Since during CSP Stage I the partic

Since during CSP Stage I the particles are not in direct contact the only active process is Ostwald ripening, which was observed by Taveri and co-workers [26] during ICC of silica spheres. The Ostwald ripening rate (i.e. the derivative of the average particle size with respect to time) is directly proportional to the solubility of the particles in the matrix phase (in this case in the liquid). Since the application of external pressure increases the solubility by a factor exp (Pext(Vs − Vl)/RT), this leads to a consistent increase in the rate of coarsening.Note that such proportionality between da/dt and exp (Pext(Vs − Vl)/RT) is valid for both Ostwald ripening controlled by interface dissolution/precipitation reactions or by diffusion through the liquid phase, as qualitatively sketched in Figure 7. Starting from thewell-known coarsening equations [29] and combining them with Eq. (4) we can define the Ostwald ripening equations for CSP Stage I (spherical particles) in the case of diffusion-controlled coarsening: