New Phases in the Sc−Mn−Si and Sc−Mn−Al−Si Systems Through Molten Indium Flux Synthesis

Abstract Through the application of synthesis via molten indium flux, we have been able to expand the ternary Sc−Mn−Si system and the quaternary Sc−Mn−Al−Si system. Specifically, we report on five previously unknown chemical compounds, namely β ‐ScMnSi 2 , Sc 4+ x Mn 4 Si 7–2 x , Sc 2 Mn 4 Si 5 , Sc 2 Mn 3 Si 4 , and Sc 4 Mn 2 AlSi 4 . The compounds with the stoichiometries Sc 2 Mn 4 Si 5 , Sc 2 Mn 3 Si 4 , and Sc 4 Mn 2 AlSi 4 have previously not been reported. We find that these crystallize in the V 6 Si 5 , Hf 2 Ru 3 Si 4 , and Ho 4 Ni 2 InGe 4 structure types, respectively. For the ternary compounds with the stoichiometries of ScMnSi 2 and Sc 4+ x Mn 4 Si 7–2 x , we find clearly deviating structural solutions compared to earlier reports. β ‐ScMnSi 2 is found to crystallize in the monoclinic crystal system isostructural to a supercell of the MnTiSi 2 structure and clearly deviating from the known orthorhombic α ‐polymorph. The compound Sc 4+ x Mn 4 Si 7–2 x is structurally very similar to Sc 4 Mn 4 Si 7 , but exhibits the P 4/ nmm space group instead of I 4/ mmm , and is related to the Zr 4 Co 4 Ge 7 structure. Disorder between Si and Sc sites leads to the off‐stoichiometric composition, for which we found x =0.287(5).