Journal articles: 'Ferrite de cobalt'

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Majid, Farzana, Amarah Nazir, Sadia Ata, Ismat Bibi, Hafiz Shahid Mehmood, Abdul Malik, Adnan Ali, and Munawar Iqbal. "Effect of Hydrothermal Reaction Time on Electrical, Structural and Magnetic Properties of Cobalt Ferrite." Zeitschrift für Physikalische Chemie 234, no. 2 (February 25, 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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de la Torre, Ernesto, Ana Lozada, Maricarmen Adatty, and Sebastián Gámez. "Activated Carbon-Spinels Composites for Waste Water Treatment." Metals 8, no. 12 (December 16, 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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Zhang, Chang Sen, Lei Yang, and 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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Gupta, Meenal, Anusree Das, Dipankar Das, Satyabrata Mohapatra, and 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, no. 8 (August 1, 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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Elsayed, Elsayed M., Hazem F. Khalil, Ibrahim A. Ibrahim, Mostafa R. Hussein, and 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, no. 7 (October 5, 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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Alotaibi, M. A., I. Ud Din, A. I. Alharthi, P. Ahmad, A. Naeem, I. A. ElSayed, and G. Centi. "Synthesis, Characterization, and Magnetic Behavior of Cobalt-Ferrite Nanoparticles under Variant Temperature Conditions." Физика твердого тела 63, no. 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, and G. Centi. "Synthesis, Characterization, and Magnetic Behavior of Cobalt-Ferrite Nanoparticles under Variant Temperature Conditions." Физика твердого тела 63, no. 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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Jha, Anal K., and Kamal Prasad. "Biological synthesis of cobalt ferrite nanoparticles." Nanotechnology Development 2, no. 1 (July 11, 2012): 9. http://dx.doi.org/10.4081/nd.2012.e9.

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A low-cost green and reproducible yeast (<em>Saccharomyces cerevisiae</em>) mediated biosynthesis of cobalt ferrite nanoparticles is reported. The synthesis is performed at close to room temperature in the laboratory. X-ray, Fourier transform infrared spectroscopy and high resolution transmission electron microscopy analyses are performed to ascertain the formation of cobalt ferrite nanoparticles. Individual nanoparticles, as well as a very few aggregate having the size of 3-15 nm, were found. The vibrating sample magnetometer measurement showed superparamagnetic behavior in cobalt ferrite nanoparticles. The mechanism involved in the biosynthesis of cobalt ferrite nanoparticles has also been discussed.

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Boss, Alan F. N., Antonio C. C. Migliano, and Ingrid Wilke. "The Influence of Stoichiometry on the Index of Refraction of Cobalt Ferrite Samples at Terahertz Frequencies." MRS Advances 2, no. 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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Sanpo, Noppakun, James Wang, and Christopher C. Berndt. "Effect of Zinc Substitution on Microstructure and Antibacterial Properties of Cobalt Ferrite Nanopowders Synthesized by Sol-Gel Methods." Advanced Materials Research 535-537 (June 2012): 436–39. http://dx.doi.org/10.4028/www.scientific.net/amr.535-537.436.

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Zinc substituted cobalt ferrite nanopowders with the general formula Co(1-x)ZnxFe2O4(with x = 0, 0.3, 0.5, 0.7, and 1) were prepared via the sol-gel route using citric acid as a chelating agent. The influence of zinc concentration on the microstructure, crystal structure and antibacterial property of zinc substituted cobalt ferrite nanopowders has been systematically investigated. The microstructure and elemental composition were characterized using scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX), respectively. Phase analysis of cobalt ferrite nanopowders was performed using X-ray diffractometry (XRD). The antibacterial properties of zinc substituted cobalt ferrite nanopowders were investigated. The results indicate that the substitution of zinc influences strongly the microstructure, crystal structure and antibacterial property of the cobalt ferrite nanopowders.

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Kikuchi, Takeyuki, Tatsuya Nakamura, Masamichi Miki, Makoto Nakanishi, Tatsuo Fujii, Jun Takada, and Yasunori Ikeda. "Synthesis of Hexagonal Ferrites by Citric Complex Method." Advances in Science and Technology 45 (October 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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Bushkova, V. S. "Optical Properties of Ferrite Powders of NixCo1-xFe2O4 System." Фізика і хімія твердого тіла 16, no. 3 (September 15, 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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Ortega López, Yudith, Hugo Medina Vázquez, Jesús Salinas Gutiérrez, Vanessa Guzmán Velderrain, Alejandro López Ortiz, and 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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Nakamura, Satoshi, Wataru Sakamoto, and Toshinobu Yogo. "In situ synthesis of nano-sized cobalt ferrite particle/organic hybrid." Journal of Materials Research 21, no. 5 (May 1, 2006): 1336–41. http://dx.doi.org/10.1557/jmr.2006.0165.

