Hydrogen storage in Mg-10 at.% LaNi5 nanocomposites, synthesized by ball milling at different conditions
Hydrogen storage in Mg-10 at.% LaNi5 nanocomposites, synthesized by ball milling at different conditions
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DOI：
10.1016/j.jallcom.2010.01.107
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发表时间：
2010-04-09
影响因子：
6.2
通讯作者：
Himitliiska, Ts
中科院分区：
文献类型：
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作者：
Spassov, T.;Delchev, P.;Himitliiska, Ts
在不同条件下通过高能球磨合成了三种 Mg-10 at.% LaNi5 纳米复合材料。其中一种复合材料是通过研磨 MgH2 和 LaNi5 制备的，而其他两种复合材料则使用纯 Mg 和 LaNi5 作为起始材料。最后两种复合材料在不同条件下干磨并用庚烷进行研磨。所有复合材料均通过扫描电子显微镜测定了相对较窄的粒度分布。前两种复合材料的平均粒径约为2μm，而在较温和的机械化学条件（在庚烷中）研磨的复合材料显示出明显更大的平均粒径，约为6μm。所有复合材料都显示出纳米晶微观结构（28-33 nm），在氢化/脱氢循环过程中似乎相当稳定，无论退火温度如何（300摄氏度），平均晶粒尺寸都会略有增加。在铣削和进一步退火过程中检测到新相的形成——形成Mg2Ni和Mg6Ni。发现对于具有更细颗粒和晶粒尺寸的复合材料来说，氢化和脱氢动力学非常快。观察到部分低温吸氢现象，并提出并证明了“泵吸气”机制。 (C) 2010 Elsevier B.V. 保留所有权利。
Three Mg-10 at.% LaNi5 nanocomposites were synthesized by high-energy ball milling at different conditions. One of the composites was prepared by milling MgH2 and LaNi5, whereas for the other two composites pure Mg and LaNi5 were used as starting materials. The last two composites were milled at different conditions dry milling and with heptane. Relatively narrow particle size distribution has been determined by scanning electron microscopy for all composites. Mean particle size of about 2 mu m has been obtained for the first two composites, while the composite milled at milder mechanochemical conditions (in heptane) shows substantially larger average particle size of about 6 mu m. All composites have shown nanocrystalline microstructure (28-33 nm), which appeared to be quite stable during hydriding/dehydriding cycling, slightly increasing the mean crystallite size regardless the high-temperature of annealing (300 degrees C). Formation of new phases has been detected during the milling and further annealing-Mg2Ni and Mg6Ni were formed. Hydriding and dehydriding kinetics were found to be very fast for the composites with finer particle and grain sizes. Partial low-temperature hydrogen absorption has been observed and "pump-getter" mechanism was suggested and proved. (C) 2010 Elsevier B.V. All rights reserved.