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Microscopic picture of paraelectric perovskites from structural prototypes

Physical Review Research 2022年第1期4卷 L012042-L012042页

作者： Michele Kotiuga Samed Halilov Boris Kozinsky Marco Fornari Nicola Marzari Giovanni Pizzi Theory and Simulation of Materials (THEOS) National Centre for Computational Design and Discovery of Novel Materials (MARVEL) École Polytechnique Fédérale de Lausanne CH-1015 Lausanne Switzerland Designed Material Technologies LLC P.O. Box 14548 Richmond Virginia 23221-9998 USA John A. Paulson School of Engineering and Applied Sciences Harvard University 29 Oxford Street Cambridge Massachusetts 02138 USA Robert Bosch LLC Research and Technology Center Cambridge Massachusetts 02139 USA Department of Physics and Science of Advanced Materials Program Central Michigan University Mt. Pleasant Michigan 48859 USA

We highlight with first-principles molecular dynamics the persistence of intrinsic 〈111〉 Ti off-centerings for BaTiO3 in its cubic paraelectric phase. Intriguingly, these are inconsistent with the Pm3¯m space group often used to atomistically model this phase using density-functional theory or similar methods. Therefore, we deploy a systematic symmetry analysis to construct representative structural models in the form of supercells that satisfy a desired point symmetry but are built from the combination of lower-symmetry primitive cells. We define as structural prototypes the smallest of these that are both energetically and dynamically stable. Remarkably, two 40-atom prototypes can be identified for paraelectric BaTiO3; these are also common to many other ABO3 perovskites. These prototypes can offer structural models of paraelectric phases that can be used for the computational engineering of functional materials. Last, we show that the emergence of B-cation off-centerings and the primitive-cell phonon instabilities is controlled by the equilibrium volume, in turn, dictated by the filler A cation.

关键词： Crystal symmetry Ferroelectricity Structural order parameter Paraelectrics

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Three-dimensional ultrafast charge-density-wave dynamics in CuTe

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Nature Communications 2024年第1期15卷 2386页

作者： Nhat Quyen, Nguyen Tzeng, Wen-Yen Hsu, Chih-En Lin, I-An Chen, Wan-Hsin Jia, Hao-Hsiang Wang, Sheng-Chiao Liu, Cheng-En Chen, Yu-Sheng Chen, Wei-Liang Chou, Ta-Lei Wang, I-Ta Kuo, Chia-Nung Lin, Chun-Liang Wu, Chien-Te Lin, Ping-Hui Weng, Shih-Chang Cheng, Cheng-Maw Kuo, Chang-Yang Tu, Chien-Ming Chu, Ming-Wen Chang, Yu-Ming Lue, Chin Shan Hsueh, Hung-Chung Luo, Chih-Wei Department of Electrophysics National Yang Ming Chiao Tung University Hsinchu 30010 Taiwan Department of Electronic Engineering National Formosa University Yunlin 632 Taiwan Department of Physics Tamkang University New Taipei City 251301 Taiwan National Synchrotron Radiation Research Center Hsinchu 30076 Taiwan Center for Condensed Matter Sciences National Taiwan University Taipei 10617 Taiwan Department of Physics National Cheng Kung University Tainan 70101 Taiwan Physics Division National Center for Theoretical Sciences Taipei Taiwan Undergraduate Degree Program of Systems Engineering and Technology National Yang Ming Chiao Tung University Hsinchu 30010 Taiwan Chung Cheng Institute of Technology National Defense University Taoyuan 335009 Taiwan Center of Atomic Initiative for New Materials (AI-MAT) National Taiwan University Taipei 10617 Taiwan Taiwan Consortium of Emergent Crystalline Materials (TCECM) National Science and Technology Council Taipei 10601 Taiwan Institute of Physics and Center for Emergent Functional Matter Science National Yang Ming Chiao Tung University Hsinchu 30010 Taiwan Department of Physics University of Washington Seattle 98195 WA United States

