针对有界随机噪声激励下轻敲式原子力显微镜(AFM:Atomic force microscope)系统的非线性动力学问题,建立Lennard-Jones力场作用下针尖-样品的集总参数模型,应用现代微分方程和分岔理论,分析了随机扰动强度和弯月面接触角对AFM针尖-样品...针对有界随机噪声激励下轻敲式原子力显微镜(AFM:Atomic force microscope)系统的非线性动力学问题,建立Lennard-Jones力场作用下针尖-样品的集总参数模型,应用现代微分方程和分岔理论,分析了随机扰动强度和弯月面接触角对AFM针尖-样品耦合系统动力学特性的影响。结果表明,轻敲式AFM耦合动力学系统中存在丰富的周期运动和混沌运动,表现出复杂的非线性行为,混沌特性随着随机扰动强度增大而增强,弯月面接触角越大混沌特性越明显,因此在轻敲式AFM优化设计中,随机噪声对AFM系统的影响不可忽视。展开更多
The microscopic mechanical characteristics of ultranano-crystalline diamond films which were prepared in four different atmospheres were investigated for the applications in microelectron-mechanical system（MEMS）.The...The microscopic mechanical characteristics of ultranano-crystalline diamond films which were prepared in four different atmospheres were investigated for the applications in microelectron-mechanical system（MEMS）.The loading-unloading curves and the change of modulus and hardness of samples along with depth were achieved through nanoindenter.The results show that the films which are made in atmosphere without Ar have the highest recovery of elasticity,hardness（72.9 GPa） and elastic modulus（693.7 GPa） among the samples.Meanwhile,samples fabricated at a low Ar content have higher hardness and modulus.All the results above demonstrate that atmosphere without Ar or low Ar content leads to better mechanical properties of nanodiamond films that are the candidates for applications in MEMS.展开更多
Beams,plates,and shells,as the fundamental mechanical structures,are widely used in microelectromechanical systems(MEMS)and nanoelectromechanical systems(NEMS)as sensors,actuators,energy harvesters,and among others.De...Beams,plates,and shells,as the fundamental mechanical structures,are widely used in microelectromechanical systems(MEMS)and nanoelectromechanical systems(NEMS)as sensors,actuators,energy harvesters,and among others.Deeply understand the electromechanical coupling of these dielectric structures is of crucial for designing,fabricating,and optimizing practice devices in these systems.Herein we demonstrate the electromechanical coupling in flexoelectric circular plate,in which higher-order strain gradients were considered to extend the classical electromechanical properties to isotropic materials,in which the non-uniform distribution of the electric potential along the radial direction was considered.Analytical solutions for the vibration modes of the flexoelectric circular plates showed that the dynamic modes were totally different from the piezoelectric circular plates owing to the inversion symmetry breaking by the strain gradient.The electromechanical coupling dynamic modes are sensitive to bending,twisting modes owing to the sensitivity of the flexoelectric effect to bending.This work provides a fundamental understanding of the electromechanical coupling in flexoelectric circular plate,which is helpful in designing novel flexoelectric circular plate-based devices,such as flexoelectric mirrors.展开更多
Due to the coupling of piezoelectric and semiconducting dual properties,much attention has been focused on the piezoelectric semiconductor materials,such as ZnO,ZnS,CdS and GaN.With the usage of these piezoelectric se...Due to the coupling of piezoelectric and semiconducting dual properties,much attention has been focused on the piezoelectric semiconductor materials,such as ZnO,ZnS,CdS and GaN.With the usage of these piezoelectric semiconductor materials,novel nanodevices have been demonstrated,from which a new field called piezotronics was formulated.The core of piezotronics is to study the mechanism of the piezoelectric effect on tuning the charge transport behavior across various junctions or interfaces,with potential applications in sensors,microelectromechanical systems,and force/pressure triggered electric devices.Here following the theoretical frame work of piezotronic effect,analytical solutions of piezoelectric heterojunction are presented to investigate the electrical transport behavior at a p-n junction.Numerical simulation is given for guiding future experimental measurements.展开更多
