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Keywords = manganese-cobalt ferrite nanoparticles

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16 pages, 12733 KiB  
Article
Enhanced Magnetic Properties of Co1−xMnxFe2O4 Nanoparticles
by Adam Szatmari, Rareș Bortnic, Roman Atanasov, Lucian Barbu-Tudoran, Fran Nekvapil, Roxana Dudric and Romulus Tetean
Appl. Sci. 2025, 15(1), 290; https://doi.org/10.3390/app15010290 - 31 Dec 2024
Cited by 3 | Viewed by 1034
Abstract
Co1−xMnxFe2O4 nanoparticles (0 ≤ x ≤ 1) have been prepared via the hydrothermal method. The prepared samples were studied using X-ray diffraction measurements (XRD), transmission electron microscopy (TEM), Raman spectroscopy, and magnetic measurements. All studied [...] Read more.
Co1−xMnxFe2O4 nanoparticles (0 ≤ x ≤ 1) have been prepared via the hydrothermal method. The prepared samples were studied using X-ray diffraction measurements (XRD), transmission electron microscopy (TEM), Raman spectroscopy, and magnetic measurements. All studied samples were found to be single phases and to have a cubic Fd-3m structure. The average crystalline sizes are between 7.8 and 15 nm. EDS analysis confirmed the presence of cobalt, manganese, iron, and oxygen in all prepared samples. It was found by Raman spectroscopy that Fe3+ would be placed on octahedral sites while Fe2+ would, in turn, be displaced to tetrahedral sites while Mn ions will be placed on both sites. Both Mn2+ and Mn4+ are present in studied ferrites. The experimental saturation magnetizations for doped samples are much higher when compared with previous reports, reaching values between 3.71 and 6.7 μB/f.u. The doping with Mn in nanocrystalline cobalt ferrite enhanced the magnetic properties due to changes in the cation distribution between the two sublattices. The higher magnetic moments are explained by the presence of Mn4+ ions located preferentially on tetrahedral sites while Mn2+ prefer octahedral sites, and by the high quality and crystallinity of our samples the nanoparticles being almost monodomain. Large values of the coercive field were found at 4.2 K while the hysteresis is almost absent in all investigated samples at room temperature. Full article
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15 pages, 8449 KiB  
Article
Hard–Soft Core–Shell Architecture Formation from Cubic Cobalt Ferrite Nanoparticles
by Marco Sanna Angotzi, Valentina Mameli, Dominika Zákutná, Fausto Secci, Huolin L. Xin and Carla Cannas
Nanomaterials 2023, 13(10), 1679; https://doi.org/10.3390/nano13101679 - 19 May 2023
Cited by 4 | Viewed by 2119
Abstract
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 [...] Read more.
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. Full article
(This article belongs to the Special Issue Morphological Design and Synthesis of Nanoparticles)
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16 pages, 2310 KiB  
Article
Saturation of Specific Absorption Rate for Soft and Hard Spinel Ferrite Nanoparticles Synthesized by Polyol Process
by Cristian Iacovita, Gabriela Fabiola Stiufiuc, Roxana Dudric, Nicoleta Vedeanu, Romulus Tetean, Rares Ionut Stiufiuc and Constantin Mihai Lucaciu
Magnetochemistry 2020, 6(2), 23; https://doi.org/10.3390/magnetochemistry6020023 - 29 May 2020
Cited by 42 | Viewed by 5299
Abstract
Spinel ferrite nanoparticles represent a class of magnetic nanoparticles (MNPs) with enormous potential in magnetic hyperthermia. In this study, we investigated the magnetic and heating properties of spinel soft NiFe2O4, MnFe2O4, and hard CoFe2 [...] Read more.
Spinel ferrite nanoparticles represent a class of magnetic nanoparticles (MNPs) with enormous potential in magnetic hyperthermia. In this study, we investigated the magnetic and heating properties of spinel soft NiFe2O4, MnFe2O4, and hard CoFe2O4 MNPs of comparable sizes (12–14 nm) synthesized by the polyol method. Similar to the hard ferrite, which predominantly is ferromagnetic at room temperature, the soft ferrite MNPs display a non-negligible coercivity (9–11 kA/m) arising from the strong interparticle interactions. The heating capabilities of ferrite MNPs were evaluated in aqueous media at concentrations between 4 and 1 mg/mL under alternating magnetic fields (AMF) amplitude from 5 to 65 kA/m at a constant frequency of 355 kHz. The hyperthermia data revealed that the SAR values deviate from the quadratic dependence on the AMF amplitude in all three cases in disagreement with the Linear Response Theory. Instead, the SAR values display a sigmoidal dependence on the AMF amplitude, with a maximum heating performance measured for the cobalt ferrites (1780 W/gFe+Co), followed by the manganese ferrites (835 W/gFe+Mn), while the nickel ferrites (540 W/gFe+Ni) present the lowest values of SAR. The heating performances of the ferrites are in agreement with their values of coercivity and saturation magnetization. Full article
(This article belongs to the Special Issue Magnetic Nanoparticles 2020)
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20 pages, 8716 KiB  
Article
Thermal Condensation of Glycine and Alanine on Metal Ferrite Surface: Primitive Peptide Bond Formation Scenario
by Md. Asif Iqubal, Rachana Sharma, Sohan Jheeta and Kamaluddin
Life 2017, 7(2), 15; https://doi.org/10.3390/life7020015 - 27 Mar 2017
Cited by 28 | Viewed by 10201
Abstract
The amino acid condensation reaction on a heterogeneous mineral surface has been regarded as one of the important pathways for peptide bond formation. Keeping this in view, we have studied the oligomerization of the simple amino acids, glycine and alanine, on nickel ferrite [...] Read more.
The amino acid condensation reaction on a heterogeneous mineral surface has been regarded as one of the important pathways for peptide bond formation. Keeping this in view, we have studied the oligomerization of the simple amino acids, glycine and alanine, on nickel ferrite (NiFe2O4), cobalt ferrite (CoFe2O4), copper ferrite (CuFe2O4), zinc ferrite (ZnFe2O4), and manganese ferrite (MnFe2O4) nanoparticles surfaces, in the temperature range from 50–120 °C for 1–35 days, without applying any wetting/drying cycles. Among the metal ferrites tested for their catalytic activity, NiFe2O4 produced the highest yield of products by oligomerizing glycine to the trimer level and alanine to the dimer level, whereas MnFe2O4 was the least efficient catalyst, producing the lowest yield of products, as well as shorter oligomers of amino acids under the same set of experimental conditions. It produced primarily diketopiperazine (Ala) with a trace amount of alanine dimer from alanine condensation, while glycine was oligomerized to the dimer level. The trend in product formation is in accordance with the surface area of the minerals used. A temperature as low as 50 °C can even favor peptide bond formation in the present study, which is important in the sense that the condensation process is highly feasible without any sort of localized heat that may originate from volcanoes or hydrothermal vents. However, at a high temperature of 120 °C, anhydrides of glycine and alanine formation are favored, while the optimum temperature for the highest yield of product formation was found to be 90 °C. Full article
(This article belongs to the Special Issue The Landscape of the Emergence of Life)
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