Electrical hetero-structure of Nd_0.1Sr_0.9TiO₃ ceramic for energy storage applications

Both high dielectric constant and high bulk resistance was required to meet high energy storage density in high-voltage ceramic capacitors. In this paper, Nd_0.1Sr_0.9TiO₃ (NSTO) ceramic with pure tetragonal perovskite structure was prepared by solid state reaction route. Dielectric response of NSTO ceramic was investigated in the temperature range of −60 to 550 °C over the frequency 20 Hz–1 MHz. Complex impedance spectroscopy (IS) analysis was employed to study the electrical conductive behavior of NSTO ceramic. IS results revealed that the NSTO ceramic showing electrical hetero-structure, which includes semiconducting grains, inter-grains and insulating grain boundaries. The space charge polarization at heterointerfaces by conductive charge carries was contributed to high dielectric constant, while insulating grain boundaries to high bulk resistance for NSTO ceramic. The mechanism of such electrical hetero-structure formation associated with charge compensation induced by trivalent Nd ions substitution for divalent Sr, as well as the first and second ionization of oxygen vacancies was discussed tentatively.