Articles de revues : « Ferrite magnetic nanoparticles »

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Swaminathan, R., J. Woods, S. Calvin, Joseph Huth et M. E. McHenry. « Microstructural Evolution Model of the Sintering Behaviour and Magnetic Properties of NiZn Ferrite Nanoparticles ». Advances in Science and Technology 45 (octobre 2006) : 2337–44. http://dx.doi.org/10.4028/www.scientific.net/ast.45.2337.

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The sintering of RF plasma synthesized NiZn ferrite nanoparticles was studied. The as-synthesized nanoparticles have been modeled as having a core-shell structure with richer Zn concentration on the surface. Most Zn cations occupy tetrahedral sites typical of zinc ferrites, while some of the Zn cations occupy tetrahedral sites in a (111) oriented surface layer in the form of ZnO. Ni and Fe cations show no evidence of such disorder and their positions are consistent with the bulk spinel structure. This core-shell structure evolves by decomposition of the as-synthesized nanoparticles into Ni-and Zn-rich ferrites followed by the decomposition of the Zn-rich ferrites into ZnO and -Fe2O3 during sintering of the nanoparticles. Within the core region, sintering causes Ni to exit the ferrite structure and be reduced to a metallic form, possibly via a NiO intermediate. The miscibility gap in the pseudo-binary ZnFe2O4/NiFe2O4 system was modeled using equilibrium solution data. Decomposition rates are interpreted considering inter-diffusion kinetics. Sintered nanoparticle compacts showed an evolution of a 4- phase mixture of ferrite + ZnO + -Fe2O3 + Ni with increasing sintering temperature. The average ferrite nanoparticle size is preserved up to very high sintering temperatures. These observations suggest that the ZnO shell contributes to the sintering process by surface diffusion while acting as a barrier to the growth of the ferrite core. Metal edge EXAFS patterns of the sintered compacts confirm that Fe transforms from a single ferrite phase into a mixture of -Fe2O3 and ferrite; ZnO content progressively increases with sintering temperature and elemental Ni evolves from the ferrite with increasing sintering temperature. The saturation magnetization and Curie temperature were observed to decrease as a function of sintering temperature, with an anomaly at the temperature where Ni starts to form. This is explained by Zn diffusing from the core depleting the ferrite and increasing the amount of non-magnetic ZnO in the shell. AC magnetic measurements also vary systematically with the microstructural evolution.

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Tambe, Sunanda, et R. Y. Borse. « Effects of Al Doping with Zinc Ferrite Nanoparticles on Structural, Magnetic and Dielectric Properties ». Material Science Research India 19, n^o 3 (30 décembre 2022) : 150–60. http://dx.doi.org/10.13005/msri/190306.

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Zinc ferrite nanoparticles have wide range of the applications in the field of Electronics, Optoelectronics, Magnetics, Solar cell, Photocatalysts. With Al doping we modify their structural, magnetic and electrical properties of zinc ferrite (ZnFe2O4). In the present studies, zinc ferrite nanoparticles were prepared by sol gel method using glycine as combustion agent. The effects of Al doping concentration on the structural, morphological, optical, magnetic and electrical properties of zinc ferrites were studied. In x-ray diffraction patterns analysis confirmed the formation of the cubic spinel structure. We characterise scanning electron microscopy (SEM) with energy dispersive X-ray (EDX) in the current work to examine the morphology of the nanomaterials. The UV-Vis optical investigation showed that Al+3 doping increased absorbance and significantly decreased energy band gap value (1.90 eV-2.01 eV). The magnetic properties of zinc ferrite NPs were studied by using vibrating samples magnetometer which showed samples of pure zinc ferrites and Al-doped zinc ferrite with paramgnetism. Dielectric properties were studied from impedance analyser. When aluminium concentration increases in the zinc ferrites, dielectric characteristic results were obtained in which dielectric constant (ɛ'), dielectric loss (ɛ'') and tangent loss decreased. Also when frequency increases above all three dielectric parameters remains stable at high frequency. The obtained results of pure and Al doped Zn ferrite are useful for high frequency applications.

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Andrade, Priscyla L., Valdeene A. J. Silva, Kathryn L. Krycka, Juscelino B. Leão, I.-Lin Liu, Maria P. C. Silva et J. Albino Aguiar. « The effect of organic coatings in the magnetization of CoFe₂O₄ nanoparticles ». AIP Advances 12, n^o 8 (1 août 2022) : 085102. http://dx.doi.org/10.1063/5.0078167.

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Cobalt ferrite has attracted considerable attention in recent years due to its unique physical properties, such as high Curie temperature, large magnetocrystalline anisotropy, high coercivity, moderate saturation magnetization, large magnetostrictive coefficient, and excellent chemical stability and mechanical hardness. This work focuses on the neutron scattering results of the magnetic response characteristics of polysaccharide fucan coated cobalt ferrite nanoparticles for their application as a solid support for enzyme immobilization and other biotechnology applications. Here, we unambiguously show that surfactant coating of nanoparticles can significantly affect their magnetic response throughout the nanoparticle volume. While it has been recently suggested that oleic acid may preserve nanoscale magnetism in ferrites, we present evidence that the influence of oleic acid on the magnetic response of CoFe2O4 nanoparticles is more than a surface effect, instead pervading throughout the interior of the nanoparticle.

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Al-Senani, Ghadah M., Foziah F. Al-Fawzan, Rasmiah S. Almufarij, Omar H. Abd-Elkader et Nasrallah M. Deraz. « Magnetic Behavior of Virgin and Lithiated NiFe2O4 Nanoparticles ». Crystals 13, n^o 1 (31 décembre 2022) : 69. http://dx.doi.org/10.3390/cryst13010069.

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A series of virgin and lithia-doped Ni ferrites was synthesized using egg-white-mediated combustion. Characterization of the investigated ferrites was performed using several techniques, specifically, X-ray Powder Diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and High-resolution transmission electron microscopy (HRTEM). XRD-based structural parameters were determined. A closer look at these characteristics reveals that lithia doping enhanced the nickel ferrite lattice constant (a), unit cell volume (V), stress (ε), microstrain (σ), and dislocation density (δ). It also enhanced the separation between magnetic ions (LA and LB), ionic radii (rA, rB), and bond lengths (A-O and B-O) between tetrahedral (A) and octahedral (B) locations. Furthermore, it enhanced the X-ray density (Dx) and crystallite size (d) of random spinel nickel ferrite displaying opposing patterns of behavior. FTIR-based functional groups of random spinel nickel ferrite were determined. HRTEM-based morphological properties of the synthesized ferrite were investigated. These characteristics of NiFe2O4 particles, such as their size, shape, and crystallinity, demonstrate that these manufactured particles are present at the nanoscale and that lithia doping caused shape modification of the particles. Additionally, the prepared ferrite’s surface area and total pore volume marginally increased after being treated with lithia, depending on the visibility of the grain boundaries. Last, but not least, as the dopant content was increased through a variety of methods, the magnetization of virgin nickel ferrite fell with a corresponding increase in coercivity. Uniaxial anisotropy, rather than cubic anisotropy, and antisite and cation excess defects developed in virgin and lithia-doped nickel ferrites because the squareness ratio (Mr/Ms) was less than 0.5. Small squareness values strongly recommend using the assessed ferrites in high-frequency applications.

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Dhariwal, Jyoti, Ravina Yadav, Sheetal Yadav, Anshu Kumar Sinha, Chandra Mohan Srivastava, Gyandshwar Kumar Rao, Manish Srivastava et al. « Magnetic Spinel Ferrite : An Efficient, Reusable Nano Catalyst for HMFsynthesis ». Current Catalysis 10, n^o 3 (décembre 2021) : 206–13. http://dx.doi.org/10.2174/2211544710666211119094247.

