| Abstract |
The high-pressure behavior of SiO2 glass has attracted considerable attention because of its importance not only in geophysics but also in condensed-matter physics and materials science. By analogy with crystalline equivalents, the structural transformation of SiO2 glass in short-range order, i.e. the change in the coordination number from four to six, is expected to occur at high pressures. We have developed synchrotron x-ray absorption and diffraction techniques for measuring the density and structure of noncrystalline materials at high pressures and have applied them to studying the behavior of SiO2 glass. SiO2 glass transformed from a fourfold- to a sixfold-coordinated structure at pressures between 20 GPa and 35-45 GPa, and then behaved as an amorphous polymorph having a sixfold-coordinated structure at least up to 100 GPa. |
