Abstract
I report the results of a series of dynamic light scattering studies of molten aluminophosphate liquids, [Al(PO3)3]x[NaPO3]100-x, obtained by photon correlation spectroscopy. The study covers a range of compositions designed to manipulate the network connectivity of the glass-forming liquid in order to investigate how the change in the chemical structure of covalent network affects its dynamics. The dynamic structure factor was measured to provide quantitative information about the liquid's dynamics through the non-ergodic level, stretching exponent, and fragility. The fragility was shown to decrease with increased network connectivity and the result is identical to both ultraphosphates and chalcogenides. I argue that this pattern fits with predictions of the rigidity theory and may be linked to a common dependence on the entropy of the liquid as a function of the network connectivity described by a two-state bond model.