Enhanced electrical properties in lead-free NBT-BT ceramics by series ST substitution

Comprehensive electrical properties of 0.94(Na1/2Bi1/2)TiO3-0.06BaTiO3 lead-free ceramics by doping series SrTiO3 were investigated. High piezoelectric constant of 205 pC/N and electromechanical coupling factor of 0.34 were obtained due to the forming of the rhombohedral-tetragonal morphotropic phase boundary at x=0.02-0.06. Very large recoverable strain of 0.34% was obtained at x=0.10 due to the coexistence of ferroelectric and relaxor pseudocubic phases. A large electrocaloric effect (ΔTmax=1.71 K and ΔT/ΔE=0.34 K mm kV−1 at 50 kV cm−1) which determined by indirect measurements method was obtained at 120 °C at x=0.02, which is significantly higher than that of lead-free ferroelectric ceramics reported so far. Moreover, lower operating temperatures of 50 °C and 30 °C were proposed when x=0.10 and 0.20 with ΔTmax=0.79 K and 0.6 K, respectively. These properties added together indicate a promising material for applications in cooling systems and actuators.