Asano Kohta, Kim Hyunjeong, Sakaki Kouji, Nakamura Yumiko, Wang Yongming, Isobe Shigehito, Doi Masaaki, Fujita Asaya, Maejima Naoyuki, Machida Akihiko, Watanuki Tetsu, Westerwaal Ruud J, Schreuders Herman, Dam Bernard
Research Institute of Energy Frontier, National Institute of Advanced Industrial Science and Technology, Tsukuba West, 16-1 Onogawa, Tsukuba, Ibaraki 305-8569, Japan.
Graduate School of Engineering, Hokkaido University, N-13, W-8, Sapporo 060-0813, Japan.
Inorg Chem. 2020 Mar 2;59(5):2758-2764. doi: 10.1021/acs.inorgchem.9b03117. Epub 2020 Feb 14.
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 MgFeSi, which consists of MgFeH and MgSi with the same cubic structure. For silicon-rich hydrides ( < 0.5), mostly the MgSi phase is observed by X-ray diffraction, and Mössbauer spectroscopy indicates the formation of an octahedral FeH unit. Transmission electron microscopy measurements indicate that MgFeH domains are nanometer-sized and embedded in a MgSi matrix. This synthesized metallographic structure leads to distortion of the MgFeH 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.
镁基金属氢化物因其相对较高的质量储氢容量和体积储氢容量以及较低的材料成本，而成为有吸引力的氢能材料。然而，它们中的大多数过于稳定，无法在温和条件下释放氢气。在此，我们合成了MgFeSi的氢化物，它由具有相同立方结构的MgFeH和MgSi组成。对于富硅氢化物（<0.5），通过X射线衍射主要观察到MgSi相，穆斯堡尔光谱表明形成了八面体FeH单元。透射电子显微镜测量表明，MgFeH畴为纳米尺寸，并嵌入MgSi基体中。这种合成的金相结构导致MgFeH晶格畸变，从而导致热失稳。我们的结果表明，纳米尺寸的镁基金属氢化物可以通过非平衡Mg-Fe-Si复合材料的氢化形成基体强制组织。通过这种方式，可以调节吸氢和解吸的热力学，这有助于开发轻质且廉价的储氢材料。
