Research Article

Synthesis and Application in Anticounterfeiting of RGB Upconversion Nanoparticles

Figure 2

(a) The XRD of NaYF4:Yb3+,Tm3+ NPs and a standard card (JCPDS: 28-1192). (b) The SEM image of NaYF4:Yb3+,Tm3+ NPs.
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(b)