Uniform growth of colloidal particles via internal gelation process

Abstract

Nanocrystalline materials with excellent properties are of great interest, but little is known about how to maintain grain size uniformity, which is essential for the reliability of nanomaterials. A fascinating question is whether it is possible to achieve a narrow size distribution of colloidal clusters in the gel. The nanocrystalline materials could be prepared by sintering the gel. Based on the above ideas, the growth mechanism of colloidal particles in the zirconium-based sol-gel transition is studied. The study showed that the primary zirconium hydroxide colloidal particles based on zirconium tetramers would aggregate into clusters of about 70 nm due to the Brownian motion. The clusters would form the Zr-O-Zr bonds and the three-dimensional gel network structure. The three-dimensional gel network could restrict the movement of free water molecules, making the zirconium sol instantly transform into the zirconium gel. The aging temperature would not affect the size of the colloidal clusters in the zirconium gel. Therefore, the uniform nanocrystalline zirconia could be prepared by sintering zirconium gel, which demonstrated the superiority of the internal gelation process for preparing nanocrystalline materials.