Pure perovskite BiFeO3–BaTiO3 ceramics prepared by reaction flash sintering of Bi2O3–Fe2O3–BaTiO3 mixed powders

Abstract

In this work, the 0.67BiFeO3-0.33BaTiO3 ferroelectric ceramic was prepared by Reaction Flash Sintering (RFS). This preparation technique combines synthesis and sintering in a single Flash experiment. The starting oxides reacted during the flash to produce a stoichiometric well-sintered solid solution at a temperature of 858 °C by applying a modest field of 35 V cm−1. The process takes place in a matter of seconds, which allows obtaining a pure perovskite structure without secondary phases. X-ray diffraction (XRD) results show the mixture of rhombohedral and pseudocubic phases expected for a composition that lies within a morphotropic phase boundary (MPB) region, since a significant splitting is observed in the reflections at 2θ values of 39° and 56.5°. The microstructure exhibit a peculiar bimodal grain size distribution that determines the electrical properties. As compared with previous results, flash-prepared 0.67BiFeO3-0.33BaTiO3 evidences smaller grain size, as well as slightly lower remanent polarization (Pr) and smaller coercive field (Ec) under similar electric fields. It is also demonstrated that the preparation by RFS provides benefits regarding electrical energy consumption.