Hydrogen and Deuterium Sorption Experiment of Metal Hydride Compound, TiMn_1.5 in Vacuum

Abstract

Pumping of hydrogen and deuterium gases by TiMn_1.5 was performed at pressures around 1.3 × 10² Pa (1 Torr). TiMn_1.5 was degassed at 550°C and hydrided at 1 atm at room temperature prior to the pumping experiment. TiMn_1.5 which had been exposed to the air for a long time required reduction of the oxidized surface by hydrogen at 550 °C. The average amount of absorbed hydrogen gas when equilibrium reached around 10² Pa (0.75 Torr) was about 4 Pa · m³ (30 Torr · l), and the corresponding hydrogen composition ratio (H/M) was 2.3 × 10^-2.
Heating of TiMn_1.5 to 400 °C made it to release almost all hydrogen and deuterium gases. From the thermal desorption spectra during dehydriding, the sorption mechanism of hydrogen and deuterium can be explained as the adsorption on segregated titanium surface instead of the solution into the bulk metal. The activation energies of H₂ and D₂ desorption are 27 and 25 kcal/mol respectively.