Effect Of Tensile Strain Research Articles

Strained induced metallic to semiconductor transitions in 2D Ruddlesden Popper perovskites: A GGA + SOC approach

Based on RP perovskites, we put 2%, 4%, 6%, and 8% biaxial strains on 2D monolayers of phenyl-ammonium tin iodide (PH2SnI4) perovskites. Density functional theory (DFT) is used to study the structural distortion, octahedral tilting, band gap tuning, Bader charge analysis, and mechanical stability of the resulting configurations. Band gaps under the effects of compressive strain (Eg1), zero strain (Eg2), and tensile strain (Eg3) follow a decreasing order of Eg1(1.262 eV) < Eg2(1.329 eV) < Eg3(1.331 eV) for 6%-strain. The absence of trap states in energy band gaps and dominant cation and anion contributions at conduction and valence band edges supports the defect tolerance. All the structures analyzed are mechanically stable. The covalently bonded structures are ductile/brittle under tensile/compressive strain, with a prominent stretching mode. Strain improves the optical performance with dielectric constant increased (red-shifted) under compressive strain and reduced (blue-shifted) under compressive strain.

Inhibiting effect of tensile strain on the nucleation of M6C at grain boundary

Inhibiting effect of tensile strain on the nucleation of M6C at grain boundary

Modeling of yarn strength and its influencing factors in the pneumatic splicing process

Yarn splicing strength is one of the most important indexes to evaluate yarn twist quality, and it determines final performance of the yarn. This paper establishes a prediction model of yarn splicing strength. The strength prediction model was used to predict the mechanical properties of yarn composed of different fibers during splicing. The effects of fiber properties, splicing and tensile strain on the splicing strength of yarn were described by using the characteristic parameters of the fiber and yarn. Finally, the interaction between parameters is analyzed by charts, and the optimal solution is obtained. The results show that the yarn splicing strength prediction model established by the mechanical analysis and geometric structure can reflect the mechanical state of the yarn in the pneumatic splicing chamber, and can be used to calculate the yarn splicing strength. Yarns with higher tensile modulus will obtain higher splicing strength under the action of lower twist and higher tensile stress. Therefore, the strength prediction model provides a theoretical basis for the study of the relationship among yarn strength and fiber properties, splicing, tensile strain and other parameters, and also provides guidance for the optimization of the modern spinning process. Furthermore, the influence of air pressure on the splicing strength is also discussed.

Heterointerface and Tensile Strain Effects Synergistically Enhances Overall Water-Splitting in Ru/RuO2 Aerogels.

Designing robust electrocatalysts for water-splitting is essential for sustainable hydrogen generation, yet difficult to accomplish. In this study, a fast and facile two-step technique to synthesize Ru/RuO2 aerogels for catalyzing overall water-splitting under alkaline conditions is reported. Benefiting from the synergistic combination of high porosity, heterointerface, and tensile strain effects, the Ru/RuO2 aerogel exhibits low overpotential for oxygen evolution reaction (189mV) and hydrogen evolution reaction (34mV) at 10mA cm-2 , surpassing RuO2 (338mV) and Pt/C (53mV), respectively. Notably, when the Ru/RuO2 aerogels are applied at the anode and cathode, the resultant water-splitting cell reflected a low potential of 1.47V at 10mAcm-2 , exceeding the commercial Pt/C||RuO2 standard (1.63V). X-ray adsorption spectroscopy and theoretical studies demonstrate that the heterointerface of Ru/RuO2 optimizes charge redistribution, which reduces the energy barriers for hydrogen and oxygen intermediates, thereby enhancing oxygen and hydrogen evolution reaction kinetics.

The effect of tensile strain in Pd-Ni core-shell nanocubes with tuneable shell thickness on urea electrolysis selectivity.

Expanding our understanding of the structure-performance relationship in nanoscale electrocatalysts for urea electrolysis is crucial for efficient urea waste treatment and concomitant cathodic hydrogen production or CO2 reduction. Here, we elucidate the effect of the lattice strain in Pd-Ni core-shell nanocubes on the dominance of urea overoxidation pathway.

From the single-atom limit to the mixed-metal phase: finding the optimum condition for activating the basal plane of a FePSe3 monolayer towards HER.

