Effect Of Uniaxial Stress Research Articles

The effect of uniaxial mechanical stress on electronic and dynamic properties of silicon

The effect of uniaxial mechanical stress on electronic and dynamic properties of silicon

A dual‐porosity model incorporating uniaxial stress effect and its application in wave velocity estimation with well‐logging data

A dual‐porosity model incorporating uniaxial stress effect and its application in wave velocity estimation with well‐logging data

Uniaxial stress effect on the electronic structure of quantum materials

Uniaxial stress has proven to be a powerful experimental tuning parameter for effectively controlling lattice, charge, orbital, and spin degrees of freedom in quantum materials. In addition, its ability to manipulate the symmetry of materials has garnered significant attention. Recent technical progress to combine uniaxial stress cells with quantum oscillation and angle-resolved photoemission techniques allowed to study the electronic structure as function of uniaxial stress. This review provides an overview on experimental advancements in methods and examines studies on diverse quantum materials, encompassing the semimetal WTe2, the unconventional superconductor Sr2RuO4, Fe-based superconductors, and topological materials.

A theoretical study of the effects of uniaxial stress and spatial dielectric functions on the density of states of shallow donor impurities in a GaAs quantum well dot of circular geometry

In the present work, we have carried out a comparative study of the effects of uniaxial stress and spatial dielectric functions on the density of impurity states (DOIS) of shallow donor impurities in a GaAs quantum well dot of circular cross-section. Using a trial wave function in the effective mass approximation, we carried out calculations for a range of binding energies of hydrogenic (dielectric constant) and non-hydrogenic (spatial dielectric functions) donors for various applied uniaxial stress and for different uniaxial lengths of the quantum dot. Our results show that, for a constant axial length of the quantum dot and constant uniaxial stress, the DOIS for the donor impurity is markedly enhanced for the non-hydrogenic donor impurity over that for purely hydrogenic donor impurity. At constant axial length, the applied uniaxial stress enhances the DOIS in both cases. The density of impurity states has also been studied for a constant applied uniaxial stress for different axial lengths of the quantum dot. Here, again, the DOIS increases with increasing axial length of the quantum dot. In fact, the enhanced DOIS is observed throughout the range of binding energies considered. These results show that not only does the DOIS vary with the applied uniaxial stress and spatial dielectric functions they are also different for various axial lengths of the quantum dot. These findings indicate that is important to take into account the effect of applied uniaxial stress and spatial dielectric functions when performing experimental studies of electronic, optical and transport properties of such nanostructures as quantum dots.

Effect of uniaxial stress on magnetic property of laminated amorphous sheets up to kilohertz range

Amorphous alloys are widely used as the core material for motors and transformers, which are subjected to stresses during manufacturing and operation processes. For instance, the compressive stress can influence the magnetic properties of amorphous alloys which leads to local overheating in the device and reduce the reliability. A high-frequency magnetizer with a stress application unit is designed and constructed to investigate the magnetic properties of amorphous alloys up to kilohertz range under stress conditions. The amorphous alloy sheets will fracture under stress because of their poor ductility and brittleness, so this paper uses laminated amorphous alloy sheets as the sample. The hysteresis loops and loss characteristics of amorphous alloys under stress ranging from 20 MPa tensile stress to 20 MPa compressive stress at a frequency of 50 Hz to 4 kHz are investigated. This research can provide data support for the design of cores in electromagnetic devices.

Microscopic investigation of the effect of uniaxial stress on the structure of pore-fissure system and methane adsorption in lean coal

In order to study the mechanism of interaction between stress, pore-fissure system, and methane adsorption. Adopting a novel combination of experimental and simulation methods. Through uniaxial fracture experiments and X-ray micro-CT scanning experiments, it was found that the pore-fissure system of coal blocks first closed and then sharply increased with the increase of uniaxial stress. Based on relevant experiments, unit cell models under different uniaxial stresses were constructed. Through simulation calculations using Zeo++-0.3 code and Materials Studio, it was found that the pore system of unit cells first decreases and then increases with the increase of uniaxial stress, and the maximum adsorption capacity of methane first decreases and then increases. The experimental and simulation results for the evolution characteristics of the coal pore system under different uniaxial stresses were consistent. Stress affects methane adsorption in coal by altering the pore-fissure system characteristics. Stress has a significant impact on the macroscopic and molecular microscopic systems of coal pores. In front of the mining and excavation working face, the gas pressure and content increase, the coal body is damaged, and the coal body stress increases. This also explains that this area is prone to coal and gas outburst.

