Bibliografias temáticas / Oxigen vacancy

Literatura científica selecionada sobre o tema "Oxigen vacancy"

Autor: Grafiati

Publicado: 13 de julho de 2024

Crie uma referência precisa em APA, MLA, Chicago, Harvard, e outros estilos

Selecione um tipo de fonte:

Índice

Artigos de revistas
Teses / dissertações
Livros
Capítulos de livros
Trabalhos de conferências
Relatórios de organizações

Consulte a lista de atuais artigos, livros, teses, anais de congressos e outras fontes científicas relevantes para o tema "Oxigen vacancy".

Ao lado de cada fonte na lista de referências, há um botão "Adicionar à bibliografia". Clique e geraremos automaticamente a citação bibliográfica do trabalho escolhido no estilo de citação de que você precisa: APA, MLA, Harvard, Chicago, Vancouver, etc.

Você também pode baixar o texto completo da publicação científica em formato .pdf e ler o resumo do trabalho online se estiver presente nos metadados.

Artigos de revistas sobre o assunto "Oxigen vacancy"

Zhang, Xinping, Fawei Tang, Meng Wang, Wangbin Zhan, Huaxin Hu, Yurong Li, Richard H. Friend e Xiaoyan Song. "Femtosecond visualization of oxygen vacancies in metal oxides". Science Advances 6, n.º 10 (março de 2020): eaax9427. http://dx.doi.org/10.1126/sciadv.aax9427.

Texto completo da fonte

Resumo:

Oxygen vacancies often determine the electronic structure of metal oxides, but existing techniques cannot distinguish the oxygen-vacancy sites in the crystal structure. We report here that time-resolved optical spectroscopy can solve this challenge and determine the spatial locations of oxygen vacancies. Using tungsten oxides as examples, we identified the true oxygen-vacancy sites in WO2.9 and WO2.72, typical derivatives of WO3 and determined their fingerprint optoelectronic features. We find that a metastable band with a three-stage evolution dynamics of the excited states is present in WO2.9 but is absent in WO2.72. By comparison with model bandstructure calculations, this enables determination of the most closely neighbored oxygen-vacancy pairs in the crystal structure of WO2.72, for which two oxygen vacancies are ortho-positioned to a single W atom as a sole configuration among all O─W bonds. These findings verify the existence of preference rules of oxygen vacancies in metal oxides.

Estilos ABNT, Harvard, Vancouver, APA, etc.

Zhang, Bin, Lve Wang, Fan Bai, Peng Xiao, Biao Zhang, Xu Chen, Jie Sun e Wensheng Yang. "High-discharge-voltage lithium-rich layered-oxide cathode materials based on low oxygen vacancy". Dalton Transactions 48, n.º 10 (2019): 3209–13. http://dx.doi.org/10.1039/c9dt00193j.

Texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

Wu, Bao-Zhen, Te Zhu, Xing-Zhong Cao, Zhao-Ming Yang, Kun Zhang, Fu-Jun Gou e Yuan Wang. "Investigation of the Oxidation Behavior of Cr20Mn17Fe18Ta23W22 and Microdefects Evolution Induced by Hydrogen Ions before and after Oxidation". Materials 15, n.º 5 (3 de março de 2022): 1895. http://dx.doi.org/10.3390/ma15051895.

Texto completo da fonte

Resumo:

The oxidation behavior of body-centered cubic (bcc) structure Cr20Mn17Fe18Ta23W22 refractory high-entropy alloy (RHEA) and the microdefects induced by hydrogen ions before and after oxidation were investigated. The results revealed that compared with oxidizing Cr20Mn17Fe18Ta23W22 at 800 °C (6.7 °C/min) for 4 h (ST3, Ar:O2 = 3:1), the heating procedure of oxidizing Cr20Mn17Fe18Ta23W22 at 300 °C (6 °C/min) for 2 h and then increased to 800 °C (5 °C/min) for 4 h is more conducive to the production of oxides without spalling on the surface, i.e., HT1 (Ar:O2 = 1:1), HT2 (Ar:O2 = 2:1) and HT3 (Ar:O2 = 3:1) samples. The oxidation of Cr20Mn17Fe18Ta23W22 RHEA is mainly controlled by the diffusion of cations instead of affinities with O. Additionally, HT1 and HT3 samples irradiated with a fluence of 3.9 × 1022 cm−2 hydrogen ions (60 eV) were found to have a better hydrogen irradiation resistance than Cr20Mn17Fe18Ta23W22 RHEA. The microdefects in irradiated Cr20Mn17Fe18Ta23W22 mainly existed as hydrogen bubbles, hydrogen-vacancy (H-V) complexes and vacancy/vacancy clusters. The microdefects in irradiated HT3 were mainly vacancies and H-V complexes, while the microdefects in irradiated HT1 mainly existed as vacancies and vacancy clusters, as large amounts of hydrogen were consumed to react with oxides on the HT1 surface. The oxides on the surface of the HT3 sample were more stable than those on HT1 under hydrogen irradiation.

Estilos ABNT, Harvard, Vancouver, APA, etc.

Wan, Zhongyu, Quan-De Wang, Dongchang Liu e Jinhu Liang. "Data-driven machine learning model for the prediction of oxygen vacancy formation energy of metal oxide materials". Physical Chemistry Chemical Physics 23, n.º 29 (2021): 15675–84. http://dx.doi.org/10.1039/d1cp02066h.

Texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

Mastrikov, Yuri A., Denis Gryaznov, Guntars Zvejnieks, Maksim N. Sokolov, Māra Putniņa e Eugene A. Kotomin. "Sr Doping and Oxygen Vacancy Formation in La1−xSrxScO3−δ Solid Solutions: Computational Modelling". Crystals 12, n.º 9 (14 de setembro de 2022): 1300. http://dx.doi.org/10.3390/cryst12091300.

Texto completo da fonte

Resumo:

Sr-doped lanthanum scandate La1−xSrxScO3−δ (LSS) is a promising perovskite-type material for electrochemical applications such as proton conductors. Oxygen vacancy is a common defect in ABO3-type perovskites. It controls ion transport as well as proton uptake. The energetic, structural, and electronic properties of oxygen vacancy in LSS are studied deploying the DFT method with meta-GGA functional. The vacancy formation energies in LSS were calculated for various Sr concentrations. Unlike other perovskites, in this material, the electrons are trapped at the oxygen vacancy site (the F-type centres, common in ionic oxides like MgO and Al2O3) rather than localised on the nearest to the vacancy B-cations. The process of oxygen vacancy formation is considered relative to Sr concentration x and oxygen nonstoichiometry factor δ. Three primary regimes are discussed: (I) localized at the vacancy electrons, x/δ < 2, (II) electron charge balanced system, x/δ = 2, and (III) delocalized electron holes, x/δ > 2. For x/δ ≥ 2 oxygen vacancy formation energy reaches the saturation level of ~3.5 eV, which is potentially beneficial for the proton uptake.

Estilos ABNT, Harvard, Vancouver, APA, etc.

Warren, William L., Karel Vanheusden, Duane Dimos, Gordon E. Pike e Bruce A. Tuttle. "Oxygen Vacancy Motion in Perovskite Oxides". Journal of the American Ceramic Society 79, n.º 2 (fevereiro de 1996): 536–38. http://dx.doi.org/10.1111/j.1151-2916.1996.tb08162.x.

Texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

Hinuma, Yoyo, Shinya Mine, Takashi Toyao, Takashi Kamachi e Ken-ichi Shimizu. "Factors determining surface oxygen vacancy formation energy in ternary spinel structure oxides with zinc". Physical Chemistry Chemical Physics 23, n.º 41 (2021): 23768–77. http://dx.doi.org/10.1039/d1cp03657b.

Texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

Peng, Yin-Hui, Chang-Chun He, Yu-Jun Zhao e Xiao-Bao Yang. "Multi-peak emission of In₂O₃ induced by oxygen vacancy aggregation". Journal of Applied Physics 133, n.º 7 (21 de fevereiro de 2023): 075702. http://dx.doi.org/10.1063/5.0135162.

Texto completo da fonte

Resumo:

Oxygen vacancy is crucial to the optical properties in In[Formula: see text]O[Formula: see text], however, the single oxygen vacancy model fails to explain the observed multi-peak emission in the experiment. Herein, we have theoretically investigated the diversity of oxygen vacancy distribution, revealing the relationship between the defect configurations and the optical properties. Combining the first-principles calculations and bayesian regularized artificial neural networks, we demonstrate that the structural stability can be remarkably enhanced by multi-oxygen vacancy aggregation, which will evolve with the defect concentration and temperature. Notably, our results indicate that the single oxygen vacancy will induce the emission peaks centered at 1.35 eV, while multi-peak emission near 2.35 eV will be attributed to the distribution of aggregated double oxygen vacancies. Our findings provide a comprehensive understanding of multi-peak emission observed in In[Formula: see text]O[Formula: see text], and the rules of the vacancy distribution may be extended for other metal oxides to modulate the optical properties in practice.

Estilos ABNT, Harvard, Vancouver, APA, etc.

Zhang, Sufen, Jianni Liu, Xiaoyang Dong, Xiaoxia Jia, Ziwei Gao e Quan Gu. "Controllable construction of oxygen vacancies by anaerobic catalytic combustion of dichloromethane over metal oxides for enhanced solar-to-hydrogen conversion". Sustainable Energy & Fuels 3, n.º 10 (2019): 2742–52. http://dx.doi.org/10.1039/c9se00464e.

Texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

Su, Hai-Yan, Xiufang Ma, Keju Sun, Chenghua Sun, Yongjun Xu e Federico Calle-Vallejo. "Trends in C–O and N–O bond scission on rutile oxides described using oxygen vacancy formation energies". Chemical Science 11, n.º 16 (2020): 4119–24. http://dx.doi.org/10.1039/d0sc00534g.

Texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

Mais fontes

Teses / dissertações sobre o assunto "Oxigen vacancy"

Luo, Kun. "Cation ordered and anion-vacancy ordered perovskite materials". Thesis, University of Oxford, 2013. http://ora.ox.ac.uk/objects/uuid:f36a3f97-70b1-4ab6-819b-d400341a4558.

