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Das RR, Leclercq B, Bouvier P, Arévalo-López AM, Goujon C, Itié JP, Polian A, Mentré O, Colin CV. Compressibility of structural modulation waves in the chain compounds BaCoX 2O 7 (X = As, P): a powder study. ACTA CRYSTALLOGRAPHICA SECTION B, STRUCTURAL SCIENCE, CRYSTAL ENGINEERING AND MATERIALS 2022; 78:162-171. [PMID: 35411855 DOI: 10.1107/s2052520622001159] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/08/2021] [Accepted: 02/01/2022] [Indexed: 06/14/2023]
Abstract
BaCoX2O7 (X = As, P) are built on magnetic 1D units in which strong aperiodic undulations originate from incommensurate structural modulations with large atomic displacive amplitudes perpendicular to the chain directions, resulting in very unique multiferroic properties. High-pressure structural and vibrational properties of both compounds have been investigated by synchrotron X-ray powder diffraction and Raman spectroscopy at room temperature and combined with density functional calculations. A structural phase transition is observed at 1.8 GPa and 6.8 GPa in BaCoAs2O7 and BaCoP2O7, respectively. Sharp jumps are observed in their unit-cell volumes and in Raman mode frequencies, thus confirming the first-order nature of their phase transition. These transitions involve the disappearance of the modulation from the ambient-pressure polymorph with clear spectroscopic fingerprints, such as reduction of the number of Raman modes and change of shape on some peaks. The relation between the evolution of the Raman modes along with the structure are presented and supported by density functional theory structural relaxations.
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Affiliation(s)
- Ranjana R Das
- Institut Néel, Université Grenoble Alpes, CNRS, Grenoble, 38042, France
| | - Bastien Leclercq
- UCCS (Unité de Catalyse et Chimie du Solide), CNRS UMR 8181, Bâtiment C7, Univ. Lille - Centrale Lille/ENSCL, Avenue Mendeleiev, 59655 - Villeneuve d'Ascq, France
| | - Pierre Bouvier
- Institut Néel, Université Grenoble Alpes, CNRS, Grenoble, 38042, France
| | - Angel M Arévalo-López
- UCCS (Unité de Catalyse et Chimie du Solide), CNRS UMR 8181, Bâtiment C7, Univ. Lille - Centrale Lille/ENSCL, Avenue Mendeleiev, 59655 - Villeneuve d'Ascq, France
| | - Céline Goujon
- Institut Néel, Université Grenoble Alpes, CNRS, Grenoble, 38042, France
| | - Jean Paul Itié
- Synchrotron SOLEIL, L'Orme des Merisiers, St Aubin BP48, Gif sur Yvette Cedex, 91192, France
| | - Alain Polian
- Synchrotron SOLEIL, L'Orme des Merisiers, St Aubin BP48, Gif sur Yvette Cedex, 91192, France
| | - Olivier Mentré
- UCCS (Unité de Catalyse et Chimie du Solide), CNRS UMR 8181, Bâtiment C7, Univ. Lille - Centrale Lille/ENSCL, Avenue Mendeleiev, 59655 - Villeneuve d'Ascq, France
| | - Claire V Colin
- Institut Néel, Université Grenoble Alpes, CNRS, Grenoble, 38042, France
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