopic boron compositions have been investigated for the first time for the normal state of superconductor LuB{sub 12} (Tc {approx} 0.44 K). Precision measurements of the resistivity, Hall coefficient, and magnetic susceptibility have been performed over a wide temperature range of 2-300 K in magnetic fields up to 80 kOe. A change of the charge transport regime in this nonmagnetic compound with metallic conduction is shown to occur near T* {approx} 50-70 K. As a result, a sharp peak with significantly different amplitudes for Lu{sup 10}B{sub 12} and Lu{sup 11}B{sub 12} is recorded in the temperature dependences of the Hall coefficient R{sub H}(T) near T*. A significant (about 10%) difference (in absolute value) of the Hall coefficients R{sub H} for the Lu{sup 10}B{sub 12} and Lu{sup 11}B{sub 12} compounds at helium and intermediate temperatures has been found and the patterns of behavior of the dependence R{sub H}(H) for T < T* in an external magnetic field H {<=} 80 kOe for Lu{sup 10}B{sub 12} and Lu{sup 11}B{sub 12} are shown to differ significantly. Analysis of the Curie-Weiss contribution to the magnetic susceptibility {chi}(T) leads to the conclusion about the formation of magnetic moments {mu}{sub eff} {approx} (0.13-0.19){mu}{sub B} in each unit cell of the fcc structure of LuB{sub 12} compounds with various isotopic compositions. The possibility of the realization of an electronic topological 2.5-order transition near T* and the influence of correlation effects in the 5d-band on the formation of a spin polarization near the rare-earth ions in LuB{sub 12} is discussed.

  18. Q-switching in a Cr{sup 3+}:Yb{sup 3+}:Ho{sup 3+}:YSGG crystal laser based on the {sup 5}I{sub 6} - {sup 5}I{sub 7} ({lambda}=2.92{mu}m) transition

    SciTech Connect

    Zavartsev, Yu D; Zagumennyi, A I; Kulevskii, L A; Lukashev, A V; Pashinin, Pavel P; Studenikin, P A; Shcherbakov, Ivan A; Umyskov, A F

    1999-04-30

    An investigation was made of the generation of giant pulses in a new yttrium scandium gallium garnet laser crystal doped with holmium (Cr{sup 3+}:Yb{sup 3+}:Ho{sup 3+}:YSGG) operating on the basis of the self-terminating {sup 5}I{sub 6} - {sup 5}I{sub 7} transition. Q-switching was performed by an electro-optical lithium niobate switch, a passive switch based on an epitaxial film of indium arsenide on a gallium arsenide substrate, or a passive switch consisting of water. The 2.92 {mu}m wavelength dominated giant pulse generation, whereas under free-running conditions the radiation was discretely tunable in the range 2.84 -3.05 {mu}m. Depending on the Q-switching method, pulses of 60 - 160 ns duration were generated and the pulse energy was {approx}20 mJ. The second and fourth harmonics of the holmium laser radiation were generated and the efficiency of each frequency-multiplication stage was {approx}20%. (lasers)

  19. Relativistic correlating basis sets for lanthanide atoms from Ce to Lu.

    PubMed

    Sekiya, Masahiro; Noro, Takeshi; Miyoshi, Eisaku; Osanai, You; Koga, Toshikatsu

    2006-03-01

    Contracted Gaussian-type function (CGTF) sets for the description of the 4f subshell correlation and of the 6s and 5d subshell correlation are developed for lanthanide atoms from Ce to Yb. Also prepared are basis sets for the 5d orbitals, which are vacant in the ground states of most lanthanide atoms but are essential in molecular environments. In addition, correlating CGTF sets for the 4f subshell correlation are supplemented for the Lu atom. A segmented contraction scheme is employed for their compactness and efficiency. Contraction coefficients and exponents are determined by minimizing the deviation from accurate natural orbitals generated from configuration interaction calculations that include relativistic effects through the third-order Douglas-Kroll approximation. All-electron and model core potential calculations with the present correlating sets are performed on the ground state of the diatomic CeO molecule. The calculated spectroscopic constants are in good agreement with experimental values. PMID:16419148

  20. Epitaxial growth and structure of (La{sub 1-x}Lu{sub x}){sub 2}O{sub 3} alloys on Si(111)

    SciTech Connect

    Watahiki, T.; Grosse, F.; Braun, W.; Kaganer, V. M.; Proessdorf, A.; Trampert, A.; Riechert, H.

    2010-07-19

    LaLuO{sub 3} layers are epitaxially grown on Si(111) by molecular beam epitaxy using high temperature effusion sources. Samples are prepared by simultaneous as well as alternating growth of La{sub 2}O{sub 3} and Lu{sub 2}O{sub 3}. Grazing incidence x-ray diffraction indicates that the resulting crystal structure of the alloys is cubic. Simultaneous and alternating growth with a monolayer period lead to the same distribution of La and Lu with no preferential ordering. In all cases the lattice mismatch to Si is less than 0.6%. The experimental results are analyzed by studying the energetics of hexagonal, bixbyite, and perovskite (La{sub 1-x}Lu{sub x}){sub 2}O{sub 3} crystal structures employing density functional theory.

  1. New tetragonal derivatives of cubic NaZn13-type structure: RNi6Si6 compounds, crystal structure and magnetic ordering (R=Y, La, Ce, Sm, Gd-Yb)

    NASA Astrophysics Data System (ADS)

    Pani, M.; Manfrinetti, P.; Provino, A.; Yuan, Fang; Mozharivskyj, Y.; Morozkin, A. V.; Knotko, A. V.; Garshev, A. V.; Yapaskurt, V. O.; Isnard, O.

    2014-02-01

    Novel RNi6Si6 compounds adopt the new CeNi6Si6-type structure for R=La-Ce (tP52, space group P4/nbm N 125-1) and new YNi6Si6-type structure for R=Y, Sm, Gd-Yb (tP52, space group P4barb2N 117) that are tetragonal derivative of NaZn13-type structure, like LaCo9Si4-type. The CeNi6Si6, GdNi6Si6, TbNi6Si6, DyNi6Si6 and HoNi6Si6 compounds are Curie-Weiss paramagnets down to ~30 K, and do not order magnetically down to 5 K. However, the inverse paramagnetic susceptibility of LaNi6Si6 does not follow Curie-Weiss law. The DyNi6Si6 shows ferromagnetic-like saturation behaviour at 5 K in applied fields of 50 kOe, giving rise to a magnetic moment value of 6.5 μB/f.u. in 50 kOe. The powder neutron diffraction study in zero applied filed indicates square modulated the c-collinear antiferromagnetic ordering of TbNi6Si6 with K=[±1/4, ±1/4, 0] wave vector below ~10 K. The CeNi6Si6, GdNi6Si6, TbNi6Si6, DyNi6Si6 and HoNi6Si6 compounds are Curie-Weiss paramagnets down to ~30 K, and do not order magnetically down to 4.2 K. The powder neutron diffraction study in zero applied filed indicates square modulated the c-collinear antiferromagnetic ordering of TbNi6Si6 with K=[±1/4, ±1/4, 0] wave vector below ~10 K.

  2. Collapse dynamics of a {sup 176}Yb-{sup 174}Yb Bose-Einstein condensate

    SciTech Connect

    Chaudhary, G. K.; Ramakumar, R.

    2010-06-15

    In this paper, we present a theoretical study of a two-component Bose-Einstein condensate composed of ytterbium (Yb) isotopes in a three-dimensional anisotropic harmonic potential. The condensate consists of a mixture of {sup 176}Yb atoms which have a negative s-wave scattering length and {sup 174}Yb atoms having a positive s-wave scattering length. We study the ground-state as well as dynamic properties of this two-component condensate. Due to the attractive interactions between {sup 176}Yb atoms, the condensate of {sup 176}Yb undergoes a collapse when the particle number exceeds a critical value. The critical number and the collapse dynamics are modified due to the presence of {sup 174}Yb atoms. We use coupled two-component Gross-Pitaevskii equations to study the collapse dynamics. The theoretical results obtained are in reasonable agreement with the experimental results of Fukuhara et al. [Phys. Rev. A 79, 021601(R) (2009)].

  3. Microwave sol-gel process of KGd(WO4)2:Ho3+/Yb3 phosphors and their upconversion photoluminescence properties

    NASA Astrophysics Data System (ADS)

    Sung Lim, Chang

    2015-03-01

    Double tungstate KGd1-x(WO4)2:Ho3+/Yb3+ phosphors with doping concentrations of Ho3+ and Yb3+ (x=Ho3++Yb3+, Ho3+=0.05, 0.1, 0.2 and Yb3+=0.2, 0.45) were successfully synthesized by the microwave sol-gel method, and the upconversion mechanisms were investigated in detail. The synthesized particles formed after heat-treatment at 900 °C for 16 h showed a well crystallized morphology with particle sizes of 2-5 μm. Under excitation at 980 nm, the UC intensities of KGd0.7(WO4)2:Ho0.1Yb0.2 and KGd0.5(WO4)2Ho0.05Yb0.45 particles exhibited yellow emissions based on a strong 550-nm emission band in the green region and a strong 655-nm emission band in the red region, which were assigned to the 5S2/5F4→5I8 and 5F5→5I8 transitions, respectively. The Raman spectra of the doped particles indicated the presence of strong peaks at higher frequencies of 764, 812, 904, 984, 1050, 1106, 1250 and 1340 cm-1 induced by the disorder of the [WO4]2- groups with the incorporation of the Ho3+ and Yb3+ elements into the crystal lattice or by a new phase formation.

  4. Synthesis of metastable rare-earth-iron mixed oxide with the hexagonal crystal structure

    SciTech Connect

    Nishimura, Tatsuya; Hosokawa, Saburo; Masuda, Yuichi; Wada, Kenji; Inoue, Masashi

    2013-01-15

    Rare-earth-iron mixed oxides with the rare earth/iron ratio=1 have either orthorhombic (o-REFeO{sub 3}) or hexagonal (h-REFeO{sub 3}) structure. h-REFeO{sub 3} is a metastable phase and the synthesis of h-REFeO{sub 3} is usually difficult. In this work, the crystallization process of the precursors obtained by co-precipitation and Pechini methods was investigated in detail to synthesize h-REFeO{sub 3}. It was found that the crystallization from amorphous to hexagonal phase and the phase transition from hexagonal to orthorhombic phase occurred at a similar temperature range for rare earth elements with small ionic radii (Er-Lu, Y). For both co-precipitation and Pechini methods, single-phase h-REFeO{sub 3} was obtained by shortening the heating time during calcination process. The hexagonal-to-orthorhombic phase transition took place by a nucleation growth mechanism and vermicular morphology of the thus-formed orthorhombic phase was observed. The hexagonal YbFeO{sub 3} had higher catalytic activity for C{sub 3}H{sub 8} combustion than orthorhombic YbFeO{sub 3}. - Graphical abstract: Although the synthesis of metastable hexagonal REFeO{sub 3} by the conventional method is difficult, we found that this phase is obtained by shortening the heating time of the precursor prepared by co-precipitation method. Highlights: Black-Right-Pointing-Pointer Synthesis of metastable REFeO{sub 3} with hexagonal structure by the co-precipitation method. Black-Right-Pointing-Pointer Hexagonal REFeO{sub 3} is obtained for the rare earth elements with small ionic radii. Black-Right-Pointing-Pointer Hexagonal-to-orthorhombic transformation of REFeO{sub 3}. Black-Right-Pointing-Pointer Catalytic activity of hexagonal REFeO{sub 3} for C{sub 3}H{sub 8} combustion.

  5. Selective excitation study of Yb3+ in GdCa4O(BO3)3 and YCa4O(BO3)3

    NASA Astrophysics Data System (ADS)

    Lupei, A.; Aka, G.; Antic-Fidancev, E.; Viana, B.; Vivien, D.; Aschehoug, P.

    2002-02-01

    The Yb3+-doped non-linear rare-earth calcium oxoborate crystals GdCa4O (BO3)3 (GdCOB) and YCa4O(BO3)3 (YCOB) were investigated by low-temperature absorption and selective excitation spectroscopy. The selective excitation and emission spectra revealed the spectral features of the main Yb3+ centre and the principal minority one in both crystals. The energy level schemes for these centres in both hosts, as well as structural assignments, were proposed. It was established that the minority centre, which represents about 10% of the total intensity and was assigned to Yb3+ in a Ca2+ site, is not a trap but an energy donor for the main centre. Common features of and differences between the vibronic structure of the two centres in GdCOB and YCOB are discussed. The existence of additional features in YCOB:Yb spectra is pointed out.

  6. Preparation of high-purity LiF, YF3, and YbF3 for laser refrigeration

    NASA Astrophysics Data System (ADS)

    Hehlen, Markus P.; Boncher, William L.; Melgaard, Seth D.; Blair, Michael W.; Jackson, Robert A.; Littleford, Thomas E.; Love, Steven P.

    2014-02-01

    The role of transition-metal impurities in Yb3+-doped YLiF4 (YLF) laser-cooling crystals is studied. Divalent 3d transition-metal ions, in particular Fe2+, are found to have strong absorptions at the laser cooling pump wavelength and degrade the cooling efficiency by introducing background absorption. A set of eight substitutional and chargecompensated defects that form upon introduction of 1+, 2+, and 3+ transition-metal ions into the YLF crystal lattice is proposed. A calculation of solution energies for each defect type and for a range of 3d ions is carried out. It indicates that divalent 3d ions preferentially substitute for Y3+ accompanied by a fluoride vacancy for charge compensation. An electron paramagnetic resonance (EPR) study of a YLF crystal identifies Fe2+ in the crystal lattice, in agreement with the elemental analysis and the computational results. A strategy for purifying the YF3, LiF, and YbF3 starting materials for the YLF:Yb crystal growth is discussed. Chelate-assisted solvent extraction purification with pyrrolidine dithiocarbamate (APDC) for Y, Li, and Yb as well as ethylenediaminetetraacetic acid (EDTA) for Li was carried out.

  7. Muon Spin Relaxation Evidence for the U(1) Quantum Spin-Liquid Ground State in the Triangular Antiferromagnet YbMgGaO4

    NASA Astrophysics Data System (ADS)

    Li, Yuesheng; Adroja, Devashibhai; Biswas, Pabitra K.; Baker, Peter J.; Zhang, Qian; Liu, Juanjuan; Tsirlin, Alexander A.; Gegenwart, Philipp; Zhang, Qingming

    2016-08-01

    Muon spin relaxation (μ SR ) experiments on single crystals of the structurally perfect triangular antiferromagnet YbMgGaO4 indicate the absence of both static long-range magnetic order and spin freezing down to 0.048 K in a zero field. Below 0.4 K, the μ+ spin relaxation rates, which are proportional to the dynamic correlation function of the Yb3 + spins, exhibit temperature-independent plateaus. All these μ SR results unequivocally support the formation of a gapless U(1) quantum spin liquid ground state in the triangular antiferromagnet YbMgGaO4 .

  8. Muon Spin Relaxation Evidence for the U(1) Quantum Spin-Liquid Ground State in the Triangular Antiferromagnet YbMgGaO_{4}.

    PubMed

    Li, Yuesheng; Adroja, Devashibhai; Biswas, Pabitra K; Baker, Peter J; Zhang, Qian; Liu, Juanjuan; Tsirlin, Alexander A; Gegenwart, Philipp; Zhang, Qingming

    2016-08-26

    Muon spin relaxation (μSR) experiments on single crystals of the structurally perfect triangular antiferromagnet YbMgGaO_{4} indicate the absence of both static long-range magnetic order and spin freezing down to 0.048 K in a zero field. Below 0.4 K, the μ^{+} spin relaxation rates, which are proportional to the dynamic correlation function of the Yb^{3+} spins, exhibit temperature-independent plateaus. All these μSR results unequivocally support the formation of a gapless U(1) quantum spin liquid ground state in the triangular antiferromagnet YbMgGaO_{4}. PMID:27610879

  9. Muon Spin Relaxation Evidence for the U(1) Quantum Spin-Liquid Ground State in the Triangular Antiferromagnet YbMgGaO_{4}.

