Structural, thermal expansion and heat capacity study of lead-free [(1 − x)(Na_0.5Bi_0.5)–xBa]Zr_1−y Ti _y O₃ ceramics

Lead-free ceramics of Na_0.5Bi_0.5TiO₃–Ba(Ti,Zr)O₃ (NBT–BTZ) were prepared by solid phase hot pressing sintering process. The obtained samples show perovskite structure. Structural, the heat capacity, thermal expansion and pyroelectric measurements were made in wide temperature range. The broad anomalies of heat capacity and thermal expansion were observed, which approximately correspond to structural, pyroelectric and dielectric properties. It was concluded that these anomalies can be connected with temperature features of polar regions and with formation of long-range ferroelectric state. The obtained results are discussed in the framework of foreign ions/lattice imperfections, which create local electric and elastic fields. The NBT–BTZ system is expected to be a new promising candidate for lead-free electronic ceramics.