The Nd^3＋：LiGd（WO4） 2 crystal with dimensions of 25mm×28mm×16mm was grown by the top-seeded solution growth method from the 60 mol% Li2W2O7 flux. LiGd（WO4） 2 crystallizes in the tetragonal system with ...The Nd^3＋：LiGd（WO4） 2 crystal with dimensions of 25mm×28mm×16mm was grown by the top-seeded solution growth method from the 60 mol% Li2W2O7 flux. LiGd（WO4） 2 crystallizes in the tetragonal system with space group I41/a（C4h^6） and cell parameters： a = 5.1986 and c = 11.2652A. The hardness is about 5.0 Mohs＇ scale. The specific heat is 0.40 J·g^-1·K^-1 at 50 oC. The thermal expansion coefficients for a-and c-axes are 1.314×10^-5 and 2.052×10^-5 K^-1,respectively. The room-temperature polarized absorption and emission spectra and the fluorescence decay curve was measured. The parameters of oscillator strengths,the spontaneous transition probabilities,the fluorescence branching ratios,the radiative lifetimes,and the emission cross sections have been investigated based on Judd-Ofelt theory and Füchtbauer-Ladenburg method. The absorption cross-section is 5.19×10^-20 cm^2 at 805 nm for π-polarization and its line width is 15 nm; the emission cross section is 1.726×10^-19 cm^2 at 1060.5 nm for π-polarization. The fluorescence and radiative lifetimes are 86 and 158 μs,respectively. The fluorescence quantum efficiency is 54.43%.展开更多
The Yb3＋-doped LiGd（MoO4）2 crystal with the size up to Φ20×30 mm3 has been grown by Czochralski technique.The polarized room temperature absorption and emission spectra have been investigated.This crystal exh...The Yb3＋-doped LiGd（MoO4）2 crystal with the size up to Φ20×30 mm3 has been grown by Czochralski technique.The polarized room temperature absorption and emission spectra have been investigated.This crystal exhibits a broad absorption band centered at 975 nm with an FWHM of 43 and 59 nm for π-and σ-polarization,respectively,and the corresponding maximal absorption cross-sections are 3.36 and 2.42×10-20 cm2.The emission broadband has an FWHM of 47 and 54 nm for π-and σ-polarization,respectively,with the corresponding emission cross sections of 3.92 and 3.34 × 10-20 cm2 at 1020 nm.The measured fluorescence lifetime is 287 μs.展开更多
Rare earth europium（Eu（3＋））-doped lithium tetraborate（Eu：Li_2B_4O_7） crystal is grown from its stoichiometric melt by microtube Czochralski pulling technique（μT-Cz） for the first time. The grown crystals ar...Rare earth europium（Eu（3＋））-doped lithium tetraborate（Eu：Li_2B_4O_7） crystal is grown from its stoichiometric melt by microtube Czochralski pulling technique（μT-Cz） for the first time. The grown crystals are subjected to powder x-ray diffraction（PXRD） analysis which reveals the tetragonal crystal structure of the crystals. UV–vis–NIR spectral analysis is carried out to study the optical characteristics of the grown crystals. The crystal is transparent in the entire visible region, and the lower cutoff is observed to be at 304 nm. The existence of BO_3 and BO_4 bonding structure and the molecular associations are analyzed by Fourier transform infrared（FTIR） spectroscopy. The results of excitation and emission-photoluminescence spectra of europium ion incorporated in lithium tetraborate（LTB） single crystal reveal that the observations of peaks at 258,297, and 318 nm in the excitation spectra and peaks at 579, 591, 597, 613, and 651 nm are observed in the emission spectra.The chromaticity coordinates are calculated from the emission spectra, and the emission intensity of the grown crystal is characterized through a CIE 1931（Commission International d＇Eclairage） color chromaticity diagram.展开更多
