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Academic literature on the topic 'SrFeO3'

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Published: 4 June 2021
Last updated: 28 January 2023

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Journal articles on the topic "SrFeO3"

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Sim, Jaeyong, Sang-Hyeok Kim, Jin-Yong Kim, Ki Bong Lee, Sung-Chan Nam, and Chan Young Park. "Enhanced Carbon Dioxide Decomposition Using Activated SrFeO3−δ." Catalysts 10, no. 11 (November 3, 2020): 1278. http://dx.doi.org/10.3390/catal10111278.

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Today, climate change caused by global warming has become a worldwide problem with increasing greenhouse gas (GHG) emissions. Carbon capture and storage technologies have been developed to capture carbon dioxide (CO2); however, CO2 storage and utilization technologies are relatively less developed. In this light, we have reported efficient CO2 decomposition results using a nonperovskite metal oxide, SrFeCo0.5Ox, in a continuous-flow system. In this study, we report enhanced efficiency, reliability under isothermal conditions, and catalytic reproducibility through cyclic tests using SrFeO3−δ. This ferrite needs an activation process, and 3.5 vol% H2/N2 was used in this experiment. Activated oxygen-deficient SrFeO3−δ can decompose CO2 into carbon monoxide (CO) and carbon (C). Although SrFeO3−δ is a well-known material in different fields, no studies have reported its use in CO2 decomposition applications. The efficiency of CO2 decomposition using SrFeO3−δ reached ≥90%, and decomposition (≥80%) lasted for approximately 170 min. We also describe isothermal and cyclic experimental data for realizing commercial applications. We expect that these results will contribute to the mitigation of GHG emissions.
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Седых, В. Д., О. Г. Рыбченко, Э. В. Суворов, А. И. Иванов, and В. И. Кулаков. "Кислородные вакансии и валентные состояния железа в соединениях SrFeO-=SUB=-3-delta-=/SUB=-." Физика твердого тела 62, no. 10 (2020): 1698. http://dx.doi.org/10.21883/ftt.2020.10.49924.096.

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The X-ray and Mossbauer studies of the Brownmillerite phase have been carried out in the given work and the well-known literature data on the single phase compounds with a perovskite structure in ferrite strontium SrFeO3-δ have been analyzed. It has been found out that all Fe valence states for any phase composition of ferrite strontium are determined by its local oxygen environment. It allows us to understand the behavior of Fe transition from one valence state to another when adding oxygen vacancies and to explain the Fe structural states in the SrFeO3-δ oxide including single and two-phase compositions. This approach is a more general case for description of the all known compounds and synthesized phase combinations in SrFeO3-δ and the formula considered in literature for the single-phase structures well agrees with it.
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Wang, Dashan, James J. Tunney, Xiaomei Du, Michael L. Post, and Raynald Gauvin. "Transmission electron microscopy investigation of interfacial reactions between SrFeO3 thin films and silicon substrates." Journal of Materials Research 22, no. 1 (January 2007): 76–88. http://dx.doi.org/10.1557/jmr.2007.0005.

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The SrFeO3/SiO2/Si thin film system has been studied using transmission electron microscopy (TEM). The thin films of SrFeO3 were grown by pulsed laser deposition onto silicon substrates with a SiO2 buffer layer at room temperature (RT) and 700 °C and subjected to annealing for various periods of time at temperature T = 700 °C. Transmission electron microscopy characterization showed that the microstructure of the film deposited at room temperature contained crystalline and amorphous layers. Silicon diffusion into SrFeO3 films occurred at the SiO2 interface for the samples deposited at 700 °C and for those films annealed at 700 °C. The silicon diffusion-induced interfacial reactions resulted in the phase transformations and the growth of complex crystalline and amorphous phases. The principal compositions of these phases were Sr(Fe,Si)12O19, SrOx and amorphous [Sr-Fe-O-Si].
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Zhong, Yu-Jie, and Chong-Der Hu. "Spin Waves in SrFeO3." Journal of the Physical Society of Japan 82, no. 1 (January 15, 2013): 014704. http://dx.doi.org/10.7566/jpsj.82.014704.

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Liang, Chong, De An Yang, Jian Jing Song, and Ming Xia Xu. "Oxygen Sensitivity of SrFeO3-δ Thin Films Prepared by Sol-Gel Method." Key Engineering Materials 280-283 (February 2007): 315–18. http://dx.doi.org/10.4028/www.scientific.net/kem.280-283.315.

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Sr(NO3)2, Fe(NO3)3 and citric acid (the mole ratio was 1:1:2) were mixed in water to form sol. Alumina substrate, which had been treated by ultrasonic cleaner, were dipped in the sol and pulled out, and the coating film was heated for 1h at 900oC. Through seventeen times treatment, SrFeO3-d thin film was coated on the alumina substrate. The remainder sol was dried and heated at 400oC, 800oC, 900oC for 2 h. The thin films and the powders were characterized by XRD. The morphologies of thin films were observed by SEM. The results showed that SrFeO3-δ was formed at 900oC on alumina substrate and the grain size was 100 ~ 200 nm. The oxygen sensitivity was measured in the temperature range of 377 ~ 577oC under different oxygen partial pressures. SrFeO3-δ thin film showed p-type conduction. The response time was less than 2 min when being exposed to a change from N2 to 0.466% O2 at 377oC.
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Седых, В. Д., О. Г. Рыбченко, А. Н. Некрасов, И. Е. Конева, and В. И. Кулаков. "Влияние содержания кислорода на локальное окружение атомов Fe в анион-дефицитном SrFeO-=SUB=-3-delta-=/SUB=-." Физика твердого тела 61, no. 6 (2019): 1162. http://dx.doi.org/10.21883/ftt.2019.06.47694.372.

