The self-learning kinetic Monte Carlo method has been shown to be suitable for examining the temporal and spatial evolution of adatom islands on the (111) surface of several fcc metals, unbiased by diffusion processes chosen a priori. A pattern-recognition scheme and a diffusion path finder scheme enable collection of a large database of diffusion processes and their energetics. A variety of mechanisms involving single and multiple atoms, and concerted island motion are uncovered in long-time simulations. In this contribution, after reviewing the methodology, we present results comparing the diffusion kinetics of two sets of homo-epitaxial and hetero-epitaxial systems: small (2–8 atom) Pd and Ag islands on the respective (111) surfaces and small Cu islands on Ni(111) and Ni islands on Cu(111). We trace the dominance of concerted motion in Pd/Pd(111) and Ni/Cu(111) and competition among concerted, multiatom and single-atom processes in Ag/Ag(111) and Cu/Ni(111) to the strength of the lateral interaction among adatoms in these systems.

ZnAl–Zr(X) hydrotalcite-like materials were synthesized by co-precipitation using a Zn/Al molar ratio of 2 and Zr/Al(X) molar ratios of 0.0, 0.10, and 0.25. The effect of the activation temperature on the catalytic performance of these materials was analyzed, revealing that at relatively low temperature (200 °C), the collapse of the material structure is diminished, leading to FAME yields varying from 68 to 82%. This remarkable catalytic activity is related to the formation of hydrotalcite, zincite, and hydrozincite which in turn lead to the generation of Brönsted basic sites and Lewis acid–basic pairs. Incorporation of Zr+4 into the brucite-like structure of hydrotalcites enhances the basicity of ZnAl–Zr(X) catalysts, which correlates well with the increase in catalytic activity observed for these catalysts. The stability of the ZnAl–Zr(0.25) catalyst was further studied, showing insignificant deactivation after five subsequent reaction cycles. A simplified reaction scheme was proposed for the transesterification reaction over these materials.

The transition metal compound catalysts have been taken a great part in renewable energy conversion and storage systems. Herein, we report the uniform CoFe2O4 nanoparticles with abundant oxygen vacancies and specific active surface exposed through the simple hydrothermal reaction for improving the electrocatalytic performance and stability. They show good electrocatalytic performance for hydrogen evolution reaction in 0.5 M H2SO4 with an onset potential of 20 mV, the overpotential of 45 mV (at j = 10 mA/cm2), and remarkable long-term stability more than 100 h at different current densities and better oxygen reduction reaction activity with lower overpotential in 0.1 M KOH. Moreover, the home-made primary Zn–air batteries, using CoFe2O4 nanoparticles as an air–cathode display the high open-circuit voltage of 1.47 V and the maximum power density of 142 mW/cm2. The two-series-connected batteries fabricated by CoFe2O4 nanoparticles can support a light-emitting diode to work for more than 48 h.

This work is part of the interlaboratory collaboration to study the stability of organic solar cells containing PCDTBT polymer as a donor material. The varieties of the OPV devices with different device architectures, electrode materials, encapsulation, and device dimensions were prepared by seven research laboratories. Sets of identical devices were aged according to four different protocols: shelf lifetime, laboratory weathering under simulated illumination at ambient temperature, laboratory weathering under simulated illumination, and elevated temperature (65 °C) and daylight outdoor weathering under sunlight. The results generated in this study allow us to outline several general conclusions related to PCDTBT-based bulk heterojunction (BHJ) solar cells. The results herein reported can be considered as practical guidance for the realization of stabilization approaches in BHJ solar cells containing PCDTBT.

The powder thixoforming method was used to fabricate 10 vol% silicon carbide particle (SiCp) reinforced 6061 Al matrix composites with high mechanical performances successfully. Here, we demonstrated with proof that proper solution treatment could not only enhance tensile strength of the composite: its ultimate tensile strength and yield strength increased from 230 to 128 MPa in the as-fabricated state to 275 and 212 MPa solutionized at 808 K for 6 h but also improve composite’s tensile elongation significantly with an increment of 161.5% from 2.6% to 6.8%. Corresponding toughening mechanisms are mainly investigated from the perspective of both microstructure examination and total strain to failure calculation through a modified model. The theoretical predictions are in reasonably good agreement with the experimental data. This work may provide a practical way to alleviate the inverse strength–ductility relationship of particulate reinforced metal matrix composites and provide reference for the SF calculation of similar composites subjected to solution treatment.

