| Much attention has been paid to plasma display panels (PDP) because it has the advantages of large scale screen, high brightness, fast response, broad visual angle, long lifetime. As the important ingredient in PDP device, phosphor affects the development and application of PDP device directly. The limitation of three primary color phosphors applied nowdays, especially to the poor color purity of the red-emitting phosphor (Y,Gd)BO3:Eu3+, can directly affect PDP performance. In addition, The commercial (Y,Gd)BO3:Eu3+phosphor cannot meet the demand of development in the area of PDP, because that phosphor is usually synthesized by conventional high temperature solid state reaction of about 1000? for 4-5 h, which can cause severe agglomeration. And then, long time grinding is indispensable for the following process. As a result, the crystal lattice of phosphor is destroyed to some degree and the luminescent intensity greatly decreases. Therefore, it is important to develop new synthesis method of red-emitting phosphor, to find the new red phosphors for PDP and to investigate mechanism of improving luminescent properties.In this work, chemical precipitation method and high temperature ball milling method are used to prepare red-emitting phosphor and investigate the structure and properties of phosphors. With borates and Aluminoborates as host materials, a series of red-emitting phosphors (Y,Gd)BO3:Eu3+, (Y,Gd)Al3(BO3)4:Eu3+, MAl2B2O7:Eu3+(M=Ca?Sr?Ba) were synthesized by chenmical precipitation method and high temperature ball milling method. The materials were characterized by x-ray diffraction (XRD), scanning electron microscopy (SEM), vacuum ultraviolet (VUV) and ultraviolet visible spectrophotometry (UV-Vis). The major research findings are as follows:Preparation and luminescent properties of (Y,Gd)BO3:Eu3+ red-mitting phosphor:Firstly, the most suitable (Y,Gd)BO3:Eu3+phosphor with proper and uniform particle size was prepared in a muffle at 900? of calcining temperature from a precursor which was prepared at 10 of precipitation pH value; urea as precipitation agent,15%(mol) Eu3+ and 20 %(mol) Gd3+doping concentrations. The (Y,Gd)BO3:Eu3+ phosphor can be effectively excited by VUV radiation at 147 nm and UV 254 run. In its emission spectrum, the strongest peak at 628 nm correlating to red emission was ascribed to the forced electric dipole transition 5D0?7F2 of Eu3+ ions. Significantly, the intensity ratio of (Y,Gd)BO3:Eu3+ phosphors of the red (5D0?7F2) to the orange 5D0?7F1) transition (R/O value) is 2.10, which is higher than 1.99 of the phosphor prepared by high temperature solid state reaction. Its chromaticity coordinates (CIE) were calculated to be x= 0.65, y= 0.35. It is closer to the standard red than commercial (Y,Gd)BO3:Eu3+, and comforms to the standard values of international chromaticity coordinates. So the red-emitting phosphor shows good potential of the commercialization phosphors.Secondly, the high temperature ball milling method was optimized, and investigate the structure and luminescence of (Y,Gd)BO3:Eu3+phosphor, a set of the optimized process parameters (the ball milling temperature at 700? for 3h,25 mol% Eu3+ and 20 mol% Gd3+ doping concentrations) can help to improve the phosphors luminescent properties. The (Y,Gd) BO3:Eu3+particles prepared by high temperature ball milling method with narrow distribution range and spherical morphology show good luminescent properties. The ball milling temperature is lower 500? than high temperature solid state method, which can save energy and reduce cost of production. The (Y,Gd) BO3:Eu3+phosphor prepared by high temperature ball milling method can be effectively excited by VUV radiation at 147 nm and UV 254 nm. The strongest emission peak at 628 nm correlating to red emission was ascribed to the forced electric dipole transition 55D0?7F2 of Eu3+ ions. Its chromaticity coordinates (CIE) were calculated to be x= 0.66, y= 0.34. The color purity was more excellent than it of the commercial red phosphor and comforms to the requirements of our country color TV phosphor (SJ1536-79). So the high temperature ball milling method has great potential to be used in manufacture.Preparation and luminescent properties of (Y,Gd)Al3(BO3)4:Eu3+ red-mitting phosphor:Firstly, when the concentration of EuJ+ and Gd3+ are 10mol% and 20mol%, the YAl3(BO3)4:Eu3+ phosphor has been prepared at 900? by chemical precipitation method, which is obviously decreased contrast to conventional