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LiYGeO4 phosphors doped with Dy3+ and Eu3+ ions were synthesized using the solid phase method, and their color characteristics were adjustable. The bandgap value of LiYGeO4 calculated by diffuse reflection data is very close to the theoretical value of 3.669 eV, indicating that LiYGeO4 is an ideal candidate for doped rare earth activated ions. The analysis of the emission spectra and fluorescence attenuation curves of Dy3+ and Eu3+ co-doped LiYGeO4 phosphors revealed a clear energy transfer process: energy transfer from Dy3+ to Eu3+. Analysis of emission spectra and fluorescence attenuation curves revealed a transfer of energy from Dy3+ to Eu3+. This transfer mechanism is attributed to the dipole–dipole interactions. In addition, by constantly adjusting the doping levels of Dy3+ and Eu3+, a warm white phosphor with a color temperature of 3881 K was obtained. Finally, the emission intensity of the LiYGeO4:0.015Dy3+,0.02Eu3+ phosphor at 423 K was 86%, indicating that the phosphor has excellent thermal stability and 40% internal quantum efficiency, which proves the potential application of the LiYGeO4 phosphor in white light-emitting diodes (w-LEDs). [ABSTRACT FROM AUTHOR]

LiYGeO 4 phosphors doped with Dy 3+ and Eu 3+ ions were synthesized using the solid phase method, and their color characteristics were adjustable. The bandgap value of LiYGeO 4 calculated by diffuse reflection data is very close to the theoretical value of 3.669 eV, indicating that LiYGeO 4 is an ideal candidate for doped rare earth activated ions. The analysis of the emission spectra and fluorescence attenuation curves of Dy 3+ and Eu 3+ co-doped LiYGeO 4 phosphors revealed a clear energy transfer process: energy transfer from Dy 3+ to Eu 3+ . Analysis of emission spectra and fluorescence attenuation curves revealed a transfer of energy from Dy 3+ to Eu 3+ . This transfer mechanism is attributed to the dipole-dipole interactions. In addition, by constantly adjusting the doping levels of Dy 3+ and Eu 3+ , a warm white phosphor with a color temperature of 3881 K was obtained. Finally, the emission intensity of the LiYGeO 4 :0.015Dy 3+ ,0.02Eu 3+ phosphor at 423 K was 86%, indicating that the phosphor has excellent thermal stability and 40% internal quantum efficiency, which proves the potential application of the LiYGeO 4 phosphor in white light-emitting diodes (w-LEDs).

A series of Ca 3 Al 2 Ge 3 O 12 : x Dy 3+ , y Eu 3+ phosphors were successfully prepared by the high-temperature solid-phase method. The phase and morphology of the phosphors were studied by means of Rietveld refinement and scanning electron microscopy. The results show that the phase is pure, and the crystal structure is the Ia 3̅ d space group. In the Ca 3 Al 2 Ge 3 O 12 : x Dy 3+ phosphors, using 380 nm excitation, phosphors showed blue ( 4 F 9/2 → 6 H 15/2 ) and yellow ( 4 F 9/2 → 6 H 13/2 ) emission peaks at 481 and 581 nm, respectively. In Ca 3 Al 2 Ge 3 O 12 : x Dy 3+ , y Eu 3+ phosphors, the energy transfer was inferred by the spectrum overlap of Dy 3+ and Eu 3+ , and the lifetime attenuation was analyzed from the perspective of dynamics; finally, the band gap structure of the phosphors was analyzed by combining diffuse reflection spectra with the first principle, and the energy transfer mechanism and luminescence mechanism were elaborated by combining theory and practice. The transition from blue white light to red light can be achieved by tuning the range of y in Ca 3 Al 2 Ge 3 O 12 : 0.015Dy 3+ , y Eu 3+ . Wherein, when y = 0.07, phosphors, the chromaticity coordinate of warm white CIE is (0.3932, 0.3203), the color temperature is 3093 K, and the warm white light is synthesized. The thermal stability of the synthesized warm white phosphors is 90.1% (423 K), the thermal sensing factors are S amax = 5.51 × 10 -4 K -1 (303 K) and S rmax = 0.0359% K -1 (303 K), and the actual quantum efficiency is IQE = 52.48%. These results prove that Ca 3 Al 2 Ge 3 O 12 : Dy 3+ , Eu 3+ have good application prospects as single-component warm w-LED devices.