Electric-field-temperature phase diagram of Mn-doped Bi-0.5(Na0.9K0.1)(0.5)TiO3 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 ferro- electric states with opposite polarization direction arise via a two-step process through an interme- diate 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 spe- cial interest since the Bi0.5(Na0.1K0.9)0.5TiO3 ceramics were proposed as a potential piezoceramic material.