Understanding high piezoelectricity in the lead-free relaxor ferroelectric BFBT

Lead free relaxor ferroelectrics are being developed to replace lead-based systems which are widely used commercially in capacitors, actuators and sensors. An important aspect of these materials is their piezoelectric behaviour which can be utilised in advanced electromechanical devices. Such relaxor ferroelectrics are characterised by local polar nano regions (PNRs) which show fast switching in electric fields. Classical average structure analysis cannot explain the observed piezo/ferroelectric behaviour of these materials and a more comprehensive analysis of both long-range and short-range structure is needed. It is proposed to carry out a detailed study of the local and long range structures of the lead-free relaxor ferroelectric (1-x)BiFeO3-xBaTiO3 (BFBT) using reverse Monte Carlo analysis of neutron total scattering data. At around x = 0.33, the system shows outstanding piezoelectric performance. This study aims at studying the evolution of PNRs in this system and their role in the enhanced piezoelectric behaviour. The study would represent the first of its kind on a lead-free ferroelectric.