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Multi-field Coupled Inverse Hall–Petch Relations for Ferroelectric Nanocrystals

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Acta Mechanica Solida Sinica 2024年第1期37卷 139-147页

作者： Xiaodong Zhang Wei Yan Xuhui Lou Yujun Chen Zhihong Zhou Qingyuan Wang Lianhua Ma xiaobao tian Non-Destructive Testing Laboratory School of Quality and Technical SupervisionHebei UniversityBaoding 071002China AVIC Huiyang Aviation Propeller Co. LtdBaoding 071051China Department of Mechanics and Engineering Sichuan UniversityChengdu 610065China Yibin Institute of Industrial Technology Sichuan University Yibin ParkYibin 644000China Research Institute of Interdisciplinary Sciences(RISE) Dongguan University of TechnologyDongguan 523808China School of Materials Science and Engineering Dongguan University of TechnologyDongguan 523808China

Tailoring grain size can improve the strength of polycrystals by regulating the proportion of grains to grain boundaries and the interaction *** the grain size decreases to the nanoscale,the deformation mechanism in polycrystals shifts from being primarily mediated by dislocations to deformation occurring within the grains and grain ***,the mechanism responsible for fine-grain strengthening in ferroelectric materials remains unclear,primarily due to the complex multi-field coupling effect arising from spontaneous *** molecular dynamics simulations,we investigate the strengthening mechanism of barium titanate(BaTiO3),with extremely fine-grain *** material exhibits an inverse Hall–Petch relationship between grain size and strength,rooting in the inhomogeneous concentration of atomic strain and grain ***,we present a theoretical model to predict the transition from the inverse Hall–Petch stage to the Hall–Petch stage based on strength variations with size,which aligns well with the simulation *** has been found that the piezoelectric properties of the BaTiO3 are affected by polarization domain switching at various grain *** study enhances our understanding of the atomic-scale mechanisms that contribute to the performance evolution of fine-grain nano-ferroelectric *** also provides valuable insights into the design of extremely small-scale ferroelectric components.

关键词： Ferroelectrics Multi-field coupling Molecular dynamics Fine-grain reinforcement Inverse Hall-Petch effect

用于生理健康和动作行为监测的柔性多相钛酸钡压电传感器研究

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生物医学工程学杂志 2024年第3期41卷 421-429,438页

作者：曾庆昊韩书朗梁英田晓宝四川大学建筑与环境学院成都610065 四川大学机械工程学院成都610065

自供电可穿戴压电传感设备需要柔韧性和高压电性以满足个性化健康安全管理需求。针对压电陶瓷压电性高、柔性差的特点,本文设计了一种基于多相钛酸钡(BTO)柔性压电陶瓷膜的高性能压电传感器,即多相BTO传感器。无衬底自支撑的多相BTO膜... 详细信息

自供电可穿戴压电传感设备需要柔韧性和高压电性以满足个性化健康安全管理需求。针对压电陶瓷压电性高、柔性差的特点,本文设计了一种基于多相钛酸钡(BTO)柔性压电陶瓷膜的高性能压电传感器,即多相BTO传感器。无衬底自支撑的多相BTO膜具有优异的柔韧性,厚度为33μm时可实现180°弯曲,厚度为5μm时可在1×10^(4)次弯曲循环中表现出良好的抗弯曲疲劳性。所制备的多相BTO传感器在经过1.2×10^(4)次压电循环测试后仍能保持良好的压电稳定性。基于此传感器的柔韧性、高压电性、可穿戴性、便携性和无电池自供电特性,开发的智能面罩可以实时监测不同频率和振幅的呼吸信号。此外,将传感器安装在手部或肩部,还可以检测到不同的手势和手臂动作。综上,本文开发的多相BTO传感器有望为生理健康和行为活动监测应用开发出便捷高效的可穿戴传感设备。

关键词：可穿戴设备柔性压电陶瓷压电传感器

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Enhancing electrochemical performance of ultrasmall Fe_(2)O_(3)-embedded carbon nanotubes via combusting-induced high-valence dopants

