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Toward Perfect Surfaces of Transition Metal Dichalcogenides with Ion Bombardment and Annealing Treatment

ACS Applied materials and Interfaces 2023年第12期15卷 16153-16161页

作者： Chen, Wan-Hsin Kawakami, Naoya Hsueh, Jing-Wen Kuo, Lai-Hsiang Chen, Jiun-Yu Liao, Ting-Wei Kuo, Chia-Nung Lue, Chin-Shan Lai, Yu-Ling Hsu, Yao-Jane Lien, Der-Hsien Hu, Chenming Chou, Jyh-Pin Luo, Meng-Fan Lin, Chun-Liang Department of Electrophysics National Yang Ming Chiao Tung University Hsinchu300 Taiwan Department of Physics National Central University Jhongli320 Taiwan Department of Physics National Cheng Kung University Tainan701 Taiwan Taiwan Consortium of Emergent Crystalline Materials National Science and Technology Council Taipei106 Taiwan Program on Key Materials Academy of Innovative Semiconductor and Sustainable Manufacturing National Cheng Kung University Tainan701 Taiwan Nanoscience Group National Synchrotron Radiation Research Center Hsinchu300 Taiwan Institute of Electronic Engineering National Yang Ming Chiao Tung University Hsinchu300 Taiwan International College of Semiconductor Technology National Yang Ming Chiao Tung University Hsinchu300 Taiwan Department of Physics National Changhua University of Education Changhua500 Taiwan

Layered transition metal dichalcogenides (TMDs) are two-dimensional materials exhibiting a variety of unique features with great potential for electronic and optoelectronic applications. The performance of devices fabricated with mono or few-layer TMD materials, nevertheless, is significantly affected by surface defects in the TMD materials. Recent efforts have been focused on delicate control of growth conditions to reduce the defect density, whereas the preparation of a defect-free surface remains challenging. Here, we show a counterintuitive approach to decrease surface defects on layered TMDs: a two-step process including Ar ion bombardment and subsequent annealing. With this approach, the defects, mainly Te vacancies, on the as-cleaved PtTe2 and PdTe2 surfaces were decreased by more than 99%, giving a defect density 10 cm-2, which cannot be achieved solely with annealing. We also attempt to propose a mechanism behind the processes. © 2023 American Chemical Society.

关键词： Scanning tunneling microscopy

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Exploring the Influence of Temperature on Sodium Titanate Mineral Formation Using X-Ray Diffraction 2

Exploring the Influence of Temperature on Sodium Titanate Mi...

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2nd International Conference on physics and Applied physics, ICP and AP 2023

作者： Noer, Zikri Sihombing, Yuan Alfinsyah Rajagukguk, Juniastel Idamayanti, Dewi Taufik, Dede Amri, Fauzan Agus, Muhammad Abduh Akram Department of Physics Faculty of Vocational Universitas Sumatera Utara Jl. Bioteknologi No. 2 Sumatera Utara Medan20155 Indonesia Department of Physics Faculty of Mathematics and Natural Sciences Universitas Sumatera Utara Jl. Bioteknologi No. 1 Sumatera Utara Medan20155 Indonesia Department of Physics Faculty of Mathematics and Natural Sciences Universitas Negeri Medan Medan Indonesia Advance Materials Engineering Study Program Department of Foundry Engineering Politeknik Manufaktur Bandung Bandung40135 Indonesia Center for Ceramics Ministry of Industry of Indonesia Jl. Achmad Yani No. 392 Jawa Barat Bandung40272 Indonesia Instrumentation and Control Engineering Technology Politeknik Negeri Indramayu Jawa Barat Indonesia

In this study, an inquiry was conducted to examine the influence of temperature on the crystal structure of sodium titanate (NTO). NTO was synthesized using NaCl, TTIP, citric acid, and ethylene glycol as precursors. The NaCl-citric acid precursor was dissolved in purified water, while the titanium precursor was prepared by blending ethylene glycol with TTIP. After vigorous stirring, the precursor solution was placed in a Teflon-coated stainless steel autoclave, subjected to preheating, and subsequently dried to form a gel. The gel underwent calcination at temperatures ranging from 800 to 1000 °C for 3 hours each. The resulting samples were rinsed with deionized water and dried to eliminate residual NaCl. Based on the results of XRD characterization, the NaTi4O8 phase experienced decomposition into rutile form when the calcination temperature was increased from 800-1000 °C and began to be identified as a rutile phase at a temperature of 900 °C. © Published under licence by IOP Publishing Ltd.

