High-pressure Phases (hex-Si, hex-Ge, hex-diamond) Formed by Use of Laser Ablation

Silicon and germanium are most likely to form cubic phases under normal equilibrium conditions. At high pressures, Si or Ge may possess other crystallographic symmetries. Using laser ablation technique we were able to grow stable phases seen only at very high pressures (~10 GPa).

(a) Hexagonal-Si (hex-Si) crystal. (b) and (c) Electronic diffraction patterns from hex-Si. (d) Electronic diffraction pattern from cubic-Si (c-Si).