Ag/LaCoO3 perovskite catalysts for soot combustion were prepared by the impregnation method.The structure and physicochemical properties of the catalysts were characterized using X-ray diffraction,N2 adsorption-desorp...Ag/LaCoO3 perovskite catalysts for soot combustion were prepared by the impregnation method.The structure and physicochemical properties of the catalysts were characterized using X-ray diffraction,N2 adsorption-desorption,H2 temperature-programmed reduction,soot temperatureprogrammed reduction,and X-ray photoelectron spectroscopy.The catalytic activity of the catalysts for soot oxidation was tested by temperature-programmed oxidation in air and in a NOx atmosphere.Metallic Ag particles were the main Ag species.Part of the Ag migrated from the surface to the lattice of the LaCoO3 perovskite,to form La（1-x）AgxCoO3.This increased the amount of oxygen vacancies in the perovskite structure during thermal treatment.Compared with unmodified LaCoO3,the maximum soot oxidation rate temperature（Tp） decreased by 50-70 ℃ in air when LaCoO3 was partially modified by Ag,depending on the thermal treatment temperature.The Tp of the Ag/LaCoO3catalyst calcined at 400℃ in a NOx atmosphere decreased to about 140℃,compared with that of LaCoO3.Ag particles and oxygen vacancies in the catalysts contributed to their high catalytic activity for soot oxidation.The stable catalytic activity of the Ag/LaCoO3 catalyst calcined at 700℃ in a NOx atmosphere was related to its stable structure.展开更多
This work is a study of effect of laser ablation in different medium on silver artifacts. The effectiveness of laser ablation cleanness methods was evaluated in air, water and vacuum condition. The samples were subjec...This work is a study of effect of laser ablation in different medium on silver artifacts. The effectiveness of laser ablation cleanness methods was evaluated in air, water and vacuum condition. The samples were subjected to HC1 treatment for several hours to simulate the formation of chloride patina on marine archeological artifacts. Laser ablation removes the patina in all medium, reducing its thickness from 300 to few microns in air and water and eliminating completely the chlorine in vacuum conditions. However, it was observed the formation, during cleanness of a white patina in air and water and an increasing of oxygen amount on surface. This indicate that in ambient reach in oxygen laser ablation favorite the oxygen absorbance on surface and the formation of a thin layer of AgO which dulls the surface. This hypothesis is confirmed by the results of laser ablation in vacuum conditions where surface tarnishing was not observed. So, laser ablation in vacuum condition was indicated as the most effective procedure to clean silver artifacts.展开更多
0107487烧银电极对 SrTiO<sub>3</sub>环形压敏电阻器性能的影响[刊]/李建英//电子元件与材料.—2000,19（6）.—1～2（C）Y2000-62524-205 0107488采用局部辐照对大面积太阳能电池进行诊断=Diag-nostics of large-area sol...0107487烧银电极对 SrTiO<sub>3</sub>环形压敏电阻器性能的影响[刊]/李建英//电子元件与材料.—2000,19（6）.—1～2（C）Y2000-62524-205 0107488采用局部辐照对大面积太阳能电池进行诊断=Diag-nostics of large-area solar cells by local irradiation[会,英]/Radil,J.& Benda,V.//2000 IEEE Proceedingsof 22nd International Conference on Microelectronics,Vol.1.—205～207（EC）展开更多
文摘Ag/LaCoO3 perovskite catalysts for soot combustion were prepared by the impregnation method.The structure and physicochemical properties of the catalysts were characterized using X-ray diffraction,N2 adsorption-desorption,H2 temperature-programmed reduction,soot temperatureprogrammed reduction,and X-ray photoelectron spectroscopy.The catalytic activity of the catalysts for soot oxidation was tested by temperature-programmed oxidation in air and in a NOx atmosphere.Metallic Ag particles were the main Ag species.Part of the Ag migrated from the surface to the lattice of the LaCoO3 perovskite,to form La（1-x）AgxCoO3.This increased the amount of oxygen vacancies in the perovskite structure during thermal treatment.Compared with unmodified LaCoO3,the maximum soot oxidation rate temperature（Tp） decreased by 50-70 ℃ in air when LaCoO3 was partially modified by Ag,depending on the thermal treatment temperature.The Tp of the Ag/LaCoO3catalyst calcined at 400℃ in a NOx atmosphere decreased to about 140℃,compared with that of LaCoO3.Ag particles and oxygen vacancies in the catalysts contributed to their high catalytic activity for soot oxidation.The stable catalytic activity of the Ag/LaCoO3 catalyst calcined at 700℃ in a NOx atmosphere was related to its stable structure.
文摘This work is a study of effect of laser ablation in different medium on silver artifacts. The effectiveness of laser ablation cleanness methods was evaluated in air, water and vacuum condition. The samples were subjected to HC1 treatment for several hours to simulate the formation of chloride patina on marine archeological artifacts. Laser ablation removes the patina in all medium, reducing its thickness from 300 to few microns in air and water and eliminating completely the chlorine in vacuum conditions. However, it was observed the formation, during cleanness of a white patina in air and water and an increasing of oxygen amount on surface. This indicate that in ambient reach in oxygen laser ablation favorite the oxygen absorbance on surface and the formation of a thin layer of AgO which dulls the surface. This hypothesis is confirmed by the results of laser ablation in vacuum conditions where surface tarnishing was not observed. So, laser ablation in vacuum condition was indicated as the most effective procedure to clean silver artifacts.
文摘0107487烧银电极对 SrTiO<sub>3</sub>环形压敏电阻器性能的影响[刊]/李建英//电子元件与材料.—2000,19（6）.—1～2（C）Y2000-62524-205 0107488采用局部辐照对大面积太阳能电池进行诊断=Diag-nostics of large-area solar cells by local irradiation[会,英]/Radil,J.& Benda,V.//2000 IEEE Proceedingsof 22nd International Conference on Microelectronics,Vol.1.—205～207（EC）
