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

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 GeI–GeII–GeL have been determined to a better degree of precision. The onsets of the GeI–GeII transition were found both under hydrostatic and non-hydrostatic conditions. Anisotropy of thermal expansion coefficient for the GeII is characterized from the c/a ratios in the temperature interval 473–823 K. Phases GeIII and GeIV are shown to be metastable forms of germanium.