Raman and X-Ray Investigations of Ice VII to 36.0 GPa

摘要

Raman data for ice VII to 30 GPa and x-ray lattice parameters to 36 GPa, all at room temperature, are presented and discussed. Both the Raman OH-stretching peak frequency (delta cap Nu) and the edge distance of the body-centered cubic unit cell (a) decrease at a decreasing rate with pressure rate. The OH peak frequency is found to be virtually linear in the nearest-neighbor 0-0 distance (r00) between about 2.5 and 2.9 A. However, the data can also be fitted with a slight cubic dependence, which when extrapolated, gives rise to a minimum in delta cap Nu at r00 = 2.35 plus or minus 0.06 A. This is close to the value of 2.4 A found for the symmetric O-H-O units in other materials. (Author)