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A CoFe2O4 particle/organic hybrid was synthesized using in situ processing of metalorganics of cobalt and iron below 100 °C. A mixture of cobalt (II) acetylacetonate (CA) and iron (III) 3-allylacetylacetonate (IAA) was hydrolyzed and polymerized yielding cobalt ferrite particle/organic hybrid. The crystallinity of cobalt ferrite depended upon the hydrolysis conditions of cobalt acetylacetonate-iron 3-allylacetylacetonate (CA-IAA). Nanocrystalline cobalt ferrite particles were uniformly dispersed in the organic matrix. The saturation magnetization of hybrid increased with increasing crystallinity of cobalt ferrite particles in the organic matrix. The hybrid showed a magnetization-applied field (BH) curve with no coercive force at room temperature. The magnetization versus H/T curves from 150 to 300 K were superimposed on the same curve and satisfied the Langevin equation. The hybrid revealed a saturation magnetization of 33.7 emu/g and a coercivity of 11 kOe at 4.2 K.

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Goswami, Partha P., Hanif A. Choudhury, Sankar Chakma, and 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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Yahya, Noorhana, Muhammad Kashif, Nadeem Nasir, Majid Niaz Akhtar, and Noorasikin Mohd Yusof. "Cobalt Ferrite Nanoparticles: An Innovative Approach for Enhanced Oil Recovery Application." Journal of Nano Research 17 (February 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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Sanpo, Noppakun, James Wang, and Christopher C. Berndt. "Sol-Gel Synthesized Copper-Substituted Cobalt Ferrite Nanoparticles for Biomedical Applications." Journal of Nano Research 22 (May 2013): 95–106. http://dx.doi.org/10.4028/www.scientific.net/jnanor.22.95.

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Copper-substituted cobalt ferrite nanoparticles were prepared via a sol-gel route using citric acid as a chelating agent. The influence of copper concentration on the microstructure, crystal structure and antibacterial property of copper-substituted cobalt ferrite nanoparticles against E. coli and S. aureus has been systematically investigated. The results indicate that the substitution of copper influences strongly the microstructure, crystal structure, particle diameter and antibacterial property of cobalt ferrite nanoparticles.

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Sanpo, Noppakun, James Wang, and Christopher C. Berndt. "Sol-Gel Synthesized Copper-Substituted Cobalt Ferrite Nanoparticles for Biomedical Applications." Journal of Nano Research 25 (October 2013): 110–21. http://dx.doi.org/10.4028/www.scientific.net/jnanor.25.110.

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Copper-substituted cobalt ferrite nanoparticles were prepared via a sol-gel route using citric acid as a chelating agent. The influence of copper concentration on the microstructure, crystal structure and antibacterial property of copper-substituted cobalt ferrite nanoparticles against E. coli and S. aureus has been systematically investigated. The results indicate that the substitution of copper influences strongly the microstructure, crystal structure, particle diameter and antibacterial property of cobalt ferrite nanoparticles.

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Barbosa, J. G., Bernardo G. Almeida, João P. Araújo, João Bessa Sousa, and Jorge A. Mendes. "Structural and Magnetic Properties of Nanogranular BaTiO₃-CoFe₂O₄ Thin Films Deposited by Laser Ablation on Si/Pt Substrates." Materials Science Forum 587-588 (June 2008): 303–7. http://dx.doi.org/10.4028/www.scientific.net/msf.587-588.303.

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Thin film nanocomposites of cobalt ferrite (CoFe2O4) dispersed in barium titanate (BaTiO3) matrix, have been deposited with different cobalt ferrite concentrations (from 20% to 70% CoFe2O4), as well as pure barium titanate and cobalt ferrite thin films (end members). The films were prepared by pulsed laser ablation on platinum covered Si(001) substrates. The films structure was studied by X-ray diffraction and their surface was examined by scanning electron microscopy (SEM). The magnetic properties were measured in a SQUID magnetometer. The results show that the deposited films are polycrystalline with a slight (111) barium titanate phase orientation and (311) CoFe2O4 phase orientation. The grain sizes measured from the X-ray diffraction peak widths, for both phases, are in the range 40nm to 100nm. However, as the concentration of the cobalt ferrite increases, the grain size of the BaTiO3 phase decreases, from 100nm to 30nm, up to 40% CoFe2O4 concentration beyond which the BaTiO3 grain size has an approximately constant value near 30nm. On the other hand the cobalt ferrite grain size does not show a clear trend with increasing cobalt ferrite concentration, fluctuating in the range 20nm to 30nm. The magnetic measurements show an increase of the magnetic moment from the low concentration region where the magnetic grains are more isolated and their magnetic interaction is small, towards the bulk value at higher CoFe2O4 concentrations. Also, a strong reduction of the magnetization with increasing temperature was observed, due to the corresponding decrease of the magnetocristalline anisotropy of the cobalt ferrite.

