Comparative study on nucleation behavior of silica spheres seeded with silica and magnetite

This study investigates silica growth processes using homogenous silica spheres and heterogeneous magnetite nanoparticles as seeds.For silica seed particles, growth occurred through the condensation of hydrolyzed tetraethyl orthosilicate (TEOS) onto the silanol groups present on the particle surface.This mechanism resulted in a consistent increase in sphere diameter, with the growth rate plateauing after several regrowth cycles, likely due to the depletion of active surface silanol groups.In contrast, a distinct growth behavior was observed for magnetite seeds.Electrostatic attraction between the negatively charged silica precursors and positively charged magnetite particles, confirmed by zeta potential measurements, induced heterocoagulation.This process reduced the number of effective nucleation sites, leading to the formation of significantly larger composite spheres compared to the neat silica system.