Properties of Ga-Doped Magnetite Nanoparticles

Rećko, K.; Klekotka, Urszula; Kalska-Szostko, B.; Soloviov, Dmytro; Satuła, D.; Waliszewski, J.

doi:10.12693/aphyspola.134.998

Cited by 7 publications

(2 citation statements)

References 12 publications

(17 reference statements)

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“…The presence of gallium in the activated catalyst suggests that dopant incorporation can occur during the activation procedure since no evidence of gallium incorporation was found in the catalyst precursor. Earlier, Kohout et al and Rećko et al suggested preferential occupation of tetrahedral sites of magnetite by gallium using NMR and Mössbauer spectroscopy, respectively, whereas a study by Wang et al indicated incorporation of gallium into both tetrahedral and octahedral sites using Mössbauer spectroscopy. These inconclusive findings might be due to the fact that the samples were prepared in different ways.…”

Section: Resultsmentioning

confidence: 99%

Substituting Chromium in Iron-Based Catalysts for the High-Temperature Water–Gas Shift Reaction

et al. 2022

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A set of doped iron oxides (chromium, aluminum, gallium, indium, manganese, zinc, niobium) were prepared by a one-step coprecipitation/calcination approach evaluated for their WGS activity under industrially relevant conditions and characterized in detail. The WGS activity after ageing the doped catalyst for 4 days at 25 bar follows the order chromium ≈ aluminum > gallium > indium > manganese > zinc > niobium for copper-codoped catalysts. The activated catalysts predominantly consist of magnetite, irrespective of the dopant. Mössbauer spectra of aged catalysts showed that aluminum and zinc occupy both tetrahedral and octahedral sites of magnetite, while chromium, gallium, indium, manganese, and niobium preferentially substitute octahedral iron. The incorporation of trivalent metal ions of similar size to octahedral Fe3+ (i.e., chromium, aluminum, gallium) results in moderate to high CO conversion, irrespective of incorporation in tetrahedral or octahedral sites. The substitution of Fe2+ with Mn2+ results in an increased Fe3+/Fe2+ ratio. Incorporation of Zn2+ in tetrahedral sites (replacing Fe3+ ions) leads to a complex structure where the charge balance is compensated from the octahedral sites. Separate dopant metal oxide phases were observed in indium- and niobium-doped catalysts. XPS shows that copper is present as a separate phase in activated copper-codoped catalysts. Aluminum is identified as the most promising promoter for substituting chromium in commercial high-temperature WGS catalysts on the basis of their similar high CO conversion although incorporation of these dopants into the magnetite structure differed substantially.

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Section: Resultsmentioning

confidence: 99%

Substituting Chromium in Iron-Based Catalysts for the High-Temperature Water–Gas Shift Reaction

et al. 2022

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“…Magnetites doped with bi- and trivalent cations form a group of innovative materials [ 19 , 20 , 21 , 22 , 23 , 24 , 25 ]. Among these, gallium nanoferrites seem to be promising candidates for use in magnetic hyperthermia [ 12 ].…”

Section: Introductionmentioning

confidence: 99%

Structural and Thermomagnetic Properties of Gallium Nanoferrites and Their Influence on Cells In Vitro

Orzechowska,

Rećko,

Klekotka

et al. 2023

IJMS

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Magnetite and gallium substituted cuboferrites with a composition of GaxFe3−xO4 (0 ≤ x ≤ 1.4) were fabricated by thermal decomposition from acetylacetonate salts. The effect of Ga3+ cation substitution on the structural and thermomagnetic behavior of 4–12 nm sized core-shell particles was explored by X-ray and neutron diffraction, small angle neutron scattering, transmission electron microscopy, Mössbauer spectroscopy, and calorimetric measurements. Superparamagnetic (SPM) behavior and thermal capacity against increasing gallium concentration in nanoferrites were revealed. The highest heat capacity typical for Fe3O4@Ga0.6Fe2.4O4 and Ga0.6Fe2.4O4@Fe3O4 is accompanied by a slight stimulation of fibroblast culture growth and inhibition of HeLa cell growth. The observed effect is concentration dependent in the range of 0.01–0.1 mg/mL and particles of Ga0.6Fe2.4O4@Fe3O4 design have a greater effect on cells. Observed magnetic heat properties, as well as interactions with tumor and healthy cells, provide a basis for further biomedical research to use the proposed nanoparticle systems in cancer thermotherapy (magnetic hyperthermia).

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Microscopic probing of the doping effects of In ions in Fe3O4

Sato

Ishizaki

Shimizu

et al. 2022

Journal of Applied Physics

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Minute examination of local lattice structures in matter affected by impurity doping is of special importance for the development of functional materials. In order to obtain microscopic information on spinel ferrites, in the present work, we introduced nonmagnetic In3+ ions in Fe3O4 and probed their site selectivity and the doping effect on the local lattice structures and bulk magnetism by means of 57Fe Mössbauer spectroscopy and positron annihilation spectroscopies. The Mössbauer parameters of the area intensity and isomer shift (IS) show that In3+ ions predominantly reside in the tetrahedral A site, especially at low doping level. With increasing concentration of In ions, however, they gradually occupy the octahedral B site replacing Fe3+ ions. Along with the site information, the IS values confirmed that the introduced In ions squeeze the B-site Fe ions at their nearest neighbors. Supporting results were obtained from positron annihilation lifetime spectroscopy; positron lifetimes become shorter with increasing In concentration, signifying that the oxygen ions are pressed by the introduced In ions resulting in lowering the volume of the adjacent lattice vacancies. The results of Doppler broadening spectroscopy also support the squeezing effect; the positrons in the vacancies adjacent to In ions are more likely to annihilate with the inner shell electrons of the surrounding oxygen ions as a result of a reduction in the vacancy volume.

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Properties of Ga-Doped Magnetite Nanoparticles

Cited by 7 publications

References 12 publications

Substituting Chromium in Iron-Based Catalysts for the High-Temperature Water–Gas Shift Reaction

Substituting Chromium in Iron-Based Catalysts for the High-Temperature Water–Gas Shift Reaction

Structural and Thermomagnetic Properties of Gallium Nanoferrites and Their Influence on Cells In Vitro

Microscopic probing of the doping effects of In ions in Fe3O4

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