Effect Of Tensile Strain Research Articles

Strain-tunable electronic and optical absorption in the MXenes nanolayers: A DFT approach

Computational simulations using density functional theory (DFT) were performed to show that biaxial strain engineering within the range of −8% to +8% is an effective method for modifying the fundamental properties of two-dimensional (2D) transition metal carbides (MXenes). In this work, we computationally explored the effect of both compressive (0 to −8%) and tensile (0 to +8%) strain on the structural, electronic, and optical properties of M2CO2 MXenes (M = Ti, Zr, Sc and Hf) nanolayers. When compressive strains are applied, the charge transfer between layers increases because of decreased interlayer coupling. Conversely, tensile strains result in the opposite behavior. The strain-tunable band gap effect in Mo2CO2 nanolayers is revealed by investigating the valence band maximum (VBM) and conduction band minimum (CBM) in the band structure under biaxial strain. It is observed that the indirect-to-direct band gap transition occurs when the tensile strain is applied to Sc2CO2 and Ti2CO2 nanolayers. In most samples, the energy gap increases with an increase in tensile strain and decreases with an increase in compressive strain. The optical absorption coefficient indicates considerable absorption in the visible to ultraviolet (UV) region. Additionally, the absorption can be influenced by biaxial strains. In particular, under compressive strains (−8%) and Z-polarized light, the UV absorption peak in Hf2CO2, Ti2CO2, and Zr2CO2 reaches 68 %, 78 %, and 113 % respectively. The results indicate that these M2CO2 MXenes nanolayers will have significant potential for applications in tunable optoelectronic devices.

Modulation of magnetic properties of trilayer MoS2/ZnO/VS2 van der Waals heterostructure via strain engineering for spintronics application

MoS2/ZnO/VS2 trilayer van der Waals (vdW) heterostructure is reported for its electronic and magnetic properties for the first time. Heyd-Scuseria-Ernzerhof (HSE) hybrid functional is used to compute the electronic band structure and it is observed that the heterojunction exhibits an indirect transition. The trilayer showed type II band alignment. This along with the Charge Density Difference (CDD) isosurface and plot showed the charge transfer in both the spin channels from ZnO to both MoS2 and VS2 monolayer. Monte Carlo (MC) simulation revealed a low Curie temperature (TC) value of 65 K. Effect of compressive and tensile biaxial strain on the trilayer was studied where all the strained system turned metallic. Under both biaxial tensile and compressive strain, the TC at first increased and then gradually decreased which hints at tuning the TC with strain engineering. Thus, the metallic strained MoS2/ZnO/VS2 trilayer has potential application in the spintronics devices.

Effect of tensile and compressive strain on the gate leakage current and inverse piezoelectric effect in AlGaN/GaN HEMT devices

The influence of external strain on the gate leakage current of AlGaN/GaN high-electron-mobility transistors was studied. The magnitude of the leakage current increased by 39% under 0.1% tensile strain but decreased by 23% under −0.1% compressive strain. The leakage current obeyed the Poole–Frenkel conduction mechanism, demonstrating a decrease/increase in the barrier height for electron emission from the trap state into the continuum dislocation state. Furthermore, the magnitude of critical reverse stressing voltage for the onset of degradation induced by the inverse piezoelectric effect became lower/higher under tensile/compressive strain compared with that of the initial state, which was attributed to the modification of the total stress in the film. In addition, using the transient current method, it was established that the detrapping time constant for the traps in the AlGaN barrier increased as a result of the tensile strain, which is ascribed to movement of the dislocation level away from the conduction band.

