The KGd(WO 4) 2[KGW] crystal has a structure belonging to the monoclinic sys tem with space group C 2/ c and with unit cell dimensions a =1.068mm, b =1.043nm, c =0.76nm, β =130°.This crystal is an excellent host...The KGd(WO 4) 2[KGW] crystal has a structure belonging to the monoclinic sys tem with space group C 2/ c and with unit cell dimensions a =1.068mm, b =1.043nm, c =0.76nm, β =130°.This crystal is an excellent host material for solid state lasers.The threshold of the laser oscillations in a Nd 3+ d oped KGW laser crystal is considerable low and has a higher emissive section.T he fluorescent concentration quench effect of the Nd 3+ ion in the KGW crystal may be weakened due to the W O covalent bond,so this crystal has a higher dopi ng concentration of active ion.Furthermore,the absorption band at 808nm of Nd 3+ in the KGW crystal,which has 12nm FWHM,is well matched with the emission w avelength of a laser diode ,a solid state laser pump that is very convenient and popular in laser science and technology today.Therefore the KGW crystal has a l aser emission with higher output and higher efficiency.Scientists of laser techn ology circles are very interested in Yb 3+ doped laser crystals because they have four advanta ges when they are compared with Nd 3+ doped laser crystals.Firstly,their flu orescent lifetimes are three or four times as many as that of Nd 3+ doped la ser crystals,which is beneficial to reserving the energy.Secondly,the heat energ y,which is formed when laser is operating,will be decreased because the pumping band is close to the upper energy level.Not only will the use ratio of energy be increased but also the damage effect to laser properties will be decreased.Thir dly,there is no absorption problems of excite state because the energy level of Yb 3+ is simple.Finally,the higher optical quality crystals are easier to gr ow because the radius of Yb 3+ is closer to that of Gd 3+ .Furthermore,Y b 3+ doped laser crystals can substitute the Ti sapphire for the psec laser .展开更多
Along with the popularity of environmental protection concepts, the environmental treatment of water pollution attracts widespread attention, among which, the research on Bi-based semiconductor photocatalytic degradat...Along with the popularity of environmental protection concepts, the environmental treatment of water pollution attracts widespread attention, among which, the research on Bi-based semiconductor photocatalytic degradation technology has made great progress. However, the development of such bismuth-based composites still remains a challenging task due to difficult recovery and low catalytic efficiency. Herein, a novel CC/BiPO4</sub>/Bi2</sub>WO6</sub> composite was successfully synthesized through two-step hydrothermal method using activated flexible carbon cloth as a substrate. The results of the photocatalytic degradation experiments showed that the obtained CC/BiPO<sub>4</sub>/Bi<sub>2</sub>WO<sub>6</sub> composites can degrade 92.1% RhB in 60 min under UV-visible light irradiation, which was much higher than that of unloaded BiPO4</sub> (24.4%) and BiPO4</sub>/Bi2</sub>WO6</sub> (52.9%), exhibiting a better adsorption-photocatalytic degradation performance than BiPO4</sub> and BiPO4</sub>/Bi2</sub>WO6</sub>. Photoluminescence spectra indicated that the improved photocatalytic activity was due to the more effective inhibition of photogenerated carrier complexation. Furthermore, the radical capture experiments confirmed that h<sup>+</sup>, ·OH and O<sub>2</sub>-</sup> were the main active substances in the photocatalytic degradation process of RhB by the CC/BiPO4</sub>/Bi2</sub>WO6</sub> composites. More importantly, the prepared CC/BiPO4</sub>/Bi2</sub>WO6</sub> composite had a simple separation process and good recycling stability, and its photocatalytic degradation efficiency can still reach 53.3% after six cycles of RhB degradation. .展开更多
CdGd2 （WO4）4 -δ single crystal was grown using the Czochralski＇s method. The crystal structure was tetragonal seheelite with lattice parameters a = b = 0.5203 nm and c = 1. 1359 nm. There were vacancies of （WO4）...CdGd2 （WO4）4 -δ single crystal was grown using the Czochralski＇s method. The crystal structure was tetragonal seheelite with lattice parameters a = b = 0.5203 nm and c = 1. 1359 nm. There were vacancies of （WO4）^2- , therefore, there were some Gd^2＋ ions. Langevin paramagnetism and anisotropy were observed from the δ-T curves at room temperature. The susceptibility X//was 3.5018×10^-3, and X⊥ was 3.4403× 10^-2. The anisotropy was also observed in the electron spin resonance （ESR） experiments. The anisotropic Land6 factors were g//= 2. 1333 and g~ = 2. 8411. The direction of easy magnetization was in the α-b plane. Anisotropic paramagnetic Curie constants C//and C⊥ were not only related to macroscopic a that was observed through the experiment, but were also related to J⊥ and J//, which were the microscopic quantum numbers of the Gd^2＋ and Gd^3｜ ions. Based on the detailed analyses, the proportion of 36.8% of Gd^3＋ ions to 63.2% of Gd^2＋ ions in the Gd ions of the CdGd2（WO4）4-δ crystal was calculated, and δ was 0.638 in the single crystal.展开更多
