Synthesis of Silica Microspheres-Inspired by the Formation of Ice Crystals-With High Homogeneous Particle Sizes and Their Applications in Photonic Crystals

Silica microspheres (SMs) must possess the performances of desirable monodispersity, narrow particle size distribution, and high sphericity for preparing photonic crystals (PCs) and other materials such as microspheres reference material, etc. We have adopted the techniques of increasing reactant concentration and raising the temperature to improve the synthesis rate of SMs, gaining inspiration from the formation mechanism of ice crystals. SMs with uniform particle sizes (polydispersity index less than 0.05) and good spherical features were fabricated through homogeneous nucleation. The mathematical relationship between particle sizes of SMs and reactant concentrations is further fitted. High accuracy of the regression equation is verified by an F-test and verification experiment. Highly ordered PCs (the stacking fault is about 1.5%, and the point defect is about 10^-3) with dense stacked opal structures have been obtained by self-assembly of SMs. In addition, highly ordered PCs (the stacking fault is about 3%, and the point defect is about 10^-3) with non-dense packed opal structure and inverse opal structure were successfully prepared. PCs of inverse opal structure were used to examine their response characteristics to identify ethanol, exhibiting good performance. Our research may provide significant inspiration for the development of other sorts of microspheres.