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Academic literature on the topic 'Ferrites spinel'

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Published: 4 June 2021

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Journal articles on the topic "Ferrites spinel"

Wang, Wen Jie, Qing Jie Jiao, Chong Guang Zang, and Xiang Dong Zhu. "Study on the Absorption Properties of Spinel Type Ferrite Composite Coatings in the Low Frequency." Advanced Materials Research 415-417 (December 2011): 30–34. http://dx.doi.org/10.4028/www.scientific.net/amr.415-417.30.

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In the present study magneto-polymer composite coatings are fabricated using nano Zn ferrite, Mn ferrite, Ni ferrite, Zn-Mn ferrite and Zn-Ni ferrite by spraying method. The complex permeabilities, Complex permittivities and microwave absorbing properties within the low frequency of these composites were characterized and investigated. The results showed that the magnetism of the mixed spinel ferrites ( Mn ferrite, Zn-Ni ferrite, Zn-Mn ferrite) are strong but the dielectric properties are weaker, while the magnetism of the normal spinel ferrites (Zn ferrite) is the weakest but provide with a big storage capability of electric energy. The absorbing characteristics of the spinel ferrites are better at 300 kHz-1.5GHz, with minimum absorption of 12.5 dB and the maximum absorption at 480MHz, 1050 MHz and 1400 MHz. The microwave absorbing property of the mixed spinel ferrite Zn-Mn ferrite is best having the RL value being -42.5 dB at 1400GHz.

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Gao, Fen, Dong Lin Zhao, and Zeng Min Shen. "Preparation and Microwave Absorbing Properties of Cu-Doped Ni-Zn Spinel Ferrites." Advanced Materials Research 105-106 (April 2010): 293–96. http://dx.doi.org/10.4028/www.scientific.net/amr.105-106.293.

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Ni-Zn spinel ferrite and Cu-doped spinel ferrite were prepared by a conventional ceramic processing method. Microwave absorption, complex permittivity and permeability of the (Ni0.5Zn0.5)Fe2O4 and (Ni0.4Cu0.2Zn0.4)Fe2O4 spinel ferrites within the frequency range of 0.5-18 GHz were investigated. The reflection loss calculation results show that the Ni-Zn spinel ferrite and Cu-doped Ni-Zn spinel ferrite are good electromagnetic wave absorbers in the microwave range. The single layer (Ni0.4Cu0.2Zn0.4)Fe2O4 spinel ferrite absorber with a thickness of 9.2 mm achieved a reflection loss below -10 dB (90% absorption) at 0.5-2.3 GHz, and the minimum value is -35.63 dB at 1.1 GHz. When the first layer and second layer are (Ni0.5Zn0.5)Fe2O4 and (Ni0.4Cu0.2Zn0.4)Fe2O4 spinel ferrites respectively, the laminated absorbers with double spinel ferrite layers with a thickness of 3 mm achieved a reflection loss below -10 dB at 9.9-12.3 GHz, and the minimum value is -35.3 dB at 11.7 GHz.

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Sláma, Jozef, Martin Šoka, Anna Grusková, Alvaro Gonzalez, and Vladimír Jančárik. "Hopkinson Effect Study in Spinel and Hexagonal Ferrites." Journal of Electrical Engineering 62, no. 4 (July 1, 2011): 239–43. http://dx.doi.org/10.2478/v10187-011-0038-7.

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Hopkinson Effect Study in Spinel and Hexagonal Ferrites The magnetic susceptibility shows a Hopkinson peak just below the Curie temperature TC when heating the selected hexagonal and spinel ferrite samples. It is proposed that this peak can be associated with a transition from stable magnetic state to super-paramagnetic relaxation above the blocking temperature up to the TC. The Hopkinson effect results are compared with SEM micrographs of both studied hexagonal and spinel ferrites.

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Galvão, Wesley S., Davino M. A. Neto, Rafael M. Freire, and P. B. A. Fechine. "Super-Paramagnetic Nanoparticles with Spinel Structure: A Review of Synthesis and Biomedical Applications." Solid State Phenomena 241 (October 2015): 139–76. http://dx.doi.org/10.4028/www.scientific.net/ssp.241.139.

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The study of ceramic materials has attracted the attention of many researchers due to the possibility of their use in nanotechnology. The spinel ferrites form a large group of materials with a broad range of applications. Some examples include electronic devices such as high-frequency transformer cores, antenna rods, induction-tuners, among many others. However, when the ferritic materials display superparamagnetic behavior, their potential for biological applications like drug delivery, hyperthermia, resonance magnetic imaging and magnetic separation, become amazingly high. Therefore, the superparamagnetism is a characteristic strongly desired for spinel ferrites. Since this phenomenon is size-dependent, the methodologies to synthesize these materials has emerged as a crucial step in order to obtain the desired properties. In this regarding, several synthetic processes have been developed. For example, co-precipitation is a fast and cheap method to synthesize superparamagnetic spinel ferrites. However, methodologies involving microwave, ultrasound or polymers frequently result in these kind of materials. Therefore, this review brings a brief historic introduction about spinel ferrites as well as essential concepts to understand their structure and magnetic properties. In addition to this, recent advances in synthesis and applications of the superparamagnetic spinel ferrites are mentioned. Contents of Paper

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Kodama, T., H. Kato, S. G. Chang, N. Hasegawa, M. Tsuji, and Y. Tamaura. "Decomposition of CO2 to carbon by H2-reduced Ni(II)- and Co(II)-bearing ferrites at 300 °C." Journal of Materials Research 9, no. 2 (February 1994): 462–67. http://dx.doi.org/10.1557/jmr.1994.0462.

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Ni(II)- and Co(II)-bearing ferrites with different levels of metal substitution have been studied for CO2 decomposition. Ni2+ and Co2+ have been substituted for Fe2+ or Fe3+ in magnetite with the spinel type of crystal structure up to 14% and 26% for the mole ratio of Ni2+ and Co2+ to the total Fe contents, respectively. The metal substitution was corroborated by Mössbauer spectroscopy and XRD studies. They were activated in a flow of H2 gas to form oxygen-deficient ferrites with the spinel structure retained. The oxygen-deficient M(II)-bearing ferrites have been found to show high reactivity toward CO2 decomposition to carbon at 300 °C. The reactivity increased with the level of metal substitution and activation. The oxygens of CO2 were incorporated into the spinel structure and carbon was deposited on the surface of the ferrites. The deposited carbon was visible on dissolution of the ferrites used. The rate of decomposition on H2-activated Ni(II)-bearing ferrite with the mole ratio of 14% was 30 times as high as that of H2-activated magnetite.

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Astik, Nidhi M., and G. J. Baldha. "Investigation of Structural, Electrical and Magnetic Properties of Mixed Ferrite System." Advanced Materials Research 1047 (October 2014): 119–22. http://dx.doi.org/10.4028/www.scientific.net/amr.1047.119.

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The mineral having chemical compositional formula MgAl2O4 is called “spinel”. The ferrites crystallize in spinel structure are known as spinel-ferrites or ferro-spinels. The spinel structure has an fcc cage of oxygen ions and the metallic cations are distributed among tetrahedral (A) and octahedral (B) interstitial voids (sites). A compound of Co0.85Ca0.15-yMgyFe2O4 (y=0.05, 0.10, 0.15) is synthesized in polycrystalline form, using the stoichiometric mixture of oxides with conventional standard ceramic technique and characterized by X-ray diffraction (XRD).The XRD analysis confirmed the presence of cubic structure. The intensity of each Bragg plane is sensitive to the distribution of cations in the interstitial voids of the spinel lattice. The computer program Powder X software for XRD analysis has been utilized for this purpose. The compositions of Co0.85Ca0.15-yMgyFe2O4 (y=0.05, 0.10, 0.15) ferrites have been prepared by standard ceramic method with double sintering at 950°C, 1100°C. In present study, we report the structural, electrical and magnetic properties of above said compound.

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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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Seyyed Ebrahimi, S. A., and Z. Pishgahi Fard. "An Investigation on the Optimum Conditions for Preparation of Pure Mn-Mg-Zn Ferrite Powder." Key Engineering Materials 336-338 (April 2007): 699–702. http://dx.doi.org/10.4028/www.scientific.net/kem.336-338.699.

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Manganese- Zinc ferrite is one of the most important spinel ferrites which is used in the electronics applications. These ferrites have an open lattice and can tolerate large amounts of the other metallic ions in their lattice. One of these divalent ions that can sit in the unit cell of Mn-Zn ferrites is Magnesium. Mn-Mg-Zn ferrites are new materials which is thought to be a good candidate for dielectric applications. In this work, a suitable relative values of raw materials for preparing pure Mn-Mg-Zn ferrite powder have been determined. It is carried out by using XRD experiments. The optimum temperature and time of calcination were also investigated by DTA/TGA, XRD and SEM techniques.

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Ušáková, Mariana, Elemír Ušák, Martin Šoka, and Ján Lokaj. "The influence of selected ions on various characteristics of Nickel-Zinc ferrites." Journal of Electrical Engineering 69, no. 6 (December 1, 2018): 449–53. http://dx.doi.org/10.2478/jee-2018-0072.

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Abstract One of acknowledged methods remarkably improving structural, magnetic and electrical properties of spinel ferrite systems is the substitution of iron ions by some trivalent ions. In the family of spinel ferrites, thanks to its high saturation magnetization and electrical resistivity as well as low losses, the nickel-zinc ferrite is a very important magnetic material used in many applications in electrical engineering and electronics. The properties of these materials are in general dependent upon chemical composition, method of preparation, stoichiometry, sintering time, temperature as well as the atmosphere, etc. In this study the influence of appropriately selected ions (M = In3+, Nd3+, Dy3+ and Er3+), partly replacing Fe3+, on the microstructure and magnetic properties of spinel ferrite with the composition Ni0.42Zn0.58M0.02Fe1.98O4 fabricated by means of standard ceramic technology was investigated.

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Ren, Gui Hua, and Zhi Song Yu. "Synthesis of Monodisperse Fe₃O₄ and MnFe₂O₄ Nanospheres by Using a Solvothermal Reduction Method." Solid State Phenomena 181-182 (November 2011): 393–96. http://dx.doi.org/10.4028/www.scientific.net/ssp.181-182.393.

