Electrical analysis of a newly synthesized rare earth double perovskite oxide: Sr2CeNbO6

A polycrystalline rare earth double perovskite oxide, strontium cerium niobate, Sr2CeNbO6 (SCN) is synthesized by solid state reaction technique for the first time. Impedance spectroscopy is employed to determine the electrical parameters (resistance (R), capacitance (C) and relaxation time (τ)) of SCN in a temperature range from 303 to 703 K and in a frequency range from 100 Hz to 1 MHz. The spectrum of imaginary part of complex impedance (Z″) at each temperature exhibits one relaxation peak. The modified Cole–Cole equation is used (experimental data is fitted with this model) to describe these relaxation peaks. Scaling behaviour of Z″ suggests that the relaxation describes the same mechanism at the entire temperature range. Impedance data of SCN that have capacitive and resistive components is represented by Nyquist diagram. The experimental impedance data is fitted using equivalent RC circuit at various temperatures. The grain conduction and τ follow an Arrhenius law associated with activation energy 0.87 and 0.88 eV, respectively.

Research Highlights
► A polycrystalline rare earth double perovskite oxide, strontium cerium niobate, Sr2CeNbO6 (SCN) is synthesized by solid state reaction technique for the first time.
► XRD pattern of the sample shows monoclinic phase of SCN.
► Dielectric relaxation observed in SCN is analysed using the simplified equivalent electrical circuit consisting of resistance capacitance (RC).
► Both R and ω obey the Arrhenius law with nearly equal activation energy (0.87 and 0.88 eV). These values suggest that the resistance and relaxation frequency vary at the same rate, implying that the capacitance of grain has a rather weak temperature dependence.