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121.
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Zinc gallate compounds codoped with manganese and europium ions were synthesized using the high-temperature solid-state reaction method. All samples were “characterized” by X-ray diffraction measurements, ultraviolet reflection spectroscopy, and photoluminescence spectroscopy. Structural investigations confirmed that incorporation of europium ions in zinc gallate host leads to distortion of the spinel unit cell and increase in lattice parameter. Manganese ions show the intense excitation in the region of band-to-band transitions. Zinc gallate spinel compounds codoped with manganese and europium ions exhibit emission in the whole spectral region. Among the manganese and europium activator emissions in the “green” and “red” spectral regions, the “blue” emission of spinel matrix was observed. Photoluminescence excitation spectra of europium ions and reflection spectra show similar results in the near-ultraviolet region of the spectra. The optimal concentration of europium activator was determined. Europium doping level leads to redistribution of excitation and emission intensities of zinc gallate codoped samples. The possible energy transfer mechanisms between matrix, manganese, and europium ions are discussed. Overlapping of excitation bands of all types of luminescence gives a possibility to obtain emission in the whole visible spectral range. The Commission Internationale de l’Eclairage chromaticity diagrams confirmed a possible application of the studied zinc gallate spinel compounds codoped with manganese and europium ions for the development of ultraviolet and near-ultraviolet phosphors with flexible emission color in the visible spectral range. 相似文献
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V. V. Zborovskii V. I. Kravets V. I. Min'kovich I. Z. Stepanenko N. N. Stoyan 《Journal of Mathematical Sciences》1993,66(4):2402-2408
The finite-element method is applied to analyze local loss of stability of a complex stiffening rib. The elastic and geometrical stiffness matrices are obtained. The critical stresses where instability sets in are determined by solving an eigenvalue problem.Translated from Vychislitel'naya i Prikladnaya Matematika, No. 66, pp. 60–70, 1988. 相似文献
126.
G. A. Kravets T. Kh. Shokhireva V. F. Anufrienko T. M. Yurieva 《Reaction Kinetics and Catalysis Letters》1982,19(1-2):85-89
ESR studies indicate that in Ti–Mo heteropoly acid supported on TiO2, two types of Mo5+ ions are observed, corresponding to stabilization of the heteropoly blue with various degrees of interaction with the surface. , - TiO2 Mo5+, . 相似文献
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Sensors highly sensitive to CO gas that are based on Ag-doped SnO2 nanoparticles are shown to be a feasibility. The structure and composition of the respective films versus the SnO2 nanoparticle size are studied. The electrical parameters of the sensor materials are measured. It is shown that exposure of the nanostructured films to carbon monoxide considerably decreases their resistance and shifts the frequency of a maximum in the impedance curves toward lower values. Specific features of the IR reflection spectra in the range of excitation of carbon and oxygen atom vibrations are revealed. 相似文献
129.
Photoluminescence and Raman spectra of SnO<Subscript>x</Subscript> nanostructures doped with Sm ions
V. G. Kravets 《Optics and Spectroscopy》2007,103(5):766-771
The photoluminescence (PL) and Raman scattering of SnOx nanoparticles deposited from vapor phase have been studied. The PL spectra are characterized by a two-band structure. The high-energy band in the range from 300 to 350 nm is due to the exciton pair annihilation and may characterize the band gap of SnOx nanocrystals as a function of their diameter. In the red spectral region (from 600 to 700 nm), a luminescence band due to defects in nanocrystals manifests itself. The existence of defects in SnOx nanostructures is confirmed by Raman spectroscopy. Doping of SnOx nanoparticles with rare earth (samarium) atoms leads to the appearance of strong luminescence lines in the red region of the PL spectrum. 相似文献
130.
Luhovyi P. Z. Kravets V. H. Prokopenko N. Ya. Shukyurov A. M. 《International Applied Mechanics》2021,57(1):34-42
International Applied Mechanics - The possibilities of controlling the edge effect of the explosion of the conic primer in the lower part of the borehole charge on the level of the bench sole are... 相似文献