Extraction-pyrolytic Method Research Articles

Применение оксидных покрытий, полученных экстракционно-пиролитическим методом, в космической технике

The problem of creating antimicrobial protection methods in rocket and space technology requires new approaches, in particular, the development of antibacterial coatings to protect the payload of launch vehicles. Also, in outer space outside the Earth's atmosphere, ultraviolet radiation with a wavelength of less than 280 nm (hard and vacuum ultraviolet) accelerates degradation of materials. It is relevant to create protective coatings for various materials used in space. An innovative extraction-pyrolytic method for producing oxide films containing copper, titanium and titanium oxide nanoparticles is considered. As a result, the compositions of effective antibacterial coatings with the function of protection against UV radiation have been established. The intended service and design features of the part on which the coating is applied are considered, and a flow diagram for applying an antibacterial coating to protect the internal volume of the fairing from bacteria circulating in the head of the launch vehicle is proposed. The possibilities of protection against UV radiation by applying oxide films to the outer surface of devices and rocket parts have been studied.

Synthesis and Magnetic Resonance of Lanthanum Manganites Doped with Potassium Ions

Manganites doped with potassium ions La1 – xKxMnO3, where х = 0.0, 0.1, and 0.15, have been obtained by extraction-pyrolytic method at low temperature. The compounds have been studied by X-ray powder diffraction, electronic paramagnetic and ferromagnetic resonances. Unit cell parameters of La1 – xKxMnO3 samples have been calculated. According to magnetic resonance spectroscopy, La1 – xKxMnO3 exhibits phase delamination into paramagnetic and ferromagnetic phases. The fraction of the latter phase increases when temperature decreases. The temperature of transition from paramagnetic into ferromagnetic phase (Curie temperature, TC) for La1 – xKxMnO3 is –17.4, –13.7, and –4.8°С at х = 0.0, 0.1, and 0.15, respectively. The reason of symbate change in TC and potassium ion concentration in La1 – xKxMnO3 is supposed to be the change in the content of ferromagnetic pairs Mn3+–О2––Mn4+ in the manganites.

Inorganic Luminophores Synthesized by the Extraction Pyrolytic Method on the Basis of Rare-Earth and Rare Elements

Inorganic Luminophores Synthesized by the Extraction Pyrolytic Method on the Basis of Rare-Earth and Rare Elements

Extraction-Pyrolytic Synthesis and Luminescent Properties of Borates La0.95Eu0.05BO3 : Sm and La0.95Eu0.05(BO2)3 : Sm

Orthoborates La0.95–хEu0.05SmхBO3 and metaborates La0.95 – хEu0.05Smх(BO2)3 (х = 0.025, 0.05, 0.075, 0.1) have been obtained under optimal conditions by extraction-pyrolytic method at lower temperature and shorter time as compared with the known methods. Increase in Sm3+ ion concentration leads to decrease of unit cell volume in La0.95 – хEu0.05SmхBO3 (aragonite structural type) and La0.95 – хEu0.05Smх(BO2)3 (monoclinic modification of α type). The larges changes in luminescence excitation spectra of the compounds depending on Sm3+ concentration is observed in 360–450 nm region, which includes the bands of transitions for both Eu3+ and Sm3+ ions. On luminescence excitation in the band of maximal absorption of Sm3+ ion (λeх = 404 nm), luminescence intensity of cooperatively doped La0.925Eu0.05Sm0.025(BO2)3 and La0.925Eu0.05Sm0.025BO3 increases, which can be explained by the possibility of efficient transfer of absorbed energy from Sm3+ to Eu3+ ion.

ЗАВИСИМОСТЬ СОСТАВА И ЛЮМИНЕСЦЕНТНЫХ ХАРАКТЕРИСТИК ЛЮМИНОФОРОВ ОТ ТЕМПЕРАТУРЫ ПИРОЛИЗА ПРЕКУРСОРОВ

General conditions for the synthesis of phosphors based on mixed oxides of REE and rare elements by the low-temperature extraction-pyrolytic method were discussed. Dependence of morphology, composition and relative integrated luminescence intensity of phosphors on the pyrolysis temperature of precursors was investigated.

ОКСИДНЫЕ ПЛЕНКИ С РАЗЛИЧНЫМИ ХАРАКТЕРИСТИКАМИ ПРОПУСКАНИЯ И ПОГЛОЩЕНИЯ В УФ-ОБЛАСТИ, ПОЛУЧЕННЫЕ ЭКСТРАКЦИОННО-ПИРОЛИТИЧЕСКИМ МЕТОДОМ

UV and visible transparency of ZrO2, CuO, TiO2, Y2O3, ZnO and NiO oxide films of various thickness obtained by the extraction-pyrolytic method on fused silica supports at pyrolysis temperature 500°C and crystallization temperature 700°C. The characterization of their optical performances demonstrated a possibility for obtaining coatings providing either reduction of increase of the transmission in different UV regions.

