Site Change of Hydrogen in Nb due to Interaction with Oxygen(Cross-disciplinary physics and related areas of science and technology)

概要

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To locate hydrogen in Nb alloyed with 0.3 at. % oxygen, which is the alloy system for the tunnelling motion of hydrogen to be observed, channelling experiments have been performed at room temperature utilizing a nuclear reaction ^1H(^<11>B, α)αα with a ^<11>B beam of about 2MeV. It has been demonstrated that for a hydrogen concentration of C_H = 0.003 (C_H = [H]/[M] ; hydrogen-to-metal-atom ratio), H atoms are located at sites displaced by 0.5-0.6 Å from tetrahedral (T) sites towards their nearest-neighbour lattice points, while for C_H = 0.019, most of the H atoms are located at T sites and the remains are at the same sites as those observed for CH = 0.003. This result indicates the trapping of hydrogen by oxygen and the formation of O-H pairs. The number of H atoms trapped by one O atom is approximately unity. As locations of the trapped hydrogen involved in the tunnelling motion, three types of displaced sites, which are described above, with the same separation of about 0.82 Å between neighbouring equivalent sites around O atoms are discussed.
社団法人日本物理学会の論文
2008-05-15