Charge density waves (CDWs) involved with electronic and phononic subsystems simultaneously are a common quantum state in solid-state physics, especially in low-dimensional materials. However, CDW phase dynamics in various dimensions are yet to be studied, and their phase transition mechanism is currently moot. Here we show that using the distinct temperature evolution of orientation-dependent ultrafast electron and phonon dynamics, different dimensional CDW phases are verified in CuTe. When the temperature decreases, the shrinking of c-axis length accompanied with the appearance of interchain and interlayer interactions causes the quantum fluctuations (QF) of the CDW phase until 220 K. At T < 220 K, the CDWs on the different ab-planes are finally locked with each other in anti-phase to form a CDW phase along the c-axis. This study shows the dimension evolution of CDW phases in one CDW system and their stabilized mechanisms in different temperature regimes. © The Author(s) 2024.

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Detecting mercury ions in water using a low-cost colorimetric sensor derived from immobilized silver nanoparticles on a paper substrate

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Environmental Nanotechnology, Monitoring and Management 2022年 18卷

作者： Budlayan, Marco Laurence Dalagan, Jhonnybert Lagare-Oracion, Jeanne Phyre Patricio, Jonathan Arco, Susan Latayada, Felmer Vales, Temmy Baje, Benito Alguno, Arnold Capangpangan, Rey Department of Physics School of Science and Engineering Ateneo de Manila University Quezon City 1108 Philippines Department of Chemistry Caraga State University Butuan City 8600 Philippines Materials Science and Polymer Chemistry Laboratory Caraga State University Butuan City 8600 Philippines Materials Science Engineering Program College of Science University of the Philippines Diliman Quezon City 1101 Philippines Synthetic Organic Chemistry Laboratory Institute of Chemistry University of the Philippines Diliman Quezon City 1101 Philippines Physics Unit Philippine Science High School Central Visayas Campus Talaytay Argao 6021 Cebu Philippines Department of Physics Mindanao State University-Iligan Institute of Technology Tibanga Iligan City 9200 Philippines Department of Physical Sciences and Mathematics College of Marine and Allied Sciences Mindanao State University at Naawan Poblacion Naawan 9023 Misamis Oriental Philippines

The exceptional and specific reactivity of mercury ions (Hg2+) toward plasmonic silver nanoparticles (AgNPs) in aqueous media has motivated the need to develop innovative, low-cost, portable, and robust sensors to hel... 详细信息

The exceptional and specific reactivity of mercury ions (Hg²⁺) toward plasmonic silver nanoparticles (AgNPs) in aqueous media has motivated the need to develop innovative, low-cost, portable, and robust sensors to help address the detrimental effects of heavy metal contamination particularly in rural communities. In this paper, we present the plasmonic and colorimetric sensing of Hg²⁺ using a paper-based sensing material derived from thiamine-functionalized (ThAgNPs) that were immobilized on a commercial filter paper. Plasmonic AgNPs with a surface plasmon resonance peak at 420 nm and a size of about 21.3 nm were synthesized by a chemical reduction technique. Fourier transform infrared spectroscopy revealed the characteristic functional groups of thiamine in the spectra of AgNPs, thereby confirming the functionalization of AgNPs. The successful integration of ThAgNPs onto the Whatman filter paper (WFP) matrix was confirmed by the UV–vis and SEM-EDX results. An evident color change from yellowish to white was manifested by the fabricated WFP-ThAgNP sensor in the presence of Hg²⁺ with an appreciable detection of up to 0.5 µM using the naked eye. The colorimetric response of the sensor was also found to be selective towards Hg²⁺ after testing with different metal ions. Moreover, the response was consistent for tap, and creek water samples spiked with Hg²⁺. The results of this work provide a promising baseline technology for the development of an affordable, fast, portable, and reliable sensor that can be used for on-site detection and monitoring of Hg²⁺ levels in the water. © 2022 Elsevier B.V.

