We use first-principles calculations based on density functional theory to investigate the interplay between oxygen vacancies, A-site cation size/tolerance factor, epitaxial strain, ferroelectricity, and magnetism in the perovskite manganite series, AMnO3 (A = Ca2+, Sr2+, Ba2+). We find that, as expected, increasing the volume through either chemical pressure or tensile strain generally lowers the formation energy of neutral oxygen vacancies consistent with their established tendency to expand the lattice. Increased volume also favors polar distortions, both because competing rotations of the oxygen octahedra are suppressed and because Coulomb repulsion associated with cation off-centering is reduced. Interestingly, the presence of ferroelectric polarization favors ferromagnetic (FM) over antiferromagnetic (AFM) ordering due to suppressed AFM superexchange as the polar distortion bends the Mn–O–Mn bond angles away from the optimal 180°. Intriguingly, we find that polar distortions compete with the formation of oxygen vacancies, which have a higher formation energy in the polar phases; conversely the presence of oxygen vacancies suppresses the onset of polarization. In contrast, oxygen vacancy formation energies are lower for FM than AFM orderings of the same structure type. Our findings suggest a rich and complex phase diagram, in which defect chemistry, polarization, structure, and magnetism can be modified using chemical potential, stress or pressure, and electric or magnetic fields.

Transparent conductive oxides and amorphous oxide semiconductors are important materials for many modern technologies. Here, we explore the ternary indium zinc tin oxide (IZTO) using combinatorial synthesis and spatially resolved characterization. The electrical conductivity, work function, absorption onset, mechanical hardness, and elastic modulus of the optically transparent (>85%) amorphous IZTO thin films were found to be in the range of 10–2415 S/cm, 4.6–5.3 eV, 3.20–3.34 eV, 9.0–10.8 GPa, and 111–132 GPa, respectively, depending on the cation composition and the deposition conditions. This study enables control of IZTO performance over a broad range of cation compositions.

We propose a surface integral equation simulation scheme which incorporates the integral equation fast Fourier transform accelerative algorithm and domain decomposition method. Such scheme provides efficient and accurate solutions for substrate-supported non-periodic plasmonic array platforms with large number of building blocks and complex element geometry. The effect of array defects can be systematically and successfully studied taking advantage of the considerable flexibility of the domain decomposition approach. The proposed model will be of great advantage for fast and accurate characterization of graded-pattern plasmonic materials and metasurfaces.

The present study aimed to develop an easy method to synthesis silver nanoparticles (AgNPs) using Allamanda cathartica flower extracts. The phytocompounds converted silver nitrate into AgNPs. UV–visible spectra show the maximum absorbance between 350 and 450 nm and x-ray powder diffraction results reveal AgNPs crystallized in cubic phase. Fourier transform infrared spectrum reveals that phytochemicals act as a reducing, stabilizing, and capping agent. Energy-dispersive spectrum, particle size distribution, and transmission electron microscopy analyses show that the nanoparticles are pure, spherical shaped with size of 39 nm. In addition, AgNPs show significantly antibacterial and antioxidant activity compared with commercial antibiotic. