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Artigos de revistas sobre o tema "Cobalt – Minerais – Ferrites de cobalt"

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Publicado: 25 de maio de 2024

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1

Lazdovica, Kristīne, e 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 de novembro de 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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2

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

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3

Kale, G. M., e T. Asokan. "Electrical properties of cobalt‐zinc ferrites". Applied Physics Letters 62, n.º 19 (10 de maio de 1993): 2324–25. http://dx.doi.org/10.1063/1.109405.

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4

Lenglet, M., F. Hochu e J. Dürr. "Optical Properties of Mixed Cobalt Ferrites". Le Journal de Physique IV 07, n.º C1 (março de 1997): C1–259—C1–260. http://dx.doi.org/10.1051/jp4:19971100.

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5

Caltun, Ovidiu, Ioan Dumitru, Marcel Feder, Nicoleta Lupu e Horia Chiriac. "Substituted cobalt ferrites for sensors applications". Journal of Magnetism and Magnetic Materials 320, n.º 20 (outubro de 2008): e869-e873. http://dx.doi.org/10.1016/j.jmmm.2008.04.067.

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6

Martin Cabañas, B., S. Leclercq, P. Barboux, M. Fédoroff e G. Lefèvre. "Sorption of nickel and cobalt ions onto cobalt and nickel ferrites". Journal of Colloid and Interface Science 360, n.º 2 (agosto de 2011): 695–700. http://dx.doi.org/10.1016/j.jcis.2011.04.082.

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7

Gupta, Priyanka, e 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, n.º 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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8

de la Torre, Ernesto, Ana Lozada, Maricarmen Adatty e Sebastián Gámez. "Activated Carbon-Spinels Composites for Waste Water Treatment". Metals 8, n.º 12 (16 de dezembro de 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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9

Boss, Alan F. N., Antonio C. C. Migliano e Ingrid Wilke. "The Influence of Stoichiometry on the Index of Refraction of Cobalt Ferrite Samples at Terahertz Frequencies". MRS Advances 2, n.º 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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10

Bushkova, V. S., I. P. Yaremiy, B. K. Ostafiychuk, V. V. Moklyak e A. B. Hrubiak. "Mössbauer Study of Nickel-Substituted Cobalt Ferrites". Journal of Nano- and Electronic Physics 10, n.º 3 (2018): 03013–1. http://dx.doi.org/10.21272/jnep.10(3).03013.

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11

Blesa, Miguel A., Alberto J. G. Maroto e Pedro J. Morando. "Dissolution of cobalt ferrites by thioglycolic acid". Journal of the Chemical Society, Faraday Transactions 1: Physical Chemistry in Condensed Phases 82, n.º 8 (1986): 2345. http://dx.doi.org/10.1039/f19868202345.

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12

Corral-Flores, Veronica, Dario Bueno-Baques, Anatoliy V. Glushchenko, Ronald F. Ziolo, Jose A. Matutes-Aquino, Reiko Sato-Turtelli e Roland Grossinger. "Magnetic Properties of Spinel Cobalt–Manganese Ferrites". IEEE Transactions on Magnetics 51, n.º 4 (abril de 2015): 1–4. http://dx.doi.org/10.1109/tmag.2014.2357172.

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13

Noor, Saroaut, M. A. Hakim, S. S. Sikder, S. Manjura Hoque, Kazi Hanium Maria e Per Nordblad. "Magnetic behavior of Cd2+ substituted cobalt ferrites". Journal of Physics and Chemistry of Solids 73, n.º 2 (fevereiro de 2012): 227–31. http://dx.doi.org/10.1016/j.jpcs.2011.10.038.

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14

Venudhar, Y. C., e K. Satya Mohan. "Dielectric behaviour of lithium–cobalt mixed ferrites". Materials Letters 54, n.º 2-3 (maio de 2002): 135–39. http://dx.doi.org/10.1016/s0167-577x(01)00551-1.

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15

Venudhar, Y. C., e K. Satya Mohan. "Elastic behaviour of lithium–cobalt mixed ferrites". Materials Letters 55, n.º 3 (julho de 2002): 196–99. http://dx.doi.org/10.1016/s0167-577x(01)00645-0.

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16

Song, J. M., e J. G. Koh. "Studies of polycrystalline cobalt-substituted lithium ferrites". IEEE Transactions on Magnetics 32, n.º 2 (março de 1996): 411–15. http://dx.doi.org/10.1109/20.486525.

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17

Pannaparayil, T., e S. Komarneni. "Synthesis and characterization of ultrafine cobalt ferrites". IEEE Transactions on Magnetics 25, n.º 5 (1989): 4233–35. http://dx.doi.org/10.1109/20.42579.

