Optical properties of lattice defects in α-Al2O3

Evans, Bruce D.; Pogatshnik, G. J.; Chen, Yok

doi:10.1016/0168-583x(94)96227-8

Cited by 175 publications

(100 citation statements)

References 29 publications

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“…The TL signal for sample 1 in the initial state (see Fig. 1a) is described by the known 415 nm luminescent band (3.0 eV) at T max ¼ 456 AE 3 K, which is caused by the F-centers (Evans et al, 1994). However, after the UV treatment of the sample (see Fig.…”

Section: Resultsmentioning

confidence: 99%

“…The F-centers are the main contributors to the overall TLD-500 luminescence signal, from which the absorbed dose is estimated. At the same time, a number of papers report a weaker luminescence in the 2.4 eV band, which is attributed to defects in the anion sublattice (F 2 -centers) (Evans et al, 1994;Kotomin and Popov, 1998;Pelenyov et al, 2001;Tale et al, 1996) or to interstitial aluminum atoms ðAl þ i À centersÞ (Evans and Stapelbroek, 1980;McKeever et al, 1999;Springis and Valbis, 1984;Vokhmintsev, 2009). Different luminescence mechanisms were suggested for the green spectral region.…”

Section: Introductionmentioning

confidence: 99%

“…The luminescence spectra have the emission bands of oxygen vacancies with two or one captured electrons, viz., 3.0 eV (F-centers) and 3.8 eV (F þ -centers), respectively, as well as the bands of Cr 3þ impurity defects (1.8 eV), among others (Evans et al, 1994;Kotomin and Popov, 1998). The F-centers are the main contributors to the overall TLD-500 luminescence signal, from which the absorbed dose is estimated.…”

Section: Introductionmentioning

confidence: 99%

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Dosimetric application of green luminescence in irradiated TLD-500 detectors

Вохминцев

Weinstein

Кортов

2013

Radiation Measurements

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h i g h l i g h t s< 3D plots of TL emission in a-Al 2 O 3 crystals before and after UV irradiation at 623 K < First-order kinetic processes prevail during thermoluminescence at the 2.4 eV band. < Observed dose dependences of the green TL light sum are linear in 10 À5 e1 Gy range. a r t i c l e i n f o b s t r a c tThe spectral and kinetic characteristics of thermoluminescence (TL) for anion-defective a-Al 2 O 3 single crystals in the 4.4e2.2 eV range at 300e600 K were studied. Three-dimensional (3D) plots of the luminescence under research for a sample before and after UV irradiation at 623 K for 30 min were analyzed. The increase in the emission response in the 2.4 and 3.7 eV bands for the sample after the photothermal treatment was observed. The dominant contribution of a thermally stimulated process with first-order kinetics in the regularities of the 2.4 eV luminescence was shown. The linearity of the dose dependences for the 2.4 eV TL response in different samples at 10 À5 e1 Gy was demonstrated. The advantage of using the green thermoluminescence in the TLD-500 for solid state dosimetry was discussed.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Dosimetric application of green luminescence in irradiated TLD-500 detectors

Вохминцев

Weinstein

Кортов

2013

Radiation Measurements

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“…The optical absorption bands of the H-ion and D-ion irradiated sapphire crystals near 210 and 260 nm can be attributed to F-type centers. 18 F-type center is well known as a defect in the research of sapphire crystals. Energetic particle irradiation induces oxygen vacancies and charges trapped at the defects.…”

Section: Methodsmentioning

confidence: 99%

Optical transmittance investigation of 1-keV ion-irradiated sapphire crystals as potential VUV to NIR window materials of fusion reactors

et al. 2016

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We investigate the optical transmittances of ion-irradiated sapphire crystals as potential vacuum ultraviolet (VUV) to near-infrared (NIR) window materials of fusion reactors. Under potential conditions in fusion reactors, sapphire crystals are irradiated with hydrogen (H), deuterium (D), and helium (He) ions with 1-keV energy and ∼ 1020-m-2 s-1 flux. Ion irradiation decreases the transmittances from 140 to 260 nm but hardly affects the transmittances from 300 to 1500 nm. H-ion and D-ion irradiation causes optical absorptions near 210 and 260 nm associated with an F-center and an F+-center, respectively. These F-type centers are classified as Schottky defects that can be removed through annealing above 1000 K. In contrast, He-ion irradiation does not cause optical absorptions above 200 nm because He-ions cannot be incorporated in the crystal lattice due to the large ionic radius of He-ions. Moreover, the significant decrease in transmittance of the ion-irradiated sapphire crystals from 140 to 180 nm is related to the light scattering on the crystal surface. Similar to diamond polishing, ion irradiation modifies the crystal surface thereby affecting the optical properties especially at shorter wavelengths. Although the transmittances in the VUV wavelengths decrease after ion irradiation, the transmittances can be improved through annealing above 1000 K. With an optical transmittance in the VUV region that can recover through simple annealing and with a high transparency from the ultraviolet (UV) to the NIR region, sapphire crystals can therefore be used as good optical windows inside modern fusion power reactors in terms of light particle loadings of hydrogen isotopes and helium.

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“…6,[20][21][22][23][24][25] suggest that although luminescence from -Al 2 O 3 :C has multiple sources [3,28], the contribution from the F-centre is dominant. This is particularly evident when the emission is measured as a thermoluminescence isometric plot above ambient temperature [29,30].…”

Section: Introductionmentioning

confidence: 99%