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1.
Luminescence and scintillation properties of Y3Al5O12:Ce single crystals grown from the melt by the Czochralski and horizontal directed crystallization methods in various gas media and Y3Al5O12:Ce single-crystal films grown by liquid-phase epitaxy from a melt solution based on a PbO-B2O3 flux have been comparatively analyzed. The strong dependence of scintillation properties of Y3Al5O12:Ce single crystals on their growth conditions and concentrations of YAl antisite defects and vacancy defects has been established. Vacancy defects are involved in Ce3+ ion emission excitation as the centers of intrinsic UV luminescence and trapping centers. It has been shown that Y3Al5O12:Ce single-crystal films are characterized by faster scintillation decay kinetics than single crystals and a lower content of slow components in Ce3+ ion luminescence decay during high-energy excitation due to the absence of YAl antisite defects in them and low concentration of vacancy defects. At the same time, the light yield of Y3Al5O12:Ce single-crystal films is comparable to that of single crystals grown by directed crystallization due to the quenching effect of the Pb2+ ion impurity as a flux component and is slightly lower (∼25%) than the light yield of single crystals grown by the Czochralski method.  相似文献   

2.
Peculiarities of growth of single crystalline films (SCF) of Pr3+ doped Y3Al5O12 and Lu3Al5O12 garnets and YAlO3 and LuAlO3 perovskites by the liquid phase epitaxy method from melt-solutions based on PbO–B2O3 flux as well as luminescent and scintillation properties of these SCFs were studied in this work. Dependence the intensity of the Pr3+ d-f and f-f-luminescence on the activator concentration and influence of Pb2+ flux dopant on the light yield of SCFs of the mentioned garnets and perovskites were analyzed.  相似文献   

3.
Luminescent properties of phosphors based on single-crystalline films (SCF) of Y3Al5O12:Ce (YAG:Ce) and Lu3Al5O12:Ce (LuAG:Ce) garnet have been analyzed in comparison with single-crystal (SC) analogues. It has been shown that the main peculiarity of luminescent properties of YAG:Ce and LuAG:Ce SCF as compared to SC is determined by the extremely low concentration of YAl3+ and LuAl3+ antisite defects (AD) in SCF. The advantages of phosphors based on YAG:Ce and LuAG:Ce SCF are caused by the absence in these SCF the additional channels for dissipation of excitation energy connected with AD and vacancy-type defects.  相似文献   

4.
The nature of the intrinsic luminescence of the lutetium aluminum garnet Lu3Al5O12 (LuAG) has been analyzed on the basis of time-resolved spectral kinetic investigations upon excitation of two model objects, LuAG single crystals and single-crystal films, by pulsed X-ray and synchrotron radiations. Due to the differences in the mechanisms and methods of crystallization, these objects are characterized by significantly different concentrations of LuAl antisite defects. The energy structure of luminescence centers in LuAG single crystals (self-trapped excitons (STEs), excitons localized near antisite defects, and LuAl antisite defects) has been established. For single-crystal LuAG films, grown by liquid-phase epitaxy from a Pb-containing flux, the energy parameters of the following luminescence centers have been determined: STEs in regular (unperturbed by the presence of antisite defects) sites of the garnet lattice and excitons localized near Pb2+ ions. The structure of the luminescence centers, related to the background emission of impurity Pb2+ ions, has also been established in the UV and visible ranges. It is suggested that, in contrast to the two-halide hole self-trapping, a self-trapped state similar to STEs in simple oxides (Al2O3, Y2O3) is formed in LuAG; this state is formed by self-trapped holes in the form of singly charged O? ions and electrons localized at excited levels of Lu3+ cations.  相似文献   

5.
The Pr3+ d–f luminescence was investigated in the single crystalline films (SCF) of Lu3Al5−xGaxO12:Pr garnet solid solution at x = 1–3, grown by the liquid phase epitaxy (LPE) method from the melt-solution based on the PbO–B2O3 flux. The shape of CL spectra and decay kinetics of Pr3+ ions in Lu3Al5−xGaxO12 SCFs strongly depend on the total gallium concentration x and distribution of Ga3+ ions between the tetrahedral and octahedral position of the garnet host. The best scintillation properties of Lu3Al5−xGaxO12:Pr SCF are achieved at the nominal Ga content in melt-solution in the x = 2–2.5 range.  相似文献   

