EFFECT OF COMPOSITION ON THE GLASS-FORMING TENDENCY OF BARIUM ALUMINOSILICATE GELS DERIVED FROM METAL ALKOXIDES

The effect of composition on the glass-forming tendency of barium alum inosilicate gels derived from metal alkoxides with compositions near t he theoretical composition of barium feldspar was studied. Results ind icated that, in the experimental range, larger SiO2 content and larger BaO/Al2O3 ratio were advantageous to glass formation. A criterion for glass formation in the studied system was established as (b + 3 - 4y) /(2y + s(1 + b)/(100 - s)) < J(c), where b is the BaO/Al2O3 ratio, s t he mol percentage of SiO2, y the fraction of four-coordinated aluminum over the total amount of aluminum, and J(c) is a constant for a defin ite experimental condition. The criterion showed good fitness with the experimental results. (C) 1998 Elsevier Science B.V. All rights reser ved.