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The structure features of polycrystalline anion-deficient ferrite strontium SrFeO3-δ have been investigated for different oxygen content by Mossbauer spectroscopy, X-ray diffraction analysis and scanning electron microscopy. Three structures with a different composition have been prepared depending on heat treatment conditions. Several non-equivalent Fe positions exist within each structure that correspond to different local oxygen environments the relation and distortion degree of which change depending on oxygen quantity. Based on the Mossbauer data obtained an oxygen content has been estimated for each structure. One more the model intermediate composition Sr16Fe16O45 of the SrFeO3-δ compound is proposed.
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Kleveland, Kjersti, Andrew Wereszczak, Timothy P. Kirkland, Mari-Ann Einarsrud, and Tor Grande. "Compressive Creep Performance of SrFeO3." Journal of the American Ceramic Society 84, no. 8 (December 20, 2004): 1822–26. http://dx.doi.org/10.1111/j.1151-2916.2001.tb00921.x.

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Wu, Chunping, Yiran Zhang, Bang Xiao, Lin Yang, Anqi Jiao, Yinan Wang, Xuteng Zhao, and He Lin. "YSZ-Based Mixed Potential Type Sensors Utilizing Pd-doped SrFeO3 Perovskite Sensing Electrode to Monitor Sulfur Dioxide Emission." Journal of The Electrochemical Society 169, no. 3 (March 1, 2022): 037508. http://dx.doi.org/10.1149/1945-7111/ac593c.

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Sulfur dioxide (SO2) is one of the key pollutants in the atmosphere that should be monitored in many combustion facilities. In this paper, YSZ-based mixed potential SO2 sensors were developed utilizing the perovskite-type SrFeO3 sensing electrode, and Pd doping was applied to enhance the sensing performance. It was found that the sensor utilizing the Pd0.05-SrFeO3 sensing electrode showed the highest sensitivity toward 1–30 ppm SO2 at 575 ° C , and exhibited a piecewise linear relationship between Δ V and the logarithm of SO2 concentrations in this concentration range. The significant enhancement of sensing performances by 5 at% Pd doping was mainly attributed to the increasing of electrochemical catalytic activity of the anodic reaction. After the sensing performance test in the temperature range between 525 ° C –625 ° C , 575 ° C was selected as the optimum operating temperature. The sensing performances of the developed Pd0.05-SrFeO3 sensor were further evaluated at 575 ° C , exhibiting good selectivity to CO, CO2, NO, and NO2 interference and good long-term stability. In addition, the fluctuation of oxygen concentration can be corrected by the Butler-Volmer equation following the mixed potential theory.
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Nguyen, Nhu Pailes, Tyler P. Farr, H. Evan Bush, Andrea Ambrosini, and Peter G. Loutzenhiser. "Air separation via two-step solar thermochemical cycles based on SrFeO3−δ and (Ba,La)0.15Sr0.85FeO3−δ perovskite reduction/oxidation reactions to produce N2: rate limiting mechanism(s) determination." Physical Chemistry Chemical Physics 23, no. 35 (2021): 19280–88. http://dx.doi.org/10.1039/d1cp03303d.

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Gurskii, A. L., N. A. Kalanda, M. V. Yarmolich, I. A. Bobrikov, S. V. Sumnikov, and A. V. Petrov. "PHASE TRANSFORMATIONS DURING CRYSTALLIZATION OF A SOLID SOLUTION OF STRONTIUM-SUBSTITUTED DOUBLE PEROVSKITE." Doklady BGUIR, no. 7-8 (December 29, 2019): 73–80. http://dx.doi.org/10.35596/1729-7648-2019-126-8-73-80.

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The kinetics of phase contents modification in the process of SrBaFeMoO6–δ crystallization from a stoichiometric mixture of SrCO3 + BaCO3 + 0,5Fe2O3 + MoO3 simple oxides using the solid phase method has been investigated. In the temperature region of 300–1200°С, a number of endotermic effects have been detected. Herewith, the first one (with maximum around 552°С) and the third one (with maximum around 743°С) are accompanying by the significant decrease of the mass of specimen. In the temperature range of 946–1200°С, the mass change of specimen is practically not observable, while the thermal effect is still present, and the specimen remains not single-phase one. This indicates the difficulty of the flow of solid phase reactions with the formation of solid solution of barium-strontium ferromolybdate. During analysis of the change of the phase composition consisting of a mixture of initial reagents of stoichiometric relation SrCO3 + BaCO3 + 0,5Fe2O3 + MoO3, it has been observed that with increasing temperature, complex compounds BaMoO4, SrFeO3 appear almost simultaneously, then SrBaFeMoO6–δ appears consequently. Thus, the compounds BaMoO4 и SrFeO3, are structure forming for the solid solution of barium-strontium ferromolybdate. With further temperature increase up to 770°С the formation of new compound ВаFeO3 with disappearing SrFeO3 was detected. In this case, the amount of double perovskite increases faster than that of barium molybdate. The main accompanying compounds at the crystallization of the SrBaFeMoO6–δ double perovskite solid solution are BaMoO4 and SrFeO3. It was established that at the initial stage of the interaction, the resulting solid solution of barium-strontium ferromolybdate is enriched with iron and its composition changes during the reaction in the direction of an increase of the molybdenum content, as in the case of other precursor combinations.
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Dissertations / Theses on the topic "SrFeO3"

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Hernandez, José Luis Valenzuela. "Obtenção e caracterização de filmes de perovskitas do tipo SrFeO3≠” para uso em spintrônica baseada em seleção aumentada de spins." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2018. http://hdl.handle.net/10183/184662.

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Inspirados por resultados que mostram grande capacidade de seleção de spins em sistemas quirais, produzimos, principalmente em forma de filmes, óxidos tipo perovskita SrFeO3− com conhecida estrutura magnética helicoidal. Foi usando método químico a partir de Fe(NO3)3.9H2O, SrCO3 e ácido cítrico como reagentes precursores. Devido à complexidade de produção, a rota de fabricação foi detalhadamente explorada e descrita. Medidas de transporte eletrônico foram feitas aplicando correntes com frequências controladas para excitar o filme depositado. Foram encontrados dois mecanismos de transporte que aparentemente dependem da espessura da amostra, com uma possível transição perto de 700 nm. O mecanismo de transporte para temperaturas acima da transição magnética é mais sensível à frequência e à temperatura. Por outro lado, duas transições atribuídas a fases magnéticas foram encontradas em temperaturas ao redor de 105 K e 135 K. As temperaturas coincidem com as transições correspondentes à transição magnética helicoidal. Mediante o uso dos modelos de Mott e de Polarons pequenos conseguimos determinar duas fases magnéticas separadas por uma transição(crossover) que possivelmente seja antiferromagnética. Conclui-se que filmes da perovskita que apressentam transições correspondentes às reportadas como helicoidais, foram fabricados com sucesso.
Inspired by results that showed great ability of chiral systems to select spins in electronic transport, we produced films of SrFeO3− perovskite-type oxides that present helical magnetic structure. We used a chemical method starting from Fe(NO3)3.9H2O, SrCO3 and citric acid as precursors. Due to the complexity of production, the manufacturing route has been extensively explored and described. Electronic transport measurements were made by applying currents with controlled frequencies to the deposited film. Two transport mechanisms were found. Apparently they depend on the thickness of the sample, with a possible transition near 700 nm. The transport mechanism for temperatures above the magnetic transition is more sensitive to both frequency and temperature. On the other hand, two transitions attributed to magnetic phases were found around the temperatures of 105 K and 135 K. The temperatures coincide with the transitions corresponding to the helical magnetic transition. Through the use of the Mott and small Polarons models we can determine two magnetic phases separated by a transition (crossover) that is possibly antiferromagnetic. It is concluded that films of the perovskite that present transactions corresponding to those reported as helical, were manufactured successfully.
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Maity, Avishek. "Etude des mécanismes de diffusion de l’oxygène dans SrFeO3-x et Pr2NiO4+d, réalisée par diffraction du rayonnement synchrotron in situ sur monocristal." Thesis, Montpellier, 2016. http://www.theses.fr/2016MONTT188/document.

