Zeitschriftenartikel: „Ferrites de cobalt“

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de la Torre, Ernesto, Ana Lozada, Maricarmen Adatty und Sebastián Gámez. „Activated Carbon-Spinels Composites for Waste Water Treatment“. Metals 8, Nr. 12 (16.12.2018): 1070. http://dx.doi.org/10.3390/met8121070.

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Nowadays, mining effluents have several contaminants that produce great damage to the environment, cyanide chief among them. Ferrites synthesized from transition metals have oxidative properties that can be used for cyanide oxidation due to their low solubility. In this study, cobalt and copper ferrites were synthesized via the precipitation method, using cobalt nitrate, copper nitrate, and iron nitrate as precursors in a molar ratio of Co or Cu:Fe = 1:2 and NaOH as the precipitating agent. The synthesized ferrites were impregnated in specific areas on active carbon. These composites were characterized using X-Ray Diffraction (XRD) and Scanning Electron Spectroscopy (SEM). The XRD results revealed a cubic spinel structure of ferrites with a single phase of cobalt ferrite and two phases (copper ferrite and copper oxides) for copper. The CoFe2O4 impregnated on active carbon reached a cyanide oxidation of 98% after 8 h of agitation; the composite could be recycled five times with an 18% decrease in the catalytic activity. In cobalt ferrites, a greater dissolution of iron than cobalt was obtained. In the case of copper ferrite, however, the copper dissolution was higher. These results confirm that ferrites and activated carbon composites are a novel alternative for cyanide treatment in mining effluents.

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Boss, Alan F. N., Antonio C. C. Migliano und Ingrid Wilke. „The Influence of Stoichiometry on the Index of Refraction of Cobalt Ferrite Samples at Terahertz Frequencies“. MRS Advances 2, Nr. 58-59 (2017): 3663–66. http://dx.doi.org/10.1557/adv.2017.355.

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ABSTRACT We report an experimental study on the terahertz frequency dielectric properties of manganese cobalt ferrites (MnxCo1−xFe2O4) and nickel cobalt ferrites (NixCo1-xFe2O4) with three different stoichiometry each, x=0.3, x=0.5 and 0.7. Particularly, we present a comparison and discussion of the terahertz frequency indices of refraction of these two ferrites compositions. MnxCo1−xFe2O4 and NixCo1-xFe2O4 pellets with different Mn/Co and Ni/Co ratios (x=0.3, x=0.5 and x=0.7) were prepared by state-of-the-art ceramic processing. The morphology and chemical homogeneity of these ferrites were characterized by energy dispersive x-ray spectroscopy. We observed that the indexes of refraction for manganese cobalt ferrites are 3.22, 3.71 and 3.67 for ratios of 0.3, 0.5 and 0.7, respectively. In the case of nickel cobalt ferrite, the indexes of refraction are 3.53, 3.57 and 3.47 for ratios of 0.3, 0.5 and 0.7 respectively. We notice a substantial difference in the index of refraction for the Mn0.3Co0.7Fe2O4. This difference may be correlated to a secondary phase formed in this sample.

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Al-Kadhi, Nada S., Ghadah M. Al-Senani, Rasmiah S. Almufarij, Omar H. Abd-Elkader und Nasrallah M. Deraz. „Green Synthesis of Nanomagnetic Copper and Cobalt Ferrites Using Corchorus Olitorius“. Crystals 13, Nr. 5 (03.05.2023): 758. http://dx.doi.org/10.3390/cryst13050758.

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This study aims to develop a self-combustion method for use in the preparation of copper and cobalt ferrites. This development was based on the full use of dry leaves of Corchorus olitorius plant in order to stimulate the preparation of the studied ferrites by making full use of the small amount of carbon produced from the combustion process. The fabrication of CuFe2O4 and CoFe2O4 with spinel-type structures and the Fd3m space group is confirmed by XRD and FTIR investigations. Two major vibration bands occur laterally at 400 cm−1 and 600 cm−1. We were able to understand the existence of two stages through the thermal behavior based on TG-DTG analysis for the materials under investigation. The first is from room temperature to 600 °C, which indicates the formation of reacting oxides with Co or Cu ferrites, while the second is from 600–1000 °C, which indicates the growth in the ferrite fabrication. The surface morphological analyses (SEM/EDS and TEM) display formation of homogeneous and nanosized particles. The surface properties of the samples containing CoFe2O4 are superior compared to those of the samples not containing CuFe2O4. Every sample under investigation displays type-IV-based isotherms with a type-H3 hysteresis loop. The VSM approach was used to evaluate the magnetic characteristics of Cu and Co ferrites. Copper ferrites have a magnetization of 15.77 emu/g, and cobalt ferrites have a magnetization of 19.14 emu/g. Moreover, the squareness (0.263) and coercivity (716.15 G) of cobalt ferrite are higher than those of copper ferrite.

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Pussi, Katariina, Keying Ding, Bernardo Barbiellini, Koji Ohara, Hiroki Yamada, Chuka Onuh, James McBride, Arun Bansil, Ray K. Chiang und Saeed Kamali. „Atomic Structure of Mn-Doped CoFe2O4 Nanoparticles for Metal–Air Battery Applications“. Condensed Matter 8, Nr. 2 (24.05.2023): 49. http://dx.doi.org/10.3390/condmat8020049.

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We discuss the atomic structure of cobalt ferrite nanoparticles doped with Mn via an analysis based on combining atomic pair distribution functions with high energy X-ray diffraction and high-resolution transmission electron microscopy measurements. Cobalt ferrite nanoparticles are promising materials for metal–air battery applications. Cobalt ferrites, however, generally show poor electronic conductivity at ambient temperatures, which limits their bifunctional catalytic performance in oxygen electrocatalysis. Our study reveals how the introduction of Mn ions promotes the conductivity of the cobalt ferrite electrode.

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Frolova, Liliya A. „Investigation of Magnetic and Photocatalytic Properties of CoFe₂O₄ Doped La³⁺, Nd³⁺, I³⁺“. ECS Meeting Abstracts MA2022-01, Nr. 30 (07.07.2022): 2496. http://dx.doi.org/10.1149/ma2022-01302496mtgabs.

