Atomic scale mobility of the volatile fission products Xe, Kr and I in cubic SiC

The migration barriers for the vacancy-assisted migration of fission products in 3C-SiC are reported and analysed in the context of the five frequency model, which enables one to calculate an effective diffusion coefficient from elementary mechanisms. Calculations were carried out using the nudged e...

Full description

Saved in:
Bibliographic Details
Published in:Physical chemistry chemical physics : PCCP 2016-06, Vol.18 (25), p.1692-16911
Main Authors: Cooper, M. W. D, Kelly, S, Bertolus, M
Format: Article
Language:English
Subjects:
Accommodation
Activation energy
Carbon
Fission products
Mathematical models
Migration
Nuclear Experiment
Nuclear Theory
Physics
Silicon carbide
Vacancies
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:The migration barriers for the vacancy-assisted migration of fission products in 3C-SiC are reported and analysed in the context of the five frequency model, which enables one to calculate an effective diffusion coefficient from elementary mechanisms. Calculations were carried out using the nudged elastic band method (NEB) with interatomic forces determined from density functional theory (DFT). Justification for treating vacancy-assisted fission product migration as limited to the FCC carbon sublattice is based on the stability of carbon vacancies, unfavourable silicon vacancy formation and the accommodation of fission products on the carbon sublattice. Results show that for most Fermi levels within the band gap the activation energy for I exceeds that of Xe which exceeds that of Kr. Results also indicate that activation energies are higher near the conduction edge, thus, implying that enhanced fission product retention can be achieved through n-type doping of 3C-SiC, which limits the availability of the migration mediating carbon vacancies. The migration barriers for the vacancy-assisted migration of fission products in 3C-SiC are reported and analysed in the context of the five frequency model, which enables one to calculate an effective diffusion coefficient from elementary mechanisms.
ISSN:1463-9076
1463-9084
DOI:10.1039/c6cp01567k