Luminescence of Eu2+ in barium and strontium aluminate and gallate

Poort, S. H. M.; Blokpoel, W. P.; Blasse, G.

doi:10.1021/cm00056a022

Cited by 402 publications

(292 citation statements)

References 1 publication

(1 reference statement)

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“…Upon lowering the temperature a second, blue, emission band becomes visible (λ max = 445 nm). Although less well studied as the green emission band, its presence has been reported earlier in several papers [16,17,26]. In the figure, the temperature dependency of both blue and green emission upon excitation with 370 nm is visible.…”

Section: A Photoluminescence Of Sral 2 O 4 :Eudysupporting

confidence: 52%

“…However, our reasoning above showed that the differences in bond lengths of the nine oxygen ligands are sufficient to explain the difference in excitation spectra. This implies that the difference in Stokes shifts should presumably have another cause than the one proposed by Poort et al [26].…”

Section: Stokes Shift In Sral 2 O 4 :Eu 2+mentioning

confidence: 77%

“…Nevertheless, several authors discarded this hypothesis because both sites are seemingly too similar to explain the large energy difference when judging on the emission bands [15,16,18]. As an alternative explanation, Poort et al [26] suggested that the two emission bands result from a possible preferential orientation of the d orbitals of Eu 2+ on Sr sites that appear to line up. Clabau et al [16] proposed that the blue emission band arises from the charge transfer from the fundamental level of the 4f 7 configuration of Eu 2+ to the valence band and is associated to a hole detrapping mechanism.…”

Section: Previously Suggested Origins Of Both Emission Bandsmentioning

confidence: 99%

“…This is the major contribution to the observed difference in emission wavelength between the two bands. Poort et al [26] attribute this difference in Stokes shift to a preferential orientation of a 5d orbital on one lattice site, but not on the other, due to interaction with the next nearest neighboring Sr 2+ ion. This assumption was made not only to explain the difference in Stokes shifts, but also the difference in the low energy offset of the excitation spectra.…”

Section: Stokes Shift In Sral 2 O 4 :Eu 2+mentioning

confidence: 99%

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Trapping and detrapping inSrAl2O4:Eu,Dypersistent phosphors: Influence of excitation wavelength and temperature

2014

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SrAl 2 O 4 :Eu,Dy is presumably the best known persistent luminescent phosphor. At room temperature, its green emission remains visible for hours after switching off the excitation. It is known that upon lowering the temperature of the phosphor a second photoluminescence emission band arises in the blue part of the visible spectrum, although its origin is still the subject of discussion. In this paper we thoroughly study the origin of both emission bands in SrAl 2 O 4 :Eu,Dy and we attribute this to europium ions substituting for the two different Sr sites in the phosphor's monoclinic host lattice. The photoluminescence properties, the thermal quenching behavior, and photoluminescence lifetime of both emission bands are investigated. A lanthanide energy level scheme is constructed for both sites. Using an integrated approach, i.e., combining charging, afterglow, and thermoluminescence measurements in the same run, we study the charging or trap filling processes in SrAl 2 O 4 :Eu,Dy upon excitation with site selective excitation wavelengths and at different temperatures. We show that trap filling is a thermally activated process when the green emitting center is excited at 435 nm.Furthermore, we also demonstrate that the distribution of filled traps after charging depends strongly on the excitation wavelength and thus on which Eu 2+ center has been excited. This suggests trapping of the electron close to the ionized Eu 2+ ion, without full delocalization to the conduction band during the trapping process. Finally, the quantum efficiency of the persistent luminescence is estimated at 65 (+/−10)%.

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Section: A Photoluminescence Of Sral 2 O 4 :Eudysupporting

confidence: 52%

Section: Stokes Shift In Sral 2 O 4 :Eu 2+mentioning

confidence: 77%

Section: Previously Suggested Origins Of Both Emission Bandsmentioning

confidence: 99%

Section: Stokes Shift In Sral 2 O 4 :Eu 2+mentioning

confidence: 99%

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Trapping and detrapping inSrAl2O4:Eu,Dypersistent phosphors: Influence of excitation wavelength and temperature

2014

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“…Eu 2+ doped BaAl 2 O 4 and SrAl 2 O 4 could be promising phosphor materials for plasma display panel (PDP) application [10,11]. SrAl 2 O 4 is one of the foremost promising host materials for fluorescent lamp, light emitting diodes, and persistent luminescent materials [12][13][14][15][16]. The effects of various doping compositions and impurities on the phosphorescence of green-emitting alkaline earth aluminate phosphor (SrAl 2 O 4 :Eu 2+ ,Dy 3+ ) have been reported by Kim et al [17].…”

Section: Introductionmentioning

confidence: 99%