Synthesis and Characterization of Upconversion Fluorescent Yb^𝟑+, Er^𝟑+ Doped CsY_𝟐F_𝟕 Nano- and Microcrystals

Figure 4

Image of the upconversion luminescence in 1 wt.-% colloidal solutions of CsY₂F₇: 78%  Y, 20%  Yb, 2.0%  Er nanocrystals in methanol. Excitation at 978 nm with a power density of about 30 W mm^-2. Overall laser power: 4.5 W. The laser is positioned on the right side.