IN-SITU HIGH-PRESSURE AND HIGH-TEMPERATUR E STUDIES OF SILICON SUBOXIDES VIA ENERGY-DISPERSIVE X-RAY-DIFFRACTION

The amorphous silicon compounds Si2O3 H2Si2O4, HSiO1.5, and SiO have b een investigated under High-Pressure- and High-Temperature conditions insitu via energy dispersive X-ray diffraction with synchrotron radiat ion. The studies have been performed using the Multi Anvil High Pressu re Device MAX-80, at HASYLAB, DESY-Hamburg, Germany. Except for SiO, a t a pre-set pressure of 45 kbars the formation of Coesite was observed at heating. Commercially available SiO did not crystallize in any way , indicating that it seems not to consist of silicon(II)-oxide, but is in fact a mixture of silicon and silicondioxide, disproportionated on an atomic scale.