Krause, J., Lisinski, S., Ratke, L. et al. J Sol-Gel Sci Technol (2008) 45: 73. doi:10.1007/s10971-007-1624-9
The gelation of alcogels mixed with microparticles of the nonlinear optical material BaTiO3 was studied with Particle Image Velocimetry (PIV). It is shown that the distribution of the microparticles in the gel is homogeneous and that the gelation occurs continuously throughout the gel body. We demonstrate that PIV is a useful method to study the gelation kinetics: The transition from a colloidal solution to a gel can be measured without any assumption on the rheology of the colloidal solution. The detected linear decrease of the flow velocity with time is described as the linear part of the critical behavior.