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Aim: In the present work, the preparation and catalytic activity of spinel ferrite (MFe2O4; M = Fe, Mn, Co, Cu, Ni) nanoparticles to synthesize 5-hydroxymethylfurfural (HMF) have been discussed. Background: Ferrites possess unique physicochemical properties, including excellent magnetic characteristics, high specific surface area, active surface sites, high chemical stability, tunable shape and size, and easy functionalization. These properties make them essential heterogeneous catalysts in many organic reactions. Objective: This study aims to synthesize a series of transition metal ferrite nanoparticles and use them in the dehydration of carbohydrates for 5-hydroxymethylfurfural (HMF) synthesis. Method: The ferrite nanoparticles were prepared via the co-precipitation method, and PXRD confirmed their phase stability. The surface area and the crystallite size of the nanoparticles were calculated using BET and PXRD, respectively. Result: The easily prepared heterogeneous nanocatalyst showed a significant catalytic performance, and among all spinel ferrites, CuFe2O4 revealed maximum catalytic ability. Conclusion: Being a heterogeneous catalyst and magnetic in nature, ferrite nanoparticles were easily recovered by using an external magnet and reused up to several runs without substantial loss in catalytic activity. Others: HMF was synthesized from fructose in a good yield of 71%.

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Petrova, Elena G., Yana A. Shavshukova, Dzmitry A. Kotsikau, Kazimir I. Yanushkevich, Konstantin V. Laznev et Vladimir V. Pankov. « Thermolysis of sprayed suspensions for obtaining highly spinel ferrite nanoparticles ». Journal of the Belarusian State University. Chemistry, n^o 1 (21 février 2019) : 14–21. http://dx.doi.org/10.33581/2520-257x-2019-1-14-21.

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Thermal treatment of ferrite magnetic nanoparticles in NaCl matrix gives an opportunity to increase their specific magnetization with preservation of nanoscale size. Composite materials based on mixed ferrites Co0.65Zn0.35Fe2O4 and Mg 0.5Zn0.5Fe2O4 were synthesized by spray-drying of aqueous suspensions in presence of NaCl and annealed at 300 –900 °C. The microstructure and phase composition of nanoparticles before and after annealing were studied by scanning and transmission electron microscopy (SEM and TEM), X-ray diffraction analysis and IR spectroscopy. The magnetic properties of nanoparticles were estimated using a ponderomotive method of measuring the specific magneti zation at room temperature in a magnetic field with an induction of 0.86 T. The increase of the annealing temperature up to 900 °C was established to lead to the increase in the specific magnetization of ferrites – from 32.79 to 91.3 emu/g (Co0.65Zn0.35Fe2O4) and from 2.76 to 22.31 emu/g (Mg 0.5 Zn 0.5Fe2O4) due to recrystallization processes and increase of crystallinity degree of the ferrites. Due to the NaCl insulating layer, the particle size increases just slightly (from ~ 10 nm before annealing to ~ 60 nm after annealing at 900 °C). This method is effective for substantial increase in specific magnetization of ferrite nanoparticles with preservation of their nanoscale size.

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JIAO, QIGANG, YI ZHANG, YA ZHAI, XIAOJUN BAI, WEI ZHANG, JUN DU et HONGRU ZHAI. « MAGNETIC PROPERTIES AND INDUCTION HEATING OF NiZn FERRITE NANOPARTICLES ». Modern Physics Letters B 22, n^o 15 (20 juin 2008) : 1497–505. http://dx.doi.org/10.1142/s0217984908016212.

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A series of nanoparticle powders of Ni x Zn 1-x Fe 2 O 4 (x = 0, 0.30, 0.40, 0.50, 0.55, 0.60, 0.70 and 1.0) ferrites was synthesized by the refluxing method at relatively low temperatures. The average size of nanoparticles is about 20 nm. The magnetic properties and induction heating behavior were investigated. On increasing the Ni content, x, from 0 to 0.50, the saturation magnetization and permeability increased, and then decreased with further increasing Ni content with the bulk Ni – Zn ferrite. The maximum value of magnetization was about 50 emu/g near x = 0.50, where the induction heating rate and induction heating final temperature of the ferrite-water suspension also showed maximum values. The specific absorption rate obtained from the initial induction heating rate curve was found to be linearly proportional to the square of the alternating magnetic field, which is roughly consistent with the theoretical power loss of magnetic materials in the alternating field.

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Andrade, Raquel G. D., Sérgio R. S. Veloso et Elisabete M. S. Castanheira. « Shape Anisotropic Iron Oxide-Based Magnetic Nanoparticles : Synthesis and Biomedical Applications ». International Journal of Molecular Sciences 21, n^o 7 (1 avril 2020) : 2455. http://dx.doi.org/10.3390/ijms21072455.

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Research on iron oxide-based magnetic nanoparticles and their clinical use has been, so far, mainly focused on the spherical shape. However, efforts have been made to develop synthetic routes that produce different anisotropic shapes not only in magnetite nanoparticles, but also in other ferrites, as their magnetic behavior and biological activity can be improved by controlling the shape. Ferrite nanoparticles show several properties that arise from finite-size and surface effects, like high magnetization and superparamagnetism, which make them interesting for use in nanomedicine. Herein, we show recent developments on the synthesis of anisotropic ferrite nanoparticles and the importance of shape-dependent properties for biomedical applications, such as magnetic drug delivery, magnetic hyperthermia and magnetic resonance imaging. A brief discussion on toxicity of iron oxide nanoparticles is also included.

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Iacovita, Cristian, Gabriela Fabiola Stiufiuc, Roxana Dudric, Nicoleta Vedeanu, Romulus Tetean, Rares Ionut Stiufiuc et Constantin Mihai Lucaciu. « Saturation of Specific Absorption Rate for Soft and Hard Spinel Ferrite Nanoparticles Synthesized by Polyol Process ». Magnetochemistry 6, n^o 2 (29 mai 2020) : 23. http://dx.doi.org/10.3390/magnetochemistry6020023.

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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.

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Alzoubi, Gassem M. « The Effect of Co-Doping on the Structural and Magnetic Properties of Single-Domain Crystalline Copper Ferrite Nanoparticles ». Magnetochemistry 8, n^o 12 (22 novembre 2022) : 164. http://dx.doi.org/10.3390/magnetochemistry8120164.

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Nanoparticles of Co-doped copper ferrite, Cu0.75Co0.25Fe2O4, were successfully synthesized by hydrothermal method. The preparation conditions were optimized to produce small nanoparticles with crystallite size of 20 nm that fall into the single-domain regime. The influence of Co-doping on the structure and magnetic properties of pure copper ferrite, CuFe2O4, was investigated. The prepared ferrite nanoparticles were found to be in a single structural phase with a spinel-type structure, according to the XRD and FT-IR measurements. When compared to pure Cu ferrite, the addition of Co increased the lattice constant and decreased the density. The TEM results confirmed the spherical morphology of the prepared ferrite nanoparticles. For the entire temperature range of the ferrite nanoparticles, the magnetization measurements showed a single ferrimagnetic phase. It was observed that the coercivity and remanent magnetization increased with decreasing temperature. Magnetic anisotropy was found to increase with Co-doping in comparison to pure Cu ferrite. The ZFC–FC magnetization curves showed that the blocking temperature (TB) of the prepared nanoparticles is above room temperature, demonstrating that they are ferrimagnetic at room temperature and below. Additionally, it was found that decreasing the magnetic field lowers TB. The FC curves below TB were observed to be nearly flat, indicating spin-glass behavior that might be attributed to nanoparticle interactions and/or surface effects such as spin canting and spin disorder.

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Gupta, Priyanka, Dr Ravi Kumar Vijai et Subhash Chander. « Synthesis, Characterization and Magnetic properties of Nanoparticles of Cobalt Doped Ferrite ». International Journal of Chemistry, Mathematics and Physics 6, n^o 5 (2022) : 06–11. http://dx.doi.org/10.22161/ijcmp.6.5.2.

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Ferrites are ceramic like material having magnetic properties which are being utilized for several applications. Cobalt ferrites are hard magnetic material with high coercivity. In our study Crystalline, Magnetic nanoparticles of Cobalt ferrite Co0.8Fe2.2O4 were synthesized by Sol Gel Method using ferric chloride and cobalt nitrate with NaOH as a reactant. Structural characteristics of samples were determined by X-Ray diffraction, FESEM and TEM. Particle size found 14.26nm by using Debye Scherrer method. Scanning electron microscopic (SEM) studies revealed nano-crystalline nature of the sample. AFM showed surface roughness. Magnetic properties were investigated using VSM (vibrating sample magnetometer). Various magnetic parameters such as saturation magnetization (Ms) and remanence (Mr) and coercivity (Hc) are obtained from the hysteresis loops. The calculated value of saturation magnetization in our study for Cobalt ferrite was found lower than the value reported for the bulk. The coercivity was found very high which indicate that the nanoparticles exhibit ferromagnetic behavior.

