Relation of vitron theory to 2-layer-liquid immiscibility in binary silicate and borate glass melts

Abstract

(AUgU5t I, 1972) Silica-rich and boron-rich binary glasses resemble c1athrates in having host cavities in which modifier ox ides may be in clos ed with out stress as inactive gues ts until the cavities are approximately fill ed. Additional modification results in stress both in th e holes of the matrix and the cavities of vitrons. Then the structur e begin s to di sintegrate and mixin g tak es place. The r equired mol e-perce nt modification is expressed by an equation of the form lOOr.100where II and a are the diame te rs of vitron cavity and matri x hole, res pective ly, L is th e lin ea r exte nt of a modifier, and q the proportion of glass-maker that forms vitrons. Computations for 66 glasses have bee n mad e to constitute a unified system covering approximate ly the gamut of typical modifiers.The identity of parameters A and a for silicates and borates leads to the suggestion that the vitron structure in boric-oxide glass is th e regular icosah edron of 20 tria ngular fa ces to accommodate a neutral molec ule of (B.O.).. Regular octahednl of (B.O.)., if present in the matrix, would provide matrix holes of approximately a in diameter.