The two-parameter Weibull model is used to describe the fiber strength distribution.The stress carried by the intact and fracture fibers on the matrix crack plane during unloading/reloading is determined based on the ...The two-parameter Weibull model is used to describe the fiber strength distribution.The stress carried by the intact and fracture fibers on the matrix crack plane during unloading/reloading is determined based on the global load sharing criterion.The axial stress distribution of intact fibers upon unloading and reloading is determined based on the mechanisms of fiber sliding relative to matrix in the interface debonded region.The interface debonded length,unloading interface counter slip length,and reloading interface new slip length are obtained by the fracture mechanics approach.The hysteresis loops corresponding to different stresses considering fiber failure are compared with the cases without considering fiber failure.The effects of fiber characteristic strength and fiber Weibull modulus on the fiber failure,the shape,and the area of the hysteresis loops are analyzed.The predicted quasi-static unloading/reloading hysteresis loops agree well with experimental data.展开更多
In the nondestructive testing and evaluation area,magnetic major hysteresis loop measurement technology are widely applied for ferromagnetic material evaluation.However the characterization ability of major hysteresis...In the nondestructive testing and evaluation area,magnetic major hysteresis loop measurement technology are widely applied for ferromagnetic material evaluation.However the characterization ability of major hysteresis loop measurement technology greatly varies as the evaluated target properties.To solve this limitation,magnetic minor hysteresis loops,which reflect the responses of ferromagnetic material magnetization in a systematic way,is recommend.Inspired by plenty of information carried by the minor loops,the sensitivity mapping technique was developed to achieve the highest sensitivity of minor-loop parameters to the nondestructively evaluated targets.In this study,for the first time,the sensitivity mapping technique is used to measure the tensile force in a steel strand and evaluate the effective case depth in induction-hardened steel rods.The method and procedures for the sensitivity mapping technique are given before experimental detection.The obtained experimental results indicate that the linear correlation between the induced voltage(or the magnetic induction intensity)and the tensile force(or effective case depth)exists at most of the locations in the cluster of minor loops.The obtained sensitivity maps can be used to optimize the applied magnetic field(or excitation current)and the analyzed locations at the minor loops for achieving the highest sensitivity.For the purpose of tensile force measurement,it is suggested that the strand should be firstly magnetized to the near-saturation state and then restored to the remanent state.In this way,the highest sensitivity is obtained as about 15.26 mV/kN.As for the induction-hardened steel rods,the highest sensitivity of magnetic induction intensity to the effective case depth occurs under low magnetic field conditions and the absolute value of the highest sensitivity is about 0.1110 T/mm.This indicates that if the highest sensitivity is required in the case depth evaluation,the induction-hardened steel rods are only required to be weakly magnetized.The proposed sensitivity mapping technique shows the good performance in the high-sensitivity evaluation of tensile force and case depth in ferromagnetic materials and its application scope can be extended to other nondestructive detection fields.展开更多
The ferroelectric response of bismuth titanate Bi4Ti3O12 （BIT） thin film is studied through a Monte Carlo simulation of hysteresis loops. The ferroelectric system is described by using a Diffour Hamiltonian with thr...The ferroelectric response of bismuth titanate Bi4Ti3O12 （BIT） thin film is studied through a Monte Carlo simulation of hysteresis loops. The ferroelectric system is described by using a Diffour Hamiltonian with three terms： the electric field applied in the z direction, the nearest dipole-dipole interaction in the transversal （x-y） direction, and the nearest dipole-dipole interaction in the direction perpendicular to the thin film （the z axis）. In the sample construction, we take into consideration the dipole orientations of the monoclinic and orthorhombic structures that can appear in BIT at low temperature in the ferroelectric state. The effects of temperature, stress, and the concentration of pinned dipole defects are assessed by using the hysteresis loops. The results indicate the changes in the hysteresis area with temperature and stress, and the asymmetric hysteresis loops exhibit evidence of the imprint failure mechanism with the emergence of pinned dipolar defects. The simulated shift in the hysteresis loops conforms to the experimental ferroelectric response.展开更多
Magnetic hysteresis and compensation behavior of a mixed spin-（1, 3/2） Ising model on a square lattice are investigated in the framework of effective field theory based on a probability distribution technique. The e...Magnetic hysteresis and compensation behavior of a mixed spin-（1, 3/2） Ising model on a square lattice are investigated in the framework of effective field theory based on a probability distribution technique. The effect of random crystal field, ferromagnetic and ferrimagnetic exchange interaction on hysteresis loops and compensation phenomenon are discussed. A number of characteristic phenomena have been reported such as the observation of triple hysteresis loops at low temperatures and for negative values of random crystal field. Critical and double compensation temperatures have been also found. The obtained results are also compared to some previous works.展开更多
