Scintillation Efficiency Improvement by Mixed Crystal Use

Gektin, A.; Belsky, A.; Vasil’ev, A. N.

doi:10.1109/tns.2013.2277883

Cited by 82 publications

(52 citation statements)

References 23 publications

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“…[ 146,147 ] In Ce-doped and Y-admixed LuAG, an increase in the light yield of about 10% compared to LuAG:Ce was reported. [ 150 ] Finally, due to the fact that all these Ce-or Prdoped garnet crystals are grown in an atmosphere which contains little (1-2%) or no oxygen, the post-growth annealing in air at elevated temperatures can also contribute to a light yield increase due to the reduction of the oxygen-vacancy concentration and related deep electron traps. This increase is ascribed to the effect of trap depth tuning, so as to maximize the light yield just around room temperature.…”

Section: Reviewmentioning

confidence: 99%

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

Nikl

Yoshikawa

2015

Advanced Optical Materials

580

352

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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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Section: Reviewmentioning

confidence: 99%

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

Nikl

Yoshikawa

2015

Advanced Optical Materials

580

352

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“…Usage of aliovalent codopants [6], bandgap engineering [7] and solid solution concept [8] are some of the recipes which led to high performance commercially successful materials.…”

Section: Introductionmentioning

confidence: 99%

The role of cerium variable charge state in the luminescence and scintillation mechanism in complex oxide scintillators: The effect of air annealing

Nikl

Babin

Mareš

et al. 2016

Journal of Luminescence

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a b s t r a c tThe influence of annealing in air at elevated temperatures on the absorption, luminescence and scintillation characteristics was studied for a set of Ce-doped aluminum garnet and perovskite single crystals. Positive effects consisting mainly in increase of light yield and decrease of afterglow were found to varying extent in all the materials. It is explained by the positive role of created stable Ce 4 þ center in scintillation mechanism and by decrease of deep trap concentration based on oxygen vacancies.

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“…Similar behavior of LY (a curve with a maximum) with introduction of substituting cations was recorded for many mixed crystals (see f.i. 45 and references therein). For a more complete picture it seems feasible to check if the dependence of Ce 3+ emission intensities on Tb 3+ concentration under UV excitation in the host (<200 nm) resembles one under cathode rays.…”

Section: Discussionmentioning

confidence: 99%

Scintillator-Oriented Investigation of Y₃Al₅O₁₂:Ce,Tb Powders

Khanin

Dongen

Buettner

et al. 2015

ECS J. Solid State Sci. Technol.

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The spectral and kinetic characteristics of YAG:Ce,Tb powders (with Tb 3+ concentration varying up to 100%, relative to Y) using cathode-ray and UV excitations were determined. The energy diagram of YAG:Ce,Tb was constructed and energy transfer processes in the compound were studied. The most effective resonance energy transfer takes place at Tb 3+ concentrations of 20%. There is no evidence of Ce 3+ →Tb 3+ energy back transfer for (Y,Tb)AG:Ce even in high resolution spectra. The optimal Tb 3+ content for maximum light output of YAG:Ce,Tb was determined to be 20% and for lowest afterglow 100%.Oxide materials based on garnet structure crystals are promising candidates for scintillator applications. 1 The garnets have good chemical and radiation stability, exhibit excellent mechanical properties, and show efficient luminescence when doped with lanthanide ions. Among other candidates, the Ce 3+ -doped Y 3 Al 5 O 12 (YAG:Ce) scintillator possesses sufficient luminous efficiency, short decay time (∼65 ns), and appropriate density (4.55 g/cm 3 ) comparable to that of CsI (Tl) crystals (4.51 g/cm 3 ). 2 Moreover, the emission located at 550 nm matches well to the Si photoelectric diode detecting range. The long wavelength emission for interconfigurational 5d-4f transitions of Ce 3+ ion in YAG is caused by large crystal field splitting of 5d orbitals. 3 At present, Ce 3+ -doped YAG is the most widely used phosphor in white light LEDs. The combination of (In,Ga)N blue emission and YAG:Ce yellow emission results in bright white light sources. 4 The light yield of YAG:Ce scintillator is less than its theoretical limit, which can be estimated to be 60 000 photons/MeV. 5 However, experimental studies report lower values of ∼ 25 000 photons/MeV. 6 The discrepancy may be related to native host lattice defects (vacancies, anti-sites, dislocations) which trap electrons and holes, thus decreasing the efficiency of energy transfer from matrix to activator or even leading to non-radiative recombination. 6,7 In addition to low efficiency, some afterglow is also observed, which likewise points to a role of defects in the garnets. To compete with trapping by defects, a higher activator concentration may be used; however, this usually leads to concentration quenching.Improving the emission properties of YAG:Ce phosphor can be achieved by incorporation of a co-dopant, in particular Tb 3+ . In some Ce 3+ ,Tb 3+ double doped silicates and perovskites, energy transfer from Ce 3+ to Tb 3+ occurs. 8 Ce 3+ to Tb 3+ energy transfer is also widely applied in phosphors for high quality fluorescent lamps. In order to get efficient Tb 3+ →Ce 3+ transfer it is necessary that the lowest d (5d 1 ) state of Ce 3+ is located at slightly lower energy than the excited 5 D 4 level of Tb 3+ . It is known that the energy of the 5d 1 state of Ce 3+ decreases with reduction of center symmetry, shortening of the Ce-anion distance and reduction in coordination number (also leading to shorter Ce-anion distances). 9 These conditions are partially fulfilled in the ...

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Scintillation Efficiency Improvement by Mixed Crystal Use

Cited by 82 publications

References 23 publications

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

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

The role of cerium variable charge state in the luminescence and scintillation mechanism in complex oxide scintillators: The effect of air annealing

Scintillator-Oriented Investigation of Y₃Al₅O₁₂:Ce,Tb Powders

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Scintillation Efficiency Improvement by Mixed Crystal Use

Cited by 82 publications

References 23 publications

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

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

The role of cerium variable charge state in the luminescence and scintillation mechanism in complex oxide scintillators: The effect of air annealing

Scintillator-Oriented Investigation of Y3Al5O12:Ce,Tb Powders

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Scintillator-Oriented Investigation of Y₃Al₅O₁₂:Ce,Tb Powders