Synthesis And Luminescence Properties Of Red Emitting Phosphors M₂P₂O₇:EU³⁺（M=Ba,Sr,Ca） For White LED

White light emitting diode （WLED） is honored the green light source due to itsattractive advantages of energy consumption saving, environmental, high efficiency andlifetime long-lasting aspects and it has been focused on in all around the world.Considering the WLED technology, the way of single-chip LED combining with inorganicluminescent materials （phosphors） is the dominant direction of solid-state lighting in thefuture. So the luminescent phosphors are very important, among which the red emittingphosphor has to pay more attention because of its low efficiency. The central point of lightemitting material lays on the red emitting phosphor for WLED.Phosphate is a kind of stable compound. It is believed to have lots of merits to meetthe requirement such as low reaction temperature, stable physical and chemical propertywhen it is used as the matrix. At present, phosphate is prepared by traditional solid-statereaction method in most time with advantages of high luminescence of the product, simpleprocess and low cost. However, this method requires high reaction temperature, result ingreatly growth of the particle size. The phosphors have to be milled before their use andthe luminous efficiency will decrease at the same time. Recently, solution combustionsynthesis method has got considerable attention for its simple process. It is a promisingmethod as a new wet-chemical process.In this paper, M₂P₂O₇（M=Ba, Sr, Ca）: Eu³⁺were synthesized by solution combustionsynthesis method. The crystal structure, particle size and luminescence of the phosphorwere investigated. The main results obtained of the paper are as follows.Red emitting phosphor α-Sr_2P2O₇:Eu³⁺is prepared by combustion synthesis methodwith urea as fuel. The phosphor is pure. The emission spectrum shows that the mostintense peak is located at588/593nm, and the relatively a little weak peak is located at612nm, which corresponding to⁵D₀�'⁷F₁,⁵D₀�'7F2transition of Eu³⁺, respectively. The critical quenching concentration of Eu³⁺ions in α-Sr_2P2O₇:Eu³⁺is0.05mol. Theconcentration quenching mechanism caused by the electric multipole interaction isconsidered to quadripole-quadripole.Luminescent properties of M_1.95P₂O₇:0.05Eu³⁺（M=Ba, Sr, Ca） red emittingphosphors are systematically studied. The spectrum shows that the emission and excitationpeaks are located at the same points. But the results show that in M_1.95P₂O₇:0.05Eu³⁺（M=Ba, Ca） the intensity of the emission peaks locating at612nm due to⁵D₀�'7F2electric-dipole transition of Eu³⁺is higher than that locating at588/593nm due to⁵D₀�'7F2electric-dipole transition, the phosphor emits red light mainly. It indicates the Eu³⁺lies innon-centrosysmetrical sites. On the contrary, the Eu³⁺in Sr1.95P₂O₇:0.05Eu³⁺lies incentrosysmetrical sites, the phosphor emits orange-red light mainly. The CIE ofM_1.95P₂O₇:0.05Eu³⁺（M=Ba, Sr, Ca） phosphors are calculated as （0.35,0.21）,（0.24,0.15）,（0.35,0.21）, respectively. All the three phosphors can be excited by the near UV light at394nm and blue light at464nm and emit red or orange-red light.Red emitting phosphor Ca2P₂O₇:Eu³⁺is prepared by combustion synthesis methodwith H₃BO₃as flux. The addition of moderate flux can improve the micro morphology ofthe phosphor and intensify the⁵D₀�'7F2electric-dipole transition.The addition of charge compensation agent （Li⁺,Na⁺,K⁺） can enhance the intensity ofthe phosphor significantly, especially the Na⁺ion. Ca_1.90P₂O₇:0.05Eu³⁺,0.05Na⁺is apromising red phosphor for WLED for it can be excited by the near UV light at394nmand blue light at464nm efficiently.