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Microsecond electro-optic switching in the nematic phase of a ferroelectric nematic liquid crystal

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arXiv 2024年

作者： Thapa, Kamal Paladugu, Sathyanarayana Lavrentovich, Oleg D. Advanced Materials and Liquid Crystal Institute Kent State University KentOH44242 United States Department of Physics Kent State University KentOH44241 United States Materials Science Graduate Program Kent State University KentOH44242 United States

Nematic liquid crystals exhibit nanosecond electro-optic response to an applied electric field which modifies the degree of orientational order without realigning the molecular orientation. However, this nanosecond electrically-modified order parameter (NEMOP) effect requires high driving fields, on the order of 108 Vm for a modest birefringence change of 0.01. In this work, we demonstrate that a nematic phase of the recently discovered ferroelectric nematic materials exhibits a robust and fast electro-optic response. Namely, a relatively weak field of 2 × 107 Vm changes the birefringence by ≈ 0.04 with field-on and-off times around 1 μs. This microsecond electrically modified order parameter (MEMOP) effect shows a greatly improved figure of merit when compared to other electro-optical switching modes in liquid crystals, including the conventional Frederiks effect, and has a potential for applications in fast electro-optical devices such as phase modulators, optical shutters, displays, and beam steerers. © 2024, CC BY-NC-ND.

关键词： Birefringence

Synthesis and Biomedical Applications of Artificial Cells

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SSRN

SSRN 2023年

作者： Xu, Qian Zhang, Zeping Lui, Pauline Po Yee Li, Xiaowu Zhang, Xing Department of Materials Physics and Chemistry School of Materials Science and Engineering Key Laboratory for Anisotropy and Texture of Materials Ministry of Education Northeastern University Liaoning Shenyang110819 China Shi-changxu Innovation Center for Advanced Materials Institute of Metal Research Chinese Academy of Sciences Liaoning Shenyang110016 China School of Materials Science and Engineering University of Science and Technology of China Anhui Hefei230026 China Department of Orthopaedics and Traumatology The Chinese University of Hong Kong 999077 Hong Kong

Artificial cells (ACs) have received much attention in recent years as cell mimics for better understanding of the origin of life, models for understanding biological processes, engineered cells with improved properties, vehicles for drug delivery, and bioreactors for the synthesis of biomolecules. The research of ACs has expanded into areas including biotechnology, medicine, bioremediation, and engineering, and new applications are being developed. It is therefore important to understand the techniques for the fabrication of ACs and their applications for further technological advancement. This review aims to summarize the advantages and limitations of different methods for the synthesis of ACs as well as the applications of ACs in biomedicine as drug carriers (microcapsules), as signaling regulators for coordinating cellular communication and as bioreactors for biomolecule synthesis. © 2023, The Authors. All rights reserved.

关键词： Bioreactors

The adsorption postures of water on CH3NH3PbI3surfaces: A first-principles insight

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The adsorption postures of water on CH3NH3PbI3surfaces: A fi...

2022 International Conference on Green Energy and Power Systems, ICGEPS 2022

作者： Pu, Wenhua Yang, Hui Xiao, Wei Li, Xiaowu Wang, Ligen Department of Materials Physics and Chemistry School of Materials Science and Engineering Key Laboratory for Anisotropy and Texture of Materials Ministry of Education Northeastern University Shenyang110819 China State Key Laboratory of Nonferrous Metals and Processes GRINM Group Co. Ltd Beijing100088 China GRIMAT Engineering Institute Co. Ltd Beijing101407 China General Research Institute for Nonferrous Metals Beijing100088 China

Inorganic organic perovskite solar cells (PSCs) are a kind of solar cells with rapid development in recent years, but their poor environmental stability, such as the water degradation behavior, hinders their commercialization. Here, we have thoroughly studied the adsorption postures of water on CH3NH3PbI3 surfaces. It is found that the adsorption energy of water molecules on perovskite surfaces is [-0.63, -0.59] eV, and with different initial postures, water molecules could eventually be adsorbed above Pb atom in a horizontal structure. The interaction between the perovskite surface and water molecules mainly comes from the electron exchange of Pb-O atoms. The weak interaction between H-I atoms makes the H atom approach the I atom, which could help maintain a horizontal structure of water molecules. The interactions between perovskite surfaces and water are well explained by our DFT calculations. © Published under licence by IOP Publishing Ltd.