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The spinel ferrites, MFe2O4(where M=Fe, Mn, Co, Ni, Zn, Mg, etc.) have attracted considerable interest during the last few decades due to their potential applications in high frequency transformers, filters, high density storage devices, and microwave applications. In the latest several years, many synthesis technologies such as sol-gel, auto-combustion, thermal decomposition methods and hydrothermal reaction have been developed to prepare spinel ferrite nanoparticles. In this paper, the spinel ferrites Fe3O4and MnFe2O4nanoparticles were synthesized by using a solvothermal reduction method. X-ray diffraction (XRD) and Raman analysis shows that all the peaks are close to the data for Fe3O4and MnFe2O4, indicating the prepared particles are single phase. The scan electronic microscopy (SEM) shows that the prepared Fe3O4and MnFe2O4are monodisperse nanospheres and with the average size of around 300nm.

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Dissertations / Theses on the topic "Ferrites spinel"

Phillips, Peter John. "Conduction processes in spinel ferrites." Thesis, University of Warwick, 1991. http://wrap.warwick.ac.uk/108772/.

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An apparatus has been designed, constructed and tested for measurements of resistivity and thermopower, having the following novel features:- I) buffer amplifiers with driven shields to make measurements on highly resistive specimens, II) “in house” software and hardware developed to automate the measurements and, III) a new method of temperature measurement for thermopower studies. Measurements have been carried out on single crystal ZnxFe3_x04 and MnxFe3_x04 with 0 < X < 1 in the temperature range 4.2K-300K. The results strongly suggest that substitutional disorder plays an important role in the electrical transport properties of ferrites. The electrical conductivity for high X near 300K is interpreted in terms of nearest-neighbour hopping. The temperature dependence of G(a7’)=dLn(< 77’)/d( 1/T) between 300K and 100K and the concentration dependence of G(crT) at 100K provides evidence for the formation of a Coulomb Gap at low X. At low temperatures, variable-range and many-electron hopping for high and low X respectively is observed. An estimate of the effective radius of the carrier wavefunction is obtained from the conductivity measurements, which at ~0.4Á is comparable to that previously deduced for nickel ferrite. For all X a peak in the thermopower at about 50K was observed. The peak for high X has been attributed to the high temperature limit of variable- range hopping, while for low X interpreted as the transition from activation across a Coulomb Gap to many-electron hopping. In the high temperature range, the temperature variation is shown to be consistent with degenerate statistics for low X and non-degenerate statistics for high X. In the latter case it is possible to extract the dopant concentrations, which compare favourably with the values found by Electron Probe Micro-Analysis (EPMA). The high temperature thermopower and resistivity behaviour have been used to deduce the variation of the energy width of the conduction states, or bandwidth, with X and this is shown to be consistent with the expected behaviour. A polaron energy of ~0.04eV is calculated at 300K for high values of X, which compares favourably with previous work.

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Price, Sean. "Critical and magnetic behaviour of some spinel ferrites." Thesis, University of Portsmouth, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.304578.

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Vestal, Christy Riann. "Magnetic couplings and superparamagnetic properties of spinel ferrite nanoparticles." Diss., Available online, Georgia Institute of Technology, 2004:, 2004. http://etd.gatech.edu/theses/available/etd-06072004-131405/unrestricted/vestal%5Fchristy%5Fr%5F200405%5Fphd.pdf.

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Song, Qing. "Size and Shape Controlled Synthesis and Superparamagnetic Properties of Spinel Ferrites Nanocrystals." Diss., Georgia Institute of Technology, 2005. http://hdl.handle.net/1853/7645.

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Size and Shape Controlled Synthesis and Superparamagnetic Properties of Spinel Ferrites Nanocrystals Qing Song 216 pages Directed by Dr. Z. John Zhang The correlationship between magnetic properties and magnetic couplings is established through the investigations of various cubic spinel ferrite nanocrystals. The results of this thesis contribute to the knowledge of size and shape controlled synthesis of various spinel ferrites and core shell architectured nanocrystals as well as the nanomagnetism in spinel ferrites by systematically investigating the effects of spin orbital coupling, magnetocrystalline anisotropy, exchange coupling, shape and surface anisotropy upon superparamagnetic properties of spinel ferrite nanocrystals. A general synthetic method is developed for size and shape control of metal oxide nanocrystals. The size and shape dependent superparamagnetic properties are discussed. The relationship between spin orbital coupling and magnetocrystalline anisotropy is studied comparatively on variable sizes of spherical CoFe2O4 and Fe3O4 nanocrystals. It also addresses the effect of exchange coupling between magnetic hard phase and soft phase upon magnetic properties in core shell structured spinel ferrite nanocrystals. The role of anisotropic shapes of nanocrystals upon self assembled orientation ordered superstructures are investigated. The effect of thermal stability of molecular precursors upon size controlled synthesis of MnFe2O4 nanocrystals and the size dependent superparamagnetic properties are described.

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Bonholzer, Michael. "Magnetic Tunnel Junctions based on spinel ZnxFe3-xO4." Doctoral thesis, Universitätsbibliothek Leipzig, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-212756.

