The effect of milling conditions on microstructure and hydrogen absorption/desorption properties of magnesium hydride (MgH_2) without and with Cr_2O_3 nanoparticles

摘要

Commercial MgH_2 powder was mechanically (ball) milled without and with nanosized Cr_2O_3 particles in different types of ball mills using various milling conditions. The results demonstrate that the high-energy ball milling greatly improves the hydrogen absorption/ desorption kinetics of MgH_2. There is no significant difference in the sorption properties between powders milled in different commonly used mills. It was noticed that samples ball-milled in a planetary ball mill show improved desorption kinetics. In this study very favorable effect of Cr_2O_3 nanoparticles on hydrogen sorption kinetics was observed. The crystallite size of /?-MgH_2 after milling without or with nano-Cr_2O_3 is almost the same (?10nm). In contrast to that, the specific surface area of MgH_2 powder after milling with nanosized Cr_2O_3 decreases significantly as compared to the powder milled without catalyst.