Thermoelectric properties of bismuth-silica nanocomposites

Bulk bismuth-silica nanocomposites have been prepared via powder metallurgy to study the influence of silica inclusions on the transport properties of Bi-based materials. Bi-SiO/sub 2/ ultrafine powders were produced by an arc-plasma processing. TEM investigations revealed the presence of a nanometric silica shell around each Bi grain. The nanocomposite powders were cold pressed and sintered close to the melting temperature of bismuth. The electrical resistivity was measured from 5 K to 300 K, the thermoelectric power, the thermal conductivity and the thermoelectric figure of merit were measured from 65 K to 300 K. The transport properties of pure single crystalline and polycrystalline bismuth are compared to those of nanocomposite materials.