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摘要: 本文用X射线衍射和差热分析方法对La-Ga二元系相图的富Ga部份进行了研究。发现在La-Ga系相图的富Ga部份存在着一包晶反应,形成一新的金属互化物,其均匀范围很窄。确定了这一新化合物为LaGa6,属四方晶系,空间群为P4/nbm,点阵常数α=6.1041?,c=7.7052?。另外还发现LaGa2这一金属互化物存在着一个相区,其均匀范围为66.7A/0 Ga到71.6A/0 Ga。在这一相区内,点阵常数α随Ga含量的递增而增大,c随之减少。论证了这一固溶体系由一对Ga原子无序地替代一个La原子的结果。
Abstract: The Ga-rich side of La-Ga binary system phase diagram has been investigated by means of X-ray diffraction and differential thermal analysis.In this portion of the phase diagram there is a peritectic reaction. A new interme-tallic compound LaGa6 is found, its homogeneous range is extremly narrow and it is formed peritectically at 700℃. It belongs to the tetragonal system with space group D4h3 -P4/nbm. Bach unit cell contains two formula units LaGa6. Its lattice parameters are: α =6.1041?, c =7.7052?.In addition, it is established that the in termatallic compound LaGa2 has a homogeneous range from 66.7 A/0 to 71.6 A/0 Ga. In this region, with the addition of gallium, the lattice parameters a increses, but c reduces. The result shows that this solid solution is formed due to one lanthanum atom substituted randomly by a pair of gallium atoms in x-y plane.