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Cobalt ferrites are widely used for permanent magnets, magnetic fluids, microwave devices, high density information storage and environmental technologies. The properties of nanosized magnetic materials strongly depend on the shape, size, and phase composition of the particles. The great interest of researchers in nanosized materials in recent years is associated with the possibility of changing the properties of magnetic materials by controlling the particle size and distribution of cations over sublattices in ferrite [1]. Nanoparticles of doped cobalt ferrite showed improved physicochemical characteristics compared to individual components due to the synergistic effect of the mutual presence of cations. Currently, various technologies for producing ferrites are used. However, to obtain a single-phase product, calcination of the precursors at a temperature of 1300-1500 0C is required, which causes agglomeration and sintering of the product. The use of modern methods of electrochemical synthesis is the basis for obtaining ferrites from transition materials with a given set of properties. A characteristic recent trend is the development of new technologies and compositions for the production of precisely nanodispersed ferrites [2]. The purpose of this work is to study the possibility of using contact low-temperature nonequilibrium plasma for the synthesis of cobalt ferrites doped with La3+, Nd3+, I3+ cations, to establish a relationship between the cationic composition of ferrites and its phase composition, magnetic and structural characteristics. Ferrites were synthesized in the form of nanoparticles using contact nonequilibrium low temperature plasma in an electrochemical reactor. The crystalline microstructure of the samples was revealed by X-ray diffraction and X-ray phase methods. The magnetic characteristics were determined from hysteresis loops. The EPR spectra were obtained on a Radiopan SE/X-2543 radiospectrometer. To characterize the EPR signals, the intensity and width of the signal, and the resonant frequency were used. The visualization of the dependences of the technological characteristics of La3+-Nd3+-I3+ ferrites on the cationic composition was carried out by the simplex method using the STATISTICA 12 program. It has been established that the nature of the rare-earth metal cation in cobalt ferrite directly determines the magnetic and photocatalytic properties of spinel ferrites. The effect of the mutual influence of the content of cations on the saturation magnetization and coercive force is determined. The most influencing factor is the content of neodymium cations. Low values of the coercive force for Mn-Zn and Co-Zn ferrites and high values for the entire range of Co-Mn ferrites are established. An increase in the content of cobalt cations leads to an increase in the saturation magnetization value of Co-Mn ferrites. The EPR spectra show that the values of the resonance field and linewidth in the EPR spectrum correlate with the value of magnetic saturation. Simultaneous substitution of Nd3+ and La3+ in CoFe2O4 nanoparticles affected the structure, magnetic and photocatalytic properties. Structural parameters were investigated and calculated using X-ray diffraction studies. The magnetization analyzes were carried out at room temperature. Various magnetic parameters have been obtained and discussed, including remanence (Mr), coercive force (Hc), saturation magnetization (Ms), squareness ratio (SQR=Mr/Ms) and magnetic moment (nB). An increase in Mr, Ms, Hc and nB was found at lower concentrations of Nd3+ and La3+. An increase in the content of Nd3+ cations leads to a significant increase in the coercive force. The analysis of photocatalytic activity in the reaction of isolation of furacilin showed the best results (destruction rate 98%, time 40 minutes) for the ternary composition. References Caldeira, Luis Eduardo, et al. "Correlation of synthesis parameters to the structural and magnetic properties of spinel cobalt ferrites (CoFe2O4)–an experimental and statistical study." Journal of Magnetism and Magnetic Materials550 (2022): 169128. Lu, Yuzheng, et al. "Effect of Gd and Co contents on the microstructural, magneto-optical and electrical characteristics of cobalt ferrite (CoFe2O4) nanoparticles." Ceramics International2 (2022): 2782-2792.

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Majid, Farzana, Amarah Nazir, Sadia Ata, Ismat Bibi, Hafiz Shahid Mehmood, Abdul Malik, Adnan Ali und Munawar Iqbal. „Effect of Hydrothermal Reaction Time on Electrical, Structural and Magnetic Properties of Cobalt Ferrite“. Zeitschrift für Physikalische Chemie 234, Nr. 2 (25.02.2020): 323–53. http://dx.doi.org/10.1515/zpch-2019-1423.

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AbstractCobalt ferrite was synthesized by hydrothermal route in order to investigate the effect of hydrothermal reaction time on structural, magnetic and dielectric properties. The synthesized cobalt ferrite was characterized by X-ray diffraction, Fourier transform infrared and Vibrating-Sample Magnetometer (VMS). XRD data analysis confirmed the formation of cubic inverse spinel ferrite for complete time series as the high intensity peak corresponds to cubic normal spinel structure. The ionic radii, cation distribution among tetrahedral and octahedral sites, lattice parameters, X-ray density, bond lengths were also investigated cobalt ferrite prepared at different hydrothermal reaction time. The crystallite size was found to be in the range of 11.79–32.78 nm. Tolerance factor was near unity that also confirms the formation of cubic ferrites. VSM studies revealed the magnetic nature of cobalt ferrite. The coercivity (1076.3Oe) was observed for a sample treated for 11 h. The squareness ratio was 0.56 that is close to 0.5 which shows uniaxial anisotropy in cobalt ferrite. Frequency dependent dielectric properties i.e. dielectric constant, AC conductivity, tangent loss and AC resistivity are calculated with the help of Impedance Analyzer. Intrinsic cation vibration of cubic spinel ferrites are confirmed from FTIR analysis in the range of 400–4000 cm−1. In view of enhanced properties, this technique could possibly be used for the synthesis of cobalt ferrite for different applications.

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Hochu, F., und M. Lenglet. „Co(II) Optical Absorption in Spinels: Infrared and Ligand-Field Spectroscopic Study of the Ionicity of the bond. Magnetic Structure and Co2+→Fe3+MMCT in Ferrites. Correlation with the Magneto-Optical Properties“. Active and Passive Electronic Components 20, Nr. 3 (1998): 169–87. http://dx.doi.org/10.1155/1998/16871.

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The analysis of the infrared and ligand field spectra of COM2O4spinels reveals that the ionicity of these compounds varies in the following order aluminate > gallate > ferrite and chromite > rhodite and cobaltite. A linear relation has been established between the Δ(LO-TO)1splitting, Racah parameter and the ionic-covalent parameterSSp=ΣICP+tetra∑ICPocta. The influence of strong superexchange interactions on the optical spectrum of cobalt ferrites has been studied. The cation distribution has been established by EXAFS and XANES measurements. The cluster (CoFeO10)15–is characterized by a large MMCT transition Co2+→Fe3+at 1.65–1.7 eV (FWMH: 1.35–1.95 eV). The4A2→4T1(P) tetrahedral cobalt(II) in ferrimagnetic compounds is overlapped by the MMCT band. This study and the reinvestigation of the iron(III) electronic spectrum is ferrites may explain the magneto-optical properties of mixed cobalt-ferrites.

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Gupta, Priyanka, Dr Ravi Kumar Vijai und Subhash Chander. „Synthesis, Characterization and Magnetic properties of Nanoparticles of Cobalt Doped Ferrite“. International Journal of Chemistry, Mathematics and Physics 6, Nr. 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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Kikuchi, Takeyuki, Tatsuya Nakamura, Masamichi Miki, Makoto Nakanishi, Tatsuo Fujii, Jun Takada und Yasunori Ikeda. „Synthesis of Hexagonal Ferrites by Citric Complex Method“. Advances in Science and Technology 45 (Oktober 2006): 697–700. http://dx.doi.org/10.4028/www.scientific.net/ast.45.697.

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Various hexagonal ferrites, which include hard and soft ferrites, were prepared by citric complex method. High purity reagent of strontium carbonate, iron (III) nitrate ennnahydrate, cobalt (II) nitrate hexahydrate and lanthanum oxide were used as starting materials. Prepared aqueous solution was heated for dehydration and gelling. Thermal pyrolysis was carried out by heating the gel. The obtained precursor powders were ground with an alumina mortar and compacted by uniaxial pressing into disk specimens and then heated at temperature range between 1023K and 1523K in air. Phase identification and determination of lattice parameters were carried out by powder X-ray diffraction. Scanning Electron Microscope was utilized to investigate the microstructure of the polycrystalline ferrites. Magnetic properties were discussed by magnetization measurements by using a vibration sample magnetometer. Magnetization and coercive force were measured. In the case of M-type ferrite, M-type barium and strontium ferrites were formed at vary low temperature relative to by conventional synthesis. The lanthanum and cobalt substituted M-type strontium ferrite ultra fine powders prepared by citric complex method showed extremely large coercive force.

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Zhang, Chang Sen, Lei Yang und Feng Zhou. „Preparation and Microstructure of Co-Ferrite Fine Powder“. Advanced Materials Research 328-330 (September 2011): 1365–68. http://dx.doi.org/10.4028/www.scientific.net/amr.328-330.1365.

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Cobalt ferrites were prepared by citrate sol-gel method, chemical co-precipitation, mechanical grinding, respectively. The grain size, morphology, and the size of crystal particles were studied by x-ray diffraction (XRD) and scanning electron microscope (SEM). Cobalt ferrite showed different morphologys when prepared by different methods, It was tapered corners which prepared by sol-gel method; It was tetrahedral which prepared by mechanical grinding method; It was sphere which prepared by chemical co-precipitation method. The average grain size of cobalt ferrite was less than 100nm, while particles prepared by chemical precipitation method were the smallest. The size of Cobalt ferrite prepared by sol-gel method was decreased with the cobalt content increased.