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Rostamzadehmansoor, S., Mirabdullah Seyed Sadjadi, K. Zare, and Nazanin Farhadyar. "Preparation of Ferromagnetic Manganese Doped Cobalt Ferrite-Silica Core Shell Nanoparticles for Possible Biological Application." Defect and Diffusion Forum 334-335 (February 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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Denisova, Kristina, Alexander A. Ilyin, Ruslan Rumyantsev, Julia Sakharova, Alexander P. Ilyin, and Natalya Gordina. "Low-Temperature Synthesis and Catalytic Activity of Cobalt Ferrite in Nitrous Oxide (N2O) Decomposition Reaction." Catalysts 11, no. 8 (July 22, 2021): 889. http://dx.doi.org/10.3390/catal11080889.

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Cobalt ferrite (CoFe2O4) nanoparticles were synthesized and investigated as a catalyst in the reaction of nitrous oxide (N2O) decomposition. Cobalt ferrite was synthesized by solid–phase interaction at 1100 °C and by preliminary mechanochemical activation in a roller-ring vibrating mill at 400 °C. The nanoparticles were characterized by X-ray diffraction (XRD), synchronous thermal analysis (TG and DSC) and scanning electron microscopy (SEM). A low-temperature nitrogen adsorption/desorption test was used to evaluate the catalytic activity of the cobalt ferrite nanoparticles. Correlations between the structure and catalytic properties of the catalysts are reported. The highest catalytic activity of CoFe2O4 in the reaction of nitrous oxide decomposition was 98.1% at 475 °C for cobalt ferrite obtained by mechanochemical activation.

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Basantakumar Sharma, H. "Multiferroic bismuth ferrite thin film and bismuth ferrite-cobalt ferrite nanocomposites." Ferroelectrics 516, no. 1 (August 18, 2017): 90–97. http://dx.doi.org/10.1080/00150193.2017.1362289.

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Nlebedim, I. C., and D. C. Jiles. "Effect of Mg-Substitution on the Magnetic Properties of Cobalt Ferrite." Key Engineering Materials 605 (April 2014): 287–89. http://dx.doi.org/10.4028/www.scientific.net/kem.605.287.

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In this study, we have substituted Mg into cobalt ferrite to investigate the effect on magnetic properties. The effect is different compared to other cation substitution studies on cobalt ferrite. An interesting observation is that the variation of magnetocrystalline anisotropy, due to Mg-substitution, is comparable with increasing Mg concentration. Similar trend was previously reported on the effect of Mg-substitution of the magnetostrictive properties of cobalt ferrite. Coercive field varies more significantly with Mg-substitution.

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Yuan, Yue, Shicheng Wei, Yi Liang, Bo Wang, and Yujiang Wang. "Effect of Solvothermal Reaction-Time on Microstructure and Microwave Absorption Properties of Cobalt Ferrite." Materials 13, no. 23 (November 25, 2020): 5331. http://dx.doi.org/10.3390/ma13235331.

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Cobalt ferrite is synthesized via a simple solvothermal method. Then, the effect of the degree of cobalt-ferrite growth on its morphology, structure, electromagnetic performance, and microwave absorption is studied as a function of the solvothermal reaction time. When the reaction time during synthesis is 8 h, the structure of cobalt ferrite is hollow spheres. In addition, when the reaction time is 12 h and 16 h, it becomes a submicron sphere with a diameter of 100–150 nm. With the increase of reaction time, cobalt ferrite underwent the process of cobalt ferrite formation, hollow structure formation, hollow structure disappearance, agglomeration separation and reagglomeration in 4–16 h. In general, CoFe2O4-8h shows better microwave absorption-the effective absorption bandwidth is 9.84 GHz (6–15.84 GHz) for a thickness of 1.72–3.72 mm. This represents a minimum return loss of −47.24 dB. A better understanding of both the synthesis parameters and the relationship between structure and electromagnetic properties can open new possibilities for applications and the development of microwave absorbing materials.

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Lin, Qing, Jinpei Lin, Yun He, Ruijun Wang, and 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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Hochu, F., and 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, no. 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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Gingasu, Dana, Ioana Mindru, Luminita Patron, Jose Maria Calderon-Moreno, Oana Catalina Mocioiu, Silviu Preda, Nicolae Stanica, et al. "Green Synthesis Methods of CoFe2O4and Ag-CoFe2O4Nanoparticles Using Hibiscus Extracts and Their Antimicrobial Potential." Journal of Nanomaterials 2016 (2016): 1–12. http://dx.doi.org/10.1155/2016/2106756.

