Relevant bibliographies by topics / Lanthanum ferrite

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  2. Dissertations / Theses
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Academic literature on the topic 'Lanthanum ferrite'

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Published: 21 February 2023

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Journal articles on the topic "Lanthanum ferrite"

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Zhang, Chang Sen, and Leia Yang. "Microstructure and Magnetic Properties of La-Doped Barium-Ferrite." Advanced Materials Research 668 (March 2013): 706–9. http://dx.doi.org/10.4028/www.scientific.net/amr.668.706.

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The La-doped barium ferrites microparticles were successful synthesized by citrate sol-gel method. The structure, morphology and magnetic properties of the ferrite were characterized by X-ray diffraction analysis (XRD), scanning electron microscopy (SEM), differential thermal analysis (TG-DSC) and superconducting quantum interference device (SQUID). The results showed that the average crystallite size of La-doped barium-ferrite decreased with increasing La content. The morphology of the barium ferrite was spherical particles; however, doped lanthanum, barium ferrite changed into laminated structure. In addition, doping lanthanum improved the magnetic properties of the ferrite. The saturation magnetization (Ms) of La-doped M-type barium ferrite 67.70emu/g, it was greater than the non-doped M-type barium ferrite 57.45emu/g.
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Wang, Zi Min, and Shi Qiang Jiang. "Calcium Lanthanum Permanent Magnetic Ferrite Coupled with Soft Magnetic Ferrite." Advanced Materials Research 311-313 (August 2011): 1309–13. http://dx.doi.org/10.4028/www.scientific.net/amr.311-313.1309.

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This paper introduces the production method of calcium lanthanum permanent magnetic ferrite coupled with soft magnetic ferrite components. This type of calcium lanthanum permanent magnetic ferrite has excellent magnetic properties. Soft magnetic ferrite components (CoFe2O4) can be coupled effectively with permanent magnetic ferrite (the main ingredients: Ca0.548Sr0.120La0.542Fe12O19) by adding the additives (SrB2Si0.67O5.34 and CaSiO3), which can promote the sintering of the liquid permanent magnetic ferrite. This calcium lanthanum permanent magnetic ferrite can be significantly improved in the microstructure, density, magnetic properties.
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Taufiqu Rochman, Nurul, and Wisnu Ari Adi. "Analysis of Structural and Microstructure of Lanthanum Ferrite by Modifying Iron Sand for Microwave Absorber Material Application." Advanced Materials Research 896 (February 2014): 423–27. http://dx.doi.org/10.4028/www.scientific.net/amr.896.423.

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Analysis crystal structure of lanthanum ferrite by modifying iron sand has been carried out. Lanthanum ferrite included one of the functional materials which had composition of ABO3perovskite system. The lanthanum ferrite is prepared by iron sand and lanthanum oxide powders. The mixture was milled for 10h with the various composition of lanthanum content. The samples are sintered at a temperature of 1000 °C for 10h. The microstructure analyses showed that the particle shapes was polygonal with the varied particle sizes and uniform distribution on the surface of the sample. The phase composition of refinement result showed that the lanthanum ferrite formed empirical compound of La0.8Mg0.2Fe0.7Ti0.2Si0.1O3. The La0.8Mg0.2Fe0.7Ti0.2Si0.1O3phase has a structure orthorombic (P b n m) with lattice parameters a = 5.513(1) Å, b = 5.549(1) Å and c = 7.849(2) Å, α = β = γ = 90°, the unit cell volume of V = 240.2(9) Å3, and the atomic density of ρ = 6.293 gr/cm3. We concluded that this study has been successfully synthesized lanthanum ferrite material from modifying iron sand and has been understood changes in the parameters of the crystal structure and phase composition of this material. It was a great opportunity that the material can be used as a material candidate of absorber electromagnetic waves.
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Gupta, Meenal, Anusree Das, Dipankar Das, Satyabrata Mohapatra, and Anindya Datta. "Chemical Synthesis of Rare Earth (La, Gd) Doped Cobalt Ferrite and a Comparative Analysis of Their Magnetic Properties." Journal of Nanoscience and Nanotechnology 20, no. 8 (August 1, 2020): 5239–45. http://dx.doi.org/10.1166/jnn.2020.18528.

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Lanthanum (La) and gadolinium (Gd) doped cobalt ferrite nanoparticles are synthesized using a soft chemical approach. The analysis of these ferrites using X-ray diffraction (XRD) and transmission electron microscopy (TEM) shows that lattice spacing decreases in the doped ferrite samples. Magnetization data indicates towards the decrease of saturation magnetisation but increase in coercivity with doping. Mössbauer spectroscopy measurements at room temperature indicate increased occupancy of trivalent cations at tetrahedral site. The addition of rare earth dopants reduces the hard-magnetic character of cobalt ferrite.
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Kikuchi, Takeyuki, Tatsuya Nakamura, Masamichi Miki, Makoto Nakanishi, Tatsuo Fujii, Jun Takada, and Yasunori Ikeda. "Synthesis of Hexagonal Ferrites by Citric Complex Method." Advances in Science and Technology 45 (October 2006): 697–700. http://dx.doi.org/10.4028/www.scientific.net/ast.45.697.