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Die vorliegende Arbeit befasst sich mit magnetischen Tunnelkontakten (magnetic tunnel junctions, MTJs) auf Basis des Oxids Zinkferrit (ZnxFe3-xO4). Dabei soll das Potential dieses Materials durch die Demonstration des Tunnelmagnetowiderstandes (tunnel magnetoresistance, TMR) in zinkferritbasierten Tunnelkontakten gezeigt werden. Dazu wurde ein Probendesign für MTJs auf Basis der „pseudo spin valve“-Geometrie entwickelt. Die Basis für dieseStrukturen ist ein Dünnfilmstapel aus MgO (Substrat) / TiN / ZnxFe3-xO4 / MgO / Co. Dieser ist mittels gepulster Laserabscheidung (pulsed laser deposition, PLD) hergestellt. Im Rahmen dieser Arbeit wurden die strukturellen, elektrischen und magnetischen Eigenschaften der Dünnfilme untersucht. Des weiteren wurden die fertig prozessierten MTJ-Bauelemente an einem im Rahmen dieser Arbeit entwickeltem und aufgebautem TMR-Messplatz vermessen. Dabei ist es gelungen einen TMR-Effekt von 0.5% in ZnxFe3-xO4-basierten MTJs nachzuweisen. Das erste Kapitel der Arbeit gibt eine Einführung in die spintronischen Effekte Riesenmagnetowiderstand (giant magnetoresistance, GMR) und Tunnelmagnetowiderstand (TMR). Deren technologische Anwendungen sowie die grundlegenden physikalischen Effekte und Modelle werden diskutiert. Das zweite Kapitel gibt eine Übersicht über die Materialklasse der spinellartigen Ferrite. Der Fokus liegt auf den Materialien Magnetit (Fe3O4) sowie Zinkferrit (ZnxFe3-xO4). Die physikalischen Modelle zur Beschreibung der strukturellen, magnetischen und elektrischen Eigenschaften dieser Materialien werden dargelegt sowie ein Literaturüberblick über experimentelle und theoretische Arbeiten gegeben. Im dritten Kapitel werden die im Rahmen dieser Arbeit verwendeten Probenpräparations- und Charakterisierungsmethoden vorgestellt und technische Details sowie physikalische Grundlagen erläutert. Die Entwicklung eines neuen Probendesigns zum Nachweis des TMR-Effekts in ZnxFe3-xO4-basierten MTJs ist Gegenstand des vierten Kapitels. Die Entwicklung des Probenaufbaus sowie die daraus resultierende Probenprozessierung werden beschrieben. Die beiden letzten Kapitel befassen sich mit der strukturellen, elektrischen und magnetischen Charakterisierung der mittels PLD abgeschiedenen Dünnfilme sowie der Tunnelkontaktstrukturen.

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Han, Man Huon. "Development of synthesis method for spinel ferrite magnetic nanoparticle and its superparamagnetic properties." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/26465.

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Thesis (Ph. D.)--Chemistry and Biochemistry, Georgia Institute of Technology, 2009.
Committee Chair: Z. John Zhang; Committee Member: Angus Wilkinson; Committee Member: C P Wong; Committee Member: E. Kent Barefield; Committee Member: Mostafa El-Sayed. Part of the SMARTech Electronic Thesis and Dissertation Collection.

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Mercier, Adrien. "Contribution à l'étude et à la réalisation de composants magnétiques monolithiques réalisés par PECS/SPS et à leurs applications en électronique de puissance." Thesis, Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLN057/document.

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L’augmentation des fréquences de commutation des alimentations induit de nouvelles problématiques pour les composants. Que ces composants soient actifs ou passifs, il est nécessaire de contrôler les pertes afin que les rendements restent acceptables. La thèse se propose d’étudier et de fabriquer une nouvelle structure de transformateur destiné à s’insérer dans une alimentation à découpage. Ces transformateurs sont produits à l’aide du procédé PECS/SPS, qui est une technologie de frittage. Cette technologie permet de fritter des ferrites tout autour des enroulements primaires et secondaires. Il en résulte que les composants sont monolithiques.Une première partie présente l’état de l’art, ainsi que le magnétisme dans la matière. Il s’ensuit un chapitre dédié à la fabrication des matériaux magnétiques utilisés durant la thèse : les ferrites.Une deuxième partie concerne les ferrites fabriqués par le procédé PECS/SPS. Il est question dans un premier temps d’étudier l’anisotropie magnétocristalline de ces matériaux, et il est possible de la diminuer en jouant sur la composition chimique. Dans un second temps, d’autres grandeurs telles que la perméabilité ou la polarisation sont mesurées, toujours en fonction de la composition chimique. Les principaux résultats montrent que le frittage par le procédé PECS/SPS est plus réducteur que le frittage classique, ce qui dégrade certaines propriétés comme la résistivité des ferrites. Un dernier chapitre est dédié à la réalisation des transformateurs monolithiques. Un protocole détaillé de la fabrication est alors présenté.Une troisième partie illustre le fonctionnement des transformateurs réalisés. Les mesures usuelles permettent d’identifier les inductances propres, mutuelles et de fuite. Les valeurs de ces inductances montrent qu’il est plus judicieux d’utiliser les composants fabriqués non pas en tant que transformateur, mais en tant que coupleur. Enfin un convertisseur basé sur une structure de type VRM est réalisé. La fréquence de découpage est de 2 MHz, le rendement est supérieur à 90 %, et la densité de puissance est de 15 kW/litre
The increase in switching frequency of power supply induces new problems for the components. These components are active or passive, it is necessary to control the losses so that efficiency remains acceptable. The thesis deals with the study and production of a new transformer structure intended to be part of a switching power supply. These transformers are produced using PECS/SPS method, which is a sintering technology. This technology can be sintered ferrite around the primary and secondary windings. It follows that the components are monolithic.A first part presents the state of the art, and magnetism in the matter. It follows a chapter dedicated to the manufacture of magnetic materials used in the thesis : the ferrites.A second part concerns the ferrites produced by the PECS / SPS process. Firstly, the magnetocrystalline anisotropy of these materials is studied, and it is possible to decrease it by varying the chemical composition. In a second stage, other variables such as the permeability or the polarization are measured, always depending on the chemical composition. The main results show that the sintering by PECS / SPS method is more reducing than conventional sintering, which degrades certain properties such as the resistivity of the ferrites. The last chapter is dedicated to the realization of monolithic processors. A detailed manufacturing protocol is presented.A third part shows the operation of the realized transformers. The usual measurements allow identifying self, mutual and leakage inductances. The values of these inductances show that it is better to use components made not as a transformer, but as a coupler. Finally a converter based on a VRM structure is realized. The switching frequency is 2 MHz, the efficiency is greater than 90%, and the power density is 15 kW / liter

