Electrical transport mechanism in a newly synthesized rare earth double perovskite oxide Sr2CeTaO6

Abstract

A rare earth double perovskite oxide strontium cerium tantalate, Sr2CeTaO6 (SCT) is synthesized by the solid state reaction technique for the first time. The determination of lattice parameters and the identification of phase are carried out by the Rietveld refinement method (RRM) using the Fullprof program in the space group P21/n (C52h). A structure of SCT is obtained from RRM. The bond angle and bond length are calculated and listed in Table 1 for SCT. A small amount of impurity of CeO2 is found in the refinement with space group Fm3m. The scanning electron micrograph shows the average grain size ∼2μm. The ac electrical property is investigated in the temperature range from 303 to 703K and in the frequency range from 0.1kHz to 1MHz using impedance spectroscopy. The relaxation mechanism of SCT is explained in detail by fitting experimental impedance and electric modulus data with the modified Debye (Cole–Cole) model. The frequency-dependent electrical data are analyzed in the framework of the conductivity and modulus formalisms. The σac data are fitted with Jonscher's universal power law. The dc conductivity (σdc) (calculated from σac) follows an Arrhenius law with the estimated conduction activation energy =0.78eV. The scaling behavior of imaginary part of electrical impedance (Z″) shows that the relaxation describes the same mechanism at various temperatures.