Structural, electrical and dielectric properties of double perovskites: BiHoZnZrO6 and BiHoCuTiO6

Two lead-free double perovskites; BiHoZnZrO6 and BiHoCuTiO6 were synthesized by a cost effective solid-state reaction technique. When the pair of elements (Zn and Zr) are replaced by another pair (Cu and Ti), the monoclinic crystal structure of BiHoZnZrO6 changes to orthorhombic system (for BiHoCuTiO6). The homogeneous distribution of the grains and formation of desired compounds in both the double pervoskites have been ascertained with the analysis of microscopic images and energy dispersive spectra. Detailed studies of the complex impedance spectra revealed that the diectric and electrical properties of both the pervoskites have strongly been influenced by the variation of frequency as well as temperature. The grains, grain boundaries and electrode were found to have profound effect on the electrical and dielectric properties of both the materials, which have provided the basis to understand the electrical conduction mechanism and micro-structure behavior of the materials.The electrical parameters, such as, bulk and grain boundary resistance and capacitance of the materials were obtained by designing an equivalent circuits, and subsequent modelling of the impedance behaviour. The ac conductivity, electrical modulus and the transport properties of both the pervoskites were compared in details in the present communication.