The bulk diffusion constants of He in britholite (Ca9Nd(PO4)5(SiO4)F2) were deduced from non-destructive 3He depth profiling data by using the resonant 3He(d,p)4He nuclear reaction. Results were obtained from polycrystalline sintered ceramics implanted with 3MeV 3He+ ions to a depth of about 9μm and then annealed in air between 200 and 400C. The activation energy for He diffusion was around 1.1eV. These data were in good agreement with literature data based on ERDA depth profiling of 27keV 4He+ ions implanted in natural (Durango) or synthetic fluorapatite single crystals.

Nuclear Reaction Analysis of Helium Diffusion in Britholite. J.M.Costantini, P.Trocellier, J.Haussy, J.J.Grob: Nuclear Instruments and Methods in Physics Research Section B, 2002, 195[3-4], 400-7