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Tomiczek, A. E. „Effect of milling time on microstructure of cobalt ferrites synthesized by mechanical alloying“. Archives of Materials Science and Engineering 111, Nr. 1 (01.09.2021): 5–13. http://dx.doi.org/10.5604/01.3001.0015.5561.

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Purpose: of this paper is to determine the effect of manufacturing conditions, especially milling time, on the microstructure and phase composition of CoFe2O4 cobalt ferrite. Design/methodology/approach: Cobalt ferrite (CoFe2O4) has been synthesised from a stoichiometric mixture of CoCo3 and α-Fe2O3 powders in a high energy planetary mill. Annealing at 1000°C for 6 hours after milling was used to improve the solid-state reaction. Calcinated samples were analysed by X-ray diffraction (XRD), and transmission electron microscopy (TEM). The relationship between the milling time of powders, their microstructure, as well as their properties were evaluated. Particles size distribution and scanning electron microscopy (SEM) with energy-dispersive X-ray spectroscopy (EDX) examination were also made. Findings: CoFe2O4 ferrites were successfully synthesized by mechanical alloying of α-Fe2O3 and CoCO3 powders. The powder particles had undergone morphological changes with the increasing milling time. However, the milling time does not affect the ferrite formation rate. It is expected that the improvement of fabrication parameters can further enhance the properties of cobalt ferrite presented in this work. Research limitations/implications: Contribute to research on the structure and properties of cobalt ferrites manufactured by mechanical alloying. Practical implications: The reactive milling and subsequently annealing is an efficient route to synthesise cobalt ferrite powder. However, using steel milling equipment risks powder contamination with iron and chromium from the vials and balls. Originality/value: The results of the experimental research of the developed ferrite materials served as the basis for determining material properties and for further investigation.

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Gupta, Meenal, Anusree Das, Dipankar Das, Satyabrata Mohapatra und 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, Nr. 8 (01.08.2020): 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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Lazdovica, Kristīne, und Valdis Kampars. „Influence of Crystallite Size of Nickel and Cobalt Ferrites on the Catalytic Pyrolysis of Buckwheat Straw by Using TGA-FTIR Method“. Key Engineering Materials 903 (10.11.2021): 69–74. http://dx.doi.org/10.4028/www.scientific.net/kem.903.69.

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Pyrolysis of buckwheat straw with or without catalysts was investigated using the TGA-FTIR method to determine the influence of nickel and cobalt ferrites on the distribution of pyrolysis products. According to the obtained results, the overall shape of the thermogravimetric and derivative thermogravimetric curves is unchanged in the presence of nickel and cobalt ferrites but different weight losses were observed. All catalysts contribute to the formation of solid residue from BWS pyrolysis. The presence of cobalt ferrites exhibited the highest bio-oil yields, whereas the highest non-condensable gas yield and the lowest bio-oil yield was obtained with the addition of NiFe2O4 (1) catalyst. According to the obtained results, the ability of nickel and cobalt ferrites to catalyze deoxygenation reactions depends on the crystallite size. The nickel or cobalt ferrites with smaller crystallite size (15-22 nm) show a higher ability to catalyzed dehydration reaction than catalysts with larger crystallite size (45-54 nm).

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Ortega López, Yudith, Hugo Medina Vázquez, Jesús Salinas Gutiérrez, Vanessa Guzmán Velderrain, Alejandro López Ortiz und Virginia Collins Martínez. „Synthesis Method Effect of CoFe2O4on Its Photocatalytic Properties for H2Production from Water and Visible Light“. Journal of Nanomaterials 2015 (2015): 1–9. http://dx.doi.org/10.1155/2015/985872.

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Currently, the need for more efficient materials that work in the visible light spectrum for hydrogen production has been increasing. Under this criterion, ferrites are ideal because their energetic properties are favorable to photocatalysis as they have a low band gap (1.5 to 3 ev). In this particular research, ferrite is presented as a hydrogen producer. Cobalt ferrites were synthesized by chemical coprecipitation (CP) and ball milling (BM) for comparison of their performance. The characterization of the materials was carried out with X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), BET surface area, UV-VIS spectroscopy, and water adsorption/desorption tests. Evaluation of the photocatalytic activity under visible light was followed by gas chromatography. The results showed that cobalt ferrite by ball milling had a higher photocatalytic activity; this is attributed to the vacancies generated during the milling process at which the sample was exposed.

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Gupta, Priyanka, und Dr Ravi Kumar Vijai. „Synthesis, Characterization and Dielectric properties of Nanoparticles of Cobalt Doped Ferrite (Cox Fe1-x Fe2 O4)“. International Journal of Chemistry, Mathematics and Physics 7, Nr. 4 (2023): 1–8. http://dx.doi.org/10.22161/ijcmp.7.4.1.

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Ferrites, a recently uncovered category of materials, have found extensive application in various critical domains. Among them, cobalt ferrites stand out as hard magnetic materials with exceptional coercivity.. We successfully prepared cobalt ferrites by using nanocrystalline powers by Sol gel method. In our study Crystalline, Magnetic nanoparticles of Cobalt ferrites (Cox Fe1-x Fe2 O4) (x = 0.4, 0.5, 0.6, 0.8) 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 and TEM. Particle size found between 8.8 nm to 14.26 nm using Debye Scherrer method. Lattice constant decreases as the value of ‘x’ increases. Dielectric properties were investigated using impedance analyser. The relative dielectric constant and loss tangents of ferrites a function of frequency (1kHz-30MHz) was investigated at room temperature, both parameter decreases as frequency increases.

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Jameel, M. H., M. A. Agam, M. Q. Hamzah, M. S. Roslan, S. Z. H. Rizvi und J. A. Yabagi. „Structural, optical and morphological properties of zinc -doped cobalt-ferrites CoFe2−xZnxO4 (x=0.1-0.5)“. Digest Journal of Nanomaterials and Biostructures 16, Nr. 2 (2021): 399–408. http://dx.doi.org/10.15251/djnb.2021.162.399.

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Cobalt-ferrite (CoFe2O4) based nanoparticles are appropriate candidates for electrical, optical, and magnetic applications for electrical appliances. In the current study, a coprecipitation technique was used to prepare Zinc doped cobalt ferrites with compositions CoFe2−xZnxO4 (x=0.1-0.5) at various percentages using Zinc and Co-nitrate as precursors. The analysis of crystal phase structure, hkl planes, average crystalline size, volume, and lattice parameters of the unit cell of CoFe2-xZnxO4 doped (NPs) was carried under X-ray diffraction (XRD). X-ray spectra analysis, FT-IR Spectra, UV Visible Spectra, and SEM studies shown that the as-synthesized powders were contained of nano-crystallite size (42– 53nm) cubic-spinel phase with irregularly-structure. Calcination at low temperature (80˚C) of the precursor followed through sintering (500°C for 3h) con-sequence in a single-phase cubic-spinel shape with an average particle size of 42-53nm, as shown by scanning electron micrographs images. Sharp peaks and intense diff raction features in XRD pattern show that an increase in Zn doping concentration in cobalt spinel ferrite increases the crystalline behavior of the cubical spine phase. In cubical structure ferrites crystal lattices, the absorption band at low frequency is noticed above 400cm-1 but in the range of 300- 600cm-1 of the Fourier Transform Infrared bands were attributed to the tremblant of the ions of metal. The absorbance results of UV Spectra indicate that Zinc doped Cobalt Ferrite specimen had symbolic absorbance in the range of 660-900nm wavelength range of the conspicuous region. The Zn-doped cobalt-ferrite have a high strain derivative that could be a prospective material for electrical devices.

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Amaro, Luís, Daniela Correia, Teresa Marques-Almeida, Pedro Martins, Leyre Pérez, José Vilas, Gabriela Botelho, Senentxu Lanceros-Mendez und Clarisse Ribeiro. „Tailored Biodegradable and Electroactive Poly(Hydroxybutyrate-Co-Hydroxyvalerate) Based Morphologies for Tissue Engineering Applications“. International Journal of Molecular Sciences 19, Nr. 8 (24.07.2018): 2149. http://dx.doi.org/10.3390/ijms19082149.