The absorption spectra, excitation spectra, and emission spectra of Tb3＋/Eu3＋ ions in LiYF4 single crystals synthesized by an improved Bridgman method are measured. The emission spectra of several bands, mainly loca...The absorption spectra, excitation spectra, and emission spectra of Tb3＋/Eu3＋ ions in LiYF4 single crystals synthesized by an improved Bridgman method are measured. The emission spectra of several bands, mainly located at blue^487 nm （Tb：5D4→7F6）, yellowish green ~542 nm （Tb：SD4→ 7F5）, and red ~611 nm （Eu：SD0 → 7F2） wavelengths, are observed under excitation by UV light. An ideal white light emission as a result of simultaneous combination of these emissions can be obtained from 1.11 mol%Tb3＋ and 0.9 mol% Eu3＋ co-doped LiYF4 single crystals with chromaticity coordinates of x = 0.3242, y = 0.3389, color temperature Tc = 5878 K, color rendering index Ra = 77, and color quality scale Qa = 75 under excitation of 384 nm light. The chromaticity coordinate, color rendering index, and color quality scale can be modified by the change of the concentration of rare-earth dopants and the excitation wavelength.展开更多
A set of 2D steady state finite element numerical simulations of electromagnetic fields and heating distribution for an oxide Czochralski crystal growth system was carried out for different input current shapes (sine,...A set of 2D steady state finite element numerical simulations of electromagnetic fields and heating distribution for an oxide Czochralski crystal growth system was carried out for different input current shapes (sine, square, triangle and sawtooth waveforms) of the induction coil. Comparison between the results presented here demonstrates the importance of input current shape on the electromagnetic field distribution, coil efficiency, and intensity and structure of generated power in the growth setup.展开更多
The Yb：YAG and Yb：YAP crystals have been grown by Czochralski method. The absorption spectra and the fluorescence spectra of Yb：YAG and Yb：YAP crystals have been investigated. It is shown that the Yb：YAG crystal ...The Yb：YAG and Yb：YAP crystals have been grown by Czochralski method. The absorption spectra and the fluorescence spectra of Yb：YAG and Yb：YAP crystals have been investigated. It is shown that the Yb：YAG crystal has better laser properties and smaller threshold power than Yb：YAP crystal. In addition, the absorption cross-section of the Yb：YAP crystal is 2.16 times of that of the Yb：YAG crystal, so laser diode pumped Yb：YAG lasing can be easily realized. Because YAP single crystal is anisotropic, it is provided with polarization characteristics.展开更多
基金Supported by the National Natural Science Foundation of China (No.60808033)Natural Science Foundation of Jiangxi Province (No.2008GZW0012)
文摘The Nd^3＋：LiGd（WO4） 2 crystal with dimensions of 25mm×28mm×16mm was grown by the top-seeded solution growth method from the 60 mol% Li2W2O7 flux. LiGd（WO4） 2 crystallizes in the tetragonal system with space group I41/a（C4h^6） and cell parameters： a = 5.1986 and c = 11.2652A. The hardness is about 5.0 Mohs＇ scale. The specific heat is 0.40 J·g^-1·K^-1 at 50 oC. The thermal expansion coefficients for a-and c-axes are 1.314×10^-5 and 2.052×10^-5 K^-1,respectively. The room-temperature polarized absorption and emission spectra and the fluorescence decay curve was measured. The parameters of oscillator strengths,the spontaneous transition probabilities,the fluorescence branching ratios,the radiative lifetimes,and the emission cross sections have been investigated based on Judd-Ofelt theory and Füchtbauer-Ladenburg method. The absorption cross-section is 5.19×10^-20 cm^2 at 805 nm for π-polarization and its line width is 15 nm; the emission cross section is 1.726×10^-19 cm^2 at 1060.5 nm for π-polarization. The fluorescence and radiative lifetimes are 86 and 158 μs,respectively. The fluorescence quantum efficiency is 54.43%.
