Nanocrystalline Gd3Ga5O12:Eu3+ with cubic phase was prepared by a urea homogeneous precipitation method. X-ray diffraction (XRD), field emission scanning electron microscopy (SEM), Fourier transform infrared spectrosc...Nanocrystalline Gd3Ga5O12:Eu3+ with cubic phase was prepared by a urea homogeneous precipitation method. X-ray diffraction (XRD), field emission scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), thermo-gravimetric and differential thermal analysis (TG-DTA) and photoluminescence spectra were used to characterize the samples. The effects of the initial solution pH value and urea content on the structure of the sample were studied. The XRD results show that pure phase Gd3Ga5O12 can be obtained at pH =6 and pH =8 of the initial solution. The average crystallite size can be calculated as in the range of 24~33 nm. The average crystallite size decreases with increasing molar ratio of urea to metal ion. The results of excitation spectra and emission spectra show that the emission peaks are ascribed to 5D0→7FJ transitions of Eu3+, and the magnetic dipole transition originated from 5D0 →7F1 of Eu3+ is the strongest; the broad excitation bands belong to change transfer band of Eu?O and the host absorption of Gd3Ga5O12. An efficient energy transfer occurs from Gd3+ to Eu3+.展开更多
A series of Er3＋, Tm3＋ and Yb3＋ doped Gd3Ga5O12 nanocrystals were prepared by a combustion method. The X-ray diffraction （XRD）, field emission scanning electron microscope （FESEM） and upconversion （UC） emissi...A series of Er3＋, Tm3＋ and Yb3＋ doped Gd3Ga5O12 nanocrystals were prepared by a combustion method. The X-ray diffraction （XRD）, field emission scanning electron microscope （FESEM） and upconversion （UC） emission spectra were used to characterize the samples. The results of XRD indicate that Gd3Ga5O12：Er3＋, Tm3＋, Yb3＋ nanocrystals with cubic phase can be obtained. Under the excitation of a 980 nm laser, the different rare earth ions doped Gd3Ga5O12 nanoerystals show upconversion luminescence involving the green emission attributed to the ^2H11/2→^4I15/2, 4^S3/2→^4I15/2 transitions of Er3＋ ions, respectively, the red emissions assigned to the ^4F9/2→^4I15/2 transitions of Er3＋ ions and the ^1G4→^3F4 as well as 3F2,3→^3H6 transitions of Tm3＋ ions, respectively, the blue emission attributed to ^1G4→^3H6 transitions of Tm3＋ ions, and the near-infrared assigned to the ^3H4→^3H6 transitions of Tm3＋ ions. The CIE coordinates for the samples are calculated. The dependence of their upconversion luminescence properties on Yb3＋ ion concentration is investieated.展开更多
Nd^3＋： Gd3Ga5O12（Nd ： GGG） nanopowder for transparent laser ceramics was synthesized using sol-gel method. XRD, SEM, and fluorescence spectrum were used to study the properties of Nd^3＋ ：Gd3Ga5O12 nanopowder. X...Nd^3＋： Gd3Ga5O12（Nd ： GGG） nanopowder for transparent laser ceramics was synthesized using sol-gel method. XRD, SEM, and fluorescence spectrum were used to study the properties of Nd^3＋ ：Gd3Ga5O12 nanopowder. XRD patterns of samples show that it has a cubic structure. Meanwhile, pure Nd：GGG crystals were obtained at 1000 ℃ for 12 h. SEM photographs show that dispersed, uniform, ball-like Nd：GGG nanopowder is obtained. Both XRD and SEM results show that the crystallization degree and the grain size increase with the increase in calcining temperature. Analysis of fluorescence spectrum shows that fluorescence emission occurs at 1062.7 nm, which is the result of Nd^3＋ （^4F3/2→^4I11/2） transition. Homogenous Nd ： GGG nanopewder with a small grain size synthesized using the sol-gel method is favorable for sintering the transparent ceramic, which proves that the nanopewder obtained is suitable as a precursor for preparing GGG transparent ceramics.展开更多
The Ytterbium doped gadolinium gallium garnet [Yb3＋：Gd3Ga5O12, Yb：GGG] precursor powders were synthesized via homogeneous precipitation method using Yb2O3, Ga2O3, Gd2O3 and ammonium bicarbonate [NH4HCO3] as precipi...The Ytterbium doped gadolinium gallium garnet [Yb3＋：Gd3Ga5O12, Yb：GGG] precursor powders were synthesized via homogeneous precipitation method using Yb2O3, Ga2O3, Gd2O3 and ammonium bicarbonate [NH4HCO3] as precipitator, and ammonium sulfate [（NH4）2SO4] as additive. The evolution of phase composition and micro-structure of the powders were characterized by TG- DTA, XRD, IR, and TEM. The results indicate that all precursor powders completely transform to Yb：GGG phase by calcining at 900 ℃ for 8 h, the resultant powders are well dispersed and have smaller particle size approximately 80 nm owing to the electrostatic effect.展开更多
