Dissertations / Theses on the topic 'Ferrite'
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Morin, Victor. "Elaboration de composites multiférroïque et caractérisation de l'effet magnétoélectrique." Thesis, Université Paris-Saclay (ComUE), 2015. http://www.theses.fr/2015SACLN030/document.
Full textThe magnetoelctric (ME) response consists in the modification of the electric polarization by an applied magnetic field (direct effect) or the modification of the magnetic polarization by an applied electric field (inverse effect). Intrinsic multiferroics are rather uncommon and the effect is often weak at room temperature. An alternative route to achieve ME effect, consists in using magnetostrictive and piezoelectric materials and coupling the two phases by mechanical stress. We draw (theoretically and experimentally) some material characteristics to achieve an importantME effect, which justify the use of ferrite and PZT. We describe the production process of the two studied connectivity schemes (stack of layers or inclusion of a phase in another). We focus on the sintering by Spark Plasma Sintering as a potential improvement of the mecanical bonding. We devoted a part of our work on multilayer composite and showed the importance of some factors such as the demagnetizing effect or the symmetry of the structure. We introduce a current sensor prototype suitable for electrical engineering application. We showed its good linearity and sensitivity but also some effects of its bandwidth
Janasi, Suzilene Real [UNESP]. "Ferrita de bário: preparação de fases dopadas com cobalto, titânio e estanho." Universidade Estadual Paulista (UNESP), 1997. http://hdl.handle.net/11449/102592.
Full textA substituição parcial de íons Fe3+ por pares de íons (Co2+-Ti4+ ou Co2+-Sn4+) na ferrita de bário hexagonal (BaFe12O19) leva a uma substancial diminuição no campo coercitivo (Hc) com uma pequena mudança na magnetização de saturação (Ms), permitindo seu uso em gravação magnética e magneto-óptica de alta densidade. Os diferentes métodos de preparação de ferritas de bário resultam em produtos com propriedades distintas. Neste trabalho, preparou-se BaFe12-2xCoxTixO19 e BaFe12-2xCoxSnxO19 (0,25 £ x £ 1) por coprecipitação, utilizando cloretos dos metais precursores e solução de KOH/K2CO3 como precipitante. Após a secagem, o produto obtido foi calcinado a 950oC por 3h, lavado e seco. Os difratogramas de raios X indicaram a formação da ferrita de bário. As micrografias eletrônicas de varredura mostraram que os pós obtidos apresentam-se na forma de plaquetas hexagonais de 1 a 2mm. As curvas de magnetização das ferritas de bário dopadas mostraram que o campo coercitivo e a remanência diminuem em função do aumento da razão de substituição x. A curva de magnetização da amostra dopada com Co-Ti, com x = 1 é característica de uma ferrita mole, com Hc = 13,5 kA.m-1 (0,17 kOe), Ms = 46,1 emu.g-1 e Mr = 11,0 emu.g-1. Para a amostra dopada com Co-Sn a diminuição de Mr não é significante. Estes resultados mostraram que as propriedades magnéticas das ferritas de bário dopadas obtidas por coprecipitação foram melhoradas, em relação aos dados da literatura para ferrita de bário pura ou dopada.
The partial substitution of Fe3+ ions with pairs of ions (Co2+-Ti4+ or Co2+-Sn4+) in hexagonal barium ferrite (BaFe12O19) leads to a substantial reduction on coercivity (Hc) with only a low change in saturation magnetization (Ms), allowing its use in high density magnetic and magneto-optical recording. Different preparative methods result in barium ferrites with distinguished properties. In this work, BaFe12-2xCoxTixO19 and BaFe12-2xCoxSnxO19 (0.25 £ x £ 1) were prepared by the coprecipitation method using chloride salt precursors and KOH/K2CO3 solution. After drying, the powder was calcinated at 950oC by 3 h, washed and dried. The X ray diffraction patterns indicated the barium ferrite phase formation. The scanning electron micrographs showed that the particles are hexagonal platelike with diameter size ranging from 1 to 2 mm. The magnetization curves of substituted barium ferrites showed that the values of Hc and Mr decrease with the increase of the substitution ratio x. The magnetization curve profile for Co-Ti substituted sample with x =1 is characteristic of a soft ferrite with Hc = 13.5kA.m-1 (0.17 kOe), Ms = 46.1 emu.g-1 and Mr = 11.0 emu.g-1. These results indicated that the magnetic properties of substituted barium ferrites obtained by coprecipitation were improved when compared with the literature data for pure and substituted barium ferrite.
Mahhouti, Zakaria. "Synthesis and characterization of functional monodispersed cobalt ferrite nanoparticles." Electronic Thesis or Diss., Amiens, 2019. http://www.theses.fr/2019AMIE0010.
Full textIn the present work, monodisperse cobalt ferrite nanoparticle systems have been explored in regard to their magnetic properties and magnetostrictive effect, as well as for use as a ferrofluid. Nanoparticles have been successfully dispersed in an organic solvent. The surface chemistry of the magnetic nanoparticle proves critical to obtaining a homogeneous and well separated high density dispersion in Hexane. In addition, Oleic acid was used to alter the surface of cobalt ferrite nanoparticles and successfully achieve good dispersion. The obtained nanoparticles are characterized using XRD, Raman spectroscopy, TGA, FT-IR, DLS, SEM, and magnetic investigations. Using STEM analysis, we found that the size and shape of nanoparticles could be controlled by varying certain parameters such as the synthesis temperature, the quantity, and nature of reagents. Furthermore, porous anodic membranes with highly ordered pores were successfully fabricated with multi-steps anodizing. Cobalt ferrite nanorods were produced by a transformation of CoFe2O4 nanoparticles using anodic alumina membrane. The insertion of CoF2O4 nanoparticles into the pores of the AAO membranes was studied with a scanning electron microscope, and it was possible to follow the behavior of CoFe2O4 nanoparticles in the pores during the insertion step as well as the transformation step
Dunn, Daniel S., Matthew S. Telep, and Eugene P. Augustin. "Variable Polarization Ferrite Antenna." International Foundation for Telemetering, 1994. http://hdl.handle.net/10150/611640.
