A review is presented of studies of polymeric membranes by applying positron annihilation lifetime spectroscopy （PALS）. PALS has been used to study subnanometer-sized holes, to determine their size distribution and ...A review is presented of studies of polymeric membranes by applying positron annihilation lifetime spectroscopy （PALS）. PALS has been used to study subnanometer-sized holes, to determine their size distribution and free-volume fractions, and to probe molecular-sized vacancies in glassy polymers. At present, PALS is believed to be a highly effective physical method for the examination of polymeric membranes.展开更多
SrTi1-xFexO3-δ ceramics were prepared using a traditional solid-state reaction method. From X-ray diffraction(XRD) result, we found that the doped Fe^3+ dissolved in the lattice, and no secondary phase was observed. ...SrTi1-xFexO3-δ ceramics were prepared using a traditional solid-state reaction method. From X-ray diffraction(XRD) result, we found that the doped Fe^3+ dissolved in the lattice, and no secondary phase was observed. Cation vacancies in perovskite oxides were identified via positron annihilation lifetime spectroscopy(PALS) measurements. Undoped and Fe-doped SrTiO3 ceramics and single-crystal SrTiO3 were measured by PALS at room temperature. The results show that the main defects in undoped SrTiO3 ceramics are Ti-related defects, and the isolated Ti vacancy lifetime is about 183.4 ps. With the increase of Fe^3+, the concentration of the Ti vacancies decreases accompanied by the appearance of the V^nSr-nV^**O(defect association of Sr vacancies and multiple O vacancies) vacancy defect complexes.展开更多
基金The project supported by the Hundred-Persons Plan Foundation of Chinese Academy of Sciences in 2003
文摘A review is presented of studies of polymeric membranes by applying positron annihilation lifetime spectroscopy （PALS）. PALS has been used to study subnanometer-sized holes, to determine their size distribution and free-volume fractions, and to probe molecular-sized vacancies in glassy polymers. At present, PALS is believed to be a highly effective physical method for the examination of polymeric membranes.
基金Supported by the National Natural Science Foundation of China(11575129,11275142)
文摘SrTi1-xFexO3-δ ceramics were prepared using a traditional solid-state reaction method. From X-ray diffraction(XRD) result, we found that the doped Fe^3+ dissolved in the lattice, and no secondary phase was observed. Cation vacancies in perovskite oxides were identified via positron annihilation lifetime spectroscopy(PALS) measurements. Undoped and Fe-doped SrTiO3 ceramics and single-crystal SrTiO3 were measured by PALS at room temperature. The results show that the main defects in undoped SrTiO3 ceramics are Ti-related defects, and the isolated Ti vacancy lifetime is about 183.4 ps. With the increase of Fe^3+, the concentration of the Ti vacancies decreases accompanied by the appearance of the V^nSr-nV^**O(defect association of Sr vacancies and multiple O vacancies) vacancy defect complexes.