Yb3＋/Tm3＋ co-doped Gd3Ga5O12 single crystal with a dimension of Φ30mm×20mm was grown successfully by Czochralski method.The absorption spectrum was recorded at room temperature and used to calculate the absorp...Yb3＋/Tm3＋ co-doped Gd3Ga5O12 single crystal with a dimension of Φ30mm×20mm was grown successfully by Czochralski method.The absorption spectrum was recorded at room temperature and used to calculate the absorption cross-section.Based on the Judd-Ofelt（J-O） theory,we obtained the three intensity parameters and spectral parameters of this crystal,such as the line strengths,oscillator strengths,radiative probabilities and radiative lifetimes as well as the fluorescent branching ratios.Room temperature fluorescence spectra and luminescence decay curves were recorded.The energy transfer between Yb3＋-Tm3＋ was observed and the mechanism was discussed.The stimulated emission cross-section of the 3F4→3H6 transition was calculated by the Füchtbauer-Ladenburg（F-L） equation.The potential laser gains for this transition were also investigated.This crystal is promising as a tunable infrared laser crystal at 2.0 μm.展开更多
Preparation of Nd3+:Gd3Ga5O12 polycrystalline material by sol-gel method was preparated in this paper.The structure and the pattern of the sample were analyzed by thermogravimetric analysis and differential thermal an...Preparation of Nd3+:Gd3Ga5O12 polycrystalline material by sol-gel method was preparated in this paper.The structure and the pattern of the sample were analyzed by thermogravimetric analysis and differential thermal analysis（TG-DTA）,Infrared spectrum,XRD,TEM and electron spectrum,which indicated that the powder with good characteristics of 70-100 nm can be obtained by sintering at 1 000℃.It was shown that the chemical composition of the sample was agreed with experimental requirements by electron spectrum analysis.展开更多
Gadolinium gallium gamet （GGG） nanopowders doped with ytterbium ions （Yb：GGG） were synthesized with citric acid as a fuel via gel combustion method. The optimized conditions for preparing yb^3＋：Gd3Ga5O12 nanopo...Gadolinium gallium gamet （GGG） nanopowders doped with ytterbium ions （Yb：GGG） were synthesized with citric acid as a fuel via gel combustion method. The optimized conditions for preparing yb^3＋：Gd3Ga5O12 nanopowders were discussed. The heat behavior, structure and morphology of powders were analyzed with thermal analysis （TG-DTA）, X-ray diffraction （XRD）, infrared spectra OR） and transmission electron microscope （TEM）. TG-DTA analysis revealed that the weight loss of the precursor occured below 800 ℃ and its crystallization temperature was 830.6℃. XRD and IR analysis showed that the precursor converted directly into pure GGG at a relatively lower temperature （900 ℃） without any other intermediate phase. The lattice constant was 1.2377 calculated by extrapolation method. TEM results indicated that the spherical powders showed good dispersity and had a relatively narrow size distribution with average particle size of approximately 40-50 ran, which was favorable for good sinterability of Yb：GGG laser ceramic.展开更多
基金financially supported by the Science and Technology Research Project of Department of Education of Liaoning Province,China(No.L2011063)
文摘Nanocrystalline Gd3Ga5O12:Eu3+ with cubic phase was prepared by a urea homogeneous precipitation method. X-ray diffraction (XRD), field emission scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), thermo-gravimetric and differential thermal analysis (TG-DTA) and photoluminescence spectra were used to characterize the samples. The effects of the initial solution pH value and urea content on the structure of the sample were studied. The XRD results show that pure phase Gd3Ga5O12 can be obtained at pH =6 and pH =8 of the initial solution. The average crystallite size can be calculated as in the range of 24~33 nm. The average crystallite size decreases with increasing molar ratio of urea to metal ion. The results of excitation spectra and emission spectra show that the emission peaks are ascribed to 5D0→7FJ transitions of Eu3+, and the magnetic dipole transition originated from 5D0 →7F1 of Eu3+ is the strongest; the broad excitation bands belong to change transfer band of Eu?O and the host absorption of Gd3Ga5O12. An efficient energy transfer occurs from Gd3+ to Eu3+.
基金Funded by the Science and Technology Research Project of Department of Education of Liaoning Province,China(No.L2011063)
文摘A series of Er3＋, Tm3＋ and Yb3＋ doped Gd3Ga5O12 nanocrystals were prepared by a combustion method. The X-ray diffraction （XRD）, field emission scanning electron microscope （FESEM） and upconversion （UC） emission spectra were used to characterize the samples. The results of XRD indicate that Gd3Ga5O12：Er3＋, Tm3＋, Yb3＋ nanocrystals with cubic phase can be obtained. Under the excitation of a 980 nm laser, the different rare earth ions doped Gd3Ga5O12 nanoerystals show upconversion luminescence involving the green emission attributed to the ^2H11/2→^4I15/2, 4^S3/2→^4I15/2 transitions of Er3＋ ions, respectively, the red emissions assigned to the ^4F9/2→^4I15/2 transitions of Er3＋ ions and the ^1G4→^3F4 as well as 3F2,3→^3H6 transitions of Tm3＋ ions, respectively, the blue emission attributed to ^1G4→^3H6 transitions of Tm3＋ ions, and the near-infrared assigned to the ^3H4→^3H6 transitions of Tm3＋ ions. The CIE coordinates for the samples are calculated. The dependence of their upconversion luminescence properties on Yb3＋ ion concentration is investieated.
