Oxalic Acid-Assisted Hydrothermal Synthesis and Luminescent of Hexagonal NaYF₄:Ln³⁺ (Ln = Sm, Eu, Yb/Er) Micro/Nanoplates

Figure 3

The XRD patterns of the NaYF₄:Yb³⁺/Er³⁺ products after different times at pH = 6, 200°C.