The microstructure of In(As,Bi)/GaAs heterostructures grown by low-temperature molecular beam epitaxy with special attention to the interfaces was studied by scanning/transmission electron microscopy, energy dispersive X-ray microanalysis, and X-ray diffraction and reflectivity. Two samples grown at similar conditions with and without the presence of the Bi-contained layer, formed at 350 °C, are considered. These samples were jointly analyzed to clarify Bi influence on the crystal structure. Two types of QD-like clusters at the GaAs/In(As,Bi) interface were found. The first type exhibited a zinc blend crystal structure, which is typical for A3B5 semiconductors. The second type adopted a tetragonal PbO crystal structure and was found in different orientations. The joint analysis by electron microscopy and X-ray methods demonstrated that the incorporation of Bi atoms into the InAs layer leads to the strain relaxation at the interface in the growth direction. According to electron microscopy data, this strain release is more pronounced around the clusters of the second type.

The indentation response of a 3D noninterlaced composite comprising three sets of orthogonal carbon-fibre tows in an epoxy matrix is investigated. The 3D composites have a near isotropic and ductile indentation response. The deformation mode includes the formation of multiple kinks in the tows aligned with the indentation direction and shearing of the orthogonally oriented tows. Finite element (FE) calculations are also reported wherein tows in one direction are explicitly modeled with the other two sets of orthogonal tows and the matrix pockets treated as an effective homogenous medium. The calculations capture the indentation response in the direction of the explicitly modeled tows with excellent fidelity but under-predict the indentation strength in the other directions. In contrast to anisotropic and brittle laminated composites, 3D noninterlaced composites have a near isotropic and ductile indentation response making them strong candidates for application as materials to resist impact loading.

The multiplication of dislocations determines the trajectories of microstructure evolution during plastic deformation. It has been recognized that the dislocation storage and the deformation-driven subgrain formation are correlated—the principle of similitude, where the dislocation density (ρi) scales self-similarly with the subgrain size (δ): $\delta \sqrt {{\rho _{\rm{i}}}}$ ∼ constant. Here, the robustness of this concept in Cu is probed utilizing large strain machining across a swathe of severe shear deformation conditions—strains in the range 1–10 and strain-rates 10–103/s. Deformation strain, strain-rate, and temperature characterizations are juxtaposed with electron microscopy, and dislocation densities are measured by quantification of broadening of X-ray diffraction peaks of crystallographic planes. We parameterize the variation of dislocation density as a function of strain and a rate parameter R, a function of strain-rate, temperature, and material constants. We confirm the preservation of similitude between dislocation density and the subgrain structure across orders-of-magnitude of thermomechanical conditions.

This work was aimed to use the peak separation method to directly measure the critical temperatures and phase transition fractions of austenite decomposition products based on experimental dilatometric curves in hypo-eutectoid steels. The results indicated that pearlite transformation start temperature and ferrite transformation finish temperature could be clearly obtained through peak separation processing, which were generally hidden in the overlapped peaks of the linear thermal expansion coefficient curve. Moreover, four critical temperatures of austenite decomposition were retarded to lower temperature with cooling rate increasing. The phase transition fraction for austenite decomposition was quantitated by measuring the area of the corresponding phase transformation peak. The final ferrite phase fraction after austenite decomposition decreased with cooling rate increasing. On the contrary, the final pearlite phase fraction increased with cooling rate increasing. Compared with the lever rule, the calculation result using peak area method can accurately reflect the actual phase fraction change versus the temperature during austenite decomposition.

