Ceramics and Glasses Simulations and Machine Learning: Poster Session
Sponsored by: ACerS Glass & Optical Materials Division
Program Organizers: Mathieu Bauchy, University of California, Los Angeles; Peter Kroll, University of Texas at Arlington; N. M. Anoop Krishnan, Indian Institute of Technology Delhi
Tuesday 9:00 AM
November 3, 2020
Room: Poster Hall
Location: MS&T Virtual
Defect Formation and Self-diffusion in Alumina: Computational Approaches: Andy Chen1; Michael Finnis2; Arthur Heuer1; 1Case Western Reserve University; 2Imperial College London
The introduction of minute concentrations of dopants in alumina (α-Al2O3) has shown to affect oxygen and aluminum self-diffusion rates significantly. This process has demonstrated remarkable utility in the case of high-temperature aluminum-rich Fe-based and Ni-based alloys, where the introduction of reactive elements (Y, Hf, and Zr, among others) suppresses the rate of growth of alumina scales during oxidation, thereby improving oxidation resistance of the alloy. The mechanism linking dopant concentration and self-diffusion rates, however, is poorly understood in alumina, and experimental figures of vacancy concentrations remain incommensurate with computational results for both polycrystalline and single-crystal frameworks (as in the “Corundum Conundrum”). In this study, we review established theory and recently-developed computational methods for vacancy analysis, and test the hypothesis that the use of density functional theory-Hartree-Fock (DFT-HF) hybrid functionals might be able to bridge the gap we currently see between theory and experiment.
Verification of Mn Local Structure in Manganese Lithium Borate-based Glass by Computer Simulations and X-ray Absorption Spectroscopy: Pattarapong Nijapai1; 1School of Physics, Suranaree University of Technology
The structure of 0.2MnO2 – 0.8(Li2O-2B2O3) manganese lithium borate-based glass was simulated using molecular dynamic (MD) and refined by Reverse Monte Carlo (RMC) method. DL_POLY MD package based on Buckingham potential parameter was employed to calculate the glass structure. Parameters obtained from Mn K-edge Extended X-ray Absorption Fine Structure (EXAFS) measurement of real glass sample were used in RMC calculation with RMC++ package for the glass structure refinement. To verify the Mn local structure, X-ray Absorption Near Edge Structure (XANES) measurement result of Mn K-edge was compared with the calculated spectra using the computer-simulated structures. A good agreement between calculated and measured data was obtained leading to a full address of Mn local structure in this glass that resides in mixed terahedral/octrahedral configuration with a mean Mn-O coordination network of 3.49(2) and an interatomic distance of 2.08(2) Å.