The incorporation of small amounts of phenolic antioxidants, such as 2,6-di-tert-butyl-4-cresol and pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], into photovoltaic organo-lead halide perovskite layers significantly suppressed the degradation of the perovskite compounds via light irradiation in the presence of ambient oxygen. While the facile incorporation of the antioxidants did not decrease both the quality of the formed perovskite crystal grains and the photovoltaic conversion performance of the cells, it enhanced the antioxidizing property and water repellency of the perovskite layer owing to the elimination of superoxide anion radical and hydrophobic molecular structure and improved the durability of the cells.

Twin–twin interactions (TTIs) take place when multiple twinning modes and/or twin variants are activated and interact with each other. Twin–twin junctions (TTJs) form and affect subsequent twinning/detwinning and dislocation slip, which is particularly important in determining mechanical behavior of hexagonal metals because twinning is one major deformation mode. Atomic-level study, including crystallographic analysis, transmission electronic microscopy (TEM), and molecular dynamics (MD) simulations, can provide insights into understanding the process of TTIs and structural characters associated with TTJs. Crystallographic analysis enables the classification of TTIs and the prediction of possible interfaces of twin–twin boundaries (TTBs), characters of boundary dislocations, and possible reactions of twinning dislocations and lattice dislocations at TTBs. MD simulations can explore the process of TTIs, microstructures of TTJs, atomic structures of TTBs, and stress fields associated with TTJs. The predictions based on crystallographic analysis and the findings from MD can be partially verified by TEM. More importantly, these results provide explanation for microstructural characters of TTJs and guidance for further TEM characterizations.

Reduced graphene oxide supported titanium dioxide (GO/TiO2) heterojunction composites as highly active photocatalysts were synthesized via simple ultrasonic mixing and hydrothermal reaction using TiCl3 and GO as precursors. Their structure and morphology were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, Raman spectra, UV-vis spectroscopy, and thermogravimetic analysis. The GO/TiO2 heterojunction composites were used to degrade methyl orange (MO). The adsorption and photocatalytic degradation rate of the prepared GO/TiO2 composites increased by nearly three times compared with that of pristine TiO2 or GO, which reached up 90%, to degrade MO after 4 h, which provides a simple method to obtain photocatalytic materials.

Ab initio calculations are performed to investigate the structural, vibrational, electronic, and piezoelectric properties of functionalized single layers of TaS2. We find that single-layer TaS2 is a suitable host material for functionalization via fluorination and hydrogenation. The one-side fluorinated (FTaS2) and hydrogenated (HTaS2) single layers display indirect gap semiconducting behavior in contrast to bare metallic TaS2. On the other hand, it is shown that as both surfaces of TaS2 are saturated anti-symmetrically, the formed Janus structure is a dynamically stable metallic single layer. In addition, it is revealed that out-of-plane piezoelectricity is created in all anti-symmetric structures. Furthermore, the Janus-type single-layer has the highest specific heat capacity to which longitudinal and transverse acoustical phonon modes have contribution at low temperatures. Our findings indicate that single-layer TaS2 is suitable for functionalization via H and F atoms that the formed, anti-symmetric structures display distinctive electronic, vibrational, and piezoelectric properties.

BaxSr(1−x)TiO3 (BST) thin films were fabricated on a Ti substrate using micro-arc oxidation (MAO) in an aqueous solution with the addition of 0.6 M Ba(OH)2, 0.4 M Sr(OH)2, and 0.05 M EDTA. The morphology, composition, and electrical properties of BST films prepared under different processing times were characterized, and MAO growth characteristics of BST films were discussed. Results indicate that dielectric and ferroelectric properties of BST films are positively correlated with surface morphology dependent on MAO spark patterns. To obtain a smooth and compact film, the large spark stage should be avoided. During MAO processes, elements from the substrate and electrolyte solution migrate in opposite directions under an electric field, resulting in Ba, Sr, Ti, and O elements exhibiting a gradient distribution between the BST film and the Ti substrate. BST film prepared using MAO is composed of two layers: an outer loose layer and an inner dense layer. In addition, because of the position of discharge breakdown continually changing, the interface between the film and the substrate is uneven. As MAO processing time increases, BST film thickness increases and ferroelectric property improves. When processing time is 15 min, the residual polarization intensity (2Pr) of the BST film is about 4.9 μC/cm2.

