Densified Amorphous Precursors Yield New Pathway to Exotic Form of Silicon

December 15, 2025
Diamond anvil techniques (left) allow experimental tuning of density. In situ diffraction data (right) show the direct crystallization of R8 from amorphous silicon at ~8 GPa

Scientific Achievement

By tuning the density of amorphous forms, a new synthetic route to the exotic “R8” phase of silicon and germanium was discovered.

 

Significance and Impact

The R8 form of silicon has technologically impactful electronic properties. The newly discovered pathway to its formation lowers formation pressure by 25% and may be applicable to other systems including carbon. 

Research Details

  • In situ high-pressure diffraction studies used neutrons (SNS) and synchrotron x-rays (Advanced Photon Source).
  • Molecular dynamics simulations (ORNL). 

 

“Pressure-driven density match nucleates metastable r8 phases from amorphous Si and Ge,” Materials Today 89, 140-149 (2025) 
https://doi-org.ornl.idm.oclc.org/10.1016/j.mattod.2025.08.002