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Fernandes, Ricardo J. C., Carlos A. B. Magalhães, Ana Rita O. Rodrigues, Bernardo G. Almeida, Ana Pires, André Miguel Pereira, João Pedro Araujo, Elisabete M. S. Castanheira et Paulo J. G. Coutinho. « Photodeposition of Silver on Zinc/Calcium Ferrite Nanoparticles : A Contribution to Efficient Effluent Remediation and Catalyst Reutilization ». Nanomaterials 11, n^o 4 (24 mars 2021) : 831. http://dx.doi.org/10.3390/nano11040831.

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The efficient photodegradation of textile dyes is still a challenge, especially considering resistant azo dyes. In this work, zinc/calcium mixed ferrite nanoparticles prepared by the sol–gel method were coupled with silver by a photodeposition method to enhance the photocatalytic potency. The obtained zinc/calcium ferrites are mainly cubic-shaped nanoparticles sized 15 ± 2 nm determined from TEM and XRD and an optical bandgap of 1.6 eV. Magnetic measurements indicate a superparamagnetic behavior with saturation magnetizations of 44.22 emu/g and 27.97 emu/g, respectively, for Zn/Ca ferrite and Zn/Ca ferrite with photodeposited silver. The zinc/calcium ferrite nanoparticles with photodeposited silver showed efficient photodegradation of the textile azo dyes C.I. Reactive Blue 250 and C.I. Reactive Yellow 145. Subsequent cycles of the use of the photocatalyst indicate the possibility of magnetic recovery and reutilization without a significant loss of efficiency.

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Rostamzadehmansoor, S., Mirabdullah Seyed Sadjadi, K. Zare et Nazanin Farhadyar. « Preparation of Ferromagnetic Manganese Doped Cobalt Ferrite-Silica Core Shell Nanoparticles for Possible Biological Application ». Defect and Diffusion Forum 334-335 (février 2013) : 19–25. http://dx.doi.org/10.4028/www.scientific.net/ddf.334-335.19.

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Magnetic oxide nanoparticles with proper surface coatings are increasingly being evaluated for clinical applications such as hyperthermia, drug delivery, magnetic resonance imaging, transfection and cell/protein separations. In this work, we investigated synthesis, magnetic properties of silica coated metal ferrite, (CoFe2O4)/SiO2 and manganese doped cobalt ferrite nanoparticles (Mnx-Co1-xFe2O4 with x = 0.02, 0.04 and 0.06)/SiO2 for possible biomedical application. All the ferrites nanoparticles were prepared by co-precipitation method using FeCl3.6H2O, CoCl2.6H2O and MnCl2.2H2O as precursors, and were silica coated by the Stober process in directly ethanol. The composition, phase structure and morphology of the prepared core/shell cobalt ferrites nanostructures were characterized by powder X-ray diffraction (XRD), Fourier Transform infra-red spectra (FTIR), Field Emission Scanning Electron Microscopy and energy dispersive X-ray analysis (FESEM-EDAX). The results revealed that all the samples maintain the ferrite spinel structure. While, the cell parameters decrease monotonically by increase of Mn content indicating that the Mn ions are substituted into the lattice of CoFe2O4. The magnetic properties of the prepared samples were investigated at room temperature using Vibrating Sample Magnetometer (VSM). The results revealed a strong dependence of room temperature magnetic properties on (1) doping content, x; (2) particle size and ion distributions.

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Je, Hae June, et Byung Kook Kim. « Magnetic Properties of Mn-Zn Ferrite Nanoparticles Fabricated by Conventional Ball-Milling ». Solid State Phenomena 124-126 (juin 2007) : 891–94. http://dx.doi.org/10.4028/www.scientific.net/ssp.124-126.891.

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Mn-Zn ferrite nanoparticles were fabricated via conventional ball-milling and their magnetic properties were investigated. By ball-milling of Mn0.53Zn0.42Fe2.05O4 agglomerates for 48h with and without a dispersant (Darvan-C (ammonium polymethacrylate)), nanoparticles having average particle size of 60 nm were obtained. The saturation magnetizations (Ms) of thus obtained Mn-Zn ferrite nanoparticles were 49 and 62 emu/g for dispersant-added and dispersant-non-added one, respectively. When the nanoparticles were heat-treated at 400, however, the Ms became comparable: 63 and 65 emu/g. When the nanoparticles were heat-treated at 600, moreover, the Ms became comparable with that of bulk ferrites: 75~78 emu/g. These magnetic properties were attributed to the surface spin disorder effects resulting from the coating of organic dispersant molecules on the surfaces of the nanoparticles as well the structural disorder on the surfaces the nanoparticles.

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Amirov, Abdulkarim, Alexander Omelyanchik, Dmitry Murzin, Valeria Kolesnikova, Stanislav Vorontsov, Ismel Musov, Khasan Musov, Svetlana Khashirova et Valeria Rodionova. « 3D Printing of PLA/Magnetic Ferrite Composites : Effect of Filler Particles on Magnetic Properties of Filament ». Processes 10, n^o 11 (16 novembre 2022) : 2412. http://dx.doi.org/10.3390/pr10112412.

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Three-dimensional printing is one of the most promising areas of additive manufacturing with a constantly growing range of applications. One of the current tasks is the development of new functional materials that would allow the manufacture of objects with defined magnetic, electrical, and other properties. In this work, composite magnetic filaments for 3D printing with tunable magnetic properties were produced from polylactic acid thermoplastic polymer with the addition of magnetic ferrite particles of different size and chemical composition. The used magnetic particles were cobalt ferrite CoFe2O4 nanoparticles, a mixture of CoFe2O4 and zinc-substituted cobalt ferrite Zn0.3Co0.7Fe2O4 nanoparticles (~20 nm), and barium hexaferrite BaFe12O19 microparticles (<40 µm). The maximum coercivity field HC = 1.6 ± 0.1 kOe was found for the filament sample with the inclusion of 5 wt.% barium hexaferrite microparticles, and the minimum HC was for a filament with a mixture of cobalt and zinc–cobalt spinel ferrites. Capabilities of the FDM 3D printing method to produce parts having simple (ring) and complex geometric shapes (honeycomb structures) with the magnetic composite filament were demonstrated.

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Khizar, Sumera, Nasir M. Ahmad, Naveed Ahmed, Sadia Manzoor, Muhammad A. Hamayun, Nauman Naseer, Michele K. L. Tenório, Noureddine Lebaz et Abdelhamid Elaissari. « Aminodextran Coated CoFe2O4 Nanoparticles for Combined Magnetic Resonance Imaging and Hyperthermia ». Nanomaterials 10, n^o 11 (2 novembre 2020) : 2182. http://dx.doi.org/10.3390/nano10112182.

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Aminodextran (AMD) coated magnetic cobalt ferrite nanoparticles are synthesized via electrostatic adsorption of aminodextran onto magnetic nanoparticles and their potential theranostic application is evaluated. The uncoated and aminodextran-coated nanoparticles are characterized to determine their hydrodynamic size, morphology, chemical composition, zeta potential and magnetization. The aminodextran containing cobalt ferrite nanoparticles of nanometer size are positively charged in the pH range from 3 to 9 and exhibit saturation magnetization of 50 emu/g. The magnetic resonance imaging (MRI) indicates capability for diagnostics and a reduction in intensity with an increase in nanoparticle amount. The hyperthermia capability of the prepared particles shows their potential to generate suitable local heat for therapeutic purposes. There is a rise of 7 °C and 9 °C at 327 kHz and 981 kHz respectively and specific absorption rates (SAR) of aminodextran-coated nanoparticles are calculated to be 259 W/g and 518 W/g at the given frequencies larger than uncoated nanoparticles (0.02 W/g). The development of novel aminodextran coated magnetic cobalt ferrite nanoparticles has significant potential to enable and improve personalized therapy regimens, targeted cancer therapies and ultimately to overcome the prevalence of nonessential and overdosing of healthy tissues and organs.