    PubMed

    Li, Yuesheng; Adroja, Devashibhai; Biswas, Pabitra K; Baker, Peter J; Zhang, Qian; Liu, Juanjuan; Tsirlin, Alexander A; Gegenwart, Philipp; Zhang, Qingming

    2016-08-26

    Muon spin relaxation (μSR) experiments on single crystals of the structurally perfect triangular antiferromagnet YbMgGaO_{4} indicate the absence of both static long-range magnetic order and spin freezing down to 0.048 K in a zero field. Below 0.4 K, the μ^{+} spin relaxation rates, which are proportional to the dynamic correlation function of the Yb^{3+} spins, exhibit temperature-independent plateaus. All these μSR results unequivocally support the formation of a gapless U(1) quantum spin liquid ground state in the triangular antiferromagnet YbMgGaO_{4}.

  10. Direct imaging of rare-earth ion clusters in Yb:CaF2

    NASA Astrophysics Data System (ADS)

    Lacroix, B.; Genevois, C.; Doualan, J. L.; Brasse, G.; Braud, A.; Ruterana, P.; Camy, P.; Talbot, E.; Moncorgé, R.; Margerie, J.

    2014-09-01

    The existence and the identification of only one or several coparticipating luminescent Yb3+ centers in the heavily doped Yb :CaF2 laser crystals which are considered in the development of several high intensity laser chains have been examined first by using two complementary and original experimental approaches, i.e., registration of low temperature site-selective laser excitation spectra related to near-infrared and visible cooperative emission processes, on the one hand, and direct imaging at the atomic scale of isolated ions and clusters using a high-resolution scanning transmission electron microscope in the high angle annular dark-field mode, on the other hand, and then correlating the data with simple crystal field calculations. As a consequence, and although all the experimental details could not be accounted for quantitatively, a good overall correlation was found between the experimental and the theoretical data. The results show that at the investigated dopant concentrations, Yb:CaF2 should be considered as a multisite system whose luminescent and lasing properties are dominated by a series of Yb3+ clusters ranging from dimers to tetramers. Hexameric luminescent centers may be dominant at really high dopant concentrations (likely above 20 at. %), as was originally proposed, but certainly not at the intermediate dopant concentrations which are considered for the laser application, i.e., between about 0.5 and 10 at. %.

  11. Yb2Pt2Pb: Magnetic frustration in the Shastry-Sutherland lattice

    DOE PAGESBeta

    Kim, M. S.; Bennett, M. C.; Aronson, M. C.

    2008-04-23

    Here, we have synthesized single crystals of Yb2Pt2Pb, which crystallize in the layered U2Pt2Sn-type structure, where planes of Yb ions lie on a triangular network. Here, we report the results of magnetization, specific heat, and electrical resistivity experiments. The lattice constants and high temperature magnetic susceptibility indicate that the Yb ions are trivalent, while the Schottky peaks in the specific heat show that the ground state is a well isolated doublet. A significant magnetic anisotropy is observed, with the ratio of susceptibilities perpendicular and parallel to the magnetic planes differing by as much as a factor of 30 at themore » lowest temperatures. Antiferromagnetic order occurs at a Néel temperature TN = 2.07 K. Evidence of short range magnetic fluctuations is found in the magnetic susceptibility and electrical resistivity, which have broad peaks above TN, and in the slow development of the magnetic entropy at TN. Our experiments indicate that Yb2Pt2Pb is a quasi-two-dimensional and localized moment system, where strong magnetic frustration may arise from the geometry of the underlying Shastry-Sutherland lattice.« less

  12. Thermal, magnetic and electronic properties of non-centrosymmetric YbPt2B

    NASA Astrophysics Data System (ADS)

    Khan, R. T.; Kneidinger, F.; Hilscher, G.; Sidorenko, A.; Sologub, O.; Michor, H.; Bauer, E.; Rogl, P.; Giester, G.

    2015-04-01

    Ternary YbPt2B crystallizes in the non-centrosymmetric hexagonal CePt2B-type structure (space group P6222). Electrical resistivity, specific heat and magnetic measurements reveal a magnetic instability at 5.6 K. Furthermore, a spin-reorientation of presumably a ferromagnetic type occurs around 1.5 K. The behaviour at low temperature is governed by a rather weak Kondo effect, TK ⩽ 1 K, in the presence of strong crystalline electric field splitting, with a doublet ground state. Besides, the complex magnetic behaviour presumably results from a Dzyaloshinskii-Moriya interaction triggered by the absence of inversion symmetry in the crystal structure. Scaling according to the de Gennes factor traces back magnetic ordering in YbPt2B to the Rudermann-Kittel-Kasuya-Yoshida (RKKY) interaction and the smooth evolution of the lattice constants and the unit cell volume of REPt2B (RE = rare earths) refers to the 4f13 electronic configuration of Yb in YbPt2B.

  13. Spectroscopy and lasing of cryogenically cooled Yb, Na:CaF2

    NASA Astrophysics Data System (ADS)

    Pugžlys, A.; Andriukaitis, G.; Sidorov, D.; Irshad, A.; Baltuška, A.; Lai, W. J.; Phua, P. B.; Su, L.; Xu, J.; Li, H.; Li, R.; Ališauskas, S.; Marcinkevičius, A.; Fermann, M. E.; Giniūnas, L.; Danielius, R.

    2009-10-01

    Absorption, photoluminescence and cw-lasing properties of a novel Na+-codoped Yb3+:CaF2 laser crystal are investigated in the temperature range from 10 K to 290 K. Cryogenic cooling leads to the disappearance of the ground-state absorption in the spectral region above 1000 nm and a substantial increase of emission and absorption cross-sections. A particular advantage of the Yb3+, Na+-codoped CaF2 crystal lies in the possibility of a direct pumping in the vicinity of the zero phonon line while nearly perfectly avoiding an overlap with the stimulated emission. Further advantages of the low-temperature operation are demonstrated by achieving a close to the theoretical limit slope efficiency of 92% in a cw-laser operation with an output coupler of 28%. By seeding stretched pulses from a femtosecond Yb fiber oscillator into a cryogenically cooled DPSS Yb3+, Na+:CaF2 regenerative amplifier, we obtain >3-mJ pulses at a 1-kHz repetition rate with a spectral bandwidth exceeding 12 nm. The pulses are compressed with a single grating compressor to 173 fs as verified by SHG FROG. Shaping of the spectral amplitude of the seed and active control of the higher-order phase is shown to be crucial for obtaining sub-200-fs pulses at multi-mJ energies.

  14. Magnetic Hyperfine Fields in Lu_2 V_2 O_7 : A Model Approach

    NASA Astrophysics Data System (ADS)

    Agzamova, Polina; Nikiforov, Anatoliy; Nazipov, Dmitriy

    2016-02-01

    We report a theoretical approach to the investigation of the magnetic hyperfine interaction on the ^{51} V nucleus in Lu_2 V_2 O_7 with the view of understanding the orbital ordering pattern in this compound. First, we have evaluated the vanadium 3d^1 -level splitting (Δ ) under the crystal field with the D _{3d} -symmetry using the point charges approximation. Second, we have calculated the exchange interaction constant (J) using the ab initio approach. It is shown that the crystal field energy is much stronger than the exchange interaction one and hence the orbital liquid state cannot occur in Lu_2 V_2 O_7 . Finally we have analyzed the magnetic hyperfine field affecting the vanadium nucleus leaning upon these results.

  15. A new oxytelluride: Perovskite and CsCl intergrowth in Ba3Yb2O5Te

    NASA Astrophysics Data System (ADS)

    Whalen, J. B.; Besara, T.; Vasquez, R.; Herrera, F.; Sun, J.; Ramirez, D.; Stillwell, R. L.; Tozer, S. W.; Tokumoto, T. D.; McGill, S. A.; Allen, J.; Davidson, M.; Siegrist, T.

    2013-07-01

    The new oxytelluride Ba3Yb2O5Te was obtained from an alkaline earth flux. Ba3Yb2O5Te crystallizes in the tetragonal space group P4/mmm (#123), with a=4.3615(3) Å and c=11.7596(11) Å, Z=1. The structure combines two distinct building blocks, a Ba2Yb2O5 perovskite-like double layer with square bipyramidal coordination of the ytterbium ions, and a CsCl-type BaTe layer. Short range magnetic order is apparent at below 5 K, with the magnetic behavior above this temperature dominated by crystal field effects. The structure may be considered as an analog to the Ruddlesden-Popper phases, where the NaCl-type layer has been replaced by the CsCl-type layer. The two-dimensional magnetic behavior is expected based on the highly anisotropic nature of the structure.

  16. Microstructure, optical, and scintillation characteristics of Pr{sup 3+} doped Lu{sub 3}Al{sub 5}O{sub 12} optical ceramics

    SciTech Connect

    Shi Yun; Feng Xiqi; Shen Yiqiang; Pan Yubai; Liu Qian; Nikl, Martin; Mares, Jiri A.; Beitlerova, A.; Kucerkova, R.

    2011-01-01

    0.5, 1.0, and 5.0 at. %Pr{sup 3+} doped Lu{sub 3}Al{sub 5}O{sub 12} (Pr:LuAG) optical ceramics are fabricated and compared with Bi{sub 4}Ge{sub 3}O{sub 12} (BGO) and Pr:LuAG single crystals as for their optical, luminescence and scintillation properties. Radio-luminescence intensity of the fast UV emission based on 5d{sub 1}{yields}4f Pr{sup 3+} transition reaches up to 20 times of that of BGO single crystal reference scintillator. Photoelectron yield of the best performing 0.5 at. % Pr:LuAG ceramic sample is about 1002 phels/MeV, about 30% lower than that of BGO reference sample and about 65% lower than that of Pr:LuAG single crystal. The trapping phenomena at grain boundaries and/or structural defects are proposed as the main cause of degradation of the scintillation response of the Pr:LuAG optical ceramics.

  17. On the structural origin of the single-ion magnetic anisotropy in LuFeO3.

    PubMed

    Cao, Shi; Zhang, Xiaozhe; Paudel, Tula R; Sinha, Kishan; Wang, Xiao; Jiang, Xuanyuan; Wang, Wenbin; Brutsche, Stuart; Wang, Jian; Ryan, Philip J; Kim, Jong-Woo; Cheng, Xuemei; Tsymbal, Evgeny Y; Dowben, Peter A; Xu, Xiaoshan

    2016-04-20

    The electronic structure for the conduction bands of both hexagonal and orthorhombic LuFeO3 thin films have been measured using x-ray absorption spectroscopy at oxygen K (O K) edge. Dramatic differences in both the spectral features and the linear dichroism are observed. These differences in the spectra can be explained using the differences in crystal field splitting of the metal (Fe and Lu) electronic states and the differences in O 2p-Fe 3d and O 2p-Lu 5d hybridizations. While the oxidation states have not changed, the spectra are sensitive to the changes in the local environments of the Fe(3+) and Lu(3+) sites in the hexagonal and orthorhombic structures. Using the crystal-field splitting and the hybridizations that are extracted from the measured electronic structures and the structural distortion information, we derived the occupancies of the spin minority states in Fe(3+), which are non-zero and uneven. The single ion anisotropy on Fe(3+) sites is found to originate from these uneven occupancies of the spin minority states via spin-orbit coupling in LuFeO3. PMID:26982512

  18. Proton and Gamma Radiation Effects in Undoped, Single-doped and co-doped YLiF4 and LuLiF4

    NASA Technical Reports Server (NTRS)

    Lee, Hyung; Bai, Yingxin; Yu, Kirong; Singh, U.

    2009-01-01

    Proton and gamma radiation effects in various YLiF4 and LuLiF4 crystals have been investigated. The radiation induced color centers compared with six different kinds of crystal samples in ranges up to 200 krads and 200 MeV. The radiation induced absorption coefficients are strongly dependent on polarization and concentration of rare-earth ions.

  19. Structural, microstructural and vibrational analyses of the monoclinic tungstate BiLuWO{sub 6}

    SciTech Connect

    Ait Ahsaine, H.; Taoufyq, A.; Patout, L.; Ezahri, M.; Benlhachemi, A.; Bakiz, B.; Villain, S.; Guinneton, F.; Gavarri, J.-R.

    2014-10-15

    The bismuth lutetium tungstate phase BiLuWO{sub 6} has been prepared using a solid state route with stoichiometric mixtures of oxide precursors. The obtained polycrystalline phase has been characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Raman spectroscopy. In the first step, the crystal structure has been refined using Rietveld method: the crystal cell was resolved using monoclinic system (parameters a, b, c, β) with space group A2/m. SEM images showed the presence of large crystallites with a constant local nominal composition (BiLuW). TEM analyses showed that the actual local structure could be better represented by a superlattice (a, 2b, c, β) associated with space groups P2 or P2/m. The Raman spectroscopy showed the presence of vibrational bands similar to those observed in the compounds BiREWO{sub 6} with RE=Y, Gd, Nd. However, these vibrational bands were characterized by large full width at half maximum, probably resulting from the long range Bi/Lu disorder and local WO{sub 6} octahedron distortions in the structure. - Graphical abstract: The average structure of BiLuWO{sub 6} determined from X-ray diffraction data can be represented by A2/m space group. Experimental Electron Diffraction patterns along the [0vw] zone axes of the monoclinic structure and associated simulated patterns show the existence of a monoclinic superstructure with space group P2 or P2/m. - Highlights: • A new monoclinic BiLuWO{sub 6} phase has been elaborated from solid-state reaction. • The space group of the monoclinic disordered average structure should be A2/m. • Transmission electron microscopy leads to a superlattice with P2/m space group. • Raman spectroscopy suggests existence of local disorder.

  20. The 4f-5d luminescence transitions in cerium-doped LuF3

    NASA Astrophysics Data System (ADS)

    Guerbous, L.; Krachni, O.

    Emission and excitation spectra of the Ce3+ ion in LuF3 single crystal were measured at 77 K. The broad bands observed in these spectra were attributed to the parity-allowed electric-dipole 4f ← 5d transitions within Ce3+ ion. No zero-phonon lines were observed, which is indicative of a strong electron-phonon coupling in this host. It is shown that Ce3+ 5d excited configuration splits into five crystal-field components in LuF3. The influence of the crystalline environment on the position of the lowest Ce3+ 5d level is investigated. The energy of the lowest level of the 4fN-15d excited configuration was predicted for all the trivalent rare earth ions embedded in LuF3. Positions of crystal field spitting levels of 4fN-15d configuration relative to the host electronic bands were discussed.

  1. Lu-Hf isotope systematics of fossil biogenic apatite and their effects on geochronology

    NASA Astrophysics Data System (ADS)

    Herwartz, Daniel; Münker, Carsten; Tütken, Thomas; Hoffmann, J. Elis; Wittke, Andreas; Barbier, Bruno

    2013-01-01

    Reliable methods for direct dating of biogenic apatite from pre-Pleistocene fossils are currently not available, and recent attempts using the Lu-Hf decay system yielded highly inaccurate ages for both bones and teeth. The geological processes accounting for this poor accuracy of Lu-Hf chronometry are not yet understood. Here we explore Lu-Hf systematics in fossil bones and teeth in detail, by applying five different sample digestion techniques that are tested on bones and composites of bone and sediment. Our current dataset implies that dissolution methods only slightly affect the resulting Lu-Hf ages, while clear differences between the individual digestion techniques became apparent for element concentrations. By analysing the insoluble leftovers from incomplete sample dissolution, four main reservoirs of Hf in fossil bones were identified: (1) a radiogenic end-member associated with apatite; (2) an unradiogenic end-member represented by the authigenic minerals or the embedding sediment; (3) a highly unradiogenic end-member that can be attributed to detrital zircon; and (4) a moderately soluble phase (probably a Zr(Hf)-phosphate) that yielded very low Lu/Hf but a highly radiogenic Hf isotope composition at the same time. This Zr(Hf)-phase must have been precipitated within the fossil bone sample at a late stage of burial history, thereby incorporating radiogenic 176Hf released from apatite surfaces over geological timescales. A second focus of our study is the effect of different sediment matrices and of crystal size on the preservation of pristine Lu-Hf isotope compositions in bioapatite. Because near-depositional Lu-Hf ages of phosphate fossils have previously been reported for the London Clay (England) and a calcareous marl from Tendaguru (Tanzania), we herein investigate specimens fossilised in carbonate matrices (calcareous marl from Oker, Germany; carbonate concretions from the Santana Formation, Brazil; carbonate from the Eifel, Germany) and argillaceous

  2. Parallel execution of LU factorization: An analysis

    SciTech Connect

    Boreddy, J.; Paulraj, A.

