High-pressure Brillouin scattering of Pb(Mg1/3Nb2/3)O-3

The pressure dependencies of the elastic constants and bulk modulus of single crystal Pb(Mg1/3Nb2/3)O-3 (PMN) have been measured up to 10 GPa at room temperature by Brillouin spectroscopy. The elastic moduli and elastic anisotropy undergo an abrupt change at 4.5 GPa, indicative of a phase transition and consistent with earlier Raman and x-ray diffraction studies. We suggest that PMN undergoes a structural change from a cubic Pm3m to rhombohedral R3c phase at 4.5 GPa.