Synthesis, structure, and magnetic properties of SrLaMnSbO6: A new B-site ordered double perovskite

Abstract

The synthesis, structural characterization, and magnetic property studies of SrLaMnSbO6 double perovskite oxide are reported. The crystal structure of SrLaMnSbO6 has been solved by powder X-ray (PXD) and neutron diffraction (NPD) data in the monoclinic space group P21/nfn (a = 5.6878(3) Å, b = 5.6990(2) Å, c = 8.0499(4) Åand β= 89.98(2)°; 295 K, NPD data). The Mn and Sb atoms are nearly completely ordered over the B-site of the perovskite structure. The octahedral framework displays significant tilting distortion according to the Glazer's tilt system a- a- c+. X-ray absorption near-edge spectroscopic (XAS) studies show the presence of Mn2+ and Sb 5+ formal oxidation states. The magnetic susceptibility data of SrLaMnSbO6 indicate the presence of ferromagnetic correlations; the calculated effective paramagnetic moment, μcaled = 5.92 μB (for HS Mn2+(3d5), S = 5/2; as evidenced by XAS data) is in good agreement with the value obtained experimentally (μexp = 5.70 μB). Variable temperature neutron diffraction data show no evidence of structural transition down to 3.7 K. A long-range antiferromagnetic ordering is established at TN = 8 K as evidenced by the magnetic susceptibility and specific heat measurements. The magnetic structure at 3.7 K is characterized by k = 0 propagation vector and m1x = -m2x, m1y = m2y = 0, m 1z = -m2z (mx = 1.26(7) μB, mz = 1.82(6) μB) coupling of magnetic moments on the Mn1 (1/2,0,0) and Mn2 (0,1/2,1/2) atoms with the ordered magnetic moment of 2.21(4) © 2008 American Chemical Society.