Preparation and thermoelectric properties of A/sub 8//sup II/B/sub 16//sup III/B/sub 30//sup IV/ clathrate compounds

The preparation, characterisation and measurements of the temperature dependence of the transport properties of clathrate compounds Ba/sub 8/Ga/sub 16/Si/sub 30/, Ba/sub 8/Ga/sub 16/Ge/sub 30/, Ba/sub 8/Ga/sub 16/Sn/sub 30/, and Sr/sub 8/Ga/sub 16/Ge/sub 30/ are reported. The samples were characterised using X-ray diffraction, differential thermal analysis, electrical resistivity, Seebeck coefficient and Hall coefficient measurements. The materials possess a moderate negative Seebeck coefficient and a low electrical resistivity which increase with increasing temperature. The potential for thermoelectric applications of these materials is assessed.