关键词： Sodium chloride

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Thermal energy dependent transient permittivity of epsilon-near-zero material

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Science China(physics,Mechanics & Astronomy) 2022年第8期65卷 96-101页

作者： Heng Wang Lixun Sun Kang Du Wending Zhang SooJin Chua Guixin Li Ting Mei MOE Key Laboratory of Material Physics and Chemistry under Extraordinary Conditions and Shaanxi Key Laboratory of Optical Information TechnologySchool of Physical Science and TechnologyNorthwestern Polytechnical UniversityXi’an710129China Department of Materials Science and Engineering Southern University of Science and TechnologyShenzhen518055China Shenzhen Institute for Quantum Science and Engineering Southern University of Science and TechnologyShenzhen518055China Department of Electrical and Computer Engineering National University of SingaporeSingapore117583Singapore LEES Program Singapore-MIT Alliance for Research&Technology(SMART)Singapore138602Singapore

Transparent conductive oxides exhibit attractive optical nonlinearity with ultrafast response and giant refractive index change near the epsilon-near-zero(ENZ) wavelength, originating from the intraband dynamics of conduction electrons. The optical nonlinearity of ENZ materials has been explained by using the overall-effective-mass and the overall-scattering-time of electrons in the extended Drude model. However, their response to optical excitation is yet the last building block to complete the theory. In this paper, the concept of thermal energy is theoretically proposed to account for the total energy of conduction electrons exceeding their thermal equilibrium value. The time-varying thermal energy is adopted to describe the transient optical response of indium-tin-oxide(ITO), a typical ENZ material. A spectrally-resolved femtosecond pump-probe experiment was conducted to verify our theory. By correlating the thermal energy with the pumping density, both the giant change and the transient response of the permittivity of ITO can be predicted. The results in this work provide a new methodology to describe the transient permittivities of ENZ materials, which will benefit the design of ENZ-based nonlinear photonic devices.

关键词： epsilon-near-zero optical nonlinearity transient response thermal energy hot electron indium tin oxide

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Connecting polymer collapse and the onset of jamming

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Physical Review E 2024年第3期109卷 034406-034406页

作者： Alex T. Grigas Aliza Fisher Mark D. Shattuck Corey S. O'Hern Graduate Program in Computational Biology and Bioinformatics Yale University New Haven Connecticut 06520 USA Integrated Graduate Program in Physical and Engineering Biology Yale University New Haven Connecticut 06520 USA Department of Mechanical Engineering and Materials Science Yale University New Haven Connecticut 06520 USA Benjamin Levich Institute and Physics Department The City College of New York New York New York 10031 USA Department of Physics Yale University New Haven Connecticut 06520 USA Department of Applied Physics Yale University New Haven Connecticut 06520 USA

Previous studies have shown that the interiors of proteins are densely packed, reaching packing fractions that are as large as those found for static packings of individual amino-acid-shaped particles. How can the interiors of proteins take on such high packing fractions given that amino acids are connected by peptide bonds and many amino acids are hydrophobic with attractive interactions? We investigate this question by comparing the structural and mechanical properties of collapsed attractive disk-shaped bead-spring polymers to those of three reference systems: static packings of repulsive disks, of attractive disks, and of repulsive disk-shaped bead-spring polymers. We show that the attractive systems quenched to temperatures below the glass transition T≪Tg and static packings of both repulsive disks and bead-spring polymers possess similar interior packing fractions. Previous studies have shown that static packings of repulsive disks are isostatic at jamming onset, i.e., the number of interparticle contacts Nc matches the number of degrees of freedom, which strongly influences their mechanical properties. We find that repulsive polymer packings are hypostatic at jamming onset (i.e., with fewer contacts than degrees of freedom) but are effectively isostatic when including stabilizing quartic modes, which give rise to quartic scaling of the potential energy with displacements along these modes. While attractive disk and polymer packings are often considered hyperstatic with excess contacts over the isostatic number, we identify a definition for interparticle contacts for which they can also be considered as effectively isostatic. As a result, we show that the mechanical properties (e.g., scaling of the potential energy with excess contact number and low-frequency contribution to the density of vibrational modes) of weakly attractive disk and polymer packings are similar to those of isostatic repulsive disk and polymer packings. Our results demonstrate that static

关键词： Jamming Polymer folding Protein folding Single polymer chains

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Antiferromagnetic V2O3 based exchange coupling

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Physical Review materials 2024年第5期8卷 054407-054407页

作者： Ralph el Hage Tianxing D. Wang Junjie Li Ali C. Basaran Felipe Torres Ivan K. Schuller Department of Physics and Center for Advanced Nanoscience University of California San Diego La Jolla California 92093 USA Materials Science and Engineering Program University of California San Diego La Jolla California 92093 USA Department of Physics Universidad de Chile Santiago 7800024 Chile Center for the Development of Nanoscience and Nanotechnology CEDENNA Santiago 9170124 Chile

