Three examples of disorder found in the averaged structures are presented. The crystal structure of high pressure form ZrO2determined at 5.1 GPa showed the disorder of oxygen positions separated by 1.22Å. The crystal structure of phase E synthesized at 15 GPa and 1000°C and quenched to the ambient condition showed that there exists short-range order between intralayer vacancies and interlayer cations but there does not exist a long-range order. The crystal structure of hydrous wadsleyite synthesized at 15.5 GPa and 1300°C and quenched to the ambient condition showed small but significant Fourier peaks at the site in a normally vacant tetrahedral void adjacent to Mg octahedral site.
