Electrical and dielectric properties study of CaZrO3-CaTiO3 composite system by impedance spectroscopy.

CaZrO₃ mono-phase and (1-x)CaZrO₃-xCaTiO₃ composite systems, where x = 0.2, 0.25, and 0.3, were synthesized by a conventional solid-state method. XRD patterns of the synthesized composites reveal the formation of both phases, and no secondary phase was detected. The analysis of the internal stress in the composites systems by the William-Hall equation indicates that tensile stress is applied to the CaZrO₃ grains, while compressive stress is applied to CaTiO₃ grains. TEM analyses show that the CaTiO₃ grain is surrounded by CaZrO₃ grains, confirming the presence of the CaZrO₃/CaTiO₃ hetero-interfaces and confirming the results obtained by the William-Hall equation. Impedance spectra were well modelled by introducing electrical equivalent circuits. The obtained results show that the incorporation of the CaTiO₃ phase favors the ionic conductivity in the composite and that the 0.75CaZrO₃-0.25CaTiO₃ composite exhibits the highest oxide ion conductivity among all the samples, where its total conductivity value is about 1.23 × 10⁻⁴ s cm⁻¹ at 500 °C, which is higher than that of the CZO mono-phase (1.01 × 10⁻⁶ s cm⁻¹ at 500 °C), and than that of the CTO mono-phase (2.1 × 10⁻⁷s cm⁻¹ at 500 °C). The conductivity enhancement was explained based on the variation of the hetero-interface CaZrO₃/CaTiO₃ surface area. Furthermore, the frequency and temperature dependence of dielectric constant ( ε r ′ ) and dielectric loss tangent (tanδ) were investigated in detail and the dielectric response improvement was attributed to the improvement of the space charge polarization in the hetero-interfaces. [ABSTRACT FROM AUTHOR]