Browsing by Author "Paria Sena, R"

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    Magnetic properties of the 6H perovskite Ba3Fe2TeO9
    (Elsevier, 2017-09-01) Tang, YW; Paria Sena, R; Avdeev, M; Battle, PD; Cadogan, JM; Hadermann, J; Hunter, EC
    A polycrystalline sample of Ba3Fe2TeO9 having the 6H perovskite structure has been prepared in a solid-state reaction and studied by a combination of electron microscopy, Mössbauer spectroscopy, magnetometry, X-ray diffraction and neutron diffraction. Partial ordering of Fe3+ and Te6+ cations occurs over the six-coordinate sites; the corner-sharing octahedra are predominantly occupied by the former and the face-sharing octahedra by a 1:1 mixture of the two. On cooling through the temperature range 18 < T/K < 295 an increasing number of spins join an antiferromagnetic backbone running through the structure while the remainder show complex relaxation effects. At 3 K an antiferromagnetic phase and a spin glass coexist. © 2017 The Authors. Creative Commons license Published by Elsevier Inc.
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    Structural chemistry and magnetic properties of the perovskite Sr3Fe2TeO
    (Elsevier, 2016-06-29) Tang, YW; Hunter, EC; Battle, PD; Paria Sena, R; Hadermann, J; Avdeev, M; Cadogan, JM
    A polycrystalline sample of perovskite-like Sr3Fe2TeO9 has been prepared in a solid-state reaction and studied by a combination of electron microscopy, Mössbauer spectroscopy, magnetometry, X-ray diffraction and neutron diffraction. The majority of the reaction product is shown to be a trigonal phase with a 2:1 ordered arrangement of Fe3+ and Te6+ cations. However, the sample is prone to nano-twinning and tetragonal domains with a different pattern of cation ordering exist within many crystallites. Antiferromagnetic ordering exists in the trigonal phase at 300 K and Sr3Fe2TeO9 is thus the first example of a perovskite with 2:1 trigonal cation ordering to show long-range magnetic order. At 300 K the antiferromagnetic phase coexists with two paramagnetic phases which show spin-glass behaviour below ~80 K. © 2016 The Authors. Published by Elsevier Inc. This is an open access article under the CC BY license