The homogeneously dispersed, less agglomerated (Nd0.01Y0.99)3Al5O12 nano-sized powders were synthesized by the low temperature combustion (LCS), using Nd2O3, Y2O3, Al(NO3)3·9H2O, ammonia water and citric acid as ...The homogeneously dispersed, less agglomerated (Nd0.01Y0.99)3Al5O12 nano-sized powders were synthesized by the low temperature combustion (LCS), using Nd2O3, Y2O3, Al(NO3)3·9H2O, ammonia water and citric acid as starting materials. This method effectively solves the problems caused by solid-state reaction at high temperature and hard agglomerates brought by the chemical precipitation method. The powders were characterized by TG-DTA, XRD, FT-IR, TEM respectively and the photoluminescence (PL) spectra of (Nd0.01Y0.99)3Al5O12 green and sintered ceramic disks were measured. The results show that the forming temperature of YAG crystal phase is 850 ℃ and YAP crystal phase appearing during the calcinations transforms to pure YAG at 1050 ℃. The particle size of the powders synthesized by the LCS is in a range of 20～50 nm depending on the thermal treatment temperatures. The effectively induced cross section (σin) with the value 4.03×10-19 cm2 of (Nd0.01Y0.99)3Al5O12 ceramics is about 44% higher than that of single crystal.展开更多
substitutes tion, high loosely dis Neodymium doped-yttrium aluminum garnet （Nd ： YAG） transparent polycrystalline ceramics already become of single crystals because they are provided with easy fabrication, low cost...substitutes tion, high loosely dis Neodymium doped-yttrium aluminum garnet （Nd ： YAG） transparent polycrystalline ceramics already become of single crystals because they are provided with easy fabrication, low cost, large size, highly doped concentraheat conductivity, mass fabrication, multi-layers and multi-filnctions. The Nd：YAG precursor powders with persed , slightly agglomerated, super fine and YAG cubic crystal phase were synthesized at 1100 ℃ by the homogeneous precipitation method, using Nd2O3, Y2O3, Al（NO3）3·9H2O and urea as raw materials, （NH4）2SO4 as electrical stabilizer, TEOS as sintering additive. The Nd：YAG transparent ceramics were prepared after being vacuum sintered at 1700 ℃ for 5 h. The Nd：YAG ceramic materials were characterized by the TG-DTA, XRD, FT-IR, TEM, FEG-ESEM and FT-PL. The results show that the crystallization temperature of YAG is 850 ℃ and the intermediate crystal phase YAP forming during the heat treatment transforms to YAG cubic crystal phase at 1050 ℃. The lasing wavelength of （Nd0.01 Y0.99）3Al5O12 transparent ceramics is 1.065 μm and there exists a slight red-shift compared to the single crystal with the same chemical composition. The optical transmittance is 45 % in the visible light and 58 % in the near infrared light and the optical transmittance descends with the decreasing the wavelength.展开更多
Nd∶YAG precursor powders were synthesized by homogeneous precipitation and Nd∶YAG transparent ceramics were prepared by vacuum sintering at 1700 ℃ for 5 h. The ceramic materials were characterized by light transmit...Nd∶YAG precursor powders were synthesized by homogeneous precipitation and Nd∶YAG transparent ceramics were prepared by vacuum sintering at 1700 ℃ for 5 h. The ceramic materials were characterized by light transmittance, field emission gun-environment scanning microscope. Fractal geometry was used to study the quantitative relationships between light transmittance and fractal dimensions of Nd∶YAG transparent ceramics. It was found that the transmittance of Nd∶YAG with 1 mm in thickness was about 45% and 58% in visible and near-infrared region respectively. The microstructures of Nd∶YAG transparent ceramics were obvious fractal characteristic and fractal dimensions depart a little from two-dimension. The light transmittance decreased with increasing of fractal dimension and nonlinear fit curve was y=1350-1185x+269x2 between fractal dimension and light transmittance of Nd∶YAG transparent ceramics.展开更多
铕掺杂钒酸钇(YVO_4:Eu^(3+))作为常用的下转换发光材料一直受到广泛的关注和研究,但是YVO_4:Eu^(3+)的表面缺陷会严重影响材料的发光效率。为了进一步改善YVO_4:Eu^(3+)纳米粉体材料的粒度分布和形貌特点,在亚微米级别的SiO_2微球表面...铕掺杂钒酸钇(YVO_4:Eu^(3+))作为常用的下转换发光材料一直受到广泛的关注和研究,但是YVO_4:Eu^(3+)的表面缺陷会严重影响材料的发光效率。为了进一步改善YVO_4:Eu^(3+)纳米粉体材料的粒度分布和形貌特点,在亚微米级别的SiO_2微球表面涂覆一层YVO_4:Eu^(3+),制成YVO_4:Eu^(3+)@SiO_2核–壳结构,得到单分散的球形YVO_4:Eu^(3+)下转换发光材料,实现YVO_4:Eu^(3+)的发光性能和SiO_2球形特性的有机结合。研究发现,当壳核比为0.6时,YVO_4:Eu^(3+)@SiO_2核–壳结构材料的发光强度可达到纯纳米粉体材料发光强度的90%以上。将改性后的YVO_4:Eu^(3+)@SiO_2核–壳结构材料涂覆在硅基薄膜太阳电池上,可使电池的短路电流密度和转化效率分别由6.694 m A/cm^2和9.40%提升至8.417 m A/cm^2和10.15%,增益效果较为明显。实验结果表明,采用溶液法制备的YVO_4:Eu^(3+)@SiO_2纳米粉体材料由于具有形貌规则、团聚小和尺寸分布均匀等特点,可用作硅基薄膜太阳电池下转换发光层材料。展开更多
文摘The homogeneously dispersed, less agglomerated (Nd0.01Y0.99)3Al5O12 nano-sized powders were synthesized by the low temperature combustion (LCS), using Nd2O3, Y2O3, Al(NO3)3·9H2O, ammonia water and citric acid as starting materials. This method effectively solves the problems caused by solid-state reaction at high temperature and hard agglomerates brought by the chemical precipitation method. The powders were characterized by TG-DTA, XRD, FT-IR, TEM respectively and the photoluminescence (PL) spectra of (Nd0.01Y0.99)3Al5O12 green and sintered ceramic disks were measured. The results show that the forming temperature of YAG crystal phase is 850 ℃ and YAP crystal phase appearing during the calcinations transforms to pure YAG at 1050 ℃. The particle size of the powders synthesized by the LCS is in a range of 20～50 nm depending on the thermal treatment temperatures. The effectively induced cross section (σin) with the value 4.03×10-19 cm2 of (Nd0.01Y0.99)3Al5O12 ceramics is about 44% higher than that of single crystal.