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Journal of Materials Science & Technology 2023年第3期134卷 142-150页

作者： Yuan Wang Tao Zhang Jianfei Xiao xiaobao tian Shaojun Yuan Low-carbon Technology and Chemical Reaction Engineering Lab College of Chemical EngineeringSichuan UniversityChengdu 610065China College of Architecture and Environment Sichuan UniversityChengdu 610065China

Doping is a reasonable solution to improve the electronic structure and surface properties of ***,we propose a rapid and simple methodology,flame synthesis,as an effective preparation strategy for incorporating high-valence metal ions(Ti^(4+),Sn^(4+),and Zr^(4+))into ultrasmall Fe_(2)O_(3)on carbon nanotube support(i.e.,M-FeO-CNT).The resulting materials exhibit not only a boosted Na+adsorption as shown by density functional theory(DFT)calculations,but also display an increased oxygen *** electrochemical activity and charge transfer efficiency of Fe 2 O 3 can be improved by reasonably sub-stituting Fe 3+with Ti^(4+),Sn^(4+),and Zr^(4+).The electrochemical investigation of Ti-doped Fe 2 O 3(Ti-FeO-CNT)electrode demonstrates a splendid specific capacitance of 1.25 F cm^(−2)at 1 mA cm^(−2)in 1 M Na_(2)SO_(4).This is significantly higher as compared to the capacitance of 0.48 F cm^(−2).Flexible solid-state asymmetric su-percapacitor Ti-FeO-CNT//MnO_(2)is verified with operating voltage of 2.0 V and stability over 3000 cycles,and delivers a high energy density of 2.14 mWh cm^(−3)at power density of 25 mW cm−*** flame synthesis is expected to be widely applicable for the preparation of high-valence metal ions doped nanosized Fe_(2)O_(3)functionalized materials,thus opening up new avenues for energy and catalysis research.

关键词： Ultrasmall Fe_(2)O_(3)nanoparticles Doping Flame synthesis Flexible supercapacitor DFT calculations

Decomposition of(c+a) Dislocations in Magnesium Alloys

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Acta Mechanica Solida Sinica 2022年第3期35卷 461-469页

作者： Zikun Li Jing Tang xiaobao tian Qingyuan Wang Wentao Jiang Haidong Fan Department of Mechanics Sichuan UniversityChengdu 610065China

In this paper,molecular dynamics simulations are performed to investigate the decomposition of(c+a)dislocations on both pyramidal-Ⅰ and pyramidal-Ⅱ *** pyramidal-Ⅰ dislocations are decomposed into(c)and(a)dislocations under shear stress at 0-400 K,which all reside on the basal *** 500-700 K,the dislocations are transited onto the basal plane at zero stress,then decomposed into(c)and(a)dislocations under shear *** particular,at 700 K,the dislocation is possibly decomposed spontaneously at zero *** the pyramidal-Ⅱ dislocations,the core is glissile below 400 *** 500 K,the dislocation is transited onto the basal plane under shear *** 600-700 K,basal(c+a)dislocation is formed at zero stress,but then decomposed under shear *** dislocation core energy is calculated to explain the *** is found that the energy of decomposed(c+a)dislocation is high,the energy of pyramidal(c+a)dislocation is intermediate,and the energy of basal(c+a)dislocation is *** results provide new insights into the behaviors of pyramidal dislocations and temperature effects.

关键词： Magnesium alloys Pyramidal(c+a)dislocations Molecular dynamics Decomposition

Hardening effects of sheared precipitates on {1121} twinning in magnesium alloys

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Journal of Magnesium and Alloys 2023年第2期11卷 580-591页

作者： Jing Tang Wentao Jiang Qingyuan Wang xiaobao tian Dean Wei Haidong Fan Department of Mechanics Sichuan UniversityChengdu 610065China School of Mechanics and Engineering Southwest Jiaotong UniversityChengdu 610031China

