The positron annihilation lifetimes and the Doppler broadening by slow positron beam are measured in thin Fe films with thickness 500 nm, a thin Hf film with thickness 100 nm, and the bilayer Fe (50 nm)/Hf (50 nm) on ...The positron annihilation lifetimes and the Doppler broadening by slow positron beam are measured in thin Fe films with thickness 500 nm, a thin Hf film with thickness 100 nm, and the bilayer Fe (50 nm)/Hf (50 nm) on quartz glass substrate. We have analyzed the behavior in vacancy-type defects in each layer through some deposition temperatures and annealing. It is observed that the thin Fe film, the thin Hf film, and the bilayer Fe (50 nm)/Hf (50 nm) already contain many vacancy-type defects. We have investigated the change of densities of the vacancy-carbon complex and the small vacancy-cluster with carbons, through solid-state amorphization of Fe (50 nm)/Hf (50 nm) bilayer.展开更多
High translucency is one of the excellent properties of AlN ceramics because of its wide optical band gap energy of 6.2 eV. We have achieved success in producing AlN ceramic tube of 98% total visible light transmittan...High translucency is one of the excellent properties of AlN ceramics because of its wide optical band gap energy of 6.2 eV. We have achieved success in producing AlN ceramic tube of 98% total visible light transmittance at 0.6 mm thick tube wall by applying an improved sintering technique. This AlN ceramic was produced by sintering at 1880℃ using Ca3Al2O6 as a sintering additive and in reduction atmosphere to remove the sintering additive from the final sintered material. After the sintering, the annealing with Al2O3 was carried out to improve the transmittance of AlN ceramics. The amount of metal impurities and carbon were 27ppm and 100ppm, respectively. It is noteworthy that the amount of oxygen in AlN ceramics after the annealing was 0.36wt% which was higher than the 0.07wt% of the as-sintered AlN ceramics. Therefore, total transmittance was improved by the oxygen doping. On the other hand, thermal conductivity of AlN after the annealing was lowered by 35% compared with that of as-sintered AlN. Positron Annihilation Lifetime (PAL) measurement was applied to investigation of a relationship between the total transmittance and lattice defects. The present PAL results confirms the presence of negatively charged atomic-size vacancies that is aluminum site vacancies and also sug-gests the increase in the concentration of the vacancies after the annealing compared with that of the as-sintered material. However, it can be concluded that there is no relation between aluminum site va-cancies and the light transmittance of AlN ceramics.展开更多
文摘The positron annihilation lifetimes and the Doppler broadening by slow positron beam are measured in thin Fe films with thickness 500 nm, a thin Hf film with thickness 100 nm, and the bilayer Fe (50 nm)/Hf (50 nm) on quartz glass substrate. We have analyzed the behavior in vacancy-type defects in each layer through some deposition temperatures and annealing. It is observed that the thin Fe film, the thin Hf film, and the bilayer Fe (50 nm)/Hf (50 nm) already contain many vacancy-type defects. We have investigated the change of densities of the vacancy-carbon complex and the small vacancy-cluster with carbons, through solid-state amorphization of Fe (50 nm)/Hf (50 nm) bilayer.
文摘High translucency is one of the excellent properties of AlN ceramics because of its wide optical band gap energy of 6.2 eV. We have achieved success in producing AlN ceramic tube of 98% total visible light transmittance at 0.6 mm thick tube wall by applying an improved sintering technique. This AlN ceramic was produced by sintering at 1880℃ using Ca3Al2O6 as a sintering additive and in reduction atmosphere to remove the sintering additive from the final sintered material. After the sintering, the annealing with Al2O3 was carried out to improve the transmittance of AlN ceramics. The amount of metal impurities and carbon were 27ppm and 100ppm, respectively. It is noteworthy that the amount of oxygen in AlN ceramics after the annealing was 0.36wt% which was higher than the 0.07wt% of the as-sintered AlN ceramics. Therefore, total transmittance was improved by the oxygen doping. On the other hand, thermal conductivity of AlN after the annealing was lowered by 35% compared with that of as-sintered AlN. Positron Annihilation Lifetime (PAL) measurement was applied to investigation of a relationship between the total transmittance and lattice defects. The present PAL results confirms the presence of negatively charged atomic-size vacancies that is aluminum site vacancies and also sug-gests the increase in the concentration of the vacancies after the annealing compared with that of the as-sintered material. However, it can be concluded that there is no relation between aluminum site va-cancies and the light transmittance of AlN ceramics.
