Research On Ho-Yb-Mg Doped C12A7Polycrystalline Powder Preparation And Luminous Performance

12CaO7Al2O3(C12A7) is a very promising upconversion luminescentmaterials, in recent, which has aroused people’s enthusiasm to research. This paperwas prepared the C12A7samples doping Ho, Yb and Mg by high-temperature. First,analyze discuss different sintering temperature and time how effect on thesolid-phase C12A7by the XRD patterns, to determine the optimum sinteringconditions: sintering temperature is1050℃and sintering time is7hours.To determine the optimal concentration doping Mg2+, prepared the samples doping0.3mol%Ho3+ion,0.7mol%Yb3+ion and different concentrations Mg2+. Ho3+,Yb3+and Mg2+ions have not changed in three C12A7lattice type by XRD analysis,which replaced positions of Ca2+existing in the lattice. The concentration dopingMg2+was1.2mol%, the purple shift extent is maximum, and the green light intensityand red light intensity are maximum, so the optimal concentration doping Mg2+is1.2mol%.In order to study the upconversion luminescence properties of C12A7:1.2Mgdoping Ho3+and Yb3+. The samples doping different Ho3+and Yb3+ionsconcentration ratio were prepared. UV analysis show occurrence of purple shift atfirst and red shift as Yb3+concentration increases; When Ho3+/Yb3+ionconcentration ratio is1:10, the upconversion green light intensity is maximum, at thistime, two-photon process mainly occurs, on5F4/5S2state transition to the groundstate on5I8emits green light at550nm, but also a part of the three-photon processoccurred, namely, the photos on5F4/5S2state continue to absorb ion-photontransition to the state on5G5; when the ratio of Ho3+/Yb3+ion concentration isover10, the green light emission mainly based on single-photon process, co-sensitization process occurs at this time, the equivalent of single-photon process,namely22F5/2+5I8â†'5F4/5S2+22F5/2. When Yb3+concentration is below6mol%,mainly red emission based on the upconversion of two-photon process,5F5â†'5I8,emits a red light at667nm; when the Yb3+concentration exceeds6mol%,co-sensitization occurs, mainly in single photon get on. With the increase of Yb3+concentration, the ratio of red and green light has been increased.