Filled IrxCo1-xSb3-based skutterudite solid solutions

Forming iso-electronic solid solutions is a standard approach to achieving low lattice thermal conductivity in thermoelectric materials. The phase diagram for Ir_xCo_1-xSb₃ solid solutions is calculated by ab initio method, and a limited solid solubility is predicted. We were able to prepare pure and filled CoSb₃ doped with Ir in single phase form for the doping concentrations x less than 0.15. The samples maintain very good electrical transport properties due to weak charge carrier scattering from the iso-electronic atoms and, at the same time, the lattice thermal conductivity is reduced significantly. A systematic study of the lattice thermal conductivity of Ir_xCo_1-xSb₃ was carried out over a broad range of temperatures from 2 K to 800 K. The behavior of the lattice thermal conductivity as a function of the filling fraction and the concentration of Ir is presented. The data indicate that Ir-doped skutterudite solid solutions are good candidates for high temperature thermoelectric applications.