Domain evolution and improved electrical property of BiMn2/3Nb1/3O3 doped 0.8Na0.5Bi0.5TiO3-0.2K0.5Bi0.5TiO3

(1-x)[0.8Na(0.5)Bi(0.5)TiO(3)-0.2K(0.5)Bi(0.5)TiO(3)]-xBiMn(2/3)Nb(1/3)O(3) ((1-x)NKBT-xBMN with x = 0-0.04) piezoceramics were prepared, the composition-dependent domain structure and domain switching under electric field and their effects on macroscopic electrical properties have been systematically investigated. At room temperature, though the ceramics persists rhombohedral-tetragonal mixed crystal structure, their domain structure evolves from dispersive island-like with average size of 80 nm for x = 0 to labyrinthian-like with average size of 120 nm for x = 0.0075, and then tends to be unobservable by forming polar nanoregions for x = 0.04. As the results, the x = 0.0075 ceramic shows enhanced ferroelectric and piezoelectric property. When compared with the x = 0 pristine counterpart, the saturated polarization, remnant polarization, piezoelectric coefficient, and electromechanical coupling factor of x = 0.0075 ceramic increase by 3%, 12%, 40%, and 20% to 43.2 mu C/cm(2), 31.21.mu C/cm(2), 147 pC/N, and 0.28. This work suggests that fine domain engineering is a promising way to further improve electrical property.