Eu3+ (2.5 at.%) and Tb3+ (0.005-0.01 at.%) co-doped gadolinium and yttrium oxide (Gd2O3 and Y2O3) powders and films have been prepared using the sol-gel process. High density and optical quality thin films were prepared with the dip-coating technique. Gadolinium (III) 2,4-pentadionate and yttrium (III) 2,4-pentadionate were used as precursors, and europium and terbium in their nitrate forms were used as doping agents. Chemical and structural analyses (infrared spectroscopy, X-ray diffraction and high-resolution transmission electron microscopy) were conducted on both sol-gel precursor powders and dip-coated films. The morphology of thin films heat-treated at 700 degrees C was studied by means of atomic force microscopy. It was shown that the highly dense and very smooth films had a root mean roughness (RMS) of 2 nm +/- 0.2 (A = 0.0075 Tb3+) and 24 nm +/- 3.0 (B = 0.01 Tb3+). After treatment at 700 degrees C, the crystallized films were in the cubic phase and presented a polycrystalline structure made up of randomly oriented crystallites with grain sizes varying from 20 to 60 nm. The X-ray induced emission spectra of Eu3+- and Tb3+-doped Gd2O3 and Y2O3 powders showed that Tb3+ contents of 0.005, 0.0075 and 0.01 at.% affected their optical properties. Lower Tb3+ concentrations (down to 0.005 at.%) in both systems enhanced the light yield. (C) 2009 Elsevier B.V. All rights reserved.