Origin of improved scintillation efficiency in (Lu,Gd)3(Ga,Al)5O12:Ce multicomponent garnets: An X-ray absorption near edge spectroscopy study

Wu, Yuntao; Luo, Jialiang; Nikl, M.; Ren, Guohao

doi:10.1063/1.4854375

Cited by 37 publications

(18 citation statements)

References 37 publications

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“…Very recently, similar studies were done for the Gd 3 Al 2 Ga 3 O 12 :Ce (GAGG:Ce) multicomponent garnet [ 133,136,137 ] Phases of a typical Czochralski process including A) approach of the seed to the overheated melt surface, B) immersion of the seed in the melt and their thermal equilibration, C) pulling of the seed in the upward direction with a continuous increase of crystal diameter and shoulder formation, D) steady state, as the constant diameter crystal is pulled, E) ending the growth with continuous diameter decrease, and F) separation of the crystal from the melt and its subsequent cooling to room temperature. Reproduced with permission.…”

Section: Reviewmentioning

confidence: 86%

“…[ 118 ] The decreased bottom edge of the conduction band in these compounds is mainly due to a gallium admixture. Such a pathway is realized by the stabilization of a tetravalent Ce 4+ center in the garnet lattice by divalent rare earth ion co-doping [ 113,[131][132][133][134] and/or by air annealing. This problem has been studied in detail and the ionization of the Ce 3+ excited state was determined to be its main cause.…”

Section: Reviewmentioning

confidence: 99%

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

Nikl

Yoshikawa

2015

Advanced Optical Materials

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630

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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Section: Reviewmentioning

confidence: 86%

Section: Reviewmentioning

confidence: 99%

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

Nikl

Yoshikawa

2015

Advanced Optical Materials

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630

374

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“…The uncertainty in the energy value in this measurement was ± 0.1 eV. All spectra were normalized in the same way using Athena software, [ 46 ] by which the Ce 3+ /Ce 4+ ratio was evaluated with an accuracy of ± 10%. Radioluminescence (RL) spectra were measured using an X-ray tube (Seifert GmbH, Germany, 40 kV) with excitation by a custom-made 5000M model Horiba Jobin Yvon fl uorometer (Horiba Jobin Yvon Co., France) and equipped with a TXB-04 photon counting detector.…”

Section: Methodsmentioning

confidence: 99%

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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“…In 1967, Blasse and Bril firstly reported YAG: Ce as a new phosphor for flying-spot cathode ray tubes10. Due to high light yield (20000 photons/ MeV) and fast response time, in the 1990s YAG: Ce and the higher density analogue Lu 3 Al 5 O 12 : Ce (LuAG) and (Lu,Gd) 3 (Al,Ga) 5 O 12 were proposed as scintillators for X-ray and gamma-ray radiation detection, used in X-ray computed tomographic scanner (CTS) and positron emission tomography (PET) for medical imaging and in scanning electron microscopy (SEM)1011121314.…”

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confidence: 99%

Charge deformation and orbital hybridization: intrinsic mechanisms on tunable chromaticity of Y3Al5O12:Ce3+ luminescence by doping Gd3+ for warm white LEDs

Chen

Liu

et al. 2015

Sci Rep

107

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The deficiency of Y3Al5O12:Ce (YAG:Ce) luminescence in red component can be compensated by doping Gd3+, thus lead to it being widely used for packaging warm white light-emitting diode devices. This article presents a systematic study on the photoluminescence properties, crystal structures and electronic band structures of (Y1−xGdx)3Al5O12: Ce3+ using powerful experimental techniques of thermally stimulated luminescence, X-ray diffraction, X-ray absorption near edge structure (XANES), extended X-ray absorption fine structure (EXAFS) and ultraviolet photoelectron spectra (UPS) of the valence band, assisted with theoretical calculations on the band structure, density of states (DOS), and charge deformation density (CDD). A new interpretation from the viewpoint of compression deformation of electron cloud in a rigid structure by combining orbital hybridization with solid-state energy band theory together is put forward to illustrate the intrinsic mechanisms that cause the emission spectral shift, thermal quenching, and luminescence intensity decrease of YAG: Ce upon substitution of Y3+ by Gd3+, which are out of the explanation of the classic configuration coordinate model. The results indicate that in a rigid structure, the charge deformation provides an efficient way to tune chromaticity, but the band gaps and crystal defects must be controlled by comprehensively accounting for luminescence thermal stability and efficiency.

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Origin of improved scintillation efficiency in (Lu,Gd)3(Ga,Al)5O12:Ce multicomponent garnets: An X-ray absorption near edge spectroscopy study

Cited by 37 publications

References 37 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

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

Charge deformation and orbital hybridization: intrinsic mechanisms on tunable chromaticity of Y3Al5O12:Ce3+ luminescence by doping Gd3+ for warm white LEDs

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Origin of improved scintillation efficiency in (Lu,Gd)3(Ga,Al)5O12:Ce multicomponent garnets: An X-ray absorption near edge spectroscopy study

Cited by 37 publications

References 37 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

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

Charge deformation and orbital hybridization: intrinsic mechanisms on tunable chromaticity of Y3Al5O12:Ce3+ luminescence by doping Gd3+ for warm white LEDs

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