Structure and electrical properties of (Bi,Na)0.94Ba0.06Ti1-x(Mg1/3Nb2/3)xO3 ceramics

Abstract

In this work the effect of pseudo-cation (Mg2+1/3Nb5+2/3)4+ addition on Ti-site of (Bi0.5Na0.5)0.94Ba0.06TiO3 ceramics, having general formula (Bi,Na)0.94Ba0.06Ti1-x(Mg1/3Nb2/3)xO3 (0 ≤ x ≤ 1), on their structural and electrical properties was investigated. These compounds were prepared using a standard high temperature solid-state reaction technique and characterized by structural, microstructural, impedance, and conductivity studies. The sintered ceramics are almost phase-pure perovskite materials showing high bulk densities (>95% TD), uniform microstructure and satisfactory impedance properties in all the samples. Besides, an attempt has been made to ascertain the role of grains and grain boundaries on the electrical properties of these solid solutions and their dependence on the temperature and frequency, using complex impedance spectroscopy technique. The obtained data analysed in the framework of AC conductivity, complex impedance as well as electric modulus formalisms indicate on dominant negative temperature coefficient of resistance (NTCR) character of the materials due to the contribution of semiconducting grains. Further, the dielectric relaxation in the material was seen to be of non-Debye type.

Keywords

• perovskites
• lead-free
• ceramics
• dielectric
• impedance
• microstructure