High-pressure Raman study of Al2(WO4)3

A high-pressure Raman scattering study of the tungstate Al-2(WO4)(3) is presented. This study showed the onset of two reversible phase transitions at 0.28 +/- 0.07 and 2.8 +/- 0.1 GPa. The pressure evolution of Raman bands provides strong evidences that both the transitions involve rotations/tilts of nearly rigid tungstate tetrahedra and that the structure of the stable phase in the 0.28-2.8 GPa range may be the same as the structure of the ambient pressure, low-temperature monoclinic (C-2h(5)), ferroelastic phase of Al-2(WO4)(3). (C) 2004 Elsevier Inc. All rights reserved.