Controlled Synthesis of Water-Soluble NaYF₄:Yb³⁺, Er³⁺ Nanoparticles with Surfactant Dependent Properties

Figure 3

SEM images of the NaYF₄: 20 mol% Yb³⁺, 2 mol% Er³⁺ NPs prepared under different conditions: (a) LPEI, 3 h; (b) LPEI, 5 h; (c) HPEI, 3 h; (d) HPEI, 5 h.

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