关键词: 水热法, 干燥方式

Abstract: Trivalent Dy3+ and trivalent Eu3+ ions co-doped NaY(WO4)2 upconversion phosphors were synthesized via traditional hydrothermal process. The effects of drying routes on the crystal structure, morphology, particle size and upconversion luminescence properties were investigated, and characterized by XRD, SEM, and photoluminescence spectrum (PL). The results showed that all the synthesized samples had the tetragonal scheelite structure with the space group I41/a, and the doping Dy3+ and Eu3+ ions did not evoke the changes of the host lattice parameters. In addition, the shape and size of products could be changed simply and effectively by different drying methods. The particle sizes of the phosphors drying by normal, spray, freeze and vacuum methods were 817.91, 486.04, 388.74 and 349.82 nm, respectively. It should be noted that the excellent dispersion of the particles were obtained by vacuum drying method. Under near infrared light excitation at 793 nm, the sample obtained by freeze drying had the better upconversion luminescence property than samples synthesized by normal drying, spray drying and vacuum drying. The possible reason for the above phenomenon were spread uniform, reunite decrease and surface defect layer decrease of powder particles during the freeze drying process. The NaY(WO4)2:Dy3+, Eu3+ phosphors exhibited yellow emission band at 576 nm corresponding to the 4F9/2→6H13/2 transition of Dy3+ ions, orange emitting lights (595 nm) were from the transition of 5D0→7F1 of Eu3+ ions, and red emitting lights at 616 and 655 nm, which were assigned to the energy level transition of 5D0→7F2 and 5D0→7F3 of Eu3+ ions, respectively. Moreover, the ideal red chromaticity was exhibited by the CIE color coordinates of NaY(WO4)2:Dy3+, Eu3+ phosphors. In view of this, the NaY(WO4)2:Dy3+, Eu3+ phosphors might have potential application in photoelectric device areas, such as light emitting diodes and color display systems.

Key words: hydrothermal method, drying routes