Model 4 Non-Steady State Vacancies and Atoms

This model employs non-steady state equations for vacancies and B species. The basic equations can be formulated as follows 

From these relations, one may conclude that the main feature of each solution is that the shrinkage velocity is controlled by a slower component Indeed, if 

the less the ratio Da/Db, the slower the shrinkage of a shell proceeds. This means that although a nanoshell is generally unstable, it may be a long-hving 

Similar to Model 3, let us proceed to new variables, having fixed the boundaries in the following way 

The numerical solution of the above-stated problem confirms the main result, according to which the time of a shell shrinkage is approximately inversely proportional to the ratio A/B = Da/ Db  

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