Study of diffuse PhaseTransition behavior in Bi and Li Co-substituted barium titanate ceramics

The effect of Bi and Li co-substitution in BaTiO₃ ceramics on its structural, dielectric and ferroelectric properties has been investigated. Bi and Li co-substituted BaTiO₃ with general formula Ba_(1-x)(Bi,Li)_xTiO₃ (x = 0, 0.02, 0.04 and 0.08) is synthesized by solid state reaction method using microwave heating. The XRD patterns revealed that the single phase tetragonal structure with space group P4mm is formed. The Raman study also shows that the prepared samples have tetragonal symmetry. The frequency and temperature dependent dielectric study on the above set of ceramics were carried out at four different frequencies (1 kHz, 10 kHz, 100 kHz and 1 MHz) and in the temperature range of 30–250 °C. The results reveal that the samples are exhibiting diffused phase transition, and there is a clear deviation from normal Curie–Weiss law. The diffused phase transition property in Bi and Li co-substituted BaTiO₃ ceramics make it more attractive for technological applications. The diffuseness is analyzed using a phenomenological theory of diffuse ferroelectric phase transitions. The room temperature P-E hysteresis loops of all these ceramic samples are investigated. The results show that remnant and spontaneous polarization has decreased with an increase of Bi and Li concentrations. This could be the result of an increased in domain pinning.