Spectroscopic properties and dielectric dispersion of K₂O-BaO-B₂O₃glasses doped with Fe₂O₃

Abstract

Alkali borate glasses doped with different concentrations of ferric oxide in the range 0-1 mol % in steps of 0.2 mol % have been prepared. The dielectric properties, especially dielectric constant e¢, loss tand a c conductivity s_ac over a wide range frequency (1-100 kHz) and temperature (30-300°C), ESR and IR spectra of Fe₂O₃ containing K₂O-BaO-B₂O₃glasses have been studied. The dielectric study reveals that the glasses have high insulating strength when Fe₂O₃ concentration is 0.8 mol % in the glass matrix. The results have been analyzed in the light of different oxidation states of iron ions with the help of IR and ESR spectra data. The analysis indicates that when the concentration of iron ions is up to 0.8 mol %, these ions exist in Fe³⁺ state that takes modifier as well as network former position, beyond this concentration some of the iron ions switch over from Fe³⁺ to Fe²⁺ state that takes network modifier positions and weakens the insulating strength of the glass.