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Moura, Alysson Elson Galv?o de. "S?ntese, sinteriza??o e caracteriza??o de ferritas ? base de Ni-Zn." Universidade Federal do Rio Grande do Norte, 2008. http://repositorio.ufrn.br:8080/jspui/handle/123456789/17599.

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Made available in DSpace on 2014-12-17T15:41:43Z (GMT). No. of bitstreams: 1 AlyssonEGM.pdf: 4274696 bytes, checksum: 0f940193275b15ce59b4b1f45e3dc11c (MD5) Previous issue date: 2008-09-24
Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico
Were synthesized different ferrites NixZn1-xFe2O4 (0,4 ≤ x ≤ 0,6) compositions by using citrate precursor method. Initially, the precursors citrates of iron, nickel and zinc were mixed and homogenized. The stoichiometric compositions were calcined at 350?C without atmosphere control and the calcined powders were pressed in pellets and toroids. The pressed material was sintered from 1100? up to 1200?C in argon atmosphere. The calcined powders were characterized by XRD, TGA/DTG, FTIR, SEM and vibrating sample magnetometer (VSM). All sintered samples were characterized using XRD, SEM, VSM and measurements of magnetic permeability and loss factor were obtained. It was formed pure ferromagnetic phase at all used temperatures. The Rietveld analyses allowed to calculate the cations level occupation and the crystallite size. The analyses obtained nanometric crystals (12-20 nm) to the calcined powder. By SEM, the sintered samples shows grains sizes from 1 to 10 μm. Sintered densities (ρ) were measured by the Archimedes method and with increasing Zn content, the bulk density decrease. The better magnetization results (105-110 emu/g) were obtained for x=0,6 at all sintering temperatures. The hysteresis shows characteristics of soft magnetic material. Two magnetization processes were considered, superparamagnetism at low temperature and the magnetic domains formation at high temperatures. The sintered toroids presents relative magnetic permeability (μr) from 7 to 32 and loss factor (tanδ) of about 1. The frequency response of toroids range from 0,3 kHz to 0,2 GHz. The composition x=0,5 presents both greater μr and tanδ values and x=0,6 the most broad range of frequency response. Various microstructural factors show influence on the behavior of μr and tanδ, such as: grain size, porosity across grain boundary and inside the grain, grain boundary content and domain walls movement during the process of magnetization at high frequency studies (0,3kKz 0,2 GHz)
Foram sintetizadas diferentes composi??es da ferrita Ni1-xZnxFe2O4 com 0,4 ≤ x ≤ 0,6 pelo uso do m?todo dos citratos precursores. Para se obter a fase estequiom?trica do sistema Ni1-xZnxFe2O4 foram misturados e homogeneizados os citratos precursores de ferro, n?quel e zinco. As composi??es estequiom?tricas foram calcinadas em atmosfera ambiente na temperatura de 350?C e depois prensadas em pastilhas e tor?ides. As amostras prensadas foram sinterizadas nas temperaturas de 1100?, 1150? e 1200?C em atmosfera de arg?nio. Os p?s calcinados foram caracterizados por DRX, TGA/DTG, FTIR, MEV e magnetometria de amostra vibrante (MAV) e as amostras sinterizadas por DRX, MEV, MAV, massa espec?fica e medidas de permeabilidade e perdas magn?ticas. Observou-se a forma??o de fase pura ferrimagn?tica em todas as temperaturas aplicadas. A an?lise pelo m?todo de Rietveld calculou o n?vel de ocupa??o dos c?tions e o tamanho de cristalito. Foram obtidos tamanhos de cristais nanom?tricos, de 12 a 20 nm para os p?s calcinados. Por MEV, as amostras sinterizadas apresentam tamanhos de gr?os na faixa de 1 a 10 μm. A massa espec?fica (ρ) do material sinterizado apresenta uma tend?ncia de diminui??o com a adi??o de Zn. Os melhores resultados de magnetiza??o foram obtidos para x=0,6 nas tr?s temperaturas de sinteriza??o, variando de 105 a 110 emu/g. As histereses mostram um perfil de materiais magn?ticos moles. Dois processos de magnetiza??o foram considerados, o superparamagnetismo a baixa temperatura (350?C) e a forma??o de dom?nios magn?ticos em altas temperaturas. Os materiais sinterizados apresentam permeabilidade (μ) de algumas unidades, de 7 a 30, e perdas magn?ticas (tanδ) por volta de 1. A resposta em freq??ncia dos n?cleos toroidais est? na faixa de 0,3 kHz a 0,2 GHz. Os maiores valores de μ e tanδ s?o para x=0,5 e a maior faixa de resposta em freq??ncia ? para x=0,6. V?rios fatores da microestrutura contribuem para o comportamento das grandezas μ e tanδ, tais como: os tamanhos dos gr?os, porosidade inter e intragranular, quantidade de contornos de gr?os e os aspectos da din?mica das paredes de dom?nios quando excitadas magneticamente sob alta freq??ncia

