Thermodynamic measurement of (Al2O3 + B2O3) system by double Knudsen cell mass spectrometry

Thermodynamic properties of B2O3 in the (Al2O3 + B2O3) binary system were investigated by vapor pressure measurement of B2O3 in equilibrium with (Al2O3 + B2O3) compounds or melts using double Knudsen cell mass spectrometry. The Gibbs free energy change of formation of Al18B4O33 (9Al2O3·2B2O3) was estimated from the vapor pressure in equilibrium with a mixture of Al18B4O33 and Al2O3 at 1573 K to 1673 K. And activities of B2O3 in the two-phase region Al18B4O33 and B2O3-rich liquid, and (Al2O3 + B2O3) melts were obtained at 1373 K to 1423 K by vapor pressure measurements.