Electrochemical technologies promise to provide the means for electrical energy storage of electricity generated from wind, solar, or nuclear energies. The challenge is to provide this storage in rechargeable batteries or clean fuels at a cost that is competitive with fossil fuels for replacement: (1) of vehicles powered by the internal combustion engine by electric vehicles and (2) of centralized power plants using intermittent electricity generated by wind and solar energy or constant electricity from a nuclear power plant, all serving a variable demand. This perspective outlines existing and possible lines of materials research for the development of rechargeable batteries or the production of clean fuels within the constraints of electrochemical technology.

CuInS2 (CIS) quantum dots (QDs) with different diameters were prepared and their optical properties were studied. The optical band gap of QDs, as estimated by absorption spectrum, was found to decrease with increase in size. The stokes shift between absorption and photoluminescence peaks was observed to be larger (>100 meV) in all the three samples. This shows that the defect states available in the forbidden gap dominates the recombination mechanism. The variation in the emission peak with QD size, however, indicates that the relaxation dynamics in CIS QDs involves both excitonic level as well as the defect states.

Monotonic and cyclic tension–tension tests with an upper stress in the GPa regime have been performed on Cu–Si nanowires. The results show that the exceptional high strength of these nanomaterials is maintained or even improved upon cyclic loading. Post-mortem transmission electron microscopy gives insight in the microstructural evolution. Fatigue-induced grain growth correlates with an observed increase in compliance, the formation of dislocation networks, and an increase in tensile strength.

Self-assembled vertical heteroepitaxial nanostructures (VHN) in the complex oxide field have fascinated scientists for decades because they provide degrees of freedom to explore in condensed matter physics and design-coupled multifunctionlities. Recently, of particular interest is the perovskite-spinel-based VHN, covering a wide spectrum of promising applications. In this review, fabrication of VHN, their growth mechanism, control, and resulting novel multifunctionalities are discussed thoroughly, providing researchers a comprehensive blueprint to construct promising VHN. Following the fabrication section, the state-of-the-art design concepts for multifunctionalities are proposed and reviewed by suitable examples. By summarizing the outlook of this field, we are excitedly expecting this field to rise with significant contributions ranging from scientific value to practical applications in the foreseeable future.

The magnetic properties of Sr3SnO (SSO) epitaxial thin films prepared under various post-growth annealing treatments are reported. The SSO films are grown on cubic yttria-stabilized zirconia Si (001) platform by pulsed laser deposition. Post-growth vacuum annealing is found to enhance the room-temperature ferromagnetism (RTFM), whereas oxygen annealing reduces it. The results are explained through the oxygen vacancy constituted bound magnetic polarons (BMP) model. An empirical relationship between the extracted BMP concentration and the oxygen vacancy concentration is shown using X-ray photoelectron spectroscopy data. The results indicate a promising way to tune RTFM by manipulating oxygen vacancies and related defects.

Some of the stable isotopes of silicon and carbon have zero nuclear spin, whereas many of the other elements that constitute semiconductors consist entirely of stable isotopes that have nuclear spins. Silicon and diamond crystals composed of nuclear-spin-free stable isotopes (28Si, 30Si, or 12C) are considered to be ideal host matrixes to place spin quantum bits (qubits) for quantum-computing and -sensing applications, because their coherent properties are not disrupted thanks to the absence of host nuclear spins. The present paper describes the state-of-the-art and future perspective of silicon and diamond isotope engineering for development of quantum information-processing devices.

Spherical and conical nanoindentation experiments were performed for the same polymer specimens to compare Young's moduli measured from the elastic loading and unloading curves, and bending experiments. Finite-element simulation was employed to ensure pure elastic deformation during spherical nanoindentation. The moduli measured from the elastic loading curves using Hertz's contact law are very close to the bending moduli, because both measurements were conducted under the same elastic deformation. However, the moduli measured from the elastic unloading curves are up to 60% higher than the bending moduli owing to plastic deformation close to the sharp conical indenter tip.

The optoelectronic and thermal properties of conjugated polymers are frequently tuned via direct synthetic modification of the conjugated repeat unit. It is also well known that these properties are inherently tied to the crystal structure, a factor which is difficult to predict upon slight chemical modification. We show that the crystal structure of random copolymers of 3-alkylthiophenes can be controlled, which in turn affects the optoelectronic properties. Furthermore, we show that the melting transitions smoothly vary between that of the two homopolymers. As such, the composition of copolymers is a convenient handle to predictably control the thermal properties, crystalline morphology, and optoelectronic properties simultaneously.

Robust superhydrophobic surfaces can improve the performance of various applications. Considerable research has focused on developing superhydrophobic surfaces, but in these studies, superhydrophobicity was attained using polymeric materials, which deteriorate under harsh environments. Recently, it has been shown that rare-earth oxide ceramics are hydrophobic and since they are ceramics, they withstand harsh environments including high temperature. Here we fabricate a superhydrophobic surface by texturing a ceria pellet using laser ablation. We demonstrate water repellency by showing an impinging water droplet bouncing off the surface. This study extends the possibility of producing robust superhydrophobic ceramics using accessible techniques for industrial applications.

The paper describes a new technique of molten salt synthesis (MSS) that is based on the direct oxidation of halide ions with molecular oxygen in thermally stable halide melts to prepare nanoparticles of complex oxides. Lithium cobaltate (LiCoO2) was chosen as a model compound for testing this method. Synthesis was achieved in LiCl–CoCl2 melts at 600 and 700 °C, respectively, under a dry-air atmosphere. Fourier transform infrared (FTIR) and Raman spectroscopies, x-ray diffraction (XRD), and transmission electron microscopy (TEM) were used to study the products obtained. The route suggested results in the formation of stoichiometric high-temperature (HT) LiCoO2 powders.

