Structural, vibrational, electrical and dielectric investigation of pyrophosphate compounds Li2Cu(1-(5/2)x) VxP2O7 (x=0 and 0.2)

The objective of this work is to study the electrical/dielectric properties of new pyrophosphates Li2Cu(1-5/2)xVxP2O7 (x = 0.2) prepared by the ceramic method. The desired phase is identified by X-ray diffraction (XRD), Raman Spectroscopy, Infrared Spectroscopy (IR) and Differential Scanning Calorimetry (DSC). The Differential Scanning Calorimetry spectrum discloses Phase Transition at 624 K. Impedance Spectroscopy is used to analyze the electrical and dielectric characteristics over a wide temperature (574-713 K.) and frequency (209 Hz-5 MHz) range. From the Direct Current (DC) conductivity and Alternating Current (AC) conductivity, electrical conduction is found to be thermally activated process. The temperature-dependent behavior of parameter s, resulting from AC conductivity fitting at different temperatures, described the Conduction Mechanism with the Non-Small Polaron Tunneling (NSPT) model predicting it at low temperatures (T < 624 K) and the inverse Overlapping Large Polaron tunnel (OLPT) model predicting it at higher temperatures (T > 624 K). The Aliovalent incorporation of vanadium (V5+) into copper (Cu2+) improves electrical conduction for the synthesized compound Li2Cu0.5V0.2P2O7, according to a comparative analysis of the two compounds Li2Cu(1-(5/2)x)VxP2O7 (x = 0 and x = 0.2).