Dielectric and impedance spectroscopy of Sm2CoIrO6 double perovskite

Abstract

Polycrystalline double perovskite Sm2CoIrO6 (SMCO) ceramics have been prepared by solid state reaction to investigate dielectric properties. X-ray investigation confirms the formation of single phase with monoclinic crystal structure with space group P21/n. Scanning electron microscopy (SEM) reveals the microstructural features with an average grain size of 543 nm. Dielectric, impedance and ac conductivity of the sample were studied in the temperature range 5 – 270 K and frequency range 100 Hz – 2 MHz. Temperature dependent dielectric constant reveals a giant step (~103) which saturates at high temperature ~ 250 K. Distribution of grain size leads to a distribution of dielectric relaxation time which has been described by Cole-Cole relaxation. Coupling of Maxwell-Wagner polarization and polaronic relaxation is evident from the impedance and ac conductivity analysis.