Texto completo da fonte

Resumo:

The investigation in this thesis focuses on the synthesis of cation-ordered perovskite phases by introducing anion vacancies into the structure. Complex cation-ordered phases Ba2YMO5 and Ba3YM2O7.5 (M = Fe, Co) have been synthesized using ceramic or citrate gel methods under flowing argon. Close inspection reveals that the structures are constructed from Y2M2O102 basic units which consist of two YO6 octahedra and two MO4 tetrahedra in a rock-salt type arrangement. In the structure of Ba2YMO5 (M = Fe, Co), the neighbouring Y2M2O102 units are connected with an equivalent one in the yz-plane with YO6 octahedra sharing an apex. In the structure of Ba3YM2O7.5 (M = Fe, Co), the basic units are connected to each other by the M2O7 dimers via a chain of Y – O – M – O – M – O – Y bonds. Complex cation ordering can be achieved by carefully controlling the anion vacancies and selecting the cations with different ionic radii. The anion vacancies present in Ba2YMO5 (M = Fe, Co) (space group P21/n) allow the intercalation of anions like O2- and F- into the lattice. The fluorination of Ba2YCoO5 leads to the formation of a new orthorhombic phase Ba2YCoO5F0.42 (space group Pbnm) in which the inserted fluoride ions are distributed in a disordered manner. In contrast, the topochemical oxidation of Ba2YFeO5 leads to the formation of a new orthorhombic phase Ba2YFeO5.5 (space group Pb21m), in which Fe4+ centres are located in 4-coordinate tetrahedral sites and 5-coordinate pyramidal sites, respectively. The polar structure of Ba2YFeO5.5 is confirmed by the observation of second-harmonic generation activity and pyroelectric behaviour. Ba2YFeO5.5 also exhibits a combination of ferromagnetic and antiferromagnetic behaviours at low temperature. LaCa2Fe2GaO8 adopts a six-layer structure consisting of an OOTLOOTR stacking sequence of layers of (Fe/Ga)O6 octahedra (O) and (Fe/Ga)O4 tetrahedra (T), related to that of the four-layer brownmillerite structure (space group Pbma). The chains of tetrahedra in the structure of LaCa2Fe2GaO8 exhibit a cooperative twisting distortion in which the twisting direction of the chains of tetrahedra alternates in adjacent tetrahedral layers. LaxSr2-xCoGaO5+δ (0.5 < x < 1) adopts brownmillerite structures which consist of octahedral and tetrahedral layers with mixed valence of Co2+/Co3+. The members with x = 0.5, 0.6 and 0.7 adopt structures with I2mb space group symmetry, in which all the tetrahedra twist in the same direction. The members with x = 0.8, 0.9 and 1.0 adopt structures with Imma space group symmetry, in which the chains of the tetrahedra twist in a disordered manner. A change in the Co3+ spin state from high spin (HS) to low spin (LS) is observed as the La/Sr ratio increases. The change of the Co3+ spin state can be rationalized on the basis of internal chemical pressure.

Estilos ABNT, Harvard, Vancouver, APA, etc.

THANNEERU, RANJITH. "VACANCY ENGINEERED DOPED AND UNDOPED NANOCRYSTALLINE RARE EARTH OXIDE PARTICLES FOR HIGH TEMPERATURE OXIDATION RESISTANT COATING". Master's thesis, University of Central Florida, 2007. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/3986.

Texto completo da fonte

Resumo:

Rare earth oxides with trivalent lattice dopants have been of great interest to researchers in the recent years due to its potential applications in catalysis and high temperature protective coatings. The ability to store oxygen in rare earths is the basis for catalysis because of the ability to change valence states which causes the presence of intrinsic oxygen vacancies in the crystal lattice. Although, several doped-rare earth oxide systems in micron scale have been investigated, the doping effect in cerium oxide nanoparticles with well characterized particle size has not been studied. The doping of ceria at that small size can be very beneficial to further improve its catalytic properties and alter the high temperature phases in alloy systems. Cost effective room temperature chemical methods are used in the current work to synthesize uniformly distributed undoped and doped (dopants: La, Nd, Sm, Gd, Y and Yb) rare earth oxide nanoparticles. In the present study, the variation of the properties in nanocrystalline ceria (NC) synthesized by microemulsion method is studied as a function of dopant size and its concentration. To further understand, the role of dopant (cation) size on the oxygen vacancy concentration, doped nanocrystalline oxide powders were analyzed by Raman Spectroscopy, X-ray Diffraction (XRD) and X-ray Photoelectron Spectroscopy (XPS). XRD studies showed that lattice parameter change in nanocrystalline oxide by doping trivalent rare earth elements is largely depending on size of trivalent ions. It showed that by doping larger cations (Gd3+ and Y3+) compare to Ce3+ causes lattice expansion where as smaller cations (Yb3+) leads to lattice contraction. It also showed that the lattice expansion or contraction is directly proportional to dopant concentration. The results of Raman Spectroscopy showed that the correlation length decreases resulting in increase in oxygen vacancies for larger trivalent dopants (Sm3+, Gd3+ and Y3+). However, the correlation length increases resulting in decrease in oxygen vacancies for smaller trivalent dopants (Yb3+) compare to nanocrystalline ceria. These nanostructured oxides are further applied to develop high temperature oxidation resistance coatings for austenitic steels. The present study investigates the role of oxygen vacancies in the performance of high temperature oxidation resistance as a function of various trivalent dopants and dopant concentration. NC and La3+ doped nanocrystalline ceria (LDN) particles were coated on AISI 304 stainless steels (SS) and exposed to 1243K in dry air for longer duration and subjected to cycling. The results are further compared with that of micro-ceria (MC) coatings. The coated samples showed 90% improvement in oxidation resistance compared to uncoated and MC coated steels as seen from the SEM cross-sectional studies. XRD analysis showed the presence of chromia in both NC and 20 LDN samples which is absent in uncoated steels. From SIMS depth profiles, Fe, Ni depletion zones are observed in presence of LDN coated sample indicating diffusion through the oxide layer. The role of oxygen vacancies in the nanoceria coatings on the early formation of protective chromia layer is discussed and compared to its micron counterpart. This study helps in understanding the role of oxygen vacancies to protect austenitic stainless steel at high temperature and confirms the oxygen inward diffusion rather cation outward diffusion in rare earth oxide coatings. It also gives an idea to identify the type of dopant and its concentration in nanocrystalline cerium oxide which supplies the critical oxygen partial pressure required at high temperature to form primarily impervious chromia layer.
M.S.M.S.E.
Department of Mechanical, Materials and Aerospace Engineering;
Engineering and Computer Science
Materials Science & Engr MSMSE

