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Hu X, Yu Chen G, Luan Y, Tang T, Liang Y, Ren B, Chen L, Zhao Y, Zhang Q, Huang D, Sun X, Cheng YF, Ou JZ. Flexoelectricity Modulated Electron Transport of 2D Indium Oxide. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2024:e2404272. [PMID: 38953411 DOI: 10.1002/advs.202404272] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/22/2024] [Revised: 06/04/2024] [Indexed: 07/04/2024]
Abstract
The phenomenon of flexoelectricity, wherein mechanical deformation induces alterations in the electron configuration of metal oxides, has emerged as a promising avenue for regulating electron transport. Leveraging this mechanism, stress sensing can be optimized through precise modulation of electron transport. In this study, the electron transport in 2D ultra-smooth In2O3 crystals is modulated via flexoelectricity. By subjecting cubic In2O3 (c-In2O3) crystals to significant strain gradients using an atomic force microscope (AFM) tip, the crystal symmetry is broken, resulting in the separation of positive and negative charge centers. Upon applying nano-scale stress up to 100 nN, the output voltage and power values reach their maximum, e.g. 2.2 mV and 0.2 pW, respectively. The flexoelectric coefficient and flexocoupling coefficient of c-In2O3 are determined as ≈0.49 nC m-1 and 0.4 V, respectively. More importantly, the sensitivity of the nano-stress sensor upon c-In2O3 flexoelectric effect reaches 20 nN, which is four to six orders smaller than that fabricated with other low dimensional materials based on the piezoresistive, capacitive, and piezoelectric effect. Such a deformation-induced polarization modulates the band structure of c-In2O3, significantly reducing the Schottky barrier height (SBH), thereby regulating its electron transport. This finding highlights the potential of flexoelectricity in enabling high-performance nano-stress sensing through precise control of electron transport.
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Affiliation(s)
- Xinyi Hu
- Key Laboratory of Advanced Technologies of Materials, Ministry of Education, School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu, 610031, China
| | - Guan Yu Chen
- Key Laboratory of Advanced Technologies of Materials, Ministry of Education, School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu, 610031, China
| | - Yange Luan
- School of Engineering, RMIT University, Melbourne, 3000, Australia
| | - Tao Tang
- Key Laboratory of Advanced Technologies of Materials, Ministry of Education, School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu, 610031, China
| | - Yi Liang
- Key Laboratory of Advanced Technologies of Materials, Ministry of Education, School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu, 610031, China
| | - Baiyu Ren
- Key Laboratory of Advanced Technologies of Materials, Ministry of Education, School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu, 610031, China
| | - Liguo Chen
- School of Mechanical and Electric Engineering Jiangsu Provincial Key Laboratory of Advanced Robotics, Soochow University, Suzhou, 215123, China
| | - Yulong Zhao
- State Key Laboratory for Manufacturing Systems Engineering, School of Mechanical Engineering, Xi'an Jiaotong University, Xi'an, 710049, China
| | - Qi Zhang
- State Key Laboratory for Manufacturing Systems Engineering, School of Mechanical Engineering, Xi'an Jiaotong University, Xi'an, 710049, China
| | - Dong Huang
- Department of Physics, The University of Hong Kong, Hong Kong, 999077, China
| | - Xiao Sun
- Inorganic Chemistry, University of Koblenz, Universitätsstraße 1, 56070, Koblenz, Germany
| | - Yin Fen Cheng
- Institute of Advanced Study, Chengdu University, Chengdu, 610106, China
| | - Jian Zhen Ou
- Key Laboratory of Advanced Technologies of Materials, Ministry of Education, School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu, 610031, China
- School of Engineering, RMIT University, Melbourne, 3000, Australia
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Hrytsyna O, Sladek J, Sladek V, Deng Q, Hrytsyna M. Rayleigh wave propagation in centrosymmetric materials with micro-stiffness, flexoelectric and micro-inertia effects. ULTRASONICS 2024; 141:107317. [PMID: 38657430 DOI: 10.1016/j.ultras.2024.107317] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/28/2023] [Revised: 03/12/2024] [Accepted: 04/15/2024] [Indexed: 04/26/2024]
Abstract
A theoretical investigation of Rayleigh waves propagation in polarized media has been carried out using a reformulated flexoelectric theory for isotropic dielectrics with micro-inertia effect. Within this non-classical theory, the internal energy density is the functional of the strain tensor, dilatation gradient, deviatoric part of stretch gradient and rotation gradient tensors, polarization vector, and polarization gradient. The obtained system of governing equations additionally contains three material length-scale parameters to account the micro-stiffness effect, one material constant to capture the micro-inertia effect, two flexoelectric constants to describe the flexoelectric effect and three length scale parameters related to the polarization gradient. To solve the coupled governing equations, the method of Lamé-type potentials for mechanical displacement and electric polarization vectors is used. The influences of various factors such as micro-stiffness, flexoelectricity, electric quadrupoles and micro-inertia effects on the phase velocity of the Rayleigh waves in a homogeneous isotropic half-space are studied. It is found that above effects become significant with the increase of the wavenumber. This study can be important for the investigation of high frequency surface acoustic waves in dielectric materials.
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Affiliation(s)
- O Hrytsyna
- Department of Mechanics, Institute of Construction and Architecture Slovak Academy of Sciences, Dúbravská cesta 9, Bratislava 84503, Slovakia.
| | - J Sladek
- Department of Mechanics, Institute of Construction and Architecture Slovak Academy of Sciences, Dúbravská cesta 9, Bratislava 84503, Slovakia.
| | - V Sladek
- Department of Mechanics, Institute of Construction and Architecture Slovak Academy of Sciences, Dúbravská cesta 9, Bratislava 84503, Slovakia.
| | - Q Deng
- Department of Engineering Mechanics, Huazhong University of Science and Technology, Luoyu Road, 1037 Wuhan, China.
| | - M Hrytsyna
- Department of Mechanics, Institute of Construction and Architecture Slovak Academy of Sciences, Dúbravská cesta 9, Bratislava 84503, Slovakia.
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Yasui K. Merits and Demerits of Machine Learning of Ferroelectric, Flexoelectric, and Electrolytic Properties of Ceramic Materials. MATERIALS (BASEL, SWITZERLAND) 2024; 17:2512. [PMID: 38893775 PMCID: PMC11172741 DOI: 10.3390/ma17112512] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/26/2024] [Revised: 05/15/2024] [Accepted: 05/21/2024] [Indexed: 06/21/2024]
Abstract
In the present review, the merits and demerits of machine learning (ML) in materials science are discussed, compared with first principles calculations (PDE (partial differential equations) model) and physical or phenomenological ODE (ordinary differential equations) model calculations. ML is basically a fitting procedure of pre-existing (experimental) data as a function of various factors called descriptors. If excellent descriptors can be selected and the training data contain negligible error, the predictive power of a ML model is relatively high. However, it is currently very difficult for a ML model to predict experimental results beyond the parameter space of the training experimental data. For example, it is pointed out that all-dislocation-ceramics, which could be a new type of solid electrolyte filled with appropriate dislocations for high ionic conductivity without dendrite formation, could not be predicted by ML. The merits and demerits of first principles calculations and physical or phenomenological ODE model calculations are also discussed with some examples of the flexoelectric effect, dielectric constant, and ionic conductivity in solid electrolytes.
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Affiliation(s)
- Kyuichi Yasui
- National Institute of Advanced Industrial Science and Technology (AIST), Nagoya 463-8560, Japan
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Wu X, Qi L, Iqbal MA, Dai S, Weng X, Wu K, Kang C, Li Z, Zhao D, Tang W, Zhuge F, Zhai T, Ruan S, Zeng YJ. Revealing Strong Flexoelectricity and Optoelectronic Coupling in 2D Ferroelectric CuInP 2S 6 Via Large Strain Gradient. ACS APPLIED MATERIALS & INTERFACES 2024; 16:14038-14046. [PMID: 38445951 DOI: 10.1021/acsami.3c18678] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/07/2024]
Abstract
The interplay between flexoelectric and optoelectronic characteristics provides a paradigm for studying emerging phenomena in various 2D materials. However, an effective way to induce a large and tunable strain gradient in 2D devices remains to be exploited. Herein, we propose a strategy to induce large flexoelectric effect in 2D ferroelectric CuInP2S6 by constructing a 1D-2D mixed-dimensional heterostructure. The strong flexoelectric effect is induced by enormous strain gradient up to 4.2 × 106 m-1 resulting from the underlying ZnO nanowires, which is further confirmed by the asymmetric coercive field and the red-shift in the absorption edge. The induced flexoelectric polarization efficiently boosts the self-powered photodetection performance. In addition, the improved photoresponse has a good correlation with the induced strain gradient, showing a consistent size-dependent flexoelectric effect. The mechanism of flexoelectric and optoelectronic coupling is proposed based on the Landau-Ginzburg-Devonshire double-well model, supported by density functional theory (DFT) calculations. This work provides a brand-new method to induce a strong flexoelectric effect in 2D materials, which is not restricted to crystal symmetry and thus offers unprecedented opportunities for state-of-the-art 2D devices.
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Affiliation(s)
- Xiaokeng Wu
- Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, P. R. China
| | - Lu Qi
- Key Laboratory of Advanced Optical Precision Manufacturing Technology of Guangdong Higher Education Institutes, Shenzhen Technology University, Shenzhen 518118, P. R. China
| | - Muhammad Ahsan Iqbal
- Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, P. R. China
| | - Sichao Dai
- Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, P. R. China
| | - Xiaoliang Weng
- Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, P. R. China
| | - Kewen Wu
- Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, P. R. China
| | - Chenxu Kang
- Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, P. R. China
| | - Zelong Li
- Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, P. R. China
| | - Duo Zhao
- Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, P. R. China
| | - Wei Tang
- Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, P. R. China
| | - Fuwei Zhuge
- State Key Laboratory of Materials Processing and Die and Mould Technology, School of Materials Science and Engineering, Huazhong University of Science and Technology (HUST), Wuhan 430074, P. R. China
- Shenzhen Huazhong University of Science and Technology Research Institute, Shenzhen 518057, P. R. China
| | - Tianyou Zhai
- State Key Laboratory of Materials Processing and Die and Mould Technology, School of Materials Science and Engineering, Huazhong University of Science and Technology (HUST), Wuhan 430074, P. R. China
- Shenzhen Huazhong University of Science and Technology Research Institute, Shenzhen 518057, P. R. China
| | - Shuangchen Ruan
- Key Laboratory of Advanced Optical Precision Manufacturing Technology of Guangdong Higher Education Institutes, Shenzhen Technology University, Shenzhen 518118, P. R. China
| | - Yu-Jia Zeng
- Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, P. R. China
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5
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Shang H, Dong H, Wu Y, Deng F, Liang X, Hu S, Shen S. Mechanical Control of Polar Patterns in Wrinkled Thin Films via Flexoelectricity. PHYSICAL REVIEW LETTERS 2024; 132:116201. [PMID: 38563913 DOI: 10.1103/physrevlett.132.116201] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/20/2023] [Revised: 11/17/2023] [Accepted: 02/09/2024] [Indexed: 04/04/2024]
Abstract
Intriguing topological polar structures in oxide nanofilms have drawn growing attention owing to their immense potential applications in nanoscale electronic devices. Here, we report a novel route to mechanically manipulate polar structures via flexoelectricity in wrinkled thin films. Our results present a flexoelectric polar transition from a nonpolar state to uniaxial polar stripes, biaxial meronlike or antimeronlike polar structures, and polar labyrinths by varying wrinkle morphologies. The evolution mechanisms and the outstanding mechanical tunability of these flexoelectric polar patterns were investigated theoretically and numerically. This strategy based on flexoelectricity for generating nontrivial polar structures will no longer rely on the superlattice structure and can be widely applicable to all centrosymmetric or noncentrosymmetric materials, providing a broader range of material and structure candidates for polar topologies.
