title: Charge deformation and orbital hybridization: intrinsic mechanisms on tunable chromaticity of Y3Al5O12:Ce3+ luminescence by doping Gd3+ for warm white LEDs.
abstract: The deficiency of Y3Al5O12:Ce (YAG:Ce) luminescence in red component can be compensated by doping Gd(3+), thus lead to it being widely used for packaging warm white light-emitting diode devices. This article presents a systematic study on the photoluminescence properties, crystal structures and electronic band structures of (Y1-xGdx)3Al5O12: Ce(3+) using powerful experimental techniques of thermally stimulated luminescence, X-ray diffraction, X-ray absorption near edge structure (XANES), extended X-ray absorption fine structure (EXAFS) and ultraviolet photoelectron spectra (UPS) of the valence band, assisted with theoretical calculations on the band structure, density of states (DOS), and charge deformation density (CDD). A new interpretation from the viewpoint of compression deformation of electron cloud in a rigid structure by combining orbital hybridization with solid-state energy band theory together is put forward to illustrate the intrinsic mechanisms that cause the emission spectral shift, thermal quenching, and luminescence intensity decrease of YAG: Ce upon substitution of Y(3+) by Gd(3+), which are out of the explanation of the classic configuration coordinate model. The results indicate that in a rigid structure, the charge deformation provides an efficient way to tune chromaticity, but the band gaps and crystal defects must be controlled by comprehensively accounting for luminescence thermal stability and efficiency.
authors.affiliation: School of Materials Science and Engineering, Hefei University of Technology, Hefei 230009, China.
authors.forename: Lei
authors.initials: L
authors.lastname: Chen
authors.affiliation: School of Materials Science and Engineering, Hefei University of Technology, Hefei 230009, China.
authors.forename: Xiuling
authors.initials: X
authors.lastname: Chen
authors.affiliation: School of Materials Science and Engineering, Hefei University of Technology, Hefei 230009, China.
authors.forename: Fayong
authors.initials: F
authors.lastname: Liu
authors.affiliation: Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050, China.
authors.forename: Haohong
authors.initials: H
authors.lastname: Chen
authors.affiliation: School of Materials Science and Engineering, Hefei University of Technology, Hefei 230009, China.
authors.forename: Hui
authors.initials: H
authors.lastname: Wang
authors.affiliation: School of Materials Science and Engineering, Hefei University of Technology, Hefei 230009, China.
authors.forename: Erlong
authors.initials: E
authors.lastname: Zhao
authors.affiliation: School of Materials Science and Engineering, Hefei University of Technology, Hefei 230009, China.
authors.forename: Yang
authors.initials: Y
authors.lastname: Jiang
authors.affiliation: National Synchrotron Radiation Research Centre, Hsinchu 30076, Taiwan.
authors.forename: Ting-Shan
authors.initials: TS
authors.lastname: Chan
authors.affiliation: National Synchrotron Radiation Research Centre, Hsinchu 30076, Taiwan.
authors.forename: Chia-Hsin
authors.initials: CH
authors.lastname: Wang
authors.affiliation: National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei 230026, China.
authors.forename: Wenhua
authors.initials: W
authors.lastname: Zhang
authors.affiliation: Shanghai Synchrotron Radiation Facilities, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201204, China.
authors.forename: Yu
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Department of Chemistry, Anhui Science and Technology University, Fengyang 233100, China.
authors.forename: Shifu
authors.initials: S
authors.lastname: Chen