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Various hexagonal ferrites, which include hard and soft ferrites, were prepared by citric complex method. High purity reagent of strontium carbonate, iron (III) nitrate ennnahydrate, cobalt (II) nitrate hexahydrate and lanthanum oxide were used as starting materials. Prepared aqueous solution was heated for dehydration and gelling. Thermal pyrolysis was carried out by heating the gel. The obtained precursor powders were ground with an alumina mortar and compacted by uniaxial pressing into disk specimens and then heated at temperature range between 1023K and 1523K in air. Phase identification and determination of lattice parameters were carried out by powder X-ray diffraction. Scanning Electron Microscope was utilized to investigate the microstructure of the polycrystalline ferrites. Magnetic properties were discussed by magnetization measurements by using a vibration sample magnetometer. Magnetization and coercive force were measured. In the case of M-type ferrite, M-type barium and strontium ferrites were formed at vary low temperature relative to by conventional synthesis. The lanthanum and cobalt substituted M-type strontium ferrite ultra fine powders prepared by citric complex method showed extremely large coercive force.
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Sorlateap, Sitthisak, and Wirunya Keawwattana. "Preparation and Magnetic Properties of La Substituted Barium Ferrites Synthesized by the Oxide one Pot Synthesis (OOPS) Process." Advanced Materials Research 634-638 (January 2013): 2250–53. http://dx.doi.org/10.4028/www.scientific.net/amr.634-638.2250.

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Lanthanum (La) substituted barium ferrite, Ba1-xLaxFe12O19(x=0.00-0.40) has been synthesized by the oxide one pot synthesis (OOPS) process. The crystalline structure and magnetic properties have been investigated by means of XRD, SEM and VSM. The XRD pattern matched with the barium ferrite structure. The saturation magnetization (Ms) and coercive field (Hc) of ferrites increased by substitution of La ions on Ba sites at the content up to x=0.15 and then decrease.
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Abdulameer Abbas, Hayder, Adnan Hussein Ali, and Ban Mohammad Hasan. "Morphology and magnetic properties of lanthanum (La3+) substituted manganese, chromium nano ferrites." International Journal of Power Electronics and Drive Systems (IJPEDS) 10, no. 2 (June 1, 2019): 1102. http://dx.doi.org/10.11591/ijpeds.v10.i2.pp1102-1109.

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<span>Several studies have been carried out to investigate the effect of Lanthanum (La<sup>3+</sup>) ion substitution on the structural and magnetic properties of manganese-chromium (Mn-Cr) ferrite of chemical formula Mn La<sub>x</sub>Cr Fe<sub>2</sub>O<sub>4</sub>(x=0.0, 0.25 and 0.5). Such studies have made efforts to improve the magnetic and structural properties of manganese-chromium (Mn-Cr) ferrite by using lanthanum substituted nano ferrites and then synthesized using the sol-gel method and annealed at a temperature of 700<sup>o</sup>C. The changes that occurred in the structure of the nano ferrites as a result of lanthanum substitution were identified using X-ray diffraction (XRD). Based on Debye-Scherrer equation, the XRD data were used in measuring the particle sizes of different diffraction and average crystallite size by means of Fourier Transform infrared spectroscopy (FTIR). In analyzing the morphology of the nano ferrites, scanning electron microscopy (SEM) was used, elemental compassion was studied using energy dispersive X-ray spectroscopy (EDAX), and the average particle diameter was determined using Transmission electron microscopy (TEM) studies. FTIR spectral analysis of the prepared samples under investigations revealed the formation of a single phase spherical particles. Two important absorption bands were observed; one (<em>ν<sub>1</sub></em>) around 556 cm<sup>-1</sup>, which is attributed to the intrinsic vibrations of tetrahedral complexes, while the other low frequency band (<em>ν<sub>2</sub></em>) was around 430 cm<sup>-1</sup>, and attributed to octahedral complexes.</span>
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Simner, S. P., J. F. Bonnett, N. L. Canfield, K. D. Meinhardt, J. P. Shelton, V. L. Sprenkle, and J. W. Stevenson. "Development of lanthanum ferrite SOFC cathodes." Journal of Power Sources 113, no. 1 (January 2003): 1–10. http://dx.doi.org/10.1016/s0378-7753(02)00455-x.

