| About this Abstract |
| Meeting |
2024 TMS Annual Meeting & Exhibition
|
| Symposium
|
Accelerated Qualification of Nuclear Materials Integrating Experiments, Modeling, and Theories
|
| Presentation Title |
E-17: Superionic-like Diffusion in Yttrium Hydride |
| Author(s) |
Yuqing Huang, Jacob Eapen |
| On-Site Speaker (Planned) |
Yuqing Huang |
| Abstract Scope |
For the next generation of micro-reactors yttrium hydride (YH2) is a leading candidate for neutron moderation. Despite a number of recent investigations, the mechanism of hydrogen transport remains poorly understood. Experimental evaluation of diffusivity is inconclusive with notably different migration energies. In this work, we perform ab initio molecular dynamics simulations (AIMD) of YH2, spanning temperatures ranging from 300 K to 1200 K. Our main finding is that YH2 shows a superionic-type behavior with hydrogen atoms hopping from one native site to another above a critical temperature of 900 K. This correlated motion results in quasi-one-dimensional string-like displacements, which depict a temperature-dependent relaxation behavior. At the highest temperature of 1200 K, the relaxation time is mere of the order of a few picoseconds, which suggests that the diffusion process is strongly driven by the concerted string-like displacements. Hydrogen self-diffusivity follows an Arrhenius dependence with an activation energy of 0.83 eV. |
| Proceedings Inclusion? |
Planned: |
| Keywords |
Computational Materials Science & Engineering, Nuclear Materials, Modeling and Simulation |