Nucleation in Glasses – New Experimental Findings and Recent Theories

International audienceNucleation is the initial process and the key operation to control and predict devitrification in glasses. The classical nucleationtheory is widely used to describe qualitatively this phenomenom though it is well known that considerable discrepancies existwith experimental results. Recent theories have been developed (Generalized Gibbs Approach, two-steps model) to overcome theapproximations in the classical model. They are based on experimental observations, considering explicitly non-classicalpathways driving to the critical nucleus formation. Additionally to these models, it is important to obtain high qualityexperimental information below about 50 nm. Using scanning transmission electron microscopy in high angle annular dark fieldimaging mode (STEM-HAADF), we have evidenced that glass structure is mesoscopically inhomogeneous and that intrinsicheterogeneities play a key role for promoting nucleatio