Ekaterina Alekseevna Tugova

Ekaterina Alekseevna Tugova
Russian Academy of Sciences | RAS ·  Ioffe Physical-Technical Institute

PhD

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37
Publications
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361
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Publications

Publications (37)
Article
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In this paper, the achievements, problems and prospects of creating personalized energy systems based on nanostructured materials are analyzed. Various concepts of developing methods and ways of personalized energy provision for autonomous human survival in remote natural habitats, emergencies of natural disasters and technogenic catastrophes when...
Article
NdCoO3 nanocrystals formed via glycine–nitrate combustion method followed by heat treatment has been systematically studied. Formation of NdCoO3 nanocrystals with minimal size of 7–10 nm from X-ray amorphous combustion products has been elucidated to be a very rapid process, occurring at the temperature of 550–600 °C for 5–30 min. The comparison of...
Article
The paper considers phase equilibria in the subsolidus region of the GdFeO3-SrFeO3-δ system in air. By using X-ray powder diffraction, SEM/EDS, and Mössbauer spectroscopy, a GdFeO3-SrFeO3-δ phase diagram was constructed in the 1300–1500 °C temperature range. The samples of Gd1-xSrxFeO3-α for this study were synthesized by solid-phase chemical react...
Article
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Nanocrystals of Nd 1 − x Bi x FeO 3 were produced during the process of combustion of the glycine-nitrate with precursors together with an excess amount of the oxidizing agent. X-ray diffraction patterns and Raman spectra were measured for investigation of the structure of the synthesized material. Hidden periodicities were extracted in the Raman s...
Article
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The effect of cationic composition and sintering conditions on the electrotransport and thermoelectric properties of Ca 3 Co x O 9+δ (x = 3.8, 4.0, and 4.2) had been investigated. It had been found that increase of cobalt oxide content in the samples increase their electrical conductivity, creation of phase inhomogeneity improves their thermo-EMF c...
Article
The formation mechanisms for a series of n = 2 Ruddlesden-Popper phases Ln2SrFe2O7 (Ln = La, Nd, Gd, Dy) in the Ln2O3-SrO-Fe2O3 systems were determined. The solid-state synthesis of Ln2SrFe2O7 (Ln = La, Nd) proceeds by a mechanism involving the stage of formation of LnFeO3 and LnSrFeO4 intermediates with their subsequent interaction to form the tar...
Article
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The minimum crystallite size in a group of oxides has been analyzed as a function of their synthesis conditions, critical nucleus size and the crystal structure parameters. Nanocrystals were synthesized by solution combustion, hydrothermal synthesis and heat treatment in air of the precipitated hy-droxides. Aluminum and iron oxides, titania and zir...
Article
Nd1–xBixFeO3 nanocrystals with crystallite size 30‒60 nm have been prepared under conditions of glycine–nitrate burning. Single-phase Nd1–xBixFeO3 nanocrystals are formed over the entire studied concentrations range if the glycine–nitrate synthesis is performed in excess of the oxidizer. Under these conditions, a continuous range of the Nd1–xBixFeO...
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Phase equilibria at subsolidus area of quasi-triple BiO1.5–CaO–CoOy system in air have been studied. The formation of triple oxide Bi2Ca2Co1.7Ox and limited number of solid solutions (Ca,Bi)3Co4O9+δ has been established. The triangulation of BiO1.5–CaO–CoOy system in air at 973 K has been carried out.
Article
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The effect of isovalent cation substitution of lanthanum atoms in the structure of La2SrAl2O7 oxide, and phase equilibria (solidus-liquidus curves) in the binary system La2SrAl2O7-Nd2SrAl2O7 were studied. It was found that Nd3+ substitution for La3+ has effect on the structure of La2SrAl2O7 in respect of the character of cation distribution in the...
Article