关键词： Colorimetric sensor Mercury detection Paper-based device Silver nanoparticle Thiamine

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Towards the Development of Tailored Steel Rebars for Carbonated-Cured Cement Matrices

SSRN

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SSRN 2023年

作者： Felipe, Rafaela F. Rezende, Mariana de Almeida Motta Corradini, Patricia Gon Santiago, Matheus Ambrósio H. Sales, Almir da Ferreira, Fernanda Silva G. Huet, Bruno Nogueira, Ricardo P. Koga, Guilherme Yuuki Federal University of São Carlos Graduate Program in Materials Science and Engineering Rod. Washington Luis km 235 SP São CarlosCEP 13565-905 Brazil Federal University of São Carlos Department of Materials Science and Engineering Rod. Washington Luis km 235 SP São CarlosCEP 13565-905 Brazil Faculty of exact sciences and technology Pontifical Catholic University of São Paulo Marquês de Paranaguá 111 SP São Paulo01303-050 Brazil Department of Chemistry Federal University of São Carlos Mailbox 676 SP São CarlosCEP 13565-905 Brazil Laboratório de Análises Químicas e Agroambientais Fluminense Federal Institute of Education Science and Technology Campus Itaperuna BR 356 km 3 RJ Itaperuna CEP 28300-000 Brazil Department of Civil Engineering Federal University of São Carlos Mailbox 676 SP São CarlosCEP 13565-905 Brazil Holcim Innovation Center 95 Rue du Montmurier Saint-Quentin-Fallavier38070 France Chemical Engineering Department Khalifa University of Science and Technology Abu Dhabi127788 United Arab Emirates Federal University of Sao Carlos Rodovia Washington Luiz km 235 SP-310 São Paulo São Carlos13565-905 Brazil

The passivation ability of steels with low chromium contents (4% and 6%) in a solution representative of carbonated-cured concrete matrices was compared to conventional carbon steel rebars. Samples were investigated through multiple electrochemical methods, and the passive film was evaluated using x-ray photoelectron spectroscopy. Results showed that carbon steel rebars are vulnerable to corroding in carbonated-cured pore solutions, while the low chromium showed spontaneous, rapid and effective passivation. The study demonstrated the possibility of producing tailored low chromium steels as a durable alternative to carbon steel while being more affordable than stainless steel, contributing to more sustainable, innovative reinforced concretes. © 2023, The Authors. All rights reserved.

关键词： Steel corrosion

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Repositioned Drugs for COVID-19-the Impact on Multiple Organs

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SN comprehensive clinical medicine 2021年第7期3卷 1484-1501页

作者： Christina Chan Sean T Foster Kayla G Chan Matthew J Cacace Shay L Ladd Caleb T Sandum Paul T Wright Brett Volmert Weiyang Yang Aitor Aguirre Wen Li Neil T Wright Department of Chemical Engineering and Materials Sciences Michigan State University 428 S. Shaw Lane Room 2100 EB East Lansing MI 48824 USA. Department of Biochemistry and Molecular Biology Michigan State University East Lansing MI USA. Department of Biomedical Engineering Michigan State University East Lansing MI USA. Institute for Quantitative Health Science and Engineering Michigan State University East Lansing MI USA. Integrative Neuroscience Program Binghamton University Binghamton NY USA. Department of Mechanical Engineering The Pennsylvania State University University Park PA USA. Department of Mechanical Engineering Virginia Polytechnic Institute and State University Blacksburg VA USA. Department of Electrical and Computer Engineering Michigan State University East Lansing MI USA. Department of Mechanical Engineering Michigan State University East Lansing MI USA.