Investigation into the magnets with different squareness of hysteresis loop(SHL) reveals that the microstructure of sintered NdFeB magnets has great effects on the SHL of the magnets. The abnormal grain growth deterio...Investigation into the magnets with different squareness of hysteresis loop(SHL) reveals that the microstructure of sintered NdFeB magnets has great effects on the SHL of the magnets. The abnormal grain growth deteriorates the SHL seriously. The shape of the grain and the grain boundary affect the intensity of demagnetization field, and consequently on the SHL. The added elements have effects on the phase structures and distributions in the magnets, which influences the uniform of demagnetization field.展开更多
Based on the transverse Ising model in the framework of the mean field approximation, this paper discusses a ferroelectric bilayer film with the surface transition layers within each constituent slab and an antiferroe...Based on the transverse Ising model in the framework of the mean field approximation, this paper discusses a ferroelectric bilayer film with the surface transition layers within each constituent slab and an antiferroelectric interracial coupling between two slabs. The hysteresis loop of a bilayer film is investigated. The results show that the surface transition layer in a ferroelectric bilayer film plays a significant role in realizing the multiple-state memory.展开更多
The magnetic susceptibility of ternary metal Prussian blue analogues with orthorhombic structure is studied using Ising model. Within the frame work of effective-field theory with correlations, the roles of the mole f...The magnetic susceptibility of ternary metal Prussian blue analogues with orthorhombic structure is studied using Ising model. Within the frame work of effective-field theory with correlations, the roles of the mole fraction y, uniaxial magnetic anisotropy, transverse and longitudinal magnetic field are discussed in detabls. The temperature dependence of the magnetic susceptibility is also investigated. The interesting phenomenon of the inverted magnetic hysteresis loop has been found. The results can help to understand the experimental work of the molecule-based ferri- ferrimagnet.展开更多
The simulation of the transformer transient is one of the indispensable qualifications for improving the performance of transformer protection, the key technique of the transformer's transient simulation is the tr...The simulation of the transformer transient is one of the indispensable qualifications for improving the performance of transformer protection, the key technique of the transformer's transient simulation is the treatment of ferromagnetic elements' loop. Thus the shapes of the primary hysteresis loop and each internal secondary hysteresis loop in the identical magnetism conducting are analyzed, and then it is proposed that there are some fractal characteristics in the relation between them. The fractal phenomenon of the ferromagnetic elements' hysteresis loop in the transformer's transient simulation is first brought forward, the mutuality between the ferromagnetic elements' primary hysteresis loop and its secondary hysteresis loops is revealed in mechanism by using the fractal theory. According to the iterated function system of fractal theory, the secondary hysteresis loops can be generated by the iterative calculation of the primary loop. The simulation results show the validity of this idea.展开更多
Total strain controlled cyclic test was performed on 316 LN under uniaxial loadings. Through the partitioning of hysteresis loops, the evolution of two components of cyclic flow stress, the internal and effective stre...Total strain controlled cyclic test was performed on 316 LN under uniaxial loadings. Through the partitioning of hysteresis loops, the evolution of two components of cyclic flow stress, the internal and effective stresses, was reported. The former one determines the cyclic stress response. Based on the transmission electron microscopic（TEM） observation on specimens loaded with scheduled cycles, it is found that planar dislocation structures prevail during the entire cyclic process at low strain amplitude, while a remarkable dislocation rearrangement from planar structures to heterogeneous spatial distributions is companied by a cyclic softening behavior at high strain amplitude. The competition between the evolution of the intergranular and the intragranular components of the internal stress caused by the transition of slip mode induces the cyclic hardening and softening at high strain levels. The intergranular internal stress represents the most part of the internal stress at low strain level.展开更多
Environmentally friendly antiferroelectric NaNbO,(NN)materials exhibit promising potential in energy storage and electrostrain applications.At room temperature,NN is an antiferroelectric P phase(Space group Pbma)that ...Environmentally friendly antiferroelectric NaNbO,(NN)materials exhibit promising potential in energy storage and electrostrain applications.At room temperature,NN is an antiferroelectric P phase(Space group Pbma)that coexists with a metastable ferroelectric Q phase(Space group P2_(1)ma),so the electric fieldinduced phase transition is irreversible.To stabilize the intrinsic antiferroelectric properties of NNs,phase structure regulation has emerged as a critical research focus.We chose the variable-valence elements Sn and Ce for doping in NN.Through atmospheric sintering,the valence states of the doped ions were altered,resulting in changes in their corresponding substitution positions.This confirmed that the doped ions could be successfully incorporated into the lattice as designed.Importantly,the x=0.04 ceramic exhibited a reversible phase transition between the AFE and FE state resulting in a standard double hysteresis loop at room temperature and a large electrostrain of 0.38%.These findings demonstrat that valence state-controlled co-doping effectively optimizes the antiferroelectric phase stability and functional performance of NN basedmaterials.展开更多
