The Study Of Rare-earth Ions Doped Molybdate Phosphors By Experiment Optimization Design

Recent years, rare earth doped luminescent materials have attracted large numbers of attention due to its important value in laser technology, optical message storage and display, medical field and so on. Rare earth molybdates have received people’s attention with good optical and thermal stability, and they are more preferable to be used as host materials by researchers. In view of the fact that two different kinds of rare earth ions co-doped into host material will largely improve its luminescent efficiency, this paper has focused on the luminescent properties of two kinds of rare earth ions co-doped into the host material.1. Uniform design and quadratic general rotary unitized design are combined to optimize the doping concentration of Tm3+ and Yb3+. The NaY(MoO4)2:Tm3+/Yb3+ phosphor with biggest blue luminescent intensity are obtained. This paper has studied NaY(MoO4)2:Tm3+/Yb3+ phosphor. Because Tm3+ can produce stronger blue up-conversion luminescence, Yb3+ as its sensitizer can largely improve the up-conversion luminescent efficiency of NaY(MoO4)2:Tm3+/Yb3+ phosphor. In order to acquire the biggest luminescence intensity of this phosphor, experiment optimization design is employed to optimize the experiment. Uniform design is firstly used to narrow the rare earth ions doping concentration range, and then quadratic general rotary unitized design is used to establish the quadratic regression equation between the luminescent intensity of NaY(MoO4)2:Tm3+/Yb3+ phosphor and the concentration of Tm3+/Yb3+. The Genetic Algorithm (GA) is applied to optimally calculate the maximum value of the established quadratic regression equation and the high temperature solid state method is used to prepare the optimum sample with biggest luminescent intensity. The up-conversion luminescence spectra of the optimum sample are detected, and the optimal sample in this experiment is in accordance with theoretical calculated optimal sample. The up-conversion luminescence mechanism is analyzed in detail and the temperature quenching mechanism is also explained.2. This paper has studied NaY(MoO4)2:Er3+/Gd3+ phosphor. Er3+, Gd3+ and synthesis temperature (T) are considered to influence the luminescence intensity of NaY(MoO4)2:Er3+/Gd3+ phosphor. Uniform design is used to narrow the rare earth ions doping concentration ranges, and then orthogonal experiment design and range analysis are used to confirm the best combination of Er3+/Gd3+/T. Down-conversion excitation and emission luminescent spectra are measured, green light emission at 530nm and 550nm are observed corresponding to Er3+ 2H11/2â†'4I15/2 and 4S3/2â†'4I15/2 transition respectively. The emission spectra at different temperature are measured and the thermal quenching is also explained according to the classical thermal quenching theory.