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The cobalt ferrite (CoFe2O4) and silver-cobalt ferrite (Ag-CoFe2O4) nanoparticles were obtained through self-combustion and wet ferritization methods using aqueous extracts ofHibiscus rosa-sinensisflower and leaf. X-ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy, and magnetic measurements were used for the characterization of the obtained oxide powders. The antimicrobial activity of the cobalt ferrite and silver-cobalt ferrite nanoparticles against Gram-positive and Gram-negative bacteria, as well as fungal strains, was investigated by qualitative and quantitative assays. The most active proved to be the Ag-CoFe2O4nanoparticles, particularly those obtained through self-combustion using hibiscus leaf extract, which exhibited very low minimal inhibitory concentration values (0.031–0.062 mg/mL) against all tested microbial strains, suggesting their potential for the development of novel antimicrobial agents.

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Peter, Emy Rose, Jismon Sebastian, and Swapna S. Nair. "Preparation of Nano Ink Using Cobalt Ferrite and Barium Titanate for Printed Electronic Devices." International Journal of Research in Engineering, Science and Management 3, no. 10 (October 24, 2020): 132–35. http://dx.doi.org/10.47607/ijresm.2020.351.

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Lead in our body is toxic and hazardous. Here leadfree Cobalt ferrite and Barium Titanate inks have been prepared and fabricated. The prepared inks remained stable without agglomeration or condensation during preservation. Cobalt Ferrite and Barium Titanate Nano inks have been characterized using X-ray diffraction method and UV Visible Spectroscopy. By the analysis of X-ray diffraction (XRD), the resultant inks were confirmed to be of pure Cobalt Ferrite and Barium Titanate powders with cubic structure and tetragonal structure respectively. Lattice parameters and grain size have been determined by X-ray diffraction method. UV Visible Spectroscopy analysis has been done to obtain the band gap energy of the prepared inks. The preparation and characterization of Cobalt Ferrite and Barium Titanate Nano inks are comprehensively demonstrated in this paper.

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Rendale, Maruti K., S. N. Mathad, and Vijaya Puri. "Structural, mechanical and elastic properties of Ni0.7−xCoxZn0.3Fe2O4 nano-ferrite thick films." Microelectronics International 34, no. 2 (May 2, 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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Iacovita, Cristian, Gabriela Fabiola Stiufiuc, Roxana Dudric, Nicoleta Vedeanu, Romulus Tetean, Rares Ionut Stiufiuc, and Constantin Mihai Lucaciu. "Saturation of Specific Absorption Rate for Soft and Hard Spinel Ferrite Nanoparticles Synthesized by Polyol Process." Magnetochemistry 6, no. 2 (May 29, 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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Boutiuc, Luminita Mirela, Ioan Dumitru, Ovidiu Florin Caltun, M. Feder, and V. Vilceanu. "Coprecipitated Cobalt Ferrite for Sensors." Sensor Letters 7, no. 3 (June 1, 2009): 244–46. http://dx.doi.org/10.1166/sl.2009.1067.

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Mosivand, Saba, and Iraj Kazeminezhad. "Synthesis of electrocrystallized cobalt ferrite nanopowders by tuning the cobalt salt concentration." RSC Advances 5, no. 19 (2015): 14796–803. http://dx.doi.org/10.1039/c4ra17162d.

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To Loan, Nguyen Thi, Nguyen Thi Hien Lan, Nguyen Thi Thuy Hang, Nguyen Quang Hai, Duong Thi Tu Anh, Vu Thi Hau, Lam Van Tan, and Thuan Van Tran. "CoFe2O4 Nanomaterials: Effect of Annealing Temperature on Characterization, Magnetic, Photocatalytic, and Photo-Fenton Properties." Processes 7, no. 12 (November 28, 2019): 885. http://dx.doi.org/10.3390/pr7120885.

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In this research, structural, magnetic properties and photocatalytic activity of cobalt ferrite spinel (CoFe2O4) nanoparticles were studied. The samples were characterized by X-ray powder diffraction (XRD), energy dispersive X-ray (EDX), scanning electron microscopy (SEM), transmission electronic microscopy (TEM), Brunauer–Emmett–Teller (BET), Fourier transform infrared spectroscopy (FTIR), and UV-visible diffused reflectance spectroscopy (DRS) analysis. The XRD analysis revealed the formation of the single-phase CoFe2O4 with a cubic structure that is annealed at 500–700 °C in 3 h. The optical band gap energy for CoFe2O4 was determined to be in the range of 1.57–2.03 eV. The effect on the magnetic properties of cobalt ferrites was analyzed by using a vibrating sample magnetometer (VSM). The particle size and the saturation magnetization of cobalt ferrite nanoparticles increased with increasing annealing temperature. The photocatalytic activity of CoFe2O4 nanoparticles was investigated by using rhodamine B dye under visible light. The decomposition of rhodamine B reached 90.6% after 270 min lighting with the presence of H2O2 and CF500 sample.

