Nanoparticle Synthesis of Willemite Doped with Cobalt Ions (Co0.05Zn1.95SiO₄) by an Epoxide-Assisted Sol−Gel Method

Willemite nanoparticles doped with divalent cobalt ions were synthesized by a sol−gel method using propylene oxide as a gelation agent. The resulting nanoparticles show a narrow size distribution with particles in the 30−50 nm range. A highly homogeneous wet gel was achieved by the formation of M−O−Si bonds (M = Zn, Co) during the hydrolysis and condensation of the precursor salts. This high homogeneity allows a substantial reduction of the calcination temperature and time required for the formation of the mixed oxide phase as compared to the solid-state and other sol−gel routes and therefore minimizes the aggregation of the nanoparticles during calcination.