Chen Li, Hu Changyi, Liu Feng
Kunming University of Science and Technology Kunming 650093 China.
Kunming Institute of Precious Metals Kunming 650106 China
RSC Adv. 2019 Feb 5;9(8):4445-4452. doi: 10.1039/c8ra08983c. eCollection 2019 Jan 30.
The present work reports the fabrication of MgRE (RE = Pr, Sm, Nd) alloys by a vacuum induction furnace. The phase analysis, structure characterization and microstructure observation of MgRE alloys were carried out by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). There exhibits a multiphase microstructure in the as-cast MgRE (RE = Pr, Nd, Sm) alloys from the comprehensive analysis made from XRD and SEM, which are containing the major phase (REMg) and several secondary phases (REMg and REMg). The detections of XRD and TEM reveal that these experimental alloys turn into a MgH nanocrystalline composite with equably distributed RE hydride nanoparticles after hydriding and this MgH major phase turns into a Mg nanocrystalline after dehydriding. The determination results of the hydrogen storage kinetics show that adding the rare earth element (Pr, Sm and Nd) ameliorates the hydriding and dehydriding kinetics of the Mg-based alloys dramatically. The hydrogen desorption activation energy (de) of MgPr, MgNd, MgSm are 140.595, 139.191, 135.280 kJ mol H, respectively. Specially, the hydrogen storage capacity (wt%) of MgSm alloy that added Sm element can reached 5 wt%. The improvement of the hydrogen storage performance of MgRE alloys can be principally ascribed to the RE hydride nanoparticles facilitating the hydriding and dehydriding reactions.
本工作报道了采用真空感应炉制备MgRE（RE = Pr、Sm、Nd）合金。通过X射线衍射（XRD）、扫描电子显微镜（SEM）和透射电子显微镜（TEM）对MgRE合金进行了相分析、结构表征和微观结构观察。根据XRD和SEM的综合分析，铸态MgRE（RE = Pr、Nd、Sm）合金呈现出多相微观结构，其中包含主要相（REMg）和几个次要相（REMg和REMg）。XRD和TEM检测表明，这些实验合金在氢化后转变为具有均匀分布的RE氢化物纳米颗粒的MgH纳米晶复合材料，而这种MgH主要相在脱氢后转变为Mg纳米晶。储氢动力学的测定结果表明，添加稀土元素（Pr、Sm和Nd）显著改善了镁基合金的氢化和脱氢动力学。MgPr、MgNd、MgSm的氢解吸活化能（de）分别为140.595、139.191、135.280 kJ mol H。特别地，添加Sm元素的MgSm合金的储氢容量（wt%）可达5 wt%。MgRE合金储氢性能的提高主要归因于RE氢化物纳米颗粒促进了氢化和脱氢反应。
