Comparison of models for multi-component hydrogen isotope mixtures absorbing in or permeating through metals

In the first place, dependences of isotope effects on temperature and compositions are discussed among hydrogen isotopes (H, D and T) absorbing in, diffusing or permeating through metals. Relation between the isotope effects and isotope separation factor is investigated when hydrogen isotope mixtures are absorbed in, diffuse or permeate through metals. Previous experimental results for the absorption of hydrogen isotopes in Pd or Li are correlated as a function of composition and temperature, and they are discussed based on several models proposed previously to explain the relation between the isotope effects and the isotope separation factor. It results in a fact that the ideal solution model with dissociation on metal surfaces can correlate most cases of absorption of hydrogen isotopes in Pd or Li. However, unresolved experimental results still remained that there is a quantitative difference in permeation rates when either H2 + D2 or H2 + D2 + HD mixture is supplied to the high-pressure side of a gaseous phase.