First principles calculations and experiment predictions for iodine vacancy centers in SrI<sub>2</sub>

Qi, Li; Williams, Richard; Åberg, Daniel

doi:10.1002/pssb.201200503

Cited by 17 publications

(6 citation statements)

References 48 publications

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“…58 A similar phenomenon is also evidenced in SrI 2 :Eu 2+ . The calculated trap depth for I vacancy with one electron (F center) and two electrons (F À center) in SrI 2 :Eu 2+ are 1.56 eV and 1.17 eV below the CBM, respectively, 59 much deeper than that of I vacancy (F + center).…”

Section: Point Defectsmentioning

confidence: 86%

Crystal structure, electronic structure, temperature-dependent optical and scintillation properties of CsCe₂Br₇

Shi

Chakoumakos

et al. 2015

J. Mater. Chem. C

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CsCe 2 Br 7 is a self-activated inorganic scintillator that shows promising performance, but the understanding of the important structure-property relationships is lacking. In this work, we conduct a comprehensive study on CsCe 2 Br 7 . The crystal structure of CsCe 2 Br 7 is refined using single crystal X-ray study for the first time. It crystallizes into the orthorhombic crystal system with Pmnb space group. Its electronic structure is revealed by density functional theory (DFT) calculations. Two cerium emission centers are identified and the energy barriers related to the thermal quenching to 4f ground states of Ce 3+ for these two Ce centers are evaluated. CsCe 2 Br 7 single crystal has better light yield and energy resolution than CsCe 2 Cl 7 , but with an additional slow decay component of 1.7 ms. The existence of a deep trap with a depth of 0.9 eV in CsCe 2 Cl 7 contributes to its higher afterglow level in comparison to that of CsCe 2 Br 7 . The most possible point defects in CsCe 2 Cl 7 and CsCe 2 Br 7 are proposed by considering the vapour pressure in the growth atmosphere upon melting point.ionic activators (in particular Bi 3+ , Ce 3+ and Eu 2+ ), is a constituent of the crystal, for example CaWO 4 and Self-activated single crystals of CsCe 2 X 7 (X = Cl, Br) were developed in 2010. 9-11 The CsCe 2 Cl 7 with a density of 3.6 g cm À3 can reach a gamma-ray excited light yield of 26 000 photons per MeV, but a 50% higher light yield is achieved in CsCe 2 Br 7 with a higher density of 4.0 g cm À3 . The phase diagrams of CsCe 2 Cl 7 12 and CsCe 2 Br 7 13,14 indicate that they both melt congruently. Recently, the crystal structure refinement revealed that CsCe 2 Cl 7 crystallizes in the monoclinic space group P112 1 /b. 15 However, despite the fact that the CsCe 2 Br 7 single crystal showed more promising scintillation properties, several fundamental questions, including structureproperty relationship, are still not understood: (i) the crystal structure and electronic structure; (ii) temperature dependent luminescent behaviors; (iii) the scintillation property comparisons between CsCe 2 Cl 7 and CsCe 2 Br 7 , including non-proportionality and afterglow; (iv) the trapping effect of point defects and their possible origins. All these questions lead us to carry out an in-depth study of CsCe 2 Br 7 . The paper is organized as follows. Firstly, the crystal

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Section: Point Defectsmentioning

confidence: 86%

Crystal structure, electronic structure, temperature-dependent optical and scintillation properties of CsCe₂Br₇

Shi

Chakoumakos

et al. 2015

J. Mater. Chem. C

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“…[ 99 ] They predict certain characteristics, such as absorption transitions, confi guration coordinate curves, vibrational lineshape, and thermal trap depth of the luminescence centers. [ 99 ] They predict certain characteristics, such as absorption transitions, confi guration coordinate curves, vibrational lineshape, and thermal trap depth of the luminescence centers.…”

Section: Theoretical Studiesmentioning

confidence: 99%

“…For the case of defects in halides, we mention the detailed fi rst principle calculations of electronic structure, lattice relaxation, and formation energies of iodine vacancy defects in SrI 2 for the one-electron, two-electron, and ionized charge states. [ 99 ] They predict certain characteristics, such as absorption transitions, confi guration coordinate curves, vibrational lineshape, and thermal trap depth of the luminescence centers. The above-mentioned study of Sr 2+ -doped LaBr 3 [ 73 ] proposes the Sr La -V Br shallow electron trap with its suggested specifi c role in the fi rst picoseconds of the scintillation mechanism.…”

Section: Reviewmentioning

confidence: 99%

Recent R&D Trends in Inorganic Single‐Crystal Scintillator Materials for Radiation Detection

Nikl

Yoshikawa

2015

Advanced Optical Materials

657

374

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In this review, the major achievements and research and development (R&D) trends from the last decade in the field of single crystal scintillator materials are described. Two material families are included, namely, those of halide and oxide compounds. In most cases, the host crystals are doped with Ce3+, Pr3+ or Eu2+ rare earth ions. Their spin‐ and parity‐allowed 5d–4f transitions enable a rapid scintillation response, on the order of tens to hundreds of nanoseconds. Technological recipes, extended characterization by means of optical and magnetic spectroscopies, and theoretical studies are described. The latter provide further support to experimental results and provide a better understanding of the host electronic band structure, energy levels of specific defects, and the emission centers themselves. Applications in medical imaging and dosimetry, security measures, high‐energy physics and the high‐tech industry, in which X(γ)‐rays or particle beams are used and monitored, are recognized as the main driving factor for R&D activities in this field.

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“…To compensate for the spurious interactions between the defects in neighboring cells, we used the finite-size correction scheme based on a multipole expansion [41,42] …”

Section: Ormentioning

confidence: 99%

Defect Engineering by Codoping in KCaI3:Eu2+ Single-Crystalline Scintillators

Jones

et al. 2017

Phys. Rev. Applied

Self Cite

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Eu2+ doped alkali or alkali earth iodide scintillators with energy resolutions ≤3% at 662 keV promise the excellent discrimination ability for radioactive isotopes required for homeland security and nuclear non-proliferation applications. To extend their applications to X-ray imaging, such as computed tomography scans, the intense afterglow which delays the response time of such materials is an obstacle that needs to be overcome. However, a clear understanding of the origin of the afterglow and feasible solutions is still lacking. In this work, we present a combined experimental and theoretical combined investigation of the physical insights of codoping-based defect engineering which can reduce the afterglow effectively in

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First principles calculations and experiment predictions for iodine vacancy centers in SrI₂

Cited by 17 publications

References 48 publications

Crystal structure, electronic structure, temperature-dependent optical and scintillation properties of CsCe₂Br₇

Crystal structure, electronic structure, temperature-dependent optical and scintillation properties of CsCe₂Br₇

Recent R&D Trends in Inorganic Single‐Crystal Scintillator Materials for Radiation Detection

Defect Engineering by Codoping in KCaI3:Eu2+ Single-Crystalline Scintillators

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First principles calculations and experiment predictions for iodine vacancy centers in SrI2

Cited by 17 publications

References 48 publications

Crystal structure, electronic structure, temperature-dependent optical and scintillation properties of CsCe2Br7

Crystal structure, electronic structure, temperature-dependent optical and scintillation properties of CsCe2Br7

Recent R&D Trends in Inorganic Single‐Crystal Scintillator Materials for Radiation Detection

Defect Engineering by Codoping in KCaI3:Eu2+ Single-Crystalline Scintillators

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First principles calculations and experiment predictions for iodine vacancy centers in SrI₂

Crystal structure, electronic structure, temperature-dependent optical and scintillation properties of CsCe₂Br₇

Crystal structure, electronic structure, temperature-dependent optical and scintillation properties of CsCe₂Br₇