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Robust enhancement of valley polarization and quantum yield in composition grading lateral heterostructure of MoS2-WS2 monolayer

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Progress in Natural science:materials International 2024年第1期34卷 187-193页

作者： Mengke Kang Cheng Zhang Congpu Mu Kun Zhai Tianyu Xue Bochong Wang Fusheng Wen Yingchun Cheng Jianyong Xiang Jun-Feng Dai Anmin Nie Zhongyuan Liu Center for High Pressure Science State Key Laboratory of Metastable Materials Science and Technology Yanshan University Shenzhen Institute for Quantum Science and Engineering and Department of Physics Southern University of Science and Technology Shenzhen Key Laboratory of Quantum Science and Engineering

Valley degeneracy can be broken owing to the strong spin-orbit coupling in two-dimensional transition metal dichalcogenides（2D-TMDCs）. Valley-dependent interaction of carriers in TMDCs with different circular polarizations of light offers valley degree-of-freedom besides charge and spin to carry information. Thus, bandgap engineering of 2D-TMDCs plays a critical role in developing practical valleytronic devices. Hereby, we demonstrate a great enhancement in quantum yield as well as polarization of monolayer MoS2achieved by gradually alloying W atoms in MoS2. By appropriately setting a time offset between the evaporation of MoO3and WO3precursors during chemical vapor deposition, a compositionally graded heterostructure of MoS2-WS2monolayer can be readily grown at large scale. Raman and transmission electron microscopy measurements demonstrate that the interface possesses a steep gradient in composition, spanning from MoS2to WS2over a length ～2 μ*** to pure monolayer MoS2, the photoluminescence intensity at the compositionally graded interface of Mo1-xWxS2was observed to increase by a factor of 16 owing to the effective separation of photogenerated carriers by the built-in electric field. Particularly, a remarkably high polarization of 70% at 16 K is demonstrated for the compositionally graded interface of Mo1-xWxS2, which is ～1.4 times larger than that in MoS2and is attributed to the combined effect of the alloyed structure and graded bandgap. Such an engineering scheme with a graded bandgap offers new approach for the development of high-efficiency valleytronics devices.

关键词： Transition metal dichalcognide monolayer Compositionally graded in-plane heterostructure Chemical vapor deposition Valley polarization Quantum yield

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Temperature-dependent microstructural evolution in a compositionally complex solid electrolyte:The role of a grain boundary transition

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Journal of Advanced Ceramics 2025年第3期14卷 163-176页

作者： Shu-Ting Ko Chaojie Du Huiming Guo Hasti Vahidi Jenna L.Wardini Tom Lee Yi Liu Jingjing Yang Francisco Guzman Timothy J.Rupert William J.Bowman Shen J.Dillon Xiaoqing Pan Jian Luo Aiiso Yufeng Li Family Department of Chemical and Nano Engineering University of California San DiegoLa JollaCalifornia 92093USA Program in Materials Science and Engineering University of California San DiegoLa JollaCalifornia 92093USA Department of Materials Science and Engineering University of California IrvineIrvineCalifornia 92697USA Department of Physics and Astronomy University of California IrvineIrvineCalifornia 92697USA Irvine Materials Research Institute University of California IrvineIrvineCalifornia 92697USA

Compositionally complex solid electrolyte(Li_(0.375)Sr_(0.4375))(Ta_(0.375)Nb_(0.375)Zr_(0.125)Hf_(0.125))O_(3)(LSTNZH)samples are synthesized using different sintering temperatures,durations,and cooling conditions(furnace cooling(FC)*** quenching(AQ)).The temperature-dependent grain growth has been examined to investigate the microstructural evolution and the origin of exaggerated(abnormal)grain *** moderate temperatures,the grain growth of LSTNZH follows a cubic root growth model with an Arrhenius temperature *** increasing temperature,bimodal microstructures develop,and the Arrhenius temperature dependence breaks ***,increasing the temperature induces increased Nb segregation at general grain boundaries(GBs),in contrast to classical GB segregation models but suggesting premelting-like GB disordering,which can explain the observed abnormal grain growth(AGG).In addition,the large grains become faceted with increasing temperature,which occurs concurrently with the temperature-induced transitions in GB segregation and grain growth,thereby further supporting the occurrence of a GB phase-like(complexion)*** impacts on the densification,ionic conductivity,and hardness are also *** work provides a new insight into the fundamental understanding of the grain growth mechanisms of the emergent class of medium-and high-entropy compositionally complex ceramics(CCCs),which is essential for tailoring microstructures and material properties.

