The formation and decomposition behaviors of BaAlH5 and Ba 2AlH7 were investigated by means of X-ray diffraction and pressure-composition isotherms (PCT). The phase transitions, phase compositions, and lattice parameters were determined by Rietveld refinement. Significantly pure BaAlH5 with a purity of 99.1% was obtained through hydriding of Ba4Al5 alloy at 100 °C under 5 MPa H2. When the hydrogenation temperature increased to 250 °C, the main phase became Ba2AlH7 with some impurity phases of BaAl4 and BaH2. PCT measurements of Ba4Al5 showed that the plateau pressure at 150 °C was about 0.5 MPa, and the maximum absorption H2 content was 2.15wt %. The final products obtained after PCT measurements of Ba4Al5 at 150 °C, 280 and 350 °C were BaAlH5, a mixture of Ba2AlH7, BaH 2 and BaAl4, a mixture of BaH2 and BaAl 4, respectively. Independent decomposition experiments showed that BaAlH5 partly desorbed H2 to form a mixture of BaAlH 5, Ba2AlH7, BaH2, and BaAl 4 at 280 °C, whereas both BaAlH5 and Ba 2AlH7 completely decomposed into BaH2 and BaAl4 at 350 °C.
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Physical and Theoretical Chemistry
- Surfaces, Coatings and Films