Nucleation catalysis in metastable liquids: Inborn active sites

A simple formalism is developed in order to analyze the nucleation activity of inborn "week" or "strong" active sites in metastable liquids which can play in nucleation kinetics a role, similar to this of heterogeneous nuclea tion cores. As examples are examined the influence of Bernal holes and fluc tuatively formed Frenkel voids on bubble nucleation, of athermal supercriti cal nuclei and heterophase fluctuations, frozen-in in the thermal prehistor y of the system on any process of phase formation, and of structural defect s, due to change of composition or created in redox processes on crystalliz ation. The analysis is pel formed in analogy with the known treatment of th e influence of heterogeneous Foreign cores on nucleation kinetics. Differen t changes of the metastable liquid are investigated, considering both isoba ric thermal quenches and change of pressure at isothermal conditions. The e ffect of inborn active sites on both steady nucleation rate I-ss and on nuc leation time lag tau(#) is investigated. In this way the whole kinetics of nucleation is constructed using the known approximative solutions of the mo re general, transient theory of nucleation.