Tensile Strain Research Articles

Effect of alloying element segregation on theoretical strength and structural low-energy transition of Ni grain boundaries: A first-principles computational tensile test study

Enhancing the stability and strength of nanocrystalline metals through the manipulation of grain boundary (GB) chemistry and structure is crucial for their engineering applications. In this study, first-principle computational tensile tests on Ni Σ5 [001] (210) GBs were conducted with considering Poisson's ratio and strengthening effect of alloying elements B, W, Zr, Ta, B-W and Zr-Ta segregation. The results indicate that the Zr-Ta co-segregated GB shows a remarkable increase in theoretical tensile strength by 195 % compared to the clean GB under small strain conditions. As tensile strain increases, both clean and segregated GBs undergo a low-energy structural transition from the Σ5 [001] (210) to the more stable Σ11 [110] (113). This work presents a promising approach for enhancing the stability of Ni nanograined materials through tensile deformation and GB segregation.

Lignin sulfonate induced ultrafast fabrication of polypyrrole-based conductive organohydrogel for high performance flexible strain and temperature sensor

The ultrafast preparation of electrically conductive hydrogels to endow high sensing performance and temperature tolerance remains a critical challenge. Herein, lignosulfonate sodium-templated polypyrrole (LS-PPy) nanofillers were rapidly introduced into polyacrylic acid (PAA) hydrogel through ultrafast free radical polymerization in a glycerol/water binary solvent system. The resultant LS-PPy/PAA electrically conductive organohydrogel possesses satisfactory mechanical performance (strength of 56 kPa at a tensile strain of 800 %), strong adhesion, and a desirable low freezing point (−35 °C). Furthermore, this organohydrogel exhibits high strain sensitivity (gauge factor = 2.65), fast response time (~160 ms), low signal hysteresis, and excellent cyclic stability (over 1200 cycles). And the wearable LS-PPy/PAA organohydrogel sensor could accurately and real-time monitor various intense or subtle human movements, such as joint bending, facial expression and hand writing. Besides, the developed LS-PPy/PAA temperature sensor can respond to environmental temperature variations over a wide range of −20–100 °C. High resolution of 0.5 °C with remarkable sensitivity (−0.80 %/°C and linearity of R2 = 0.99) and repeatability were achieved within 36.5–40 °C, which makes it suitable for human body temperature monitoring. All these results demonstrate the substantial prospective value of the LS-PPy/PAA hydrogel in wearable sensors and other associated fields.

Topological phase engineering of rutile GeO2 with strain

Nodal-line semimetals serve as the parent phase for various topological states. By manipulating spin-orbit coupling (SOC), time-reversal symmetry, or spatial inversion symmetry, a Dirac nodal-line semimetal can transition into a 3D Dirac semimetal, Weyl semimetal, or topological insulator.In this study, we present the topological phase engineering of rutile GeO2 under strain through first-principles calculations. Without considering SOC effect, applying tensile strain to GeO2 induces a transformation from a trivial insulator to a Dirac nodal-line semimetal, characterized by two orthogonal and interconnected Dirac nodal rings protected by mirror symmetry. When SOC is taken into account, the band degeneracy persists only at two points, resulting in a 3D Dirac semimetal. Nonetheless, due to the negligible strength of SOC in GeO2, its nodal-line semimetal properties remain largely intact even after including SOC effects.Our findings provide valuable insights for the topological phase engineering and potential spintronics applications of GeO2.

