The incipient kinetics of hydride growth on cerium surfaces

摘要: Abstract The incipient hydriding stage of cerium is characterized by nucleation and growth the hydride phase on surface metal. kinetics this initial process were studied utilizing a hot-stage microscope (HSM) equipped with video camera. Growth velocities nuclei determined as function reaction temperature hydrogen pressure over grid temperatures pressures which enabled maintenance near isothermal conditions (25–100°C, 10–1000 mbar H 2 ). A linear dependence was obtained, temperature-dependent slopes. An Arrehenius plot these slopes yielded straight line apparent activation energy 6.3 kcal (g atomic H) −1 (0.27 eV). results compared those previously massive stage, where contracting envelope morphology hydride-metal boundary moving at constant (temperature-pressure dependent) velocity. Under similar experimental conditions, are significantly higher than corresponding stage. Different types controlling mechanism proposed to account for observed differences between stages.