文摘针对有界随机噪声激励下轻敲式原子力显微镜(AFM:Atomic force microscope)系统的非线性动力学问题,建立Lennard-Jones力场作用下针尖-样品的集总参数模型,应用现代微分方程和分岔理论,分析了随机扰动强度和弯月面接触角对AFM针尖-样品耦合系统动力学特性的影响。结果表明,轻敲式AFM耦合动力学系统中存在丰富的周期运动和混沌运动,表现出复杂的非线性行为,混沌特性随着随机扰动强度增大而增强,弯月面接触角越大混沌特性越明显,因此在轻敲式AFM优化设计中,随机噪声对AFM系统的影响不可忽视。
基金Projects(51301211,21271188)supported by the National Natural Science Foundation of ChinaProject(2010A0302013)supported by the Foundation of China Academy of Engineering Physics+3 种基金Project(ZZ13005)supported by the Foundation of Laboratory of Ultra Precision Manufacturing Technology of China Academy of Engineering PhysicsProject(2012M521541)supported by the China Postdoctoral Science FoundationProject(20110933K)supported by the State Key Laboratory of Powder Metallurgy,ChinaProject(CSU2013016)support by and the Open-End Fund for Valuable and Precision instruments of Central South University,China
文摘The microscopic mechanical characteristics of ultranano-crystalline diamond films which were prepared in four different atmospheres were investigated for the applications in microelectron-mechanical system（MEMS）.The loading-unloading curves and the change of modulus and hardness of samples along with depth were achieved through nanoindenter.The results show that the films which are made in atmosphere without Ar have the highest recovery of elasticity,hardness（72.9 GPa） and elastic modulus（693.7 GPa） among the samples.Meanwhile,samples fabricated at a low Ar content have higher hardness and modulus.All the results above demonstrate that atmosphere without Ar or low Ar content leads to better mechanical properties of nanodiamond films that are the candidates for applications in MEMS.
基金supported by the National Natural Science Foundation of China(Grant Nos.12122209,12072251,and 12102153)the Project B18040.
文摘Beams,plates,and shells,as the fundamental mechanical structures,are widely used in microelectromechanical systems(MEMS)and nanoelectromechanical systems(NEMS)as sensors,actuators,energy harvesters,and among others.Deeply understand the electromechanical coupling of these dielectric structures is of crucial for designing,fabricating,and optimizing practice devices in these systems.Herein we demonstrate the electromechanical coupling in flexoelectric circular plate,in which higher-order strain gradients were considered to extend the classical electromechanical properties to isotropic materials,in which the non-uniform distribution of the electric potential along the radial direction was considered.Analytical solutions for the vibration modes of the flexoelectric circular plates showed that the dynamic modes were totally different from the piezoelectric circular plates owing to the inversion symmetry breaking by the strain gradient.The electromechanical coupling dynamic modes are sensitive to bending,twisting modes owing to the sensitivity of the flexoelectric effect to bending.This work provides a fundamental understanding of the electromechanical coupling in flexoelectric circular plate,which is helpful in designing novel flexoelectric circular plate-based devices,such as flexoelectric mirrors.
基金partly supported by the Beijing Institute of Nanoenergy and NanosystemsChinese Academy of Sciencesthe Fundamental Research Funds for the Central Universities(Grant No.Lzujbky-2013-35)
文摘Due to the coupling of piezoelectric and semiconducting dual properties,much attention has been focused on the piezoelectric semiconductor materials,such as ZnO,ZnS,CdS and GaN.With the usage of these piezoelectric semiconductor materials,novel nanodevices have been demonstrated,from which a new field called piezotronics was formulated.The core of piezotronics is to study the mechanism of the piezoelectric effect on tuning the charge transport behavior across various junctions or interfaces,with potential applications in sensors,microelectromechanical systems,and force/pressure triggered electric devices.Here following the theoretical frame work of piezotronic effect,analytical solutions of piezoelectric heterojunction are presented to investigate the electrical transport behavior at a p-n junction.Numerical simulation is given for guiding future experimental measurements.