Surface chemo-mechanics coupling of MnO2/Au layered composites under electrochemical environment

The intersection of surface mechanics and electrochemistry has gradually become a prominent topic in the realm of new energy research. To explore the influence of the electrochemical process on the stress of energy storage electrode composite, supercapacitor material manganese dioxide (MnO2) was selected as the coating and the MnO2/Au composites were prepared by the electrochemical deposition. The surface stress of MnO2/Au composites under different electrochemical modes and the stress variation law of MnO2 with varying thicknesses were determined. The addition of MnO2 could alter the stress response and the strain magnitude of the gold electrode with varied electrochemical potential. The reversible tensile strain within the Au surface during 0.3 ∼ 0.8 V charging was induced by the absorption of SO42−, while the compressive strain of the MnO2/Au composites was related to the extraction of Na+ ions resulting from the redox pseudocapacitance of MnO2. Notably, the produced stress exhibited a linear correlation with the capacitance. And the long-cycle tests revealed that as the specific capacitance of electrodes decreased, the induced tensile stress progressively diminished. This study emphasized the surface chemo-mechanics coupling of both the Au layer and MnO2/Au composites, which would provide a new approach to regulating surface strain in the solid–liquid interface.

Strain effect on the electronic and optical characteristics of FAGeX3 (X=Cl, Br, and I) perovskite materials: DFT analysis

This study investigates the electronic and optical properties of a perovskite material known as Formamidinium Germanium Halide (FAGeX3), where X represents the elements Chlorine (Cl), Bromine (Br), and Iodine (I). We explore the bandgap, density of state (DOS), and partial density of state (PDOS) to understand their electronic properties. We use two methods, PBE and HSE-06, to determine the bandgap. Further, we investigate the optical properties by investigating the real and imaginary functions of the dielectric constant, refractive index, electron energy loss function, and absorption coefficient. Our research extends to the impact of biaxial strain, both tensile and compressive, in the −6% to +6 % range. Without strain, the materials exhibit direct bandgaps at the R point, with FAGeCl3 showing the highest bandgap (2.1359 eV), followed by FAGeBr3 (1.7325 eV), and FAGeI3 with the lowest (1.2581 eV). Our results reveal that applying tensile strain increases the bandgap and induces a blueshift, shifting the optical responses to shorter wavelengths, while compressive strain reduces the bandgap and causes a redshift, enhancing longer wavelength responses. Our findings demonstrate that FAGeX3 perovskites exhibit highly tunable electronic and optical properties under strain, making them exceptional candidates for advanced optoelectronic applications.

Experimental study on mechanical behavior and countermeasures of mountain tunnels under strike-slip fault movement

In the seismic mountainous regions such as western China, it is usuallly inevitable to construct tunnels near active fault zones. Those fault-crossing tunnel structures can be extremely vulnerable during earthquakes. Extensive experimental studies have been conducted on the response of continuous mountain tunnels under reverse and normal fault movements, limited experimental investigations are available in the literatures on mountain tunnels with special structural measures crossing strike-slip faults. In this study, a new experimental facility for simulating the movement of strike-slip fault was developed, accounting for the spatial deformation characteristics of large active fault zones. Two groups of sandbox experiment were performed on the scaled tunnel models to investigate the evolution of ground deformation and surface rupture subjected to strike-slip fault motion and its impact on a water conveyance tunnel. The nonlinear response and damage mechanism of continuous tunnels and tunnels incorporated with specially designed articulated system were examined. The test results show that most of slip between stationary block and moving block occurred within the fault core, and significant surface ruptures are observed along the fault strike direction at the fault damage zone. The continuous tunnel undergoes significant shrinkage deformation and diagonal-shear failure near the slip surface and resulted in localized collapse of tunnel lining. The segments of articulated system tunnel suffer a significant horizontal deflection of about 5°, which results in opening and misalignment at the flexible joint. The width of the damaged zone of the articulated system tunnel is about 0.44 to 0.57 times that of the continuous tunnel. Compared to continuous tunnels, the articulated design significantly reduces the axial strain response of the tunnel lining, but increases the circumferential tensile strain at the tunnel crown and invert. It is concluded that articulated design provides an effective measure to reduce the extent of damage in mountain tunnel.