Antiferroelectrics(AFEs)possess great potential for high performance dielectric capacitors,due to their distinct double hysteresis loop with high maximum polarization and low remnant polarization.However,the well-know...Antiferroelectrics(AFEs)possess great potential for high performance dielectric capacitors,due to their distinct double hysteresis loop with high maximum polarization and low remnant polarization.However,the well-known NaNbO_(3) lead-free antiferroelectric(AFE)ceramic usually exhibits square-like P–E loop related to the irreversible AFE P phase to ferroelectric(FE)Q phase transition,yielding low recoverable energy storage density(Wrec).Herein,significantly improved Wrec up to 3.3 J/cm^(3) with good energy storage efficiency(η)of 42.4% was achieved in Na_(0.7)Ag_(0.3)Nb_(0.7)Ta_(0.3)O_(3)(30Agsingle bond30Ta)ceramic with well-defined double P–E loop,by tailoring the A-site electronegativity with Ag+and B-site polarizability with Ta^(5+).The Transmission Electron Microscope,Piezoresponse Force Microscope and in-situ Raman spectra results verified a good reversibility between AFE P phase and high-field-induced FE Q phase.The improved stability of AFE P phase,being responsible for the double P–E loop and improved Wrec,was attributed to the decreased octahedral tilting angles and cation displacements.This mechanism was revealed by synchrotron X-ray diffraction and Scanning Transmission Electron microscope.This work provides a good paradigm for achieving double P–E loop and high energy storage density in NaNbO_(3)-based ceramics.展开更多
Piezo actuators are widely used in ultra-precision fields because of their high response and nano-scale step length.However,their hysteresis characteristics seriously affect the accuracy and stability of piezo actuato...Piezo actuators are widely used in ultra-precision fields because of their high response and nano-scale step length.However,their hysteresis characteristics seriously affect the accuracy and stability of piezo actuators.Existing methods for fitting hysteresis loops include operator class,differential equation class,and machine learning class.The modeling cost of operator class and differential equation class methods is high,the model complexity is high,and the process of machine learning,such as neural network calculation,is opaque.The physical model framework cannot be directly extracted.Therefore,the sparse identification of nonlinear dynamics(SINDy)algorithm is proposed to fit hysteresis loops.Furthermore,the SINDy algorithm is improved.While the SINDy algorithm builds an orthogonal candidate database for modeling,the sparse regression model is simplified,and the Relay operator is introduced for piecewise fitting to solve the distortion problem of the SINDy algorithm fitting singularities.The Relay-SINDy algorithm proposed in this paper is applied to fitting hysteresis loops.Good performance is obtained with the experimental results of open and closed loops.Compared with the existing methods,the modeling cost and model complexity are reduced,and the modeling accuracy of the hysteresis loop is improved.展开更多
Three-dimensional simulations of ferroelectric hysteresis and butterfly loops are carried out based on solving the time dependent Ginzburg-Landau equations using a finite volume method. The influence of externally mec...Three-dimensional simulations of ferroelectric hysteresis and butterfly loops are carried out based on solving the time dependent Ginzburg-Landau equations using a finite volume method. The influence of externally mechanical loadings with a tensile strain and a compressive strain on the hysteresis and butterfly loops is studied numerically. Different from the traditional finite element and finite difference methods, the finite volume method is applicable to simulate the ferroelectric phase transitions and properties of ferroelectric materials even for more realistic and physical problems.展开更多
Using the Monte Carlo method,the compensation temperature and hysteresis loops of a ferrimagnetic mixed spin-3/2 and spin-5/2 Ising-type graphene-like bilayer are investigated induced by different physical parameters ...Using the Monte Carlo method,the compensation temperature and hysteresis loops of a ferrimagnetic mixed spin-3/2 and spin-5/2 Ising-type graphene-like bilayer are investigated induced by different physical parameters such as crystal field,exchange coupling,external magnetic field,and temperature.The variations of magnetization,magnetic susceptibility,specific heat,and internal energy with the change of temperature are discussed.In addition,we also plot the phase diagrams including transition temperature and compensation temperature.Finally,multiple hysteresis loops under certain parameters are given.展开更多
Based on the low-cycle fatigue tests of carbon and alloy steels,the cyclic properties of hysteresis energy and its changing rules have been analysed.The mathematical formula of cyclic hysteresis energy of the material...Based on the low-cycle fatigue tests of carbon and alloy steels,the cyclic properties of hysteresis energy and its changing rules have been analysed.The mathematical formula of cyclic hysteresis energy of the materials with different cyclic properties have been presented. The total absorbed energy to failure is associated with the variation of cyclic hysteresis energy.展开更多
