Preservation dose of helium-implanted in nanocrystal titanium films

Helium concentration profile, preservation dose and release rate from a nanocrystal titanium film implanted with helium at different energy and dose have been measured by proton Rutherford backscattering technique in a range from room temperature to 500 degree C. It is observed that the implanted helium may be stably preserved for a long time in the nanocrystal titanium film in the temperature environment from room temperature to below 100 degree C when its concentration in up to 41%-52% of He-Ti atomic ratio, and also may be effectively preserved for a long time at room temperature if their atomic concentration ratio is up to 52%-74%. Possible mechanism of helium effectively preserved in the nanocrystal film with a large boundary volume ratio is preliminarily discussed from the energy viewpoint in this paper