Morphotropic phase boundary in (1–x)Bi_0.5Na_0.5TiO₃–x (Bi_0.8La_0.2)FeO₃ with improved depolarization temperature

Abstract The structure–property relationship of (1–x)Bi_0.5Na_0.5TiO₃–x (Bi_0.8La_0.2)FeO₃ (BNT–BLF) lead‐free piezoceramics was investigated. A morphotropic phase boundary (MPB) exists near x = 0.0125 with highest piezoelectric constant d₃₃ and electromechanical coupling factor k_p of 128 pC/N and 0.30, respectively. Especially, it was found that the introduction of BLF can improve the depolarization temperature (T_d) of BNT‐based piezoceramics. At 100 Hz, the measured T_d of the composition with x = 0.0125 was 163 °C, i.e., higher than for other BNT‐based ceramics. These results may provide some guidelines to develop BNT‐based piezoceramics with high T_d. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)