Change of Site Occupancy of Hydrogen in Nb on Alloying with Undersized Mo

抄録

The site occupancy of hydrogen in Nb--20 at.%Mo alloys is investigated at room temperature for H concentrations (C_H) 2.6, 4.2, and 8.0 at.% by a channelling method using a nuclear reaction ¹H(¹¹B}, α )α α . Different from previous results for lower Mo concentrations, a large portion of H atoms are at tetrahedral (T) sites and, in addition, the octahedral (O) site occupancy is newly observed. The hydrogen distribution changes with C_H. At C_H=2.6 and 4.2 at.%, the 20--30% of H atoms are located at O sites, while at C_H=8.0 at.% the fraction of the O-site occupancy remarkably decreases to 0--10%.