Slow relaxation near structural and orientational transitions in glass-forming liquids and solids

We argue that the fragility observed near the glass-transition temperature complies with the growing correlation length conception for the entire family of glass-forming materials. The analysis is given through the percolation-theoretical treatment of the relaxation dynamics considered in an effective medium of dimension (d) over bar. For long-lived clusters of characteristic radius R-0 dynamical correlations are introduced through the relaxation time tau(0) infinity R-0(z). The relaxation function is given in an explicit Kohlrausch-Williams-Watts form with the stretch exponent beta = (d) over bar/(z + (d) over bar) that results in the fragility m = m(0)(1/beta - 1) It is shown that within the low-frequency domain the cluster-growing correlations are consistent with the Dixon-Nagel master curve and fit the idea of universality of glass-transformation features in solids and liquids.