| Autor: |
Ashley Williams, Kien Nguyen Cong, Nir Goldman, Ivan Oleynik, Jonathan Willman |
| Rok vydání: |
2020 |
| Předmět: |
|
| Zdroj: |
SHOCK COMPRESSION OF CONDENSED MATTER - 2019: Proceedings of the Conference of the American Physical Society Topical Group on Shock Compression of Condensed Matter. |
| ISSN: |
0094-243X |
| Popis: |
Carbon exhibits a relatively simple phase diagram under hydrostatic compression: thermodynamically stable sp2– bonded graphite and metastable sp3–bonded cubic diamond at ambient conditions. The diamond phase is the only phase which exists at high pressures up to 1 TPa, followed by bc8 and simple cubic phases at high pressures above 1 TPa. There have been reports of appearance of hexagonal phase of diamond in shock experiments, but these results have been questioned by interpreting associated diffraction peaks as deformation twinning on planes as a result of plastic deformations in cubic diamond. We explore unknown metastable phases of carbon under both hydrostatic and uniaxial compressions by using combination of first- principles density functional theory and evolutionary crystal structure prediction. Shear stresses are dominant at shock-induced uniaxial compressions and play a key role in transforming diamond to new lower energy metastable phases. The appearance of these phases provides a plausible interpretation of recent experimental observations. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
|
