THE STRUCTURE AND MAGNETIC-PROPERTIES OF LA(2)MIRO(6) WITH M=MG, CO, NI, AND ZN

The structure of the compounds La(2)MIrO(6) is a monoclinic deformatio n of the perovskite-like GdFeO3-type (space group P2(1)/n) with comple te ordering between iridium and M for M = Mg, Co, Ni, and Zn. These co mpounds are isomorphous with La2NiRuO6. The unit cell dimensions compa re to those of the cubic perovskite as a(m) approximate to b(m) approx imate to a(c) root 2, c(m) approximate to 2a(c), beta approximate to 9 0 degrees. The structure has been determined by Rietveld refinement on X-ray and neutron powder diffraction data. The magnetic susceptibilit y measurements show magnetic ordering for the compounds with M = Co an d Ni at 130 and 110 K respectively. (C) 1995 Academic Press, Inc.