BETA-PO PHASE OF SULFUR AT 162 GPA - X-RAY-DIFFRACTION STUDY TO 212 GPA

Using diamond anvil cell techniques and powerful synchrotron sources, we carried out an energy dispersive x-ray diffraction study on sulfur to 212 GPa and detected a transition to a new phase at 162+/-5 GPa. This new phase has been indexed as the beta-Po structure based on agreement with the d spacings and the measured diffraction peaks. This is consistent with the published results on high pressure phases of Se and Te. The Raman spectra of the fully recovered sulfur indicate permanent changes in the molecular structure. This paper represents the first experimental results in which a structural determination has been made for the low-atomic-number materials above 100 GPa.