Influence of calcium substitution on structural, morphological and electrical conductivity properties of La1- xCaxNi0.5Ti0.5O3 (x=0.0, x=0.2) compounds for energy storage devices

This paper explores the effect of calcium insertion on the physicochemical properties of La1-xCaxNi0.5Ti0.5O3 (x = 0.0 (LNTO), x = 0.2 (LCNTO)) compounds fabricated by the sol-gel process. The samples crystallize in an orthorhombic distorted structure with the Pnma space group. The purity and morphology of nano-grains were evaluated by SEM/ EDX analysis. The behaviors of the imaginary parts of the impedance (Z'') show a dielectric relaxation phenomenon in the samples with activation energies close to those determined from the conductivity study. Nyquist diagrams are fitted using two circuits in series; each circuit consists of resistance in parallel with a CPE capacitance. The DC-conductivity enhances significantly with temperature confirming that our sample has a semiconductor behavior. The conduction mechanism was evaluated using the temperature dependence of the exponent Jonscher's power law parameter, which confirms the type of NSPT conduction mechanism for the compound LNTO and (NSPT) in zone I (T < 255 K) and (OLPT) in zone II (T > 255 K) for the LCNTO compound. The observed high conductivity indicates that our materials may be suitable for applications in energy storage devices.