Crystal structure and properties of BaTiO3-(Bi0.5Na0.5)TiO3 ceramic system

(1 - x)BaTiO3-x(Bi0.5Na0.5)TiO3 (x ranged from 0.01 to 0.96) ceramics were fabricated by the conventional ceramic technique. The crystal structure, as well as dielectric and piezoelectric properties of the ceramics were studied. All the ceramics formed single-phase solid solutions with perovskite structure after sintering in air at 1150-1250 degrees C for 2-4 h. The crystal structure and microstructure varied gradually with the increase of (Bi0.5Na0.5)TiO3 (BNT) content. The Curie temperature, T-c, shifted monotonously to high temperature as BNT increased. The ceramics with 20-90 mol% BNT had relatively low and stable dielectric loss characteristics. The piezoelectric constant, d(33), enhanced with the increase of BNT content through a maximum value in a composition of 93 mol% BNT and then tended to decrease. The maximum value, 148 pC/N, of piezoelectric constant d(33) together with the electromechanical coupling factors, k(t), 19.8% and k(p), 15.8%, were obtained when BNT was 93 mol%.