solid state reaction method. YAl3(BO3)4:Eu3+ phosphor can be effectively excited by VUV radiation at 147 nm and the strongest emission peak lies at 616 nm. Its chromaticity coordinates (CIE) were calculated to be x= 0.66, y= 0.34. The color purity was more excellent than it of the commercial (Y,Gd)BO3:Eu3+ red-emitting phosphor. In addition, (Y,Gd)Al3(BO3)4:Eu3+ phosphor can be effectively excited by UV radiation at 394 nm, which can match ultra-violet and blue chips in light-emitting diodes application.Secondly, The (Y,Gd)Al3(BO3)4:Eu3+ phosphors were synthesized by high temperature ball milling method. The optimized technological parameterare determined:15%(mol) Eu3+ and Gd3+doped concentrationat at 750? for 2h, i.e. at a much lower temperature in contrast to conventional solid state reaction. The particles with narrow distribution range and spherical morphology can be effectively excited by VUV light at 147nm. The strongest emission peak at 616nm correlating to red emission was ascribed to the forced electric dipole transition 55D0?7F2 of Eu3+ ions.Preparation and luminescent properties of MAl2B2O7:Eu3+(M=Ca, Sr, Ba) red-emitting phosphor:Firstly, phosphors MAl2B2O7:Eu3+(M=Ca, Sr, Ba)were prepared by chenmical precipitation method, and the structure and luminescent properties were studied. The chromaticity coordinates of CaAl2B2O7:Eu3+and SrAl2B2Eu3+ comforms to the requirements of our country color TV phosphor (SJ1536-79). Under the same technological condition and the Eu3+concentration, the order of luminescent intensity from strong to weak is SrAl2B2O7:Eu3+>CaAl2B2O7:Eu3+>BaAl2B2O7:Eu3+. MAl2B2O7:Eu3+(M= Ca, Sr, Ba) phosphors can be effectively excited by UV radiation at 394 nm and the strongest emission peak at 616 nm correlating to red emission was ascribed to the forced electric dipole transition 55D0?7F2 of Eu3+ ions.Secondly, the SrAl2B2O7:Eu3+ phosphor was prepared by high temperature ball milling method at 700? for 2h,12 mol%Eu3+ doping concentrations and balls/material weight ratio up to 15:1, the phosphor has the strongest luminescent intensity at 616 nm. Doping with Li2CO3?Na2CO3 and K2CO3 as charge compensators can improve intensity of emission peaks of SrAl2B2O7:Eu3+ phosphor when charge compensating model is 2Sr2+?Eu3++Li+/Na+/K+. The optimum doping mole fraction is 2% Li+?4% Na+ and 2% K+ result in the most improvement of intensity of the emission peaks excited by 254 nm raditation, respectively. When the molar concentration of the charge compensators are 2%Li+?4%Na+ and 6% K+, respectively, the strongest luminescent intensity excited by 393 nm raditation can be obstained.The innovations of this paper are as follows:Firstly, the (Y,Gd) BO3:Eu3+phosphor with the ideal structure and luminescent properties was prepared successfully by chemical precipation method. In its emission spectrum, the intensity ratio of phosphors of the red (5D0?7F2) to the orange (5D0?7F1) transition (R/O value) is 2.10, which is higher than 1.99 of the phosphor prepared by solid state reaction. Its chromaticity coordinates (CIE) were calculated to be x= 0.65, y= 0.35. The color purity was more excellent than it of the phosphor prepared by conventional high temperature solid state method.Secondly, the (Y,Gd)BO3:Eu3+ and (Y,Gd)Al3(BO3)4:Eu3+ phosphors with the ideal structure and luminescent properties were prepared successfully by high temperature ball milling method. The ball milling temperature is lower 500? than the conventional high temperature solid state method.Thirdly, the color purities of (Y,Gd)BO3:Eu3+ and (Y,Gd)Al3(BO3)4:Eu3+ phosphors prepared by chemical precipation method and high temperature ball milling method are better than the commercialization phosphor (Y,Gd)BO3:Eu3+, and the chromaticity coordinates are closer to the standard values of international chromaticity coordinates, and reached national standards (SJ1536-79). So these phosphors show the good application potential.Fourthly, the luminescent properties of phosphor SrAl2B2O7:Eu3+are optimized by doping charge compensators, which can provide references for improving and developing of phosphors.Fifthly, the materials could be prepared by high temperature ball milling method at a much lower temperature in contrast to conventional solid state reaction, which provided an energy-saving way for the synthesis of luminescence materials, broadened the application range of phosphor preparation technology. |
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