Liquid Immiscibility in the Systems Na2O‐Yb2O3‐B2O3‐SiO2 and K2O‐Yb2O3‐B2O3‐SiO2

Abstract

Limits of miscibility were determined for portions of the systems Na2O‐Yb2O3‐B2O3‐SiO2 and K2O‐Yb2O3‐B2O3‐SiO2 in the range 650° to 800°C, at Yb2O3 concentrations up to 5 mol%, and at a fixed SiO2/B2O3 mole ratio of 2.0. Regions of the phase diagrams at higher Yb2O3 concentrations were not accessible because of interference from crystallization. The miscibility gaps have topographies similar to those found in the alkali‐metallalkaline‐earth borosilicate systems, X2O‐MO‐B2O3‐SiO2.