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Affiliation(s)
- Hongxing Shang
- State Key Laboratory for Strength and Vibration of Mechanical Structures, School of Aerospace Engineering, Xi'an Jiaotong University, Xi'an 710049, China
| | - Huiting Dong
- State Key Laboratory for Strength and Vibration of Mechanical Structures, School of Aerospace Engineering, Xi'an Jiaotong University, Xi'an 710049, China
| | - Yihan Wu
- State Key Laboratory for Strength and Vibration of Mechanical Structures, School of Aerospace Engineering, Xi'an Jiaotong University, Xi'an 710049, China
| | - Feng Deng
- State Key Laboratory for Strength and Vibration of Mechanical Structures, School of Aerospace Engineering, Xi'an Jiaotong University, Xi'an 710049, China
| | - Xu Liang
- State Key Laboratory for Strength and Vibration of Mechanical Structures, School of Aerospace Engineering, Xi'an Jiaotong University, Xi'an 710049, China
| | - Shuling Hu
- State Key Laboratory for Strength and Vibration of Mechanical Structures, School of Aerospace Engineering, Xi'an Jiaotong University, Xi'an 710049, China
| | - Shengping Shen
- State Key Laboratory for Strength and Vibration of Mechanical Structures, School of Aerospace Engineering, Xi'an Jiaotong University, Xi'an 710049, China
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Chen YC, Chen PH, Liao YS, Chou JP, Wu JM. Defect Engineering Centrosymmetric 2D Material Flexocatalysts. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2024:e2401116. [PMID: 38456370 DOI: 10.1002/smll.202401116] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/12/2024] [Revised: 02/24/2024] [Indexed: 03/09/2024]
Abstract
In this study, the flexoelectric characteristics of 2D TiO2 nanosheets are examined. The theoretical calculations and experimental results reveal an excellent strain-induced flexoelectric potential (flexopotential) by an effective defect engineering strategy, which suppresses the recombination of electron-hole pairs, thus substantially improving the catalytic activity of the TiO2 nanosheets in the degradation of Rhodamine B dye and the hydrogen evolution reaction in a dark environment. The results indicate that strain-induced bandgap reduction enhances the catalytic activity of the TiO2 nanosheets. In addition, the TiO2 nanosheets degraded Rhodamine B, with kobs being ≈1.5 × 10-2 min-1 in dark, while TiO2 nanoparticles show only an adsorption effect. 2D TiO2 nanosheets achieve a hydrogen production rate of 137.9 µmol g-1 h-1 under a dark environment, 197% higher than those of TiO2 nanoparticles (70.1 µmol g-1 h-1 ). The flexopotential of the TiO2 nanosheets is enhanced by increasing the bending moment, with excellent flexopotential along the y-axis. Density functional theory is used to identify the stress-induced bandgap reduction and oxygen vacancy formation, which results in the self-dissociation of H2 O on the surface of the TiO in the dark. The present findings provide novel insights into the role of TiO2 flexocatalysis in electrochemical reactions.
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Affiliation(s)
- Yu-Ching Chen
- Department of Materials Science and Engineering, National Tsing Hua University, 101 Section 2 Kuang Fu Road, Hsinchu, 300, Taiwan
- Ph.D. Program in Prospective Functional Materials Industry, National Tsing Hua University, 101 Section 2 Kuang Fu Road, Hsinchu, 300, Taiwan
| | - Po-Han Chen
- Department of Materials Science and Engineering, National Tsing Hua University, 101 Section 2 Kuang Fu Road, Hsinchu, 300, Taiwan
| | - Yin-Song Liao
- Department of Materials Science and Engineering, National Tsing Hua University, 101 Section 2 Kuang Fu Road, Hsinchu, 300, Taiwan
- Tsing Hua Interdisciplinary Program, National Tsing Hua University, 101 Section 2 Kuang Fu Road, Hsinchu, 300, Taiwan
| | - Jyh-Pin Chou
- Department of Physics, National Changhua University of Education, No. 1 Jin-De Road, Changhua, 500, Taiwan
| | - Jyh Ming Wu
- Department of Materials Science and Engineering, National Tsing Hua University, 101 Section 2 Kuang Fu Road, Hsinchu, 300, Taiwan
- High Entropy Materials Center, National Tsing Hua University, 101 Section 2 Kuang Fu Road, Hsinchu, 300, Taiwan
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Wang JL, Zhao YF, Xu W, Zheng JD, Shao YP, Tong WY, Duan CG. Nanotube ferroelectric tunnel junctions with an ultrahigh tunneling electroresistance ratio. MATERIALS HORIZONS 2024; 11:1325-1333. [PMID: 38174937 DOI: 10.1039/d3mh02006a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2024]
Abstract
Low-dimensional ferroelectric tunnel junctions are appealing for the realization of nanoscale nonvolatile memory devices due to their inherent advantages of device miniaturization. Those based on current mechanisms have limitations, including low tunneling electroresistance (TER) effects and complex heterostructures. Here, we introduce an entirely new TER mechanism to construct a nanotube ferroelectric tunnel junction with ferroelectric nanotubes as the tunneling region. When rolling a ferroelectric monolayer into a nanotube, due to the coexistence of its intrinsic ferroelectric polarization with the flexoelectric polarization induced by bending, a metal-insulator transition occurs depending on the radiative polarization states. For the pristine monolayer, its out-of-plane polarization is tunable by an in-plane electric field, and the conducting states of the ferroelectric nanotube can thus be tuned between metallic and insulating states via axial electric means. Using α-In2Se3 as an example, our first-principles density functional theory calculations and nonequilibrium Green's function formalism confirm the feasibility of the TER mechanism and indicate an ultrahigh TER ratio that exceeds 9.9 × 1010% of the proposed nanotube ferroelectric tunnel junctions. Our findings provide a promising approach based on simple homogeneous structures for high density ferroelectric microelectric devices with excellent ON/OFF performance.
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Affiliation(s)
- Jiu-Long Wang
- Key Laboratory of Polar Materials and Devices (MOE), Ministry of Education, Department of Electronics, East China Normal University, Shanghai, 200241, China.
- Shanghai Center of Brain-inspired Intelligent Materials and Devices, East China Normal University, Shanghai 200241, China
| | - Yi-Feng Zhao
- Key Laboratory of Polar Materials and Devices (MOE), Ministry of Education, Department of Electronics, East China Normal University, Shanghai, 200241, China.
- Shanghai Center of Brain-inspired Intelligent Materials and Devices, East China Normal University, Shanghai 200241, China
| | - Wen Xu
- Key Laboratory of Polar Materials and Devices (MOE), Ministry of Education, Department of Electronics, East China Normal University, Shanghai, 200241, China.
- Shanghai Center of Brain-inspired Intelligent Materials and Devices, East China Normal University, Shanghai 200241, China
| | - Jun-Ding Zheng
- Key Laboratory of Polar Materials and Devices (MOE), Ministry of Education, Department of Electronics, East China Normal University, Shanghai, 200241, China.
- Shanghai Center of Brain-inspired Intelligent Materials and Devices, East China Normal University, Shanghai 200241, China
| | - Ya-Ping Shao
- Key Laboratory of Polar Materials and Devices (MOE), Ministry of Education, Department of Electronics, East China Normal University, Shanghai, 200241, China.
- Shanghai Center of Brain-inspired Intelligent Materials and Devices, East China Normal University, Shanghai 200241, China
| | - Wen-Yi Tong
- Key Laboratory of Polar Materials and Devices (MOE), Ministry of Education, Department of Electronics, East China Normal University, Shanghai, 200241, China.
- Shanghai Center of Brain-inspired Intelligent Materials and Devices, East China Normal University, Shanghai 200241, China
| | - Chun-Gang Duan
- Key Laboratory of Polar Materials and Devices (MOE), Ministry of Education, Department of Electronics, East China Normal University, Shanghai, 200241, China.
- Shanghai Center of Brain-inspired Intelligent Materials and Devices, East China Normal University, Shanghai 200241, China
- Collaborative Innovation Center of Extreme Optics, Shanxi University Taiyuan, Shanxi 030006, China
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Xia Y, Qian W, Yang Y. Advancements and Prospects of Flexoelectricity. ACS APPLIED MATERIALS & INTERFACES 2024; 16:9597-9613. [PMID: 38357861 DOI: 10.1021/acsami.3c16727] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/16/2024]
Abstract
The flexoelectric effect, as a novel form of the electromechanical coupling phenomenon, has attracted significant attention in the fields of materials science and electronic devices. It refers to the interaction between strain gradients and electric dipole moments or electric field intensity gradients and strain. In contrast to the traditional piezoelectric effect, the flexoelectric effect is not limited by material symmetry or the Curie temperature and exhibits a stronger effect at the nanoscale. The flexoelectric effect finds widespread applications ranging from energy harvesting to electronic device design. Utilizing the flexoelectric effect, enhanced energy harvesters, sensitive sensors, and high-performance wearable electronic devices can be developed. Additionally, the flexoelectric effect can be utilized to modulate the optoelectronic properties and physical characteristics of materials, holding the potential for significant applications in areas such as optoelectronic devices, energy storage devices, and flexible electronics. This review provides a comprehensive overview of the historical development, measurement of flexoelectric coefficients, enhancement mechanisms, and current research progress of the flexoelectric effect. Additionally, it offers a perspective on future prospects of the flexoelectric effect.
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Affiliation(s)
- Yanlong Xia
- CAS Center for Excellence in Nanoscience, Beijing Key Laboratory of Micro-nano Energy and Sensor, Beijing Institute of Nanoenergy and Nanosystems, Chinese Academy of Sciences, Beijing 101400, P. R. China
- School of Resources Environment and Materials, Center on Nanoenergy Research, Guangxi University, Nanning, Guangxi 530004, P. R. China
| | - Weiqi Qian
- CAS Center for Excellence in Nanoscience, Beijing Key Laboratory of Micro-nano Energy and Sensor, Beijing Institute of Nanoenergy and Nanosystems, Chinese Academy of Sciences, Beijing 101400, P. R. China
| | - Ya Yang
- CAS Center for Excellence in Nanoscience, Beijing Key Laboratory of Micro-nano Energy and Sensor, Beijing Institute of Nanoenergy and Nanosystems, Chinese Academy of Sciences, Beijing 101400, P. R. China
- School of Resources Environment and Materials, Center on Nanoenergy Research, Guangxi University, Nanning, Guangxi 530004, P. R. China
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Zhang Y, Huang J, Zhu M, Zhang Z, Nie K, Wang Z, Liao X, Shu L, Tian T, Wang Z, Lu Y, Fei L. Significant hydrogen generation via photo-mechanical coupling in flexible methylammonium lead iodide nanowires. Chem Sci 2024; 15:1782-1788. [PMID: 38303930 PMCID: PMC10829025 DOI: 10.1039/d3sc05434a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2023] [Accepted: 12/21/2023] [Indexed: 02/03/2024] Open
Abstract
The flexoelectric effect, which refers to the mechanical-electric coupling between strain gradient and charge polarization, should be considered for use in charge production for catalytically driving chemical reactions. We have previously revealed that halide perovskites can generate orders of higher magnitude flexoelectricity under the illumination of light than in the dark. In this study, we report the catalytic hydrogen production by photo-mechanical coupling involving the photoflexoelectric effect of flexible methylammonium lead iodide (MAPbI3) nanowires (NWs) in hydrogen iodide solution. Upon concurrent light illumination and mechanical vibration, large strain gradients were introduced in flexible MAPbI3 NWs, which subsequently induced significant hydrogen generation (at a rate of 756.5 μmol g-1 h-1, surpassing those values from either photo- or piezocatalysis of MAPbI3 nanoparticles). This photo-mechanical coupling strategy of mechanocatalysis, which enables the simultaneous utilization of multiple energy sources, provides a potentially new mechanism in mechanochemistry for highly efficient hydrogen production.
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Affiliation(s)
- Yucheng Zhang
- School of Physics and Materials Science, Nanchang University Nanchang 330031 China
| | - Jiawei Huang
- School of Physics and Materials Science, Nanchang University Nanchang 330031 China
| | - Mengya Zhu
- Department of Mechanical Engineering, City University of Hong Kong Kowloon Hong Kong SAR China
| | - Zhouyang Zhang
- Department of Mechanical Engineering, City University of Hong Kong Kowloon Hong Kong SAR China
| | - Kaiqi Nie
- Institute of High Energy Physics, Chinese Academy of Sciences Beijing 100049 China
| | - Zhiguo Wang
- School of Physics and Materials Science, Nanchang University Nanchang 330031 China
| | - Xiaxia Liao
- School of Physics and Materials Science, Nanchang University Nanchang 330031 China
| | - Longlong Shu
- School of Physics and Materials Science, Nanchang University Nanchang 330031 China
| | - Tingfang Tian
- School of Physics and Materials Science, Nanchang University Nanchang 330031 China
| | - Zhao Wang
- Hubei Key Laboratory of Micro- & Nano electronic Materials and Devices, School of Microelectronics, Hubei University Wuhan 430062 China
| | - Yang Lu
- Department of Mechanical Engineering, The University of Hong Kong Hong Kong SAR China
| | - Linfeng Fei
- School of Physics and Materials Science, Nanchang University Nanchang 330031 China
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Qvotrup C, Liu Z, Papon C, Wieck AD, Ludwig A, Midolo L. Curved GaAs cantilever waveguides for the vertical coupling to photonic integrated circuits. OPTICS EXPRESS 2024; 32:3723-3734. [PMID: 38297587 DOI: 10.1364/oe.510799] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2023] [Accepted: 12/19/2023] [Indexed: 02/02/2024]
Abstract
We report the nanofabrication and characterization of optical spot-size converter couplers based on curved GaAs cantilever waveguides. Using the stress mismatch between the GaAs substrate and deposited Cr-Ni-Au strips, single-mode waveguides can be bent out-of-plane in a controllable manner. A stable and vertical orientation of the out-coupler is achieved by locking the spot-size converter at a fixed 90 ∘ angle via short-range forces. The optical transmission is characterized as a function of temperature and polarization, resulting in a broad-band chip-to-fiber coupling extending over 150 nm wavelength bandwidth at cryogenic temperatures, with the lower bound for the coupling efficiency into the TE mode being 16±2% in the interval 900-1050 nm. The methods reported here are fully compatible with quantum photonic integrated circuit technology with quantum dot emitters, and open opportunities to design novel photonic devices with enhanced functionality.