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Heat treatment of coprecipitated hydroxides in air has afforded isometric nanocrystals of rhombic yttrium, lanthanum, and gadolinium ferrites with average crystallite size 40±4 nm. It has been stated that the formation of XFeO3 (X = Y, La, Gd) nanocrystals occurs via two mechanisms, from the corresponding coprecipitated hydroxide (main route) and f...
Article
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Effect of synthesis conditions on the formation and dielectric characteristics of materials based on the La0.33Ca0.67Al0.33Ti0.67O3 phase was studied. It is shown that the new approach suggested in the study to obtaining ceramic materials based on the LaAlO3–CaTiO3 system via introduction of an excess amount of Al2O3 over the stoichiometry of La0.3...
Article
Regularities of formation of complex aluminates with structure of P/RS intergrowth type phases in the Ln2O3–MO–Al2O3 systems (Ln = rare-earth element, M = Mg, Ca, Sr, Ba) have been considered. Systematization of the data on formation of complex compounds coexisting with one-layer phases in the Ln2O3–MO–Al2O3 systems and analysis of geometry criteri...
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The sequence of phases appearance during the formation of Bi1–xNdxFeO3 solid solutions in powder oxides mixtures of bismuth, neodymium, and iron has been determined. It has been shown that the closeness of the reaction mixture composition to that of the individual compound (BiFeO3 or NdFeO3) is essential for the realization of the series of phase t...
Article
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Direct solution combustion synthesis of oxide nanoparticles has been of great interest in recent years because of its rapidity, simplicity and cost effectiveness. Nanoparticles obtained by mentioned method, as a rule, possess comparatively narrow size distribution and high surface area, which provides the possibility for its industrial and technica...
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We have studied the thermal, electrical, and thermoelectric properties of Ca3–x Bix Co4O9 + δ (0.0 ≤ x ≤ 1.5) ceramics prepared by solid-state reactions. Phase-pure Ca3–x Bix Co4O9 + δ solid solutions were obtained at x ≤ 0.3. The samples with 0.3 < x < 1.5 consisted of three phases: Ca2.7Bi0.3Co4O9 + δ, Bi2Ca2Co1.7Oy , and Со3О4. The sample with t...
Article
For the first time, DySrAlO4 of K2NiF4-type structure was synthesized. The parameters of DySrAlO4 elementary unit cell are determined as follows: a = 0.368 (4) nm, c = 1.229 (2) nm, V = 0.166 (4) nm3. The research of the complex aluminates LnSrAlO4 (Ln = Nd, Gd, Dy) solid-state process demonstrated the change of the formation mechanism among LnSrAl...
Article
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By means of solid-state reactions method the Ca3–xBixCo3.85Bi0.15O9+delta (0.2 <= x <= 0.5) was synthesized, its phase composition, microstructure, physicochemical and thermoelec-tric properties was investigated. It was found that complex substitution of calcium and cobalt by bismuth in Ca3Co4O9+delta lead to the improvement of sinterability and de...
Article
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Materials based on layered calcium (Ca3Co4O9 + δ) and calcium-bismuth (Bi2Ca2Co1.7Oy ) cobaltites were derived based on a technique of solid-phase reactions. Their thermal expansion, electrical conductivity, and thermoelectric power were found. It was demonstrated that these materials are p-type semiconductors with a coefficient of linear thermal e...
Article
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The ceramic samples of Bi0.85Nd0.15FeO3, BiFe0.85Mn0.15O3, and Bi0.85Nd0.15Fe0.85Mn0.15O3 solid solutions were synthesized, their lattice constants were determined, and their microstructure, thermal expansion, magnetic susceptibility, magnetic moment, electrical conductivity, and thermo-EMF were studied. It was found that Bi0.85Nd0.15FeO3 and BiFe...
Article
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The continuous Gd2Sr(Al1 − x Fex )2O7 solid solution series was synthesized by a solid-state route over the entire concentration range (0 < x < 1). The processing stages of Gd2Sr(Al1 − x Fex )2O7 series were investigated, and phase interaction schemes reflecting the multistaged formation of double-layered Ruddlesden-Popper solid solution are constr...
