| About this Abstract |
| Meeting |
2024 TMS Annual Meeting & Exhibition
|
| Symposium
|
Accelerated Qualification of Nuclear Materials Integrating Experiments, Modeling, and Theories
|
| Presentation Title |
E-6: Fundamental Surface Reconstruction and Formation of Phyllosilicate Waste Barrier Materials |
| Author(s) |
An Tien Ta, R. Seaton Ullberg, Simon Phillpot |
| On-Site Speaker (Planned) |
An Tien Ta |
| Abstract Scope |
Phyllosilicate materials (e.g., smectite) have been proposed to act as a waste barrier within long-term geological repositories for their ability to swell and sequester radionuclides. Sequestration of problematic radionuclides like iodine-129 and technetium-99 is achieved through intermolecular interactions involving clay basal planes and edge surfaces. Here we characterize the structures and energetics of dehydrated clay edges via Density Functional Theory (DFT). Using pyrophyllite as a representative model for phyllosilicates, thirteen terminations were considered in the context of reconstruction, charge distribution, and formation energies. The following primary reconstruction mechanisms were observed and will be presented on and discussed herein: (1) Al displacement, (2) proton shift, and (3) sub-surface reconstruction. DFT calculations revealed that charge distribution and relative bond deficiency were the main driving forces. Using a machine learning approach, the key physical mechanisms that determine the surface energies were also determined. |
| Proceedings Inclusion? |
Planned: |
| Keywords |
Computational Materials Science & Engineering, Modeling and Simulation, Sustainability |