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Wang YX, Li JG, Seifert G, Chang K, Zhang DB. Giant Flexoelectricity in Bent Semiconductor Thinfilm. NANO LETTERS 2024; 24:411-416. [PMID: 38146896 DOI: 10.1021/acs.nanolett.3c04220] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2023]
Abstract
We elucidate the flexoelectricity of semiconductors in the high strain gradient regime, the underlying mechanism of which is less understood. By using the generalized Bloch theorem, we uncover a strong flexoelectric-like effect in bent thinfilms of Si and Ge due to a high-strain-gradient-induced band gap closure. We show that an unusual type-II band alignment is formed between the compressed and elongated sides of the bent film. Therefore, upon the band gap closure, electrons transfer from the compressed side to the elongated side to reach the thermodynamic equilibrium, leading to a pronounced change of polarization along the film thickness dimension. The obtained transverse flexoelectric coefficients are unexpectedly high with a quadratic dependence on the film thickness. This new mechanism is extendable to other semiconductor materials with moderate energy gaps. Our findings have important implications for the future applications of flexoelectricity in semiconductor materials.
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Affiliation(s)
- Ya-Xun Wang
- College of Nuclear Science and Technology, Beijing Normal University, Beijing 100875, P.R. China
- Department of Physics, Beijing Normal University, Beijing 100875, P.R. China
| | - Jian-Gao Li
- College of Nuclear Science and Technology, Beijing Normal University, Beijing 100875, P.R. China
- Department of Physics, Beijing Normal University, Beijing 100875, P.R. China
| | - Gotthard Seifert
- Theoretische Chemie, Technische Universitat Dresden, Dresden D-01062, Germany
| | - Kai Chang
- School of Physics, Zhejiang University, Hangzhou 310027, P. R. China
| | - Dong-Bo Zhang
- Department of Physics, Beijing Normal University, Beijing 100875, P.R. China
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12
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Zhong L, Li X, Pu Y, Wang M, Zhan C, Xiao X. Tunable Li-ion diffusion properties in MoSSe bilayer anodes by strain gradient. Phys Chem Chem Phys 2024; 26:1030-1038. [PMID: 38093680 DOI: 10.1039/d3cp04650h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2024]
Abstract
Layered MoSSe nanostructures have been shown as potential candidates for the anode of lithium ion (Li-ion) batteries. The diffusion properties are generally critical to the performance of ionic batteries. The possible migration paths and associated diffusion energy barriers of Li-ions are systematically explored in MoSSe bilayer anodes with different stacking patterns by means of first-principles simulations. It is found that the diffusion properties strongly depend on interfaces and stacking patterns. Furthermore, the simulation results show that the diffusion energy barrier (and thus the diffusion coefficient) can be significantly reduced (enlarged) by applying a positive strain gradient, while increased (reduced) by applying a negative one. For example, the diffusion coefficient is increased roughly by 100 times relative to that of the pristine one when subjected to a strain gradient of 0.02 Å-1. In particular, it is found that less maximum strain is required in the strain-gradient than the uniform strain in order to achieve the same diffusion energy barrier. By careful analysis, the underlying mechanism can be attributed to the flexo-diffusion coupling effect. The coupling strength is characterized by the so-called flexo-diffusion coupling constant which is also calculated for each simulation model. The results of this work may provide valuable insights into the design and optimization of the anodes of ionic batteries.
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Affiliation(s)
- Li Zhong
- School of Civil Engineering, Hefei University of Technology, Anhui 230009, China.
| | - Xiaobao Li
- School of Civil Engineering, Hefei University of Technology, Anhui 230009, China.
| | - Yuxue Pu
- School of Civil Engineering, Hefei University of Technology, Anhui 230009, China.
| | - Meiqin Wang
- School of Civil Engineering, Hefei University of Technology, Anhui 230009, China.
| | - Chunxiao Zhan
- School of Civil Engineering, Hefei University of Technology, Anhui 230009, China.
| | - Xinle Xiao
- Anhui Engineering Research Center of Highly Reactive Micro-Nano Powders, Chizhou University, Anhui 247000, China.
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13
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Marin Angel JC, Kyu T. Flexoelectric Ionic Liquid-Grafted Triblock Copolymers for Energy Harvesting under Flexural Deformation. ACS APPLIED MATERIALS & INTERFACES 2023. [PMID: 38033309 DOI: 10.1021/acsami.3c13793] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/02/2023]
Abstract
The goal of the present article is to develop flexoelectric polyelectrolyte elastomers for energy harvesting based on a poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol) dimethacrylate (PEG-b-PPG-b-PEG-DMA) triblock grafted with an ionic liquid (IL) such as allylmethylimidazolium bis(trifluoromethane sulfonyl) imide (AMIMTFSI). The IL-grafted triblock copolymer network possesses a balance of reasonably good ionic conductivity and high ion polarization during cantilever bending. Of particular importance is the achievement of high flexoelectric coefficients in some flexoelectric polyelectrolyte elastomer (FPE) compositions reaching 1368 μC/m at ambient temperature during mechanical deformation under intermittent square-wave bending mode. With the addition of a 10 wt % lithium bis(trifluoromethane sulfonyl) imide (LiTFSI) salt, the flexoelectric coefficient further improved to 1737 μC/m, which is the highest among all piezoelectric and flexoelectric materials hitherto reported, and thus it opens a new opportunity for clean energy harvesting from a vibrating natural environment.
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Affiliation(s)
- Juan C Marin Angel
- School of Polymer Science and Polymer Engineering, University of Akron, Akron, Ohio 44325, United States
| | - Thein Kyu
- School of Polymer Science and Polymer Engineering, University of Akron, Akron, Ohio 44325, United States
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14
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Liu Y, Morozovska AN, Ghosh A, Kelley KP, Eliseev EA, Yao J, Liu Y, Kalinin S. Stress and Curvature Effects in Layered 2D Ferroelectric CuInP 2S 6. ACS NANO 2023; 17:22004-22014. [PMID: 37917122 DOI: 10.1021/acsnano.3c08603] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/03/2023]
Abstract
Nanoscale ferroelectric 2D materials offer the opportunity to investigate curvature and strain effects on materials functionalities. Among these, CuInP2S6 (CIPS) has attracted tremendous research interest in recent years due to combination of room temperature ferroelectricity, scalability to a few layers thickness, and ferrielectric properties due to coexistence of 2 polar sublattices. Here, we explore the local curvature and strain effect on polarization in CIPS via piezoresponse force microscopy and spectroscopy. To explain the observed behaviors and decouple the curvature and strain effects in 2D CIPS, we introduce the finite element Landau-Ginzburg-Devonshire model, revealing strong changes in hysteresis characteristics in regions subjected to tensile and compressive strain. The piezoresponse force microscopy (PFM) results show that bending induces ferrielectric domains in CIPS, and the polarization-voltage hysteresis loops differ in bending and nonbending regions. These studies offer insights into the fabrication of curvature-engineered nanoelectronic devices.
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Affiliation(s)
- Yongtao Liu
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, United States
| | - Anna N Morozovska
- Institute of Physics, National Academy of Sciences of Ukraine, 46, pr. Nauky, 03028 Kyiv, Ukraine
| | - Ayana Ghosh
- Computational Sciences and Engineering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, United States
| | - Kyle P Kelley
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, United States
| | - Eugene A Eliseev
- Institute for Problems of Materials Science, National Academy of Sciences of Ukraine, 3, Krjijanovskogo, 03142 Kyiv, Ukraine
| | - Jinyuan Yao
- Department of Physics, Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Ying Liu
- Department of Physics, Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Sergei Kalinin
- Department of Materials Science and Engineering, The University of Tennessee, Knoxville, Tennessee 37996, United States
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15
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Jiang Y, Yan D, Wang J, Shao LH, Sharma P. The giant flexoelectric effect in a luffa plant-based sponge for green devices and energy harvesters. Proc Natl Acad Sci U S A 2023; 120:e2311755120. [PMID: 37748078 PMCID: PMC10556619 DOI: 10.1073/pnas.2311755120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2023] [Accepted: 08/22/2023] [Indexed: 09/27/2023] Open
Abstract
Soft materials that can produce electrical energy under mechanical stimulus or deform significantly via moderate electrical fields are important for applications ranging from soft robotics to biomedical science. Piezoelectricity, the property that would ostensibly promise such a realization, is notably absent from typical soft matter. Flexoelectricity is an alternative form of electromechanical coupling that universally exists in all dielectrics and can generate electricity under nonuniform deformation such as flexure and conversely, a deformation under inhomogeneous electrical fields. The flexoelectric coupling effect is, however, rather modest for most materials and thus remains a critical bottleneck. In this work, we argue that a significant emergent flexoelectric response can be obtained by leveraging a hierarchical porous structure found in biological materials. We experimentally illustrate our thesis for a natural dry luffa vegetable-based sponge and demonstrate an extraordinarily large mass- and deformability-specific electromechanical response with the highest-density-specific equivalent piezoelectric coefficient known for any material (50 times that of polyvinylidene fluoride and more than 10 times that of lead zirconate titanate). Finally, we demonstrate the application of the fabricated natural sponge as green, biodegradable flexible smart devices in the context of sensing (e.g., for speech, touch pressure) and electrical energy harvesting.
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Affiliation(s)
- Yudi Jiang
- National Key Laboratory of Strength and Structural Integrity, Institute of Solid Mechanics, School of Aeronautic Science and Engineering, Beihang University, Beijing100191, People’s Republic of China
| | - Dongze Yan
- National Key Laboratory of Strength and Structural Integrity, Institute of Solid Mechanics, School of Aeronautic Science and Engineering, Beihang University, Beijing100191, People’s Republic of China
| | - Jianxiang Wang
- Department of Mechanics and Engineering Science, College of Engineering, Peking University, Beijing100871, People’s Republic of China
- Center for Applied Physics and Technology, Peking University, Beijing100871, People’s Republic of China
- Collaborative Innovation Center of Inertial Fusion Sciences and Applications, Ministry of Education, Peking University, Beijing100871, People’s Republic of China
| | - Li-Hua Shao
- National Key Laboratory of Strength and Structural Integrity, Institute of Solid Mechanics, School of Aeronautic Science and Engineering, Beihang University, Beijing100191, People’s Republic of China
| | - Pradeep Sharma
- Department of Mechanical Engineering, University of Houston, Houston, TX77204
- Department of Physics, University of Houston, Houston, TX77204
- Materials Science and Engineering Program, University of Houston, Houston, TX77204
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16
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Guzmán-Verri GG, Liang CH, Littlewood PB. Lamellar Fluctuations Melt Ferroelectricity. PHYSICAL REVIEW LETTERS 2023; 131:046801. [PMID: 37566848 DOI: 10.1103/physrevlett.131.046801] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/21/2022] [Revised: 04/24/2023] [Accepted: 06/25/2023] [Indexed: 08/13/2023]
Abstract
We consider a standard Ginzburg-Landau model of a ferroelectric whose electrical polarization is coupled to gradients of elastic strain. At the harmonic level, such flexoelectric interaction is known to hybridize acoustic and optic phonon modes and lead to phases with modulated lattice structures that precede the state with spontaneously broken inversion symmetry. Here, we use the self-consistent phonon approximation to calculate the effects of thermal and quantum polarization fluctuations on the bare hybridized modes to show that such long-range modulated order is unstable at all temperatures. We discuss the implications for the nearly ferroelectric SrTiO_{3} and KTaO_{3}, and we propose that these systems are melted versions of an underlying modulated state that is dominated by nonzero momentum thermal fluctuations except at the very lowest temperatures.
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Affiliation(s)
- G G Guzmán-Verri
- Centro de Investigación en Ciencia e Ingeniería de Materiales, Universidad de Costa Rica, San José 11501, Costa Rica; Escuela de Física, Universidad de Costa Rica, San José 11501, Costa Rica; and Department of Materials Science and Metallurgy, University of Cambridge, Cambridge CB3 0FS, United Kingdom
| | - C H Liang
- Pritzker School of Molecular Engineering, University of Chicago, Chicago, Illinois 60637, USA; James Franck Institute, University of Chicago, Chicago, Illinois 60637, USA; and Argonne National Laboratory, Materials Science Division, Lemont, Illinois 60439, USA
| | - P B Littlewood
- James Franck Institute, University of Chicago, Chicago, Illinois 60637, USA
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17
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Xia Y, Dan H, Ji Y, Han X, Wang Y, Hu Q, Yang Y. Flexible BaTiO 3 Thin Film-Based Coupled Nanogenerator for Simultaneously Scavenging Light and Vibration Energies. ACS APPLIED MATERIALS & INTERFACES 2023; 15:23226-23235. [PMID: 37129586 DOI: 10.1021/acsami.3c02494] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Ferroelectric materials have a variety of properties, such as piezoelectricity, pyroelectricity, and the ferroelectric photovoltaic effect, which enable them to obtain electrical energy from various external stimuli. Here, we report a coupled nanogenerator based on flexible BTO ferroelectric films with a cantilevered beam structure. It combines the photovoltaic and flexoelectric effects in a ferroelectric materials-based coupled nanogenerator for simultaneously scavenging vibration energy and light energy, thus improving energy scavenging performance. As compared with the photovoltaic effect individually, simultaneous vibration and light illumination under a light intensity of 57 mW/cm2 at 405 nm can produce a photo-flexoelectric coupling current of 85 nA, where the current peak has been enhanced by 121%. Due to the photo-flexoelectric coupling effect, the device has outstanding charging performance, where a 4.7 μF capacitor can be charged to 60 mV in 150 s. These devices have potential applications in multi-energy scavenging and self-powered sensors.
