Dielectric and piezoelectric properties of Bi1/2Na1/2TiO3–SrTiO3 lead–free ceramics

This study investigated the microstructure, crystal structure, and electrical properties of (1 − x)Bi1/2Na1/2TiO3–xSrTiO3 (BNST100x; x = 0.20, 0.22, 0.24, 0.26, 0.28, and 0.30) lead−free piezoceramics. The average grain size of BNST100x ceramics decreased with increasing SrTiO3 content. A phase transition from nonergodic relaxor (NER) to ergodic relaxor (ER) was observed at x = 0.26, and the highest unipolar strain under 4 kV/mm electric field, of 0.25% (d33* ≈ 620 pm/V), was obtained at x = 0.28. We found that the BNST26 and BNST28 compositions yielded the competitive advantage of larger strain values under lower operating fields compared with other BNT–based lead–free piezoelectric ceramics. Therefore, we regard these ceramics as promising candidates for actuator applications.