Ionic doping effects on crystal structure and relaxation character in Bi_0.5Na_0.5TiO₃ ferroelectric ceramics

The effects of ionic doping in Bi_0.5Na_0.5TiO₃ (BNT) ceramics were investigated. Pure and doped BNT samples containing 0 to 16 at.% Ba²⁺ and 0 to 1.0 at.% Ce⁴⁺ were synthesized at 1135 to 1200 °C for 2 h in ambient atmosphere. Temperature dependences of dielectric properties were analyzed. These results suggest that Ba²⁺ and Ce⁴⁺ replace the ions in A and B sites of perovskite structures, and the lattice structure is altered. The component differences of each crystal domain lead to variance of phase transition temperature, which enhances the relaxation character in BNT ceramics, and the dielectric properties were consequently improved.