We exploit the recoil loop measurements to study La0.07 Sr0.33 Mn O3/La0.33 Ca0.67 Mn O3 bilayer film. the asymmetric magnetization reversal in an exchange-biased It is found that the recoil curve encloses a marked ar...We exploit the recoil loop measurements to study La0.07 Sr0.33 Mn O3/La0.33 Ca0.67 Mn O3 bilayer film. the asymmetric magnetization reversal in an exchange-biased It is found that the recoil curve encloses a marked area only in the second quadrant of the hysteresis loop, and the recoil susceptibility in the descending branch of the major loop is evidently higher than that in the ascending branch. The study indicates that the exchange anisotropy of a unidirectional nature and an orientation deviated from the easy axis of the ferromagnetic layer plays a crucial role in creating the reversal asymmetry.展开更多
Zero-temperature Monte Carlo simulations are used to investigate the hysteresis of a magnetic particle ina dipolarIsing model. The magnetic particle is described in a system of permanent dipoles, and the dipoles are l...Zero-temperature Monte Carlo simulations are used to investigate the hysteresis of a magnetic particle ina dipolarIsing model. The magnetic particle is described in a system of permanent dipoles, and the dipoles are locatedin a cubic lattice site. The effects of the shape and the size of the particle on the hysteresis loop at zero temperatureare obtained. For strong exchange interactions, the shapes of magnetic hysteresis loops approach rectangle. For weakexchange interactions, the effects of the size and the shape of the particle on the loops are more remarkable than thoseof strong exchange interactions case. The slope of the hysteresis loop decreases with the increase of the ratio of thesemi major axis to the semi minor axis of the ellipsoidal magnetic particle, and there is an increase of the slope of thehysteresis with the decrease of the size of the magnetic particle. The effects of the shape and size of the particle on thecoercive force at zero temperature are also investigated.展开更多
We described ferromagnetic film and bilayer films composed of two ferromagnetic layers coupled through antiferromagnetic interfacial interaction by classical Heisenberg model and simulated their magnetization state,ma...We described ferromagnetic film and bilayer films composed of two ferromagnetic layers coupled through antiferromagnetic interfacial interaction by classical Heisenberg model and simulated their magnetization state,magnetic permeability,and Faraday effect at zero and finite temperature by using the Landau–Lifshitz–Gilbert(LLG)equation.The results indicate that in a microwave field with positive circular polarization,the ferromagnetic film has one resonance peak while the bilayer film has two resonance peaks.However,the resonance peak disappears in ferromagnetic film,and only one resonance peak emerges in bilayer film in the negative circularly polarized microwave field.When the microwave field’s frequency exceeds the film’s resonance frequency,the Faraday rotation angle of the ferromagnetic film is the greatest,and it decreases when the thickness of the two halves of the bilayer is reduced.When the microwave field’s frequency remains constant,the Faraday rotation angle fluctuates with temperature in the same manner as spontaneous magnetization does.When a DC magnetic field is applied in the direction of the anisotropic axis of the film,the Faraday rotation angle varies with the DC magnetic field and shows a similar shape of the hysteresis loop.展开更多
This paper studies the relaxation processes and electromechanical hysteresis in relaxor piezoceramics based on the PzT system.Measurements and analysis of the electric displacement and mechanical strain hysteresis loo...This paper studies the relaxation processes and electromechanical hysteresis in relaxor piezoceramics based on the PzT system.Measurements and analysis of the electric displacement and mechanical strain hysteresis loops recorded in bipolar AC electric fields in the frequency range 0.001-5 Hz were performed by means of the electromechanical response characterization system(STEPHV)and program(STEP).It was found that the coercive field,remnant and saturation electric displacement,area of hysteresis loops and relative mechanical strain values are strongly dependent on frequency.As a result of this study,complete sets of parameters characterizing the switching and ferroelectric hysteresis processes in relaxor piezoceramics were obtained.展开更多
基金Supported by the National Natural Science Foundation of China(51075204)the Graduate Innovation Foundation of Jiangsu Province(CX08B-133Z)the Doctoral Innovation Foundation of Nanjing University of Aeronautics and Astronautics(BCXJ08-05)~~
文摘The two-parameter Weibull model is used to describe the fiber strength distribution.The stress carried by the intact and fracture fibers on the matrix crack plane during unloading/reloading is determined based on the global load sharing criterion.The axial stress distribution of intact fibers upon unloading and reloading is determined based on the mechanisms of fiber sliding relative to matrix in the interface debonded region.The interface debonded length,unloading interface counter slip length,and reloading interface new slip length are obtained by the fracture mechanics approach.The hysteresis loops corresponding to different stresses considering fiber failure are compared with the cases without considering fiber failure.The effects of fiber characteristic strength and fiber Weibull modulus on the fiber failure,the shape,and the area of the hysteresis loops are analyzed.The predicted quasi-static unloading/reloading hysteresis loops agree well with experimental data.
