The role of the dynamic structural correlation in glasses in the initiation of brittle fracture

The previously reported data on the mid-range order and on the low-frequency vibrational interaction in glassy materials are interpreted in terms of dynamically defined correlation lengths between disordered structural units. The latter parameter is shown to be highly sensitive to the topological perturbations in the material which affect the cation–cation separation lengths, or, in general, to the local strains in the glass network. Virtual expansion of the correlation sphere involving ultimately strained chemical bonds imposes conditions on the formation of the fractal structure of primary nanocracks due to the scaling character of the inverse of the Grüneisen parameter.