An Al–3% B master alloy has been subjected to equal channel angular pressing (ECAP). The grain refining performance and fading resistance of an Al–3% B master alloy on a commercial purity Al (CPA) have been evaluated. The effect of the number of ECAP passes on the size and the distribution of the AlB2 particles, the grain size of CPA ingots with and without adding the Al–3% B master alloy subjected to ECAP have been investigated. The mean size of AlB2 particles was significantly reduced from ∼34 to ∼12 μm after four ECAP passes. Fine blocky AlB2 particles were uniformly distributed in the Al matrix. It has been revealed that when it was inoculated by the Al–B master alloy subjected to ECAP, the grain size of α-Al was decreased from ∼1200 to ∼180 μm after four ECAP passes, beyond that, the grain size tends to be saturated. It has been proved that grain refinement efficiency and fading resistance of the Al–3% B master alloy subjected to ECAP in CPA ingots was enhanced.

Transient transmission oscillations in X-cut and Z-cut congruent, iron-doped, and magnesium-doped lithium niobate samples were measured using 50 fs, 800 nm, 0.5 nJ pulses from a self-mode-locked Ti:sapphire laser in an optical pump–probe system. Several Raman-active oscillation modes excited by these pulses were observed as changes in the transmitted probe intensity versus time delay between the pump and probe pulses. The samples were rotated to determine how the incident polarization of the pump pulses affects the mode excitations. The observed Raman-active oscillations correspond to previously reported symmetry modes measured with traditional, continuous-wave, Raman spectroscopy using the same scattering geometry. In addition, a polariton mode and other, previously unreported, lower-frequency modes were observed in each of the samples. The transmission intensity data for each sample were fit successfully to a superposition of sinusoidal functions with exponentially decaying amplitudes.

The effects of the thermal cyclic aging treatment on the microstructure and mechanical properties of 2060 Al–Li alloy laser beam welded joints were investigated. Aging treatments were conducted at different temperatures and for different cycles. Test results showed that the tensile strength of the weld joints increased and the elongation slightly decreased after the thermal cycling treatment. It was also found that the heat affected zone (HAZ) of the welds exhibited a significant increase in microhardness, whilst the microhardness variation of the nondendrite equiaxed zone (EQZ) can be neglected. The strengthening effect of the thermal cycling became more obvious as the temperature and cycles increased. The highest strength of around 513 MPa (96% of the base metal) was obtained at the temperature of 180 °C. Reprecipitation of strengthening phases such as T1 in the HAZ at 180 °C was observed by TEM, which can be considered as the main reason for the strengthening effect of the aging treatment.

Si nanoparticles and multi-walled carbon nanotubes (MWNTs) were combined using the simple, inexpensive, and scalable approach involving ultrasonication and positive-pressure filtration to generate binder-free freestanding flexible Si–MWNT (Si–MW) composite paper anodes for Li-ion batteries. Through controlling the Si/carbon nanotube (CNT) weight ratio, the composite with 3:2 Si/CNT ratio exhibited the optimal balance between the high capacity of SiNPs and high conductivity and structural stabilization quality of MWNTs, leading to high rate capability as well as specific capacity and cyclability surpassing the conventional slurry-cast SiNP electrode using binder and current collector and other complicated freestanding Si/carbon composite designs. After 100 cycles, our electrode retained a capacity of 1170 mA h/g at 100 mA/g and 750 mA h/g at 500 mA/g. Moreover, a different electrolyte composition enabled a reversible capacity of 1300 mA h/g at 100 mA/g after 100 cycles. The freestanding feature of our electrodes is promising for enhanced energy density of Li-ion cells.

The Fe–18.6% Ga alloy (at.%) has a high magnetostriction and an excellent piezomagnetic (PZM) property. However, Fe–Ga has a poor ductility and the addition of B helps to improve this property. The magnetostriction of the Fe–Ga alloy is not appreciably improved by the addition of B; however, the PZM behavior of Fe–Ga–B is unknown up to now. Then, an Fe–Ga alloy with 2% of B was produced to evaluate the effect of boron addition on the PZM property of the Fe–Ga alloy. The PZM force sensing performance coefficient d33* decreased, but the maximum sensitivity is reached for a fixed magnetic field. In addition, d33* values are among 2 and 5 mT/MPa, which is sufficient for many applications. A better ductility compared to Fe–Ga and a good sensitivity at constant field, makes the alloy Fe–Ga–B a good candidate for application as force sensors up to stresses of 80 MPa.

