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 T d, the rhombohedral–tetragonal phase transition temperature T R−T and the temperature T m 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 T d, which explained the antiferroelectric phase above T d. The values of P s, P r and E c reduced slightly with increasing temperature in the range 303–453 K.Scopu