Doubly-valent rare-earth ions in halide crystals

Cuesta‐Rubio, Osmany

doi:10.1016/0022-3697(91)90062-5

Cited by 228 publications

(10 citation statements)

References 188 publications

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“…Previous research attributed a defect emitting at 453 nm in NaBr:Eu 2+ to a EuBr 2 -type precipitate, and emission at 461 nm in NaI:Eu 2+ to a EuI 2 -type precipitate. 14 The emission shown in Figure 5c, supported by the larger bandwidth shown in Figure 5d, might therefore also be attributed to a EuBr 2 - or EuI 2 -type precipitate, or a mixture thereof. The band’s emission center shifts to lower energies with increasing Eu concentration.…”

Section: Results and Discussionmentioning

confidence: 81%

“…These emissions are attributed to substitutional defects, where Eu 2+ replaces Na + combined with a charge-compensating defect outside of the first coordinating sphere. 14 Between NaBr and NaI, the only changes in this first coordinating sphere are the type of the anions (becoming more electronegative from Br to I) and the distance of the anions (having a larger ionic radius from Br to I). From a well-mixed phase that follows Vegard’s law we would therefore expect the emission to change fluently from NaBr at 428 nm to NaI at 441 nm, regardless of Eu concentration.…”

Section: Results and Discussionmentioning

confidence: 99%

“…The centers of the e g and t 2g levels are taken as the center of gravity (first moment) and their bandwidths as the second moment of their respective excitation bands. 14 Dotted lines are drawn through the centers of the e g and t 2g levels and the emission energies as a guide to the eye. The crystal field splitting is shown as a red dashed curve.…”

Section: Results and Discussionmentioning

confidence: 99%

“…For instance, KCl 1– x Br x crystals doped with Eu 2+ have shown this fluent shifting of emission. 14 Therefore, to illustrate the capabilities of the method, we have chosen a continuously varying mixed-phase library of NaBr:Eu 2+ and NaI:Eu 2+ as an example. While the individual phosphors have previously been researched, 14 the behavior of the mixed-phase phosphor has not yet been studied.…”

Section: Introductionmentioning

confidence: 99%

“…14 Therefore, to illustrate the capabilities of the method, we have chosen a continuously varying mixed-phase library of NaBr:Eu 2+ and NaI:Eu 2+ as an example. While the individual phosphors have previously been researched, 14 the behavior of the mixed-phase phosphor has not yet been studied. The end points of this library are therefore well-known, while the mixed-phase in between provides new data on the behavior of mixed binary halides.…”

Section: Introductionmentioning

confidence: 99%

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Method for the Detailed Characterization of Cosputtered Inorganic Luminescent Material Libraries

Merkx

Kolk

2018

ACS Comb. Sci.

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Understanding the behavior of combinatorially developed luminescent materials requires detailed characterization methods that have been lacking thus far. We developed a device for directly surveying the luminescent properties of thin-film libraries created through combinatorial gradient sputter deposition. Step-scan recorded excitation-, emission- and luminescence decay spectra of a thin-film library were resolved and combined with EDX measurements on the same film, relating composition to luminescent properties. This technique was applied to a single-substrate gradient thin-film library of NaBr0.73I0.27 to NaBr0.09I0.91, doped with 6.5% to 16.5% Eu2+. This gradient film closely followed Vegard’s law, with emission fluently shifting from 428 to 439 nm. In comparison, pure NaBr:Eu2+ showed emission at 428 nm and NaI:Eu2+ at 441 nm. Luminescence decay measurements demonstrated a great degree of concentration quenching in the gradient film. From these measurements we could conclude that an optimized phosphor would most efficiently luminesce when close to NaI:Eu2+. This gradient film confirmed that the method presented in this work allows to both study and optimize luminescent behavior in a broad range of host- and dopant systems.

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Section: Results and Discussionmentioning

confidence: 81%

Section: Results and Discussionmentioning

confidence: 99%

Section: Results and Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Method for the Detailed Characterization of Cosputtered Inorganic Luminescent Material Libraries

Merkx

Kolk

2018

ACS Comb. Sci.

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Applications of the group-function theory to the field of materials science

Seijo

Barandiarán

1996

Int. J. Quantum Chem.

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The group-function theory, as proposed by McWeeny for the study of weak intermolecular interactions and developed by Huzinaga in the context of valence-electron methods, is shown to be applicable to the ab initio study of tunable solid-state laser materials made of defective ionic crystals. The applicability of the theory relies on the existence of local electronic states (to which the demonstrated/potential laser activity is ascribed), which are essentially localized in a small cluster of atoms including the defect and whose electron correlation interactions with the surrounding crystal components are negligible. According to the group-function formalism, it is possible (a) to neglect electron correlation effects beyond the defect cluster and (b) to define a quantum mechanical embedding potential which embodies the rest of the so-called host effects. Computationally, the theory becomes applicable as the embedding potential is approximated through ab initio model potentials (AIMP). The results of AIMP embedded-cluster calculations demonstrate that it is possible to calculate the local structure and spectroscopy of the active defect at an ab initio level, the attainable accuracy being comparable to the usual one in molecular ab initio studies in the gas phase. Also, in this article, we present a systematic study of the local distortions produced upon doping divalent first-series transition-metal ions in rock-salt oxides, MOMe2+ (M=Mg, Ca, Sr; Me=Sc-Zn) and TIt in KMgF, and KF hosts. This study leads to the calculation of the local structures of the defects in these materials, which have not been measured. The results suggest that the use of the mismatch of the empirical ionic radii of the impurity and the substituted ion in order to pre$ct local distortions in doped ionic crystals is not significant when it is smaller than 0.1 A, and when it is larger, it should be weighted by a reduction factor depending on the host. For the first-series divalent transition-metal ion impurities, this factor is shown to be 0.15 for SrO, 0.25 for CaO, and around 0.50 for MgO.

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Cathodoluminescence and Optically Active Regions of Intrinsic and Induced Defects in Eu2+-Doped KCl Crystals

Aceves

Pérez‐Salas

Pal

2002

phys. stat. sol. (b)

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PACS: 78.55.Fv; 78.60.Hk; 78.60.Kn Cathodoluminescence (CL) spectra and images of KCl : Eu 2+ have been measured between 80 and 300 K. The CL broad band observed in the spectrum has been assigned to the well known 4f 6 5d ! 4f 7 electronic transition of the Eu 2+ ions and to the "off center" p luminescence (STE) modified by the F center absorption band (F center self-absorption). By studying the CL emissions at different temperatures it is found that the europium ions interfere the dynamics of the defect formation in KCl. In addition, the CL images have revealed the optically active zones in both the doped and pure samples.

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Doubly-valent rare-earth ions in halide crystals

Cited by 228 publications

References 188 publications

Method for the Detailed Characterization of Cosputtered Inorganic Luminescent Material Libraries

Method for the Detailed Characterization of Cosputtered Inorganic Luminescent Material Libraries

Applications of the group-function theory to the field of materials science

Cathodoluminescence and Optically Active Regions of Intrinsic and Induced Defects in Eu2+-Doped KCl Crystals

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