Investigation of structural and electrical properties of Bi0.5(Na1-xKx)0.5TiO3-yBiFeO3 ceramic system

To develop lead free piezoelectric materials Bi0. 5 (Na1-xKx) 0. 5TiO3-yBiFeO3 (abbreviated as BNKTx-BFy، x=0. 18، 0. 20 and 0. 22، y=0. 03 and 0. 07) ceramics were prepared by solid state synthetic method. The formation of a solid solution of BNKT with BF has proven to omit the impurity of bismuth ferrite and resulted in a pure perovskite phase. The room temperature ferroelectric and piezoelectric properties of these ceramics were studied. The morphotropic phase boundary (MPB) of Bi0. 5 (Na1-xKx) 0. 5TiO3 ceramics between rhombohedral and tetragonal exactly locates at x=0. 20. Polarization versus electric field (P-E) hysteresis and relative dielectric constant ɛr studies show maximum remanent polarization Pr= 33µC/cm2and ɛr =5435، respectively. The depolarization temperature Td، the maximum temperature Tm and piezoelectric coefficient d33 were obtained at x=0. 20 and y=0. 03، 80 oC، 275 oC and 120 pC/N، respectively.