Effects of increasing size and changing europium activator concentration in KCaI3 scintillator crystals

Lindsey, Adam C.; Zhuravleva, Mariya; Wu, Yuntao; Stand, Luis; Loyd, Matthew; Gokhale, S.; Koschan, Merry; Melcher, Charles L.

doi:10.1016/j.jcrysgro.2016.05.045

Cited by 21 publications

(5 citation statements)

References 13 publications

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“…The cracks originated from the stresses generated due to the different thermal expansions of ampule and crystal during cooling process. Similar phenomenon has been observed for the Bridgman growth of other alkali and alkaline earth iodides. , A ϕ22 mm × 19 mm crystal slab was cut from the cylinder region of the ingot and polished to evaluate the energy resolutions. The pulse height spectra of a ϕ22 mm × 19 mm long sample acquired with R6231-100 PMT under 137 Cs and 57 Co irradiation are shown in Figure c,d.…”

Section: Resultssupporting

confidence: 64%

“…The prolonged decay time with increasing Eu 2+ concentration in metal iodides, such as SrI 2 /Eu 2+ , KCaI 3 /Eu 2+ , and KCa 0.8 Sr 0.2 I 3 /Eu 2+ , is associated with a light trapping effect, the consequence of self-absorption of Eu 2+ centers. To compare the self-absorption effect in Cs 1.06 Sr 0.94 I 3 /Eu 2+ doped with different Eu 2+ concentrations, the values of the Stoke shift were evaluated by measuring the PL and PLE spectra.…”

Section: Resultsmentioning

confidence: 99%

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Toward High Energy Resolution in CsSrI₃/Eu²⁺ Scintillating Crystals: Effects of Off-Stoichiometry and Eu²⁺ Concentration

Gokhale

Lindsey

et al. 2016

Crystal Growth & Design

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CsSrI3/Eu2+ has very promising scintillation properties for gamma-ray spectroscopy applications, but it has proven difficult to grow high quality single crystals in large sizes. This paper reports a composition-engineering strategy, in this case a combination of off-stoichiometric melts and Eu2+ concentration optimization, to obtain large-size CsSrI3/Eu2+ crystals with excellent energy resolution. Crystals of a series of off-stoichiometric compositions, Cs(1+x)(Sr,Eu)(1–x)I(3–x) (x = 0, 0.05, 0.06, and 0.1), were grown by the Bridgman method. The Cs1.06Sr0.94I2.94/Eu2+ single crystal has the highest optical transmittance between 450 and 800 nm. Cs1.06Sr0.94I2.94 single crystals doped with 0.5, 1, 3, 5, and 7 mol % Eu2+ ions were also grown by the Bridgman method. The effects of Eu2+ concentration on the phase purity and optical and scintillation properties were studied. X-ray diffraction patterns confirmed the phase purity of all samples with the exception of a hydrate phase formed during measurement. Increasing Eu2+ concentration leads to longer decay components due to the effect of self-absorption. An unexpected relationship was found between the Eu2+ concentration and the appearance of two photopeaks in a pulse height spectrum acquired under a single gamma-ray energy of 662 keV irradiation. The origins of this phenomenon are proposed from experimental insights. The optimal composition we developed achieved an excellent energy resolution of 3.4% for ϕ22 mm × 2 mm, 3.9% for ϕ22 mm × 15 mm, and 4.1% for ϕ22 mm × 19 mm at 662 keV. The results of this paper lead to a better understanding of the effects of composition-engineering in optimization of nonstoichiometric scintillator compounds.

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Section: Resultssupporting

confidence: 64%

Section: Resultsmentioning

confidence: 99%

Toward High Energy Resolution in CsSrI₃/Eu²⁺ Scintillating Crystals: Effects of Off-Stoichiometry and Eu²⁺ Concentration

Gokhale

Lindsey

et al. 2016

Crystal Growth & Design

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“…Another result of low Eu 2+ concentration is the diminished excitation spectra intensity in the range of 250–340 nm. This effect has been observed in similar metal-halide scintillators doped with <5% Eu 2+ . Self-absorption is typical in Eu 2+ -doped compounds and is observed in the overlapping of the emission and excitation spectra.…”

