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Artykuły w czasopismach na temat „Oxigen vacancy”

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Data publikacji: 13 lipca 2024

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1

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

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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.

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2

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

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3

Wu, Bao-Zhen, Te Zhu, Xing-Zhong Cao, Zhao-Ming Yang, Kun Zhang, Fu-Jun Gou i Yuan Wang. "Investigation of the Oxidation Behavior of Cr20Mn17Fe18Ta23W22 and Microdefects Evolution Induced by Hydrogen Ions before and after Oxidation". Materials 15, nr 5 (3.03.2022): 1895. http://dx.doi.org/10.3390/ma15051895.

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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.

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4

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

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5

Mastrikov, Yuri A., Denis Gryaznov, Guntars Zvejnieks, Maksim N. Sokolov, Māra Putniņa i Eugene A. Kotomin. "Sr Doping and Oxygen Vacancy Formation in La1−xSrxScO3−δ Solid Solutions: Computational Modelling". Crystals 12, nr 9 (14.09.2022): 1300. http://dx.doi.org/10.3390/cryst12091300.

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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.

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6

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

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7

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

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8

Peng, Yin-Hui, Chang-Chun He, Yu-Jun Zhao i Xiao-Bao Yang. "Multi-peak emission of In₂O₃ induced by oxygen vacancy aggregation". Journal of Applied Physics 133, nr 7 (21.02.2023): 075702. http://dx.doi.org/10.1063/5.0135162.

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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.

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9

Zhang, Sufen, Jianni Liu, Xiaoyang Dong, Xiaoxia Jia, Ziwei Gao i 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, nr 10 (2019): 2742–52. http://dx.doi.org/10.1039/c9se00464e.

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10

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

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11

Chen, Shihao, Yang Xiao, Wei Xie, Yinhai Wang, Zhengfa Hu, Wei Zhang i Hui Zhao. "Facile Strategy for Synthesizing Non-Stoichiometric Monoclinic Structured Tungsten Trioxide (WO3−x) with Plasma Resonance Absorption and Enhanced Photocatalytic Activity". Nanomaterials 8, nr 7 (21.07.2018): 553. http://dx.doi.org/10.3390/nano8070553.

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Oxygen vacancy defects play an important role in improving the light-capturing and photocatalytic activity of tungsten trioxide (WO3). However, the hydrogen treatment method that is commonly used to introduce oxygen vacancies is expensive and dangerous. Therefore, the introduction and control of oxygen vacancy defects in WO3 remains a challenge. Here, we demonstrated that oxygen vacancies could be successfully introduced into WO3−x while using a facile method through low temperature annealing in alcohol. The obtained WO3−x samples with optimal oxygen vacancies showed strong absorption of light, extending from the ultraviolet to the visible and near-infrared regions, and exhibits strong plasmon resonance from 400–1200 nm peaking at approximately 800 nm. When compared to pristine WO3, the photocatalytic activity of WO3−x was greatly improved in the ultraviolet and visible regions. This study provides a simple and efficient method to generate oxygen vacancies in WO3 for photocatalysis, which may be applied in the photoelectrochemical, electrochromic, and photochromic fields. Because oxygen vacancy is a common characteristic of metal oxides, the findings that are presented herein may be extended to other metal oxides.

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12

Sachs, Michael, Ji-Sang Park, Ernest Pastor, Andreas Kafizas, Anna A. Wilson, Laia Francàs, Sheraz Gul i in. "Effect of oxygen deficiency on the excited state kinetics of WO3 and implications for photocatalysis". Chemical Science 10, nr 22 (2019): 5667–77. http://dx.doi.org/10.1039/c9sc00693a.

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13

Bliem, R., E. McDermott, P. Ferstl, M. Setvin, O. Gamba, J. Pavelec, M. A. Schneider i in. "Subsurface cation vacancy stabilization of the magnetite (001) surface". Science 346, nr 6214 (4.12.2014): 1215–18. http://dx.doi.org/10.1126/science.1260556.

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Iron oxides play an increasingly prominent role in heterogeneous catalysis, hydrogen production, spintronics, and drug delivery. The surface or material interface can be performance-limiting in these applications, so it is vital to determine accurate atomic-scale structures for iron oxides and understand why they form. Using a combination of quantitative low-energy electron diffraction, scanning tunneling microscopy, and density functional theory calculations, we show that an ordered array of subsurface iron vacancies and interstitials underlies the well-known (2×2)R45° reconstruction of Fe3O4(001). This hitherto unobserved stabilization mechanism occurs because the iron oxides prefer to redistribute cations in the lattice in response to oxidizing or reducing environments. Many other metal oxides also achieve stoichiometry variation in this way, so such surface structures are likely commonplace.

