Examining the effects of sintering temperature on double perovskite La2 NiTiO6 : Analysis of structural, optical, electrical properties, and leakage current characteristics

This study explores the influence of varying sintering temperatures on the structural, optical, electrical, and leakage current features of La2NiTiO6 (LNTO), a double perovskite material synthesized through the citrate autoignition method. The X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), and energy dispersive X-ray (EDX) analysis were employed to investigate the structure, microstructure, and compositional distribution of the samples. The samples sintered at various temperatures showed the monoclinic structure with space group P21/n and were confirmed by Rietveld's refinement of the XRD patterns. The average grain size increased with higher sintering temperatures, which is consistent with the particle size estimated from the histogram plot of the FE-SEM data. The UV-visible (UV-Vis) spectroscopy showed that the energy band gap decreased as sintering temperatures increased. Impedance spectroscopy analysis revealed non-Debye type relaxation of charge carriers and confirmed the negative temperature coefficient of resistance (NTCR) behavior. Electrical analysis affirmed that the direct current (DC) conductivity is thermally activated, following the Arrhenius equation with an inverse temperature dependency. As the sintering temperature increases, the leakage current density decreases, and the leakage current conforms to the ohmic conduction mechanism.