Structure and magnetic properties of RE₄CoCd and RE₄RhCd (RE = Tb, Dy, Ho).

New rare earth metal rich cadmium compounds RE₄CoCd and RE₄RhCd (RE = Tb, Dy, Ho) were prepared by high-frequency melting of the elements in sealed tantalum tubes. The samples were studied by x-ray powder and single-crystal diffraction. All the compounds crystallize with Gd₄RhIn-type structure, with space group [Formula: see text]. The structures are built up from rigid three-dimensional networks of condensed, cobalt (rhodium) centred trigonal RE₆ prisms. The voids left by these networks are filled by Cd₄ cluster units and the coordination number 14 polyhedra of the RE1 atoms. The terbium and dysprosium compounds in both series undergo antiferromagnetic ordering, whereas the holmium compounds exhibit ferromagnetic ordering. The magnetic ordering in these compounds is characterized by broad peaks around the transition temperatures. The results of detailed crystallographic investigations and preliminary magnetic and specific heat studies are presented and discussed in this work.