NUCLEATION IN DISORDERED MEDIA

A theory of the nucleation of crystalline particles in disordered media is proposed accounting for small statistical fluctuations in microscopic structural parameters, which are shown to affect considerably the thermodynamic barrier to nucleation. As a result, the classical nucleation-rate exponent -W/kT takes the correction GAMMA (W/kT)3 at high temperatures, where GAMMA depends both on the correlation radius of the disorder and its amplitude; this correction may be significant. At low temperatures the nucleation-rate exponent remains finite in the case of uncorrelated disorder, while it is proportional to T-1/3 at T --> 0 in the case of strongly correlated disorder. The implications of these findings for nucleation in glasses are discussed.