Full textThis paper describes a ferrite antenna that can produce any polarization on the Poincaré sphere over the frequency range of 9.0 to 11.4 GHz by utilizing Faraday rotation and a quarter-wavelength phase shifter. All possible polarizations of the electromagnetic wave are achievable with this antenna which includes linear, circular and elliptical polarizations. Any tilt angle of elliptical polarization and any orientation of the linear polarization can be achieved as well. The polarization of the ferrite antenna can be electronically switched to a different polarization instantly without the use of moving parts. An automatic data acquisition system was designed and built to fully analyze the antenna' s characteristics.
Ajroudi, LIlia. "Ferrites de cobalt nanostructurés ; élaboration, caractérisation, propriétés catalytiques, électriques et magnétiques." Thesis, Toulon, 2011. http://www.theses.fr/2011TOUL0017/document.
Full textThis work is devoted to the synthesis and the study of the physical properties of cobalt ferrite nanomaterials. Thecobalt ferrite nanopowders (CoxFe3-xO4 , x=0.6,1,1.2,1.8 ) were synthesized by a new solvo thermal chemical route.The nanopowders are highly crystallized, very homogeneous in size and chemical composition. The nanopowderssizes are ranged from 4 nm for high cobalt content to 7 nm for low cobalt content. They are single phased, with thespinel structure, and a cell parameter varying with the cobalt content. The cobalt ferrites do not oxidize, when heatedunder air. For compositions near x=1, the cobalt ferrites are stable when heated under air up to 900°C, as for the othercompositions, phase transformations occur above 550°C.The catalytic measurements have shown the oxidation of CH4 into CO2 in presence of the catalyst for all thecompositions. Cobalt ferrite with composition x=1.8, presents the lowest activation energy and the best catalyticefficiency; this can be related to the great specific surface and the high rate of active sites for this composition.Concerning the conduction properties, the cobalt ferrites exhibit a semiconductor character up to 500-600 ° C and ametallic one above. Changes in conductivity from a composition to another are explained by changes in the number ofpairs [Co2+, Fe3+].A superparamagnetic behaviour was evidenced whatever the composition. This is due for one part to a size and shapeeffect and for the other part to different cationic distribution between tetrahedral and octahedral sites. These ferriteshave a saturation magnetization close to that of the massive state, because of the high crystallinity of the nanopowders,attributed to the synthesis method developed in this work
Janasi, Suzilene Real. "Ferrita de bário : preparação de fases dopadas com cobalto, titânio e estanho /." Araraquara : [s.n.], 1997. http://hdl.handle.net/11449/102592.
Full textBanca: Inês Joekes
Banca: Adley F. Rubira
Banca: Élson Longo
Banca: Carlos de Oliveira Paiva Santos
Resumo: A substituição parcial de íons Fe3+ por pares de íons (Co2+-Ti4+ ou Co2+-Sn4+) na ferrita de bário hexagonal (BaFe12O19) leva a uma substancial diminuição no campo coercitivo (Hc) com uma pequena mudança na magnetização de saturação (Ms), permitindo seu uso em gravação magnética e magneto-óptica de alta densidade. Os diferentes métodos de preparação de ferritas de bário resultam em produtos com propriedades distintas. Neste trabalho, preparou-se BaFe12-2xCoxTixO19 e BaFe12-2xCoxSnxO19 (0,25 £ x £ 1) por coprecipitação, utilizando cloretos dos metais precursores e solução de KOH/K2CO3 como precipitante. Após a secagem, o produto obtido foi calcinado a 950oC por 3h, lavado e seco. Os difratogramas de raios X indicaram a formação da ferrita de bário. As micrografias eletrônicas de varredura mostraram que os pós obtidos apresentam-se na forma de plaquetas hexagonais de 1 a 2mm. As curvas de magnetização das ferritas de bário dopadas mostraram que o campo coercitivo e a remanência diminuem em função do aumento da razão de substituição x. A curva de magnetização da amostra dopada com Co-Ti, com x = 1 é característica de uma ferrita mole, com Hc = 13,5 kA.m-1 (0,17 kOe), Ms = 46,1 emu.g-1 e Mr = 11,0 emu.g-1. Para a amostra dopada com Co-Sn a diminuição de Mr não é significante. Estes resultados mostraram que as propriedades magnéticas das ferritas de bário dopadas obtidas por coprecipitação foram melhoradas, em relação aos dados da literatura para ferrita de bário pura ou dopada.
Abstract: The partial substitution of Fe3+ ions with pairs of ions (Co2+-Ti4+ or Co2+-Sn4+) in hexagonal barium ferrite (BaFe12O19) leads to a substantial reduction on coercivity (Hc) with only a low change in saturation magnetization (Ms), allowing its use in high density magnetic and magneto-optical recording. Different preparative methods result in barium ferrites with distinguished properties. In this work, BaFe12-2xCoxTixO19 and BaFe12-2xCoxSnxO19 (0.25 £ x £ 1) were prepared by the coprecipitation method using chloride salt precursors and KOH/K2CO3 solution. After drying, the powder was calcinated at 950oC by 3 h, washed and dried. The X ray diffraction patterns indicated the barium ferrite phase formation. The scanning electron micrographs showed that the particles are hexagonal platelike with diameter size ranging from 1 to 2 mm. The magnetization curves of substituted barium ferrites showed that the values of Hc and Mr decrease with the increase of the substitution ratio x. The magnetization curve profile for Co-Ti substituted sample with x =1 is characteristic of a soft ferrite with Hc = 13.5kA.m-1 (0.17 kOe), Ms = 46.1 emu.g-1 and Mr = 11.0 emu.g-1. These results indicated that the magnetic properties of substituted barium ferrites obtained by coprecipitation were improved when compared with the literature data for pure and substituted barium ferrite.
