Phonon thermodynamics and elastic behavior of GaAs at high temperatures and pressures
Journal Article
·
· Physical Review B
- California Institute of Technology (CalTech), Pasadena, CA (United States); Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); University of Illinois at Chicago
- California Institute of Technology (CalTech), Pasadena, CA (United States)
The phonons of wurtzite and zinc blende GaAs were calculated at simultaneously elevated temperature and pressure, and elastic constants were calculated as functions of pressure. Pressure caused instabilities of shorter-wavelength transverse acoustic modes in both wurtzite and zinc blende GaAs, causing them to fall to zero at 18 and 20GPa, respectively. Here, the Born stability criteria, which depend on elastic constants and only long wavelength phonons, therefore overestimated the pressure needed to induce instability at 0 K. At elevated temperatures, explicit anharmonicity pushes the onset of instability to higher pressures in both wurtzite and zincblende GaAs. Phonon linewidth and densities of states data showed that the quasiharmonic approximation failed to account for temperature-induced phonon frequency shifts, and the quasiharmonic approximation became less reliable at elevated pressure. In general, the number of three-phonon processes increased with pressure, thereby increasing the temperature-driven broadening of phonon spectral lineshapes.
- Research Organization:
- Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States); Univ. of Illinois, Chicago, IL (United States)
- Sponsoring Organization:
- USDOE National Nuclear Security Administration (NNSA), Office of Defense Programs (DP); USDOE Office of Science (SC), Basic Energy Sciences (BES)
- Grant/Contract Number:
- AC52-07NA27344; FG02-03ER46055; NA0003975
- OSTI ID:
- 1712427
- Alternate ID(s):
- OSTI ID: 1729746
- Report Number(s):
- LLNL-JRNL--800378
- Journal Information:
- Physical Review B, Journal Name: Physical Review B Journal Issue: 21 Vol. 101; ISSN 2469-9950
- Publisher:
- American Physical Society (APS)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
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