Defect studies in BaTiO3 ceramics using positron annihilation spectroscopy

Temperature-dependent measurements using positron lifetime spectroscopy (POLIS) were carried out to study intrinsic defects in polycrystalline BaTiO3 (BT) samples. Annealing under different oxygen partial pressure of < 10(-15) to 10(5) Pa were carried out. It was found that with decreasing oxygen pressure the average lifetime increases. This is attributed to the formation of complexes containing oxygen vacancies V-O and other vacancies, probably V-Ba. The influence of the grain boundaries on the trapping probability in ceramic BT material was studied. It was found that the average positron lifetime increases distinctly with decreasing grain size.