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Budi, M. A. K., E. B. Glass, N. G. Rudawski, and J. S. Andrew. "Exchange bias in bismuth ferrite/cobalt ferrite Janus nanofibers." Journal of Materials Chemistry C 5, no. 33 (2017): 8586–92. http://dx.doi.org/10.1039/c7tc00975e.

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Bismuth ferrite:cobalt ferrite (BiFeO₃:CoFe₂O₄) nanofibers with tailorable exchange bias effects were synthesized utilizing a Janus type morphology, wherein both phases are coupled longitudinally along the length of each fiber.

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Medina, Mauricio A., Goldie Oza, A. Ángeles-Pascual, Marlene González M., R. Antaño-López, A. Vera, L. Leija, et al. "Synthesis, Characterization and Magnetic Hyperthermia of Monodispersed Cobalt Ferrite Nanoparticles for Cancer Therapeutics." Molecules 25, no. 19 (September 27, 2020): 4428. http://dx.doi.org/10.3390/molecules25194428.

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Magnetic nanoparticles such as cobalt ferrite are investigated under clinical hyperthermia conditions for the treatment of cancer. Cobalt ferrite nanoparticles (CFNPs) synthesized by the thermal decomposition method, using nonionic surfactant Triton-X100, possess hydrophilic polyethylene oxide chains acting as reducing agents for the cobalt and iron precursors. The monodispersed nanoparticles were of 10 nm size, as confirmed by high-resolution transmission electron microscopy (HR-TEM). The X-ray diffraction patterns of CFNPs prove the existence of cubic spinel cobalt ferrites. Cs-corrected scanning transmission electron microscopy–high-angle annular dark-field imaging (STEM–HAADF) of CFNPs confirmed their multi-twinned crystallinity due to the presence of atomic columns and defects in the nanostructure. Magnetic measurements proved that the CFNPs possess reduced remnant magnetization (MR/MS) (0.86), which justifies cubic anisotropy in the system. Microwave-based hyperthermia studies performed at 2.45 GHz under clinical conditions in physiological saline increased the temperature of the CFNP samples due to the transformation of radiation energy to heat. The specific absorption rate of CFNPs in physiological saline was 68.28 W/g. Furthermore, when triple-negative breast cancer cells (TNBC) in the presence of increasing CFNP concentration (5 mg/mL to 40 mg/mL) were exposed to microwaves, the cell cytotoxicity was enhanced compared to CFNPs alone.

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Kim, Eun Hee, Hyo Sook Lee, and Hui Ping Shao. "Preparation of Nanostructured Metal Ferrite Particles by Sonochemistry." Key Engineering Materials 277-279 (January 2005): 1044–48. http://dx.doi.org/10.4028/www.scientific.net/kem.277-279.1044.

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Nanostructured iron and cobalt ferrite particles were prepared from iron chloride and cobalt chloride, respectively, using the sonochemical method. The particles were compared with those synthesized using the co-precipitation method. The properties of the particles were characterized using various techniques, such as XRD, TEM, VSM and a SQUID magnetometer. The iron ferrite particles had an average particle size of about 15 nm and a magnetization value of 83 emu/g at a magnetic field of 50 kOe, while the particle size of cobalt ferrite was about 5 nm and its magnetization value was 33 emu/g at the same magnetic field.

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Singh, Ashok K., and Vijay S. Raykar. "Experimental Investigation of Thermal Conductivity and Effusivity of Ferrite Based Nanofluids under Magnetic Field." ISRN Nanotechnology 2013 (August 4, 2013): 1–5. http://dx.doi.org/10.1155/2013/479763.

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We investigate the effect of magnetic field (H) on the thermal conductivity (λ) and effusivity (ε) of cobalt ferrite based nanofluids having different concentrations (ϕ). Cobalt ferrite nanoparticles (NPs) have been synthesized using the microwave assisted method. At high volume fraction of cobalt ferrite nanoparticles in water (ϕ > 0), both thermal parameters have been found to be suppressed relative to ϕ and λ of water in the absence of H. However, it is seen that percentage values of the effusivity in perpendicular field direction show negative to positive variation, and thermal conductivity in parallel field direction shows negative to zero variation.

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Lin, Qing, Yun He, Jianmei Xu, Jinpei Lin, Zeping Guo, and Fang Yang. "Effects of Al3+ Substitution on Structural and Magnetic Behavior of CoFe2O4 Ferrite Nanomaterials." Nanomaterials 8, no. 10 (September 21, 2018): 750. http://dx.doi.org/10.3390/nano8100750.

