Correlation between phase, microstructure and electrical properties of Ba _0.7 Sr _0.3 TiO ₃ -modified Bi _0.5 Na _0.5 TiO ₃ -0.06BaTiO ₃ lead free ceramics

Environmentally friendly Pb-free piezoelectric ceramics are essential for electronic industries and devices utilizations owing to their excellent piezoelectric properties which enable powerful sensor, transducer and actuator developments. In the present work, highly dense complex perovskite oxide ceramics with the formula of (1-x)[0.94Bi0.5Na0.5TiO3-0.06BaTiO3]-x(Ba0.7Sr0.3)TiO3 or (1-x)[0.94BNT–0.06BT]-xBST, where x = 0.00, 0.01, 0.02, 0.03, 0.04 and 0.05 mol fraction were fabricated by a solid-state mixed oxide method. After sintering at 1125°C for 2 h, all ceramics were characterized with attention paid on their phases, microstructures, dielectric, ferroelectric, piezoelectric and strain properties as a function of BST content. The unit all size expansion i.e. higher degree of tetragonality was detected as BST content increased. All compositions exhibited single perovskite phase and uniform microstructures containing cubic-like grains with average grain size range of all ceramics was in the order of ~ 0.75–1.57 µm, depending on the amount of BST. It was interestingly found that the addition of BST enhanced the densification, sintering ability, grain size and electrical properties of BNT-BT ceramics, indicating their potential Pb-free piezoelectric candidates for future actual applications.