Host Structure Modification Of Two Kinds Of Mineral-inspired Phosphors And The Investigation On Their Photoluminescence And Afterglow Properties

In recent decades, rare-earth doped luminescence materials have attracted much attention in the field of lighting, display and photoelectron devices. Especially, the phosphors for white light emitting diodes(w-LEDs) and long-persistent luminescence act as the main topic, and the basic academic and industry research have been conduceted in many groups working in these fields. It is known that host material plays a key role in the optimization of the luminescence properties of optical materials. At the same time, the composition and structure of the mineral give us new insight on the understanding of the new inorganic compounds. Therefore, structural modification of the phosphor host becomes the important reseach field for solving some problems in the applications as well as providing a novel strategy to search new efficiency optical materials. Furthermore, it also reveals the relationship between the solid structure and its luminescence property.In this paper, we have prepared garnet-type phosphor Lu3Al5-xScxO12:Ce3+ and studied the effect on luminescence properties via replacement of Al3+ by Sc3+. The results show that there is a blue-shift of emission spectra. Moreover, the thermal stability has been improved. We also prepare other garnet-type phosphors Y3Sc2Ga3-xAlxO12:Ce3+, Y3Sc2Ga3-xAlxO12:Cr3+ and investigate the afterglow properties caused by Al/Ga substitution. The results indicate that the substitution of Ga3+ by Al3+ not only enhance the concentration of traps but also generate new trap levels. Hence, the afterglow properties have been significantly improved.We have prepared two melilite-type phosphors, Ca2Al2-xSi1+xO7-xNx:Eu2+ and Sr2Al2 Si O7:Eu2+,RE3+(Nd3+, Dy3+, Tm3+, Yb3+ and Ce3+), and studied the relationship between structural modification and optical properties. The substitution of Al-O by Si-N may cause a blue-shift in emission and improve the thermal stability. The afterglow intensity and the decay time have been tremendously increased when co-doping Nd3+ ions. The optimal concentration for Eu2+ and Nd3+ doping in Sr2Al2 Si O7 are determined to be 4 mol% and 10 mol%, respectively.