Crystal structures and magnetic properties of ordered perovskites A(2)R(3+)Ir(5+)O(6) (A=Sr, Ba; R=Sc, Y, La, Lu)

The ordered perovskite-type compounds A(2)RIrO(6) (A = Sr, Ba; R = Sc, Y, L u, La), with the exception of Sr2LaIrO6, were prepared. Using the Rietveld method, their crystal structures were assigned to be monoclinic (space grou p P2(t)/n) with a fully ordered arrangement between R and Ir ions. For Sr2S cIrO6 and Ba2ScIrO6, small amounts of disordered arrangements between Sc an d Ir ions were found. The magnetic susceptibilities of these compounds show paramagnetic behavior down to 4.5 K. The magnetic behavior for these compo unds is explained by Kotani's theory and the spin-orbit coupling constants for the Ir(V) ion were calculated. (C) 1999 Elsevier Science S.A. All right s reserved.