Anomalous <SUP>5</SUP>D<sub>0</sub> → <SUP>7</SUP>F<sub>4</sub> transition induced by alkali ion co-doping in Eu<SUP>3+</SUP>-activated K<sub>7</sub>SrY<sub>2</sub>(B<sub>5</sub>O<sub>10</sub>)<sub>3</sub> borates: A Judd-Ofelt and photoluminescence analysis for pc-WLEDs
Creators
- 1. Princess Nourah bint Abdulrahman Univ, Coll Sci, Dept Phys, POB 84428, Riyadh 11671, Saudi Arabia
- 2. Manisa Celal Bayar Univ, Fac Engn & Nat Sci, Phys Dept, Manisa, Turkiye
- 3. Bakircay Univ, Fac Engn & Architecture, Dept Fundamental Sci, Izmir, Turkiye
- 4. Balikesir Univ, Fac Arts & Sci, Dept Phys, Balikesir, Turkiye
- 5. Jazan Univ, Coll Sci, Dept Phys Sci, Phys Div, POB 114, Jazan 45142, Saudi Arabia
- 6. Nigde Omer Halisdemir Univ, Fac Sci, Phys Dept, Nigde, Turkiye
- 7. Pamukkale Univ, Fac Technol, Dept Biomed Engn, TR-20070 Denizli, Turkiye
Description
In this study, red-emitting K7SrY2(B5O10)(3):Eu3+ phosphors were synthesized via high-temperature solid-state reaction. The effects of Li+ and Na+ co-doping on structural and photoluminescent properties were investigated. XRD and Rietveld refinement confirmed a phase-pure trigonal structure. Under 394 nm excitation, Li+ co-doping induced significant local lattice asymmetry, leading to a remarkable similar to 58-fold enhancement of D-5(0) -> F-7(4) transition, which is typically parity-forbidden. This behavior is further supported by the high Judd-Ofelt Omega(6) parameter (5.42 x 10(-20) cm(2)), indicating enhanced electric dipole character due to symmetry breaking. CIE chromaticity coordinates shifted toward deeper red emission with color purity up to 97.7 % and CCT as low as 2253 K. Temperature-dependent PL confirmed high thermal stability (E-a = 0.190 eV). These results demonstrate that Li+-induced symmetry distortion is a powerful strategy to enhance anomalous red emission, positioning KSYBO:Eu3+,Li+ as a promising red phosphor for pc-WLEDs.
Files
bib-2168d6a1-6c02-440b-b618-6db1e4f2d8b1.txt
Files
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