In this work, a facile superhydrophobic coating for 2024-T3 aluminum alloy is developed and characterized. The corrosion resistance of the coating was analyzed. The results showed that the coating has high polarization resistance and a low corrosion rate. Furthermore, a micro/nanoscale investigation about the interaction between substrates and the corrosive environment was carried out using the in situ atomic force microscope technique. The change in surface topography was monitored for both the bare aluminum alloy substrate and the superhydrophobic aluminum alloy. The results showed that the coating retained surface features indicated that the coating has excellent corrosion resistance.

In the present work, an efficient route has been further explored to achieve the batch synthesis of inorganic fullerene (IF)-WS2 nanoparticles, and the self-lubricating film is conveniently prepared by coating these nanoparticles on the surface of metal substrates. The as-synthesized IF-WS2 nanoparticles have a closed hollow structure with an average particle size of about 50 nm and are evenly distributed in the self-lubricating film. Further friction tests show that the film has excellent friction properties, with its lowest friction coefficient of approximately 0.008, which can be mainly attributed to the unique hollow cage structure and a smaller particle size of the IF-WS2 nanoparticles.

Impedance spectroscopy was conducted on colloidal ITO thin films that had been subjected to alternating oxygen and argon plasma treatments, followed by air annealing from 150 to 750 °C. An equivalent circuit consisting of an RC element nested within another RC element, featuring a negative resistance and a negative capacitance, fitted the data well. These results are interpreted as being due to surface plasmons that are a function of the presence of nanoporous ITO-rich regions surrounded by isolated ITO nanoparticles coated with an amorphous polymer that intertwines with the ITO-rich regions as a function of annealing treatment.

The quality of the polymer raw material used in plastic processing methods is an important characteristic because it is one of the main factors in producing quality products. Therefore, the characterization of polymeric pellets in the polymer processing industry is very important to avoid using inferior materials. In general, differences in the interiors of polymeric pellets reflect differences in their densities. In this study, a high-sensitivity magnetic levitation method was used to characterize the polymeric pellets in four different occasions. The device used has a high sensitivity that can distinguish minute differences as small as of 0.0041 g/cm3 in density between different samples. In addition, the method can obtain a sample's density without knowing the weight and volume of the sample. This method can be used to characterize materials by testing only a single pellet, which is very useful for polymeric pellet characterization.

Severe cracking and unsatisfied mechanical performance are the major challenges of manufacturing titanium aluminide (TiAl) components by selective laser melting (SLM). In this work, graphene oxide (GO) sheets were introduced onto the metal powder surface to improve the manufacturability of SLM of a Ti–48Al–2Cr–2Nb (at.%) alloy and enhance the mechanical strength of the laser-fabricated parts. The effect of laser power and GO content on the macromorphology of single-track processing was investigated, showing that the crack-free track could be obtained with the addition of 0.1–0.5 wt.% GO under a laser power of 110 W. In addition, the characterization of multilayer buildups via electron backscatter diffraction and backscatter electron imaging reveals the grain refinement during SLM of GO/TiAl nanocomposites. Finally, the strength of the as-built samples was examined using micro-hardness test, showing a maximal increase of 21.9% by adding 0.3 wt.% GO into the TiAl powders from laser-fabricated samples without GO.

A novel approach is utilized to investigate the deformation mechanisms at the microstructural level in 3D-printed alloys. The complex formation methods leave a unique and complicated microstructure in the as-built 3D-printed alloys. The microstructure is three leveled, composed of meltpools, grains, and cells. Deformation mechanisms in this microstructure are still highly unexplored due to the complexities of analysis at this scale. To understand these, we establish an image processing framework that converts scanning electron microscope (SEM) images directly into models that are scaled up and 3D printed with representative stiff and soft materials for the proposed material types within the body. These bodies are loaded in uniaxial tension with digital image correlation to study the strain gradient and stress delocalization as a result of the microstructure. The same models were tested through Finite Element Analysis (FEA) with materials similar to reality. Our testing shows the hierarchical material distribution leads to an increased damage tolerance.

Dark-field x-ray microscopy is intended for the acquisition of three -dimensional (3D) movies of the nanostructure (grains, domains, and dislocations) and the associated local strain within bulk materials. It is analogous to dark-field electron microscopy in that an objective lens magnifies diffracting features of the sample. The use of high-energy synchrotron x-rays, however, means that these microstructural features can be large and deeply embedded. The spatial and angular resolution is on the order of 100 nm and 0.001°, respectively, and full maps can be recorded in seconds to minutes. Four applications of the technique are presented—domain switching in ferroelectrics, processing of metals, microstructural characterization of biominerals, and visualization of dislocations. The ability to directly characterize complex, multiscale phenomena in situ—and in 3D—is a key step toward formulating and validating multiscale models that account for the entire heterogeneity of materials.