Hydrogen up-take in noble gas implanted W

Hydrogen accumulation in W crystal surface irradiated by noble gas ions was studied in connection with morphological and compositional changes. Noble gas ions such as He, Ne, Ar, Kr and Xe were implanted into W single crystals with energies of 10-380 keV up to doses of about 2 x 1022 ions/m2 at room temperature. Remarkable hydrogen retention was found for the He and Xe ion implanted layers where blisters and exfoliation were created. Tungsten oxides such as WO2 were formed along projected ranges of the implanted ions. Results indicated that the porous oxide surface layers play important role for dissociation of hydrogen, and hydrogen trapping is correlated with microstructural changes owing to formation of bubbles or clusters of implanted noble gas atoms