Estilos ABNT, Harvard, Vancouver, APA, etc.

Iwata, Tatsuya. "Study on Resistive Switching Phenomenon in Metal Oxides for Nonvolatile Memory". 京都大学 (Kyoto University), 2014. http://hdl.handle.net/2433/188598.

Texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

Nishi, Yusuke. "Nonpolar Resistive Switching Based on Quantized Conductance in Transition Metal Oxides". Kyoto University, 2019. http://hdl.handle.net/2433/242544.

Texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

Maiti, Debtanu. "Defect Laden Metal Oxides and Oxynitrides for Sustainable Low Temperature Carbon Dioxide Conversion to Fuel Feedstocks". Scholar Commons, 2018. https://scholarcommons.usf.edu/etd/7694.

Texto completo da fonte

Resumo:

The current energy and environmental scenario in the world demands acute attention on sustainable repurposing of waste CO2 to high value hydrocarbons that not only addresses the CO2 mitigation problem, but also provides pathways for a closed loop synthetic carbon cycle. Difference in the scales of global CO2 emissions (about 40 Gtpa, 2017) and the carbon capture and sequestration (CCS) facilities (estimated cumulative 40 Mtpa, 2018) provokes active research on this topic. Solar thermochemical (STC) and visible light photocatalysis are two of the most promising routes that have garnered attention for this purpose. While STC has the advantages of high CO2 conversion rates, it operates at high temperatures (more than 1000 °C) limiting its industrial implementation. Photocatalysis, on the contrary, is plagued by the poor quantum efficiency and conversion rates, although its exhibits the benefits of low temperature operation. Thus, any significant progress towards low temperature STC and visible light photocatalytic CO2 reduction is a giant leap towards a greener and sustainable energy solution. This dissertation is an effort towards improving both the STC and photocatalytic CO2 reduction. Reverse water gas shift - chemical looping (RWGS-CL) is a modified STC approach that has the potential for low temperature CO2 conversion. RWGS-CL process uses mixed metal oxides like perovskite oxides (ABO3) for the conversion to CO, a potential feedstock for subsequent hydrocarbon production. Generation of oxygen vacancy defects on these perovskite oxides is a key step of RWGS-CL and thus, oxygen vacancy formation energy has been found to be a key descriptor for this process. Using density functional theory based calculations, this intrinsic material property has been used towards rational design of better catalysts. Highest rate of CO2 conversion at the low temperatures of 450 °C was demonstrated by earth abundant perovskite oxide via RWGS-CL. This low temperature and stable CO2 conversion process enables thermal integration with subsequent Fischer Tropsch processes for the hydrogenation of CO to hydrocarbons. Parallel to the developments on materials discovery, another crucial parameter that deserves attention is the surface termination effects of the perovskite oxides. Hence, the site specificity of the bulk and surface oxygen vacancies have been probed in detail towards elucidating the CO2 conversion performance over these materials. In the view of recent progress on the growth of selective crystal facets and terminations, this study opens new avenues for enhanced CO2 conversion performance not only through bulk composition variation, but also via exposing desired crystal facets. Type-II semiconductor heterojunctions (staggered type) are promising candidates for efficient photocatalytic reactions, not only because of their capabilities of electronic density of states tuning, but also their ability to segregate the excited electrons and holes into different materials thereby restricting exciton recombination. Metal oxynitride heterojunctions have recently demonstrated promising activity on visible light water splitting. Elucidating the structure-function relationships for these materials can pave the way towards designing better CO2 conversion photocatalysts. This dissertation focuses on unravelling the roles of material composition, anion vacancy defects and lattice strain towards modulating the electronic density of states of lateral and vertical heterojunctions of (ZnO)X(AlN)1-X and (ZnO)X(GaN)1-X. The heterojunctions consist of periodic potential wells that allows for restricting interlayer charge transport. Increased ZnO concentration was explicitly shown to decrease the band gap due to N 2p and Zn-3d repulsion. Biaxial and vertical compressive strain effected increased band gap while tensile strain reduced the same. Oxygen vacancies was found to have different effect on the electronic state of the materials. When present in charged state (+2), it promotes mid gap state formation, while in neutral state it revealed increased electronic densities near the valence band and conduction band edges. These fundamental site specific material property tuning insights are essential for designing better photocatalysts for future.

Estilos ABNT, Harvard, Vancouver, APA, etc.

Peng, Yung-Kang. "Surface mapping of faceted metal oxides by chemical probe-assisted NMR for catalytic applications". Thesis, University of Oxford, 2017. https://ora.ox.ac.uk/objects/uuid:7b56021f-71fb-437b-8c6b-0569705ef68e.

