Atom insertion into the CoSb₃ skutterudite host lattice under high pressure

CoSb₃ with the skutterudite-type structure was synthesized by solid-state reaction and the atom insertion into the body-centered vacant site was attempted under high pressure and temperature conditions. Various 14-group elements were selected for atom insertion under pressure of 30 MPa to 5 GPa. It was found that various elements could be inserted in the body-centered vacant site, resulting in the formation of new filled-skutterudite phase M_xCo₄Sb₁₂ (M=Si, Ge, Sn, Pb). The degree of insertion (x) increased with increasing the applied pressure. In the case of the Sn-CoSb₃ system, nearly 40% of the body-centered vacant site was filled by Sn atom at 5 GPa. The crystal structure of resulting Sn_0.4Co₄Sb₁₂ was refined by the Rietveld analysis of the X-ray diffraction data.