Shape of Liquid Immiscibility Volume in the System Barium Oxide‐Boric Oxide‐Silica

Abstract

The shape of the immiscibility volume in the system BaO‐B 2 O 3 ‐SiO 2 is determined from data on seventeen compositions. The ternary critical solution curve originates at the critical point in the binary system BaO‐B 2 O 3 , located at 1225°C. and 15 weight % BaO. It extends almost linearly to its terminus on the silica primary‐phase surface, at about 1405° C. and the composition 18 weight % BaO, 10.5% B 2 O 3 , 71.5% SiO 2 . By extrapolation of the ternary critical solution curve, the critical point of the postulated meta‐stable immiscibility region in the binary system BaO‐SiO2 is located at 1430° C. and 18.5 weight % BaO.