Doutor
Souza, NatÃlia Dantas Gomes de. "Obtaining magnetic nanobiocompÃsitos consisting of galactomannan, glycerol and nickel ferrite and zinc." Universidade Federal do CearÃ, 2014. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=11766.
Full textFundaÃÃo de Amparo à Pesquisa do Estado do CearÃ
Nos Ãltimos anos, um grande interesse na associaÃÃo de materiais magnÃticos e biolÃgicos tem sido relatado na literatura. A obtenÃÃo de novos compÃsitos constituÃdos de galactomanana (GM), nanopartÃculas magnÃticas (MNPs) de NiZn e glicerol (GL) foram produzidos em diferentes proporÃÃes com finalidade de potencializar as caracterÃsticas individuais de cada material para futuras aplicaÃÃes. Sendo assim, as propriedades estruturais, magnÃticas e dielÃtricas dos nanobiocompÃsitos foram investigadas por DifraÃÃo de Raios-X (DRX), Espectroscopia de AbsorÃÃo na RegiÃo de Infravermelho (FTIR), AnÃlise TÃrmica (TG), Calorimetria ExploratÃria Diferencial (DSC), Microscopia EletrÃnica de Varredura (MEV), Microscopia EletrÃnica de TransmissÃo (TEM), Medidas MagnÃticas e Medidas DielÃtricas. A estrutura de espinÃlio da ferrita de NiZn foi confirmada por DRX e TEM e a amostra GMGL apesar de ser um material amorfo apresentou em seus nanobiocompÃsitos picos caracteristicos da fase de NiZn. As bandas caracterÃsticas para as amostras foram confirmadas por FTIR. Estas por sua vez seguiram um perfil de degradaÃÃo de acordo com as quantidades de NiZn incorporados, confirmados nos termogramas de DSC. A caracterizaÃÃo por MEV foi importante para avaliaÃÃo da morfologia. Os resultados das medidas dielÃtricas apresentaram baixas perdas dielÃtricas e das medidas magnÃticas mostraram comportamento magnÃtico para todos os nanobiocompÃsitos. Portanto, os resultados da caracterizaÃÃo dos nanobiocompÃsitos foram satisfatÃrios para possÃveis aplicaÃÃes como biomaterias, dispositivos eletrÃnicos ou em Ãreas afins.
In recent years, a great interest in the association of magnetic and biological materials has been reported in the literature. New composite consisting of galactomannan (GM), magnetic nanoparticles (NPs) of NiZn and glycerol (GL) were produced in different proportions with the purpose of enhancing the individual characteristics of each material for future applications. Thus, the structural, magnetic and dielectric properties of nanobiocomposites were investigated by Absorption Spectroscopy in the Region of Infrared (FTIR), X-Ray Diffraction (XRD), Thermal Analysis (TG), Differential Scanning Calorimetry (DSC), Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Magnetic Measurements and Dielectric Measurements. The structure of spinel NiZn ferrite was confirmed by XRD and TEM. Sample GMGL despite being an amorphous material presented in their nanobiocomposites characteristic peaks of phase NiZn. The characteristic bands in the samples were confirmed by FTIR. These in turn followed a degradation profile in accordance with the amounts of NiZn incorporated, which was confirmed in the DSC thermograms. The characterization by SEM was important to assess the morphology. The results of dielectric measurements showed low dielectric loss and magnetic measurements showed magnetic behavior for all nanobiocomposites. Therefore, the results of the characterization of nanobiocomposites were satisfactory for potential applications as biomaterials, electronic devices or related areas.
Brachwitz, Kerstin. "Defekt-induzierte Leitungsmechanismen und magnetische Eigenschaften spinellartiger Ferrite." Doctoral thesis, Universitätsbibliothek Leipzig, 2014. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-141251.
Full textQueck, Cham Kiong. "Planar ferrite coupled line circulators." Thesis, University of Manchester, 2003. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.488295.
Full textKirouane, Souad. "Conception et réalisation d'un isolateur coplanaire en bande X pour des applications télécoms." Thesis, Saint-Etienne, 2010. http://www.theses.fr/2010STET4002.
Full textThe minimization of circuits and the increasing frequency are two important issues of future communication systems. That requires a high degree of integration, higher performance at reduced cost. This work aims to design and implementation of new isolators on coplanar line based on two types of ferrite materials: barium hexaferrite (BaM) and garnet and yttrium iron (YIG). The first study presented on a planar layer of BaM leads to the feasibility of the isolator of field displacement in the 40-50 GHz band. The second one concerns the use of saturated YIG for applications around 10 GHz. The magnetic field displacement phenomenon appears when the magnetic substrate is polarized by a D.C. magnetic field. The new isolator structure is made from an asymmetric coplanar line put on a layer or magnetic substrate with a half ground plane placed under this substrate. Several sets of prototypes are fabricated and characterized from a measurement bench which is composed by a microwave prober and a vector network analyzer. The experimental results are very promising because low insertion loss (less than 1 dB) and isolation (over 16 dB) have been obtained
Viardin, Alexandre. "Modélisation par champ de phases de la croissance de la ferrite allotriomorphe dans les aciers Fe-C-Mn." Thesis, Vandoeuvre-les-Nancy, INPL, 2010. http://www.theses.fr/2010INPL014N/document.
