Compositional effects on the properties of (1-x)BaTiO3-xBi0.5Na0.5TiO3 ceramics

The compositional effects on the crystal structure, phase transition, dielectric, ferroelectric and piezoelectric properties of the (1-x)BaTiO3-x(Bi0.5Na0.5)TiO3 solid solution ceramics were investigated. After sintering at 1200 degrees C for 2 h, the ceramics with different content of (Bi0.5Na0.5)TiO3 (BNT) formed single-phase solid solutions with perovskite structure. The lattice constant c/a ratio of the solid solutions decreased as BNT content increased except that with 20 mol% BNT, which had the largest value of c/a ratio for all samples. The second phase transition corresponding to BaTiO3 (BT) at about 5 degrees C shifted to low temperature and gradually disappeared as BNT increased. A new secondary phase transition appeared at 32 degrees C and 64 degrees C, respectively, when BNT content was 5 and 14 mol%. The Curie temperature, T (c), shifted in the temperature range between 112 degrees C and 166 degrees C, and the remanent polarization, P (r), decreased whereas the coercive field, E (c), increased as the BNT content increased. The relatively high value of piezoelectric coefficient d(33) together with a relatively high Curie temperature and low loss tangent and stable dielectric properties were obtained when the addition of BNT was 20 mol%.