Determination of depolarization temperature of (Bi1/2Na1/2)TiO3-based lead-free piezoceramics

• Published in: Journal of applied physics 2011-11, Vol.110 (9)
• Main Authors: Anton, Eva-Maria, Jo, Wook, Damjanovic, Dragan, Rödel, Jürgen
• Format: Article
• Language: English
• ISSN: 0021-8979; 1089-7550
• DOI: 10.1063/1.3660253

The depolarization temperature Td of piezoelectric materials is an important figure of merit for their application at elevated temperatures. Until now, there are several methods proposed in the literature to determine the depolarization temperature of piezoelectrics, which are based on different physical origins. Their validity and inter-correlation have not been clearly manifested. This paper applies the definition of depolarization temperature as the temperature of the steepest decrease of remanent polarization and evaluates currently used methods, both in terms of this definition and practical applicability. For the investigations, the lead-free piezoceramics (1–y)(Bi1/2Na1/2TiO3–xBi1/2K1/2TiO3)−yK0.5Na0.5NbO3 in a wide compositional range were chosen. Results were then compared to those for BaTiO3 and a commercial Pb(Zr,Ti)O3-based material as references. Thermally stimulated depolarization current and in situ temperature-dependent piezoelectric coefficient d33 are recommended to determine Td according to the proposed definition. Methods based on inflection point of the real part of permittivity or the peak in dielectric loss give consistently higher temperature values.