Vanadium sesquioxide (V2O3) is a strongly correlated electronic material that famously undergoes a triple coupled first-order transition where it transitions from a paramagnetic metal with a rhombohedral structure at high temperature to an antiferromagnetic insulator with a monoclinic structure. While several studies have used one of both electronic and structural transitions to control the properties of a heterostructure, evidence of magnetic coupling has notoriously yet to be found. In this paper, we report on a robust magnetic coupling between the antiferromagnetic (AFM) V2O3 and ferromagnetic (FM) Permalloy (Py) layers that results in a significant exchange bias and strain-induced coercivity enhancement. We provide a temperature and angle-dependent study of magnetic properties, which clearly indicates exchange bias at the AFM/FM interface that appears at the onset of the metal-insulator transition. The magnitude of the exchange bias is strongest when the field is applied along the [001] V2O3 crystallographic orientation which corresponds to an AFM spin configuration on the [110] surface. This opens the door to designing and implementing novel functionalities in transition metal oxide-based computing using the connection between magnetism and the metal-insulator transition.

关键词： First order phase transitions Magnetic anisotropy Magnetic coupling Magnetism Magnetization dynamics Antiferromagnets Magnetic thin films Thin films Kerr effect Magnetization measurements X-ray reflectivity

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Large negative magnetoresistance in the off-stoichiometric topological semimetal PrSbxTe2−x

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Physical Review B 2025年第2期111卷 024421-024421页

作者： Gokul Acharya Krishna Pandey M. M. Sharma Jian Wang Santosh Karki Chhetri Md Rafique Un Nabi Dinesh Upreti Rabindra Basnet Josh Sakon Department of Physics University of Arkansas Fayetteville Arkansas 72701 USA Materials Science and Engineering Program Institute for Nanoscience and Engineering University of Arkansas Fayetteville Arkansas 72701 USA Department of Chemistry and Biochemistry Wichita State University Wichita Kansas 67260 USA Department of Chemistry & Physics University of Arkansas at Pine Bluff Pine Bluff Arkansas 71603 USA Department of Chemistry and Biochemistry University of Arkansas Fayetteville Arkansas 72701 USA

Magnetic topological materials LnSbTe (Ln = lanthanide) have attracted intensive attention because of the presence of interplay between magnetism, topological, and electron correlations depending on the choices of magnetic Ln elements. Varying Sb and Te composition is an efficient approach to control structural, magnetic, and electronic properties. Here, we report on the composition-dependent properties in PrSbxTe2−x. We identified the tetragonal-to-orthorhombic structure transitions in this material system and very large negative magnetoresistance in the x=0.3 composition, which might be ascribed to the coupling between magnetism and transport. Such unusual magnetotransport enables PrSbxTe2−x topological materials as a promising platform for device applications.

关键词： Magnetoresistance

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Reliability of Deployed Organic Photovoltaic Modules

Reliability of Deployed Organic Photovoltaic Modules

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IEEE Conference Photovoltaic Specialists (PVSC)

作者： Hafiz K. M. Sheriff Yongxi Li Sammy Saad Stephen R. Forrest Applied Physics Program University of Michigan Ann Arbor Michigan USA Department of Electrical Engineering University of Michigan Ann Arbor Michigan USA Department of Physics University of Michigan Ann Arbor Michigan USA Department of Materials Science and Engineering University of Michigan Ann Arbor Michigan USA

ISBN: (数字)9781665464260

ISBN: (纸本)9781665475822

The commercial future of organic photovoltaics (OPVs) relies on their efficiency and reliability. Recent progress in the field has ensured the achievement of device efficiency comparable to those of commercial silicon-based photovoltaics (Si-PVs) [1]. In pursuit of reliable devices, recent works have demonstrated the intrinsic stability of both small-molecule, vacuum deposited [2] and non-fullerene acceptor (NFA) – polymer-based devices [3] under controlled laboratory conditions. The final step for outdoor deployment is therefore a demonstration of the reliability of large area OPV modules in the field, subjected to fluctuating environmental conditions such as humidity, temperature, rainfall, snow, and solar intensity. In this work, we develop a customized test facility intended for the study of the reliability of large area OPV modules deployed in outdoor environments. The facility is designed for automated in-situ measurements calibrated to 1 sun solar intensity, AM 1.5 G illumination. Initial data show the modules retain more than 95% of their initial performance for 150 h when exposed to varying solar intensities, temperature fluctuations of -2°C to 10°C, and relative humidity as high as 90%. The only significant extrinsic challenge to device stability observed was the ingress of water into the package. This is mitigated by improved packaging which utilizes polyisobutylene (PIB) encapsulation and a customized insulated glass unit (IGU).

