Stability investigation of the γ-MgH₂ phase synthesized by high-energy ball milling

Structural investigations showed that the crystal structure influences the hydrogen storage properties of MgH₂. The crystal structure and dehydriding temperature of MgH₂ activated by high energy ball milling under an argon atmosphere were studied. The X-ray diffraction characterization showed that a small amount of tetragonal α-MgH₂ phase transforms into crystalline γ-MgH₂ of an orthorhombic structure during milling, and γ-MgH₂ peak intensity increased with increasing ball milling time within a certain limit, but disappeared early in the hydrogenation cycle at a temperature of 300 °C. We studied the phase structure and the stability of the MgH₂ during absorption/desorption cycles as well as thermal stability in a context of sustainable use of MgH₂.