Synthesis and Characterization of ScMGa₅ (M = Fe, Co, Ni) and Yb₁₋ₓScₓCoGa₅ (0 ≤ x ≤ 1)




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The crystal structures of ScMGa5 (M = Fe, Co, Ni) have been determined by single crystal X-ray diffraction for crystals grown from a gallium self-flux. The synthesis and characterization of Yb₁₋ₓScxCoGa₅ (0 ≤ x ≤ 1) is first reported here. ScMGa₅ (M = Fe, Co, Ni) adopts the HoCoGa5-structure type and crystallizes in the tetragonal space group P4/mmm (No. 123), Z = 1, a = 4.1367(7) Å and c = 6.6422(17) Å for ScFeGa₅, a = 4.1290(11) Å and c = 6.6034(16) Å for ScCoGa₅, and a = 4.1466(6) Å and c = 6.492(2) Å for ScNiGa₅. As the transition metal atomic size increases, from Ni to Fe, the volume of the unit cell increases from 111.63(5) ų to 113.66(4) ų. The compounds consist of alternating MGa₂ edgesharing rectangular prisms interweaved with face-sharing cuboctahedra of ScGa₃ that stack in the [001] direction. ScMGa₅ (M = Fe, Co, Ni) can be structurally compared to materials adopting the AuCu₃-structure type. Yb₁₋ₓScₓCoGa₅ (0 ≤ x ≤ 1) also adopts the HoCoGa₅-structure type and crystallizes in the tetragonal space group P4/mmm. The volume of the unit cell decreases linearly with increasing Sc concentration. Inhomogeneity was found to be maximized when the nominal molar ratios of Yb and Sc were equal.



Intermetallic compounds, Crystals -- Synthesis, Inorganic compounds -- Synthesis, Chemistry, Inorganic



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