Synchrotron X-ray diffraction study of phenacite at high pressure

We report the results of a natural phenacite from 0 to 30.9 GPa using in situ angle-dispersive X-ray diffraction and a diamond anvil cell at the National Synchrotron Light Source, Brookhaven National Laboratory. Over this pressure range, no phase change or disproportionation has been observed. The isothermal equation of state was determined. The values of V-0, K-0, and K-0' refined with a third-order Birch-Murnaghan equation of state are V-0=1116.1 +/- 1.2 angstrom(3), K-0=223 +/- 9 GPa, and K-0 '=5.5 +/- 0.8. Furthermore, we confirm that the linear compressibilities (beta) along a and c directions of phenacite are elastically isotropic (beta(a)=1.50 x 10(-3) and beta(c)=1.34 x 10(-3) GPa(-1)). Consequently, it can be concluded that the compressibility of phenacite under high pressures has been accurately constrained.