PREPARATION, STRUCTURE AND MAGNETIC-PROPERTIES OF A NEW NICKEL(III) OXIDE YBSR3NIO6

An investigation of the Yb2-xSrNiO4-delta system has shown that no pha ses crystallise with a K2NiF4 structure for reaction temperatures up t o 1100-degrees-C at 1 atm oxygen pressure, but a new phase of ideal co mposition YbSr3NiO6 is formed. Rietveld refinement using powder X-ray diffraction data shows that YbSr3NiO6 adopts a rhombohedral K4PtCl6 ty pe structure [R3cBAR, Z = 6, a = 9.6851(2) angstrom, c = 11.0960(2) an gstrom, R(wp) = 2.8%], with a deficiency of scattering from the Yb sit e due to 11% Yb vacancies or possibly cation substitutions. Iodometric titrations suggest an average Ni oxidation state of 3.0+. Magnetic su sceptibility data for YbSr3NiO6 between 5 and 300 K show Curie-Weiss b ehaviour at higher temperatures, characteristic of Yb3+ and low-spin N i3+ with overall mu(eff) = 4.63(1) mu(B) and theta(W) = -29.0(1) K. A broad susceptibility maximum at 12 K may be due to one-dimensional ant iferromagnetic order.