First-principles calculations to investigate effect of uniaxial stress on optical and magnetic properties of Sr2XWO6 (X = Fe, Co & Ni)

The high symmetry cubic phase of double perovskites is an ideal crystal phase at higher temperatures, and exhibit various fascinating properties such as multiferroicity, half-metallicity and half-semiconductivity. Here, the first principles DFT method was used to study the effect of applying uniaxial stress on the structural, magnetic and opto-electronic properties of Sr2XWO6 (X = Fe, Co, Ni) layered perovskite in cubic phase. Our calculation predicted a negative value of the dielectric function for Sr2CoWO6 compound. Also, the addition of external pressure increases the reflectivity and the refractive index in the visible region for all the double perovskites under consideration. We also find that the Sr2FeWO6 and Sr2CoWO6 structures exhibit ferromagnetic half metallicity, with a decreasing half-metallic gap under increasing pressure. Furthermore, half-semiconducting nature is observed in Sr2NiWO6 structure which have potential implementation inoptoelectronics and spintronics.

Effects of uniaxial stress and temperature on the interfacial tensile strength and stability of Al/NiO nanolaminates: A first-principles study

Nanoenergetic multilayer films have been widely prepared due to their unique advantages in realizing “nanoenergetics-on-a-chip”. Recently, the potential for adjusting the performance of nanothermites without altering their film thickness has attracted much attention, prompting researchers to concentrate on film stress. Here, we employed first-principles tensile tests and ab initio molecular dynamics simulations to investigate the tensile properties, fracture mechanisms, and film stability of two Al/NiO interfaces under pre-stress. An analysis of electron localization function and bond overlap population shows that the weakest locations of the (100)-Top and (111)-Top interface systems are distinctly different, leading to two different fracture mechanisms. When the pre-stress and temperature are coupled, the reactivity of Al/NiO as an energetic material is enhanced. Particularly for (111)-Top, the amorphous, mixed region between the two phases replaces the original coherent interface. With the increase of the pre-stress, the crack evolves ahead of the critical strain, indicating that the coupling effects of the pre-stress and temperature have an important influence on the stability and fracture strength. This work not only reveals the mechanical properties of Al/NiO, but also provides a theoretical guidance for optimizing the structure of energetic nanolaminates.

Evolution of magnetic stripes under uniaxial stress in La1.885Ba0.115CuO4 studied by neutron scattering

We present the effect of uniaxial stress on the magnetic stripes in the cuprate system ${\mathrm{La}}_{2\ensuremath{-}x}{\mathrm{Ba}}_{x}{\mathrm{CuO}}_{4}$ with $x=0.115$, previously found to have a stress-induced enhancement in the superconducting transition temperature. By means of neutron scattering, we confirm that the static stripes are suppressed by stress, pointing towards a trade-off between superconductivity and static magnetism, in direct agreement with previously reported muon spin rotation measurements. Additionally, we show that some of the reduced weight in the elastic channel appears to have moved to the inelastic channel, while we can exclude the opening of a spin gap down to an energy of 1 meV. Moreover, a stress-induced momentum shift of the fluctuations towards the typical 1/8 value of commensurability is observed, while no change in periodicity is seen in the static stripe signal. These results impose a strong constraint on the theoretical interpretation of stress-enhanced superconductivity in cuprate systems.