Full textThe growth of allotriomorphic ferrite plays a major role in the formation of martensite bands in Dual-Phase steels. We have thus developed a phase field model to study the ferritic growth in different ternary Fe-C-X alloys, incorporating two necessary features. First, we have paid a particular attention to recover the different growth regimes due to the huge difference between the diffusion rates of Cand X substitutional species. Our calculations have exhibited a transition from fast paraequilibrium to slow orthoequilibrium in good agreement with experimental measurements in the literature. Second, austenite grain boundaries have been included in the model because they can conterbalance the manganese segregation bands, as shown in our calculations. Indeed, our results show that the bands can be broken bythe wetting of ferrite along the austenite grain boundaries, provided that the segregation is below a threshold value, and provided that the grain boundary energies are sufficiently high
Han, Ping. "Characterization of MnZn ferrite materials and finite element method for MnZn ferrite core loss calculations." Thesis, This resource online, 1995. http://scholar.lib.vt.edu/theses/available/etd-06082009-170857/.
Full textFernandes, de Medeiros Indira Aritana. "Nanostructuration de ferrites de cobalt CoxFe3-xO4 : Effets sur la catalyse et la détection de gaz polluants." Thesis, Toulon, 2018. http://www.theses.fr/2018TOUL0007/document.
Full textDifferent synthesis methods such as hydrothermal, solvothermal and thermal decomposition were developed to control nanoparticles shape and composition. The influence of synthesis parameters such as the nature of surfactants, the solvents, temperature and time of synthesis were also investigated. The powders were characterized by X-ray Diffraction and Transmission Electron Microscopy coupled with Dispersive Energy Spectroscopy. The catalytic and detection properties were evaluated in presence of CO and NO2 in synthetic air. CoxFe3-xO4 (x = 1, 1.5 ) nanooctahedra with 15-20 nm were produced by hydrothermal synthesis using different surfactants (CTAB, SDS and PVP). Nanocubes of CoFe2O4 were successfully obtained by solvothermal synthesis using oleylamine as surfactant. Nanooctahedra of CoxFe3-xO4 with x = 1.5 have higher activity for the CO conversion than those with x=1, and the conversion starts at lower temperature for the nanocubes. The nanocubes show lower sensitivity for the detection of NO2 than the nanooctahedra which indicates that the {111} faces are more reactive than the {100} ones in cobalt ferrites nanoparticles
Ajroudi, LIlia. "Ferrites de cobalt nanostructurés ; élaboration, caractérisation, propriétés catalytiques, électriques et magnétiques." Electronic Thesis or Diss., Toulon, 2011. http://www.theses.fr/2011TOUL0017.
Full textThis work is devoted to the synthesis and the study of the physical properties of cobalt ferrite nanomaterials. Thecobalt ferrite nanopowders (CoxFe3-xO4 , x=0.6,1,1.2,1.8 ) were synthesized by a new solvo thermal chemical route.The nanopowders are highly crystallized, very homogeneous in size and chemical composition. The nanopowderssizes are ranged from 4 nm for high cobalt content to 7 nm for low cobalt content. They are single phased, with thespinel structure, and a cell parameter varying with the cobalt content. The cobalt ferrites do not oxidize, when heatedunder air. For compositions near x=1, the cobalt ferrites are stable when heated under air up to 900°C, as for the othercompositions, phase transformations occur above 550°C.The catalytic measurements have shown the oxidation of CH4 into CO2 in presence of the catalyst for all thecompositions. Cobalt ferrite with composition x=1.8, presents the lowest activation energy and the best catalyticefficiency; this can be related to the great specific surface and the high rate of active sites for this composition.Concerning the conduction properties, the cobalt ferrites exhibit a semiconductor character up to 500-600 ° C and ametallic one above. Changes in conductivity from a composition to another are explained by changes in the number ofpairs [Co2+, Fe3+].A superparamagnetic behaviour was evidenced whatever the composition. This is due for one part to a size and shapeeffect and for the other part to different cationic distribution between tetrahedral and octahedral sites. These ferriteshave a saturation magnetization close to that of the massive state, because of the high crystallinity of the nanopowders,attributed to the synthesis method developed in this work
Bischoff, Marten. "Dielektrische Eigenschaften nanoskaliger Ferrite und Hochfrequenzmessungen." Karlsruhe : FZKA, 2005. http://bibliothek.fzk.de/zb/berichte/FZKA7175.pdf.
Full textLee, Chung-Kook. "Crystallization of Nano-sized barium ferrite." Diss., Georgia Institute of Technology, 1994. http://hdl.handle.net/1853/19920.
Full textDondero, Russell A. "Silica coating of spinel ferrite nanoparticles." Thesis, Georgia Institute of Technology, 2000. http://hdl.handle.net/1853/27375.
Full textMcAtamney, Karen Marie. "Transition metal aryloxides as ferrite precursors." Thesis, Queen's University Belfast, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.326372.
Full textKitra, Maria I. "Low-SAR ferrite handset antenna design." Thesis, Loughborough University, 2006. https://dspace.lboro.ac.uk/2134/35984.
Full textMercier, 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.
Full textThe 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
Recouvreur, Michel. "Contribution à l'étude des liants organiques pour ferrites étude de l'alcool polyvinylique dans le ferrite manganèse-zinc /." Grenoble 2 : ANRT, 1986. http://catalogue.bnf.fr/ark:/12148/cb37600681v.
