Large strain response and fatigue-resistant behavior of lead-free (1-x)(Bi_0.5Na_0.5)TiO₃-xSrTiO₃ ceramics at a relatively low driving field

Lead-free (1-x)(Bi_0.5Na_0.5)TiO₃-xSrTiO₃ (abbreviated as BNT-100xST, x = 0.19-0.27) piezoceramics were synthesized via the traditional solid-state process. The micromorphology, phase structure, strain response and fatigue behavior were studied in detail. For all the composition range, the ceramics are pure perovskite structures. And the tetragonal phase gradually changes into pseudocubic phase. The ferroelectric order was destroyed with the increase of ST concentration. Strains up to 0.289% for BNT-23ST can be achieved at the driving fields (45 kV cm^-1) with a high corresponding normalized strain d ₃₃ ^∗ (S _max/E _max) of 642 pm V^-1. Furthermore, the BNT-23ST ceramics exhibit an excellent fatigue resistance, and the unipolar strain value decreased by only 8.24% after 10⁷ cycles.