Abstract :
The optimal compositions of many commercial glasses (such as window glass) are close to the ternary 74SiO2–16Na2O–10CaO. Constraint theory determines the contributions of the modifiers Na2O and CaO to network formation. Unexpectedly, the mechanical aspects of ionic oxide glasses are found to be quite similar to those of covalent chalcogenide glasses, which consist of network formers alone. The theory identifies old critical experiments and predicts new ones. It correctly determines the composition of window glass, one of natureʹs most remarkable materials, without adjustable parameters.