Full textSauerwald, Frank. "Impedanzspektroskopie im System CoFe2O4-MnFe2O4." [S.l. : s.n.], 2005. http://archiv.ub.uni-marburg.de/diss/z2005/0094/.
Full textNemrava, Sandra [Verfasser]. "Synthese und Charakterisierung iso- und aliovalent substituierter M-artiger Ferrite und Ferrite des R-Typs / Sandra Nemrava." München : Verlag Dr. Hut, 2017. http://d-nb.info/1147674337/34.
Full textTourinho, Francisco. "Ferrofluides a base de ferrite de cobalt et de ferrite de manganese : elaboration, comportement physicochimique et magnetique." Paris 6, 1988. http://www.theses.fr/1988PA066570.
Full textTourinho, Francisco. "Ferrofluides à base de ferrite de cobalt et de ferrite de manganèse élaboration, comportement physicochimique et magnétique /." Grenoble 2 : ANRT, 1988. http://catalogue.bnf.fr/ark:/12148/cb376189349.
Full textMoura, 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.
Full textConselho 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
Oliveira, Flavio Henrique. "Preparação e caracterização de compostos tipo hidrotalcita com metais Ni-Fe-Cu." [s.n.], 2009. http://repositorio.unicamp.br/jspui/handle/REPOSIP/249014.
Full textDissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Quimica
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Resumo: Sistemas ternários tipo hidrotalcita contendo metais de transição Ni, Fe e Cu tendo o ânion interlamelar o carbonato foram preparados através de um estudo sistemático de composição e parâmetros de síntese. Diferentes quantidades de Cu foram introduzidas na camada tipo brucita da hidrotalcita, sendo estas quantidades de 10, 20, 30, 40 e 50 % em relação a quantidade de Níquel. De acordo com difratogramas para baixas quantidades de cobre (10 e 20 %) a fase hidrotalcita apresentou-se pura, para maiores quantidades de cobre ocorreu segregação de fase a qual foi identificada como CuO. A preparação dos compostos ternários foi feita tendo como razão de metal II para metal III 2:1, essa razão entre os metais foi confirmada através de análises de ICP a qual demonstrou exata proporção entre os metais nas amostras. Análise térmica apresentaram um comportamento típico para hidrotalcitas, apresentando duas transições características a 170 °C e a 280 ºC. Devido à ocorrência de alta segregação de fases que ocorre na precipitação com estes metais, foram realizados experimentos com diferentes temperaturas de precipitação e os resultados preliminares indicam a formação de uma fase pura em baixas temperaturas. Compostos preparados com 30 % de Cu a temperatura ambiente apresenta segregação de fase o que não ocorre a temperaturas próximas a 0 ºC, temperaturas elevadas (60 °C) favorecem a formação de óxidos durante a precipitação. Portanto baixas temperaturas de precipitação resultam em fases puras de hidrotalcitas para concentrações de cobre intermediarias, como conseqüência é possível preparar amostras com altas concentrações de cobre na estrutura lamelar com a fase da hidrotalcita pura. Com estes metais de transição na estrutura lamelar este sistema pode vir a ser um bom precursor na formação de óxidos dos respectivos metais que constituem o composto, com a finalidade de ser utilizada em catálise
Abstract: Ternary systems of hydrotalcite-like compouds containing transition metals Ni, Fe and Cu and the interlayer anion the carbonate were prepared through a systematic study of composition and synthesis parameters. Different amounts of Cu were introduced into the layer hydrotalcite, and the figure of 10, 20, 30, 40 and 50% on the amount of Nickel. According to difratograms, for low quantities of copper (10 and 20%) the phase is pure hydrotalcite and for larger quantities of copper segregation occurred, which was identified as CuO. The preparation of ternary compound was made with the ratio of metal II to metal III 2:1, the ratio between the metals was confirmed through analysis of ICP which showed exact proportion between the metals in the samples. Thermal analysis showed a typical behavior for hydrotalcite, presenting features two transitions to 170 ° C and 280 C. Due to the high occurrence of segregation of phases in the precipitation that occurs with these metals, experiments were performed with different temperatures and precipitation and the preliminary results indicate the formation of a pure phase at low temperatures. Compounds prepared with 30% of Cu at room temperature shows segregation of the stage that does not occur at temperatures close to 0 º C, high temperature (60 C) favor the formation of oxides during the precipitation. In conclusion, low temperatures of precipitation result in phases of pure hydrotalcite for an intermediary concentration of copper, as a result, is possible to prepare samples with high concentrations of copper in the lamellar structure with pure phase of hydrotalcite. With these transitions metals in the lamellar structure this systems might be a good precursor in the formation of oxides of the metals that constitute the compound in order to be used in catalysis
Mestrado
Quimica Inorganica
Mestre em Química
Giske, Gustav, and Mikael Hug. "Linear Ferrite Generator Prototype for Wave Power." Thesis, KTH, Hållbar utveckling, miljövetenskap och teknik, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-228744.
Full textEn linjär direktdriven generatorprototyp har designats på KTH, Kungliga Tekniska högskolan i Sverige. Prototypen är baserad på en nerskalad elektromagnetisk optimering gjord av Anders Hagnestål. Målet med projektet är att verifiera beräkningar experimentellt och genom att använda ferritmagneter finns det en möjlighet att utveckla en konkurrenskraftig och miljövänligare generator för vågkraftverk. Baserat på den elektromagnetiska optimeringen har en mekanisk design tagits fram med hjälp av datorstödd design (CAD). Hållfasthetsberäkningar har gjorts för att säkerställa att designen klarar av de stora magnetiska krafter den utsätts för. Vidare har även olika tekniker och utmaningar som uppstått i byggnationen utvärderats och beskrivits. En beskrivning av designens fördelar och den grundläggande elektromagnetiska designen har även inkluderats. Byggnationen pågår och beräknas vara färdig under 2018.
