Catalytic effect of mixed Zr-Fe additives on the hydrogen desorption kinetics of MgH2

Mg films containing Fe-Zr mixed additives were prepared by rf sputtering and their hydrogen sorption kinetic was studied by Sievert technique. We observed that mixed Fe-Zr additives improve the H(2) desorption kinetics better than singly Fe or Zr. X-ray diffraction analysis evidences that mixed additives optimize the Fe distribution that forms smaller clusters than in Mg sample with single Fe catalyst. The presence of mixed additives, with Fe having larger diffusivity than Zr, contributes to maintain the atomic Zr dispersion in the Mg matrix, thus, favoring the presence of a greater number of nucleation sites for MgH(2) to Mg transformation. (c) 2008 American Institute of Physics.