Large-scale Patterning of TiO2 nano powders using micro molds

For the fabrication of ceramic micro-scale patterns over a wide area, the Micro-molding in Capillaries (MIMIC) method is can be used by applying low solid loading colloidal suspensions of nanopowders. However, to uniformly form thick films from low solids loading suspensions, it is necessary that the additional spontaneous process of concentrating the suspensions in the molds occurs and is successfully accomplished, after the ordinary MIMIC process caused by capillary action. This concentration of suspension occurs as a result of inflow of the suspension from the entrance along with solvent evaporation from the exit of the mold. Therefore, the suspension preparation is important in order that the particles flow in due to the flow of the solvent. In this study, we determined the required condition of the suspension preparation by fabricating films from aqueous and ethanol-based suspensions of TiO2 nanopowders. By comparing the uniformity of the fabricated films and the particle distributions of the suspensions, it was found that the condition required for uniform patterning over a wide area is to disperse the nanoparticles into their primary size.