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Effect of surface steps on chemical ordering in the subsurface of Cu(Au) solid solutions

Physical Review B 2021年第3期103卷 035401-035401页

作者： Kuo Liu Siming Zhang Dongxiang Wu Langli Luo Xianhu Sun Xiaobo Chen Dmitri Zakharov Shaobo Cheng Yimei Zhu Judith C. Yang Guofeng Wang Guangwen Zhou Department of Mechanical Engineering and Materials Science and Engineering Program State University of New York Binghamton New York 13902 USA Department of Mechanical Engineering and Materials Science University of Pittsburgh Pittsburgh Pennsylvania 15261 USA Center for Functional Nanomaterials Brookhaven National Laboratory Upton New York 11973 USA Department of Condensed Matter Physics and Materials Science Brookhaven National Laboratory Upton New York 11973 USA Department of Chemical and Petroleum Engineering University of Pittsburgh Pittsburgh Pennsylvania 15261 USA

Atomic steps are typically assumed to only influence surface phenomena of solids. In contrast, here we show, using in situ atomic-resolution electron microscopy observations and atomistic modeling, the pronounced effect from surface steps in inducing compositional and structural evolution in the subsurface of a Cu(Au) solid solution. We find that Au surface segregation results in a stacked sequence of Cu-Au ordered phases in the subsurface. The presence of a monatomic step at the surface induces the formation of an antiphase boundary that extends from the surface step to deeper layers by maintaining the same composition profile associated with each terrace. The bunching of surface steps induces chemical disordering of the Cu-Au ordered phases in the subsurface region of the bunched steps. These results demonstrate the instant propagation of surface dynamics of atomic steps into the subsurface region and can find broader applicability in utilizing surface defects to tune the composition and structure in the subsurface of alloys.

关键词： Structural properties Surface & interfacial phenomena Alloys Density functional theory Electron microscopy

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Piezo-Flexocatalysis of Single-Atom Pt-Loaded Graphitic Carbon Nitride

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Small Methods 2024年第7期8卷 e2301287页

作者： Wang, Yu Teng Lin, Hsun-Yen Chen, Yu-Ching Lin, Yan-Gu Wu, Jyh Ming Department of Materials Science and Engineering National Tsing Hua University 101 Section 2 Kuang Fu Road Hsinchu300 Taiwan Program in Prospective Functional Materials Industry National Tsing Hua University 101 Section 2 Kuang Fu Road Hsinchu300 Taiwan National Synchrotron Radiation Research Center 101 Hsin-Ann Road Hsinchu Science Park Hsinchu300092 Taiwan High Entropy Materials Center National Tsing Hua University 101 Section 2 Kuang Fu Road Hsinchu300 Taiwan

This study develops a single-atom Pt-loaded graphitic carbon nitride (SA-Pt/CN) and evaluates its piezo-flexocatalytic properties by conducting a hydrogen evolution reaction (HER) and Rhodamine B (RB) dye degradation test under ultrasonic vibration in the dark. SA-Pt/CN has a hydrogen gas yield of 1283.8 µmol g−1 h−1, which is 23.3 times higher than that of pristine g-C3N4. Moreover, SA-Pt/CN enhances the dye degradation reaction rate by ≈2.3 times compared with the pristine sample. SA-Pt/CN exhibits lattice distortion and strain gradient enlargement caused by the single atom Pt at the N sites of g-C3N4, which disrupts the symmetric structure and contributes to the enhancement of piezoelectric and flexoelectric polarization. As far as it is known, this is the first study to investigate the piezo-flexocatalytic reaction of SA-Pt/CN without light irradiation and provides new insights into single-atom piezocatalysts. © 2023 Wiley-VCH GmbH.

关键词： Degradation

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Peroxidase-Like Reactivity at Iron-Chelation Sites in a Mesoporous Synthetic Melanin

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CCS Chemistry 2021年第3期3卷 1483-1490页

作者： Yijun Xie Kelsey A.Krug Kristine S.Cay Mark Kalaj Naneki C.McCallum Zofia E.Siwicka Zhao Wang Nathan C.Gianneschi Michael D.Burkart Jeffrey D.Rinehart Materials Science and Engineering Program University of CaliforniaSan DiegoLa JollaCA 92093 Department of Chemistry and Biochemistry University of CaliforniaSan DiegoLa JollaCA 92093 Department of Chemistry Northwestern UniversityEvanstonIL 60208 International Institute of Nanotechnology Simpson-Querrey InstituteChemistry of Life Processes InstituteNorthwestern UniversityEvanstonIL 60208 Pritzker School of Molecular Engineering University of ChicagoChicagoIL 60637 Lurie Cancer Center Northwestern UniversityEvanstonIL 60208 Department of Materials Sciences and Engineering Northwestern UniversityEvanstonIL 60208 Department of Biomedical Engineering Northwestern UniversityEvanstonIL 60208