This review summarizes published findings of the beneficial and harmful effects on the heart, lungs, immune system, kidney, liver, and central nervous system of 47 drugs that have been proposed to treat COVID-19. Many of the repurposed drugs were chosen for their benefits to the pulmonary system, as well as immunosuppressive and anti-inflammatory effects. However, these drugs have mixed effects on the heart, liver, kidney, and central nervous system. Drug treatments are critical in the fight against COVID-19, along with vaccines and public health protocols. Drug treatments are particularly needed as variants of the SARS-Cov-2 virus emerge with some mutations that could diminish the efficacy of the vaccines. Patients with comorbidities are more likely to require hospitalization and greater interventions. The combination of treating severe COVID-19 symptoms in the presence of comorbidities underscores the importance of understanding the effects of potential COVID-19 treatments on other organs.

关键词： COVID-19 Central nervous system Drug repositioning Heart Immune system Kidneys Liver Lungs

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Temperature-dependent crystal structure of U3Si2 by high-temperature neutron diffraction 14

Temperature-dependent crystal structure of U3Si2 by high-tem...

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14th International Nuclear Fuel Cycle Conference, GLOBAL 2019 and Light Water Reactor Fuel Performance Conference, TOP FUEL 2019

作者： Vogel, Sven C. Wilson, Tashiema L. Wood, Elizabeth Sooby White, Joshua T. Besmann, Theodore M. Materials Science and Technology Division Los Alamos National Laboratory MS H805 Los AlamosNM87545 United States Mechanical Engineering Department Nuclear Engineering Program University of South Carolina 541 Main St ColumbiaSC29201 United States Department of Physics and Astronomy College of Sciences University of Texas at San Antonio One UTSA Circle San AntonioTX78249 United States

The crystal structure of the U3Si2 line compound in the U-Si system was investigated as a function of temperature from room temperature to 1373 K using high temperature neutron time-of-flight diffraction on the High-pressure Pressure/preferred Preferred Orientation (HIPPO) diffractometer at the Los Alamos Neutron science Center (LANSCE). The U-Si system is actively researched due to its promise as an accident tolerant nuclear fuel. The simultaneous Rietveld refinement of five histograms from the five HIPPO detector rings provided fundamental datasets for the lattice parameters, anisotropic atomic displacement parameters, and atomic positions as a function of temperature. To explore the possibility of a homogeneity range, two samples were analyzed, stoichiometric U3Si2.00 and a hyperstoichiometric U3Si2.01. While minor differences in the thermal expansion anisotropic atomic displacement parameters between the two samples were observed, over the entire investigated temperature range no additional phases were observed. However, significant differences in the thermal expansion behavior were identified between the two compositions that warrant future investigations. Copyright © GLOBAL 2019 - International Nuclear Fuel Cycle Conference and TOP FUEL 2019 - Light Water Reactor Fuel Performance *** rights reserved.

关键词： Atoms

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Endotaxial Stabilization of 2D Charge Density Waves with Long-Range Order

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Microscopy and Microanalysis 2024年第SUPPLEMENT_1期30卷

作者： Sung, Suk Hyun Agarwal, Nishkarsh Baggari, Ismail El Kezer, Patrick Goh, Yin Min Schnitzer, Noah Shen, Jeremy M Chiang, Tony Liu, Yu Lu, Wenjian Sun, Yuping Kourkoutis, Lena F Heron, John T Sun, Kai Hovden, Robert Department of Materials Science and Engineering University of Michigan Ann Arbor MI USA Rowland Institute at Harvard University Cambridge MA USA Department of Electrical and Computer Engineering University of Michigan Ann Arbor MI USA John A. Paulson School of Engineering and Applied Science Harvard University Cambridge MA USA Department of Materials Science and Engineering Cornell University Ithaca NY USA Kavli Institute at Cornell for Nanoscale Science Ithaca NY USA Key Laboratory of Materials Physics Institute of Solid State Physics Chinese Academy of Sciences Hefei PR China Collaborative Innovation Centre of Advanced Microstructures Nanjing University Nanjing PR China High Magnetic Field Laboratory Chinese Academy of Sciences Hefei PR China School of Applied and Engineering Physics Cornell University Ithaca NY USA Applied Physics Program University of Michigan Ann Arbor MI USA Department of Physics University of Michigan Ann Arbor MI USA

