Optical and electron paramagnetic resonance studies of Fe impurities in yttrium aluminum garnet crystals

Chen, C. Y.; Pogatshnik, G. J.; Chen, Y.; Kokta, Milan R.

doi:10.1103/physrevb.38.8555

Cited by 49 publications

(29 citation statements)

References 6 publications

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“…The absorption pattern below 300 nm is composite due to the overlap of the higher 4f → 5d Ce 3+ absorption bands and various intrinsic and trace-impurity (Fe 3+ , Yb 2+ ) related absorptions. [ 28,29 ] The presence of the Ce 4+ charge transfer (CT) absorption peaking at about 240 nm, which increases with increasing Mg concentration, also adds to the absorption band below 300 nm, similarly to what has been observed for LuAG:Ce,Mg and Gd 3 Al 2 Ga 3 O 12 :Ce,Mg (GGAG:Ce,Mg) single crystals. [ 30,31 ] Before annealing, this additional CT absorption band is only observable for the highest Mg concentration (0.6%).…”

Section: Introductionmentioning

confidence: 56%

Towards Bright and Fast Lu₃Al₅O₁₂:Ce,Mg Optical Ceramics Scintillators

Liu

Mareš

Feng

et al. 2016

Advanced Optical Materials

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needed. Within the last two decades, a number of excellent scintillators based on Ce 3+ and Pr 3+ -doped materials, together with truly novel nanoscintillators, nanocomposites, and phase-separated material systems, have been discovered and studied in depth. [1][2][3][4][5][6][7][8] This high R&D activity in the scintillator fi eld was triggered by the pressing needs of modern medical imaging and radiotherapy, of high-energy physics, homeland security, and environmental applications. Among them, Cedoped Lu 3 Al 5 O 12 (LuAG:Ce) aluminum garnets have attracted much attention because of their relatively high density of 6.73 g cm −3 , 5d -4f electric dipole allowed radiative transition of Ce 3+ with emission at around 500-550 nm, fast scintillation response of about 60 ns, and high theoretical light yield (LY) value of 60000 photons/MeV. [ 9,10 ] It was found that LuAG:Ce single crystal containing 0.55 at% Ce 3+ ions prepared by Bridgman technique is a highly competitive scintillator displaying a LY of about 26000 photons/MeV with a shaping time of 1.5 μs, close to that of Lu 2 SiO 5 :Ce (LSO:Ce). [ 11 ] Based on the understanding of defect chemistry, an effective bandgap engineering approach was successfully applied to the LuAG system. Multicomponent garnets, featuring a balanced admixture of Gd and Ga cations in the Lubased garnet structure, form a new family of materials with an amazingly high light yield up to 58000 photons/MeV, a value exceeding that of the best Lu 2-x Y x SiO 5 :Ce (LYSO:Ce) materials by about 40%. [12][13][14][15] Therefore, oxides based on garnet structure are presently considered as competitive candidates for advanced scintillation applications.However, the low segregation coeffi cient of Ce 3+ ions in the LuAG lattice is detrimental for the growth of homogeneously doped large LuAG:Ce single crystals, especially for high Ce 3+ concentrations (Ce 3+ > 0.2 at%). [ 16 ] It was also noticed that Lu Al antisite defects (AD) can severely deteriorate the scintillation characteristics of LuAG:Ce single crystals by acting as shallow traps, thus delaying the energy transport to the Ce 3+ emission centers. [ 17 ] Therefore, extensive research has recently been aimed at the preparation of ceramic analogues, which are characterized by lower preparation temperatures, more uniform doping, and lower cost. One point to consider is that during The choice of sintering agent appears critical to achieve both high optical transparency and scintillation performance. In this work, the optical investigations coupled with X-ray absorption near-edge spectroscopy evidence the benefi cial role of MgO sintering agent. Mg 2+ co-dopants in ceramics drive the partial conversion of Ce 3+ to Ce 4+ . The Ce 4+ center, however, does not impair the scintillation performance due to its capability to positively infl uence the scintillation process. The importance of simultaneous application of such co-doping and annealing treatment is also demonstrated. With 0.3 at% Mg, our ceramics display a light yield of ≈25000 photons/MeV wit...

