Electrical and spectroscopic properties of Fe2O3 doped Na2SO4–BaO–P2O5 glass system

Na2SO4–BaO–P2O5 glasses doped with different concentrations of Fe2O3 were prepared. The valence states of iron ions and their coordination in the glass network have been investigated using optical absorption, ESR, IR and Raman spectroscopy. Electrical and dielectric spectral features have been studied over a wide frequency range (10− 2–106 Hz) and within the temperature range from 303 to 523 K. The ac and dc conductivities have exhibited maximal effect, whereas the activation energy for the conductivity demonstrated minimum at 1.5 mol% of Fe2O3. The ac conductivity in the low temperature region is explained based on quantum mechanical tunneling (QMT) model. The analysis of the dc conductivity indicated that at T > θD/2, the small polaron hopping model is appropriate. The dispersion of real part of dielectric constant ε′(ω), and loss, tan δ, with temperature have been analyzed quantitatively on the basis of space charge and orientation polarization models.