Intermetallic phases in the Sc–Ir–In system – synthesis and structure of Sc1.024Ir2In0.976 and Sc3Ir1.467In4

Abstract The intermetallic scandium compounds Sc 1.024 Ir 2 In 0.976 and Sc 3 Ir 1.467 In 4 were synthesized by reactions of the elements in sealed tantalum ampoules at high temperature followed by annealing for crystal growth. Both structures were refined from single-crystal X-ray diffractometer data: MnCu 2 Al type, Fm3‾m $Fm‾{3}m$ , a = 639.97(19) pm, wR 2 = 0.0376, 41 F 2 values, seven variables for Sc 1.024 Ir 2 In 0.976 and P6‾ $P‾{6}$ , a = 769.99(5), c = 684.71(4) pm, wR 2 = 0.0371, 967 F 2 values, 33 variables for Sc 3 Ir 1.467 In 4 . Sc 1.024 Ir 2 In 0.976 is a new Heusler phase with a small homogeneity range due to Sc/In and In/Sc mixing. The structure of Sc 3 Ir 1.467 In 4 is closely related to that of Sc 3 Rh 1.594 In 4 and belongs to the large family of ZrNiAl superstructures. The striking structural motif is the ordered stacking of empty In 6 and filled Ir@In 6 prisms with Ir–In distances of 269 pm.