    1990-02-01

    The authors consider LU factorization of dense matrices, and develop analytical models for execution on MIMD local memory systems. Both broadcast and nearest neighbor communication models are studied by quantifying computation, communication, and idle times. The performance modelling is validated through experimental results on a transputer array. The authors implemented three variants of LU factorization on a unidirectional ring: nearest neighbor communications with non-overlapped as well as overlapped communications, and broadcasting with pipelined data transfer. It has been found that broadcasting falls in between non-overlapped and overlapped nearest neighbor communications.

  3. Modeling the absorption spectra of Er3+ and Yb3+ in a phosphate glass

    NASA Astrophysics Data System (ADS)

    Gruber, John B.; Sardar, Dhiraj K.; Zandi, Bahram; Hutchinson, J. Andrew; Trussell, C. Ward

    2003-10-01

    Absorption spectra of Er3+ and Yb3+ ions, codopants in a phosphate glass, are reported at 8 K and at wavelengths between 350 and 1600 nm. Detailed structure appearing in the spectra, associated with individual multiplet states, 2S+1LJ, of Er3+(4f11) and Yb3+(4f13) is interpreted using a ligand-field coordination sphere model to characterize the microscopic environment surrounding the rare earth ions in multiple sites. Inhomogeneous broadening of the spectra is likely due to different configurations of PO4 tetrahedra clustered about a caged rare earth ion in the amorphous host. Similarity between the Er3+ spectrum in the glass and in the spectrum of single-crystal LiErP4O12, where Er3+ occupies sites of C2 symmetry, suggests that an averaged site symmetry of C2 is a reasonable approximation for Er3+ and Yb3+ ions in the phosphate glass. Calculated splitting of multiplet states by the ligand-field cluster model are compared with energy levels derived from the observed absorption peaks and well-defined shoulders. Inhomogeneous broadening of the spectra limit the precision in establishing the energy of the multiplet splittings, but the analysis is useful for modeling studies of the Er:Yb:phosphate glass as an eye-safe laser (1.53 μm). The splitting of the Yb3+(4f13)2FJ states is determined using parameters obtained from the Er3+ set by means of the three-parameter theory. No adjustments were made to the Yb3+ parameters that predict multiplet splittings in reasonable agreement with experimental data.

  4. The success and complementarity of Sm-Nd and Lu-Hf garnet geochronology

    NASA Astrophysics Data System (ADS)

    Baxter, E. F.; Scherer, E. E.

    2013-12-01

    Garnet's potential as a direct chronometer of tectonometamorphic processes and conditions was first realized over 30 years ago. Since then, the Sm-Nd and Lu-Hf systems have emerged as the most effective, with both permitting age precision < ×1 Myr. Both have proven successful not merely in dating garnet growth itself, but rather in constraining the ages, durations, and rates of particular earth processes or conditions that can be directly linked to garnet growth via chemical, thermodynamic, or petrographic, means. Appreciating important differences between Sm-Nd and Lu-Hf in terms of contaminant phases, partitioning, daughter element diffusivity, and isotopic analysis makes these two systems powerfully complementary when used and interpreted in concert. Well established, robust analytical methods mitigate the effects of ubiquitous mineral inclusions (monazite is most significant for Sm-Nd; zircon is most significant for Lu-Hf), improving the precision and accuracy of garnet dates from both systems. Parent-daughter ratios tend to be higher for Lu-Hf leading to the potential for better age precision in general. The Lu-176 decay rate is faster than Sm-147, meaning that Lu-Hf provides better age precision potential for young (Cenozoic) samples. However, Sm-Nd provides better precision potential for older (Precambrian) samples primarily because of the higher precisions on the parent-daughter ratios (i.e., 147Sm/144Nd) that can be achieved by ID-TIMS analysis. For dating microsampled zones or growth rings in single garnet crystals, Sm-Nd has proven most successful owing to more uniform distribution of Sm, and established methods to measure <10 ng quantities of Nd at high precision via TIMS. However, new MC-ICP-MS sample introduction technologies are closing this gap for small samples. For analyses of bulk garnet that grew over a protracted interval, Lu-Hf dates are expected to be older than Sm-Nd dates owing to differences in Lu and Sm zonation (i.e. Lu tends to be

  5. ZnO epitaxy on (111) Si using epitaxial Lu2O3 buffer layers

    NASA Astrophysics Data System (ADS)

    Guo, W.; Allenic, A.; Chen, Y. B.; Pan, X. Q.; Tian, W.; Adamo, C.; Schlom, D. G.

    2008-02-01

    We report the growth and characterization of single-crystalline, crack-free, epitaxial (0001) ZnO films on (111) Si substrates using intervening epitaxial Lu2O3 buffer layers. The epitaxial orientation relationships are (0001)ZnO∥(111)Lu2O3∥(111)Si and [12¯10]ZnO∥[1¯10]Lu2O3∥[11¯0]Si. X-ray diffraction and transmission electron microscopy reveal that the ZnO films have high structural quality and an atomically sharp ZnO /Lu2O3 interface. Temperature-dependent photoluminescence measurements show optical properties comparable to ZnO single crystals. The films have a resistivity of 0.31Ωcm, an electron concentration of 2.5×1017cm-3, and a mobility of 80cm2/Vṡs at room temperature. The epitaxial growth of ZnO on Si represents a significant step toward the integration of ZnO-based multifunctional devices with Si electronics.

  6. Diode-pumped cw tunable Er 3+:Yb 3+:YCOB laser at 1.5-1.6 μm

    NASA Astrophysics Data System (ADS)

    Wang, Pu; Dawes, Judith M.; Burns, Phillip; Piper, James A.; Zhang, Huaijin; Zhu, Li; Meng, Xianlin

    2002-05-01

    Laser emission at 1.55 μm has been achieved for the novel laser-nonlinear optical crystal Er:Yb:YCa 4O(BO 3) 3 operated at room temperature, and pumped by a 976 nm diode. A tunable range of 23 nm (1535-1558 nm) was realized with a 50 μm etalon.

  7. Thin-disk Raman laser operation of Yb:YVO4/YVO4 around 1120 nm

    NASA Astrophysics Data System (ADS)

    Yang, F. G.; Qiao, L.; Xia, Z. C.

    2015-12-01

    We present diode-pumped Yb:YVO4/YVO4 thin-disk Raman laser operation around 1120 nm. The thin-disk crystals, Yb:YVO4, and the Raman crystal, YVO4, are cut with 250 μm and 20 mm, respectively. In multimode configurations, up to 0.91 W of Raman laser output power and a maximum slope efficiency of 10% are demonstrated corresponding to a pump power of 10 W. A continuous wavelength tuning range of 54 nm from 1096 to 1150 nm with a maximum output power of 320 mW at 1126 nm is confirmed.

  8. Orthogonally polarized dual-wavelength Yb:KGW laser induced by thermal lensing

    NASA Astrophysics Data System (ADS)

    Zhao, Haitao; Major, Arkady

    2016-06-01

    Simultaneous dual-wavelength laser oscillation with orthogonal polarizations has been observed and analyzed in a continuous wave N g-cut Yb:KGW oscillator. Without inserting any optical elements for polarization control, the N m- and N p-polarized modes, each of which possessed a distinct wavelength, coexisted and switched twice in two power regimes as the pump power was varied. The two wavelengths and their separation slightly depended on output coupling level. The wavelength switching and coexistence was studied and explained by considering the thermal and spectral anisotropy of the Yb:KGW crystals, which led to polarization-dependent reabsorption loss in the unpumped regions of the crystal. The maximum average output power obtained in the dual-wavelength regime was 4.6 W.

  9. High-temperature thermoelectric studies of A {sub 11}Sb{sub 10} (A=Yb, Ca)

    SciTech Connect

    Brown, Shawna R.; Kauzlarich, Susan M. Gascoin, Franck; Jeffrey Snyder, G.

    2007-04-15

    Large samples (6-8 g) of Yb{sub 11}Sb{sub 10} and Ca{sub 11}Sb{sub 10} have been synthesized using a high-temperature (1275-1375 K) flux method. These compounds are isostructural to Ho{sub 11}Ge{sub 10}, crystallizing in the body-centered, tetragonal unit cell, space group I4/mmm, with Z=4. The structure consists of antimony dumbbells and squares, reminiscent of Zn{sub 4}Sb{sub 3} and filled Skutterudite (e.g., LaFe{sub 4}Sb{sub 12}) structures. In addition, these structures can be considered Zintl compounds; valence precise semiconductors with ionic contributions to the bonding. Differential scanning calorimetry (DSC), thermogravimetry (TG), resistivity ({rho}), Seebeck coefficient ({alpha}), thermal conductivity ({kappa}), and thermoelectric figure of merit (zT) from room temperature to at minimum 975 K are presented for A {sub 11}Sb{sub 10} (A=Yb, Ca). DSC/TG were measured to 1400 K and reveal the stability of these compounds to {approx}1200 K. Both A {sub 11}Sb{sub 10} (A=Yb, Ca) materials exhibit remarkably low lattice thermal conductivity ({approx}10 mW/cm K for both Yb{sub 11}Sb{sub 10} and Ca{sub 11}Sb{sub 10}) that can be attributed to the complex crystal structure. Yb{sub 11}Sb{sub 10} is a poor metal with relatively low resistivity (1.4 m{omega} cm at 300 K), while Ca{sub 11}Sb{sub 10} is a semiconductor suggesting that a gradual metal-insulator transition may be possible from a Ca{sub 11-} {sub x} Yb {sub x} Sb{sub 10} solid solution. The low values and the temperature dependence of the Seebeck coefficients for both compounds suggest that bipolar conduction produces a compensated Seebeck coefficient and consequently a low zT. - Graphical abstract: Large samples (6-8 g) of Yb{sub 11}Sb{sub 10} and Ca{sub 11}Sb{sub 10} have been synthesized from a Sn-flux method. Thermoelectric measurements from room temperature to 1075 K have been obtained. Both A {sub 11}Sb{sub 10} (A=Yb, Ca) materials exhibit remarkably low lattice thermal conductivity ({approx}10 m

  10. The peculiarities of local structure of YbNi2 and YbCo2 intermetallics synthesized at high pressure.

    NASA Astrophysics Data System (ADS)

    Chernysheva, O. V.; Menushenkov, A. P.; Tsvyashchenko, A. V.; Fomicheva, L. N.; Ivanov, A. A.; Kuznetsov, A. V.

    2016-09-01

    Local structure of YbCo2 and YbNi2 was investigated by EXAFS and XANES spectroscopy. It was found that the bond Yb-Co(Ni) has the highest static disorder and its length increases with temperature decrease, while all other bonds remain almost unchanged. This phenomenon may be caused by short-range magnetic ordering at temperatures above the phase transition. XANES measurements above ZIII-Yb absorption edge in YbCo2 and YbNi2 revealed that both compounds have almost the same density of free 5d-states

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

    NASA Astrophysics Data System (ADS)

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

    2016-05-01

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

  12. Origin of laser-induced internal cooling of Yb3+ -doped systems

    NASA Astrophysics Data System (ADS)

    Fernandez, Joaquin R.; Mendioroz, A.; Balda, Rolindes; Voda, M.; Al-Saleh, M.; Garcia-Adeva, A. J.; Adam, Jean-Luc; Lucas, Jacques

    2002-04-01

    Laser induced internal cooling has been investigated in a new fluorochloride glass (CNBZn) and a fluoride glass (BIG) doped with 2.1x1020 Yb3+ ions/cm3 and in a Kpb2Cl5 crystal doped with 5x1019 Yb3+ by using collinear photothermal deflection and conventional laser excitation spectroscopies under high photon irradiances. The cooling efficiency for CNBZn glass which is approximately 2% relative to the absorbed laser power at 1010 nm and 300 K falls about 20% at 77 K. The cooling efficiency for BIG glass was only approximately 6% at room temperature. For the Yb3+ doped Kpb2Cl5 crystal we have shown internal laser cooling with a cooling efficiency of about 0.2% at room temperature. This is the third ytterbium-doped crystal, after Kgd(WO4) (Ref.10) and YAG (Ref.11), in which anti-Stokes laser-induced internal cooling has been demonstrated. The observed temperature dependence of the cooling process can be explained by a simple model accounting for the photon-ion- photon interaction.

  13. Lu-Hf and Sm-Nd Isotopic Studies of Shergottites and Nakhlites: Implications for Martian Mantle Sources

    NASA Technical Reports Server (NTRS)

    Debaille, V.; Yin, Q.-Z.; Brandon, A. D.; Jacobsen, B.; Treiman, A. H.

    2007-01-01

    We present a new Lu-Hf and Sm-Nd isotope systematics study of four enriched shergottites (Zagami, Shergotty, NWA856 and Los Angeles), and three nakhlites (Nakhla, MIL03346 and Yamato 000593) in order to further understand processes occurring during the early differentiation of Mars and the crystallization of its magma ocean. Two fractions of the terrestrial petrological analogue of nakhlites, the Archaean Theo's flow (Ontario, Canada) were also measured. The coupling of Nd and Hf isotopes provide direct insights on the mineralogy of the melt sources. In contrast to Sm/Nd, Lu/Hf ratios can be very large in minerals such as garnet. Selective partial melting of garnet bearing mantle sources can therefore lead to characteristic Lu/Hf signatures that can be recognized with Hf-176/Hf-177Hf ratios.

  14. UPCONVERSION LUMINESCENCE ENHANCEMENT OF NaYF4:Yb3+, Er3+ NANOPARTICLES ON INVERSE OPAL SURFACE

    NASA Astrophysics Data System (ADS)

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

    2014-01-01

    LaPO4 inverse opal photonic crystals with different photonic band gaps were fabricated by template-assisted method. The Yb3+/Er3+ co-doped NaYF4 nanoparticles were deposited on the surfaces of the inverse opals, and their up-conversion emission properties were investigated. The upconversion emissions of Yb3+/Er3+ co-doped NaYF4 nanoparticles on the inverse opal surfaces have been enhanced when the upconversion emission bands of the nanoparticles are in the range of photonic band gaps of the inverse opals, which is attributed to an efficient and selective reflection of photonic band gaps.

  15. Quantum Criticality Beneath the Superconducting Dome in β-YbAlB4

    NASA Astrophysics Data System (ADS)

    Tomita, T.; Kuga, K.; Uwatoko, Y.; Nakatsuji, S.

    2016-02-01

    Yb-based heavy fermion superconductor β-YbAlB4 at 0 K and 0 T at ambient pressure is located near the quantum critical point with strong mixed valiancy. In this type of Yb electron system, we expect that the magnetic order connected to the quantum critical point derives from the applied pressure. We built a pressure-temperature phase diagram for β-YbAlB4 by measuring the electrical resistivity of high quality single crystal at temperatures down to 40 mK under an applied pressure. A strange metal region appeared, showing non-Fermi liquid ρab α T1.5 behavior, which is stable with applied pressure up to 0.4 GPa, even when below the superconducting dome excluded by a magnetic field of 0.1 T. By increasing of pressure above 2.5 GPa, a magnetic order is first generated. Such ambient quantum criticality/superconductivity is unconventional and is detached from the magnetic order.

  16. Optical properties and laser performance of some Yb 3+, Er 3+ and Tm 3+-doped silicates

    NASA Astrophysics Data System (ADS)

    Souriau, J. C.; Romero, R.; Borel, C.; Wyon, Ch.; Li, C.; Moncorgé, R.

    1994-12-01

    This paper reports the main spectroscopic characterizations and laser experiments carried out on two new crystal hosts: the yttrium orthosilicate Y 2SiO 5 and the silicate oxyapatite SrY 4(SiO 4) 3O (hereafter noted SYS), doped with ytterbium and erbium for a 1.55 μm laser emission and with thulium for a 2 μm emission. Four new lasers have been demonstrated at 1.554 μm, 1.576 μm, 1.99 μm and 2.05 μm for respectively Yb, Er:SYS; Yb,Er:Y 2SiO 5; Tm:SYS and Tm:Y 2SiO 5. If for Yb,Er-codoped materials laser performances are still poor compared with the Yb,Er phosphate glass, the Tm-doped materials exhibit laser performances similar to the Tm: YAG and look very promising.

