Final Activity and Management Report Summary - POLYAMORPHIC SYSTEMS (High-pressure phase transitions inpolyamorphic systems of semiconducting elements)
Our results demonstrate that HDA form of Ge contains atoms in higher average coordination than the tetrahedrally-bonded LDA polyamorph. During compression the LDA-to-HDA transformation occurs at P app. 8-12 GPa, while a reverse transformation occurs between P app. 5.5-6.5 GPa indicating hysteresis characteristic for the first order-like transition as observed previously for a-Si at slightly higher pressure. We expect that the LDA-HDA transformation in amorphous Ge is linked to a density-driven liquid-to-liquid phase transition that is predicted theoretically to occur in the supercooled liquid state of Ge.