Synthesis and Surface Modification of Metal Oxide Nanoparticles for Functional Nanocomposite and Thin Film Applications

Abstract

In this work the use of ZrO2 and BaTiO3 nanoparticles for the fabrication of thin films and nanocomposites is reported. The nanoparticles were synthesized through the non-aqueous benzyl alcohol route. It is shown that for ZrO2 nanoparticles the material of the reaction vessel and the reaction temperature have a strong influence on their crystal phase composition. Also, the effect of the use of co-solvents during the synthesis of BaTiO3 nanoparticles is shown. Here, the selected co-solvents have a strong influence on their crystallite size. Subsequently to the synthesis, the preparation of stable dispersions through surface modification of the nanoparticles is investigated. It is shown that by using minor amounts of ligand highly stable dispersions of ZrO2 and BaTiO3 can be achieved. Additionally, it is shown that the surface modified nanoparticles could be simply redispersed after induced precipitation. The dispersions were then successfully employed for the fabrication of nanocomposites and thin films. For the nanocomposites, the influence of the change in the surface chemistry on the particle-polymer interface and the properties of the nanocomposites are examined. It is shown that the surface chemistry as well as the embedding procedure of the modified nanoparticles has a strong impact on the mechanical properties of the composite, inducing an increase of up to 12 % for the maximum tensile strength and 11 % for the Young’s modulus, at a particle loading of only 2 wt% ZrO2. As for the thin films, the effect of the choice of ligand, its concentration and the drying procedure on the structure of the thin films is briefly investigated. Furthermore, the implementation of these thin films as a dielectric for capacitors, which are integratable into printed circuit boards, is shown. These capacitors exhibited outstanding dielectric properties, much better than the state of the art integratable capacitor solutions.