Dielectric properties of Mn-doped (Na_(0.8)K_(0.2))_(0.5)Bi_(0.5)TiO_3 ceramics

摘要

In this paper, the lead-free ceramics with single perovskite phase of (Na_(0.8)K_(0.2))_(0.5)Bi_(0.5)TiO_3 + x wt. percent Mn (abbreviated as BNKT-x percent Mn, x = 0 approx 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.