Much detailed discussion about effect
of NH3 and H2O on the particle size could be seen in Section 3.3 and
4. Moreover, Bougush et al. [19] 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.