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Al-Khabouri, Saja, Salim Al-Harthi, Toru Maekawa, Mohamed E. Elzain, Ashraf Al-Hinai, Ahmed D. Al-Rawas, Abbsher M. Gismelseed, Ali A. Yousif et Myo Tay Zar Myint. « Free and partially encapsulated manganese ferrite nanoparticles in multiwall carbon nanotubes ». Beilstein Journal of Nanotechnology 11 (29 décembre 2020) : 1891–904. http://dx.doi.org/10.3762/bjnano.11.170.

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Free and partially encapsulated manganese ferrite (MnFe2O4) nanoparticles are synthesized and characterized regarding structure, surface, and electronic and magnetic properties. The preparation method of partially encapsulated manganese ferrite enables the formation of a hybrid nanoparticle/tube system, which exhibits properties of manganese ferrite nanoparticles inside and attached to the external surface of the tubes. The effect of having manganese ferrite nanoparticles inside the tubes is observed as a shift in the X-ray diffraction peaks and as an increase in stress, hyperfine field, and coercivity when compared to free manganese ferrite nanoparticles. On the other hand, a strong charge transfer from the multiwall carbon nanotubes is attributed to the attachment of manganese ferrite nanoparticles outside the tubes, which is detected by a significant decrease in the σ band emission of the ultraviolet photoemission spectroscopy signal. This is followed by an increase in the density of states at the Fermi level of the attached manganese ferrite nanoparticles in comparison to free manganese ferrite nanoparticles, which leads to an enhancement of the metallic properties.

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Alotaibi, M. A., I. Ud Din, A. I. Alharthi, P. Ahmad, A. Naeem, I. A. ElSayed et G. Centi. « Synthesis, Characterization, and Magnetic Behavior of Cobalt-Ferrite Nanoparticles under Variant Temperature Conditions ». Физика твердого тела 63, n^o 4 (2021) : 513. http://dx.doi.org/10.21883/ftt.2021.04.50746.pss109.

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Wet chemical method was applied for the synthesis of cobalt-ferrite nanoparticles. The physicochemical properties were investigated by number of analytical techniques. TGA revealed the thermal stability of synthesized cobalt-ferrite nanoparticles. X-ray diffraction studies displayed the nanoparticles crystalline nature. Structure of cobalt-ferrite nanoparticles was confirmed via infrared spectroscopy by manifesting Co and Fe ions absorption peaks. Morphological studies showed synthesis of nanoparticles of cobalt-ferrite by employing field emissions scanning electron microscopy. The magnetic properties of cobalt-ferrite nanoparticles were investigated by vibrating sample magnetometer (VSM). The X-ray photoelectron spectroscopy studies confirmed the synthesis of cobalt-ferrite by displaying the oxidation of Co as Co2+ and Fe as Fe3+, respectively. The VSM results revealed that the magnetic characteristics of cobalt-ferrite nanoparticles were completely changed by the variation of temperature. Keywords: ferrite nanoparticles, VSM, temperature effect, magneton number, anisotropy constant.

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Alotaibi, M. A., I. Ud Din, A. I. Alharthi, P. Ahmad, A. Naeem, I. A. ElSayed et G. Centi. « Synthesis, Characterization, and Magnetic Behavior of Cobalt-Ferrite Nanoparticles under Variant Temperature Conditions ». Физика твердого тела 63, n^o 4 (2021) : 513. http://dx.doi.org/10.21883/ftt.2021.04.50746.pss109.

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Wet chemical method was applied for the synthesis of cobalt-ferrite nanoparticles. The physicochemical properties were investigated by number of analytical techniques. TGA revealed the thermal stability of synthesized cobalt-ferrite nanoparticles. X-ray diffraction studies displayed the nanoparticles crystalline nature. Structure of cobalt-ferrite nanoparticles was confirmed via infrared spectroscopy by manifesting Co and Fe ions absorption peaks. Morphological studies showed synthesis of nanoparticles of cobalt-ferrite by employing field emissions scanning electron microscopy. The magnetic properties of cobalt-ferrite nanoparticles were investigated by vibrating sample magnetometer (VSM). The X-ray photoelectron spectroscopy studies confirmed the synthesis of cobalt-ferrite by displaying the oxidation of Co as Co2+ and Fe as Fe3+, respectively. The VSM results revealed that the magnetic characteristics of cobalt-ferrite nanoparticles were completely changed by the variation of temperature. Keywords: ferrite nanoparticles, VSM, temperature effect, magneton number, anisotropy constant.

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Habib, Shaimaa A., Samia A. Saafan, Talaat M. Meaz, Moustafa A. Darwish, Di Zhou, Mayeen U. Khandaker, Mohammad A. Islam et al. « Structural, Magnetic, and AC Measurements of Nanoferrites/Graphene Composites ». Nanomaterials 12, n^o 6 (11 mars 2022) : 931. http://dx.doi.org/10.3390/nano12060931.

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As a contribution to the graphene-based nanoferrite composites, this article is intended to present Mn, Co, and Co-Mn nanoferrites for the preparation and investigation of such samples. Nanoparticles of Co ferrite, Mn ferrite, and Co-Mn ferrite were chemically synthesized by the coprecipitation method. The composites of ferrite/graphene were made by incorporating weight ratios of 25% graphene to 75% ferrite. Various structural and characterizing investigations of ferrite samples and ferrite/graphene composites were performed, including XRD, EDX, SEM, VSM hysteresis loops, AC conductivity, and dielectric behavior. The investigations ensured the formation of the intended nanoferrite powders, each having a single-phase crystal structure with no undesired phases or elements. All samples exhibit a soft magnetic behavior. They show a semiconducting behavior of AC electrical conductivity as well. This was proved by the temperature dependence of the AC’s electrical conductivity. Whereas the dielectric function and loss tangent show an expected, well-explained behavior, the ferrite/graphene composite samples have lower saturation magnetization values, lower AC conductivity, and dielectric constant values than the pure ferrites but still have the same behavior trends as those of the pure ferrites. The values obtained may represent steps on developing new materials for expected applications, such as manufacturing supercapacitors and/or improved battery electrodes.

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Lin, Wenbin, Taeghwan Hyeon, Gregory M. Lanza, Miqin Zhang et Thomas J. Meade. « Magnetic Nanoparticles for Early Detection of Cancer by Magnetic Resonance Imaging ». MRS Bulletin 34, n^o 6 (juin 2009) : 441–48. http://dx.doi.org/10.1557/mrs2009.120.

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AbstractThis article provides a brief overview of recent progress in the synthesis and functionalization of magnetic nanoparticles and their applications in the early detection of malignant tumors by magnetic resonance imaging (MRI). The intrinsic low sensitivity of MRI necessitates the use of large quantities of exogenous contrast agents in many imaging studies. Magnetic nanoparticles have recently emerged as highly efficient MRI contrast agents because these nanometer-scale materials can carry high payloads while maintaining the ability to move through physiological systems. Superparamagnetic ferrite nanoparticles (such as iron oxide) provide excellent negative contrast enhancement. Recent refinement of synthetic methodologies has led to ferrite nanoparticles with narrow size distributions and high crystallinity. Target-specific tumor imaging becomes possible through functionalization of ferrite nanoparticles with targeting agents to allow for site-specific accumulation. Nanoparticulate contrast agents capable of positive contrast enhancement have recently been developed in order to overcome the drawbacks of negative contrast enhancement afforded by ferrite nanoparticles. These newly developed magnetic nanoparticles have the potential to enable physicians to diagnose cancer at the earliest stage possible and thus can have an enormous impact on more effective cancer treatment.

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Yahya, Noorhana, Muhammad Kashif, Nadeem Nasir, Majid Niaz Akhtar et Noorasikin Mohd Yusof. « Cobalt Ferrite Nanoparticles : An Innovative Approach for Enhanced Oil Recovery Application ». Journal of Nano Research 17 (février 2012) : 115–26. http://dx.doi.org/10.4028/www.scientific.net/jnanor.17.115.