基金Supported by National Key R&D Program of China(Grant No.2018YFF01012300)National Natural Science Foundation of China(Grant No.11527801).
文摘In the nondestructive testing and evaluation area,magnetic major hysteresis loop measurement technology are widely applied for ferromagnetic material evaluation.However the characterization ability of major hysteresis loop measurement technology greatly varies as the evaluated target properties.To solve this limitation,magnetic minor hysteresis loops,which reflect the responses of ferromagnetic material magnetization in a systematic way,is recommend.Inspired by plenty of information carried by the minor loops,the sensitivity mapping technique was developed to achieve the highest sensitivity of minor-loop parameters to the nondestructively evaluated targets.In this study,for the first time,the sensitivity mapping technique is used to measure the tensile force in a steel strand and evaluate the effective case depth in induction-hardened steel rods.The method and procedures for the sensitivity mapping technique are given before experimental detection.The obtained experimental results indicate that the linear correlation between the induced voltage(or the magnetic induction intensity)and the tensile force(or effective case depth)exists at most of the locations in the cluster of minor loops.The obtained sensitivity maps can be used to optimize the applied magnetic field(or excitation current)and the analyzed locations at the minor loops for achieving the highest sensitivity.For the purpose of tensile force measurement,it is suggested that the strand should be firstly magnetized to the near-saturation state and then restored to the remanent state.In this way,the highest sensitivity is obtained as about 15.26 mV/kN.As for the induction-hardened steel rods,the highest sensitivity of magnetic induction intensity to the effective case depth occurs under low magnetic field conditions and the absolute value of the highest sensitivity is about 0.1110 T/mm.This indicates that if the highest sensitivity is required in the case depth evaluation,the induction-hardened steel rods are only required to be weakly magnetized.The proposed sensitivity mapping technique shows the good performance in the high-sensitivity evaluation of tensile force and case depth in ferromagnetic materials and its application scope can be extended to other nondestructive detection fields.
基金sponsored by the research departments of the Universidad Nacional de Colombia DIMA and DIB under Project 201010018227-"Crecimientoy caracterización eléctrica y estructural de películas delgadas de BixTiyOz producidas mediante Magnetrón Sputtering"Project 12920-"Desarrollo teóricoexperimental de nanoestructuras basadas en Bismutoy materiales similares""Bisnano Project"
文摘The ferroelectric response of bismuth titanate Bi4Ti3O12 （BIT） thin film is studied through a Monte Carlo simulation of hysteresis loops. The ferroelectric system is described by using a Diffour Hamiltonian with three terms： the electric field applied in the z direction, the nearest dipole-dipole interaction in the transversal （x-y） direction, and the nearest dipole-dipole interaction in the direction perpendicular to the thin film （the z axis）. In the sample construction, we take into consideration the dipole orientations of the monoclinic and orthorhombic structures that can appear in BIT at low temperature in the ferroelectric state. The effects of temperature, stress, and the concentration of pinned dipole defects are assessed by using the hysteresis loops. The results indicate the changes in the hysteresis area with temperature and stress, and the asymmetric hysteresis loops exhibit evidence of the imprint failure mechanism with the emergence of pinned dipolar defects. The simulated shift in the hysteresis loops conforms to the experimental ferroelectric response.
