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Y. Yahagi, T. Tagi, H. Yamawaki, K. Aoki
[Solid State Commun., 89, pp. 945-948, 1994]
Infrared spectra of three high-pressure phases of low-cristabolite, cristabolite II (1.5-10 GPa), X-I phase (10-40 GPa) and X-III which was quenched from the pressure above 40 GPa, were obtained in the spectrum range from 400-1400 cm-1 at room temperature. The frequency and relative intensity of Si-O stretching mode observed for the three high-pressure phases were compared with those of the other known silica polymorphs. It was concluded that those phases are dominant with four-fold silicon atoms.