Generating gradient germanium nanostructures by shock-induced amorphization and crystallization
- Univ. of California, San Diego, CA (United States). Materials Science and Engineering Program
- Univ. of California, San Diego, CA (United States). Dept. of Structural Engineering
- Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
- Univ. of California, San Diego, CA (United States). Materials Science and Engineering Program; Univ. of California, San Diego, CA (United States). Dept. of Mechanical and Aerospace Engineering; Univ. of California, San Diego, CA (United States). Dept. of Nanoengineering
Gradient nanostructures are attracting considerable interest due to their potential to obtain superior structural and functional properties of materials. Applying powerful laser-driven shocks (stresses of up to one-third million atmospheres, or 33 gigapascals) to germanium, we report a complex gradient nanostructure consisting of, near the surface, nanocrystals with high density of nanotwins. Beyond there, the structure exhibits arrays of amorphous bands which are preceded by planar defects such as stacking faults generated by partial dislocations. At a lower shock stress, the surface region of the recovered target is completely amorphous. Here, we propose that germanium undergoes amorphization above a threshold stress and that the deformation-generated heat leads to nanocrystallization. These experiments are corroborated by molecular dynamics simulations which show that supersonic partial dislocation bursts play a role in triggering the crystalline-to-amorphous transition.
- Research Organization:
- Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States); Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States)
- Sponsoring Organization:
- USDOE National Nuclear Security Administration (NNSA), Office of Defense Nuclear Nonproliferation; USDOE Office of Science (SC), Basic Energy Sciences (BES). Scientific User Facilities Division
- Contributing Organization:
- Univ. of Rochester, NY (United States). Lab. for Laser Energetics
- Grant/Contract Number:
- AC05-00OR22725; 09-LR-06-118456-MEYM; NA0002930; LFR-17-449059; AC52-07NA27344; NA0002080
- OSTI ID:
- 1377093
- Alternate ID(s):
- OSTI ID: 1414697; OSTI ID: 1462273; OSTI ID: 1476238
- Report Number(s):
- DE-UCSD-NA0002080; LLNL-JRNL-741090
- Journal Information:
- Proceedings of the National Academy of Sciences of the United States of America, Vol. 114, Issue 37; ISSN 0027-8424
- Publisher:
- National Academy of Sciences, Washington, DC (United States)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
Web of Science
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