Uniaxial stress-dependent dielectric properties and phase transitions of antiferroelectric AgNbO3

Antiferroelectric AgNbO3 ceramic is investigated with a focus on the effects of uniaxial compressive stress on dielectric response and phase transitions as well as its frequency-dependent ferroelastic behavior. The application of uniaxial compressive stress leads to diffused phase transitions, higher phase transition temperatures, and increased permittivity parallel to the stress application direction for low-temperature phase regions (MI, MIIa). The stress-dependent permittivity response at different phase regions reveals the influence of stress on domain wall motion and phase changes. Additionally, loading rate-dependent stress–strain measurements demonstrate easier ferroelastic domain switching under a lower loading frequency, where the coercive stress increases with frequency initially while getting saturated above 5 mHz. This study reveals the impact of external stress, which can alter the dielectric response and affect domain wall movement at different extents depending on the loading frequency and shift phase boundaries of AgNbO3, implying positive prospects of property engineering of energy storage materials by stress application.

Magnetic Signal Characteristics in Critical Yield State of Steel Box Girder Based on Metal Magnetic Memory Inspection

Metal magnetic memory testing (MMMT) is a nondestructive testing technique that can detect early signs of damage in components. Many scholars have studied the effect of uniaxial stress on the self-magnetic-leakage field (SMLF)’s strength. Nevertheless, there is still insufficient research on the combined action of bending and shear. We studied the law of distribution of the magnetic signal, ΔHSF(y), at different stress parts of a steel box girder and the quantitative relationship between the magnetic characteristic parameters and the external load. The results showed that the MMMT could accurately detect the early stress concentration zone (SCZ) and predict the final buckling zone of steel box girders. It could be judged that the corresponding parts of the steel box girder had entered the elastic-plastic working stage by the reverse change of the ΔHSF(y)-F and |HSF(y)|a -F curve trends, this feature could be used as an early warning sign before the steel box girder was deformed or destroyed. The fitted |HSF(y)|ave -F linear expression could be used as the expression between the magnetic signal and the shear capacity. All the evaluation methods were expected to provide a basis for effectively evaluating the stress state of steel box girders with the MMMT method.

A model of thermal creep and annealing in finite domains based on coupled dislocation climb and vacancy diffusion

We develop a framework to investigate thermal creep and annealing in finite domains, where the climb motion of discrete dislocations is coupled to the diffusion of a continuum vacancy field. The model is first formulated in a continuum finite-deformation setting. All governing equations and boundary conditions are obtained from a unified irreversible thermodynamics principle. The resulting model couples a mechanical boundary value problem (BVP), a vacancy diffusion BVP, and the climb and glide motion of the discrete dislocation network within the crystal. The framework is then linearized for implementation in three-dimensional (3D) discrete dislocation dynamics (DDD) simulations for arbitrary anisotropic crystals. A solution scheme is developed based on the superposition principle, which is imposed weakly on the dislocation network to obtain a Galerkin solution for the nodal climb velocities. The framework includes diffusional (Nabarro–Herring) creep deformation as well as dislocation creep by climb-assisted-glide. The method is applied to simulate the annealing of vacancy loops in Al, with good agreement to experimental measurements by Silcox and Hirsch (1959). We further consider the effects of annealing under stress, and of the proximity of the vacancy loops to loaded and free boundaries Simulations in polycrystalline materials are carried out to highlight the effects of the grain size on dislocation climb and vacancy loop annealing. The method is also applied to estimate the creep rate due to climb-assisted glide of jogged-screw dislocations in γ-TiAl, and results are compared to experiments by Viswanathan et al. (1999). Finally, we discuss the effects of uniaxial and hydrostatic stresses on the two diffusive deformation pathways of the material, namely Nabarro–Herring creep and dislocation climb.

Effect mechanism of nitrogen injection into fire-sealed-zone on residual-coal re-ignition under stress in goaf

