Phase Equilibria and Thermodynamic Properties of Components in the Cs_2O-B_2O_3-SiO_2 System at High Temperatures

摘要

The phase equilibria in the Cs_2O-B_2O_3-SiO_2 system are investigated in the temperature range 873-1073 K by the annealing-quenching technique,high-temperature microscopy,and X-ray powder diffraction analysis.The vapor composition,the activities of the components,and the Gibbs energies of glasses and melts in the Cs_2O-B_2O_3-SiO_2 system are determined at a temperature of 1020 K.It is demonstrated that glasses and melts in the Cs_2O centre dot B_2O_3-Cs_2O centre dot SiO_2 system are characterized by positive deviations of the CsBO_2 activities and negative deviations of the Cs_2O centre dot SiO_2 activities from ideal behavior.As a consequence,the deviations of the Gibbs energies from ideal behavior change their sign.