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

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 (P_r) and negative strain (S_neg) changes from positive to negative as BT component increases, leading to a nearly zero temperature coefficient of P_r at critical component (BT=0.35). Combined with multi-scale structure characterization techniques and polarization switching/backswitching described by the temperature-dependent P_s and P_s-P_r, 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.