6.
Optical properties of Ho3+-doped Lu3Al5O12 and (Lu,Y)3Al5O12 crystals were investigated and compared. Substitution of Y for Lu in the host garnet Lu3Al5O12 results in broad absorption and emission spectra, and improvements in the laser behavior of Ho3+. Pumped by Tm:fiber laser, a maximum output power of 5.02 and 5.73 W of Ho-doped Lu3Al5O12 and (Lu,Y)3Al5O12 have been obtained, respectively. The center lasing wavelength are 2124.5 and 2123.0 nm for Lu3Al5O12 and (Lu,Y)3Al5O12, respectively.  相似文献   

7.
Comparative studies of the luminescence of Y3Al5O12:Ce and Lu3Al5O12:Ce single-crystal films and their volume analogues—Y3Al5O12 and Y3Al5O12:Ce single crystals, excited by synchrotron radiation with energy E=120–150 eV, have been performed. The films were grown from melt-solution by liquid-phase epitaxy and the crystals were grown from melt. The single-crystal films and single crystals studied are characterized by different degrees of structural order, in particular, different concentrations of substitutional defects of the Y Al 3+ and LU Al 3+ types. It was ascertained that the bands at 260 and 250 nm in the intrinsic luminescence spectra of Y3Al5O12:Ce and Lu3Al5O12:Ce single-crystal films and single crystals are due to the emission of self-trapped excitons. The luminescence band with λmax=300 nm and τ=0.36 μs, which is present in the luminescence spectrum of single crystals and absent in the spectra of single-crystal films, is due to the recombination of electrons with holes localized at Y Al 3+ centers. It is shown that an efficient energy transfer by excitons to activator ions occurs in Y3Al5O12 and Lu3Al5O2 single-crystal films doped with Ce3+ ions.  相似文献   

8.
Nanocrystalline Y3Al5O12: Ce3+/Tb3+ (average crystalline size 30 nm) phosphor layers were coated on non-aggregated, monodisperse and spherical SiO2 particles by the sol-gel method, resulting in the formation of core-shell structured SiO2@Y3Al5O12:Ce3+/Tb3+ particles. X-ray diffraction, Fourier transform infrared spectroscopy, transmission electron microscopy, photoluminescence, cathodoluminescence spectra, as well as lifetimes were utilized to characterize the core-shell structured SiO2@Y3Al5O12:Ce3+/Tb3+ phosphor particles. The obtained core-shell structured phosphors consist of well-dispersed submicron spherical particles with a narrow size distribution. The thickness of the Y3Al5O12:Ce3+/Tb3+ shells on the SiO2 cores (average size about 500 nm, crystalline size about 30 nm) could be easily tailored by varying the number of deposition cycles (100 nm for four deposition cycles). Under the excitation of ultraviolet and low-voltage electron beams (1–3 kV), the core-shell SiO2@Y3Al5O12:Ce3+/Tb3+ particles show strong yellow-green and green emission corresponding to the 5d–4f emission of Ce3+ and 5D47F J (J = 6, 5, 4, 3) emission of Tb3+, respectively. These phosphors may have potential application in field emission displays.  相似文献   

9.
Luminescence characteristics of Ce3+- and Pr3+-doped aluminium perovskite (LuAlO3, YAlO3) and garnet (Lu3Al5O12, Y3Al5O12) single crystalline films, prepared by the liquid phase epitaxy method with the use of the PbO-based flux, were investigated by the time-resolved spectroscopy methods in the 80–300 K temperature range. The influence of various lead-related centers on the characteristics of the Ce3+- and Pr3+-related luminescence centers was studied. It was found that the presence of lead-related centers in the single crystalline films results in a decrease of the quantum efficiency and appearance of undesirable slow components in the luminescence decay kinetics. The possibilities of improving the scintillation characteristics of the single crystalline films were considered.  相似文献   

10.
Submicron core-shell structure particles SiO2@Y3Al5O12:Er3+, which silica spherical particles was coated with an yttrium aluminum garnet (Y3Al5O12) layer doped with Er3+, were prepared by the modified Pechini-Type sol-gel method for the first time. The structure and morphology of samples were detected by the X-ray powder diffraction (XRD) measurement, field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM), respectively. The results indicate that well-crystallized garnet nanocrystallines were formed on the surface of the silica particles. The luminescent spectra in near infrared and visible region of the core-shell structured SiO2@Y3Al5O12:Er3+ powders were also investigated and compared with those of the pure Y3Al5O12:Er3+ and the Er3+ doped silicate glass. The results show that mono-dispersed SiO2@Y3Al5O12:Er3+ core-shell spherical particles with the near infrared, red and green luminescent emissions under the excitation of 980 nm laser diode have been successfully synthesized.  相似文献   