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Scarberry, Kenneth Edward. "Biomedical applications of cobalt-spinel ferrite nanoparticles for cancer cell extraction and drug delivery." Diss., Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/33951.

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In this presentation it is demonstrated that the unique magnetic properties of superparamagnetic cobalt-spinel ferrite nanoparticles can be employed in several novel applications. A method to selectively capture and remove pathogens from infected organisms to improve longevity is presented. Evidence is provided to show that automated methods using modified forms of hemofiltration or peritoneal dialysis could be used to eliminate the particle/pathogen or particle/infected cell conjugates from the organism postoperatively. It is shown that disparately functionalized nanoparticles can be used in concert as drug carrier and release mechanisms. Lastly, we provide preliminary evidence to support the use of magnetic nanoparticles for controlling reaction kinetics.

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Marija, Milanović. "Sinteza i karakterizacija nanočestičnih prahova na bazi cink-ferita." Phd thesis, Univerzitet u Novom Sadu, Tehnološki fakultet Novi Sad, 2010. https://www.cris.uns.ac.rs/record.jsf?recordId=82019&source=NDLTD&language=en.

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U ovom radu prikazani su rezultati ispitivanja strukturnih i magnetnih osobina čistih cink- ferita, ZnFe₂O₄ i cink-ferita sa dodatkom indijuma Zn_1-xIn_xFe₂O₄ i itrijuma, ZnY_xFe_2-xO₄, gde je 0 ≤ x ≤ 0,6. Prahovi na bazi cink-ferita su sintetisani koristeći nisko temperaturnu metodu sinteze iz tečne faze – metodu koprecipitacije. Osnovni cilj ove doktorske disertacije je bio da se utvrdi veza između uslova sinteze, uticaja različitih katjona, strukture i osobina čistih cink-feritnih nanočestica, kao i cink-ferita sa dodatkom indijuma i itrijuma. Radi praćenja uticaja veličine čestica dobijenog praha na strukturu i osobine ovih materijala, sintetisani čist cink-ferit je kalcinisan na različitim temperaturama. Posebno je razmatran i uticaj dodatka različitih jona na distribuciju i preraspodelu katjona u spinelnoj strukturi. Pored toga ispitivan je uticaj tako pripremljenih prahova na njihove magnetne osobine. Rentgenostrukturna i TEM analize potvrdili su da ispitivani uzorci spadaju u klasu nanomaterijala spinelne strukture. Analiza Raman i Mössbauer spektara je ukazala na moguću raspodelu katjona između tetraedarskih i oktaedarskih mesta, te formiranje delimično inverznog spinela. Ispitivanja magnetnih osobina su pokazala da histerezisne petlje ne pokazuju saturaciju u prisustvu jakog magnetnog polja, što je potvrdilo superparamagnetnu i jednodomensku prirodu čestica. Pokazano je da pored uticaja veličine čestica, dodatak različitih katjona (u ovom slučaju itrijum i indijum) ima veliki uticaj na uređenje strukture, a posledično i na magnetno ponašanje ispitivanih nanočestičnih sistema.
This thesis presents the results of the investigation of the structural and magnetic properties of nanostructured zinc ferrites, ZnFe2O4 and zinc ferrites supstituted with different amount of indium and yttrium, Zn1-xInxFe2O4 and ZnYxFe2-xO4 (0 ≤ x ≤ 0,6). Powders based on zinc ferrites were synthesised by a low temperature wet-chemical method – coprecipitation. The main purpose of this thesis was to establish the relationship between the synthesis, dopants, structure and properties of zinc ferrite based materials. Nanoparticles of ZnFe2O4 were calcined at different temperatures in order to elucidate the influence of the particle size on the magnetic properties of the obtained nanoparticles. In addition, we have investigated the effect of dopant addition on cation distribution in spinel structure, in order to modify the magnetic properties and to obtain the magnetic ceramics with improved properties compared to the bulk-counterparts. The results of X-ray and TEM analyses confirmed the nanosized nature and spinel type structure of the investigated samples. Raman and Mössbauer spectroscopy studies implied on the possible cation distribution between the tetrahedral and octahedral sites and formation of the partially inversed spinel. The study of the magnetic properties showed that hysteresis loops do not saturate even in the presence of high magnetic fields, which confirmed the superparamagnetic and single domain nature of the samples. These observations imply that, besides the particle size, doping (e.g. yttrium and indium) causes significant structural rearrangements which in turn induce changes in magnetic behavior of the investigated nanoparticulate systems.