文摘Magnetic hysteresis and compensation behavior of a mixed spin-（1, 3/2） Ising model on a square lattice are investigated in the framework of effective field theory based on a probability distribution technique. The effect of random crystal field, ferromagnetic and ferrimagnetic exchange interaction on hysteresis loops and compensation phenomenon are discussed. A number of characteristic phenomena have been reported such as the observation of triple hysteresis loops at low temperatures and for negative values of random crystal field. Critical and double compensation temperatures have been also found. The obtained results are also compared to some previous works.
基金Project supported by Shanghai Leading Academic Discipline (P1502)
文摘Investigation into the magnets with different squareness of hysteresis loop(SHL) reveals that the microstructure of sintered NdFeB magnets has great effects on the SHL of the magnets. The abnormal grain growth deteriorates the SHL seriously. The shape of the grain and the grain boundary affect the intensity of demagnetization field, and consequently on the SHL. The added elements have effects on the phase structures and distributions in the magnets, which influences the uniform of demagnetization field.
文摘Based on the transverse Ising model in the framework of the mean field approximation, this paper discusses a ferroelectric bilayer film with the surface transition layers within each constituent slab and an antiferroelectric interracial coupling between two slabs. The hysteresis loop of a bilayer film is investigated. The results show that the surface transition layer in a ferroelectric bilayer film plays a significant role in realizing the multiple-state memory.
基金Supported by the Excellent Talents Program of the university of Liaoning Province of China under Grant No.LR201031
文摘The magnetic susceptibility of ternary metal Prussian blue analogues with orthorhombic structure is studied using Ising model. Within the frame work of effective-field theory with correlations, the roles of the mole fraction y, uniaxial magnetic anisotropy, transverse and longitudinal magnetic field are discussed in detabls. The temperature dependence of the magnetic susceptibility is also investigated. The interesting phenomenon of the inverted magnetic hysteresis loop has been found. The results can help to understand the experimental work of the molecule-based ferri- ferrimagnet.
文摘The simulation of the transformer transient is one of the indispensable qualifications for improving the performance of transformer protection, the key technique of the transformer's transient simulation is the treatment of ferromagnetic elements' loop. Thus the shapes of the primary hysteresis loop and each internal secondary hysteresis loop in the identical magnetism conducting are analyzed, and then it is proposed that there are some fractal characteristics in the relation between them. The fractal phenomenon of the ferromagnetic elements' hysteresis loop in the transformer's transient simulation is first brought forward, the mutuality between the ferromagnetic elements' primary hysteresis loop and its secondary hysteresis loops is revealed in mechanism by using the fractal theory. According to the iterated function system of fractal theory, the secondary hysteresis loops can be generated by the iterative calculation of the primary loop. The simulation results show the validity of this idea.
基金Funded by the Nuclear Power Major Project(No.2011zx06004-002)
文摘Total strain controlled cyclic test was performed on 316 LN under uniaxial loadings. Through the partitioning of hysteresis loops, the evolution of two components of cyclic flow stress, the internal and effective stresses, was reported. The former one determines the cyclic stress response. Based on the transmission electron microscopic（TEM） observation on specimens loaded with scheduled cycles, it is found that planar dislocation structures prevail during the entire cyclic process at low strain amplitude, while a remarkable dislocation rearrangement from planar structures to heterogeneous spatial distributions is companied by a cyclic softening behavior at high strain amplitude. The competition between the evolution of the intergranular and the intragranular components of the internal stress caused by the transition of slip mode induces the cyclic hardening and softening at high strain levels. The intergranular internal stress represents the most part of the internal stress at low strain level.
基金sponsored by the Guizhou Tongren University Ph.D.Start-up Fund,China(No.trxyDH2313)Department of Education of Guizhou Province,China(No.QJ[2022]055)+1 种基金Guizhou Key Laboratory of Green Metallurgy and Process Strengthening(No.[2023]026)Jingdezhen University Ph.D.Startup Fund,China(No.jdzxy2502).
文摘Environmentally friendly antiferroelectric NaNbO,(NN)materials exhibit promising potential in energy storage and electrostrain applications.At room temperature,NN is an antiferroelectric P phase(Space group Pbma)that coexists with a metastable ferroelectric Q phase(Space group P2_(1)ma),so the electric fieldinduced phase transition is irreversible.To stabilize the intrinsic antiferroelectric properties of NNs,phase structure regulation has emerged as a critical research focus.We chose the variable-valence elements Sn and Ce for doping in NN.Through atmospheric sintering,the valence states of the doped ions were altered,resulting in changes in their corresponding substitution positions.This confirmed that the doped ions could be successfully incorporated into the lattice as designed.Importantly,the x=0.04 ceramic exhibited a reversible phase transition between the AFE and FE state resulting in a standard double hysteresis loop at room temperature and a large electrostrain of 0.38%.These findings demonstrat that valence state-controlled co-doping effectively optimizes the antiferroelectric phase stability and functional performance of NN basedmaterials.
