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 F4-bar3m. 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