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Affiliation(s)
- Yanlong Xia
- School of Resources Environment and Materials, Center on Nanoenergy Research, Guangxi University, Nanning, Guangxi, 530004, P. R China
- CAS Center for Excellence in Nanoscience, Beijing Key Laboratory of Micro-nano Energy and Sensor, Beijing Institute of Nanoenergy and Nanosystems, Chinese Academy of Sciences, Beijing 101400, P. R. China
| | - Huiyu Dan
- School of Resources Environment and Materials, Center on Nanoenergy Research, Guangxi University, Nanning, Guangxi, 530004, P. R China
- CAS Center for Excellence in Nanoscience, Beijing Key Laboratory of Micro-nano Energy and Sensor, Beijing Institute of Nanoenergy and Nanosystems, Chinese Academy of Sciences, Beijing 101400, P. R. China
| | - Yun Ji
- CAS Center for Excellence in Nanoscience, Beijing Key Laboratory of Micro-nano Energy and Sensor, Beijing Institute of Nanoenergy and Nanosystems, Chinese Academy of Sciences, Beijing 101400, P. R. China
| | - Xiao Han
- CAS Center for Excellence in Nanoscience, Beijing Key Laboratory of Micro-nano Energy and Sensor, Beijing Institute of Nanoenergy and Nanosystems, Chinese Academy of Sciences, Beijing 101400, P. R. China
| | - Yuanhao Wang
- SUSTech Engineering Innovation Center, School of Environmental Science and Engineering, Southern University of Science and Technology, Shenzhen, Guangdong 518055, P. R. China
| | - Qing Hu
- SUSTech Engineering Innovation Center, School of Environmental Science and Engineering, Southern University of Science and Technology, Shenzhen, Guangdong 518055, P. R. China
| | - Ya Yang
- School of Resources Environment and Materials, Center on Nanoenergy Research, Guangxi University, Nanning, Guangxi, 530004, P. R China
- CAS Center for Excellence in Nanoscience, Beijing Key Laboratory of Micro-nano Energy and Sensor, Beijing Institute of Nanoenergy and Nanosystems, Chinese Academy of Sciences, Beijing 101400, P. R. China
- School of Nanoscience and Technology, University of Chinese Academy of Sciences, Beijing 100049, P. R. China
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18
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Luo Y, Pu T, Liu H. Research on Output Characteristics of Microscale BST Laminate Structure Based on Mixed Finite Element Method. MICROMACHINES 2023; 14:755. [PMID: 37420988 DOI: 10.3390/mi14040755] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/06/2023] [Revised: 03/26/2023] [Accepted: 03/27/2023] [Indexed: 07/09/2023]
Abstract
The flexoelectric effect, which is sensitive to size, refers to the phenomenon of coupling between the strain gradient and electrical polarization and involves higher-order derivatives of physical quantities such as displacement, and the analytical process is complicated and difficult. Therefore, in this paper, a mixed finite element method is developed considering the effects of size effect and flexoelectric effect on the electromechanical coupling behavior of microscale flexoelectric materials. Based on the theoretical model of enthalpy density and the modified couple stress theory, the theoretical model and finite element model of microscale flexoelectric effect are established, and the Lagrange multiplier is used to coordinate the higher-order derivative relationship between the displacement field and its gradient, and the C1 continuous quadrilateral 8-node (displacement and potential) and 4-node (displacement gradient and Lagrange multipliers) flexoelectric mixed element. By comparing the numerical calculation results and analytical solutions of the electrical output characteristics of the microscale BST/PDMS laminated cantilever structure, it is proved that the mixed finite element method designed in this paper is an effective tool for studying the electromechanical coupling behavior of flexoelectric materials.
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Affiliation(s)
- Ying Luo
- Faculty of Civil Engineering and Mechanics, Jiangsu University, Zhenjiang 212013, China
- National Center for International Research on Structural Health Management of Critical Components, Jiangsu University, Zhenjiang 212013, China
| | - Tian Pu
- Faculty of Civil Engineering and Mechanics, Jiangsu University, Zhenjiang 212013, China
- National Center for International Research on Structural Health Management of Critical Components, Jiangsu University, Zhenjiang 212013, China
| | - Hongguang Liu
- Faculty of Civil Engineering and Mechanics, Jiangsu University, Zhenjiang 212013, China
- National Center for International Research on Structural Health Management of Critical Components, Jiangsu University, Zhenjiang 212013, China
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19
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Abstract
The piezoelectric effect was discovered over a century ago, and it has found wide application since that time. The direct piezoelectric effect is the production of charge upon application of force to a material, and the converse piezoelectric effect is a change in the material dimension(s) upon the application of a potential. To date, piezoelectric effects have been observed only in solid-phase materials. We report here the observation of the direct piezoelectric effect in room-temperature ionic liquids (RTILs). The RTILs 1-butyl-3-methyl imidazolium bis(trifluoromethyl-sulfonyl)imide (BMIM+TFSI-) and 1-hexyl-3-methyl imidazolium bis(trifluoromethylsulfonyl) imide (HMIM+TFSI-) produce a potential upon the application of force when confined in a cell, with the magnitude of the potential being directly proportional to the force applied. The effect is one order of magnitude smaller than that seen in quartz. This is the first report to our knowledge of the direct piezoelectric effect in a neat liquid. Its discovery has fundamental implications about the organization and dynamics in ionic liquids and invites theoretical treatment.
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Affiliation(s)
- Md Iqbal Hossain
- Michigan State University, Department of Chemistry, 578 S. Shaw Lane, East Lansing, Michigan 48824, United States
| | - G J Blanchard
- Michigan State University, Department of Chemistry, 578 S. Shaw Lane, East Lansing, Michigan 48824, United States
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20
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Yasui K. Critical Roles of Impurities and Imperfections in Various Phases of Materials. MATERIALS (BASEL, SWITZERLAND) 2023; 16:ma16041612. [PMID: 36837241 PMCID: PMC9960772 DOI: 10.3390/ma16041612] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/19/2023] [Revised: 02/08/2023] [Accepted: 02/13/2023] [Indexed: 06/01/2023]
Abstract
In many materials, impurities and imperfections play a critical role on the physical and chemical properties. In the present review, some examples of such materials are discussed. A bulk nanobubble (an ultrafine bubble) is stabilized against dissolution by hydrophobic impurities attached to the bubble surface. An acoustic cavitation threshold in various liquids decreases significantly by the presence of impurities such as solid particles, etc. The strength of brittle ceramics is determined by the size and number of pre-existing microcracks (imperfections) in the specimen. The size effect of a BaTiO3 nanocrystal is influenced by the amount and species of adsorbates (impurities) on its surface as adsorbate-induced charge-screening changes the free energy. The dielectric constant of an assembly of BaTiO3 nanocubes is influenced by a small tilt angle (imperfection) between two attached nanocubes, which induces strain inside a nanocube, and is also influenced by the spatial strain-relaxation due to defects and dislocations (imperfections), resulting in flexoelectric polarization.
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Affiliation(s)
- Kyuichi Yasui
- National Institute of Advanced Industrial Science and Technology (AIST), Nagoya 463-8560, Japan
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21
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Acevedo-Salas U, Croes B, Zhang Y, Cregut O, Dorkenoo KD, Kirbus B, Singh E, Beccard H, Rüsing M, Eng LM, Hertel R, Eliseev EA, Morozovska AN, Cherifi-Hertel S. Impact of 3D Curvature on the Polarization Orientation in Non-Ising Domain Walls. NANO LETTERS 2023; 23:795-803. [PMID: 36668991 DOI: 10.1021/acs.nanolett.2c03579] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Ferroelectric domain boundaries are quasi-two-dimensional functional interfaces with high prospects for nanoelectronic applications. Despite their reduced dimensionality, they can exhibit complex non-Ising polarization configurations and unexpected physical properties. Here, the impact of the three-dimensional (3D) curvature on the polarization profile of nominally uncharged 180° domain walls in LiNbO3 is studied using second-harmonic generation microscopy and 3D polarimetry analysis. Correlations between the domain-wall curvature and the variation of its internal polarization unfold in the form of modulations of the Néel-like character, which we attribute to the flexoelectric effect. While the Néel-like character originates mainly from the tilting of the domain wall, the internal polarization adjusts its orientation due to the synergetic upshot of dipolar and monopolar bound charges and their variation with the 3D curvature. Our results show that curved interfaces in solid crystals may offer a rich playground for tailoring nanoscale polar states.
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Affiliation(s)
- Ulises Acevedo-Salas
- Université de Strasbourg, CNRS, Institut de Physique et Chimie des Matériaux de Strasbourg, UMR 7504, 67034Strasbourg, France
| | - Boris Croes
- Université de Strasbourg, CNRS, Institut de Physique et Chimie des Matériaux de Strasbourg, UMR 7504, 67034Strasbourg, France
| | - Yide Zhang
- Université de Strasbourg, CNRS, Institut de Physique et Chimie des Matériaux de Strasbourg, UMR 7504, 67034Strasbourg, France
| | - Olivier Cregut
- Université de Strasbourg, CNRS, Institut de Physique et Chimie des Matériaux de Strasbourg, UMR 7504, 67034Strasbourg, France
| | - Kokou Dodzi Dorkenoo
- Université de Strasbourg, CNRS, Institut de Physique et Chimie des Matériaux de Strasbourg, UMR 7504, 67034Strasbourg, France
| | - Benjamin Kirbus
- Institute of Applied Physics, Technische Universität Dresden, 01062Dresden, Germany
| | - Ekta Singh
- Institute of Applied Physics, Technische Universität Dresden, 01062Dresden, Germany
| | - Henrik Beccard
- Institute of Applied Physics, Technische Universität Dresden, 01062Dresden, Germany
| | - Michael Rüsing
- Institute of Applied Physics, Technische Universität Dresden, 01062Dresden, Germany
| | - Lukas M Eng
- Institute of Applied Physics, Technische Universität Dresden, 01062Dresden, Germany
- ct.qmat: Würzburg-Dresden Cluster of Excellence - EXC 2147, TU Dresden, https://www.ctqmat.de/
| | - Riccardo Hertel
- Université de Strasbourg, CNRS, Institut de Physique et Chimie des Matériaux de Strasbourg, UMR 7504, 67034Strasbourg, France
| | - Eugene A Eliseev
- Institute for Problems of Materials Science, National Academy of Sciences of Ukraine, Krjijanovskogo 3, 03142Kyiv, Ukraine
| | - Anna N Morozovska
- Institute of Physics, National Academy of Sciences of Ukraine, 46, pr. Nauky, 03028Kyiv, Ukraine
| | - Salia Cherifi-Hertel
- Université de Strasbourg, CNRS, Institut de Physique et Chimie des Matériaux de Strasbourg, UMR 7504, 67034Strasbourg, France
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22
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Unnikrishnan GK, Sharma S, Pathak H, Chauhan VS, Jain SC. Extended Isogeometric Analysis of Cracked Piezoelectric Materials in the Presence of Flexoelectricity. ADVANCED THEORY AND SIMULATIONS 2023. [DOI: 10.1002/adts.202200846] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Affiliation(s)
- Gokul Krishna Unnikrishnan
- School of Mechanical and Materials Engineering Indian Institute of Technology Mandi Himachal Pradesh 175075 India
| | - Saurav Sharma
- Faculty of Mechanical Maritime and Materials Engineering Delft University of Technology Mekelweg 2 CD Delft 2628 The Netherlands
| | - Himanshu Pathak
- School of Mechanical and Materials Engineering Indian Institute of Technology Mandi Himachal Pradesh 175075 India
| | - Vishal Singh Chauhan
- School of Mechanical and Materials Engineering Indian Institute of Technology Mandi Himachal Pradesh 175075 India
| | - Satish Chandra Jain
- School of Mechanical and Materials Engineering Indian Institute of Technology Mandi Himachal Pradesh 175075 India
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23
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Yeo Y, Hwang SY, Yeo J, Kim J, Jang J, Park HS, Kim YJ, Le DD, Song K, Kim M, Ryu S, Choi SY, Yang CH. Configurable Crack Wall Conduction in a Complex Oxide. NANO LETTERS 2023; 23:398-406. [PMID: 36595450 DOI: 10.1021/acs.nanolett.2c02640] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Mobile defects in solid-state materials play a significant role in memristive switching and energy-efficient neuromorphic computation. Techniques for confining and manipulating point defects may have great promise for low-dimensional memories. Here, we report the spontaneous gathering of oxygen vacancies at strain-relaxed crack walls in SrTiO3 thin films grown on DyScO3 substrates as a result of flexoelectricity. We found that electronic conductance at the crack walls was enhanced compared to the crack-free region, by a factor of 104. A switchable asymmetric diode-like feature was also observed, and the mechanism is discussed, based on the electrical migration of oxygen vacancy donors in the background of Sr-deficient acceptors forming n+-n or n-n+ junctions. By tracing the temporal relaxations of surface potential and lattice expansion of a formed region, we determine the diffusivity of mobile defects in crack walls to be 1.4 × 10-16 cm2/s, which is consistent with oxygen vacancy kinetics.
