Lutetium‐rich phases with a coloring variant of the Y 3 Rh 2 type structure

The lutetium‐rich intermetallic compounds Lu 21 T 14– x In x ( T =Rh, Pd, Pt) with x values ranging from 1.57 to 4.70 were synthesized from the elements in sealed tantalum ampules in an induction furnace with a special annealing sequence. Two samples from each solid solution were studied by powder X‐ray diffraction and the structures of Lu 21 Rh 10.36 In 3.55 , Lu 21 Rh 12.43 In 1.57 , Lu 21 Pd 9.74 In 4.26 , Lu 21 Pd 10.19 In 3.81 , Lu 21 Pt 9.26 In 4.70 and Lu 21 Pt 9.93 In 4.07 were refined from single crystal X‐ray diffractometer data. All phases crystallize with coloring variants of the Y 3 Rh 2 type structure, space group I 4/ mcm (No. 140). The Lu 21 T 14– x In x phases are built up from a tetragonal rod packing of columns that consist of a condensation of square prisms and square antiprisms of the lutetium atoms that are centered by the indium and transition metal atoms. These columns condense with the substructure of coordination number 9 and 11 polyhedra around the Pt2 and In1/Pt5 atoms. The striking features of the ternary samples concern small defects on the transition metal 16 l sites and T /In mixing on the sites 16 l and 4 c .