Thermodynamic measurement of (Al 2O 3 + B 2O 3) system by double Knudsen cell mass spectrometry

Abstract

Thermodynamic properties of B 2O 3 in the (Al 2O 3 + B 2O 3) binary system were investigated by vapor pressure measurement of B 2O 3 in equilibrium with (Al 2O 3 + B 2O 3) compounds or melts using double Knudsen cell mass spectrometry. The Gibbs free energy change of formation of Al 18B 4O 33 (9Al 2O 3·2B 2O 3) was estimated from the vapor pressure in equilibrium with a mixture of Al 18B 4O 33 and Al 2O 3 at 1573 K to 1673 K. And activities of B 2O 3 in the two-phase region Al 18B 4O 33 and B 2O 3-rich liquid, and (Al 2O 3 + B 2O 3) melts were obtained at 1373 K to 1423 K by vapor pressure measurements.