shown in the bottom of Figure A. As a result, the first derivative, dG/dc i , as well as the driving force for phase separation, increase progressively between the binodal and spinodal lines. Further, through the classical relation of the volumetric change in Gibbs free energy and the critical energy barrier for nucleation, ∆G * , ∆G * ∝ 16π 3 • γ 3 (∆G) 2 , with γ being the surface tension, we can state a lowering of the critical energy barrier when going deeper into the binodal region. This translates directly to an increase in the nucleation rate J (and nucleation constant k being proportional to J) in a thermally activated process through the relation J ∝ e Analogously, the exponential dependence of the relative size distribution (RSD) on the kinetic constant can be rationalized. The probability of a nucleating cluster crossing the critical size and becoming a stable particle, a statistical, thermally activated process, depends exponentially on the height of the energy barrier. Thus, for a low energy barrier the probability of nucleation is high and all stable nuclei will form over a very confined time interval and grow uniformly to ACC nanoparticles with a narrow size distribution. On the contrary, when the energy barrier is high, the likelihood of nucleation decreases, spreading the nucleation process over a longer period. Consequently, the first nuclei to form will have already grown to a certain size by the time the last stable seeds nucleate, resulting in a broader particle size distribution. This narrowing in size distribution through fast kinetics at high supersaturation was proposed in 1950 by LaMer; it is visible in Figure , where the RSD of particles increases exponentially with decreasing nucleation kinetics. We can thus summarize the thermodynamic driving force variation within the binodal region of phase separation. Following the black arrow on the green line in Figure A, going deeper into the binodal region, we find an increase in formation kinetics concomitant with a lowering in the critical nucleus size (Figure ) and an analogous lowering in the final Mg-ACC nanoparticle size (Figure ). Based on the statistical nature of particle formation, this directly translates to a lower size distribution of the formed nanoparticles.