Post-sinter annealing of Pb0.7La0.2TiO3 derived from mechanical activation

Abstract

To investigate the relationships between the dielectric behaviors and defect structures in Pb0.7La0.2TiO3, such as A-site vacancies and oxygen vacancies, post-sinter annealing in oxygen and nitrogen were conducted. Upon initial annealing in oxygen, space charge polarization, manifesting with A-site vacancies created by PbO evaporation from the surface region, dominates the dielectric properties of Pb 0.7La0.2TiO3. Prolonged annealing in oxygen, for example, for more than 4 hours, led to a steady fall in both dielectric constant and dielectric loss. Annealing in nitrogen resulted in a similar rise in the dielectric properties at the initial stage, followed by a slow down in the increase rate at extended duration of annealing, when the perovskite structure is destabilized in combination with the interactions between oxygen vacancies and A-sitc vacancies.