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New RMnO3+δ (R=Y, Ho; δ≈0.35) phases with modulated structure

Abstract : A series of hexagonal RMnO3 (R=Y, Ho-Lu) compounds are first annealed in various highly oxidizing conditions to show that for the largest R constituents, Y and Ho, it is possible to load the phases with large amounts of excess oxygen. Within the oxygen-annealed samples we identify new heavily-oxygenated phases, that is, YMnO3.35 and HoMnO3.34. The former is then thoroughly characterized by thermogravimetric analysis, X-ray diffraction and electron diffraction. These studies evidence a hexagonal sub-cell (aS≈3.578 Å (aH/3), cS≈11.18 Å, space group P63mc) and satellites, associated with two modulation vectors q→∗1≈0.41a→∗s+0.41b→∗ s+1/3c→∗s and q→∗2=(1/2). The results are interpreted by the formation of a modulated composite structure, resulting from the evolution of the hexagonal parent YMnO3+δ structure toward a reduced pyrochlore-type structure Y2Mn2O7-x, in long- and short-range ordering. © 2014 Elsevier Ltd. All rights reserved.
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Submitted on : Monday, July 15, 2019 - 6:04:22 PM
Last modification on : Monday, January 27, 2020 - 12:56:10 PM

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O. Parkkima, S. Malo, M. Hervieu, E.-L. Rautama, M. Karppinen. New RMnO3+δ (R=Y, Ho; δ≈0.35) phases with modulated structure. Journal of Solid State Chemistry, Elsevier, 2015, 221, pp.109-115. ⟨10.1016/j.jssc.2014.09.012⟩. ⟨hal-02184113⟩

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