Layered ternary transition metal tri-chalcogenides are some of the most promising candidates for hydrogen evolution reaction (HER) because of their ease of synthesis and affordability. However, majority of the materials in this category have HER active sites only at their edges, rendering a large portion of the catalyst useless. In this work, ways for activating the basal planes of one of these materials, namely, FePSe3, are explored. The effects of substitutional transition metal doping and external biaxial tensile strain on the HER activity of the basal plane of a FePSe3 monolayer are studied via first principles electronic structure calculations based on density functional theory. This study reveals that although the basal plane of the pristine material is inactive towards HER (value of H adsorption free energy, ΔGH* = 1.41 eV), 25% Zr, Mo, and Tc doping makes it more active (ΔGH* = 0.25, 0.22 and 0.13 eV, respectively). The effect of reducing the doping concentration, moving to the single-atom limit, on the catalytic activity is studied for Sc, Y, Zr, Mo, Tc and Rh dopants. For Tc, the mixed-metal phase FeTcP2Se6 is also studied. Among the unstrained materials, 25% Tc-doped FePSe3 gives the best result. Significant tunability of HER catalytic activity in the 6.25% Sc doped FePSe3 monolayer via strain engineering is also discovered. An external tensile strain of 5% reduces ΔGH* to ∼0 eV from 1.08 eV in the unstrained material, making this an attractive candidate for HER catalysis. The Volmer-Heyrovsky and Volmer-Tafel pathways are examined for some of the systems. A fascinating correlation between the electronic density of states and HER activity is also observed in most materials.

Strain-induced tunable optoelectronic properties of inorganic halide perovskites APbCl3 (A = K, Rb, and Cs)

Halide perovskites are promising photovoltaic, solar cell, and semiconductor materials. Density-functional theory (DFT) models address compressive and tensile biaxial strain effects on APbCl3, where A = (K, Rb, and Cs). This research shows how A-cation impacts bandgap energy and band structure. The direct bandgap for KPbCl3, RbPbCl3, and CsPbCl3 is found 1.612, 1.756, and 2.046 eV, respectively; increases from A = K to Cs. When spin–orbital coupling (SOC) is introduced, bandgaps in KPbCl3, RbPbCl3, and CsPbCl3 perovskites are reduced to 0.356, 0.512, and 0.773 eV, respectively. More tensile strain widens the bandgap; compressive strain narrows it. Without SOC, the bandgaps of KPbCl3, RbPbCl3, and CsPbCl3 were tuned from 0.486 to 2.213 eV, 0.778 to 2.289 eV, and 1.168 to 2.432 eV, respectively. When the compressive strain is increased, the dielectric constant of APbCl3 decreases (redshift) and increases (blueshift) as the tensile strain is increased. Strain improves APbCl3 perovskite’s optical performance.

Tensile strain and finite size modulation of low lattice thermal conductivity in monolayer TMDCs (HfSe2 and ZrS2) from first-principles: a comparative study.

With excellent physical and chemical properties, 2D TMDC materials have been widely used in engineering applications, but they inevitably suffer from the dual effects of strain and device size. As typical 2D TMDCs, HfSe2 and ZrS2 are reported to have excellent thermoelectric properties. Thermal transport properties have great significance for exerting the performance of materials, ensuring device lifetime and stable operation, but current research is not detailed enough. Here, first-principles combined with the phonon Boltzmann transport equation are used to study the phonon transport inside monolayer HfSe2 and ZrS2 under tensile strain and finite size, and explore the band structure properties. Our research shows that they have similar phonon dispersion curve structures, and the band gap of HfSe2 increases monotonically with the increase of tensile strain, while the bandgap of ZrS2 increases and then decreases with the increase of tensile strain. Thermal conductivity has obvious strain dependence: with the increase of tensile strain, the thermal conductivity of HfSe2 gradually decreases, while that of ZrS2 increases slightly, and then gradually decreases. Reducing the system size can limit the contribution of phonons with a long mean free path, significantly decreasing thermal conductivity through the controlling effect of tensile strain. The mode contribution of thermal conductivity is systematically investigated, and anharmonic properties including mode and frequency-level scattering rates, group velocity and Grüneisen parameters are used to explain the associated mechanism. Phonon scattering processes and channels in various cases are discussed in detail. Our research provides a detailed understanding of the phonon transport and electronic structural properties of low thermal conductivity monolayers of HfSe2 and ZrS2, and further completes the study of thermal transport of the two materials under strain and size tuning, which will provide a foundation for further popularization and application.

