Structure and electrical properties of some Fe-doped sodium borate devitrified glasses: self-heating action

This study highlight the effect of the replacement of a transition-metal oxide Fe2O3 with a transition-metal halide FeCl3 on the structural and electrical properties of the iron–sodium borate devitrified glass. The preparation process was performed based on the fast quenching principle. The XRD patterns showed that the FeCl3-free and FeCl3/Fe2O3 samples are devitrified glasses, while the Fe2O3-free sample is a pure glass. The ESR spectral analysis showed an increase in Fe3+ at the expense of Fe2+, while the TEM and SEM images showed some crystallites suspended and distributed randomly within the amorphous glass network matrices of all samples except for that of the Fe2O3-free sample. The FTIR analysis showed an increase in BO4:BO3 ratio, as well as the presence of the structural groups (FeO4 and FeO6), where the concentration of FeO6 increased at the expense of FeO4. The V–I characteristics for the studied samples are similar to those of the P–N junction, in which the forward voltage shifted to a lower value when Fe2O3 was replaced with FeCl3. The electric measurements showed a decrease in the DC conductivity values, while that of time-dependence of temperature varying, at a constant electric power, showed that the self-heating of the studied samples decreased when Fe2O3 was replaced with FeCl3.