High catalytic activity and substrate specificity make enzymes a rich source of inspiration for catalyst ***-opting the advantages of natural materials while tuning them to a modified form and purpose,however,is not a straightforward synthetic *** of L-3,4-dihydroxyphenylalanine(L-DOPA)results in amorphous polymer nanoparticles that are similar in many ways to natural ***,the authors introduce mesoporosity and iron ion chelation to synthesize a variant of the L-DOPA polymer with high peroxidase-like *** results indicate catalytic reaction with peroxide under mildly acidic conditions(pH 5.4 and 6)with a greater maximum reaction velocity(Vmax)than horseradish peroxidase(HRP)at optimal pH 3.5–*** between Fe(Ⅲ)and Fe(Ⅱ)loading indicates that either can be used as a starting point to trigger reactivity,though Fe(Ⅱ)loading leads to materials with twice the Vmax of the Fe(Ⅲ)-loaded *** lack of catalyst degradation despite the redox changes and presence of radical species is consistent with the robust nature and redox versatility of polydopamine-based materials and demonstrates strong potential as a versatile redox-catalysis platform.

关键词： L-DOPA mesoporosity peroxidase-like reactivity iron ion chelation catalysis

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Raman Linewidth Contributions from Four-Phonon and Electron-Phonon Interactions in Graphene

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Physical Review Letters 2022年第4期128卷 045901-045901页

作者： Zherui Han Xiaolong Yang Sean E. Sullivan Tianli Feng Li Shi Wu Li Xiulin Ruan School of Mechanical Engineering and the Birck Nanotechnology Center Purdue University West Lafayette Indiana 47907-2088 USA Institute for Advanced Study Shenzhen University Shenzhen 518060 China College of Physics and Center of Quantum Materials and Devices Chongqing University Chongqing 401331 China Materials Science and Engineering Program The University of Texas at Austin Austin Texas 78712 USA Department of Mechanical Engineering The University of Utah Salt Lake City Utah 84112 USA

The Raman peak position and linewidth provide insight into phonon anharmonicity and electron-phonon interactions in materials. For monolayer graphene, prior first-principles calculations have yielded decreasing linewidth with increasing temperature, which is opposite to measurement results. Here, we explicitly consider four-phonon anharmonicity, phonon renormalization, and electron-phonon coupling, and find all to be important to successfully explain both the G peak frequency shift and linewidths in our suspended graphene sample over a wide temperature range. Four-phonon scattering contributes a prominent linewidth that increases with temperature, while temperature dependence from electron-phonon interactions is found to be reversed above a doping threshold (ℏωG/2, with ωG being the frequency of the G phonon).

关键词： Lattice dynamics Phonons Graphene First-principles calculations Raman spectroscopy

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A First-Principles and Calphad-Assisted Phase-Field Model for Microstructure Evolution: Application to Mo-V Binary Alloy Systems

SSRN

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SSRN 2023年

作者： Thakur, Abhishek Kumar Kovacevic, Sasa Manga, Venkateswara Rao Deymier, Pierre Alix Muralidharan, Krishna Department of Materials Science and Engineering University of Arizona TucsonAZ85721 United States Department of Civil and Environmental Engineering Imperial College London LondonSW7 2AZ United Kingdom Lunar and Planetary Laboratory University of Arizona TucsonAZ85721 United States Graduate Interdisciplinary Program in Applied Mathematics India

A multiscale computational framework combining the first-principles calculations and the CALPHAD approach with the phase-field method is presented to simulate the microstructure evolution in multicomponent steel alloys. We demonstrate the potential of the framework by predicting the microstructural evolution in elastically periodic arrays of the Mo-V binary sub-system. The framework utilizes the first-principles calculations using special quasi-random structures. Hitherto unavailable thermodynamic and material properties of the alloy are obtained by employing the first-principles calculations and the CALPHAD approach and fed into the phase-field model to predict the microstructure evolution at different temperatures within the miscibility gap region. In addition to the temperature and cooling rates, the model incorporates the role of mechanical fields in decomposition kinetics in the Mo-V binary alloy system. Regimes for temperatures and cooling rates at which spinodal decomposition occurs are identified. Applying external loading leads to directional phase separation in the Mo-V binary system. The elastic inhomogeneity in terms of material properties between the two phases initiates the directional alignment while eigenstrains and applied external loading control the degree of alignment. The framework developed is general and extendable to higher multicomponent sub-systems in steel alloys. © 2023, The Authors. All rights reserved.