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A sol-gel autocombustion method was used to synthesize Al3+ ion-substituted cobalt ferrite CoAlxFe2−xO4 (x = 0–1.5). According to X-ray diffraction analysis (XRD), cobalt ferrite was in a single cubic phase after being calcined at 1000 °C for 3 h. Moreover, the lattice constant decreased with increase in aluminum substituents. When the sample was analyzed by Scanning Electron Microscopy (SEM), we found that uniformly sized, well-crystallized grains were distributed in the sample. Furthermore, we confirmed that Al3+ ion-substituted cobalt ferrite underwent a transition from ferrimagnetic to superparamagnetic behavior; the superparamagnetic behavior was completely correlated with the increase in Al3+ ion concentration at room temperature. All these findings were observed in Mössbauer spectra. For the cobalt ferrite CoAlxFe2−xO4, the coercivity and saturation magnetization decrease with an increase in aluminum content. When the annealing temperature of CoAl0.1Fe1.9O4 was steadily increased, the coercivity and saturation magnetization initially increased and then decreased.

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Li, Juan Bi, Di Qiong Hu, Yu Huan Wang, Liang Chao Li, and Yan Ding. "Preparation and Performance of Chiral Polyaniline/Cobalt Ferrite Composites." Materials Science Forum 852 (April 2016): 342–45. http://dx.doi.org/10.4028/www.scientific.net/msf.852.342.

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The cobalt ferrite and chiral polyaniline/cobalt ferrite composites were synthesized by co-precipitation and in-situ polymerization method, respectively. The crystal structure and composition, electrical conductivity, optical rotation, dielectric loss and magnetic loss of the as-prepared samples were researched. It was found that the optical rotation (levorotation) of composites is less than that of chiral polyaniline (L-PANI), and increased with the increasing of L-PANI content. The conductivity of the composites with a mass ratio of L-PANI to cobalt ferrite above 0.4 was better than of pure L-PANI, and their dielectric loss was in accordance with the conductivity in variation trend.

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NAYAK, BIBHUTI B., NADIYA BIHARY NAYAK, RAHUL KUMAR MALLIK, and APARNA MONDAL. "SYNTHESIS AND MAGNETIC PROPERTIES OF COBALT FERRITE WITH DIFFERENT MORPHOLOGIES." International Journal of Modern Physics: Conference Series 22 (January 2013): 164–68. http://dx.doi.org/10.1142/s2010194513010064.

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Different morphologies (spherical, flake and rod) of cobalt ferrite were synthesized using cobalt salt, iron salts, hydrazine hydrate (as a precipitating agent) and CTAB (surfactant) in water as well as ethylene glycol solvents. Four different synthesis ways (HIS, SIH, HISCO and HISG) were adopted to synthesize cobalt ferrite nanopowders using precipitation method. The as-prepared powders obtained after different synthesis ways were calcined at 800°C and structure, microstructure as well as magnetic properties are studied. X-ray diffraction (XRD), scanning electron microscope (SEM) and magnetization studies using pulsed field loop tracer were employed to characterize these cobalt ferrite powders, prepared using different precipitation ways. All the samples are identified with single phase cobalt ferrite and the crystallite size was found to be around 40 nm. Nearly spherical (multifaceted), rod with flake-like, nearly spherical and rod-like morphologies are obtained while synthesizing using HIS, SIH, HISCO and HISG ways, respectively. Rod with flake-like (SIH sample) and rod-like morphologies (HISG sample) show higher coercivity, than the spherical-like (SIH and HISCO smaples) morphology. The highest coericivty was found to be around 925 Oe for HISG sample and highest magnetization is 67 emu/g for HISCO sample.

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Randhawa, B. S., Manik Gupta, and Manpreet Kaur. "Preparation of cobalt ferrite from the thermolysis of cobalt tris(malonato)ferrate(III)trihydrate precursor." Ceramics International 35, no. 8 (December 2009): 3521–24. http://dx.doi.org/10.1016/j.ceramint.2009.05.014.

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Sanpo, Noppakun, and Jirasak Tharajak. "Influence of Feedstock Feed Rate on the Properties of SPPS-Deposited Cobalt Ferrite Splats." Applied Mechanics and Materials 866 (June 2017): 291–94. http://dx.doi.org/10.4028/www.scientific.net/amm.866.291.

