Electrophoretic Deposition of Flake-Shaped ZnO Nanoparticles

Abstract

ZnO films have been grown on different substrates by using a variety of fabrication techniques. In the present work, we discuss the results on the preparation of ZnO films by electrophoretic deposition (EPD) starting from synthetic flake-shaped nanoparticles. The critical parameters related to the preparation of aqueous colloidal suspensions have been analyzed. Dispersing conditions have been evaluated in terms of particle/cluster morphology, electrokinetic properties, i.e., particle size distribution and cationic surface functionality, and zeta potential. EPD parameters for film assembly have been selected. Depending on both the particle morphology and the solid's concentration in the colloidal system, different orientation effects have been observed in the built structure. For a low ZnO concentration, independent clusters arrive at the Ni substrate where the large dimension of the ZnO flakelike nanoparticles align with the surface of the substrate. When the solid's concentration increases, such ordering is not observed. The electrical resistivity measured by the four-point probe method evidences the presence of a ZnO film with unusually high electrical resistivity for undoped ZnO. ? 2009 The Electrochemical Society.