| Abstract
| - A new phase, SnxPt4Sb12−ySny, has been prepared from the elements. It exhibits a wide range of homogeneity with 0.3(2) ≤ x ≤ 1.0(2) and 4.2(2) ≤ y ≤ 7.0(2). The crystal structure and the composition were established by single-crystal and powder X-ray diffraction as well as wavelength-dispersive X-ray analysis measurements and were supported by nuclear magnetic resonance experiments. The compound is the first representative of the filled-skutterudite family with the filler atoms not located at the center of the cavity but covalently bonded to the cavity’s wall, as confirmed by the analysis of chemical bonding with the electron localizability indicator. The Sn and Sb atoms share the framework site with different coordinate parameters caused by the difference in atomic size; additional tin atoms are located in the cavities of the framework. The material is a diamagnet in the whole composition range. In agreement with the calculated electronic density of states, the material reveals a metallic behavior in electronic transport. The absolute values of electrical resistivity vary with the tin-to-antimony ratio.
- The filled skutterudite SnxPt4Sn12−ySby is synthesized and characterized. Tin and antimony in random distribution form the framework; a small fraction of Sn atoms occupy the icosahedral voids. In contrast to the known skutterudites, the filler Sn atoms are shifted from the center of the cavity. Analysis of the chemical bonding by the electron localizability indicator reveals direct (covalent) interactions between the filler and framework, this being observed for the first time in skutterudite-like compounds.
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