Surface modifications and deuterium depth profiles in molybdenum irradiated with low-energy D ions

Depth profiles of deuterium trapped in single crystal Mo, polycrystalline Mo, and molybdenum trioxide film on polycrystalline Mo irradiated with 200 eV D ions have been measured up to a depth of 8 μm using the D(3He,p)4He nuclear reaction at a 3He energy varied from 0.69 to 4.0 MeV. For the D ion irradiation at 323 K to the highest ion fluence of 5 × 1024 D/m2, the D concentration decreases from several at.% in the near-surface layer to bulk values below 10−4 at.% for single crystal Mo and about 10−2 at.% for polycrystalline Mo. The maximum D concentration in molybdenum trioxide film differs little in value from that for polycrystalline Mo. Blister formation at high fluences is observed for polycrystalline Mo and molybdenum trioxide film, but not for single crystal Mo. As the irradiation temperature increases from 323 to 493 K, the D retention in the polycrystalline Mo decreases from about 3 × 1021 down to about 2 × 1018 D/m2.