Phase Equilibria in the B–BN–B2O3 System at 5 GPa

Abstract

Phase equilibria in the B–BN–B2O3 ternary system at pressures up to 5 GPa have been studied by in situ probing with synchrotron X-ray powder diffraction, microscopic and X-ray diffraction characterization of recovered samples, and thermodynamic analysis. The phase diagram of the system has been constructed by combining the previously reported data for binary subsystems and a conventional phenomenological model describing ternary interactions. The interaction parameter of the model of the ternary liquid phase has been determined by adjustment of experimental melting points to the calculated monovariant eutectic curve. The phase diagram is characterized by two ternary eutectics, one ternary transition-type equilibrium, and the maximum in the monovariant eutectic curve.