Buron, Marie-Pierre. "Elaboration, caractérisations structurale et morphologique, propriétés magnétiques de pigments composites : ferrite de cuivre-magnétite, ferrite de cobalt-magnétite." Toulouse 3, 1996. http://www.theses.fr/1996TOU30266.
Full textCamus, Olivier. "Modélisation des propriétés magnétiques de matériaux ferrite et de composites à base de ferrite absorbant le rayonnement électromagnétique." Vandoeuvre-les-Nancy, INPL, 1996. http://www.theses.fr/1996INPL022N.
Full textAltan, Hakki Ilhan. "X-band High Power Ferrite Phase Shifters." Master's thesis, METU, 2010. http://etd.lib.metu.edu.tr/upload/12612410/index.pdf.
Full textHatling, Oddmund. "Multiferroic, Magnetoelectric Nanoparticles : Lanthanum-substituted Bismuth Ferrite." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for materialteknologi, 2011. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-16315.
Full textQureshi, Omar Osman. "The modelling of ferrite-loaded helical devices." Thesis, University of Birmingham, 2011. http://etheses.bham.ac.uk//id/eprint/2918/.
Full textScott, Byron L. "Magneto-Optical Study of Cobalt Ferrite Nanoparticles." ScholarWorks@UNO, 2007. http://scholarworks.uno.edu/td/623.
Full textAbdulwahab, Khadijat Olabisi. "Synthesis and characterisation of monodispersed ferrite nanoparticles." Thesis, University of Manchester, 2013. https://www.research.manchester.ac.uk/portal/en/theses/synthesis-and-characterisation-of-monodispersed-ferrite-nanoparticles(d262d9d1-12d8-43e4-b355-6692411a7abb).html.
Full textPetosa, Aldo Carleton University Dissertation Engineering Electronics. "Ferrite and dielectric antennas for personal communications." Ottawa, 1995.
Find full textLiu, Yuhang. "First Principle Study of Multiferroic Bismuth Ferrite." Thesis, Uppsala universitet, Materialteori, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-364857.
Full textHug, Mikael, and Gustav Giske. "Linear Ferrite Generator Prototype for Wave Power." Thesis, KTH, Skolan för elektroteknik och datavetenskap (EECS), 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-239384.
Full textOhlsson, Simon. "IGSCC in weld with high ferrite content." Thesis, KTH, Fysik, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-252691.
Full textNguyen, Thi Yen Mai. "Ferrite-based micro-inductors for power systems on chip : from material elaboration to inductor optimisation." Toulouse 3, 2014. http://thesesups.ups-tlse.fr/2564/.
Full textOn-chip inductors are key passive elements for future power supplies on chip (PwrSoC), which are expected to be compact and show enhanced performance: high efficiency and high power density. The objective of this thesis work is to study the material and technology to realize small size (<4 mm²) and low profile (< 250 µm) ferrite-based on-chip inductor. This component is dedicated to low power conversion (˜ 1 W) and should provide high inductance density and high quality factor at medium frequency range (5-10 MHz). Fully sintered NiZn ferrites are selected as soft magnetic materials for the inductor core because of their high resistivity and moderate permeability stable in the frequencies range of interest. Two techniques are developed for the ferrite cores: screen printing of in-house made ferrite powder and cutting of commercial ferrite films, followed in each case by sintering and pick-and place assembling to form the rectangular toroid inductor. Test inductors were realized first so that the characterization could be carried out to study the magnetic properties of the ferrite core and the volumetric core losses. The core losses were fit from the measured curve with Steinmetz equation to obtain analytical expressions of losses versus frequency and induction. The second phase of the thesis is the design optimization for the on-chip ferrite based inductor, taking into account the expected losses. Genetic algorithm is employed to optimize the inductor design with the objective function as minimum losses and satisfying the specification on the inductance values under weak current-bias condition. Finite element method for magnetics FEMM is used as a tool to calculate inductance and losses. The second run of prototypes was done to validate the optimization method. In perspective, processes of thick-photoresist photolithography and electroplating are being developed to realize the completed thick copper windings surrounding ferrite cores
Fernandes, de Medeiros Indira Aritana. "Nanostructuration de ferrites de cobalt CoxFe3-xO4 : Effets sur la catalyse et la détection de gaz polluants." Electronic Thesis or Diss., Toulon, 2018. http://www.theses.fr/2018TOUL0007.
Full textDifferent synthesis methods such as hydrothermal, solvothermal and thermal decomposition were developed to control nanoparticles shape and composition. The influence of synthesis parameters such as the nature of surfactants, the solvents, temperature and time of synthesis were also investigated. The powders were characterized by X-ray Diffraction and Transmission Electron Microscopy coupled with Dispersive Energy Spectroscopy. The catalytic and detection properties were evaluated in presence of CO and NO2 in synthetic air. CoxFe3-xO4 (x = 1, 1.5 ) nanooctahedra with 15-20 nm were produced by hydrothermal synthesis using different surfactants (CTAB, SDS and PVP). Nanocubes of CoFe2O4 were successfully obtained by solvothermal synthesis using oleylamine as surfactant. Nanooctahedra of CoxFe3-xO4 with x = 1.5 have higher activity for the CO conversion than those with x=1, and the conversion starts at lower temperature for the nanocubes. The nanocubes show lower sensitivity for the detection of NO2 than the nanooctahedra which indicates that the {111} faces are more reactive than the {100} ones in cobalt ferrites nanoparticles
Gradzki, Pawel Miroslaw. "Core loss characterization and design optimization of high-frequency power ferrite devices in power electronics applications." Diss., This resource online, 1992. http://scholar.lib.vt.edu/theses/available/etd-06062008-165934/.
