Crystal structure of the high-pressure monoclinic phase-II of cristobalite, SiO_2

摘要

The crystal structure of the high-pressure phase-II of cristobalite has been solved by neutron diffraction (space group P2_1/c, a =8.3780(11)A, b =4.6018(6)A, c =9.0568 (13)A, #beta# =124.949 (7) deg, at P =3.5 Gpa). This phase corresponds to a distortion of the high-temperature cubic #beta# -phase, rather than of the ambient temperature and pressure tetragonal #alpha#-phase.