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Cobalt ferrite sol-gel solution was deposited onto mild steel substrates to form single splats using a solution precursor plasma spray (SPPS) process. It was revealed that the thermal oxidation of cobalt and iron salts occurred mainly into six different formations of deposited splats. These formulations were cobalt monoxide (CoO), maghemite (γ-Fe2O3), cobalt oxide (Co3O4), cobalt oxyhydroxide (CoOOH), goethite (α-FeOOH), hematite (α-Fe2O3), magnetite (Fe3O4), and cobalt ferrite (CoFe2O4). The surface topographies of the splats exhibited burned, unmolten, partially molten, and completely molten splats. The feed rates of SPPS process played the important role on several properties of the splat such as splat morphologies and percentage of the obtained composite splat phases.

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Shabelskaya, Nina P., Marina A. Egorova, Anna V. Arzumanova, Elena A. Yakovenko, Vladimir M. Zababurin, and Alexander V. Vyaltsev. "PREPARATION OF COMPOSITE MATERIALS BASED ON COBALT (II) FERRITE FOR PURIFICATION OF AQUEOUS SOLUTIONS." IZVESTIYA VYSSHIKH UCHEBNYKH ZAVEDENII KHIMIYA KHIMICHESKAYA TEKHNOLOGIYA 64, no. 2 (January 29, 2021): 95–102. http://dx.doi.org/10.6060/ivkkt.20216402.6215.

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In this paper, composite materials based on cobalt (II) ferrite, which is a promising object of research as a magnetic material, are obtained. Thus, it is known to be used for producing organo / inorganic and non-organo/inorganic compositions. The introduction of cobalt ferrite makes it possible to give new properties to carrier materials. As a carrier, waste from the production of phosphoric acid – phosphogypsum, ash – and – slag waste from thermal power stations and cullet-foam glass, and activated carbon were used. Finding a way to process waste to produce new composite materials is an urgent task of chemical technology. The obtained samples were studied using X-ray phase analysis and electron microscopy. In the course of the conducted research, the principal possibility of using the specified number of production wastes for the synthesis of catalytically active materials is shown. Photocatalytic reactions are widely used in water treatment processes for wastewater treatment from organic pollutants. A simple method for obtaining composite materials of the composition of foam glass/ cobalt ferrite (II), phosphogypsum/ cobalt ferrite (II), activated carbon/ cobalt ferrite (II) is proposed. The catalytic properties of synthesized materials in the process of oxidative destruction of an organic dye in the presence of hydrogen peroxide are studied. It was found that the highest activity under the specified conditions is observed for the activated carbon/ cobalt (II) ferrite composite: complete removal of the organic dye from the aqueous solution is achieved after 90 min from the beginning of the reaction. The phosphogypsum-based composite shows the least pronounced activity. The results obtained can serve as a guide for choosing a method for producing non-toxic materials that are promising for use in water treatment systems and ensuring environmental safety of industrial enterprises that use organic dyes in the production process.

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Walters, I., R. Shende, and J. A. Puszynski. "Hydrogen Production from Thermochemical Water-Splitting Using Ferrites Prepared by Solution Combustion Synthesis." Advances in Science and Technology 91 (October 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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Chen, I.-Han, Cheng-Chien Wang, and Chuh-Yung Chen. "Fabrication and characterization of magnetic cobalt ferrite/polyacrylonitrile and cobalt ferrite/carbon nanofibers by electrospinning." Carbon 48, no. 3 (March 2010): 604–11. http://dx.doi.org/10.1016/j.carbon.2009.09.062.

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Maat, S., M. J. Carey, Eric E. Fullerton, T. X. Le, P. M. Rice, and B. A. Gurney. "Cobalt–oxide underlayers for cobalt–ferrite pinned spin valves." Applied Physics Letters 81, no. 3 (July 15, 2002): 520–22. http://dx.doi.org/10.1063/1.1494461.

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47

Sulaiman, Jameel M. A., Suhad M. Hamdoon, and Ghada Y. Abdulrahman. "Antibacterial Activity of Cobalt Ferrite (CoFe₂O₄) Nanoparticles against Oral Enterococci." Materials Science Forum 1021 (February 2021): 150–59. http://dx.doi.org/10.4028/www.scientific.net/msf.1021.150.

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This study aimed to show the enhanced effect of nanoparticles cobalt ferrite CoFe2O4 with chlorhexidine on Enterococcus faecium isolated from failure root canal treatment cases. Sol-gel technique was used to prepare the spinel cobalt ferrite CoFe2O4 at 200 °C then sintering at 400 °C & 600 °C, whereas the antimicrobial susceptibility test of nanoparticles was carried out according to the Kirby-Bauer technique compared with chlorhexidine. Fifteen isolates of Enterococcus faecium obtained by inserting sterile paper points in root canals, from patients who consulted the Teaching Hospital of Dentistry College at the University of Mosul, Iraq. For the first time, results showed that the nanoparticle cobalt ferrite CoFe2O4 at 400 °C and 600 °C, when mixed with chlorhexidine, give the mean inhibition zone 8.5334 mm and 8.0667mm respectively, while the pure chlorhexidine was providing a mean inhibition zone of 3.1667 mm, and also the nanoparticles cobalt ferrite in both cases of sintering without mixing, there was no antimicrobial effect. Statistical analysis using Duncan showed significant differences among groups (p < 0.05).

