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1.
The timing characteristics of scintillation response of Czochralski-grown Gd3Al2Ga3O12:Ce and Gd3Al2.6Ga2.4O12:Ce single crystals were compared. The photoelectron yield, scintillation decay times, and coincidence time resolution were measured. At 662 keV γ-rays, the photoelectron yield of 6200 phe MeV−1 obtained for Gd3Al2Ga3O12:Ce is higher than that of 4970 phe MeV−1 obtained for Gd3Al2.6Ga2.4O12:Ce, while an inferior energy resolution of the former (7.2% vs. 5.6%) is observed. Scintillation decays are approximated by sum of exponentials with the dominant fast component decay time and its relative intensity of 89 ns (73%) for Gd3Al2Ga3O12:Ce and 136 ns (69%) for Gd3Al2.6Ga2.4O12:Ce. The coincidence time resolution obtained for Gd3Al2Ga3O12:Ce is superior than that of Gd3Al2.6Ga2.4O12:Ce. The normalized time resolution was also discussed in terms of a number of photoelectrons and decay characteristics of the light pulse. 相似文献
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N. V. Vasil’eva V. V. Randoshkin V. G. Plotnichenko Yu. N. Pyrkov V. V. Koltashev A. M. Galstyan N. N. Sysoev 《Journal of Surface Investigation: X-ray, Synchrotron and Neutron Techniques》2008,2(1):48-51
Single-crystal films of complex composition (Bi,Gd)3(Ga,Pt)2Ga3O12 on Gd3Ga5O12(111) substrates are synthesized by liquid-phase epitaxy from a supercooled solution-melt based on Bi2O3-B2O3 flux. Optical absorption of Bi3+ and Pt3+ ions in these films is investigated in the wavelength range from 200 to 860 nm. 相似文献
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V. V. Randoshkin N. V. Vasil’eva V. G. Plotnichenko Yu. N. Pyrkov S. V. Lavrishchev M. A. Ivanov A. A. Kiryukhin A. M. Saletskii N. N. Sysoev 《Physics of the Solid State》2004,46(6):1030-1036
Epitaxial films of composition (Gd,Nd)3Ga5O12 or (Gd,Y,Nd)3Ga5O12 with a neodymium content varying from 0.3 to 15 at. % are grown by liquid-phase epitaxy from a supercooled PbO-B2O3-based solution melt on Gd3Ga5O12(111) substrates. The optical absorption spectra of the epitaxial films grown are measured in the wavelength range 0.2–1.0 µm. The results of interpreting the absorption bands observed in the spectra are used to construct the energy level diagrams of Nd3+ and Gd3+ ions in the matrices of the epitaxial films. 相似文献
5.
A. Marshall K. P. O'Donnell M. Yamaga B. Henderson B. Cockayne 《Applied Physics A: Materials Science & Processing》1990,50(6):565-572
This paper describes measurements of the R-line emission from Cr3+ ions in Y3Ga5O12, Gd3Sc2Ga3O12, and Gd3Sc2Al3O12. Discrete splittings of the lines are interpreted as due to disorder on the cation sublattices. Assuming statistical distributions of the cations on the different cation sublattices enables estimates to be made of the degree of non-stoichiometry in the crystals. 相似文献
6.
Using a tunable stimulated Raman source, we have observed second-harmonic generation in the blue in a sputtered LiNbO3 film deposited on Gd3Ga5O12. With the choice of Gd3Ga5O12 as a substrate, it becomes possible to both phase-match a large range of fundamental wavelengths as well as have an excellent epitaxial quality surface. The SHG efficiency for the TMω0 → TM2ω2 phase matched conversion process is estimated to be ~ 10-4. 相似文献
7.
V. V. Randoshkin N. N. Usmanov Yu. A. Koksharov V. I. Kozlov A. M. Saletzky N. N. Sysoev N. V. Vasilieva 《Technical Physics》2006,51(6):799-802
Ferromagnetic resonance in epitaxial (Bi,Lu)3(Fe,Ga)5O12 films grown on Gd3Ga5O12(210) substrates is investigated. The spectrum contains a number of peaks, the most intense of which is related to the bulk of the film and the transition layer at the film-substrate interface. Most of the film volume is characterized by reduced magnetic anisotropy. The azimuthal and polar dependences of the resonance field exhibit 180° symmetry. 相似文献
8.
