STRUCTURAL CHEMISTRY AND ELECTRONIC PROPERTIES OF Sr2FeIrO6

摘要

A polycrystalline sample of Sr2FeIrO6 has been synthesized and shown by a combination of XRD, neutron diffraction, magnetometry, and Mossbauer spectroscopy to be a triclinic (space group I-1; a=5.54996(3) angstroms, b=5.57847(3) angstroms, c=7.84165(3) angstroms, alpha=89.990(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 metal cations over the six-coordinate sites. The predominant oxidation states are Fe3+ and Ir5+, although the Mossbauer data suggest that approx 4% Fe4+ 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 Fe3+ cation. The spins associated with the antisite defects are frustrated and do not take part in the long-range magnetic ordering, consequently giving rise to hysteresis in the magnetic susceptibility below 40 K. The possible location of the Fe4+ cations is discussed briefly. 19 refs.