A new high pressure phase of SiO2 formed by hydrostatic compression of cristobalite —Effect of non-hydrostatic stress on the crystal lattice

Cristobalite was compressed under various degree of hydrostaticity in this work. It was clarified that, under high pressure, non-hydrostatic stress affects the crystal structure of high pressure polymorph. A new polymorph of SiO2 was formed under quasi-hydrostatic compression of cristobalite. While the crystal structure of this new polymorph is very similar to that of rutile-type, lattice parameters are different from that of stishovite. No systematic study to clarify the effects of non-hydrostatic stress has ever been made. The effect of non-hydrostatic stress on the crystal lattice was discussed in this paper.