TEM studies of nanostructure in melt-spun Mg-Ni-La alloy manifesting enhanced hydrogen desorbing kinetics
TEM studies of nanostructure in melt-spun Mg-Ni-La alloy manifesting enhanced hydrogen desorbing kinetics
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DOI：
10.1016/j.jallcom.2008.11.031
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发表时间：
2009-06-10
影响因子：
6.2
通讯作者：
Kuroda, K.
中科院分区：
文献类型：
--
作者：
Tanaka, K.;Miwa, T.;Kuroda, K.
通过在晶化和活化过程中形成纳米结构，显着提高了熔体快淬法制备的富镁镁合金的储氢性能。它可以在低至200摄氏度的温度下在中等时间内吸收和解吸类似于5wt%的氢气。对该合金的透射电子显微镜研究表明，氢化后LaH(3)和Mg(2)NiH(4)纳米粒子均匀地分散在MgH(2)基质中，在300℃以下相当稳定，但在400℃以上经历了这些颗粒和基质的粗化和偏析。这些结构变化已被电子能量损失谱(EELS)成像和高分辨电子显微镜技术所证实。在本研究中首次发现了与MgH(2)相的等离子体激元激发有关的新的EELS峰(H-等离子体激元)。通过对氢等离子体峰的成像，可以清楚地看到氢在合金中的分布。我们已经成功地利用这种电致发光二极管成像技术在显微镜下原位观察到了类似于400摄氏度的氢的脱附过程。(C)2008爱思唯尔B.V.保留所有权利。
The hydrogen storage properties of a magnesium-rich Mg-M-La alloy prepared by melt-spinning are significantly improved by nanostructure formation during crystallization and activation. It can absorb and desorb similar to 5 wt% hydrogen at temperatures as low as 200 degrees C in moderate time periods. Transmission electron microscopic (TEM) studies on this alloy indicate that the nanostructure, consisting of LaH(3) and Mg(2)NiH(4) nano-particles dispersed homogeneously in MgH(2) matrices after hydrogenation, is rather stable at temperatures below 300 degrees C but undergoes coarsening and segregation of these particles and matrices above similar to 400 degrees C. These structural changes have been confirmed by electron energy-loss spectroscopic (EELS) imaging as well as high-resolution TEM techniques. A new EELS peak associated with a plasmon excitation in the MgH(2) phase (H-plasmon) is found for the first time in this study. By imaging the H-plasmon peak, the hydrogen distribution in the alloy has been clearly visualized. We have succeeded in observing the hydrogen desorption process at similar to 400 degrees C in-situ in the microscope using this EELS imaging technique. (C) 2008 Elsevier B.V. All rights reserved.