Dielectric properties of Mn-doped (Na0.8K0.2)0.5Bi0.5TiO3 ceramics

In this paper, the lead-free ceramics with single perovskite phase of (Na0.8K0.2)(0.5)Bi0.5TiO3 + x wt-% Mn (abbreviated as BNKT-x% Mn, x=0 similar to 0.5) were prepared by solid state reaction method. The SEM indicates that Mn-doping restrains the growth of grain at a certain extent. There were two abnormal dielectric peaks of T-d and T-m appeared in curves of dielectric permittivity vs. temperature for the pure BNKT ceramics. Compared to pure BNKT ceramics, Mn-doping restrained the transition of ferroelectric phase to antiferroelectric phase that can be explained by oxygen vacancies. A linear fitting of the modified Curie-Weiss law to experimental data show that all the samples have a diffuse character. (c) 2005 Elsevier B.V. All rights reserved.