Exploring the inorganic perovskite materials Mg3SbX3 (Where, X=I, Br, Cl and F) through the perspective of density functional theory: Adjustment of physical characteristics as consequence of strain

The solar technology industry has lately given inorganic perovskite materials an abundance of thought because of their unique optical, electrical and structural characteristics. Issues pertaining to lead (Pb) toxicity and instability require being referred to promptly, making lead-free atomically designed metal halide perovskites of foremost importance to the photovoltaic and optoelectronic industries. Perovskites, a class of inorganic metal halide semiconductors, have variant similarities with Mg3SbX3 (X = I, Br, Cl and F). According to the space group Pm-3m Mg3SbX3 (X = I, Br, Cl and F) has a cubic perovskite crystal structure. Utilizing first-principles density-functional theory (FPDFT), The intention of this investigation is to analyze how strain and spin-orbit coupling (SOC) impact the structural, electrical, optical and mechanical features of the inorganic cubic perovskite of Mg3SbX3 (X = I, Br, Cl and F). At the point between R and Γ, the Mg3SbI3,Mg3SbBr3,Mg3SbCl3 molecule displays an indirect bandgap of 0.105 eV, 0.957 eV, 1.728 eV. At the Γ point, the Mg3SbF3 molecule displays a direct bandgap of 3.184 eV. The bandgaps of the Mg3SbI3,Mg3SbBr3,Mg3SbCl3 and Mg3SbF3 perovskites are 0.198 eV, 1.203 eV, 1.901 eV and 3.723 eV respectively, when considering the spin-orbital coupling (SOC) quantum influence. A wider bandgap is investigated for increasing compressive strain while a smaller bandgap is observed for increasing tensile strain. Apart from the elastic constants and anisotropic factors, other factors that are anticipated include Pugh's ratio, Poisson's ratio, bulk modulus and others. Isotropic, ductile and mechanically stable are the words that best describe these materials, according to the elastic property evaluations. In the photon energy range that is appropriate for solar cells, the dielectric constant spikes of Mg3SbX3 are found to be visible. Therefore, Mg3SbX3 (X = I, Br, Cl and F) perovskite is a good material to use in solar cells for managing light and producing electricity.

Heteroatom‐induced tensile strain in copper lattice boosts CO2 electroreduction toward multi‐carbon products

AbstractStrain engineering on metal‐based catalysts has been utilized as an efficacious strategy to regulate the mechanism and pathways in various electrocatalytic reactions. However, controlling strain and establishing the strain‐activity relationship still remain significant challenges. Herein, three different and continuous tensile strains (CuPd‐1.90%, CuAu‐3.37%, and CuAg‐4.33%) are successfully induced by introducing heteroatoms with different atomic radius. The catalytic performances of CuPd‐1.90%, CuAu‐3.37%, and CuAg‐4.33% display a positive correlation against tensile strains in electrochemical CO2 reduction reaction (CO2RR). Specifically, CuAg‐4.33% exhibits superior catalytic performance with a 77.9% Faradaic efficiency of multi‐carbon products at −300 mA cm−2 current density, significantly higher than those of pristine Cu (Cu‐0%). Theoretical calculations and in situ spectroscopies verify that tensile strain can affect the d‐band center of Cu, thereby altering the binding energy of *CO intermediates and Gibbs free energies of the C–C coupling procedure. This work might highlight a new method for precisely regulating the lattice strain of metallic catalysts in different electrocatalytic reactions.

Tip-like copper sites on high curvature supports for non-covalent to covalent interaction tuning in CO2 photoreduction

Single-atom engineering offers a promising method to transform CO2 into high-value chemicals. The local coordination structure design of the metal-support is crucial for overcoming slow reaction kinetics. In this study, Cu single atoms are immobilized on curved Bi12O17Br2 surface to create a tip-like metal site structure named Cutip-Bi12O17Br2. Due to the high curvature Bi12O17Br2 surface with tensile strain, the tip Cu creates significant electronegativity differences between adjacent Bi atomic sites, creating the vigorous polarization centers. The strong charge redistribution character of tip asymmetric Cu-Bi site favor the polarization of CO bond in nonpolar CO2 and adjust the noncovalent to covalent interaction of reaction intermediates. Benefiting from these features, the optimized Cutip-Bi12O17Br2 enhance the CO production rate by a factor of 34 relative to bulk-Bi12O17Br2, reaching a rate of 96.99 μmol g−1 h−1. This work provides a comprehensive understanding of the structural regulation of single-atom on high curvature surface for CO2 photoreduction.

