The mechanism of long phosphorescence of SrAl2−xBxO4 (0&lt;x&lt;0.2) and Sr4Al14−xBxO25 (0.1&lt;x&lt;0.4) co-doped with Eu2+ and Dy3+

Nag, Abanti; Kutty, T.R.N.

doi:10.1016/j.materresbull.2003.11.007

Cited by 90 publications

(72 citation statements)

References 14 publications

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“…The band which is observed in the infrared spectrum can be attributed to symmetric stretching at γs(Al-O)= 688 cm - This indicates the presence of substitutional boron in AlO4 framework as Ba4Al14-xBxO25. When B2O3 was added as a flux, BO4 took place in the formation of structural units by breaking off the O-Al-O-Al-O bonds in the aluminate framework and forms O-Al-O-B-O bonds [13].…”

Section: Resultsmentioning

confidence: 99%

Synthesis, characterization and luminescence properties of long afterglow Phosphor Ba4Al14O25:Eu,Dy

2010

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Section: Resultsmentioning

confidence: 99%

Synthesis, characterization and luminescence properties of long afterglow Phosphor Ba4Al14O25:Eu,Dy

2010

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“…[5][6][7][8][9] Since the work by Matsuzawa et 26 For each of these compounds the model of Matsuzawa et al 1 is used to explain the mechanism. Experiments to elucidate the mechanism by means of thermoluminescence, 3,4 electron paramagnetic resonance ͑EPR͒, 14 and photoconductivity 1,2,5 were all interpreted in support of that mechanism. Hölsa and coworkers [27][28][29][30][31][32] are some of the few who disagree with the mechanism.…”

mentioning

confidence: 81%

“…The scheme shows that the ground state of Dy 2+ is located 0.9 eV below the bottom of the conduction band, and this value agrees with the trap depth of about 1 eV derived from thermoluminescence studies by Yamamoto and Matsuzawa 4 and Nag and Kutty. 14 An electron-trapping model was also suggested by Yuan et al 5 However, they rejected it because at that time holes were believed to be the transporting charge carriers.…”

Section: H108mentioning

confidence: 99%

Mechanism of Persistent Luminescence in Eu[sup 2+] and Dy[sup 3+] Codoped Aluminate and Silicate Compounds

Dorenbos

2005

J. Electrochem. Soc.

387

265

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A mechanism of persistent luminescence that was proposed in 1996 for SrAl 2 O 4 :Eu 2+ ;Dy 3+ has been widely adopted to explain afterglow in many Eu 2+ and Dy 3+ codoped aluminates and silicates. The mechanism involves the thermally activated release of a hole from Eu 2+ in its excited 5d state to the valence band which is subsequently trapped by Dy 3+ . In this work the location of the lanthanide energy levels relative to the valence and conduction band of various compounds is presented. It is shown that the mechanism of persistent luminescence cannot be correct. An alternative model that involves the ionization of the 5d electron to conduction band states and subsequent trapping by Dy 3+ is proposed. The level schemes are consistent, both qualitatively and quantitatively, with many observations regarding persistent luminescence. They also provide insight into the mechanism of thermal quenching of Eu 2+ 5d-4f emission. proposed the same mechanism for CaGa 2 S 4 :Eu 2+ . In mechanisms of persistent luminescence, luminescence quenching, and electroluminescence, the thermally activated ionization or field ionization of either electrons to the conduction band or holes to the valence band is an important aspect. To understand these mechanisms it is necessary to accurately know the location of the impurity states relative to the conduction band and the valence band. The problem is that hitherto this information has not been available, leading to mechanisms that rely on speculative ideas.Recently new methods have become available that make it possible to determine the absolute location of the lanthanide impurity levels. In this work we apply these methods to reconsider the mechanism of persistent luminescence and luminescence quenching. It is shown that the mechanism proposed by Matsuzawa et al. Results and DiscussionLevel schemes for CaGa 2 S 4 and SrAl 2 O 4 .-The method to determine the absolute location of the lowest 4f state and the lowest 5d state of divalent and trivalent lanthanide ions in compounds was presented in detail in previous papers and is not repeated here. 36,37Instead only the information used to construct the level schemes in the electroluminescence phosphor CaGa 2 S 4 and the persistent luminescence phosphor SrAl 2 O 4 is presented. Recently Bessiere et al. 38 determined the level scheme for CaGa 2 S 4 . The result is reproduced in Fig. 1 where zero energy is at the top of the valence band. E ex = 4.35 eV is the energy of exciton creation, i.e., a bound electron-hole pair. The energy E VC needed to create a free electron in the conduction band is at 4.9 eV. The lowest 4f and lowest 4f5d levels of the divalent and the trivalent lanthanides are drawn in the scheme as function of the number n in the 4f n state of the trivalent lanthanide. SrGa 2 S 4 has the same crystal structure as CaGa 2 S 4 and also approximately the same bandgap value. We therefore regard the level scheme for CaGa 2 S 4 also as representative for that of SrGa 2 S 4 .Ultraviolet and vacuum ultraviolet ͑VUV͒ studies by Kamada ...

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“…Recently, the addition of B 2 O 3 was found to incorporate as a BO 4 framework instead of AlO 4 in the SrAl 2 O 4 lattice [6,7]. The dissolved B 3+ ions were further observed to substitute Al 3+ ions at tetrahedral positions in isolated planes along [0 1 1] the SrAl 2 O 4 structure [8].…”

Section: Introductionmentioning

confidence: 99%

Characterizations of Eu, Dy co-doped SrAl2O4 phosphors prepared by the solid-state reaction with B2O3 addition

Chang

Hsiang

Liang

2008

Journal of Alloys and Compounds

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The mechanism of long phosphorescence of SrAl2−xBxO4 (0<x<0.2) and Sr4Al14−xBxO25 (0.1<x<0.4) co-doped with Eu2+ and Dy3+

Cited by 90 publications

References 14 publications

Synthesis, characterization and luminescence properties of long afterglow Phosphor Ba4Al14O25:Eu,Dy

Synthesis, characterization and luminescence properties of long afterglow Phosphor Ba4Al14O25:Eu,Dy

Mechanism of Persistent Luminescence in Eu[sup 2+] and Dy[sup 3+] Codoped Aluminate and Silicate Compounds

Characterizations of Eu, Dy co-doped SrAl2O4 phosphors prepared by the solid-state reaction with B2O3 addition

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