Texto completo da fonte

Resumo:

Semiconductive metal oxides are of great importance in environmental remediation and electronics because of their ability to generate charge carriers when excited with appropriate energy. The electronic structure, light absorption and charge transport properties have made the transition metal oxides an attractive material as photocatalyst. Recently, facet-engineering by morphology control has been intensively studied as an efficient approach to further enhance their photocatalytic performance. However, various processing steps and post-treatments used in the preparation of facet-engineered particles may generate different surface active sites which may affect their photocatalysis. Moreover, many traditional techniques (PL, EPR and XPS) used for materials characterization (oxygen vacancy, hydroxyl group, cation, etc.) are not truly surface specific but analyzing a range from surface few layers to bulk. Accordingly, they can only provide very limited information on chemical states of the surface active features and their distribution among facets, causing difficulties to unambiguously correlate facet-dependent results with activity. As a result, this often leads to different interpretations amongst researchers during the past decades. As the publications of titanium and zinc ranked top two among studies of first row of transition oxides in the past decades, this thesis will firstly review on the disagreements generated among researchers when they correlated the performance of ZnO and TiO₂ with their facet activities based on traditional techniques. As there are shortcomings of these techniques in producing truly facet-dependent features, some results can be misleading and with no cross-literature comparison. To address these issues, we have developed a new technique "probe-molecule-assisted NMR" which allows a genuine differentiation of surface active sites from various facets. This surface-fingerprint technique has been demonstrated to provide both qualitative (chemical shift) and quantitative (peak intensity) information on the concentration and distribution of truly surface features among facets. In light of the new technique, this thesis will revisit the facet-dependent photocatalytic properties and shed light on these issues.

Estilos ABNT, Harvard, Vancouver, APA, etc.

Shojaee, Kambiz. "Fundamental aspects of ammonia oxidation on cobalt oxide catalysts". Thesis, The University of Sydney, 2014. http://hdl.handle.net/2123/13657.

Texto completo da fonte

Resumo:

The current thesis deals with the ammonia oxidation on cobalt oxide catalyst at the molecular level. The catalytic oxidation of ammonia to NO is crucial in the industrial process of nitric acid production. Cobalt oxide catalysts are being used together with platinum gauzes to reduce the production cost and emission of greenhouse gas N2O. However, the fundamentals of ammonia oxidation on cobalt oxides are not known. This thesis aims to provide insights into our fundamental understanding of ammonia oxidation on Co3O4 surfaces. The performance of cobalt oxide catalysts in the oxidation of NH3 strongly depends upon the exposed surface terminations. Results indicate that different surfaces of Co3O4 behave markedly differently in oxidative reactions due to the difference in binding energy and O recombination energies and oxygen vacancy formation. Overall, NH3 oxidation follows stepwise dehydrogenative route (NH3* → NH2* → NH* → N*) on Co3O4 surfaces. Desorption of lattice products results in the formation of O vacancy sites opening the way for a Mars-van Krevelen mechanism. The successive dehydrogenation of ammonia preferably occurs on the surfaces exposing active lattice O sites. Removal of active lattice O sites from the Co3O4 surfaces in the form of products results in the surface reduction. If the rate of reduction is faster than that of re-oxidation, a CoO-like phase might form. The formation of CoO in Co3O4 catalysts during NH3 oxidation not only reduces the NH3 conversion but also alters the selectivity towards N2 rather than NO due to weak ability of lattice O at the CoO surface to assist the hydrogen abstraction process. A surface with a lower oxygen vacancy formation energy and a higher binding energy of hydrogen exhibits a higher activity towards ammonia oxidation to NO.

Estilos ABNT, Harvard, Vancouver, APA, etc.

Stokes, Stephen J. "Atomistic modelling studies of fluorite- and perovskite-based oxide materials". Thesis, University of Bath, 2010. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.527142.

Texto completo da fonte

Resumo:

Fast oxide-ion and proton conductors are the subject of considerable research due to their technological applications in sensors, ceramic membranes and solid oxide fuel cells (SOFCs). This thesis describes the use of computer modelling techniques to study point defects, dopants and clustering effects in fluorite-and perovskitetype ion conductors with potential SOFC applications. Bi2O3 related phases are being developed with the objective of high oxide-ion conductivities at lower operating temperatures than 1000°C, as in current generation SOFC electrolytes. Doped Bi2O3 phases have shown promise as materials capable of accomplishing this goal. First, the Y-doped phase, Bi3YO6, has been investigated including the ordering of intrinsic vacancies. The defect and dopant characteristics of Bi3YO6 have been examined and show that a highly mobile oxygen sub-lattice exists in this material. A preliminary structural modelling study of a new Re-doped Bi2O3 phase was also undertaken. A comprehensive investigation of the proton-conducting perovskites BaZrO3, BaPrO3 and BaThO3 is then presented. Our results suggest that intrinsic atomic disorder in BaZrO3 and BaThO3 is unlikely, but reduction of Pr4+ in BaPrO3 is favourable. The water incorporation energy is found to be less exothermic for BaZrO3 than for BaPrO3 and BaThO3, but in all cases the results suggest that the proton concentration would decrease with increasing temperature, in accord with experimental data. The high binding energies for all the dopant-OH pair clusters in BaPrO3 and BaThO3 suggest strong proton trapping effects. Finally, a study of multiferroic BiFeO3 is presented, in which the defect, dopant and migration properties of this highly topical phase are investigated. The reduction process involving the formation of oxygen vacancies and Fe2+ is the most favourable redox process. In addition, the results suggest that oxide-ion migration is anisotropic within this system.

