  We study the effects of pressure on the structural, vibrational, and magnetic
behavior of cuproscheelite. We performed powder x-ray diffraction and Raman
spectroscopy experiments up to 27 GPa as well as ab initio total-energy and
lattice-dynamics calculations. Experiments provide evidence that a structural
phase transition takes place at 10 GPa from the low-pressure triclinic phase
(P-1) to a monoclinic wolframite-type structure (P2/c). Calculations confirmed
this finding and indicate that the phase transformation involves a change in
the magnetic order. In addition, the equation of state for the triclinic phase
is determined: V0 = 132.8(2) A3, B0 = 139 (6) GPa and = 4. Furthermore,
experiments under different stress conditions show that non-hydrostatic
stresses induce a second phase transition at 17 GPa and reduce the
compressibility of CuWO4, B0 = 171(6) GPa. The pressure dependence of all Raman
modes of the triclinic and high-pressure phases is also reported and discussed.