关键词： Temperature

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Wavelength dependence of laser-induced nanowelded microstructures assembled from metal nanoparticles

arXiv

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arXiv 2023年

作者： Rogers, Ariel Niyonshuti, Isabelle I. Ou, Jun Shrestha, Diksha Chen, Jingyi Wang, Yong Department of Physics University of Arkansas FayettevilleAR72701 United States Department of Chemistry and Biochemistry University of Arkansas FayettevilleAR72701 United States School of Engineering California State Polytechnic University Humboldt ArcataCA95521 United States Mechanical Engineering Program California State Polytechnic University Humboldt ArcataCA95521 United States Cell and Molecular Graduate Program University of Arkansas FayettevilleAR72701 United States Materials Science and Engineering Program University of Arkansas FayettevilleAR72701 United States

Light-based nanowelding of metallic nanoparticles is of particular interest because it provides convenient and controlled means for the conversion of nanoparticles into microstructures and fabrication of nanodevices. Here, we demonstrated the wavelength dependence of laser-induced nanowelded shapes of silver nanoparticles (AgNPs). We observed that the nanowelded microstructures illuminated by the 405 nm laser only were more branched than those formed with illumination of both the 405 nm and 532 nm lasers. We quantified this observation by several compactness descriptors and examined the dependence of the power of the 532 nm laser. More importantly, to understand the experimental observations, we formulated and tested a hypothesis by calculating the wavelength-dependent electric field enhancement due to surface plasmon resonance of the AgNPs and nanowelded microstructures when illuminated with lights at the two wavelengths. Based on the different patterns of "hot spots" for welding AgNPs from these calculations, numerical simulations successfully "reproduced" the different shapes of nanowelded microstructures, supporting our hypothesis. This work suggests the possibility of light-based controlling the shapes of laser-induced nanowelded microstructures of metallic nanoparticles. This work is expected to facilitate the development of better nanowelding strategies of metallic nanoparticles for broader applications. Copyright © 2023, The Authors. All rights reserved.

关键词： Surface plasmon resonance

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Elucidating Dynamic Conductive State Changes in Amorphous Lithium Lanthanum Titanate for Resistive Switching Devices

arXiv

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arXiv 2023年

作者： Shimizu, Ryosuke Cheng, Diyi Zhu, Guomin Han, Bing Marchese, Thomas S. Burger, Randall Xu, Mingjie Pan, Xiaoqing Zhang, Minghao Meng, Ying Shirley Department of NanoEngineering University of California San Diego La Jolla CA United States Materials Science and Engineering Program University of California San Diego La Jolla CA United States Pritzker school of Molecular Engineering University of Chicago ChicagoIL60637 United States Irvine Materials Research Institute University of California Irvine IrvineCA92697 United States

Exploration of novel resistive switching materials attracts attention to replace conventional Si-based transistor and to achieve neuromorphic computing that can surpass the limit of the current Von-Neumann computing for the time of Internet of Things (IoT). materials priorly used to serve as an electrode or electrolyte in batteries have demonstrated metal-insulator transitions upon an external electrical biasing due to resulting compositional change. This property is desirable for future resistive switching devices. Amorphous lithium lanthanum titanate (a-LLTO) was originally developed as a solid-state electrolyte with relatively high lithium ionic conductivity (~10-3 S/cm) and low electronic conductivity (~10-10 S/cm) among oxide-type solid electrolytes. However, it has been suggested that electric conductivity of a-LLTO changes depending on oxygen content. In this work, the investigation of switching behavior of a-LLTO sandwiched by nickel electrodes was conducted by employing a range of voltage sweep techniques, ultimately establishing a stable and optimal operating condition within the voltage window of -3.5 V to 3.5 V. This voltage range effectively balances the desirable trait of a substantial resistance change by three orders of magnitude with the imperative avoidance of LLTO decomposition. This switching behavior is also confirmed at nanodevice of Ni/LLTO/Ni through in-situ biasing inside focused-ion beam/scanning electron microscope (FIB-SEM). Experiment and computation with different LLTO composition shows that LLTO has two distinct conductivity states due to Ti reduction. The distribution of these two states is discussed using simplified binary model, implying the conductive filament growth during low resistance state. Consequently, our study deepens understanding of LLTO electronic properties and encourages the interdisciplinary application of battery materials for resistive switching devices. © 2023, CC BY.