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14

Murat, Altynbek, i Julia E. Medvedeva. "Native point defects in multicomponent transparent conducting oxides". MRS Proceedings 1633 (2014): 37–42. http://dx.doi.org/10.1557/opl.2014.144.

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ABSTRACTThe formation of native point defects in layered multicomponent InAMO4 oxides with A3+=Al or Ga, and M2+=Ca, Mg, or Zn, is investigated using first-principles density functional calculations. We calculated the formation energy of acceptor (cation vacancies, acceptor antisites) and donor (oxygen vacancy, donor antisites) defects within the structurally and chemically distinct layers of InAMO4 oxides. We find that the antisite donor defect, in particular, the A atom substituted on the M atom site (AM) in InAMO4 oxides, have lower formation energies, hence, higher concentrations, as compared to those of the oxygen vacancy which is know to be the major donor defect in binary constituent oxides. The major acceptor (electron “killer”) defects are cation vacancies except for InAlCaO4 where the antisite CaAl is the most abundant acceptor defect. The results of the defect formation analysis help explain the changes in the observed carrier concentrations as a function of chemical composition in InAMO4, and also why the InAlZnO4 samples are unstable under a wide range of growing conditions.

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15

Petel, Brittney E., i Ellen M. Matson. "Oxygen-atom vacancy formation and reactivity in polyoxovanadate clusters". Chemical Communications 56, nr 88 (2020): 13477–90. http://dx.doi.org/10.1039/d0cc05920j.

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Overview of recent work detailing oxygen-deficient polyoxovanadate clusters as models for reducible metal oxides: toward gaining a fundamental understanding the consequences of vacancy formation on metal oxide surfaces during catalysis.

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16

Ellis, D. E. "Vacancy and defect structures in metal oxides". Physics and Chemistry of Minerals 14, nr 4 (maj 1987): 303–7. http://dx.doi.org/10.1007/bf00309801.

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17

Chen, Pengqi, Mingli Qin, Zheng Chen, Baorui Jia i Xuanhui Qu. "Solution combustion synthesis of nanosized WOx: characterization, mechanism and excellent photocatalytic properties". RSC Advances 6, nr 86 (2016): 83101–9. http://dx.doi.org/10.1039/c6ra12375a.

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We present a method called solution combustion synthesis by using metal acid radical ions to design nanostructured tungsten oxide with both stoichiometric and oxygen-vacancy-rich nonstoichiometric oxides with excellent photocatalytic activity.

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18

Maiti, Debtanu, Yolanda A. Daza, Matthew M. Yung, John N. Kuhn i Venkat R. Bhethanabotla. "Oxygen vacancy formation characteristics in the bulk and across different surface terminations of La(1−x)SrxFe(1−y)CoyO(3−δ) perovskite oxides for CO2 conversion". Journal of Materials Chemistry A 4, nr 14 (2016): 5137–48. http://dx.doi.org/10.1039/c5ta10284g.

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19

Bhatt, Nisarg K., Brijmohan Y. Thakore, P. R. Vyas, A. Y. Vahora i Asvin R. Jani. "Thermal Properties of Divalent Metal Oxides: CaO as a Prototype". Solid State Phenomena 209 (listopad 2013): 190–93. http://dx.doi.org/10.4028/www.scientific.net/ssp.209.190.

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Commonly employed quasiharmonic approximation (QHA) is inadequate to account for intrinsic anharmonism such as phonon-phonon interaction, vacancy contribution, etc. Though anharmonic contributions are important at high temperatures and low pressure, complete ab initio calculations are scanty due largely to laborious computational requirements. Nevertheless, some simple semi-empirical schemes can be used effectively to incorporate the anharmonism. In this regards, in the present study we have proposed a simple computational scheme to include the effect of vacancy directly into the description within the mean-field potential approach, which calculates vibrational free energy of ions. Validity of the scheme is verified by taking calcium oxide as a test case. Equilibrium properties at (T,P) = (0,0) condition is obtained within the tight-binding second-moment approximation (TB-SMA), whose parameters were determined through first principles density functional theory. Kohn-Sham equations for core electrons were solved using ultrasoft plane-wave pseudopotential employing the generalized gradient approximation for exchange and correlation. Present findings for thermal expansion and high-T EOS clearly show perceptible improvement over the case when vacancy contribution was not included. Some related thermodynamic properties are also calculated and compared with the available experimental and theoretical data.

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20

Song, Myoung Geun, Jun Young Han i Chung Wung Bark. "The Effect of Annealing Temperature on the Bandgap of Bi3.25La0.75FeTi2O12 Powders". Journal of Nanoscience and Nanotechnology 15, nr 10 (1.10.2015): 8195–98. http://dx.doi.org/10.1166/jnn.2015.11275.

