Diffuse phase transition, piezoelectric and optical study ceramic

摘要

Bismuth sodium titanate, Bi_(0.5)Na_(0.5)TiO_3 (BNT) is considered to be an excellent candidate for a key material of lead-free dielectric ceramics. In this study, we propose the dielectric and optical study of single phase BNT powder prepared by solid-state reaction route. The phase formation and structural study were done by X-ray diffraction (XRD) which shows well developed crystallite with a pure perovskite phase. The ceramic was sintered at different temperatures from 1050°C to 1175°C to study the effect of sintering temperature on the morphology and density. It was found that the sample sintered at 1150°C shows the highest density. The microstructure of the ceramic was investigated by scanning electron microscopic (SEM) technique. The temperature-dependent dielectric study of the sample sintered at 1150°C was done in the frequency range of 50 kHz-1 MHz which shows a diffuse phase transition. The piezoelectric constant (d_(33)) was found to be 41 pCN~(-1). The P-E hysteresis loop confirms the ferroelectric behaviour in the ceramic. The UV-Vis spectrum indicated that the Bi_(0.5)Na_(0.5)TiO_3 ceramic has an optical band gap of 2-94 eV.