Mg／MmM5多层复合薄膜的储氢性能和显微结构研究

Microstructure of MmNi3.5 （CoAIMn） 1.5/Mg Multi-layers for Hydrogen Storage

用X-ray衍射（XRD）方法研究了磁控溅射制备的MmNi35（CoAIMn）1．5／Mg（简写为Mg／MmM5）多层薄膜吸放氢前后的结构变化和储氢性能。XRD表明Mg／MmM5多层膜中Mg层的储氩性能有一定程度的改善，吸傲氢温度分别为473K和523K。用透射电镜（TEM）分析方法研究了快速热退火（RTA）处理前后Mg／MmM5多层薄膜的微现结构的变化。Mg／MmM5多层膜中Mg层和MmM5层的结构与村底的温度和材料本身的性质有密切关系。Mg／MmM5多层膜在400℃经过3min RTA处理后，Mg层中的纳米晶和拄状晶都有所长大，长大后的纳米晶和拄状晶晶粒尺寸基本相当，约200nm，纳米晶和拄状晶区界限仍然明显，拄状晶依然保持着沿垂直于衬底表面的[001]方向生长；MmM5层中的非晶层消失，纳米晶得到长大，尺寸约20nm。

The change of microstructures and hydrogen storage properties of MmNi3.5 （CoAlMn）1.5/Mg （MmM5 denoting MmNi3.5 （CoAlMn） 1.5 here and thereby） multi-layer thin films were studied by using X-ray diffraction（XRD）. XRD results shows that Mg/MmM5 multi-layer thin films could absorb and desorb hydrogen at 473 K and 523 K respectively. The change of microstructures of Mg/MmM5 multi-layer thin films as-prepared and as rapid thermal annealing （RTA） at 400 ℃ for 3 minutes in a furnace was also studied by using cross section transmission electron microscopy （XTEM） in order to monitor the real microstructure when hydrogenation/dehydrogenation takes place. 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 100 nm, After annealing, the nanocrystalline region extends to 250 nm thick and the columnar crystallites becomes to about 200 nm. On the other hand, 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, After annealing, the entire MmM5 layer turns into nanocrystalline.