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X2–Y2SiO5:A (A=Eu3+, Tb3+, Ce3+) phosphor films and their patterning were fabricated by a sol–gel process combined with a soft lithography. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), atomic force microscopy (AFM), scanning electron microscopy (SEM) optical microscopy and photoluminescence (PL) were used to characterize the resulting films. The results of XRD indicated that the films began to crystallize at 900 °C with X1–Y2SiO5, which transformed completely to X2–Y2SiO5 at 1250 °C. Patterned thin films with different band widths (5 μm spaced by 5 μm and 16 μm spaced by 24 μm) were obtained by a soft lithography technique (micromoulding in capillaries, MIMIC). The SEM and AFM study revealed that the nonpatterned phosphor films were uniform and crack free, and the films mainly consisted of closely packed grains with an average size of 350 nm. The doped rare earth ions (A) showed their characteristic emissions in X2–Y2SiO5 phosphor films, i.e., 5D0–7FJ (J=0,1,2,3,4) for Eu3+, 5D3, 4–7FJ (J=6,5,4,3) for Tb3+ and 5d (2D)–4f (2F2/5, 2/7) for Ce3+, respectively. The optimum doping concentrations for Eu3+, Tb3+ were determined to be 13 and 8 mol% of Y3+ in X2–Y2SiO5 films, respectively. [Copyright &y& Elsevier]

Abstract: Rare earth ions (Eu3+, Ce3+ and Tb3+)-doped Y3Al5−x Ga x O12 (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−x Ga x O12 films, i.e., Eu3+ 5D0-7F J (J=1, 2, 3, 4), Ce3+ 5d-4f and Tb3+ 5D3, 4-7F J (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−x Ga x O12 films on the luminescence properties of Ln3+ were also investigated. [Copyright &y& Elsevier]

Thin film phosphors with compositions of RP1−xVxO4: A (R=Y, Gd, La; A=Sm3+, Er3+; x=0, 0.5, 1) have been prepared by a Pechini sol–gel process. X-Ray diffraction, atomic force microscopy (AFM), photoluminescence excitation and emission spectra were utilized to characterize the thin film phosphors. The results of XRD showed that a solid solution formed in YVxP1−xO4: A film series from x=0 to x=1 with zircon structure, which also held for GdVO4: A film. However, LaVO4: A film crystallized with a different structure, monazite. AFM study revealed that the phosphor films consisted of homogeneous particles ranging from 90 to 400 nm depending on the compositions. Upon short ultraviolet excitation, the films exhibit the characteristic Sm3+ 4G5/2–6HJ (J=5/2, 7/2, 9/2) emission in the red region and Er3+ 2H11/2, 4S3/2–4I15/2 emission in the green region, respectively. With the increase of x values in YVxP1−xO4: Sm3+ (Er3+) films, the emission intensity of Sm3+ (Er3+) increases due to the increase of energy transfer probability from VO43− to Sm3+ (Er3+). Due to the structural effects, the Sm3+ (Er3+) shows similar spectral properties in YVO4 and GdVO4 films, which are much different from those in LaVO4 film. [Copyright &y& Elsevier]