Section: Resultssupporting

confidence: 53%

“…This effect has been observed in similar metal-halide scintillators doped with <5% Eu 2+ . 22 Self-absorption is typical in Eu 2+ -doped compounds and is observed in the overlapping of the emission and excitation spectra. Luminescence Kinetics.…”

Section: ■ Introductionmentioning

confidence: 99%

Discovery of New Compounds and Scintillators of the A₄BX₆ Family: Crystal Structure, Thermal, Optical, and Scintillation Properties

Johnson

Zhuravleva

Stand

et al. 2018

Crystal Growth & Design

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We report the discovery of four new compounds of Eu2+-doped scintillators [Cs3Rb]SrI6, [Cs3K]SrI6, [Cs3Rb]CaI6, and [Cs3K]CaI6. A compositional engineering strategy dictated by the structural systematics of the base compounds Cs4CaI6 and Cs4SrI6 (space group R3̅c-hexagonal basis) was conducted to confirm an ideal solid solution for this system. Substitution of smaller monovalent cations Rb1+ and K1+ for Cs1+, maintained the crystal structure, producing an ordered substitution. Crystals were initially grown doped with 0.5% Eu to compare scintillation properties, and a Eu2+ optimization study determined that 7% Eu was the ideal concentration. A 56 mm3 crystal of composition [Cs3.5Rb0.5]SrI6:Eu 7% gave the best measured scintillation performance with an absolute light yield of 75 000 ph/MeV and energy resolution of 3.3% at 662 keV.

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“…We found that crystal cracking can be effectively prevented by utilizing a carboncoated quartz ampoule with a bent capillary. 7,8 A high temperature gradient of 45 °C cm −1 at the solid-liquid interface can contribute to the suppression of the formation of visible inclusions caused by constitutional supercooling. 7 In this communication, we first report the growth of high quality 25 mm and 38 mm diameter KCa 0.8 Sr 0.2 I 3 :Eu 2+ single crystals with excellent scintillation properties grown using optimized Bridgman growth parameters.…”

mentioning

confidence: 99%

Growth of inch-sized KCa_0.8Sr_0.2I₃:Eu²⁺scintillating crystals and high performance for gamma-ray detection

Lindsey

Zhuravleva

et al. 2016

CrystEngComm

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Effects of increasing size and changing europium activator concentration in KCaI3 scintillator crystals

Cited by 21 publications

References 13 publications

Toward High Energy Resolution in CsSrI₃/Eu²⁺ Scintillating Crystals: Effects of Off-Stoichiometry and Eu²⁺ Concentration

Toward High Energy Resolution in CsSrI₃/Eu²⁺ Scintillating Crystals: Effects of Off-Stoichiometry and Eu²⁺ Concentration

Discovery of New Compounds and Scintillators of the A₄BX₆ Family: Crystal Structure, Thermal, Optical, and Scintillation Properties

Growth of inch-sized KCa_0.8Sr_0.2I₃:Eu²⁺scintillating crystals and high performance for gamma-ray detection

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Effects of increasing size and changing europium activator concentration in KCaI3 scintillator crystals

Cited by 21 publications

References 13 publications

Toward High Energy Resolution in CsSrI3/Eu2+ Scintillating Crystals: Effects of Off-Stoichiometry and Eu2+ Concentration

Toward High Energy Resolution in CsSrI3/Eu2+ Scintillating Crystals: Effects of Off-Stoichiometry and Eu2+ Concentration

Discovery of New Compounds and Scintillators of the A4BX6 Family: Crystal Structure, Thermal, Optical, and Scintillation Properties

Growth of inch-sized KCa0.8Sr0.2I3:Eu2+scintillating crystals and high performance for gamma-ray detection

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Toward High Energy Resolution in CsSrI₃/Eu²⁺ Scintillating Crystals: Effects of Off-Stoichiometry and Eu²⁺ Concentration

Toward High Energy Resolution in CsSrI₃/Eu²⁺ Scintillating Crystals: Effects of Off-Stoichiometry and Eu²⁺ Concentration

Discovery of New Compounds and Scintillators of the A₄BX₆ Family: Crystal Structure, Thermal, Optical, and Scintillation Properties

Growth of inch-sized KCa_0.8Sr_0.2I₃:Eu²⁺scintillating crystals and high performance for gamma-ray detection