Electrical conductivity relaxation in lithium doped silver iodide

摘要

We report on electrical conductivity relaxation measurements of single crystal lithium doped silver iodide (Li_xAg_(1-x)I, 0 <= x <= 0.2) by Admittance Spectroscopy, in the frequency range 20 Hz to 1 MHz and at temperatures between 270 and 330 K. A power-law frequency dependence of the ac conductivity is observed at low temperatures and/or high frequencies, which is characteristic of the effects of ion-ion correlation in ion hopping. An analysis of the frequency dependence of the electric modulus shows that the time decay functions for the electric field relaxation are well described by stretched exponential functions of the form exp[-(t/tau)~(1-n)]. By increasing lithium content, ionic conductivity values do not change significantly, but the exponent n is found to decrease from n = 0.54 (for x = 0) to n = 0.23 (for x = 0.2). This result points to weaker correlation effects among silver ions when the lithium content is increased.