The emission and excitation spectra of Cr3+ -doped Gd3Ga5O12 (GGG) and Gd3Sc2Ga3O12 (GSGG) are explained in the light of multisite effects. The situation is particularly complicated in the case of GSGG, where the different sites have2E energy levels near each other which overlap with the4A2 →4T2 absorption bands. The spectra obtained under selective excitations are interpreted on the multisite assumption. 相似文献
9.
采用提拉法制备了Gd3Ga5-xAlxO12(以下简称GGAG)单晶,经X射线粉末照相证实为石榴石型单相结构。在T=1.5—77K温区里,场强从45—60000Oe范围内,沿[111]晶轴方向测量了磁化强度和磁化率,并与本文所用钇镓石榴石Gd3Ga5O12(以下简称GGG)和文献[1,2]报道的GGG单晶数据作了比较。实验结果表明:(1)在场强H<500Oe时,磁化率X与温度T的关系遵守居里-外斯定律,其有序温度TN远低于1.5K;(2)H>10000Oe时,该材料的磁化强度(或磁化率)比GGG高3—4%;(3)在H~30000Oe时,特定温度Tmin对应的临界场Hc比GGG约高4000Oe。实验研究表明,采用离子代换法寻找新的性能良好的磁致冷剂的途径是可行的。
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The emission and excitation spectra of Cr3+ -doped Gd3Ga5O12 (GGG) and Gd3Sc2Ga3O12 (GSGG) are explained in the light of multisite effects. The situation is particularly complicated in the case of GSGG, where the different sites have2E energy levels near each other which overlap with the4A2 4T2 absorption bands. The spectra obtained under selective excitations are interpreted on the multisite assumption. 相似文献
12.
We have studied the photoinduced effects in the nanocrystallized Y3Fe5O12 films deposited on the Gd3Ga5O12 <1 1 1> substrates. We have found for the first time substantial changes of the birefringence, two-photon absorption and circularly polarized absorption in different regimes of treatment of the nanocrystallized films. The explanations of the observed phenomena are suggested. The absorption spectra were modeled by the DFT based calculations of the electronic structure and density of states, which have revealed the well-pronounced differences between the densities of states of the tetra- and octahedrally coordinated iron ions. In addition, the crystal field calculations of the Fe3+ energy levels at the octahedral and tetrahedral positions have been performed. 相似文献
13.
《Journal of Physics and Chemistry of Solids》2003,64(4):599-605
The infrared (IR) reflectance spectra of Gd3Al5O12, Tb3Al5O12 and Lu3Al5O12 single crystals are studied for the first time. At room temperature, 15 infrared active modes for Lu3Al5O12 and 14 for Gd3Al5O12, Tb3Al5O12, out of the 17 theoretically predicted, have been experimentally recorded. The complex dielectric function the refractive index, the absorption coefficient as well as the longitudinal (ωLO) and transverse (ωTO) frequencies of the long-wavelength T1u modes are determined by the Kramers-Kronig transformation of the reflectance spectra. The experimental data are compared and discussed with the theoretical results obtained by the rigid ion model. Our theoretical analysis reveals that the bonds in the tetrahedra exhibit a covalent character while those in the dodecahedra almost ionic character, which is in accordance with the results for other materials of this crystal family. 相似文献
14.
G. Marest N. Kornilios A. Perez F. Ravel P. Gerard B. Gilles M. Brunel 《Hyperfine Interactions》1987,35(1-4):943-946
Y3Fe5O12, Y3Al5O12 and Gd3Ga5O12 single crystal granets were implanted with 1017iron.cm−2. Complementary techniques: CEMS, TEM and XRD at glancing angles have allowed to follow the behavior of implanted iron during
thermal annealings. For Y3Fe5O12 large α-Fe2O3 particles are formed after annealings and at 1200°C occurs a low temperature regime of the Morin transition at room temperature.
For Y3Al5O12, due to aluminium substitution in the precipitates, the Morin transition is only detected after an annealing at 1300°C whereas
in Gd3Ga5O12 no Morin transition is observed. 相似文献
15.
