Hydrogenation of anodized aluminum and crystal growth of formed hydride at high pressure and high temperature

Abstract

Anodized aluminum samples with different surface oxide layer thicknesses (approximately 0.3 and 3 μm) were hydrogenated at 9 GPa and 600°C for 24 h. A few large crystals of AlH3, of which average crystal size was 30 μm, were formed when the aluminum sample with the thicker oxide layer was hydrogenated, whereas the sample with the thinner oxide layer was uniformly hydrogenated to form AlH3crystals 10μm in particle size. It is likely that the surface oxide layer inhibits not only the hydrogenation reaction of aluminum but also the spontaneous nucleation of AlH3, which causes the difference between the formed crystal sizes.