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In recent years, there has been increasing interest in the bandgap engineering of ferroelectric oxides to improve absorbance of the solar spectrum, which is governed by their band gap. To enhance the photovoltaic efficiency by tuning the optical bandgap of complex oxides, an attempt was recently made to reduce the optical band gap of iron doping of lanthanum-modified Bi4Ti3O12-based oxides (Fe-BLT) using oxygen vacancy doping. To study the tunability of the optical band gap from the generation of oxygen vacancies, the thermal treatment time and temperature were controlled during heat treatment under a vacuum environment. The structural, optical properties of the synthesized podwers were examined by X-ray diffraction, scanning electron microscopy, and ultraviolet-visible spectroscopy. Typically, an oxygen vacancy in a complex oxide can alter their structure very easily. On the other hand, the ultraviolet-visible absorption spectra of iron-doped bismuth titanate ceramics under optimal conditions (12 h, 800 °C) showed a decrease in optical bandgap from 2.02 eV to 1.8 eV without a corresponding change in their crystallographic structure. This study suggests that optimal control of the thermal treatment time and temperature critically effects the optical band gap of complex oxides.

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21

Sharma, Manisha, Ashish Kumar i Venkata Krishnan. "Influence of oxygen vacancy defects on Aurivillius phase layered perovskite oxides of bismuth towards photocatalytic environmental remediation". Nanotechnology 33, nr 27 (12.04.2022): 275702. http://dx.doi.org/10.1088/1361-6528/ac6088.

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Abstract The low light absorption and rapid recombination of photogenerated charge carriers are primary contributors to the low activity of various photocatalysts. Fabrication of oxygen vacancy defect-rich materials for improved photocatalytic activities has been attracting tremendous attention from researchers all over the world. In this work, we have compared the photocatalytic activities of oxygen vacancy-rich Bi2MoO6 (BMO-OV) and Bi2WO6 (BWO-OV) for the degradation of a model pharmaceutical pollutant, ciprofloxacin under visible light irradiation. The photocatalytic activity was increased from 47% to 77% and 40% to–67% for BMO-OV and BWO-OV, respectively in comparison to pristine oxides. This enhancement can be ascribed to suppressed charge carrier recombination and increased surface active sites. In addition, scavenger studies have been done to explain the role of photoinduced charge carriers in the degradation mechanism. Moreover, oxygen vacancy-rich photocatalysts have remained stable even after three consecutive cycles, making them promising materials for practical applications. Overall, this work provides deeper insight into the design and development of oxygen vacancy-rich materials.

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22

Mastrikov, Yuri A., Denis Gryaznov, Maksim N. Sokolov, Guntars Zvejnieks, Anatoli I. Popov, Roberts I. Eglitis, Eugene A. Kotomin i Maxim V. Ananyev. "Oxygen Vacancy Formation and Migration within the Antiphase Boundaries in Lanthanum Scandate-Based Oxides: Computational Study". Materials 15, nr 7 (6.04.2022): 2695. http://dx.doi.org/10.3390/ma15072695.

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The atomic structure of antiphase boundaries in Sr-doped lanthanum scandate (La1−xSrxScO3−δ) perovskite, promising as the proton conductor, was modelled by means of DFT method. Two structural types of interfaces formed by structural octahedral coupling were constructed: edge- and face-shared. The energetic stability of these two interfaces was investigated. The mechanisms of oxygen vacancy formation and migration in both types of interfaces were modelled. It was shown that both interfaces are structurally stable and facilitate oxygen ionic migration. Oxygen vacancy formation energy in interfaces is lower than that in the regular structure, which favours the oxygen vacancy segregation within such interfaces. The calculated energy profile suggests that both types of interfaces are advantageous for oxygen ion migration in the material.

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23

Zheng, Rongwei, Ruifan Tan, Yali Lv, Xiaoling Mou, Junqiao Qian, Ronghe Lin, Ping Fang i Weidong Kan. "Oxygen-Vacancy-Rich Fe@Fe3O4 Boosting Fenton Chemistry". Catalysts 13, nr 7 (30.06.2023): 1057. http://dx.doi.org/10.3390/catal13071057.

