Figure 7

(a) TEM image of as-prepared 0.05 mol Er³⁺ doped precursor. (b) TEM image of as-prepared 0.05 mol Er³⁺ doped YOF nanocrystals sintered at 500 °C. The insert shows HRTEM image of single YOF:0.05Er nanocrystal sintered at 500 °C. (c) EDS spectrum of 0.05 mol Er³⁺ doped YOF nanocrystals sintered at 500 °C. (d–g) The two-dimensional mapping distribution of F, O, Y and Er in single Er³⁺ doped YOF nanocrystal, respectively. (h) TEM image of 0.05 mol Er³⁺ doped YOF nanocrystals sintered at 900 °C. The insert shows SAED pattern of single YOF:0.05Er nanocrystals sintered at 900 °C. (i) HRTEM image of 0.05 mol Er³⁺ doped YOF nanocrystals sintered at 900 °C.