Raman scattering and x-ray-absorption spectroscopy in gallium nitride under high pressure

Abstract
Gallium nitride was studied by Raman scattering and x-ray-absorption spectroscopy up to 60 GPa. A high-pressure structural phase transition was observed in gallium nitride at 47 GPa by means of Raman scattering and x-ray-absorption spectroscopy. We also report the direct determination of the bulk modulus B0 of this compound (245 GPa). Grüneisen parameters of the four observed phonon modes were established. The transition pressure is compared with existing calculations.