Piezoelectric response of BiFeO3 ceramics at elevated temperatures
The high Curie temperature (T-C similar to 825 degrees C) of BiFeO3 has made this material potentially attractive for the development of high-T-C piezoelectric ceramics. Despite significant advances in the search of new BiFeO3-based compositions, the piezoelectric behavior of the parent BiFeO3 at elevated temperatures remains unexplored. We present here a systematic analysis of the converse, longitudinal piezoelectric response of BiFeO3 measured in situ as a function of temperature (25-260 degrees C), driving-field frequency, and amplitude. Earlier studies performed at room temperature revealed that the frequency and field dependence of the longitudinal response of BiFeO3 is dominated by linear and nonlinear piezoelectric Maxwell- Wagner mechanisms, originating from the presence of local conductive paths along domain walls and grain boundaries within the polycrystalline matrix. This study shows that the same mechanisms are responsible for the distinct temperature dependence of the piezoelectric coefficient and phase angle and thus identifies the local electrical conductivity as the key for controlling the temperature dependent piezoelectric response of BiFeO3 and possibly other, more complex BiFeO3-based compositions. Published by AIP Publishing.