Hydrolysis and condensation of metal-organic precursors is an interesting process for the design of Nanomaterials, in particular de fabrication of nanoparticles for emerging applications. One issue of this process is the control of the chemical stability of the solutions and the minimization of the condensation-nucleation processes at the desired stage of particle formation. For the fabrication of nanoparticles, process parameters have to be adjusted in order to avoid gelation or to stop particle growth in the solution. Common approaches to control the chemical reactions in the “sol” state have been applied by using complexing agents in order to control precursor reactivity toward the hydrolysis and condensation. Once the nanoparticles are formed, particle growth or network formation needs to be controlled in order to avoid the formation of clusters, agglomerates or gelation. Two ways commonly used to limit particle growth or cluster formation has been by limiting solution concentration and by surface treating the nanoparticles. In this work, a process to stabilize sol-gel solutions without additives is presented. The process allows significant reduction of the kinetics of condensation resulting in controlled nanoparticles size in relatively high concentration solution which is stable over the time. The finding is also interesting for practical purposes. TMOS was used to produce silica nanoparticles in the two step thermal condensation process. Stable silica solutions with colloids of 70 nm were produced. The solutions were stable for more than six month. The solutions were characterized by laser granulometry, turbidity and viscosity techniques.

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