Luminescence and x-ray absorption measurements of persistent SrAl<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msub><mml:mrow /><mml:mn>2</mml:mn></mml:msub></mml:math>O<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msub><mml:mrow /><mml:mn>4</mml:mn></mml:msub></mml:math>:Eu,Dy powders: Evidence for valence state changes

Korthout, Katleen; Eeckhout, Koen Van den; Botterman, Jonas; Nikitenko, Sergey I.; Poelman, Dirk; Smet, Philippe

doi:10.1103/physrevb.84.085140

Cited by 110 publications

(85 citation statements)

References 31 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…YPO 4 :Ce,RE [42], cannot be confirmed nor rejected at this stage. Recently, no valence state change upon trapping was observed for Dy 3+ in SrAl 2 O 4 :Eu 2+ ,Dy 3+ [43]. Surely, further research into the physical and chemical nature of the trap states is required.…”

Section: Discussionmentioning

confidence: 99%

Temperature and wavelength dependent trap filling in M2Si5N8:Eu (M=Ca, Sr, Ba) persistent phosphors

Smet¹,

Eeckhout²,

Bos³

et al. 2012

Journal of Luminescence

View full text Add to dashboard Cite

The evaluation of persistent phosphors is often focused on the processes right after the excitation, namely on the shape of the afterglow decay curve and the duration of the afterglow, in combination with thermoluminescence glow curve analysis. In this paper we study in detail the trap filling process in europium-doped alkaline earth silicon nitrides (Ca 2 Si 5 N 8 :Eu, Sr 2 Si 5 N 8 :Eu and Ba 2 Si 5 N 8 :Eu), i.e., how the persistent luminescence can be induced. Both the temperature at which the phosphors are excited and the spectral distribution of the excitation light on the ability to store energy in the phosphors' lattices are investigated. We show that for these phosphors this storage process is thermally activated upon excitation in the lower 5d excited states of Eu 2+ , with the lowest thermal barrier for europium doped Ca 2 Si 5 N 8 . Also, the influence of co-doping with thulium on the trap filling and afterglow behavior is studied. Finally there exists a clear relation between the luminescence quenching temperature and the trap filling efficiency. The latter relation can be utilized to select new efficient 5d-4f based afterglow phosphors. 2 Center for Nano-and Biophotonics (NB-Photonics), Ghent University, Belgium.

show abstract

Section: Discussionmentioning

confidence: 99%

Temperature and wavelength dependent trap filling in M2Si5N8:Eu (M=Ca, Sr, Ba) persistent phosphors

Smet¹,

Eeckhout²,

Bos³

et al. 2012

Journal of Luminescence

View full text Add to dashboard Cite

show abstract

“…This makes it a versatile tool to study persistent luminescent materials since the dopant concentration will usually be very low. [18][19][20][21][22][23][24][25][26][27][28] …”

Section: Introductionmentioning

confidence: 99%

The importance of inversion disorder in the visible light induced persistent luminescence in Cr³⁺doped AB₂O₄(A = Zn or Mg and B = Ga or Al)

Basavaraju

Priolkar

Gourier

et al. 2015

Phys. Chem. Chem. Phys.

131

110

View full text Add to dashboard Cite

Cr 3+ doped spinel compounds AB 2 O 4 with A=Zn, Mg and B=Ga, Al exhibit a long near infrared persistent luminescence when excited with UV or X-rays. In addition, persistent luminescence of ZnGa 2 O 4 and to a lesser extent MgGa 2 O 4 , can also be induced by visible light excitation via 4 A 2 → 4 T 2 transition of Cr 3+ , which makes these compounds suitable as biomarkers for in vivo optical imaging of small animals. We correlate this peculiar optical property with the presence of antisite defects, which are present in ZnGa 2 O 4 and MgGa 2 O 4 . By using X-ray absorption fine structure (XAFS) spectroscopy, associated with electron paramagnetic resonance (EPR) and optical emission spectroscopy, it is shown that an increase in antisite defects concentration results in a decrease in the Cr-O bond length and the octahedral crystal field energy. A part of the defects are in the close environment of Cr 3+ ions, as shown by the increasing strain broadening of EPR and XAFS peaks observed upon increasing antisite disorder. It appears that ZnAl 2 O 4 , which exhibits the largest crystal field splitting of Cr 3+ and the smallest antisite disorder, does not show considerable persistent luminescence upon visible light excitation as compared to ZnGa 2 O 4 and MgGa 2 O 4 . These results highlight the importance of Cr 3+ ions with neighboring antisite defects in the mechanism of persistent luminescence exhibited by Cr 3+ doped AB 2 O 4 spinel compounds.

show abstract

“…By means of x-ray absorption techniques, it was indeed shown that an oxidation of europium ions in SrAl 2 O 4 :Eu,Dy occurred during the charging process [34].…”

Section: F Trapping Mechanismmentioning

confidence: 99%

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

2014

View full text Add to dashboard Cite

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)%.

show abstract

Luminescence and x-ray absorption measurements of persistent SrAl2O4:Eu,Dy powders: Evidence for valence state changes

Cited by 110 publications

References 31 publications

Temperature and wavelength dependent trap filling in M2Si5N8:Eu (M=Ca, Sr, Ba) persistent phosphors

Temperature and wavelength dependent trap filling in M2Si5N8:Eu (M=Ca, Sr, Ba) persistent phosphors

The importance of inversion disorder in the visible light induced persistent luminescence in Cr³⁺doped AB₂O₄(A = Zn or Mg and B = Ga or Al)

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

Contact Info

Product

Resources

About

Luminescence and x-ray absorption measurements of persistent SrAl2O4:Eu,Dy powders: Evidence for valence state changes

Cited by 110 publications

References 31 publications

Temperature and wavelength dependent trap filling in M2Si5N8:Eu (M=Ca, Sr, Ba) persistent phosphors

Temperature and wavelength dependent trap filling in M2Si5N8:Eu (M=Ca, Sr, Ba) persistent phosphors

The importance of inversion disorder in the visible light induced persistent luminescence in Cr3+doped AB2O4(A = Zn or Mg and B = Ga or Al)

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

Contact Info

Product

Resources

About

The importance of inversion disorder in the visible light induced persistent luminescence in Cr³⁺doped AB₂O₄(A = Zn or Mg and B = Ga or Al)