Annealing and relaxation in the high-pressure phase of amorphous SiO2.

In a recent article (Phys. Rev. Lett. 52, 2379 (1984)) it was reported that irreversible changes occur in the Brillouin spectra of a-italic-SiO/sub 2/ that has been subjected to pressures above --9 GPa. Based on Raman spectra from the recovered samples it was concluded that the new ''polymorph'' was also amorphous. Here we report on relaxation and annealing effects in this high-pressure form which leave no doubt as to its amorphous nature.