基金This work was financially supported by the National Natural Science Foundation of China(Grant No.52072080 and 52388201)Guangxi Natural Science Fund for Distinguished Young Scholars(Grant No.2022GXNSFFA035034)+2 种基金Y.Z.acknowledges the support of the Research Grants Council of Hong Kong(Grant No.C5029-18E)J.L.acknowledges the support of Tsinghua-Foshan Innovation Special Fund(TFISF)under Grant No.2020THFS0113Y.L.acknowledges the support of Hunan Provincial Natural Science Foundation of China(No.2021JJ10006).
文摘Antiferroelectrics(AFEs)possess great potential for high performance dielectric capacitors,due to their distinct double hysteresis loop with high maximum polarization and low remnant polarization.However,the well-known NaNbO_(3) lead-free antiferroelectric(AFE)ceramic usually exhibits square-like P–E loop related to the irreversible AFE P phase to ferroelectric(FE)Q phase transition,yielding low recoverable energy storage density(Wrec).Herein,significantly improved Wrec up to 3.3 J/cm^(3) with good energy storage efficiency(η)of 42.4% was achieved in Na_(0.7)Ag_(0.3)Nb_(0.7)Ta_(0.3)O_(3)(30Agsingle bond30Ta)ceramic with well-defined double P–E loop,by tailoring the A-site electronegativity with Ag+and B-site polarizability with Ta^(5+).The Transmission Electron Microscope,Piezoresponse Force Microscope and in-situ Raman spectra results verified a good reversibility between AFE P phase and high-field-induced FE Q phase.The improved stability of AFE P phase,being responsible for the double P–E loop and improved Wrec,was attributed to the decreased octahedral tilting angles and cation displacements.This mechanism was revealed by synchrotron X-ray diffraction and Scanning Transmission Electron microscope.This work provides a good paradigm for achieving double P–E loop and high energy storage density in NaNbO_(3)-based ceramics.
基金National Natural Science Foundation of China(62203118)。
文摘Piezo actuators are widely used in ultra-precision fields because of their high response and nano-scale step length.However,their hysteresis characteristics seriously affect the accuracy and stability of piezo actuators.Existing methods for fitting hysteresis loops include operator class,differential equation class,and machine learning class.The modeling cost of operator class and differential equation class methods is high,the model complexity is high,and the process of machine learning,such as neural network calculation,is opaque.The physical model framework cannot be directly extracted.Therefore,the sparse identification of nonlinear dynamics(SINDy)algorithm is proposed to fit hysteresis loops.Furthermore,the SINDy algorithm is improved.While the SINDy algorithm builds an orthogonal candidate database for modeling,the sparse regression model is simplified,and the Relay operator is introduced for piecewise fitting to solve the distortion problem of the SINDy algorithm fitting singularities.The Relay-SINDy algorithm proposed in this paper is applied to fitting hysteresis loops.Good performance is obtained with the experimental results of open and closed loops.Compared with the existing methods,the modeling cost and model complexity are reduced,and the modeling accuracy of the hysteresis loop is improved.
基金Supported by the Research Starting Funds for Imported Talents of Ningxia University under Grant No BQD2012011
文摘Three-dimensional simulations of ferroelectric hysteresis and butterfly loops are carried out based on solving the time dependent Ginzburg-Landau equations using a finite volume method. The influence of externally mechanical loadings with a tensile strain and a compressive strain on the hysteresis and butterfly loops is studied numerically. Different from the traditional finite element and finite difference methods, the finite volume method is applicable to simulate the ferroelectric phase transitions and properties of ferroelectric materials even for more realistic and physical problems.
