E. V. Pashkova

Effects of Chemical Composition and Sintering Temperature on the Structure of La1 – xSrxMnO3 ± γ Solid Solutions

AbstractThe structural parameters of La1 – xSrxMnO3 ± γ solid solutions sintered at different temperatures are refined using chemical analysis, x-ray fluorescence, and Rietveld profile analysis data. The samples are shown to consist of two rhombohedrally distorted perovskite phases (sp. gr. R

Effect of synthesis methods on the morphology of nanosized tin dioxide particles

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Phase Composition of Heat-Treatment Products in the ZrO(OH)2–Y(OH)3–FeOOH System

c and R3m) identical in chemical composition and containing excess oxygen. The electrical properties and magnetoresistive response of the Sr-doped lanthanum manganite ceramics depend on the relative amounts of these phases. The origin of structural disordering in the materials studied is discussed.

Lithium-cation Conduction and Crystallochemical Features of Solid Solutions La2/3 – xLi3x□4/3 – 2xNb2O6 with the Structure of Fault Perovskite

The phase composition and particle shape of amorphous iron hydroxide-iron oxide precipitates were correlated with the oxidation state of iron in the starting solution, Fe2O3 : FeO ratio, and precipitation procedure (coprecipitation or successive precipitation) using Mössbauer spectroscopy, atomic absorption, lowtemperature nitrogen BET, and electron microscopy data. A correlation was established between the amount of iron(II) in the starting solution, the amount of the metastable phase γ-Fe2O3 in the precipitate, particle shape, and the activity of the final heat-treatment products—α-Fe2O3 and mixed oxides of iron.

Mössbauer and X-ray diffraction studies of cubic (ZrO2)0.90(Sc2O3)0.10 − x(Fe2O3)x solid solutions

The effect of precursors on the microstructure of nanocrystalline tin dioxide is studied by thermal analysis, IR spectroscopy, electron microscopy, and X-ray powder diffraction. The precursor precipitated in an optimal pH range whose dehydration and crystallization occur over a wide temperature range with low degrees of oxolation yields crystalline tin dioxide with grain sizes on the order of 16 nm upon calcination at 800°C for 2 h.

Fractal structure of precursors and phase transformations in the sol-gel synthesis of nanoparticulate M-type barium hexaferrite

We have studied the effect of “double” substitution in Ba0.7Sr0.3Fe12 − 2xCoxTixO19 on the structural and magnetic properties of M-type barium hexaferrite. The basic composition of Ba1 − xSrxFe12O19 obtained by heat-treating carbonate-hydroxide precipitates has been optimized (x = 0.3). 2Fe3+ → Co2+ + Ti4+ substitutions considerably reduce the coercive force (Hc) and increase the magnetization (Ms) relative to Ba0.7Sr0.3Fe12 O19.

Structural and magnetic properties of BaFe12 − 2x Co x Sn x O19 modified M-type hexaferrites

The phase composition of the heat-treatment products in the ZrO(OH)2–Y(OH)3–FeOOH system is determined as a function of the precipitation procedure and calcination temperature (620–1570 K) for the compositions 0.97ZrO2· xY2O3· yFe2O3(x+ y= 0.03; x= 0, 0.01, 0.015, 0.02, 0.03) and (1 – x– y)ZrO2· xY2O3· yFe2O3(x= y= 0.02, 0.025, 0.03, 0.04). At a given ZrO2: stabilizer ratio, partial substitution of Fe3+for Y3+increases the degree of ZrO2stabilization and retards the low-temperature degradation of the material.

Structural and magnetic properties of BaFe12 − 2xCoxSnxO19 modified M-type hexaferrites

Transport properties and crystallochemical features of lithium-containing lanthanum metaniobates La2/3 – xLi3x□4/3 – 2xNb2O6 with the structure of fault perovskite are studied. The materials studied have high conductivity by lithium ions. A correlation between the conductivity magnitude, chemical composition, and crystallographic parameters is found.