Formation of metastable bc8 phase from crystalline Si0.5Ge0.5 by high-pressure torsion

Yoshifumi Ikoma, Terumasa Yamasaki, Takahiro Shimizu, Marina Takaira, Masamichi Kohno, Qixin Guo, Martha R. McCartney, David J. Smith, Yasutomo Arai, Zenji Horita

Research output: Contribution to journalArticlepeer-review

8 Scopus citations


Si0.5Ge0.5 crystals were subjected to severe plastic deformation using high-pressure torsion (HPT). A metastable body-centered-cubic phase having a bc8 structure was formed by HPT processing with anvil rotations. High-resolution transmission electron microscopy analysis revealed that nanograins having diamond-cubic (dc) and bc8 phases were present in the HPT-processed sample. The bc8 phase was reverse transformed back to the dc phase after annealing. The resistivity of the crystalline Si0.5Ge0.5 (~9 × 10−3 Ω·cm) increased by roughly a factor of 6 after compression, and remained on the same order of magnitude but decreased slightly after 10 anvil rotations despite the grain refinement. These results indicate that the electrical behavior of bc8-Si0.5Ge0.5 is similar to that of bc8-Si.

Original languageEnglish (US)
Article number110590
JournalMaterials Characterization
StatePublished - Nov 2020


  • High-pressure torsion
  • Metastable phase
  • Phase transformations
  • Semiconductors
  • Severe plastic deformation

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering


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