The Kinetic Isotope Effect On Thermal Desorption Of Ti-Mo Alloy Hydrides

The desorption kinetics of TiMox alloy deuterides with different Mo contents (x=0.03, 0.13, 0.25, 0.50, 1.00, atomic ratio) were studied in an ultra-high vacuum system by applying the constant volume method. The rate constant of desorption, kd, is calculated by first-order rate analysis; and the desorption activation energy, Ed, is obtained from the relationship lnkd vs 1000/T, and Ed is 46.6, 22.4, 13.7, 17.1, 10.4kJ.mol-1, respectively. To investigate the kinetic isotope effect of Ti-Mo alloy hydrides, Ed of the alloy protides is compared. When the Mo content is lower than 0.03, the activation energy for deuterium desorption is larger than the activation energy for protium desorption. When the Mo content is between 0.13 and 0.25, Ed for protium desorption is larger than Ed for deuterium desorption. And the Mo content is larger than 0.50, the kinetic isotope effect is not obvious. The nature of the kinetic isotope effect is explored through the stability of deuterides and protides at various temperatures.