| Energy transfer is an important phenomena during the process of luminescence which opens doors to reveal the nature and rules of electron transitions as well as is extensive use in luminescent material, has become a meaningful research. Eulytite-type phosphate is a suitable host for studying energy transfer for the reason that it has a special cation site that could be heavily doped with common luminescence ions and as it is a phosphate host, which always presents high luminous efficiency in luminescence with good stability.In this article, the energy transfer is based on the Ce3+ ion in Sr3Y(PO4)3 (SYP) host. The single-doped and co-doped samples with the chemical formula Sr3Y(PO4)3:Ln(Ln=Ce3+,Mn2+,Dy3+) were synthesized via high temperature solid state method. The XRD, photoluminescence, energy transfer mechanism, CIE are analysed or calculated to investigate the luminescence nature and energy transfer property of the samples, and the results as follows:1. The study on luminescence and energy transfer properties of Sr3Y(PO4)3:Ce3+,Mn2+A series of highly efficient Sr3-yY1-x(PO4)3:xCe3+,yMn2+phosphors have been prepared via a solid state reaction. There is only one exclusive luminescence center in the sample of SYP:xCe3+, the two strongest excitation peaks of which are located at 270 nm and 315 nm and the emission is peaking at 366 nm.When prepared in air, the self-reducing process of turning Ce4+ into Ce3+ can be found in SYP:;xCe3+ phosphor. A bright red light emission was presented in the Ce+ and Mn2+ co-doping samples via the efficient ET from the sensitizer Ce3+ to Mn2+, which is ascribed to electric multipolar interaction between these two kinds of ions. The critical concentration of Ce3+ in SrY1-x(PO4)3:xCe3+ and Mn2+ in Sr3-yY1-x(PO4)3:xCe3+, yMn2+ are x=0.07 and y=0.15, respectively. In addition, the ET efficiency reach 51.6% when the luminescence intensity of Ce3+ is half of that in the absence of Mn2+ and the concentration of Mn2+ is 0.15. The analysis of CIE coordinate briefly indicate that the emission color of SYP:0.07Ce3+.yMn2+ is tunable and determined by the concentration of Mn2+, which could change from blue to orange-red. There is the potential in lighting after improving.2. Sensitization effect of Ce3+ on Dy3+ in Sr3Y(PO4)3The Dy3+ ion were used as the activator co-doping with Ce3+ in SYP due to the highly overlapping of the excitation of Dy3+ and the emission of Ce3+ in the host. The XRD indicates that the doping of Dy+ will not change the crystal structure and lattice constant of SYP in that the structure parameter of Sr3Dy(PO4)3 (SDP)is almost the same as that of SYP. Thus the ratio of the blue emission to yellow emission did not change with the increasing of the Dy3+ concentration.The increasing concentration of Dy3+ in co-doped samples leads to monotonically decline of the Ce3+ emission and the monotonically increment of ηET. The Dy3+ emission intensity reaches the maximum with the content of Dy3+ equals to 0.07 and the ηET=61.7%at that point. The energy transfer belongs to dipole-dipole interaction. Near-while light could be formed in the SYP:0.07Ce3+,zDy3+ phosphor where z=0.05, whose CIE=(0.353,0.318). We can also see its potential in lighting applications. |
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