|Título||Compression mechanism and pressure-induced amorphization of [upsilon]-ZrW/sub 2/O/sub 8/
Figueiredo, Camila Araújo de
Zorzi, Janete Eunice
Souza, Leonardo Salvador
Baumvol, Israel Jacob Rabin
Gallas, Marcia Russman
Jornada, Joao Alziro Herz da
Perottoni, Claudio Antonio
|Abstract||The structure of [upsilon]-ZrW2O8 has been optimized at zero pressure and also at V/V0=0.97 by means of density functional theory calculations using the B3LYP functional. As previously found for [upsilon]-ZrW2O8, tungsten polyhedra are stiffer than zirconium octahedra in -ZrW2O8. However, contrary to what has been found for [upsilon]-ZrW2O8, all first coordination polyhedra in the phase are less compressible than the unit cell. Volume reduction in [upsilon]-ZrW2O8 is, thus, mainly accomplished by polyhedral tilting. Upon pressure increase, the distance between the terminal oxygen and W atoms from the nearest polyhedra decreases by as much as 3.66% for the pair O101-W6 . Accordingly, a further reduction in the zirconium tungstate molar volume with the high-pressure transition to the amorphous phase should bring several oxygen atoms within the threshold of bond formation to W. O 1s photoelectron spectra provide further experimental evidence on the formation of additional W-O bonds in amorphous zirconium tungstate. These new W-O bonds should enable the metastable retention of the amorphous phase upon pressure release.
|Contido em||Physical review. B, Condensed matter and materials physics. Woodbury. Vol. 76, no. 18 (Nov. 2007), 184201 7p.
Física da matéria condensada
|Tipo||Artigo de periódico
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