NUCLEATION IN DISORDERED MEDIA

A theory of the nucleation of crystalline particles in disordered medi a is proposed accounting for small statistical fluctuations in microsc opic structural parameters, which are shown to affect considerably the thermodynamic barrier to nucleation. As a result, the classical nucle ation-rate exponent -W/kT takes the correction GAMMA (W/kT)3 at high t emperatures, where GAMMA depends both on the correlation radius of the disorder and its amplitude; this correction may be significant. At lo w 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 the se findings for nucleation in glasses are discussed.