Molecular dynamics study of hydrogen isotopes at the Be/BeO interface

Area of Science:

• Materials Science
• Computational Materials Science
• Nuclear Engineering

Background:

• Beryllium (Be) and beryllium oxide (BeO) are crucial materials in fusion energy applications.
• Understanding deuterium (D) behavior at Be/BeO interfaces is vital for predicting fuel retention and permeation.
• Previous studies lack detailed atomic-level insights into D-interface interactions.

Purpose of the Study:

• To investigate the behavior and migration of deuterium (D) atoms at beryllium (Be) and beryllium oxide (BeO) interfaces using molecular dynamics simulations.
• To identify factors influencing D atom trapping and diffusion kinetics at these interfaces.
• To assess the implications of D-interface interactions on fuel retention in Be-containing fusion reactor components.

Main Methods:

• Utilized molecular dynamics (MD) simulations to model D atom behavior at Be/BeO interfaces.
• Simulations were conducted at temperatures ranging from 750 K to 1500 K for durations of tens to hundreds of nanoseconds.
• Analyzed interface structures, including localized defects and hexagonal misfit dislocation networks, and their effect on D atom distribution and migration.

Main Results:

• Both Be/BeO interfaces were identified as significant trapping sites for D atoms.
• D atoms preferentially migrate towards regions with higher solubility, aligning with thermodynamic predictions.
• Observed kinetic barriers, such as D trapping sites and D2 formation/dissociation in BeO, significantly slow the approach to equilibrium.

Conclusions:

• The Be/BeO interfaces act as effective traps for deuterium, influencing its distribution within the material.
• While thermodynamics guides D solubility, kinetic factors like trapping and dissociation present additional barriers to diffusion.
• These kinetic barriers are critical for understanding and modeling fuel retention and permeation in beryllium-based materials for fusion applications.