Abstract MgH2 is one of promising hydrogen storage materials, but Mg crystallites grow up very fast during hydrogen desorption, leading to the degradation of hydrogen storage properties. Therefore the growth behavior and mechanism of Mg crystallites during hydrogen desorption of nanocrystalline MgH2 were investigated in this work. It was found that the transformation from MgH2 to Mg occurred by the surface-controlled ‘nucleation and growth’ mechanism. After the instantaneous nucleation of Mg at free surfaces of MgH2 particles, Mg crystallites grew through three stages, namely one-dimensional, then two-dimensional and finally one-dimensional growths. In the second stage, Mg crystallites grew quickly as compared with other stages. After complete hydrogen desorption, the average Mg crystallite size in MgH2−10 wt% Pr3Al11 sample was smaller than that in pure MgH2 sample due to the presence of Pr3Al11.

中文翻译：

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MgH2 脱氢过程中 Mg 的微晶生长特性

摘要 MgH2 是一种很有前景的储氢材料，但在脱氢过程中，Mg 微晶生长非常快，导致储氢性能下降。因此，在这项工作中研究了在纳米晶 MgH2 的氢解吸过程中 Mg 微晶的生长行为和机制。发现从 MgH2 到 Mg 的转变是通过表面控制的“成核和生长”机制发生的。在 MgH2 粒子的自由表面瞬时成核后，Mg 微晶的生长经历了三个阶段，即一维、二维和最后一维生长。在第二阶段，与其他阶段相比，Mg 微晶生长迅速。氢气完全解吸后，