Thermally-stable large strain in Bi(Mn0.5Ti0.5)O3 modified 0.8Bi0.5Na0.5TiO3-0.2Bi0.5K0.5TiO3 ceramics

Abstract (1- x )[0.8Bi 0.5 Na 0.5 TiO 3 -0.2Bi 0.5 K 0.5 TiO 3 ]- x Bi(Mn 0.5 Ti 0.5 )O 3 ( x  = 0–0.06, BNKMT100 x ) lead-free ferroelectric ceramics were prepared via solid state reaction method. Bi(Mn 0.5 Ti 0.5 )O 3 induces a structure transition from rhombohedral-tetragonal morphotropic phases to pseudo-cubic phase. Moreover, the wide range of compositions within x  = 0.03–0.055 exhibit large strain of 0.31%–0.41% and electrostrictive coefficient of 0.027–0.041 m 4 /C 2 . Especially, at x  = 0.04, the large strain and electrostrictive coefficient are nearly temperature-independent in the range of 25–100 °C. The impedance analysis shows the large strain and electrostrictive coefficient originate from polar nanoregions response due to the addition of Bi(Mn 0.5 Ti 0.5 )O 3 .