Coal is the one of foundations of energy and economic structure in China, while the unsealing of coal mine fires would cause a great risk of coal re-ignition. In order to explore the influence of pressure-bearing state on the re-ignition characteristics for residual coal, the uniaxial compression equipped with a temperature-programmed device was built. The scanning electron microscope, synchronous thermal analyzer and Fourier transform infrared absorption spectrometer was applied to investigate the microscopic structure and thermal effect of the coal samples. Moreover, the microscopic effect of uniaxial stress on coal re-ignition is revealed, and the re-ignition mechanism is also obtained. As the uniaxial stress increasing, the number, depth and length of the fractures of the pre-treated coal increases. The application of uniaxial stress causes the thermal conductivity to change periodically, enhances the inhibition of injecting nitrogen on heat transfer and prolonges the duration of oxidation exothermic. The content of oxygen-containing functional groups has a high correlation with apparent activation energy, and coal samples at 6 MPa is more probability to re-ignite while the fire zone is unsealed. Uniaxial stress could control the re-ignition mechanism by changing the structure of fractures and pores. The side chains and functional groups of coal structure are easier to be broken by thermal-stress coupling. The higher the ·OH content, the more difficult coal samples would be re-ignited. The research results would lay a solid theoretical foundation for the safe unsealing of closed fire-areas underground, tighten the common bond between the actual industry and the experimental theory in closed fire-areas underground, and provide the theoretical guidance for coal re-ignition preventing.

The superconductivity of Sr2RuO4 under c-axis uniaxial stress

Applying in-plane uniaxial pressure to strongly correlated low-dimensional systems has been shown to tune the electronic structure dramatically. For example, the unconventional superconductor Sr2RuO4 can be tuned through a single Van Hove point, resulting in strong enhancement of both Tc and Hc2. Out-of-plane (c axis) uniaxial pressure is expected to tune the quasi-two-dimensional structure even more strongly, by pushing it towards two Van Hove points simultaneously. Here, we achieve a record uniaxial stress of 3.2 GPa along the c axis of Sr2RuO4. Hc2 increases, as expected for increasing density of states, but unexpectedly Tc falls. As a first attempt to explain this result, we present three-dimensional calculations in the weak interaction limit. We find that within the weak-coupling framework there is no single order parameter that can account for the contrasting effects of in-plane versus c-axis uniaxial stress, which makes this new result a strong constraint on theories of the superconductivity of Sr2RuO4.

Anisotropy of exchange and Dzyaloshinskii-Moriya interactions effects on the stabilization of Néel-type skyrmions

In this work, the effect of uniaxial stress on the stability of magnetic skyrmion is studied by use of Monte Carlo simulations. The classical Heisenberg model with anisotropic exchanges and Dzyaloshinskii-Moriya interactions is applied to correlate the stress behavior. We calculate magnetization M and skyrmion number Q to estimate the phase transition points, use the spin configurations and their Fourier transform to determine the region of skyrmion state. The h − T phase diagram show the area of skyrmion state is larger with stress than without stress. These results are interpreted qualitatively by the energy competitions between Zeeman, exchanges and Dzyaloshinskii-Moriya interactions. The simulated results suggest that anisotropy induced by uniaxial stress can stabilize the skyrmion phase.

Effect of uniaxial compressive stress with different orientations on the hole mobility of wurtzite GaN heterojunction quantum well

The influence of uniaxial compressive stress with different orientations to the current channel on the physical and transport properties of the wurtzite GaN heterojunction quantum well is investigated in this work. By using the six-band stress-dependent k × p Hamiltonian, accurate two-dimensional physical pictures are given for the quantized valence subband under the uniaxial compressive stress on the (0001) transport plane. The low-field hole mobility is obtained by the Kubo–Greenwood formula, taking the scattering rates for acoustic phonon, polar optical phonon, and surface roughness into account. Using these methods, the microscopic relationship between the orientation of uniaxial compressive stress and low-field hole mobility is obtained according to the variations of valence subband dispersion and hole effective mass. Results show that for temperatures around and above room temperature, the acoustic phonon scattering is predominant. We find that the mobility gain is mostly contributed from effective mass, and there is an increasing trend under uniaxial compressive stress with all orientations due to the effective mass reduction. For the same stress value, the mobility decreases monotonically as the stress orientation changes from 0° to 90° with respect to the current channel. At room temperature, the calculated low-field hole mobility is 182 cm2/V s under 8 GPa uniaxial compressive stress parallel to the current channel, with the hole density of 5.5 × 1013 cm−2 and the effective electric field of 0.93 MV/cm.