关键词： compositionally complex ceramics(CCCs) solid electrolytes perovskite grain growth grain boundary(GB) electron backscatter diffraction(EBSD)

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Effects of Ta content on microstructure and oxidation behavior of AlCoCrFeNiYTa_(x)high entropy alloy

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Rare Metals 2024年第9期43卷 4462-4475页

作者： Cang Gu Jun-Hao Hu Jian-Bo Song Cheng Xu Ming-Yu Hu Yu-Xuan Zhang Jiang Tian Chao Li Jing Feng Faculty of Materials Science and Engineering Kunming University of Science and TechnologyKunming 650093China Department of Physics Hong Kong Baptist UniversityHong Kong 999077China

The oxidation behavior of the Al CoCrFeNiYTa_(x)high entropy alloy(HEA)doped with different Ta contents at 1100℃is *** this study,different reasons for the spallation of the oxide scales of HEAs without/with excessive Ta addition after 1000 h of oxidation are discussed,and the most suitable Ta doping content for this HEA is explored,in which the HEA exhibits both an exceptionally low oxidation rate,and the formation of oxide scales composed of intact a-Al_(2)O_(3).Meanwhile,it is found that the addition of Ta can effectively inhibit the phase transition of β phase,which makes the surface of the oxide scale *** combining our experimental results with Wagner–Hauffe theory,the influence of Ta drag effect on oxide scale growth is explained,which provides some theoretical guidance for the subsequent design of AlCoCrFeNi HEAs,and can lead to the development of thermal barrier coatings at higher service temperature.

关键词： High-entropy alloy Al_(2)O_(3)scales Oxidation Elements diffusion

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Oscillatory Hall effect from magnetoelectronic coupling in flexoelectronic silicon

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Physical Review B 2024年第8期109卷 L081113-L081113页

作者： Paul C. Lou Ravindra G. Bhardwaj Anand Katailiha W. P. Beyermann Sandeep Kumar Department of Mechanical Engineering University of California Riverside California 92521 USA Department of Physics and Astronomy University of California Riverside California 92521 USA Materials Science and Engineering Program University of California Riverside California 92521 USA

Magnetoelectronic coupling can be defined as cross-domain coupling between electronic and magnetic properties, where modulation in magnetic properties changes the electronic properties. In this Letter, explicit experimental evidence of magnetoelectronic coupling is presented, which is uncovered from the oscillatory Hall effect response in Hall measurement. The strain gradient in a MgO (1.8 nm)/p-Si (∼400 nm) freestanding sample leads to transfer of electrons (∼5×1018cm−3) from valence to conduction band due to flexoelectronic charge separation in the p-Si layer. The resulting flexoelectronic polarization gives rise to the temporal magnetic moment from dynamical multiferroicity. The external magnetic field changes the net temporal magnetic moment, which causes modulations in charge carrier concentration and oscillatory Hall effect. The period of oscillatory Hall response is 1.12 T, which is attributed to the magnitude of the temporal magnetic moment. The discovery of the oscillatory Hall effect adds another member to the family of Hall effects.

关键词： Hall effect Doped semiconductors Electronically polarized systems Flexoelectrics Multiferroics Hall bar

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Effect of Structural Configu ations on Mechanical and Shape Recovery Properties of Ni Ti Triply Periodic Minimal Surface Porous Structures

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Chinese Journal of Mechanical engineering 2024年第6期37卷 303-319页

作者： Shuaishuai Wei Bo Song Lei Zhang Xiaobo Wang Junxiang Fan Zhi Zhang Yusheng Shi State Key Laboratory of Materials Processing and Die and Mould Technology School of Materials Science and EngineeringHuazhong University of Science and TechnologyWuhan 430074China Institute of Materials China Academy of Engineering PhysicsMianyang 621907China Department of Mechanical Engineering City University of Hong KongKowloon 999077China

Based on the advantages of triply periodic minimal surface(TPMS)porous structures,extensive research on NiTi shape memory alloy TPMS scaffolds has been ***,the current reports about TPMS porous structures highly rely on the implicit equation,which limited the design *** this work,novel shell-based TPMS structures were designed and fabricated by laser powder bed *** comparisons of manufacturability,mechanical properties,and shape recovery responses between traditional solid-based and novel shell-based TPMS structures were *** indicated that the shell-based TPMS porous structures possessed larger Young's moduli and higher compressive ***,Diamond shell structure possessed the highest Young's moduli of 605.8±24.5MPa,while Gyroid shell structure possessed the highest compressive strength of 43.90±3.32 *** addition,because of the larger specific surface area,higher critical stress to induce martensite transformation,and lower austenite finish temperature,the Diamond shell porous structure exhibited much higher shape recovery performance(only 0.1%residual strain left at pre-strains of 6%)than other porous *** results substantially uncover the effects of structural topology on the mechanical properties and shape recovery responses of NiTi shape memory alloy scaffolds,and confirm the effectiveness of this novel structural design *** research can provide guidance for the structural design application of NiTi porous scaffolds in bone implants.