11.
Molybdenum ions are implanted into aluminium with high ion flux and high dose at elevated temperatures of 200℃, 400℃ and 500℃. Due to the high temperature and high flux of vacancies and interstitial atoms, the atom diffusion and chemical effects are enhanced during the ion implantation. The effects increase with increasing ion flux and dose, so that new phase formation and phase transition emerge noticeably. X-ray diffraction analysis shows that when the aluminium is implanted with Mo ions at a low ion flux (25μA/cm2), the Al5Mo alloy is formed. The atomic ratio of Mo/Al of the Al5Mo phase is close to 20%. When the aluminium is implanted with Mo ions at a high ion flux (50μA/cm2), the phase transition from Al5Mo to Al12Mo appears, and the latter is dominant, which is determined to be the final phase. The ratio of Mo/Al in Al12Mo is 7.7%. Rutherford backscattering spectroscopy indicates also that the Mo/Al atom ratio is ~7% to ~8% in Mo-implanted aluminium. The atomic ratios of the constituents in Al5Mo and Al12Mo are of stoichiometric composition for these alloys. The thicknesses of the Al12Mo alloy layers for Mo-implanted Al with ion doses of 3×1017/cm2 and 1×1018/cm2 are 550nm and 2000nm, respectively. The pitting corrosion potential Vp increases obviously. It is clear that due to the formation of Al12Mo alloy layer, the pitting corrosion resistance is enhanced.  相似文献   

12.
In this paper, a facile co-precipitation process for preparing mono-dispersed core–shell structure nanoparticles is reported. The 110 nm SiO2 cores coated with an yttrium aluminum garnet (Y3Al5O12) layer doped with Er3+ were synthesized and the influence of the concentration ratio of [urea]/[metal ions] on the final product was investigated. The structure and morphology of samples were characterized by the X-ray powder diffraction, Fourier transform IR spectroscopy and transmission electron microscopy, respectively. The results indicate that a layer of well-crystallized garnet Y3Al5O12:Er3+ were successfully coated on the silica particles with the thickness of 20 nm. The near infrared and upconversion luminescent spectra of the SiO2@Y3Al5O12:Er3+ powders further confirm that a Y3Al5O12:Er3+ coating layer has formed on the surface of silica spherical particles.  相似文献   

13.
The effect of the growth rate of directionally solidified Al2O3-Y3Al5O12 ceramics on the structural perfection of the two-phase material is studied by low-angle neutron scattering, as well as by constant-wavelength and time-of-flight neutron diffraction methods. When the growth rate is high, the orientation and size of Y3Al5O12 needles remain unchanged, while the Al2O3 matrix phase decomposes into crystallites. Neutron diffraction methods are viewed as an effective tool for flexible crystal growth control.  相似文献   

14.
Yttrium aluminum garnet (Y3Al5O12) and Mn activated Y3Al5O12 phosphors have been prepared by urea combustion route in less than 5 min. The phosphors are well characterized by powder X-ray diffraction, Scanning electron microscopy and Fourier-transform infrared spectroscopic techniques. Photoluminescence tests on the pure Y3Al5O12 showed a strong green emission at 525 nm (2.36 eV) attributed to the strongly allowed transition of F+ center whereas in Mn2+ activated YAG the green emission at 519 nm is due to the 4T1 (G)→6A1 (S) transition of Mn2+ ions. EPR studies have been carried out on Mn2+ activated Y3Al5O12 phosphor at 300 and 110 K. From EPR spectra the spin-Hamiltonian parameters have been evaluated. The magnitude of the hyperfine splitting (A) indicates that the Mn2+ ions are in a moderately ionic environment. The spin concentration (N) and paramagnetic susceptibility (χ) have been evaluated and discussed.  相似文献   

15.
The luminescence spectra of single-crystal films and bulk crystals of yttrium-aluminum garnet Y3Al5O12 and Ce3+-activated Y3Al5O12 were investigated. It was shown that the room-temperature luminescence intensity of the Ce3+-free single-crystal Y3Al5O12 film was considerably lower than that of the bulk crystals, while the luminescence intensity of the Ce3+ ions in the Y3Al5O12:Ce films was considerably higher than that one for the corresponding bulk crystal.  相似文献   