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Polymer-based piezoelectric biomaterials have already proven their relevance for tissue engineering applications. Furthermore, the morphology of the scaffolds plays also an important role in cell proliferation and differentiation. The present work reports on poly(hydroxybutyrate-co-hydroxyvalerate) (PHBV), a biocompatible, biodegradable, and piezoelectric biopolymer that has been processed in different morphologies, including films, fibers, microspheres, and 3D scaffolds. The corresponding magnetically active PHBV-based composites were also produced. The effect of the morphology on physico-chemical, thermal, magnetic, and mechanical properties of pristine and composite samples was evaluated, as well as their cytotoxicity. It was observed that the morphology does not strongly affect the properties of the pristine samples but the introduction of cobalt ferrites induces changes in the degree of crystallinity that could affect the applicability of prepared biomaterials. Young’s modulus is dependent of the morphology and also increases with the addition of cobalt ferrites. Both pristine and PHBV/cobalt ferrite composite samples are not cytotoxic, indicating their suitability for tissue engineering applications.

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Gatelyte, Aurelija, Darius Jasaitis, Aldona Beganskiene und Aivaras Kareiva. „Sol-Gel Derived Ferrites: Synthesis and Characterization“. Advanced Materials Research 222 (April 2011): 235–38. http://dx.doi.org/10.4028/www.scientific.net/amr.222.235.

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In the present work, the sinterability and formation of nanosized yttrium iron garnet (Y3Fe5O12), yttrium perovskite ferrite (YFeO3), cobalt, nickel and zinc iron spinel (CoFe2O4, NiFe2O4 and ZnFe2O4, respectively) powders by an aqueous sol-gel processes are investigated. The phase purity of synthesized nano-compounds was characterized by powder X-ray diffraction analysis (XRD). The microstructural evolution and morphological features of obtained transition metal ferrites were studied by scanning electron microscopy (SEM). The possible application of these nanosized transition metal ferrites as ceramic pigments was demonstrated.

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Walters, I., R. Shende und J. A. Puszynski. „Hydrogen Production from Thermochemical Water-Splitting Using Ferrites Prepared by Solution Combustion Synthesis“. Advances in Science and Technology 91 (Oktober 2014): 32–38. http://dx.doi.org/10.4028/www.scientific.net/ast.91.32.

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Currently, there are several methods to produce spinel ferrite powder material such as sol-gel synthesis, self-propagating high-temperature synthesis (SHS), aerosol spray pyrolysis, and solution combustion synthesis (SCS). These methods have been shown to produce nominally phase pure ferrites for use in hydrogen generation by thermochemical water-splitting. Among these methods, the ferrites derived by SCS have not been fully investigated for hydrogen generation from thermochemical water-splitting. SCS, in general, has several advantages such as it being a simple synthesis that can be done relatively quickly and produces materials with high specific surface area. In this study, nickel, zinc, cobalt, and manganese ferrites were synthesized using SCS and analyzed by XRD, BET, and SEM. Each ferrite material was placed inside an Inconel tubular reactor and five consecutive thermochemical cycles to determine hydrogen production. The regeneration and water-splitting temperatures were performed with water-splitting and regeneration temperatures of 900°C and 1100°C, respectively. Nickel ferrite produced significantly higher average hydrogen volume as compared to the other ferrites over the five thermochemical cycles. However, all four ferrites showed a decrease in hydrogen volume generation with increase in consecutive water-splitting cycle, which could be due to the grain growth as observed by BET and SEM analyses.

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Manimegalai, R., S. Sendhilnathan und V. Chithambaram. „Experimental investigation on ferrofluid properties of Cd doped Co-Zn ferrites“. Digest Journal of Nanomaterials and Biostructures 17, Nr. 2 (22.06.2022): 661–76. http://dx.doi.org/10.15251/djnb.2022.172.661.

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"Cadmium substituted Co-Zn ferrites 𝐶𝑜0.5𝑍𝑛0.5𝐶𝑑𝑥𝐹𝑒(2−𝑥)𝑂4 (𝑥=0.0, 0.1, 0.2, 0.4, and 0.5) were fabricated by using the Co-precipitation method. The molecular composition and prepared samples of cubic spinel structureswas characterized using X-ray diffraction peak (XRD). X-ray diffraction patterns obtained the most intensive peak at (311) crystallographic planes for x=0.5. Williamson-Hall (W-H) relation was associated with XRD data to determine the crystallite sizes range from 25.356 nm to 35.632 nm and strain value brought into being 0.0024 to 0.0021. Tetrahedral and octahedral sites of hoping length were found to diminish from 3.6707Å-3.6332Å and 2.9967Å-2.9662Å respectively due to the addition of Cd ion concentration. TEM analysis reveals the presence of spherical shape nanoparticles with agglomeration for the prepared samples. It could be referenced based on the investigation of results for molecule size by two XRD and TEM strategies which demonstrate the development of nanomaterials and doping of cobalt ferrites. TEM results are well agreed with the XRD diffraction pattern in crystallite size by using Scherrer’s formula. Fourier Transform Infrared Spectroscopy (FTIR) spectra analysis were carried out on synthesized ferrite samples and observed v1 and v2 strong absorption band in the range 400-4000 cm-1 be the possession to tetrahedral (A) and octahedral (B) sites. In FTIR, the increase of Cd2+ ion in Co-Zn ferrites leads to diminishing peak values towards lower wavenumbers. It is feasible to tune the magnetic characteristics of cobalt ferrite as a potential material for diverse technological applications by substituting Zn2+ and Cd2+ for cobalt magnetic ions."

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Mullurkara, Suraj V., Ramon Egli, B. C. Dodrill, Susheng Tan und P. R. Ohodnicki. „Understanding magnetic interactions and reversal mechanisms in a spinodally decomposed cobalt ferrite using first order reversal curves“. AIP Advances 13, Nr. 2 (01.02.2023): 025328. http://dx.doi.org/10.1063/9.0000562.

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Cobalt ferrites exhibit widely varied magnetic behaviour due to the presence of a miscibility gap leading to the formation of periodic self-assembled nanostructures via spinodal decomposition. Periodicity and amplitude of the compositional fluctuations can be controlled by thermodynamic and kinetic processing parameters which allows for careful tuning of the magnetic properties. Although reports have shown evidence of spinodal decomposition, there is a lack of detailed characterization of the magnetic interactions and reversal mechanisms in these materials. In this work we use high-resolution first order reversal curves (FORC) measurements to understand the underlying magnetic processes occurring in a cobalt ferrite with a nominal composition of Co1.8Fe1.2O4 before (calcined) and after spinodal decomposition (annealed). Additionally, FORC measurements with preconditioning fields were conducted to separate the interaction signatures at low coercive fields by biasing the sample in positive and negative mean fields. Microstructural characterization using TEM combined with EDS showed uniform chemistry in the calcined sample and the presence of Fe rich and Co rich regions in the annealed sample, due to spinodal decomposition. Signs of positive exchange interactions were observed in both calcined and annealed samples. This work presents the first detailed magnetic characterization of magnetic interactions in a nanostructured cobalt ferrite, and provides an example of magnetic characterization of nanostructured ferrites using FORC.

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El-Salam, Asmaa Reda Abd, K. E. Rady, Ezzat A. ELFadaly und Mobarak Hassan Aly. „Enhanced Structural and Morphological Properties of Doped Cobalt Zinc Ferrite“. Journal of Nanotechnology and Nanomaterials 4, Nr. 2 (22.11.2023): 89–93. http://dx.doi.org/10.33696/nanotechnol.4.046.

