Effects of zirconia, scandia, and other trivalent metal oxides on liquid immiscibility in sodium borosilicate glasses

The effects of aluminum, gallium, indium, scandium, ytterbium, lanthanum, and zirconium oxides on the miscibility temperature, T/sub c/, of a sodium borosilicate glass, 9Na/sub 2/O . 31B/sub 2/O/sub 3/ . 60SiO/sub 2/, are reported. Gallium oxide behaves like lumina, tending to reduce T/sub c/ whereas the other four trivalent metal oxides tend to increase it. Zirconium oxide is intermediate in its behavior and showed little effect on T/sub c/ of this glass or other sodium borosilicate compositions within the range 5-15 mol% Na/sub 2/O, 0-7 mol% ZrO/sub 2/, 20-50 mol% B/sub 2/O/sub 3/, and 45-70 mol% SiO/sub 2/. Detailed examination of the sodium scandium borosilicate system confirmed that Sc/sub 2/O/sub 3/ affects miscibility limits in a similar way to rare-earth oxides.