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Pérez-Ramírez, Javier, and Bent Vigeland. "Lanthanum ferrite membranes in ammonia oxidation." Catalysis Today 105, no. 3-4 (August 2005): 436–42. http://dx.doi.org/10.1016/j.cattod.2005.06.057.

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Syed, Komal, Jiayue Wang, Bilge Yildiz, and William J. Bowman. "Bulk and surface exsolution produces a variety of Fe-rich and Fe-depleted ellipsoidal nanostructures in La0.6Sr0.4FeO3 thin films." Nanoscale 14, no. 3 (2022): 663–74. http://dx.doi.org/10.1039/d1nr06121f.

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Dissertations / Theses on the topic "Lanthanum ferrite"

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Hatling, 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.

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In this report, 10 at% lanthanum was introduced to the perovskite structure of bismuth ferrite at the expense of bismuth through a modified Pechini wet chemical method. Green body powders were calcined at several temperatures, and the lattice parameters for each size were found by Rietveld refinement of X-ray powder diffraction data. The parameters displayed strong size-dependent properties, and the rhombohedral distortion from the cubic structure was reduced by decreased particle size. With decreasing crystallite size, the Néel temperature decreased and the cooperative cationic displacement (s - t) showed size dependence at crystallite sizes below 30 nm. A size-dependency was also observed in the Curie temperature.
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Esquirol, Audrey. "Characterisation of doped lanthanum ferrite cathodes for intermediate temperature solid oxide fuel cells." Thesis, Imperial College London, 2003. http://hdl.handle.net/10044/1/12007.

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De, La Fuente Garcia Elena Luisa. "Visible Light Photocatalyst for Water Purification and Self-Cleaning Coatings." Doctoral thesis, Università degli studi di Bergamo, 2018. http://hdl.handle.net/10446/108456.

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Pollution in water and atmosphere is a growing concern in the current society and demands short-term solutions. Conventional purification techniques like biological treatment, direct oxidation, etc. cannot eliminate low concentrations or some of the so-called emerging pollutants (hormones, detergents, pharmaceuticals, etc.) thus calling for the use of advanced oxidation processes (AOP), namely, techniques in which highly oxidising agents (mostly OH radicals) are produced to degrade organics compound, bacteria and viruses, reaching the complete mineralization or, at least, producing nontoxic by-products. One of these techniques is heterogeneous photocatalysis: redox reactions are developed on the surface of a solid catalyst that is activated by light. Nowadays the more employed and studied photocatalyst is titanium dioxide (TiO2). Its commercial applications are very diverse, including self-cleaning materials (cements, paints), antifogging materials (mirrors, glasses) and water and air purification devices. The operating limits of this effective photocatalyst are in the fact that it needs UV radiation to be activated, due to its relatively wide band gap (3.2 eV). This is a significant problem in economic terms, for high energy costs, in healthy terms, since UV radiation is dangerous for sight and skin, and it is a limit to the use of sunlight, as only 4 % of the solar spectrum that reaches the Earth surface is in the UV range. To overcome this problem, investigations are focused on TiO2 modifications to render it active with visible light (doping with metal and non-metal ions, coupling with other semiconductors, etc) as well as on the use of other semiconductors with narrower band gap. A ceramic material, lanthanum orthoferrite (LaFeO3), with ionic and electronic semiconductor properties, is synthesized in our laboratory since 2008 and it is studied for its application in the combustion cells. Knowing that it also works as photoconductor under visible light [3], it can be considered a good candidate to be used as visible light photocatalyst. Its effectiveness in the degradation of organic dyes and other molecules has been reported. After the successful degradation of organic compounds in the slurry tests carried up with the LaFeO3 powders, our group started to develop deposition systems in order to avoid filtration problems, such as loss of catalyst and costs, thus rendering the reuse of the photocatalyst easier to achieve a practical applicability. In the present thesis two deposition methods were studied: the preparation of a photocatalytic paint and the deposition of the catalyst over a ceramic foam by dip-coating process. In the first part of the work, LaFeO3 was added to a commercial water based paint. This innovative photocatalytic paint has been tested to prove two aspects: • Its self-cleaning performances, following the degradation of an azo dye under visible light irradiation. • The paint durability, executing accelerated ageing tests in a climatic chamber, and subsequently verifying visible alterations and possible diminution of its self-cleaning performances. In the second part, the objective was the application of the material for the wastewater treatment. In collaboration with the Universidad de Las Palmas de Gran Canaria a handy and resistant photocatalytic foam was developed, to avoid the vigorous continuous stirring required to keep powder in slurry and the necessary filtration after the reactions to reuse the photocatalyst. The support chosen was a commercial ceramic inert porous material (foam) and the deposition method was the dip-coating technique. To apply this coating technique high quantities of catalyst had to be used because it required the preparation of a very concentrate solution. For this reason and for a possible scaling up, the production rate of the photocatalyst in our laboratory had to be increased. The quality of the catalyst had been largely tested for low production rates. Theoretically the results of the synthesis must be the same; however, a complete characterization and determination of photocatalytic performances were carried out on three batches of catalyst prepared on a large scale. The photocatalytic foam and the different batches in slurry were tested in the degradation of 4-Nitrophenol. A comparison between the slurry test and the fixed bed test is presented.
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Morel, Antoine. "Amélioration des propriétés magnétiques des aimants permanents du type hexaferrite de strontium par la substitution lanthane - cobalt." Rouen, 2003. http://www.theses.fr/2003ROUES017.