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La compréhension des aspects fondamentaux de la diffusion de l'oxygène dans les oxydes solides à des températures modérées, jusqu'à température ambiante, est un enjeu majeur pour le développement d'une variété de dispositifs technologiques dans un avenir proche. Cela concerne, par exemple, le développement de la prochaine génération des électrolytes et membranes solides d'oxygène pour les piles à combustible de type SOFC. Autrement, les réactions d'intercalation de l'oxygène réalisées à basse température présentent un outil puissant pour contrôler le dopage en oxygène ainsi que des propriétés physiques. Dans ce contexte, les oxydes ayant une structure type brownmillérite (A2BB'O5) ou type K2NiF4, ont attiré beaucoup d'attention, car ils montrent une mobilité de l'oxygène déjà à température ambiante.Dans cette thèse, nous avons étudié les mécanismes d'intercalation d'oxygène dans SrFeO2.5+x, ainsi que Pr2NiO4+x par des méthodes de diffraction in situ, réalisées sur des monocristaux dans une cellule électrochimique spécifiquement conçue, explorant principalement le rayonnement synchrotron. Ceci a permis d’explorer en 3D tout le réseau réciproque, et d'obtenir des informations précieuses sur la diffusion diffuse, sur les faibles intensités des raies de surstructure, ainsi que des informations sur la fraction volumique des différents domaines de maclage au cours de la réaction, impossibles à accéder par diffraction de poudre.Les deux systèmes montrent des changements structuraux complexes, accompagnés par une mise en ordre de l'oxygène à longue portée. Au cours de l'intercalation d'oxygène nous avons mis en évidence deux phases intermédiaires, SrFeO2.75 et SrFeO2.875, possédant des lacunes en oxygène ordonnées à longue échelle. En raison du maclage, avec jusqu'à douze possibles individus, nous avons suivi directement la formation et l'évolution des domaines de maclage ainsi que leur micro-structure apparentée. Nous avons ainsi observé un mécanisme de réaction topotactique pour SrFeO2.5 vers SrFeO2.75, tandis que l'oxydation de SrFeO2.75 conduit à des importants réarrangements de l’oxygène, associés à un changement de nombre de domaines de maclage. La réduction électrochimique de la phase orthorhombique Pr2NiO4.25 donne Pr2NiO4.0 comme produit final, ayant la même symétrie, tandis que la phase tétragonale Pr2NiO~4.12 apparaît comme phase intermédiaire. Utilisant un monocristal avec un diamètre de 50 microns, la réaction se déroule dans des conditions d'équilibre dans moins que 24 heures, ce qui implique un coefficient de diffusion de l’oxygène anormalement élevé, supérieur à 10-^11cm2*s-1 à température ambiante. Nous avons également étudié le diagramme de phase de Pr2NiO4.25 sur monocristal jusqu’à 1100°C en chauffant sous air. Une série complexe de transition de phases a été mise en évidence, la vraie symétrie de Pr2NiO4.25 s’avérée en fait monoclinique.Outre l'exploration des diagrammes de phases complexes de SrFeO2.5+x et Pr2NiO4+d, nous avons pu étudier les changements détaillés concernant la micro-structure à l'aide de diffraction sur monocristaux in situ, impossible à accéder par des méthodes de diffraction de poudre classique. Les changements de la micro-structure des domaines va bien au-delà des composés étudiés ici et porte une grande importance pour extrapoler sur la performance, la stabilité et la durée de vie par exemple des matériaux utilisés pour le stockage de l’énergie
Understanding fundamental aspects of oxygen diffusion in solid oxides at moderate temperatures, down to ambient, is an important issue for the development of a variety of technological devices in the near future. This concerns e.g. the progress and invention of next generation solid oxygen ion electrolytes and oxygen electrodes for solid oxide fuel cells (SOFC) as well as membrane based air separators, oxygen sensors and catalytic converters to transform e.g. NOx or CO from exhaust emissions into N2 and CO2. On the other hand oxygen intercalation reactions carried out at low temperatures present a powerful tool to control hole doping, i.e. the oxygen stoichiometry, in electronically correlated transition metal oxides. In this aspect oxides with Brownmillerite (A2BB’O5) and K2NiF4-type frameworks, have attracted much attention, as they surprisingly show oxygen mobility down to ambient temperature. In this thesis we investigated oxygen intercalation mechanisms in SrFeO2.5+x as well as Pr2NiO4+x by in situ diffraction methods, carried out on single crystals in especially designed electrochemical cell, mainly exploring synchrotron radiation. Following up oxygen intercalation reactions on single crystals is challenging, as it allows to scan the whole reciprocal lattice, enabling to obtain valuable information as diffuse scattering, weak superstructure reflections, as well as information of the volume fraction of different domains during the reaction, to highlight a few examples, difficult or impossible to access by powder diffraction. Both title systems are able to take up an important amount of oxygen on regular and interstitial lattice sites, inducing structural changes accompanied by long range oxygen ordering. For SrFeO2.5+x the uptake of oxygen carried out by electrochemical oxidation yields SrFeO3 as the final reaction product. The as grown SrFeO2.5 single crystals we found to show a complex defect structure, related to the stacking disorder of the octahedral and tetrahedral layers. During the oxygen intercalation we evidenced the formation of two reaction intermediates, SrFeO2.75 and SrFeO2.875, showing complex and instantly formed long range oxygen vacancies. Due to the specific twinning with up to totally twelve possible twin individuals, we directly follow up the formation and changes of the specific domain and related micro-structure. We thus observed a topotactic reaction mechanism from SrFeO2.5 to SrFeO2.75, while further oxidation lead to important rearrangements in the dimensionality of the oxygen defects in SrFeO2.75, implying the formation of an additional twin domain in course of the reaction. The electrochemical reduction of orthorhombic Pr2NiO4.25 yields stoichiometric Pr2NiO4.0 as the final reaction product with the same symmetry, while tetragonal Pr2NiO~4.12 appears as a non-stoichiometric intermediate phase. Using a single crystal with 50µm diameter, the reaction proceeded under equilibrium conditions in slightly less than 24h, implying an unusually high oxygen ion diffusion coefficient of > 10^-11cm2*s-1 at already ambient temperature. From the changes of the associated twin domain structure during the reduction reaction, the formation of macro twin domains was evidenced. Heating up Pr2NiO4.25 single crystals in air revealed a complex series of phase transition, evidencing the true symmetry of the starting phase to be in fact monoclinic. Beside exploring the complex phase diagrams of SrFeO2.5+x and Pr2NiO4+d we were able to investigate detailed changes in the micro-structure using in situ single crystal diffraction techniques, impossible to access by classical powder diffraction methods. The importance of changes in the domain structure goes far beyond the investigated title compounds and has utmost importance of the performance, stability and lifetime of e.g. battery materials
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Schmidt, Marek Wojciech, and Marek Schmidt@rl ac uk. "Phase formation and structural transformation of strontium ferrite SrFeOx." The Australian National University. Research School of Physical Sciences and Engineering, 2001. http://thesis.anu.edu.au./public/adt-ANU20020708.190055.

