Catalytic effect of Ge on hydrogen desorption from MgH2

We studied the influence of Ge on hydrogen desorption from MgH2 produced by mechanical alloying at room temperature under a hydrogen atmosphere. The structural and morphological properties, and the desorption kinetics of the products were examined by X-ray diffraction, differential scanning calorimetry, thermal desorption spectroscopy and scanning electron microscopy. The mechanical milling of Mg-Ge mixtures under hydrogen leads to the formation of Mg2Ge and MgH2. The presence of Ge decreases the hydride decomposition temperature in a range from 50 to 150degreesC, depending on the Ge amount. On the contrary, Mg2Ge does not show any effect on hydrogen desorption. (C) 2002 Elsevier Science B.V. All rights reserved.