Subsurface microstructure alteration has been a major concern to implement micromachining of titanium alloy in the high-tech industry. To quantitatively promulgate the underlying mechanisms of this alteration, a discrete dislocation dynamics-based model is proposed and used to simulate the subsurface defects and their evolution under different cutting conditions. The model considers the subsurface dislocation configuration and inner stress distribution during the orthogonal cutting of titanium alloy. The results show that subsurface defect structure consists of plenty of dislocation dipoles, twining dislocation bands, and refined grains after cutting. In the primary shear zone, two different characteristics of subsurface damage layers can be found, the near-surface damage layer and deep-surface damage layer, which have different structural natures and distribution features. Moreover, it is found that high cutting speed and small depth of the cut can suppress the formation and propagation of subsurface defects. A powerful inner stress state would promote the distortion of the lattice and result in a microcrack within the subsurface matrix. The simulation results have been compared with experimental findings on the machined surface and subsurface of similar materials, and strong similarities were revealed and discussed.

The layer-by-layer self-assembly technology was adopted to prepare a new generation of supercapacitor electrode material, GOQDs@NiAl-LDH, between Ni–Al layered double hydroxide (LDH) and graphene oxide quantum dots (GOQDs). First, Ni–Al LDH was prepared by coprecipitation of nickel nitrate and aluminum nitrate and then delaminated by ultrasonication. Second, NiAl-LDH was combined with GOQDs that were prepared by a ball milling reaction using hexachlorobenzene as raw material. The electrochemical data indicate that the composite (OGL9) exhibits highest specific capacitance, large current charge and discharge characteristics, and excellent cycle stability when the content of GOQDs is 10%. And the specific capacitance of composite reaches to 869 F/g at the current density of 1 A/g. Moreover, the capacitance retention at 1 A/g discharge current condition is 69.6% after 2000 cycles. And the results indicate that the OGL9 can be a promising electrode material for supercapacitor applications.

In this paper, mechanical characteristics of the aluminum layer coated with graphene are investigated by performing numerical tensile experiments through classical molecular dynamics simulations. Based on the results of the simulations, it is shown that coating with graphene enhances the Young’s modulus of aluminum by 88% while changing the tensile behavior of aluminum with hardening–softening mechanisms and significantly increased toughness. Furthermore, the effect of loading rate is examined and a transformation to an amorphous phase is observed in the coated aluminum structure as the loading rate is increased. Even though the dominant component of the coated hybrid structure is the aluminum core in the elastic region, the graphene layer shows its effects majorly in the plastic region by a 60% increase in the ultimate tensile strength. High loading rates at room temperature cause the structure transforms to an amorphous phase, as expected. Thus, effects of loading rate and temperature on amorphization are investigated by performing the same simulations at different strain rates and temperatures (i.e., 0, 300, and 600 K).

NiO nanoparticles (NPs) were synthesized at different annealing temperatures via a thermal decomposition process and characterized using X-ray diffraction, scanning electron microscopy, and UV-vis spectroscopy. The NiO NPs prepared at higher annealing temperature (400 °C) were shown excellent adsorption and photocatalytic activity toward textile dyes reactive black 5 (RB-5) and methylene blue (MB). About 87.2% of RB-5 in 60 min and 70.2% of MB in 5 h was removed using NiO NPs synthesized at 400 °C. The photocatalytic degradation of MB was found to increase with an increase in the annealing temperature of the catalyst. Moreover, the kinetic study revealed that the adsorption and photocatalytic activity of NiO NPs followed the second and first-order kinetics, respectively. The enhanced performance of NiO NPs toward dye removal might be related to its optical and structural properties.