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Ahmadi, Rahil, Mina Imani, and Azadeh Tadjarodi. "Microwave Assisted Synthesis of CoFe2O4 Nanoparticles by Utilizing Organic Promoters and Evaluation of Its Properties." Chemistry Proceedings 3, no. 1 (November 14, 2020): 52. http://dx.doi.org/10.3390/ecsoc-24-08351.

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Nano-sized spinel ferrites are highly regarded owing to their special optical, electrical, and magnetic properties. Cobalt ferrite (CoFe2O4) is a nominee of particular interest due to its high saturation magnetization, high coercivity, strong anisotropy, and excellent chemical stability. The synthesis of these materials with a pure crystalline phase is sometimes limited due to the required high temperatures for their calcination. In this work, we report a one-pot simple synthesis procedure of cobalt ferrite by the auto-combustion under microwave irradiation into a domestic microwave oven with a power of 900 W for 30 min. Glycine and ammonium nitrate were used as organic promoters and metal nitrates as precursors. The synthesized nanoparticles were characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersion of X-ray spectrometry (EDX) techniques. The electrochemical properties and capability of the prepared product as a pseudocapacitive material were evaluated using cyclic voltammetry (CV) tests in details.

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Hoh, J. C., and Iskandar I. Yaacob. "Polymer matrix templated synthesis: Cobalt ferrite nanoparticles preparation." Journal of Materials Research 17, no. 12 (December 2002): 3105–9. http://dx.doi.org/10.1557/jmr.2002.0449.

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Cobalt ferrite (CoFe2O4) nanoparticles were successfully synthesized by polymer matrix templated synthesis. Synthetic ion-exchange resins were used as hosts for the coprecipitation of cobalt ferrite where the nanopores of the resin acted as the constrained environment. The weight fraction of the particles within the resin was roughly 16%. X-ray diffraction analysis indicated that cobalt ferrite crystallites were about 1–7 nm in diameter. Magnetic properties measured using an alternating gradient magnetometer showed the particles (prepared using initial salt solution ratio of Fe3+:Co2+ of 1.5:1.0) were superparamagnetic with magnetization M (of the particle-resin system) in the range of 3.0 to 4.4 emu/g at 10 kOe of applied field. The least upper bound of the magnetic size was about 3 nm in diameter. Ratios of Fe3+ to Co2+ within the matrix of the resin before and after precipitation were investigated by x-ray fluorescence spectrometry and were found to be sensitive to the initial salt solution mixture. The ratio Fe3+:Co2+ of 1.5:1.0 was found to be a better mixture in terms of magnetization value. Spherical shape cobalt ferrite particles 2–8 nm in diameter were observed using transmission electron microscopy. The close agreement between the physical and crystallite size indicated that the particles are largely monocrystals.

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Hamdi, N., L. Bessais, and W. Belam. "Sol-gel Autocombustion Elaboration and Physiochemical Characterizations of Cu2+ Substituted Cobalt Ferrite Nanoparticles." Open Chemistry Journal 7, no. 1 (December 31, 2020): 44–54. http://dx.doi.org/10.2174/1874842202007010044.

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Abstract:

Introduction: The copper doped cobalt ferrite series, with nominal formula CuXCo1-XFe2O4 (X = 0, 0.25, 0.5, 0.75, 1), has been elaborated via sol-gel autocombustion process by copper substitution procedure into cobalt ferrite framework. Methods: The five synthesized ferrites have been analyzed by X-ray powder diffraction, Fourier transform infrared spectroscopy, field emission scanning electron microscopy coupled to energy dispersive X-ray spectroscopy, complex impedance spectroscopy and superconducting quantum interference device magnetometry. Results and Discussion: The analysis of the results allowed to deduce that the cubic spinel basic structure was not modified by the incorporation of copper into the host lattice and the corresponding pure fine powders obtained formed by homogeneous nanoparticles. The highest electrical conductivity value, σDC(373K) = 27.03x10-3S.cm-1, was observed in the case of CuFe2O4. Conclusion: Moreover, the superparamagnetic behavior at room temperature has been confirmed by using both ZFC-FC and hysteresis magnetic measurement modes. In addition, the remarkable electrical conductivity and magnetic properties of the five explored nanoferrites, derived from the present investigation, enabled them useful in several modern nanotechnological and biomedical applications.

Journal articles on the topic 'Ferrite de cobalt'

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