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Les hexaferrites, en raison de leur faible coût et de leurs performances magnétiques, sont d'excellents matériaux pour produire des aimants permanents. Leur principale qualité est leur forte anisotropie magnétique uniaxiale. Leurs propriétés magnétiques peuvent être améliorées par substitution, notamment par la substitution lanthane-cobalt, comme le citent différents brevets apparus en 1998. Dans une première partie, nous avons, à l'aide de quatre techniques spectroscopiques (spectrométrie Mössbauer, spectroscopie Raman, résonance magnétique nucléaire et diffraction neutronique), étudié le positionnement de l'ion Co2+ dans la maille M des hexaferrites de composition Sr1-xLaxFe12-xCoxO19 synthétisées selon un procédé céramique classique. Les résultats montrent que l'ion Co2+ se place préférentiellement sur les sites octaédriques 4f2 et 2a. L'effet majeur observé sur les propriétés magnétiques intrinsèques est une forte augmentation du champ d'anisotropie magnétocristalline, mesuré par la méthode SPD (singular point detection), lorsque le taux de substitution augmente. Cet effet s'explique, à l'aide du " modèle de l'ion isolé " par la localisation de l'ion Co2+, lorsqu'il est associé à l'ion lourd La3+, sur les sites octaédriques dits " centraux " de la maille M. En outre, la dépendance en température du champ d'anisotropie magnétocristalline est fortement modifiée. La composition intrinsèquement la plus intéressante est Sr0,6La0,4Fe11,6Co0,4O19. L'étude des propriétés magnétiques des aimants montre une amélioration très significative. L'induction rémanente, la stabilité thermique et surtout le champ coercitif augmentent. En revanche, la rectangularité des courbes de désaimantation se dégrade. La composition optimale en terme de performances magnétiques, différente de l'optimum intrinsèque, est Sr0,8La0,2Fe11,8Co0,2O19. Cette différence s'explique par des effets microstructuraux antagonistes lorsque le taux de substitution devient supérieur à 0,2. En particulier, l'évolution du champ coercitif a été modélisée en tenant compte des évolutions microstructurales et des propriétés magnétiques intrinsèques. Enfin, dans le but de bénéficier pleinement des effets bénéfiques de cette substitution, les aimants ont été optimisés afin de corriger le défaut de rectangularité de leur courbe de désaimantation
Hexaferrites, due to their low cost combined with their magnetic properties, are excellent materials to produce permanent magnets. Their main quality is their high uniaxial magnetocrystalline anisotropy. As shown by different patents published in 1998, their magnetic properties can been improved by using the lanthanum-cobalt substitution. Firstly, using four spectroscopic methods (Mössbauer spectrometry, Raman spectroscopy, nuclear magnetic resonance and neutron diffraction), we localized the position of the Co2+ ion in the unit cell of the hexagonal M-type M phase in samples with the Sr1-xLaxFe12-xCoxO19 composition, synthesized with a classical ceramic process. The results show that Co2+ is localized in both 4f2 and 2a octahedral sites. The intrinsic magnetic properties are influenced by this substitution and the main effect is a strong increase of the magnetocristalline anisotropy field, as measured by the SPD (singular point detection) method, when the degree of substitution increases. This effect can be explained using the "single-ion model", and is attributed to the localization of the Co2+ ion, in relation with the presence of the La3+ ion, on the so-called "central" octahedral sites of the M unit cell. Moreover, the temperature dependence of the magnetocristalline anisotropy field is strongly modified. The most interesting intrinsic composition is Sr0. 6La0. 4Fe11. 6Co0. 4O19. The investigation of the magnet properties shows a significant improvement. The remanent induction, thermal stability and, mainly, coercive field increase. However, the squareness of the demagnetization curve decreases. The optimal composition giving the best final magnetic properties is Sr0. 8La0. 2Fe11. 8Co0. 2O19. This is different from the optimal intrinsic composition. This difference can be explained by negative microstructural effects when the degree of substitution is higher than 0. 2. Particularly, the behaviour of the coercive field has been accurately described by taking in account both microstrutural evolution and intrinsic magnetic properties. Finally, to take full benefit from the effects of this substitution, this magnets have been optimized to improve the squareness of their demagnetization curve
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Parras-Vazquez, Marina. "Phénomènes de non-stoechiométrie dans les systèmes BaFeO3-y et BaxLa1-xFeO3-y." Phd thesis, Université Sciences et Technologies - Bordeaux I, 1989. http://tel.archives-ouvertes.fr/tel-00159210.