Tensile Strain and Interatomic Orbital Hybridization Effects Boost the Electrocatalytic Performance of Intermetallic Pd3Pb Nanowires for Ethanol Electrooxidation†

Comprehensive SummaryWe present a strategy that effectively modulate the d‐band electronic structure of the active center by strain effect and interatomic orbital hybridization. This strategy efficiently promotes the kinetic process of the ethanol oxidation reaction (EOR) in alkaline media. In the intermetallic Pd3Pb nanowires, the introduction of Pb not only causes the lattice expansion of Pd but also achieves the interatomic orbital hybridization bonding with Pd. Such interatomic orbital hybridization effect and tensile strain effect can effectively achieve a co‐regulation of the d‐band electronic structure of Pd, which directly affects the adsorption behavior of intermediate on Pd for EOR. Hence, the intermetallic Pd3Pb nanowires demonstrate enhanced EOR activity and anti‐poisoning ability against COads. Theoretical calculations show that the enhanced OH* adsorption ability and the low energy barrier for the oxidative dehydrogenation of ethanol are the keys to high EOR activity and stability of the intermetallic Pd3Pb nanowires.

Modeling thermal-induced wellhead growth through the lifecycle of a well

During production from high-yield wells, hot reservoir fluids may significantly heat the casing string which may lead to the wellhead growing out of the surface once the induced thermal stress exceeds the wellhead load. This issue involves some challenges that lie in the initial gravity-driven elongation of casing strings before cementing and then their combined expansion with annular cement as one assembly due to later temperature changes. Here, we proposed an integrated modeling method for wellhead growth by incorporating heat transfer and thermodynamics. Element-death technique is used to simulate free elongation of the casings in the absence of cement before cementing and their subsequent coupling thermomechanical behavior with cement after cementing job. Arbitrary Lagrange-Eulerian (ALE) adaptive meshing is employed to avoid mesh distortion due to uncoordinated deformation between casings and cements. Numerical results indicate that the combined effect of gravitational-induced tensile strain and thermal-induced compressive strain may potentially result in a strain-neutral point within the casing. Beyond this point, the casing experiences a tensile state, whereas, below it, the casing is subjected to a compressive state. Furthermore, casing running friction can mitigate tensile strain, while higher production can enhance the thermal strain in the casing. Both factors contribute to shifting the strain neutral point upwards and exacerbating the risk of wellhead growth. However, the application of pre-tensioned casing while cementing can effectively mitigate wellhead growth by offsetting the thermal-induced compressive strain through the increasing tensile strain.

Strain engineering of electronic structure and thermoelectric properties of quasi-hexagonal fullerene monolayer

As a newly synthesized two-dimensional (2D) carbon material, monolayer quasi-hexagonal phase fullerene (qHP C60) has an excellent electronic structure and low thermal conductivity. qHP C60 attracted significant attention from scientists because it has potential applications in thermoelectric materials. Thermoelectric properties of 2D materials significantly depend on the transport of carriers (such as electrons and phonons), and strain engineering is an essential method for modulating the transport of electrons and phonons in 2D materials. However, the strain engineering method for the modulation of the thermoelectric properties of monolayer qHP C60 has not been reported yet. In the present paper, the first-principles combined with the non-equilibrium Green's function method are used to investigate the ballistic transport properties of electrons and phonons in monolayer qHP C60. The effects of temperature, chemical potential, and biaxial tensile strain on the thermoelectric transport parameters (including conductivity, Seebeck coefficient, power factor, and thermal conductivity) as well as the figure of merit (ZT) of monolayer qHP C60 are presented, compared, discussed, and analyzed. We found that monolayer qHP C60 exhibits anisotropic characteristics in electron and phonon transport properties, showcasing outstanding thermoelectric properties. The distinctive quasi-hexagonal phase fullerene network structure offers a novel platform for exploring innovative 2D thermoelectric materials in research. This study provides crucial theoretical insights to guide the designing and implementation of 2D thermoelectric materials based on fullerenes.

