The Properties of Reduced Bi-Ge-O Glasses for Thermoelectric Devices

The bismuth-germanate glasses have been investigated to examine their applicability for thermoelectric devices. In order to increase their electrical conductivity, the 25Bi2O3–75GeO2 glass samples have been reduced at 340-380 °C for 10 hours in hydrogen. It has been shown that such heat treatment in H2 leads to the reduction of metal ions Bi3+ and Ge4+ into neutral atoms and the formation of metal grains both in an amorphous glass matrix and on the glass surface. The bulk electrical conductivity of the reduced 25Bi2O3–75GeO2 sample measured at 100 °C is ∼ 2.6 Scm-1, whereas the Seebeck coefficient of this glass estimated in a temperature range 20-100 °C in reference to Pt is α=(-57.5±0.5) μVK-1.