Evolution of the Magnetic and Structural Properties with the Chemical Composition in Oleate-Capped MnxCo1–xFe2O4 Nanoparticles

Angotzi, Marco Sanna; Mameli, Valentina; Zákutná, Dominika; Kubániová, Denisa; Cara, Claudio; Cannas, Carla

doi:10.1021/acs.jpcc.1c06211

Cited by 13 publications

(8 citation statements)

References 90 publications

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“…A representative series of hydrophilic core-shell MNPs with narrow CoFe 2 O 4 core size and shell thickness distributions was prepared using two-step hydrothermal synthesis reported previously [45]. First, the hydrophobic oleate-coated core-shell MNPs were built from two different sizes of the oleate-coated CoFe 2 O 4 MNPs (termed Co1 and Co2) followed by the growth of spinel ferrite shells: Mn = MnFe 2 O 4 and Fe = γ-Fe 2 O 3 (termed Co1@Mn, Co1@Fe, Co2@Mn, and Co2@Fe).…”

Section: Methodsmentioning

confidence: 99%

Self-Limitations of Heat Release in Coupled Core-Shell Spinel Ferrite Nanoparticles: Frequency, Time, and Temperature Dependencies

et al. 2021

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We explored a series of highly uniform magnetic nanoparticles (MNPs) with a core-shell nanoarchitecture prepared by an efficient solvothermal approach. In our study, we focused on the water dispersion of MNPs based on two different CoFe2O4 core sizes and the chemical nature of the shell (MnFe2O4 and spinel iron oxide). We performed an uncommon systematic investigation of the time and temperature evolution of the adiabatic heat release at different frequencies of the alternating magnetic field (AMF). Our systematic study elucidates the nontrivial variations in the heating efficiency of core-shell MNPs concerning their structural, magnetic, and morphological properties. In addition, we identified anomalies in the temperature and frequency dependencies of the specific power absorption (SPA). We conclude that after the initial heating phase, the heat release is governed by the competition of the Brown and Néel mechanism. In addition, we demonstrated that a rational parameter sufficiently mirroring the heating ability is the mean magnetic moment per MNP. Our study, thus, paves the road to fine control of the AMF-induced heating by MNPs with fine-tuned structural, chemical, and magnetic parameters. Importantly, we claim that the nontrivial variations of the SPA with the temperature must be considered, e.g., in the emerging concept of MF-assisted catalysis, where the temperature profile influences the undergoing chemical reactions.

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Section: Methodsmentioning

confidence: 99%

Self-Limitations of Heat Release in Coupled Core-Shell Spinel Ferrite Nanoparticles: Frequency, Time, and Temperature Dependencies

et al. 2021

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“…Comp, on the contrary, reveals a broadband at about 22 • , typical of amorphous silica, and the distinctive reflexes of two Fe III oxides, i.e., hematite and maghemite. All the RT Mössbauer spectra (Figure 1c) are characterized by isomer shift values in the range 0.32-0.38 mm s −1 , typical of Fe III -based phases (Table S2) [52][53][54][55][56][57][58]. The Aka, Fer, and Comp spectra feature one or more doublets, whereas the Mag spectrum can be fitted with two broad sextets, accounting for the distribution of hyperfine fields.…”

Section: Characterization Of the Sorbentsmentioning

confidence: 99%

As(III, V) Uptake from Nanostructured Iron Oxides and Oxyhydroxides: The Complex Interplay between Sorbent Surface Chemistry and Arsenic Equilibria

et al. 2022

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Iron oxides/oxyhydroxides, namely maghemite, iron oxide-silica composite, akaganeite, and ferrihydrite, are studied for AsV and AsIII removal from water in the pH range 2–8. All sorbents were characterized for their structural, morphological, textural, and surface charge properties. The same experimental conditions for the batch tests permitted a direct comparison among the sorbents, particularly between the oxyhydroxides, known to be among the most promising As-removers but hardly compared in the literature. The tests revealed akaganeite to perform better in the whole pH range for AsV (max 89 mg g−1 at pH0 3) but to be also efficient toward AsIII (max 91 mg g−1 at pH0 3–8), for which the best sorbent was ferrihydrite (max 144 mg g−1 at pH0 8). Moreover, the study of the sorbents’ surface chemistry under contact with arsenic and arsenic-free solutions allowed the understanding of its role in the arsenic uptake through electrophoretic light scattering and pH measurements. Indeed, the sorbent’s ability to modify the starting pH was a crucial step in determining the removal of performances. The AsV initial concentration, contact time, ionic strength, and presence of competitors were also studied for akaganeite, the most promising remover, at pH0 3 and 8 to deepen the uptake mechanism.

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“…Recently, we set up a versatile solvothermal synthesis method able to produce single-phase spherical particles [ 70 , 71 ], chemically mixed spinel phases [ 72 , 73 ], homogeneous spherical bi-magnetic core–shell NPs [ 46 , 70 , 74 , 75 ], and flower-like Ag-spinel ferrite nanoarchitectures [ 1 ] with high crystallinity, low size dispersity, and precise control of the shell growth.…”

Section: Introductionmentioning

confidence: 99%

Hard–Soft Core–Shell Architecture Formation from Cubic Cobalt Ferrite Nanoparticles

et al. 2023

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Cubic bi-magnetic hard–soft core–shell nanoarchitectures were prepared starting from cobalt ferrite nanoparticles, prevalently with cubic shape, as seeds to grow a manganese ferrite shell. The combined use of direct (nanoscale chemical mapping via STEM-EDX) and indirect (DC magnetometry) tools was adopted to verify the formation of the heterostructures at the nanoscale and bulk level, respectively. The results showed the obtainment of core–shell NPs (CoFe2O4@MnFe2O4) with a thin shell (heterogenous nucleation). In addition, manganese ferrite was found to homogeneously nucleate to form a secondary nanoparticle population (homogenous nucleation). This study shed light on the competitive formation mechanism of homogenous and heterogenous nucleation, suggesting the existence of a critical size, beyond which, phase separation occurs and seeds are no longer available in the reaction medium for heterogenous nucleation. These findings may allow one to tailor the synthesis process in order to achieve better control of the materials’ features affecting the magnetic behaviour, and consequently, the performances as heat mediators or components for data storage devices.

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Evolution of the Magnetic and Structural Properties with the Chemical Composition in Oleate-Capped Mn_xCo_1–xFe₂O₄ Nanoparticles

Cited by 13 publications

References 90 publications

Self-Limitations of Heat Release in Coupled Core-Shell Spinel Ferrite Nanoparticles: Frequency, Time, and Temperature Dependencies

Self-Limitations of Heat Release in Coupled Core-Shell Spinel Ferrite Nanoparticles: Frequency, Time, and Temperature Dependencies

As(III, V) Uptake from Nanostructured Iron Oxides and Oxyhydroxides: The Complex Interplay between Sorbent Surface Chemistry and Arsenic Equilibria

Hard–Soft Core–Shell Architecture Formation from Cubic Cobalt Ferrite Nanoparticles

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