In situ X-ray diffraction study of germanium at pressures up to 11 GPa and temperatures up to 950 K

Abstract

In situ X-ray diffraction measurements on germanium were conducted in the pressure range of 5–11 GPa and temperatures up to 950 K. Using our data a better defined P–T diagram for germanium is presented. The coordinates of the triple point between Ge I–Ge II–Ge L have been determined to a better degree of precision. The onsets of the Ge I–Ge II transition were found both under hydrostatic and non-hydrostatic conditions. Anisotropy of thermal expansion coefficient for the Ge II is characterized from the c/ a ratios in the temperature interval 473–823 K. Phases Ge III and Ge IV are shown to be metastable forms of germanium.