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Preparation and Photoluminescence of Rare-earth Doped Slilican Phosphors for White Leds

Author: PanZhengZuo
Tutor: FuRenLi
School: Nanjing University of Aeronautics and Astronautics
Course: Materials Science
Keywords: ions doping phosphor high temperature solid state reaction Pechini-sol-gel route energy transfer
CLC: O482.31
Type: Master's thesis
Year: 2010
Downloads: 185
Quote: 1
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Abstract


Rare-earth doped silicates phosphors were prepared by high temperature solid state reaction （SSR） and Pechini-sol-gel route, respectively. Using X-ray Diffractometer （XRD）, Scanning Electron Microscope （SEM） and fluorescent spectrophotometer, the influences of different doping ions including alkaline-earth metal ions and rare-earth ions, and preparing methods on phase compositions, microstructures and optical properties of silicates phosphors were studied. Experimental result show: （ⅰ） Comparing with SSR, Pechini-sol-gel route synthesized pure single phase phosphors with uniform phosphor particles and beneficial spherical shape. （ⅱ） Ba2+-doped Sr2SiO4:Eu2+ phosphors (BaxSr2-x-ySiO4:Euy2+) show two intense emission bands at green and yellow regions of spectrum, originated from Eu2+ ions accommodated at two different sites in the host crystal, whose peaks depend on the concentrations of Ba2+ and Eu2+ ions. Additional, Ba2+-doping favored the stabilization ofα′-Sr2SiO4 phase. Intense and broad excitation spectra and emission spectra were obtained by doping Ca2+ or Ba2+ ions in Li2SrSiO4:Eu2+ phosphor, which show blue emitting and yellow emitting in chromaticity diagram, respectively. （ⅲ） The energy transfer from Ce3+ to Eu2+ （Ce→Eu） was demonstrated to be the type of electric dipole-dipole interaction in the Eu2+ and Ce3+ codoped Li2SrSiO4 phosphor. There were broad blue and yellow emissions peaked at 400 nm and 570 nm, respectively. It was observed that Li2SrSiO4:0.5%Ce3+,0.75%Eu2+ displayed the highest emission intensity, and higher concentration of Eu2+ resulted in concentration quenching.

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CLC: > Mathematical sciences and chemical > Physics > Solid State Physics > Solid nature of the > Optical Properties > Luminescence
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