Article
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The continuous series of perovskite-related oxides with the general formula Gd2Sr(Al1−x Fex )2O7 0 < x < 1 were prepared by conventional ceramic technology in air. The processing stages of Gd2Sr(Al1−x Fex )2O7 0 < x < 1 phases were investigated by means of X-ray powder diffraction (XRD) and scanning electron microscopy (SEM) with the element phase...
Article
It is shown that Sr1−xGdxFeO3−α solid solution formation on initial stage of GdSrFeO4 oxide solid state synthesis leads to the occurrence of stable secondary products, mainly, Gd2SrFe2O7. The data investigation presents some ways of intermediate compounds formation avoidance by revising of solid state chemical reaction passing scheme.
Article
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A comparative analysis of the formation processes of Ruddlesden-Popper phases in the La2O3-SrO-M 2O3 (M = Al, Fe) systems has been performed. It is demonstrated that, in order to provide the completeness of the occurrence of the processes, it is necessary to introduce SrO in some excess into the reaction system. The inference is made that the prese...
Article
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Phase relations in the Y2O3-Ga2O3 system were studied by the anneal-and-quench technique in air within 1000–2300°C, and a phase diagram was plotted. Three compounds were found to form: Y3GaO6, Y4Ga2O9, and Y3Ga5O12; the temperature and concentration bounds of stability were determined for these compounds. Indexing results for Y3GaO6 are given.
Article
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Magnetic susceptibility of complex perovskite-like oxides Gd2SrFe2O7 and Gd2SrAl2O7 was studied. A sharp decrease in the magnetic characteristics of gadolinium ferrite as compared to gadolinium aluminate points to the presence of strong antiferromagnetic interactions between the iron ions.
Article
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The phase formation is investigated and the phase diagram of the Ho2O3-SrAl2O4 system is constructed. A ternary compound, namely, Ho2SrAl2O7, is revealed. It is established that this compound undergoes incongruent melting.
Article
The mechanism of formation of the perovskite-like layered structure of the oxide Gd2SrFe2O7 was studied. The limiting stages are those of formation of phases with perovskite (GdFeO3, SrFeO3−x ) and K2NiF4 (GdSrFeO4) structures. The Mössbauer study has shown that iron atoms exist in a heterovalent state (Fe3+ and Fe4+) only in the structure of SrFeO...
Article
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Phase formation processes in the systems Ln2O3-SrO-Fe2O3 (Ln = La, Nd) in air in the temperature range 1200–1500°C were studied. The synthesis of the complex ferrites La2SrFe2O7 and Nb2SrFe2O7 involves the formation of the intermediate compounds LnFeO3 and LnSrFeO4 and occurs by the same mechanism as the synthesis of the corresponding aluminates, b...
Article
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The phase relationships in the LaFeO3-LaSrFeO4 system at temperatures in the range 1000–2100°C in air are investigated, and the phase diagram of the system is constructed. One perovskite-like compound, namely, La2SrFe2O7, which belongs to the Ruddlesden-Popper phases, is revealed in the system.
Article
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The phase equilibria are investigated and the phase diagram is constructed for the Gd2O3-SrAl2O4 pseudobinary join of the Gd2O3-SrO-Al2O3 ternary oxide system. One ternary compound, namely, Gd2SrAl2O7, is revealed in the Gd2O3-SrAl2O4 join. It is found that this compound undergoes congruent melting.
Article
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The phase equilibria are investigated and the phase diagram is constructed for the LaAlO3-LaSrAlO4 pseudobinary join of the La2O3-SrO-Al2O3 ternary oxide system. One ternary compound, namely, La2SrAl2O7, is found in the LaAlO3-LaSrAlO4 join. The crystallographic, thermal, and some other physicochemical characteristics of the compounds are reported.

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