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Title: New highly efficient green phosphor for LEDs
Authors: Nazarov, Mihail
Tsukerblat, Boris
Noh, Do Young
Issue Date: Jun-2009
Publisher: CSIR
Abstract:  To develop a highly energy-efficient white light sources, one needs to design highly efficient yellow, green and red phosphors, which are able to absorb excitation energy of blue LEDs and generate emissions. In this paper, results on production of a new green multiphase thiogallate phosphor {SrGa2S4 + MgGa2O4}:Eu2+ with improved luminescence properties have been presented. The detailed XRD analysis, Raman spectroscopy and PL study have been carried out in order to enlarge the understanding of the radiative processes in {SrGa2S4 + MgGa2O4}:Eu2+, based on two different crystallographic phases {SrGa2S4} and {MgGa2O4}, prepared by solid state reaction at 900-1000°C during 4 h with a carbon reduction atmosphere. A model of 4f-5d optical transitions with due account for the electron-vibrational interaction is discussed. An approximate simple expression for the shape function of the broad vibronic bands with allowance for the terms corresponding to the emission (absorption) from both ground and first excited vibrational levels is given. Within this approximation we analyze the room temperature experimental data on the 4f-5d transitions in thiogallates doped with Eu2+ ions. The vibronic coupling parameters, Stokes shift and nephelauxetic effect for systems under study are estimated. The theoretical results are in a good agreement with the experimental data.
Page(s): 147-150
ISSN: 0975-1017 (Online); 0971-4588 (Print)
Source:IJEMS Vol.16(3) [June 2009]

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