TiAlN, CrAlN films and alternate CrAlN/TiAlN multilayers with different repeated bilayer thickness ranging from 10 to 30 nm were prepared by reactive magnetron sputtering. The interface structures of the films were characterized using x-ray reflectometry method. The individual thickness of the repeated bilayers in multilayers and total thickness of the films are close to the nominal thickness and they are more accurate for thicker films. The interface roughness increases as the thickness of the repeated bilayer in mutilayers decreases. The scattering length density profiles of the films suggests that the chemical composition is more accurate for thicker films.

The Cu2O homojunction was formed by epitaxially growing a manganese-doped Cu2O (Cu2O:Mn) thin film on thermally oxidized polycrystalline p-type sodium-doped Cu2O (p-Cu2O:Na) sheets by electrochemical deposition. A significant improvement of photovoltaic properties was achieved in solar cells fabricated by inserting a Cu2O:Mn thin film between an Al-doped ZnO (AZO) transparent electrode and p-Cu2O:Na sheets. The photovoltaic properties obtained in AZO/Cu2O:Mn/p-Cu2O:Na solar cells were controlled by changing the Mn content doped into the Cu2O:Mn thin film. An efficiency of 4.21% was obtained in an AZO/Cu2O:Mn/p-Cu2O:Na solar cell fabricated with a Cu2O:Mn thin film that was identified as an i-type semiconductor.

Heterostructures consisting of two ferromagnetic oxides La0.7Ca0.3MnO3 (LCMO) and SrRuO3 (SRO) were epitaxially grown by pulsed laser deposition onto a silicon (Si) substrate buffered by SrTiO3 (STO)/MgO/TiN. The x-ray scans and electron-diffraction patterns reveal the epitaxial nature of all five layers. From transmission electron microscopy, the thicknesses of the LCMO and SRO layers were estimated to be ~100 and ~200 nm, respectively. The magnetic properties of individual SRO and LCMO layers are in good agreement with the previous studies reported for those individual layers deposited on lattice-matched substrates, such as STO. The LCMO/SRO heterostructures showed enhanced switching field (from 6008 to 7600 Oe), which may originate from the bulk part of the heterostructure. The ability to grow these multifunctional structures on Si provides a route for wafer scale integration with Si, in contrast to oxide substrates that are not suitable for CMOS integration for microelectronics and spintronics applications.

Nickel–molybdenum (Ni–Mo) materials are widely used functional oxide catalysts for the hydrogen evolution reaction. In this work, we investigate the high activity of Ni–Mo by depositing size-controlled Ni nanocrystals (NCs) onto Mo substrates. We observe a synergistic increase in catalytic activity that does not scale with the Ni–Mo interface length. This evidence points to a bulk electronic interaction of the two metals that is separate from the mechanism of enhancement seen in conventionally co-deposited Ni–Mo electrocatalysts. In addition to elucidating the catalytic behavior of the Ni–Mo system, this work offers a general NC-based paradigm for investigating fundamental interactions and synergistic effects in electrocatalytic materials.

In-doped tin (II) sulfide nanoparticles (NPs), synthesized by ultrasonication method and their optical and photovoltaic properties, have been investigated. FESEM images show NPs which have a flower-like morphology that sizes are <100 nm. Optical energy band gap estimation of tin sulfide NPs with the Tauc plot method had shown an increase with minimum of indium concentration and then decreases with higher concentration of indium. Photovoltaic experiment shows the highly photovoltaic efficiency of tin sulfide NPs with indium doping, can be obtained.

We demonstrate formation of allylamine (AAm) and acrylic acid (AAc)-functionalized colloidal silicon nanocrystals (Si NCs) exhibiting near-infrared (NIR) luminescence and immobilization of the NCs on substrates via covalent bond. The surface functionalization is confirmed by IR absorption spectroscopy and specific binding property of functionalized NCs. Atomic force microscope observations reveal that AAm- and AAc-functionalized Si NCs are chemically immobilized on self-assembled monolayers via covalent bonds. The functionalized Si NCs exhibit photoluminescence in a NIR region (1.5–1.6 eV), which is not significantly affected by the functionalization.

This paper reviews progress in ultraviolet (UV) optoelectronic devices based on AlGaN films and their quantum wells (QWs), grown by plasma-assisted molecular beam epitaxy. A growth mode, leading to band-structure potential fluctuations and resulting in AlGaN multiple QWs with internal quantum efficiency as high as 68%, is discussed. Atomic ordering in these alloys, which is different from that observed in traditional III–V alloys, and its effect on device performance is also addressed. Finally, progress in UV-light-emitting diodes, UV lasers, UV detectors, electroabsorption modulators, and distributed Bragg reflectors is presented.

When two materials interact, the processes between the phases determine the functional properties of the compound. Pivotal interface phenomena are diffusion and redistribution of atoms (molecules). This is especially of interest in Lithium ion batteries where the interfacial kinetics determines the battery performance and impact cycling stability. A new phase field model, which links the atomistic processes at the interface to the mesoscale transport by a redistribution flux controlled by the so called ‘interface permeability’ was developed. The model was validated with experimental data from diffusion couples. Calculations of the concentration profiles of the species at the electrode–electrolyte interface are reported. Active particle size, morphology and spatial arrangement were put in correlation with diffusion behavior for use in reverse engineering.

