Glass and Ceramics最新文献

LuAG-based optical ceramics co-doped with Yb³⁺ and Er³⁺ ions was successfully synthesized for the first time. The optical, spectral-luminescent, and kinetic characteristics of ceramics based on Y_2.82Yb_0.15Er_0.03Al₅O₁₂ (YAG 5-Yb, 1-Er) and Lu_2.82Yb_0.15Er_0.03Al₅O₁₂ (LuAG 5-Yb, 1-Er) compositions were investigated. It is demonstrated that excitation of luminescence at a wavelength of 940 nm in YAG 5-Yb, 1-Er and LuAG 5-Yb, 1-Er ceramics results in the effective transfer of excitation radiation energy from Yb³⁺ ions to Er³⁺ ions. The energy transitions that play a pivotal role in the processes of Stokes and anti-Stokes luminescence of ceramics based on YAG 5-Yb, 1-Er and LuAG 5-Yb compositions was identified, and a schematic representation of these transitions is presented. The mutual variation of the intensity of anti-Stokes luminescence bands resulting from the transitions ²H_11/2 → ⁴I_15/2 (525 nm) and ⁴S_3/2 →⁴I_15/2 (546 nm) was observed, with regard to the power of the excitation radiation. This study demonstrates the potential of YAG 5-Yb, 1-Er and LuAG 5-Yb, 1-Er ceramics as materials for optical thermometry.

By means of vibrational spectroscopy, the study examines the structure of matrix materials synthesized through the quenching of sodium-rubidium aluminoborosilicate melts with the addition of zirconium. Zirconium was found to have a significant effect on the ratio of the main structural units and the distribution of modifier cations among them in the glass structure. The obtained results were used to explain changes in the glass-melt transition temperature and synthesized material density; they can be useful in adjusting the composition and synthesis parameters of matrix materials for the immobilization of high-level radioactive waste containing significant amounts of zirconium.

The possibility of increasing the current density of a charged particle beam (focusing) by means of tapered glass channels without the use of external energy sources is actively translated into action today for positively charged ions. For electron beams, this possibility is not realized due to the lack of experimental data on the sliding interaction between electron beams and a dielectric surface. It is necessary to examine the compression of an electron beam by tapered capillaries depending on their geometrical parameters, as well as to study the temporal characteristics of the focusing process. In this work, the authors experimentally studied the compression of a 10 keV electron beam using a 15-mm-long tapered glass channel with an inlet-to-outlet inside diameter ratio of 1.15 mm/0.30 mm. The beam current density is shown to increase at the outlet of the capillary with the specified parameters by up to a factor of 2.7 for the position where the channel axis is parallel to that of the initial beam. This density increase is estimated for electrons that have lost no more than 1 keV of initial energy. It is also shown that the process of electron transmission by a tapered capillary is stable regardless of the orientation of the capillary with respect to the direction of the initial beam.

The article shows the possibility of synthesizing a ZnO-based sulfur chemisorbent deposited on a granular (upgamma -{text{AI}}_{2}{text{O}}_{3}) substrate by impregnating it with an aqueous zinc salt solution followed by thermal decomposition. The strength and textural properties of the obtained sorbent were studied via low-temperature nitrogen adsorption, x-ray diffraction, and scanning electron microscopy. The synthesized adsorbent exhibits higher strength and more efficient use of the surface than conventional ZnO-based sorbents used in natural gas processing. The proposed sorbent showed relatively high static sulfur capacity for ({text{H}}_{2}text{S}) adsorption as compared to industrial zinc-based counterparts.

The compliance of buildings with fire safety requirements is an urgent issue for design engineers and builders. Based on the analysis of statistical data, the inadequacy of measures to ensure the safety of individuals in case of fire and the role of translucent fire-rated glazing (FRG) in solving this problem are substantiated. Mandatory fire safety requirements for FRG of buildings are considered. Regulatory documentation is analyzed in the context of recent updates of regulations on fire safety requirements. A brief review of fire-rated glazing and fire-rated glass is presented. Recommendations are given on the use of fire-rated glazing to increase the safety of individuals in the event of fire.

The paper outlines the principles of the directional drilling method with the use of hydraulic fracturing, demonstrating the impact of drilling cuttings and coal combustion waste on the environment. It presents the results of physical and chemical analysis of drilling cuttings from the Vostochno-Chumakovskoye oil field and boiler slag from the OGK-2-Novocherkassk SDPP Branch. In addition, the potential use of boiler slag in the synthesis of aluminosilicate proppants is investigated.

The modified sol-gel method (Pechini method) is shown to synthesize multielement oxides on the basis of bismuth niobate that crystallize in the pyrochlore structure (space group Fd-3m). The temperature for the synthesis of a single-phase sample amounts to 950°C, which is 100°C lower than the calcination temperature used in the conventional ceramic method of synthesis. The average crystallite size determined radiographically varies from 39 nm (850°C) to 48 nm (1050°C) depending on the sintering temperature. According to x-ray diffraction analysis, the unit cell parameter is equal to 10.4872(6) Å. The conducted elemental mapping indicates a uniform distribution of metal atoms on the sample surface, while energy dispersive x-ray analysis shows that the chemical composition of the synthesized sample corresponds to the specified theoretical composition.

Bismuth germanate glasses were modified with sodium oxide, and the resulting glasses were studied in order to determine the influence of the modifier on their spectral-luminescent properties. The ratios of Bi₂O₃ and Na₂O concentrations at which the infrared luminescence of these glasses is possible were identified.

The article examines temperature conditions for the thermal synthesis of silica from rice husk and different conditions for subsequent milling. In the study, the following methods were used: elemental analysis, x-ray diffraction analysis, petrographic analysis, electron and atomic force microscopy, differential scanning calorimetry, and laser granulometry. The occurrence of silica was detected at about 650°C; its structure remained stable during pyrolysis and subsequent thermal treatment in the presence of air. Following thermal treatment at 1000 – 1100°C, cristobalite remained the predominant phase. The milling of thermal treatment products involved a significant loss of process efficiency due to the cellular structure of aggregates and their plastic failure.

Bismuth-containing chromates, Bi_xCrO_1.5x+3 , were synthesized using a ceramic method from bismuth (III) and chromium (III) oxides, with a variable molar ratio of 1 ≤ n (Bi)/n (Cr) ≤ 38. The calcined samples exhibit a color variation from green to dark red, depending on the n (Bi)/n (Cr) ratio. The ceramic materials undergo a color change from green to red when a mixture of oxides with a significant predominance of bismuth oxide n (Bi₂O₃)/n (Cr₂O₃) ≥ 3 is subjected to a high-temperature treatment in air (at 650°C). It is noteworthy that the calcination of chromium (III) oxide under similar conditions occurs without the oxidation of chromium ions. X-ray diffraction analysis confirmed the formation of chromates, including Bi₆Cr₂O₁₅, Bi₁₀Cr₂O₂₁, Bi₃₁Cr₅O_61.5, and Bi₁₄CrO₂₄ . X-ray spectroscopy studies of the samples revealed that the NEXAFS Cr2p spectra of the red bismuth-chromium ceramics exhibited similarities in the main details of the K₂CrO₄ spectrum, indicating the presence of chromium in the oxide ceramics in the form of tetrahedral ({text{CrO}}_{4}^{2-}) ions. In addition, scanning electron microscopy data demonstrated that the samples exhibited a dense, low-porosity microstructure.