The impacts of spin–orbit coupling and strain on transverse dynamical spin susceptibility in undoped phosphorene: Kane–Mele model study

We present the behaviors of dynamical transverse spin susceptibilities of undoped phosphorene monolayer using the Green’s function approach in the context of Kane–Mele model Hamiltonian. Such dynamical spin susceptibility is proportional to inelastic cross section of neutron beam from the layer. Specially, the effects of magnetic field and spin–orbit coupling strength on the spin excitation modes of phosphorene monolayer are investigated via calculating correlation function of spin density operators. Our results show the increase of magnetic field leads to move the magnetic excitation energy to higher values. Also, the intensity of peaks in inelastic cross section reduces with increase of magnetic field. We also show that applying both uniaxial and biaxial strains causes to decrease the intensity of peaks in dynamical spin susceptibility. Finally the effects of both compressive and tensile strains on frequency dependence of dynamical spin structure factor of phosphorene layer are studied. Moreover, the frequency positions of spin excitation mode of phosphorene layer have been investigated due to the effects of spin orbit coupling strength in details.

Electronic Transport Modulation in Ultrastrained Silicon Nanowire Devices.

In this work, we explore the effect of ultrahigh tensile strain on electrical transport properties of silicon. By integrating vapor-liquid-solid-grown nanowires into a micromechanical straining device, we demonstrate uniaxial tensile strain levels up to 9.5%. Thereby the triply degenerated phonon dispersion relation at the Γ-point of silicon disentangle and the longitudinal phonon modes are used to precisely determine the extent of mechanical strain. Simultaneous electrical transport measurements showed a significant enhancement in the electrical conductance. Aside from considerable reduction of the Si bulk resistivity due to strain-induced band gap narrowing, comparison with quasi-particle GW calculations further reveals that the effective Schottky barrier height at the electrical contacts undergoes a substantial reduction. For these reasons, nanowire devices with ultrastrained channels may be promising candidates for future applications of high-performance silicon-based devices.

Comprehensive correlation analysis of electromechanical behavior in high-stretchable carbon nanotube/polymer composites

In this study, a comprehensive correlation analysis of highly stretchable carbon nanotube (CNT)/polymer composites was conducted to predict the change in electrical conductivities in response to uniaxial deformation. To this end, the representative volume elements (RVEs) were generated by randomly distributing CNTs in a polymer matrix using a Monte Carlo simulation algorithm. The effective electrical conductivity was then calculated through a network model. Under uniaxial tensile strain, where the length of CNTs was maintained constant and their configuration kept straight, CNT translation and rotation were considered along with the effects of tensile strain and shrinkage, incorporating Poisson’s ratio. The RVE configuration was updated to account for changes in the network under these conditions. To achieve a strong correlation between the simulation and test results from the previously published works, numerous trade-off studies have been conducted on the RVE size, geometric periodicity, the length of CNT fibers, the mixing ratio of CNT fibers of CNT/polymer composites, and tensile strain. From the results it can be seen that excellent correlations can be only achieved with careful control of the aforementioned parameters.

Study on corrosion behavior of 40Cr steel in 3.5 % NaCl solution under the synergistic effect of UV illumination and strain

The corrosion behavior of 40Cr steel under the synergistic effect of plastic tensile strain and UV was investigated. The results show that the corrosion current density increases under the synergistic effect of strain and illumination. Before the formation of the complete rust layer, it is mainly attributed to the variation of the electric double layer, and the strain can enhance the effect of illumination on the electric double layer. After the formation of the complete rust layer, the increase in corrosion current density was mainly related to the change in the inner rust layer composition. Data availabilityThe data that has been used is confidential.

Effect of biaxial tensile strain on the thermoelectric properties of monolayer ZrTiCO2

Using ab-initio calculation principle calculations, we investigate the effect of biaxial tensile strain on the stability and electronic properties of the two-dimensional double transition metal MXenes ZrTiCO2. The monolayer ZrTiCO2 has stability and semiconducting properties under different strain conditions. The results of thermoelectric properties under other strain conditions calculated by Boltzmann transport theory and Slack model show that biaxial tensile strain can improve the electrical transport properties of monolayer ZrTiCO2 materials and lead to the decrease of lattice thermal conductivity. The thermoelectric efficiency of a material can be evaluated using the figure of merit ZT. The n-type ZrTiCO2 has a maximum ZT value of 1.49 at 900 K without adding biaxial strain and reaches a ZT value of 2.86 with 2% biaxial strain. The monolayer ZrTiCO2 material has the potential to become a thermoelectric material, and its thermoelectric properties can be improved by biaxial tensile strain.

