LAUSR

Abstract The iron-bearing sodium borosilicate glasses with different contents of iron were prepared by the charge melting method and studied by XRD, TEM, FTIR, Mossbauer and Dynamic Impedance Spectroscopy techniques. An analysis and the transmittance spectra of two-phase sodium borosilicate glasses with different contents of iron oxide were carried out. A usage of the Mossbauer spectroscopy revealed differences between two-phase and porous glasses. In both cases Fe2+ and Fe3+ ions in octahedral and tetrahedral coordination were found, while in the two-phase glasses the significant contribution of magnetite was additionally detected. The activation energy associated with the relaxation processes determined from the electric modulus spectra was found to be in a range between 0.986 eV and 0.729 eV, which is close to the activation energy for dc conductivity. Two different conduction mechanisms were observed and their physical origin was explained. The hopping between two valence states of iron and the sodium ion conduction mechanism was additionally discussed.