AC conductivity, electric modulus analysis of KLi(H2PO4)2 compound

Abstract

In this paper, the potassium lithium dihydrogenphosphate, KLi(H2PO4)2, has been investigated by X-ray powder diffraction (XRD), scanning electron microscopy (SEM) and electrical impedance spectroscopy. The X-ray diffraction analysis indicated the little compound was found to crystallize in the monoclinic system with space group P21/c. Electrical properties were studied using complex impedance spectroscopy as a function of frequency (4–7 MHz) at various temperatures (300–420 K). The impedance plots show semicircle arcs at different temperatures and an electrical equivalent circuit has been proposed to explain the impedance results. The equivalent circuit built up by a parallel combination of resistance (R), fractal capacitance (CPE) and capacitance (C). Single relaxation peak is observed in the imaginary part of the electrical modulus, suggesting the response of grain. Moreover, the frequency dependence of the conductivity is interpreted in term of Jonschers law: σ=σDC+fn. The near activation energies, obtained from the impedance, modulus spectra and conductivity confirms, that the transport is through a proton hopping mechanism in investigated materials.