Título:
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Effect of pressure on La2(WO4)3 with a modulated scheelite-type structure
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Autor/a:
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Sabalisck, N. P.; López-Solano, J.; Guzmán-Afonso, C.; Santamaría-Pérez, D.; González-Silgo, C.; Mujica, A.; Muñoz, A.; Rodríguez-Hernández, P.; Radescu, S.; Vendrell, Xavier; Mestres i Vila, Ma. Lourdes; Sans, J. A.; Manjón, F. J.
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Otros autores:
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Universitat de Barcelona |
Abstract:
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We have studied the effect of pressure on the structural and vibrational properties of lanthanum tritungstate La2(WO4)3. This compound crystallizes under ambient conditions in the modulated scheelite-type structure known as the α phase. We have performed x-ray diffraction and Raman scattering measurements up to a pressure of 20 GPa, as well as ab initio calculations within the framework of the density functional theory. Up to 5 GPa, the three methods provide a similar picture of the evolution under pressure of α-La2(WO4)3. At 5 GPa, we begin to observe some structural changes, and above 6 GPa we find that the x-ray patterns cannot be indexed as a single phase. However, we find that a mixture of two phases with C2/c symmetry accounts for all diffraction peaks. Our ab initio study confirms the existence of several C2/c structures, which are very close in energy in this compression range. According to our measurements, a state with medium-range order appears at pressures above 9 and 11 GPa, from x-ray diffraction and Raman experiments, respectively. Based upon our theoretical calculations we propose several high-pressure candidates with high cationic coordinations at these pressures. The compound evolves into a partially amorphous phase at pressures above 20 GPa. |
Materia(s):
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-Terres rares -Difracció de raigs X -Espectroscòpia Raman -Propietats òptiques -Ferromagnetisme -Rare earths -X-rays diffraction -Raman spectroscopy -Optical properties -Ferromagnetism |
Derechos:
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(c) American Physical Society, 2014
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Tipo de documento:
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Artículo Artículo - Versión publicada |
Editor:
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American Physical Society
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