Excess heat capacity in glass-forming liquid systems containing molecules

Excess heat capacities at glass transition temperature in two types of glass-forming systems of [xNaNO3(1x)KNO3]60·[Ca(NO3)2]40(0x1) and Ca(NO3)2yH2O(4y13) are studied.In the former system,with the replacement of K + cation with Na + cation,the excess heat capacity is around 65.1 J mol-1·K-1,while the excess increases by 38.9 J mol-1·K-1 upon one molar H2O content in latter system.A quantitative description to the excess heat capacity is built up with the thermal effects of atomic and molecular translational motion in liquids.The results might offer a further understanding to the glass transition.