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18

Rao, K. Srinivasa, A. Mahesh Kumar, M. Chaitanya Varma, G. S. V. R. K. Choudary e K. H. Rao. "Cation distribution of titanium substituted cobalt ferrites". Journal of Alloys and Compounds 488, n.º 1 (novembro de 2009): L6—L9. http://dx.doi.org/10.1016/j.jallcom.2009.08.086.

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19

Velinov, Nikolay, Kremena Koleva, Tanya Tsoncheva, Daniela Paneva, Elina Manova, Krassimir Tenchev, Boris Kunev, Izabela Genova e Ivan Mitov. "Copper-cobalt ferrites as catalysts for methanol decomposition". Open Chemistry 12, n.º 2 (1 de fevereiro de 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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20

Nandiyanto, Asep Bayu Dani, Yustika Desti Yolanda, Mia Widyaningsih, Risti Ragadhita, Herry Saputra, Eddy Soeryanto Soegoto e 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, n.º 4 (31 de agosto de 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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21

Othéro de Brito, Vera Lúcia, Stéphanie Alá Cunha, Ana Paula Ribeiro Uchoas, Fabiana Faria de Araújo, Cristina Bormio Nunes e Luis Antonio Genova. "Evaluation of the Sinterability of Copper-Substituted Ferrites by Means of Dilatometric Thermal Analysis". Materials Science Forum 805 (setembro de 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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22

Hochu, F., e 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, n.º 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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23

Liu, Binghai, Jun Ding, Jiabao Yi, Jianhua Yin e Zhili Dong. "Magnetic Anisotropies in Cobalt-Nickel Ferrites (NixCo1-xFe2O4)". Journal of the Korean Physical Society 52, n.º 5 (15 de maio de 2008): 1483–86. http://dx.doi.org/10.3938/jkps.52.1483.

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24

Gingasu, Dana, Lucian Diamandescu, Ioana Mindru, Gabriela Marinescu, Daniela C. Culita, Jose Maria Calderon-Moreno, Silviu Preda, Cristina Bartha e Luminita Patron. "Chromium Substituted Cobalt Ferrites by Glycine-Nitrates Process". Croatica Chemica Acta 88, n.º 4 (2015): 445–51. http://dx.doi.org/10.5562/cca2743.

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25

Franco, A., F. L. A. Machado, V. S. Zapf e F. Wolff-Fabris. "Enhanced magnetic properties of Bi-substituted cobalt ferrites". Journal of Applied Physics 109, n.º 7 (abril de 2011): 07A745. http://dx.doi.org/10.1063/1.3565406.

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26

Ardizzone, Silvia, Alba Chittofrati e Leonardo Formaro. "Iron(II) cobalt ferrites. Preparation and interfacial behaviour". Journal of the Chemical Society, Faraday Transactions 1: Physical Chemistry in Condensed Phases 83, n.º 4 (1987): 1159. http://dx.doi.org/10.1039/f19878301159.

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27

Blasco, J., G. Subías, J. García, C. Popescu e V. Cuartero. "High-pressure transformation in the cobalt spinel ferrites". Journal of Solid State Chemistry 221 (janeiro de 2015): 173–77. http://dx.doi.org/10.1016/j.jssc.2014.09.028.

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28

El-Saadawy, M., e M. M. Barakat. "Electrical conductivity of cobalt-doped BaZn hexagonal ferrites". Journal of Magnetism and Magnetic Materials 205, n.º 2-3 (novembro de 1999): 319–22. http://dx.doi.org/10.1016/s0304-8853(99)00447-3.

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29

Tourinho, Francisco Augusto, Raymonde Franck e Ren� Massart. "Aqueous ferrofluids based on manganese and cobalt ferrites". Journal of Materials Science 25, n.º 7 (julho de 1990): 3249–54. http://dx.doi.org/10.1007/bf00587682.

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30

Ardizzone, Silvia, e Leonardo Formaro. "Surface defectivity and pHp.z.c. of cobalt ferrous ferrites". Colloids and Surfaces 34, n.º 3 (janeiro de 1988): 247–54. http://dx.doi.org/10.1016/0166-6622(88)80103-3.

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31

Ramana Reddy, A. V., G. Ranga Mohan, B. S. Boyanov e D. Ravinder. "Electrical transport properties of zinc-substituted cobalt ferrites". Materials Letters 39, n.º 3 (maio de 1999): 153–65. http://dx.doi.org/10.1016/s0167-577x(98)00234-1.

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32

Arean, C. Otero, J. L. Rodriguez Blanco, J. M. Rubio Gonzalez e M. C. Trobajo Fernandez. "Structural characterization of polycrystalline gallium-substituted cobalt ferrites". Journal of Materials Science Letters 9, n.º 2 (fevereiro de 1990): 229–30. http://dx.doi.org/10.1007/bf00727726.

