Hydrogenation of transition element additives (Ti, V) during ball milling of magnesium hydride

It has been revealed that ball-milling of MgH2 powders with small amounts of selected 3d-transition metals M such as Ti, Nb.... or oxides of 3d-metals (e.g. Cr2O3) leads to marked improvements of the hydrogen absorption/desorption kinetics. We have undertaken systematic co-milling processes under argon atmosphere of MgH2 powders added with small amounts of Ti, V and Nb by using a planetary machine. The resulting products were analysed by using XRD, SEM and hydrogen absorption techniques. Different milling times were applied and both the resulting particle size and the degree of crystalline/amorphous state were estimated. During the intensive milling, we have pointed out the formation of transition metal hydrides MHx as an effect of mechanical alloying. The main results are discussed regarding the nature of the d-metal additions and the co-milling time procedure. (C) 2004 Elsevier B.V. All rights reserved.