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991.
Rebekah Chua Jing Yang Xiaoyue He Xiaojiang Yu Wei Yu Fabio Bussolotti Ping Kwan Johnny Wong Kian Ping Loh Mark B. H. Breese Kuan Eng Johnson Goh Yu Li Huang Andrew T. S. Wee 《Advanced materials (Deerfield Beach, Fla.)》2020,32(24):2000693
There have been several recent conflicting reports on the ferromagnetism of clean monolayer VSe2. Herein, the controllable formation of 1D defect line patterns in vanadium diselenide (VSe2) monolayers initiated by thermal annealing is presented. Using scanning tunneling microscopy and q-plus atomic force microscopy techniques, the 1D line features are determined to be 8-member-ring arrays, formed via a Se deficient reconstruction process. The reconstructed VSe2 monolayer with Se-deficient line defects displays room-temperature ferromagnetism under X-ray magnetic circular dichroism and magnetic force microscopy, consistent with the density functional theory calculations. This study possibly resolves the controversy on whether ferromagnetism is intrinsic in monolayer VSe2, and highlights the importance of controlling and understanding the atomic structures of surface defects in 2D crystals, which could play key roles in the material properties and hence potential device applications. 相似文献
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996.
Mattia Zanni Alessandro Morri Lorella Ceschini 《Fatigue & Fracture of Engineering Materials & Structures》2022,45(1):113-132
A new model for the high cycle notch fatigue strength prediction of tool steels subjected to axial loading is proposed, based on previous literatures studies and experimental tests carried out on six different tool steels, including rotating bending fatigue tests on notched specimens, fractographic analyses, hardness, residual stress, and roughness measurements. The novelty is the assumption that surface defects are the main cause of notch fatigue failures of such steels. A probabilistic approach was implemented by modeling size distributions of defects, resulting in the prediction of normal distributions of fatigue strength. Like to other previous models, the effect of steel hardness, surface residual stress, notch severity, and specimen size was also taken into account. Model calibration and validation were performed using the data collected by the experimental activity. Model behavior was investigated by performing a sensitivity analysis, aiming to verify the response to variations of the considered input variables. Prediction errors of only 1.3% (on average) and 3.1% (maximum) resulted from the comparison between model-predicted and experimental notch fatigue strength. 相似文献
997.
Aiping Chen Qing Su Hyungkyu Han Erik Enriquez Quanxi Jia 《Advanced materials (Deerfield Beach, Fla.)》2019,31(4)
Vertically aligned nanocomposite thin films with ordered two phases, grown epitaxially on substrates, have attracted tremendous interest in the past decade. These unique nanostructured composite thin films with large vertical interfacial area, controllable vertical lattice strain, and defects provide an intriguing playground, allowing for the manipulation of a variety of functional properties of the materials via the interplay among strain, defect, and interface. This field has evolved from basic growth and characterization to functionality tuning as well as potential applications in energy conversion and information technology. Here, the remarkable progress achieved in vertically aligned nanocomposite thin films from a perspective of tuning functionalities through control of strain, defect, and interface is summarized. 相似文献
998.
Bingchen Zhang Shuo Liu Haochen Li Dong Wang Wenpei Kang Daofeng Sun 《Small (Weinheim an der Bergstrasse, Germany)》2023,19(27):2208228
The rational structural design of the electrode materials is significant to enhance the electrochemical performance for potassium ion storage, benefiting from the shortened ion diffusion distance, increased conductivity, and pseudo-capacitance promotion. Herein, hydrated vanadium oxide (HVO) nanosheets with enriched oxygen defects are well confined into hollow mesoporous carbon spheres (HMCS), producing Od-VOH@C nanospheres through one-step hydrothermal reaction. Attributed to the restricted growth in the HMCS, the HVO nanosheets are loosely packed, generating abundant interfacial boundaries and large specific areas. As a result, Od-VOH@C nanospheres show increased reaction kinetics and well buffer the volume effects for the K+ storage. Od-VOH@C delivers stable capacities of 138 mAh g−1 at 2.0 A g−1 over 10 000 cycles in half-cells attributed to the high pseudo-capacitance contribution. The K+ storage mechanism of insertion and conversion reaction is confirmed by ex situ X-ray diffraction, Raman, and X-ray photoelectron spectroscopy analyses. Moreover, the symmetric potassium-ion capacitors of Od-VOH@C//Od-VOH@C deliver a high energy density of 139.6 Wh kg−1 at the power density of 948.3 W kg−1. 相似文献
999.
Yiming Ding Yunchao Zhao Shuncheng Yao Shaobo Wang Xingyi Wan Quanhong Hu Linlin Li 《Small (Weinheim an der Bergstrasse, Germany)》2023,19(24):2300327
Sonodynamic therapy (SDT) is regarded as a new-rising strategy for cancer treatment with low invasiveness and high tissue penetration, but the scarcity of high-efficiency sonosensitizers has seriously hindered its application. Herein, the iron-doped and oxygen-deficient bismuth tungstate nanosheets (BWO-Fe NSs) with piezotronic effect are synthesized for enhanced SDT. Due to the existence of oxygen defects introduced through Fe doping, the bandgap of BWO-Fe is significantly narrowed so that BWO-Fe can be more easily activated by exogenous ultrasound (US). The oxygen defects acting as the electron traps inhibit the recombination of US-induced electrons and holes. More importantly, the dynamically renewed piezoelectric potential facilitates the migration of electrons and holes to opposite side and causes energy band bending, which further promotes the production of reactive oxygen species. Furthermore, Fe doping endows BWO-Fe with Fenton reactivity, which converts hydrogen peroxide (H2O2) in tumor microenvironment into hydroxyl radicals (•OH), thereby amplifying the cellular oxidative damage and enhancing SDT. Both in vitro and in vivo experiments illustrate their high cytotoxicity and tumor suppression rate against refractory breast cancer in mice. This work may provide an alternative strategy to develop oxygen-deficient piezoelectric sonosensitizers for enhanced SDT via doping metal ions. 相似文献
1000.
Anuj Pokle Daniel Weber Matteo Bianchini Jürgen Janek Kerstin Volz 《Small (Weinheim an der Bergstrasse, Germany)》2023,19(4):2205508
In lithium ion batteries (LIBs), the layered cathode materials of composition LiNi1−x−yCoxMnyO2 are critical for achieving high energy densities. A high nickel content (>80%) provides an attractive balance between high energy density, long lifetime, and low cost. Consequently, Ni-rich layered oxides cathode active materials (CAMs) are in high demand, and the importance of LiNiO2 (LNO) as limiting case, is hence paramount. However, achieving perfect stoichiometry is a challenge resulting in various structural issues, which successively impact physicochemical properties and result in the capacity fade of LIBs. To better understand defect formation in LNO, the role of the Ni(OH)2 precursor morphology in the synthesis of LNO requires in-depth investigation. By employing aberration-corrected scanning transmission electron microscopy, electron energy loss spectroscopy, and precession electron diffraction, a direct observation of defects in the Ni(OH)2 precursor preparedis reported and the ex situ structural evolution from the precursor to the end product is monitored. During synthesis, the layered Ni(OH)2 structure transforms to partially lithiated (non-layered) NiO and finally to layered LNO. The results suggest that the defects observed in commercially relevant CAMs originate to a large extent from the precursors, hence care must be taken in tuning the co-precipitation parameters to synthesize defect-free Ni-rich layered oxides CAMs. 相似文献