Quantitative principles of silicate glass chemistry

The optimal compositions of many commercial glasses (such as window glass) are close to the ternary 74SiO(2)-16Na(2)O-10CaO. Constraint theory determi nes the contributions of the modifiers Na2O and CaO to network formation. U nexpectedly, the mechanical aspects of ionic oxide glasses are found to be quite similar to those of covalent chalcogenide glasses, which consist of n etwork formers alone. The theory identifies old critical experiments and pr edicts new ones. It correctly determines the composition of window glass, o ne of nature's most remarkable materials, without adjustable parameters. (C ) 2000 Elsevier Science Ltd. All rights reserved.