Extraction-pyrolytic Method Research Articles

Study of thermal conductivity of glass with ZrO2-based thin films

Extraction-pyrolysis method is used for deposition of thin films of ZrO2 and ZrMgO3, ZrNiO3, ZrBaO3 onto glass substrates. The effect of thin films on coefficient of thermal conductivity of glass depending on the temperature is studied.

Ta-containing coatings formed on titanium and stainless steel by plasma electrolytic oxidation and/or extraction pyrolysis

Coatings with up to 20at.% of tantalum and phases of Ta2O5, Ta2O5·TiO2, and TiO2 have been formed on titanium in an aqueous electrolyte containing NH4[TaF6] by means of the method of plasma electrolyte oxidation (PEO). The addition of ethylene glycol into the electrolyte enables one to change the morphology and phase composition of resulting coatings. By combining the PEO and extraction–pyrolysis (EP) methods, layered coatings composed, in the upper part, of alternating elevations with predominant content of tantalum oxides and lows containing titanium oxides and calcium phosphates. The sizes of elevations and lows are about 10μm. Layers consisting predominantly of tantalum oxides of a thickness of 3μm have been formed on stainless steel by means of the EP method. The composition and structure of the obtained coatings make it possible to recommend their use in tests as biocompatible or bioinert media for deposition on titanium or steel implants, stents, or catheters.

Preparation of nanosized powders of calcium hydrosilicates for the use in composite materials

Nanosized powders of calcium hydrosilicates with a high granulometric uniformity have been synthesized from water-soluble calcium- and silicon-containing raw materials in the presence of structure-forming agents using the sol-gel method. The possibility of their application as the main components in the manufacture of acrylic paints has been demonstrated. The process of the formation of CaSiO3/TiO2 composite nanoparticles using freshly precipitated calcium hydrosilicate gel using the extraction-pyrolysis method has been investigated. A method of preparing composite titanium pigments based on calcium silicates has been elaborated and the possibility of using them in paint compositions as a substitute for titanium dioxide has been found out. A method of producing a white water-dispersion acrylic paint based on synthetic calcium hydro-silicates in the form of pastes of high humidity from calcium chloride and liquid glass has been developed.

Europium oxide-based nanocomposites synthesized by extraction-pyrolytic method

Promise was shown for a method for producing complex oxide nanocomposites of europium, iron, and bismuth both as bulk powders, and as thin-film coatings on various supports by low-temperature pyrolysis of organic extracts based on extraction systems with various polyfunctional ligands. The magnetic properties of nanosized bismuth and europium ferrites of the compositions Bi0.775Eu0.225O1.5, EuFeO3, and Eu3Fe5O12 were studied. The effect of the particle size on the magnetic characteristics of multiferroic EuFeO3 was detected.

Catalytically active coatings of noble metals and oxides of rare-earth elements

It was shown that the extraction pyrolysis method and the combined method of plasma electrolysis and extraction pyrolysis are suitable technologies for the formation of functional complex oxide composites exhibiting catalytic activity in CO conversion.

Oxide protective films obtained by the extraction pyrolytic method

The extraction pyrolytic method was used to obtain oxide films. Organic solutions of extracts were applied by dipping followed by thermal treatment of samples. It was shown that a thin film of zirconium dioxide stabilized by yttrium virtually does not reduce the transmission coefficient and the standing-wave ratio of microwave circuits.

Luminescent oxide materials obtained by the extraction pyrolytic method

Luminescent Y1.74Eu0.16Bi0.1O3 films have been obtained by extraction pyrolytic method. The formation of a crystalline structure in the film upon isothermal annealing in air at 600–650°C was established by X-ray diffraction. Single-phase Y1.74Eu0.16Bi0.1O3 films begin to exhibit luminescent properties after pyrolysis at 500°C; the intensity of luminescence increases with increasing temperature. The films annealed at 800°C consists of defect-free homogeneous crystallites with sizes of about 0.7 μm and demonstrats high luminescence intensity.

Combination of plasma-electrolytic oxidation and extraction-pyrolytic method for formation of metal oxide layers

Elemental composition and morphology of oxide coatings formed on stainless steel, nickel alloy (nonvalve metals), and titanium (valve metal) by plasma-electrolytic method combined with the extraction-pyrolytic technique are reported. It is shown that combination of these methods is promising for obtaining oxide coatings with a complex chemical composition and various physicochemical properties.

Pt/SiO2 and Pt/TiO2/Ti compositions and their catalytic properties

To support Pt on finely dispersed SiO2 or TiO2/Ti structures obtained via the plasma-electrochemical technique, the extraction-pyrolytic method was used. By means of scanning electron microscopy and X-ray spectral analysis, it was shown that the oxide compositions contain up to 3.5 wt % of Pt. The resulting compositions, Pt/SiO2 and Pt/TiO2/Ti, were tested as catalysts for CO conversion. In the first case, the complete conversion of CO can be reached at 250°C, while in the second case it can be reached at 300°C.

