Experimental and computational studies on tritium permeation mechanism in erbium oxide

Mao, W.*; Chikada, Takumi*; Suzuki, Akihiro*; Terai, Takayuki*; Yamaguchi, Kenji

A tritium permeation barrier (TPB) is strongly required in fusion blankets for the reduction of loss of fuel and radiological hazard. However, the precise tritium permeation mechanism through the TPB coatings has not been clarified yet, because of their complicated crystal structures. To understand the microscopic mechanism, we have not only prepared and characterized nanostructured ceramic ErO thin films, but also studied the energetics and mobility of hydrogen atom in cubic bulk ErO using ab initio density-functional calculations. The estimated diffusion activation energy () of interstitial H is somewhat higher than the diffusion energy barrier observed experimentally at 873 K. It is then considered that diffusion and permeation of hydrogen and its isotopes through the ErO coatings are likely to be dominated by the grain boundary rather than by the grain.