The Near-infrared Luminous Of Er³⁺-doped Oxide Superfine Powders

Recently, the NIR luminescent materials have received the extensive researchand attention at home and abroad, duing to the advantages of strong penetrability, freeof back ground, high sensitivity, good thermal effect, etc. The energy level transitionsof Er3+from4I13/2to ground state4I15/2lead to the luminescence of1.54um. Becausethe light of1.54um is the third low loss for optical fiber communication window andsecurity for the human eye, the NIR luminescent materials doped Er3+have beenwidely applied in optical fiber communication, food testing, laser systems, biologicalsensors and biological imaging, etc. The energy level of Er3+ion is very rich.However, the absence of strong absorption bands in the visible and NIR spectralranges leads to some deficiencies of weak absorption intensity, low pump efficiency,low luminous efficiency, and weak luminous intensity in the NIR luminescentmaterials doped Er3+. So the NIR luminescent materials have received limitation inpractical application. In this paper, we studied the effective ways and means toimprove the Er3+NIR luminous intensity by looking for the right sensitizing ions andsubstrate. The conclusions and results were summarized as follows:The NIR fluorescent powders of YAG: Er3+, Ce3+, Bi3+were prepared byco-precipitation method. We studied the influence of different Bi3+ion concentrationto the NIR luminescence, and found the NIR emission of Er3+ions at1531nm isenhanced threefold by the addition of7mol%Bi3+. The doped Bi3+results in theformation of exciton in YAG and the variation of the local environment for the dopedrare earth ions. The enhancement of near-infrared luminescence is ascribed to thecombination of the sensitization of extionâ†'Ce3+â†'Er3+and the Bi3+doping inducedadjustment of local environment for Ce3+and Er3+ions.The NIR fluorescent powders of YPO4: Er3+, Ce3+, Yb3+were prepared byco-precipitation method. The NIR emission spectrum and the red-green light emissionspectrum were obtained under980nm laser excitation. It is found that the Ce3+dopingeffectively suppress the up-conversion of Er3+, increase the particle population on the4I13/2level of Er3+ion, enhance the4I13/2â†'4I15/2transition probability, and improve theNIR luminous intensity of1.5um. On the basis of the best Ce3+doping concentration,we found the Li+doping enhance the1.5um NIR luminous intensity of Er3+ion,which is enhanced tenfold when the addition of Li+is0.06.The NIR fluorescent powders of Y3Fe5O12: Ce3+, Er3+were prepared by sol-gel method. We studied the influence of the composition of the simple, excessive Y3+ions, and calcination temperature on the sample structure. It is found that there is noother impurity phase in the crystal lattice when mixing with30%citric acid ascomplexing agent, Y3+ions excessing1%, and calcining temperature at1100oC for6h. By analyzing the influence of Ce3+ions concentration to the NIR luminescence,we found the luminous intensity enhanced30times when the concentration of Ce3+ions is2%. In addition, with the increase of calcination time, the energy transferbetween Ce3+and Er3+ions increase. The excitation intensity and near-infraredluminous intensity are also enhanced.