Three New Alkaline Beryllium Borates LiBeBO₃, Li₆Be₃B₄O₁₂, and Li₈Be₅B₆O₁₈ in the Ternary Phase Diagrams Li₂O–BeO–B₂O₃

The phase diagram in the Li2O–BeO–B2O3 system has been systematically investigated by the methods of visual polythermal analysis, spontaneous crystallization, and X-ray diffraction. Three new alkaline beryllium borates, namely, LiBeBO3, Li6Be3B4O12, and Li8Be5B6O18, were synthesized with molten fluxes based on Li2O–B2O3 solvent in this system. All of the materials are centrosymmetric. The similarity of the fundamental building block of the title compounds has been compared. Thermal analysis and powder XRD studies were applied to determine phase relation and their incongruent melting behavior. The UV–vis diffuse reflectance spectroscopy demonstrated that the UV cutoff edges of the aforementioned materials are all below 200 nm.