Ti-v Alloy Hydride Hydrogen Isotope Effect Studies

Three Titanium-Vanadium alloys , Ti₀.76V₀.24, Ti₀.51V₀.49 and Ti₀.25V₀.75, are prepared and their lattice parameters as well as their hydride lattice parameters are obtained. Thermodynamic and kinetic parameters of Hydrogen and Deuterium absorption , equilibrium H-D separation factors are also determined by researching thermodynamic , kinetic behavior and H-D separation of Hydrogen and Deuterium absorption. The isotope effects of Ti-V alloy- Hydrogen isotope systems are described by combining the theoretical calculation results.The conclusions that Ti-V alloy is a b.c.c structure with a=0.3141nm and its β phase hydride a f.c.c structure with a=0.4314nm are drew by XRD and theoretical calculation. It is found that Ti-V alloy has good stability and it does not decompose during Hydrogen and Deuterium absorption-desorption.The same results as from XRD are obtained from the p-c-T relationship of Hydrogen and Deuterium absorption. The α -β phase transition plateau of Hydrogen and Deuterium absorption takes place after c (ratio of H/(Ti+V)) reaches 1.0. While c is less than 1.0, the hydride of Ti-V alloy is still α phase, which the XRD pattern of the hydride is similar to that of Ti-V alloy, and Hydrogen and Deuterium absorption obey the Sievert's law. Thermodynamic parameters are separately calculated by the Sievert constant and Van't Hoff equations. In the range of c<1.0, the enthalpy values of Hydrogen and Deuterium absorption rise as the content of Ti in Ti-V alloys increase. But in the range of c>1.0, the enthalpy values of Hydrogen and Deuterium absorption reduce as the content of Ti in Ti-V alloys increase. Thermodynamic isotope effect for Hydrogen and Deuterium absorption of Ti-V alloy is not notable, but generally, at the same conditions, Deuterium equilibrium pressure is higher slightly than that of Hydrogen, presenting the hydride is more stable. The total energy, lattice structure and isotope effect of these Ti-V alloy- Hydrogen isotope systems are obtained by theoretical calculation, indicating that the hydride is more stable than the deudride and the deudride is more stable than the tridride by analyzing the total energy of every Ti-V alloy-Hydrogen isotope system.The measured kinetic curves show that Hydrogen or Deuterium absorption kinetics doesn't obey the classical equations of gas-solid reactions, and is influenced by temperature, time, pressure, composition of Hydrogen or Deuterium in Ti-V alloy. By induction, the kinetic equation and its application scope are as follows:The kinetic isotope effect is obvious. In comparison to Deuterium absorption, Hydrogen absorption shows a fast reaction rate, high rate constant and low apparent active energy. As result, Hydrogen condenses in solid phase, while Deuterium in gas phase.The equilibrium H-D separation factors for the three Ti-V alloys, determined by quadrupole mass spectrum, are all greater than 1.0, indicating that Hydrogencondenses in solid phase, while Deuterium in gas phase. Theoretical calculation, the p-c-T curves and kinetic investigation give the same results as equilibrium H-D separation factors that the stability is in the sequence hydride>deuteride>tritide.