A holistic approach of strain-induced and spin-orbit coupling governed structural, optical, electrical and phonon properties of Janus MoSSe heterostructure via DFT theory

Spintronics and optoelectronic equipment benefit from efficient modification of electrical and optical characteristics for Van der Waals heterostructures. Janus MoSSe, in two dimensions, has superior electronic, optical, and phonon properties. Based on these characteristics, we evaluate the effects of biaxial compressive and tensile strain ranges of −6% to +6% on the structural, optical, spin–orbit coupling, and phonon properties of two-dimensional MoSSe employing first-principles-based density functional theory calculations. At K-point, MoSSe possesses a direct band gap of 1.665 eV, making it a semiconductor. Yet, applying tensile strain, we can observe that the bandgap of MoSSe has declined. On the other hand, the bandgap of MoSSe rises due to the compressive strain. From the phonon properties, it is clear that the stability of the monolayer MoSSe is observed in the case of tensile strain. With the increase of compressive strain, it loses its stability. With a photon energy of 2.5 eV, MoSSe exhibits three times greater optical absorption than other photon energy levels. In comparison to two monolayers (MoS2, MoSe2), the MoSSe heterostructure shows an elevated optical absorption coefficient in the visible light band, according to our calculations of its dielectric constant and optical absorptionThe MoSSe dielectric constant’s peaks shift to the stronger photon energy as compressive strain is increased; in contrast, if tensile strain is added, the highest points shift to the less powerful photon energy. This suggests that the spin–orbit coupling (SOC) in MoSSe heterostructures can be enhanced under strain, which has implications for spintronics. The effect of strain can be used to tailor the phonon behaviors of MoSSe, which can be useful for controlling the material’s mechanical and thermal characteristics. The versatility of the electronic and optical properties of the material under strain can be harnessed to design novel devices such as strain sensors, optoelectronic modulators, and detectors.

Study on fatigue performance of asphalt mixture in service life based on accelerated loading test

To further study the fatigue damage evolution law of asphalt mixture in service period, the accelerated pavement testing (APT) of graded gravel base asphalt pavement and in-situ pavement was conducted. The full-scale test road of graded gravel base asphalt pavement was built, and the mechanical response sensors and temperature sensors were embedded. The fatigue damage test of the full-scale test road was conducted at 15°C through the accelerated loading test (ALT) equipment. The mechanical responses under the repeated wheel loadings were captured by the strain sensor at the bottom of the asphalt layer, and the deflections of the pavement under different cycles of wheel load were tested by Falling Weight Deflectometer (FWD). The fatigue damage model of asphalt mixture was established, and the accuracy of the model was verified by the accelerated loading fatigue test of in-situ pavement. The results show that asphalt layer bears an alternating effect of tensile and compressive strain, and when the wheel load is reduced or the driving speed increases, the tensile strain at the bottom of the asphalt layer decreases. As an evaluation index of fatigue damage of asphalt layer, the residual modulus ratio can accurately characterize the cumulative degree of fatigue damage. The modulus of asphalt layer shows an inverse S-type curve with the repeated wheel loadings. Based on the quantitative analysis of the whole process of fatigue damage of asphalt layer, a nonlinear damage evolution model of modulus attenuation of asphalt mixture was established, which would provide a reference for the study of pavement service performance attenuation law in different climatic environments and structural compositions in the future.

Effect of strain on the electronic structure and optical spectra of two-dimensional monolayer GaN

The effect of compressive strain and tensile strain on the band structure and optical spectra of two-dimensional monolayer GaN has been investigated. Computations were performed within density functional-theory. The results show that tensile two-dimensional monolayer-GaN undergoes an indirect-to-direct transition, which makes the material suitable for light-emitting and laser diodes. The material of interest is found to exhibit different optical properties dependent on the strain. Besides, the absorption band becomes wider and the optical absorption coefficient is reduced negligibly by strain, making two-dimensional-GaN a good candidate for application in photovoltaics and flexible optoelectronics.