Examining the electronic, structural, optical, and photovoltaic capabilities of Sr3AsBr3 perovskite under tensile and compressive strains with DFT and SCAPS-1D

A significant amount of interest in the field of solar energy has recently been generated by the remarkable optical, structural, and electronic attributes of inorganic perovskite-based substances. A thorough investigation was conducted on how tensile along with compressive strains influence the electronic and optical properties of halide perovskite Sr3AsBr3, utilizing FP-DFT. The PBE functional is used to determine the direct bandgap of 1.512 eV for unstrained Sr3AsBr3 at the Γ position. The bandgap redshifts (1.216 eV at -4 % strain) under compressive strain and slightly increases (1.728 eV at +4 % strain) under tensile tension, causing the absorption coefficient to blueshift. The optical properties, including the functions of dielectric, electron energy loss function, and absorption coefficient, all indicate a considerable capacity for absorption in the area of the visible spectrum, and the band characteristics of this component agree with these qualities. We used Sr3AsBr3 absorbers and CdS electron transport layers (ETL) with different thicknesses, defect densities, and doping concentrations to study solar power capabilities using the SCAPS-1D simulator. The most effective arrangement (at -4 % strain) had a fill factor (FF) of 86.76 %, a short-circuit current density (JSC) of 37.5593 mAcm−2, an open-circuit voltage (VOC) of 0.8712 V, and a power conversion efficiency (PCE) of 28.39 %. Our findings support additional research into Sr3AsBr3, a promising perovskite for optoelectronic uses.

The effect of post heat treatment on microstructural evolution and mechanical properties of Ti2AlNb intermetallic alloy prepared by point-forging and laser-deposition

Ti2AlNb-based intermetallic alloy is considered to be the latest class of light-weight structural material severing in the range of 600∼750 °C. Hybrid interlayer point-forging with laser-deposition (PF-LD) provides a new idea to produce near-net-shape Ti2AlNb part with promising mechanical performance. The present work mainly investigated the effect of post heat-treatment on microstructural evolution and tensile mechanical properties of PF-LDed Ti2AlNb alloy. The experimental results demonstrated that solution-treated at 940 °C–1020 °C followed by aging at 840 °C was effective to regulate phase morphology and tensile mechanical properties. With the consecutive increase of solution temperature, more fine-lamellar O-phase was reprecipitated within parent B2/β matrix during secondary aging treatment. The ultimate tensile strength was enhanced significantly from 1055.5 MPa to 1148.1 MPa with the help of precipitation hardening effect. In the meantime, stronger stress accumulation introduced by fine-lamella also exerted a detrimental impact on tensile strain capability, and the elongation after failure decreased from 10.9 % to 7.4 % with increasing solution temperature. Considering above results, this study provides a basic research for exploring the heat treatment of PF-LDed Ti2AlNb-alloy, and it is feasible to obtain high-strength and high-ductility properties by tailoring phase morphology.

First-principles prediction of high carrier mobility for β-phase MX2N4 (M = Mo, W; X = Si, Ge) monolayers

The recently synthesized monolayer MoSi2N4 (Science 2020, 369, 367) exhibits exceptional environmental stability, a moderate band gap, and excellent mechanical properties, presenting exciting opportunities for the exploration of two-dimensional (2D) MX2Z4 materials. However, the low carrier mobility of α-phase MoSi2N4 significantly limits its potential applications in field-effect transistor (FET) devices. In this study, we systematically investigate the structural stability, elastic properties, and carrier mobility of a novel family of β-phase MX2N4 (M = Mo, W; X = Si, Ge) monolayers through first-principles calculations. Our findings reveal that these β-phase MX2N4 monolayers demonstrate remarkable dynamic, thermal, and mechanical stability. Specifically, we identify the MoSi2N4, MoGe2N4, WSi2N4, and WGe2N4 monolayers as semiconductors with band gaps of 2.70 eV, 1.57 eV, 3.12 eV, and 1.93 eV, respectively, as calculated using the HSE06 functional. Moreover, the MX2N4 monolayers exhibit significant elastic anisotropy, characterized by high ideal tensile strengths and a critical tensile strain exceeding 25%. Notably, the WGe2N4 monolayer displays exceptional anisotropic in-plane charge transport, achieving mobility levels of up to 104 cm2V− 1S− 1, surpassing those of the α-phase MX2N4 monolayers. These novel ternary monolayer structures have the potential to broaden the 2D MX2Z4 material family and emerge as promising candidates for applications in field-effect transistors.