关键词： NiTi shape memory alloy Porous structure Laser powder bed fusion Mechanical property Shape recovery property

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Spray deposited yttrium incorporated TiO_(2) photoelectrode for efficient photoelectrocatalytic degradation of organic pollutants

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Journal of Rare Earths 2023年第12期41卷 1929-1937,I0004页

作者： N.A.Narewadikar R.S.Pedanekar V.G.Parale H.H.Park K.Y.Rajpure Electrochemical Materials Laboratory Department of PhysicsShivaji UniversityKolhapur46004India Department of Materials Science and Engineering Yonsei University Seoul037322South Korea

This work presents result on yttrium-doped titanium dioxide(YTO) thin films using a cost-effective spray pyrolysis technique for the photoelectrocatalytic degradation of phthalic acid(PA) and benzoic acid(BA).The physicochemical properties of YTO thin films were studied using X-ray diffraction,Raman spectroscopy,X-ray photoelectron spectroscopy,field-emission scanning electron microscopy,UV-vis spectroscopy,*** obtained results confirm the presence of yttrium in the host *** band bending and flat band positions were studied using Mott-Schottky *** film with 1% doping amount shows the highest degradation efficiency for both the model pollutants compared to TiO_(2).The stability of 1% YTO film confirms excellent performance analyzed by recycling tests using a UV-vis *** results highlight the significance of rare earth metal doping in TiO_(2)for improved photoelectrocatalytic degradation efficiency.

关键词： Doping Organic pollutant Spray pyrolysis Thin film TiO_(2) Rare earths

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Phase-transition-free rivets for layered oxide potassium cathodes

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Nano Research 2024年第11期17卷 9671-9678页

作者： Jie Chen Apparao M. Rao Caitian Gao Jiang Zhou Limei Cha Xiaoming Yuan Bingan Lu School of Physics and Electronics Hunan University Changsha 410082 China Department of Physics and Astronomy Clemson Nanomaterials Institute Clemson University Clemson SC USA School of Materials Science and Engineering Central South University Changsha 410083 China Materials Science and Engineering program Guangdong Technion-Israel Institute of Technology Shantou 515063 China Materials Science and Engineering program Technion-Israel Institute of Technology Haifa 32000 Israel MATEC Key Lab Guangdong Technion-Israel Institute of Technology Shantou 515063 China Hunan Key Laboratory of Nanophotonics and Devices School of Physics Central South University Changsha 410078 China

As a cathode material for potassium-ion batteries (PIBs), manganese-based layered oxides have attracted widespread attention due to their low cost, ease of synthesis, and high performance. However, the Jahn-Teller effect caused by Mn3+ and the irreversible phase transformation of the structure leads to poor cycle stability, limiting the development of layered oxides in PIBs. Herein, we demonstrate the use of phase-transition-free CaTiO_(3) as rivets in K_(0.5)Mn_(0.9)Ti_(0.1)O_(2) by a simple solid-state method. As verified by the in situ X-ray diffraction, the CaTiO_(3) rivets effectively prevent the slippage of the transition metal layer during charge and discharge, inhibiting structural degradation. As a result, the obtained K_(0.5)Mn_(0.9)Ti_(0.1)O_(2)-0.02CaTiO_(3) shows excellent cycling stability and rate performance, with high capacities of 119.3 and 70.1 mAh·g^(-1) at 20 and 1000 mA·g^(-1), respectively. At 200 mA·g^(-1), the capacity retention remains 94.7% after more than 300 cycles. This work represents a new avenue for designing and optimizing layered cathode materials for PIBs and other batteries.

