Influence of A-site Sm Doping on Structural and Electrical Property of 0.93Na0.5Bi0.5TiO3-0.07BaTiO3 Lead Free Ceramics

Sm doped [(Na0.5Bi0.5)(0.93)Ba-0.07](1-x)SmxTiO3 (BNBST) lead-free dielectric energy storage ceramics were prepared by solid-phase reaction sintering method. Effects of the Sm doping content on phase structure, microstructure, ferroelectric, dielectric, energy storage properties and d.c., and a.c. conductance of BNBST ceramics were systematically investigated. Results indicate that the as-fabricated BNBST ceramics exhibit single-phase perovskite structure, and Sm dopants get into the A-site lattice of (Na0.5Bi0.5)(0.93)Ba0.07TiO3 matrix. Dense and uniform grains are obtained by grain growth inhibition of Sm dopants with average grain size within 2 mu m. The remanent polarization and coercivity of BNBST ceramics sharply decrease after introducing Sm dopants, and the double hysteresis loops are observed with a little decrease of saturation polarization. The energy storage density and efficiency increase firstly and then decrease with increasing Sm doping content, the energy storage density reaches a maximum value of 0.70 J/cm(3) at x=0.02 and 70 kV/cm electric field, with corresponding efficiency of 40%. The BNBST ceramics show an obvious relaxation ferroelectric characteristic and its dielectric constant peaks of T-m decrease and planarize with increasing Sm doping content. The electric insulativity of BNBST ceramics has strong temperature dependence, and the excellent electric insulativity can be kept when ambient temperature is below 300 degrees C.