Phase equilibria and β-BaB2O4 crystal growth in the BaB2O4–BaF2 system

Abstract

The phase formation in the BaB₂O₄–BaF₂ system has been studied. According to the results obtained, the BaB₂O₄–BaF₂ system is quasi binary with the eutectic at 760 °C, 41 mol% of BaB₂O₄, and 59 mol% of BaF₂. The fast pyrohydrolysis of BaF₂ in air causes the gradual transformation of the BaB₂O₄–BaF₂ system into the BaB₂O₄–BaO system and results in the co-crystallization of BaB₂O₄ and Ba₅B₄O₁₁ phases, making the growth of large high-quality β-BaB₂O₄ crystals in air impossible.