Effect of Uniaxial Compressive Stress on Phase Transformation Kinetics of Low-Carbon Steel.

To attain microstructure transformation and the kinetics of phase transformation under stress during the annealing process, dilatometric curves of phase transformation for Q235 steel were tested using a Gleeble-3500 thermal-mechanical simulator under different uniaxial compressive stresses. The Johnson–Mehl–Avrami (JMA) model considering impingement correction was applied to study the phase-transformation kinetics during annealing. The results showed that the grain size increased with increasing uniaxial compressive stresses because it provided additional energy for grain growth. Furthermore, the interfacial migration velocity decreased with increasing stress owing to grain coarsening and a decrease in the density of the α/γ boundary. Meanwhile, the stress reduces the sum of the misfit accommodation energy and interface energy caused by the transformation, and the driving force required for the transformation of austenite to ferrite decreases. Hence, it was concluded that uniaxial compressive stress plays a complex role in the phase transformation, which inhibits interfacial migration and the transformation rate while providing additional energy for the transformation.

A comprehensive assessment of the galvanic corrosion behavior of an electrically assisted pressure joint of dissimilar stainless steel alloys under uniaxial tensile stress

The effect of uniaxial tensile stress on the galvanic corrosion behavior of a dissimilar joint of stainless steel alloys is investigated in 0.5 M Na2SO4 electrolyte solution at room temperature. The experimental stress-corrosion test results reveal that the application of uniaxial tensile stress causes a decrease in the corrosion potential and an increase in the corrosion rate compared to the nonstressed specimen. A numerical model is established and validated using the results from the experimental stress-corrosion tests. Consequently, a series of case studies is presented to investigate the galvanic corrosion behavior of the joint under some applied tensile strains.

Acoustic emission characteristics and damage law for prefabricated single‐crack sandstone under uniaxial compression

The cracks of rock seriously threaten the safety of building structures and underground space. Uniaxial compression tests were carried out on prefabricated single-crack sandstone samples with different angles and lengths. The results show that the existence of a prefabricated single-crack has a certain influence on the mechanical properties and acoustic emission response characteristics of sandstone samples. A function formula of the effect of uniaxial compression stress on the angle and length of prefabricated crack is established. It is found that there is an obvious moment of acoustic emission energy mutation in the three deformation and failure stages before sandstone failure. The change of angle and length of crack has a great influence on the stress value corresponding to the energy mutation at the stable development stage of the micro-crack. Meanwhile, the acoustic emission waveform characteristic parameters of sandstone samples under various fracture conditions are analyzed. Thus, the crack propagation mode of the sample with small angle can be judged. The damage variables based on real-time acoustic emission energy were defined, and the damage constitutive model of rock material with a single fracture under uniaxial compression was established based on real-time acoustic emission energy. The results show that the new model and method can not only reasonably explain the damage mechanism of prefabricated rock with a single fracture under uniaxial compression but also accurately simulate the full stress-strain process of rock with a single fracture at different angles and lengths, which has good rationality and feasibility.

Uniaxial stress effect on quasi-one-dimensional Kondo lattice CeCo2Ga8

Quantum critical phenomena in the quasi-one-dimensional limit remain an open issue. We report the uniaxial stress effect on the quasi-one-dimensional Kondo lattice CeCo2Ga8 by electric transport and AC heat capacity measurements. CeCo2Ga8 is speculated to sit in close vicinity but on the quantum-disordered side of a quantum critical point. Upon compressing the c axis, parallel to the Ce–Ce chain, the onset of coherent Kondo effect is enhanced. In contrast, the electronic specific heat diverges more rapidly at low temperature when the intra-chain distance is elongated by compressions along a or b axis. These results suggest that a tensile intra-chain strain (εc > 0) pushes CeCo2Ga8 closer to the quantum critical point, while a compressive intra-chain strain (εc > 0) likely causes departure. Our work provides a rare paradigm of manipulation near a quantum critical point in a quasi-1D Kondo lattice by uniaxial stress, and paves the way for further investigations on the unique feature of quantum criticality in the quasi-1D limit.