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In this study, Mn2+ substituted Co0.8−x Mnx Zn0.2 (where x = 0.0, 0.1, 0.2, and 0.3) ferrites are prepared by a coprecipitation method to study the effect of Mn2+ions on the structural and morphological properties. These ferrites are characterized by X-ray powder diffraction (XRD), and Fourier transform infrared. X-ray diffraction patterns of the prepared samples confirm partial substitution of Mn2+ ions that does not change the basic structure of Co0.8 Zn0.2 Fe2O4. It also provides information about the formation of a single-phase spinel structure without any secondary phase. It is concluded that Co0.6 Mn0.2 Zn0.2 Fe2O4 has a spherical shape with an average particle size of 22.51 nm based on TEM, as confirmed by the XRD analysis. FT-IR analysis confirms the formation of vibrational frequency bands associated with the entire spinel structure. The IR spectra of ferrites show two clear and sharp absorption bands in the range of 442.09 and 620.21 cm-1 in the range of 200–1000 cm-1, which confirms the formation of the ferrite composite.

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Shedam, Rakesh M., Priyanka P. Kashid, Shridhar N. Mathad, Rahul B. Deshmukh, Mahadev R. Shedam und Ashok B. Gadkari. „Ferrites gas sensors: A Review“. Physics and Chemistry of Solid State 23, Nr. 3 (30.09.2022): 626–40. http://dx.doi.org/10.15330/pcss.23.3.626-640.

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Gas sensors that are highly sensitive, stable, and selective are increasingly in demand to detect toxic gases. As a result of the need to monitor concentrations of these gases, humans, animals, and the environment are all protected. Metal ferrites (AFe2O3, where A is a metal) are a major factor in this field. The development of ferrite gas sensors has made remarkable advances in the detection of toxic gases from vehicle exhaust, biological hazards, environmental monitoring, and pollution monitoring over the last decade. It is important for ferrite gas sensors to consider parameters like phase formation, crystallite size, particle size, grain size, dopants, surface area, sensitivity, selectivity, operating temperature, gas concentration, response time, and recovery time. There are various materials for gas sensing use such as carbon monoxide (CO), carbon dioxide (CO2), methane (CH4), ethyl alcohol (C2H5OH), hydrogen sulfide (H2S), C2H5COOH, oxygen (O2), hydrogen (H2), chlorine (Cl2), NH3, C4H10, CH3COOH, gasoline, acetylene, petrol, and liquefied petroleum gas (LPG). Various methods are used to prepare ferrite gas sensors. Additionally, a brief description is provided of the various methods employed for synthesizing ferrite gas sensors. A comprehensive survey of ferrites as gas sensors, such as nickel, copper, zinc, cadmium, cobalt, magnesium, manganese, and multi-component ferrites, prepared by various methods.

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Iacovita, Cristian, Gabriela Fabiola Stiufiuc, Roxana Dudric, Nicoleta Vedeanu, Romulus Tetean, Rares Ionut Stiufiuc und Constantin Mihai Lucaciu. „Saturation of Specific Absorption Rate for Soft and Hard Spinel Ferrite Nanoparticles Synthesized by Polyol Process“. Magnetochemistry 6, Nr. 2 (29.05.2020): 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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Rasool, G., M. S. Shifa, H. M. N. H. K. Asghar, Z. A. Gilani, A. Javid, M. M. Alam, S. M. Ali, M. A. Shar und H. S. Abdo. „Characterization of Bi substitution of strontium cobalt zinc ferrites synthesized by micro-emulsion technique“. Journal of Ovonic Research 19, Nr. 6 (20.12.2023): 695–704. http://dx.doi.org/10.15251/jor.2023.196.695.

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Strontium cobalt zinc bismuth ferrites with formula are provided in this study using formula Sr0.5Co0.4Zn0.4BixFe2-xO4 at different variation of x= 0.0, 0.05, 0.10, 0.15 synthesized by Micro-emulsion techniques. To check the physical characteristics of this series (Sr0.5Co0.4Zn0.4BixFe2-xO4) of nano-ferrites using FTIR (Fourier Transformation of infrared spectroscopy), UV-visible, X-ray diffraction and scanning electron microscope. SEM and XRD analysis were used to examine the structure and morphology of manufactured nano-ferrites. The spectra of XRD demonstrated the production of a single-phase cubic spinel ferrite structure in the nanometer size range with no minor phase. When extending metal-oxygen bonds at tetrahedral and octahedral sites, FTIR analysis showed two bands centered at 592 and 410 cm-1 . Using ultraviolet-DRS, we determined that band-gap range for the synthesised magnetic materials was between 2.42 and 2.32 eV.

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Santosh, Dr Santosh Kumar, Avinash Chand Yadav, Prabhat Ranjan Tiwari, Gulab Singh, Parasmani Rajput und Manvendra Kumar. „Synthesis and Characterization of Cobalt doped Zinc Ferrite for its Structural and Magnetic Properties“. Asian Journal of Chemistry 35, Nr. 10 (28.09.2023): 2461–67. http://dx.doi.org/10.14233/ajchem.2023.28210.

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In this work, the synthesis of cobalt doped zinc ferrites CoxZn1-xFe2O4 for x = 0, 0.1, 0.2 and 0.3 by sol-gel method followed by selfignition root is reported. The prepared materials in powder form were characterized by HRXRD, FTIR, SEM and VSM analysis for its structural, vibrational and magnetic properties. Single phase cubic structure having fd3m space group of the zinc ferrites was revealed by HRXRD technique. The minimum crystallite size of Co doped ZnFe2O4 was found to be 26.11 nm for x = 0.1. The effect of cobalt in the prepared composites was studied using VESTA and Match3! Software for the structural analysis. The FTIR spectra illustrate two bands in the range 565-544 cm-1 and 431-410 cm-1, which confirm the formation of the spinel ferrite phase. Vibrating sample magnetometer (VSM) was used for magnetic parameters like remanence, coercivity and saturation magnetization, etc. of the prepared nanomaterials.

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Bushkova, V. S. „Optical Properties of Ferrite Powders of NixCo1-xFe2O4 System“. Фізика і хімія твердого тіла 16, Nr. 3 (15.09.2015): 506–10. http://dx.doi.org/10.15330/pcss.16.3.506-510.

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The aim of this work was to create and study of ferrite nickel-cobalt powders, using sol-gel technology with participation of auto-combustion. It is studied the optical properties of the powders depending on the degree of substitution of cobalt cations on nickel cations. As a result of analysis of the absorption spectra is revealed that for all investigated powders inherent allowed direct transition of electrons from the valence band to the conduction band. It was shown that the optical band gap increases with increasing concentration of nickel cations in the composition of ferrites.

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Amirov, Abdulkarim, Alexander Omelyanchik, Dmitry Murzin, Valeria Kolesnikova, Stanislav Vorontsov, Ismel Musov, Khasan Musov, Svetlana Khashirova und Valeria Rodionova. „3D Printing of PLA/Magnetic Ferrite Composites: Effect of Filler Particles on Magnetic Properties of Filament“. Processes 10, Nr. 11 (16.11.2022): 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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Jain, Prachi, O. P. Thakur und S. Shankar Subramanian. „Structural, Dielectric and Impedance Phenomena in Copper Ferrite Nano Powders for Hydroelectric Cell Application“. Materials Science Forum 1099 (05.10.2023): 157–62. http://dx.doi.org/10.4028/p-4ou996.

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Multiferroic materials have become the new era of research because it exhibits the presence of more than two ferroic orderings in its same phase. The pure copper ferrite nano powders have been prepared using sol-gel auto combustion method. The particle size is found to be near about 30-40 nm. Pure copper ferrite nanoparticles have been chosen to prepare because of its improved dielectric and structural properties. The sharpened peaks obtained from the XRD diffraction pattern confirms the crystalline nature of the sample. The structural and impedance studies of pure copper ferrites has also been reported. The SEM analysis confirms the formation of nanoparticles by revealing the value of grain size in nanometer range. The dielectric studies exhibit the Maxwell Wagner polarization and impedance spectroscopy confirms the contribution in conductivity from both grains and grain boundaries at room temperature. The fabrication of hydroelectric cell having area=0.75 cm2 has been done using pure copper ferrite nanoparticles which have shown improved value of current in wet state as compared to other ferrites like cobalt ferrites and bismuth ferrites. These all properties are responsible for improving the structural stability and thus this material can be suggested for fabricating the hydroelectric cells.