Dual-coated barium titanate (BT) particles were prepared using dopamine (DP) in conjunction with bromine (Br) in order to enhance the dielectric constant of silicone rubber (SR) composites containing evenly distributed BT particles. The results showed that both DP and Br were deposited on the BT particles. The dielectric constant of the SR/BT composite was significantly increased from 3.6 to 4.7 at 1 kHz with the addition of BT modified with dopamine (DP–BT). Moreover, the dielectric constant further rose to 4.9 at 1 kHz when the DP–BT particle was grafted with bromine (Br–DP–BT).

We report the effect of patterning on photoelectrochemical (PEC) water-splitting performance. Oxide–oxide heterostructures based on horizontal and vertical heterojunctions were fabricated on transparent conductive oxide glass by sequential plasma enhanced chemical vapor deposition (PECVD) of individual metal oxide. Featured masks were employed to enable three-dimensional patternings of stripes and cross-bars structures formed by Fe2O3 and TiO2 layers. PEC measurement was carried out by a three-electrode cell. It was found that double layered TiO2//Fe2O3:FTO showed a decrease in PEC performance when compared with single Fe2O3:FTO layer, whereas triple-layered Fe2O3//TiO2//Fe2O3:FTO (both patterned and unpatterned samples) displayed enhanced photocurrent density. The results show that the existence of multiple phase boundaries does not always add up to PEC enhancement observed in single heterojunction.

We analyze phosphorus (P)- and boron (B)-doped silicon nanocrystals (Si NCs) with various compositions of silicon-rich oxide using atom probe tomography. By creating Si iso-concentration surfaces, it is confirmed that there are two types of Si NC networks depending on the amount of excess Si. A proximity histogram shows that P prefers to locate inside the Si NCs, whereas B is more likely to reside outside the Si NCs. We discuss the difference in a preferential location between P and B by a segregation coefficient.

Axial compression was conducted on micro-pillars, in which polycrystalline Cu thin films were sandwiched between CrN and Si. Plastic flow of Cu was achieved, when the Cu films are inclined either at 90° or 45° with respect to the pillar axis. The texture of Cu films was altered by changing the template on which film growth occurred. The Cu microstructure was further altered by post-deposition annealing. The flow stress shows little dependence on the film texture in the as-deposited state. However, annealing influences the flow stress of confined Cu films significantly. The implications on strain gradient plasticity models are discussed.

The synergistic effects of the template [Pluronic-123 (P123)] and the silica source [tetraethoxysilane (TEOS)] concentrations on the SBA-15 mesoporous silica morphology were investigated through adjusting the system initial solution volume with the same amounts of silica source and template. It found interestingly that the SBA-15 morphology changed from the hexagonal plate-like shape to the gear-like shape with the decrease of the P123 and TEOS concentration. Based on the morphology variations, the growth of the gear-like morphology was speculated to be formed through the preferential growth at the corner and the layer-by-layer growth in the end face of the ordinary hexagonal plate-like particle.

By solving the problems in the previous pragmatic method [Scr. Mater.90–91, 53–56 (2014)] and including the interdiffusion flux as the criteria, an augmented numerical inverse method was proposed and realized in a house-made code. The proposed augmented numerical inverse method was successfully applied to high-throughput determination of the composition-dependent interdiffusivities in different solid solution alloys ranging from binary, ternary to multicomponent systems by using a single diffusion couple. Moreover, the advance features of the augmented numerical inverse method were also demonstrated.

The origin of ionic conductivity in bulk lithium lanthanum titanate, a promising solid electrolyte for Li-ion batteries, has long been under debate, with experiments showing lower conductivity than predictions. Using first-principles-based calculations, we find that experimentally observed type I boundaries are more stable compared with the type II grain boundaries, consistent with their observed relative abundance. Grain boundary stability appears to strongly anti-correlate with the field strength as well as the spatial extent of the space charge region. Ion migration is faster along type II grain boundaries than across, consistent with recent experiments of increased conductivity when type II densities were increased.

In this study, “within the environment” and “within the contact” in situ tribology techniques are combined in order to study the interfacial processes in lubricated metallic (i.e., aluminum-based) sliding conditions. The evolution of the roughness follows the trend of the coefficient of friction closely, with initially low values followed by higher roughness during steady state. Similarly, the transfer film behavior correlates well with the roughness of the worn surfaces and the subsurface microstructure of the worn surfaces. The effect of normal load on the running-in behavior is also studied in terms of differences in the interfacial processes.

Machinable mica glass ceramics were synthesized by sintering method. The crystal phase was characterized using x-ray diffraction, showing that the main crystal phase was fluorophlogopite. Mechanical properties were measured at different temperatures. The results demonstrated that bending strength and fracture toughness increased 28% and 24% when temperature decreased from 300 to 77 K, respectively. Compressive strength also increased at cryogenic temperatures, but a higher value was obtained at 195 K. According to scanning electron microscope observation, the extraction of mica platelets was observed at 77 K, which may be the toughening mechanism of machinable mica glass ceramics.