HIGH-PRESSURE X-RAY-DIFFRACTION OF SR-3(VO4)(2) AND BA-3(VO4)(2)

High-pressure behavior of Sr-3(VO4)(2) and Ba-3(VO4)(2) is investigate d with energy-dispersive X-ray diffraction up to 27.0 and 29.0 GPa, re spectively. For Sr-3(VO4)(2) (R (3) over bar m); there occurs a phase transition to an orthorhombic structure in the 13.8-17.0 GPa pressure range. Ba-3(VO4)(2) (R (3) over bar m) does not undergo any structural transformation up to 29.0 GPa. The systematic high pressure behavior in the Ca-3(VO4)(2) (R3c), Sr-3(VO4)(2), and Ba-3(VO4)(2) series is di scussed. (C) 1998 Elsevier Science B.V. All rights reserved.