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This Paper Describes the Synthesis of Cobalt Ferrite (CoFe2O4) Nanoparticles and their Application in Enhanced Oil Recovery. Cobalt Ferrite (CoFe2O4) Nanoparticles Were Used as Ferrite Magnetic Feeders with Antenna to Improve the Magnetic Field Strength and Cobalt Ferrite Nanofluid to Improve Oil Recovery. Cobalt Ferrite (CoFe2O4) Nanoparticles Were Synthesized by Sol-Gel Method. these Nanoparticles Were then Characterized by Using X-Ray Diffractometer (XRD) and Field Emission Scanning Electron Microscope (FESEM). Cobalt Ferrite Nanoparticles Annealed at 600oC, the Particle Size Is 51.17nm and 26nm as Determined by XRD and FESEM, Respectively while for the Sample Annealed at 800oC, the Particle Size Is 62nm as Determined by XRD and 60 Nm as Determined by FESEM. Magnetic Measurement Results Show that Initial Permeability of Cobalt Ferrite Powder Increased and Relative Loss Factor Decreased at High Frequency. in Order to Improve the Oil Recovery, Nanoparticles Were Used in Two Different Experiments. in the First Experiment, Nanoparticles Were Used as Magnetic Feeders with an Antenna to Improve the Magnetic Field Strength. in the Second Experiment, Nanoparticles Were Used as Nanofluids. Results Show that the Antenna with Magnetic Feeders Increases the Magnetic Field Strength by 0.94% as Compared to Antenna without Magnetic Feeders in the Water, and by 5.90% in the Air. Magnitude versus Offset (MVO) Study of Antenna with Magnetic Feeders Shows an Increase in Magnetic Field Strength of 275% as Compared to Antenna without Magnetic Feeders. it Is Found that Antenna with Magnetic Feeders Was Able to Recover 29.50% and 20.82% of Original Oil in Place (OOIP) in Core Rock Samples A-1 and A-2 Respectively. the Use of Cobalt Ferrite Nanoparticles as a Nanofluid with Electromagnetic Waves Yielded a Higher Recovery of Residual Oil in Place (ROIP) which Is 31.58% as Compared to 8.70% when it Was Used as Nanofluid Alone. it Is Investigated that due to Absorption of Electromagnetic Waves by Cobalt Ferrite Nanoparticles the Oil Viscosity Reduces which Increase the Oil Recovery. it Can Be Concluded that the Synthesised Cobalt Ferrite (CoFe2O4) Nanoparticles Can Be Potentially Used for Enhanced Oil Recovery in Future.

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Alzoubi, Gassem M. « Observation of Spin-Glass-like Behavior over a Wide Temperature Range in Single-Domain Nickel-Substituted Cobalt Ferrite Nanoparticles ». Nanomaterials 12, n^o 7 (28 mars 2022) : 1113. http://dx.doi.org/10.3390/nano12071113.

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In this study, single-domain NixCo1−xFe2O4 ferrite nanoparticles with 0≤x≤1 were hydrothermally prepared and characterized using X-ray diffraction, transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), and vibrating sample magnetometry. According to the Rietveld refinement results, all of the prepared nanoparticles were single phase with spinel-type structures. Increasing the Ni content increased the average crystallite size and X-ray density while decreasing the lattice constant. According to the TEM observations, the nanoparticles were spherical in shape. The formation of a single-phase spinel structure with two lattices centered at tetrahedral and octahedral sites was confirmed by the observation of two absorption bands in all FT-IR spectra. Magnetization data showed that the prepared nanoparticles of all compositions were ferrimagnetic across the entire temperature range of 300 K to 10 K. Magnetic properties such as saturation magnetization, remanent magnetization, coercivity, magnetic anisotropy, and magnetic moments per unit cell were found to decrease with increasing Ni content. The big difference in Hc of the x = 0, 0.25, 0.5, 0.75 ferrites between 300 K and 10 K suggested that these ferrite nanoparticles are truly single-domain nanoparticles. The small value of Hc of the NiFe2O4(x=1) ferrite and its very weak temperature dependence suggested that this sample is in a multi-domain regime. The ZFC–FC curves revealed the existence of spin-glass-like behavior in these ferrite nanoparticles over the entire temperature range.

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Gazeau, F., J. C. Bacri, F. Gendron, R. Perzynski, Yu L. Raikher, V. I. Stepanov et E. Dubois. « Magnetic resonance of ferrite nanoparticles : ». Journal of Magnetism and Magnetic Materials 186, n^o 1-2 (juillet 1998) : 175–87. http://dx.doi.org/10.1016/s0304-8853(98)00080-8.

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Tamboli, Qudsiya Y., Sunil M. Patange, Yugal Kishore Mohanta, Rohit Sharma et Kranti R. Zakde. « Green Synthesis of Cobalt Ferrite Nanoparticles : An Emerging Material for Environmental and Biomedical Applications ». Journal of Nanomaterials 2023 (6 février 2023) : 1–15. http://dx.doi.org/10.1155/2023/9770212.

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Research and utilization of nanotechnology are growing exponentially in every aspect of life. The constant growth of applications for magnetic nanoparticles, specifically nanoferrites, attracted many researchers. Among them, nanocobalt ferrite is the most crucial and studied magnetic nanoparticle. Environmentally benign synthetic methods became necessary to minimize environmental and occupational hazards. Green synthesis approaches in science and technology are now widely applied in the synthesis of nanomaterials. Herein, we reviewed recent advances in synthesizing nanocobalt ferrites and their composites using various scientific search engines. Subsequently, various applications were discussed, such as environmental (treatment of water/wastewater, photocatalytic degradation of dyes, and nanosorbent for environmental remediation) and biomedical (nanobiosensors for cancer diagnosis at the primary stage, effective targeted drug delivery, magnetic resonance imaging, hyperthermia, and potential drug candidates against cancer and microbial infections). This review offers comprehensive knowledge on how to choose appropriate natural resources for the green synthesis of nanocobalt ferrite and the benefits of this approach compared to conventional methods.

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Fernandes, Ricardo J. C., Carlos A. B. Magalhães, Carlos O. Amorim, Vítor S. Amaral, Bernardo G. Almeida, Elisabete M. S. Castanheira et Paulo J. G. Coutinho. « Magnetic Nanoparticles of Zinc/Calcium Ferrite Decorated with Silver for Photodegradation of Dyes ». Materials 12, n^o 21 (31 octobre 2019) : 3582. http://dx.doi.org/10.3390/ma12213582.

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Magnetic nanoparticles of zinc/calcium ferrite and decorated with silver were prepared by coprecipitation method. The obtained nanoparticles were characterized by UV/Visible absorption, XRD, TEM and SQUID. The mixed zinc/calcium ferrites exhibit an optical band gap of 1.78 eV. HR-TEM imaging showed rectangular nanoplate shapes with sizes of 10 ± 3 nm and aspect ratio mainly between 1 and 1.5. Magnetic measurements indicated a superparamagnetic behavior. XRD diffractograms allowed a size estimation of 4 nm, which was associated with the nanoplate thickness. The silver-decorated zinc/calcium ferrite nanoparticles were successfully employed in the photodegradation of a model dye (Rhodamine B) and industrial textile dyes (CI Reactive Red 195, CI Reactive Blue 250 and CI Reactive Yellow 145). The nanosystems developed exhibited promising results for industrial application in effluent photoremediation using visible light, with the possibility of magnetic recovery.

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SINGH, JITENDRA PAL, R. C. SRIVASTAVA, H. M. AGRAWAL et PREM CHAND. « RELAXATION PHENOMENA IN NANOSTRUCTURED ZINC FERRITE ». International Journal of Nanoscience 08, n^o 06 (décembre 2009) : 523–31. http://dx.doi.org/10.1142/s0219581x09006456.

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The electron paramagnetic resonance (EPR) is a well known tool to investigate the magnetic relaxation phenomena in the magnetic particles. For the present investigation, temperature variant EPR has been performed in order to study the relaxation mechanism in zinc ferrite nanoparticles. The magnetic nanoparticles were synthesized by using the nitrates of zinc and iron, and citric acid. The particle size of the samples were measured by the X-ray diffraction and Transmission Electron Microscopy. A more precise, Williamson–Hall (W–H) approach was used for the determination of the particle size as well as the strain in nanoparticles. The kinematics of magnetic moment has been studied with the help of temperature dependent EPR spectroscopy. Relaxation time calculations and temperature dependence of linewidth show the dominance of spin-lattice relaxation in these systems. Both nanoparticle systems show the presence of direct and Raman process in the relaxation mechanism and completely rule out the presence of Orbach process.

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Tsay, Chien-Yie, Yi-Chun Chiu et Chien-Ming Lei. « Hydrothermally Synthesized Mg-Based Spinel Nanoferrites : Phase Formation and Study on Magnetic Features and Microwave Characteristics ». Materials 11, n^o 11 (14 novembre 2018) : 2274. http://dx.doi.org/10.3390/ma11112274.

