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  • Küçük Resim
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    Dy3+and Eu3+co-activated gadolinium aluminate borate phosphor: Synthesis, enhanced luminescence, energy transfer and tunable color
    (Pergamon-Elsevier Science Ltd, 2023) Madkhali, O.; Kaynar, Umit H.; Kaynar, S. Cam; Ayvacikli, M.; Can, N.
    The synthesis of GdAl3(BO3)4 phosphors incorporated with activators of Dy3+ and Dy3+/ Eu3+was successful and achieved through the gel combustion method. Powder X-ray diffraction (XRD) was employed to identify phase purity and the effects of dopant concentration on the crystallographic structure. The results of Photo-luminescence (PL) measurements revealed that the intensity and lifetime of luminescence properties varied depending on the concentrations of Dy3+ and Eu3+ ions. The dependence of luminescence intensity on doping concentration is investigated with respect to the energy transfer process between Eu3+ and Dy3+ ions. A decrease in luminescence lifetime occurs with increasing concentrations of Eu3+ co-doping. The energy transfer was also investigated using decay curve analysis. The co-doping of Eu3+ significantly boosts the energy transfer efficiency from 26% to 84%. These findings make GdAl3(BO3)4: Dy3+, Eu3+ phosphors an ideal choice for LED applications in solid state lighting and displays.
  • Küçük Resim
    Öğe
    Structural and temperature dependence luminescence characteristics of RE (RE=Eu3+, Dy3+, Sm3+and Tb3+) in the new gadolinium aluminate borate phosphor
    (Elsevier Sci Ltd, 2023) Madkhali, O.; Kaynar, Umit H.; Alajlani, Y.; Coban, M. B.; Guinea, J. Garcia; Ayvacikli, M.; Pierson, J. F.
    GdAl3(BO3)4:Dy3+, Sm3+, Eu3+, and Tb3+ samples were successfully achieved via a sol-gel combustion method. The observed XRD analysis confirms the formation of the desired GAB host, indicating rhombohedral structures that agree well with JPCD card number 72-1985. The FTIR analyses show the detection of B -O stretching and B -O -B bending modes as well as Al -O and Gd -O bonds in the phosphor samples. Energy dispersive spectroscopy (EDS) analysis reveals that Sm, Eu, Dy, and Tb have been successfully doped into GdAl3(BO3)4. The observed broad intrinsic luminescence band can be caused by oxygen-induced luminescence defects in the GAB host with hydrous precursors. The luminescence properties of rare earth ion-doped GdAl3(BO3)4 samples are analysed by photoluminescence spectra, showing their optimal doping concentrations and critical distances of Dy3+, Eu3+, Sm3+ and Tb3+ are 2 wt% -25.8 angstrom, 7 wt% -17 angstrom, 1 wt% -32.59 angstrom, and 7 wt% -17.03 angstrom. Additionally, the energy transfer mechanism for luminescence quenching was determined as dipole-dipole (for Dy3+, Eu3+, and Tb3+) or dipole-quadrupole (for Sm3+) and the cross-relaxation process. GdAl3(BO3)4 samples obtained by doping with different RE3+ ions exhibit intense light emissions with different colors originating from different RE3+ ions under 349 nm excitation. When doped with different concentrations of RE3+ ions, the luminescence properties of the samples changed. The synthesized luminescence materials have potential ap-plications in lighting and display technologies.