Pechini sol-gel deposition and luminescence properties of Y3Al5−xGaxO12:Ln3+ (Ln3+=Eu3+, Ce3+, Tb3+; 0≤x≤5) thin films

Rare earth ions (Eu3+, Ce3+ and Tb3+)-doped Y3Al5−xGaxO12 (0≤x≤5) films were deposited on quartz glass substrates by a simple Pechini sol-gel method. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), thermogravimetric and differential thermal analysis (TG-DTA), atomic force microscopy, field-emission scanning electron microscope, photoluminescence spectra, and lifetimes were used to characterize the resulting films. The results of XRD indicated that the films began to crystallize at 900 °C and fully crystallized at 1000 °C. Both the results of FT-IR spectra and TG-DTA were in agreement with those of XRD. Uniform and crack-free films annealed at 1000 °C were obtained with an average grain size of 480 nm, a root mean square roughness of 13 nm and a thickness of 287 nm. The doped Ln3+ ions showed their characteristic emission in crystalline Y3Al5−xGaxO12 films, i.e., Eu3+5D0-7FJ (J=1, 2, 3, 4), Ce3+ 5d-4f and Tb3+5D3, 4-7FJ (J=6, 5, 4, 3) emissions, respectively. The optimum doping concentrations of the Eu3+, Ce3+ and Tb3+ were determined to be 1.5, 1.0, and 4.0 mol% of Y3+ in Y3Al5O12 films, respectively. At the same time, the effects of the contents of Ga3+ (x) in Y3Al5−xGaxO12 films on the luminescence properties of Ln3+ were also investigated.