Restraining quenching-induced decline of resistivity in NBT-BFO ceramics by incorporation of BiAlO3

Abstract

(1-x)Na0.5Bi0.5TiO3-xBiFeO3 (NBT-BFO) is a system with a composition-induced transition from relaxor to ferroelectric. Upon quenching, 0.4NBT-0.6BFO obtain a Td of 640 °C and d33 of 56 pC/N. However, the quenching treatment also causes the reduction of resistivity, which is unfavorable for high-temperature piezoelectric ceramics. The aim of this study is to restrain quenching-induced decline of resistance in NBT-BFO ceramics by doping a small amount of BiAlO3 (BA). For unquenched NBT-BFO-BA, with increasing BA content, the piezoelectric coefficient (d33) decreases slightly, while the resistivity increases. After quenching, both d33 and the depolarization temperature (Td) increase, but more importantly, the resistivity of quenched NBT-BFO-BA is comparable with that of the unquenched samples. This phenomenon is not observed in other quenched samples, and the reason is attributed to the defect dipoles caused by BA. Besides, the enhanced piezoelectric properties and the resistivity can be retained after annealing the quenched samples at 400 °C for 4 h. Thus, this work implies the potential application of NBT-BFO based piezoelectric ceramics at elevated temperatures.