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Non-stoichiometric strontium iron oxide is described by an abbreviated formula SrFeOx (2.5 ≤ x ≤ 3.0) exhibits a variety of interesting physical and chemical properties over a broad range of temperatures and in different gaseous environments. The oxide contains a mixture of iron in the trivalent and the rare tetravalent state. The material at elevated temperature is a mixed oxygen conductor and it, or its derivatives,can have practical applications in oxygen conducting devices such as pressure driven oxygen generators, partial oxidation reactors in electrodes for solid oxide fuel cells (SOFC). ¶ This thesis examines the behaviour of the material at ambient and elevated temperatures using a broad spectrum of solid state experimental techniques such as: x-ray and neutron powder diffraction,thermogravimetric and calorimetric methods,scanning electron microscopy and Mossbauer spectroscopy. Changes in the oxide were induced using conventional thermal treatment in various atmospheres as well as mechanical energy (ball milling). The first experimental chapter examines the formation of the ferrite from a mixture of reactants.It describes the chemical reactions and phase transitions that lead to the formation of the oxide. Ball milling of the reactants prior to annealing was found to eliminate transient phases from the reaction route and to increase the kinetics of the reaction at lower temperatures. Examination of the thermodynamics of iron oxide (hematite) used for the reactions led to a new route of synthesis of the ferrite frommagnetite and strontium carbonate.This chapter also explores the possibility of synthesis of the material at room temperature using ball milling. ¶ The ferrite strongly interacts with the gas phase so its behaviour was studied under different pressures of oxygen and in carbon dioxide.The changes in ferrite composition have an equilibrium character and depend on temperature and oxygen concentration in the atmosphere. Variations of the oxygen content x were described as a function of temperature and oxygen partial pressure, the results were used to plot an equilibrium composition diagram. The heat of oxidation was also measured as a function of temperature and oxygen partial pressure. ¶ Interaction of the ferrite with carbon dioxide below a critical temperature causes decomposition of the material to strontium carbonate and SrFe12O19 . The critical temperature depends on the partial pressure of CO2 and above the critical temperature the carbonate and SrFe12O19 are converted back into the ferrite.The resulting SrFe12O19 is very resistant towards carbonation and the thermal carbonation reaction does not lead to a complete decomposition of SrFeOx to hematite and strontium carbonate. ¶ The thermally induced oxidation and carbonation reactions cease at room temperature due to sluggish kinetics however,they can be carried out at ambient temperature using ball milling.The reaction routes for these processes are different from the thermal routes.The mechanical oxidation induces two or more concurrent reactions which lead to samples containing two or more phases. The mechanical carbonation on the other hand produces an unknown metastable iron carbonate and leads a complete decomposition of the ferrite to strontiumcarbonate and hematite. ¶ Thermally and mechanically oxidized samples were studied using Mossbauer spectroscopy. The author proposes a new interpretation of the Sr4Fe4O11 (x=2.75) and Sr8Fe8O23 (x=2.875)spectra.The interpretation is based on the chemistry of the compounds and provides a simpler explanation of the observed absorption lines.The Mossbauer results froma range of compositions revealed the roomtemperature phase behaviour of the ferrite also examined using x-ray diffraction. ¶ The high-temperature crystal structure of the ferrite was examined using neutron powder diffraction.The measurements were done at temperatures up to 1273K in argon and air atmospheres.The former atmosphere protects Sr2Fe2O5 (x=2.5) against oxidation and the measurements in air allowed variation of the composition of the oxide in the range 2.56 ≤ x ≤ 2.81. Sr2Fe2O5 is an antiferromagnet and undergoes phase transitions to the paramagnetic state at 692K and from the orthorhombic to the cubic structure around 1140K.The oxidized formof the ferrite also undergoes a transition to the high-temperature cubic form.The author proposes a new structural model for the cubic phase based on a unit cell with the Fm3c symmetry. The new model allows a description of the high-temperature cubic form of the ferrite as a solid solution of the composition end members.The results were used to draw a phase diagramfor the SrFeOx system. ¶ The last chapter summarizes the findings and suggests directions for further research.
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Darracq, Stéphane. "Contribution à l'étude des corrélations entre stoechiométrie, structure, liaison chimique et propriétes physico-chimiques de perovskites oxygénées renfermant un élément 3d a un degrè d'oxydation inusuel (Cu(III), Cu(IV), Fe(IV))." Phd thesis, Université Sciences et Technologies - Bordeaux I, 1993. http://tel.archives-ouvertes.fr/tel-00136172.

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Ce mémoire concerne l'influence d'un degré d'oxydation inusuel d' un element de transition (Cu(III), Cu(IV), Fe(IV)) sur les proprietes physico-chimiques des réseaux oxygènes dérivés de structure perovskite. Les différentes structures du compose du cuivre trivalent LaCuO3 (formes basse et haute pression) ont été étudiées. Le role de plusieurs facteurs sur les propriétés physiques de ce matériau a pu etre mis en évidence, en particulier: 1) l'accroissement de la covalence moyenne de la liaison Cu-O du a la stabilisation de la valence mixte Cu(III)/Cu(IV) obtenue par substitution du Sr au La; 2) la distorsion structurale induite par substitution de l'yttrium au lanthane; 3) la pression d'oxygène de synthèse. La seconde partie de ce travail permet, au travers d' une étude Mössbauer par sonde diamagnétique locale (119Sn), d' expliquer le mécanisme de dismutation du fer tétravalent au sein d'un réseau perovskite AFeO3 (A=Ca, Sr)
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Kleveland, Kjersti. "Preparation, microstructure and mechanical properties of LaCoO₃ and SrFeO₃ based ceramics." Doctoral thesis, Norwegian University of Science and Technology, Department of Chemistry, 2000. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-1931.

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Glenne, Rita. "Preparation and Transport Properties of SrFeO. Based Materials with controlled Microstructure." Doctoral thesis, Norwegian University of Science and Technology, Department of Chemistry, 2001. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-463.

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This work consists of mainly two parts. The first part deals with the sintering behaviour and the microstructural stability of SrFe1-xCrxO3-δ, and the second with transport properties of membranes of the same compositions. The most important experimental tools have been dilatometry and oxygen permeability measurements. Supplementary tools were x-ray diffraction analysis (XRD), scanning electron microscope (SEM) and particle size distribution analysis.

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Thomas, Cyrille Alain. "Dynamics of the storage ring free electron laser : theoretical and experimental study of two SRFELs in Europe." Paris 11, 2003. http://www.theses.fr/2003PA112336.

