Experimental optimal design on BaY2ZnO5: Tm3+/Yb3+ phosphor and its up-conversion luminescence property

Abstract

To obtain a maximal blue up-conversion luminescence of Tm3+/Yb3+ co-doped BaY2ZnO5 phosphors, orthogonal experimental design combined with quadratic general rotary unitized design method is employed to optimize the Tm3+ and Yb3+ ions doping concentration. Two sets of BaY2ZnO5:Tm3+/Yb3+ phosphors are synthesized by the traditional high temperature solid reaction method. The doping concentration ranges of Tm3+ and Yb3+ are first narrowed by orthogonal experimental design, and then quadratic general rotary unitized design is performed and one regression equation is established based on the experimental results from the latter design. The theoretical maximum value of the blue up-conversion luminescence intensity and the optimal Tm3+ and Yb3+ doping concentrations are obtained by genetic algorithm. The optimal sample is synthesized and its crystal structure and up-conversion luminescence properties are investigated. It is found that the blue up-conversion luminescence originates from three photon processes under 980 nm excitation. Temperature dependent up-conversion luminescence spectra of the optimal sample show that the blue up-conversion luminescence intensity declines with increasing temperature, implying the occurrence of thermal quenching of up-conversion luminescence. The calculated excitation energy is about 0.602 eV.