Research On The Red Long Afterglow Phosphorescent Material Y₂O₃: Eu～(3+),Ca～(2+),Ti～(4+) Fabricated From Combustion Synthesis

In this paper, the effect of components on the structure, spectrum nature and luminescent performance of Y₂O₃:Eu³⁺ phosphors was studied in order to develop a new type of red long afterglrow material which is nonradioactive, high efficient and non-active. According to the results of large quantities of experiments and research, the primary reason that generate the long afterglow is the existing of Ti⁴⁺ and Ca²⁺ mixed in phosphor and the optimal initial healing temprature was acquired. At the same time, the range of incendiary agent(carbamide), activator(Eu³⁺) and fluxing agent(H₃BO₃) concentration was sdudied, and the influence of alkali and alkaline earth ions for the phosphors was discussed.The auxiliary activators(Gd₂O₃, Sm₂O₃, Dy₂O₃ and Bi³⁺) which can affect the luminescent performance were also investegated. Based on the studing of XRD, emission spectra, excitation spectra and UV-Vis reflective spectrum, the result indicates the most suitable healing temprature is about 600℃and the main excitation spectrum peaking ascribed to the electron transition of Eu3+ -O2-(CTS) is located at 253nm. Because of the restriction of selection rules, some quit short excitation spectra peakings is introduced by the inner transtion of 4f electrons out of 300nm. The emission spectra peakings of Y₂O₃:Eu³⁺ phosphor are generated by the characteristic emission from ⁵D₀→⁷F₀, ⁵D₀→⁷F₁ and ⁵D₀→⁷F₂ of Eu³⁺. When the mass ratio of carbamide/nitrade is 1.5 and the concentration of Eu³⁺ doped as activator is 5%mol, the Y₂O₃:Eu³⁺ phospors have the better luminescent performance. The XRD patterns show the phosphors fabricated using combustion procedure belong to the nanophase materials and don't exist other phases except for the cubic Y₂O₃. The conclusions also indicates the particle size is varied with the use level of carbamide . The use level of carbamide is more less, the power granules will become more smaller. But the cell parameter(a) don't vary with the use level of carbamide. If the use level of carbamide being cut down or the doping content of activator Eu3+ being increased, the main excitation spectrum peaking(CTS peaking) will happen red shift effect but the main emission spectrum peaking desn't shift. The most suitable concentration of H₃BO₃ used as fluxing agent is 0.1mol. Because H₃BO₃ can increase the density of electon traps and the concentration of luminescence centres through provoking combustion products crystallization easily and formating to perfect crystal structure to make the lattice point replaced by active ion is occupied by themthelves, it can enhance the luminescent intensity and elangate the decay time. The afterglow performance is improved by the alkali ions and alkaline earth ions in some way, which ascribes the proper energy level of electron traps and elecron holes produced by positive ions whose valency is unqual replacing and the long afterglow phenomenon induced by the interactivity of two kinds of trap energy level. In the end, the effect of variant doped ions on the afterglow performance of phosphor Y2O3:Eu3+ was studied.The luminescent intensity of phosphors is inhanced by Bi3+ and Sm3+, especially Sm3+ at first, weakened later on. The lulminescent performanmce is improved by Gd3+ very little but is deteriorated evidently by Dy3+. Because there is no any abnormally emission peaks on the emission spectra patterns of Y2O3:Eu3+, the rare earth ions Y2O3:Eu3+ doped only play the roles of sensitizer and auxiliary activator.