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Abdullah, Minhal, Syed Hasany, Muhammad Amir Qureshi und Sajid Hussain. „Cost-Effective Synthesis of Cobalt Ferrite Nanoparticles by Sol-Gel Technique“. Materials Science Forum 1067 (10.08.2022): 213–19. http://dx.doi.org/10.4028/p-jdlq11.

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In material science, doping method is employed to produce nanoferrites with desired characteristics. Recently, cobalt doped iron oxide nanomaterials have gained importance in industry for multiple electronic/electrical applications. Large number of methods have been adopted for the synthesis of nanoparticles (NPs), but high manufacturing cost, uniform sized, and anisotropic behaviors limit the commercial applications. In the presented work, cobalt doped (Co-Fe nanomaterials) are developed by a cost-effective sol-gel approach. The doped cobalt ferrites NPs (1%, 2%, and 3% doping of cobalt) were prepared and characterized by XRD, SEM & TEM, FTIR, and VSM techniques. XRD and microscopic (SEM & TEM) analysis revealed synthesis of hexagonal structured cobalt ferrite sized from ~16nm to ~8nm, with the increasing doping pattern of Cobalt from 1% to 3%. FTIR analysis showed the formation of well-structured oxides, which is in strong agreement with XRD and microscopy techniques. Moreover, VSM analysis revealed that cobalt ferrite nanoparticles possess ferromagnetic properties with Ms, Mr and Hc values of 0.038emu/g, 0.005emu/g and 405.19Oe respectively. In addition, squareness (Mr/Ms = 0.16) indicates the presence of single domain spherical particles.

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Othéro de Brito, Vera Lúcia, Stéphanie Alá Cunha, Ana Paula Ribeiro Uchoas, Fabiana Faria de Araújo, Cristina Bormio Nunes und Luis Antonio Genova. „Evaluation of the Sinterability of Copper-Substituted Ferrites by Means of Dilatometric Thermal Analysis“. Materials Science Forum 805 (September 2014): 254–59. http://dx.doi.org/10.4028/www.scientific.net/msf.805.254.

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Cobalt and cobalt-manganese spinel ferrites have magnetostrictive properties suitable for application in magneto-electric and magneto-mechanical transducers. In this work, copper-substituted ferrites of these compositions were processed by means of the ceramic method and their sinterabilities were evaluated by dilatometric thermal analyses. The results obtained suggest that copper affects the solid-state reactions for the spinel formation and lowers the required sintering temperature for the ferrites. However, the densification obtained with sintering of the copper-substituted ferrites at 950oC for 6h was only 64%, which indicates that further adjustments on the processing route must be made in order to obtain higher densities.

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Jain, Prachi, S. Shankar und O. P. Thakur. „Production of Green energy via Water Splitting mechanism by Mn- doped cobalt ferrites [Co1-xMnxFe2O4] based hydroelectric cells“. Current Natural Sciences and Engineering 1, Nr. 2 (29.03.2024): 37–45. http://dx.doi.org/10.63015/2h-2419.1.2.

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In our current study, we have investigated the impact of manganese (Mn) doping on the structural, magnetic properties, and hydroelectric cell properties of cobalt ferrite with chemical formula [Co1-xMnxFe2O4, x=0.00, 0.125]. The solid-state approach has been utilized to synthesize the material. XRDmeasurements revealed the formation of an inverse spinel cubic structure with the space group Fd-3m. FTIR spectra hold a shift in the octahedral and tetrahedral bands with the increase in Mn content in cobalt ferrites. The subsequent rise in ferroelectric behavior has been observed with the net maximum saturation polarization of 1.08μC/cm2. The variation in the permittivity values has been also studied with the increase in Mn content for dry as well as wet hydroelectric cells. The impedance measurements helped us understand the contribution of grains/grain boundaries in the prepared ferrites. The enhanced value of magnetization has been noticed from 48.258 emu/g to 73.089 emu/g upon doping of Mn ions in cobalt ferrite spinel structure lattice.The Mndoped CFO exhibited enhanced performance in hydroelectric cells which demonstrates the great ionic diffusion mechanism with the incorporation of Mn ions. The obtained output makes Mn doped CFO a suitable material for studying microelectronic and hydroelectric cell applications. The purpose of this study is to enhance both ferroelectric as well as ferromagnetic behavior along with the improved value of current in hydroelectric cells.

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Changwal, R., R. Ameta und S. C. Ameta. „Oxidation of benzyl alcohols by molecular oxygen catalyzed by cobalt ferrite“. Research Journal of Chemistry and Environment 28, Nr. 1 (05.12.2023): 91–97. http://dx.doi.org/10.25303/281rjce91097.

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Oxidation of alcohols to aldehydes/ketones/carboxylic acids is a crucial step in organic synthesis. Normally, strong oxidants oxidize alcohol to carboxylic acid and this reaction may or may not stop at the intermediate steps to form aldehyde and ketone. Some mild oxidants are required to stop it here at this stage. Here, molecular oxygen can help in achieving this objective, but there is a disadvantage to use molecular oxygen as an oxidant as it has a slow rate of oxidation. Hence, such a reaction may be catalyzed by metal ferrites. These metal ferrites are easy to separate by using an external magnet and can be recycled. Cobalt ferrite has been used for the oxidation of benzyl alcohols to corresponding benzaldehydes.

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Beera, Chandra Sekhar, B. Dhanalakshmi, D. Nirmala Devi, D. Vijayalakshmi, Akanksha Mishra, S. Ramesh, B. Parvatheeswara Rao et al. „Magnetic and Magnetostrictive Properties of Sol–Gel-Synthesized Chromium-Substituted Cobalt Ferrite“. Gels 9, Nr. 11 (02.11.2023): 873. http://dx.doi.org/10.3390/gels9110873.

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Chromium (Cr)-doped cobalt ferrite nanoparticles were synthesized using a sol–gel autocombustion method, with the chemical formula CoCrxFe2xO4. The value of x ranged from 0.00 to 0.5 in 0.1 increments. X-ray diffraction analysis confirmed the development of highly crystalline cubic spinel structures for all samples, with an average crystallite size of approximately 40 to 45 nm determined using the Scherrer equation. Pellets were prepared using a traditional ceramic method. The magnetic and magnetostrictive properties of the samples were tested using strain gauge and VSM (vibrating sample magnetometer) techniques. The results of the magnetic and magnetostrictive tests showed that the chromium-substituted cobalt ferrites exhibited higher strain derivative magnitudes than pure cobalt ferrite. These findings indicated that the introduction of chromium into the cobalt ferrite structure led to changes in the material’s magnetic properties. These changes were attributed to anisotropic contributions, resulting from an increased presence of Co2+ ions at B-sites due to the chromium substitutions. In summary, this study concluded that introducing chromium into the cobalt ferrite structure caused alterations in the material’s magnetic properties, which were explained by changes in the cationic arrangement within the crystal lattice. This study successfully explained these alterations using magnetization and coercivity data and the probable cationic dispersion.

