Lutetium-rich phases with a coloring variant of the Y3Rh2 type structure

The lutetium-rich intermetallic compounds Lu21T14-xInx (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 Lu21Rh10.36In3.55, Lu21Rh12.43In1.57, Lu21Pd9.74In4.26, Lu21Pd10.19In3.81, Lu21Pt9.26In4.70 and Lu21Pt9.93In4.07 were refined from single crystal X-ray diffractometer data. All phases crystallize with coloring variants of the Y3Rh2 type structure, space group I4/mcm (No. 140). The Lu21T14-xInx 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 4c.