Abstract
Semiconducting oxide glasses of the system Fe2O3–Bi2O3–Na2B4O7 were prepared by a press-quenching method. Their DC conductivity was measured in the temperature range of 300–473K. In this temperature range, the DC conductivity increased from 10−9 to 10−5Scm−1 with increasing Fe2O3 concentration. Bi2O3 acted as a reducing agent for redox reaction during glass synthesis and affected the conductivity. Mössbauer results revealed that the relative fraction of Fe2+ increases with an increasing Fe2O3 concentration. The conduction mechanism was found to obey the non-adiabatic small polaron hopping model, and was mainly due to hopping between Fe-ions in the glasses. The small polaron coupling γp was calculated and found to be in the range of 17.06–26.25. For varying glass compositions, hopping mobility and carrier density were calculated and their values were in the range of 3.66×10−8–8.17×10−5 cm2V−1s−1 and 1.29×1017–5.04×1018 cm−3 at 400K, respectively.