关键词： Atoms

Chiral ground states of ferroelectric liquid crystals

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arXiv 2024年

作者： Kumari, Priyanka Basnet, Bijaya Lavrentovich, Maxim O. Lavrentovich, Oleg D. Advanced Materials and Liquid Crystal Institute Kent State University KentOH44242 United States Materials Science Graduate Program Kent State University KentOH44242 United States Department of Earth Environment and Physics Worcester State University WorcesterMA01602 United States Department of Physics Kent State University KentOH44242 United States

Ferroelectric nematic liquid crystals are formed by achiral molecules with large dipole moments. Its three-dimensional orientational order is universally described as unidirectionally polar. We demonstrate that the ground state of ferroelectric nematic unconstrained by externally imposed alignment directions is chiral, with left- and right-hand twists of polarization. Although the helicoidal deformations and defect walls separating domains of opposite handedness increase the elastic energy, the twists reduce the electrostatic energy and become weaker when the material is doped with ions. The study shows that the polar orientational order of molecules could trigger chirality in the soft matter with no chemically induced chiral centers. © 2024, CC BY.

关键词： Ground state

The influence of molecular structure on the thermal properties and processability of nitrile-based resin molecules 3

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The influence of molecular structure on the thermal properti...

2021 3rd International Conference on Polymer Synthesis and Application, ICPSA 2021

作者： Mengdi, Chen Wei, Liao Changping, Yin Suli, Xing Su, Ju Liping, Sheng Department of Materials Science and Engineering National University of Defense Technology Hunan Changsha China Department of Polymer Chemistry and Physics Hunan Normal University Hunan Changsha China

With the increase in the speed of various aircraft and the demand for lightweight weapons and equipment, the demand for high-performance, high-temperature-resistant resin-based composite materials has become more urgent. The temperature resistance and molding process of composite materials are determined by the temperature resistance and manufacturability of the resin, so there is an urgent need to develop a resin that has both high temperature resistance and excellent process performance. The temperature resistance and processability of the resin are essentially determined by the molecular structure of the resin system. Therefore, in order to design a resin system with excellent heat resistance and processability, the relationship between molecular structure and performance must first be recognized. This paper collects a large amount of experimental data and preliminarily summarizes the influence of different molecular structures on the thermal performance and resin processability of resin polymers from the perspective of structure and performance. This provides a good experience and theoretical basis for the design of high-performance resin systems, providing references and ideas for related research. © 2021 Institute of physics Publishing. All rights reserved.

关键词： Resins

Performance Evaluation of a Diamond Quantum Magnetometer for Biomagnetic Sensing: A Phantom Study

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arXiv 2024年

作者： Sekiguchi, Naota Kainuma, Yuta Fushimi, Motofumi Shinei, Chikara Miyakawa, Masashi Taniguchi, Takashi Teraji, Tokuyuki Abe, Hiroshi Onoda, Shinobu Ohshima, Takeshi Hatano, Mutsuko Sekino, Masaki Iwasaki, Takayuki Department of Electrical and Electronic Engineering Institute of Science Tokyo Meguro Tokyo152-8550 Japan Department of Bioengineering The University of Tokyo Bunkyo Tokyo113-8656 Japan Research Center for Electronic and Optical Materials National Institute for Materials Science Ibaraki Tsukuba305-0044 Japan Department of Applied Physics University of Tsukuba Ibaraki Tsukuba305-8571 Japan Research Center for Materials Nanoarchitectonics National Institute for Materials Science Ibaraki Tsukuba305-0044 Japan Takasaki Institute for Advanced Quantum Science National Institutes for Quantum Science and Technology Gunma Takasaki370-1292 Japan Department of Materials Science Tohoku University Miyagi Sendai980-8579 Japan

We employ a dry-type phantom to evaluate the performance of a diamond quantum magnetometer with a high sensitivity of about 6 pT/√Hz from the viewpoint of practical measurement in biomagnetic sensing. The dry phantom is supposed to represent an equivalent current dipole (ECD) generated by brain activity, emulating an encephalomagnetic field. The spatial resolution of the magnetometer is evaluated to be sufficiently higher than the length of the variation in the encephalomagnetic field distribution. The minimum detectable ECD moment is evaluated to be 0.2 nA m by averaging about 8000 measurements for a standoff distance of 2.4 mm from the ECD. We also discuss the feasibility of detecting an ECD in the measurement of an encephalomagnetic field in humans. We conclude that it is feasible to detect an encephalomagnetic field from a shallow cortex area such as the primary somatosensory cortex. © 2024, CC BY-NC-SA.