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Three kinds of magnesium-based spinel nanoferrites with the chemical formulas of MgFe2O4 (Mg ferrite), Mg0.9Mn0.1Fe2O4 (Mg-Mn ferrite), and Mg0.9Mn0.1In0.1Fe1.9O4 (Mg-Mn-In ferrite) were synthesized by hydrothermal route. We report the composition-dependent magnetic parameters and microwave properties of Mg-based ferrite nanoparticles. XRD results revealed that the Mg-based ferrite nanoparticles exhibited a cubic spinel structure and had an average nanocrystallite size in the range of 5.8–2.6 nm. Raman spectroscopy analysis confirmed the formation of cubic-spinel phase Mg-based nanoferrites. The room-temperature magnetization measurements indicated that the Mg ferrite nanoparticles had superparamagnetic behavior; whereas the Mg-Mn and Mg-Mn-In ferrite nanoparticles exhibited a paramagnetic nature. The microwave properties of obtained ferrite nanoparticles were studied by alternating current (AC) magnetic susceptibility measurement and electron paramagnetic resonance (EPR) spectroscopy. It was found that the un-substituted Mg ferrite sample exhibited microwave characteristics better than those of the Mn substituted and Mn-In co-substituted Mg ferrite samples.

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Gupta, Meenal, Anusree Das, Dipankar Das, Satyabrata Mohapatra et Anindya Datta. « Chemical Synthesis of Rare Earth (La, Gd) Doped Cobalt Ferrite and a Comparative Analysis of Their Magnetic Properties ». Journal of Nanoscience and Nanotechnology 20, n^o 8 (1 août 2020) : 5239–45. http://dx.doi.org/10.1166/jnn.2020.18528.

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Lanthanum (La) and gadolinium (Gd) doped cobalt ferrite nanoparticles are synthesized using a soft chemical approach. The analysis of these ferrites using X-ray diffraction (XRD) and transmission electron microscopy (TEM) shows that lattice spacing decreases in the doped ferrite samples. Magnetization data indicates towards the decrease of saturation magnetisation but increase in coercivity with doping. Mössbauer spectroscopy measurements at room temperature indicate increased occupancy of trivalent cations at tetrahedral site. The addition of rare earth dopants reduces the hard-magnetic character of cobalt ferrite.

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Lin, Qing, Jinpei Lin, Yun He, Ruijun Wang et Jianghui Dong. « The Structural and Magnetic Properties of Gadolinium Doped CoFe2O4Nanoferrites ». Journal of Nanomaterials 2015 (2015) : 1–6. http://dx.doi.org/10.1155/2015/294239.

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Gadolinium substituted cobalt ferrite CoGdxFe2−xO4(x= 0, 0.04, 0.08) powders have been prepared by a sol-gel autocombustion method. XRD results indicate the production of a single cubic phase of ferrites. The lattice parameter increases and the average crystallite size decreases with the substitution of Gd3+ions. SEM shows that the ferrite powers are nanoparticles. Room temperature Mössbauer spectra of CoGdxFe22−xO4are two normal Zeeman-split sextets, which display ferrimagnetic behavior. The saturation magnetization decreases and the coercivity increases by the Gd3+ions.

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Saykova, Diana, Svetlana Saikova, Yuri Mikhlin, Marina Panteleeva, Ruslan Ivantsov et Elena Belova. « Synthesis and Characterization of Core–Shell Magnetic Nanoparticles NiFe2O4@Au ». Metals 10, n^o 8 (10 août 2020) : 1075. http://dx.doi.org/10.3390/met10081075.

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In this study, NiFe2O4@Au core–shell nanoparticles were prepared by the direct reduction of gold on the magnetic surface using amino acid methionine as a reducer and a stabilizing agent simultaneously. The obtained nanoparticles after three steps of gold deposition had an average size of about 120 nm. The analysis of particles was performed by X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, and UV-Vis spectroscopy techniques. The results indicate successful synthesis of core–shell particles with the magnetic core, which consists of a few agglomerated nickel ferrite crystals with an average size 25.2 ± 2.0 nm, and the thick gold shell consists of fused Au0 nanoparticles (NPs). Magnetic properties of the obtained nanoparticles were examined with magnetic circular dichroism. It was shown that the magnetic behavior of NiFe2O4@Au NPs is typical for superparamagnetic NPs and corresponds to that for NiFe2O4 NPs without a gold shell. The results indicate the successful synthesis of core–shell particles with the magnetic nickel ferrite core and thick gold shell, and open the potential for the application of the investigated hybrid nanoparticles in hyperthermia, targeted drug delivery, magnetic resonance imaging, or cell separation. The developed synthesis strategy can be extended to other metal ferrites and iron oxides.

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Mohapatra, Jeotikanta, Meiying Xing et J. Ping Liu. « Inductive Thermal Effect of Ferrite Magnetic Nanoparticles ». Materials 12, n^o 19 (30 septembre 2019) : 3208. http://dx.doi.org/10.3390/ma12193208.

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Localized heat induction using magnetic nanoparticles under an alternating magnetic field is an emerging technology applied in areas including, cancer treatment, thermally activated drug release and remote activation of cell functions. To enhance the induction heating efficiency of magnetic nanoparticles, the intrinsic and extrinsic magnetic parameters influencing the heating efficiency of magnetic nanoparticles should be effectively engineered. This review covers the recent progress in the optimization of magnetic properties of spinel ferrite nanoparticles for efficient heat induction. The key materials factors for efficient magnetic heating including size, shape, composition, inter/intra particle interactions are systematically discussed, from the growth mechanism, process control to chemical and magnetic properties manipulation.

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Wirecka, Roma, Krzysztof Maćkosz, Antoni Żywczak, Mateusz Marek Marzec, Szczepan Zapotoczny et Andrzej Bernasik. « Magnetoresistive Properties of Nanocomposites Based on Ferrite Nanoparticles and Polythiophene ». Nanomaterials 13, n^o 5 (26 février 2023) : 879. http://dx.doi.org/10.3390/nano13050879.

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In the presented study, we have synthesized six nanocomposites based on various magnetic nanoparticles and a conducting polymer, poly(3-hexylthiophene-2,5-diyl) (P3HT). Nanoparticles were either coated with squalene and dodecanoic acid or with P3HT. The cores of the nanoparticles were made of one of three different ferrites: nickel ferrite, cobalt ferrite, or magnetite. All synthesized nanoparticles had average diameters below 10 nm, with magnetic saturation at 300 K varying between 20 to 80 emu/g, depending on the used material. Different magnetic fillers allowed for exploring their impact on the conducting properties of the materials, and most importantly, allowed for studying the influence of the shell on the final electromagnetic properties of the nanocomposite. The conduction mechanism was well defined with the help of the variable range hopping model, and a possible mechanism of electrical conduction was proposed. Finally, the observed negative magnetoresistance of up to 5.5% at 180 K, and up to 1.6% at room temperature, was measured and discussed. Thoroughly described results show the role of the interface in the complex materials, as well as clarify room for improvement of the well-known magnetoelectric materials.

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Goswami, Partha P., Hanif A. Choudhury, Sankar Chakma et Vijayanand S. Moholkar. « Sonochemical Synthesis of Cobalt Ferrite Nanoparticles ». International Journal of Chemical Engineering 2013 (2013) : 1–6. http://dx.doi.org/10.1155/2013/934234.

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Cobalt ferrite being a hard magnetic material with high coercivity and moderate magnetization has found wide-spread applications. In this paper, we have reported the sonochemical synthesis of cobalt ferrite nanoparticles using metal acetate precursors. The ferrite synthesis occurs in three steps (hydrolysis of acetates, oxidation of hydroxides, and in situ microcalcination of metal oxides) that are facilitated by physical and chemical effects of cavitation bubbles. The physical and magnetic properties of the ferrite nano-particles thus synthesized have been found to be comparable with those reported in the literature using other synthesis techniques.

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Aji, Wahyu Waskito, et Edi Suharyadi. « Study of Heavy Metal Ions Mn(II), Zn(II), Fe(II), Ni(II), Cu(II), and Co(II) Adsorption Using MFe₂O₄ (M=Co²⁺, Mg²⁺, Zn²⁺, Fe²⁺, Mn²⁺, and Ni²⁺) Magnetic Nanoparticles as Adsorbent ». Materials Science Forum 901 (juillet 2017) : 142–48. http://dx.doi.org/10.4028/www.scientific.net/msf.901.142.

