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Defect-Accommodating Intermediates Yield Selective Low-Temperature Synthesis of YMnO 3 Polymorphs.
- Source :
-
Inorganic chemistry [Inorg Chem] 2020 Sep 21; Vol. 59 (18), pp. 13639-13650. Date of Electronic Publication: 2020 Aug 31. - Publication Year :
- 2020
-
Abstract
- In the synthesis of complex oxides, solid-state metathesis provides low-temperature reactions where product selectivity can be achieved through simple changes in precursor composition. The influence of precursor structure, however, is less understood in solid-state synthesis. Here we present the ternary metathesis reaction (LiMnO <subscript>2</subscript> + YOCl → YMnO <subscript>3</subscript> + LiCl) to target two yttrium manganese oxide products, hexagonal and orthorhombic YMnO <subscript>3</subscript> , when starting from three different LiMnO <subscript>2</subscript> precursors. Using temperature-dependent synchrotron X-ray and neutron diffraction, we identify the relevant intermediates and temperature regimes of reactions along the pathway to YMnO <subscript>3</subscript> . Manganese-containing intermediates undergo a charge disproportionation into a reduced Mn(II,III) tetragonal spinel and oxidized Mn(III,IV) cubic spinel, which lead to hexagonal and orthorhombic YMnO <subscript>3</subscript> , respectively. Density functional theory calculations confirm that the presence of Mn(IV) caused by a small concentration of cation vacancies (∼2.2%) in YMnO <subscript>3</subscript> stabilizes the orthorhombic polymorph over the hexagonal. Reactions over the course of 2 weeks yield o-YMnO <subscript>3</subscript> as the majority product at temperatures below 600 °C, which supports an equilibration of cation defects over time. Controlling the composition and structure of these defect-accommodating intermediates provides new strategies for selective synthesis of complex oxides at low temperatures.
Details
- Language :
- English
- ISSN :
- 1520-510X
- Volume :
- 59
- Issue :
- 18
- Database :
- MEDLINE
- Journal :
- Inorganic chemistry
- Publication Type :
- Academic Journal
- Accession number :
- 32866379
- Full Text :
- https://doi.org/10.1021/acs.inorgchem.0c02023