Effect of lithium doping on electrophysical and diffusion properties of nonstoichiometric superionic copper selenide Cu_1.75Se

Abstract

The results of studies of the ionic conductivity and the conjugated chemical diffusion coefficients (CCDC) in the nonstoichiometric LixCu1.75Se(0 ≤ x ≤ 0.25) ternary alloys are presented. It has been observed that the values of the ionic conductivity of Cu1.75Se copper selenide decreases with lithium doping in general owing to increasing the the activation energy. The increasing of the conjugate chemical diffusion coefficients of the cations and electron holes was observed with increasing of lithium content, despite the decreasing of self-diffusion coefficients of the cations and decreasing of electron mobilities. The behavior of the conjugate chemical diffusion coefficients explained by a decrease in the degree of non-stoichiometry of the composition, leading to an increase of the internal electric field accelerating the motion of slower particles.