1. Energy transfer mechanism in infrared-emitting NaYGeO4:Tm3+, Ho3+ phosphors.
- Author
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Melentsova, Anna A., Lipina, Olga A., Chufarov, Alexander Yu., Tyutyunnik, Alexander P., and Zubkov, Vladimir G.
- Subjects
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ENERGY transfer , *OPTICAL properties , *SEMICONDUCTOR lasers , *DIPOLE-dipole interactions , *BAND gaps - Abstract
Two series of NaY 0.85 Tm 0.15-x Ho x GeO 4 (x = 0.005–0.03) and NaY 0.85-x Tm 0.15 Ho x GeO 4 (x = 0.0–0.055) phosphors have been prepared by the citrate technique. According to XRPD study, all the germanates crystallize in olivine structure and have an orthorhombic lattice, space group Pnma , Z = 4. The diffuse reflectance spectra have been measured and the optical band gap has been estimated. Under 808 nm laser diode excitation, the NaYGeO 4 :Tm3+, Ho3+ samples exhibit luminescence in the range of 1640–2240 nm, which is caused by 3F 4 → 3H 6 transition in Tm3+ and 5I 7 → 5I 8 transition in Ho3+ ions. The highest intensity of holmium lines, while maintaining relatively high intensity of thulium lines, was observed for NaY 0.82 Tm 0.15 Ho 0.03 GeO 4 , NaY 0.815 Tm 0.15 Ho 0.035 GeO 4 samples with the Tm3+/Ho3+ ratio close to 5/1. The luminescence decay kinetics has been studied and the rate of energy transfer from Tm3+ to Ho3+ ions has been calculated. The obtained results indicate an effective energy transfer accelerated by migration due to dipole-dipole interaction. The mechanism of excitation and infrared luminescence in NaYGeO 4 :Tm3+, Ho3+ phosphors has been proposed. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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