Raman and x-ray diffraction investigations on BaMoO4under high pressures

X-ray diffraction and Raman scattering studies on the scheelite structured barium molybdate show that, at ∼5.8 GPa, it undergoes a first order phase transition to the fergusonite structure (I 2/a,Z = 4)-as also observed in iso-structural barium tungstate. At still higher pressures, barium molybdate transforms to another phase between ∼7.2 and 9.5 GPa. On release of pressure from 15.8 GPa, the initial phase is recovered, implying that the observed structural modifications are reversible.