Kinetic fragility of binary and ternary glass forming liquid mixtures

The experimental studies of liquid fragility in miscible binary and ternary glass forming mixtures reveal a general observation of the negative deviation in fragility upon mixing from the linear average of those of the components. Further analyses from ideal, near ideal to non-ideal mixing modes show that the deviation magnitude does not increase monotonically with mixing enthalpy, and a moderate intermolecular interaction would generate a largest reduction in fragility. Four eutectic systems, methyl-o-toluate-methyl-p-toluate, ZnCl(2)-AlCl(3), glycerol-water, and fructose-water, are studied to locate the composition where the largest fragility deviation occurs in phase diagrams. It is found that the compositions with the fragility minima do not coincide with the eutectic points. The results partly explain the experimental observation that the best glass forming region is not located at the eutectic composition.