||In this research, aluminum hydride (AlH3) was synthesized by wet chemical precipitation method in the glovebox. Single phase α-AlH3, single phase γ-AlH3, and β-AlH3 coexisting with other phases were obtained. All of polymorphs consist of packs of crystalline lamenae.|
For α and γ polymorphs, x-ray diffraction pattern, IR absorption spectra and thermal properties all have great agreement with literature. In Situ FTIR was used and analyzed by 2D IR to observe the behaviors of phase transition and decomposition. It turned out that for α-AlH3, decomposition was observed by the form of rising baseline. For γ polymorph, two decomposition routes were observed. It transformed to α polymorph followed by decomposition, or it decomposed directly from γ polymorph. The former rout occurred prior to the latter, whereas no region that α polymorph dominating was observed. Stable wise, α polymorph exhibits better stability than γ polymorph.
Stabilization achieved by doping and surface treatment was introduced to further enhance the stability of α-AlH3. Doped by Mg, Td of AlH3 increased at most to 191 °C. Otherwise, surface treatment via HCl acid wash workshop had a promising effect on enhancing the stability in the air.