The interactions between a plate-like precipitate and two twin boundaries(TBs)({1012},{1121}) in magnesium alloys are studied using molecular dynamics(MD) simulations. The precipitate is not sheared by {1012} TB, but sheared by {1121} TB. Shearing on the(110) plane is the predominant deformation mode in the sheared precipitate. Then, the blocking effects of precipitates with different sizes are studied for {1121} twinning. All the precipitates show a blocking effect on {1121} twinning although they are sheared, while the blocking effects of precipitates with different sizes are different. The blocking effect increases significantly with the increasing precipitate length(in-plane size along TB) and thickness, whereas changes weakly as the precipitate width changes. Based on the revealed interaction mechanisms, a critical twin shear is calculated theoretically by the Eshelby solutions to determine which TB is able to shear the precipitate. In addition, an analytical hardening model of sheared precipitates is proposed by analyzing the force equilibrium during TB-precipitate interactions. This model indicates that the blocking effect depends solely on the area fraction of the precipitate cross-section, and shows good agreement with the current MD simulations. Finally, the blocking effects of plate-like precipitates on the {1012} twinning(non-sheared precipitate), {1121} twinning(sheared precipitate) and basal dislocations(non-sheared precipitate) are compared together. Results show that the blocking effect on {1121} twinning is stronger than that on {1012} twinning, while the effect on basal dislocations is weakest. The precipitate-TB interaction mechanisms and precipitation hardening models revealed in this work are of great significance for improving the mechanical property of magnesium alloys by designing microstructure.

关键词： Magnesium alloys Precipitate-twin boundary interactions Sheared precipitate Precipitation hardening model Molecular dynamics simulations

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锆中层错金字塔与点缺陷的相互作用研究

固体力学学报 2024年第3期45卷 289-301页

作者：谢荣轩刘燕许传龙田晓宝蒋文涛王清远范海冬四川大学力学系成都610065

锆及其合金具有优异的力学性能和耐腐蚀性能、极小的热中子吸收截面,被用作核燃料包壳材料.在辐照环境中,锆合金内部产生大量的辐照缺陷,严重降低其力学性能和服役寿命.本文运用分子动力学方法研究了锆中层错金字塔与点缺陷(间隙原子、... 详细信息

锆及其合金具有优异的力学性能和耐腐蚀性能、极小的热中子吸收截面,被用作核燃料包壳材料.在辐照环境中,锆合金内部产生大量的辐照缺陷,严重降低其力学性能和服役寿命.本文运用分子动力学方法研究了锆中层错金字塔与点缺陷(间隙原子、空位)的相互作用,发现当温度为0K和300K时层错金字塔只能吸收间隙原子;当温度为600 K时层错金字塔可以同时吸收间隙原子和空位.为了解释此现象,本文计算了间隙原子/空位与层错金字塔的结合能,结果表明结合能与点缺陷的类型/位置有关:间隙原子的结合能远大于空位结合能,故间隙原子更易于被吸收;同时距离层错金字塔越近,结合能越大,两种点缺陷也更易于被吸收.本文的模拟成果有助于学界认识锆中辐照缺陷的长大机制,为锆合金的抗辐照设计提供理论指导.

关键词：锆分子动力学辐照点缺陷层错金字塔

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High Efficiency and Anomalous Photoacoustic Behavior in Vertical CNTs Array

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Energy & Environmental Materials 2023年第1期6卷 105-110页

作者： Jiapu Li Ziyu Wang Laiming Jiang Zechuan Yu Xu Ge Jun Ouyang Xiaofei Yang xiaobao tian He tian Benpeng Zhu School of Optical and Electronic Information Huazhong University of Science and TechnologyWuhan 430074China The Institute of Technological Sciences Wuhan UniversityWuhan 430072China College of Materials Science and Engineering Sichuan UniversityChengdu 610064China School of Civil Engineering and Architecture Wuhan University of TechnologyWuhan 430070China Department of Mechanics Sichuan UniversityChengdu 610065China Institute of Microelectronics and Beijing National Research Center for Information Science and Technology(BNRist) Tsinghua UniversityBeijing 100084China