Fatigue Behavior of Cord-Rubber Composite Materials under Different Loading Conditions.

Cord-rubber composites are subjected to a wide range of loads in various applications. However, their fatigue behavior remains relatively under-researched. To address this gap, a set of representative specimens was developed, and a validated numerical model was employed to assess fatigue-relevant parameters. In this study, we present the results from two series of tests with different strain ratios (R values). One series was subjected to a pure pulsating tensile strain (R ~0), while the second series experienced an increased mean strain with an R ratio between 0.2 and 0.3. A direct comparison of the two series demonstrated that a higher strain ratio results in a longer service life. This is reflected in an increase in the slope (k) from 13 to 23, as well as an increase in the ultimate fiber strain from 8% to 11% at Nd = 50,000 load cycles for a survival probability of 50%. Both series indicate a comparable scatter in the test results. This comparative analysis shows that the strain ratio significantly impacts the fatigue behavior of cord-rubber composite materials based on cyclic tests under different loading conditions. The findings of this study demonstrate the necessity of considering different load situations when evaluating or designing components.

Controlled Vapor-Liquid-Solid Growth of Long and Remarkably Thin Pb1-xSnxTe Nanowires with Strain-Tunable Ferroelectric Phase Transition.

The Pb1-xSnxTe family of compounds possess a wide range of intriguing and useful physical properties, including topologically protected surface states, robust ferroelectricity, remarkable thermoelectric properties, and potential topological superconductivity. Compared to bulk crystals, one-dimensional (1D) nanowires (NWs) offer a unique platform to enhance the functional properties and enable new capabilities, e.g., to realize 1D Majorana zero modes for quantum computations. However, it has been challenging to achieve controlled synthesis of ultrathin Pb1-xSnxTe (0 ≤ x ≤ 1) nanowires in the truly 1D region. In this work, we report on a Au-catalyzed vapor-liquid-solid (VLS) growth of remarkably thin (20-30 nm) and sufficiently long (several to tens of micrometers) Pb1-xSnxTe nanowires of high single-crystalline quality in a controlled fashion. This controlled growth was achieved by enhancing the incorporation of Te into the Au catalyst particle to facilitate the precipitation of the Sn/Pb species and suppress the enlargement of the particle, which we identified as a major challenge for the growth of ultrathin nanowires. Our growth strategy can be easily extended to other compound and alloy nanowires, where the constituent elements have different incorporation rates into the catalyst particle. Furthermore, the growth of thin Pb1-xSnxTe nanowires enabled strain-dependent electrical transport measurements, which shows an enhancement of electrical resistance and ferroelectric transition temperature induced by uniaxial tensile strain along the nanowire axial direction, consistent with density functional theory calculations of the structural phase stability.

Strain-oxygen vacancies coupling in topotactic (La,Sr)CoO3-δ thin films

Oxygen defect engineering is a widely used approach for tuning physical properties in oxides. Multivalent transition metal oxide La0.7Sr0.3CoO3-δ (LSCO) shows oxygen vacancy-driven metal-to-insulator transition (MIT) due to topotactic phase transition and its high oxygen vacancy tolerance. Here, we introduce strain as a new degree of freedom to study the strain-oxygen vacancy coupling effects and elucidate its impact on the electronic property in oxygen-deficient LSCO epitaxial thin films grown on SrTiO3 (100) single crystal. By combining the experimental results with density functional theory plus U (DFT+U) calculations, we reveal that 2.1 % in-plane tensile strain can stabilize the insulating state of LSCO with a surprisingly low concentration of oxygen vacancies, <0.5 %. This study reveals that the MIT in LSCO is governed by the combination of oxygen vacancies and strain, offering the potential for additional tuning knob of the material's electronic properties.