Beneficial effects of tensile strain on charge carrier lifetime in metal halide perovskites containing halogen vacancies

Direct and trap-assisted recombination of electrons and holes is suppressed by applying tensile strain in lead halide perovskites containing halogen vacancies.

Compressive and tensile strain effects on the ultrafast carrier dynamics and transport of gallium arsenide thin films on silicon and magnesium oxide substrates

We investigate strain effects on the ultrafast carrier dynamics and transport of gallium arsenide films on silicon (GaAs/Si) and magnesium oxide (GaAs/MgO) substrates using temperature-dependent photoluminescence (PL) and terahertz time-domain spectroscopy (THz-TDS) from 11 K - 300 K. The PL shows that GaAs/Si and GaAs/MgO samples are under tensile and compressive strain at low temperature, respectively. The temperature-dependent THz emission from GaAs/Si does not show significant differences with the emission from bulk GaAs, while the THz emission from GaAs/MgO shows an order-of-magnitude decrease at low temperature. The THz emission from the samples exhibits an interplay between strain-induced effective mass changes and temperature-dependent electric field effects.

Strain engineering and thermoelectric performance of Janus monolayers of titanium dichalcogenides: A DFT study

By employing state-of-the-art density functional theory calculations, we have investigated the effect of compressive and tensile strain on the electronic and transport properties of recently invented Janus monolayers of 1 T TiXY (X, Y = S, Se, Te). The lattice dynamics studies reveal that the monolayers of TiSSe are stable up to a tensile strain of 4 %, whereas TiSTe and TiSeTe monolayers are stable up to 10 % tensile strain. The compressive strain leads to appearance of imaginary phonon frequencies indicating the instability of these monolayers against compressive strain. Our results predict that the strain engineering has a favorable impact on the electronic band structure. According to our findings, with increase in biaxial tensile strain on all the studied monolayers the Seebeck coefficient increases and the electronic thermal conductivity reduces which results in improved ZT. The obtained ZT values at highest tolerable tensile strains for these monolayers are found to be 1.04, of 0.95 and 0.88 for TiSSe, TiSTe and TiSeTe respectively. Further, the spin orbit coupling does not have any significant effect on electronic properties. Thus, our study predicts that biaxial strain can drastically enhance thermoelectric performance of the studied Janus monolayers. Hence, these materials have the potential to find use in nanoscale optoelectronic and thermoelectric devices.

Predicting the adsorption and reduction of NO2 on Sr-doped CeO2(1 1 1) using first-principles calculations

Developing highly efficient materials for adsorbing and reducing NO2 is significant for reducing air pollution due to the released nitrogen oxides from cars. In this study, the performance of Sr-doped CeO2-δ(111) with regard to the adsorption of NO2 and it’s reduction was systematically elucidated. Furthermore, the adsorption strength of NO2 onto Sr-doped ceria can be further tuned via strain and a promoter. The effect of tensile strain applied to Sr-doped ceria was lower than that of the Al promoter with regard to strengthening the NO2-adsorption onto Sr-doped ceria. The charge transfer between NO2 and the adsorbent (i.e., Sr-doped ceria and Al (Sr)-promoted (doped) ceria) was also analyzed to reveal the influence of the presence of the Al promoter on the adsorption of NO2 using the Bader charge method. This analysis demonstrated that the charge amount moved to NO2 from the adsorbent increased through the promotion of Al in Sr-doped ceria.

Understanding the Semiconducting-to-Metallic Transition in the CF2Si Monolayer under Shear Tensile Strain

With the ever-increasing interest in low-dimensional materials, it is urgent to understand the effect of strain on these kinds of structures. In this study, taking the CF2Si monolayer as an example, a computational study was carried out to investigate the effect of tensile shear strain on this compound. The structure was dynamically and thermodynamically stable under ambient conditions. By applying tensile shear, the structure showed a strain-driven transition from a semiconducting to a metallic behavior. This electronic transition’s nature was studied by means of the electron localization function index and an analysis of the noncovalent interactions. The result showed that the elongation of covalent bonds was not responsible for this metallization but rather noncovalent interactions governing the nonbonded bonds of the structure. This strain-tuned behavior might be capable of developing new devices with multiple properties involving the change in the nature of chemical bonding in low-dimensional structures.

