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RESEARCH PRODUCT
Complex high-pressure polymorphism of barium tungstate
Oscar GomisJean-claude ChervinR. Lacomba-peralesDaniel ErrandoneaYue MengAlain PolianJuan Angel SansJuan Angel Sanssubject
Phase transitionMaterials science02 engineering and technologyCrystal structureBawo47. Clean energy01 natural sciencesX-rayTetragonal crystal systemsymbols.namesakeAb initio quantum chemistry methods0103 physical sciencesCrystal010306 general physicsCaoo4Refinement021001 nanoscience & nanotechnologyCondensed Matter PhysicsElectronic Optical and Magnetic MaterialsCrystallographyFISICA APLICADA[PHYS.COND.CM-GEN]Physics [physics]/Condensed Matter [cond-mat]/Other [cond-mat.other]X-ray crystallographyTransitionsymbolsPACS: 62.50.−p 61.50.Ks 61.05.cp 63.20.ddCell0210 nano-technologyRaman spectroscopyPowder diffractionPowder DiffractionMonoclinic crystal systemdescription
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.
| year | journal | country | edition | language |
|---|---|---|---|---|
| 2012-08-27 |