Phase transformations in the TiO₂–SiO₂ system at high pressures and temperatures

Abstract

In situ X-ray diffraction study of a sol–gel-produced SiO₂–TiO₂ glass and intimately mixed ultrafine powders of SiO₂ and TiO₂ was used to investigate the effect of TiO₂ on the high-pressure phase transformations of SiO₂ and specifically on the change in the p,T-conditions of the formation of coesite and stishovite. Our findings have shown that at pressures to 7.5 GPa and temperatures up to 1300 K the presence of TiO₂ does not favor the formation of stishovite.

^†On leave from the Institute for Superhard Materials, Kiev, Ukraine.

Keywords:

• High-pressure–high-temperature phase transformations
• Multianvil X-ray system
• Geological compounds
• Sol–gel
• Mixture powder

The authors thank Dr. Ch. Lathe for assistance in high-pressure experiments. This work was supported by the GFZ-Potsdam under the MAX80 program.

Notes

^†On leave from the Institute for Superhard Materials, Kiev, Ukraine.

¹(P ₃ = 1 − γ), where γ is the concentration of turbostratic stacking faults, calculated following the procedure [17].