Synthesis and structure determination of Ce sub(6)Cd sub(23)Te: a new chalcogen-containing member of the RE sub(6)Cd sub(23)T family (RE is a rare-earth metal and T is a late group 14, 15 and 16 element)

The ternary phase hexacerium tricosacadmium telluride, Ce sub(6)Cd sub(23)Te, was synthesized by a high-temperature reaction of the elements in sealed Nb ampoules and was structurally characterized by powder and single-crystal X-ray diffraction. The structure, established from single-crystal X-ray diffraction methods, is isopointal with the Zr sub(6)Zn sub(23)Si structure type (Pearson symbol cF120, cubic space group Fmm), a filled version of the Th sub(6)Mn sub(23) structure with the same space group and Pearson symbol cF116. Though no Cd-containing rare-earth metal binaries are known to form with this structure, it appears that the addition of small amounts of a p-block element allows the formation of such interstitially stabilized ternary compounds. Temperature-dependent direct current (dc) magnetization measurements suggest local-moment magnetism arising from the Ce super(3+) ground state, with possible valence fluctuations at low temperature, inferred from the deviations from the Curie-Weiss law. Ce sub(6)Cd sub(23)Te is a new intermetallic phase belonging to the extended RE sub(6)Cd sub(23)T family, up until now known to encompass RE = La-Nd, Sm, and Gd, and T = Sn, Pb, Sb, and Bi. It is the first known compound in the Ce-Cd-Te ternary phase diagram.