SYNTHESIS AND MAGNETIC-PROPERTIES OF NEW SERIES OF ONE-DIMENSIONAL OXIDES CA3CO1-XO6 (B = IR, RU)(XB1)

New one-dimensional compounds Ca3CoBO6 (B = Ir, Ru) with K4CdCl6-type structure have been synthesized by conventional solid state reactions. Both compounds adopt the rhombohedral symmetry with the space group R (3) over bar c; a = 9.1811(1) Angstrom, c = 10.8232(3) Angstrom, Z = 6 (hexagonal expression) for Ca3CoIrO6 and a = 9.1921(3) Angstrom, c = 10.7784(7) Angstrom, Z = 6 for Ca3CoRuO6. One-dimensional chains are built by alternating face-shared CoO6 octahedra and BO6 trigonal prism s. The magnetic susceptibility of Ca3CoIrO6 shows an abrupt drop at 30 K, as seen in the case of Sr(3)NilrO(6), suggesting that ferromagneti c chains couple antiferromagnetically. On the contrary, Ca3CoRuO6 is a n ordinary antiferromagnet with T-N = 55 K. We have also succeeded in preparing the solid solution series, Ca3Co1 + xIr1 - xO6 and Ca(3)Co(1 + x)Zu(1 - x)O(6) (0 less than or equal to x less than or equal to 1) , and magnetic properties of these systems were investigated. (C) 1998 Academic Press.