Selective Epitaxy of Tensile, Highly Doped SiP for Planar NMOS FD-SOI Devices

The epitaxy of sources and drains is a critical enabler for enhanced transistor performances. In N-type MOS devices, selective SiP epitaxy can simultaneously yield (i) very high levels of electrically active dopants which is crucial for contact resistance minimization and (ii), tensile strain in Raised Sources and Drains (RSD) on each side of Si FD-SOI channels. This study present process solutions in order to benefit from large amounts of phosphorus in a silicon lattice and have thereby tensile strain, while maintaining excellent crystal quality, good surface morphology and a low electrical resistivity. We use here industrial precursors widely used in manufacturing, e.g. a [SiH2Cl2 + PH3 + HCl + H2] chemistry, for the selective deposition, in the 600°C-700°C range, of SiP in conventional epitaxy reactors. We achieved phosphorous concentrations as high as 4.6×10²¹ cm-3 (9.3%) in blanket SiP layers while preserving good crystal quality. In FD-SOI devices, we succeeded in having a selective process yielding rather smooth and free of defects Si:P films with 1.6×10²¹ cm-3(3.2%) of P.

Fabrication of High-Performance Asphalt Mixture Using Waterborne Epoxy-Acrylate Resin Modified Emulsified Asphalt (WEREA)

Existing research shows that using waterborne epoxy resin (WER) instead of emulsified asphalt as the binder for cold mix asphalt (CMA) can enhance the rutting resistance, high-temperature performance, fracture performance, and early performance of CMA. In order to eliminate the potential drawbacks such as insufficient strength and low-temperature performance of CMA during application, a novel method was proposed in this study for the preparation of waterborne epoxy-acrylate resin (WER), specifically tailored to modify emulsified asphalt, resulting in waterborne epoxy-acrylate resin emulsified asphalt (WEREA). The modification effect of WER on emulsified asphalt was evaluated through rheological tests and direct tensile tests. A modified design method based on the conventional Marshall design method was proposed to determine the optimal mix proportions, including the key parameters of specimen compaction and curing. The results revealed that the incorporation of WER led to a substantial improvement in the complex shear modulus and a concurrent decrease in the phase angle. When the temperature exceeded 60 °C, the phase angle exhibited a diminishing trend, indicative of a reduced viscosity as temperatures escalated. As the WER content increased, a decrease in the direct tensile strain rate was observed, accompanied by a substantial elevation in direct tensile strength. At various stress levels, the shear strain of WEREA decreases with increased content of WER, indicating that the incorporation of WER can enhance the hardness of emulsified asphalt and improve its deformation resistance. The results from MSCR tests indicate that WER could significantly improve the elasticity and hardness of emulsified asphalt, transitioning it from a viscoelastic material to an elastic material, thereby improving its deformation resistance, resistance to rutting, and high-temperature performance. The results of fatigue life are consistent with those of the amplitude sweep, both reflecting the improvement of resistance to deformation of emulsified asphalt by WER. This indicates that WER has a significant improving effect on the fatigue resistance of emulsified asphalt. Furthermore, the Marshall design tests further confirmed the advantages of WEREA in asphalt mixtures. The optimal preparation for the WEREA mixture was proposed as follows: double-sided compaction for 50 times each, aging at 60 °C for 48 h, optimal moisture content of 5.14%, cement content of 2.5%, and emulsion content of 8.4%. The optimal mix proportions identified through these tests yielded asphalt mixtures with significantly improved stability, reduced flow value, and enhanced rutting resistance compared to the hot-mix asphalt mixture (HMA) of AC-16. These findings suggest that WEREA has the potential to significantly enhance the durability and longevity of asphalt pavements. For future applications, it can be explored for use in producing cold recycled asphalt mixtures. In addition to designing the WEREA mixture according to AC-16 gradation, consideration can also be given to using a gradation with a smaller nominal maximum aggregate size for the application in the surface layer or ultra-thin wearing course.