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Iron-based materials are widely applied in Fenton chemistry, and they have promising prospects in the processing of wastewater. The composition complexity and rich chemistry of iron and/or oxides, however, hamper the precise understanding of the active sites and the working mechanism, which still remain highly controversial. Herein, iron oxides of four different model systems are designed through a conventional precipitation method plus H2 reduction treatment. These systems feature Fe@Fe3O4 with abundant oxygen vacancy, Fe0 and Fe3O4 particles with interface structures, and Fe3O4-dominated nanoparticles of different sizes. These materials are applied in the decomposition of methyl orange as a model reaction to assess the Fenton chemistry. The Fe@Fe3O4 with core–shell structures exhibits significantly higher decomposition activity than the other Fe3O4-rich nanoparticles. A thin Fe3O4 layer formed by auto-oxidation of iron particles when exposed to air can boost the activity as compared with the Fe0 and Fe3O4 particles with interface structures but poor oxygen vacancy. The unique hetero-structure with the co-existence of both metallic iron and oxygen vacancy displays excellent redox propensity, which might account for the superior Fenton activity. This finding provides a new perspective to understand and design highly efficient iron-based Fenton catalysts.

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24

Filatova, E. O., S. S. Sakhonenkov, A. S. Konashuk i V. V. Afanas’ev. "Control of TiN oxidation upon atomic layer deposition of oxides". Physical Chemistry Chemical Physics 20, nr 44 (2018): 27975–82. http://dx.doi.org/10.1039/c8cp06076b.

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25

Qi, Yue, Christine James, Tridip Das, Jason D. Nicholas, Leah Nation i Brian W. Sheldon. "(Invited) Computing the Anisotropic Chemical Strain in Non-Stoichiometric Oxides for Solid Oxide Fuel Cell and Li-Ion Battery Applications". ECS Meeting Abstracts MA2018-01, nr 32 (13.04.2018): 1940. http://dx.doi.org/10.1149/ma2018-01/32/1940.

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Accurate characterization of chemical strain is required to study a broad range of chemical-mechanical coupling phenomena. By combining density functional theory (DFT) calculations and elastic dipole tensor theory, it is readily to predict the long-range chemical strain tensor and the chemical expansion coefficient tensor induced by dilute point defects in a crystal structure. First, we demonstrate that, even in cubic CeO2-δ, both the short-range deformation surrounding an oxygen vacancy and the long-range chemical strain (or the expansion coefficient) are anisotropic. The origin of this anisotropy is the charge disproportionation between the four cerium atoms surrounding each oxygen vacancy (two become Ce3+ and two become Ce4+) when a neutral oxygen vacancy is formed. While the short-range deformation agrees with experimentally determined Ce-O bond lengths, the predicted maximum and average chemical strains successfully bound the variety of CeO2-δ chemical strain behavior previously reported in the literature. Normally, since there are six possible disproportionation configurations, the average chemical strain is isotropic. Only under an external bias, such as an applied electric field, the chemical strain can be oriented to show the anisotropic effect. This successfully explained the giant electrostriction effect reported in doped and un-doped CeO2-δ. Next, we show strains induced by coupled vacancies in layered Li-intercalation compounds for battery applications. Li2MnO3 was investigated as Li-excess intercalation compounds containing Li2MnO3 need to be “activated” to deliver the high capacity. This activation process during the first delithiation cycle at a high voltage is believed to introduce oxygen vacancies into the system. Due to the large amount Li vacancy generated, a large number of defect configurations were sampled and the average chemical strain induced by Li vacancy concentration is obtained by Boltzmann average. Previously, we have demonstrated that it is energetically favorable to create a Li-O-Li vacancy dumbbell structure (VLi - VO - VLi) in Li2MnO3. The chemical strain of the vacancy dumbbell structure is smaller than the sum of the chemical strain of one Vo and two VLis. The chemical expansion coefficient averaged for the polycrystalline samples and the experimentally measured stress change provided a novel method to in situ track the irreversible chemical changes in Li-excess cathode materials.

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Xiao, Zhitong, Jiashen Meng, Fanjie Xia, Jinsong Wu, Fang Liu, Xiao Zhang, Linhan Xu, Xinming Lin i Liqiang Mai. "K+ modulated K+/vacancy disordered layered oxide for high-rate and high-capacity potassium-ion batteries". Energy & Environmental Science 13, nr 9 (2020): 3129–37. http://dx.doi.org/10.1039/d0ee01607a.

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A K⁺/vacancy disordered structure has been obtained by simply modulating the K⁺ contents in a series of K_xMn_0.7Ni_0.3O₂ layered oxides, which exhibits outstanding rate performance.

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27

Nakajima, Hideo, i Ryusuke Nakamura. "Diffusion in Intermetallic Compounds and Fabrication of Hollow Nanoparticles through Kirkendall Effect". Journal of Nano Research 7 (lipiec 2009): 1–10. http://dx.doi.org/10.4028/www.scientific.net/jnanor.7.1.

