Energy Dissipation and Defect Generation for Nanocrystalline Silicon Carbide

Journal Article · Wed May 05 04:00:00 EDT 2010 · Physical Review. B, Condensed Matter and Materials Physics, 81(18):Article No.184101

DOI:https://doi.org/10.1103/PhysRevB.81.184101· OSTI ID:982943

Gao, Fei; Chen, Dong; Hu, Wangyu; Weber, William J

Large-scale molecular dynamics simulations have been employed to study defect generation and primary damage state in nano crystalline (NC) SiC of average grain diameters from 5 to 21 nm. Primary knock-on atom (PKA) kinetic energies of 10 keV are simulated, and cascade structures in NC SiC with a grain size smaller than 12 nm are generally different from those generated in single crystalline SiC. It is found that the local stresses near the grain boundaries (GBs) strongly affect the behavior of the PKA and secondary recoil atoms (SRAs), and the GBs act as sinks for deposition of kinetic energy. A striking feature is that the PKA and SRAs preferentially deposit energy along the GBs for grains with average size less 12 nm, which results in atomic displacements primarily within the GBs; whereas for larger grain sizes, most defects are produced within the grains. There exists a crossover in defect production, which is manifested in switching from grain boundary damage to grain damage. The most common defects created in NC SiC are antisite defects, following by vacancies and interstitials, in contrast to those produced in a single crystalline SiC, where the dominate defects are Frenkel pairs. Defect production efficiency increases with increasing the grain size, with a typical value of 0.18 for small grains and rising to 0.5 for larger grains.

• Research Organization: Pacific Northwest National Laboratory (PNNL), Richland, WA (US), Environmental Molecular Sciences Laboratory (EMSL)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC05-76RL01830
• OSTI ID: 982943
• Report Number(s): PNNL-SA-72240; 34899; KC0201020
• Journal Information: Physical Review. B, Condensed Matter and Materials Physics, 81(18):Article No.184101, Journal Name: Physical Review. B, Condensed Matter and Materials Physics, 81(18):Article No.184101 Journal Issue: 18 Vol. 81
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ATOMIC DISPLACEMENTS
ATOMS
Computer Simulations
DEFECTS
DEPOSITION
EFFICIENCY
ENERGY LOSSES
Environmental Molecular Sciences Laboratory
GRAIN BOUNDARIES
GRAIN SIZE
INTERSTITIALS
Irradiation Effects
KINETIC ENERGY
KINETICS
KNOCK-ON
Nanograins
PRODUCTION
SILICON CARBIDES
STRESSES
Silicon Carbide
VACANCIES