Investigation on Temperature-Dependent Structural, Dielectric and Impedance Characteristics of Cu-doped CaFe X Ti 1-X O 3-Δ Nanotitanates

In recent days, the development of low-cost, sustainable, efficient electrode materials for energy storage applications is of great interest. Herewith, Cu-doped Ca(Ti 0.9 Fe 0.1 )O 3-δ (Cu:CTF) double-perovskite electroceramic, heat-treated at diverse temperatures (800–1100 °C) were prepared using sol–gel technology. X-ray diffraction pattern confirmed the orthorhombic structure of the prepared Cu:CTF perovskites. Significant traces of TiO 2 , CuO vanishes at elevated temperatures, which is evident from the XRD pattern. Further, the secondary phase traces were also observed in XRD, but without changing its crystal structure of Cu:CTF nanotitanate. The crystalline nature of the Cu:CTF ceramic was identified around 750 °C employing TG/DTA. UV–visible spectroscopy demonstrates the poor visible absorbance region towards the red shift with the bandgap variation of 5.28–5.42 eV. The nature of the Cu:CTF particles were analyzed using electron microscopes with the estimated particle size between 52 and 190 nm. Considering the action of temperature and frequency, complex impedance spectroscopy was utilized to analyse the inter- and intra-grain inclusions. Complex impedance spectroscopy study confirms the existence of dipole–dipole relaxation and Maxwell–Wagner (MW) polarisation for the samples heated above 900 °C. However, the a.c. test reveals the presence of conduction due to the addition of Cu 2+ ions to CaTi 1-x Fe x O 3-δ perovskite, which enhances oxygen vacancies and is strongly dependent on the inhibition of the hopping conduction mechanism.