Effect of mo content on the hydrogen isotope effect of Ti-Mo alloy hydrides

The alloys with various Mo content TiMox (x = 0.03, 0.13, 0.25, 0.50, 1.00, atomic ratio) were prepared with electromagnetic levitation technique. The alloys after activation reacted rapidly with H-D gas mixture (D%=50%), the composition of the mixture in equilibrium of isotope exchange was determined using a mass-spectroscopy. H-D separation factor α(H-D) was defined as([D] / [H])s/([D] / [H])g, in which [D] / [H]s refers to the atomic ratio of D and H in solid phase, and [D] / [H]g refers to the atomic ratio of D and H in gas phase. The results showed that at 20 degree C, x=0.03-1.00, α(H-D-) >1.00, D prefered to stay at solid phase, and the preference becomed stronger as the Mo content increases, with α(H-D) rising from 1.04 to 1.27. α(H-D) kept nearly unvaried when x=0.50-1.00.α(H-D)≅1.00 when x=0.03, namely TiMo0.03 hydride showed zero effect, through previous TG-DSC analysis results, the hydride contains TiH2 with negative effect, and Ti-Mo hydrides with positive effect, so it is the total effect of the two hydrides with oppositive effect. From the relationship between the Mo content and α(H-D), H atom prefers to take 4Ti tetrahedral interstice, whereas D atom tends to take 3Ti1Mo position in which the energy level is higher than that of 4Ti position. (authors)