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Affiliation(s)
- Youngki Yeo
- Department of Physics, Korea Advanced Institute of Science and Technology, Daejeon34141, Republic of Korea
- Center for Lattice Defectronics, Korea Advanced Institute of Science and Technology, Daejeon34141, Republic of Korea
| | - Soo-Yoon Hwang
- Department of Materials Science and Engineering, Pohang University of Science and Technology, Pohang37673, Republic of Korea
| | - Jinwook Yeo
- Department of Mechanical Engineering, Korea Advanced Institute of Science and Technology, Daejeon34141, Republic of Korea
| | - Jihun Kim
- Department of Physics, Korea Advanced Institute of Science and Technology, Daejeon34141, Republic of Korea
- Center for Lattice Defectronics, Korea Advanced Institute of Science and Technology, Daejeon34141, Republic of Korea
| | - Jinhyuk Jang
- Department of Materials Science and Engineering, Pohang University of Science and Technology, Pohang37673, Republic of Korea
| | - Heung-Sik Park
- Department of Physics, Korea Advanced Institute of Science and Technology, Daejeon34141, Republic of Korea
- Center for Lattice Defectronics, Korea Advanced Institute of Science and Technology, Daejeon34141, Republic of Korea
| | - Yong-Jin Kim
- Department of Physics, Korea Advanced Institute of Science and Technology, Daejeon34141, Republic of Korea
- Center for Lattice Defectronics, Korea Advanced Institute of Science and Technology, Daejeon34141, Republic of Korea
| | - Duc Duy Le
- Department of Physics, Korea Advanced Institute of Science and Technology, Daejeon34141, Republic of Korea
- Center for Lattice Defectronics, Korea Advanced Institute of Science and Technology, Daejeon34141, Republic of Korea
| | - Kyung Song
- Department of Materials Analysis and Evaluation, Korea Institute of Materials Science, Changwon51508, Republic of Korea
| | - Moonhong Kim
- Division of Mechanical Engineering, Korea Maritime & Ocean University, 727 Taejong-ro, Yeongdo-gu, Busan49112, South Korea
| | - Seunghwa Ryu
- Department of Mechanical Engineering, Korea Advanced Institute of Science and Technology, Daejeon34141, Republic of Korea
| | - Si-Young Choi
- Department of Materials Science and Engineering, Pohang University of Science and Technology, Pohang37673, Republic of Korea
| | - Chan-Ho Yang
- Department of Physics, Korea Advanced Institute of Science and Technology, Daejeon34141, Republic of Korea
- Center for Lattice Defectronics, Korea Advanced Institute of Science and Technology, Daejeon34141, Republic of Korea
- KAIST Institute for the NanoCentury, Korea Advanced Institute of Science and Technology, Yuseong-gu, Daejeon34141, Republic of Korea
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24
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Ruiz VM, Olmos D, González-Benito J. PVDF/MWCNT nanocomposites with complex configurations prepared by solution blow spinning and their flexoelectric responses. POLYMER 2023. [DOI: 10.1016/j.polymer.2022.125669] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
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25
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Free Vibration Behaviors of Nanoplates Resting on Viscoelastic Medium. ARABIAN JOURNAL FOR SCIENCE AND ENGINEERING 2022. [DOI: 10.1007/s13369-022-07500-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/07/2022]
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26
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A Comprehensive Study on Mechanical Responses of Non-uniform Thickness Piezoelectric Nanoplates Taking into Account the Flexoelectric Effect. ARABIAN JOURNAL FOR SCIENCE AND ENGINEERING 2022. [DOI: 10.1007/s13369-022-07362-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
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27
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Wang J, Fang H, Nie F, Chen Y, Tian G, Shi C, He B, Lü W, Zheng L. Domain Switching in BaTiO 3 Films Induced by an Ultralow Mechanical Force. ACS APPLIED MATERIALS & INTERFACES 2022; 14:48917-48925. [PMID: 36281808 DOI: 10.1021/acsami.2c15062] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Low-energy switching of ferroelectrics has been intensively studied for energy-efficient nanoelectronics. Mechanical force is considered as a low-energy consumption technique for switching the polarization of ferroelectric films due to the flexoelectric effect. Reduced threshold force is always desirable for the considerations of energy saving, easy domain manipulation, and sample surface protection. In this work, the mechanical switching behaviors of BaTiO3/SrRuO3 epitaxial heterostructure grown on Nb:SrTiO3 (001) substrate are reported. Domain switching is found to be induced by an extremely low tip force of 320 nN (estimated pressure ∼0.09 GPa), which is the lowest value ever reported. This low mechanical threshold is attributed to the small compressive strain, the low oxygen vacancy concentration in BaTiO3 film, and the high conductivity of the SrRuO3 electrode. The flexoelectricity under both perpendicular mechanical load (point measurement) and sliding load (scanning measurement) are investigated. The sliding mode shows a much stronger flexoelectric field for its strong trailing field. The mechanical written domains show several advantages in comparison with the electrically written ones: low charge injection, low energy consumption, high density, and improved stability. The ultralow-pressure switching in this work presents opportunities for next-generation low-energy and high-density memory electronics.
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Affiliation(s)
- Jie Wang
- Functional Materials and Acousto-Optic Instruments Institute, School of Instrumentation Science and Engineering, Harbin Institute of Technology, Harbin150080, China
- Spintronics Institute, School of Physics and Technology, University of Jinan, Jinan250022, China
| | - Hong Fang
- Functional Materials and Acousto-Optic Instruments Institute, School of Instrumentation Science and Engineering, Harbin Institute of Technology, Harbin150080, China
- Spintronics Institute, School of Physics and Technology, University of Jinan, Jinan250022, China
| | - Fang Nie
- School of Physics, State Key Laboratory of Crystal Materials, Shandong University, Jinan250100, China
| | - Yanan Chen
- Spintronics Institute, School of Physics and Technology, University of Jinan, Jinan250022, China
| | - Gang Tian
- School of Physics, State Key Laboratory of Crystal Materials, Shandong University, Jinan250100, China
| | - Chaoqun Shi
- Spintronics Institute, School of Physics and Technology, University of Jinan, Jinan250022, China
| | - Bin He
- Spintronics Institute, School of Physics and Technology, University of Jinan, Jinan250022, China
| | - Weiming Lü
- Functional Materials and Acousto-Optic Instruments Institute, School of Instrumentation Science and Engineering, Harbin Institute of Technology, Harbin150080, China
- Spintronics Institute, School of Physics and Technology, University of Jinan, Jinan250022, China
| | - Limei Zheng
- School of Physics, State Key Laboratory of Crystal Materials, Shandong University, Jinan250100, China
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28
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Yasui K. Merits and Demerits of ODE Modeling of Physicochemical Systems for Numerical Simulations. MOLECULES (BASEL, SWITZERLAND) 2022; 27:molecules27185860. [PMID: 36144593 PMCID: PMC9505051 DOI: 10.3390/molecules27185860] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/28/2022] [Revised: 09/02/2022] [Accepted: 09/07/2022] [Indexed: 11/25/2022]
Abstract
In comparison with the first-principles calculations mostly using partial differential equations (PDEs), numerical simulations with modeling by ordinary differential equations (ODEs) are sometimes superior in that they are computationally more economical and that important factors are more easily traced. However, a demerit of ODE modeling is the need of model validation through comparison with experimental data or results of the first-principles calculations. In the present review, examples of ODE modeling are reviewed such as sonochemical reactions inside a cavitation bubble, oriented attachment of nanocrystals, dynamic response of flexoelectric polarization, ultrasound-assisted sintering, and dynamics of a gas parcel in a thermoacoustic engine.
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Affiliation(s)
- Kyuichi Yasui
- National Institute of Advanced Industrial Science and Technology (AIST), Nagoya 463-8560, Japan
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29
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Xia Y, Ji Y, Liu Y, Wu L, Yang Y. Controllable Piezo-flexoelectric Effect in Ferroelectric Ba 0.7Sr 0.3TiO 3 Materials for Harvesting Vibration Energy. ACS APPLIED MATERIALS & INTERFACES 2022; 14:36763-36770. [PMID: 35939364 DOI: 10.1021/acsami.2c09767] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
The rapid development of the automotive and aerospace industries has led to an increasingly urgent need for electromechanical coupling materials and devices. Here, we have demonstrated the tunable piezo-flexoelectric effect in ferroelectric Ba0.7Sr0.3TiO3 materials for scavenging vibration energy. The positive peak output current of an ITO/Ba0.7Sr0.3TiO3/Ag cantilever device based on the flexoelectric effect is only 45 nA at room temperature, which is promoted to 90 nA by the piezo-flexoelectric effect. In addition, the piezo-flexoelectric current of the device can be further boosted to 270 nA by increasing the working temperature to 41.0 °C with a corresponding enhancement ratio of 348.28%. The significantly improved piezo-flexoelectric current is ascribed to the ultrahigh dielectric constant, which is related to the tetragonal-cubic phase transition of the Ba0.7Sr0.3TiO3 materials. This work reveals the temperature-modulated piezo-flexoelectric effect in ferroelectric Ba0.7Sr0.3TiO3 materials, providing a convenient route for scavenging and sensing of vibration energy.
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Affiliation(s)
- Yanlong Xia
- CAS Center for Excellence in Nanoscience, Beijing Key Laboratory of Micro-Nano Energy and Sensor, Beijing Institute of Nanoenergy and Nanosystems, Chinese Academy of Sciences, Beijing 101400, P. R. China
- School of Resources Environment and Materials, Center on Nanoenergy Research, Guangxi University, Nanning 530004, Guangxi, P. R. China
| | - Yun Ji
- CAS Center for Excellence in Nanoscience, Beijing Key Laboratory of Micro-Nano Energy and Sensor, Beijing Institute of Nanoenergy and Nanosystems, Chinese Academy of Sciences, Beijing 101400, P. R. China
| | - Yuan Liu
- CAS Center for Excellence in Nanoscience, Beijing Key Laboratory of Micro-Nano Energy and Sensor, Beijing Institute of Nanoenergy and Nanosystems, Chinese Academy of Sciences, Beijing 101400, P. R. China
- School of Physical Science and Technology, Center on Nanoenergy Research, Guangxi University, Nanning 530004, Guangxi, P. R. China
| | - Li Wu
- CAS Center for Excellence in Nanoscience, Beijing Key Laboratory of Micro-Nano Energy and Sensor, Beijing Institute of Nanoenergy and Nanosystems, Chinese Academy of Sciences, Beijing 101400, P. R. China
- School of Physical Science and Technology, Center on Nanoenergy Research, Guangxi University, Nanning 530004, Guangxi, P. R. China
| | - Ya Yang
- CAS Center for Excellence in Nanoscience, Beijing Key Laboratory of Micro-Nano Energy and Sensor, Beijing Institute of Nanoenergy and Nanosystems, Chinese Academy of Sciences, Beijing 101400, P. R. China
- School of Resources Environment and Materials, Center on Nanoenergy Research, Guangxi University, Nanning 530004, Guangxi, P. R. China
- School of Physical Science and Technology, Center on Nanoenergy Research, Guangxi University, Nanning 530004, Guangxi, P. R. China
- School of Nanoscience and Technology, University of Chinese Academy of Sciences, Beijing 100049, China
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30
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Highly heterogeneous epitaxy of flexoelectric BaTiO3-δ membrane on Ge. Nat Commun 2022; 13:2990. [PMID: 35637222 PMCID: PMC9151678 DOI: 10.1038/s41467-022-30724-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2022] [Accepted: 05/12/2022] [Indexed: 11/08/2022] Open
Abstract
The integration of complex oxides with a wide spectrum of functionalities on Si, Ge and flexible substrates is highly demanded for functional devices in information technology. We demonstrate the remote epitaxy of BaTiO3 (BTO) on Ge using a graphene intermediate layer, which forms a prototype of highly heterogeneous epitaxial systems. The Ge surface orientation dictates the outcome of remote epitaxy. Single crystalline epitaxial BTO3-δ films were grown on graphene/Ge (011), whereas graphene/Ge (001) led to textured films. The graphene plays an important role in surface passivation. The remote epitaxial deposition of BTO3-δ follows the Volmer-Weber growth mode, with the strain being partially relaxed at the very beginning of the growth. Such BTO3-δ films can be easily exfoliated and transferred to arbitrary substrates like Si and flexible polyimide. The transferred BTO3-δ films possess enhanced flexoelectric properties with a gauge factor of as high as 1127. These results not only expand the understanding of heteroepitaxy, but also open a pathway for the applications of devices based on complex oxides. The integration of epitaxial complex oxides on semiconductor and flexible substrates is required but challenging. Here, the authors report the highly heterogeneous epitaxy of transferrable BaTiO3-δ membrane with enhanced flexoelectricity on Ge (011).