Full textVerdier, Thomas. "Elaboration de poudres nanostructurées de ferrites de manganèse-zinc par mécanosynthèse : Influence des paramètres de broyage." Rouen, 2006. http://www.theses.fr/2006ROUES042.
Full textSpinel ferrites compounds are widely used for their technological applications, which are essentially their magnetic and catalytic properties. Nanocrystalline Mn-Zn ferrites have been synthesized by high-energy ball milling in different media (tempered steel and WC) starting from simple oxides (α-Fe2O3, ZnO and MnO). This technique leads to a change in the distribution of cations in both sites, resulting in an increase of magnetic properties. X-ray diffraction, Mössbauer spectrometry and VSM are used to characterize the powders. This work shows that a redox reaction is observed between Fe11 and metalling iron during milling in steel medium, leading to a spinel phase containing some Fe11. The mechanism for the appearance of this phase is studied : ZnO seems to have a non negligeable influence on the synthesis, by creating an intermediate wüstite-type phase solid solution with FeO. Millings in WC medium permit to avoid the Fe11 contamination
Franklin, David Richard. "Theoretical and experimental study of the millimetre wave properties of barium hexaferrite." Thesis, University of Portsmouth, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.357577.
Full textQassym, Lilia. "Etude et mise au point de ferrites de structure grenat à basse température de frittage pour intégration dans les circulateurs hyperfréquences." Thesis, Université Paris-Saclay (ComUE), 2017. http://www.theses.fr/2017SACLS479/document.
Full textEmbedded systems in aircraft must comply with the requirements of mass, volume and cost. The active modules of electronic scanning antenna are, in this context, a strategic challenge in terms of mass, volume and reliability. Today, there are up to 1000 modules per antenna, each one containing a circulator-isolator in order to guarantee its performances. The technology of ferrite circulators and isolators remains the most efficient in terms of isolation and insertion losses. It is also fully passive as no external energy is required to work. However this technology is expensive due to complex mechanical assembling of the different materials: magnetic and dielectric ceramics, magnets, conductors made of copper and soft metallic material. The integration of such devices also requires the reduction of dimensions without increasing losses for power levels that can be high. Based on by multilayer ceramic components (capacitors and inductors) as well as Low Temperature Cofired Ceramics (LTCC) technology, a new way of manufacturing these components, is investigated in this PhD work.. The idea is to be able to cofire the heart of the component which is the most difficult to adjust and also determines the final volume. The ferrites which currently constitute the core of the circulators are ferrimagnetic garnets synthetized by using a conventional ceramic process and sintered at high temperature (> 1400°C). To make them compatible with LTCC technology, it is essential to reduce their sintering temperature. The targeted temperatures must be less than 1000°C in order to cofire with gold metal parts and, if possible, close to 900°C for circulators with silver. In this context, the objective of this PhD work was to develop a ferrimagnetic garnet for microwave applications with sintering temperatures close to 900°C. This ferrite was then used for the preparation of microwave circulators which are essential components in radar and telecommunications systems. In addition, studies of optimization of the magnetic and dielectric properties have also been carried out to meet the operating requirements (frequency band and power level)
Aygar, Gulfem. "Preparation Of Silica Coated Cobalt Ferrite Magnetic Nanoparticles For The Purification Of Histidine-tagged Proteins." Master's thesis, METU, 2011. http://etd.lib.metu.edu.tr/upload/12613894/index.pdf.
Full textit can be performed directly in crude samples containing suspended solid materials without pretreatment, and can easily isolate some biomolecules from aqueous systems in the presence of magnetic gradient fields. This thesis focused on the development of new class of magnetic separation material particularly useful for the separation of histidine-tagged proteins from the complex matrixes through the use of imidazole side chains of histidine molecules. For that reason surface modified cobalt ferrite nanoparticles which contain Ni-NTA affinity group were synthesized. Firstly, cobalt ferrite nanoparticles with a narrow size distribution were prepared in aqueous solution using the controlled coprecipitation method. In order to obtain small size of agglomerates two different dispersants, oleic acid and sodium chloride, were tried. After obtaining the best dispersant and optimum experimental conditions, ultrasonic bath was used in order to decrease the size of agglomerates. Then, they were coated with silica and this was followed by surface modification of these nanoparticles by amine in order to add functional groups on silica shell. Next, &ndash
COOH functional groups were added to silica coated cobalt ferrite magnetic nanoparticles through the NH2 groups. After that N&alpha
,N&alpha
-Bis(carboxymethyl)-L-lysine hydrate, NTA, was attached to carboxyl side of the structure. Finally, nanoparticles were labeled with Ni (II) ions. The size of the magnetic nanoparticles and their agglomerates were determined by FE-SEM images, particle size analyzer, and zeta potential analyzer (zeta-sizer). Vibrational sample magnetometer (VSM) was used to measure the magnetic behavior of cobalt ferrite and silica coated cobalt ferrite magnetic nanoparticles. Surface modifications of magnetic nanoparticles were followed by FT-IR measurements. ICP-OES was used to find the amount of Ni (II) ion concentration that was attached to the magnetic nanoparticle.
Yang, Shicheng. "Non reciprocal passive components on LTCC ferrite substrate." Thesis, Saint-Etienne, 2015. http://www.theses.fr/2015STET4020/document.
