Comparative analysis of immittance spectroscopy of some layered structured compounds

A comparative analysis of structural and immittance characteristics of bismuth and antimony based fourfold layered perovskites BaBi4-xSbxTi4O15 (x = 1-4), synthesized by high temperature mixed oxide method are reported in this paper. The room temperature XRD data shows single phase orthorhombic crystal system for all the compounds with some variation in lattice parameters. Mostly uniformly and homogeneously distributed grains with a smaller number of voids are observed over pallet surface in SEM micrographs which exposes the good quality of the samples. Immittance spectroscopy indicates the influence of bulk and bulk boundary in the resistive and capacitive properties of the materials. The bulk resistance is found to be very small for when Bi is completely substituted by S band behaves as a good conductor. Negative temperature coefficient of resistance characteristics is observed from the impedance analysis, which confirm the semiconductor characteristics of the materials within the experimental range of temperature. Non-Debye type of relaxation mechanism is seen from the Nyquist plots. From the modulus spectroscopy, the higher capacitive properties are observed at lower temperature. The charge carriers in the samples have long-range as well as short-range ordering which are confirmed from complex impedance and modulus study of the studied samples.