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Cyclic ferroelectric switching and quantized charge transport in CuInP2S6

Physical Review B 2023年第18期108卷 L180101-L180101页

作者： Daniel Seleznev Sobhit Singh John Bonini Karin M. Rabe David Vanderbilt Department of Physics and Astronomy Center for Materials Theory Rutgers University Piscataway New Jersey 08854 USA Department of Mechanical Engineering University of Rochester Rochester New York 14627 USA Materials Science Program University of Rochester Rochester New York 14627 USA Center for Computational Quantum Physics Flatiron Institute 162 5th Avenue New York New York 10010 USA

The van der Waals layered ferroelectric CuInP2S6 has been found to exhibit a variety of intriguing properties arising from the fact that the Cu ions are unusually mobile in this system. While the polarization switching mechanism is usually understood to arise from Cu ion motion within the monolayers, a second switching path involving Cu motion across the van der Waals gaps has been suggested. In this work, we perform zero-temperature first-principles calculations on such switching paths, focusing on two types that preserve the periodicity of the primitive unit cell: “cooperative” paths preserving the system's glide mirror symmetry, and “sequential” paths in which the two Cu ions in the unit cell move independently of each other. We find that CuInP2S6 features a rich and varied energy landscape, and that sequential paths are clearly favored energetically both for cross-gap and through-layer paths. Importantly, these segments can be assembled to comprise a globally insulating cycle with the out-of-plane polarization evolving by a quantum as the Cu ions shift to neighboring layers. In this sense, we argue that CuInP2S6 embodies the physics of a quantized adiabatic charge pump.

关键词： Electric polarization Electronic structure Ferroelectricity Phonons Structural phase transition

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Polyacrylamide hydrogel containing rice husk ash as internal curing agent in mortar/concrete

引用

Journal of Molecular Liquids 2025年 423卷

作者： de Almeida, Edson Araujo Kruger, Fábio Rodrigo Valderrama, Patrícia da Silva Gonzalez, Regiane Muniz, Edvani Curti Chemistry Postgraduation Program Chemistry Department State University of Maringá – UEM Paraná Maringá87020-90 Brazil Civil Engineering Department Federal University of Technology – Paraná – UTFPR-CM Paraná Campo Mourão87301-899 Brazil Chemistry Department Federal University of Technology – Paraná – UTFPR-CM Paraná Campo Mourão87301-899 Brazil Food Postgraduation Program Federal University of Technology – Paraná – UTFPR-CM PR Campo Mourão87301-899 Brazil Materials Science and Engineering Postgraduation Program Federal University of Technology – Paraná – UTFPR-LD PR Londrina86036-370 Brazil Chemistry Postgraduation Program Chemistry Department Federal University of Piauí – UFPI Piauí Teresina64049-550 Brazil

Internal curing is a process based on the addition of materials that work as water reservoirs in cementitious media. Their function is to minimize the effect of water lost through evaporation and self-desiccation that occurs during curing. Hydrogels are polymeric materials that have the ability of absorbing and retaining water and releasing it in a gradual and sustained way. In this work, polyacrylamide hydrogel containing rice husk ash (PAAm/RHA) was synthesised and applied in mortar and concrete formulations. The aim was to study the influence of this material on the hydration process and on the final properties of such cementitious materials. The results indicated that the addition of as prepared composite hydrogel improved the mechanical strength and reduced shrinkage in the mortar in 23%;however, its application in concrete led to a reduction of 7.1% in the mechanical strength. Despite this, it can be postulated that the developed hydrogel acts satisfactorily for internal curing in cementitious materials. To the best of our knowledge, it is the first time that hydrogel formulation uses rice husk ash (RHA) and crosslinked polyacrylamide to be used as curing agent for mortars and concrete. Beyond the technological use of composite hydrogel as curing agent, the methodology is also interesting because rice husk ash, as by-product from rice agro-industries, was used. So, it should be seen also as a contribution for environment. © 2025 Elsevier B.V.

关键词： Mortar

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Long-Term Stability of NaOCl Passivation on CZTS Crystals Investigated via SEM-EDS

Long-Term Stability of NaOCl Passivation on CZTS Crystals In...

