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31.
Ho3+ doped TTB–BaTa2O6 phosphors were produced by the solid state reaction method. XRD analysis confirmed the formation of BaTa2O6 single phase which was accomplished by heat treatment at 1425 °C for 20 h. The crystal structure of TTB–BaTa2O6 allowed doping concentration of Ho3+ ions up to 10 mol%, maintaining a single phase composition. A second phase of HoTaO4 begins to appear at 15 mol%. The lattice structure and the crystallite sizes changed with the concentration of Ho3+. In SEM analysis, it was also shown that BaTa2O6 grain sizes changed with the concentration of Ho3+. EDS analysis revealed that the Ta/Ba ratio increased on the grains depending on Ho3+ concentration. Charge balance of the structure was formulated through the EDS results. In fluorometer analysis, a strong green emission (λem = 546.9 nm) was observed in the visible spectral region. The emission increased with the doping concentration of up to 2.5 mol%, and above this level decreased due to concentration quenching. 相似文献
32.
The photoluminescence (PL) properties of ZrO2 have been measured at different temperatures between 7 and 300 K, using various kinds of ZrO2 specimens: bulk crystal melt-grown by a large solar furnace, thermally oxidized zirconium plate (ZrO2 film crystal on Zr ) and nanocrystals (surface area: 35–45m2/g, diameter: 20–30 nm). The results clarify the deep and shallow energy level structures in the energy gap. Reversible UV-laser-light-induced spectral changes are observed for all of the specimens in different specimen-atmospheres (vacuum and O2 gas). The results elucidate the defect-effects of the PL properties and the PL enhancement mechanism in ZrO2 nanocrystals. 相似文献
33.
V. I. Shulga 《辐射效应与固体损伤》2013,168(1-4):65-83
Sputtering of Cu single-crystal and polycrystal targets by 27 keV Ar ions has been simulated using the new binary collision cascade computer program OKSANA. The sputtering yield, the sputtering and reflection efficiencies, and the absolute and relative contributions to sputtering from various components have been calculated in a broad range of incidence angles. The obtained angular dependences of the sputtering yield have proved to agree with experimental data. Some features of sputtering due to semichannel focusing of incident particles have been found. The contributions to sputtering from several types of linear collision chains and from the primary knock-on atoms are considered in most detail. It has been shown, in particular, that the pure focused, pure defocused, and mixed focused-defocused collision chains contribute noticeably to sputtering. The contribution from the primary knock-on atoms is angle-dependent and reaches its maximum in the range of glancing angles for both single-crystal and polycrystal targets. 相似文献
34.
S. A. Gevelyuk I. K. Doycho L. P. Prokopovich E. Rysiakiewics-Pasek E. D. Safronsky 《辐射效应与固体损伤》2013,168(1-6):427-432
We have studied the influence of multiple carbon treatments on the properties of silica porous glasses. Each step of each carbon treatment started with filling the voids of porous glass with carbon. During the following anneal carbon interacted with the walls of the voids. It was shown that low dimensional silicon clusters were formed inside the voids as a result of this reaction. In the experiments the photoluminescence spectra and conductivity of carbon-processed specimens were measured. The size-distribution of voids in porous glasses was calculated from absorption—desorption isotherms. An original technique was proposed that allowed to obtain the size-distribution of silicon clusters from the positions of peaks in the photoluminescence spectra. Correlation between the photoluminescence intensity and the sizes of pores was revealed. The observed oscillations in the shapes of the photoluminescence spectra in subsequent cycles of carbon treatment are explained by changes of the number of clusters corresponding to definite peaks in the size distribution spectra. 相似文献
35.
R. M. Montereali 《辐射效应与固体损伤》2013,168(6-12):545-551
Research activities concerned with color centers in alkali halide films started recently. The use of versatile, well-assessed, and low-cost fabrication techniques consisting of physical vapor deposition of Lithium Fluoride (LiF) films combined with direct writing lithographic processes allows the realization of miniaturized structures, like broad-band emitters, channel waveguides, optical microcavities and point-light sources emitting in the visible spectral range. Promising results have been obtained in the generation, amplification and waveguiding of visible light in LiF treated by low energy electron beams, where the efficient formation of stable primary and aggregate color centers also induces a local modification of the refractive index. A brief overview of the investigated optical properties is presented together with a short discussion about their perspectives of applications in optoelectronics. 相似文献
36.