  17. 981 nm Yb:KYW laser intracavity pumped at 912 nm and frequency-doubling for an emission at 490.5 nm

    NASA Astrophysics Data System (ADS)

    Lü, Y. F.; Zhang, X. H.; Xia, J.; Chen, R.; Jin, G. Y.; Wang, J. G.; Li, C. L.; Ma, Z. Y.

    2010-05-01

    We present an Yb:KY(WO4)2 (Yb:KYW) laser emitting at 981 nm intracavity pumped by a 912 nm diode-pumped Nd:GdVO4 laser. A 808 nm diode laser is used to pump the Nd:GdVO4 crystal emitting at 912 nm, and the Yb:KYW laser emitting at 981 nm intracavity pumped at 912 nm. This configuration enabled us to indirectly diode-pump this ytterbium doped crystal, and to obtain 1.12 W output power at 981 nm for 19.6 W of incident pump power at 808 nm. Furthermore, intracavity second harmonic generation has also been demonstrated with a power of 106 mW at 490.5 nm by using a LBO nonlinear crystal.

  18. Ytterbium-doped borate fluoride laser crystals and lasers

    DOEpatents

    Schaffers, K.I.; DeLoach, L.D.; Payne, S.A.; Keszler, D.A.

    1997-10-14

    A new class of solid state laser crystals and lasers are formed from Yb-doped borate fluoride host crystals. The general formula for the host crystals is MM{prime}(BO{sub 3})F, where M, M{prime} are monovalent, divalent aria trivalent metal cations. A particular embodiment of the invention is Yb-doped BaCaBO{sub 3}F (Yb:BCBF). BCBF and some of the related derivative crystals are capable of nonlinear frequency conversion, whereby the fundamental of the laser is converted to a longer or shorter wavelength. In this way, these new crystals can simultaneously serve as self-frequency doubling crystals and laser materials within the laser resonator. 6 figs.

  19. Ytterbium-doped borate fluoride laser crystals and lasers

    DOEpatents

    Schaffers, Kathleen I.; DeLoach, Laura D.; Payne, Stephen A.; Keszler, Douglas A.

    1997-01-01

    A new class of solid state laser crystals and lasers are formed from Yb-doped borate fluoride host crystals. The general formula for the host crystals is MM'(BO.sub.3)F, where M, M' are monovalent, divalent aria trivalent metal cations. A particular embodiment of the invention is Yb-doped BaCaBO.sub.3 F (Yb:BCBF). BCBF and some of the related derivative crystals are capable of nonlinear frequency conversion, whereby the fundamental of the laser is converted to a longer or shorter wavelength. In this way, these new crystals can simultaneously serve as self-frequency doubling crystals and laser materials within the laser resonator.

  20. Test beam results of a high granularity LuAG fibre calorimeter prototype

    NASA Astrophysics Data System (ADS)

    Benaglia, A.; Lucchini, M.; Pauwels, K.; Tully, C.; Medvedeva, T.; Heering, A.; Dujardin, C.; Kononets, V.; Lebbou, K.; Aubry, N.; Faraj, S.; Ferro, G.; Lecoq, P.; Auffray, E.

    2016-05-01

    The progresses in the micropulling-down technique allow heavy scintillating crystals to be grown directly into a fibre geometry of variable shape, length and diameter. Examples of materials that can be grown with this technique are Lutetium Aluminum Garnets (LuAG, Lu3Al5O12) and Yttrium Aluminum Garnets (YAG, Y3Al5O12). Thanks to the flexibility of this approach, combined with the high density and good radiation hardness of the materials, such a technology represents a powerful tool for the development of future calorimeters. As an important proof of concept of the application of crystal fibres in future experiments, a small calorimeter prototype was built and tested on beam. A grooved brass absorber (dimensions 26cm×7cm×16cm) was instrumented with 64 LuAG fibres, 56 of which were doped with Cerium, while the remaining 8 were undoped. Each fibre was readout individually using 8 eightfold Silicon Photomultiplier arrays, thus providing a highly granular description of the shower development inside the module as well as good tracking capabilities. The module was tested at the Fermilab Test Beam Facility using electrons and pions in the 2-16 GeV energy range. The module performance as well as fibre characterization results from this beam test are presented.

  1. Test beam results of a high granularity LuAG fibre calorimeter prototype

    NASA Astrophysics Data System (ADS)

    Benaglia, A.; Lucchini, M.; Pauwels, K.; Tully, C.; Medvedeva, T.; Heering, A.; Dujardin, C.; Kononets, V.; Lebbou, K.; Aubry, N.; Faraj, S.; Ferro, G.; Lecoq, P.; Auffray, E.

    2016-05-01

    The progresses in the micropulling-down technique allow heavy scintillating crystals to be grown directly into a fibre geometry of variable shape, length and diameter. Examples of materials that can be grown with this technique are Lutetium Aluminum Garnets (LuAG, Lu3Al5O12) and Yttrium Aluminum Garnets (YAG, Y3Al5O12). Thanks to the flexibility of this approach, combined with the high density and good radiation hardness of the materials, such a technology represents a powerful tool for the development of future calorimeters. As an important proof of concept of the application of crystal fibres in future experiments, a small calorimeter prototype was built and tested on beam. A grooved brass absorber (dimensions 26cm×7cm×16cm) was instrumented with 64 LuAG fibres, 56 of which were doped with Cerium, while the remaining 8 were undoped. Each fibre was readout individually using 8 eightfold Silicon Photomultiplier arrays, thus providing a highly granular description of the shower development inside the module as well as good tracking capabilities. The module was tested at the Fermilab Test Beam Facility using electrons and pions in the 2–16 GeV energy range. The module performance as well as fibre characterization results from this beam test are presented.

  2. The growth and defect structure of CdF{sub 2} and nonstoichiometric Cd{sub 1-x}R{sub x}F{sub 2+x} phases (R are rare earth elements or in): Part VI. The optical properties of Cd{sub 0.9}R{sub 0.1}F{sub 2.1} crystals

    SciTech Connect

    Konstantinova, A. F.; Glushkova, T. M.; Buchinskaya, I. I.; Krivandina, E. A.; Sobolev, B. P.

    2009-07-15

    The optical properties of the isoconcentration series of Cd{sub 0.9}R{sub 0.1}F{sub 2.1} crystals (R = Y, La, Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, Tm, Yb, or Lu) grown from a melt by the Bridgman method have been investigated. The crystals have an anomalous birefringence ({approx}10{sup -6}) nonuniformly distributed over the sample diameter; the dichroism in them does not exceed 10{sup -9}. Scanning using a spectral modulator showed the nonuniform distribution of rare earth elements over the crystal diameter. The refractive indices n have been measured at wave-lengths of 0.436, 0.546, and 0.589 {mu}m. The character of change in n along the rare-earth series is nonuniform and similar to the change in n in Sr{sub 0.9}R{sub 0.1}F{sub 2.1} crystals. It is shown that the refractive indices in Cd{sub 1-x}R{sub x}F{sub 2+x} crystals, depending on the RF{sub 3} content, can be estimated using the method of molecular refraction additivity.

  3. Rare earth doped LiYbF{sub 4} phosphors with controlled morphologies: Hydrothermal synthesis and luminescent properties

    SciTech Connect

    Huang, Wenjuan; Lu, Chunhua; Jiang, Chenfei; Jin, Junyang; Ding, Mingye; Ni, Yaru; Xu, Zhongzi

    2012-06-15

    Highlights: ► LiYbF{sub 4} microparticles as an excellent upconverting materials. ► High temperature and long time can favor high crystalline LiYbF{sub 4} microparticles. ► The shape of LiYbF{sub 4} microparticles can be tuned by the molar ratio of EDTA to Yb{sup 3+}. ► Bright green emission can be obtained by changing the doping concentration of Er{sup 3+}. -- Abstract: High quality monodisperse LiYbF{sub 4} microparticles with shape of octahedron had been prepared via a facile hydrothermal route. The crystalline phase, size, morphology and luminescence properties were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), photoluminescence (PL) spectra and Commission Internationale de L’Eclairage (CIE 1931) chromaticity coordinates, respectively. The influences of reaction temperature, reaction time and the molar ratio of EDTA to Yb{sup 3+} on the crystal phases and shapes of as-prepared products had been investigated in detail. The upconversion (UC) luminescence properties of LiYb{sub 1−x}F{sub 4}:xEr{sup 3+} (x =0.1, 0.2, 0.5, 1, 2, 5 and 10 mol%) particles with octahedral microstructures were studied under 976 nm excitation. The results showed that the luminescence colors of the corresponding products could be tuned to bright green by changing the doping concentration of Er{sup 3+} ion. The luminescence mechanisms for the doped Er{sup 3+} ion were thoroughly analyzed, showing great potential in applications such as biolabels, displays and other optical technologies.

  4. Preparation and characterization of optical spectroscopy of Lu 2O 3:Eu nanocrystals

    NASA Astrophysics Data System (ADS)

    Xu, Mei; Zhang, Weiping; Dong, Ning; Jiang, Yin; Tao, Ye; Yin, Min

    2005-02-01

    Nanoscale Lu 2O 3:Eu powders were prepared by solution combustion synthesis. X-ray diffraction (XRD), high-resolution electronic microscope (HREM), Fourier transform infrared spectroscopy (FT-IR), excitation and emission spectra, as well as fluorescent decay curves were measured to characterize the structure and luminescent properties of the samples. The results show that the compound of composition Lu 2O 3 crystallizes in pure cubic structure. By changing the ratio of glycine to nitrate in the combustion process, the particle size varies from 40 nm to less than 5 nm. The emission and excitation spectra strongly depend on the particle size of the samples. Novel emission band, red-shift of charge transfer band (CTB) and shortening of lifetime were observed in nanoscale samples.

  5. First-principles study of electronic and elastic properties of LuAl3

    NASA Astrophysics Data System (ADS)

    Shukla, Pushplata; Shrivastava, Deepika; Sanyal, Sankar P.

    2016-05-01

    A systematic theoretical study of electronic structure of rare earth intermetallic LuAl3 has been carried out using full potential linearized augmented plane wave (FP-LAPW) method based on density functional theory (DFT) within the generalized gradient approximation(GGA) for exchange and correlation potential. The ground state properties such as lattice constant (ao), bulk modulus (B) and pressure derivative of bulk modulus (Bˈ) were evaluated. LuAl3 has the cubic AuCu3 type crystal structure. The electronic properties of this compound have been analyzed quantatively from band structure and DOS. It is clear from band structure that this compound is metallic in nature. The calculated elastic constants infer that this compound is mechanically stable.

  6. A low temperature study of antiferromagnetic YbVO4 by NMR thermally detected by nuclear orientation

    NASA Astrophysics Data System (ADS)

    Hutchison, W. D.; Prandolini, M. J.; Harker, S. J.; Chaplin, D. H.; Bowden, G. J.; Bleaney, B.

    1999-09-01

    NMR-TDNO results using an external 60CoCo (hcp) nuclear orientation thermometer for non-irradiated, single crystal, antiferromagnetic YbVO4 are compared with those obtained earlier with neutron activated samples using both internal and external γ-ray thermometers. Detailed comparisons are made for the 171Yb (I=1/2, 14.31% abundant) stable nucleus. This strongly asymmetric, largely homogeneous, resonance lineshape was retained and is readily power broadened. Extremely broad, field-dependent homogeneous thermometric responses are observed in the expected frequency range for the quadrupolar stable nucleus 173Yb (I=5/2, 16.13% abundant) for both irradiated and non-irradiated samples.

  7. Room temperature diode-pumped Yb:CaYAlO4 laser with near quantum limit slope efficiency

    NASA Astrophysics Data System (ADS)

    Tan, W. D.; Tang, D. Y.; Xu, X. D.; Li, D. Z.; Zhang, J.; Xu, C. W.; Cong, Z. H.; Xu, J.

    2011-03-01

    The room temperature continuous wave (CW) laser performance of a compact Yb:CaYAlO4 (Yb:CYA) laser with near quantum limit slope efficiency is demonstrated. Pumped with a CW diode operating at 979 nm, the laser emitted a maximum CW output power of 2.3 W at 1050 nm. The corresponding slope efficiency was found to be 92% while the optical to optical conversion efficiency was 70%. The laser can also be continuously tuned from 1008 nm to 1063 nm using an intra-cavity SF 10 prism. The round trip cavity losses of Yb:CYA was 0.6% while the loss coefficient of the crystal was 0.01 cm-1.

  8. Magnetic and dielectric properties of YbFe{sub 2-x}Mn{sub x}O{sub 4} (0<=x<=1)

    SciTech Connect

    Yoshii, Kenji; Ikeda, Naoshi; Michiuchi, Takamasa; Yokota, Yusuke; Okajima, Yuka; Yoneda, Yasuhiro; Matsuo, Yoji; Horibe, Yoichi; Mori, Shigeo

    2009-07-15

    We have investigated the magnetic and dielectric properties of YbFe{sub 2-x}Mn{sub x}O{sub 4} (0<=x<=1), which is an Fe-site-substituted system of new multiferroic oxides RFe{sub 2}O{sub 4} (R=Y, Ho-Lu). X-ray diffraction measurements show that a solid solution is formed between YbFe{sub 2}O{sub 4} (x=0) and YbFeMnO{sub 4} (x=1) for 0<=x<=1, whereas only compounds with x=1 (i.e., RM{sub 1}M{sub 2}O{sub 4}; M{sub 1} and M{sub 2}=trivalent and divalent cations, respectively) have been known for the Fe-site substitution in RFe{sub 2}O{sub 4}. The valence of the Mn ion is determined to be {approx}2+, consistently with the suppression of low-temperature magnetization by the Mn substitution. The magnetic transition temperature (T{sub N}) and the dielectric constant (epsilon') decrease monotonically with increasing x. This result plausibly confirms that the magnetic and dielectric properties in oxides isostructural with RFe{sub 2}O{sub 4} are governed by the electron transfer between Fe-site ions, unlike ordinary ferroelectrics and dielectrics, in which the ionic displacement plays a key role. The possibility for application is briefly discussed as well. - Graphical abstract: Dielectric constant (epsilon') and magnetic transition temperature (T{sub N}) of YbFe{sub 2-x}Mn{sub x}O{sub 4} (0<=x<=1), which is a solid-solution system of new multiferroic oxides RFe{sub 2}O{sub 4} (R=Y, Ho-Lu).

  9. Self-frequency-doubled vibronic yellow Yb:YCOB laser at the wavelength of 570  nm.

    PubMed

    Fang, Qiannan; Lu, Dazhi; Yu, Haohai; Zhang, Huaijin; Wang, Jiyang

    2016-03-01

    A watt-level self-frequency-doubled yellow laser at the 570 nm wavelength was realized by taking advantage of the vibronic emission of a Yb3+ doped calcium yttrium oxoborate (Yb:YCOB) crystal cut along the optimized direction out of the principal planes with the maximum effective nonlinear coefficient. Fluorescence spectroscopic properties of Yb:YCOB were studied, which showed that it had broad and anisotropic vibronic emission with a small peak at ∼1130  nm. By suppressing the electronic emission, the polarized vibronic Yb:YCOB radiation was realized with the fundamental wavelength shifting from 1130 nm to 1140 nm. By employing the self-frequency-doubling behavior of Yb:YCOB, the self-frequency-doubled yellow laser was achieved with a maximum output power of 1.08 W at 570 nm. This work provides an unprecedented and efficient way to generate yellow lasers with a compact microchip structure that may have promising applications in some regimes including medicine, entertainment, and scientific research. PMID:26974101

  10. Self-frequency-doubled vibronic yellow Yb:YCOB laser at the wavelength of 570  nm.

    PubMed

    Fang, Qiannan; Lu, Dazhi; Yu, Haohai; Zhang, Huaijin; Wang, Jiyang

    2016-03-01

    A watt-level self-frequency-doubled yellow laser at the 570 nm wavelength was realized by taking advantage of the vibronic emission of a Yb3+ doped calcium yttrium oxoborate (Yb:YCOB) crystal cut along the optimized direction out of the principal planes with the maximum effective nonlinear coefficient. Fluorescence spectroscopic properties of Yb:YCOB were studied, which showed that it had broad and anisotropic vibronic emission with a small peak at ∼1130  nm. By suppressing the electronic emission, the polarized vibronic Yb:YCOB radiation was realized with the fundamental wavelength shifting from 1130 nm to 1140 nm. By employing the self-frequency-doubling behavior of Yb:YCOB, the self-frequency-doubled yellow laser was achieved with a maximum output power of 1.08 W at 570 nm. This work provides an unprecedented and efficient way to generate yellow lasers with a compact microchip structure that may have promising applications in some regimes including medicine, entertainment, and scientific research.