引用

IEEE Symposium on Nuclear science (NSS/MIC)

作者： J. Seo J. Byun K. Kim Y. Kim B. Park Department of Health and Safety Convergence Science Korea University Seoul Republic of Korea Interdisciplinary program in precision public health Korea University Seoul Republic of Korea Department of Materials Science and Engineering Korea University Seoul Republic of Korea School of Health and Environmental Science Korea University Seoul Republic of Korea Marine Radioactivity Monitoring Group Korea University Busan Republic of Korea

ISBN: (数字)9798350388152

ISBN: (纸本)9798350388169

This study investigates the efficient passivation of CdTe-based semiconductor crystals, focusing on the long-term stability and underlying mechanisms of NaOCl passivation. CdZnTeSe crystals were grown, processed, and passivated with NaOCl, and their surface characteristics were studied using SEM-EDS and XPS. The passivation was found to significantly enhance the surface resistance, with a sustained effect for more than 90 s, attributed to the formation of a tellurium oxide layer. The passivation process was further elucidated through detailed morphological and compositional analyses. The NaOCl-passivated crystals exhibited improved electrical and spectroscopic properties in radiation detection, with a prolonged stability of 60-90 days, which are longer compared to other passivants. Additionally, the feasibility of NaOCl passivation on a CdZnTeSe detector was explored, showcasing enhanced resistivity and spectroscopic performance. The study concludes with insights into the potential industrial application of NaOCl passivation for CdTe-based radiation detectors.

关键词： Microwave integrated circuits Semiconductor detectors Surface resistance Radiation detectors Surface morphology Crystals Stability analysis

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Thermally-induced phase transformations of CALF-20: insights into its phase stability and carbon capture properties

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Journal of materials Chemistry A 2025年第24期13卷 18892-18899页

作者： Kang, Dong A. Suphavilai, Navaporn Mohamed, Amro M. O. Economou, Ioannis G. Shetty, Manish Kim, Jinsoo Jeong, Hae-Kwon Artie McFerrin Department of Chemical Engineering Texas A&M University 3122 TAMU College StationTX77843 3122 United States Department of Materials Science and Engineering Texas A&M University 3122 TAMU College StationTX77843 3122 United States Chemical Engineering Program Texas A&M University at Qatar PO Box 23874 Doha Qatar Kyung Hee University 1732 Deogyeong-daero Gyeonggi-do Yongin17104 Korea Republic of

Calgary Framework 20 (CALF-20) has garnered a great deal of attention as a promising adsorbent for CO2 capture applications due to its high CO2 uptake capacity and excellent stability in humid environments. Multiple studies have explored its adsorption properties and separation performance, while a few studies reveal the existence of several phases of CALF-20, including α-, β-, and τ-phases. α-Phase (i.e., referred as CALF-20) is known to transform into β- or τ-phase under humid or thermal conditions, respectively. Computational studies have shown that β-CALF-20 exhibits a higher heat of CO2 adsorption, making it more suitable for CO2 capture compared to α-CALF-20. However, β-CALF-20, transformed from α-CALF-20 under humid conditions, is known to be less stable, thus observed only upon moisture exposure. Here, we demonstrate that β-CALF-20 can be formed solely by thermal treatment of α-CALF-20 and this thermally-derived β-CALF-20 is significantly more stable and can be readily obtained by drying as-synthesized CALF-20 at temperatures above 100 °C. Computational analyses corroborate the experimental results, affirming that the α-to-β phase transformation can be achieved solely through thermal treatment, without the involvement of water, via a modification in the Zn coordination number from 5 to 4. More importantly, this study finds that it is challenging to determine gas adsorption properties of α-CALF-20, as degassing of α-CALF-20 at elevated temperatures under vacuum almost always leads to its transformation into β-CALF-20. The resultant β-phase demonstrates a CO2 uptake of 2.38 mmol g−1 at 0.1 bar and 30 °C, along with a CO2/N2 IAST selectivity of 222 for a 10 : 90 CO2/N2 mixture, which aligns with previous reports. Consequently, these findings imply that previously reported gas adsorption properties, including carbon (CO2) capture capacities, may have been measured on the β-phase of CALF-20, rather than the α-phase. © 2025 The Royal Society of Chemistry.

