Mesoscopic scale description of nucleation processes in glasses

Mesoscale ordering of a Zr-bearing aluminosilicate glass is determined using high-angle annular dark field scanning transmission microscopy, corrected from aberration. This method reveals evidences for the presence of nanometer-size inhomogeneities in a macroscopically isotropic glass, with regions enriched in Zr. The nucleation step is largely overcome by the initial glass organization and can be understood as a local aggregation process, made easier as a result from the intrinsic heterogeneous organization of the initial glass structure.