High-pressure stability, pressure-volume equation of state, and crystal structure under pressure of the thermoelectric material IrSb3

There is considerable current interest in filled and unfilled skutterudites because of their potential applications as thermoelectric materials. We have compressed the unfilled skutterudite IrSb3 to pressures of 42 GPa and find that it is surprisingly stable in view of the presence of large cavities in the structure. This has implications for the both the implantation of atomic or molecular species within the cavities by means of pressure and the stability of IrSb3 under hot isostatic pressing conditions. From a fit to the pressure-volume equation of state, values were obtained for the bulk modulus and pressure derivative of the bulk modulus of 136 +/- 5 GPa and 4.8 +/- 0.5, respectively. Rietveld refinement of the crystal structure at high-pressure further demonstrates the stability of the cavities under compression.