关键词： Metastable phases

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Single-peak and narrow-band mid-infrared thermal emitters driven by mirror-coupled plasmonic quasi-BIC metasurfaces

arXiv

引用

arXiv 2023年

作者： Yang, Sen He, Mingze Hong, Chuchuan Nordlander, Josh Maria, Jon-Paul Caldwell, Joshua D. Ndukaife, Justus C. Department of Electrical and Computer Engineering Vanderbilt University NashvilleTN37235 United States Department of Mechanical Engineering Vanderbilt University NashvilleTN37235 United States Interdisciplinary Materials Science Program Vanderbilt University NashvilleTN37240 United States Department of Materials Science and Engineering The Pennsylvania State University University ParkPA16802 United States Sensorium Technological Labs 6714 Duquaine Ct NashvilleTN37205 United States

Wavelength-selective thermal emitters (WS-EMs) hold considerable appeal due to the scarcity of cost-effective, narrow-band sources in the mid-to-long-wave infrared spectrum. WS-EMs achieved via dielectric materials typically exhibit thermal emission peaks with high quality factors (Q factors), but their optical responses are prone to temperature fluctuations. Metallic EMs, on the other hand, show negligible drifts with temperature changes, but their Q factors usually hover around 10. In this study, we introduce and experimentally verify a novel EM grounded in plasmonic quasi-bound states in the continuum (BICs) within a mirror-coupled system. Our design numerically delivers an ultra-narrowband single peak with a Q factor of approximately 64, and near-unity absorptance that can be freely tuned within an expansive band of more than 10 μm. By introducing air slots symmetrically, the Q factor can be further augmented to around 100. Multipolar analysis and phase diagrams are presented to elucidate the operational principle. Importantly, our infrared spectral measurements affirm the remarkable resilience of our designs’ resonance frequency in the face of temperature fluctuations over 300℃. Additionally, we develop an effective impedance model based on the optical nanoantenna theory to understand how further tuning of the emission properties is achieved through precise engineering of the slot. This research thus heralds the potential of applying plasmonic quasi-BICs in designing ultra-narrowband, temperature-stable thermal emitters in mid-infrared. Moreover, such a concept may be adaptable to other frequency ranges, such as near-infrared, Terahertz, and Gigahertz. Copyright © 2023, The Authors. All rights reserved.

关键词： Mirrors

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Improving iPSC Differentiation Using a Nanodot Platform

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ACS Applied materials and Interfaces 2024年第28期16卷 36030-36046页

作者： Chiew, Men Yee Wang, Erick Lan, Kuan-Chun Lin, Yan-Ren Hsueh, Yu-Huan Tu, Yuan-Kun Liu, Chu-Feng Chen, Po-Chun Lu, Huai-En Chen, Wen Liang Center for Regenerative Medicine and Cellular Therapy National Yang Ming Chiao Tung University Hsinchu300 Taiwan Department of Biological Science and Technology National Yang Ming Chiao Tung University Hsinchu300 Taiwan College of Biological Science and Technology Industrial Ph. D. Program National Yang Ming Chiao Tung University Hsinchu300 Taiwan Kyoto University Kyoto606-8397 Japan Department of Emergency and Critical Care Medicine Changhua Christian Hospital Changhua500 Taiwan Department of Post Baccalaureate Medicine College of Medicine National Chung Hsing University Taichung402 Taiwan School of Medicine Kaohsiung Medical University Kaohsiung807 Taiwan School of Medicine Chung Shan Medical University Taichung402 Taiwan College of Biological Science and Technology National Yang Ming Chiao Tung University Hsinchu300 Taiwan Department of Orthopedic Surgery E-Da Hospital I-Shou University Kaohsiung824 Taiwan Emergency Medicine Department Kaohsiung Chang Gung Memorial Hospital Kaohsiung833 Taiwan Ph. D. Degree Program of Biomedical Science and Engineering National Yang Ming Chiao Tung University Hsinchu300 Taiwan Institute of Materials Science and Engineering National Taipei University of Technology Taipei106 Taiwan Institute of Biochemistry and Molecular Biology National Yang Ming Chiao Tung University Hsinchu300 Taiwan Bioresource Collection and Research Center Food Industry Research and Development Institute Hsinchu City300 Taiwan

