Effect of dynamical heterogeneity on heat capacity at glass transition in typical silicate glasses.

The heat capacity jump ΔC_p at glass transition and the dynamical heterogeneity are two of the most important features of glass forming liquids. In order to reveal the intrinsic relationship between the two properties, a model glass system (Na₂O)_x(SiO₂)_1-x (x=0.2-0.35) was studied by the systematic measurements of the ΔC_p and the mechanical relaxation in the supercooled liquid region. A linear increase in ΔC_p with increasing content of Na₂O was found, indicating direct contributions of the locally fast dynamics around Na₂O to ΔC_p. This positive correlation between the locally heterogeneous dynamics and ΔC_p was further confirmed by the dynamical heterogeneity analyses. Our results might be helpful for understanding the nature of glass transition. [ABSTRACT FROM AUTHOR]