Synthesis and magnetic properties of new series of one-dimensional oxides Ca3Co1+xB1-xO6 (B = Ir, Ru)

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 prisms. The magnetic susceptibility of Ca3CoIrO6 shows an abrupt drop at 30 K, as seen in the case of Sr(3)NilrO(6), suggesting that ferromagnetic chains couple antiferromagnetically. On the contrary, Ca3CoRuO6 is an 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.