The exposure of the Cd2Nb2O7:Cr crystal to monochromatic light with wavelength shorter than 600 nm at 12 K decreases the Cr3? photoluminescence emission and allows us to observe thermoluminescence within 60–200 K during subsequent heating of the crystal at a rate of 0.077 K/s. The glow curve of thermoluminescence revealed a rather complex structure with two pronounced intensive glow peaks at 91 and 180 K and four rather weak peaks at 99, 117, 132, and 155K. An analysis of the glow peaks by “an initial rise” gave evidence of many various charge carrier traps with activation energies from 150 to 470 meV. Since a comparison of the thermoluminescence and photoluminescence emission spectra showed that these spectra are identical, it was concluded that the thermoluminescence glow peaks are associated with thermal release of charge carriers from shallow traps followed by Cr4?→Cr3?(2E) and/or Cr2?→Cr3?(2E) charge capture and 2E→4A2 radiative decay of Cr3?(2E) ions. 相似文献
37.
One dimensional nanostructures of cerium doped dysprosium phosphate (DyPO4:Ce3+) were synthesized via hydrothermal route in the presence of different surfactants [sodium dodecyl sulfate (SDS), dodecyl sulfosuccinate (DSS), polyvinyl pyrollidone (PVP)] and solvent [ethylene glycol and water]. The prepared nanostructures were characterized by Powder X-ray diffraction (PXRD), Fourier transform infrared spectroscopy (FTIR), Field emission scanning electron microscopy (FE-SEM), Transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS), UV-VIS-NIR absorption spectrophotometer and photoluminescence (PL) studies. The PXRD and FTIR results indicate purity, good crystallinity and effective doping of Ce3+ in nanostructures. SEM and TEM micrographs display nanorods, nanowires and nanobundles like morphology of DyPO4:Ce3+. Energy-dispersive X-ray spectra (EDS) of DyPO4:Ce3+nanostructures confirm the presence of dopant. UV-VIS-NIR absorption spectra of prepared compounds are used to calculate band gap and explore their optical properties. Luminescent properties of DyPO4:Ce3+ was studied by using PL emission spectra. The effect of additives and solvents on the uniformity, morphology and optical properties of the nanostructures were studied in detail. 相似文献
38.
Fengfeng Chi Yanguang Qin Shaoshuai Zhou Xiantao Wei Yonghu Chen Changkui Duan Min Yin 《Current Applied Physics》2017,17(1):24-30
In order to clarify the site occupancy of rare-earth ions in rare-earth doped perovskite materials, the un-doped pure CaTiO3 and Eu3+-doped CaTiO3 samples with a series of Ca/Ti ratio were synthesized via high-temperature solid-state reaction method. X-ray diffraction (XRD) powder patterns confirm that the crystal structure keeps invariant at various Ca/Ti ratios. Measurement results of unit-cell parameters and X-ray photoelectron spectroscopy (XPS) indicate that Eu3+ ions enter into the Ca2+ site. The high-resolution photoluminescence spectra of Eu3+ ions at 20 K in all samples did not witness a significant change under the excitation at different wavelength, implying that Eu3+ ions occupy only one type of site. Considering the small spectral splitting range of 5D0 → 7F2 transition and the large intensity ratio of 5D0 → 7F2/5D0 → 7F1, it can be concluded that Eu3+ occupies Ca2+ site with larger coordinate numbers rather than Ti4+ site. 相似文献
39.
Photoluminescence and atomic force microscopy studies on pre- and post-irradiated ruby with Fe3+ ion
Photoluminescence spectra measured for pristine ruby and its two irradiated samples with Fe3+ ion show R1, R2, N lines and a broad band. Decrease in intensities of these features is observed with irradiation of Fe3+ ion in ruby. Progressive structural changes and modifications on surface of irradiated rubies with Fe3+ ion have been observed by atomic force microscopy. Decrease in intensities is discussed in terms of pair formation. 相似文献
40.
The objective of this work is to study electron-vibrational interaction (EVI) and concentration quenching and their manifestation in experimental photoluminescence spectra of Cu+ ion in various lithium based phosphors namely, Li2SO4, LiNaSO4 and LiKSO4. The main parameters of EVI, such as the Stokes shift, Huang-Rhys factor and zero-phonon line positions, were estimated. The studied systems shows strong electron lattice coupling. The validity of results was established by modeling the shape of the emission spectra, which was found to be in good agreement with experimental photoluminescence spectra. The concentration quenching study is also carried out for these compounds. The studied systems correspond to the nearest neighbor energy transfer mechanism. 相似文献