Miniaturized sound generators are attractive to realize intriguing *** device’s application is seriously limited due to the frequency-doubling *** address this issue,photoacoustic sound generator is considered as a promising ***,based on vertical single-wall carbon nanotubes(CNTs)array,we introduce a photoacoustic sound generator with internal nano-Helmholtz *** from traditional device that generates sound by periodically heating up the open space air around material,this sound generator produces an audio signal by forming a forced vibration of the air inside the ***,anomalous photoacoustic behavior is observed that the sound pressure level(SPL)curve has a resonance peak,the corresponding frequency of which is inversely proportional to the CNTs array’s ***,the energy conversion efficiency of this photoacoustic device is 1.64 times as large as that of a graphene sponge-based photoacoustic *** importantly,this device can be employed for music playing,bringing a new clew for the development of musical instruments in the future.

关键词： anomalous photoacoustic behavior CNTs array Nano-Helmholtz Cavity photoacoustic sound generator

Entanglement dynamics in κ-deformed spacetime

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Science China(Physics,Mechanics & Astronomy) 2024年第10期Mechanics & Astronomy) .卷 37-58页

作者： xiaobao Liu Zehua tian Jiliang Jing Department of Physics and Electrical Engineering Liupanshui Normal University School of Physics Hangzhou Normal University CAS Key Laboratory of Microscale Magnetic Resonance and School of Physical Sciences University of Science and Technology of China Department of Physics Key Laboratory of Low Dimensional Quantum Structures and Quantum Control of Ministry of EducationSynergetic Innovation Center for Quantum Effects and ApplicationsHunan Normal University

We treat two identical and mutually independent two-level atoms that are coupled to a quantum field as an open quantum *** master equation that governs their evolution is derived by tracing over the degree of freedom of the field. With this, we compare the entanglement dynamics of the two atoms moving with different trajectories in κ-deformed and Minkowski ***, when the environment-induced interatomic interaction does not exist, the entanglement dynamics of two static atoms in κ-deformed spacetime are reduced to that in Minkowski spacetime in the case that the spacetime deformation parameter κ is sufficiently large as theoretically predicted. However, if the atoms undergo relativistic motion, regardless of whether inertial or non-inertial, their entanglement dynamics in κ-deformed spacetime behave differently from that in Minkowski spacetime even when κ is large. We investigate various types of entanglement behavior, such as decay and generation, and discuss how different relativistic motions, such as uniform motion in a straight line and circular motion, amplify the differences in the entanglement dynamics between the κ-deformed and Minkowski spacetime cases. In addition, when the environment-induced interatomic interaction is considered, we find that it may also enhance the differences in the entanglement dynamics between these two ***, in principle, one can tell whether she/he is in κ-deformed or Minkowski spacetime by checking the entanglement behavior between two atoms in certain circumstances.

关键词： quantum entanglement $\kappa$-deformed spacetime relativistic motion environment-induced interatomic interaction quantum field theory in curved spacetime

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BASIC THEOREMS IN LINEAR MICROMORPHIC THERMOELECTROELASTICITY AND THEIR PRIMARY APPLICATION

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Acta Mechanica Solida Sinica 2013年第2期26卷 161-176页

作者： Weizhong Cao Xinhua Yang xiaobao tian Department of Mechanics Huazhong University of Science and Technology State Key Laboratory of Materials Processing and Die & Mould Technology Huazhong University of Science and Technology

As a natural extension of the micromorphic continuum theory, the linear theory of micromorphic thermoelectroelasticity is developed to characterize the nano-micro scale behavior of thermoelectroelastic materials with remarkable microstructures. After the basic governing equations are given and the reciprocal theorem is deduced, both the generalized variational prin- ciple and the generalized Hamilton principle for mixed boundary-initial value problems of micro- morphic thermoelectroelastodynamics in convolution form are established. Finally, as a primary application, steady state responses of an unbounded homogeneous isotropic micromorphic thermo- electroelastic body to external concentrated loads with mechanical, electric, and thermal origins are analyzed.

关键词： micromorphic thermoelectroelasticity reciprocal theorem variational principle,concentrated load microstructure