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Books on the topic "Ferrites spinel"

Phillips, Peter John. Conduction processes in spinel ferrites. [s.l.]: typescript, 1991.

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Spinel Ferrite Nanostructures for Energy Storage Devices. Elsevier, 2020. http://dx.doi.org/10.1016/c2018-0-04420-5.

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Mane, Rajaram S., and Vijaykumar Jadhav. Spinal Ferrite Nanostructures for Energy Storage Devices. Elsevier, 2020.

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Mane, Rajaram S., and Vijaykumar Jadhav. Spinal Ferrite Nanostructures for Energy Storage Devices. Elsevier, 2020.

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Advanced Spinel Ferrite Nanocomposites for Electromagnetic Interference Shielding Applications. Elsevier, 2021. http://dx.doi.org/10.1016/c2018-0-05541-3.

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Houston, Victoria. Dead spider: A novel. 2017.

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12 Mile Remembered Our Lives Before They Burned Our Homesteads: Flooded and burned dreams of a small community in British Columbia. Victoria, Canada: Trafford Publishing, 2008.

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Book chapters on the topic "Ferrites spinel"

Tang, Gui-De. "Spinel Ferrites with Canted Magnetic Coupling." In New Itinerant Electron Models of Magnetic Materials, 129–46. Singapore: Springer Singapore, 2021. http://dx.doi.org/10.1007/978-981-16-1271-8_8.

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Tang, Gui-De. "Magnetic Ordering of Typical Spinel Ferrites." In New Itinerant Electron Models of Magnetic Materials, 81–100. Singapore: Springer Singapore, 2021. http://dx.doi.org/10.1007/978-981-16-1271-8_6.

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Tailhades, Ph. "Original Spinel Ferrites for New Mass Storage Media." In Nano-Crystalline and Thin Film Magnetic Oxides, 3–26. Dordrecht: Springer Netherlands, 1999. http://dx.doi.org/10.1007/978-94-011-4493-3_1.

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Sharath, R., Nagaraju Kottam, H. Muktha, K. Samrat, M. Chandraprabha, R. Harikrishna, and Bincy Rose Vergis. "Spinel Ferrites—A Future Boon to Nanotechnology- Based Therapies." In Nanomaterials, 297–316. Oakville, ON ; Waretown, NJ : Apple Academic Press, [2018]: Apple Academic Press, 2018. http://dx.doi.org/10.1201/b21267-14.

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Tang, Gui-De. "Experimental Evidences of the IEO Model Obtained from Spinel Ferrites." In New Itinerant Electron Models of Magnetic Materials, 101–27. Singapore: Springer Singapore, 2021. http://dx.doi.org/10.1007/978-981-16-1271-8_7.

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Msomi, J. Z., T. Moyo, and K. Bharuth-Ram. "MÖssbauer and XRD Study of (Zn, Cd) x Co1−x Fe2−x Al x O4 Spinel Ferrites." In Hyperfine Interactions (C), 181–84. Dordrecht: Springer Netherlands, 2002. http://dx.doi.org/10.1007/978-94-010-0281-3_45.

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Sharma, Ruchi, and Satbir Singh. "The Role of Various Spinel Ferrites Magnetic Nanoparticles in the Improvement of Photovoltaic Performance of Organic Solar Cell: A Review." In Springer Proceedings in Energy, 193–99. Cham: Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-63085-4_26.

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Greenblatt, M., and B. Raveau. "Oxides Based on the Spinel Structure; Hexagonal Ferrites, β-Alumina Oxide Types, and LiX M2 O4 (M = Ti, V, Mn)1-3." In Inorganic Reactions and Methods, 195–96. Hoboken, NJ, USA: John Wiley & Sons, Inc., 2007. http://dx.doi.org/10.1002/9780470145203.ch129.

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Frolova, L. A., O. A. Pivovarov, O. A. Kushnerov, and N. M. Tolstopalova. "Peculiarities of the Crystal-Chemical Structure of Spinel Ferrites CoxFe3-xO4 (0.25 ≤ x ≤1) Obtained Under the Action of a Low-Temperature Contact Nonequilibrium Plasma." In Springer Proceedings in Physics, 79–87. Cham: Springer International Publishing, 2018. http://dx.doi.org/10.1007/978-3-319-92567-7_5.