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31
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Effect of Pre-Polarization Process on the Apparent Piezoelectric Response Measured by Point-Ring Method in Ferroelectric Perovskite Oxide Ceramics. ENERGIES 2022. [DOI: 10.3390/en15103627] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Both flexoelectricity and piezoelectricity belong to the electromechanical coupling effect. While piezoelectricity only exists in materials whose crystal structure is noncentrosymmetric and a pre-polarization process is necessary for ferroelectric piezoelectric ceramics, flexoelectricity theoretically exists in all dielectric materials and does not require pre-polarization. However, this does not mean that flexoelectricity would not be affected by the pre-polarization process, considering that flexoelectricity is a polarization phenomenon. In this work, we prepared ferroelectric perovskite oxide ceramics Ba1−xCaxTiO3 and revealed a strong effect of the pre-polarization process on the flexoelectric response of the ceramics, characterized by the apparent piezoelectric response measured by the point-ring method. The effective piezoelectric coefficient was separated into the one contributed by the flexoelectric(-like) response and the piezoelectric(-like) response by quasi-static d33 measurement and a two-step point-ring testing method. The effective piezoelectric coefficient contributed by the flexoelectric(-like) response of the ceramics could be largely enhanced to be over 350 pC/N after a 900 V polarization, larger than the standard piezoelectric response. The pre-polarization process was suggested to alter the polarization state and defect distributions, which would further change the overall flexoelectric response (both intrinsic and extrinsic parts) of the samples. Our work indicates a facile method to enhance the apparent piezoelectric response of flexoelectric materials under a bending mode.
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32
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YANG Y, HIRSINGER L, Devel M. Computation of Flexoelectric Coefficients of a MoS 2 monolayer with a Model of Self-consistently Distributed Effective Charges and Dipoles. J Chem Phys 2022; 156:174104. [DOI: 10.1063/5.0088972] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Flexoelectricity is an electromechanical coupling phenomenon, that can generate noticeable electric polarization in dielectric materials for nanoscale strain gradients. It is gaining an increasing attention because of its potential applications, and the fact that experimental results were initially an order of magnitude higher than initial theoretical predictions. This stimulated intense experimental and theoretical researches to investigate flexoelectric coefficients in dielectric materials such as two-dimensional materials. In this work, we concentrate on the calculation of the flexoelectric coefficients of 2D-MoS2 thanks to a model using self-consistently determined charges and dipoles on the atoms. More specifically, we study the importance of two contributions which were neglected/omitted in previous papers using this model, namely the charge term in the total polarization and the conservation of electric charge through a Lagrange multiplier. Our calculations demonstrate that the results for flexoelectric coefficient computed with this improved definition of polarization agree better with experimental measurements, provided consistent definitions for signs are used. Additionally, we show how two physical contributions with opposite signs compete to give net values of flexoelectric coefficients that can be either positive of negative depending on their relative importance, and give net values for the case of MoS2.
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Affiliation(s)
| | | | - Michel Devel
- Doubs, Ecole Nationale Supérieure de Mécanique et des Microtechniques, France
- FEMTO-ST
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33
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Wu M, Zhang X, Li X, Qu K, Sun Y, Han B, Zhu R, Gao X, Zhang J, Liu K, Bai X, Li XZ, Gao P. Engineering of atomic-scale flexoelectricity at grain boundaries. Nat Commun 2022; 13:216. [PMID: 35017521 PMCID: PMC8752668 DOI: 10.1038/s41467-021-27906-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2021] [Accepted: 12/17/2021] [Indexed: 12/05/2022] Open
Abstract
Flexoelectricity is a type of ubiquitous and prominent electromechanical coupling, pertaining to the electrical polarization response to mechanical strain gradients that is not restricted by the symmetry of materials. However, large elastic deformation is usually difficult to achieve in most solids, and the strain gradient at minuscule is challenging to control. Here, we exploit the exotic structural inhomogeneity of grain boundary to achieve a huge strain gradient (~1.2 nm-1) within 3-4-unit cells, and thus obtain atomic-scale flexoelectric polarization of up to ~38 μC cm-2 at a 24° LaAlO3 grain boundary. Accompanied by the generation of the nanoscale flexoelectricity, the electronic structures of grain boundaries also become different. Hence, the flexoelectric effect at grain boundaries is essential to understand the electrical activities of oxide ceramics. We further demonstrate that for different materials, altering the misorientation angles of grain boundaries enables tunable strain gradients at the atomic scale. The engineering of grain boundaries thus provides a general and feasible pathway to achieve tunable flexoelectricity.
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Affiliation(s)
- Mei Wu
- International Center for Quantum Materials, School of Physics, Peking University, Beijing, 100871, China
- Electron Microscopy Laboratory, School of Physics, Peking University, Beijing, 100871, China
| | - Xiaowei Zhang
- International Center for Quantum Materials, School of Physics, Peking University, Beijing, 100871, China
| | - Xiaomei Li
- International Center for Quantum Materials, School of Physics, Peking University, Beijing, 100871, China
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
| | - Ke Qu
- Electron Microscopy Laboratory, School of Physics, Peking University, Beijing, 100871, China
| | - Yuanwei Sun
- International Center for Quantum Materials, School of Physics, Peking University, Beijing, 100871, China
- Electron Microscopy Laboratory, School of Physics, Peking University, Beijing, 100871, China
| | - Bo Han
- International Center for Quantum Materials, School of Physics, Peking University, Beijing, 100871, China
- Electron Microscopy Laboratory, School of Physics, Peking University, Beijing, 100871, China
| | - Ruixue Zhu
- International Center for Quantum Materials, School of Physics, Peking University, Beijing, 100871, China
- Electron Microscopy Laboratory, School of Physics, Peking University, Beijing, 100871, China
| | - Xiaoyue Gao
- International Center for Quantum Materials, School of Physics, Peking University, Beijing, 100871, China
- Electron Microscopy Laboratory, School of Physics, Peking University, Beijing, 100871, China
| | - Jingmin Zhang
- Electron Microscopy Laboratory, School of Physics, Peking University, Beijing, 100871, China
| | - Kaihui Liu
- State Key Laboratory for Mesoscopic Physics, School of Physics, Peking University, Beijing, 100871, China
- Collaborative Innovation Centre of Quantum Matter, Beijing, 100871, China
- Interdisciplinary Institute of Light-Element Quantum Materials and Research Center for Light-Element Advanced Materials, Peking University, Beijing, 100871, China
| | - Xuedong Bai
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
| | - Xin-Zheng Li
- State Key Laboratory for Mesoscopic Physics, School of Physics, Peking University, Beijing, 100871, China.
- Collaborative Innovation Centre of Quantum Matter, Beijing, 100871, China.
- Frontiers Science Center for Nano-optoelectronics, School of Physics, Peking University, Beijing, 100871, China.
- Peking University Yangtze Delta Institute of Optoelectronics, Nantong, 226010, Jiangsu, China.
| | - Peng Gao
- International Center for Quantum Materials, School of Physics, Peking University, Beijing, 100871, China.
- Electron Microscopy Laboratory, School of Physics, Peking University, Beijing, 100871, China.
- Collaborative Innovation Centre of Quantum Matter, Beijing, 100871, China.
- Interdisciplinary Institute of Light-Element Quantum Materials and Research Center for Light-Element Advanced Materials, Peking University, Beijing, 100871, China.
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34
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Yasui K, Itasaka H, Mimura KI, Kato K. Coexistence of Flexo- and Ferro-Electric Effects in an Ordered Assembly of BaTiO 3 Nanocubes. NANOMATERIALS 2022; 12:nano12020188. [PMID: 35055207 PMCID: PMC8781377 DOI: 10.3390/nano12020188] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Revised: 12/28/2021] [Accepted: 12/28/2021] [Indexed: 12/25/2022]
Abstract
It has been reported that the flexoelectric effect could be dominant in the nanoscale. The discrepancy between theory and experiments on the frequency dependence of the dielectric constant of an ordered assembly of BaTiO3 nanocubes is nearly resolved by assuming the coexistence of flexo- and ferro-electric effects. Although flexoelectric polarizations perpendicular to the applied alternating electric field contribute to the dielectric constant, those parallel to the electric field do not contribute because the magnitude of the flexoelectric polarization does not change due to the mismatch of strain at the interface of the nanocubes. On the other hand, some dielectric response is possible for the ferroelectric component of the polarization parallel to the electric field.
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35
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Springolo M, Royo M, Stengel M. Direct and Converse Flexoelectricity in Two-Dimensional Materials. PHYSICAL REVIEW LETTERS 2021; 127:216801. [PMID: 34860115 DOI: 10.1103/physrevlett.127.216801] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/16/2020] [Revised: 07/16/2021] [Accepted: 09/30/2021] [Indexed: 06/13/2023]
Abstract
Building on recent developments in electronic-structure methods, we define and calculate the flexoelectric response of two-dimensional (2D) materials fully from first principles. In particular, we show that the open-circuit voltage response to a flexural deformation is a fundamental linear-response property of the crystal that can be calculated within the primitive unit cell of the flat configuration. Applications to graphene, silicene, phosphorene, boron nitride, and transition-metal dichalcogenide monolayers reveal that two distinct contributions exist, respectively of purely electronic and lattice-mediated nature. Within the former, we identify a key metric term, consisting in the quadrupolar moment of the unperturbed charge density. We propose a simple continuum model to connect our findings with the available experimental measurements of the converse flexoelectric effect.
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Affiliation(s)
- Matteo Springolo
- Institut de Ciència de Materials de Barcelona (ICMAB-CSIC), Campus UAB, 08193 Bellaterra, Spain
| | - Miquel Royo
- Institut de Ciència de Materials de Barcelona (ICMAB-CSIC), Campus UAB, 08193 Bellaterra, Spain
| | - Massimiliano Stengel
- Institut de Ciència de Materials de Barcelona (ICMAB-CSIC), Campus UAB, 08193 Bellaterra, Spain
- ICREA-Institució Catalana de Recerca i Estudis Avançats, 08010 Barcelona, Spain
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36
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Geometrical Nonlinearity for a Timoshenko Beam with Flexoelectricity. NANOMATERIALS 2021; 11:nano11113123. [PMID: 34835888 PMCID: PMC8620600 DOI: 10.3390/nano11113123] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/25/2021] [Revised: 11/12/2021] [Accepted: 11/13/2021] [Indexed: 11/17/2022]
Abstract
The Timoshenko beam model is applied to the analysis of the flexoelectric effect for a cantilever beam under large deformations. The geometric nonlinearity with von Kármán strains is considered. The nonlinear system of ordinary differential equations (ODE) for beam deflection and rotation are derived. Moreover, this nonlinear system is linearized for each load increment, where it is solved iteratively. For the vanishing flexoelectric coefficient, the governing equations lead to the classical Timoshenko beam model. Furthermore, the influence of the flexoelectricity coefficient and the microstructural length-scale parameter on the beam deflection and the induced electric intensity is investigated.
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Abstract
Low-dimensional (LD) transition metal dichalcogenides (TMDs) in the form of nanoflakes, which consist of one or several layers, are the subject of intensive fundamental and applied research. The tuning of the electronic properties of the LD-TMDs are commonly related with applied strains and strain gradients, which can strongly affect their polar properties via piezoelectric and flexoelectric couplings. Using the density functional theory and phenomenological Landau approach, we studied the bended 2H-MoS2 monolayer and analyzed its flexoelectric and piezoelectric properties. The dependences of the dipole moment, strain, and strain gradient on the coordinate along the layer were calculated. From these dependences, the components of the flexoelectric and piezoelectric tensors have been determined and analyzed. Our results revealed that the contribution of the flexoelectric effect dominates over the piezoelectric effect in both in-plane and out-of-plane directions of the monolayer. In accordance with our calculations, a realistic strain gradient of about 1 nm−1 can induce an order of magnitude higher than the flexoelectric response in comparison with the piezoelectric reaction. The value of the dilatational flexoelectric coefficient is almost two times smaller than the shear component. It appeared that the components of effective flexoelectric and piezoelectric couplings can be described by parabolic dependences of the corrugation. Obtained results are useful for applications of LD-TMDs in strain engineering and flexible electronics.
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38
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Analysis of the Piezoelectric Properties of Aligned Multi-Walled Carbon Nanotubes. NANOMATERIALS 2021; 11:nano11112912. [PMID: 34835676 PMCID: PMC8617926 DOI: 10.3390/nano11112912] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/07/2021] [Revised: 10/25/2021] [Accepted: 10/26/2021] [Indexed: 11/23/2022]
Abstract
Recent studies reveal that carbon nanostructures show anomalous piezoelectric properties when the central symmetry of their structure is violated. Particular focus is given to carbon nanotubes (CNTs) with initial significant curvature of the graphene sheet surface, which leads to an asymmetric redistribution of the electron density. This paper presents the results of studies on the piezoelectric properties of aligned multi-walled CNTs. An original technique for evaluating the effective piezoelectric coefficient of CNTs is presented. For the first time, in this study, we investigate the influence of the growth temperature and thickness of the catalytic Ni layer on the value of the piezoelectric coefficient of CNTs. We establish the relationship between the effective piezoelectric coefficient of CNTs and their defectiveness and diameter, which determines the curvature of the graphene sheet surface. The calculated values of the effective piezoelectric coefficient of CNTs are shown to be between 0.019 and 0.413 C/m2, depending on the degree of their defectiveness and diameter.