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L'objectif principal de ce travail est l'étude de la dynamique du laser à électron libres sur anneaux de stockage, dans le domaine spectral UV-VUV et en présence de l'instabilité micro-onde. Cette instabilité affecte tous les anneaux de stockage en fonctionnement pour le laser à électrons libres. Une étude à la fois théorique et expérimentale du comportement de ce système a été mise en place, dans laquelle les résultats théoriques ont été comparés aux mesures effectuées à Super ACO (France) et à ELETTRA (Italie). Dans un premier temps, le comportement du système en présence de l'instabilité micro­onde est décrit qualitativement par un modèle simple. Ensuite, dans le but de prédire de façon quantitative le comportement du faisceau, nous avons développé un code numérique unidimensionel de la dynamique du laser à électrons libres sur anneau de stockage en présence de l'instabilité micro-onde. Le code décrit l'évolution du champ électrique du laser dans la cavité optique, couplée à l'évolution du faisceau d'électrons dans l'anneau, et a été validé par comparaison avec les résultats expérimentaux obtenus à Super ACO et ELETTRA. L'étude expérimentale nous a amené en premier lieu à caractériser le comportement du faisceau dans l'anneau de stockage. Ceci a été effectué seulement à Super ACO. Nous avons mesuré les caractéristiques du faisceau d'électrons (distribution électronique, dispersion en énergie, etc. ) pour le fonctionnement du laser à électrons libres, et nous avons caractérisé deux effets du champs de sillage sur le faisceau d'électrons. Le premier effet, communément appelé la ''distortion du puits de potentiel", modifie les caractériques du faisceau sans générer aucune instabilité. Le deuxième effet du champ de sillage est la génération d'instabilités dans le faisceau d'électron, en particulier l'instabilité micro-onde. Cette instabilité induit en moyenne sur le temps un accroissement de la dispersion en énergie, qui s'accompagne d'un accroissement de la longueur des paquets d'électrons dans l'anneau. Ensuite nous avons caractérisé le comportement du laser, mesuré les caractéristiques de l'impulsion laser sous différentes conditions de désaccord, i. E. Synchronisation entre l'impulsion laser et les paquets d’électrons. Les paramètres du système dynamique, tels que le gain, les pertes de la cavité optique etc. , ont été déduits de ces mesures. La principale conclusion de ce travail est que l'instabilité micro-onde peut sérieusement dégrader les performances du laser à électrons libres sur anneau de stockage. Pour tout projet de construction d'un tel système, l'impédance de l'anneau de stockage, qui régit la puissance de l'instabilité micro-onde, doit être la plus petite possible. Le laser est en compétition avec l'instabilité micro-onde, et est capable de l'amortir dans une plage de courant dont la borne supérieure est déterminée par le gain, les pertes de la cavité optique, et la puissance de l’instabilité. Pour des courants supérieurs, le laser n’est pas stable, ou est tout simplement éteint par l'instabilité. Le code numérique que nous avons développé a été utilisé pour simuler avec succès le comportement de deux lasers à électrons libres. Il peut donc être utilisé comme outil pour l'étude de tout nouveau laser à électrons libres sur anneau de stockage
The purpose of the present work is to study the dynamics of the storage ring free electron laser in the UV-VUV wavelength range and in the presence of the microwave instability. In practice this instability is always present during the operation of a free electron laser in a storage ring, and it may degrade the performance of the laser. In order to investigate the behavior of this complex system, we used a dual approach, in which theoretical results have been compared with measurements performed on two storage ring free electron lasers, at Super ACO (France) and at ELETTRA (Italy). As a first theoretical step, we analyzed a simple model which describes qualitatively the behavior of the storage ring free electron laser only, including the effects due to the microwave instability. In order to get more quantitative predictions, which can not be obtained from the simple model, we developed a 1-dimensional numerical code for the evolution of the laser electric field along the optical cavity axis. The code was validated by the comparison with experimental measurements performed at Super ACO and at ELETTRA. The experimental approach has also been clone in two steps. The first step was to characterize the electron beam behavior in the storage ring without the free electron laser. This has only been clone at Super ACO. We measured the beam characteristics (electron distribution, beam energy spread, etc. ) for the free electron laser operation, and we characterized two effects of the wakefield on the electron beam. The first effect is the so-called potential well distortion, which only modifies the beam properties, leaving the beam stable. The second effect induces instabilities in the beam, in particular the microwave instability, with on average an enhancement of energy spread and a proportional bunch lengthening. Next we characterized the laser behavior, measured the laser pulse properties (pulse duration, average power, etc. ) under detuning conditions, and deduced from measurements the parameters of the dynamical system, such as the gain at start-up, the cavity loss, etc. The main conclusion of the present work is that the microwave instability can seriously degrade the performance of the storage ring free electron laser. For any design of such a system one has to make sure that the impedance of the storage ring, which scales the strength of the microwave instability, is as low as possible. The laser is in competition with the instability, and is able to damp it in a range of current determined by the gain of the free electron laser, the optical cavity Joss and the microwave instability strength. At higher current the laser is unstable, or simply, it may be switched off by the microwave instability. The numerical code we developed has been used to simulate successfully the behavior of two different storage ring free electron lasers. It can be used reliably as a tool for the design of new storage ring free electron lasers
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Rizki, Youssef. "Structure et propriétés physiques d’oxydes de fer à valence mixte SrFe1-x(Sc,Sn)xO3-d." Rouen, 2011. http://www.theses.fr/2011ROUES048.

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Ce travail de thèse porte sur les relations entre structure et propriétés physiques de nouveaux oxydes de métaux de transition à valence mixte de type SrFe1-x(Sc,Sn)xO3-d (M = Sc, Sn). La caractérisation structurale a été effectuée par diffraction X et par microscopie électronique en transmission. La spectrométrie Mössbauer a permis d'accéder aux degrés d'oxydation du fer et à son environnement local. Les propriétés physiques des composés ont été caractérisées par mesures de résistivité avec ou sans champ magnétique appliqué, mesures de susceptibilité magnétique, mesures d'aimantation en fonction du champ magnétique ou de la température. La substitution du fer par un ion trivalent non magnétique tel que le Sc3+ conduit, comme attendu, à une diminution de la teneur en oxygène sans affecter la structure cristalline du composé. Cependant, la substitution est limitée et le composé limite SrFe0,5Sc0,5O2,5 peut être également synthétisé dans une structure chimiquement ordonnée de type brownmillerite. Bien que les propriétés de transport et les propriétés magnétiques soient fortement affectées par une telle substitution, la magnétorésistivité n'est pas significativement modifiée. La substitution du fer par un ion tétravalent tel que le Sn4+ ne permet pas de maintenir constante la teneur en oxygène. Celle-ci augmente avec le taux de substitution. La substitution n'est pas limitée, et un changement de structure est observé pour un taux de substitution supérieur à 0,5 : la structure de la pérovskite n'est plus cubique mais orthothrombique. Toutes les propriétés physiques étudiées (transport, magnétisme, magnétorésistivité) sont significativement influencées par la substitution
In this thesis, the relationship between structure and physical properties of new transition-metal oxides of the SrFe1-x(Sc,Sn)xO3-d (M = Sc, Sn) type has been investigated. The structural characterization was performed by X-ray diffraction and transmission electron microscopy. Mössbauer spectrometry has been used to investigate both the oxidation state of iron and its local environment. The physical properties of the compounds were characterized by resistivity measurements with and without applied magnetic field, magnetic susceptibility measurements, magnetization measurements as a function of magnetic field or temperature. The substitution of iron by a nonmagnetic trivalent ion such as Sc3+ leads to a decrease in the oxygen content without affecting the crystalline structure of the compound. However, the substitution is limited and the SrFe0,5Sc0,5O2,5 limit compound can also be chemically synthesized in a brownmillerite ordered structure. Although transport and magnetic properties are strongly affected by such substitution, magnetoresistivity is not significantly altered. The substitution of iron by a tetravalent ion such as Sn4+ cannot maintain constant oxygen content, which increases with the substitution rate. Substitution is not limited, and a structural change is observed for a substitution rate higher than 0. 5. All the physical properties investigated (transport, magnetism, magnetoresistivity) are significantly influenced by the substitution
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Karim, Abid [Verfasser], and Christine A. [Akademischer Betreuer] Kuntscher. "Electronic correlations in SrFe2-xCoxAs2 pnictides and EuB6 probed by infrared spectroscopy under high-pressure and low-temperatures / Abid Karim. Betreuer: Christine A. Kuntscher." Augsburg : Universität Augsburg, 2014. http://d-nb.info/1077704267/34.

