SYNTHESIS OF FINE COMPOSITE-PARTICLES FOR HYDROGEN STORAGE, STARTING FROM MG-YNI2 MIXTURE

We synthesized new composite particles for hydrogen storage on the bas is of an idea of ''particle designing''. As starting materials, powder s of Mg and YNi2 were selected. Fine composite particles containing ma inly Mg2Ni could be designed by repetitive hydriding and dehydriding c ycles at 673 K. In the synthesis process of the composite particles, t he following two points were found to be essential for this technique. The first point is that, after being activated by the sequential proc esses of hydrogenation, amorphization and disproportionation, YNi2 rea cts effectively with Mg. The second point is that evaporated Mg, which occurs during dehydriding, adheres to the surface of the activated YN i2 and accelerates a diffusion reaction to form Mg2Ni at the interface . In these composite particles, Mg2NiH4 is formed, even at 373 K, unde r a hydrogen pressure of 5 MPa.