Hydrogenation rate limiting step, diffusion and thermal conductivity in cold rolled magnesium hydride

In this paper, the investigation of the rate limiting steps in hydrogen absorption and desorption of cold rolled magnesium hydride is reported. Absorption and desorption curves were made at different temperatures with constant driving force. Results show that the rate limiting step of the reactions of magnesium with hydrogen does not change with temperature. After cold rolling, hydrogen absorption is diffusion controlled, while the desorption process is three dimensional growth of existing nuclei. NMR measurements are also reported; there is no increase in the rate of hydrogen diffusive motions in the cold rolled material, compared to bulk. The effect of rolling and ball milling on thermal conductivity was also investigated.