Electrical properties of barium bismuth titanate

Abstract

Family of bismuth oxides was discovered more than 50 years ago by Aurivillius [1]. Recently, there has been renewed interest in the properties of the Aurivillius phases as temperature-stable ferro-piezoelectrics [2]. Several bismuth-layered crystal structures and their properties have been investigated in detail. However, a lot of aspects of the preparation and properties of barium bismuth titanate, BaBi4Ti4O15 [BBiT] remain unexplored, whereas being promising candidate for high-temperature piezoelectric applications, memory application and ferroelectric nonvolatile memories (Fe-RAM). In present work, BBiT was prepared by solid state reaction from mixture of oxide: BaO, TiO2 and Bi2O3 which was, previously, milled for 6 h. Mixture was heated at 750 oC for 4 h and after that sintered at 1130 oC for 1 h. The values of Tc, dielectric constant (ε), the loss tangent (tanδ), degree of relaxation behavior (∆T relaxor) and degree of diffuseness of the material (γ) are summarized in Table below. The degree of relaxation behavior is found to be only 15 K, which suggests the shift of Tc with frequency is not much distinct in BBiT ceramics. A modified Curie-Weiss relationship is used to study the diffuseness behavior of a ferroelectric phase transition where value of γ indicates the degree of diffuseness of BBiT material. The dielectric relaxation rate foollow the Vogel-Fulcher relation with activation energy = 0.013eV, relaxation frequency = 2.09×108 Hz, and freezing temperature = 378 oC. All this parametars indicate that BBiT is a relaxor ferroelectric.