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Wattiaux, Alain. "Etude du comportement électrocatalytique relatif au dégagement de l'oxygène des pérovskites non-stoechiométriques La1-xSrFe1-zCOzO3-y." Phd thesis, Université Sciences et Technologies - Bordeaux I, 1985. http://tel.archives-ouvertes.fr/tel-00574567.

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La mise au point d'une méthodologie : les mesures électrochimiques sur céramiques a été réalisée dans le but d'étudier, de façon qualitative ou quantitative, le comportement électrocatalytique des perovskites non-stoechiométriques de type La1-xSrFe1-zCOzO3-y, vis à vis de la réaction de dégagement de l'oxygène. Un mécanisme réactionnel à cinq étapes élémentaires a été proposé, et les étapes limitantes ont été discutées sur la base de calculs cinétiques et thermodynamiques. On en a déduit des critères d'amélioration des performances électrocatalytiques de ce type de matériaux.
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Book chapters on the topic "SrFeO3"

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Morimoto, S., K. Kuzushita, and S. Nasu. "Mössbauer Study of Ba Doped Cubic Perovskite SrFeO3." In Hyperfine Interactions (C), 177–80. Dordrecht: Springer Netherlands, 2002. http://dx.doi.org/10.1007/978-94-010-0281-3_44.

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Ali, Hassan, Hassan Soleimani, Noorhana Yahya, and Mohammed Falalu Hamza. "Simulation and Experimental Study for Electromagnetic Absorption in Sandstone with SrFeO3 Nanofluid." In Proceedings of the 6th International Conference on Fundamental and Applied Sciences, 393–401. Singapore: Springer Singapore, 2021. http://dx.doi.org/10.1007/978-981-16-4513-6_34.

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Park, Seong-Jin, Hyeongseok Son, Sunghyun Cho, Ki-Sang Hong, and Seungyong Lee. "SRFeat: Single Image Super-Resolution with Feature Discrimination." In Computer Vision – ECCV 2018, 455–71. Cham: Springer International Publishing, 2018. http://dx.doi.org/10.1007/978-3-030-01270-0_27.

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Lugmayr, Andreas, Martin Danelljan, Luc Van Gool, and Radu Timofte. "SRFlow: Learning the Super-Resolution Space with Normalizing Flow." In Computer Vision – ECCV 2020, 715–32. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-58558-7_42.

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Menushenkov, V. P., VS Shubakov, and S. V. Ketov. "Magnetic Properties of Strontium Ferrite Prepared Using Submicron-Sized SrFe12-xAlxO19Powders." In Energy Technology 2012, 275–79. Hoboken, NJ, USA: John Wiley & Sons, Inc., 2012. http://dx.doi.org/10.1002/9781118365038.ch33.

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Liang, Chong, De An Yang, Jian Jing Song, and Ming Xia Xu. "Oxygen Sensitivity of SrFeO3-δ Thin Films Prepared by Sol-Gel Method." In High-Performance Ceramics III, 315–18. Stafa: Trans Tech Publications Ltd., 2007. http://dx.doi.org/10.4028/0-87849-959-8.315.

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Patrakeev, M. V., V. L. Kozhevnikov, I. A. Leonidov, J. A. Bahteeva, and E. B. Mitberg. "Phase Transitions and Ion Transport in SrFe1-XMXO2.5, where M = Ga, Cr." In Mixed Ionic Electronic Conducting Perovskites for Advanced Energy Systems, 163–68. Dordrecht: Springer Netherlands, 2004. http://dx.doi.org/10.1007/978-1-4020-2349-1_13.

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Xu, Zh J., R. Q. Chu, S. C. Cui, and J. S. Zhang. "Synthesis of Mixed Conducting Oxides SrFeCo0.5Oy Powder by Citrate Method." In Key Engineering Materials, 971–73. Stafa: Trans Tech Publications Ltd., 2007. http://dx.doi.org/10.4028/0-87849-410-3.971.

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Xu, Zh J., R. Q. Chu, S. C. Cui, Long Zhi Zhao, and J. S. Zhang. "Change of Microwave Dielectric Loss during the Solid-Reaction Synthesis of SrFeCo0.5Oy." In High-Performance Ceramics V, 183–84. Stafa: Trans Tech Publications Ltd., 2008. http://dx.doi.org/10.4028/0-87849-473-1.183.

