Research Institute of Energy Frontier , National Institute of Advanced Industrial Science and Technology (AIST) , Tsukuba West, 16-1 Onogawa , Tsukuba , Ibaraki 305-8569 , Japan.
Research Institute for Material and Chemical Measurement , National Institute of Advanced Industrial Science and Technology (AIST) , Tsukuba Central-5, 1-1-1 Higashi , Tsukuba , Ibaraki 305-8565 , Japan.
Inorg Chem. 2018 Sep 17;57(18):11831-11838. doi: 10.1021/acs.inorgchem.8b02015. Epub 2018 Sep 4.
Hydrogenation of nonequilibrium alloys may form nanometer-sized metal hydride clusters, depending on the alloy compositions and hydrogenation conditions. Here in the Ti-rich compositions of the immiscible Mg-Ti system MgH clusters are embedded in a Ti-H matrix. Our previous works have indicated that the interface energy between the two metal hydrides reduces the stability of MgH. The aim of our study is to obtain the structural information on the nanometer-sized clusters. Indeed, MgD clusters embedded in a face-centered-cubic (FCC) Ti-D matrix is found in MgTiD by means of H magic angle spinning nuclear magnetic resonance (MAS NMR). The atomic pair distribution function (PDF) analysis of neutron total scattering data suggests that the MgD clusters have an orthorhombic structure, which is different from a rutile-type body-centered-tetragonal (BCT) structure of α-MgD observed in the Mg-rich compositions. Our results suggest that we can tune the thermodynamics of hydrogen absorption and desorption in Mg-H using the interface energy effect and accompanying stress-induced structural change, which contributes to the substantial development of lightweight and inexpensive hydrogen storage materials.
非平衡合金的加氢反应可能会形成纳米级金属氢化物团簇，这取决于合金成分和加氢条件。在不相溶的 Mg-Ti 体系富 Ti 成分中，MgH 团簇嵌入在 Ti-H 基体中。我们之前的工作表明，两种金属氢化物之间的界面能降低了 MgH 的稳定性。我们研究的目的是获取纳米级团簇的结构信息。实际上，通过 H 魔角旋转核磁共振（MAS NMR）发现在 MgTiD 中存在嵌入在面心立方（FCC）Ti-D 基体中的 MgD 团簇。对中子总散射数据的原子对分布函数（PDF）分析表明，MgD 团簇具有正交结构，与在富 Mg 成分中观察到的 α-MgD 的金红石型体心四方（BCT）结构不同。我们的结果表明，我们可以利用界面能效应和伴随的应力诱导结构变化来调节 Mg-H 中吸氢和放氢的热力学，这有助于开发更轻、更便宜的轻质储氢材料。
