The potential for the practical application of bismuth ferrite (BFO) in information storage, microelectronic, and spintronic devices and in medical sensors of various purpose is limited by the presence of a spin cycloid. Its destruction, including destruction due to doping with rare earth elements and the transfer of BFO to a nanoscale state, contributes to the occurrence of ferromagnetism and the manifestation of the magnetoelectric effect. The study was aimed at the synthesis of bismuth ferrite nanopowder doped with erbium ions.By spray pyrolysis at a temperature of 760 °C, we synthesised BFO samples with a nominal degree of doping with erbium ions from 0.05 to 0.20. The data of X-ray diffraction analysis show that there is a small amount of Bi25FeO39 and Bi2Fe4O9 in the doped samples.The shift of the BFO reflections on diffraction patterns towards larger 2q angles is representative of the incorporation of erbium ions into the crystal lattice of BiFeO3. The morphological characteristics of the samples were determined using transmission electron microscopy. According to the data of electron probe X-Ray microanalysis, the real composition of the doped ErxBi1-xFeO3 samples is very close to the nominal.The particles of ErxBi1-xFeO3 powders synthesised by spray pyrolysis have a nearly spherical shape, the particle-size distribution is in the range of 5–300 nm, the predominant number of particles have a size in the range of 50-200 nm, and the agglomeration is weak. The decrease in the crystal lattice parameters and the unit cell volume of ErxBi1-xFeO3 and an increase in the degree of doping with erbium ions confirm the incorporation of Er3+ into the BFO crystal lattice to the bismuth position.

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Установлено активирующее действие микроволнового излучения в процессе синтеза нанопорошков ортоферрита иттрия, допированного никелем, заключающеесяв значительном увеличении скорости процесса, снижении температуры отжига, высокой химической гомогенности синтезированных образцов. Реальная степень допирования согласно результатам локального рентгеноспектрального микроанализа оказалась несколько ниже номинальной, максимальная реальная степень допирования составляет 0.12. Средний размер частиц YFeO3 и NiхY1-хFeO3 находится в диапазоне 200–300 нм.   REFERENCES Popkov V. I., Almjasheva O. V. Yttrium orthoferrite YFeO3 nanopowders formation under glycine-nitrate combustion conditions. Russian Journal of Applied Chemistry, 2014, v. 87(2), pp. 167-171. https://doi.org/10.1134/S1070427214020074 Letyuk L. M., Kostishin V. G., Gonchar A. V. Tekhnologiya ferritovykh materialov magnitoelektroniki [Technology of ferrite materials of magnetoelectronics]. Moscow, MISiS Publ., 2005, 352 p. (in Russ.) Petrova E., Kotsikau D., Pankov V. Structural characterization and magnetic properties of sol–gel derived ZnxFe3-xO4 Journal of Magnetism and Magnetic Materials, 2015, v. 378, pp, 429–435. https://doi.org/10.1016/j.jmmm.2014.11.076 Mittova I. Ya., Tomina E. V., Lavrushina S. S. Nanomaterialy: sintez nanokristallicheskikh poroshkov i poluchenie kompaktnykh nanokristallicheskikh materialov: uchebnoe posobie dlya vuzov [Nanomaterials: the synthesis of nanocrystalline powders and the production of compact nanocrystalline materials: a textbook for universities]. Voronezh, LOP VGU Publ., 2007, 35 p. (in Russ.) Brandon D., Kaplan W. Microstructural Characterization of Materials. Chichester: John Wiley & Sons Ltd, 1999, 424 p. Tretyakov Yu. D. Development of inorganic chemistry as a fundamental for the design of new generations of functional materials. Russian Chemical Reviews, 2004, v. 73(9), pp. 831–846. https://doi.org/10.1070/RC2004v073n09ABEH000914 Tomina E. V., Mittova I. Ya., Burtseva N. A., Patent RF, N 2548089, 2015. Kuznetsova V. A., Almjasheva O. V., Gusarov V. V. Infl uence of microwave and ultrasonic treatment on the formation of CoFe2O4 under hydrothermal conditions. Glass Physics and Chemistry, 2009, v. 35(2), pp. 205–209. International Center for Diffraction Data. Shpanchenko R. V., Rozova M. G. Metodicheskaya razrabotka dlya spetspraktikuma k kursu lektsii «Prakticheskie aspekty rentgenovskoi difraktometrii» [Methodical development for the special practical course for lectures “Practical aspects of X-ray diffractometry”]. Moscow, Izd-vo Mosk. un-ta Publ., 1998, 25 p. (in Russ.) Tret’yakov Yu. D. Neorganicheskaya khimiya. Khimiya elementov: uchebnik dlya stud. vuzov, obuch. po napravleniyu 510500 “Khimiya” i spetsial’nosti 011000 “Khimiya” : v 2 t [Inorganic chemistry. Chemistry of elements: a textbook for students. universities enrolled in the direction 510500 “Chemistry” and specialization 011000 “Chemistry”: in 2 volumes]. Moscow, Izd-vo Mosk. un-ta: Akademkniga Publ., 2007, v. 1, 538 p.; v. 2, 670 p. (in Russ.) Tomina E. V., Darinskii B. M., Mittova I. Ya., Churkin V. D., Boikov N. I., Ivanova O. V. Sintez nanokristallov YСоxFe1-xO3 pod vozdeistviem mikrovolnovogo izlucheniya [Synthesis of YСоxFe1-xO3 Nanocrystals Under the Microwave Radiation], Inorganic Materials, v. 55(4), 2019, pp. 421–425. https://doi.org/10.1134/S0002337X19040158    (in Russ.)

New magnetic nanocomposite sorbents were obtained by doping natural bentonite with nanosized CoFe2O4 spinel (10 and 20 wt.%). Nanocrystals of cobalt ferrite were synthesized by a citrate burning method. The structure and physical-chemical properties of the composites were characterized by XRD, XRF, TEM, BET, FTIR and Faraday balance magnetometry. During the formation of nanocomposites, 10–30 nm particles of cobalt ferrite occupied mainly the interparticle space of Fe-aluminosilicate that significantly changed the particle morphology and composite porosity, but at the same time retained the structure of the 2:1 smectite layer. A combination of two functional properties of composites, adsorption and magnetism has been found. The adsorption capacity of magnetic nanosorbents exceeded this parameter for bentonite and spinel. Despite the decrease in the adsorption volume, pore size and specific surface area of the composite material relative to bentonite, the sorption activity of the composite increases by 12%, which indicated the influence of the magnetic component on the sorption process. FTIR data confirmed the mechanism of formaldehyde sorption by the composite sorbent. The production of a magnetic nanosorbent opens up new possibilities for controlling the sorption processes and makes it possible to selectively separate the sorbent from the adsorption medium by the action of a magnetic field.

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