Heterostructures based on multiferroic bismuth ferrite, BiFeO3, are proposed for use in micro-wave HEMTs and for the synthesis of high-T c materials with a high superconducting transition temperature T c.

Выполнен численный конечно-разностный расчет дипольного вихря-скирмиона в мультиферроике BiFeO3 и показана стабилизирующая роль электростатического диполь-дипольного взаимодействия. Приведены основные методы создания вихревых решеток в BiFeO3 и показано возможное их использование в спинтронике и диптронике.

This paper presents finite difference calculations of a dipole skyrmion vortex in multiferroic BiFeO 3 and demonstrates a stabilizing role of electrostatic dipole-dipole interaction. We consider the main approaches to producing vortex lattices in BiFeO 3 and their potential applications in spintronics and diptronics.

The kinetics of BiFeO3 formation from xerogel prepared by reverse coprecipitation were studied at different synthesis temperatures. We examined the influence of annealing temperature on the morphology of the reaction products and optimized synthesis conditions, which allowed us to obtain 99.7 wt % pure BiFeO3 consisting of crystalline grains less than 50 nm in size. Its magnetic properties were investigated.

This paper examines the main applications of bismuth ferrite and bismuth titanate and demonstrates their potential applications in spintronics and radioelectronics.

The formation of carbon structures upon the reactions of organic compounds with strong mineral acids under hydrothermal conditions was studied. The reactions were found to give amorphous carbon, microcrystalline graphite, nanodiamonds, diamond-like carbon, diamonds, C60 and C70 fullerenes, and carbolite. Hydrocarbons of various compositions including aromatics and naphthenes were detected among the reaction products. A possible mechanism of the formation of carbon structures with sp 2 bond hybridization under hydrothermal conditions was proposed.

The interaction in the system Bi(NO3)3-K3HCit-(H2O + glycerol) was studied by chemical analysis and pH titration over a wide range of ratios between the initial components. Solid phases of the compositions Bi(OH)3−3x HCit x · nH2O and KBiCit · H2O were isolated and investigated by X-ray powder diffraction and differential thermal analyses and IR spectroscopy. The effect of the chemical nature of the alkali metal on the solubility in the system under consideration was demonstrated.

Изучена кинетика образования BiFeO3 при различных температурах синтеза из ксерогеля, полученного методом обратного химического соосаждения. Рассмотрено влияние температуры отжига на морфологию продуктов реакции. Оптимизированы условия синтеза и получен материал с содержанием BiFeO3 не менее 99.7 мас. % и с размерами кристаллических зерен менее 50 нм. Исследованы его магнитные свойства.

An integrodifferential equation for skyrmions in a magnetic material is solved by the finite-difference method with allowance for Dzyaloshinskii-Moriya and dipole-dipole interactions.

Изучено влияние механохимической активации на реакционную способность смеси оксидов Bi2O3 и Fe2O3. Проведено сравнительное исследование влияния температуры на кинетику образования BiFeO3 для смесей до и после механохимической активации. Оптимизированы условия синтеза феррита висмута методом твердофазных реакций. Получен материал с содержанием BiFeO3 не менее 98.3 мас. %. Изучены его магнитные свойства.

Изучено образование углеродных структур, возникающих при взаимодействии органических веществ с сильными минеральными кислотами в гидротермальных условиях. Установлено, что продуктами реакций являются аморфный углерод, микрокристаллический графит, наноалмазы, алмазоподобный углерод, алмазы, фуллерены С60 и С70 и карболайт. В продуктах реакции обнаружены углеводороды разного состава, в том числе ароматические и нафтеновые соединения. Предложен возможный механизм образования углеродных структур с sp2-гибридизацией связей в гидротермальных условиях.

We have studied the effect of mechanochemical activation on the reactivity of Bi 2 O 3 + Fe 2 O 3 oxide mixtures, assessed the temperature effect on the kinetics of BiFeO 3 formation in the oxide mixtures before and after mechanochemical activation, and optimized the conditions of bismuth ferrite synthesis by solid-state reaction. A material with a BiFeO 3 content of at least 98.3 wt % has been obtained, and its magnetic properties have been investigated.

Рассмотрены основные применения феррита и титаната висмута. Показана перспектива их использования в спинтронике и радиоэлектронике.

We gave studied the crystallization behavior of 30BaO · 25Bi 2 O 3 · 45B 2 O 3 glasses doped with Eu 2 O 3 to different levels. At a Eu 2 O 3 content of 7 mol % or higher, the glasses undergo volume crystallization. The only precipitating phase is a solid solution between europium and bismuth oxides. With increasing europium concentration in the glass, the structure of the crystallites changes from cubic to rhombohedral. We have investigated the morphology, physicochemical properties, and luminescence spectra of the glasses and glass-ceramics.

A method was developed for introducing gallium into Mg-Al hydrotalcites—precursors of oxide catalysts for oxidative dehydrogenation of alkanes. Samples of oxide catalysts were synthesized that contained gallium oxide and also oxides of magnesium, aluminum, chromium, vanadium, molybdenum, and niobium in various combinations. The catalytic properties of the produced catalysts were studied in the oxidative dehydrogenation of ethane, propane, isobutane, and hexane. It was established that the addition of gallium to catalysts increases the ethylene and propylene yields in the oxidative dehydrogenation of ethane and propane. New hydroxo salts with a layered structure of the hydrotalcite type were synthesized: ternary magnesium gallium aluminum hydroxonitrate of variable composition [Al1 − n Ga n Mg m (OH)3 + 2m − 1][NO3 · nH2O] and quaternary magnesium gallium chromium aluminum hydroxonitrate of the composition [AlGaCrMg1.8(OH)11.6][NO3 · nH2O]; these salts were found to be isostructural.

Major ways to improve the magnetic and electrical properties of promising multiferroic BiFeO3 and optimize its synthesis have been studied, and its applications in spintronics, photonics, and magnonics have been discussed.

A compound with the general formula Bi 36 MgP 2 O 60 − δ was obtained by a solid-state reaction method. Its composition was confirmed using EDAX. The compound belongs to the cubic crystal system (space group I 23, no. 197) and has a sillenite-type structure. The lattice parameter a o is 10.15704(12) Å. The Rietveld refinement of the crystallographic data revealed mixed tetrahedral sites (2 a ) occupied by Mg, P, and Bi in a ratio of 32: 63: 5. The resulting lattice strains are compensated by vacancies in the cationic (2 a ) and anionic sites (24 f ) and by distortion of the Bi-O framework detected by IR and Raman spectroscopy.