] found that near the maximum achievable size for any given TEOS concentration, monodispersity could hardly be achieved and bimodal final particle size distributions were commonly observed.
However, in our experiments, near the maximum achievable size (873 nm) for 0.75 M TEOS, monodispersity is often achieved and only the bimodal final particle size distribution can be observed at 0.15 M NH3 and 4.7 M H2O (A1 in Table 3). Further investigations on this phenomenon are underway to understand completely the formation mechanism of particles in this reaction system.