Differentiation of induced pluripotent stem cells (iPSCs) is an extremely complex process that has proven difficult to study. In this research, we utilized nanotopography to elucidate details regarding iPSC differentiation by developing a nanodot platform consisting of nanodot arrays of increasing diameter. Subjecting iPSCs cultured on the nanodot platform to a cardiomyocyte (CM) differentiation protocol revealed several significant gene expression profiles that were associated with poor differentiation. The observed expression trends were used to select existing small-molecule drugs capable of modulating differentiation efficiency. BRD K98 was repurposed to inhibit CM differentiation, while iPSCs treated with NSC-663284, carmofur, and KPT-330 all exhibited significant increases in not only CM marker expression but also spontaneous beating, suggesting improved CM differentiation. In addition, quantitative polymerase chain reaction was performed to determine the gene regulation responsible for modulating differentiation efficiency. Multiple genes involved in extracellular matrix remodeling were correlated with a CM differentiation efficiency, while genes involved in the cell cycle exhibited contrasting expression trends that warrant further studies. The results suggest that expression profiles determined via short time-series expression miner analysis of nanodot-cultured iPSC differentiation can not only reveal drugs capable of enhancing differentiation efficiency but also highlight crucial sets of genes related to processes such as extracellular matrix remodeling and the cell cycle that can be targeted for further investigation. Our findings confirm that the nanodot platform can be used to reveal complex mechanisms behind iPSC differentiation and could be an indispensable tool for optimizing iPSC technology for clinical applications. © 2024 The Authors. Published by American Chemical Society.

关键词： Efficiency

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Revolutionary Energy Harvesting: Gravity-Driven Piezocatalysts for Sustainable Hydrogen Production in MoS2@Mo2CTx Systems

引用

Advanced Energy materials 2024年第39期14卷

作者： Lin, Hsun-Yen Wu, Jyh Ming Department of Materials Science and Engineering National Tsing Hua University 101 Section 2 Kuang Fu Road Hsinchu300 Taiwan Ph.D Program in Prospective Functional Materials Industry National Tsing Hua University 101 Section 2 Kuang Fu Road Hsinchu300 Taiwan High Entropy Materials Center National Tsing Hua University 101 Section 2 Kuang Fu Road Hsinchu300 Taiwan

Hydrogen (H2) is mainly produced using steam methane reforming, electrolysis, and gasification, which require external energy and special catalysts. A new catalyst by combining MoS2 nanoflowers (NFs) with metal carbide/nitride nanosheets (Mo2CTx MXene) to create a nanosheet bending moment. The MoS2@Mo2CTx heterostructures achieve a production rate of 1164.8 µmol g−1 h−1 under an application of mechanical force, 4.01 and 3.06 times higher than Mo2CTx and MoS2 alone, due to enhanced charge transfer from MoS2's piezoelectricity and Mo2CTx's conductivity. This study introduces a pioneering methodology that harnesses gravitational energy as a continuous mechanical force, simulated using a peristaltic pump, to drive the piezocatalytic hydrogen evolution reaction (HER), achieving a notable hydrogen production rate of 454.1 µmol g−1 over 24 hours and demonstrating a sustained capability for hydrogen generation. The theoretical calculation results validate the piezoelectric potential in water-flow-pressure triggered HER systems. The piezocatalytic HER system, assuming powered by the Hoover Dam, will produce 290.9 kmoles of hydrogen per ton daily, equivalent to utilizing 19 150 kWh of energy in the electrocatalytic system. The simulated gravity-driven water flow using MoS2@Mo2CTx piezocatalysts for H2 generation demonstrates superior efficiency by eliminating common thermal energy conversion losses, marking a significant breakthrough in sustainable hydrogen production technologies. © 2024 Wiley-VCH GmbH.