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Rostamzadehmansoor, S., Mirabdullah Seyed Sadjadi, K. Zare und Nazanin Farhadyar. „Preparation of Ferromagnetic Manganese Doped Cobalt Ferrite-Silica Core Shell Nanoparticles for Possible Biological Application“. Defect and Diffusion Forum 334-335 (Februar 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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Abdul Aziz, Siti Aishah, Saiful Amri Mazlan, U. Ubaidillah, Muhammad Kashfi Shabdin, Nurul Azhani Yunus, Nur Azmah Nordin, Seung-Bok Choi und Rizuan Mohd Rosnan. „Enhancement of Viscoelastic and Electrical Properties of Magnetorheological Elastomers with Nanosized Ni-Mg Cobalt-Ferrites as Fillers“. Materials 12, Nr. 21 (28.10.2019): 3531. http://dx.doi.org/10.3390/ma12213531.

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Carbon-based particles, such as graphite and graphene, have been widely used as a filler in magnetorheological elastomer (MRE) fabrication in order to obtain electrical properties of the material. However, these kinds of fillers normally require a very high concentration of particles to enhance the conductivity property. Therefore, in this study, the nanosized Ni-Mg cobalt ferrite is introduced as a filler to soften MRE and, at the same time, improve magnetic, rheological, and conductivity properties. Three types of MRE samples without and with different compositions of Mg, namely Co0.5Ni0.2Mg0.3Fe2O4 (A1) and Co0.5Ni0.1Mg0.4Fe2O4 (A2), are fabricated. The characterization related to the micrograph, magnetic, and rheological properties of the MRE samples are analyzed using scanning electron microscopy (SEM), vibrating sample magnetometer (VSM), and the rheometer. Meanwhile, the effect of the nanosized Ni-Mg cobalt ferrites on the electrical resistance property is investigated and compared with the different Mg compositions. It is shown that the storage modulus of the MRE sample with the nanosized Ni-Mg cobalt ferrites is 43% higher than that of the MRE sample without the nanomaterials. In addition, it is demonstrated that MREs with the nanosized Ni-Mg cobalt ferrites exhibit relatively low electrical resistance at the on-state as compared to the off-state condition, because MRE with a higher Mg composition shows lower electrical resistance when higher current flow occurs through the materials. This salient property of the proposed MRE can be effectively and potentially used as an actuator to control the viscoelastic property of the magnetic field or sensors to measure the strain of the flexible structures by the electrical resistance signal.

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Tsoncheva, Tanya, Radostina Ivanova, Nikolay Velinov, Daniela Kovacheva, Ivanka Spassova, Daniela Karashanova und Nartzislav Petrov. „Design and Catalytic Behaviour of Hosted in Activated Carbon Foam CoxZn1−xFe2O4 Ferrites“. Symmetry 13, Nr. 8 (20.08.2021): 1532. http://dx.doi.org/10.3390/sym13081532.

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Carbon foams with different surface functionality and tailored texture characteristics were prepared from mixtures containing coal tar pitch and furfural in different proportions. The obtained materials were used as a host matrix for the preparation of zinc- and cobalt-mixed ferrite nanoparticles. The texture, morphology, phase composition, and the related redox and catalytic properties of the obtained composites were characterized by low-temperature nitrogen physisorption, XRD, SEM, HRTEM, FTIR, Mössbauer spectroscopy, TPR and catalytic decomposition of methanol to syngas. The impact of the carbon support on the formation of Co- and Zn-mixed ferrites was discussed in detail using KIT-6 silica-based modifications as reference samples. The catalytic behavior of the ferrites was considered in a complex relation to their composition, morphology, location in the porous matrix and metal ions distribution in the spinel sub-lattices. The higher amount of furfural in the carbon foam precursor promoted the formation of cobalt-rich, more accessible and highly active methanol decomposition to syngas spinel particles.

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Nandiyanto, Asep Bayu Dani, Yustika Desti Yolanda, Mia Widyaningsih, Risti Ragadhita, Herry Saputra, Eddy Soeryanto Soegoto und Senny Luckyardi. „Techno-Economic Evaluation of the Production of Dysprosium-Doped Cobalt Ferrites Nanoparticles by Sol-Gel Auto-Combustion Method“. Mathematical Modelling of Engineering Problems 9, Nr. 4 (31.08.2022): 1152–59. http://dx.doi.org/10.18280/mmep.090435.

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The purpose of this study was to examine two models of the economic feasibility of producing nanoparticle of dysprosium-doped cobalt ferrites by sol-gel auto-combustion method, from a laboratory scale to an industrial scale, including technical analysis and economic evaluation. Various economic evaluation parameters were analyzed to report the fabrication potential of dysprosium-doped cobalt ferrites nanoparticles in the case of the time required for a speculation to recover its total initial expenditure (PBP), the conditions of a generating project in the production function in years (CNPV), undertaking profits, etc. The results of the economic feasibility study on the production of dysprosium-doped cobalt ferrites nanoparticles showed that all parameter changes gave positive values, demonstrating that this project might have been practical to run commercially and on a large scale. Technical analysis to produce 26.4 tons of dysprosium-doped cobalt ferrites nanoparticles per year reveals that investment will be gainful then afterward more than three years. This project emulates PBP capital market guidelines due to the crisp return on investment. Estimates range from ideal to worst-case states in production to ensure project feasibility, including labor, sales, crude materials, utilities, external factors, and taxes.

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Choudary, G. S. V. R. K., P. Prameela, M. Chaitanya Varma, A. Mahesh Kumar und K. H. Rao. „Contribution to Analysis of Co/Cu Substituted Ni-Zn Ferrites“. Indian Journal of Materials Science 2013 (24.10.2013): 1–7. http://dx.doi.org/10.1155/2013/350707.

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In this communication, Co/Cu substituted Ni-Zn ferrites processed through sol-gel synthesis using polyethylene glycol (PEG) as a chelating agent are studied, intending to aid in understanding and choosing the optimum ferrite material for high frequency applications. Lattice constant and average crystallite size have been estimated from FWHM of the X-ray diffraction peaks, and these parameters are understood by considering the ionic radii of the substituted as well as the replacing ions. Observed variations in saturation magnetization and initial permeability for these ferrites have been explained on the basis of anisotropy contribution for cobalt and segregation of copper at grain boundaries evident from scanning electron micrographs.

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Rendale, Maruti K., S. N. Mathad und Vijaya Puri. „Structural, mechanical and elastic properties of Ni0.7−xCoxZn0.3Fe2O4 nano-ferrite thick films“. Microelectronics International 34, Nr. 2 (02.05.2017): 57–63. http://dx.doi.org/10.1108/mi-02-2016-0009.

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Purpose The present communication aims to investigate the influence of cobalt substitution on the structural, mechanical and elastic properties of nickel–zinc ferrite thick films. The changes observed in the crystallite size (D), lattice constant (a), texture coefficient [TC(hkl)] and mechanical and elastic properties of the thick films due to cobalt substitution have been reported systematically. Design/methodology/approach Ni–Zn ferrites with the stoichiometric formula Ni0.7−xCoxZn0.3Fe2O4 (where, x = 0, 0.04, 0.08, 0.12, 0.16 and 0.20) were synthesized via solution combustion technique using sucrose as the fuel and poly-vinyl-alcohol as the matrix material. The thick films of the ferrites were fabricated on alumina substrates by the screen printing method. The thickness of the films was 25 μm, as measured by the gravimetric method. The thick films were subjected to X-ray diffraction and Fourier transform infrared spectroscopy. Findings The detailed study of variation of lattice parameter (a), sintering density, micro-strain and elastic properties with cobalt (Co+2) substituted was carried out. The remarkable increase in lattice parameter (from 8.369 A° to 8.3825 A°), bulk density and average grain size (69-119 nm) with the cobalt content was due to larger ionic radius of Co2+ compared to Ni2+. Texture analysis [TC(hkl)] reveals all thick films have adequate grain growth in the (311) plane direction. The main absorption bands of spinel ferrite have appeared through infrared absorption spectra recorded in the range of 300-700 cm−1. Originality/value The variation in stiffness constants (for isotropic material, C11 = C12), longitudinal elastic wave (Vl), transverse elastic wave (Vt), mean elastic velocity (VMean), rigidity modulus (G), Poisson’s ratio(s) and Young’s modulus (E) with cobalt (Co+2) composition has been interpreted in terms of binding forces found.

