Density functional theory and evolution algorithm calculations of elastic properties of AlON
- U.S. Army Research Laboratory, Aberdeen Proving Ground, Maryland 21005 (United States)
Different models for aluminum oxynitride (AlON) were calculated using density functional theory and optimized using an evolutionary algorithm. Evolutionary algorithm and density functional theory (DFT) calculations starting from several models of AlON with different Al or O vacancy locations and different positions for the N atoms relative to the vacancy were carried out. The results show that the constant anion model [McCauley et al., J. Eur. Ceram. Soc. 29(2), 223 (2009)] with a random distribution of N atoms not adjacent to the Al vacancy has the lowest energy configuration. The lowest energy structure is in a reasonable agreement with experimental X-ray diffraction spectra. The optimized structure of a 55 atom unit cell was used to construct 220 and 440 atom models for simulation cells using DFT with a Gaussian basis set. Cubic elastic constant predictions were found to approach the experimentally determined AlON single crystal elastic constants as the model size increased from 55 to 440 atoms. The pressure dependence of the elastic constants found from simulated stress-strain relations were in overall agreement with experimental measurements of polycrystalline and single crystal AlON. Calculated IR intensity and Raman spectra are compared with available experimental data.
- OSTI ID:
- 22271274
- Journal Information:
- Journal of Applied Physics, Vol. 115, Issue 2; Other Information: (c) 2014 U.S. Government; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-8979
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ALGORITHMS
ALUMINIUM NITRIDES
ATOMS
COMPARATIVE EVALUATIONS
COMPUTERIZED SIMULATION
DENSITY FUNCTIONAL METHOD
ELASTICITY
MONOCRYSTALS
OXYGEN COMPOUNDS
POLYCRYSTALS
PRESSURE DEPENDENCE
RAMAN SPECTRA
STRAINS
STRESSES
VACANCIES
X-RAY DIFFRACTION