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. In intermetallic compounds, random vacancy motion is not possible as it would disrupt the equilibrium ordered arrangement of atoms on lattice sites. In view of this limitation, various atomistic models have been proposed, which allow atom-vacancy exchanges to take place without concomitant long range disordering. For a L12 -type A3B structure, the major element A diffuses faster than the minor element B. The trend is attributed to the different diffusing paths; A atoms can diffuse through site exchanges with a neighbouring vacancy on its own sublattice, while the jump of a B atom to a neighbouring site always creates wrong bonds. For L10-type structures such as γ-TiAl, significant diffusion anisotropy is observed; Ti atoms diffuse on the Ti sublattice, while Al atoms also diffuse on the Ti sublattice. The formation of hollow metal oxide nanoparticles through the oxidation process has been studied by transmission electron microscopy for Cu, Zn, Al, Pb and Ni. The hollow structure is obtained as a result of vacancy aggregation, resulting from the rapid outward diffusion of metal ions through the oxide layer during the oxidation process. This suggests the occurrence of two different diffusion processes in the formation of hollow oxides.

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Su, Mingji, Jirong Liu, Zeping Weng, Xiang Ding, Zhengyang Chen, Yi Zhang, Liang Zhao, Choonghyun Lee i Yi Zhao. "Stabilization of the ferroelectric phase in Hf-based oxides by oxygen scavenging". Applied Physics Express 14, nr 12 (29.11.2021): 126503. http://dx.doi.org/10.35848/1882-0786/ac3a3f.

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Abstract We propose an oxygen scavenging technique based on thermodynamic considerations of metal and oxygen systems to stabilize the ferroelectric phase and enhance the ferroelectricity in Hf-based oxides. By using an oxygen scavenging metal to control the oxygen vacancy concentration in Hf-based oxides, the effect of this oxygen scavenging technique in ferroelectric Hf-based oxides was systematically investigated. It was revealed that controlling the oxygen vacancies during the crystallization process is of vital importance to stabilizing the ferroelectric properties. This oxygen scavenging technique is an effective method of improving the performance of Hf-based ferroelectric materials without employing any dopant in Hf-based oxides.

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29

Zhu, Jiaxin, Jung-Woo Lee, Hyungwoo Lee, Lin Xie, Xiaoqing Pan, Roger A. De Souza, Chang-Beom Eom i Stephen S. Nonnenmann. "Probing vacancy behavior across complex oxide heterointerfaces". Science Advances 5, nr 2 (luty 2019): eaau8467. http://dx.doi.org/10.1126/sciadv.aau8467.

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Oxygen vacancies (VO••) play a critical role as defects in complex oxides in establishing functionality in systems including memristors, all-oxide electronics, and electrochemical cells that comprise metal-insulator-metal or complex oxide heterostructure configurations. Improving oxide-oxide interfaces necessitates a direct, spatial understanding of vacancy distributions that define electrochemically active regions. We show vacancies deplete over micrometer-level distances in Nb-doped SrTiO3 (Nb:SrTiO3) substrates due to deposition and post-annealing processes. We convert the surface potential across a strontium titanate/yttria-stabilized zirconia (STO/YSZ) heterostructured film to spatial (<100 nm) vacancy profiles within STO using (T = 500°C) in situ scanning probes and semiconductor analysis. Oxygen scavenging occurring during pulsed laser deposition reduces Nb:STO substantially, which partially reoxidizes in an oxygen-rich environment upon cooling. These results (i) introduce the means to spatially resolve quantitative vacancy distributions across oxide films and (ii) indicate the mechanisms by which oxide thin films enhance and then deplete vacancies within the underlying substrate.

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Katsman, A., G. Zeevi i Y. Yaish. "Stress Induced Vacancy Clustering Mechanism of Resistive Switching in Hafnium Oxides". MRS Advances 1, nr 5 (2016): 349–55. http://dx.doi.org/10.1557/adv.2016.81.

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ABSTRACTReversible changes in the conductivity of HfO2 dielectric film between high and low resistive states of a metal-insulator-metal memory cell were attributed to the formation of oxygen vacancies and their clustering across the insulator layer. In this study we present an innovative model which includes generation of two-charged states of oxygen vacancies at the anode, their diffusion to the cathode, transformation to one-charged state, and then to neutral vacancies. Vacancy clusters in the insulator layer are built from only neutral vacancies, while the kinetics of the clustering process is controlled by diffusion of mobile one-charged state vacancies. Resistive switching is treated as the formation of critical size vacancy cluster which provides continuous conductive path through the dielectric layer. Good agreement between the experimental data and the theoretical bias and temperature dependences for the delay time was obtained.

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López, C. A., J. C. Pedregosa, M. T. Fernández-Díaz i J. A. Alonso. "Ionic conductivity enhancement in Ti-doped Sr11Mo4O23 defective double perovskites". RSC Advances 7, nr 26 (2017): 16163–72. http://dx.doi.org/10.1039/c6ra28459k.