  11. Er{sup 3+}/Yb{sup 3+}co-doped bismuth molybdate nanosheets upconversion photocatalyst with enhanced photocatalytic activity

    SciTech Connect

    Adhikari, Rajesh; Gyawali, Gobinda; Cho, Sung Hun; Narro-García, R.; Sekino, Tohru; Lee, Soo Wohn

    2014-01-15

    In this paper, we report the microwave hydrothermal synthesis of Er{sup 3+}/Yb{sup 3+} co-doped Bi{sub 2}MoO{sub 6} upconversion photocatalyst. Crystal structure, morphology, elemental composition, optical properties and BET surface area were analyzed in detail. Infrared to visible upconversion luminescence at 532 nm and 546 nm of the co-doped samples was investigated under excitation at 980 nm. The results revealed that the co-doping of Er{sup 3+}/Yb{sup 3+} into Bi{sub 2}MoO{sub 6} exhibited enhanced photocatalytic activity for the decomposition of rhodamine B under simulated solar light irradiation. Enhanced photocatalytic activity can be attributed to the energy transfer between Er{sup 3+}/Yb{sup 3+} and Bi{sub 2}MoO{sub 6} via infrared to visible upconversion from Er{sup 3+}/Yb{sup 3+} ion and higher surface area of the Bi{sub 2}MoO{sub 6} nanosheets. Therefore, this synthetic approach may exhibit a better alternative to fabricate upconversion photocatalyst for integral solar light absorption. - Graphical abstract: Schematic illustration of the upconversion photocatalysis. Display Omitted - Highlights: • Er{sup 3+}/Yb{sup 3+} co-doped Bi{sub 2}MoO{sub 6} upconversion photocatalyst is successfully synthesized. • We obtained the nanosheets having high surface area. • Upconversion of IR to visible light was confirmed. • Upconversion phenomena can be utilized for effective photocatalysis.

  12. Cryogenically-cooled Yb:YGAG ceramic picosecond oscillator

    NASA Astrophysics Data System (ADS)

    Mužik, J.; Jelínek, M.; Miura, T.; Smrž, M.; Endo, A.; Mocek, T.; Kubeček, V.

    2016-04-01

    In this work, a passively mode-locked Yb:YGAG (Yb:Y3Ga2Al3O12) ceramic laser generating picosecond pulses at liquid-nitrogen temperature is demonstrated. The Yb:YGAG has a similar structure to Yb:YAG, but its emission bandwidth at cryogenic temperature remains much broader, which is advantageous for ultrashort pulse generation and amplification. Using this laser material, a stable train of pulses at a wavelength of 1026 nm was obtained, with measured pulse duration of 2.4 ps, which is more than four times shorter than that achieved with a cryogenically-cooled Yb:YAG.

  13. Layered Yb:YAG ceramics produced by two different methods: processing, characterization and comparison

    NASA Astrophysics Data System (ADS)

    Hostaša, Jan; Esposito, Laura; Biasini, Valentina; Piancastelli, Andreana; Vannini, Matteo; Toci, Guido

    2016-03-01

    The use of Yb:YAG ceramic gain media in solid state lasers has been of growing interest for high repetition rate and high power lasers. Probably the most important advantage of ceramic production technology in comparison with that of single crystals is the flexibility of shaping methods that allow the production of near-net-shape components with a welldefined internal structure. In the case of Yb:YAG with dopant distribution designed accordingly to the pumping and cooling geometry the efficiency of the laser device can be enhanced by mitigating thermal lensing effects. The presented work reports on Yb:YAG transparent ceramics composed of layers with different Yb doping produced by two different shaping methods: dry pressing of spray-dried powders and tape casting, all sintered under high vacuum. The selected geometry of materials was based on numerical simulations. Microstructure of the produced materials was characterized by SEM and EDX with a particular attention to the dopant content across the layers. The optical quality of produced ceramics was characterized and discussed in connection with the microstructure and laser emission results. Output power of nearly 7 W and slope efficiency 58.1 % were obtained in QCW regime from bilayered 0-10 %Yb:YAG. In the case of multilayered materials higher scattering losses were observed. The comparison between the two processing methods highlighted that the tape-cast materials provided higher optical uniformity and the diffusion zone between the single layers with different dopant content was about 150 nm compared to about 250 nm in samples produced by pressing of powders.

  14. Pressure dependence of the emission in CaF2 : Yb2+

    NASA Astrophysics Data System (ADS)

    Mahlik, S.; Lazarowska, A.; Grinberg, M.; Wells, J.-P. R.; Reid, M. F.

    2015-08-01

    We present a detailed spectroscopic investigation of CaF2 doped with Yb2+ performed at high hydrostatic pressure which is applied in a diamond anvil cell. At ambient pressure and at temperatures lower than 175 K, the luminescence consists of a single broad band peaked at 18 500 cm-1, attributed to the recombination of impurity-trapped excitons. Increasing pressure causes the luminescence to be observable at higher temperature. At a pressure of 72 kbar luminescence can be observed up to 275 K. The emission lineshape does not strongly depend on pressure below 85 kbar. However, at 85 kbar it is blue shifted to 21 630 cm-1. This is attributed to the known phase transition of the CaF2 crystal from cubic to the orthorhombic phase. The absolute energy of the ground and 4f135d states of Yb2+ as well as the energy of the impurity-trapped exciton with respect to valence and conduction bands have been estimated. The results, are discussed in comparison with the pressure dependences observed for the luminescence of BaF2 : Eu2+ and CaF2 : Eu2+. The difference between the spectral properties of Eu2+ and Yb2+ is attributable to the fact that the ground and 4f65d states of Eu2+ are placed deeper in the CaF2 bandgap than the ground and excited 4f135d states of Yb2+, whereas the energies of the impurity-trapped exciton states for Yb2+ and Eu2+ with respect to the conduction band are approximately the same.

  15. A study of response of a LuYAP:Ce array with innovative assembling for PET

    NASA Astrophysics Data System (ADS)

    Pani, Roberto; Cinti, Maria Nerina; Scafè, Raffaele; Bennati, Paolo; Lo Meo, Sergio; Preziosi, Enrico; Pellegrini, Rosanna; De Vincentis, Giuseppe; Sacco, Donatella; Fabbri, Andrea

    2015-09-01

    We propose the characterization of a first array of 10×10 Lutetium Yttrium Orthoaluminate Perovskite (LuYAP:Ce) crystals, 2 mm×2 mm×10 mm pixel size, with an innovative assembling designed to enhance light output, uniformity and detection efficiency. The innovation consists of the use of 0.015 mm thick dielectric coating as inter-pixel light-insulators, manufactured by Crytur (Czech Republic) intended to improve crystal insulation and then light collection. Respect to the traditional treatment with 0.2 mm of white epoxy, a thinner pixel gap enhances packing fraction up to 98% with a consequent improvement of detection efficiency. Spectroscopic characterization of the array was performed by a Hamamatsu R6231 photomultiplier tube. A pixel-by-pixel scanning with a collimated 99mTc radioisotope (140 keV photon energy) highlighted a deviation in pulse height close to 3.5% respect to the overall mean value. Meanwhile, in term of energy resolution a difference between the response of single pixel and the array of about 10% was measured. Results were also supported and validated by Monte Carlo simulations performed with GEANT4. Although the dielectric coating pixel insulator cannot overcome the inherent limitations of LuYAP crystal due to its self-absorption of light (still present), this study demonstrated that the new coating treatment allows better light collection (nearly close to the expected one) with in addition a very good uniformity between different pixels. These results confirm the high potentiality of this coating for any other crystal array suited for imaging application and new expectations for the use of LuYAP for PET systems.

  16. The influence of critical current density of Bi-2212 superconductors by defects after Yb-doping

    NASA Astrophysics Data System (ADS)

    Lu, Tianni; Zhang, Cuiping; Guo, Shengwu; Wu, Yifang; Li, Chengshan; Zhou, Lian

    2015-12-01

    Bi2Sr2Ca1-xYbxCu2O8+δ (Bi-2212) single crystals with x = 0.000, 0.005, 0.010 and 0.020 have been prepared by self-flux method. The influences of Yb doping on the formation of the dislocations in the lattice structures, as well as the related current carrying capability are investigated. Due to the SQUID measurement and the Bean model calculation, the maximum critical current density (Jc) is obtained when the Yb doping content is x = 0.010, though the Tc and the carrier concentration are not in the optimal region. Based on the HRTEM analyses of the Ca-O and Cu-O2 layers, the optimal dislocation density in the Cu-O2 layers is deduced according to the number of the dislocations per unit area. Besides, the sizes of the dislocations also prove the effectiveness of Yb substitution on the enhancement of the current carrying capability in Bi-2212 single crystals.

  17. Superconductivity in Y3Ru4Ge13 and Lu3Os4Ge13: A comparative study

    NASA Astrophysics Data System (ADS)

    Prakash, Om; Thamizhavel, A.; Ramakrishnan, S.

    2014-12-01

    A variety of unconventional superconductors have low carrier density as a common factor. However, the underlying mechanism of superconductivity in such low carrier density systems is not well understood. Besides, small carrier density is an unfavourable component for conventional superconductivity as described by the Bardeen-Cooper-Schrieffer (BCS) theory. Therefore, studying low carrier density systems can lead to a better understanding in such systems. In this paper, we report superconductivity property studies in low carrier density systems, Y3Ru4Ge13 and Lu3Os4Ge13, using various experimental techniques. Single crystals of Y3Ru4Ge13 and Lu3Os4Ge13 have been grown using the Czochralski crystal pulling method in a tetra-arc furnace. The x-ray diffraction experiment reveals that both compounds crystallize in cubic structure (space group Pm3n, no. 223). The transport, magnetization and heat capacity measurements show that Y3Ru4Ge13 single crystal undergoes a superconducting transition at 2.85 K, whereas, Lu3Os4Ge13 becomes superconductor at 3.1 K.

  18. Rise in power of Yb:YCOB for green light generation by self-frequency doubling.

    PubMed

    Khaled, Federico; Loiseau, Pascal; Aka, Gérard; Gheorghe, Lucian

    2016-08-01

    Spectroscopic properties and self-frequency-doubling laser performance are presented for Yb:YCa4O(BO3)3 (Yb:YCOB) crystals oriented for type I second-harmonic generation in the ZX plane. In a plane-concave cavity 10 cm long, up to 330 mW of green light (544.5 nm) is obtained for 14.7 W of laser diode incident pump power. Broad emission bands and weak anisotropy in the 1060-1100 nm range between the two eigenstates of polarization may explain the instability of the self-frequency-doubled output power.

  19. Fragile antiferromagnetism in the heavy-fermion compound YbBiPt

    SciTech Connect

    Ueland, Benjamin G.; Kreyssig, Andreas; Prokes, K.; Lynn, J. W.; Harriger, L. W.; Pratt, D. K.; Singh, D. K.; Heitmann, T. W.; Sauerbrei, Samantha; Saunders, Scott M.; Mun, E. D.; Budko, Serguei L.; McQueeney, Robert J.; Canfield, Paul C.; Goldman, Alan I.

    2014-05-08

    We report results from neutron scattering experiments on single crystals of YbBiPt that demonstrate antiferromagnetic order characterized by a propagation vector, τAFM = (121212), and ordered moments that align along the [1 1 1] direction of the cubic unit cell. We describe the scattering in terms of a two-Gaussian peak fit, which consists of a narrower component that appears below TN≈0.4 K and corresponds to a magnetic correlation length of ξn≈ 80 Å, and a broad component that persists up to T*≈ 0.7 K and corresponds to antiferromagnetic correlations extending over ξb≈ 20 Å. Our results illustrate the fragile magnetic order present in YbBiPt and provide a path forward for microscopic investigations of the ground states and fluctuations associated with the purported quantum critical point in this heavy-fermion compound.

  20. High-power, 1-ps, all-Yb:YAG thin-disk regenerative amplifier.

    PubMed

    Fattahi, Hanieh; Alismail, Ayman; Wang, Haochuan; Brons, Jonathan; Pronin, Oleg; Buberl, Theresa; Vámos, Lénárd; Arisholm, Gunnar; Azzeer, Abdallah M; Krausz, Ferenc

    2016-03-15

    We report a 100 W, 20 mJ, 1-ps, all-Yb:YAG thin-disk regenerative amplifier seeded by a microjoule-level Yb:YAG thin-disk Kerr-lens mode-locked oscillator. The regenerative amplifier is implemented in a chirped pulse amplification system and operates at an ambient temperature in air, delivering ultrastable output pulses at a 5 kHz repetition rate and with a root mean square power noise value of less than 0.5%. Second harmonic generation of the amplifier's output in a 1.5 mm-thick BBO crystal results in more than 70 W at 515 nm, making the system an attractive source for pumping optical parametric chirped pulse amplifiers in the visible and near-infrared spectral ranges.

  1. High-power, 1-ps, all-Yb:YAG thin-disk regenerative amplifier.

    PubMed

    Fattahi, Hanieh; Alismail, Ayman; Wang, Haochuan; Brons, Jonathan; Pronin, Oleg; Buberl, Theresa; Vámos, Lénárd; Arisholm, Gunnar; Azzeer, Abdallah M; Krausz, Ferenc

    2016-03-15

    We report a 100 W, 20 mJ, 1-ps, all-Yb:YAG thin-disk regenerative amplifier seeded by a microjoule-level Yb:YAG thin-disk Kerr-lens mode-locked oscillator. The regenerative amplifier is implemented in a chirped pulse amplification system and operates at an ambient temperature in air, delivering ultrastable output pulses at a 5 kHz repetition rate and with a root mean square power noise value of less than 0.5%. Second harmonic generation of the amplifier's output in a 1.5 mm-thick BBO crystal results in more than 70 W at 515 nm, making the system an attractive source for pumping optical parametric chirped pulse amplifiers in the visible and near-infrared spectral ranges. PMID:26977650

  2. Epitaxial growth and electronic properties of mixed valence YbAl3 thin films

    NASA Astrophysics Data System (ADS)

    Chatterjee, Shouvik; Sung, Suk Hyun; Baek, David J.; Kourkoutis, Lena F.; Schlom, Darrell G.; Shen, Kyle M.

    2016-07-01

    We report the growth of thin films of the mixed valence compound YbAl3 on MgO using molecular-beam epitaxy. Employing an aluminum buffer layer, epitaxial (001) films can be grown with sub-nm surface roughness. Using x-ray diffraction, in situ low-energy electron diffraction, and aberration-corrected scanning transmission electron microscopy, we establish that the films are ordered in the bulk as well as at the surface. Our films show a coherence temperature of 37 K, comparable to that reported for bulk single crystals. Photoelectron spectroscopy reveals contributions from both f13 and f12 final states establishing that YbAl3 is a mixed valence compound and shows the presence of a Kondo Resonance peak near the Fermi-level.