Antibacterial Copper–Titanium Oxide Coatings Obtained with the Extraction–Pyrolytic Method

Antibacterial Copper–Titanium Oxide Coatings Obtained with the Extraction–Pyrolytic Method

The Use of the Extraction–Pyrolytic Method for the Production of Oxide Functional Films and Coatings

The Use of the Extraction–Pyrolytic Method for the Production of Oxide Functional Films and Coatings

Luminescent Properties of La0.95Eu0.05BO3:М and La0.95Eu0.05(BO2)3:М Borates (М = Tb, Bi) Synthesized by the Extraction-Pyrolytic Method

Luminescent Properties of La0.95Eu0.05BO3:М and La0.95Eu0.05(BO2)3:М Borates (М = Tb, Bi) Synthesized by the Extraction-Pyrolytic Method

Synthesis of Nanocrystalline TiO<sub>2</sub> by the Extraction-Pyrolytic Method and its Phase Transformation in the Presence of Gadolinium

Due to its to its optical, thermal, photocatalytic and electrophysical properties, nanocrystalline titanium oxide (TiO2) is widely used in various fields. In the present work, a series of pure and Gd-modified (0.5, 5, 50 mol%) TiO2 nanocrystalline powders were prepared by a novel synthesis approach – extraction-pyrolytic method (EPM). Metal containing extracts on the basis of valeric acid were used as precursors. Thermal behavior of produced individual and mixed precursors were investigated by thermogravimetric analysis (TGA) and high temperature differential scanning colometry (HDSC). Phase composition of pure and Gd-modified TiO2 powders were studied as a function of pyrolysis temperature (450o -850°C ) and gadolinium content by X-ray diffraction (XRD) method. Photocatalytic activity of produced powders was studied by photocatalytic degradation of methylene blue (MB) under UV/VIS light irradiation.

Influence of MeV Gamma Photons on Thermally Stimulated Exoelectron Emission from MgO Films

The effect of 6 MeV gamma photons on thermally stimulated exoelectron emission (TSEE) spectra of MgO films was studied. The films were fabricated on Si/SiO2 substrates using the extraction-pyrolytic method. The crystalline structure and surface morphology of the films were characterized by X-ray diffraction (XRD) and atomic force microscopy (AFM). TSEE spectra of MgO films had emission peaks at about 450 oC and 525 oC. The area under the TSEE peaks increased after repeated TSEE measurements. In the case of gamma-irradiated films, the percentage increase in the area depended on the radiation dose, decreasing linearly with an increase in the radiation dose from 0 to 80 Gy. The results suggest that gamma radiation reduced the density of trapped electrons present in the as-grown MgO films or created competing hole traps that inhibited TSEE from the films.

Using the Extraction–Pyrolysis Method in Synthesis of Bioactive Glass

Using the Extraction–Pyrolysis Method in Synthesis of Bioactive Glass

Applying the Extraction–Pyrolysis Method to Modify Functional Materials Based on Metal Oxides

Applying the Extraction–Pyrolysis Method to Modify Functional Materials Based on Metal Oxides

Study of phase composition, photocatalytic activity, and photoluminescence of TiO2 with Eu additive produced by the extraction-pyrolytic method

Due to the unique properties and wide array of applications of nanocrystalline materials based on titanium dioxide, the study of new synthesis approaches remains relevant. In this study, within the framework of the extraction-pyrolytic method (EPM), we suggest using the mixtures of Ti- and Eu-containing organic extracts based on valeric acid as precursors for fabrication of nanocrystalline TiO2-based powders with different Eu content: 0.5 mol%, 5 mol%, and 50 mol%. The thermal behavior of individual metal-containing extracts and their mixture was studied by thermogravimetric analysis and differential scanning calorimetry (TGA–DSC). To characterize phase composition and morphology of produced materials, the X-ray diffraction (XRD) method and scanning electron microscopy (SEM) were used. Photoluminescence properties of Eu3+ ions in TiO2 nanocrystals have been studied. Photocatalytic activity of produced materials was tested in the reaction of methylene blue (MB) oxidation under UV-VIS irradiation. Correlation between synthesis parameters (Eu content and pyrolysis temperature) and properties of produced materials (phase composition, photoluminescence and photocatalytic properties) has been studied. It was demonstrated that the presence of a Eu-containing extract in the precursor mixture increases the anatase-to-rutile phase transformation temperature. The highest efficiency (degradation degree of MB 96%) was shown by TiO2 powder consisting of mixed polymorphs, anatase (main phase) and rutile, with 0.5 mol% Eu additive. It was shown that anatase-to-rutile phase transformation in TiO2:Eu3+ nanoparticles manifests in a degradation of Eu3+ luminescence intensity.

