Fig. 1. Energy-level diagram of Dy³⁺ systems.

Fig. 2. (a) Photographs and test samples of Dy:YAP crystal with a doping concentration of 1%; (b) XRD patterns of 1% Dy:YAP crystal and standard ICSD 4115.

Fig. 3. Crystal structure of YAP crystal.

Fig. 4. (a) Absorption spectra of Dy:YAP single crystals; (b) excitation spectra of Dy:YAP crystals with different doping concentrations; (c) PL spectra of Dy:YAP crystals with different doping concentrations and excited at 350 nm; (d) PL spectra of Dy:YAP crystals with different doping concentrations and excited at 450 nm.

Fig. 5. CIE chromaticity coordinates of Dy:YAP crystals with different exciting wavelengths and doping concentrations.

Fig. 6. (a) Schematic of the Dy:YAP white light; (b) white-light spectrum; (c) CIE chromaticity coordinates.

Fig. 7. (a) PLQY with the excited wavelength of 350 nm; (b) PLQY with the excited wavelength of 450 nm; (c) PLQY with different doping concentrations; (d) luminescent lifetime of 1% Dy:YAP crystal.

Table 1. Fluorescence Quantum Efficiency of Various Dy³⁺-Doped Crystals