Strain and electric field tunable photoelectric properties of multilayer Sb2Se3

Antimony selenide, Sb2Se3, has been attracted widespread attention in photovoltaic applications due to its high absorption coefficient and suitable band gap. However, the influence of uniaxial strain and electric field on the electronic and photovoltaic properties of multilayer Sb2Se3 is still unknown. Here, the quantitative relationship, such as strain-property, electric field-property, as well as thickness-property, is explored via first-principles calculations. Our results demonstrate that the band gap and photovoltaic parameters (Jsc, Voc, FF and PCE) of multilayer Sb2Se3 are not only affected by the uniaxial strain and electric field, but can also be tuned via the coupling of thickness with strain and electric field. The band-gap of multilayer Sb2Se3 is linear dependent on uniaxial strain and external electric field. We found that the effect of strain on the photovoltaic parameters could be negligible as compared with the effect of thickness. However, the effect of electric field is thickness dependent, 1 ‒ 2 layer(s) thin films are not affected while the impact of electric field increases with the increasing thickness. The quantitative strain (electric field)-properties relation of multilayer Sb2Se3 suggesting that Sb2Se3 films have a potential application in the field of strain and electric field sensors.

Shear Properties of Cemented Paste Backfill under Low Confining Stress

Cemented paste backfill (CPB) plays an important role in the mining industry due to safety, cost efficiency, and environmental benefits. Studies on CPB have improved the design and application of paste backfill in underground mines. Direct shear is one of the most fundamental parameters for assessing backfill strength. This study harnesses direct shear tests to explore the low confining stress behavior of CPB. We perform all the tests in a standard apparatus on the combination of three binder contents of 4.2%, 6.9%, and 9.7% CPB with four curing times of 3, 7, 14, and 28 days, respectively. The applied confining stress levels vary in a range according to the in situ regime. Results are presented by strength envelope, stress-strain property, and shear strength with curing time and binder content. The data suggest that the shear strength follows the Mohr–Coulomb envelope in which the shear strength and behavior are time and binder content dependent. In addition, the results show that shear strength is strongly related to the binder content than the curing time, namely, the higher the degree of binder hydration, the higher the cementation binding force between CPBs.

Engineering Na+-layer spacings to stabilize Mn-based layered cathodes for sodium-ion batteries

Layered transition metal oxides are the most important cathode materials for Li/Na/K ion batteries. Suppressing undesirable phase transformations during charge-discharge processes is a critical and fundamental challenge towards the rational design of high-performance layered oxide cathodes. Here we report a shale-like NaxMnO2 (S-NMO) electrode that is derived from a simple but effective water-mediated strategy. This strategy expands the Na+ layer spacings of P2-type Na0.67MnO2 and transforms the particles into accordion-like morphology. Therefore, the S-NMO electrode exhibits improved Na+ mobility and near-zero-strain property during charge-discharge processes, which leads to outstanding rate capability (100 mAh g−1 at the operation time of 6 min) and cycling stability (>3000 cycles). In addition, the water-mediated strategy is feasible to other layered sodium oxides and the obtained S-NMO electrode has an excellent tolerance to humidity. This work demonstrates that engineering the spacings of alkali-metal layer is an effective strategy to stabilize the structure of layered transition metal oxides.

High Load Stress-Strain Property of Natural Turf for Professional Use, Various Types of Natural, Hybrid and Artificial Turfs in Football

High load quasi stress-strain (qSS) properties of professionally maintained natural turf (N-pro) was compared with eight natural, hybrid or artificial turfs: one professionally maintained natural turf in a sub field and one grown in a test field without maintenance, two hybrid turfs (one in the sub field and one grown in the test field without maintenance), three new artificial turfs (sand, rubber and sand/rubber infill) and one aged artificial turf (eight years old with sand/rubber infill). N-pro was characterized with a distinctive magnitude of plastic deformation and hysteresis profile, indicating its more energy absorbable properties compared to the artificial turfs. Apparent differences exist between N-pro and other natural turfs, suggesting factors such as daily maintenance work and sod compositions are very influential. Clear differences were also observed when the hybrid turf was professionally maintained. The aged artificial turf becomes substantially stiffer indicating usage over years affects the stiffness.

Supersonic oscillation impact upon aging process of different metal alloys

A short literary review on the super-sound impact upon different alloy aging is shown. The super-sound impact upon aging processes martensite alloys is considered. A super-sonic plant allowing increasing a super-sound impact upon martensite steel aging is developed. There are shown the investigation results of frequency and intensity of sound oscillation upon stress-strain property changes in aging processes.

Dynamic Behavior of PET FRP and Its Preliminary Application in Impact Strengthening of Concrete Columns

Polyethylene terephthalate (PET) fiber has attracted significant attention for reinforced concrete (RC) structure rehabilitation due to its large rupture strain (LRS; more than 7%) characteristic and recyclability from waste plastic bottles. This study presents a dynamic tensile test of PET fiber bundles performed using a drop-weight impact system. Results showed that the tensile strength and the elastic modulus of the PET fiber bundles increased, whereas the failure strain and the toughness decreased with the increasing strain rate from 1/600 to 160 s−1. In addition, the performance of concrete confined with the PET fiber-reinforced polymer (FRP) under impact loading was investigated based on a 75 mm-diameter split Hopkinson pressure bar (SHPB) device and a drop-weight apparatus. For the SHPB test, owing to the large rupture strain property of PET FRP, the PET FRP-confined concrete exhibited significantly better performance under impact loading compared to its counterpart confined with carbon FRPs (CFRPs). During the drop-weight test, the confinement of the PET FRP composites to the concrete columns as external jackets not only improved the peak impact force, but also prolonged the impact process.

Prediction of Cyclic Stress–Strain Property of Steels by Crystal Plasticity Simulations and Machine Learning

In this study, a method for the prediction of cyclic stress–strain properties of ferrite-pearlite steels was proposed. At first, synthetic microstructures were generated based on an anisotropic tessellation from the results of electron backscatter diffraction (EBSD) analyses. Low-cycle fatigue experiments under strain-controlled conditions were conducted in order to calibrate material property parameters for both an anisotropic crystal plasticity and an isotropic J2 model. Numerical finite element simulations were conducted using these synthetic microstructures and material properties based on experimental results, and cyclic stress-strain properties were calculated. Then, two-point correlations of synthetic microstructures were calculated to quantify the microstructures. The microstructure-property dataset was obtained by associating a two-point correlation and calculated cyclic stress-strain property. Machine learning, such as a linear regression model and neural network, was conducted using the dataset. Finally, cyclic stress-strain properties were predicted from the result of EBSD analysis using the obtained machine learning model and were compared with the results of the low-cycle fatigue experiments.