Effect of SrTiO3 modification on dielectric, phase transition and piezoelectric properties of lead-free Bi0.5Na0.5TiO3‒CaTiO3‒SrTiO3 piezoelectric ceramics

This study investigated the structures, dielectric, ferroelectric and piezoeletric properties of lead-free (0.99‒x) Bi0.5Na0.5TiO3‒0.01CaTiO3‒xSrTiO3 (BNT‒CT‒100xST, x = 0.22–0.30) piezoelectric ceramics. These piezoceramics were successfully prepared using the conventional solid-state reaction method sintered at 1175 °C for 2 h. It was found that a phase transition from nonergodic relaxor to ergodic relaxor was induced by ST modification in BNT‒CT ceramics. Consequently, a large electromechanical strain of 0.20% corresponding to high normalized strain d33∗\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$d_{33}^{*}$$\end{document} of 667 pm/V was obtained even under 3 kV/mm for BNT‒CT‒28ST ceramics. Therefore, it is noted that lead-free BNT‒CT‒100xST ceramics can be promising candidates for actuator applications.