Influence of the sintering process on ferroelectric properties of Bi0.5(Na0.8K0.2)0.5TiO3 lead-free piezoelectric ceramics

Abstract

The effect of sintering process, particularly the sintering time, on ferroelectric properties of Bi0.5(Na0.8K0.2)0.5TiO3 (BNKT) has been studied and compared with Bi0.5Na0.5TiO3 (BNT) and Bi0.5K0.5TiO3 (BKT) ceramics. Ceramic powders were prepared by the solid-state reaction method, employing a mechanochemical activation step, and sintered at different times. Samples were characterized by X-ray diffraction (XRD), Raman microspectroscopy, Scanning Electron Microscopy (SEM), impedance spectroscopy and ferroelectric hysteresis loops. Through XRD and Raman results, the perovskite structure was detected. In addition, a secondary phase was observed by SEM images. As the sintering time was increased, the medium grain size grew, and the amount of the secondary phase raised. Moreover, dielectric properties were modified by the resulting grain size and the amount of the secondary phase.