“…Nevertheless, Phanjoubam et al [16], presents a model where some Fe 3+ ions can be present in the glass matrix in octahedral environment (i.e., network modifier) [17,18], contributing also to the ionic conductivity. Therefore, in the 94Si samples, the observed increase of the r dc , with the increase of the heat-treatment temperature ( Table 1), can be assigned to an increase of the volume ratio between the iron-based particles and the glass matrix [15]. Qiu et al [15] propose that the rise of the Fe 2+ ion content, will causes a decrease in activation energy [15], which seems to be the same behaviour on these samples (Fig.…”