High-Temperature Depolarization of Alkali Niobate Lead-Free Piezoceramics
Na0.5K0.5NbO3 (NKN) lead-free piezoelectric ceramics was synthesized by a mixed oxide reaction method. The ceramics was poled under an electric field of 3 kV/mm at 150 °C for 0.5 h. The thermally stimulated depolarization current (TSDC) measurement was carried out at the heating rate of 1 °C/min from room temperature up to 500 °C under an applied voltage of 0 and 0.5 V. The zero-bias TSDC pattern showed broad patterns around at 365 and 375 °C. These temperatures corresponded to the temperatures showing bending points in the Arrhenius plot of TSDC measured under 0.5 V. The oxygen vacancy related electrical conduction was changed at 313 °C at the heating step. The mobile oxygen vacancy in NKN ceramics was piled up under the poling field, and the oxygen vacancy was diffused at temperature higher than 313 °C.
Chazono Hirokazu, Fujihara Shinobu, Katayama Keiichi, Masumoto Hiroshi, Mizoguchi Teruyasu, Osada Minoru, Shinozaki Kazuo and Takeda Hiroaki
H. Matsudo et al., "High-Temperature Depolarization of Alkali Niobate Lead-Free Piezoceramics", Key Engineering Materials, Vol. 485, pp. 53-56, 2011