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Kobayashi, Tatsuya. "Electronic Phase Diagram and Superconducting Property of $$\text {SrFe}_2\text {(As}_{1-x}\text {P}_x)_2$$." In Study of Electronic Properties of 122 Iron Pnictide Through Structural, Carrier-Doping, and Impurity-Scattering Effects, 19–36. Singapore: Springer Singapore, 2017. http://dx.doi.org/10.1007/978-981-10-4475-5_3.

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Conference papers on the topic "SrFeO3"

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Sendilkumar, A., V. R. Reddy, M. Manivel Raja, P. D. Babu, A. Gupta, and S. Srinath. "Mössbauer effect in tetragonal SrFeO3-δ." In SOLID STATE PHYSICS: Proceedings of the 56th DAE Solid State Physics Symposium 2011. AIP, 2012. http://dx.doi.org/10.1063/1.4710461.

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Okamoto, J. "Magnetic Circular X-ray Dichroism Study of Paramagnetic and Anti-Ferromagnetic States in SrFeO3 Using a 10-T Superconducting Magnet." In SYNCHROTRON RADIATION INSTRUMENTATION: Eighth International Conference on Synchrotron Radiation Instrumentation. AIP, 2004. http://dx.doi.org/10.1063/1.1757993.

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Jaiswal, Shivendra Kumar, and Jitendra Kumar. "Sol-Gel Synthesis and Magnetic, Optical and Impedance Behaviour of Strontium Ferrite Powder." In ASME 2011 International Manufacturing Science and Engineering Conference. ASMEDC, 2011. http://dx.doi.org/10.1115/msec2011-50067.

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An attempt has been made to synthesize SrFeO3-δ powder by sol-gel process involving oxalate formation, its digestion for 4h, drying at 150°C for 24h, and decomposition at 800°C for 10h. The resulting powder is shown to a) exhibit a single phase with a perovskite-type cubic structure and lattice parameter a = 3.862±0.002A˚, b) contain irregular shape particles, and c) display optical absorption peaks corresponding to charge transfer from oxygen to iron (3.73 and 3.41eV), t2g to eg transition of Fe3+ (1.57eV), and crystal field (3d-3d) charge transfer of Fe3+ (1.25eV). Impedance over a wide frequency range of 20Hz-2MHz at 118–318K has contributions from two parallel ‘RC’ circuits belonging to bulk and grain boundaries with the later displaying significant space charge polarization. The relaxation time of polarization follows an Arrhenius behaviour (τ = τo exp[Ea/kBT]) with τo as ∼10−8s and activation energy Ea as ∼50meV. Further, the sample having magnetic character with transition temperature as 853K, coercivity (Hc) = 3748Oe and magnetization 0.09 μB per iron atom (at 17kOe). The zero field cooled and field cooled magnetization versus temperature data in conjunction with constricted hysteresis loops near the origin suggest core-shell morphology for the particles, core being antiferromagnetic with net uncompensated moment and shell conforming to disordered disposition of spins.
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Nguyen, Nhu, T. Farr, Hagan Bush, Andrea Ambrosini, and Peter Loutzenhiser. "Rate limiting mechanism(s) determination of SrFeO3-δand (Ba,La)0.15Sr0.85FeO3-δ perovskite reduction/oxidation reactions for air separation via two-step solar thermochemical cycles." In Proposed for presentation at the SolarPACES 2021 held September 27-October 1, 2021 in Virtual,. US DOE, 2021. http://dx.doi.org/10.2172/1890878.

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Sendilkumar, A., S. Srinath, Dinesh K. Aswal, and Anil K. Debnath. "Magnetization And ESR Study Of SrFeO[sub 3-δ] Systems." In INTERNATIONAL CONFERENCE ON PHYSICS OF EMERGING FUNCTIONAL MATERIALS (PEFM-2010). AIP, 2010. http://dx.doi.org/10.1063/1.3530505.

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Manimuthu, P., D. Paul Joseph, S. Philip Raja, M. Kovendhan, C. Venkateswaran, Alka B. Garg, R. Mittal, and R. Mukhopadhyay. "Investigation of the Less Oxygen Deficient SrFeO[sub 3-δ]." In SOLID STATE PHYSICS, PROCEEDINGS OF THE 55TH DAE SOLID STATE PHYSICS SYMPOSIUM 2010. AIP, 2011. http://dx.doi.org/10.1063/1.3606286.

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Jo, Younghyun, Sejong Yang, and Seon Joo Kim. "SRFlow-DA: Super-Resolution Using Normalizing Flow with Deep Convolutional Block." In 2021 IEEE/CVF Conference on Computer Vision and Pattern Recognition Workshops (CVPRW). IEEE, 2021. http://dx.doi.org/10.1109/cvprw53098.2021.00046.

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Prabhu, E., K. I. Gnanasekar, V. Jayaraman, and T. Gnanasekaran. "Studies on the oxygen sensing characteristics of SrFe1−xTixO3-δ." In 2015 2nd International Symposium on Physics and Technology of Sensors (ISPTS). IEEE, 2015. http://dx.doi.org/10.1109/ispts.2015.7220140.

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Prabhu, E., K. I. Gnanasekar, V. Jayaraman, and T. Gnanasekaran. "Studies on the oxygen sensing characteristics of SrFe1−xTixO3-δ." In 2015 2nd International Symposium on Physics and Technology of Sensors (ISPTS). IEEE, 2015. http://dx.doi.org/10.1109/ispts.2015.7220150.

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Rai, B. K., L. Wang, and S. R. Mishra. "Effect of RE ion valency variation in Tb and Dy doped magnetic SrFe10−xRExO19 hexaferrite." In 2015 IEEE International Magnetics Conference (INTERMAG). IEEE, 2015. http://dx.doi.org/10.1109/intmag.2015.7156604.

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