Inverse hydrogen isotope effects in some metal hydride systems

Vanadium-based BCC alloys: phase-structural characteristics and hydrogen sorption properties

“…It is higher than isotopic effect recently reported [17] for the RECo 5 alloys (P D /P H = 2). A comparison with the performance of undoped vanadium ( [4]; P H /P D ∼3 at T = 40 • C) reveals two principal advantages of the materials studied in the present work. Firstly, we have not observed a significant difference between absorptiondesorption dynamics both for H 2 and D 2 , whereas the reaction of D 2 with pure vanadium is much slower compared to hydrogen.…”

“…Secondly, for the V 75 Ti 10 Zr 7.5 Ni 7.5 alloy the transition VH ∼2 ↔ VH ∼1 takes place at the same concentrations both for hydride and deuteride, and maximum sorption capacities are close in both cases. On the contrary, the ␥-deuteride on the basis of pure vanadium has much lower reversible sorption capacity than corresponding ␥-dihydride [4].…”

“…At the same time, the VH ∼2 ↔ VH ∼1 transition is characterised by an incline temperature dependence of hydrogen equilibrium pressure, associated with unusually high values of entropy and enthalpy of the formation of the dihydride [3]. In addition, this transition has a strong inverse isotopic effect [4].…”

Synthesis of the dihydride phase of vanadium

“…The temperature dependence of the separation factor α H−T for the vanadium-protium-tritium system plotted based on the data provided in Ref. [10] for the dihydride phase of vanadium takes the following form: log α H−T = 154.3/T − 0.284.…”

Hydrogen Isotope Effects on Absorption Properties of Ti-Cr-V Alloys

“…23) Vanadium is known to have large hydrogen isotope effects. 19,24) However, no hydrogen isotope effects of the Ti-Cr-V alloys were reported except for the works by Cho. 25,26) Therefore, the purpose of this study is to clarify the hydrogen isotope effects on the absorption properties of the Ti-Cr-V alloys in a composition range near the boundary between the appearance regions of the mono-and di-protides.…”