Glasses With Transitional Structures

In many glass sytems a range of compositions exists over which the structure transforms from one in which properties are controlled by continuous alkali-rich channels to one in which the alkali-rich regions become discontinous (clusters), or randomly disperse (random network). In the latter case the properties are controlled by the strongly bonded silicate network. Structures between the two limiting structures are termed "transitional". This paper describes alkali alumino- and borosilicate glasses with transitional structures.