Effect of the Rate of Mixing on Kinetic and Morphological Parameters of the Growth of Amorphous Silica Nanospheres Obtained According to Stöber

Abstract

Real-time calorimetric and conductometric analyses are used in synthesizing silica globules. The dependence of the initial rate of the sol synthesis reaction on the rate of the reaction mixture mixing is obtained. Regions of mixing that correspond to the diffusion and kinetic characters of synthesis are revealed in the ratio of components Si(OC₂H₅)₄ : H₂O : NH₃⋅H₂O − 0.2 : 18.9 : 2.0 (mol L⁻¹). The kinetic region lies in the range of mixing frequencies 7–23 Hz, of which the rate of the constant process and quality of grown nanospheres are characteristic, and the range of diffusion up to 7 Hz with varying parameters of synthesis. SEM photographs of samples are analyzed, and their average dimensions and deviations from them are determined for different rates of mixing. Morphological defects of nanospheres grown in the mode of diffusion synthesis are noted.