Regensburg 2010 – scientific programme

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 40: Nanoparticles and Composite Materials I

CPP 40.5: Talk

Thursday, March 25, 2010, 10:30–10:45, H48

Manufacturing of barium titanate thin films with designed microstructure by a sol-gel process: in-situ SAXS investigation of the precursor system — •Tomasz Stawski, Sjoerd Veldhuis, Johan ten Elshof, Ole Göbel, Hessel Castricum, and Dave Blank — University of Twente, Inorganic Materials Science group, P.O. Box 217, 7500 AE Enschede, The Netherlands

Barium titanate (BTO) is used as a high-k dielectric material in multi-layer ceramic capacitors. The minimum BTO layer thickness that can be achieved commercially with the state of the art tape casting methods is about 1 um, which implies the use of starting powders with a particle size of ca. 200 nm. Further downsizing requires finer powders. Wet-chemical methods based on sol-gel reactions are among most thoroughly investigated, and can also be applied to make BTO. Knowledge of the size, shape and kinetics of primary sol-gel derived oligomeric nanostructures in solution is crucial to optimize the processing of functional oxide thin films from these solutions. The barium titanate sol-gel precursor system was analyzed by small angle X-ray scattering analysis at the DUBBLE beamline at the ESRF in Grenoble. BTO sols were formed in the reaction of barium acetate, tit! anium isopropoxide and water in glacial acetic acid and 2-methoxyethanol. The relationship between size and dimensionality of the oligomers, and the influence of synthesis conditions (temperature, concentrations of reactants) were investigated. Evolutionary, systematic changes in the radii of gyration (Rg) and internal structure of colloidal sols (characterized by the fractal dimension, Df) were monitored as a function of time.