This work is devoted to an analysis of thermal decay processes of the stable colour centres (CC) created in gadolinium gallium garnet (GGG) Gd3Ga5O12, crystals under irradiation by gamma-quanta (E=1.25 MeV, D=106 Gy). An analysis of the model of CC accumulation under irradiation as well as an isochronous heating model is presented. The decay activation energy (Δ E) for O? and F centres in GGG crystals is calculated in accordance with this model. 相似文献
16.
Improvement of the scintillation properties of Gd3Ga3Al2O12:Ce,B single crystals having tailored defect structure
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M. Tyagi A. K. Singh S. G. Singh D. G. Desai G. D. Patra S. Sen S. C. Gadkari 《固体物理学:研究快报》2015,9(9):530-534
A novel approach is reported to minimize various defect centers in Ce doped Gd3Ga3Al2O12 single crystals to improve the scintillation properties. The crystals of Gd3Ga3Al2O12 codoped with 0.2 at% Ce and B (GGAG:Ce,B) have been grown in air and argon ambient using the Czochralski technique. The scintillation light output of crystals grown in Ar ambient was significantly increased after annealing the crystals in air. The measured light output of 60000 ph/MeV for annealed crystals is the highest value reported among this class of materials. As a consequence, the energy resolution at 662 keV gamma‐rays from a 137Cs source was improved from 8% for the crystals grown in air to 6% for crystals grown in Ar and subsequently annealed in air. Further, the thermal quenching energy of photoluminescence (PL) emission was increased to be 470 meV for the annealed crystals. The thermoluminescence (TL) measurements suggest that the crystals grown in Ar ambient and post‐growth annealed in air may have a lesser concentration of trap centers which subsequently lead to the improvement in optical and scintillation properties leading to a superior detector performance. (© 2015 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim) 相似文献
17.
We study deep trapping states in Ce3+-doped garnet crystals with the composition (Lu,Y,Gd)3(Ga,Al)5O12, recently shown as having remarkably high light yield. We use thermally stimulated luminescence (TSL) technique above room temperature and determine the composition Gd3Ga3Al2O12 as the host showing the lowest concentration of traps. This host consistently manifests very low afterglow comparable to that of the standard BGO crystal. We also perform TSL glow peak analysis based on the initial rise technique to evaluate trap depth and other characteristics associated with TSL peaks. 相似文献
18.
V. V. Randoshkin V. I. Kozlov Yu. A. Koksharov A. M. Saletskiĭ N. N. Sysoev N. N. Usmanov 《Technical Physics》2007,52(4):495-497
It is shown that the ferromagnetic resonance spectrum in (Bi,Tm)3(Fe,Ga)5O12 films grown in Gd3Ga5O12(210) substrates has a single peak. The azimuthal and polar dependences of the resonance field possess 180° symmetry. The angular dependences of the ferromagnetic resonance line width and intensity are studied. 相似文献
19.
N. V. Vasil’eva K. S. Gochelashvili O. N. Evdokimova G. F. Makarenko V. V. Randoshkin 《Bulletin of the Lebedev Physics Institute》2007,34(6):174-175
The phosphorescence of a Gd3Ga5O12 single crystal grown by the Czochralski method is discussed. The phosphorescence was excited by UV radiation of a deuterium lamp. 相似文献
20.
V. Venkatramu D. Falcomer A. Speghini M. Bettinelli C.K. Jayasankar 《Journal of luminescence》2008,128(5-6):811-813
The concentration-dependent luminescence properties of sol–gel-derived nanocrystalline Lu3(1?x)Er3xGa5O12 powders (where x=0.01, 0.05 and 0.1) have been studied. Laser-excited luminescence spectra, emission decays and upconversion luminescence of Er3+-doped Lu3Ga5O12 nanocrystalline samples have been measured. The decay curve of the (2H11/2,4S3/2) emission exhibits a non-exponential behavior presumably due to cross-relaxation process. Moreover, near-infrared to visible upconversion luminescence has been observed in the green region for 1.0 mol% Er3+ ions in Lu3Ga5O12 nanocrystals upon 815 nm excitation. The power dependence of the anti-Stokes luminescence suggests that upconversion is probably achieved through the sequential absorption of two photons. To the best of our knowledge, this is the first report on the preparation and optical properties of Er3+-doped Lu3Ga5O12 in the form of nanocrystalline powders. 相似文献