Thermodynamic and kinetic studies of Mg–Fe–H after mechanical milling followed by sintering

The transition metal complex hydride Mg₂FeH₆ has been successfully synthesized utilizing mechanical milling of a 2Mg-Fe mixture followed by heating at 673 K under 6 MPa of hydrogen pressure, without pressing step. The obtained yield of Mg₂FeH₆ was about 50%. Hydrogen storage properties of the Mg-Fe-H system, i.e. capacities, absorption/desorption kinetics and thermodynamic parameters, were examined. The pressure-composition isotherm (PCI) measurements of the samples at 548-673 K showed that the alloys possessed good cyclic stability and reversibility. Enthalpies and entropies of decomposition of the Mg-Fe-H system were evaluated by van’t Hoff plots. The absorption /desorption rates at 573 K were very fast in comparison with the reported data. The non-isothermal desorption of hydrogen was found greatly dependent on the thermal history of the sample.