Studies of structural and electrical characteristics of multi-substituted Bi_0.5Na_0.5TiO₃ ferroelectric ceramics

In this communication, preliminary structural and detailed electrical characteristics of the CaSnO₃/CaSeO₃-modified Bi_0.5Na_0.5TiO₃ ceramics of a general chemical composition (1–2x) [Bi_0.5Na_0.5TiO₃] + x (CaSnO₃) + x (CaSeO₃) with x = 0, 0.05, 0.10, 0.15, has been prepared by high-temperature solid-state reaction method with calcination and sintering temperature 925 °C and 950 °C, respectively, for 5 h. Structural and electrical characteristics of the parent compound have significantly been tailored by the addition of the equal percentage of CaSnO₃, CaSeO₃ over a wide range of temperature (25–400 °C) as well as frequency (1 kHz–1 MHz). Room-temperature X-ray diffraction (XRD) analysis confirms the development of single-phase compound (with rhombohedral symmetry) with very small amount of impurity phase in higher concentrations (x). In the dielectric spectroscopy, two dielectric peaks are observed at around the temperatures 210 °C and 320 °C indicating multiple phase transitions of different types including the ferroelectric to paraelectric through anti-ferroelectric. Impedance analysis of data exhibits both negative/and positive temperature coefficient of resistance of the materials. The Nyquist plots determine the grain and grain boundary effect in capacitive and resistive properties of the materials, and also the non-Debye type of relaxation. The room-temperature hysteresis loop confirms the existence of ferroelectricity in the compounds where as the leakage current characteristics determine the Ohmic behavior of the materials.