Abstract
Interest in magnetic nanoparticles is primarily due to their practical use. In this work, for the production of nanocrystalline powders of pure and gadolinium doped iron oxides, the extraction-pyrolytic method (EPM) was used. As a precursor, either iron-containing extract (iron (III) caproate in caproic acid) or its mixture with gadolinium-containing extract (gadolinium (III) valerate in valeric acid) was used. The mixed precursor contained 0.5 mol %, 2.5 mol %, 12.5 mol %, 50 mol %, and 75 mol % gadolinium in relation to the iron content. The formation of iron oxide phases, depending on the preparation conditions, was investigated. According to the results obtained, it was demonstrated that the presence of more than 2.5 mol % gadolinium additive in the mixed precursor inhibits the magnetite-to-hematite transformation process during thermal treatment. Produced samples were characterized by XRD and SEM methods, and the magnetic properties were studied.
Highlights
Magnetic nanoparticles play an important role in the rapidly developing branches of science focusing on the study of nanocrystalline materials
The aim of this work is to investigate the formation of iron oxide phases depending on the pyrolysis temperature of the iron(III)-containing extract and the presence of different amounts of gadolinium (III) additive, as well as to investigate the magnetic properties of all produced materials
According to the results presented in [32], during the heat treatment of precursor 2, the mass loss of the sample ends at 450 ◦ C, and upon reaching 550 ◦ C, the crystallization of gadolinium oxide begins
Summary
Magnetic nanoparticles play an important role in the rapidly developing branches of science focusing on the study of nanocrystalline materials. Magnetite has the inverse spinel structure, in which half of Fe3+ ions occupy tetrahedral positions, while Fe3+ and Fe2+ are uniformly distributed over octahedral positions. Maghemite has the inverse spinel structure, along with structural vacancies. Unlike magnetite, it contains only Fe3+ ions [1]. Hematite (α-Fe2 O3 ) is another phase of iron oxide, in which all Fe3+ ions have an octahedral coordination. It is antiferromagnetic at temperatures below 950 K, while, above 260 K, it exhibits so-called “weak” ferromagnetism [2,3]. Magnetite-to-hematite oxidation proceeds either directly or via maghemite [4,5]
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