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Structural modulation in potassium birnessite single crystals

Kulish, LD and Nukala, P and Scholtens, R and Uiterwijk, AGM and Hamming-Green, R and Blake, GR (2021) Structural modulation in potassium birnessite single crystals. In: Journal of Materials Chemistry C, 9 (4). pp. 1370-1377.

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Official URL: https://dx.doi.org/10.1039/d0tc05396a


We report on the growth of single-crystal potassium birnessite (K0.31MnO2·0.41H2O) and present both the average and local structural characterization of this frustrated magnetic system. Single crystals were obtained employing a flux growth method with a KNO3/B2O3flux at 700 °C. Single-crystal X-ray diffraction revealed an average orthorhombic symmetry, with space groupCmcm. A combination of high angle annular dark field scanning transmission electron microscopy (HAADF-STEM) with atomic resolution energy dispersive X-ray spectroscopy (EDS) demonstrated the layered structure of potassium birnessite with manganese-containing planes well separated by layers of potassium atoms. MnO6octahedra and the K/H2O planes were clearly imagedviaintegrated differential phase contrast (iDPC) STEM. Furthermore, iDPC-STEM also revealed the existence of local domains with alternating contrast of the manganese oxide planes, most likely originating from charge ordering of Mn3+and Mn4+along thec-axis. These charge-ordered domains are clearly correlated with a reduction in thec-lattice parameter compared to the rest of the matrix. The insight gained from this work allows for a better understanding of the correlation between structure and magnetic properties. © The Royal Society of Chemistry 2021.

Item Type: Journal Article
Publication: Journal of Materials Chemistry C
Publisher: Royal Society of Chemistry
Additional Information: The copyright of this article belongs to Royal Society of Chemistry
Keywords: Crystal symmetry; Energy dispersive spectroscopy; High resolution transmission electron microscopy; Manganese metallography; Manganese oxide; Potash; Potassium; Potassium Nitrate; Scanning electron microscopy; Single crystals, Charge-ordered domains; Differential phase contrast; Energy dispersive X ray spectroscopy; High-angle annular dark fields; Orthorhombic symmetry; Single crystal x-ray diffraction; Structural characterization; Structural modulations, Crystal atomic structure
Department/Centre: Division of Interdisciplinary Sciences > Centre for Nano Science and Engineering
Date Deposited: 04 Mar 2021 06:50
Last Modified: 04 Mar 2021 06:50
URI: http://eprints.iisc.ac.in/id/eprint/68068

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