Synthesis and hydrogen storage behaviour of pure Mg2FeH 6at nanoscale

Pure Mg2FeH6 compounds with two different morphologies have been successfully synthesized directly by mechanical milling (MM) and sintering of a mixture of 2Mg+Fe nanoparticles under an H2 atmosphere, respectively. The successful preparation of pure Mg 2FeH6 can be attributed to the small particle sizes of Mg and Fe nanoparticles prepared by hydrogen plasma-metal reaction (HPMR), which provides shorter diffusion distance for hydrogen and the metals. The X-ray diffraction (XRD) and scanning electron microscopy (SEM) results show that the Mg2FeH6 synthesized by mechanical milling has larger particle size but smaller crystallite size compared with the Mg 2FeH6 synthesized by sintering. The Mg2FeH 6 synthesized by mechanical milling can desorb more than 4.5mass% hydrogen in 10 min under an initial hydrogen pressure of 0.001 bar at 573 K. Compared with the Mg2FeH6 synthesized by sintering under the same conditions as the Mg2FeH6 synthesized by mechanical milling, it is suggested that decrease of crystallite size is beneficial for enhancing desorption property of Mg2FeH6. ?2011 The Japan Institute of Metals.EI4618-6225