关键词： Temperature measurement Temperature distribution Test facilities Rain Snow Humidity Solar panels Polymers Sun Thermal stability

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Annular Dark Field Imaging with Variable Angle for Improving STEM Tomography of Biological Samples

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Microscopy and microanalysis : the official journal of Microscopy Society of America, Microbeam Analysis Society, Microscopical Society of Canada 2023年第1期29卷 945-947页

作者： Li, Wing Shun Roth, Eric Bleher, Reiner Backman, Vadim Dravid, Vinayak P. Applied Physics Program Northwestern University Evanston IL United States Department of Materials Sciences and Engineering Northwestern University Evanston IL United States Northwestern University Atomic and Nanoscale Characterization Experimental (NUANCE) Center Northwestern University Evanston IL United States Department of Biomedical Engineering Northwestern University Evanston IL United States International Institute of Nanotechnology Northwestern University Evanston IL United States

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Understanding and Tuning Magnetism in van der Waals-type Metal Thiophosphates

arXiv

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arXiv 2024年

作者： Basnet, Rabindra Hu, Jin Department of Chemistry & Physics University of Arkansas at Pine Bluff Pine BluffAR71603 United States Department of Physics University of Arkansas FayettevilleAR72701 United States Materials Science and Engineering Program Institute for Nanoscience and Engineering University of Arkansas FayettevilleAR72701 United States

Over the past two decades, significant progress in two-dimensional (2D) materials has invigorated research in condensed matter and material physics in low dimensions. While traditionally studied in three-dimensional systems, magnetism has now been extended to the 2D realm. Recent breakthroughs in 2D magnetism have captured substantial interest from the scientific community, owing to the stable magnetic order achievable in atomically thin layers of the van der Waals (vdW)-type layered magnetic materials. These advances offer an exciting platform for investigating related phenomena in low dimensions and hold promise for spintronic applications. Consequently, vdW magnetic materials with tunable magnetism have attracted significant attention. Specifically, antiferromagnetic metal thiophosphates MPX3 (M = transition metal, P = phosphorus, X = chalcogen) have been investigated extensively. These materials exhibit long-range magnetic orders spanning from bulk to the 2D limit. The magnetism in MPX3 arises from localized moments associated with transition metal ions, making it tunable via substitutions and intercalations. In this review, we focus on such tuning by providing a comprehensive summary of various metal- and chalcogen-substitution and intercalation studies, along with the mechanism of magnetism modulation, and a perspective on the development of this emergent material family. © 2024, CC0.

关键词： Van der Waals forces

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Three-dimensional construction of hyperuniform, nonhyperuniform, and antihyperuniform disordered heterogeneous materials and their transport properties via spectral density functions

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Physical Review E 2025年第3期111卷 035310-035310页

作者： Wenlong Shi Yang Jiao Salvatore Torquato Materials Science and Engineering Arizona State University Tempe Arizona 85287 USA Department of Physics Arizona State University Tempe Arizona 85287 USA Department of Chemistry Princeton University Princeton New Jersey 08544 USA Department of Physics Princeton University Princeton New Jersey 08544 USA Princeton Institute of Materials Princeton University Princeton New Jersey 08544 USA Program in Applied and Computational Mathematics Princeton University Princeton New Jersey 08544 USA

Rigorous theories connecting physical properties of a heterogeneous material to its microstructure offer a promising avenue to guide the computational material design and optimization. The spectral density function χ̃V(k), which can be obtained experimentally from scattering data, enables accurate determination of various transport and wave propagation characteristics, including the time-dependent diffusion spreadability S(t) and effective dynamic dielectric constant εe for electromagnetic wave propagation. Moreover, χ̃V(k) determines rigorous upper bounds on the fluid permeability K. Given the importance of χ̃V(k), we present here an efficient Fourier-space based computational framework to construct three-dimensional (3D) statistically isotropic two-phase heterogeneous materials corresponding to targeted spectral density functions. In particular, we employ a variety of analytical functional forms for χ̃V(k) that satisfy all known necessary conditions to construct disordered stealthy hyperuniform, standard hyperuniform, nonhyperuniform, and antihyperuniform two-phase heterogeneous material systems at varying phase volume fractions. We show that by tuning the correlations in the system across length scales via the targeted functions, one can generate a rich spectrum of distinct structures within each of the above classes of materials. Importantly, we present the first realization of antihyperuniform two-phase heterogeneous materials in 3D, which are characterized by autocovariance function χV(r) with a power-law tail, resulting in microstructures that contain clusters of dramatically different sizes and morphologies. We also determine the diffusion spreadability S(t) and estimate the fluid permeability K associated with all of the constructed materials directly from the corresponding spectral densities. Although it is well established that the long-time asymptotic scaling behavior of S(t) only depends on the functional form of χ̃V(k), with the stealthy hyperuniform a

关键词： Spectral density

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