Competitive mechanism of temperature-dependent electrical properties in BiFeO3-BaTiO3 ferroelectrics controlled by domain evolution

Abstract

To understand the structure nature and physical mechanisms of property evolution under electric and temperature fields, temperature-dependent electrical properties of bismuth ferrite-barium titanate (BiFeO3-BaTiO3, BF-BT) ceramics were analyzed from both static structure and domain dynamics. Intriguingly, temperature coefficient of remanent polarization (Pr) and negative strain (Sneg) changes from positive to negative as BT component increases, leading to a nearly zero temperature coefficient of Pr at critical component (BT=0.35). Combined with multi-scale structure characterization techniques and polarization switching/backswitching described by the temperature-dependent Ps and Ps-Pr, such behavior is explained by the evolution of domain size for the first time and a competitive mechanism is also proposed. That is, the evolution of macro stripe domain (0.25≤BT≤0.30) to nanodomain (0.35≤BT≤0.45) determines the transition from the dominated polarization switching process to the dominated backswitching process, further greatly determining the temperature-stability of strain properties: variation of unipolar strain changes from 136% (BT=0.25) to 25% (BT=0.45) with increasing BT content. We believe that these results significantly guide the performance improvement (especially temperature-dependent properties) of BF-BT solid solutions.