Modulus spectroscopy study of a double perovskite oxide Sr2CeNbO6: Frequency and time domain analyses

A polycrystalline rare earth double perovskite oxide, strontium cerium niobate, Sr2CeNbO6 (SCN) is synthesized by solid state reaction technique for the first time. The X-ray diffraction pattern of the sample shows the monoclinic structure at room temperature. The relaxation dynamics of the conductive process present in SCN is investigated in a temperature range from 303 to 703 K and in a frequency range from 100 Hz to 1 MHz using modulus spectroscopy. The time decay function φ(t)φ(t) is obtained from the values of frequency dependence of the electric modulus (imaginary component, M  ″) by using a relaxation function in frequency domain, which is found to be a Cole–Cole distribution function. The experimental electric modulus data are fitted to the Kohlrausch-Williams-Watts exponential function φ(t)φ(t) and various relaxation characteristic parameters are analysed. The values of activation energy obtained in the whole investigated temperature range suggest the existence of the relaxation mechanism (a conductive process), which may be interpreted by ion hopping between neighbouring sites within the crystal lattice. The conductivity spectra of SCN at various temperatures are investigated considering a power law.

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