基金supported by the National Natural Science Foundation of China (No. 60808033)Natural Science Foundation of Jiangxi Province (No. 2008GZW0012)the Science Project of the Education Commission of Jiangxi Province (No. GJJ08345)
文摘The Yb3＋-doped LiGd（MoO4）2 crystal with the size up to Φ20×30 mm3 has been grown by Czochralski technique.The polarized room temperature absorption and emission spectra have been investigated.This crystal exhibits a broad absorption band centered at 975 nm with an FWHM of 43 and 59 nm for π-and σ-polarization,respectively,and the corresponding maximal absorption cross-sections are 3.36 and 2.42×10-20 cm2.The emission broadband has an FWHM of 47 and 54 nm for π-and σ-polarization,respectively,with the corresponding emission cross sections of 3.92 and 3.34 × 10-20 cm2 at 1020 nm.The measured fluorescence lifetime is 287 μs.
基金Project supported by the Department of Science and Technology–Science and Engineering Research Board(Grant No.SR/S2/LOP-0012/2011)the Government of India for Awarding Major Research Project,the University Grants Commission–Department of Atomic Research–Consortium for Scientific Research(Grant No.CSR–KN/CSR–63/2014–2015/503)the Kalpakkam and Indore,India
文摘Rare earth europium（Eu（3＋））-doped lithium tetraborate（Eu：Li_2B_4O_7） crystal is grown from its stoichiometric melt by microtube Czochralski pulling technique（μT-Cz） for the first time. The grown crystals are subjected to powder x-ray diffraction（PXRD） analysis which reveals the tetragonal crystal structure of the crystals. UV–vis–NIR spectral analysis is carried out to study the optical characteristics of the grown crystals. The crystal is transparent in the entire visible region, and the lower cutoff is observed to be at 304 nm. The existence of BO_3 and BO_4 bonding structure and the molecular associations are analyzed by Fourier transform infrared（FTIR） spectroscopy. The results of excitation and emission-photoluminescence spectra of europium ion incorporated in lithium tetraborate（LTB） single crystal reveal that the observations of peaks at 258,297, and 318 nm in the excitation spectra and peaks at 579, 591, 597, 613, and 651 nm are observed in the emission spectra.The chromaticity coordinates are calculated from the emission spectra, and the emission intensity of the grown crystal is characterized through a CIE 1931（Commission International d＇Eclairage） color chromaticity diagram.
基金supported in part by the National Natural Science Foundation of China(Nos.51472125 and 51272109)the K.C.Wong Magna Fund in Ningbo University
文摘The absorption spectra, excitation spectra, and emission spectra of Tb3＋/Eu3＋ ions in LiYF4 single crystals synthesized by an improved Bridgman method are measured. The emission spectra of several bands, mainly located at blue^487 nm （Tb：5D4→7F6）, yellowish green ~542 nm （Tb：SD4→ 7F5）, and red ~611 nm （Eu：SD0 → 7F2） wavelengths, are observed under excitation by UV light. An ideal white light emission as a result of simultaneous combination of these emissions can be obtained from 1.11 mol%Tb3＋ and 0.9 mol% Eu3＋ co-doped LiYF4 single crystals with chromaticity coordinates of x = 0.3242, y = 0.3389, color temperature Tc = 5878 K, color rendering index Ra = 77, and color quality scale Qa = 75 under excitation of 384 nm light. The chromaticity coordinate, color rendering index, and color quality scale can be modified by the change of the concentration of rare-earth dopants and the excitation wavelength.
文摘A set of 2D steady state finite element numerical simulations of electromagnetic fields and heating distribution for an oxide Czochralski crystal growth system was carried out for different input current shapes (sine, square, triangle and sawtooth waveforms) of the induction coil. Comparison between the results presented here demonstrates the importance of input current shape on the electromagnetic field distribution, coil efficiency, and intensity and structure of generated power in the growth setup.
文摘The Yb：YAG and Yb：YAP crystals have been grown by Czochralski method. The absorption spectra and the fluorescence spectra of Yb：YAG and Yb：YAP crystals have been investigated. It is shown that the Yb：YAG crystal has better laser properties and smaller threshold power than Yb：YAP crystal. In addition, the absorption cross-section of the Yb：YAP crystal is 2.16 times of that of the Yb：YAG crystal, so laser diode pumped Yb：YAG lasing can be easily realized. Because YAP single crystal is anisotropic, it is provided with polarization characteristics.