文摘substitutes tion, high loosely dis Neodymium doped-yttrium aluminum garnet （Nd ： YAG） transparent polycrystalline ceramics already become of single crystals because they are provided with easy fabrication, low cost, large size, highly doped concentraheat conductivity, mass fabrication, multi-layers and multi-filnctions. The Nd：YAG precursor powders with persed , slightly agglomerated, super fine and YAG cubic crystal phase were synthesized at 1100 ℃ by the homogeneous precipitation method, using Nd2O3, Y2O3, Al（NO3）3·9H2O and urea as raw materials, （NH4）2SO4 as electrical stabilizer, TEOS as sintering additive. The Nd：YAG transparent ceramics were prepared after being vacuum sintered at 1700 ℃ for 5 h. The Nd：YAG ceramic materials were characterized by the TG-DTA, XRD, FT-IR, TEM, FEG-ESEM and FT-PL. The results show that the crystallization temperature of YAG is 850 ℃ and the intermediate crystal phase YAP forming during the heat treatment transforms to YAG cubic crystal phase at 1050 ℃. The lasing wavelength of （Nd0.01 Y0.99）3Al5O12 transparent ceramics is 1.065 μm and there exists a slight red-shift compared to the single crystal with the same chemical composition. The optical transmittance is 45 % in the visible light and 58 % in the near infrared light and the optical transmittance descends with the decreasing the wavelength.
基金Study on Optical Properties and Structure of Transparent Ceramics,Chinese Education Ministry Excellent Teachers Project (KB200226)
文摘Nd∶YAG precursor powders were synthesized by homogeneous precipitation and Nd∶YAG transparent ceramics were prepared by vacuum sintering at 1700 ℃ for 5 h. The ceramic materials were characterized by light transmittance, field emission gun-environment scanning microscope. Fractal geometry was used to study the quantitative relationships between light transmittance and fractal dimensions of Nd∶YAG transparent ceramics. It was found that the transmittance of Nd∶YAG with 1 mm in thickness was about 45% and 58% in visible and near-infrared region respectively. The microstructures of Nd∶YAG transparent ceramics were obvious fractal characteristic and fractal dimensions depart a little from two-dimension. The light transmittance decreased with increasing of fractal dimension and nonlinear fit curve was y=1350-1185x+269x2 between fractal dimension and light transmittance of Nd∶YAG transparent ceramics.
文摘铕掺杂钒酸钇(YVO_4:Eu^(3+))作为常用的下转换发光材料一直受到广泛的关注和研究,但是YVO_4:Eu^(3+)的表面缺陷会严重影响材料的发光效率。为了进一步改善YVO_4:Eu^(3+)纳米粉体材料的粒度分布和形貌特点,在亚微米级别的SiO_2微球表面涂覆一层YVO_4:Eu^(3+),制成YVO_4:Eu^(3+)@SiO_2核–壳结构,得到单分散的球形YVO_4:Eu^(3+)下转换发光材料,实现YVO_4:Eu^(3+)的发光性能和SiO_2球形特性的有机结合。研究发现,当壳核比为0.6时,YVO_4:Eu^(3+)@SiO_2核–壳结构材料的发光强度可达到纯纳米粉体材料发光强度的90%以上。将改性后的YVO_4:Eu^(3+)@SiO_2核–壳结构材料涂覆在硅基薄膜太阳电池上,可使电池的短路电流密度和转化效率分别由6.694 m A/cm^2和9.40%提升至8.417 m A/cm^2和10.15%,增益效果较为明显。实验结果表明,采用溶液法制备的YVO_4:Eu^(3+)@SiO_2纳米粉体材料由于具有形貌规则、团聚小和尺寸分布均匀等特点,可用作硅基薄膜太阳电池下转换发光层材料。
