Phase Diagram and Enhanced Piezoelectric Response of Lead‐Free BaTiO ₃ – CaTiO ₃ – BaHfO ₃ System

Abstract

Three composition groups in the BaTiO 3 – CaTiO 3 – BaHfO 3 ternary system, (1 − x ) Ba ( Hf y Ti 1− y ) O 3 – x ( Ba 1− z Ca z ) TiO 3 (abbreviated as BH y T – x BC z T with x = 0–1.0, y = 0.16, z = 0.20; x = 0–1.0, y = 0.16, z = 0.30; x = 0–1.0, y = 0.20, z = 0.30, respectively), have been designed for investigating the variation of the intermediate O‐phase region and its effect on the electrical properties. The temperature‐composition phase diagram of each group has been proposed based on the X‐ray diffraction patterns and the temperature‐dependent dielectric behaviors. The enhanced piezoelectric properties are achieved in the O–T phase boundary compositions of the three groups, which are BH 0.16 T –0.58 BC 0.20 T , BH 0.16 T –0.48 BC 0.30 T and BH 0.20 T –0.53 BC 0.30 T , respectively. Piezoelectric coefficient d 33 of 448 pC/N is obtained in BH 0.20 T –0.53 BC 0.30 T , which is higher than those of the other two phase boundary compositions. The O‐phase zone in BH 0.20 T – x BC 0.30 T is narrower than those in the BH 0.16 T – x BC 0.20 T and BH 0.16 T – x