Influence of annealing temperature on structural and optical properties of Lu2O3:Eu3+, Tb3+ transparent films

• Lu2O3:Eu3+, Tb3+ films were synthesized by sol–gel and by dip-coating technique.
• Effects of annealing treatment on structural and optical properties were studied.
• Optogeometrical characteristics of synthesized films were analyzed.
• X-ray diffraction results showed that Lu2O3:Eu3+, Tb3+ crystallizes at 700 °C.
• High reddish emission on transparent films with at least 1 μm thick was observed.

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 °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 °C. The ellipsometry results showed that the thickness of the films varied from 1 to 1.4 μm at 1000 and 600 °C, respectively. Finally, the films presented a typical Eu3+ red emission at 611 nm (5D0 → 7F2); furthermore, the effect of the Tb3+ content showed that the highest emission intensity corresponded to the lower Tb3+ content.

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