Formation and crystal growth process of AlH3 in Al–H system

The hydrogenation process of aluminum is observed at high pressure and temperature by angle-dispersive in situ X-ray diffraction method. At 10 GPa and 600 °C, single crystals of AlH3 about 20 μm in size are found to grow through three steps: self-pulverization of aluminum, hydrogenation of pulverized aluminum, and solid-state grain growth of hydride. The self-pulverization seems to be the precursor of the hydrogenation reaction because it occurs at pressure temperature conditions where AlH3 is thermodynamically stable.