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Balatskiy, Denis, Yulia Budnikova, Svetlana Bratskaya und Marina Vasilyeva. „TiO2-CoFe2O4 and TiO2-CuFe2O4 Composite Films: A New Approach to Synthesis, Characterization, and Optical and Photocatalytic Properties“. Journal of Composites Science 7, Nr. 7 (16.07.2023): 295. http://dx.doi.org/10.3390/jcs7070295.

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Here, we report a new simple and fast method of cobalt and copper ferrites film fabrication on the Ti/TiO2 surface. The approach is based on the deposition of gelatin gel containing copper and cobalt nitrates on the surface of porous oxide-silicon coatings on titanium obtained by plasma electrolytic oxidation (PEO) followed by two-stage annealing at 300 °C and 800 °C to yield ferrite films with good adhesion to PEO layer. The presence of Co/Cu ferrite phases was confirmed by EDX analysis, XRD, and Mössbauer spectroscopy. TiO2-CoFe2O4 and TiO2-CuFe2O4 composite films have excellent performance in the photocatalytic degradation of indigo carmine as a model dye at pH 3 under UV and visible irradiation. The suggested approach to obtain ferrite/TiO2 composite films is promising for the development of magnetic materials, sensors, catalysts, and photocatalysts for various applications.

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Elsayed, Elsayed M., Hazem F. Khalil, Ibrahim A. Ibrahim, Mostafa R. Hussein und Mohamed M. B. El-Sabbah. „The Significance of Buffer Solutions on Corrosion Processes of Cobalt Ferrite CoFe2O4 Thin Film on Different Substrates“. Combinatorial Chemistry & High Throughput Screening 23, Nr. 7 (05.10.2020): 599–610. http://dx.doi.org/10.2174/1386207323666191217130209.

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Background: The spinel ferrite nanoparticles, such as zinc, nickel, and cobalt ferrites have exceptional electronic and magnetic properties. Cobalt ferrite nanomaterial (CoFe2O4) is a hard material that reveals high magnetic, mechanical, and chemical stability. Aim and Objective: The objective of this research is to predict the corrosion behavior of cobalt ferrite (CoFe2O4) thin films deposited on different substrates (platinum Pt, stainless steel S.S, and copper Cu) in acidic, neutral, and alkaline medium. Materials and Method: Cobalt ferrite thin films were deposited on platinum, stainless steel, and copper via electrodeposition-anodization process. After that, corrosion resistance of the prepared nanocrystalline cobalt ferrite on different substrates was investigated in acidic, neutral, and alkaline medium using open circuit potential and potentiodynamic polarization measurements. The crystal structure, crystallite size, microstructure, and magnetic properties of the ferrite films were investigated using a combination of XRD, SEM and VSM. Results: The results of XRD revealed a cubic spinel for the prepared cobalt ferrite CoFe2O4. The average size of crystallites was found to be about 43, 77, and 102 nm precipitated on platinum, stainless steel, and copper respectively. The magnetic properties of which were enhanced by rising the temperature. The sample annealed at 800oC is suitable for practical application as it showed high magnetization saturation and low coercivity. The corrosion resistance of these films depends on the pH of the medium as well as the presence of oxidizing agent. Conclusion: Depending on the obtained corrosion rate, we can recommend that, CoFe2O4 thin film can be used safely in aqueous media in neutral and alkaline atmospheres for Pt and Cu substrates, but it can be used in all pH values for S.S. substrate.

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Lin, Qing, Jinpei Lin, Yun He, Ruijun Wang und 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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Manimegalai, R., S. Sendhilnathan, V. Chithambaram und M. Kumar. „Experimental investigation on ferrofluid properties of Cd doped Co-Zn ferrites“. Digest Journal of Nanomaterials and Biostructures 18, Nr. 2 (01.05.2023): 547–55. http://dx.doi.org/10.15251/djnb.2023.182.547.

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The Co-Zn ferrites 𝐶𝐶𝐶𝐶0.5𝑍𝑍𝑍𝑍0.5𝐶𝐶𝐶𝐶𝑥𝑥𝐹𝐹𝐹𝐹(2−𝑥𝑥)𝑂𝑂4 (x-0.0, 0.1, 0.2, 0.3, 0.4, and 0.5) were synthesized by CO-precipitation method. The dielectric and structural properties has been investigated by effect of Cd doping in Co-Zn spinel ferrites. Dielectric constants were studied dependence of the frequency and temperature thus revealed that the dielectric dispersion based on the MaxwellWagner method polarizations are agreed with Koop’s conceptualization theory. Further, dielectric properties were studies over a frequency range from 10 kHZ to 30 MHZ. The dielectric constant is varied from 2.4 to 8.4 for real parts and 0.008 to 0.42 for imaginary parts, respectively. The tangent loss also recorded as 0.003 to 0.052 at 1 MHZ due to Co ions concentrations. In high and low frequencies of grain and grain boundary contribution is an important evident for obtained dielectric constant. The obtained values of coercivity (Hc) for these ferrites range between 280.4 Oe to 1380.3 Oe, based on VSM data. By converting Zn2+ and Cd2+ to cobalt magnetic ions it is possible to convert the magnetic properties of cobalt ferrite into a potential individual for numerous technical uses. The dielectric loss at room temperature and at high frequencies is found to be quite negligible. It is also discovered that when Cd is substituted, the dielectric loss tangent reduces.

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Assem, E. E., A. M. Abden und O. M. Hemada. „Thermal Properties of Cobalt Cadmium Ferrites“. Key Engineering Materials 224-226 (Juni 2002): 831–34. http://dx.doi.org/10.4028/www.scientific.net/kem.224-226.831.

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Kale, G. M., und T. Asokan. „Electrical properties of cobalt‐zinc ferrites“. Applied Physics Letters 62, Nr. 19 (10.05.1993): 2324–25. http://dx.doi.org/10.1063/1.109405.

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Lenglet, M., F. Hochu und J. Dürr. „Optical Properties of Mixed Cobalt Ferrites“. Le Journal de Physique IV 07, Nr. C1 (März 1997): C1–259—C1–260. http://dx.doi.org/10.1051/jp4:19971100.

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Caltun, Ovidiu, Ioan Dumitru, Marcel Feder, Nicoleta Lupu und Horia Chiriac. „Substituted cobalt ferrites for sensors applications“. Journal of Magnetism and Magnetic Materials 320, Nr. 20 (Oktober 2008): e869-e873. http://dx.doi.org/10.1016/j.jmmm.2008.04.067.

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Velinov, Nikolay, Kremena Koleva, Tanya Tsoncheva, Daniela Paneva, Elina Manova, Krassimir Tenchev, Boris Kunev, Izabela Genova und Ivan Mitov. „Copper-cobalt ferrites as catalysts for methanol decomposition“. Open Chemistry 12, Nr. 2 (01.02.2014): 250–59. http://dx.doi.org/10.2478/s11532-013-0371-8.

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AbstractCopper-cobalt ferrites with composition Cu1−xCoxFe2O4, where x= 0.2 and 0.8 were prepared by thermal treatment of co-precipitated precursor. The obtained materials were characterized by TG-DSC, XRD, Transmission and Conversion Electron Mössbauer spectroscopy and temperature programmed reduction with hydrogen. The catalytic properties of ferrites were tested in methanol decomposition to CO and hydrogen.

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Andrade, Priscyla L., Valdeene A. J. Silva, Kathryn L. Krycka, Juscelino B. Leão, I.-Lin Liu, Maria P. C. Silva und J. Albino Aguiar. „The effect of organic coatings in the magnetization of CoFe₂O₄ nanoparticles“. AIP Advances 12, Nr. 8 (01.08.2022): 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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