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Section: Introductionmentioning

confidence: 56%

Towards Bright and Fast Lu₃Al₅O₁₂:Ce,Mg Optical Ceramics Scintillators

Liu

Mareš

Feng

et al. 2016

Advanced Optical Materials

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“…At higher concentrations (above 0.1%) Fe 3+ is evidenced by characteristic absorption doublet at 407 + 415 nm and luminescence band around 800 nm [101]. Fe 3+ presence in YAG lattice is manifested also through the charge transfer transition resulting in a wide absorption band at 255 nm [102]. Also an Yb 3+ ion can introduce additional nonradiative losses in LuAG:Ce scintillator as its charge transfer luminescence is heavily quenched at RT [103].…”

Section: Aluminum Garnetsmentioning

confidence: 96%

Complex oxide scintillators: Material defects and scintillation performance

Nikl¹,

Laguta

Vedda

2008

Physica Status Solidi (b)

198

106

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An overview of recognized structural defects, impurities and related trapping levels and their role in the scintillation mechanism is provided and discussed in single crystal materials belonging to tungstate, Ce‐ or Pr‐doped aluminum perovskite, garnet and finally to Ce‐doped silicate scintillators. New achievements and open problems in deeper understanding of electron and hole self‐trapping phenomena and of the nature of defects in the crystal structure and their ability to localize migrating charge carriers are indicated. Fast optical ceramics and nanocomposite materials are pointed out as possible future advanced scintillators. Such novel technologies can in principle explore materials which are not available in the bulk single crystal form, but their figure‐of‐merit is dramatically dependent on the surface‐interface defect states and related trapping and nonradiative recombination phenomena. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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“…18 3) Our previous optical absorption measurements 20 on some of the YAG samples used in this investigation showed the 255 nm absorption band in the crystals, which is known to be due to charge transfer transitions of Fe 3+ . 21 Glow Discharge Mass Spectrometry (GDMS) analysis was conducted on one of the YAG samples to confirm the presence of iron and quantitatively determine the impurity contents. The analysis confirmed the presence of iron impurities at level of 0.48 x 10 -4 at.…”

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confidence: 99%

Strong visible and near infrared luminescence in undoped YAG single crystals

et al. 2011

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Strong luminescence peaks were observed at 700 and 800 nm in undoped yttrium aluminum garnet (YAG) single crystals. They were attributed to low level of iron impurities as confirmed by Glow Discharge Mass Spectrometry analysis. The 800 nm was only excited by high energy band at 270 nm; the reason behind that was discussed. Photoluminescence measurements revealed a large number of luminescence peaks in all YAG crystals regardless of the growth conditions due to native defects and low-level impurities. These luminescence centers have significant effects on the optical properties of rare-earth doped YAG crystals and their performance in laser and scintillation applications. Excitons released in the lattice may be easily captured by iron ions instead of Ce3+ ions and the scintillation output is substantially decreased. Nevertheless, Undoped YAG crystals may have the potential to be developed into efficient scintillators

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Optical and electron paramagnetic resonance studies of Fe impurities in yttrium aluminum garnet crystals

Cited by 49 publications

References 6 publications

Towards Bright and Fast Lu₃Al₅O₁₂:Ce,Mg Optical Ceramics Scintillators

Towards Bright and Fast Lu₃Al₅O₁₂:Ce,Mg Optical Ceramics Scintillators

Complex oxide scintillators: Material defects and scintillation performance

Strong visible and near infrared luminescence in undoped YAG single crystals

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Optical and electron paramagnetic resonance studies of Fe impurities in yttrium aluminum garnet crystals

Cited by 49 publications

References 6 publications

Towards Bright and Fast Lu3Al5O12:Ce,Mg Optical Ceramics Scintillators

Towards Bright and Fast Lu3Al5O12:Ce,Mg Optical Ceramics Scintillators

Complex oxide scintillators: Material defects and scintillation performance

Strong visible and near infrared luminescence in undoped YAG single crystals

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Towards Bright and Fast Lu₃Al₅O₁₂:Ce,Mg Optical Ceramics Scintillators

Towards Bright and Fast Lu₃Al₅O₁₂:Ce,Mg Optical Ceramics Scintillators