Predicting homogeneous nucleation rates in silicate glass-formers

We employed the Classical Nucleation Theory using a characteristic value of the pre-exponential constant and an average (temperature dependent) interfacial energy and derived an expression to estimate the maximum nucleation rates, Imax, as a function of the reduced glass transition temperatures, Tgr ≡ Tg/Tm (Tg is the laboratory glass transition temperature and Tm is the melting point or liquidus temperature). The theoretical predictions were surprisingly good for 51 out of 54 silicate glass-formers tested and describe well the experimental trend that Imax strongly decreases with increasing Tgr. This trend, in turn, explains the well-known fact that only silicate glasses having a relatively low Tgr, Tgr < 0.6, show internal homogeneous nucleation in laboratory time/sample-size scales.