Production of copper molybdates by the extraction-pyrolytic method

The dependence of the molybdenum recovery by isoamyl alcohol from solutions of ammonium paramolybdate on the HCl concentration is studied. Extracts with a metal content in the organic phase of up to 1.10 mol/dm3 are obtained. It is established by the method of infrared spectroscopy that Mo(IV) in an extractable compound gradually reduces to Mo(V) with the formation of aldehyde or acid. The molybdates CuMoO4 and Cu3Mo2O9 are synthesized by the pyrolysis of mixtures of molybdenum extracts in isoamyl alcohol and copper in n-octanoic acid. It is shown that the composition of the formed phases corresponds to the original stoichiometric ratios of metals in the mixture of extracts. The thermal decomposition of the mixture of Mo and Cu extracts proceeds in successive steps: before 350×C the CuCl and Cu phases are formed, which oxidize to Cu2OCl2 and CuO as the temperature rises. At over 350×C, there appear amorphous products of the destruction of the extractable Mo compound, and at the temperature range from 400 to 450×C the formation of molybdates takes place.

Nanostructured thin films of the La0.7Sr0.3MnO3 manganite obtained using the extraction pyrolytic method

The extraction pyrolytic method is used to fabricate thin (100–300 nm) films of the lanthanum manganites La0.7Sr0.3MnO3 on fused silica substrates. The films are deposited on the substrate using the alternate sessions of the centrifuging of solution and pyrolysis. The annealing of thin films at temperatures of greater than 650°C yields the single-phase La0.7Sr0.3MnO3 material. It is demonstrated that the annealing temperature substantially affects the magnetic properties of the resulting films: the films exhibit the properties of spin glasses and ferromagnetic properties at temperatures of less than 700°C and greater than 700°C, respectively.

Low-temperature extraction-pyrolytic synthesis of nanosized composites based on metal oxides

This article deals with the subject of synthesizing with the use of the extraction pyrolysis method of nanosized composites based on iron, manganese, bismuth, zirconium, europium, terbium oxides, and metal platinum, both in the form of powder and thin coatings on dielectric supports. The composition, morphology, and properties of nanosized synthesized materials are studied.

Cobalt ferrite nanoparticles in a mesoporous silicon dioxide matrix

We have studied magnetic nanoparticles of cobalt ferrite obtained by the extraction-pyrolysis method in a mesoporous silicon dioxide (MSM-41) molecular sieve matrix. The X-ray diffraction data show evidence for the formation of CoFe2O4 particles with a coherent scattering domain size of ∼40 nm. Measurements of the magnetization curves showed that powders consisting of these nanoparticles are magnetically hard materials with a coercive field of H c(4.2 K) = 9.0 kOe and H c(300 K) = 1.8 kOe and a reduced remanent magnetization of M r/M s(4.2 K) = 0.83 and M r/M s(300 K) = 0.49. The shape of the low-temperature (4.2 K) magnetization curves is adequately described in terms of the Stoner-Wohlfarth model for randomly oriented single-domain particles with a cubic magnetic anisotropy.

Preparation of photoactive materials based on porous silicon

The results of the investigation of the preparation of heterostructures for solar cells on the basis of porous silicon and photoactive oxide films are presented. The possibilities for the use of low-cost technologies of the electroerosive formation of porous silicon and an extraction pyrolysis method for the formation of thin films on porous silicon for the enhancement of solar cell efficiency were ascertained.

Oxide films for solar cells obtained by the extraction pyrolytic method

Oxide materials such as titanium dioxide and complex oxides of zinc, titanium, bismuth, and silicon are photoactive materials, and therefore, it is promising to use them for solar cells manufacturing. In order to start the commercial production of oxide film electrodes, it is necessary to develop the technology permitting the covering of large areas. In the presented work, it is shown how it is possible to obtain the films of TiO2 and of ZnTiO3 sensitized by ruthenium oxides deposited onto glass substrates using the extraction pyrolytic method.

Manganite Pr0.7Ca0.3MnO3 films obtained by extraction pyrolysis

The magnetic properties of manganite Pr0.7Ca0.3MnO3 films, obtained for the first time by the extraction pyrolysis method, have been investigated. The effect of the synthesis temperature of the magnetic properties of the manganite films is demonstrated.

Features of the magnetic properties of La0.7Sr0.3MnO3 Manganite films obtained by an extraction-pyrolysis method

We have experimentally studied the magnetic properties of manganite films obtained for first time using an extraction-pyrolysis technique. It is established that the characteristics of samples significantly depend on the conditions of final annealing. The annealing at temperatures Ta < 970 K is accompanied by strong thermomagnetic effects, and the resulting films possess properties similar to those of spin glasses. When the annealing temperature is increased to Ta ≥ 1020 K, the films exhibit magnetic properties typical of ferromagnetic systems.