Conductivity of Li(Fe, Al)₅O₈ Spinel Solid Solutions

Abstract

The dependence of the conductivity of the Li(Fe_xAl_1-x)₅O₈ solid solution on its composition was investigated. The abrupt increase in the conductivity and decrease in the activation energy were observed between x=0.4 and 0.5 of Li(Fe_xAl_1-x)₅O₈. The composition x=0.415, which corresponds to the percolation threshold expected from the percolation theory, is within this range (x=0.4-0.5). The conductivities of the compositions above the percolation threshold were revealed to increase as (p-p_SC)^2.0(p_SC=0.311). Consequently, the abrupt increase in the conductivity is attributed to the formation of the conducting or percolation path of Fe ions among the B-sites of the spinel.