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A substantially higher ionic motion can be achieved by partially replacing Mo(vi) by Ti(iv) cations in the novel Sr₁₁Mo_4−xTi_xO_23−δ (with x = 0.0, 0.5 and 1.0) electrolyte oxides, successfully enhancing the oxygen vacancy level.

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Zhou, Gege, Wentong Geng, Lu Sun, Xue Wang, Wei Xiao, Jianwei Wang i Ligen Wang. "Influence of Mixed Valence on the Formation of Oxygen Vacancy in Cerium Oxides". Materials 12, nr 24 (5.12.2019): 4041. http://dx.doi.org/10.3390/ma12244041.

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Ceria is one of the most important functional rare-earth oxides with wide industrial applications. Its amazing oxygen storage/release capacity is attributed to cerium’s flexible valence conversion between 4+ and 3+. However, there still exists some debate on whether the valence conversion is due to the Ce-4f electron localization-delocalization transition or the character of Ce–O covalent bonds. In this work, a mixed valence model was established and the formation energies of oxygen vacancies and electronic charges were obtained by density functional theory calculations. Our results show that the formation energy of oxygen vacancy is affected by the valence state of its neighboring Ce atom and two oxygen vacancies around a Ce4+ in CeO2 have a similar effect to a Ce3+. The electronic charge difference between Ce3+ and Ce4+ is only about 0.4e. Therefore, we argue that the valence conversion should be understood according to the adjustment of the ratio of covalent bond to ionic bond. We propose that the formation energy of oxygen vacancy be used as a descriptor to determine the valence state of Ce in cerium oxides.

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Carey, John J., i M. Nolan. "Enhancing the oxygen vacancy formation and migration in bulk chromium(iii) oxide by alkali metal doping: a change from isotropic to anisotropic oxygen diffusion". Journal of Materials Chemistry A 5, nr 30 (2017): 15613–30. http://dx.doi.org/10.1039/c7ta00315c.

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Oxygen vacancy formation and migration are vital properties for reducible oxides such as TiO₂, CeO₂ and Cr₂O₃ as the oxygen storage capacity (OSC) of these materials are important for a wide range of applications in photovoltaics, oxidative catalysis and solid oxide fuel cells.

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Shluger, Alexander, Mladen Georgiev i Noriaki Itoh. "Self-trapped excitons and interstitial-vacancy pairs in oxides". Philosophical Magazine B 63, nr 4 (kwiecień 1991): 955–64. http://dx.doi.org/10.1080/13642819108205550.

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Matsuda, Y., M. Karppinen, Y. Yamazaki i H. Yamauchi. "Oxygen-vacancy concentration in A2MgMoO6−δ double-perovskite oxides". Journal of Solid State Chemistry 182, nr 7 (lipiec 2009): 1713–16. http://dx.doi.org/10.1016/j.jssc.2009.04.016.

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Varney, C., i F. Selim. "Positron Lifetime Measurements of Vacancy Defects in Complex Oxides". Acta Physica Polonica A 125, nr 3 (marzec 2014): 764–66. http://dx.doi.org/10.12693/aphyspola.125.764.

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Meng, Jie, Qingyun Lin, Tao Chen, Xiao Wei, Jixue Li i Ze Zhang. "Oxygen vacancy regulation on tungsten oxides with specific exposed facets for enhanced visible-light-driven photocatalytic oxidation". Nanoscale 10, nr 6 (2018): 2908–15. http://dx.doi.org/10.1039/c7nr08590g.

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Ji, Denghui, Bin Zhang, Yong Yang, Shuling Wang, Yingdi Liu, Yuanping Shi, Shunzhen Feng, Cuijian Zhao, Shaohui Shi i Qingqing Zhang. "The structural, magnetic and electrical transport properties of perovskite La0.67Sr0.33Mn1−x(VMn)xO3: The B-sites vacancies as a rapier". Modern Physics Letters B 35, nr 25 (5.08.2021): 2150415. http://dx.doi.org/10.1142/s0217984921504157.

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The polycrystalline samples of manganites perovskite [Formula: see text] with B-sites vacancies were synthesized using the conventional solid-state reaction method. The results based on the X-Ray Diffraction (XRD) and Scanning Electron Microscope (SEM) analyses show that the samples with [Formula: see text] have a secondary phase of lanthanum oxides. It indicates there is a maximum vacancy content at the B-sites with [Formula: see text]. By X-ray Photoelectron Spectra (XPS), the ionicities of oxygen were determined to be 0.762, 0.842, and 0.886, corresponding to [Formula: see text], 0.03, and 0.05, respectively. The B-sites vacancy plays an important role in magnetic performances: (i) B-sites vacancy changes the contents and the average cant angle of Mn cations, and makes the specific saturation magnetization at 100 K and 300 K increase, and then decrease rapidly. (ii) The Curie temperature changes in a small range from 363.93 K to 366.00 K, resulting from both the double exchange interaction increasing and the double exchange path destroyed by the vacancies. (iii) The magnetoresistance (MR) at room temperature achieves 6.97% in the [Formula: see text] sample, whose value is larger than that of [Formula: see text] sample.