Interfacial antiferromagnetic phase induced two-step magnetization reversal in PbZr0.52Ti0.48O3/La0.67Sr0.33MnO3 superlattices

Artificial multiferroic heterostructures have recently attracted much interests due to the demonstrated magnetoelectric coupling (MEC) and unique functionalities, promising a tantalizing perspective of novel applications in next-generation electronic, memory, sensor, and energy harvesting technologies. Herein, we report a two-step magnetization reversal in PbZr0.52Ti0.48O3/La0.67Sr0.33MnO3 (PZT/LSMO) superlattices, which originates from the strongly entangled strain-, ferroelectric (FE)-polarization-, and exchange-dependent effects. Specifically, the preferential occupancy of the in-plane Mn dx2−y2 orbitals is triggered via the collective effects of the large tensile strain and FE polarization, giving rise to an interfacial antiferromagnetic (AFM) layer with strong AFM anisotropy. The strong spin exchange coupling between the AFM layer and the adjacent ferromagnetic (FM) layer facilitates the magnetic stratification of the FM layer, leading to two coercivities, i.e., two-step magnetization reversal. Meanwhile, a sizeable exchange bias (EB) field is induced. The emerged two-step magnetization reversal concomitant with the pronounced EB phenomenon should be a signature of an enhanced MEC in PZT/LSMO superlattices. Our results will stimulate further interests in multiferroic superlattices in applications of multiferroic-based devices.

Shape memory property and mechanism of the knitting-fabric reinforced epoxy composites subjected to tensile loading

Shape memory polymers (SMPs), as stimulus-responsive shape-shifting materials, are generally reinforced with particles and fibers to fabricate the shape memory polymer composites (SMPCs) for better mechanical and shape-recovery properties. However, many continuous fibers reinforced SMPCs have good shape recoverability subjected to bending loading but limited shape recoverability under tensile loading due to limitation of tensile deformation of continuous fibers. Here, we developed the continuous fiber knitting-fabric reinforced shape memory epoxy composites and investigated their shape memory property and mechanism subjected to large tensile strain. The effect of epoxy component ratios, tensile strains, and course(0°)/wale(90°) directions on the shape memory behavior, recovery stress, and mechanical property of the shape memory epoxy (SMEP) and its composite (SMPC) were studied. The results show that the SMEPs and SMPCs with the tensile strain up to 30% have good shape fixation rates of above 99% and final recovery ratios of above 98%. A mesoscopic finite element model of knitting-fabric reinforced SMPC was established to study the shape memory mechanism. The recovery stress of the SMPC can improve up to 5.8 times as compared with pure SMEP. The knowledge gained in this work will benefit future development and application for better actuators.

The Synergy of Tensile Strain and Ligand Effect in PtBi Nanorings for Boosting Electrocatalytic Alcohol Oxidation

AbstractAs the best electrocatalysts for alcohol oxidation reactions in direct alcohol fuel cells (DAFCs), Pt‐based nanomaterials still face the challenges of low utilization efficiency of Pt atoms and poor reaction kinetics. To address these issues, a self‐etching strategy is developed to prepare PtBi nanorings (NRs) with abundant low‐coordinated atoms and inhomogeneous tensile strain (≈4%). The obtained PtBi NRs exhibit superior activity toward methanol oxidation reaction (MOR) and ethanol oxidation reaction (EOR) in alkaline media. Particularly, the mass activities of PtBi NRs for MOR and EOR are 9.4 and 8.5 times higher than those of commercial Pt/C, respectively, which are among the best in the reported Pt‐based catalysts. The highly open structure of PtBi NRs is believed to provide plentiful catalytic active sites and increase the utilization of Pt atoms. Theoretical calculations show that the two important factors, i.e., adsorption energy with the key reaction intermediates and the energy barrier for the potential‐determining step, are significantly optimized owing to the synergy of tensile strain and the ligand effect in PtBi NRs. This study offers a promising strategy for the rational design and preparation of highly efficient catalysts for DAFCs.

