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Title: Density functional theory and evolution algorithm calculations of elastic properties of AlON

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.
Authors:
; ; ;  [1]
  1. U.S. Army Research Laboratory, Aberdeen Proving Ground, Maryland 21005 (United States)
Publication Date:
OSTI Identifier:
22271274
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 115; Journal Issue: 2; Other Information: (c) 2014 U.S. Government; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, 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