Estilos ABNT, Harvard, Vancouver, APA, etc.

Umeda, Yuji. "Rational design of dielectric oxide materials through first-principles calculations and machine-learning technique". Doctoral thesis, Kyoto University, 2020. http://hdl.handle.net/2433/245844.

Texto completo da fonte

Resumo:

京都大学
0048
新制・課程博士
博士(工学)
甲第22159号
工博第4663号
新制||工||1727(附属図書館)
京都大学大学院工学研究科材料工学専攻
(主査)教授田中功, 教授中村裕之, 教授邑瀬邦明
学位規則第4条第1項該当
Doctor of Philosophy (Engineering)
Kyoto University
DFAM

Estilos ABNT, Harvard, Vancouver, APA, etc.

Agarwal, Sahil. "Defect Studies In Metals, Alloys, and Oxides By Positron Annihilation Spectroscopy and Related Techniques". Bowling Green State University / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1626713209028374.

Texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

Mais fontes

Livros sobre o assunto "Oxigen vacancy"

Karapetrova, Euguenia. Factors influencing the crystallization, phase and oxygen vacancy concentration in zirconia. 1997.

Encontre o texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

Capítulos de livros sobre o assunto "Oxigen vacancy"

Browning, N. D., R. F. Klie e Y. Lei. "Vacancy Segregation at Grain Boundaries in Ceramic Oxides". In Mixed Ionic Electronic Conducting Perovskites for Advanced Energy Systems, 15–25. Dordrecht: Springer Netherlands, 2004. http://dx.doi.org/10.1007/978-1-4020-2349-1_2.

Texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

Pacchioni, Gianfranco. "Numerical Simulations of Defective Structures: The Nature of Oxygen Vacancy in Non-reducible (MgO, SiO2, ZrO2) and Reducible (TiO2, NiO, WO3) Oxides". In Defects at Oxide Surfaces, 1–28. Cham: Springer International Publishing, 2015. http://dx.doi.org/10.1007/978-3-319-14367-5_1.

Texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

HENDERSON, T. M., J. C. GREER, G. BERSUKER, A. KORKIN e R. J. BARTLETT. "EFFECT OF CHEMICAL ENVIRONMENT AND STRAIN ON OXYGEN VACANCY FORMATION ENERGIES AT SILICONSILICON OXIDE INTERFACES". In Defects in High-k Gate Dielectric Stacks, 373–83. Dordrecht: Springer Netherlands, 2006. http://dx.doi.org/10.1007/1-4020-4367-8_30.

Texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

Ayyakannu Sundaram, Ganeshraja, Rajkumar Kanniah e Vaithinathan Karthikeyan. "Tuning the Magnetic and Photocatalytic Properties of Wide Bandgap Metal Oxide Semiconductors for Environmental Remediation". In Updates on Titanium Dioxide. IntechOpen, 2023. http://dx.doi.org/10.5772/intechopen.110422.

Texto completo da fonte

Resumo:

The review focuses on recent developments towards preparing room temperature ferromagnetic metal oxide semiconductors for better photocatalytic performance. Here we reported the combined study of photocatalytic and ferromagnetic properties at room temperature on metal oxides, particularly TiO2, which is rapidly an emerging field in the development of magnetism and environmental remediation. Even after decades of research in this area, the exact mechanism of the combination of ferromagnetism and photocatalysis in these materials has been not understood completely. However, some of the critical factors were hinted about the contribution to magnetism. Many reports demonstrated that oxygen vacancy and various metal doping plays a primary role in the room temperature ferromagnetism and photocatalysis in wide-band-gap metal oxides. However, it is not easy to understand the direct correlation between magnetism, oxygen vacancies, dopant concentration, and photocatalysis. This review primarily aims to encompass the recent progress of metal oxide for understanding magnetism and photocatalyst under visible light.

Estilos ABNT, Harvard, Vancouver, APA, etc.

Khan, Hasmat, Atanu Naskar e Susanta Bera. "Vacancy and defect structures in metal oxides". In Metal Oxide Defects, 61–81. Elsevier, 2023. http://dx.doi.org/10.1016/b978-0-323-85588-4.00007-6.

Texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

Dhaka, Kapil, e Maytal Caspary Toroker. "Vacancy formation in 2D and 3D oxides". In 2D Nanomaterials for Energy Applications, 149–72. Elsevier, 2020. http://dx.doi.org/10.1016/b978-0-12-816723-6.00006-x.

Texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

W. Wambu, Enos. "The Graphene Surface Chemistry and Adsorption Science". In Graphene - Chemistry and Applications [Working Title]. IntechOpen, 2024. http://dx.doi.org/10.5772/intechopen.114281.