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Removal of heavy metal ions (Co2+, Cu2+, Zn2+, Fe2+, Mn2+, and Ni2+) from artificial wastewater has been successfully perfomed by adsorption process using magnetic ferrite (MFe2O4; M=Co2+, Mg2+, Zn2+, Fe2+, Mn2+, and Ni2+) nanoparticles. Ferrite nanoparticles were synthesized using coprecipitation method and used as absorbent in heavy metal ions removal with concentration of 5 g/L and 10 g/L. The adsorption and desorption ability of each ferrite nanoparticles, the effect of heavy metal ion in adsorption and desorption process, and the endurance of ferrite nanoparticles were investigated using atomic absorption spectroscopy (AAS). The removal process has been conducted for wastewater at pH 7.It showed the presence of heavy metal precipitate in solution. The result shows that MgFe2O4 has the highest adsorption ability than other ferrite and MnFe2O4 is the lowest. Desorption ability of all ferrites is high except for Fe ion removal. Desorption of Fe ion shows very low result which might due to FeO bond from Fe ion reaction in acid solution. The endurance of MnFe2O4 and Fe3O4 as adsorbent after repeated adsorption and desorption process is up to 4 times and more than 6 times. The MnFe2O4 nanoparticles show a stability in adsorption ability after 4 times repetition adsorption and desorption process.

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Blanco-Esqueda, I. G., G. Ortega-Zarzosa, J. R. Martínez et A. L. Guerrero. « Preparation and Characterization of Nickel Ferrite-SiO2/Ag Core/Shell Nanocomposites ». Advances in Materials Science and Engineering 2015 (2015) : 1–7. http://dx.doi.org/10.1155/2015/678739.

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Magnetic composites with silver nanoparticles bonded to their surface were successfully prepared using a simple chemical method. By means of a sol-gel technique, nickel ferrite nanoparticles have been prepared and coated with silica to control and avoid their magnetic agglomeration. The structural and magnetic properties of the nanoparticles were studied in function of the annealing temperature. Then, silver nanoparticles were incorporated by hydrolysis-condensation of tetraethyl orthosilicate, which contains silver nitrate on the surface of the nickel ferrite-SiO2core/shell. Samples were characterized using X-ray diffraction, IR spectroscopy, SEM, and magnetometry. Results show that the silica covered the nickel ferrite nanoparticles and the silver nanoparticles remain stable in the surface of the composite.

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Gaumet, Alizé, Francesco Caddeo, Danilo Loche, Anna Corrias, Maria Casula, Andrea Falqui et Alberto Casu. « Magnetic Study of CuFe2O4-SiO2 Aerogel and Xerogel Nanocomposites ». Nanomaterials 11, n^o 10 (12 octobre 2021) : 2680. http://dx.doi.org/10.3390/nano11102680.

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CuFe2O4 is an example of ferrites whose physico-chemical properties can vary greatly at the nanoscale. Here, sol-gel techniques are used to produce CuFe2O4-SiO2 nanocomposites where copper ferrite nanocrystals are grown within a porous dielectric silica matrix. Nanocomposites in the form of both xerogels and aerogels with variable loadings of copper ferrite (5 wt%, 10 wt% and 15 wt%) were synthesized. Transmission electron microscopy and X-ray diffraction investigations showed the occurrence of CuFe2O4 nanoparticles with average crystal size ranging from a few nanometers up to around 9 nm, homogeneously distributed within the porous silica matrix, after thermal treatment of the samples at 900 °C. Evidence of some impurities of CuO and α-Fe2O3 was found in the aerogel samples with 10 wt% and 15 wt% loading. DC magnetometry was used to investigate the magnetic properties of these nanocomposites, as a function of the loading of copper ferrite and of the porosity characteristics. All the nanocomposites show a blocking temperature lower than RT and soft magnetic features at low temperature. The observed magnetic parameters are interpreted taking into account the occurrence of size and interaction effects in an ensemble of superparamagnetic nanoparticles distributed in a matrix. These results highlight how aerogel and xerogel matrices give rise to nanocomposites with different magnetic features and how the spatial distribution of the nanophase in the matrices modifies the final magnetic properties with respect to the case of conventional unsupported nanoparticles.

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Maklad, M. H., N. M. Shash et H. K. Abdelsalam. « Synthesis, characterization and magnetic properties of nanocrystalline Ni1-xZnxFe2O4 spinels via coprecipitation precursor ». International Journal of Modern Physics B 28, n^o 25 (9 septembre 2014) : 1450165. http://dx.doi.org/10.1142/s0217979214501653.

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Nanocrystalline Ni 1-x Zn x Fe 2 O 4 (0.0 ≤ x ≤ 1.0) spinels are synthesized with a crystallite size range 5–2.2 nm, using different annealing temperatures. The influence of zinc content as well as grain size of ferrite on the ferrite microstructure, therefore on the physical properties of ferrite, are investigated by means of X-ray diffraction (XRD), scanning electron microscope (SEM), atomic force microscope (AFM), thermal analysis (TG, DTG, DSC) and infrared microscopy (IR). XRD results confirm single phase spinel structure for ferrite with Zn content x = 0.1 whereas second phase appears in higher zinc content ferrites. Thermal analysis shows an endothermic peak at ~ 720°C–750°C reveals the removal of defective surface layer existed on the surface of ferrite grains, which leads to cation redistribution. This is supported by the shift observed in IR bands as a result of the increase in zinc content or calcination temperature. Ferrite with composition Ni 0.7 Zn 0.3 Fe 2 O 4 calcined at 1000°C has the maximum saturation magnetization Ms among various compositions at different calcination temperatures. The Ms and the coercivity Hc of the ferrites nanoparticles are different from their corresponding bulk, which attributes to a defective surface layer, controlling the ultrafine particle behavior.

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Santos, P. T. A., Joelda Dantas, P. M. A. G. Araújo, P. T. A. Santos et A. C. F. M. Costa. « Nanoferrites Ni-Zn Silanized with 3-Aminopropyltrimethoxysilane Using the Reflux Method ». Materials Science Forum 805 (septembre 2014) : 94–99. http://dx.doi.org/10.4028/www.scientific.net/msf.805.94.

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In this paper we propose nanoferrites Ni-Zn silanization with 3-aminopropyltrimethoxysilane using the method of reflux and evaluate the effect of silanization on the structure, morphology and magnetism of the magnetic nanoparticles aimed at biological applications. The samples as synthesized and after silanization were characterized by XRD, FTIR, SEM and testing magnetic attraction. The results indicated a single phase inverse spinel Ni-Zn ferrite, high intensity of diffraction peaks and a high basal width of all reflections observed, indicating that the samples are crystalline, and formation of nanoparticles. Morphologically, for nanoferrites Ni-Zn synthesized observed formation of large agglomerates in the form of spongy blocks of frail and after silanization was observed with respect dense pellets, indicating that most particles were rigidly connected by the presence of the agent silane. The characteristic bands of the spinel were observed for the Ni-Zn nanoferrites before and after silanization, and also observed the characteristic bands of silane in confirming the ferrites silanized functionalization of ferrites with the silane agent. Nanoparticles ferrite as synthesized and after silanized were strongly attracted by the presence of a magnet, immediately after the presence thereof indicating that the silane is effective is not interfere with the magnetic particles, maintaining the same magnetic behavior.

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Akhtar, M., G. Hussain, M. Yusuf, N. Amin et M. I. Arshad. « Synthesis and characterizations of Mg-Cu-Co-Dy ferrites and their composites with graphene nanoplatelets (GNP) ». Journal of Ovonic Research 18, n^o 4 (31 juillet 2022) : 539. http://dx.doi.org/10.15251/jor.2022.184.539.

