Preparation And Characteristics Of Rare Earth Doped Tungstates Nanocrystal

In this paper, ZnWO4 and Bi2WO6 nanocrystals co-doped Yb3+ and Er3+ ions were prepared by hydrothermal method using PEG as dispersant. The optimum fabrication process was discussed by changing the experimental condition and list of the optimum composition of two types of samples.The physical properties of ZnWO4 and Bi2WO6 was analyzed by X-ray diffraction, transmission electron microscope, scanning electron microscope. The up-conversion spectrum was measured with Hitachi F-4500 spectrophotometer, under 980nm diode laser excitation. The results are as follows:1.ZnWO4 belongs to monoclinic crystal system. The diameter of ZnWO4 is about 20nm, but is changed to 100nm after annealing crystallization. The results indicate there are three emission peaks of samples located at 532nm,553nm and 656nm. The annealing experiment shows that the luminous results of sample is best when ratio of Yb3+(c/mol):Er3+(c/mol) is 6:1 and temperature is 800℃.2.Bi2WO6 belongs to orthorhombic crystal system, The diameter of Bi2WO6 is about 40nm, but is changed to 100nm after annealing crystallization. The results indicate there are three emission peaks of samples located at 527nm,549nm and 656nm. The annealing experiment shows that the luminous results of sample is best when ratio of Yb3+(c/mol):Er3+(c/mol) is 7:1 and temperature is 700℃...