Rare earths(REs),as a kind of key elements widely used in high-tech industry,have been paid more and more attention all over the world.At a time when the world trade war is raging,dignitaries and executives are trying...Rare earths(REs),as a kind of key elements widely used in high-tech industry,have been paid more and more attention all over the world.At a time when the world trade war is raging,dignitaries and executives are trying to control this strategic resource,while scientific and technological re-searchers are trying to solve the scientific and technological problems in the development of RE industry.The innovation research of RE materials are orientated by three main aspects as shown in Figure 1:one is to make the production process of RE materials more green and sustainable,the second is to strengthen the material properties and save energy,and the third is to find new functional materials with improved quality..展开更多
YAG∶Ce 3+ phosphor particles were prepared using polyacrylamide gel method. The structure evolution of powders during annealing process was followed by X-ray diffraction determination. It is found that some intermedi...YAG∶Ce 3+ phosphor particles were prepared using polyacrylamide gel method. The structure evolution of powders during annealing process was followed by X-ray diffraction determination. It is found that some intermediate phases, including θ-Al2O3, YAM and YAP, are formed when calcining polyacrylamide gel, however, the pure YAG phase can be formed directly when calcining polyacrylamide gel with α-Al2O3 as seed crystal. These facts show that the existence of α-Al2O3 seed crystal can block the formation of θ-Al2O3, YAM and YAP, and accelerate its reaction with Y2O3 to form YAG phase directly at lower temperature. The emission peak of prepared YAG∶Ce 3+ phosphor is wide with maximum at 550 nm and the exitation band has two peaks, the major one is around at 460 nm, which matches the blue emission of GaN LED and is suitable for the assemble of white LED. Some fluxes can enhance the photoluminescence intensity of phosphor particles, that can be attributed both to the improvement of crystallization processes of YAG and to the stabilization of trivalence cerium ion in YAG∶Ce 3+.展开更多
Lanthanum hydroxide with rod-like morphology was synthesized with simple hydration processing via the hydration of its bulk oxide in normal water solution at boiling temperature. An XRD pattern shows the formation of ...Lanthanum hydroxide with rod-like morphology was synthesized with simple hydration processing via the hydration of its bulk oxide in normal water solution at boiling temperature. An XRD pattern shows the formation of the hexagonal phase of La（OH）3, indicating that the hydration process is very rapid. The as-prepared La（OH）3 is almost entirely with a needle- or rod-like shape with a width of 2～3 μm and a length of 5～8 μm. The mechanism of the formation of La（OH）3 with rod-like morphology was preliminarily presented. It is easier to expand the simple hydration process on a large scale than the hydrothermal process.展开更多
The porous cubic yttrium oxides with high specific surface area were prepared by the explosive decomposition of yttrium nitrate and its complex formed with methyl salicylate. The specific surface area and properties o...The porous cubic yttrium oxides with high specific surface area were prepared by the explosive decomposition of yttrium nitrate and its complex formed with methyl salicylate. The specific surface area and properties of powders synthesized at various temperatures were characterized using BET, X-ray diffraction (XRD), infrared spectra (IR), and scanning electron microscopy (SEM). The results indicate that the highest specific surface area is found to be 65.37 m2·g -1 at the calcination temperature of 600 ℃, and then decreases to 20.33 m2·g -1 with the calcination temperature rising from 600 to 900 ℃. The powders show strong surface activity for adsorping water and carbon dioxide in air, which also decreases with the rising calcination temperature. The drop both on the surface area and surface activity of samples at higher temperatures may be due to pore-narrowing(sintering) effects.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.51864033)the Key R&D Program of the Ministry of Science and Technology(Grant No.2019YFC0605000)Major Projects of Consulting and Research of the Chinese Academy of Engineering(Grant No.2018-ZD-11)
文摘Rare earths(REs),as a kind of key elements widely used in high-tech industry,have been paid more and more attention all over the world.At a time when the world trade war is raging,dignitaries and executives are trying to control this strategic resource,while scientific and technological re-searchers are trying to solve the scientific and technological problems in the development of RE industry.The innovation research of RE materials are orientated by three main aspects as shown in Figure 1:one is to make the production process of RE materials more green and sustainable,the second is to strengthen the material properties and save energy,and the third is to find new functional materials with improved quality..
