STRUCTURAL CHARACTERIZATION AND MAGNETIC-SUSCEPTIBILITY OF BA(2)RIRI(6) DISTORTED PEROVSKITES (R=RARE EARTH)

The isostructural Ba(2)RIrO(6) (R=La, Pr, Ho) perovskites have been ch aracterized from X-ray diffraction data by means of the Rietveld metho d. They show an orthorhombic symmetry, space group Pbnm, with a random distribution of R and Ir cations in B sites. The magnetic properties of these materials have been studied via magnetic susceptibility measu rements in the temperature range 4.2-300 K. Oxidation states of III we re found for the rare earths and V for iridium when R=La and Ho, where as in the case of Ba2PrIrO6 the oxidation state of both Pr and Ir was IV. The small value obtained for the effective magnetic moment of Pr(I V), i.e. 1.30 BM, has been explained in terms of crystal field effects ; no magnetic interactions were detected.