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33

Abellän, J., e M. Ortuño. "The Verwey Transition in Polycrystalline Cobalt-Iron Ferrites". physica status solidi (a) 96, n.º 2 (16 de agosto de 1986): 581–86. http://dx.doi.org/10.1002/pssa.2210960226.

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34

Hsiang, Hsing-I., Jui-Huan Tu, Wen-Chin Kuo, Chi-Yao Tsai e Li-Then Mei. "Cobalt oxide addition effects on the microstructure and electronic properties of CuZn ferrites". Additional Conferences (Device Packaging, HiTEC, HiTEN, and CICMT) 2015, CICMT (1 de setembro de 2015): 000131–38. http://dx.doi.org/10.4071/cicmt-tp46.

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The effects of cobalt oxide addition on the microstructure and electrical properties of CuZn ferrites were investigated. CuZn ferrites with compositions of (CuO)0.2(ZnO)0.8(Co3O4)x/3 (Fe2O3) 0.986-2x; x = 0 , 0.02, 0.04, 0.08, 0.1 were synthesized using a solid state reaction. It was observed that the addition of cobalt will change the amounts and distribution of Cu2+, Cu+, Fe2+, and Fe3+ in the grain and grain boundary. The segregation of copper ions at the grain boundary was observed as the substitution of cobalt was increased. Moreover, as the x value was increased above 0.04, second phases of CuO and ZnO were found. The different amounts and distribution of Cu2+, Cu+, Fe2+, and Fe3+ in the bulk and grain boundary for samples added with different amounts of cobalt changed the conductivity activation energies of the bulk and grain boundary, and hence affected the space polarization and dielectric properties.

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35

Pussi, Katariina, Keying Ding, Bernardo Barbiellini, Koji Ohara, Hiroki Yamada, Chuka Onuh, James McBride, Arun Bansil, Ray K. Chiang e Saeed Kamali. "Atomic Structure of Mn-Doped CoFe2O4 Nanoparticles for Metal–Air Battery Applications". Condensed Matter 8, n.º 2 (24 de maio de 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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36

Al-Kadhi, Nada S., Ghadah M. Al-Senani, Rasmiah S. Almufarij, Omar H. Abd-Elkader e Nasrallah M. Deraz. "Green Synthesis of Nanomagnetic Copper and Cobalt Ferrites Using Corchorus Olitorius". Crystals 13, n.º 5 (3 de maio de 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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37

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

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

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38

Frolova, Liliya A. "Investigation of Magnetic and Photocatalytic Properties of CoFe₂O₄ Doped La³⁺, Nd³⁺, I³⁺". ECS Meeting Abstracts MA2022-01, n.º 30 (7 de julho de 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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Venkateshwarlu, Ch, M. Ramesh, G. Vinod, Y. Suresh Reddy, K. Rajashekhar, B. Naresh, P. Ramesh, U. Dasharatha, B. Venkatesh e J. Laxman Naik. "The Structural and Electrical Studies on Cu-Co Ferrites". IOP Conference Series: Materials Science and Engineering 1221, n.º 1 (1 de março de 2022): 012014. http://dx.doi.org/10.1088/1757-899x/1221/1/012014.

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Abstract The system Cobalt substituted copperferritesampleswere synthesized by a conventional double sintering ceramic method.A series of doped Copper ferrites withcomposithion Cu1-xCoxFe2O4 (x = 0.2, 0.4, and 0.6 ) are synthesized. The X-raydiffraction pattern at room temperature show that the sample exists in single phase with a spinel structure.Copper-Cobalt ferrites seriesaretakenand their electrical conductivityproperty are studied with a variation of composition and temperature. Log (σT) vs 103/T is almost linear with a variation close to the temperature of Curie.In general, the paramagnetic region activation energy is greater than that of the ferromagnetic region’s.

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40

El-Salam, Asmaa Reda Abd, K. E. Rady, Ezzat A. ELFadaly e Mobarak Hassan Aly. "Enhanced Structural and Morphological Properties of Doped Cobalt Zinc Ferrite". Journal of Nanotechnology and Nanomaterials 4, n.º 2 (22 de novembro de 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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41

Islam, M. A., A. K. M. Akther Hossain, M. Z. Ahsan, M. A. A. Bally, M. Samir Ullah, S. M. Hoque e F. A. Khan. "Structural characteristics, cation distribution, and elastic properties of Cr³⁺ substituted stoichiometric and non-stoichiometric cobalt ferrites". RSC Advances 12, n.º 14 (2022): 8502–19. http://dx.doi.org/10.1039/d1ra09090a.

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Khan, Amrita, Mahabub Alam Bhuiyan, Golam Dastegir Al Quaderi, Kazi Hanium Maria, Shamima Choudhury, Kazi Md Amjad Hossain, Shirin Akther e DK Saha. "Dielectric and transport properties of Zn-substituted cobalt ferrites". Journal of Bangladesh Academy of Sciences 37, n.º 1 (14 de julho de 2013): 73–82. http://dx.doi.org/10.3329/jbas.v37i1.15683.

