A series of Tb3+, Eu3+-doped Sr2MgSi2O7 (SMSO) phosphors were synthesized by high temperature solid-state reaction. X-ray diffraction (XRD) patterns, Rietveld refinement, photoluminescence spectra (PL), and luminescence decay curves were utilized to characterize each sample’s properties. Intense green emission due to Tb3+
5D4→7F5 transition was observed in the Tb3+ single-doped SMSO sample, and the corresponding concentration quenching mechanism was demonstrated to be a diople-diople interaction. A wide overlap between Tb3+ emission and Eu3+ excitationspectraresults in energy transfer from Tb3+ to Eu3+. This has been demonstrated by the emission spectra and decay curves of Tb3+ in SMSO:Tb3+, Eu3+ phosphors. Energy transfer mechanism was determined to be a quadrupole-quadrupole interaction. And critical distance of energy transfer from Tb3+ to Eu3+ ions is calculated to be 6.7 Å on the basis of concentration quenching method. Moreover, white light emission was generated via adjusting concentration ratio of Tb3+ and Eu3+ in SMSO:Tb3+, Eu3+ phosphors. All the results indicate that SMSO:Tb3+, Eu3+ is a promising single-component white light emitting phosphor.
Eu, Tb co-doped SrAl 2 Si 2 O 8 luminescent materials were synthesized via a high-temperature solid-state reaction. Excitation spectra of SrAl 2 Si 2 O 8 : Eu 2þ gives two broad excitation bands maximizing at 270 and 330 nm, resulting from splitting Eu 2þ energy levels in octahedral crystal field. Eu single doped SrAl 2 Si 2 O 8 luminescent material exhibits two emission bands at about 406 and 616 nm. Intensity of the blue emission from Eu 2þ is always strong, compared with that of the red emission band of Eu 3þ . Reduction from Eu 3þ to Eu 2þ can be explained with the model of charge compensation. Blue emission in SrAl 2 Si 2 O 8 : xEu was strengthened after incorporation of Tb, which can be explained by electron transfer from Tb 3þ to Eu 3þ Tb 3þ þ Eu 3þ ! Tb 4þ þ Eu 2þ À Á . Under 230 nm excitation, intensity of Tb 3þ emission was nearly unchanged and that of Eu 2þ was increased, obviously due to the delivery of more electrons to Eu 3þ . The strongest emission of Eu 2þ in 0.09Eu/0.06Tb codoped SrAl 2 Si 2 O 8 and excited at 270 and 330 nm was remarkably enhanced by about four times compared to that of 0.15Eu Single doped SrAl 2 Si 2 O 8 . All of the results indicate that SrAl 2 Si 2 O 8 : xEu, yTb are potential blue emitting luminescent materials for UV-LEDs. More importantly, this research may provide a new perspective in designing broad band blue luminescent materials.
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