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Les phénomènes de non-stoehiométrie dans les ferrites du système Ba-La-Fe-O dont les structures dérivent de la perovskite, ont été étudiés au moyen de diverses techniques (diffraction X, HRTEM, spectroscopie Mössbauer...).
Dans le système BaFe4+O3-BaFe3+O2.50 la structure et l'ordre des lacunes des phases BaFeO3-y dépendent du taux de lacunes (y) et corrélativement du rapport Fe4+/Fe3+ (t / (1-t)) directement lié aux conditions de synthèse (PO2, T). Pour y <~ 0.35, l'empilement est un mélange des types "hexagonal compact" et "cubique compact" conduisant à des structures de type perovskite 6H ou 12H lacunaires en oxygène alors que pour des valeurs de y plus élévées (y ~> 0.35) il devient "cubique compact". Dans ce domaine de compositions, la non-stoichiométrie est accomodée grâce à la formation de structures en microdomaines soit d'une phase monoclinique (BaFeO2.50), soit d'une phase orthorombique de composition voisine de BaFe02.55.
En revanche pour 0.25 < y < 0.37, on observe des phénomènes d'intercroissances entre une phase de type 6H et une phase dérivée de la perovskite cubique. Pour y <= 0.25, aucun ordre des lacunes à longue distance n'apparaît.
Dans le système LaFeO3-BaFeO2.50, quatre phases différentes, surstructures de la perovskite cubique, apparaissent en fonction du rapport Ba/La (x/(1-x)). Leur microstructure est discutée en fonction de la composition, de l'ordre Ba-La et du taux de lacunes (y).
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Pignard, Stéphane. "Elaboration par MOCVD à injection, caractérisations structurale et physique de films d'oxydes magnétiques : hexaferrite BaFe12O19 et pérovskite à magnétorésistance géante La(1-x)MnO(3-delta)." Grenoble INPG, 1997. http://www.theses.fr/1997INPG0189.

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Un des problemes majeurs des procedes cvd reside dans le controle precis de la pression de vapeur des precurseurs, lorsque ceux-ci sont liquides ou solides. Un nouveau procede, brevete dans notre laboratoire, permet de resoudre ce probleme : il s'agit du procede cvd a injection. Son principe est base sur l'injection controlee de micro-quantites d'une solution contenant les precurseurs. Le premier objectif de ce travail a ete la construction et la mise au point d'une nouvelle enceinte d'elaboration de couches minces par voie cvd basee sur ce principe. Dans l'effort d'augmentation de la densite de stockage sur milieu magnetique, l'enregistrement perpendiculaire suscite depuis de nombreuses annees un interet de tout premier plan. L'hexaferrite de baryum bafe#1#2o#1#9 presente des caracteristiques interessantes pour cette application : les films doivent etre textures et convenablement dopes pour reduire le champ d'anisotropie. Jusqu'alors seules des techniques physiques de depot ont ete utilisees pour la synthese de telles couches. Nous avons etudie la possibilite d'elaborer des films de bafe#1#2o#1#9 par voie chimique au moyen du procede cvd a injection. Concernant la lecture des informations stockees, l'accroissement de la densite de stockage necessite l'utilisation de nouvelles tetes de lecture : dans ce domaine, les tetes magnetoresistives sont les plus prometteuses. Les recherches se sont recemment intensifiees avec la decouverte de la magnetoresistance colossale des composes la#1#-#xa#xmno#3#-# (a=sr,ca,ba). Nous nous sommes interesses aux manganites de lanthane lacunaires la#1#-#xmno#3#-#, deposes sous forme de couches minces par cvd a injection, dont les proprietes ont ete peu etudiees jusqu'a ce jour. Nous montrons que la technique de depot mise au point peut etre tres performante pour l'elaboration de tels films. Les proprietes structurales et physiques des couches la#1#-#xmno#3#-# sont etudiees : une magnetoresistance de 20%/tesla est obtenue a temperature ambiante
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Ting-FangYu and 游婷芳. "Unsupported and silica-supported perovskite-type lanthanum manganite and lanthanum ferrite in the conversion of ethanol." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/9t4xfh.

