Preparation, patterning and luminescent properties of nanocrystalline Gd_2O_3:A (A = Eu~(3+), Dy~(3+), Sm~(3+), Er~(3+)) phosphor films via Pechini sol-gel soft lithography

摘要

Nanocrystalline Gd_2O_3:A (A = Eu~(3+), Dy~(3+), Sm~(3+), Er~(3+)) phosphor films and their patterning were fabricated by a Pechini sol-gel process combined with a soft lithography. X-ray diffraction (XRD), atomic force microscopy (AFM), scanning electron microscopy (SEM) and optical microscopy, UV/vis transmission and photoluminescence (PL) spectra as well as lifetimes were used to characterize the resulting films. The results of XRD indicated that the films began to crystallize at 500°C and that the crystallinity increased with the elevation of annealing temperatures. Uniform and crack free non-patterned phosphor films were obtained by optimizing the composition of the coating sol, which mainly consisted of grains with an average size of 70 nm and a thickness of 550 nm. Using micro-molding in capillaries technique, we obtained homogeneous and defects-free patterned gel and crystalline phosphor films with different stripe widths (5, 10, 20 and 50 μm). Significant shrinkage (50%) was observed in the patterned films during the heat treatment process. The doped rare earth ions (A) showed their characteristic emission in crystalline Gd_2O_3 phosphor films due to an efficient energy transfer from Gd_2O_3 host to them. Both the lifetimes and PL intensity of the rare earth ions increased with increasing the annealing temperature from 500 to 900°C, and the optimum concentrations for Eu~(3+), Dy~(3+), Sm~(3+), Er~(3+) were determined to be 5, 0.25, 1 and 1.5 mol% of Gd~(3+) in Gd_2O_3 films, respectively.