Trivalent Dy³⁺ and Eu³⁺ Ions Codoped High-Entropy Gadolinium Yttrium Scandium Aluminum Garnet Crystals for Promising Visible Solid-State Laser and Anticounterfeiting Applications

Rare earth ion-doped luminescent materials exhibit significant potential for application in visible solid-state laser and anticounterfeiting applications. The Czochralski method was employed to successfully synthesize high-quality Dy3+, Eu3+ codoped Gd3Sc2Al3O12 (GSAG), and Gd2.79Y0.21Sc2Al3O12 (GYSAG) single crystals. Comprehensive studies were conducted on their structural and physicochemical properties, luminescence properties, and fluorescence lifetime. The Dy,Eu:GSAG and Dy,Eu:GYSAG crystals both display favorable thermal conductivity values of 5.56 and 5.43 W m–1 K–1, respectively, along with commendable hardness properties of 7.241 and 7.247 kg/mm2. The emission color of the Dy,Eu:G(Y)SAG crystals can be adjusted from white light under a 355 nm excitation to orange-red light under a 405 nm excitation and bright yellow light under a 450 nm excitation. Additionally, the maximum stimulated emission cross-section for both crystals was calculated under various wavelength laser excitations. The fluorescence lifetime of the crystals at the 4F9/2 level (Dy3+) and the 5D0 level (Eu3+) was also examined. Notably, the fluorescence quantum efficiencies at the 4F9/2 level in Dy,Eu:GSAG and Dy,Eu:GYSAG were measured to be impressive at 91.3 and 92.7%, respectively. The mechanism of resonance energy transfer between Dy3+ and Eu3+ was analyzed, indicating promising applications of Dy,Eu:G(Y)SAG in visible solid-state lasers and multimode anticounterfeiting.