Phase formation and dielectric phase transition in Ba1−xCaxTi0.6Zr0.4O3 solid solutions

Perovskite types Ba_1−xCa_xTi_0.6Zr_0.4O₃ (with x=0.0-0.5) ceramics have been prepared through solid state reaction route. The room temperature XRD study suggests the compositions with x=0.0 and x=0.1 have single phase cubic symmetry. With further increase in Ca content, solid solution breaks and an orthorhombic CaTiO₃ like phase is developed. The dielectric study on single phase compositions (x=0.0 and 0.1) reveals that the materials are of relaxor type and undergo a diffuse type ferroelectric phase transition. In the Ca containing composition higher transition temperature is observed than the pure BaTi_0.6Zr_0.4O₃ materials. In the paraelectric region (above T_c) lower diffusivity is observed in the Ca containing composition. The strength of relaxation is calculated and found to be more in Ca containing material than that of pure BaTi_0.6Zr_0.4O₃ composition.