Effect of tensile and compressive strains on the electronic structure of O-atom-doped monolayer MoS2

We investigate the effects of biaxial tensile and compressive strains on the electronic structure of O-doped monolayer MoS2 by density functional theory (DFT) in this paper. O-doped monolayer MoS2 is an exothermic reaction. The doping of O leads to the transformation of the system from direct bandgap to indirect, and the bonding of Mo and O causes a large amount of charge transfer. The application of tensile strain leads to a decrease in the stability of the doped system, and the system always maintains the nature of indirect bandgap. The degree of interatomic charge transfer and bandgap value gradually decrease with the increase of tensile strain. The application of compression strain improves the stability of the doped system, and as the compressive strain increases, the bandgap of the doped system completes the indirect–direct–indirect transformation. The bandgap value shows a trend of increasing and then decreasing. Additionally, the degree of charge transfer between atoms is strengthened.

Effect of Strain on Electron Transport and Quantum Lifetimes in InxGa1−xAs/In0.52Al0.48As Modulation Doped Double Quantum Well‐Based High Electron Mobility Transistor Structures

The effect of tensile and compressive strain on low‐temperature electron transport (τt) and quantum (τq) lifetimes are analyzed as function of well width (w) in InxGa1−xAs/In0.52Al0.48As modulation‐doped double quantum well (MD‐DQW)‐based high electron mobility transistors structures. The DQW system can be made either lattice‐matched or strained, tensile and compressive, by considering x = 0.53, 0.41, and 0.75, respectively. Results show that the nonlinearity in τt and τq relates to the uneven dependence on the ionized impurity (ii), interface roughness (ir), and alloy disorder (al) scatterings. As w increases, τt enhances. The improvement in τt is substantial for the strained system compared to the unstrained. Further, for w < 94 Å, the ir‐scattering is more dominating under the compressive than the tensile strained structure, leading to τt (x = 0.41) > τt (x = 0.75). Conversely, τq is dominated by ii‐scattering exhibiting τq (x = 0.75) > τq (x = 0.53) > τq (x = 0.41). A hybrid structure is also proposed with one well tensile (x = 0.41) and the other as compressively (x = 0.75) strained, resulting in a step‐like MD‐DQW structure. As a result, only a single sub‐band is occupied leading to a twofold improvement in τt for w = 150 Å compared to the symmetric structures.

Effect of tensile strain on the electronic structure, optical absorptivity, and power conversion efficiency of the BC6N/ZnO van der Waals heterostructure

van der Waals heterostructures (vdWHs) have attracted significant interest as unique structures for application in nanoelectronic devices. A novel BC6N/ZnO vdWH was prepared by superimposing BC6N semiconductor wafers onto a hexagonal ZnO monolayer. The electronic structure, optical absorptivity, and power conversion efficiency (PCE) of BC6N/ZnO vdWH under tensile strain were studied using first-principles calculations. The band structure of the BC6N/ZnO vdWH exhibited a type-I band alignment with a direct bandgap of 1.92 eV. The type-I direct bandgap transformed into a type-II indirect bandgap when the uniaxial and biaxial tensile strains were increased to 10 %. Although the bandgap of the BC6N/ZnO vdWH increased (from 1.92 to 2.20 eV) monotonically with uniaxial strain (0–10 %), it was nearly independent of biaxial strain. The BC6N/ZnO vdWH exhibited a wide range and strong optical absorption in the ultraviolet (UV)–visible range; the absorptivity curve was red-shifted, and the optical absorptivity significantly increased in the UV region with increasing tensile strain. The PCE of BC6N/ZnO vdWH reached 22.5 % and 15.3 % under 10 % biaxial and uniaxial strains, respectively. The tunable electronic structure, excellent optical absorptivity, and ultrahigh PCE of BC6N/ZnO vdWH can be used in designing two-dimensional high-efficiency photovoltaic devices.

