| Long afterglow materials can be applied to lighting, transportation, medical and otherfields. Long-lasting12CaO·7Al2O3:Eu2+, Nd3+is prepared by burning method. The phasestructures of the products have been characterized by X-ray diffraction. Optical propertieswere studied by excitation spectra, emission spectra, thermoluminescence, afterglowphotostimulated luminescence, and so on.The results of XRD indicated that12CaO·7Al2O3:Eu2+, Nd3+were obtained，and it is asimple phase. It revealed that Eu2+,Nd3+had been incorporated into C12A7lattice site. Theexcitation peak at about324nm and the emission peak at about442nm which is contribute tothe typical4f65d1-4f7transition of Eu2+.The emission spectra and excitation spectra have abroadband character, due to the5d levels of Eu2+could be easily affected by the crystal fieldsplit. The results of experiment indicated that change the concentration of neodymium,wecan observe different optical properties, especially the afterglow time,12CaO·7Al2O3:0.5%Eu2+,0.5%Nd3+have the longest afterglow, afterglow lasted more thantwo hours.12CaO·7Al2O3:0.5%Eu2+,0.5%Nd3+thermoluminescence curves calculate the trapdepth is0.695ev. Photostimulated luminescence of C12A7: Eu2+,Nd3+is better than C12A7:Eu2+, due to Nd3+increase the number of deep traps. The reason of long afterglow may beelectrons is excited to the conduction band, trapped by shallow traps and deep traps, due tothe thermal excitation, the shallow traps of electrons escape into the conduction band, a partof electrons go to the luminescence center and recombination hole to luminescence, the restelectrons is trapped by trap, electrons of deep traps would not escape the conduction band atroom temperature in a minute, electrons will slowly escape and luminescence, make the timeof afterglow increase.Doping neodymium to increase a large number of traps and afterglow time throughcomparing with the luminescence properties of the co-doped C12A7:Eu2+, Nd3+andC12A7:Eu2+. |
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