4 f n−1 5 d  centroid shift in lanthanides and relation with anion polarizability, covalency, and cation electronegativity

Dorenbos, P.; Andriessen, J.; Eijk, C.W.E. van

doi:10.1016/s0022-4596(02)00196-2

Cited by 77 publications

(51 citation statements)

References 17 publications

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“…In these expressions, α sp and β Q poly are empirical parameters, introduced by Dorenbos [49,50]. Equation (B3) was originally introduced for Ce 3+ , but the theoretical basis for this empirical relation is more generally valid for 4f N 5d 1 configurations as was derived by Morrison, based on a suggestion of Judd [50,51].…”

Section: Discussionmentioning

confidence: 99%

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: Discussionmentioning

confidence: 99%

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

2014

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“…Introduction of the trivalent cerium ion (Ce 3+ , 4f 1 ) into inorganic matrices, in contrast, gives rise to a broaden and high intensity emission band in the blue-UV spectral range assigned to interconfigurational 5d → 4f transition allowed by the parity rule [21]. Moreover, the tetravalent cerium ion (Ce 4+ , 4f 0 ) has an empty electronic configuration.…”

Section: Photoluminescence Behaviormentioning

confidence: 99%

Optical and electrical characterization of samaria-doped ceria

Souza¹,

Brito

Muccillo³

2010

Journal of Alloys and Compounds

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“…10 Other reasons why the red band was called and is still called anomalous are that it falls out of the framework and model that has been created for lanthanide ions in crystals using crystal field theory and because the electronic structure of such an excited state cannot be described nor predicted from it. Nevertheless, McClure and collaborators transcended the model and, from experiments alone, envisaged and described, with surprising precision, the characteristics of the electronic structure of the excited state responsible for the anomalous luminescence.…”

Section: Introductionmentioning

confidence: 99%

Yb 2 + -doped SrCl2: Electronic structure of impurity states and impurity-trapped excitons

Sánchez‐Sanz

Seijo

Barandiarán

2010

The Journal of Chemical Physics

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First principles electronic structure calculations of the excited states of Yb 2+ -doped SrCl 2 crystals up to 65000 cm −1 reveal the existence of unexpected excited states with double-well potential energy surfaces and dual electronic structure lying above and very close in energy to the 4f 13 5d manifold, with which they interact strongly through spin-orbit coupling. The double-well energy curves result from avoided crossings between Yb-trapped exciton states (more stable at short YbCl distances) and 4f 13 6s impurity states (more stable at long Yb-Cl distances); the former are found to be pre-ionization states in which the impurity holds the excited electron in close lying empty interstitials located outside the YbCl 8 moiety. Spin-orbit coupling between the double-well states and lower lying 4f 13 5d impurity states spreads the dual electronic structure character to lower energies and, hence, the instability of the divalent oxidation state is also spread. To some extent, the dual electronic structure (impurity-trapped exciton -impurity state) of some excited states expresses and gives support to hypotheses of interaction between Yb 2+ and Yb 3+ pairs proposed to understand the complex spectroscopy of the material and conciliates these hypotheses with interpretations in terms of the existence of only one type of Yb 2+ defect. The results presented confirm the presence of impurity states of the 4f 13 6s configuration among the 4f 13 5d manifolds, as proposed in the literature, but their energies are very different from those assumed.The Yb-trapped excitons found in this chloride host can be seen as precursors of the luminescent Yb-trapped excitons characterized experimentally in the isomorphous SrF 2 crystals.

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4 f n−1 5 d centroid shift in lanthanides and relation with anion polarizability, covalency, and cation electronegativity

Cited by 77 publications

References 17 publications

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

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

Optical and electrical characterization of samaria-doped ceria

Yb 2 + -doped SrCl2: Electronic structure of impurity states and impurity-trapped excitons

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