Nucleation truncation by time-dependent supersaturation: a unified model for homogeneous and heterogeneous nucleation

• Published in: Electrochimica acta 2003-12, Vol.49 (1), p.93-101
• Main Authors: Pohlmann, Ludwig, Donner, Constanze
• Format: Article
• Language: English
• Subjects: Avromi theorem; Cross-disciplinary physics: materials science; rheology; Electrochemical phase transitions; Exact sciences and technology; Exponential law of nucleation; First-order phase transitions; Homogeneous and heterogeneous nucleation; Materials science; Methods of crystal growth; physics of crystal growth; Nucleation truncation; Physics; Theory and models of crystal growth; physics of crystal growth, crystal morphology and orientation; Time-dependent supersaturation
• ISSN: 0013-4686; 1873-3859
• DOI: 10.1016/j.electacta.2003.04.005

In this paper, a unified model for heterogeneous, as well as for homogeneous two-dimensional nucleation and growth processes for electrochemical phase transitions is derived. It accounts for three different mechanisms of the termination of nucleation and growth: the geometric mechanism by surface exhausting, the stoichiometric mechanism by the consumption of active surface sites and the systemic mechanism by the time dependence of the supersaturation of the initial phase as the thermodynamic driving force of the phase transition. The special role of time-dependent supersaturation in truncating the nucleation process is discussed by means of numerical simulations of the model equations. It could be shown that some—until now—poorly understood experimental findings concerning phase transition kinetics at electrodes, as for example, the occurrence of instantaneous homogeneous nucleation at the mercury electrode or of non-integer Avrami slopes for heterogeneous nucleation at single crystal electrodes, can be explained easily in the frame of the presented model.