The effect of elemental substitution on the electronic properties of Ru2Ge3

Abstract

The effect of chemical substitution on the electrical resistivity and Seebeckcoefficients of Ru2Ge3 is reported, with a particular emphasis on enhancingthe properties relevant to thermoelectric behaviour. The properties ofRu2Ge3 itself are shown to be strongly dependent on quenching temperature.The effects of metal doping for Ru and metalloid substitution (Sn andSi) for Ge are reported. It is shown that doping of both ruthenium andgermanium sites is required to reduce the high resistivity of Ru2Ge3(∼ 280 mΩ cm at 300 K) to avalue of 1.5 mΩcm, for Ru1.85Mn0.15Ge2.4Sn0.6 while maintaining high Seebeckcoefficients. This latter composition has the highest thermoelectric figure ofmerit observed in this system: ZT 300 K = 1 × 10−2.Unfortunately this value is too small to be competitive with existing materials.