Phase equilibria in the system Li2O-MgO-B2O3

The subsolidus region of the Li 2 O-MgO-B 2 O 3 system has been studied by X-ray powder diffraction and differential thermal analysis. Isothermal sections at 500–550 and 650–700°C have been designed. The following complex borates have been found to form: at 500–550°C, Li 2 MgB 2 O 5 and LiMgBO 3 are formed; at 650–700°C, a new phase Li 4 MgB 2 O 5 is formed along with LiMgBO 3 ; and at 5500–600°, Li 2 MgB 2 O 5 is formed.