  3. Lu{sub 2}O{sub 3}:Eu{sup 3+} glass ceramic films: Synthesis, structural and spectroscopic studies

    SciTech Connect

    Carrera Jota, M.L.; García Murillo, A.; Morales Ramírez, A. de J.; Rosa Cruz, E. de la; Kassiba, Abdelhadi

    2014-03-01

    Graphical abstract: - Highlights: • Lu{sub 2}O{sub 3}:Eu{sup 3+}@SiO{sub 2} films were synthesized by sol–gel and by dip-coating technique. • Effects of incorporating PVP on structural properties were studied. • Effects of incorporating silica (SiO{sub 2}) luminescence characteristics were analyzed. • X-ray diffraction results showed that Lu{sub 2}O{sub 3}:Eu{sup 3+}@SiO{sub 2} crystallizes at 700 °C. • The 611 nm emission for the Lu:Si = 8:1 system presented an improvement. - Abstract: For the first time, transparent and crack free europium-doped lutetia silica sol–gel films were synthesized using the dip-coating technique on silica quartz substrates. In this study, we examined the effects of incorporating polyvinylpyrrolidone (PVP) and silica (SiO{sub 2}) into different precursor solutions for different Lu–Si molar ratios: 4:1, 6:1, 8:1 and 10:1. Different systems, such as Lu{sub 2}O{sub 3}:Eu{sup 3+}@SiO{sub 2} (using the above Lu:Si molar ratios), were synthesized by sol–gel and by dip-coating technique, employing acetylacetonate lutetium and tetraethylorthosilicate as Lu and Si precursors, in order to produce Lu{sub 2}O{sub 3}:Eu{sup 3+} (5 mol%)@SiO{sub 2} glass–ceramic films. The film microstructure was studied by microRaman spectroscopy (MRS) and X-ray diffraction (XRD) for different Lu:Si molar ratios on films annealed at 700 °C. X-ray diffraction results showed that the lutetium oxide cubic phase crystallizes in the silica matrix at 700 °C, and the crystallite size of Lu{sub 2}O{sub 3}:Eu{sup 3+}@SiO{sub 2} films varies from 5 nm to 17 nm according to the respective Lu:Si molar ratios. Opto-geometrical parameters determined by m-lines spectroscopy using a 632.5 nm He–Ne laser showed that the Eu{sup 3+} doped films heat-treated at 700 °C presented a thickness and density of 1.7 μm (8.8 g cm{sup −3}), 970 nm (9.2 g cm{sup −3}), 1 μm (9.3 g cm{sup −3}) and 1.3 μm (9.25 g cm{sup −3}) for the Lu:Si = 4:1, 6:1, 8:1 and 10

  4. Ionic liquid-based hydrothermal synthesis of Lu2O3 and Lu2O3:Eu3+ microcrysals

    NASA Astrophysics Data System (ADS)

    Li, Yinyan; Xu, Shiqing

    2016-09-01

    Uniform and well-defined Lu2O3 and Lu2O3:Eu3+ microarchitectures have been successfully synthesized via a green and facile ionic liquid-based hydrothermal method followed by a subsequent calcination process. Novel 3D micro-rodbundles and 1D microrods of Lu2O3 and Lu2O3:Eu3+ were controllably obtained through this method. X-ray powder diffraction, scanning electron microscopy, transmission electron microscopy and photoluminescence spectra were used to characterize the micromaterials. The proposed formation mechanisms have been investigated on the basis of a series of SEM studies of the products obtained at different hydrothermal durations. The results indicated that hydrothermal temperature and the ionic liquid-tetrabutylammonium hydroxide were two key factors for the formation as well as the morphology control of the Lu2O3 and Lu2O3:Eu3+ microarchitectures.

  5. Spectral and Luminescent Properties of Oxyfluoride Glasses Codoped with (Yb3+, Eu3+) and (Yb3+, Tb3+)

    NASA Astrophysics Data System (ADS)

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

    2016-09-01

    The spectral and luminescent properties of SiO2-PbO-PbF2-CdF2 oxyfl uoride glasses doped with Yb3+, Eu3+, and Tb3+ were investigated. The lifetime τ( 5D0) of Eu3+ in glasses doped with Eu2O3 was 1.73 ms; τ( 5D4) of Tb3+, 2.25 ms. Intense red and green up-conversion luminescence due to cooperative energy transfer from Yb3+—Yb3+ pairs to Eu3+ and Tb3+ was observed for glasses codoped with (Yb3+, Eu3+) and (Yb3+, Tb3+) upon excitation at 960 nm into the Yb3+ absorption band. Down-conversion luminescence of Yb3+ ions in the vicinity of ~1 μm was detected upon excitation by UV light of wavelength 355 nm.

  6. Upcoversion performance improvement of NaYF{sub 4}:Yb, Er by Sn codoping: Enhanced emission intensity and reduced decay time

    SciTech Connect

    Yu, Han; Cao, Wenbing; Huang, Qingming; Ma, En; Zhang, Xinqi; Yu, Jianchang

    2013-11-15

    In this manuscript we report a phenomenon that upconversion emission intensity of Er{sup 3+} was enhanced while decay time constant was decreased obviously by Sn codoping with Yb/Er into hexagonal NaYF{sub 4} synchronously. X-ray powder diffiraction, field emission scanning electron microscope, transmission electron microscopy, X-ray photoelectron spectroscopy, electron spin-resonance spectroscopy and upconversion emission spectra were employed to explore the relation of crystal structure and properties. From these characterizations we found that symmetry of the rare earth ion local crystal field could be tuned by different Sn codoping concentration. For the variable valence property of Sn the local crystal field asymmetry and emission intensity of NaYF{sub 4}:Yb, Er arrived to the maximum when 3 mol% Sn was codoped, while decay time was reduced. The study of this changing tends of upconversion emission intensity and decay time constant may be helpful for design and fabrication of high performance upconversion materials. - Graphical abstract: Variable-valenced Sn is introduced with Yb/Er into NaFY{sub 4} to tune structure and local crystal field. Upconversion emission intensity of Er{sup 3+} was enhanced while decay time constant was decreased. Display Omitted - Highlights: • NaYF{sub 4}: Yb, Er was codoped with different concentration Sn. • Upconversion emission intensity was enhanced while decay time constant was decreased. • Introduction of variable-valenced Sn is effective to tune structure and crystal field of NaFY{sub 4}.

  7. Yb2Pt2Pb: Magnetic frustration in the Shastry-Sutherland lattice

    SciTech Connect

    Kim, M. S.; Bennett, M. C.; Aronson, M. C.

    2008-04-23

    Here, we have synthesized single crystals of Yb2Pt2Pb, which crystallize in the layered U2Pt2Sn-type structure, where planes of Yb ions lie on a triangular network. Here, we report the results of magnetization, specific heat, and electrical resistivity experiments. The lattice constants and high temperature magnetic susceptibility indicate that the Yb ions are trivalent, while the Schottky peaks in the specific heat show that the ground state is a well isolated doublet. A significant magnetic anisotropy is observed, with the ratio of susceptibilities perpendicular and parallel to the magnetic planes differing by as much as a factor of 30 at the lowest temperatures. Antiferromagnetic order occurs at a Néel temperature TN = 2.07 K. Evidence of short range magnetic fluctuations is found in the magnetic susceptibility and electrical resistivity, which have broad peaks above TN, and in the slow development of the magnetic entropy at TN. Our experiments indicate that Yb2Pt2Pb is a quasi-two-dimensional and localized moment system, where strong magnetic frustration may arise from the geometry of the underlying Shastry-Sutherland lattice.

  8. Broadband telecommunication wavelength emission in Yb(3+)-Er(3+)-Tm(3+) co-doped nano-glassceramics.

    PubMed

    Tikhomirov, V K; Driesen, K; Görller-Walrand, C; Mortier, M

    2007-07-23

    Transparent Yb(3+), Er(3+) and Tm(3+) co-doped nano-glass-ceramics 3(SiO(2)2)9(AlO(1.5))31.5(CdF(2))18.5(PbF(2))5.5(ZnF(2)):3.5(Yb-Er-TmF(3)), mol%, have been prepared where co-dopants mostly partition in nano-crystals Pb(1-x) (Yb(3+),Er(3+),Tm(3+))(x)F(2+x) embedded in the glass network. The Yb(3+) ensures high absorption at 980 nm telecommunication pump wavelength and further phonon-mediated energy transfer to Er(3+) and Tm(3+) co-dopants. Er(3+) and Tm(3+) radiate overlapping emission bands from their lowest energy levels, with similar lifetime of about 9 ms, which cover the range between 1.50 to 1.70 mum. The lifetime of all higher levels of Er(3+) and Tm(3+) dopants is shorter than 70 mus due to short inter-dopant distances in the nano-crystals resulting in fast energy transfer to their lowest levels.

  9. High-resolution optical spectroscopy and magnetic properties of Yb3 + in Y2SiO5

    NASA Astrophysics Data System (ADS)

    Welinski, Sacha; Ferrier, Alban; Afzelius, Mikael; Goldner, Philippe

    2016-10-01

    Rare-earth doped crystals are promising systems for quantum information processing. In particular, paramagnetic rare earths could be used to build coherent interfaces with optical and microwave photons. In addition, isotopes with nonzero nuclear spins could provide long-lived states for quantum state storage and processing. Yb3 + is particularly interesting in this respect since it is the only paramagnetic rare earth with a spin-1/2 isotope, which corresponds to the simplest possible level structure. In this paper, we report on the optical and magnetic properties of Yb3 + in the two sites of Y2SiO5 , a commonly used crystal for quantum applications. We measured optical inhomogeneous linewidths, peak absorption coefficients, oscillator strengths, and excited-state lifetimes. The Zeeman tensors were also determined in the ground and excited states, as well as the ground-state hyperfine tensor for the 3+171Yb (I =1/2 ) isotope. These results suggest that Yb3 +:Y2SiO5 is a promising material for applications like solid-state optical and microwave quantum memories.

  10. Tunability of laser based on Yb-doped hot-pressed CaF2 ceramics

    NASA Astrophysics Data System (ADS)

    Sulc, Jan; Doroshenko, Maxim E.; Jelínková, Helena; Basiev, Tasoltan T.; Konyushkin, Vasilii A.; Osiko, Vyacheslav V.

    2012-06-01

    The aim of presented study was an investigation of tunability of diode pumped laser based on hot-pressed Yb:CaF2 ceramics. The tested Yb:CaF2 sample was in the form of 3.5mm thick plane-parallel face-polished plate (without AR coatings). The Yb3+ concentration was 5.5 %. A fiber (core diameter 200 μm, NA= 0.22) coupled laser diode (LIMO, HLU25F200-980) with emission at wavelength 976 nm, was used for longitudinal Yb:CaF2 pumping. The laser diode was operating in the pulsed regime (4 ms pulse length, 20 Hz repetition rate). The duty-cycle 8% ensured a low thermal load even under the maximum diode pumping power amplitude 10W (crystal sample was only air-cooled). This radiation was focused into the crystal (pumping beam waist diameter ~ 170 μm). The 145mm long semi-hemispherical laser resonator consisted of a flat pumping mirror (HR @ 1.01 - 1.09 μm, HT @ 0.97 μm) and curved (r = 150mm) output coupler with a reflectivity of ~ 98% @ 1.01 - 1.09 μm. Tuning of the ytterbium laser was accomplished by using a birefringent filter (single 1.5mm thick quartz plate) placed inside the optical resonator at the Brewster angle between the output coupler and the laser active medium. The extremely broad and smooth tuning was obtained. The laser was continuously tunable over ~ 66nm (from 1015nm to 1081 nm) and the tuning band was mostly limited by free spectral range of used birefringent filter. The tunability FWHM was 40 nm corresponding bandwidth 10 THz results in Fourier limited gaussian pulse width ~ 40 fs (FWHM). The maximum output power amplitude 0.68W was obtained at wavelength 1054nm for absorbed pump power amplitude 6W. The laser slope efficiency was 15%.

  11. Optical properties of CaF2 and Yb3+:CaF2 for laser applications

    NASA Astrophysics Data System (ADS)

    Stäblein, Jörg; Pöhl, Karin; Weisleder, Andreas; v. d. Gönna, Gordon; Töpfer, Thomas; Hein, Joachim; Siebold, Mathias

    2011-06-01

    Highly transparent CaF2 has found many applications from the deep UV- to the IR-range. The optical quality and the laser damage threshold are influenced by the purity and the real structure of the crystal. Both properties strongly depend on raw material quality and growth conditions. Production of pure CaF2 single crystals and their characterization are described. The authorś process enables to produce crystals up to diameters of 425mm with an internal transmittance of higher than 99.7% at 193nm (thickness 100mm) and a homogeneity of refractive index below 1ppm for diameters >200mm. A new approach is the growth of Yb3+ doped CaF2 crystals in such furnaces dedicated to large volumes. The advantage of higher volume is a better homogeneity of the dopant concentration and the diffractive index in the crystal. Critical mechanical properties especially of the doped fluoride have to be taken into account. The growth process has to be adopted carefully to avoid stress, cracks and other crystal defects. Data of refractive index homogeneity and stress birefringence are presented. A comparison of doped and undoped crystals is made and an outlook for further improvement is given. The segregation coefficient of the dopant which is important to be near to one is reported. The ratio Yb3+ /Yb2+ is characterized spectroscopically. Differences between top and bottom of the crystal are shown. Results of the real structure evaluation are presented. The most critical feature for high energy applications which are strength and concentration of small angle grain boundaries are compared with that of undoped crystals.

  12. Estimated human absorbed dose of ¹⁷⁷Lu-BPAMD based on mice data: Comparison with ¹⁷⁷Lu-EDTMP.

    PubMed

    Yousefnia, Hassan; Zolghadri, Samaneh; Shanehsazzadeh, Saeed

    2015-10-01

    In this work, the absorbed dose of human organs for (177)Lu-BPAMD was evaluated based on biodistribution studies into the Syrian mice by RADAR method and was compared with (177)Lu-EDTMP as the only clinically used Lu-177 bone-seeking agent. The highest absorbed dose for both (177)Lu-BPAMD and (177)Lu-EDTMP is observed on the bone surface with 8.007 and 4.802 mSv/MBq. Generally, (177)Lu-BPAMD has considerable characteristics compared with (177)Lu-EDTMP and can be considered as a promising agent for the bone pain palliation therapy. PMID:26163291

  13. Plasmon-photon conversion to near-infrared emission from Yb(3+): (Au/Ag-nanoparticles) in tungsten-tellurite glasses.

    PubMed

    Rivera, V A G; Ledemi, Yannick; Pereira-da-Silva, Marcelo A; Messaddeq, Younes; Marega, Euclydes

    2016-01-04

    This manuscript reports on the interaction between (2)F5/2→(2)F7/2 radiative transition from Yb(3+) ions and localized surface plasmon resonance (from gold/silver nanoparticles) in a tungsten-tellurite glass. Such an interaction, similar to the down-conversion process, results in the Yb(3+) emission in the near-infrared region via resonant and non-resonant energy transfers. We associated such effects with the dynamic coupling described by the variations generated by the Hamiltonian HDC in either the oscillator strength, or the local crystal field, i.e. the line shape changes in the emission band. Here, the Yb(3+) ions emission is achieved through plasmon-photon coupling, observable as an enhancement or quenching in the luminescence spectra. Metallic nanoparticles have light-collecting capability in the visible spectrum and can accumulate almost all the photon energy on a nanoscale, which enable the excitation and emission of the Yb(3+) ions in the near-infrared region. This plasmon-photon conversion was evaluated from the cavity's quality factor (Q) and the coupling (g) between the nanoparticles and the Yb(3+) ions. We have found samples of low-quality cavities and strong coupling between the nanoparticles and the Yb(3+) ions. Our research can be extended towards the understanding of new plasmon-photon converters obtained from interactions between rare-earth ions and localized surface plasmon resonance.

  14. Plasmon-photon conversion to near-infrared emission from Yb3+: (Au/Ag-nanoparticles) in tungsten-tellurite glasses

    PubMed Central

    Rivera, V. A. G.; Ledemi, Yannick; Pereira-da-Silva, Marcelo A.; Messaddeq, Younes; Marega Jr, Euclydes

    2016-01-01

    This manuscript reports on the interaction between 2F5/2→2F7/2 radiative transition from Yb3+ ions and localized surface plasmon resonance (from gold/silver nanoparticles) in a tungsten-tellurite glass. Such an interaction, similar to the down-conversion process, results in the Yb3+ emission in the near-infrared region via resonant and non-resonant energy transfers. We associated such effects with the dynamic coupling described by the variations generated by the Hamiltonian HDC in either the oscillator strength, or the local crystal field, i.e. the line shape changes in the emission band. Here, the Yb3+ ions emission is achieved through plasmon-photon coupling, observable as an enhancement or quenching in the luminescence spectra. Metallic nanoparticles have light-collecting capability in the visible spectrum and can accumulate almost all the photon energy on a nanoscale, which enable the excitation and emission of the Yb3+ ions in the near-infrared region. This plasmon-photon conversion was evaluated from the cavity’s quality factor (Q) and the coupling (g) between the nanoparticles and the Yb3+ ions. We have found samples of low-quality cavities and strong coupling between the nanoparticles and the Yb3+ ions. Our research can be extended towards the understanding of new plasmon-photon converters obtained from interactions between rare-earth ions and localized surface plasmon resonance. PMID:26725938

  15. [Analysis on the ancient clinical application of Taiyuan (LU 9)].

