Structural, dielectric and ferroelectric properties of lead-free Na0.5Bi0.5TiO3 ceramics prepared by spark plasma sintering technique

Lead-free Na0.5Bi0.5TiO3 (NBT) fine-grained ceramics were prepared by spark plasma sintering method. Single phase ceramics with an ABO3 perovskite structure were confirmed by X-ray diffraction method. The grain morphology was analyzed by using a scanning electron micrograph. The crystal particles arranged compactly and the typical grain size was about ≈200 nm. The depolarization temperature Td, the rhombohedral–tetragonal phase transition temperature TR−T and the temperature Tm of the maximum dielectric constant corresponding to tetragonal–cubic phase transition were determined to be 453 K, approximately 623 and 793 K, respectively, from the temperature dependence of dielectric properties. The P-E hysteresis loop at different temperatures indicated the existence of antiferroelectric state at the depolarization temperature Td, which explained the antiferroelectric phase above Td. The values of Ps, Pr and Ec reduced slightly with increasing temperature in the range 303–453 K.