Synthesis of superparamagnetic GdFeO 3 nanoparticles using a free impinging-jets microreactor
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Russian Chemical Bulletin, International Edition, Vol. 69, No. 7, pp. 1290—1295, July, 2020
Synthesis of superparamagnetic GdFeO3 nanoparticles using a free impinging-jets microreactor* Y. Albadi,a,b A. A. Sirotkin,a V. G. Semenov,c R. S. Abiev,a and V. I. Popkovd aSt.
Petersburg State Institute of Technology, 26 Moskovsky prosp., 190013 St. Petersburg, Russian Federation. E-mail: [email protected] bAl-Baath University, Syrian Arab Republic, 77 Homs cSt. Petersburg State University, 26 Universitetskaya nab., 198504 St. Petersburg, Petergof, Russian Federation dIoffe Institute, 26 ul. Politekhnicheskaya, 194021 St. Petersburg, Russian Federation Gadolinium orthoferrite GdFeO3 nanoparticles were synthesized by co-precipitation of gadolinium and iron(III) hydroxides in a free impinging-jets microreactor followed by thermal treatment of co-precipitation products. According to X-ray diffraction, the co-precipitated hydroxides were X-ray amorphous, and the content of key elements within their composition corresponded to the stoichiometry of GdFeO3. Powder X-ray diffraction of the product of thermal treatment of hydroxides at 750 C for 4 h indicated on the formation of GdFeO3 nanocrystals with a perovskite-like orthorhombic structure and an average crystallite size of 27±3 nm. Scanning electron microscopy showed that the gadolinium orthoferrite nanocrystals had an isometric morphology, and their specific surface area was determined by the Brunauer—Emmett— Teller method to be 13.55 m2 g–1. Mössbauer spectroscopy and vibrational magnetometry showed that the obtained GdFeO3 nanoparticles were superparamagnetic and were characterized by a bimodal distribution of the effective field, indicating on their core—shell-type composite structure. The study of the composition, structure, morphology, and magnetic behavior of the obtained gadolinium orthoferrite nanoparticles showed that they can be used as a basis for contrast agents for magnetic resonance imaging (MRI). Key words: perovskites, gadolinium orthoferrite, co-precipitation, free impinging-jets microreactor, superparamagnetic nanoparticles.
Nanocrystalline rare-earth orthoferrites LnFeO3 (Ln is a rare-earth element) with a perovskite-like structure have been actively studied since the 1960s due to their unique magnetic properties, which led to their widespread practical application.1 One of these compounds is gadolinium orthoferrite GdFeO3, which is of particular interest as a basis of materials for gas sensors, data storage devices, as well as a contrast agent for magnetic resonance imaging (MRI).1—4 Previously, various approaches were used for the synthesis of GdFeO3 nanoparticles, including co-precipitation,5 hydrothermal synthesis,6 solution combustion synthesis,7 as well as sol—gel,8 microwave,9 and some other methods. However, the traditional co-precipitation method of synthesizing GdFeO3 nanoparticles has not yet been successfully used to obtain ultrafine crystallites with super* Based on the materials of the XXI Mendeleev Congress on General and Applied Chemi
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