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.
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