Thermal conductivity ofxFe2O3 · (1−x) [3 B2O3 · PbO] glasses

The thermal conductivity and thermal diffusivity of thexFe₂O₃ · (1–x) 3 B₂O₃ · PbO] glasses containing 0, 5, 15, 25, 35 and 50 mol % Fe₂O₃ were studied. Measurements were performed at temperatures ranging from 100 to 450 K. From the results obtained for thermal conductivity and diffusivity the specific heats of samples were calculated and comparated with those obtained from the additive rules. Our results do not prove the validity of the additive rules. The observed deviations were assigned to structural factors. By using the approximation of the Debye model the average sound velocity, the mean free path and dominant angular frequency of phonon have been calculated. The deviation of phonon mean free path from the average value as a function density fluctuations of the samples was discussed.