A comprehensive investigation of the Sr3AsX3 (X = F/Cl/Br) inorganic cubic perovskites' strain-induced structural, electronic, optical, and mechanical properties with solar cell applications.

In comparison to the lead halide perovskites, nowadays, lead-free halide perovskites have demonstrated a number of benefits, including efficient optical absorption, increased stability, variable bandgap, excellent mobility of carriers, non-toxicity, abundant raw ingredients, and low manufacturing cost. The use of the Perdew-Burke-Ernzerhof (PBE) and Heyd-Scuseria-Ernzerhof (HSE) hybrid functional inside the quantum espresso software allowed for a thorough examination of these materials, potentially leading to improvements in the development of ecologically acceptable and economically sustainable perovskite-based products. This work has extensively examined the effects of compressive and tensile strain on the structural, optical, and electronic characteristics of the inorganic cubic perovskite Sr3AsX3 (X = F, Cl, Br) with varying X anion using first-principles density-functional theory (FP-DFT). At the Γ point, the unstrained Sr3AsF3, Sr3AsCl3, and Sr3AsBr3 compounds have a direct bandgap of 1.68/2.50 eV, 1.65/2.47 eV, and 1.522/2.30 eV, respectively, from the PBE/HSE methods. A drop in bandgap values occurs when the X-anion switches from F to Cl to Br. Furthermore, the bandgaps of the three proposed structures show a minor increase in response to tensile strain and a decreasing prevalence in response to compressive strain. The optical properties, which include dielectric functions, absorption coefficient, and electron loss function, are consistent with the band characteristics of these components, all of which point to a significant capability for absorption in the visible region. The dielectric constants of Sr3AsF3, Sr3AsCl3, and Sr3AsBr3 are discovered to have peaks that, with compressive strain, redshift (move towards lower photon energy) and, under tensile strain, blueshift (move towards upper photon energy). In comparison to the compounds Sr3AsF3 and Sr3AsCl3, the parameters indicate that the material Sr3AsBr3 is more optically advantageous. The SCAPS-1D simulator was used to methodically examine the photovoltaic (PV) performance of novel cell topologies that included SnS2 as an electron transport layer (ETL) and Sr3AsF3, Sr3AsCl3, and Sr3AsBr3 as absorbers and primarily 19.76, 19.89, and 20.89% PCE was achieved, respectively.

Effects of isotropic strain on the structure and transport properties of half-Heusler alloy BiBaK: a first-principles investigation.

In this study, using density functional and Boltzmann transport theories, we systematically investigated the effects of tensile and compressive strains on the elastic properties, phonon dispersion relation, electronic structure, and transport properties of the half-Heusler compound BiBaK. We calculated the elastic constants and phonon dispersion curves for BiBaK, which demonstrated its mechanical and thermodynamic stability, respectively, under different isotropic strains. Further, calculations showed that the electronic structure and energy bandgap of BiBaK changed with the application of isotropic strain. A high power factor and low thermal conductivity are key to improving the performance of thermoelectric materials. The figure of merit of BiBaK is 0.6 when it is unstrained and reaches a maximum value of 0.93 at -9% compressive strain and a temperature of 1200 K, indicating that under isotropic compressive strain, BiBaK compounds are efficient thermoelectric materials for high-temperature applications.

Strain effects on Auger–Meitner recombination in silicon

We study the effects of compressive and tensile biaxial strain on direct and phonon-assisted Auger–Meitner recombination (AMR) in silicon using first-principles calculations. We find that the application of strain has a non-trivial effect on the AMR rate. For most AMR processes, the application of strain increases the AMR rate. However, the recombination rate for the AMR process involving two holes and one electron is suppressed by 38% under tensile strain. We further analyze the specific phonon contributions that mediate the phonon-assisted AMR mechanism, demonstrating the increased anisotropy under strain. Our results indicate that the application of tensile strain increases the lifetime of minority electron carriers in p-type silicon and can be leveraged to improve the efficiency of silicon devices.