Analysis of SiO2 particle size using photon correlation spectroscopy

In this study, fixed SiO2 particle sizes were observed using a photon correlation spectroscopy (PCS) system. PCS measurements were carried out using samples of fixed SiO2 particles uniformly dispersed on the surface of a cover glass and particles moving in a liquid. The monodispersed spherical SiO2 particles were made using the Stöber process with tetraethyl orthosilicate (TEOS) concentrations of 0.1 M, 0.2 M, and 0.3 M. The solid sample was made by fixing the particles on a cover glass by self-assembly, and the liquid sample was made by dispersing particles in distilled water. The fixed particle sizes on the surface were measured by PCS as 263.1 ± 21.7 nm, 309.3 ± 28.2 nm, and 425.4 ± 14.6 nm for TEOS concentrations of 0.1 M, 0.2 M, 0.3 M respectively. The corresponding liquid colloidal particle sizes were measured as 252.5 ± 8.0 nm, 322.8 ± 23.1 nm, and 423.2 ± 12.2 nm. The PCS show agreement with SEM images within ±9%.