    PubMed

    Mao, Gai; Jia, Hongling; Zhang, Yongchen

    2015-10-01

    The ancient literature on Taiyuan (LU 9) was collected to summarize the application laws of this acupoint. One thousand TCM ancient works collected in Chinese Medical Dictionary (fourth edition) were retrieved. The literature on the indications of Taiyuan (LU 9), the indications of Taiyuan (LU 9) combined prescriptions, the laws of acupoints combination and the techniques of acupuncture and moxibustion was collected systematically and the database was set up. It is found that there are 333 provisions in compliance with the inclusive standard of Taiyuan (LU 9), 306 provisions for the treatment of disorders and 66 relevant ancient works. There are 119 provisions relevant with the indication of single Taiyuan (LU 9) , 187 provisions for the applications of the combined prescriptions and 143 acupoints for the combined acupoints. Taiyuan (LU 9) and the combined prescriptions are applied to every department in clinic, especially for the disorders of TCM internal medicine department. The combined acupoints are distributed among the fourteen meridians and extra points and had been used totally for 1142 times. Of these points, there are 9 acupoints from the lung meridian of hand-taiyin and 25 acupoints from the bladder meridian of foot-taiyang, with the highest use frequency, 195 times and 141 times respectively, accounting for 17.08% and 12.35% of the total frequency. The common pairs of combination are Taiyuan (LU 9) and Yuji (LU 10), Taiyuan (LU 9) and Lieque (LU 7) and Taiyuan (LU 9) and Taibai (SP 3). The common dose of moxibustion at the acupoint is 3 cones. The depth of insertion is 0.2 cun and the acupuncture time is two breathes.

  16. Thermal lensing measurements in diode-pumped Yb-doped GdCOB, YCOB, YSO, YAG and KGW

    NASA Astrophysics Data System (ADS)

    Chénais, S.; Druon, F.; Balembois, F.; Lucas-Leclin, G.; Fichot, Y.; Georges, P.; Gaumé, R.; Viana, B.; Aka, G. P.; Vivien, D.

    2003-04-01

    A Shack-Hartmann wavefront sensor was used to measure thermal lensing in diode-end-pumped Yb-doped GdCOB, YCOB, YSO, YAG, and KGW crystals, under lasing or nonlasing conditions. Measured thermal lenses are aberration-free, and their focal lengths under lasing action range from 40 to 140 mm for 5 W of absorbed power. When laser action was inhibited the thermal lens dioptric power was increased significantly in most crystals, supplying evidence that nonradiative mechanisms exist. Reduction of thermal effects in a composite YCOB crystal is also investigated, as well as the dependence of thermal lensing on the emission wavelength in YSO.

  17. Self-stabilized and dispersion-compensated passively mode-locked Yb:Yttrium aluminum garnet laser

    NASA Astrophysics Data System (ADS)

    Agnesi, A.; Guandalini, A.; Reali, G.

    2005-04-01

    Self-stabilized passive mode-locking of a diode-pumped Yb:yttrium aluminum garnet laser with a semiconductor saturable absorber was achieved using an off-phase-matching second-harmonic crystal. According to the numerical model, such a condition is accomplished by self-defocusing in the nonlinear crystal in the presence of positive intracavity dispersion. Robust mode locking with Fourier-limited 1.0-ps pulses was obtained, whereas mode locking, unassisted by the nonlinear crystal, yielded 2.2-ps pulses, with the laser operating near the edge of the stability region in order to minimize the saturation energy of the semiconductor device.

  18. Tuning Magnetism of [MnSb4](9-) Cluster in Yb14MnSb11 through Chemical Substitutions on Yb Sites: Appearance and Disappearance of Spin Reorientation.

    PubMed

    Hu, Yufei; Chen, Chih-Wei; Cao, Huibo; Makhmudov, F; Grebenkemper, Jason H; Abdusalyamova, M N; Morosan, Emilia; Kauzlarich, Susan M

    2016-09-28

    Single crystals of Yb14-xRExMnSb11 (0 < x < 0.6, RE = Pr, Nd, Sm, and Gd) were synthesized by Sn flux. The compounds are iso-structural with Ca14AlSb11 (I41/acd), and their compositions were determined by wavelength-dispersive spectroscopy. Yb14MnSb11 is described as a partially screened d-metal Kondo system with the isolated [MnSb4](9-) tetrahedral cluster having a d(5) + hole configuration that results in four unpaired electrons measured in the ferromagnetically ordered phase. All of the Yb atoms in Yb14MnSb11 are present as Yb(2+), and the additional RE in Yb14-xRExMnSb11 is trivalent, contributing one additional electron to the structure and altering the magnetic properties. All compounds show ferromagnetic ordering in the range of 39-52 K attributed to the [MnSb4](9-) magnetic moment. Temperature-dependent DC magnetization measurements of Yb14-xPrxMnSb11 (0.44 ≤ x ≤ 0.56) show a sharp downturn right below the ferromagnetic transition temperature. Single-crystal neutron diffraction shows that this downturn is caused by a spin reorientation of the [MnSb4](9-) magnetic moments from the ab-plane to c-axis. The spin reorientation behavior, caused by large anisotropy, is also observed for similar x values of RE = Nd but not for RE = Sm or Gd at any value of x. In Pr-, Nd-, and Sm-substituted crystals, the saturation moments are consistent with ∼4 unpaired electrons attributed to [MnSb4](9-), indicating that local moments of Pr, Nd, and Sm do not contribute to the ferromagnetic order. In the case of RE = Pr, this is confirmed by neutron diffraction. In contrast, the magnetic measurements of RE = Gd show that the moments of Gd ferromagnetically order with the moments of [MnSb4](9-), and reduced screening of moments on Mn(2+) is evident. The sensitive variation of magnetic behavior is attributed to the various RE substitutions resulting in different interactions of the 4f-orbitals with the 3d-orbitals of Mn in the [MnSb4](9-) cluster conducted through 5p

  19. Tuning Magnetism of [MnSb4](9-) Cluster in Yb14MnSb11 through Chemical Substitutions on Yb Sites: Appearance and Disappearance of Spin Reorientation.

    PubMed

    Hu, Yufei; Chen, Chih-Wei; Cao, Huibo; Makhmudov, F; Grebenkemper, Jason H; Abdusalyamova, M N; Morosan, Emilia; Kauzlarich, Susan M

    2016-09-28

    Single crystals of Yb14-xRExMnSb11 (0 < x < 0.6, RE = Pr, Nd, Sm, and Gd) were synthesized by Sn flux. The compounds are iso-structural with Ca14AlSb11 (I41/acd), and their compositions were determined by wavelength-dispersive spectroscopy. Yb14MnSb11 is described as a partially screened d-metal Kondo system with the isolated [MnSb4](9-) tetrahedral cluster having a d(5) + hole configuration that results in four unpaired electrons measured in the ferromagnetically ordered phase. All of the Yb atoms in Yb14MnSb11 are present as Yb(2+), and the additional RE in Yb14-xRExMnSb11 is trivalent, contributing one additional electron to the structure and altering the magnetic properties. All compounds show ferromagnetic ordering in the range of 39-52 K attributed to the [MnSb4](9-) magnetic moment. Temperature-dependent DC magnetization measurements of Yb14-xPrxMnSb11 (0.44 ≤ x ≤ 0.56) show a sharp downturn right below the ferromagnetic transition temperature. Single-crystal neutron diffraction shows that this downturn is caused by a spin reorientation of the [MnSb4](9-) magnetic moments from the ab-plane to c-axis. The spin reorientation behavior, caused by large anisotropy, is also observed for similar x values of RE = Nd but not for RE = Sm or Gd at any value of x. In Pr-, Nd-, and Sm-substituted crystals, the saturation moments are consistent with ∼4 unpaired electrons attributed to [MnSb4](9-), indicating that local moments of Pr, Nd, and Sm do not contribute to the ferromagnetic order. In the case of RE = Pr, this is confirmed by neutron diffraction. In contrast, the magnetic measurements of RE = Gd show that the moments of Gd ferromagnetically order with the moments of [MnSb4](9-), and reduced screening of moments on Mn(2+) is evident. The sensitive variation of magnetic behavior is attributed to the various RE substitutions resulting in different interactions of the 4f-orbitals with the 3d-orbitals of Mn in the [MnSb4](9-) cluster conducted through 5p

  20. Grey scale memory in an optically addressed spatial light modulator with a Lu(Pc)2 doped layer

    NASA Astrophysics Data System (ADS)

    Guéna, M.; Wu, Z. Y.; L'Her, M.; Pondaven, A.; Cadiou, C.

    1998-02-01

    An optically addressed spatial light modulator with electrolyte bisphtalocyanine of lutetium incorporated in the alignment layer is shown to be capable of memorizing a grey scale image. The relationship between the memorized grey scale and the illumination is shown. The temperature, the concentration of Lu(Pc)2 and the spontaneous polarization of liquid crystals are found to have the effect on the memorization rate.

  1. Ytterbium-Doped Yettrium Aluminum Garnet Crystal Fiber Multipass Ring Laser

    NASA Astrophysics Data System (ADS)

    Yi, Jui-Yun; Huang, Kuang-Yao; Lai, Chien-Chih; Peng, Hsin; Chen, Li-Hsuan; Huang, Sheng-Lung

    2010-12-01

    We report the growth of ytterbium-doped yettrium aluminum garnet (Yb:YAG) crystal fibers by the laser-heated pedestal growth (LHPG) method. The characteristics of Yb:YAG crystal fibers were analyzed by electron probe microanalyzer (EPMA) and X-ray diffraction measurements. The small crystal fiber diameter makes it effective for heat removal from a high-Yb3+-concentration and quasi-three-level gain medium. The length of this crystal-fiber-based high absorption can be shorter, which is eminently suitable for a multipass ring cavity to maintain cavity stability and mode symmetry. We successfully demonstrated a two-mirror multipass ring laser with 54.7% slope efficiency, which is higher than the 50.3% for a bulk Yb:YAG laser.

  2. Diode-pumped intra-cavity doubled Nd:LuVO 4 laser at 458 nm

    NASA Astrophysics Data System (ADS)

    He, Kunna; Gao, Chunqing; Wei, Zhiyi; Li, Dehua; Zhang, Zhiguo; Zhang, HuaiJin; Wang, Jiyang

    2008-07-01

    We have demonstrated a diode-pumped intra-cavity frequency doubling Nd:LuVO 4 laser operating at 916 nm with a Z-folded cavity. A 10-mm long LBO crystal, cut for critical type I phase matching at 912 nm, is used for the experiment. A maximum output power of 330 mW at 458 nm has been achieved at pump power of 22 W. The optical-to-optical conversion efficiency and slope efficiency is 1.5% and 2.3%, respectively. The power instability at the maximum output power in 30 min is better than 3%.

  3. Diode-pumped Yb:Sr{sub 5}(PO{sub 4}){sub 3}F laser performance

    SciTech Connect

    Marshall, C.D.; Payne, S.A.; Smith, L.K.

    1995-03-17

    The performance of the first diode-pumped Yb{sup 3+}-doped Sr{sub 5}(PO{sub 4}){sub 3}F (Yb:S-FAP) laser is discussed. We found the pumping dynamics and extraction cross-sections of Yb:S-FAP crystals to be similar to those previously inferred by purely spectroscopic techniques. The saturation fluence for pumping was measured to be 2.2 J/cm{sup 2} using three different methods based on either the spatial, temporal, or energy transmission properties of a Yb:S-FAP rod. The small signal gain implies an emission cross section of 6.0 x 10{sup -20} cm{sup 2} that falls within error bars of the previously reported value of 7.3 x 10{sup -20} cm{sup 2}, obtained from spectroscopic techniques. Up to 1.7 J/cm{sup 3} of stored energy density was achieved in a 6 x 6 x 44 mm Yb:S-FAP amplifier rod. An InGaAs diode array has been fabricated that has suitable specifications for pumping a 3 x 3 x 30 mm Yb:S-FAP rod. In a free running configuration diode-pumped slope efficiencies up to 43% were observed with output energies up to {approximately}0.5 J per 1 ms pulse. When the rod was mounted in a copper block for cooling, 13 W of average power was produced with power supply limited operation at 70 Hz and 500 {mu}s pulses.

  4. Microwave sol-gel synthesis and upconversion photoluminescence properties of CaGd2(WO4)4:Er3+/Yb3+ phosphors with incommensurately modulated structure

    NASA Astrophysics Data System (ADS)

    Lim, Chang Sung; Aleksandrovsky, Aleksandr; Molokeev, Maxim; Oreshonkov, Aleksandr; Atuchin, Victor

    2015-08-01

    CaGd2-x(WO4)4:Er3+/Yb3+ phosphors with the doping concentrations of Er3+ and Yb3+ (x=Er3++Yb3+, Er3+=0.05, 0.1, 0.2 and Yb3+=0.2, 0.45) have been successfully synthesized by the microwave sol-gel method. The crystal structure of CaGd2-x(WO4)4:Er3+/Yb3+ tungstates have been refined, and upconversion photoluminescence properties have been investigated. The synthesized particles, being formed after the heat-treatment at 900 °C for 16 h, showed a well crystallized morphology. Under the excitation at 980 nm, CaGd2(WO4)4:Er3+/Yb3+ particles exhibited a strong 525-nm and a weak 550-nm emission bands in the green region and a very weak 655-nm emission band in the red region. The Raman spectrum of undoped CaGd2(WO4)4 revealed about 12 narrow lines. The strongest band observed at 903 cm-1 was assigned to the ν1 symmetric stretching vibration of WO4 tetrahedrons. The spectra of the samples doped with Er and Yb obtained under the 514.5 nm excitation were dominated by Er3+ luminescence preventing the recording of these samples Raman spectra. Concentration quenching of the erbium luminescence at 2H11/2→4I15/2 transition is weak in the range of erbium doping level xEr=0.05-0.2, while, for transition 4S3/2→4I15/2, the signs of concentration quenching become pronounced at xEr=0.2.

  5. Morphology Controllable Synthesis of ScF3:Er3+, Yb3+ Nano/Sub-Microncrystals by Hydrothermal/Solvothermal Process.

    PubMed

    Han, Lili; Li, Hua; Ci, Zhipeng; Wang, Yuhua

    2016-04-01

    In this paper, red phosphors Yb3+-Er3+ co-doped ScF3 nano/microcrystals were successfully prepared by a facile hydrothermal/solvothermal route using the sodium dodecyl benzene sulfonate (SDBS) as the surfactant. The structure, morphologies and up-conversion (UC) photoluminescence properties of the as-prepared products were well characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and photoluminescence (PL) spectra, respectively. The SEM images show that the obtained samples are the uniform cubic and cuboid crystals. With the increase of the surfactant SDBS or the change in the solvent types, the sample change their size from nanometer to submicron. Upon the 980 nm laser diode excitation, the ScF3:Era+, Yb3+ nanocrystals exhibit red emission which can be assigned to the characteristic 4F9/2/4I15/2 transition of Er3+. In order to understand the emission mechanisms of ScF3:ErS+, Yb3+ nanocrystals, the dependence of UC luminescence intensity on the 980 nm excitation power was measured, suggesting that the UC phenomenon results from a two-photon process. Meanwhile, the emission intensities of the YbS+-Er3+ codoped ScF3 nano/sub-micro crystals with different solution composition show an obvious change under the 980 nm laser excitation. Therefore, the phosphors Yb3+-Er3+ co-doped ScF3 possibly have a potential application in the biological applications.

  6. Morphology Controllable Synthesis of ScF3:Er3+, Yb3+ Nano/Sub-Microncrystals by Hydrothermal/Solvothermal Process.

    PubMed

    Han, Lili; Li, Hua; Ci, Zhipeng; Wang, Yuhua

    2016-04-01

    In this paper, red phosphors Yb3+-Er3+ co-doped ScF3 nano/microcrystals were successfully prepared by a facile hydrothermal/solvothermal route using the sodium dodecyl benzene sulfonate (SDBS) as the surfactant. The structure, morphologies and up-conversion (UC) photoluminescence properties of the as-prepared products were well characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and photoluminescence (PL) spectra, respectively. The SEM images show that the obtained samples are the uniform cubic and cuboid crystals. With the increase of the surfactant SDBS or the change in the solvent types, the sample change their size from nanometer to submicron. Upon the 980 nm laser diode excitation, the ScF3:Era+, Yb3+ nanocrystals exhibit red emission which can be assigned to the characteristic 4F9/2/4I15/2 transition of Er3+. In order to understand the emission mechanisms of ScF3:ErS+, Yb3+ nanocrystals, the dependence of UC luminescence intensity on the 980 nm excitation power was measured, suggesting that the UC phenomenon results from a two-photon process. Meanwhile, the emission intensities of the YbS+-Er3+ codoped ScF3 nano/sub-micro crystals with different solution composition show an obvious change under the 980 nm laser excitation. Therefore, the phosphors Yb3+-Er3+ co-doped ScF3 possibly have a potential application in the biological applications. PMID:27451694

  7. Dysfunction of Rice Mitochondrial Membrane Induced by Yb3+.

    PubMed

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

    2015-12-01

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

  8. Location of trivalent lanthanide dopant energy levels in (Lu{sub 0.5}Gd{sub 0.5}){sub 2}O{sub 3}

    SciTech Connect

    Retot, H.; Viana, B.; Bessiere, A.; Galtayries, A.

