High-optical quality Lu2O3:Eu3+ 5 mol%, X Tb3+ (X=0-0.04 mol%) thin films were prepared by the sol-gel process and dip-coating technique. The procedure was as follows: lutetium, europium and terbium nitrates were used as precursors, and ethanol as a solvent. Etylenglycol (EG) was added as a sol stabilizer, and the pH was adjusted by acetic acid. After 10 dipping-cycles, followed by an annealing process (600-900 degrees C) for 1 h, transparent, smooth and crack-free films (ra = 8-9 nm) were formed. The X-ray diffraction (XRD) results showed crystallized films into the cubic structure at 800 degrees C. The ellipsometry results showed that the thickness of the films varied from 1 to 1.4 mu m at 1000 and 600 degrees C, respectively. Finally, the films presented a typical Eu3+ red emission at 611 nm (D-5(0) -> F-7(2)); furthermore, the effect of the Tb3+ content showed that the highest emission intensity corresponded to the lower Tb3+ content. (C) 2015 Elsevier Ltd. All rights reserved.