Modeling of Tritium Permeation Through Erbium Oxide Coatings

Tritium permeation through erbium oxide coatings has been modeled on the basis of experimental results. Permeation models were constructed step-by-step by the introduction of the following predominant parameters: surface coverage, grain size, and energy barrier. The surface-coverage model agreed with the imperfectly coated samples fabricated by filtered arc deposition as well as by metal-organic decomposition. The grain-boundary-diffusion model also agreed with the coatings fabricated by filtered arc deposition, though it was not applicable to the metal-organic decomposition coatings because of impurities and different layer structures. The energy-barrier model explains the contributions to the additional permeation reduction of the multilayer coatings. The discussion of permeation models provides new design concepts for the development of tritium permeation barriers.