Figure 6.

(a) Lifetimes spectra of NaYF₄:5%Yb³⁺/30%Mn²⁺ nanoparticles with different synthesis temperatures (120 °C, 140 °C, 160 °C, 180 °C and 200 °C) and (b) amount of decay under 980 nm pulsed excitation. (c) Lifetimes spectra of NaYF₄:5%Yb³⁺/x%Mn²⁺ (x% = 20,30, 40, 50, 60 and 70) nanoparticles, (d) amount of decay under 980 nm pulsed excitation. (e) Lifetimes spectra of NaYF₄:40% Mn²⁺/x%Yb³⁺ (x% = 1, 5, 10, 20, 30 and 40) nanoparticles, (f) amount of decay under 980 nm pulsed excitation. The power density and spot diameter of the used 980-nm laser are 10 W/cm² and 3.0 mm, respectively. Luminescence decay times were measured in the red wavelength region. The analyzed samples were in solution form.