Full textThis thesis investigates passive non-reciprocal components (mainly circulators) based on ferrite Low Temperature Co-fired Ceramic (LTCC) substrate. The external magnets used in conventional circulators must be strong to overcome the ferrite's demagnetization field. The novel circulator presented herein uses an embedded winding within the ferrite substrate to magnetize the material from the inside, thereby significantly reducing the demagnetization effects. Because of the controllability of the bias field, the resulting device is also multifunctional: when the windings are energized by a current, the device operates as a dynamic circulator in which the circulation direction can be changed by switching the direction of the current. Unlike other LTCC circulators with external magnets, the proposed device can even operate as a power splitter by removing the bias current. A circulator prototype has been characterized in three states: unbiased, biased by winding and biased by winding and external magnets. When no current is applied, the transmission of each port is about -5 dB with return loss better than 20 dB at 14.8 GHz. When a current of 300 mA is injected into the winding, the measured insertion loss and isolation of the circulator is approximately 3 dB and 8 dB, respectively, whereas the return loss is better than 20 dB at 14.2 GHz. When external magnets are added in addition to the current of 200 mA, the insertion loss and isolation is improved to 1.6 dB and 23 dB, respectively at 14.2 GHz. The variation of the circulator's working frequency is 0.6 GHz. This is achieved firstly by the change of internal magnetization M when current is less than 120 mA, then the heat in the substrate due to the winding introduces more frequency shifting. The total size (L*W*H) is 8mm*8mm*1.1mm
Perevoshchikova, Nataliya. "Modeling of austenite to ferrite transformation in steels." Thesis, Université de Lorraine, 2012. http://www.theses.fr/2012LORR0342/document.
Full textTransformation in steels focusing on the thermodynamic and kinetics conditions at the alpha/gamma interfaces during the ferrite growth. The first chapter deals with the determination of thermodynamic equilibria between alpha and gamma with CalPhad thermodynamic description. We have developed a new hybrid algorithm combining the construction of a convex hull to the more classical Newton-Raphson method to compute two phase equilibria in multicomponent alloys with two sublattices. Its capabilities are demonstrated on ternary Fe-C-Cr and quaternary Fe-C-Cr-Mo steels. In the second chapter, we present a thick interface model aiming to predict the whole spectrum of conditions at an alpha/gamma interface during ferrite growth, from full equilibrium to paraequilibrium with intermediate cases as the most interesting feature. The model, despite its numerous simplifying assumptions to facilitate its numerical implementation, allows to predict some peculiar kinetics in Fe-C-X systems with a minimum of fitting parameters, mainly the ratio between the diffusivities of the substitutional element inside the thick interface and in bulk austenite. The third chapter deals with the phase field model of austenite to ferrite transformation in steels. A thorough analysis on the conditions at the interface has been performed using the technique of matched asymptotic expansions. Special attention is given to clarify the role of the interface mobility on the growth regimes both in simple Fe-C alloys and in more complex Fe-C-Mn alloys
Oliveira, Felipe Fernandes de. "Deposição de filmes BiFeO3 via spray pirólise e caracterização microestrutural e de propriedades elétricas e ópticas." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2015. http://hdl.handle.net/10183/131385.
Full textThis research investigated the deposition of thin films of bismuth ferrite (BFO) on silicon substrate using the spray pyrolysis technique based on inorganic salts as precursors. For this purpose water, ethylene glycol and ethanol/butyl carbytol (1:1) were used as solvents to prepare the solution for spraying. The depositions were carried out with different substrate temperatures for each solvent used: 200, 250, 300 and 350ºC. The film deposition at low temperatures (200°C) promotes the formation of cracks due to the arrival of the liquid state from droplets sprayed by the atomizer. When using solvent ethanol/butyl carbytol (1:1) the formation of dense films was verified for the different depositions. The thermal gravimetric (TGA) and differential thermal analysis (DTA) were performed for the as-deposited films at 200°C with different solvents for the study of possible reactions of thermal decomposition. The BFO films were heated at 550°C for one hour aiming to the formation of the crystalline state BiFeO3 with rhombohedral structure. The films were analyzed by Xray diffraction (XRD) and scanning electron microscopy (SEM) before and after treatment. The XRD showed the crystalline state obtained after the heat treatment at 550°C/1h. It was observed the formation of non-stoichiometric composition on the film. The SEM images showed formation of films regardless of the solvent used for the temperature to 200°C. However, the increase temperature promotes the formation of particles on the substrate. Applying the ethylene glycol solvent the formation of porous films appeared, since for ethanol/butyl carbytol (1:1) was observed the formation of dense films with the presence of cracks. The electrical characterization of the films will be performed using impedance spectroscopy (IS) coupled to a furnace in order to vary the temperature of the measures. The film deposited with ethylene glycol presents a major electrical conductivity than films deposited using ethanol/butyl carbytol or water. This behavior can be associated with a non-stoichiometric composition of BFO. Moreover, the optical properties were obtained by diffuse reflectance spectroscopy. The films present a band gap between 2.23 and 2.26 eV, approximately.
Aydogan, Eda. "Processing And Characterization Of Textured Barium Ferrite Ceramics." Master's thesis, METU, 2012. http://etd.lib.metu.edu.tr/upload/12614465/index.pdf.
Full textm average size were synthesized as seed crystals for the synthesis of BaHF platelets by RTGG method. After the washing of these platelets with dilute HNO3, pure BaHF powders and platelets were directed by tape casting which was followed by sintering using TGG phenomenon. Degree of achieved texturing in the processed ceramics was studied using Rietveld analysis, pole figure measurement and electron backscattered diffraction (EBSD).