Sintering condition-dependent electromechanical behavior of the lead-free piezoelectric Bi1/2K1/2TiO3
Gina E. Eyoum, Udo Eckstein, Kevin Riess, Ahmed Gadelmawla, Eva Springer, Kyle G. Webber, Neamul H. Khansur
Abstract
Abstract Sintering conditions govern the optimized functional properties of ceramics. However, solid-state processing of Bi 1/2 K 1/2 TiO 3 (BKT), an important end member for lead-free piezoelectric solid solutions suitable for higher temperature (≤ 300 °C) transducer applications, is challenging due to the low melting temperature (≈1070 °C). In this work, the sintering temperature (1030 °C, 1050 °C, and 1060 °C) and dwell time (10 h, 20 h, and 40 h)-dependent functional properties of solid-state processed BKT were investigated, where the sintering condition-dependent dielectric and electromechanical properties were correlated with the variations in crystal structure and microstructure. Although X-ray diffraction data revealed a single-phase tetragonal structure of BKT at room temperature for all sintering conditions, significant changes in both the tetragonal distortion and spontaneous relaxor-ferroelectric transition were observed, which were directly related to the optimized functional properties. In addition, Rayleigh behavior of the piezoelectric coefficient was characterized between −150 °C and 400 °C, demonstrating that the electromechanical response is dominated by the intrinsic contribution, which can be explained by large tetragonal distortion and associated suppression of non-180° domain wall motion.