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Trivalent europium-doped strontium molybdate red phosphors in white light-emitting diodes: Synthesis, photophysical properties and theoretical calculations
- Source :
-
Acta Materialia . Sep2012, Vol. 60 Issue 15, p5399-5407. 9p. - Publication Year :
- 2012
-
Abstract
- Abstract: Eu3+-doped strontium molybdate red phosphors (Sr1− x MoO4:Eu x (x =0.01–0.2)) for white light-emitting diodes (LED) were synthesized by the solid-state reaction method. The fluorescent intensities of the as-prepared phosphors were remarkably improved. The excitation and emission spectra demonstrate that these phosphors can be effectively excited by the near-UV light (395nm) and blue light (466nm). Their emitted red light peaks are located at 613nm, and the highest quantum yield value (η) of the as-grown red phosphor, which is 95.85%, is much higher than that of commercial red phosphor (77.53%). These red phosphors plus commercial yellow powers (1:10) were successfully packaged with the GaN-based blue chips on a piranha frame by epoxy resins. The encapsulated white LED lamps show high performance of the CIE chromaticity coordinates and color temperatures. Moreover, to explain the fluorescent spectra of these phosphors, a complete 3003×3003 energy matrix was successfully built by an effective operator Hamiltonian including free ion and crystal field interactions. For the first time, the fluorescent spectra for Eu3+ ion at the tetragonal (S 4) Sr2+ site of SrMoO4 crystal were calculated from a complete diagonalization (of energy matrix) method. The fitting values are close to the experimental results. [Copyright &y& Elsevier]
Details
- Language :
- English
- ISSN :
- 13596454
- Volume :
- 60
- Issue :
- 15
- Database :
- Academic Search Index
- Journal :
- Acta Materialia
- Publication Type :
- Academic Journal
- Accession number :
- 79339179
- Full Text :
- https://doi.org/10.1016/j.actamat.2012.06.052