RE 10 T Cd 3 ( RE = Y, Tb – Tm, Lu; T = Fe, Co, Ni, Ru, Rh, Pd) – Rare Earth‐rich Phases with Ordered anti ‐Co 2 Al 5 Structure

The rare earth‐rich intermetallic cadmium compounds RE 10 T Cd 3 ( RE = Y, Tb – Tm, Lu; T = Fe, Co, Ni, Ru, Rh, Pd) were synthesized by induction melting of the elements in sealed niobium ampoules. These cadmium intermetallics crystallize with an ordered variant of the hexagonal Co 2 Al 5 type, space group P 6 3 / mmc . The three crystallographically independent rare earth atoms lie on the aluminum sites, while the transition metal and cadmium atoms are ordered on the two cobalt positions. The structures of Y 10 Co 1.103 Cd 2.897 , Y 10 NiCd 3 , Y 10 RuCd 3 , Y 10 PdCd 3 , Er 9.92 FeCd 3.08 , and Er 9.82 NiCd 3.18 were refined from single‐crystal X‐ray diffraction data. Some of the crystals showed small degrees of RE /Cd, respectively T /Cd mixing. The striking structural building units are transition metal centered T @ RE 6 trigonal prisms (TP) that are condensed to empty RE 6 octahedra (O), building infinite …TP–O–O… rows in c direction. The second motifs are slightly flattened RE 3@Cd 6 RE 1 6 icosahedra. The latter are condensed via common triangular faced along the c axis. Each …TP–O–O… row is enrolled by three rows of condensed RE 3@Cd 6 RE 1 6 icosahedra in the motif of a hexagonal rod packing.