NaYF4∶Yb3+/Eu3+上转换发光微纳粒子在防伪识别中的应用研究

doi:10.3964/j.issn.1000-0593(2021)05-1525-05

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Abstract Rare earth doped upconversion luminescent micro-nano particles have great application prospects in anti-counterfeit identification. First of all，in the article NaYF₄∶Yb³⁺/Eu³⁺ micro-nano particles prepared by hydrothermal synthesis method，The size，morphology and crystallinity of NaYF₄∶Yb³⁺/Eu³⁺ micro-nano particles were investigated by X-ray diffraction (XRD)、scanning electron microscope (SEM) and transmission electron microscope，and the luminescence properties of NaYF₄∶Yb³⁺/Eu³⁺ micro-nano particles were analyzed using a 980 nm pump source；Secondly，NaYF₄∶Yb³⁺/Eu³⁺ micro-nano particles and alcohol were mixed in a certain proportion to make a screen printing agent and combined with a network-customized screen template，different anti-counterfeit patterns were printed on the paper. After air drying，the words were exposed to a 980 nm laser and camera were used to study it. Finally，the printed words were divided into two parts，one was stored indoors at a constant temperature of 25 ℃, and the other was stored in the outdoor natural environment in January in winter. The storage locations are all Xi’an. After one week，in different environments the words were again tested with the same experimental instruments for imaging. The experiment and test results show that the diffraction peak of NaYF₄∶Yb³⁺/Eu³⁺ micro-nano particles is a completely consistent standard card of NaYF₄，and no other impurities are generated. In this experiment，The synthesized micro-nano particles are all hexagonal in shape，and the average length and cross-sectional width are 209 and 175 nm respectively. The surface of the nanocrystal is smooth，defect-free，unbent，with high crystallinity and good dispersion. The electron diffraction ring corresponds to the 312，300，and 302 crystal planes of NaYF₄∶Yb³⁺/Eu³⁺ micro-nano particles. NaYF₄∶Yb³⁺/Eu³⁺ micro-nano particles are affected by doped ions，it produces four visible lights of blue，green，yellow and red by different energy level transitions. Through fluorescence spectrum analysis of NaYF₄∶Yb³⁺/Eu³⁺ micro-nano particles. The asymmetry ratio of Eu³⁺ ion is about 1. This result shows that the magnetic dipole transition is equivalent to the electric dipole transition. Screen printing agent of NaYF₄∶Yb³⁺/Eu³⁺ micro-nano particles are good in different environments，the results are clear and easy to identify. However，affected by the storage environment，The results of indoor imaging have not changed much from the original imaging results. All characters of outdoor imaging are affected by moisture in the natural environment，the brightness is slightly reduced，but they can still be recognized. The imaging results show that the prepared NaYF₄∶Yb³⁺/Eu³⁺ micro-nano particles have the characteristics of stability and reliability in anti-counterfeiting identification，but they are still affected by natural environmental factors with a controllable degree. On the whole，it has great application prospects in anti-counterfeiting identification.

Key words：Upconversion luminescence; Hydrothermal synthesis; Anti-counterfeiting identification; Screen printing; Micro-nano particles

Received: 2020-04-16 Accepted: 2020-08-20

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https://www.gpxygpfx.com/EN/10.3964/j.issn.1000-0593(2021)05-1525-05 OR https://www.gpxygpfx.com/EN/Y2021/V41/I05/1525