MmM_5/Mg复合薄膜的显微结构与储氢性能的关系

Microstructure and hydrogen storage properties of MmNi_(3.5)(CoAlMn)_(1.5)/Mg multi-layers

本文用X-ray衍射(XRD)方法研究了磁控溅射制备的MmNi3.5(CoAlMn)1.5/Mg(简写为Mg/MmM5)复合薄膜吸放氢前后的结构变化与储氢性能间的关系。XRD表明Mg/MmM5多层膜中Mg层的储氢性能有一定程度的改善,吸/放氢温度分别为473 K和523 K。用透射电镜(TEM)分析方法研究了Mg/MmM5多层薄膜的微观结构,Mg/MmM5多层膜中Mg层和MmM5层的结构与衬底的性质有密切关系。Mg层由纳米晶和沿垂直于衬底表面的[001]方向生长的柱状晶组成;MmM5层则由纳米晶和非晶组成。Mg/MmM5多层膜在吸氢过程中表现为(103)面平行于衬底生长的柱状晶先吸氢,然后是(001)面生长的柱状晶再吸氢。

The change of microstructures and hydrogen storage properties of MmNi3.5 （CoAlMn）15/Mg （MmM5 denoting MmNi3.5 （CoAlMn）1.5 here and thereby） multi-layer thin films were studied using X-raydiffraction（XRD）. XRD results show that Mg/MmM5 multi-layer thin films could absorb and desorb hydrogen at 473 K and 523 K respectively. The microstructure of Mg/MmM5 muhi-layer thin films as-prepared was also studied using cross section transmission electron microscopy （XTEM）. The Mg layers in the as-prepared thin films mainly compose of two regions： randomly orientated nanocrystalline region at the bottom of the layer with a columnar crystallite region on top of them. These Mg columnar crystallites have their [ 001 ] directions roughly parallel to the growth direction and the average lateral size of these columnar crystallites is about 100nm. The MmM5 layer in the as-prepared thin films contains two regions as well： an amorphous region of about 4 nm thick at the bottom of the layer with a nanocrystalline region on the top. During the hydrogenation process, the Mg columnar crystallites with （103） orientation absorb hydrogen first and then these with （001） orientation and those with （101） orientation.