Immaphase of germanium at ∼80 GPa

Ge has been studied to 81 GPa with angle-dispersive diffraction techniques, using an image-plate area detector and high-brilliance synchrotron radiation from the European Synchrotron Radiation Facility. A previously unknown phase of Ge, with orthorhombic symmetry Imma, is found to exist above ∼75 GPa—between the well established $\beta$-tin and simple hexagonal phases. This phase is the same as that found recently between the $\beta$-tin and simple hexagonal phases of Si.