关键词： Electric conductivity

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On the second law of thermodynamics: a global flow spontaneously induced by a locally nonchaotic energy barrier

arXiv

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arXiv 2022年

作者： Qiao, Yu Shang, Zhaoru Program of Materials Science and Engineering University of California La Jolla San DiegoCA92093 United States Department of Structural Engineering University of California La Jolla San DiegoCA92093-0085 United States

People are well aware that, inherently, certain small-scale nonchaotic particle movements are not governed by thermodynamics. Usually, such phenomena are studied by kinetic theory and their energy properties are considered "trivial". In current research, we show that, beyond the boundary of the second law of thermodynamics where Boltzmann’s H-theorem does not apply, there are also large-sized systems of nontrivial energy properties: when the system is isolated, entropy can decrease;from a single thermal reservoir, the system can absorb heat and produce useful work without any other effect. The key concept is local nonchaoticity, demonstrated by using a narrow energy barrier. The barrier width is much less than the nominal particle mean free path, so that inside the barrier, the particle-particle collisions are sparse and the particle trajectories tend to be locally nonchaotic. Across the barrier, the steady-state particle flux ratio is intrinsically in a non-Boltzmann form. With a step-ramp structure, the nonequilibrium effect spreads to the entire system, and a global flow is generated spontaneously from the random thermal motion. The deviation from thermodynamic equilibrium is steady and significant, and compatible with the basic principle of maximum entropy. These theoretical and numerical analyses may shed light on the fundamentals of thermodynamics and statistical mechanics. © 2022, CC BY.

关键词： Statistical mechanics

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First-Principles Assessment of Chemical Lithiation of Sulfide Electrolytes and its Impact on Their Transport, Electronic and Mechanical Properties

SSRN

引用

SSRN 2022年

作者： Hao, Wei Lee, Myungsuk Hwang, Gyeong S. Materials Science and Engineering Program The University of Texas at Austin AustinTX78712 United States McKetta Department of Chemical Engineering The University of Texas at Austin AustinTX78712 United States SK Innovation Korea Republic of

Sulfide-based solid electrolytes (SEs) have received considerable attention, but their practical application is hindered by the lack of chemical stability. When in contact with Li metal, sulfide SEs may undergo decomposition induced by lithiation, which could be largely responsible for the high interfacial impedance observed between them. While the underlying mechanism is still uncertain, this first-principles study examines the structural evolution of sulfide materials, Li3PS4 and Li10GeP2S12, upon lithiation and its impact on their transport, electronic and mechanical properties. Our calculations demonstrate that the lithiation reaction is thermodynamically favorable until reaching full lithiation in which PS43- and GeS44- tetrahedral anions are completely decomposed to S2-, P3- and Ge4- atomic ions. This process is also found to involve the transition formation of small P(Ge) clusters and more importantly an increase in the relative density which may cause void formation at the Li metal/SE interface. Moreover, our analyses highlight that, even when fully lithiated, the sulfide materials could retain the high Li-ion conductivity as well as the ability to block electron transport. This suggests that the chemical decomposition of sulfide SEs would not be the only factor that is responsible for the increase of interfacial impedance during electrochemical cycling. © 2022, The Authors. All rights reserved.

关键词： Solid electrolytes

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Parity-time symmetry breaking enables swarming motility in Caenorhabditis elegans

arXiv

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arXiv 2024年

作者： Basaran, Mustafa Yüce, Tevfik Can Keçebaş, Ali Altın, Baha Yaman, Yusuf Ilker Demir, Esin Kocabaş, Coşkun Özdemir, Şahin K. Kocabaş, Aşkın Department of Physics Koç University Sarıyer Istanbul34450 Turkey Bio-Medical Sciences and Engineering Program Koç University Sarıyer Istanbul34450 Turkey Sciences and Engineering Program Harvard University CambridgeMA02138 United States Department of Engineering Science and Mechanics The Pennsylvania State University University ParkPA16802 United States Department of Materials University of Manchester ManchesterM13 9PL United Kingdom Koç University Surface Science and Technology Center Koç University Sarıyer Istanbul34450 Turkey Koç University Research Center for Translational Medicine Koç University Sarıyer Istanbul34450 Turkey

Nonreciprocal interactions break action-reaction symmetry in systems of interacting bodies. This process inevitably introduces non-Hermitian dynamics which with its hallmark signature called exceptional points (EPs) has been a subject of intense research across different disciplines ranging from photonics to metamaterials. Whether non-Hermiticity and EPs are a fundamental property of nature and if so, how nature utilizes them to gain competitive advantage have remained largely unanswered. Although biological systems feature many examples of non-reciprocal interactions with the potential to drive non-Hermitian dynamics, these are often theoretically overlooked and not experimentally investigated. Here, we demonstrate in an active matter composed of social animal Caenorhabditis elegans and bacteria, non-Hermitian dynamics, and the emergence of EPs owing to the nonreciprocal nature of oxygen sensing, nonequilibrium interfacial current, and bacterial consumption. We observed that when driven through the EP, the system collectively breaks parity-time (PT) symmetry leading to traveling waves and arrested phase separation. We further find that these features enable the collective ability to localize interfaces between broken and exact PT-phases. Remarkably, this ability provides a strong evolutionary advantage to animals living in soil. Altogether our results provide mechanistic insights into the detailed symmetries controlling the collective response of biological systems;answer a long-standing problem;and give an example of the EP-enabled dynamics in a biological system. © 2024, CC BY.

关键词： Dynamics

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