ESR and optical study of [Cl−2] centre in BaClF crystal

Yuste, M.; Taurel, L.; Rahmani, Marzieh

doi:10.1016/0038-1098(75)90620-1

Cited by 32 publications

(11 citation statements)

References 5 publications

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“…allows one to conclude that Vk in-plane configuration with Tmig ~ 130 K[35] fits well the proposed linear relation, and to predict that the Vk migration for out-of-plane We suggest that only experiments at temperatures below LHeT could help to observe this type of defects.From the viewpoint of scintillator engineering, materials are required with fast hole diffusion (and thus recombination) at room temperatures, which holds for STH with small lattice displacements and thus low delocalization temperatures, e.g. NaI.3.…”

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confidence: 58%

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Analysis of self-trapped hole mobility in alkali halides and metal halides

2017

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The small radius hole polarons (self-trapped holes (STH) known also as the Vk centres) are very common color centers observed in alkali halides and alkaline-earth halides. Their mobility controls the rate of secondary reactions between electron and hole defects and thus radiation stability/sensitivity of materials. We have analysed here the correlation between the temperatures at which hole polarons start migration in a series of alkali halides (fluorites, chlorides, bromides, iodides) and the lattice displacement around X2quasi-molecule. These results are especially important for identification of the selftrapped holes, for example, in novel scintillating materials such as SrI2, as well as in a large family of perovskite halides and more complex halide materials.

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confidence: 58%

“…Another example of complex materials is the family of metal fluorohalides, which are important media for X -ray and neutron imaging [35][36][37][38]. In BaFCl layered matlockite crystals, only Cl2in-plane configuration was found (see Table 4).…”

Section: Analysis Of the Sth Migrationmentioning

confidence: 99%

Analysis of self-trapped hole mobility in alkali halides and metal halides

2017

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“…Previous vacuum UV and X-ray luminescence investigations have reported a broad emission at 360 nm and attributed it to the radiative relaxation of self-trapped excitons , with a strongly off-center configuration to account for the large Stokes shift . Alternatively, electron spin resonance and luminescence investigations have assigned this emission to electron recombination with V k (Cl 2 – ) centers. , The cathodoluminescence observed at around 350 nm (in Figure ) may possibly be also attributed to an oxygen impurity defect. Oxygen is a common impurity in barium fluorohalides and typically forms two types of oxygen-vacancy centers.…”

Section: Resultsmentioning

confidence: 93%

Photoluminescence and Cathodoluminescence Properties of Nanocrystalline BaFCl:Sm³⁺ X-ray Storage Phosphor

2012

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Nanocrystalline BaFCl:Sm3+ is an efficient photoluminescent X-ray storage phosphor. To gain a better understanding of the storage mechanism, the photoluminescence and cathodoluminescence properties of nanocrystalline BaFCl:Sm3+ before and after X-irradiation were investigated. The results were compared with those obtained for microcrystalline BaFCl:Sm3+ prepared by high-temperature sintering. Significant differences in the local coordination environment of Sm3+ ions between the two samples were revealed by comparing the photoluminescence spectra at 2 and 293 K. From the cathodoluminescence microanalysis, it follows that the Sm3+ ions in the as-prepared nanocrystalline BaFCl:Sm3+ are mainly located on or close to the surface of the nanoparticles, whereas those in the microcrystalline sample are distributed homogeneously throughout the microcrystallites. For nanocrystalline BaFCl:Sm3+, the X-irradiation-induced reduction of Sm3+ to Sm2+ ions and the photoionization of Sm2+ to Sm3+ ions during photobleaching were investigated by monitoring the photoluminescence intensities of both Sm2+ and Sm3+ ions. The two processes can be modeled well assuming dispersive first-order kinetics, where the rate constant of the electron transfer is given by an exponential function of the distance between the shallow electron traps and the Sm3+ centers.

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“…Alternatively, electron paramagnetic resonance (EPR) and luminescence investigations have assigned the broad ∼360 nm emission to electron recombination with V k centers (Yuste et al, 1975; Chen et al, 2005). The V k center or self-trapped hole consists of a hole shared between two adjacent halide ions.…”

Section: Resultsmentioning

confidence: 99%

Cathodoluminescence Microanalysis of Irradiated Microcrystalline and Nanocrystalline Samarium Doped BaFCl

2012

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BaFCl:Sm3+ is an efficient photoluminescent storage phosphor for ionizing radiation. Cathodoluminescence (CL) microanalysis enables the Sm2+ and Sm3+ oxidation states of samarium doped BaFCl to be easily identified, provides information about electron-beam and X-ray induced modification of BaFCl:Sm, and enables the synthesis dependent spatial distribution of samarium dopants of <100 ppm concentration to be determined with sub-100 nm resolution at 295 K. CL spectroscopy of BaFCl:Sm particles reveals broad CL emissions at ≈ 360 and ≈500 nm associated with V k (Cl-) and oxygen-vacancy defects in the BaFCl host lattice and fine structure CL emissions associated with major 4GJ → 6HJ (Sm3+) and 5DJ → 7FJ (Sm2+) transitions. CL microanalysis shows samarium dopants are uniformly distributed in conventional sintered microcrystalline BaFCl:Sm. In contrast, CL investigations reveal that for BaFCl:Sm nanoparticles, which have been prepared using a co-precipitation method, with greatly improved Sm3+ → Sm2+ conversion efficiency, the samarium dopants are concentrated near the particle surface resulting in a BaFCl:Sm3+ shell surrounding the BaFCl core, which is stable to energetic irradiation.

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ESR and optical study of [Cl−2] centre in BaClF crystal

Cited by 32 publications

References 5 publications

Analysis of self-trapped hole mobility in alkali halides and metal halides

Analysis of self-trapped hole mobility in alkali halides and metal halides

Photoluminescence and Cathodoluminescence Properties of Nanocrystalline BaFCl:Sm³⁺ X-ray Storage Phosphor

Cathodoluminescence Microanalysis of Irradiated Microcrystalline and Nanocrystalline Samarium Doped BaFCl

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ESR and optical study of [Cl−2] centre in BaClF crystal

Cited by 32 publications

References 5 publications

Analysis of self-trapped hole mobility in alkali halides and metal halides

Analysis of self-trapped hole mobility in alkali halides and metal halides

Photoluminescence and Cathodoluminescence Properties of Nanocrystalline BaFCl:Sm3+ X-ray Storage Phosphor

Cathodoluminescence Microanalysis of Irradiated Microcrystalline and Nanocrystalline Samarium Doped BaFCl

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Photoluminescence and Cathodoluminescence Properties of Nanocrystalline BaFCl:Sm³⁺ X-ray Storage Phosphor