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碩士
國立成功大學
化學工程學系
107
This study reports that the Lewis acid-base properties of peroskite-type LaMnO3 and LaFeO3 can be adjusted by immobilizing them on silica. Bulk LaMnO3 and LaFeO3 were strong base catalyst due to unsaturated-coordinated oxygen on the surface, While, after supported them on silica, the basic properties of bulk materials were diluted and simultaneously acidities improved due to the increased amounts of tetravalent B-site cations. Ethanol reactivity was performed to reflect the different acid-base properties of bulk and silica-supported LaMnO3 and LaFeO3. Under differential analysis conditions, bulk perovskites were active in base-catalyzed reactions such as reverse aldolization and Tishchenko reaction, while silica-supported perovskites were active in aldolization and dehydration. We also notice the higher aldolization activity over LaMnO3/SiO2 than that of LaFeO3/SiO2, the different activity was attributed to existence of excess mobile oxygen on the surface of LaMnO3/SiO2, forming aldolization-active Lewis acid (Mn4+)-base (nonstoichiometric oxygen) pair sites while these sites were absent in LaFeO3/SiO2 which was enriched with oxygen vacancies.
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Wu, chun-hsien, and 吳俊賢. "Films Thickness Dependence of Ferroelectric and Photovoltaic Properties of Lanthanum Doped Bismuth Ferrite." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/18060275025942903027.

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碩士
國立新竹教育大學
應用科學系碩士班
103
The photovoltaic effect was discussed under different thickness of Lanthanum doped BiFeO3 thin film. Thin film were deposited by RF-sputtering.First,LaNiO3 (LNO) was deposited on Si(100) substrate, then BiFeO3 was grown on LNO. The top electrode used aluminum doped zinc oxide (AZO). BFO thickness have 25, 50, 75, 100 and 150 nm, respectively, and the thickness was calibrated by X-ray reflectivity and field emission scanning electron microscopy. Surface roughness was carried out by atomic force microscopy. Lanthanum doped BFO have strain relaxation with film thickness increase which was observed from the peak position shift of theta-two theta scan of X-ray diffraction. As the film thickness increase, the dipole moment decrease and the built-in electric field decrease. The probability of electron-hole recombination become higher as the built-in electric field become smaller; therefore, the efficiency of photovoltaic effect become smaller. The polarization effect played an important role for efficiency of photovoltaic. As the film thickness increase, the resistance has a dramatic increase that dominate the efficiency of photovoltaic more than the polarization effect dominate. The efficiency of photovoltaic do not have straight correlation with film crystallinity, surface roughness, transmittance and leakage current by various measurements under different film thickness.
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Che-WeiLiu and 劉哲維. "Effect of lanthanum and chromium co-doping on the dielectric properties of bismuth ferrite." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/54149721425120860296.

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碩士
國立成功大學
材料科學及工程學系碩博士班
101
BiFeO3(BFO),which is one of the most potential multiferroics ,has high Curie temperature TC(~1123 K) and high Néel temperature TN(~643 K) resulting to the coexistence of ferroelectricity and ferromagnetism at room temperature.This study mainly reported the influence and change by the co-doping of lanthanum and different content of chromium.Bi3+ ions have close size as La3+ ions, and Fe3+ ions have close size as Cr3+ ions, so we hope to improve the ferroelectric properties with the substitution of La3+ ions for Bi3+ ions and Cr3+ ions for Fe3+ ions in the perovskite BiFeO3 structure. Bulks of BiFeO¬3 and BiFeO3 co-doping with La3+ and Cr3+ were prepared by the usual solid state reaction method. X-ray diffraction(XRD), Scanning electron microscopy(SEM), ferroelectric hysteresis measurements, leakage current measurements and dielectric measurement are used for understanding the effect of codoping. We found that second phases appeared when the doping amount of Cr were more than 5%, indicating that there was a limit for Cr doping in BFO.With the XPS analysis,La doping and the increased doping amount of Cr make more Fe ions change from Fe3+ to Fe2+,which resulting to higher conductivity by transfer of electrons between the neighboring Fe2+ and Fe3+ ions. Because of more Fe2+ ions, the conductive mechanism changes from ohmic conduction to space charge limit conduction by fitting the IV curve. The dielectric measurement can find out that the space charge is the main polarization mechanism.
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Yu, Yang. "Surface segregation in strontium doped lanthanum cobalt ferrite: effect of composition, strain and atmospheric carbon dioxide." Thesis, 2016. https://hdl.handle.net/2144/17079.