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Isomeric 1,4-Dihydropentalene-Containing Building Blocks for High Mobility Ladder-Type Conjugated Polymers

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Angewandte Chemie 2025年

作者： Shengnan Zhang Yuqian Liu Hao Dong Yanru Li Kai Zhang Kaihu Xian Prof. Yang Han Prof. Long Ye Prof. Martin Heeney Prof. Zhuping Fei Institute of Molecular Plus Department of Chemistry and Haihe Laboratory of Sustainable Chemical Transformations Key Laboratory of Organic Integrated Circuits Ministry of Education Tianjin University Tianjin 300072 China School of Materials Science & Engineering Tianjin Key Laboratory of Molecular Optoelectronic Sciences and Collaborative Innovation Center of Chemical Science and Engineering Tianjin University Tianjin 300350 China Institute for Electric Light Sources School of Information Science and Technology Fudan University Shanghai 200433 China Division of Physical Sciences & Engineering Chemistry Program King Abdullah University of Science and Technology (KAUST) Thuwal 23955-6900 Saudi Arabia

Nearly amorphous conjugated polymers, though lacking long-range order, can exhibit high charge carrier mobility and enhanced flexibility, making them ideal for flexible or stretchable OFET applications. However, research on novel structural blocks for this class of materials remains limited. We report the synthesis of two derivatives of the 5,10-dihydroindeno[2,1- a ]indene (DHI) core, where two thieno groups are appended to each end to reduce torsional disorder with adjacent comonomers. The two 1,4-dihydropentalene containing isomers, anti-C16DHIT-Br and syn-C16DHIT-Br, feature distinct thieno group orientations, leading to differences in their electronic properties. The anti-isomer shows a fully delocalized conjugation pathway, whereas the syn isomer exhibits cross-conjugation, limiting delocalization along the polymer backbone. These monomers were copolymerized with benzothiadiazole (BT) to form two conjugated polymers, anti-C16DHIT-BT and syn-C16DHIT-BT, both with highly planar backbones, good solubility, and solution processability. Morphological studies reveal that anti-C16DHIT-BT exhibits more ordered stacking and higher crystallinity than syn-C16DHIT-BT. Devices based on anti-C16DHIT-BT show significantly better performance, with a hole mobility of 2.38 cm 2 V −1 s −1 , slightly higher than the widely studied pIDTBT under identical conditions.

关键词： Conjugated polymers High mobility Isomerization effect Novel building blocks Organic field-effect transistors

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Room-temperature polar metal stabilized under high pressure

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Physical Review B 2020年第22期101卷 220101(R)-220101(R)页

作者： J.-J. Gao S.-Y. Fu K. Yamaura J. F. Lin J.-S. Zhou Materials Science and Engineering Program Mechanical Engineering The University of Texas at Austin Austin Texas 78712 USA Institute of Fluid Physics China Academy of Engineering Physics Mianyang 621900 China Department of Geological Sciences The University of Texas at Austin Austin Texas 78712 USA International Center for Materials Nanoarchitectronics (WPI-MANA) National Institute for Materials Science 1-1 Namiki Tsukuba Ibaraki 305-0044 Japan Graduate School of Chemical Sciences and Engineering Hokkaido University North 10 West 8 Kita-ku Sapporo Hokkaido 060-0810 Japan

