Ac conductivity and NSPT model conduction of KAlP2O7 compound

Abstract

The KAlP2O7 compound was prepared by conventional solid-state reaction technique. The structure is confirmed by X-ray powder diffraction. The frequency-dependent electrical properties of the sample were investigated in the temperature range of 528–668 K and in the frequency range of 209 Hz–5 MHz by impedance spectroscopy. The ac conductivity has been fitted and studied using Jonscher’s equation, whose exponent s varied with the temperature, showing that the non-overlapping small polaron tunneling (NSPT) is the suitable model to describe the electrical conduction mechanism. The variation of dc conductivity suggests Arrhenius type. Besides, the modulus data were analyzed using the Kohlrausch–Williams–Watts (KWW) stretched exponential function. The peak positions ωm of the above spectra shifted towards higher frequencies with the increase in temperature. Moreover, the value of activation energy for the bulk obtained from the analysis of equivalent circuit (1.11 eV) and modulus relaxation (0.91 eV) confirms that the transport is not due to a simple hopping mechanism and that the ion transport is probably due to the hopping of K+ ions along [101] tunnels direction. The thermodynamic parameters were also calculated.