Extraction–Pyrolytic Method for TiO2 Polymorphs Production

The unique properties and numerous applications of nanocrystalline titanium dioxide (TiO2) are stimulating research on improving the existing and developing new titanium dioxide synthesis methods. In this work, we demonstrate for the first time the possibilities of the extraction–pyrolytic method (EPM) for the production of nanocrystalline TiO2 powders. A titanium-containing precursor (extract) was prepared by liquid–liquid extraction using valeric acid C4H9COOH without diluent as an extractant. Simultaneous thermogravimetric analysis and differential scanning calorimetry (TGA–DSC), as well as the Fourier-transform infrared (FTIR) spectroscopy were used to determine the temperature conditions to fabricate TiO2 powders free of organic impurities. The produced materials were also characterized by X-ray diffraction (XRD) analysis and transmission electron microscopy (TEM). The results showed the possibility of the fabrication of storage-stable liquid titanium (IV)-containing precursor, which provided nanocrystalline TiO2 powders. It was established that the EPM permits the production of both monophase (anatase polymorph or rutile polymorph) and biphase (mixed anatase–rutile polymorphs), impurity-free nanocrystalline TiO2 powders. For comparison, TiO2 powders were also produced by the precipitation method. The results presented in this study could serve as a solid basis for further developing the EPM for the cheap and simple production of nanocrystalline TiO2-based materials in the form of doped nanocrystalline powders, thin films, and composite materials.

Luminescent Properties of Lanthanum Borates LaBO3:Eu and La(BO2)3:Eu Obtained by the Extraction-Pyrolytic Method

Luminescent Properties of Lanthanum Borates LaBO3:Eu and La(BO2)3:Eu Obtained by the Extraction-Pyrolytic Method

FERROELECTRICS IN ACOUSTOELECTRONICS

Аcoustoelectronics is one of the areas of acoustics, associated with the use of mechanical resonance effects and the piezoelectric effect, as well as the effect based on the interaction of electric fields with waves of acoustic stresses in a piezoelectric material. The main materials used in acoustoelectronics are ferroelectrics, which are mainly complex oxide materials. This article discusses the possibility of increasing the purity and homogeneity of ferroelectric materials, as well as softening the regimes of their synthesis using the solution extraction-pyrolytic method. It is shown that the synthesis temperatures of BaTiO3, SrTiO3, and Pb(Zr)TiO3 ferroelectric films are reduced to 550-600°C, and the synthesis time is down to 5-10 minutes. The dielectric constant and Curie temperature values correspond to the maximum characteristics for these materials. Thus, using the extraction-pyrolytic method we obtained suitable for use in acoustoelectronic technology ferroelectric films.

Extraction-pyrolytic method for obtaining functional materials based on metal oxides: possibilities and prospects

Extraction-pyrolytic method for obtaining functional materials based on metal oxides: possibilities and prospects

Impact of Gadolinium on the Structure and Magnetic Properties of Nanocrystalline Powders of Iron Oxides Produced by the Extraction-Pyrolytic Method.

Interest in magnetic nanoparticles is primarily due to their practical use. In this work, for the production of nanocrystalline powders of pure and gadolinium doped iron oxides, the extraction-pyrolytic method (EPM) was used. As a precursor, either iron-containing extract (iron (III) caproate in caproic acid) or its mixture with gadolinium-containing extract (gadolinium (III) valerate in valeric acid) was used. The mixed precursor contained 0.5 mol %, 2.5 mol %, 12.5 mol %, 50 mol %, and 75 mol % gadolinium in relation to the iron content. The formation of iron oxide phases, depending on the preparation conditions, was investigated. According to the results obtained, it was demonstrated that the presence of more than 2.5 mol % gadolinium additive in the mixed precursor inhibits the magnetite-to-hematite transformation process during thermal treatment. Produced samples were characterized by XRD and SEM methods, and the magnetic properties were studied.

Porous Silicon Capacitor Structures with Embedded Barium Strontium Titanates

The possibility of creating capacitor structures based on porous silicon with oxide ferroelectrics embedded in the pores—barium strontium titanates, which have a diffuse phase transition—is considered. In this case, thin films of barium strontium titanate are characterized as nanostructures with ferroelectric properties. To obtain such structures, the extraction-pyrolytic method is used. The dependences of the capacitance and permittivity of the structures on the ratio of barium and strontium components in barium strontium titanates are studied. The results of this work confirm the possibility of using the presented technologies—the production of porous silicon matrices and the extraction-pyrolytic method for producing a ferroelectric based on barium and strontium titanates—to create a capacitive-type structures with different dielectric characteristics due to the possibility of varying the obtained ferroelectric composition, dimension, and morphology of the porous silicon matrix.