| Rear earth doped functional material in lighting region has been applied more and morecommonly. At present, the blue LED chip matched with yellow fluorescence phosphorpowders and ultraviolet LED chips coupled with blue/green/red phosphors are regarded as thetwo dominant white LED lighting source. And among them, the fluorescent powder materialis the crucial factor to realize the white light emission. Ca8Mg (SiO4)4Cl2(hereinafter referredto as CMSC) has stable crystal structure, as is an important matrix materials using in LED. Itbelongs to the cubic crystal department, and the type of crystal cell belongs to face centered,the space of Fd3m, and the crystal cell parameters a is1.5064nm.For CMSC, there are three cationic existing in the cells, named as the6coordinationCa2+(Ⅰ),8coordination of Ca2+(Ⅱ), and4coordination of cells Mg2+, which has differentsymmetry that is, C2v, C1, and Td group symmetry, respectively. Therefore, when activatorsion replace the matrix cation, three different replaced type of cells and three disparitysymmetries may presented. CMSC: Eu2+phosphor is recognized as a kind of good LEDmaterial for green light, it has stronger emission peak, and quite wide activate spectrum band.Ce3+doped CMSC can be effectively pumped by ultraviolet and blue light, combined withits high brightness and stable crystal structure, is expected to become an ideal candidate forwhite LED phosphor.The previous research mostly focused the fluorescence spectra of rare earth doped CMSC,however, the fluorescence spectrometer probe response curve is not straight and level thuscan’t reflect the true fluorescence spectrum of the relative spectrum power distribution.Therefore it is quite urgent to correct the fluorescence spectra so as to coordinate its true colorlocation.Based on this consideration, A series of Ce3+and Eu2+doped Ca8Mg(SiO4)4Cl2(CMSC)powder have been synthesized by high-temperature solid-state reaction. And the dopingconcentration of Ce3+and Eu2+are3%based on the quality of the matrix. Ce3+and Eu2+doped Ca8Mg(SiO4)4Cl2powder have been synthesized by introducing the processes optimized in the fabrication of CMSC. The structure of the crystal was investigated by X-raypowder diffraction (XRD) and the fluorescence spectra were also recorded and analyzed. Therelative spectral power distribution was obtained by spectral power calibration curve, and thecolor coordinates of samples were calculated and characterized, which provide a new designmethod for the green, blue three colors mixed white LED.The followings are results this work achieved:1.Ca8Mg(SiO4)4Cl2powder material has been prepared, and the optimized compositionof the host are CaCO3:MgO:SiO2:CaCl2=7:1:4:2, by adjusting the experiment process theoptimum fabrication parameters are realized. Based on this, a series of Ce3+and Eu2+dopedCa8Mg(SiO4)4Cl2powder have been synthesized successfully by high-temperature solid-statereaction.2.The relative spectral power distribution was obtained by spectral power calibrationcurve, and the color coordinates of samples were calculated and characterized. Ce3+and Eu2+doped Ca8Mg(SiO4)4Cl2samples present purplish-blue and green color under the excitation ofultraviolet radiation, and the corresponding color coordinates are (0.1573,0.0528) and(0.1540,0.4663), respectively. In Ce3+/Eu2+codoped Ca8Mg(SiO4)4Cl2powder, the additionof Ce3+changes the luminescent color obviously, and with the increasing concentration ofCe3+, the color coordinates move into the greenish blue color region.In Ce3+/Eu2+co-doped CMSC phosphors, with sensitizing the green emission of Eu2+,Ce3+co-doping changed the luminescence color from green to bluish-green, presenting apreferable mixed effect from two primary colors. Potential mixture of red phosphors willprovide the possibility in achieving the ideal white fluorescence under UV-LED excitation. |
PDF Full Text Request