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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

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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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Monitoring blood pressure through a single hybrid hemodynamic signal with a flexible optoelectronic patch

Device

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Device 2025年

作者： Zhong, Yizhou Zhang, Yongcao Pu, Jing Wustoni, Shofarul Uribe, Johana Lopez-Larrea, Naroa Marks, Adam McCulloch, Iain Mecerreyes, David Baran, Derya Inal, Sahika Organic Bioelectronics Laboratory Biological and Environmental Science and Engineering Division King Abdullah University of Science and Technology (KAUST) Thuwal 23955-6900 Saudi Arabia Materials Science and Engineering Program (MSE) Physical Sciences and Engineering Division (PSE) KAUST Thuwal 23955-6900 Saudi Arabia POLYMAT University of the Basque Country UPV/EHU Avenida Tolosa 72 Guipuzcoa Donostia-San Sebastian 20018 Spain Department of Chemistry University of Oxford Oxford OX1 3TF United Kingdom Andlinger Center for Energy and the Environment and Department of Electrical and Computer Engineering Princeton University Princeton 08544 NJ United States IKERBASQUE Basque Foundation for Science Plaza Euskadi 5 Bilbao 48009 Spain

Hemodynamics, the study of blood flow and circulatory forces, is fundamental for assessing cardiovascular health, disease states, and therapeutic outcomes. Here, we introduce a skin-conformable organic optoelectronic thin-film patch (ePatch) designed to simultaneously capture electrocardiography (ECG) and photoplethysmography (PPG) signals as a single hybrid signal, named the electrocardio-photoplethysmogram (EC-PPG). The ePatch integrates an organic electrochemical transistor (OECT), an organic photodiode, surface-mounted light-emitting diodes, and electrochemical electrodes on a flexible, skin-conforming substrate. By training deep learning models on the hybrid EC-PPG data, we achieved accurate arterial blood pressure estimations, with mean errors of just 1.69 mmHg for systolic and 0.89 mmHg for diastolic blood pressure, outperforming traditional predictions that rely on individual physiological signals as inputs. Our findings underscore the potential of EC-PPG as a compound hemodynamic signal for AI-driven vital sign monitoring and integrated, solution-processable soft electronics for clinical and point-of-care applications. © 2025 The Authors

关键词： DTI-3: Develop electrocardiography electrophysiology flexible electronics OECT OPD organic electrochemical transistor photoplethysmography wearable electronics

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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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Increasing the mobility and power-electronics figure of merit of AlGaN with atomically thin AlN/GaN digital-alloy superlattices

arXiv

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arXiv 2022年

作者： Pant, Nick Lee, Woncheol Sanders, Nocona Kioupakis, Emmanouil Applied Physics Program University of Michigan Ann ArborMI48109 United States Department of Materials Science and Engineering University of Michigan Ann ArborMI48109 United States Department of Electrical Engineering and Computer Science University of Michigan Ann ArborMI48109 United States

Alloy scattering in random AlGaN alloys drastically reduces the electron mobility and therefore the power-electronics figure of merit. As a result, Al compositions greater than 75% are required to obtain even a two-fold increase of the Baliga figure of merit compared to GaN. However, beyond approximately 80% Al composition, donors in AlGaN undergo the DX transition which makes impurity doping increasingly more difficult. Moreover, the contact resistance increases exponentially with increasing Al content, and integration with dielectrics becomes difficult due to the upward shift of the conduction band. Atomically thin superlattices of AlN and GaN, also known as digital alloys, are known to grow experimentally under appropriate growth conditions. These chemically ordered nanostructures could offer significantly enhanced figure of merit compared to their random-alloy counterparts due to the absence of alloy scattering, as well as better integration with contact metals and dielectrics. In this work, we investigate the electronic structure and phonon-limited electron mobility of atomically thin AlN/GaN digital-alloy superlattices using first-principles calculations based on density-functional and many-body perturbation theory. The band gap of the atomically thin superlattices reaches 4.8 eV, and the in-plane (out-of-plane) mobility is 369 (452) cm2 V-1 s-1. Using the modified Baliga figure of merit that accounts for the dopant ionization energy, we demonstrate that atomically thin AlN/GaN superlattices with a monolayer sublattice periodicity have the highest modified Baliga figure of merit among several technologically relevant ultra-wide band-gap materials, including random AlGaN, β-Ga2O3, cBN, and diamond. Copyright © 2022, The Authors. All rights reserved.

关键词： Aluminum gallium nitride

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Data-based Polymer-Unit Fingerprint (PUFp): A Newly Accessible Expression of Polymer Organic Semiconductors for Machine Learning

arXiv

引用

arXiv 2022年

作者： Zhang, Xinyue Wei, Genwang Sheng, Ye Yang, Jiong Ye, Caichao Zhang, Wenqing Department of Physics Guangdong Provincial Key Laboratory of Computational Science and Material Design Southern University of Science and Technology Shenzhen518055 China Academy for Advanced Interdisciplinary Studies Department of Materials Science and Engineering Southern University of Science and Technology Shenzhen518055 China Materials Genome Institute Shanghai University Shanghai200444 China Zhejiang Laboratory Hangzhou311100 China

In the process of finding high-performance organic semiconductors (OSCs), it is of paramount importance in material development to identify important functional units that play key roles in material performance and subsequently establish substructure-property relationships. Herein, we describe a polymer-unit fingerprint (PUFp) generation framework. Machine learning (ML) models can be used to determine structure-mobility relationships by using PUFpinformation as structural input with 678 pieces of collected OSC data. A polymer-unit library consisting of 445 units is constructed, and the key polymer units for the mobility of OSCs are identified. By investigating the combinations of polymer units with mobility performance, a scheme for designing polymer OSC materials by combining ML approaches and PUFpinformation is proposed to not only passively predict OSC mobility but also actively provide structural guidance for new high-mobility OSC material design. The proposed scheme demonstrates the ability to screen new materials through pre-evaluation and classification ML steps and is an alternative methodology for applying ML in new high-mobility OSC discovery. Copyright © 2022, The Authors. All rights reserved.

