title: Photoluminescence enhancement of PEG-modified YAG:Ce3+ nanocrystal phosphor prepared by glycothermal method.
abstract: Y3Al5O12:Ce3+ (YAG:Ce3+) 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 photoluminescence (PL) corresponding to the 5d --> 4f transition of Ce3+ in the YAG:Ce3+ 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 --> 13C cross-polarization magic angle spinning nuclear magnetic resonance (CP-MAS NMR) confirmed the preferential coordination of PEG to the YAG:Ce3+ nanocrystal. 27Al 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:Ce3+ nanocrystal by PEG induces the surface passivation, the prevention of the oxidation of Ce3+ to Ce4+, the promotion of the incorporation of Ce3+ into YAG and the local structural rearrangement, resulting in the PL enhancement.
authors.affiliation: Department of Applied Chemistry, Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama 223-8522, Japan.
authors.forename: Ryo
authors.initials: R
authors.lastname: Kasuya
authors.forename: Tetsuhiko
authors.initials: T
authors.lastname: Isobe
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Kuma
authors.forename: Junichi
authors.initials: J
authors.lastname: Katano
mesh_terms: D000327:Adsorption; D017607:Aluminum Compounds / Q000737:chemistry*; D002072:Butylene Glycols / Q000737:chemistry*; D002563:Cerium / Q000737:chemistry*; D003460:Crystallization; D049449:Luminescence; D046529:Microscopy, Electron, Transmission / Q000379:methods; D053758:Nanoparticles / Q000737:chemistry*; D010316:Particle Size; D010777:Photochemistry; D011092:Polyethylene Glycols / Q000737:chemistry*; D012680:Sensitivity and Specificity; D013499:Surface Properties; D013696:Temperature; D015019:Yttrium / Q000737:chemistry*
chemical_list: D017607:Aluminum Compounds; D002072:Butylene Glycols; D002563:Cerium; D011092:Polyethylene Glycols; D015019:Yttrium; C039681:1,4-butanediol