The synthesis and structure of two filled skutterudite compounds: BaFe₄Sb₁₂ and BaRu₄Sb₁₂

Two compounds, BaT₄Sb₁₂ (T = Fe, Ru), have been synthesized using high temperature methods. These compounds crystallize in the cubic LaFe₄P₁₂ structure type. Two methods are described for the synthesis of BaFe₄Sb₁₂. Single crystals of BaFe₄Sb₁₂ can be prepared by reacting BaSb, Fe, and Sb in a 1:4:18 (Ba:Fe:Sb) molar ratio (method I). Single crystal X-ray diffraction data (room temperature, a = 9.200(3) Å) for BaFe₄Sb₁₂ prepared by Method I were refined (cubic, Im3 (No. 204), Z = 2, R = 1.96%, R_w = 1.73% for 179 independent reflections). BaFe₄Sb₁₂ can also be prepared in ≥80% yield from the reaction of stoichiometric amounts of Ba₂Sb₃, FeSb₂, and Sb (method II). Low temperature (130 K, a = 9.188(2)) single crystal X-ray diffraction data on BaFe₄Sb₁₂ crystals produced from Method II were also measured and refined (R = 2.29%, R_w = 2.45% for 179 independent reflections). The structure of BaFe₄Sb₁₂ will be compared to that of the LaFe₄Sb₁₂ and CoSb₃.