关键词： Machine learning

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

引用

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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Influence of Temperature and Stress State on the Twip Behavior of 201ln and 316lv Austenitic Stainless Steels

SSRN

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SSRN 2022年

作者： Braga, Diogo Pedrino Corrêa, Leonardo Muthi Sordi, Vitor Luiz Rovere, Carlos Alberto Della Cintho, Osvaldo Mitsuyuki Kliauga, Andrea Madeira Federal University of São Carlos Graduate Program in Materials Science and Engineering São Carlos São Paulo Brazil Federal University of São Carlos Graduate Program in Mechanical Engineering São Carlos São Paulo Brazil Federal University of São Carlos Department of Materials Engineering São Carlos São Paulo Brazil State University of Ponta Grossa Department of Materials Engineering Ponta Grossa Paraná Brazil

The present results analyzed deformation behavior under tension and compression of two different austenitic stainless steels: AISI 201LN, with low nickel content and stabilized with Mn and N;and AISI 316LV, stabilized with Ni and with low content of interstitial atoms. Mechanical tests were performed at 10 -3 s -1 and at temperatures varying from -100 to 600 o C to yield comparable values of the stacking fault energy (SFE). The resulting microstructure was analyzed by X-ray diffraction and EBSD. The stress-strain curves were analyzed using the Kocks-Mecking (K-M) approach. For comparable stacking fault energies, temperature enhances the thermal activation effects that led to lower fraction of mechanical twins in the 201LN compared with the 316LV. The crystallographic re-orientation followed the flow rule irrespective of the temperature and deformation mechanism: tension and compression experiments showed the or orientation with the tension axis, respectively. In tension the dislocation storage and recovery factors of the K-M model were larger than in the compression and the amount of stored dislocations and crystallite size reflect these effects. In the compression, the TWIP effect was reduced for the 316LV and suppressed for the 201LN. © 2022, The Authors. All rights reserved.

关键词： Stacking faults

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Superstructures and magnetic order in heavily Cu-substituted (Fe1−xCux)1+yTe

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Physical Review B 2024年第4期109卷 045142-045142页

作者： Saizheng Cao Xin Ma Dongsheng Yuan Zhen Tao Xiang Chen Yu He Patrick N. Valdivia Shan Wu Hang Su Wei Tian Adam A. Aczel Yaohua Liu Xiaoping Wang Zhijun Xu Huiqiu Yuan Edith Bourret-Courchesne Chao Cao Xingye Lu Robert Birgeneau Yu Song Center for Correlated Matter and School of Physics Zhejiang University Hangzhou 310058 China Materials Science Division Lawrence Berkeley National Lab Berkeley California 94720 USA Research Center for Electronic and Optical Materials National Institute for Materials Science Tsukuba 305-0044 Japan Center for Advanced Quantum Studies and Department of Physics Beijing Normal University Beijing 100875 China Physics Department University of California Berkeley California 94720 USA Department of Applied Physics Yale University New Haven Connecticut 06511 USA Neutron Scattering Division Oak Ridge National Laboratory Oak Ridge Tennessee 37831 USA Second Target Station Oak Ridge National Laboratory Oak Ridge Tennessee 37831 USA NIST Center for Neutron Research National Institute of Standards and Technology Gaithersburg Maryland 20899 USA Department of Materials Science and Engineering University of Maryland College Park Maryland 20742 USA

Most iron-based superconductors exhibit stripe-type magnetism, characterized by the ordering vector Q=(12,12). In contrast, Fe1+yTe, the parent compound of the Fe1+yTe1−xSex superconductors, exhibits double-stripe magnetic order associated with the ordering vector Q=(12,0). Here, we use elastic neutron scattering to investigate heavily Cu-substituted (Fe1−xCux)1+yTe compounds and reveal that (1) for x≳0.4, short-range magnetic order emerges around the stripe-type vector at Q=(12±δ,12±δ,12) with δ≈0.05; (2) the short-range magnetic order is associated with a superstructure modulation at Q=(13,13,12), with the magnetic correlation length shorter than that for the superstructure; and (3) for x≳0.55, we observe an additional intergrown phase with higher Cu content, characterized by a superstructure modulation vector Q=(13,13,0) and magnetic peaks at Q=(23,13,12)/(13,23,12). The positions of superstructure peaks suggest that relative to the tetragonal unit cell of Fe1+yTe, heavy Cu substitution leads to Fe-Cu orderings that expand the unit cell by 2×32 times in the ab plane, corroborated by first-principles calculations that suggest the formation of spin chains and spin ladders. Our findings show that stripe-type magnetism is common in magnetically diluted iron pnictides and chalcogenides, despite the varying associated atomic orderings.

关键词： Magnetic order Structural properties Iron-based superconductors Density functional calculations Neutron scattering

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

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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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