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Solid oxide fuel cells (SOFCs) convert chemical energy directly into electrical energy, leading to significantly higher conversion efficiencies. The oxygen reduction reaction (ORR) at the cathode is often the rate-controlling step in the electrochemical reactions occurring in the SOFCs. Strontium doped lanthanum cobalt ferrite (LSCF) is a widely used cathode material due to its high electronic and ionic conductivity, and reasonable oxygen surface exchange coefficient. However, LSCF can have long-term stability issues such as surface segregation of Sr during SOFC operation, which can adversely affect the electrochemical performance. Thus, understanding the nature of the Sr surface segregation phenomenon, and how it is affected by the composition of LSCF, strain, and the CO2 in the gas phase at the cathode, are critical. In this research, heteroepitaxial thin films of La1-x SrxCo0.2Fe0.8O3- with various Sr contents (x = 0.4, 0.3, 0.2) were deposited by Pulsed Laser Deposition (PLD) on single crystal NdGaO3, SrTiO3 and GdScO3 substrates, leading to different strains in the films. The extent of Sr segregation at the film surface was quantified using the synchrotron-based total reflection X-ray fluorescence (TXRF) technique, and by Atomic Force Microscopy (AFM). The microstructure and the electronic structure of the Sr-rich phases formed on the surface were investigated by scanning/transmission electron microscopy (S/TEM) and hard X-ray photoelectron spectroscopy (HAXPES), respectively. These studies revealed that the surface phases consisted of SrO covered with a capping layer of SrCO3. The presence of CO2 in the atmosphere was found to enhance the kinetics of Sr surface segregation in LSCF. The extent of Sr segregation was found to be a function of the Sr content in bulk. Lowering the Sr content from 40% to 30% reduced the surface segregation, but further lowering the Sr content to 20% increased the segregation. The strains of LSCF thin films on various substrates were measured using high-resolution X-ray diffraction (HRXRD) and the Sr surface segregation was found to be reduced with compressive strain and enhanced with tensile strain present within the thin films. A model was developed correlating the Sr surface segregation with Sr content and strain effects to explain the experimental results.
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Book chapters on the topic "Lanthanum ferrite"

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Udagani, Chikkappa, H. R. Mahalakshmi, N. Kumar Govind, and J. Keerthiveni. "Green Synthesis and Characterization of Zinc Ferrite and Lanthanum- Doped Zinc Ferrite." In Springer Proceedings in Materials, 221–31. Singapore: Springer Singapore, 2022. http://dx.doi.org/10.1007/978-981-16-7554-6_14.

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Piña, P. C., R. Buentello, H. Arriola, and E. N. Nava. "Mössbauer spectroscopy of lanthanum and holmium ferrites." In ICAME 2007, 853–57. Berlin, Heidelberg: Springer Berlin Heidelberg, 2008. http://dx.doi.org/10.1007/978-3-540-78697-9_117.

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3

Zhang, Xijun, Guoqian Wang, Xin Peng, Sujun Lu, Dalin Chen, Yutian Ma, and Ailiang Chen. "Structural and Magnetic Properties of Rare Earth Lanthanum-Doped Cobalt Ferrites." In The Minerals, Metals & Materials Series, 433–43. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-030-92388-4_39.

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Conference papers on the topic "Lanthanum ferrite"

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Rai, Atma, and Awalendra K. Thakur. "Multifunctionality of nanocrystalline lanthanum ferrite." In INTERNATIONAL CONFERENCE ON CONDENSED MATTER AND APPLIED PHYSICS (ICC 2015): Proceeding of International Conference on Condensed Matter and Applied Physics. Author(s), 2016. http://dx.doi.org/10.1063/1.4946542.

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Gaikwad, Vishwajit M., Pankaj Uikey, and Smita A. Acharya. "Study of multi-functionality of lanthanum ferrite (LaFeO3)." In NANOFORUM 2014. AIP Publishing LLC, 2015. http://dx.doi.org/10.1063/1.4918255.

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Kamran, Muhammad, Yasir Abbas, Tanveer Akhtar, and Muhammad Anis-ur-Rehman. "Electrical Properties of Lanthanum Doped Cobalt Ferrite Nanoparticales." In International Symposium on Advanced Materials. Switzerland: Trans Tech Publications Ltd, 2022. http://dx.doi.org/10.4028/p-5v3687.

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Ferrites materials with Spinel structure have been broadly studied in recent years because of numerous technological applications. Lanthanum substituted Co-ferrites nanoparticles (CoLa0.075Fe1.925O4) were synthesized via chemical co-precipitation method. X-ray Diffraction study revealed that prepared nanoparticales are single-phased spinel ferrites. Lattice constant, crystallite size, theoretical densities were estimated from XRD data. Electrical properties have been investigated with frequency ranging from 20Hz to 3MHz at room temperature. Dielectric constant and dielectric loss factor shows decreasing trend with increasing frequency. Ac conductivity exhibit increasing behavior with increasing frequency. The contribution of grains and intergrain boundaries in conduction process was estimated from impedance study. Nyquist plot shows dominant contribution of grain boundary resistance than the grain resistance in conduction mechanism.
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4

Islam, Md Nurul, Wakako Araki, and Yoshio Arai. "Investigation of ferroelastic mechanical behavior of lanthanum ferrite, LaFeO3." In 8TH BSME INTERNATIONAL CONFERENCE ON THERMAL ENGINEERING. AIP Publishing, 2019. http://dx.doi.org/10.1063/1.5115956.

