Effect of iron substitution on electronic conductivity of bismuth sesquioxide glasses

Several glassy oxide semiconductors exhibit large electron mobilities; however, these oxides may not be considered environmentally friendly because of their toxicity. Herein, we report on the electrical conduction of iron oxide-containing bismuth sesquioxide borate glasses that are not toxic and show ohmic transport in the temperature range of 100-400 degrees C. The dominant carrier is the electron, which is revealed by the signs of Hall and Seebeck coefficients, without sign anomalies. The Hall mobility is similar to 0.1 cm(2)/(V s), and the carrier density is similar to 6 x 1015 cm(-3) at 400 degrees C. The Seebeck coefficient is approximately -500 mu V/K at 388 degrees C. The carriers might be generated by charge transfer between Fe2+ and Fe3+ substituted in the glass, and they exhibit thermally activated hopping-type electronic conduction. The oxide glass can be used as a glass thermistor for a temperature range of 100-400 degrees C.