基金supported by the High Technology Research and Development Program of Jilin(20130204021GX)the Specialized Research Fund for Graduate Course Identification System Program(Jilin University)of China(450060523183)+2 种基金the National Natural Science Foundation of China(61520106008,U1564207,61503149)the Education Department of Jilin Province of China(2016430)the Graduate Innovation Fund of Jilin University(2016030)
基金funded by the Project of Liaoning Education Department (No.LJKMZ20220500)the Natural Sciences Foundation of Liaoning province (Grant No.20230157)+1 种基金the National Natural Science Foundation of China (No.21976124)the Liaoning Revitalization Talents Program (No.XLYC2007195)。
文摘Using the Monte Carlo method,the compensation temperature and hysteresis loops of a ferrimagnetic mixed spin-3/2 and spin-5/2 Ising-type graphene-like bilayer are investigated induced by different physical parameters such as crystal field,exchange coupling,external magnetic field,and temperature.The variations of magnetization,magnetic susceptibility,specific heat,and internal energy with the change of temperature are discussed.In addition,we also plot the phase diagrams including transition temperature and compensation temperature.Finally,multiple hysteresis loops under certain parameters are given.
文摘Based on the low-cycle fatigue tests of carbon and alloy steels,the cyclic properties of hysteresis energy and its changing rules have been analysed.The mathematical formula of cyclic hysteresis energy of the materials with different cyclic properties have been presented. The total absorbed energy to failure is associated with the variation of cyclic hysteresis energy.
基金Supported by the National Natural Science Foundation of China under Grant No 10774173.
文摘We exploit the recoil loop measurements to study La0.07 Sr0.33 Mn O3/La0.33 Ca0.67 Mn O3 bilayer film. the asymmetric magnetization reversal in an exchange-biased It is found that the recoil curve encloses a marked area only in the second quadrant of the hysteresis loop, and the recoil susceptibility in the descending branch of the major loop is evidently higher than that in the ascending branch. The study indicates that the exchange anisotropy of a unidirectional nature and an orientation deviated from the easy axis of the ferromagnetic layer plays a crucial role in creating the reversal asymmetry.
文摘Zero-temperature Monte Carlo simulations are used to investigate the hysteresis of a magnetic particle ina dipolarIsing model. The magnetic particle is described in a system of permanent dipoles, and the dipoles are locatedin a cubic lattice site. The effects of the shape and the size of the particle on the hysteresis loop at zero temperatureare obtained. For strong exchange interactions, the shapes of magnetic hysteresis loops approach rectangle. For weakexchange interactions, the effects of the size and the shape of the particle on the loops are more remarkable than thoseof strong exchange interactions case. The slope of the hysteresis loop decreases with the increase of the ratio of thesemi major axis to the semi minor axis of the ellipsoidal magnetic particle, and there is an increase of the slope of thehysteresis with the decrease of the size of the magnetic particle. The effects of the shape and size of the particle on thecoercive force at zero temperature are also investigated.
基金the Research Program of Shenyang Institute of Science and Technology(Grant No.ZD-2024-05).
文摘We described ferromagnetic film and bilayer films composed of two ferromagnetic layers coupled through antiferromagnetic interfacial interaction by classical Heisenberg model and simulated their magnetization state,magnetic permeability,and Faraday effect at zero and finite temperature by using the Landau–Lifshitz–Gilbert(LLG)equation.The results indicate that in a microwave field with positive circular polarization,the ferromagnetic film has one resonance peak while the bilayer film has two resonance peaks.However,the resonance peak disappears in ferromagnetic film,and only one resonance peak emerges in bilayer film in the negative circularly polarized microwave field.When the microwave field’s frequency exceeds the film’s resonance frequency,the Faraday rotation angle of the ferromagnetic film is the greatest,and it decreases when the thickness of the two halves of the bilayer is reduced.When the microwave field’s frequency remains constant,the Faraday rotation angle fluctuates with temperature in the same manner as spontaneous magnetization does.When a DC magnetic field is applied in the direction of the anisotropic axis of the film,the Faraday rotation angle varies with the DC magnetic field and shows a similar shape of the hysteresis loop.
基金financially supported by the Russian Science Foundation Grant No.24-22-00063,https:/rscf.ru/project/24-22-00063/at the Southern Federal University.
文摘This paper studies the relaxation processes and electromechanical hysteresis in relaxor piezoceramics based on the PzT system.Measurements and analysis of the electric displacement and mechanical strain hysteresis loops recorded in bipolar AC electric fields in the frequency range 0.001-5 Hz were performed by means of the electromechanical response characterization system(STEPHV)and program(STEP).It was found that the coercive field,remnant and saturation electric displacement,area of hysteresis loops and relative mechanical strain values are strongly dependent on frequency.As a result of this study,complete sets of parameters characterizing the switching and ferroelectric hysteresis processes in relaxor piezoceramics were obtained.
