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Wang F.,Kunming University of Science and Technology | Yang B.,Key Laboratory for Nonferrous Vacuum Metallurgy of Yunnan Province | Yang B.,State Key Laboratory Breed Base Of Complex Nonfer Met Rsrc Clear Utiliz In Yunnan Prov | Liu D.,Key Laboratory for Nonferrous Vacuum Metallurgy of Yunnan Province | And 7 more authors.
Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy | Year: 2014

As a novel red long afterglow phosphor, Si4+ and Ti4+ ion codoped Gd2O2S:Eu phosphor with spherical morphology, sub-micrometer size and narrow particle size distribution was synthesized by solid-state reaction in vacuum. The vacuum synthesis mechanism was determined by thermal analysis. The crystal structure, luminescence properties and mechanisms were investigated respectively by XRD, SEM and fluorescence spectrophotometer. The results show that well-crystallized Gd2O2S:Eu,Si,Ti phosphors are of hexagonal structure which is in agreement with the standard powder peak positions of Gd2O2S hexagonal phase. It displays pure red emission because of the strongest peaks at 627 nm and 617 nm which are attributed to energy transfer (5D0- 7F2). There is a little blue shift of charge transfer excitation band in the excitation spectra between the bulk and sub-micrometer-sized samples, which may stem from size dependent shift and different lattice distortion in the position of the Eu3+-ligand electron transfer absorption/excitation band. To further study the influence of the impurities in Gd2O2S:Eu crystals on crystal growth, the simulated crystal face and its XRD patterns were illustrated. The preferred orientation of crystal growth changed from crystal face (1 0 1) to (1 0 0) thus to result in different luminescence mechanisms.

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