We have used phase-separated poly(3-hexyltiophene) (P3HT)/poly(L-lactic acid) (PLLA) blends to fabricate low-voltage ion-modulated transistors on a rough paper substrate. The semiconductor and insulator are mixed together in a solution and spin casted onto the paper substrate. Owing to their different solubilities and surface energies the P3HT and PLLA will phase separate vertically during the spinning process creating a thin layer of semiconductor on top of the insulator. This thin semiconductor layer, difficult to achieve by other means on an absorbing paper substrate, creates faster ion-modulated transistors. Using this approach we have created ring-oscillators on paper oscillating at 5 Hz.

Cu2ZnSn(S,Se)4 (CZTSSe) photovoltaics (PV) have long been considered promising candidates for large-scale PV deployment due to the availability of constituent elements and steady improvements in device efficiency over time. The key limitation to high efficiency in this technology remains a deficit in the open-circuit voltage with respect to the band gap. The past decade has seen significant progress toward understanding how the various material properties such as bulk and surface composition, point defects (intrinsic and extrinsic), and grain boundaries all impact the optoelectronic properties of CZTSSe materials, and consequently device performance. This paper aims to summarize what is known about the CZTSSe bulk and surfaces, and how these material properties may be related to the Voc deficit.

Large volume fractions of Mn–Ni–Si (MNS) precipitates formed in irradiated light water reactor pressure vessel (RPV) steels cause severe hardening and embrittlement at high neutron fluence. A new equilibrium thermodynamic model was developed based on the CALculation of PHAse Diagrams (CALPHAD) method using both commercial (TCAL2) and specially assembled databases to predict precipitation of these phases. Good agreement between the model predictions and experimental data suggest that equilibrium thermodynamic models provide a basis to predict terminal MNS precipitation over wider range of alloy compositions and temperatures, and can also serve as a foundation for kinetic modeling of precipitate evolution.

We describe a new protocol for testing coating/substrate interfacial failures through compression loading of micro-pillars containing an inclined interface region, experimentally realized in the TiN/Ti/Si(100) system. Interfacial failures were achieved through direct compression loading in the axial direction, which yielded reproducible failure stresses which exhibited little dependence on the pillar diameter. The testing protocol lends itself to high-resolution analysis of failure surfaces, and is conducive to correlating interfacial structure and chemistry with mechanical failures within the coating/substrate interfacial region.

With multiple elements mixed at equal or near-equal molar ratios, the emerging, high-entropy alloys (HEAs), also named multi-principal elements alloys (MEAs), have posed tremendous challenges to materials scientists and physicists, e.g., how to predict high-entropy phase formation and design alloys. In this paper, we propose some guidelines in predicting phase formation, using thermodynamic and topological parameters of the constituent elements. This guideline together with the existing ones will pave the way toward the composition design of MEAs and HEAs, as well as property optimization based on the composition–structure–property relationship.

Here we report a general method for the synthesis of layered inorganic nanocrystalline materials using graphene oxide (GO) film as the template. Free-standing three-dimensional (3D) lamellar ZnO, α-Fe2O3, and reduced GO/ZnO hybrid structures were synthesized as examples. Such layered structures could also be exfoliated to obtain 2D assembled nanocrystal microsheets. The abundant nucleation sites on the GO surface and the compact stacking of GO platelets made it possible to tightly control metal oxide crystal size (~15 nm), alter preferential crystal growth direction, and assemble the nanocrystals into sheets, as confirmed by multiple characterization techniques.

Mechanical strain triggers changes in inherent molecular structure, especially in polymeric and biological materials. Unlike conventional techniques, we demonstrate a novel dynamic mechanical characterization method to study the effect of this structural evolution with strain on elastic properties. During tensile characterization of small diameter fibers, we quantitatively measured the viscoelastic properties as a continuous function of strain. While this approach is useful to characterize the elastic properties of metal microwires independent of applied strain, it is extremely important for fundamental understanding of molecular changes and their effect on the viscoelastic properties in materials such as polymer fiber and spider silk.

Nanoindentation experiments have been carried on Arabidopsis thaliana using spherical tungsten tips. Load–displacement plots obtained from experiments suggest that there is an optimum diameter of tip size which can be used to safely penetrate the tip through the cell wall. Based on the exact tip size used in the experiments and the measured load–displacement response, the failure stress was calculated using the experimental data in conjunction with a computational model. The value of failure stress was investigated in hypertonic (plasmolyzed), isotonic, and hypotonic (turgid) samples.

We report a new insulation composite of aramid honeycombs filled with superflexible resorcinol–formaldehyde aerogels. Aerogels produced via a sol–gel process were dried with supercritical CO2. The aerogels exhibit a high, rubber-like flexibility, due to almost zero shrinkage and networking of nanoparticles and suitably sized macropores. The high porosity of the aerogels in the range of about 95–98% leads to a low thermal conductivity about 0.037 W/mK and low bulk density of 0.05 g/cm3. The filling of light and stiff aramid honeycombs with these flexible aerogels results in a composite with decreased thermal conductivity and modified mechanical properties.

Using detailed information on the spectrum of shear transformation dynamics previously obtained from low-strain, quasi-static anelastic relaxation in a metallic glass, the corresponding response to a cyclic force is calculated, and prevailing analysis approaches are evaluated. It is shown that the time–temperature superposition principle does not resolve the distribution of activation energies for shear transformations. The distribution of shear transformation zone sizes explains the microscopic mechanisms of both slow (α) and fast (β) relaxations, and the fact that the former are irreversible. These results suggest the need to re-evaluate past interpretations of dynamic behavior of glasses.