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Metallurgical Synthesis of Mg2FexSi1-x Hydride: Destabilization of Mg2FeH6 Nanostructured in Templated Mg2Si.
Inorganic Chemistry ( IF 4.3 ) Pub Date : 2020-02-14 , DOI: 10.1021/acs.inorgchem.9b03117
Kohta Asano 1 , Hyunjeong Kim 1 , Kouji Sakaki 1 , Yumiko Nakamura 1 , Yongming Wang 2 , Shigehito Isobe 2 , Masaaki Doi 3 , Asaya Fujita 4 , Naoyuki Maejima 5, 6 , Akihiko Machida 6 , Tetsu Watanuki 6 , Ruud J Westerwaal 7 , Herman Schreuders 7 , Bernard Dam 7
Affiliation  

Magnesium-based transition-metal hydrides are attractive hydrogen energy materials because of their relatively high gravimetric and volumetric hydrogen storage capacities combined with low material costs. However, most of them are too stable to release the hydrogen under moderate conditions. Here we synthesize the hydride of Mg2FexSi1-x, which consists of Mg2FeH6 and Mg2Si with the same cubic structure. For silicon-rich hydrides (x < 0.5), mostly the Mg2Si phase is observed by X-ray diffraction, and Mössbauer spectroscopy indicates the formation of an octahedral FeH6 unit. Transmission electron microscopy measurements indicate that Mg2FeH6 domains are nanometer-sized and embedded in a Mg2Si matrix. This synthesized metallographic structure leads to distortion of the Mg2FeH6 lattice, resulting in thermal destabilization. Our results indicate that nanometer-sized magnesium-based transition-metal hydrides can be formed into a matrix-forced organization induced by the hydrogenation of nonequilibrium Mg-Fe-Si composites. In this way, the thermodynamics of hydrogen absorption and desorption can be tuned, which allows for the development of lightweight and inexpensive hydrogen storage materials.

中文翻译:

Mg2FexSi1-x氢化物的冶金合成:模板化Mg2Si中纳米结构化的Mg2FeH6的失稳。

镁基过渡金属氢化物因其相对较高的重量和体积氢存储容量以及较低的材料成本而成为有吸引力的氢能材料。但是,它们中的大多数都太稳定,无法在中等条件下释放氢。在这里,我们合成了Mg2FexSi1-x的氢化物,它由具有相同立方结构的Mg2FeH6和Mg2Si组成。对于富硅氢化物(x <0.5),通过X射线衍射可观察到大部分Mg2Si相,穆斯堡尔光谱表明形成了八面体FeH6单元。透射电子显微镜测量表明,Mg2FeH6域是纳米尺寸的,并嵌入在Mg2Si基质中。这种合成的金相结构导致Mg2FeH6晶格变形,从而导致热不稳定。我们的结果表明,纳米级镁基过渡金属氢化物可通过非平衡Mg-Fe-Si复合材料的氢化作用而形成为基体强迫的组织。以此方式,可以调节氢吸收和解吸的热力学,这允许开发轻质且廉价的氢存储材料。
更新日期:2020-02-17
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