CRYSTAL-STRUCTURE AND PHYSICAL-PROPERTIES OF CE3PD6SB5

A new ternary antimonide, Ce3Pd6Sb5, was prepared by are melting of th e elemental components and subsequent annealing at 750 degrees C. Its orthorhombic crystal structure was determined from single-crystal X-ra y data: space group, Pmmn; Z = 2; a = 1348.1(2) pm, b = 445.9(1) pm an d c = 1005.0(1) pm; V = 0.6041(2) nm(3), wR(2) = 0.045; 1432 F-2 value s; 48 variables. The structure of Ce3Pd6Sb5 is of a new type, built fr om three pseudo-body-centered subcells of the cerium atoms. Palladium and antimony atoms form a three-dimensional infinite polyanion [Pd6Sb5 ] with an atomic arrangement derived from the well-known ThCr2Si2 and CaBe2Ge2 structures. The crystal chemistry of this new compound is dis cussed together with the related Dy3Co6Sn5-type structure. The magneti c susceptibility exhibits significant anisotropy with an effective hig h temperature moment per cerium of 2.67 mu(B) and antiferromagnetic or dering at 6 K. The resistance shows a minimum near 17 K, possibly sugg esting some Kondo-type interactions, and an anomaly at 6 K which corre sponds to the antiferromagnetic ordering.