Effect of poling temperature on piezoelectricity of CaZrO3-modified (K, Na)NbO3-based lead-free ceramics

• Published in: Journal of applied physics Vol. 116; no. 11
• Main Authors: Yao, Fang-Zhou, Wang, Ke, Jo, Wook, Lee, Jae-Shin, Li, Jing-Feng
• Format: Journal Article
• Language: English
• Published: Melville American Institute of Physics 21.09.2014
• Subjects: Applied physics; Calcium zirconate; Deoxidizing; Electrical properties; Ferroelectric materials; Ferroelectricity; Hysteresis loops; Lead free; Niobates; Niobium; Phase transitions; Piezoelectric ceramics; Piezoelectricity; Polarization; Polycrystals; Space charge; Tantalum
• ISSN: 0021-8979; 1089-7550
• DOI: 10.1063/1.4895774

Electrical poling is indispensable for endowing isotropic ferroelectric polycrystals with a net macroscopic polarization and hence piezoelectricity. However, little attention has been paid to the optimization of poling conditions in (K, Na)NbO3-based ceramics with a polymorphic phase transition. This study investigated the electrical properties of CaZrO3-modified (K, Na, Li)(Nb, Ta)O3 lead-free piezoceramics as a function of the poling temperature. Peak piezoelectric coefficient d33 of 352 ± 7 pC/N and planar electromechanical coupling factor kp of 0.47 were obtained at the optimized poling temperature of 120 °C, which crosses the polymorphic phase transition regime. In-depth analysis of the asymmetric polarization hysteresis loops and bipolar strain curves uncovered striking analogy between electrical poling and unipolar cycling in the current system, which is attributed to a competition between domain reorientation and space charge accumulation.