Ferroelectric, electrical, and structural properties of Dy and Sc co-doped BaTiO3

Ba1 xDyxTi1 xScxO3 ceramics, 0 <= x <= 0.075, were prepared and the influence of Dy and Sc co-doping on the ferroelectric, electrical and structural properties of BaTiO3 (BT) investigated. A solid solution limit of x approximate to 0.05 was established using X-ray diffraction, and all compositions x <= 0.05 were tetragonal at room temperature. Fixed-frequency capacitance measurements showed the temperature of the cubic to tetragonal phase transition, T-C, decreased non-linearly with increasing x and the associated permittivity peak broadened, with frequency-dependent 'relaxor'-type behaviour observed for cubic x = 0.075. In addition, the magnitude of the relative permittivity at T-C showed a negative dependence on x, decreasing from similar to 11 700 for x = 0 to similar to 6950 for x = 0.05. In contrast to the non-linear decrease in T-C, the tetragonal to orthorhombic and orthorhombic to rhombohedral phase transition temperatures decreased linearly at rates of similar to 40 and similar to 28 degrees C mol%(-1) of DyScO3, respectively. The effect on the ferroelectric properties of BT was to quadruple the coercive field, from similar to 0.9 kV cm(-1) for x = 0 to similar to 4.4 kV cm(-1) for x = 0.025, without affecting the remnant polarisation, similar to 10 to 11 mu C cm(-2) for x = 0 to 0.025. Finally, the non-linear decrease in T-C is discussed in terms of the contributions of the mean size and statistical variance of the cations on the A and B sites of the perovskite, ABO(3), lattice and the replacement of Ti4+ with Sc3+ cations.