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Effect of Zn content on the dielectric and transport properties of CoZnxFe2-xO4 (x = 0.0, 0.1, 0.2, 0.3 and 0.4), prepared by standard double sintering ceramic technique, sintered at 1000°C for 4 hours were investigated. The X-ray diffraction (XRD) pattern of the prepared samples showed single phase inverse-spinel structure without any detectable impurity. Lattice constant of the samples increased with the increasing Zn concentration which follows Vegards law. The theoretical densities of these samples remained almost constant whereas the bulk density decreased with Zn content up to x = 0.2. But with further increase of Zn content the bulk density increased. The porosity of the prepared samples showed the opposite trend. The dielectric constant (??) measurement showed the normal dielectric behavior of the prepared ferrite. The DC electrical resistivity of the prepared samples decrease with increasing temperature which indicates the semiconducting behavior of the prepared ferrites. The Zn concentration showed pronounced effect on the resistivity at room temperature. Possible explanation for the observed features of densities, porosity, dielectric constant and resistivity of the studied samples are discussed. DOI: http://dx.doi.org/10.3329/jbas.v37i1.15683 Journal of Bangladesh Academy of Sciences, Vol. 37, No. 1, 73-82, 2013

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Ullah, Muhammad Samir, Kaniz Fatama, Md Firoz Uddin e Mohammad Mizanur Rahman. "Magnetic Properties of Cobalt Substituted Nickel-Zinc Mixed Ferrites". Journal of Magnetics 26, n.º 2 (30 de junho de 2021): 216–20. http://dx.doi.org/10.4283/jmag.2021.26.2.216.

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44

REDDY, V. DEVENDER, e P. VENUGOPAL REDDY. "ELECTRICAL CONDUCTIVITY OF COBALT-SUBSTITUTED BaZn-W HEXAGONAL FERRITES". Modern Physics Letters B 07, n.º 11 (10 de maio de 1993): 753–60. http://dx.doi.org/10.1142/s0217984993000734.

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The D.C. electrical conductivity of cobalt substituted BaZn-W hexagonal ferrites has been studied as a function of composition and temperature over a temperature range of 300–800 K. It has been observed that the cobalt doping has no influence on the RT values of electrical conductivity, although it does affect many other physical properties. For the first time, the authors noticed two clear and distinct transitions in the conductivity vs. temperature plots of all the samples, the first being ≈475 K and the second near their Curie temperatures. The transition T1 has been attributed to the spin reorientation while the second could be due to the Curie temperature. The activation energy values obtained for the paramagnetic region are found to be higher than those of the ferrimagnetic one for all the samples.

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45

Kaiser, M. "Effect of Silver Nanoparticles on Properties of Cobalt Ferrites". Journal of Electronic Materials 49, n.º 8 (11 de junho de 2020): 5053–63. http://dx.doi.org/10.1007/s11664-020-08234-3.

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Tahir Farid, Hafiz Muhammad, Ishtiaq Ahmad, K. A. Bhatti, Irshad Ali, Shahid M. Ramay e Asif Mahmood. "The effect of praseodymium on Cobalt-Zinc spinel ferrites". Ceramics International 43, n.º 9 (junho de 2017): 7253–60. http://dx.doi.org/10.1016/j.ceramint.2017.03.016.

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47

Velinov, Nikolay, Dimitar Dimitrov, Kremena Koleva, Krassimir Ivanov e Ivan Mitov. "Mechanochemical Synthesis and Characterization of Nanocrystalline Copper–Cobalt Ferrites". Acta Metallurgica Sinica (English Letters) 28, n.º 3 (13 de janeiro de 2015): 367–72. http://dx.doi.org/10.1007/s40195-015-0207-y.

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Vasambekar, P. N., C. B. Kolekar e A. S. Vaingankar. "Magnetic behaviour of Cd2+ and Cr3+ substituted cobalt ferrites". Materials Chemistry and Physics 60, n.º 3 (setembro de 1999): 282–85. http://dx.doi.org/10.1016/s0254-0584(99)00062-0.

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Shinde, S. S., e K. M. Jadhav. "Electrical and dielectric properties of silicon substituted cobalt ferrites". Materials Letters 37, n.º 1-2 (setembro de 1998): 63–67. http://dx.doi.org/10.1016/s0167-577x(98)00068-8.

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Hsiang, Hsing-I., Chi-Shiung Hsi, Chi-Yao Tsai e Li-Then Mei. "Cobalt-substitution effects on dielectric properties of CuZn ferrites". Ceramics International 41, n.º 3 (abril de 2015): 4140–44. http://dx.doi.org/10.1016/j.ceramint.2014.11.110.

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