Structural chemistry and electronic properties of Sr(2)FelrO(6)

A polycrystalline sample of Sr2FeIrO6 has been synthesized and shown by a c ombination of X-ray diffraction, neutron diffraction, magnetometry, and Mos sbauer spectroscopy to be a triclinic (space group I (1) over bar; a = 5.54 996(3) Angstrom, b = 5.57847(3) Angstrom, c = 7.84165(3) Angstrom, a = 89.9 90(1)degrees, beta = 90.059(1)degrees, gamma = 90.079(1)degrees) perovskite , with a partially ordered (0.928:0.072(4)) distribution of transition meta l cations over the six-coordinate sites. The predominant oxidation states a re Fe3+ and Ir5+, although the Mossbauer data suggest that similar to 4% Fe 4+ is present. The compound is a Type II antiferromagnet below 120 K, with an ordered magnetic moment on the Fe-dominated sites of 3.67(3) mu(B) per F e3+ cation. The spins associated with the antisite defects are frustrated a nd do not take part in the long-range magnetic ordering, consequently givin g rise to hysteresis in the magnetic susceptibility below 40 K. The possibl e location of the Fe4+ cations is discussed briefly, (C) 1999 Academic Pres s.