An ab initio and monte carlo study of MS2/VS2 (M=Mo, W) ferromagnetic bilayer with negative magnetoresistance in MoS2/VS2 heterostructure

Herein, the electronic and magnetic properties of ferromagnetic van der Waals MS2/VS2 (M=Mo, W) heterostructures, investigated using density functional theory (DFT) and Monte Carlo (MC) simulations are reported. Stability was confirmed via interlayer binding energy, and electronic band structure analysis revealed an indirect band gap with staggered (type II) heterojunctions. The systems exhibit potential for opto-spintronics devices due to large band offsets in both spin channels. Ferromagnetic ground states were identified with Curie temperatures of 299 K and 301 K for MoS2/VS2 and WS2/VS2, respectively. Biaxial strain studies indicated that while WS2/VS2 transitions to half-metallic behavior under tensile strain beyond 1%, the Curie temperatures decrease under both compressive and tensile strains, demonstrating tunable magnetic properties. Additionally, MoS2/VS2 heterostructures fabricated via drop casting exhibited negative magnetoresistance, suggesting potential in spintronics applications.

Spectroscopic Study of Strain, Oxidation, and Formation of Few-Layer Graphene at Steel Surfaces Tribologically Tested against MoS2 Films.

MoS2 not only has unique optoelectronic properties realizing photonic and semiconductor applications but also serves as a promising solid lubricant in tribological three-body contacts due to its advantageous friction and wear behavior. Its functionality is defined by elementary processes including strain, oxidation processes, and material mixing. However, these mechanisms were not elucidated for MoS2 having transferred from the MoS2 film synthesized at the main body to a steel counter body during tribological ball-on-disk tests. Using spatially and spectrally high-resolved Raman spectroscopy, we study the compressive and tensile strain within the MoS2 transfer material and analyze the oxidation of molybdenum, sulfur, and iron. In addition, we elaborate on the impact of transition metals modifying the MoS2 films on the strain distribution and oxidation processes. Decreasing intensities of the MoS2 Raman lines are accompanied with enhanced intensities of sulphur and molybdenum oxide Raman signatures which are particularly agglomerated at the edges of the tribological track. The formation of tribochemical oxides, including Mo4O11 in the Magnéli-phase, depends weakly on the type of modifying element, and an oxidation of a modification element itself is not detected. We also identified a tribologically induced formation of disordered few-layer graphene at counter-body surface areas which experienced weak thermo-mechanical tribological load. Our results characterize structural and chemical features of the MoS2 transfer material, thus predicting material failure at the microscopic level.

Lime Stabilization of Tropical Soil for Resilient Pavements: Mechanical, Microscopic, and Mineralogical Characteristics.

Lime stabilization is a sustainable technique due to its use of local materials, increased durability, reduced maintenance, and improved resistance to water action. This paper examines the impact of lime stabilization on the mechanical, microscopic, and mineralogical properties of a tropical soil. Two types of lime, calcitic and dolomitic, were tested at 3% and 5% by weight. Compressive, indirect tensile and flexural test results and statistical analysis revealed that calcitic lime mixtures had higher strength and stiffness, whereas dolomitic lime mixtures exhibited greater deformability with higher tensile strain at break. Scanning electron microscopy indicated that the soil's porous matrix closed within 7 days for both lime types due to flocculation, with increased matrix interlocking over time. The calcitic lime mixture developed a more closed matrix compared to the dolomitic lime, which showed weaker cementing. X-ray diffraction analysis indicated higher consumption of clay minerals and a notable reduction in calcium hydroxide peaks in the lime-treated soils. The study concludes that calcitic lime provides better pavement performance for stabilizing the soil, enhancing its engineering properties while also being sustainable by reducing the need for raw material extraction and improving resilience to climate-related issues such as floods.