Texto completo da fonte

Resumo:

Graphene (G) has attracted immense attention due to its exceptional physicochemical and electronic properties, and quite a large amount of literature has accumulated on this subject over the last few decades. The current work, based on a systematic review of the relevant literature, was designed to provide an overview of G surface chemistry with respect to its adsorption science. The aim was to improve knowledge of the graphene surface chemistry while informing new strategies for designing and implementing new G materials for emerging applications. The key G surface reactions include: molecular adsorption of gases, bandgap tuning, gas detection tests; alkali metal storage for battery technology; G vacancy engineering; environmental amelioration of pollutants; and sensors and biosensors technology. GO (graphene oxide) or G has been surface-modified using nonmetals, metals, metal oxides, or organics. In general, GO and related functionalized materials have high affinity and adsorption efficacy for ionic adsorbates, whereas pristine G, and reduced graphene oxide (rGO), exhibits enhanced hydrophobic surfaces with propensity to strong π-π interactions. The metals’ adsorption and doping can impart G magnetic and metallic character, whereas molecular intercalations tend to induce a G bandgap for nano-electronic and nanophotonic uses among other interactions.

Estilos ABNT, Harvard, Vancouver, APA, etc.

Michejevs Padilha, Antonio Claudio, Alexandre Reily Rocha e Gustavo Martini Dalpian. "Ordered vacancy compounds: the case of the Mangéli phases of TiO2". In Metal Oxide Defects, 533–65. Elsevier, 2023. http://dx.doi.org/10.1016/b978-0-323-85588-4.00014-3.

Texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

Broomhead, William Thomas, e Ya-Huei (Cathy) Chin. "Connection of thermodynamics and kinetics in oxidation reactions catalyzed by transition metals and oxides". In Catalysis, 69–105. Royal Society of Chemistry, 2024. http://dx.doi.org/10.1039/bk9781837672035-00069.

Texto completo da fonte

Resumo:

This chapter examines the oxidation reactions of alcohols and alkanes on transition metal or metal oxide surfaces. The diverse sets of reactions, including oxidative dehydrogenation, partial oxidation, reforming, and combustion, occur over temperature and oxygen chemical potential ranges spanned over many orders of magnitude, but they share similar active site requirements and mechanistic events—the oxygen chemical potentials dictate the thermodynamically stable states of the surfaces and type of reactive oxygen, on which catalytic turnovers occur via the general cycles of reductant and oxidant activation, kinetically coupled together. The chapter begins with an exploration on the thermodynamics of a bulk metal–O2 system and its application as a first approximation on the oxide phase and oxygen storage capacity, as well as the driving force in oxide redox reactions, the latter being graphically captured in an Ellingham diagram. Aside from bulk properties, the thermochemical properties of individual lattice oxygen atoms in dispersed metal oxides, such as their vacancy formation enthalpies, are expected to depend on their local coordination sphere. Through case studies, the chapter explores the general mechanistic trends, especially how the thermochemical properties of the reactive oxygen atoms, either as chemisorbed oxygen or lattice oxygen, mediate the catalytic conversion of alcohols and alkanes, through altering the active site structures and/or the character and activation free energy of the kinetically relevant C–H bond scission transition states.

Estilos ABNT, Harvard, Vancouver, APA, etc.

Sonigara, Keval K., Jayraj V. Vaghasiya e Saurabh S. Soni. "Metal oxides as photoanodes for photoelectrochemical water splitting: synergy of oxygen vacancy". In Advances in Metal Oxides and Their Composites for Emerging Applications, 99–134. Elsevier, 2022. http://dx.doi.org/10.1016/b978-0-323-85705-5.00017-8.

Texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

Trabalhos de conferências sobre o assunto "Oxigen vacancy"

Resnick, Alex, Katherine Mitchell, Jungkyu Park, Hannah Maier, Eduardo B. Farfán, Tien Yee e Christian Velasquez. "Thermal Transport in Defective Actinide Oxides". In ASME 2018 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/imece2018-87605.

Texto completo da fonte

Resumo:

The present study employs a molecular dynamics simulation to explore thermal transport in various oxide nuclear fuels with defects such as uranium oxide and plutonium oxide. In particular, the effect of vacancy and substitutional defects on the thermal transport in actinide oxides are investigated. It is found that the thermal conductivities of these oxide nuclear fuels are significantly reduced by the presence of vacancy defects. In spite of their small size, oxygen vacancy is shown to alter the thermal conductivity of oxide fuels greatly; 0.1% oxygen vacancy reduces the thermal conductivity of plutonium dioxide by more than 10% when the number of unit cell in length is 100. It was shown that the missing of larger atoms alters the thermal conductivity of actinide oxides more significantly. For the case of uranium dioxide, 0.1% uranium vacancies decrease the thermal conductivity by 24.6% while the same concentration of oxygen vacancies decreases the thermal conductivity of uranium dioxide by 19.4%. However, the uranium substitutional defects are shown to have a minimal effect on the thermal conductivity of plutonium dioxide because of the small change in the atomic mass.

Estilos ABNT, Harvard, Vancouver, APA, etc.

Varley, Joel B. "First-principles simulations of vacancy-related complexes in Ga2O3 and related alloys". In Oxide-based Materials and Devices XV, editado por Ferechteh H. Teherani e David J. Rogers. SPIE, 2024. http://dx.doi.org/10.1117/12.3023620.

Texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

Stavola, Michael, W. Beall Fowler, Amanda Portoff, Andrew Venzie, Evan Glaser e Stephen Pearton. "O-H centers in β-Ga2O3 with a Ga(1) vacancy at their core". In Oxide-based Materials and Devices XV, editado por Ferechteh H. Teherani e David J. Rogers. SPIE, 2024. http://dx.doi.org/10.1117/12.3009619.

Texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

Ryu, Byungki, Kee Joo Chang, Jisoon Ihm e Hyeonsik Cheong. "Electronic Structure of O-vacancy in Amorphous Zinc-Tin Oxides". In PHYSICS OF SEMICONDUCTORS: 30th International Conference on the Physics of Semiconductors. AIP, 2011. http://dx.doi.org/10.1063/1.3666284.

Texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

Riley, Christopher, Stanley Chou, Datye Abhaya e Andrew De La Riva. "Catalytic High Entropy Oxides Stabilized with Vacancy Contributed Configurational Entropy." In Proposed for presentation at the Materials Research Society Spring held April 17-23, 2021 in virtual, virtual, US. US DOE, 2021. http://dx.doi.org/10.2172/1862768.

Texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

Park, Kwangjin, Seungwhan Baek e Joongmyeon Bae. "Characterization of PSCF3737 for Intermediate Temperature-Operating Solid Oxide Fuel Cell (IT-SOFC)". In ASME 2008 6th International Conference on Fuel Cell Science, Engineering and Technology. ASMEDC, 2008. http://dx.doi.org/10.1115/fuelcell2008-65042.

Texto completo da fonte

Resumo:

Pr0.3Sr0.7Co0.3Fe0.7O3−δ (PSCF3737) was prepared and characterized as a cathode material for intermediate temperature-operating solid oxide fuel cell (IT-SOFC). X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), extended X-ray absorption fine structure (EXAFS), and electrical property measurement were performed to study cathode performance of the material. XPS and EXAFS results proved that oxygen vacancy concentration was decreased and lattice constants of the perovskite structure material was increased by doping Fe up to 70 mol% at B-site of the crystal structure, which also extended the distance between oxygen and neighbor atom. Thermal expansion coefficient (TEC) of PSCF3737 is smaller than that of Pr0.3Sr0.7CoO3−δ (PSC37) due to lower oxygen vacancy concentration. PSCF3737 showed better cathode performance than PSC37. It might be due good adhesion by a smaller difference of TEC between Gd0.1Ce0.9O2 (CGO91) and electrode. Composite material PSCF3737-CGO91 showed better compatibility of TEC than PSCF3737. However, PSCF3737-CGO91 did not represent higher electrochemical property than PSCF3737 due to a decline of reaction sites by CGO91.

Estilos ABNT, Harvard, Vancouver, APA, etc.

Lambrecht, Walter R. L., Dmitry Skachkov, Amol Ratnaparkhe, Hans Jürgen von Bardeleben, Uwe Gerstmann, Quoc Duy Ho e Peter Déak. "Computational studies of beta-Ga2O3 band structure and the electron paramagnetic resonance spectra of the Ga-vacancy defects (Conference Presentation)". In Oxide-based Materials and Devices IX, editado por Ferechteh H. Teherani, David C. Look e David J. Rogers. SPIE, 2018. http://dx.doi.org/10.1117/12.2297411.

Texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

Nakanishi, T., K. Chokawa, M. Araidai, T. Nakayama e K. Shiraishi. "Physics in HRS-LRS Switching in Vacancy Modulated Conductive Oxide (VMCO) Memories". In 2019 International Conference on Solid State Devices and Materials. The Japan Society of Applied Physics, 2019. http://dx.doi.org/10.7567/ssdm.2019.ps-2-15.

Texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

Sohn, Y. H., P. Mohan, P. Schelling e D. Nguyen. "Degradation of Thermal Barrier Coatings by Fuel Impurities and CMAS". In ITSC2009, editado por B. R. Marple, M. M. Hyland, Y. C. Lau, C. J. Li, R. S. Lima e G. Montavon. ASM International, 2009. http://dx.doi.org/10.31399/asm.cp.itsc2009p0089.

Texto completo da fonte

Resumo:

Abstract This study investigates the degradation of YSZ-CoNiCrAlY thermal barrier coatings (TBCs) due to vanadium and phosphorus pentoxides and calcium-magnesium aluminosilicate (CMAS) sand at temperatures up to 1400 °C. The pentoxides are shown to degrade bond coat and topcoat layers through acidic dissolution, while CMAS sand is shown to degrade YSZ layers through ingress and the precipitation of ZrO2 grains. Density functional theory simulations provide insights on reactions at the surface of fluorite-structured oxides and the role of oxygen vacancy clustering. A method to mitigate melt-infiltration attack through electrophoretic deposition is introduced.

Estilos ABNT, Harvard, Vancouver, APA, etc.

Yousefi, Saeed, Rob Trappen, Navid Mottaghi, Alan D. Bristow e Mikel Holcomb. "Oxygen vacancy effect on ultra-fast carrier dynamics of perovskite oxide La0.7Sr0.3MnO3 thin films". In Ultrafast Phenomena and Nanophotonics XXIV, editado por Markus Betz e Abdulhakem Y. Elezzabi. SPIE, 2020. http://dx.doi.org/10.1117/12.2550978.

Texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

Relatórios de organizações sobre o assunto "Oxigen vacancy"

Chen, Y. (Prospect for wavelength tunable lasers based on vacancy defects in alkaline-earth oxides). Office of Scientific and Technical Information (OSTI), outubro de 1989. http://dx.doi.org/10.2172/5418910.

Texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

Oferecemos descontos em todos os planos premium para autores cujas obras estão incluídas em seleções literárias temáticas. Contate-nos para obter um código promocional único!