Crystal growth and luminescence properties of calcium- and vanadium-doped gadolinium gallium garnet (original) (raw)
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Optical Materials, 2014
Cr-doped (Gd X Y 1-X) 3 Al 5 O 12 (X = 0, 0.25, 0.50) crystals prepared by the micro-pulling down method were investigated to develop a infra-red scintillator for implantable patient dosimeter in radiation therapy. In order to evaluate their optical and scintillation performance, the following properties were measured: (i) transmittance between ultraviolet and near-infra red region, (ii) photoluminescence spectra under Xe-lamp excitation, (iii) X-ray excited radio-luminescence spectra. Cr:Y 3 Al 5 O 12 and Cr:(Gd 0.25 Y 0.75) 3 Al 5 O 12 crystals showed increased transmittance of 80 %, while Cr:(Gd 0.50 Y 0.50) 3 Al 5 O 12 had a lower transmittance of 40 % due to its polycrystalline structure. In addition, all the Cr:(Gd X Y 1-X) 3 Al 5 O 12 crystals showed sharp scintillation luminescence peaks ascribed to Cr 3+ d-d transitions. Therefore, these results suggested that Cr:Y 3 Al 5 O 12 and Cr:(Gd 0.25 Y 0.75) 3 Al 5 O 12 crystals can be candidate materials
Crystal growth and luminescence properties of Ti-doped LiAlO2 for neutron scintillator
Journal of Crystal Growth, 2011
1-mol%-Yb-doped Gd 3 Al 2 Ga 3 O 12 infra-red scintillator crystal has been studied as a novel implantable radiation monitor in radiation therapy. Powder X-ray diffraction measurement and chemical analysis with a field emission scanning microscope and wavelength dispersive spectrometer determined its garnet structure and average chemical composition of Yb 0.03±0.01 Gd 2.99±0.07 Al 2.21±0.08 Ga 2.64±0.09 O 12.10±0.09. Transmittance measurements reached high values of approximately 70% in the human body transparency region between 650 to 1200 nm. Photoluminescence peaks were detected around 970 and 1030 nm under the 940 nm excitation with a Xe lamp. Infra-red scintillation emissions were clearly observed around 970 and 1030 nm due to Yb 3+ 4f-4f transitions under X-ray excitation. Therefore, these results suggest that Yb-doped Gd 3 Al 2 Ga 3 O 12 might be used as an infra-red scintillator material.
Ceramic Processing Research Scintillation properties of the Gd 3 Al 2 Ga 3 O 12 : Ce crystal
We investigated luminescence and scintillation properties of the Gd 3 Al 2 Ga 3 O 12 : Ce (GAGG) crystal grown in TPS(Total Polishing Solution) Co.. The GAGG crystal has the highest light yield among oxide crystal at room temperature and fast decay time for the detection of radioactivity and in nuclear and particle physics experiments and medical imaging. The scintillation properties of the GAGG crystal were studied by comparing the GAGG crystals grown by two companies. We measured an X-ray induced emission spectra, an energy resolution, an absolute light yield and a decay time. A pulse shape discrimination capability for a and gray was also demonstrated.
Journal of Luminescence, 2016
Cerium-doped lutetium aluminum garnet (LuAG:Ce) and yttrium aluminum garnet (YAG:Ce) transparent ceramics of same dimension were fabricated and their optical and scintillation properties were studied. LuAG:Ce transparent ceramic showed higher light yield under UV and X-ray excitation with respect to YAG:Ce transparent ceramic. YAG:Ce transparent ceramic showed higher light yield under gamma excitation and better energy resolution, which could be due to the considerable amount of slower emission (38.5%) in LuAG:Ce as well as lower optical transparency with respect to YAG:Ce ceramic.
Recent progress in advanced optical materials based on gadolinium aluminate garnet (Gd 3 Al 5 O 12 )
Science and Technology of Advanced Materials, 2015
This review article summarizes the recent achievements in stabilization of the metastable lattice of gadolinium aluminate garnet (Gd 3 Al 5 O 12 , GAG) and the related developments of advanced optical materials, including down-conversion phosphors, up-conversion phosphors, transparent ceramics, and single crystals. Whenever possible, the materials are compared with their better known YAG and LuAG counterparts to demonstrate the merits of the GAG host. It is shown that novel emission features and significantly improved luminescence can be attained for a number of phosphor systems with the more covalent GAG lattice and the efficient energy transfer from Gd 3+ to the activator. Ce 3+ doped GAG-based single crystals and transparent ceramics are also shown to simultaneously possess the advantages of high theoretical density, fast scintillation decay, and high light yields, and hold great potential as scintillators for a wide range of applications. The unresolved issues are also pointed out.
Optical Materials, 2014
Scintillation properties associated with intrinsic lattice defects of undoped Y 3 A 5 O 12 (YAG) and Lu 3 A 5 O 12 (LuAG) transparent ceramics and single crystals are compared. The ceramics excited with X-ray demonstrated relatively low emission intensity when compared with that of the single crystals. Decay times of the ceramics and the single crystals were similar. These parameters were approximately 430 ns (YAG ceramic), 460 ns (YAG single crystal), 30 ns and 1090 ns (LuAG ceramic), and 25 ns and 970 ns (LuAG single crystal). According to the pulse height spectra recorded under 137 Cs gamma-ray irradiation, the scintillation light yield of the both ceramics were about 2950 ± 290 ph/MeV. However, the single crystals had greater kight yield of about about 14,300 ± 1430 ph/MeV for YAG and 8350 ± 830 ph/MeV for LuAG.
Journal of Physics: Conference Series
Rare earth activators are impurities added in the phosphor material to enhance probability of visible photon emission during the luminescence process. The main activators employed are rare earth trivalent ions such as Ce +3 , Tb +3 , Pr 3+ and Eu +3. In this work, four terbium-activated Gd 2 O 2 S (GOS) powder screens with different thicknesses (1049 mg/cm 2 , 425.41 mg/cm 2 , 313 mg/cm 2 and 187.36 mg/cm 2) and one europium-activated GOS powder screen (232.18 mg/cm 2) were studied to investigate possible applications for general radiology detectors. Results presented relevant differences in crystallinity between the GOS:Tb doped screens and GOS:Eu screens in respect to the dopant agent present. The AE (Absolute efficiency) was found to rise (i) with the increase of the X-ray tube voltage with the highest peaking at 110kVp and (ii) with the decrease of the thickness among the four GOS:Tb. Comparing similar thickness values, the europium-activated powder screen showed lower AE than the corresponding terbium-activated.
Synthesis and Characterization of Doped Ceramic Scintillators Based on (Gd,Y)/sub 2/O/sub 3
Journal of Approximation Theory, 2005
From the measured X-ray luminescence spectra, the Gd1.94-x YxEu0.06O3 ceramics with x=0.4 showed the highest emission luminescence. Also both excitation and emission spectra measured at room temperature were higher than that at 11 K. The decay characteristics measured by laser luminescence showed that the decay time was about 1.2 msec at 11 K and it did not change much by increasing ambient temperature. From the results of the X-ray luminescence spectra measurement, it was also found that Eu and Li co-doping certainly increased the light output in the powder form but substantially the light output decreased in the ceramic form, which was considered due to the creation of defects in the sintering process. Therefore a further tuning procedure of the sintering process worthwhile to investigate for making better (Gd,Y)2O3 ceramic scintillator