Electric-field-temperature phase diagram of Mn-doped Bi0.5(Na0.9K0.1)0.5TiO3 ceramics

An electric field-temperature (E-T) phase diagram for a lead-free 0.5 mol.% Mn-doped Bi(Na0.1K0.9)TiO3 ceramics was investigated. The x-ray diffraction, dielectric and polarization measurements revealed relaxor behavior and were used to characterize the stability regions of the non-ergodic relaxor, ergodic relaxor and electric field induced ferroelectric states. As indicated by the polarization-current density profiles, transformation between two electric fields, induced ferroelectric states with opposite polarization direction arise via a two-step process through an intermediate relaxor state. Interplay between the ferroelectric state conversion and intermediate relaxor state is governed by the dynamics of polarization relaxation. The presented E-T phase diagram revealed the effects of the applied electric field and temperature on stability regions. This is of special interest since the Bi-0.5(Na0.1K0.9)(0.5)TiO3 ceramics were proposed as a potential piezoceramic material. (C) 2015 AIP Publishing LLC.