2. Reaction mechanisms

2.1 Germination mechanisms

The mechanisms envisaged for surface sprouting are inspired by those of homogeneous sprouting, and involve several stages, including the formation of defects in the initial phase (gaps, interstitials, etc.) and the aggregation of these defects. The thermodynamic approach leads to the expression of the free enthalpy of formation of an aggregate of defects as a function of their number, for a given form of aggregate. Generally speaking, the molar free enthalpy associated with the formation of an aggregate containing i species is written as :