    2011-06-15

    The location of Ln{sup 3+} dopant energy levels relative to bands in (Lu{sub 0.5}Gd{sub 0.5}){sub 2}O{sub 3} was studied. A several-steps analysis of XPS measurements on heavy lanthanides sesquioxides Ln{sub 2}O{sub 3} (Ln = Gd, Tb, Dy, Er, Tm, Yb, Lu) and on Sc{sub 2}O{sub 3} and Y{sub 2}O{sub 3} reference materials were used to locate Ln{sup 3+} dopant ground state relative to the top of the valence band in (Lu{sub 0.5}Gd{sub 0.5}){sub 2}O{sub 3} within an error bar of {+-}0.4 eV. The agreement between XPS data and model was found improved relative to previous studies. When compared to XPS analysis, prediction based on optical absorption shows a slight underestimation attributed to the lack of precision in Ce{sup 4+} charge transfer band measurement.

  9. Neutron Capture Reactions on lu Isotopes at Dance

    NASA Astrophysics Data System (ADS)

    Roig, O.; Meot, V.; Daugas, J.-M.; Morel, P.; Jandel, M.; Vieira, D. J.; Bond, E. M.; Bredeweg, T. A.; Couture, A. J.; Haight, R. C.; Keksis, A. L.; Rundberg, R. S.; Ullmann, J. L.; Wouters, J. M.

    2013-03-01

    The DANCE1 (Detector for Advanced Neutron Capture Experiments) array at LANSCE spallation neutron source in Los Alamos has been used to obtain the neutron radiative capture cross sections for 175Lu and 176Lu with neutron energies from thermal up to 100 keV. Both isotopes are of current interest for the nucleosynthesis s-process.2,3 Three targets were used to perform these measurements. One was natural Lu foil of 31 mg/cm2 and the other two were isotope-enriched targets of 175Lu and 176Lu. Firstly, the cross sections were obtained by normalizing yield to a well-known cross section at the thermal neutron energy. Now, we want to obtain absolute cross sections of radiative capture through a precise neutron flux determination, an accurate target mass measurement and an efficiency determination of the DANCE array.

  10. Neutron capture reactions on Lu isotopes at DANCE

    NASA Astrophysics Data System (ADS)

    Roig, O.; Jandel, M.; Vieira, D. J.; Bond, E. M.; Bredeweg, T. A.; Couture, A. J.; Daugas, J.-M.; Haight, R. C.; Keksis, A. L.; Méot, V.; Morel, P.; O'Donnell, J. M.; Rundberg, R. S.; Taylor, W. A.; Ullmann, J. L.; Wouters, J. M.

    2010-03-01

    The DANCE (Detector for Advanced Neutron Capture Experiments) array located at the Los Alamos national laboratory has been used to obtain the neutron capture cross sections for the 175Lu and 176Lu isotopes with neutron energies from thermal up to 100 keV. Both isotopes are of current interest for the nucleosynthesis s-process in astrophysics and for applications as in reactor physics or in nuclear medicine. Three targets were used to perform these measurements. One was natLu foil and the other two were isotope-enriched targets of 175Lu and 176Lu. The cross sections are obtained for now through a precise neutron flux determination and a normalization at the thermal neutron cross section value. A comparison with the recent experimental data and the evaluated data of ENDF/B-VII.0 will be presented. In addition, resonances parameters and spin assignments for some resonances will be featured.

  11. Growth and characterization of LuAs films and nanostructures

    NASA Astrophysics Data System (ADS)

    Krivoy, E. M.; Nair, H. P.; Crook, A. M.; Rahimi, S.; Maddox, S. J.; Salas, R.; Ferrer, D. A.; Dasika, V. D.; Akinwande, D.; Bank, S. R.

    2012-10-01

    We report the growth and characterization of nearly lattice-matched LuAs/GaAs heterostructures. Electrical conductivity, optical transmission, and reflectivity measurements of epitaxial LuAs films indicate that LuAs is semimetallic, with a room-temperature resistivity of 90 μΩ cm. Cross-sectional transmission electron microscopy confirms that LuAs nucleates as self-assembled nanoparticles, which can be overgrown with high-quality GaAs. The growth and material properties are very similar to those of the more established ErAs/GaAs system; however, we observe important differences in the magnitude and wavelength of the peak optical transparency, making LuAs superior for certain device applications, particularly for thick epitaxially embedded Ohmic contacts that are transparent in the near-IR telecommunications window around 1.3 μm.

  12. Growth and characterization of LuAs films and nanostructures

    SciTech Connect

    Krivoy, E. M.; Nair, H. P.; Crook, A. M.; Rahimi, S.; Maddox, S. J.; Salas, R.; Ferrer, D. A.; Dasika, V. D.; Akinwande, D.; Bank, S. R.

    2012-10-01

    We report the growth and characterization of nearly lattice-matched LuAs/GaAs heterostructures. Electrical conductivity, optical transmission, and reflectivity measurements of epitaxial LuAs films indicate that LuAs is semimetallic, with a room-temperature resistivity of 90 {mu}{Omega} cm. Cross-sectional transmission electron microscopy confirms that LuAs nucleates as self-assembled nanoparticles, which can be overgrown with high-quality GaAs. The growth and material properties are very similar to those of the more established ErAs/GaAs system; however, we observe important differences in the magnitude and wavelength of the peak optical transparency, making LuAs superior for certain device applications, particularly for thick epitaxially embedded Ohmic contacts that are transparent in the near-IR telecommunications window around 1.3 {mu}m.

  13. Remarkable enhancement of upconversion fluorescence and confocal imaging of PMMA Opal/NaYF(4):Yb(3+), Tm(3+)/Er(3+) nanocrystals.

    PubMed

    Yin, Ze; Zhu, Yongsheng; Xu, Wen; Wang, Jing; Xu, Sai; Dong, Biao; Xu, Lin; Zhang, Shuang; Song, Hongwei

    2013-05-01

    Novel PMMA opal photonic crystal/NaYF(4):Yb(3+), Tm(3+)/Er(3+) nanocrystal composites were fabricated and tremendous improvement in upconversion luminescence (UCL) was observed under infrared 980 nm excitation. They were also explored to improve brightness of cell images. PMID:23539518

  14. Inhibited local thermal effect in upconversion luminescence of YVO₄:Yb³⁺, Er³⁺ inverse opals.

    PubMed

    Zhu, Yongsheng; Xu, Wen; Zhang, Hanzhuang; Xu, Sai; Wang, Yunfeng; Dai, Qinlin; Dong, Biao; Xu, Lin; Song, Hongwei

    2012-12-31

    Upconversion Luminescence (UCL) of YVO₄:Yb³⁺, Er³⁺ inverse opal photonic crystals (IOPCs) was investigated in contrast to the references under the excitation of a 980-nm laser diode. Besides the traditional modification on UCL and dynamics, it is significant to observe that in the IOPCs the temperature quenching and local thermal effect was greatly suppressed.

  15. Lu-Hf and Sm-Nd geochronology of garnet gneisses in the central Appalachians, U.S.: Implications for the timing and duration of Grenville Orogeny

    NASA Astrophysics Data System (ADS)

    Vervoort, Jeff; Ramsey, Molly; Mulcahy, Sean; Aleinikoff, John; Southworth, Scott

    2014-05-01

    The Grenville orogeny is one of the most significant geological events in Earth's history with remnants of this event prominent on virtually every continent. Constraining its timing and duration is important not only for understanding the tectonics of the Grenville itself, but also for understanding supercontinent cycles and other questions of Earth's evolution. In order to provide better constraints on the timing of Grenvillian metamorphism, we analyzed garnet-bearing Mesoproterozoic ortho and paragneisses, collected along a 150 km transect in the northern Blue Ridge Province, using combined Lu-Hf and Sm-Nd geochronology. The orthogneisses have U-Pb zircon crystallization ages of ~1140 and 1100 Ma. The paragneisses have maximum depositional ages ~1050 to 1020 Ma, based on the youngest detrital zircon populations. Zircon overgrowths and monazite ages suggest metamorphic events between ~1050 and 960 Ma. The Lu-Hf and Sm-Nd data for these samples both yield robust garnet ages with large spread of parent/daughter ratios, low age uncertainties, and low MSWD values. Lu-Hf ages define a narrow time span (1043±12 Ma to 1016±4 Ma; wtd. mean, 1024±7 Ma, 2σ). The Sm-Nd ages, determined on the same solutions as Lu-Hf, also define a narrow time range but are systematically younger (974±11 Ma to 932±5 Ma; wtd. mean, 957±10 Ma). The average difference between Lu-Hf and Sm-Nd ages is 67 Ma; the oldest Sm-Nd age is 40 Ma younger than the youngest Lu-Hf age. These large systematic differences in the ages are enigmatic. While Sm-Nd ages younger than Lu-Hf are not uncommon, these differences are typically small. There are, however, potential explanations for these differences. (1) Lu partitions strongly into garnet during growth resulting in high Lu/Hf ratios in the core and yielding ages weighted toward the beginning of growth (e.g., Skora, 2006); no similar partitioning exists in Sm/Nd and these ages reflect mean garnet growth. (2) Lu diffuses much faster than Hf at elevated

  16. Features of the band structure and conduction mechanisms of n-HfNiSn semiconductor heavily Lu-doped

    SciTech Connect

    Romaka, V. A.; Rogl, P.; Romaka, V. V.; Kaczorowski, D.; Stadnyk, Yu. V.; Korzh, R. O.; Krayovskyy, V. Ya.; Kovbasyuk, T. M.

    2015-03-15

    The crystal and electronic structures, energy, kinetic, and magnetic characteristics of n-HfNiSn semiconductor heavily doped with a Lu acceptor impurity in the ranges T = 80–400 K and N{sub A}{sup Lu} ≈ 1.9 × 10{sup 20}−1.9 × 10{sup 21} cm{sup −3} (x = 0.01–0.10) at H ≤ 10 kG is studied. The nature of the structural-defect generation mechanism leading to changes in the band gap and the degree of semiconductor compensation is determined. Its essence is the simultaneous reduction and elimination of donor-type structural defects due to the displacement of ∼1% of Ni atoms from the Hf (4a) site, the generation of acceptor-type structural defects by substituting Ni atoms with Lu atoms at the 4c site, and the generation of donor-type defects such as vacancies at the Sn (4b) site. The results of calculations of the electronic structure of Hf{sub 1−x}Lu{sub x}NiSn are in agreement with experimental data. The results are discussed within the model of a heavily doped and compensated Shklovskii-Efros semiconductor.

  17. Correlation between structure and optical properties in (Y,Lu)3Al5O12:Ce3+ solid solutions

    NASA Astrophysics Data System (ADS)

    Zhang, Mei; Li, Bowen; Yang, Yingshu; Chen, Shuijin; He, Xin; Zhao, Fenghua; Zeng, Qingguang

    2016-10-01

    A series of (Y,Lu)3Al5O12:Ce3+ (YLuAG:Ce) solid solutions were synthesized via the solid-state reaction route. The phosphors are all of the cubic garnet crystal structures confirmed by x-ray diffraction (XRD). The internal quantum efficiency and emission intensity of the phosphors can be enhanced by increasing the Lu3+ content in the host lattice, along with a blue shift of the emission peak. In addition, the blue shift of the emission peak correlates very well with the lattice contraction. Intense light-emitting diodes (LEDs) are successfully fabricated based on the YLuAG:Ce phosphors and 450 nm blue Ga(In)N chips. The luminous efficiency of YLuAG:Ce phosphors converted LEDs increases with elevating Lu3+ concentration. The results indicate that Ce3+ doped YLuAG solid solutions, especially LuAG:Ce phosphor is a promising green phosphor for solid-state lighting.

  18. Scaling of Yb-Fiber Frequency Combs

    NASA Astrophysics Data System (ADS)

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

    2010-06-01

    Immediately after their introduction in 1999, femtosecond laser frequency combs revolutionized the field of precision optical frequency metrology and are key elements in many experiments. Frequency combs based on femtosecond Er-fiber lasers based were demonstrated in 2005, allowing additionally rugged, compact set-ups and reliable unattended long-term operation. The introduction of Yb-fiber technology led to an dramatic improvement in fiber-comb performance in various aspects. Low-noise Yb-fiber femtosecond oscillators enabled a reduction of relative comb tooth linewidth to the sub-Hz level as well as scaling of the fundamental comb spacings up to 1 GHz. This is beneficial for any frequency-domain comb application due to the higher power per comb-mode. Many spectroscopic applications require, however, frequency combs way beyond the wavelength range accessible with broad band laser materials, so nonlinear conversion and hence higher peak intensity is required. We demonstrated power scaling of Yb-fiber frequency combs up to 80 W average power in a strictly linear chirped-pulse amplification schemes compatible with low-noise phase control. These high-power Yb-fiber-frequency combs facilitated not only the extension to the mid-IR spectral region. When coupled to a passive enhancement cavity, the average power can be further scaled to the kW-level opening new capabilities for XUV frequency combs via high-harmonic generation. All these advances of fiber-based frequency combs will trigger many novel applications both in fundamental and applied sciences. Schibli et al., Nature Photonics 2 355 (2008). Hartl et al., MF9 in Advanced Solid-State Photonics. 2009, Optical Society of America. Ruehl et al., AWC7 in Advanced Solid-State Photonics. 2010, Optical Society of America. Adler et al., Optics Letters 34 1330 (2009). Yost et al., Nature Physics 5 815 (2009).

  19. Melt processing of Yb-123 tapes

    SciTech Connect

    Athur, S. P.; Balachandran, U.; Salama, K.

    2000-02-17

    The innovation of a simple, scalable process for manufacturing long-length conductors of HTS is essential to potential commercial applications such as power cables, magnets, and transformers. In this paper the authors demonstrate that melt processing of Yb-123 tapes made by the PIT route is an alternative to the coated conductor and Bi-2223 PIT tape fabrication techniques. Ag-clad Yb-123 tapes were fabricated by groove rolling and subsequently, melt processed in different oxygen partial pressures in a zone-melting furnace with a gradient of 140 C/cm. The transition temperatures measured were found to be around 81 K undermost processing conditions. EPMA of the tapes processed under different conditions show the 123 phase to be Ba deficient and Cu and Yb rich. Critical current was measured at various temperatures from 77 K to 4.2 K. The J{sub c} increased with decrease in pO{sub 2}. The highest I{sub c} obtained was 52 A at 4.2 K.

  20. YB-1 protein: functions and regulation.

    PubMed

    Lyabin, Dmitry N; Eliseeva, Irina A; Ovchinnikov, Lev P

    2014-01-01

    The Y-box binding protein 1 (YB-1, YBX1) is a member of the family of DNA- and RNA-binding proteins with an evolutionarily ancient and conserved cold shock domain. It falls into a group of intrinsically disordered proteins that do not follow the classical rule 'one protein-one function' but introduce a novel principle stating that a disordered structure suggests many functions. YB-1 participates in a wide variety of DNA/RNA-dependent events, including DNA reparation, pre-mRNA transcription and splicing, mRNA packaging, and regulation of mRNA stability and translation. At the cell level, the multiple activities of YB-1 are manifested as its involvement in cell proliferation and differentiation, stress response, and malignant cell transformation. WIREs RNA 2014, 5:95-110. doi: 10.1002/wrna.1200 CONFLICT OF INTEREST: The authors have declared no conflicts of interest for this article. For further resources related to this article, please visit the WIREs website.