Germanium at high pressures

Abstract

X-ray diffraction experiments have been carried out on germanium in a diamond anvil cell to 26 GPa. The pressure at the transition to the metallic phase (II) has been studied in different pressurizing media, giving 10.6\ifmmode\pm\else\textpm\fi{}0.05 GPa in a quasihydrostatic medium (4:1 methanol:ethanol mixture), 9.8\ifmmode\pm\else\textpm\fi{}0.1 GPa in NaCl, and 8.1\ifmmode\pm\else\textpm\fi{}0.3 GPA when the sample was compressed directly between the anvils. The compression curve for phase II has been fitted to a modified Murnaghan equation. Upon release of pressure the transformation from phase II to III (tetragonal) was found at 7.6\ifmmode\pm\else\textpm\fi{}0.05 GPa. It was found that the details of the transition depended on the stress condition and rate of decompression.