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39
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Gortsas TV, Tsinopoulos SV, Polyzos E, Pyl L, Fotiadis DI, Polyzos D. BEM evaluation of surface octahedral strains and internal strain gradients in 3D-printed scaffolds used for bone tissue regeneration. J Mech Behav Biomed Mater 2021; 125:104919. [PMID: 34740014 DOI: 10.1016/j.jmbbm.2021.104919] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2021] [Revised: 10/20/2021] [Accepted: 10/20/2021] [Indexed: 10/20/2022]
Abstract
Most of the mechnoregulatory computational models appearing so far in tissue engineering for bone healing predictions, utilize as regulators for cell differentiation mainly the octahedral volume strains and the interstitial fluid velocity calculated at any point of the fractured bone area and controlled by empirical constants concerning these two parameters. Other stimuli like the electrical and chemical signaling of bone constituents are covered by those two regulatory fields. It is apparent that the application of the same mechnoregulatory computational models for bone healing predictions in scaffold-aided regeneration is questionable since the material of a scaffold disturbs the signaling pathways developed in the environment of bone fracture. Thus, the goal of the present work is to evaluate numerically two fields developed in the body of two different compressed scaffolds, which seem to be proper for facilitating cell sensing and improving cell viability and cell seeding efficiency. These two fields concern the surface octahedral strains that the cells attached to the scaffold can experience and the internal strain gradients that create electrical pathways due to flexoelectric phenomenon. Both fields are evaluated with the aid of the Boundary Element Method (BEM), which is ideal for evaluating with high accuracy surface strains and stresses as well as strain gradients appearing throughout the analyzed elastic domain.
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Affiliation(s)
- T V Gortsas
- Department of Mechanical Engineering and Aeronautics, University of Patras, Greece.
| | - S V Tsinopoulos
- Department of Mechanical Engineering, University of Peloponnese, Greece
| | - E Polyzos
- Department of Mechanics of Materials and Constructions, Vrije Universiteit Brussel (VUB), BE-1050, Brussels, Belgium
| | - L Pyl
- Department of Mechanics of Materials and Constructions, Vrije Universiteit Brussel (VUB), BE-1050, Brussels, Belgium
| | - D I Fotiadis
- Unit of Medical Technology and Intelligent Information Systems, Dept. of Material Science and Engineering, University of Ioannina, GR 451 10, Ioannina, Greece
| | - D Polyzos
- Department of Mechanical Engineering and Aeronautics, University of Patras, Greece
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40
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Shimada T, Wang Y, Hamaguchi T, Kasai K, Masuda K, Van Lich L, Xu T, Wang J, Hirakata H. Emergence of non-trivial polar topologies hidden in singular stress field in SrTiO 3: topological strain-field engineering. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2021; 33:505301. [PMID: 34547728 DOI: 10.1088/1361-648x/ac28c1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/15/2021] [Accepted: 09/21/2021] [Indexed: 06/13/2023]
Abstract
Discovery of non-trivial topological structures in condensed matters holds promise in novel technological paradigms. In contrast to ferromagnetics, where a variety of topological structures such as vortex, meron, and skyrmion have been discovered, only few topological structures can exist in ferroelectrics due to the lack of non-collinear interaction like the Dzyaloshinskii-Moriya interaction in ferromagnetics. Here, we demonstrate that polarization structures with a wide range of topological numbers (winding numbernfrom -3 to +1) can be mechanically excited and designed by the mode-I singular stress field formed near the crack-tip in incipient ferroelectric SrTiO3. Our phase-field simulations based on Ginzburg-Landau theory successfully reveals that the near-tip polar topology is driven by the flexoelectric coupling with intense strain gradient at the tip, while a variety of the far-field topological structures is triggered by a collaboration between the electrostrictive and flexoelectric effects. The strain (gradient) field analysis further shows that the unexpected topological characters are implied in the singular stress field, which develops a variety of polar topologies near the crack tip. Therefore, our work provides a novel insight into the unusual interplay between mechanical- and ferroelectric-topologies, i.e. 'topological strain-field engineering', which paves the way to the mechanical design of functional topologies in the matter.
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Affiliation(s)
- Takahiro Shimada
- Department of Mechanical Engineering and Science, Kyoto University, Nishikyo-ku, Kyoto 615-8540, Japan
| | - Yu Wang
- Department of Mechanical Engineering and Science, Kyoto University, Nishikyo-ku, Kyoto 615-8540, Japan
| | - Takayuki Hamaguchi
- Department of Mechanical Engineering and Science, Kyoto University, Nishikyo-ku, Kyoto 615-8540, Japan
| | - Kohta Kasai
- Department of Mechanical Engineering and Science, Kyoto University, Nishikyo-ku, Kyoto 615-8540, Japan
| | - Kairi Masuda
- Department of Mechanical Engineering and Science, Kyoto University, Nishikyo-ku, Kyoto 615-8540, Japan
| | - Le Van Lich
- School of Materials Science and Engineering, Hanoi University of Science and Technology, No 1, Dai Co Viet Street, Hanoi 100000, Vietnam
| | - Tao Xu
- Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201, People's Republic of China
| | - Jie Wang
- Department of Engineering Mechanics & Key Laboratory of Soft Machines and Smart Devices of Zhejiang Province, School of Aeronautics and Astronautics, Zhejiang University, Hangzhou 310027, People's Republic of China
| | - Hiroyuki Hirakata
- Department of Mechanical Engineering and Science, Kyoto University, Nishikyo-ku, Kyoto 615-8540, Japan
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41
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Chen H, Jerusalem A. A Framework for Low-Intensity Low-Frequency Ultrasound Neuromodulation Sonication Parameter Identification from Micromechanical Flexoelectricity Modelling. ULTRASOUND IN MEDICINE & BIOLOGY 2021; 47:1985-1991. [PMID: 33820667 DOI: 10.1016/j.ultrasmedbio.2021.02.028] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/09/2020] [Revised: 02/23/2021] [Accepted: 02/28/2021] [Indexed: 06/12/2023]
Abstract
Low-intensity, low-frequency ultrasound (LILFU) has recently emerged as a promising technique to modulate non-invasively nerve activities at lower cost than other traditional and more-invasive neuromodulation methods. However, there is currently no consensus on the optimum sonication parameters to be used in LILFU applications, and most of the accepted ranges have arisen from trial-and-error approaches. Here we utilise a recently proposed micromechanics model of membrane flexoelectricity, a potential candidate for neuromodulation, and simulate action potentials/membrane polarisation triggered by acoustic pulses of different pulse frequencies, pulse magnitudes and duty cycles. Results reveal that, at constant duty cycles, increasing the transmit frequency increases the thresholds of both the pulse magnitude and the elastic energy rate density required to mechanically trigger an action potential, whereas at constant frequencies, increasing the duty cycle reduces both. The influence of transmit frequency is weakened at lower duty cycles. Our simulation results offer some guidance on the selections of sonication parameters used in LILFU for neurologic disorder treatments in the context of the flexoelectricity hypothesis.
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Affiliation(s)
- Haoyu Chen
- Department of Engineering Science, University of Oxford, Oxford, United Kingdom
| | - Antoine Jerusalem
- Department of Engineering Science, University of Oxford, Oxford, United Kingdom.
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42
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Liu C, Liu Y, Zhang B, Sun CJ, Lan D, Chen P, Wu X, Yang P, Yu X, Charlton T, Fitzsimmons MR, Ding J, Chen J, Chow GM. Ferroelectric Self-Polarization Controlled Magnetic Stratification and Magnetic Coupling in Ultrathin La 0.67Sr 0.33MnO 3 Films. ACS APPLIED MATERIALS & INTERFACES 2021; 13:30137-30145. [PMID: 34137601 DOI: 10.1021/acsami.1c02300] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Multiferroic oxide heterostructures consisting of ferromagnetic and ferroelectric components hold the promise for nonvolatile magnetic control via ferroelectric polarization, advantageous for the low-dissipation spintronics. Modern understanding of the magnetoelectric coupling in these systems involves structural, orbital, and magnetic reconstructions at interfaces. Previous works have long proposed polarization-dependent interfacial magnetic structures; however, direct evidence is still missing, which requires advanced characterization tools with near-atomic-scale spatial resolutions. Here, extensive polarized neutron reflectometry (PNR) studies have determined the magnetic depth profiles of PbZr0.2Ti0.8O3/La0.67Sr0.33MnO3 (PZT/LSMO) bilayers with opposite self-polarizations. When the LSMO is 2-3 nm thick, the bilayers show two magnetic transitions on cooling. However, temperature-dependent magnetization is different below the lower-temperature transition for opposite polarizations. PNR finds that the LSMO splits into two magnetic sublayers, but the inter-sublayer magnetic couplings are of opposite signs for the two polarizations. Near-edge X-ray absorption spectroscopy further shows contrasts in both the Mn valences and the Mn-O bond anisotropy between the two polarizations. This work completes the puzzle for the magnetoelectric coupling model at the PZT/LSMO interface, showing a synergic interplay among multiple degrees of freedom toward emergent functionalities at complex oxide interfaces.
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Affiliation(s)
- Chao Liu
- Department of Materials Science & Engineering, National University of Singapore, Singapore 117575, Singapore
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Yaohua Liu
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Bangmin Zhang
- School of Physics, Sun Yat-Sen University, Guangzhou510275 Guangdong, China
| | - Cheng-Jun Sun
- Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439, United States
| | - Da Lan
- Department of Materials Science & Engineering, National University of Singapore, Singapore 117575, Singapore
| | - Pingfan Chen
- Department of Materials Science & Engineering, National University of Singapore, Singapore 117575, Singapore
| | - Xiaohan Wu
- Department of Materials Science & Engineering, National University of Singapore, Singapore 117575, Singapore
| | - Ping Yang
- Singapore Synchrotron Light Source, National University of Singapore, Singapore 117603, Singapore
| | - Xiaojiang Yu
- Singapore Synchrotron Light Source, National University of Singapore, Singapore 117603, Singapore
| | - Timothy Charlton
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Michael R Fitzsimmons
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Jun Ding
- Department of Materials Science & Engineering, National University of Singapore, Singapore 117575, Singapore
| | - Jingsheng Chen
- Department of Materials Science & Engineering, National University of Singapore, Singapore 117575, Singapore
| | - Gan Moog Chow
- Department of Materials Science & Engineering, National University of Singapore, Singapore 117575, Singapore
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43
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Wang C, Zhang Y, Zhang B, Wang B, Zhang J, Chen L, Zhang Q, Wang ZL, Ren K. Flexophotovoltaic Effect in Potassium Sodium Niobate/Poly(Vinylidene Fluoride-Trifluoroethylene) Nanocomposite. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2021; 8:2004554. [PMID: 33898200 PMCID: PMC8061384 DOI: 10.1002/advs.202004554] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/25/2020] [Indexed: 06/12/2023]
Abstract
Flexoelectricity is an electromechanical coupling effect in which electric polarization is generated by a strain gradient. In this investigation, a potassium sodium niobite/poly(vinylidene fluoride-trifluoroethylene) (KNN/PVDF-TrFE)-based nanocomposite is fabricated, and the flexoelectric effect is used to enhance the photovoltaic current (I pv) in the nanocomposite. It is found that both a pyroelectric current and photovoltaic current can be generated simultaneously in a light illumination process. However, the photovoltaic current (I pv) in this process contributes ≈85% of the total current. When assessing the effect of flexoelectricity with a curvature of 1/20, the I pv of the curved KNN/PVDF-TrFE (20%) (K/P-20) composite increased by ≈13.9% compared to that of the flat K/P-20 nanocomposite. Similarly, at a curvature of 1/20, the I pv of the K/P-20 nanocomposite is 71.6% higher than that of the PVDF-TrFE film. However, the photovoltaic effect induced by flexoelectricity is much higher than the increased polarization from flexoelectricity, so this effect is called as the flexophotovoltaic effect. Furthermore, the calculated energy conversion efficiency of the K/P-20 film is 0.017%, which is comparable to the previous research result. This investigation shows great promise for PVDF-based nanocomposites in ferroelectric memory device applications.
