Analysis of AC electrical properties of (Li and Ti)-doped NiO

(Li and Ti)-doped NiO samples were prepared by the citrate precursor method followed by a sintered process, and impedance spectroscopy (IS) of these samples was measured as a function of frequency and temperature. Accordingly, the impedance spectra exhibit two depressed semicircles when the Ti content is more than 5 mol.%, which is corresponding to the core–shell microstructure. The simple resistor–capacitor (RC) effective circuit and the modified effective circuit (the capacitor in the RC circuit is replaced by a constant-phase element (CPE)) were used to fit the experimental data. And it is indicated that the CPE element is an effective tool to analyze IS.