Electrical and thermal properties of semiconducting Fe2O3–Bi2O3–Na2B4O7 glasses

xFe2O3–(25 − x)Bi2O3–75Na2B4O7 glasses with x = 5, 10, 15 and 20 mol% were prepared by press-quenching from glass melts, and their dc conductivity (σ) were determined in the temperature range 300–473 K. It is found that the dc conductivity increased from 10−9 to 10−5 S cm−1 with increasing Fe2O3 content. The small polaron hopping (SPH) model of Mott is used for the interpretation of the temperature dependence of the activation energy. Results of thermal analysis performed at different heating rates on these glasses are reported and discussed. From the heating rate dependence of the glass transition temperature (Tg) and the peak temperature of crystallization (Tp) values of the activation energy for glass transition (Et) and the activation energy for crystallization (Ec) are evaluated, and their composition dependence is discussed.