Browsing by Author "Hendrickx, M"

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    Magnetic properties of La3Ni2SbxTayNb1–x–yO9; from relaxor to spin glass
    (Elsevier, 2019-05-01) Chin, CM; Battle, PD; Hunter, EC; Avdeev, M; Hendrickx, M; Hadermann, J
    Neutron diffraction experiments conducted at 5 K in a magnetic field 0 ≤ H/kOe ≤50 have shown that the monoclinic perovskite La3Ni2TaO9 behaves as a relaxor ferromagnet. Compositions in the series La3Ni2SbxTayNb1–x–yO9 have been synthesized in polycrystalline form. Electron microscopy, X–ray diffraction and neutron diffraction have shown that the solid solutions are largely homogeneous and monophasic. Magnetometry and neutron diffraction have shown that the relaxor magnetisation persists in low fields when x + y = 1 but is rapidly diminished by the introduction of niobium. This change in magnetic behaviour is ascribed to the differences in the d–orbital energies of Sb5+, Nb5+ and Ta5+. © 2019 The Authors CC BY licence. Published by Elsevier Inc.
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    Stabilisation of magnetic ordering in La3Ni2-xCuxB’O9 (B’= Sb, Ta, Nb) by the introduction of Cu2+
    (Elsevier, 2019-08-01) Chin, CM; Battle, PD; Hunter, EC; Avdeev, M; Hendrickx, M; Hadermann, J
    La3Ni2-xCuxB’O9 (x = 0.25; B’ = Sb, Ta, Nb: x = 0.5; B’ = Nb) have been synthesized and characterised by transmission electron microscopy, neutron diffraction and magnetometry. Each adopts a perovskite-like structure (space group P21/n) with two crystallographically-distinct six-coordinate sites, one occupied by a disordered arrangement of Ni2+ and Cu2+ and the other by a disordered ∼1:2 distribution of Ni2+ and B′5+, although some Cu2+ is found on the latter site when x = 0.5. Each composition undergoes a magnetic transition in the range 90 ≤ T/K ≤ 130 and shows a spontaneous magnetisation at 5 K; the transition temperature always exceeds that of the x = 0 composition by ≥ 30 K. A long-range ordered G-type ferrimagnetic structure is present in each composition, but small relaxor domains are also present. This contrasts with the pure relaxor and spin-glass behaviour of x = 0, B’ = Ta, Nb, respectively. © 2019 The Authors. This is an open access article under the CC BY license. Published by Elsevier Inc.