摘要
The effect of the partial substitution of Mg by A1 on the crystal structure of La2Mg17 has been investigated. It was found that the LaEMgl7 phase disappears after the partial substitution of Mg by Al. The LaE（Mgo.gAl0.1）17 alloy contains La（Mg,AI）12 and La（Mg,Al）2. Further increasing the Al content, the La2（Mg0.8Al0.2）17 alloy consists of La（Mg,Al）12, La（Mg,Al）2, and Mg. The La（Mg0.93Al0.07）12 phase in the La2（Mg0.9Al0.1）17 alloy crystallizes with the ThMn12-type structure in space group 14/mmm （No. 139）. The lattice parameters were determined to be a = 1.03246（7） nm and c = 0.59410（6） nm. In the ThMn12-type structure, AI atoms occupy 8f site but the A1 content is limited. Moreover, the hydrogenation character- istics have also been compared. La2Mgl7 decomposes into LaH3 and MgH2 under hydrogen, but the La（Mgo.93Alo.o7）12 phase can be hydrogenated into LaH3, MgH2, and La3Al11 at 473 K.
The effect of the partial substitution of Mg by A1 on the crystal structure of La2Mg17 has been investigated. It was found that the LaEMgl7 phase disappears after the partial substitution of Mg by Al. The LaE（Mgo.gAl0.1）17 alloy contains La（Mg,AI）12 and La（Mg,Al）2. Further increasing the Al content, the La2（Mg0.8Al0.2）17 alloy consists of La（Mg,Al）12, La（Mg,Al）2, and Mg. The La（Mg0.93Al0.07）12 phase in the La2（Mg0.9Al0.1）17 alloy crystallizes with the ThMn12-type structure in space group 14/mmm （No. 139）. The lattice parameters were determined to be a = 1.03246（7） nm and c = 0.59410（6） nm. In the ThMn12-type structure, AI atoms occupy 8f site but the A1 content is limited. Moreover, the hydrogenation character- istics have also been compared. La2Mgl7 decomposes into LaH3 and MgH2 under hydrogen, but the La（Mgo.93Alo.o7）12 phase can be hydrogenated into LaH3, MgH2, and La3Al11 at 473 K.
基金
financially supported by the Natural Science Foundation of Anhui Province (No. 050440602)
the Key Project of Chinese Ministry of Education (No. 205070)
the Scientific Research Foundation for the Candidates of Academic Leaders, Education Department of Anhui Province, China (No. 2005hbz08)
