Structural properties of electrophoretically deposited europium oxide nanocrystalline thin films

The structural properties of nanocrystalline europium oxide (Eu₂O₃) thin films, produced via electrophoretic deposition (EPD), were investigated. We found that EPD from our Eu₂O₃ nanocrystal solutions yielded both translucent films, with uniform size and distribution of the microstructure, and opaque films, with marked anisotropy to the size and distribution of the constituents of the microstructure. The disparity in the film morphology arose from the initial temperature conditions of the nanocrystal solution. The translucent films, produced from pre-chilled (−25 °C) EPD solutions, were bimodal films, comprised of homogeneous, tightly packed, glassy nanocrystalline films interspersed with micron-sized nanocrystal aggregates. In contrast, the opaque films, produced from room temperature solutions, consisted of an irregularly distributed and shaped microstructure. The evolution of the microstructure was monitored for the chilled samples as a function of film thickness (deposition time) and juxtaposed with the resultant structure of the room temperature film. Optical microscopy and scanning electron microscopy were employed to characterize the films.