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5

Kumar, Pawan, Jagdish Chand, Satish Verma, M. Singh, S. K. Tripathi, Keya Dharamvir, Ranjan Kumar, and G. S. S. Saini. "Room Temperature Ferromagnetic Ordering in Lanthanum Substituted Nano-Cobalt Ferrite." In INTERNATIONAL CONFERENCE ON ADVANCES IN CONDENSED AND NANO MATERIALS (ICACNM-2011). AIP, 2011. http://dx.doi.org/10.1063/1.3653685.

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Lassman, Alexander, Alevtina Smirnova, and Nigel Sammes. "An Investigation of Doped Perovskites Based on La, Pr, and Sm Ferrites as Cathode Materials for Solid Oxide Fuel Cells." In ASME 2008 6th International Conference on Fuel Cell Science, Engineering and Technology. ASMEDC, 2008. http://dx.doi.org/10.1115/fuelcell2008-65153.

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Perovskites with the composition ABO3 have been studied as cathode candidate materials for solid oxide fuel cells. Both the A and B sites can be doped. This paper investigates ABO3 perovskites in which the A site ion is lanthanum (La), praseodymium (Pr), or samarium (Sm), doped with strontium (Sr). The B site ion is iron (Fe) doped with cobalt (Co) or nickel (Ni). Powders were prepared by the glycine-nitrate process, and were calcined at temperatures between 700°C and 900°C. XRD analysis was performed to determine the effect of calcination temperature on structure. Cathode pellets were made and sintered at 1200°C for 4 hours. The electrical conductivity of these pellets was measured, in ambient air, at temperatures ranging from 200°C to 800°C. The measured conductivity was generally higher for the ferrite-nickelates than the ferrite-cobaltites. Additionally, the samples with lanthanum as the A site cation demonstrated higher electrical conductivity than those with samarium or praseodymium.
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Naseem, Swaleha, Wasi Khan, B. R. Singh, and A. H. Naqvi. "Room temperature optical and dielectric properties of Sr and Ni doped lanthanum ferrite nanoparticles." In NANOFORUM 2014. AIP Publishing LLC, 2015. http://dx.doi.org/10.1063/1.4917689.

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J, Chandradass, Rengasamy N.V., AMUTHA SURABI M, Ki Hyeon kim, and R. Rajendran. "Preparation and Characterization of Lanthanum Ferrite Nanopowders Using Igepal CO 520 as a Surfactant." In International Conference on Advances in Design, Materials, Manufacturing and Surface Engineering for Mobility. 400 Commonwealth Drive, Warrendale, PA, United States: SAE International, 2022. http://dx.doi.org/10.4271/2022-28-0581.

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Rai, Atma, and Awalendra K. Thakur. "The enhancement in dielectric and magnetic property in Na and Mn co substituted lanthanum ferrite." In INTERNATIONAL CONFERENCE ON CONDENSED MATTER AND APPLIED PHYSICS (ICC 2015): Proceeding of International Conference on Condensed Matter and Applied Physics. Author(s), 2016. http://dx.doi.org/10.1063/1.4946355.

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Tucker, David, Ayyakkannu Manivannan, Dan Haynes, Harry Abernathy, Nick Miller, Karon Wynne, and Angine´s Matos. "Evaluating Methods for Infiltration of LSCF Cathodes With Mixed Electric/Ionic Conductors for Improved Oxygen Exchange." In ASME 2010 8th International Conference on Fuel Cell Science, Engineering and Technology. ASMEDC, 2010. http://dx.doi.org/10.1115/fuelcell2010-33214.

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Infiltration methods for improving lanthanum strontium cobalt ferrite (LSCF) cathode performance through catalyst surface modification were evaluated at the U.S. Department of Energy, National Energy Technology Laboratory. Infiltration of mixed conductors into LSCF cathodes of solid oxide fuel cells promises a low cost method of improving oxygen exchange and performance in these materials at lower temperatures. LSCF cathodes on Nickel-Yttria Stabilized Zirconia (Ni-YSZ) anode supported cells were infiltrated with strontium-doped lanthanum zirconate (LSZ) pyrochlores using two methods. An aqueous solution of nitrate salts was vacuum infiltrated into the cathodes of anode supported button cells, and the cells were heated to form the pyrochlore phase in-situ. This was compared to the efficacy of infiltrating a suspension of pyrochlore nanoparticles. Different dispersants were used to prepare the nanoparticle suspensions at varying concentrations and pH levels, and the results are compared.
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