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High-pressure phase transitions and compressibility of wolframite-type tungstates

Abstract: This paper reports an investigation on the phase diagram and compressibility of wolframite-type tungstates by means of x-ray powder diffraction and absorption in a diamond-anvil cell and ab initio calculations. X-ray diffraction experiments show that monoclinic wolframite-type MgWO4 suffers at least two phase transitions, the first one being to a triclinic polymorph with a structure similar to that of CuWO4 and FeMoO4-II. The onset of each transition is detected at 17.1 and 31 GPa. In ZnWO4 the onset of the monoclinic-triclinic transition has been also found at 16.7 GPa. This transition does not involve any change in the atomic coordination as confirmed by x-ray absorption measurements. These findings are supported by density-functional theory calculations, which predict the occurrence of additional transitions upon further compression. Calculations have been also performed for wolframite-type MnWO4, which is found to have an antiferromagnetic configuration. In addition, our study reveals details of the local-atomic compression in MgWO4 and ZnWO4. In particular, below the transition pressure the ZnO6 and equivalent polyhedra tend to become more regular, whereas, the WO6 octahedra remain almost unchanged. Fitting the pressure-volume data we obtained the equation of state for the low-pressure phase of MgWO4 and ZnWO4. These and previous results on MnWO4 and CdWO4 are compared with the calculations. The compressibility of wolframite-type tungstates is also systematically discussed. Finally Raman spectroscopy measurements and lattice dynamics calculations are presented for MgWO4.

Otras publicaciones de la misma revista o congreso con autores/as de la Universidad de Cantabria

 Fuente: Journal of Applied Physics 107, 083506 (2010)

Editorial: American Institute of Physics

 Fecha de publicación: 01/04/2010

Nº de páginas: 10

Tipo de publicación: Artículo de Revista

 DOI: 10.1063/1.3380848

ISSN: 0021-8979,1089-7550,1520-8850

Proyecto español: MAT2007-65990-C03-01/03

Url de la publicación: https://aip.scitation.org/doi/10.1063/1.3380848

Autores/as

RUIZ FUERTES, J.

LÓPEZ MORENO, S.

ERRANDONEA, D.

PELLICER PORRES, J.

LACOMBA PERALES, R.

SEGURA, A.

RODRÍGUEZ HERNÁNDEZ, P.

MUÑOZ, A.