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The Study On Luminescence Properties Of M2SiO4: Dy3+ (M=Ca, Sr, Ba) Phosphors

Posted on:2010-08-06Degree:MasterType:Thesis
Country:ChinaCandidate:X R ZhouFull Text:PDF
GTID:2178360278952401Subject:Optics
Abstract/Summary:PDF Full Text Request
White LED has attracted much interest in the field of illumination due to its own superiorities such as low voltage, long lifetime, environmental protection, and so on. The single matrix white light phosphor becomes the focus of light conversion materials' research because of its stability of color and good property of color deoxidization.M2SiO4: Dy3+(M=Ca, Sr, Ba) phosphors for WLED were prepared by high temperature solid-state reaction method. The structure and emission spectrum excited by near violet light were investigated. The X-ray power diffraction data of M2SiO4:Dy3+(M=Ca, Sr, Ba) are in agreement of JCPDS standard card which indicates that single phase M2SiO4: Dy3+(M=Ca, Sr, Ba) phosphors can be obtained by such synthesis process.The excitation spectra of M2SiO4: Dy3+ show strong absorption near 325nm,350nm,365nm and 386nm due to 6H15/2→6P3/2,6H15/2→6P7/2,6H15/2→6P5/2,6H15/2→4M21/2transition of Dy3+. The emission light is at about 479nm,491nm,571nm under 386nm UV excitation. The emission at 479nm and 491nm (Blue) attribute to the 4F9/2→6H15/2 transition and 571nm (Yellow) attributes to the 4F9/2→6H13/2 transition. White light is generated by mixing the two colors. The color coordinates(CIE) analysis indicates Ca2SiO4:Dy3+ is located at (0.30, 0.33) which is near white color region.The emission spectrum of Eu3+ and Dy3+ co-doped M2SiO4 phosphors under UV excitation were investigated for enhancing red emission. The emission spectrum consists of three bands. The blue and yellow band attribute to Dy3+ ions and the red band from 610nm to 620nm attributes to the 5D0—7F2 transition of Eu3+ ions. The emission intensity of red band is enhanced comparatively.Still we prepared and analyzed (Sr1-xMx)2SiO4: Dy3+(M=Ca, Ba) phosphors for their change rules of Y/B ratio under UV excitation. The increase of Ca2+ ions in (Sr1-xCax) 2SiO4: Dy3+ made the whole emission spectrum enhanced and the Y/B ratio is increased from 0.46 to 0.92. The increase of Ba2+ ions in (Sr1-xBax)2SiO4: Dy3+ made the blue band emission declined while the yellow band and Y/B ratio is are increased first then declined.As a result, the emission intensity of the yellow band can be controlled by changing the sort and content of the alkaline-earth metals thus the color coordinates of the phosphors will located at the white light region. This is significant for the spectrum characteristic study of Dy3+ ions doped phosphors.There are 22 figures, 5 tables and 42 references in this paper.
Keywords/Search Tags:Single matrix white phosphor, Dy3+, solid state lighting, white LED
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