关键词： Molybdenum compounds

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Effect of flow velocity on corrosion behaviour of spark plasma sintered Fe-Cr-Ni reinforced with TiN in 3.5 wt% NaCl

引用

materials Today: Proceedings 2021年 38卷 688-695页

作者： O.O. Ige S.R. Oke O.E. Falodun S. Aribo K.M. Oluwasegun O.O. Ajibola J.O. Olawale A. Ogunbadejo O.T. Olalemi P.A. Olubambi Center for NanoEngineering and Tribocorrosion School of Mining Metallurgy and Chemical Engineering University of Johannesburg Doornfontein Campus Johannesburg 2028 South Africa Department of Materials Science and Engineering Obafemi Awolowo University Ile – Ife 220282 Nigeria Department of Metallurgical and Materials Engineering Federal University of Technology Akure 340252 Nigeria Department of Metallurgical and Materials Engineering Federal University Oye Ekiti 371104 Nigeria

This study investigated the effect of varying flow velocities on the corrosion behavior of titanium nitride reinforced Fe-Cr-Ni (Duplex Stainless Steel – UNS S32205) manufactured by spark plasma sintering. The TiN reinforcement was within the range of 0–8% at an interval of 2%. The spark plasma sintering parameters are sintering temperature (1150 °C), sintering time (10 mins), applied pressure (50 Mpa) and heating rate (100 °C/mins). The sintered samples were subjected to both gravimetric and electrochemical measurement in 3.5 wt% NaCl at a flow velocity of 1.0 m/s and increasing at 0.5 m/s till 2.5 m/s. A field emission scanning electron microscope (FESEM) equipped with energy dispersive x-ray spectrometer (EDS) was employed to carry out the microstructural characterizations of the corroded sintered products. The results showed that increasing the flow velocity decreased the passive current, but leads to more positive corrosion potential of the sintered products. The active-passive behaviour and the role of microstructures on the reinforced sintered composites in 3.5 wt% NaCl are discussed.

关键词： Powders Sintering DSS 2205 Titanium nitride Simulated seawater Flow induced-corrosion

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Synthesis and Characterization of Two-dimensional Cs2AgInCl6 Nanoplates as Building Blocks for Functional Surfaces

arXiv

引用

arXiv 2025年

作者： Khalfin, Sasha Veber, Noam Shaek, Saar Shamaev, Betty Levy, Shai Dror, Shaked Kauffmann, Yaron Khristosov, Maria Koifman Bekenstein, Yehonadav Department of Materials Science and Engineering Technion Israel Institute of Technology Haifa3200003 Israel The Solid-state institute Technion – Israel Institute of Technology Haifa3200003 Israel The Nancy and Stephen Grand Technion Energy Program Technion Israel Institute of Technology Haifa32000 Israel

breaking crystal symmetry is essential for engineering emissive double perovskite metal halides. The goal is to overcome their inherently indirect and disallowed optical transitions. Here we introduce a synthesis for silver - Cs2AgInCl6 two-dimensional hybrid nanoplate products that break the symmetry in two ways, their shape and their heterointerfaces. A comparative study between Cs2AgInCl6 nanocubes and nanoplates is presented to emphasize the difference in optical properties. A modified colloidal synthesis for Cs2AgInCl6 yields high-quality nanoplates with small lateral dimensions very different from the symmetric cubes. Each nanoplate is decorated with metallic silver nanoparticles, with diameters on the scale of the thickness of the perovskite nanoplate, forming significant heterointerfaces that further break symmetry. The Cs2AgInCl6 two-dimensional nanoplates also demonstrate facile transformation into larger crystalline nanosheets once deposited on substrates. We thus highlight those nanoplates as potential building blocks for assemblies of functional surfaces. © 2025, CC BY-NC-ND.

关键词： Perovskite

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Mid-IR Gain of Tensile Germanium Waveguide Lasers with SiNx Stress Liners

Mid-IR Gain of Tensile Germanium Waveguide Lasers with SiNx ...

引用

2021 IEEE Photonics Society Summer Topicals Meeting Series, SUM 2021

作者： Reza, Md Shamim Gulyas, Istvan Wistey, Mark A. Materials Science Engineering and Commercialization Program Texas State University San MarcosTX78666 United States Department of Physics Texas State University San MarcosTX78666 United States

ISBN: (纸本)9781665416009

We used ab-initio and finite element strain modeling to explain high threshold current densities in reported tensile Ge lasers. Anisotropic strains improve carrier confinement but reduces optical confinement, and intervalence band absorption still dominates. Strain anisotropy increases Jth compared with simple slab models. © 2021 IEEE.

关键词： Germanium

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