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Nanocrystalline spinel ferrite Mg0.5Cu0.25Co0.25Fe1.97Dy0.03O4 (MCCD-ferrites) and their composites with graphene nanoplatelets (GNP =0.0%, 1.25% 2.5%, 3.75%, 5%) were prepared by sol-gel technique and sintered at 850 oC for 5 hours. Measurements in the areas of X-ray diffraction, electrical, optical, dielectric and magnetic properties were used to analyze the effects of the inclusion of graphene with ferrite nanoparticles. The crystallite size was determined in the range of 27.62 – 41.46 (nm). The optical bandgap was found in the range of 3.50 eV to 2.88 eV. The dielectric loss was measured between 8 Hz and 8 MHz at room temperature (RT). Magnetic characteristics of the materials are measured and calculated. The magnetic performances of MCCDF-GNP Composites nanoparticles are improved with an increase in saturation (Ms) magnetization. This material can be utilized for humidity sensors, antennae, and micro memory chips.

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Malathi, S., B. Sridhar et Shiferaw Garoma Wayessa. « A Study of Lithium Ferrite and Vanadium-Doped Lithium Ferrite Nanoparticles Based on the Structural, Optical, and Magnetic Properties ». Journal of Nanomaterials 2023 (14 février 2023) : 1–7. http://dx.doi.org/10.1155/2023/6752950.

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Lithium ferrite and vanadium-doped lithium ferrite have been extensively studied in recent research because of their potential applications in thermochromic materials, optoelectronic devices, and as a cathode material for rechargeable lithium batteries. In the present investigation, lithium ferrite and lithium vanadium ferrite are synthesized by sol–gel process. According to the Scherrer formula, the average particle size of lithium ferrite is 22 nm and that of vanadium-doped lithium ferrite is 29 nm. The lattice parameters and dislocation density are calculated from the X-ray diffraction results. According to the Fourier transform infrared spectroscopy analysis, ferrites were formed that exhibit strong absorption bands. According to the energy-dispersive X-ray analysis spectrum, the predicted elements are present in the sample. With the use of a vibrating sample magnetometer (VSM), the materials’ magnetic behavior is investigated.

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Vestal, Christy R., et Z. John Zhang. « Magnetic spinel ferrite nanoparticles from microemulsions ». International Journal of Nanotechnology 1, n^o 1/2 (2004) : 240. http://dx.doi.org/10.1504/ijnt.2004.003727.

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Veverka, M., P. Veverka, O. Kaman, A. Lančok, K. Závěta, E. Pollert, K. Knížek et al. « Magnetic heating by cobalt ferrite nanoparticles ». Nanotechnology 18, n^o 34 (27 juillet 2007) : 345704. http://dx.doi.org/10.1088/0957-4484/18/34/345704.

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Thirupathi, G., et R. Singh. « Magnetic Properties of Zinc Ferrite Nanoparticles ». IEEE Transactions on Magnetics 48, n^o 11 (novembre 2012) : 3630–33. http://dx.doi.org/10.1109/tmag.2012.2199475.

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Sharma, S. K., Ravi Kumar, Shalendra Kumar, V. V. Siva Kumar, M. Knobel, V. R. Reddy, A. Banerjee et M. Singh. « Magnetic study of Mg0.95Mn0.05Fe2O4 ferrite nanoparticles ». Solid State Communications 141, n^o 4 (janvier 2007) : 203–8. http://dx.doi.org/10.1016/j.ssc.2006.10.014.

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Ichiyanagi, Y., M. Kubota, S. Moritake, Y. Kanazawa, T. Yamada et T. Uehashi. « Magnetic properties of Mg-ferrite nanoparticles ». Journal of Magnetism and Magnetic Materials 310, n^o 2 (mars 2007) : 2378–80. http://dx.doi.org/10.1016/j.jmmm.2006.10.737.

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Chitra, Chitra, T. Raguram et K. S. Rajni. « Microstructural and Magnetic Properties of Cobalt Ferrite Nanoparticles Synthesized by Sol-Gel Technique ». International Journal of Trend in Scientific Research and Development Volume-2, Issue-5 (31 août 2018) : 371–77. http://dx.doi.org/10.31142/ijtsrd15871.

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Petrova, E. G., Ya A. Shavshukova, D. A. Kotsikau, K. V. Laznev et V. V. Pankov. « Synthesis of nano-dimensional cobalt-zinc ferrites by the low-temperature spray-drying with subsequent thermolysis ». Proceedings of the National Academy of Sciences of Belarus, Chemical Series 54, n^o 4 (12 janvier 2019) : 406–12. http://dx.doi.org/10.29235/1561-8331-2018-54-4-406-412.

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Co0,65Zn0,35Fe2O4nanoparticles were produced by spray-drying in air in presence of NaCl from the solution of nitrates, as well as from the suspension of coprecipitated particles. The precursors obtained were annealed at 300–900 °C in the matrix of the inert component in order to increase the crystallinity degree without substantial increase of the nanoparticle size. Microstructure, morphology and magnetic properties of nanoparticles were studied by XRD, FT-IR spectroscopy, TEM / SEM and magnetometry. For the ferrites obtained from nitrate solutions partial oxidation of Co2+ions to Co3+occurs, which leads to the formation of two spinel phases, ferrite and cobaltite. With the increase of annealing temperature the content of cobaltite decreases and content of ferrite increases. No cobaltite formation was observed for annealing the spray-dried suspension. An increase in the temperature of the heat treatment leads to partial recrystallization of the particles and the ordering of the ferrite crystal structure, which causes an increase in the specific magnetization of the materials: from 32.8 emu/g (before annealing) to 91.3 emu/g (annealing at 900 ° C). The average diameter of nanoparticles after heat treatment does not exceed 100 nm.

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Kronkalns, G., M. Kodols et M. M. Maiorov. « Structure, Composition and Magnetic Properties of Ferrofluid Nanoparticles after Separation / Feromagnētisko Šķidrumu Nanodaļiņu Struktūras, Sastāva un Magnētisko Īpašību Izmaiņas Pēc Separācijas ». Latvian Journal of Physics and Technical Sciences 50, n^o 4 (1 août 2013) : 56–61. http://dx.doi.org/10.2478/lpts-2013-0026.

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Abstract The structure, composition and magnetic properties of iron oxide nanoparticles are studied as dependent on the synthesis technology and method of separation in ferrofluids. The goal of the present study is to improve the magnetic properties of wet-synthesized nanoparticles and achieve a narrow nanoparticle size distribution. The results of measurements show that by varying the conditions of the chemical coprecipitation method, different compositions and structures of the nanoparticles could be obtained. The separation of ferrite nanoparticles of a polydisperse colloid by centrifugation as well as by HGMS provides the possibility to obtain a nanoparticle set with narrow size distribution

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Owolabi, Taoreed O., Tawfik A. Saleh, Olubosede Olusayo, Miloud Souiyah et Oluwatoba Emmanuel Oyeneyin. « Modeling the Specific Surface Area of Doped Spinel Ferrite Nanomaterials Using Hybrid Intelligent Computational Method ». Journal of Nanomaterials 2021 (18 août 2021) : 1–13. http://dx.doi.org/10.1155/2021/9677423.

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Spinel ferrites nanomaterials are magnetic semiconductors with excellent chemical, magnetic, electrical, and optical properties which have rendered the materials useful in many technological driven applications such as solar hydrogen production, data storage, magnetic sensing, converters, inductors, spintronics, and catalysts. The surface area of these nanomaterials contributes significantly to their targeted applications as well as the observed physical and chemical features. Experimental doping has shown a great potential in enhancing and tuning the specific surface area of spinel ferrite nanomaterials while the attributed experimental challenges call for viable theoretical model that can estimate the surface area of doped spinel ferrite nanomaterials with high degree of precision. This work develops stepwise regression (STWR) and hybrid genetic algorithm-based support vector regression (GBSVR) intelligent model for estimating specific surface area of doped spinel ferrite nanomaterials using lattice parameter and the size of nanoparticle as descriptors to the models. The developed hybrid GBSVR model performs better than STWR model with the performance improvement of 7.51% and 22.68%, respectively, using correlation coefficient and root mean square error as performance metrics when validated with experimentally measured specific surface area of doped spinel ferrite nanomaterials. The developed GBSVR model investigates the influence of nickel, yttrium, and lanthanum nanoparticles on the specific surface area of different classes of spinel ferrite nanomaterials, and the obtained results agree excellently well with the measured values. The accuracy and precision characterizing the developed model would be of immense importance in enhancing specific surface area of doped spinel ferrite nanomaterial prediction with circumvention of experimental stress coupled with reduced cost.

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