基金Project supported by the National Natural Science Foundation of China (50306008)Advance Research Foundation forGeneral Equipment Department (41328030507)
文摘缩放 Nano 的氧化钇粒子基于含水的钇硝酸盐和乙二醇经由非水的 sol-gelprocess 被综合。到雏晶上的钇离子和锻烧温度的乙二醇的臼齿的比率的效果产品缩放我们再学习。为铵 perehlorate (AP ) 的同样准备的氧化钇的催化表演分解被微分扫描调查热量测定(DSC ) 。结果显示有在平均雏晶尺寸的不到 20 nm 的 缩放nano 的立方的氧化钇粒子能在 70 deg C 在 2 h 倒流以后被获得，在 90 deg C 弄干，形成 xerogel ，并且由为 2 h xerogel 退火列在后面，并且到 AP 的 缩放nano 的氧化钇的增加在温度合并 AP 的二座小发热的山峰，这 310 ~变化 350 deg C 并且 400 - 470 deg C 进 AP 和增加的一座强壮的发热的山峰从 515 的明显的分解热到超过 1110 Jcentre 点g~(-1)。发热的山峰减少和明显的分解 AP 加热的 AP 分解的温度随数量的增加增加缩放 ofnano 的氧化钇，也是清楚的。到 AP 的5% 缩放nano 的氧化钇的增加减少的事实到由 114.6 deg C 的减小的 337.7 deg C 的 AP 发热的山峰的温度，并且从 515～1240 J 中心点g~增加明显的分解热(-1),揭示那 缩放nano 的氧化钇 hows 为 AP 的强壮的催化性质热分解。
文摘YAG∶Ce 3+ phosphor particles were prepared using polyacrylamide gel method. The structure evolution of powders during annealing process was followed by X-ray diffraction determination. It is found that some intermediate phases, including θ-Al2O3, YAM and YAP, are formed when calcining polyacrylamide gel, however, the pure YAG phase can be formed directly when calcining polyacrylamide gel with α-Al2O3 as seed crystal. These facts show that the existence of α-Al2O3 seed crystal can block the formation of θ-Al2O3, YAM and YAP, and accelerate its reaction with Y2O3 to form YAG phase directly at lower temperature. The emission peak of prepared YAG∶Ce 3+ phosphor is wide with maximum at 550 nm and the exitation band has two peaks, the major one is around at 460 nm, which matches the blue emission of GaN LED and is suitable for the assemble of white LED. Some fluxes can enhance the photoluminescence intensity of phosphor particles, that can be attributed both to the improvement of crystallization processes of YAG and to the stabilization of trivalence cerium ion in YAG∶Ce 3+.
基金Project supported bythe National Natural Science Foundation of China (20161002) ,the Natural Science Foundation of JiangxiProvince (0220004) and the Education Department of Jiangxi Province
文摘Lanthanum hydroxide with rod-like morphology was synthesized with simple hydration processing via the hydration of its bulk oxide in normal water solution at boiling temperature. An XRD pattern shows the formation of the hexagonal phase of La（OH）3, indicating that the hydration process is very rapid. The as-prepared La（OH）3 is almost entirely with a needle- or rod-like shape with a width of 2～3 μm and a length of 5～8 μm. The mechanism of the formation of La（OH）3 with rod-like morphology was preliminarily presented. It is easier to expand the simple hydration process on a large scale than the hydrothermal process.
文摘The porous cubic yttrium oxides with high specific surface area were prepared by the explosive decomposition of yttrium nitrate and its complex formed with methyl salicylate. The specific surface area and properties of powders synthesized at various temperatures were characterized using BET, X-ray diffraction (XRD), infrared spectra (IR), and scanning electron microscopy (SEM). The results indicate that the highest specific surface area is found to be 65.37 m2·g -1 at the calcination temperature of 600 ℃, and then decreases to 20.33 m2·g -1 with the calcination temperature rising from 600 to 900 ℃. The powders show strong surface activity for adsorping water and carbon dioxide in air, which also decreases with the rising calcination temperature. The drop both on the surface area and surface activity of samples at higher temperatures may be due to pore-narrowing(sintering) effects.
