Hydrogen absorption kinetics and mechanisms of rare earths (La, Ce, Pr, Nd, Tb, Dy) in the H2O surface reaction at room temperature

The quantitative reactivities of H2O and H2 gases with clean surfaces of rare earth (RE) metals La, Ce, Pr, Nd, Tb and Dy were measured volumetrically at 298 K as a function of the amount of reacted gas. The H2O reactivity was found higher by factors of 10–103 than the H2 reactivity, resulting in much higher rates of hydrogen (H) absorption of the metals than in H2 exposure. Quantitative data of reactivities of H2O and H2 with the metals are reported, and mechanisms of the H absorption of the RE metals in H2 and H2O exposures are discussed.