Electrical conductivity of Fe2O3-PbO-Bi2O3 glasses?

Fe2O3-PbO-Bi2O3 glasses were prepared by the press-quenching method and their de conductivities in the temperature range 373-573 K were measured. The glass formation region was found to be Fe2O3=0-30 mol%, PbO=0-40 mol%, Bi2O3=0-100 mol%. The Seebeck coefficients showed these glasses to be p-type semiconductors. The glasses had conductivities, sigma, ranging from 2.82 x 10(-6) S . cm(-1) to 2.69 x 10(-4) S . cm(-1) at 573 K for Fe2O3 = 20-30 mol%. The de conductivity increased with increasing Fe2O3 content. Electrical conduction was confirmed to be due to nonadiabatic small polaron hopping, and the conductivity was primarily determined by the hopping mobility. The polaron band width, J, ranged from 0.03 to 0.28 eV depending on the Fe-Fe spacing. The IR absorption spectra suggested that the quenched glasses contained FeO4 tetrahedra and BiO6 octahedra.