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Affiliation(s)
- Chenchen Wang
- Beijing Key Laboratory of Micro‐nano Energy and Sensor; CAS Center for Excellence in NanoscienceBeijing Institute of Nanoenergy and Nanosystems, Chinese Academy of SciencesBeijing101400P. R. China
| | - Yang Zhang
- Institute of SemiconductorsChinese Academy of SciencesBeijing100083P.R. China
| | - Bowen Zhang
- Beijing Key Laboratory of Micro‐nano Energy and Sensor; CAS Center for Excellence in NanoscienceBeijing Institute of Nanoenergy and Nanosystems, Chinese Academy of SciencesBeijing101400P. R. China
| | - Bo Wang
- Department of Materials Science and EngineeringThe Pennsylvania State UniversityUniversity ParkPA16802USA
| | - Jinxi Zhang
- Beijing Key Laboratory of Micro‐nano Energy and Sensor; CAS Center for Excellence in NanoscienceBeijing Institute of Nanoenergy and Nanosystems, Chinese Academy of SciencesBeijing101400P. R. China
| | - Long‐Qing Chen
- Department of Materials Science and EngineeringThe Pennsylvania State UniversityUniversity ParkPA16802USA
| | - Qiming Zhang
- Department of Electrical Engineering and Materials Research InstitutePennsylvania State UniversityUniversity ParkPA16802USA
| | - Zhong Lin Wang
- Beijing Key Laboratory of Micro‐nano Energy and Sensor; CAS Center for Excellence in NanoscienceBeijing Institute of Nanoenergy and Nanosystems, Chinese Academy of SciencesBeijing101400P. R. China
- School of Material Science and EngineeringGeorgia Institute of TechnologyAtlantaGA30332USA
| | - Kailiang Ren
- Beijing Key Laboratory of Micro‐nano Energy and Sensor; CAS Center for Excellence in NanoscienceBeijing Institute of Nanoenergy and Nanosystems, Chinese Academy of SciencesBeijing101400P. R. China
- School of Physical Science and TechnologyGuangxi UniversityNanningGuangxi530004P.R. China
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44
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Hadjimichael M, Li Y, Zatterin E, Chahine GA, Conroy M, Moore K, Connell ENO, Ondrejkovic P, Marton P, Hlinka J, Bangert U, Leake S, Zubko P. Metal-ferroelectric supercrystals with periodically curved metallic layers. NATURE MATERIALS 2021; 20:495-502. [PMID: 33398118 DOI: 10.1038/s41563-020-00864-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/09/2019] [Accepted: 10/26/2020] [Indexed: 06/12/2023]
Abstract
Simultaneous manipulation of multiple boundary conditions in nanoscale heterostructures offers a versatile route to stabilizing unusual structures and emergent phases. Here, we show that a stable supercrystal phase comprising a three-dimensional ordering of nanoscale domains with tailored periodicities can be engineered in PbTiO3-SrRuO3 ferroelectric-metal superlattices. A combination of laboratory and synchrotron X-ray diffraction, piezoresponse force microscopy, scanning transmission electron microscopy and phase-field simulations reveals a complex hierarchical domain structure that forms to minimize the elastic and electrostatic energy. Large local deformations of the ferroelectric lattice are accommodated by periodic lattice modulations of the metallic SrRuO3 layers with curvatures up to 107 m-1. Our results show that multidomain ferroelectric systems can be exploited as versatile templates to induce large curvatures in correlated materials, and present a route for engineering correlated materials with modulated structural and electronic properties that can be controlled using electric fields.
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Affiliation(s)
- Marios Hadjimichael
- London Centre for Nanotechnology, London, UK.
- Department of Physics and Astronomy, University College London, London, UK.
- Department of Quantum Matter Physics, University of Geneva, Geneva, Switzerland.
| | - Yaqi Li
- Department of Physics and Astronomy, University College London, London, UK
| | - Edoardo Zatterin
- Department of Physics and Astronomy, University College London, London, UK
- The European Synchrotron Radiation Facility (ESRF), Grenoble, France
| | - Gilbert A Chahine
- Université Grenoble Alpes, CNRS, Grenoble INP, SIMAP, Grenoble, France
| | - Michele Conroy
- Department of Physics, Bernal Institute, University of Limerick, Limerick, Ireland
| | - Kalani Moore
- Department of Physics, Bernal Institute, University of Limerick, Limerick, Ireland
| | - Eoghan N O' Connell
- Department of Physics, Bernal Institute, University of Limerick, Limerick, Ireland
| | - Petr Ondrejkovic
- Institute of Physics of the Czech Academy of Sciences, Praha, Czech Republic
| | - Pavel Marton
- Institute of Physics of the Czech Academy of Sciences, Praha, Czech Republic
| | - Jiri Hlinka
- Institute of Physics of the Czech Academy of Sciences, Praha, Czech Republic
| | - Ursel Bangert
- Department of Physics, Bernal Institute, University of Limerick, Limerick, Ireland
| | - Steven Leake
- The European Synchrotron Radiation Facility (ESRF), Grenoble, France
| | - Pavlo Zubko
- London Centre for Nanotechnology, London, UK.
- Department of Physics and Astronomy, University College London, London, UK.
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45
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Zabalo A, Stengel M. Switching a Polar Metal via Strain Gradients. PHYSICAL REVIEW LETTERS 2021; 126:127601. [PMID: 33834822 DOI: 10.1103/physrevlett.126.127601] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/22/2020] [Accepted: 02/15/2021] [Indexed: 06/12/2023]
Abstract
Although rare, spontaneous breakdown of inversion symmetry sometimes occurs in a material which is metallic: these are commonly known as polar metals or ferroelectric metals. Their polarization, however, is difficult to switch via an electric field, which limits the experimental control over band topology. Here we investigate, via first-principles theory, flexoelectricity as a possible way around this obstacle with the well-known polar metal LiOsO_{3}. The flexocoupling coefficients are computed for this metal with high accuracy with an approach based on real-space sums of the interatomic force constants. A Landau-Ginzburg-Devonshire-type first-principles Hamiltonian is built and a critical bending radius to switch the material is estimated, whose order of magnitude is comparable to that of BaTiO_{3}.
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Affiliation(s)
- Asier Zabalo
- Institut de Ciència de Materials de Barcelona (ICMAB-CSIC), Campus UAB, 08193 Bellaterra, Spain
| | - Massimiliano Stengel
- Institut de Ciència de Materials de Barcelona (ICMAB-CSIC), Campus UAB, 08193 Bellaterra, Spain
- ICREA-Institució Catalana de Recerca i Estudis Avanats, 08010 Barcelona, Spain
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46
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Harbola V, Crossley S, Hong SS, Lu D, Birkhölzer YA, Hikita Y, Hwang HY. Strain Gradient Elasticity in SrTiO 3 Membranes: Bending versus Stretching. NANO LETTERS 2021; 21:2470-2475. [PMID: 33689379 DOI: 10.1021/acs.nanolett.0c04787] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Young's modulus determines the mechanical loads required to elastically stretch a material and also the loads required to bend it, given that bending stretches one surface while compressing the opposite one. Flexoelectric materials have the additional property of becoming electrically polarized when bent. The associated energy cost can additionally contribute to elasticity via strain gradients, particularly at small length scales where they are geometrically enhanced. Here, we present nanomechanical measurements of freely suspended SrTiO3 crystalline membrane drumheads. We observe an unexpected nonmonotonic thickness dependence of Young's modulus upon small deflections. Furthermore, the modulus inferred from a predominantly bending deformation is three times larger than that of a predominantly stretching deformation for membranes thinner than 20 nm. In this regime we extract a strain gradient elastic coupling of ∼2.2 μN, which could be used in new operational regimes of nanoelectro-mechanics.
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Affiliation(s)
- Varun Harbola
- Department of Physics, Stanford University, Stanford, California 94305, United States
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, United States
| | - Samuel Crossley
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, United States
- Department of Applied Physics, Stanford University, Stanford, California 94305, United States
| | - Seung Sae Hong
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, United States
- Department of Applied Physics, Stanford University, Stanford, California 94305, United States
| | - Di Lu
- Department of Physics, Stanford University, Stanford, California 94305, United States
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, United States
| | - Yorick A Birkhölzer
- Department of Inorganic Materials Science, Faculty of Science and Technology and MESA+ Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands
| | - Yasuyuki Hikita
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, United States
| | - Harold Y Hwang
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, United States
- Department of Applied Physics, Stanford University, Stanford, California 94305, United States
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47
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Hrytsyna O. The effect of local mass displacement on coupled fields in dielectrics. APPLIED NANOSCIENCE 2021. [DOI: 10.1007/s13204-021-01714-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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48
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Kumar S, Codony D, Arias I, Suryanarayana P. Flexoelectricity in atomic monolayers from first principles. NANOSCALE 2021; 13:1600-1607. [PMID: 33427828 DOI: 10.1039/d0nr07803d] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
We study the flexoelectric effect in fifty-four select atomic monolayers using ab initio Density Functional Theory (DFT). Specifically, considering representative materials from each of the Group III monochalcogenides, transition metal dichalcogenides (TMDs), Groups IV, III-V, and V monolayers, Group IV dichalcogenides, Group IV monochalcogenides, transition metal trichalcogenides (TMTs), and Group V chalcogenides, we perform symmetry-adapted DFT simulations to calculate transversal flexoelectric coefficients along the principal directions at practically relevant bending curvatures. We find that the materials demonstrate linear behavior and have similar coefficients along both principal directions, with values for TMTs being up to a factor of five larger than those of graphene. In addition, we find electronic origins for the flexoelectric effect, which increases with monolayer thickness, elastic modulus along the bending direction, and sum of polarizability of constituent atoms.
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Affiliation(s)
- Shashikant Kumar
- College of Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA.
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49
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Zhang X, Beyer A. Mechanics of free-standing inorganic and molecular 2D materials. NANOSCALE 2021; 13:1443-1484. [PMID: 33434243 DOI: 10.1039/d0nr07606f] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
The discovery of graphene has triggered a great interest in inorganic as well as molecular two-dimensional (2D) materials. In this review, we summarize recent progress in the mechanical characterization of free-standing 2D materials, such as graphene, hexagonal boron nitride (hBN), transition metal-dichalcogenides, MXenes, black phosphor, carbon nanomembranes (CNMs), 2D polymers, 2D metal organic frameworks (MOFs) and covalent organic frameworks (COFs). Elastic, fracture, bending and interfacial properties of these materials have been determined using a variety of experimental techniques including atomic force microscopy based nanoindentation, in situ tensile/fracture testing, bulge testing, Raman spectroscopy, Brillouin light scattering and buckling-based metrology. Additionally, we address recent advances of 2D materials in a variety of mechanical applications, including resonators, microphones and nanoelectromechanical sensors. With the emphasis on progress and challenges in the mechanical characterization of inorganic and molecular 2D materials, we expect a continuous growth of interest and more systematic experimental work on the mechanics of such ultrathin nanomaterials.
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Affiliation(s)
- Xianghui Zhang
- Physics of Supramolecular Systems and Surfaces, Bielefeld University, 33615 Bielefeld, Germany.
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50
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Wang H, Wang J, Cai G, Liu Y, Qu Y, Wu T. A Physical Perspective to the Inductive Function of Myelin-A Missing Piece of Neuroscience. Front Neural Circuits 2021; 14:562005. [PMID: 33536878 PMCID: PMC7848263 DOI: 10.3389/fncir.2020.562005] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2020] [Accepted: 12/09/2020] [Indexed: 11/21/2022] Open
Abstract
Starting from the inductance in neurons, two physical origins are discussed, which are the coil inductance of myelin and the piezoelectric effect of the cell membrane. The direct evidence of the coil inductance of myelin is the opposite spiraling phenomenon between adjacent myelin sheaths confirmed by previous studies. As for the piezoelectric effect of the cell membrane, which has been well-known in physics, the direct evidence is the mechanical wave accompany with action potential. Therefore, a more complete physical nature of neural signals is provided. In conventional neuroscience, the neural signal is a pure electrical signal. In our new theory, the neural signal is an energy pulse containing electrical, magnetic, and mechanical components. Such a physical understanding of the neural signal and neural systems significantly improve the knowledge of the neurons. On the one hand, we achieve a corrected neural circuit of an inductor-capacitor-capacitor (LCC) form, whose frequency response and electrical characteristics have been validated by previous studies and the modeling fitting of artifacts in our experiments. On the other hand, a number of phenomena observed in neural experiments are explained. In particular, they are the mechanism of magnetic nerve stimulations and ultrasound nerve stimulations, the MRI image contrast issue and Anode Break Excitation. At last, the biological function of myelin is summarized. It is to provide inductance in the process of neural signal, which can enhance the signal speed in peripheral nervous systems and provide frequency modulation function in central nervous systems.
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Affiliation(s)
- Hao Wang
- Institute of Biomedical & Health Engineering, Shenzhen Institutes of Advanced Technology (SIAT), Chinese Academy of Sciences (CAS), Shenzhen, China.,Department of Electrical and Computer Engineering, National University of Singapore, Singapore, Singapore
| | - Jiahui Wang
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore, Singapore
| | - Guangyi Cai
- Institute of Biomedical & Health Engineering, Shenzhen Institutes of Advanced Technology (SIAT), Chinese Academy of Sciences (CAS), Shenzhen, China
| | - Yonghong Liu
- Institute of Biomedical & Health Engineering, Shenzhen Institutes of Advanced Technology (SIAT), Chinese Academy of Sciences (CAS), Shenzhen, China
| | - Yansong Qu
- Institute of Biomedical & Health Engineering, Shenzhen Institutes of Advanced Technology (SIAT), Chinese Academy of Sciences (CAS), Shenzhen, China
| | - Tianzhun Wu
- Institute of Biomedical & Health Engineering, Shenzhen Institutes of Advanced Technology (SIAT), Chinese Academy of Sciences (CAS), Shenzhen, China.,Key Laboratory of Health Bioinformatics, Chinese Academy of Sciences, Shenzhen, China
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