Thermoelectric properties of semi-metallic Ru₂Sn_3-δ with low thermal conductivity

Intermetallic Ru₂Sn₃-δ was found to show high thermoelectric performance of ZT ∼ 0.3 at temperatures around 660 K. The transport properties, combined with the electronic structure calculation, indicate that Ru₂Sn₃ is a semi-metal with contrasting dispersions between the hole and electron bands, which generate a large thermoelectric power of S ∼ 100 μuV/K. A low thermal conductivity κ of around 1Wm^-1 K^-1 was observed above room temperature, which is likely due to the strong lattice anharmonicity associated with the martensitic transformation.