Thermal desorption of H from high-purity material was observed after heat treatment at 470 to 870K under a H pressure of 1.7GPa. A total of 0.1 to 1.5at% of trapped H, with the amount increasing at higher holding temperatures, was desorbed in 5 stages. The most prominent stage, at 400 to 440K, was identified with release from vacancy-H complexes of the form, vH6. The binding energy with a vacancy was estimated to be 44kJ/mol.

Superabundant Vacancy Formation in Iron under High Hydrogen Pressures: Thermal Desorption Spectroscopy. M.Iwamoto, Y.Fukai: Materials Transactions, 1999, 40[7], 606-11