16.
In this study, several up-conversion luminescence agents (Er3+:Y3Al5O12, Er3+:Yb0.2Y2.79Al5O12, Er3+:Yb0.2Y2.79Al5N0.01O11.99, Er3+:Yb0.2Y2.79Al5F0.01O11.99 and Er3+:Yb0.2Y2.79Al5N0.01F0.01O11.98) were synthesized using sol–gel method. And then, the corresponding sonocatalyst (Er3+:Y3Al5O12/TiO2, Er3+:Yb0.2Y2.79Al5O12/TiO2, Er3+:Yb0.2Y2.79Al5N0.01O11.99/TiO2, Er3+:Yb0.2Y2.79Al5F0.01O11.99/TiO2 and Er3+:Yb0.2Y2.79Al5N0.01F0.01O11.98/TiO2 coated composites) were prepared by sol–gel coating process. The synthesized up-conversion luminescence agents and their coated composites were characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM). And that, the sonocatalytic activities were detected through the degradation of Azo Fuchsine (AF) dye in aqueous solution by UV–vis spectroscopy. Some key influences such as heat-treated temperature and heat-treated time on the sonocatalytic activity of Er3+:YbaY2.99−aNxFyAl5O12−xy/TiO2 coated composite, as well as ultrasonic irradiation time and initial dye concentration on the sonocatalytic degradation were studied. The results showed that the doping of Yb, N and F into Er3+:Y3Al5O12/TiO2 significantly enhanced the sonocatalytic activity of Er3+:Y3Al5O12/TiO2 coated composite in the degradation of organic dyes. Particularly, Er3+:Yb0.2Y2.79Al5N0.01F0.01O11.98/TiO2 coated composites with 3:7 M ratio heat-treated at 550 °C for 60 min showed the highest sonocatalytic activity. At last, the experiments also indicated that the Er3+:Yb0.2Y2.79Al5N0.01F0.01O11.98/TiO2 coated composites has a good sonocatalytic activity to degrade other organic dyes under ultrasonic irradiation.  相似文献   

17.
High-order Raman parametric generation was excited in the visible and near-IR regions on the Stokes and anti-Stokes lines of Y3Al5O12 single crystals and nanocrystalline ceramics. All generation components, as well as the χ(3)-active vibrational modes of these materials, were identified. In connection with the extensive use of the Nd3+-and Yb3+-doped Y3Al5O12 crystals and, in recent years, nanocrystalline Y3Al5O12: Nd3+ ceramics in laser physics and quantum electronics, the applied aspect of the observed nonlinear properties of these materials is outlined.  相似文献   

18.
Y3Al5O12∶Ce3+的余辉和热释光特性   总被引:1,自引:0,他引:1       下载免费PDF全文
高温固相法合成了Ce3+掺杂的Y3Al5O12 (YAG)样品,研究了样品的结构、光致发光和热释发光性质. X射线衍射分析结果表明合成样品为YAG纯相,稀土离子的少量掺杂不改变基质YAG的结构. 荧光光谱测试表明在高温空气气氛下Y2.95Al5O12 ∶Ce4+0.05制备过程中存在Ce4+关键词: 长余辉 高温热释光 缺陷  相似文献   

19.
In this progress report, seven kinds of novel carefully designed and fabricated up-conversion luminescence agents, Er3+:Y3Al5O12, Er3+:YbnY3?nAl5O12, Er3+:Y3BaAl5?aO12, Er3+:Y3GabAl5?bO12, Er3+:Y3Al5NxO12?x, Er3+:Y3Al5FyO12?y and Er3+:YbnY3?nBaGabAl5?a?bNxFyO12?x?y, are successfully synthesized using sol–gel methods. After that, their corresponding photocatalysts, Er3+:Y3Al5O12/TiO2, Er3+:YbnY3?nAl5O12/TiO2, Er3+:Y3BaAl5?aO12/TiO2, Er3+:Y3GabAl5?bO12/TiO2, Er3+:Y3Al5NxO12?x/TiO2, Er3+:Y3Al5FyO12?y/TiO2 and Er3+:YbnY3?nBaGabAl5?a?bNxFyO12?x?y/TiO2, are also prepared by sol–gel coating process. The obtained up-conversion luminescence agents and photocatalysts were characterized by using XRD, XPS, SEM, UV–vis and fluorescence spectrophotometer. Synchronously, several kinds of organic dyes are used to test their photocatalytic degradation using prepared photocatalysts. It indicates that the up-conversion luminescence ability of Er3+:Y3Al5O12 can be improved obviously through doping of some elements. And then, the photocatalytic activity of TiO2 is markedly enhanced by modified up-conversion luminescence agents which can transform much visible light into ultraviolet light.  相似文献   

20.
The specific features of the crystal structure of crystal phosphors Y3Al5O12: Ce3+/Lu2O3 (Lu2O3: Ce) synthesized by the colloidal chemical method have been investigated by neutron diffraction at room temperature. The influence of the method used for introducing Lu2O3 into the system on the structure and luminescence properties of the samples has been analyzed. The investigation has revealed that the spectra of the samples prepared under the most nonequilibrium conditions are characterized by the Stokes shift and high photoluminescence intensity. This has been explained by the disorder of their crystal structure due to the formation of stable associates of defects.  相似文献   

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