Criterion for the minimum phase size
Figure 25.6 indicates the existence of solutions of the system of equations (24.8) for which the values of σ are negative. This occurs at critical drop sizes. The condition σ = 0 can be achieved both by raising the temperature near the critical temperature, so by decreasing the size of the drop. In the first case, the system is in the region of large thermal fluctuations and the selected radii are smaller than the average size of the fluctuations at a given temperature. In the second case, the ‘phase’ inside the drop becomes unstable due to the large fraction of the interphase region in the total volume of the drop (see Fig. 25.4).