Complex high-pressure polymorphism of barium tungstate
We have studied BaWO 4 under compression at room temperature by means of x-ray diffraction and Raman spectroscopy. When compressed with neon as a pressure-transmitting medium (quasihydrostatic conditions), we found that BaWO 4 transforms from its low-pressure tetragonal structure into a much denser...
| Autores: | , , , , , , |
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| Tipo de recurso: | artículo |
| Fecha de publicación: | 2012 |
| País: | España |
| Institución: | Universitat Politècnica de València (UPV) |
| Repositorio: | RiuNet. Repositorio Institucional de la Universitat Politécnica de Valéncia |
| Idioma: | inglés |
| OAI Identifier: | oai:riunet.upv.es:10251/47801 |
| Acceso en línea: | https://riunet.upv.es/handle/10251/47801 |
| Access Level: | acceso abierto |
| Palabra clave: | X-ray Powder Diffraction Bawo4 Crystal Refinement Transition Caoo4 Cell FISICA APLICADA |
| Sumario: | We have studied BaWO 4 under compression at room temperature by means of x-ray diffraction and Raman spectroscopy. When compressed with neon as a pressure-transmitting medium (quasihydrostatic conditions), we found that BaWO 4 transforms from its low-pressure tetragonal structure into a much denser monoclinic structure. This result confirms our previous theoretical prediction based on ab initio calculations that the scheelite to BaWO 4-II transition occurs at room temperature if kinetic barriers are suppressed by pressure. However, our experiment without any pressure- transmitting medium has resulted in a phase transition to a completely different structure, suggesting nonhydrostaticity may be responsible for previously reported rich polymorphism in BaWO 4. The crystal structure of the low- and high-pressure phases from the quasihydrostatic experiments has been Rietveld refined. Additionally, for the tetragonal phase the effects of pressure on the unit-cell volume and lattice parameters are discussed. Finally, the pressure evolution of the Raman modes of different phases is reported and compared with previous studies. © 2012 American Physical Society. |
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