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Lai, Chun Hung, Wen Shiush Chen, Cheng Hsing Hsu, Yi Mu Lee, Jenn Sen Lin i Tze Ming Chen. "Resistive Switching Properties of Zr, Ti, and Zn Metal Oxides". Advanced Materials Research 1119 (lipiec 2015): 194–97. http://dx.doi.org/10.4028/www.scientific.net/amr.1119.194.

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Sputtered metal oxides of Zr, Ti, and Zn were investigated on their resistive switching properties. All these three oxides exhibit electrode independence of the on-state currents, implying presence of non-uniform distribution of the conduction paths. The formation and rupture of those low-resistance filaments determine the reversible stable conductions and transition thresholds, which is related to the oxygen vacancy. The change in filament size explains the effect of current compliance and sweeping bias under various deposition temperatures and ambient. The decrease or increase of conduction currents is ascribed to the varying length and cross-section area of the filaments.

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Delmas, Claude, Marie Guignard i Francois Weill. "(Invited) Overview of the Ordering Phenomena in Li and Na Layered Oxide Electrode Materials". ECS Meeting Abstracts MA2022-02, nr 1 (9.10.2022): 23. http://dx.doi.org/10.1149/ma2022-02123mtgabs.

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AX(M)O2 layered oxides (A = Li, Na) are considered as the best positive electrode materials either for Li ion and Na ion batteries. In most of the systems, the shape of the voltage curve shows change in slope of the curve which indicate the occurrence of structural transitions due to: (i) electronic configuration modification in the MO2 slab, (ii) change in the slab packing, (iii) alkali ion-vacancy ordering. Moreover, in AX(M,L)O2 materials a M/L ordering can occur within the (M,L)O2 slab for the pristine material. Lithium and sodium tends to be ordered in the deintercalated materials for peculiar compositions. Nevertheless, due to the larger ionic radii of Na+ vs Li+, the repulsive interaction between sodium ions are stronger for sodium, leading to many Na+/vacancy patterns in the interslab space. Moreover, transition element orderings can occur within the (L,M)O2 slab if the difference in size is significant and if the cation ratio corresponds to a specific composition (1/3, ½, 2/3...). Then an interesting behaviour is observed as the sodium/vacancy ordering in the interslab space can be st superimposed to the cation ordering. Another original situation is also observed for cations (d2 or d3) which like to form M-M bonds. In this case, the pattering of short bond and long bond in the MO2 slab is directly related to the Na+/vacancy distribution and to the M3+/M4+ ratio.

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Li, Xiang, Hao Wang, Zhiming Cui, Yutao Li, Sen Xin, Jianshi Zhou, Youwen Long, Changqing Jin i John B. Goodenough. "Exceptional oxygen evolution reactivities on CaCoO3 and SrCoO3". Science Advances 5, nr 8 (sierpień 2019): eaav6262. http://dx.doi.org/10.1126/sciadv.aav6262.

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We investigated the roles of covalent bonding, separation of surface oxygen, and electrolyte pH on the oxygen evolution reaction (OER) on transition metal oxides by comparing catalytic onset potentials and activities of CaCoO3 and SrCoO3. Both cubic, metallic perovskites have similar CoIV intermediate spin states and onset potentials, but a substantially smaller lattice parameter and shorter surface oxygen separation make CaCoO3 a more stable catalyst with increased OER activity. The onset potentials are similar, occurring where H+ is removed from surface -OH−, but two competing surface reactions determine the catalytic activity. In one, the surface -O− is attacked by electrolyte OH− to form the surface -OOH−; in the other, two -O− form a surface peroxide ion and an oxygen vacancy with electrolyte OH− attacking the oxygen vacancy. The second pathway can be faster if the surface oxygen separation is smaller.

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Gerasimov, Evgeny, Vladimir Zajkovskij, Lubov Isupova i Sergey Tsybulya. "Microstructure Features of the Calcium Manganite in the Case of Different Partial Oxygen Pressure". Siberian Journal of Physics 4, nr 4 (1.12.2009): 59–64. http://dx.doi.org/10.54362/1818-7919-2009-4-4-59-64.

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By the transmission electronic microscopy and X-ray powder diffraction influence of various gas environments on the perovskite – like oxides CaMnO3 microstructure synthesized by polymer-salt method was researched. Formation of the vacancy-ordered structures in the [101] direction in the samples participated in catalytic reaction of CH4 oxidation was revealed. Partial disintegration of the solid solutions was fixed at heating the sample in vacuum up to 1 100oC.