文摘The KGd(WO 4) 2[KGW] crystal has a structure belonging to the monoclinic sys tem with space group C 2/ c and with unit cell dimensions a =1.068mm, b =1.043nm, c =0.76nm, β =130°.This crystal is an excellent host material for solid state lasers.The threshold of the laser oscillations in a Nd 3+ d oped KGW laser crystal is considerable low and has a higher emissive section.T he fluorescent concentration quench effect of the Nd 3+ ion in the KGW crystal may be weakened due to the W O covalent bond,so this crystal has a higher dopi ng concentration of active ion.Furthermore,the absorption band at 808nm of Nd 3+ in the KGW crystal,which has 12nm FWHM,is well matched with the emission w avelength of a laser diode ,a solid state laser pump that is very convenient and popular in laser science and technology today.Therefore the KGW crystal has a l aser emission with higher output and higher efficiency.Scientists of laser techn ology circles are very interested in Yb 3+ doped laser crystals because they have four advanta ges when they are compared with Nd 3+ doped laser crystals.Firstly,their flu orescent lifetimes are three or four times as many as that of Nd 3+ doped la ser crystals,which is beneficial to reserving the energy.Secondly,the heat energ y,which is formed when laser is operating,will be decreased because the pumping band is close to the upper energy level.Not only will the use ratio of energy be increased but also the damage effect to laser properties will be decreased.Thir dly,there is no absorption problems of excite state because the energy level of Yb 3+ is simple.Finally,the higher optical quality crystals are easier to gr ow because the radius of Yb 3+ is closer to that of Gd 3+ .Furthermore,Y b 3+ doped laser crystals can substitute the Ti sapphire for the psec laser .
文摘Along with the popularity of environmental protection concepts, the environmental treatment of water pollution attracts widespread attention, among which, the research on Bi-based semiconductor photocatalytic degradation technology has made great progress. However, the development of such bismuth-based composites still remains a challenging task due to difficult recovery and low catalytic efficiency. Herein, a novel CC/BiPO4</sub>/Bi2</sub>WO6</sub> composite was successfully synthesized through two-step hydrothermal method using activated flexible carbon cloth as a substrate. The results of the photocatalytic degradation experiments showed that the obtained CC/BiPO<sub>4</sub>/Bi<sub>2</sub>WO<sub>6</sub> composites can degrade 92.1% RhB in 60 min under UV-visible light irradiation, which was much higher than that of unloaded BiPO4</sub> (24.4%) and BiPO4</sub>/Bi2</sub>WO6</sub> (52.9%), exhibiting a better adsorption-photocatalytic degradation performance than BiPO4</sub> and BiPO4</sub>/Bi2</sub>WO6</sub>. Photoluminescence spectra indicated that the improved photocatalytic activity was due to the more effective inhibition of photogenerated carrier complexation. Furthermore, the radical capture experiments confirmed that h<sup>+</sup>, ·OH and O<sub>2</sub>-</sup> were the main active substances in the photocatalytic degradation process of RhB by the CC/BiPO4</sub>/Bi2</sub>WO6</sub> composites. More importantly, the prepared CC/BiPO4</sub>/Bi2</sub>WO6</sub> composite had a simple separation process and good recycling stability, and its photocatalytic degradation efficiency can still reach 53.3% after six cycles of RhB degradation. .
基金Project supported by the National Natural Science Foundation of China (69977005)
文摘CdGd2 （WO4）4 -δ single crystal was grown using the Czochralski＇s method. The crystal structure was tetragonal seheelite with lattice parameters a = b = 0.5203 nm and c = 1. 1359 nm. There were vacancies of （WO4）^2- , therefore, there were some Gd^2＋ ions. Langevin paramagnetism and anisotropy were observed from the δ-T curves at room temperature. The susceptibility X//was 3.5018×10^-3, and X⊥ was 3.4403× 10^-2. The anisotropy was also observed in the electron spin resonance （ESR） experiments. The anisotropic Land6 factors were g//= 2. 1333 and g~ = 2. 8411. The direction of easy magnetization was in the α-b plane. Anisotropic paramagnetic Curie constants C//and C⊥ were not only related to macroscopic a that was observed through the experiment, but were also related to J⊥ and J//, which were the microscopic quantum numbers of the Gd^2＋ and Gd^3｜ ions. Based on the detailed analyses, the proportion of 36.8% of Gd^3＋ ions to 63.2% of Gd^2＋ ions in the Gd ions of the CdGd2（WO4）4-δ crystal was calculated, and δ was 0.638 in the single crystal.
