Conductivity of Li(Fe,Al)(5)O-8 spinel solid solutions

The dependence of the conductivity of the Li(FexAl1-x)(5)O-8 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(FexAl1-x)(5)O-8. 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.