Effect of processing on the structures and properties of bismuth sodium titanate compounds

The processing of sodium (Na) and bismuth (Bi)-based piezoelectric compounds are always a concern due to their volatilization at high temperatures (> 1000 °C) and the hygroscopic nature of the precursors. The effect of drying and impurities in the precursors on 0.94(Bi0.5Na0.5TiO3)–0.06BaTiO3 (BNTBT) ceramics was investigated. A substantial difference in the weight fraction of polar (R3c) and weak-polar (P4bm) phase at room temperature was observed for BNTBT obtained from dried, undried and low purity precursors, evaluated by XRD and Raman. The local crystal structure was evaluated by transmission electron microscope, which showed the presence of both ferroelectric domains and polar nano regions. The electrical measurements corroborated well with the structure results, and showed a variation in the depolarization temperature (Td). The results highlight the importance of the pre-processing steps on the functional compounds obtained from sensitive elements, which has broader implementations for similar systems.