Effects of tensile strain on the electronic, optical and ferroelectric properties of a multifunctional R3c InFeO3 compound

The search for materials with appropriate ferroelectric and photovoltaic properties is an intense field of research. The main objective of these studies is to obtain efficient materials for solar cell applications. In this work, non-collinear spin density functional theory calculations are performed to describe the electronic, optical, and ferroelectric properties of a multiferroic R3c InFeO3 compound under tensile strain. Our studies reveal that under conditions of tensile strain, this material had ideal fundamental properties for photovoltaic applications. Under 9% tensile strain of the R3c InFeO3 unit cell volume (a = 5.536 Å and c = 13.808 Å), a direct energy band gap of 1.74 eV was found. With this energy band gap, the material absorbs the entire range of visible light, and for a film thickness of up to 100 nm it reaches a maximum photoconversion efficiency of 20%, a higher value than observed in some semiconductors that are used in practice. Furthermore, the effective mass of charge carriers (m*), and the exciton binding energy (Eb) are significantly decreased (m* < 0.4 m0 and Eb < 1.0 meV), which likely to lead to better charge mobility and easier separation of the electron-hole pair in the process of photoabsorption. Under this level of strain, the spontaneous electric polarization was reduced to 77.6 µC/cm2, a value that is still higher than other ferroelectric-photovoltaic materials.

Strain engineering on the thermoelectric performance of monolayer AlP3: A first-principles study

Recently, the two-dimensional semiconductor AlP 3 has been proved to be a promising thermoelectric material with high carrier mobility and low thermal conductivity . By using first-principles methods combined with Boltzmann transport theory, we investigate the effect of biaxial tensile strain on the thermoelectric properties of monolayer AlP 3 . Through calculating electronic transport properties, we find that the electron mobility first increases and then drops with the increase of tensile strain. Furthermore, the power factor of monolayer AlP 3 under a 4% tensile strain has been significantly improved, indicating that strain engineering could enhance the power factor of monolayer AlP 3 . Moreover, the tensile strain will increase the electronic and lattice thermal conductivities. Compared with unstrained AlP 3 , the increase of lattice thermal conductivities of strained monolayer AlP 3 results from a higher phonon lifetime. The ZT and maximum energy conversion efficiency of n -type doping monolayer AlP 3 under a 4% tensile strain can reach 7.13 and 29.4% at 700 K. This study provides an in-depth understanding of the transport properties of monolayer AlP 3 by applying tensile strain and monolayer AlP 3 has a great potential in flexible thermoelectric applications. • The biaxial tensile strain can improve the power factor of monolayer AlP 3 . • The tensile strain can tune the thermal conductivity of monolayer AlP 3 . • The ZT of n -type doping monolayer AlP 3 under a 4% tensile strain can reach 7.13 • Monolayer AlP 3 has a great potential in flexible thermoelectric applications.

Studies on the abnormal effect of tensile strain on the MC→M23C6 in-situ transformation in Ni-based superalloy

Experiment and first-principles calculations were utilized to study the effect of tensile strain on the MC→M23C6 in-situ transformation in MC-M23C6 complex carbide as well as its micro-mechanism. The experiment indicates that strain inhibits the transformation. According to the calculations, Cr atoms will occupy M sublattice sites and diffusion through the VM-(VC)6 vacancy clusters in MC. Nevertheless, a single VM mechanism works during the diffusion of Cr atoms across the MC/M23C6 interface. Tensile strain as well as its direction can seriously influence the diffusion behavior of atoms by expanding or compressing the lattice. Generally, tensile strain will facilitate the diffusion of Cr atoms in MC and the flipping of diagonals. However, tensile strain decreases the lattice mismatch at the MC/M23C6 interface. Thus, the activation energy of the diffusion of Cr across the interface increases and the diffusion coefficient decreases. Strain inhibits the transformation mainly by restraining the diffusion of Cr atoms across the MC/M23C6 interface. The demonstrated concept enables a deeper understanding of superalloys and shed light on the rational design of higher property superalloys for various potential applications.

First-principles study on the electronic structure, magnetic and optical properties of strain regulated (V, Cr) co-doped SnSe2

The effects of strain and doped on the magnetic and optical properties of SnSe2 were studied by density functional theory. The results shown that intrinsic SnSe2 is a narrow indirect band gap semiconductor (0.781 eV). And shown that the ferromagnetism is enhanced in tensile strain, in which the ΔE increases nearly three times with the X6%, the ΔE increases nearly two times with the Y4% and the ΔE increases nearly two times with the B2%. Therefore, the effect of tensile strain on the ferromagnetism of SnSe2 is more obvious. In terms of charge transfer, the amount of charge transfer under tensile strain is more than that under compressive strain. More interestingly, with the regulations of doping and strain, the absorption spectrum in the visible part is weakened, accompanied by phenomena of the red shift. The paper provides a feasible scheme for regulating the ferromagnetic state of SnSe2 and developing spin electronics and optoelectronic devices.