In-situ evaluation of particle size distribution of ZrO2-nanoparticles obtained by sol–gel

• In-situ synthesis of zirconia via sol–gel was investigated.
• In the acetic medium, the particle size stayed mostly below 100 nm.
• With the addition of NaCl, the maximum particle size reached 71 nm.
• The probability of a dynamic equilibrium.
• Formation of the primary particles after secondary, resulting in agglomeration.

In this study the in-situ synthesis of zirconia via sol–gel was investigated in order to relate the influence of the processing parameters on particle size distribution. Zirconium n-propoxide was used as the precursor, n-propanol as solvent and several parameters were investigated, such as pH, reaction medium, synthesis time and temperature. The particle sizes and the polydispersion of colloidal dispersions were determined in situ using dynamic light scattering. In acetic medium, the particle size remained mostly below 100 nm. With the introduction of NaCl, the maximum particle size reached 71 nm. For other reaction media (HNO3 and without acid or base), the largest particle size was in the order of micrometers. The comparison of the different synthesis routes investigated did not enable us to observe one trend related to increased particle size when compared to reaction times in the synthesis of zirconia. This work aims to show how the reaction medium influence in obtaining a colloidal dispersion with nanometric sizes obtained from the sol–gel process.

At 27 °C the particles tend to agglomerate increasing size. After this time, the agglomerated particles tend to decrease their size. When samples were refluxed under reflux at 70 °C, a maximum particle size of 100 nm was observed after 2 h. In 3 h, the average size reached 280 nm. In the presence of NaCl at 27 °C a maximum particle size of 70 nm after 2 h was observed.Figure optionsDownload as PowerPoint slide