Sol–gel deposition and luminescence properties of lanthanide ion-doped Y_2(1-x)Gd_2xSiWO₈ (0≤x ≤1) phosphor films

Abstract

Y_2(1-x)Gd_2xSiWO₈ : A (0≤x≤1; A=Eu³⁺, Dy³⁺, Sm³⁺, Er³⁺) phosphor films have been prepared on silica glass substrates through the sol–gel dip-coating process. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), thermogravimetric and differential thermal analysis (TG-DTA), atomic force microscope (AFM), scanning electron microscopy (SEM) and photoluminescence spectra as well as lifetimes were used to characterize the resulting films. The results of the XRD indicated that the films began to crystallize at 800 °C and crystallized completely at 1000 °C. The AFM and SEM study revealed that the phosphor films, which mainly consisted of closely packed grains with an average size of 90–120 nm with a thickness of 660 nm, were uniform and crack free. Owing to an efficient energy transfer from the WO₄^2- groups to the activators, the doped lanthanide ion (A) showed its characteristic f–f transition emissions in crystalline Y_2(1-x)Gd_2xSiWO₈ (0≤x≤1) films. The optimum concentrations for Eu³⁺, Dy³⁺, Sm³⁺, Er³⁺ were determined to be 21, 5, 3 and 7 mol % of Y³⁺ in Y₂SiWO₈ films, respectively. The above lanthanide ions showed higher emission intensity for 0<x≤1 than for x=0 in Y_2(1-x)Gd_2xSiWO₈ films.