关键词： potassium cathodes layered oxide phase-transition-free perovskite rivets

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Finite-time PID control for nonlinear nonaffine systems

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science China(Information sciences) 2024年第11期67卷 238-251页

作者： Zhiqing LIU Ronghu CHI Biao HUANG Zhongsheng HOU College of Mathematics and Physics Qingdao University of Science and Technology College of Automation and Electronic Engineering Qingdao University of Science and Technology Department of Chemical and Materials Engineering University of Alberta School of Automation Qingdao University

This article proposes a finite-time proportional-integral-derivative(FT-PID) control method to fast stabilize the control system to achieve the desired performance within the predesignated time *** a considered nonaffined nonlinear system, we develop a new dynamic linearization approach to reformulate the system model as a linear data model(LDM) whose arguments are consistent with that used in the PID control law. Then, a projection algorithm is presented to estimate the unknown pseudo gradient vector of the LDM. Subsequently, an adaptive tuning algorithm is designed to update the three PID parameters by solving linear matrix inequalities in terms of the predesignated error precision and the finite-time instant. The finite-time convergence of the proposed FT-PID control system is shown mathematically, which guarantees a pre-specified error precision to be achieved within the predesignated finite-time instants. As a result, not only can the proposed FT-PID control save the control cost but it also improves the production efficiency. The simulation study verifies the results.

关键词： PID control finite-time control nonlinear nonaffine systems linear data model finite-time convergence

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Optical anapole modes in hybrid metal–dielectric nanoantenna for near-field enhancement and optical sensing

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Chinese physics B 2023年第11期32卷 296-305页

作者：王德宝吕靖薇刘伟任艳茹李薇许鑫辰刘超朱剑豪 School of Physics and Electronic Engineering Northeast Petroleum UniversityDaqing 163318China Department of Physics Department of Materials Science and Engineeringand Department of Biomedical EngineeringCity University of Hong KongHong Kong 999077China

Metal–dielectric nanostructures in the optical anapole modes are essential for light–matter interactions due to the low material loss and high near-field enhancement. Herein, a hybrid metal–dielectric nanoantenna composed of six wedgeshaped gold(Au) nanoblocks as well as silica(SiO2) and silicon(Si) nanodiscs is designed and analyzed by the finite element method(FEM). The nanoantenna exhibits flexibility in excitation and manipulation of the anapole mode through the strong coupling between the metal and dielectrics, consequently improving the near-field enhancement at the gap. By systematically optimizing the structural parameters, the electric field enhancement factors at wavelengths corresponding to the anapole modes(AM1 and AM2) can be increased to 518 and 1482, respectively. Moreover, the nanoantenna delivers great performance in optical sensing such as a sensitivity of 550 nm/RIU. The results provide guidance and insights into enhancing the coupling between metals and dielectrics for applications such as surface-enhanced Raman scattering and optical sensing.

关键词： light-matter interaction metal-dielectric nanoantenna anapole mode electric field enhancement optical sensing

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Facile growth of a heteroepitaxial layer on perovskite oxide surfaces for active and durable fuel cell cathodes

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Journal of Energy Chemistry 2025年第4期103卷 1-8页

作者： Shengli Pang Yifan Song Ting Fang Xudong He Jiaxiang Qiu Shuai Ma Yaozheng Qian Gongmei Yang Hongping Li Yangyang Wan Chonglin Chen Institute for Advanced Materials School of Materials Science and EngineeringJiangsu UniversityZhenjiang 212013JiangsuChina Department of Physics and Astronomy University of Texas at San AntonioSan Antonio 78249TXUSA

Polycrystalline perovskite oxide particles are promising candidates for cathode materials in solid oxide fuel ***,their limited activity and stability pose significant challenges for practical *** this study,we demonstrate a novel approach to achieve both high activity and durability in a PrBaCo_(2)O_(5+δ) catalyst through a simple epitaxial layer growth *** found that an amorphous precursor of the highly durable catalyst SmBa_(0.5)Ca_(0.5)CoCuO_(5+δ) can spontaneously adhere to the surface of PrBaCo_(2)O_(5+δ) *** heat treatment,it grows along the perovskite lattice,forming a heteroepitaxial layer with just a few atomic layers *** heterostructure enhances the operational stability of PrBaCo_(2)O_(5+δ) transforming a 78% decrease over 100 h into a 7% *** 100 h,the power output density of the cell with the modified sample is more than 500% higher than that of unmodified PrBaCo_(2)O_(5+δ.)This work presents a new strategy for fabricating heteroepitaxial layers on polycrystalline ceramic catalysts and introduces a pioneering approach for developing high-performance oxygen reduction catalysts and related materials.

关键词： Solid oxide fuel cell Cathode material Perovskite oxide Oxygen reduction reaction Surface chemistry Electrocatalyst

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