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Chen, Zhenpan, Qingqing Jiang, Feng Cheng, Jinhui Tong, Min Yang, Zongxuan Jiang i Can Li. "Sr- and Co-doped LaGaO3−δ with high O2 and H2 yields in solar thermochemical water splitting". Journal of Materials Chemistry A 7, nr 11 (2019): 6099–112. http://dx.doi.org/10.1039/c8ta11957k.

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Sr- and Co-doped perovskite oxides La_1−xSrxGa_1−yCo_yO_3−δ (LSGC) with controllable oxygen vancancy formation energy (E_V) and oxygen vacancy concentration (−) are successfully developed to exhibit high O₂ and H₂ yields when reduced at 1350 °C and re-oxidized at optimized 400−1100 °C.

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Wu, J., L. P. Li, W. T. P. Espinosa i S. M. Haile. "Defect chemistry and transport properties of BaxCe0.85M0.15O3-δ". Journal of Materials Research 19, nr 8 (sierpień 2004): 2366–76. http://dx.doi.org/10.1557/jmr.2004.0302.

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The site-incorporation mechanism of M3+ dopants into A2+B4+O3 perovskites controls the overall defect chemistry and thus their transport properties. For charge-balance reasons, incorporation onto the A2+-site would require the creation of negatively charged point defects (such as cation vacancies), whereas incorporation onto the B4+-site is accompanied by the generation of positively charged defects, typically oxygen vacancies. Oxygen-vacancy content, in turn, is relevant to proton-conducting oxides in which protons are introduced via the dissolution of hydroxyl ions at vacant oxygen sites. We propose here, on the basis of x-ray powder diffraction studies, electron microscopy, chemical analysis, thermal gravimetric analysis, and alternating current impedance spectroscopy, that nominally B-site doped barium cerate can exhibit dopant partitioning as a consequence of barium evaporation at elevated temperatures. Such partitioning and the presence of significant dopant concentrations on the A-site negatively impact proton conductivity. Specific materials examined are BaxCe0.85M0.15O3-δ (x = 0.85 - 1.20; M = Nd, Gd, Yb). The compositional limits for the maximum A-site incorporation are experimentally determined to be: (Ba0.919Nd0.081)(Ce0.919Nd0.081)O3, (Ba0.974Gd0.026)(Ce0.872Gd0.128)O2.875, and Ba(Ce0.85Yb0.15)O2.925. As a consequence of the greater ability of larger cations to exist on the Ba site, the H2O adsorption and proton conductivities of large-cation doped barium cerates are lower than those of small-cation doped analogs.

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Wang, Yingying, Jingnan Zhang, M. S. Balogun, Yexiang Tong i Yongchao Huang. "Oxygen vacancy–based metal oxides photoanodes in photoelectrochemical water splitting". Materials Today Sustainability 18 (czerwiec 2022): 100118. http://dx.doi.org/10.1016/j.mtsust.2022.100118.

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Kim, Inseo, Hyungwoo Lee i Minseok Choi. "First-principles study of oxygen vacancy formation in strained oxides". Journal of Applied Physics 131, nr 7 (21.02.2022): 075106. http://dx.doi.org/10.1063/5.0077043.

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Young, Joshua, Eun Ju Moon, Debangshu Mukherjee, Greg Stone, Venkatraman Gopalan, Nasim Alem, Steven J. May i James M. Rondinelli. "Polar Oxides without Inversion Symmetry through Vacancy and Chemical Order". Journal of the American Chemical Society 139, nr 7 (15.02.2017): 2833–41. http://dx.doi.org/10.1021/jacs.6b10697.

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Klie, R. F., Y. Ito, S. Stemmer i N. D. Browning. "Observation of oxygen vacancy ordering and segregation in Perovskite oxides". Ultramicroscopy 86, nr 3-4 (luty 2001): 289–302. http://dx.doi.org/10.1016/s0304-3991(00)00120-0.

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Mateos, J. M. Jimenez, W. Jones, J. Morales i J. L. Tirado. "Composition and cation-vacancy distribution of cation-deficient spinel oxides". Journal of Solid State Chemistry 93, nr 2 (sierpień 1991): 443–53. http://dx.doi.org/10.1016/0022-4596(91)90318-c.

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Wu, Qi-Hui, A. Thissen, W. Jaegermann i Meilin Liu. "Photoelectron spectroscopy study of oxygen vacancy on vanadium oxides surface". Applied Surface Science 236, nr 1-4 (wrzesień 2004): 473–78. http://dx.doi.org/10.1016/j.apsusc.2004.05.112.

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