摘要
采用热蒸发法制备了纯Mg膜及Mg_(78)Ni_(22)合金膜,研究了薄膜的结构及其氢化性能。Mg膜具有典型的柱状晶结构,择优取向生长趋势明显;Mg_(78)Ni_(22)薄膜由纳米晶Mg_2Ni,Mg及少量非晶组成,Mg_2Ni相沿着平行于薄膜表面的(001)方向择优生长。纯Mg膜的吸放氢温度分别为593和653 K,其吸氢过程遵循形核长大机制。Mg_(78)Ni_(22)薄膜的压力一组成等温曲线存在低压和高压两个平台区,分别对应Mg和Mg_2Ni的氢化反应,薄膜内Mg的吸放氢温度可分别降至473和503 K,薄膜的最大吸氢量(质量分数)达到5.7％。Mg的氢化性能改善与薄膜中纳米晶Mg_2Ni和非晶相起到的催化作用有关。
Microstructure and hydrogenation properties of Mg and Mg-Ni films fabricated by thermal evaporation method were investigated. The as deposited Mg film exhibits a preferred orientation and a typical columnar crystalline structure. The as deposited Mg-Ni film with a composition of Mg78Ni22 is composed of nanocrystalline Mg2Ni, Mg and a small amount of amorphous phase. Besides, the Mg2Ni crystallites grow with their (001) crystalline plane parallel to the substrate surface. The hydrogen absorption and desorption temperatures of pure Mg film are 593 K and 653 K, respectively and its hydriding reaction follows a nucleation and growth mechanism. Pressure-composition isotherms of Mg78Ni22 film show that its maximum hydrogen absorption capacity (mass fraction) reaches to 5.7% and there are the lower and higher pressure plateaus corresponding to the hydriding reactions of Mg and Mg2Ni, respectively. The hydriding/dehydriding temperatures of Mg in Mg78Ni22 film decreased down to 473 K and 503 K, respectively. The improvement on the hydrogenation properties of Mg is related to the catalytic role of nanocrystalline Mg2Ni and amorphous phase.
出处
《金属学报》
SCIE
EI
CAS
CSCD
北大核心
2004年第5期531-536,共6页
Acta Metallurgica Sinica
基金
国家自然科学基金 59925102
50131040
50071022
关键词
储氢合金
热蒸发
Mg膜
Mg—Ni薄膜
氢化性能
hydrogen storage alloy
thermal evaporation
Mg film
Mg-Ni film
hydrogenation property
