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1.
Luminescence ; 38(4): 469-476, 2023 Apr.
Article in English | MEDLINE | ID: mdl-36849109

ABSTRACT

The luminescent properties and energy transfer (ET) mechanism in the Ln3+ pair of the RE3+ (RE = Eu3+ , Ce3+ , Dy3+ and Sm3+ ) doped K4 Ca(PO4 )2 phosphor were successfully investigated using a conventional high-temperature solid-state reaction. In the near infrared (NIR) range, Ce3+ -doped K4 Ca(PO4 )2 phosphor exhibited a UV-Vis. emission band, whereas K4 Ca(PO4 )2 :Dy3+ exhibited characteristic emission bands centred at 481 and 576 nm in the near-ultraviolet excitation range. The possibility of ET from Ce3+ to Dy3+ in K4 Ca(PO4 )2 phosphor was confirmed by a significant increase in the photoluminescence intensity of the Dy3+ ion based on the spectral overlap of acceptor and donor ions. X-ray diffraction, Fourier-transform infrared and thermogravimetric analysis/differential thermal analysis TGA/DTA were carried out to study phase purity, presence of functional groups and amount of weight loss under different temperature regimes. Therefore, the RE3+ -doped K4 Ca(PO4 )2 phosphor may be a stable phosphor host for light-emitting diode applications.


Subject(s)
Europium , Luminescent Agents , Dysprosium , Luminescence , X-Ray Diffraction
2.
Luminescence ; 37(6): 1009-1017, 2022 Jun.
Article in English | MEDLINE | ID: mdl-35404541

ABSTRACT

This work presents the optimized luminescence spectra for the Ce3+ ,Sm3+ -doped NaSrPO4 phosphor that was synthesized using a wet chemical method. Ce3+ and Sm3+ are activator impurities that show spectral splitting bands that corresponds to the d-f and f-f transitions, respectively. These impurity elements shows the characteristics spectral bands when doped with the NaSrPO4 host lattice. Spectral splitting in the Ce3+ excitation band was monitored in the 240-340 nm range, in which the observed bands were located at 269 nm, 292 nm and 321 nm, and emission bands were observed in the broad spectral range 330-430 nm. However, when Sm3+ ion was doped in the same host lattice we obtained a characteristic emission band at 590 and 645 nm in the orange-red region, under sharp excitation bands located at 345, 361, 375, and 403 nm respectively. Also, we carried out energy transfer analysis in the Ce3+ /Dy3+ -doped NaSrPO4 phosphor. Further crystalline phase and the nanophase nature of the phosphor compound were confirmed using X-ray diffraction and transmission electron microscopy analyses.

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