Structural and magnetic properties of rare earth-transition metal compounds for hydrogen storage materials

In this work we investigate the effect of hydrogen absorption/desorption at 0 and 25 ° C on the structural, magnetic and microstructural characteristics of bulk samples with Sm(Co0.6Fe0.2Zr0.16B0.04)7.5 and Sm(Co0.74Fe0.1Cu0.12Zr0.04)8 stoichiometries. The B-doped sample absorbs 0.8 wt.% at room temperature under 15 bar of hydrogen pressure while the B-free one absorbs less than 0.01 wt.% under the same conditions. The B-free bulk sample has Hc=1.5  kOe while after hydrogenation this value increases slightly. Hydrogenation of the B-free bulk sample results in stronger dipolar interactions between the hard grains, as revealed from δM plots. SEM with EDAX was used in order to examine the composition and surface morphology of bulk samples.