LiOsO3 synthesized under high pressure in recent years is a rare metal since it undergoes a nonpolar to polar phase transition at Ts=140K. Forming a polar axis through a phase transition in a metal seems against common sense. It is also not clear whether the transition to a polar phase in the oxide fits the mechanism predicted by Anderson and Blount in 1965. As monitored by an anomaly of resistivity in LiOsO3 at Ts reported recently, Ts increases under pressure. The structural study under high pressure could give us a useful clue for understanding how dipoles form in this metallic oxide. Here, we report the identification of a polar phase of LiOsO3 at room temperature under high pressure by using in situ probes of Raman and synchrotron x-ray diffraction. In the Raman study, the pressure-induced modes and their responses to polarized light, the linewidth change, the peak profile change, and mode softening have been directly compared with the corresponding changes of LiOsO3 on cooling through Ts at ambient pressure. Whereas a complete set of Raman modes from the R3c phase can be found at P≥15.5GPa, a Raman mode of the R3c phase appears in the R3¯c phase at 4.11 GPa. A significant drop in the linewidth occurs at 12.6 GPa that coincides with the critical pressure for the phase transition to the polar phase detected by x-ray diffraction. Fitting the peak profile of a Raman mode to the Fano formula also indicates a clear change of electron-phonon coupling at 16 GPa. In contrast to a sharp structural transition to the polar phase at Ts under ambient pressure, our results reveal all the structural ingredients to facilitate the polar phase over a broad range of pressure. A bond valence sum analysis has been introduced to reveal the local structural instability under pressure. The transition to the polar phase in metallic LiOsO3 is solely caused by optimizing the local structure in order to make the bond valence sum close to the formal valence of the Li ion.

关键词： Ferroelectricity Phase transitions Pressure effects Metals

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Field-driven metamorphoses of isolated skyrmions within the conical state of cubic helimagnets

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Physical Review B 2021年第6期104卷 064432-064432页

作者： Andrey O. Leonov C. Pappas Ivan I. Smalyukh Department of Chemistry Faculty of Science Hiroshima University Kagamiyama Higashi Hiroshima Hiroshima 739-8526 Japan Chirality Research Center Hiroshima University Higashi Hiroshima Hiroshima 739-8526 Japan IFW Dresden Postfach 270016 D-01171 Dresden Germany Faculty of Applied Sciences Delft University of Technology Mekelweg 15 2629JB Delft The Netherlands Soft Materials Research Center and Materials Science and Engineering Program University of Colorado Boulder Colorado 80309 USA Department of Physics and Department of Electrical Computer and Energy Engineering University of Colorado Boulder Colorado 80309 USA Renewable and Sustainable Energy Institute National Renewable Energy Laboratory and University of Colorado Boulder Colorado 80309 USA

Topologically stable field configurations appear in many fields of physics, from elementary particles to condensed matter and cosmology. Deep physical relations and common physical features of a large variety of very different solitonic states in these systems arise from the mathematical similarity of phenomenological equations. During the last decade, chiral liquid crystals and chiral magnets took on the role of model objects for the experimental investigation of topological solitons and the understanding of their nonsingular field configurations. This is directly related to the discovery of particle-like chiral skyrmions, which are also considered as promising ingredients for technological applications. Here we introduce a paradigm of facile skyrmionic networks with mutually orthogonal orientations of constituent isolated skyrmions. On the one hand, such networks are envisioned as a novel concept of spintronic devices based, e.g., on gapless skyrmion motion along each other, and are presumably responsible for precursor phenomena near the ordering temperatures of bulk cubic helimagnets. In particular, we demonstrate an interconversion between mutually orthogonal skyrmions: horizontal skyrmions may swirl into an intermediate spring-like state and subsequently squeeze into vertical skyrmions with both polarities. On the other hand, skyrmion tubes are considered as building blocks for particle-like states with more involved internal structure. A family of target-skyrmions, which includes a so far overlooked type with a multiple topological charge, is formed owing to the tendency to minimize the interaction energy between vertical and horizontal skyrmions. The conical phase serves as a suitable background for considered skyrmion evolution. It substantializes the attracting skyrmion-skyrmion interaction in the skyrmionic networks, shapes their internal structure, and guides the nucleation processes. Alternatively, intricate textural changes of isolated skyrmions result

关键词： Skyrmions Chiral magnets Cholesteric liquid crystals Helimagnets

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