关键词： Biomagnetism

Clean realization of the Hund physics near the Mott transition: NiS2 under pressure

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arXiv 2023年

作者： Park, Ina Jang, Bo Gyu Kim, Dong Wook Shim, Ji Hoon Kotliar, Gabriel Department of Chemistry Pohang University of Science and Technology Pohang37673 Korea Republic of Department of Advanced Materials Engineering For Information & Electronics Kyung Hee University Yongin17104 Korea Republic of Physics and Astronomy Department Center for Materials Theory Rutgers University PiscatawayNJ08854 United States Condensed Matter Physics and Materials Science Department Brookhaven National Laboratory UptonNY11973 United States

Strong correlation effects caused by Hund’s coupling have been actively studied during the past decade. Hund’s metal, strongly correlated while far from the Mott insulating limit, was studied as a representative example. However, recently, it was revealed that a typical Mott system also exhibits a sign of Hund physics by investigating the kink structure in the spectral function of NiS2-xSex. Therefore, to understand the Hund physics in a half-filled multi-orbital system near the metal-insulator transition, we studied pressure-induced metallic states of NiS2 by using density functional theory plus dynamical mean-field theory. Hund physics, responsible for suppressing local spin fluctuation, gives low-energy effective correlations, separated from Mott physics, which suppresses charge fluctuation at higher energy. This effect is prominent when J becomes comparable to the quasiparticle kinetic energy, showing apparent scaling behavior of the kink position Ekink ~ J•Z. We suggest that the Hund effect can also be observed in the optical conductivity as a non-Drude-like tail with 1/ω frequency dependence and non-monotonic temperature evolution of the integrated optical spectral weight at fixed frequency. Our study demonstrates the important role of Hund’s coupling for electronic correlations even in a half-filled system. Copyright © 2023, The Authors. All rights reserved.

关键词： Metal insulator transition

Solid state reduction of nickelate thin films

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Physical Review materials 2023年第1期7卷 013802-013802页

作者： Wenzheng Wei Kidae Shin Hawoong Hong Yeongjae Shin Arashdeep Singh Thind Yingjie Yang Robert F. Klie Frederick J. Walker Charles H. Ahn Department of Applied Physics Yale University New Haven Connecticut 06520 USA Department of Physics Yale University New Haven Connecticut 06520 USA Advanced Photon Source Argonne National Laboratory Argonne Illinois 60439 USA Department of Physics University of Illinois Chicago Chicago Illinois 60607 USA Department of Mechanical Engineering and Materials Science Yale University New Haven Connecticut 06520 USA

The square-planar nickelates are a class of superconductors analogous to the cuprates and promise to provide insight into the pairing mechanism in high-temperature superconducting oxides. The parent phase of doped superconducting films is NdNiO2, which is prepared by reducing 3+ Ni in NdNiO3 films. In this paper, we develop an ultrahigh vacuum reduction method using aluminum deposited on top of the 3+ nickelates and monitor the reduction process in real time through in situ crystal truncation rod measurements and diffraction x-ray absorption near edge spectroscopy measurements across the Ni K edge. We establish a relation between Ni valence and the lattice constant of NdNiO3−x and show that the process can precisely control the oxygen content in the films. Finally, we extend the reduction process to quintuple square-planar nickelates.

关键词： Crystal structure Electronic structure Synthesis Perovskites Ultrathin films Molecular beam epitaxy X-ray absorption near-edge spectroscopy X-ray diffraction

Theory-directed discovery of high-temperature superconductivity in clathrate hydrides at high pressure

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The Innovation 2022年第2期3卷 9-10页

作者： Xin Zhong John S.Tse Russell J.Hemley Hanyu Liu International Center for Computational Method&Software and State Key Laboratory of Superhard Materials College of PhysicsJilin UniversityChangchun 130012China Department of Physics and Engineering Physics University of SaskatchewanSaskatoon S7N 5E2Canada Departments of Physics Chemistryand Earth and Environmental SciencesUniversity of Illinois ChicagoChicagoIL 60607USA International Center of Future Science Jilin UniversityChangchun 130012China

The search for room-temperature superconductivity has been one of the great challenges in condensedmatter physics ever since the first observation of superconductivity with a critical temperature(T_(c))of 4 K in mercury in *** recent years,we have been witness to the successful observation of superconductivity in highly compressed SH_(3)(T_(c)=203 K at 155 GPa)and classes of clathrate hydrides(e.g.,CaH_(6),YH_(6),YH_(9),LaH_(10)).

关键词： hydrides superconductivity high