Photoluminescence Enhancement of PEG-Modified YAG:Ce~(3+) Nanocrystal Phosphor Prepared by Glycothermal Method

摘要

Y_3Al _5O_(12):Ce~(3+) (YAG:Ce~(3+)) nanocrystals were synthesized in 1,4-butylene glycol (BG) with and without poly(ethylene glycol) (PEG) by the glycothermal method.The internal quantum efficiency of the photolu-minescence (PL) corresponding to the 5d -> 4f transition of Ce~(3+) in the YAG:Ce~(3+) nanocrystal increased from 21.3 to 37.9% by addition of PEG,while no appreciable change in the primary particle size,the crystallite size,and the lattice distortion was recognized by transmission electron microscopy and X-ray diffractometry.The thermogravimetry-differential thermal analysis,Fourier transform infrared absorption spectroscopy and ~1H->~(13)C cross-polarization magic angle spinning nuclear magnetic resonance (CP-MAS NMR) confirmed the preferential coordination of PEG to the YAG:Ce~(3+) nanocrystal.~(27)A1 single-pulse excitation MAS NMR reveals that the ratio of the 4-fold coordination site to the 6-fold coordination site increased from 0.53 to 0.72 by addition of PEG.We conclude that the surface modification of the YAG:Ce~(3+) nanocrystal by PEG induces the surface passivation,the prevention of the oxidation of Ce~(3+) to Ce~(4+),the promotion of the incorporation of Ce~(3+) into YAG and the local structural rearrangement,resulting in the PL enhancement.