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Dolia, S. N., Arun S. Prasad, M. S. Dhawan, M. P. Sharma, and Subhash Chander. "Magnetic behaviour of nanocrystalline Ni0.5Cu0.5Fe2O4 spinel ferrite." In ICAME 2007, 489–95. Berlin, Heidelberg: Springer Berlin Heidelberg, 2008. http://dx.doi.org/10.1007/978-3-540-78697-9_64.

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Conference papers on the topic "Ferrites spinel"

Allendorf, Mark D., Richard B. Diver, James E. Miller, and Nathan P. Siegel. "Thermodynamic Analysis of Mixed-Metal Ferrites for Hydrogen Production by Two-Step Water Splitting." In ASME 2006 International Solar Energy Conference. ASMEDC, 2006. http://dx.doi.org/10.1115/isec2006-99114.

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A thermodynamic analysis of the two-step water splitting process for the production of hydrogen is reported in this paper. Calculations simulating the preparation of ferrite samples, their thermal reduction to form a mixture of metal oxides, and subsequent reoxidation with steam to produce hydrogen were performed. Mixed-metal spinel ferrites of the general form MFe2O4, where M = Co, Ni, or Zn, are compared with iron spinel, Fe3O4. The results indicate that of the four ferrites examined, nickel spinel has the most favorable combination of properties for use in two-step water splitting.

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Borikar, M. A., D. M. Borikar, A. S. Kakde, and K. G. Rewatkar. "Nickel nano spinel ferrites: Synthesis and characterization." In 2016 International Conference on Electrical, Electronics, and Optimization Techniques (ICEEOT). IEEE, 2016. http://dx.doi.org/10.1109/iceeot.2016.7755306.

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OCHMANN, Martin, Fredericus M. A. LINDERHOF, and Libor MACHALA. "Spinel ferrites nanoparticles for alloy steel protective layers." In NANOCON 2020. TANGER Ltd., 2020. http://dx.doi.org/10.37904/nanocon.2020.3722.

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Kaczmarek, W. A., A. Calka, and B. W. Ninham. "Magnetic Properties Of Aerosol Synthesized Co-substituted Spinel Ferrites." In 1993 Digests of International Magnetics Conference. IEEE, 1993. http://dx.doi.org/10.1109/intmag.1993.642605.

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Lazarevic, Zorica, Aleksandra Milutinovic, Maja Romcevic, Nebojsa Romcevic, Cedomir Jovalekic, Dalibor Sekulic, and Milos Slankamenac. "Soft mechanochemical synthesis and characterization of nanodimensional spinel ferrites." In 2012 Joint 21st IEEE ISAF / 11th IEEE ECAPD / IEEE PFM (ISAF/ECAPD/PFM). IEEE, 2012. http://dx.doi.org/10.1109/isaf.2012.6297730.

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Hooda, Ashima, Sujata Sanghi, Ashish Agarwal, Satish Khasa, and Bhawana Hooda. "Rietveld refinement and electrical properties of Ni-Zn spinel ferrites." In DAE SOLID STATE PHYSICS SYMPOSIUM 2016. Author(s), 2017. http://dx.doi.org/10.1063/1.4980251.

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Ashima, S. Dagar, Sonia, Krittika, and S. Khasa. "Structural and electrical properties of Ni-Mg-Zn spinel ferrites." In DAE SOLID STATE PHYSICS SYMPOSIUM 2019. AIP Publishing, 2020. http://dx.doi.org/10.1063/5.0016667.

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Nandanwar, A. K., D. S. Chaoudhary, S. A. Tirpude, and K. G. Rewatkar. "Synthesis and Electric behavior of Cd-doped nano-size spinel ferrites." In International Conference on Science and Engineering for Sustainable Development. Infogain Publication, 2017. http://dx.doi.org/10.24001/icsesd2017.38.

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Thummer, K. P., Ashish R. Tanna, and Hiren H. Joshi. "Rietveld structure refinement and elastic properties of MgAlxCrxFe2−2xO4 spinel ferrites." In FUNCTIONAL OXIDES AND NANOMATERIALS: Proceedings of the International Conference on Functional Oxides and Nanomaterials. Author(s), 2017. http://dx.doi.org/10.1063/1.4982142.

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Branická, Eva, Mariana Ušáková, Elemír Ušák, Martin Šoka, and Edmund Dobročka. "Effect of Eu substitution on magnetic behavior of spinel nickel ferrites." In APPLIED PHYSICS OF CONDENSED MATTER (APCOM 2019). AIP Publishing, 2019. http://dx.doi.org/10.1063/1.5119456.

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Reports on the topic "Ferrites spinel"

Stevenson, Jeffry W., Eric M. Riel, Elizabeth V. Stephens, and Mohammad A. Khaleel. Surface Treatments for Improved Performance of Spinel-coated AISI 441 Ferritic Stainless Steel. Office of Scientific and Technical Information (OSTI), January 2013. http://dx.doi.org/10.2172/1068652.

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Yang, Zhenguo, Guanguang Xia, Chong M. Wang, Zimin Nie, Joshua D. Templeton, Prabhakar Singh, and Jeffry W. Stevenson. Investigation of AISI 441 Ferritic Stainless Steel and Development of Spinel Coatings for SOFC Interconnect Applications. Office of Scientific and Technical Information (OSTI), May 2008. http://dx.doi.org/10.2172/1019232.

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