基金Project supported bythe Nature Science Foundation of Jilin Province (20000516)
文摘Nd^3＋： Gd3Ga5O12（Nd ： GGG） nanopowder for transparent laser ceramics was synthesized using sol-gel method. XRD, SEM, and fluorescence spectrum were used to study the properties of Nd^3＋ ：Gd3Ga5O12 nanopowder. XRD patterns of samples show that it has a cubic structure. Meanwhile, pure Nd：GGG crystals were obtained at 1000 ℃ for 12 h. SEM photographs show that dispersed, uniform, ball-like Nd：GGG nanopowder is obtained. Both XRD and SEM results show that the crystallization degree and the grain size increase with the increase in calcining temperature. Analysis of fluorescence spectrum shows that fluorescence emission occurs at 1062.7 nm, which is the result of Nd^3＋ （^4F3/2→^4I11/2） transition. Homogenous Nd ： GGG nanopewder with a small grain size synthesized using the sol-gel method is favorable for sintering the transparent ceramic, which proves that the nanopewder obtained is suitable as a precursor for preparing GGG transparent ceramics.
文摘The Ytterbium doped gadolinium gallium garnet [Yb3＋：Gd3Ga5O12, Yb：GGG] precursor powders were synthesized via homogeneous precipitation method using Yb2O3, Ga2O3, Gd2O3 and ammonium bicarbonate [NH4HCO3] as precipitator, and ammonium sulfate [（NH4）2SO4] as additive. The evolution of phase composition and micro-structure of the powders were characterized by TG- DTA, XRD, IR, and TEM. The results indicate that all precursor powders completely transform to Yb：GGG phase by calcining at 900 ℃ for 8 h, the resultant powders are well dispersed and have smaller particle size approximately 80 nm owing to the electrostatic effect.
基金Supported by the Science & Technology Plan Project of Fujian Province (Nos 2005HZ1026 and 2007H0037)the Great Projects of FJIRSM (SZD08001-2 and SZD09001)the Open Science Foundation from Key Laboratory of Optoelectronic Materials Chemistry and Physics of CAS (No 2009KL004)
文摘Yb3＋/Tm3＋ co-doped Gd3Ga5O12 single crystal with a dimension of Φ30mm×20mm was grown successfully by Czochralski method.The absorption spectrum was recorded at room temperature and used to calculate the absorption cross-section.Based on the Judd-Ofelt（J-O） theory,we obtained the three intensity parameters and spectral parameters of this crystal,such as the line strengths,oscillator strengths,radiative probabilities and radiative lifetimes as well as the fluorescent branching ratios.Room temperature fluorescence spectra and luminescence decay curves were recorded.The energy transfer between Yb3＋-Tm3＋ was observed and the mechanism was discussed.The stimulated emission cross-section of the 3F4→3H6 transition was calculated by the Füchtbauer-Ladenburg（F-L） equation.The potential laser gains for this transition were also investigated.This crystal is promising as a tunable infrared laser crystal at 2.0 μm.
文摘Preparation of Nd3+:Gd3Ga5O12 polycrystalline material by sol-gel method was preparated in this paper.The structure and the pattern of the sample were analyzed by thermogravimetric analysis and differential thermal analysis（TG-DTA）,Infrared spectrum,XRD,TEM and electron spectrum,which indicated that the powder with good characteristics of 70-100 nm can be obtained by sintering at 1 000℃.It was shown that the chemical composition of the sample was agreed with experimental requirements by electron spectrum analysis.
基金supported by the Foundation of Ordnance Science Institute (42001070403)
文摘Gadolinium gallium gamet （GGG） nanopowders doped with ytterbium ions （Yb：GGG） were synthesized with citric acid as a fuel via gel combustion method. The optimized conditions for preparing yb^3＋：Gd3Ga5O12 nanopowders were discussed. The heat behavior, structure and morphology of powders were analyzed with thermal analysis （TG-DTA）, X-ray diffraction （XRD）, infrared spectra OR） and transmission electron microscope （TEM）. TG-DTA analysis revealed that the weight loss of the precursor occured below 800 ℃ and its crystallization temperature was 830.6℃. XRD and IR analysis showed that the precursor converted directly into pure GGG at a relatively lower temperature （900 ℃） without any other intermediate phase. The lattice constant was 1.2377 calculated by extrapolation method. TEM results indicated that the spherical powders showed good dispersity and had a relatively narrow size distribution with average particle size of approximately 40-50 ran, which was favorable for good sinterability of Yb：GGG laser ceramic.
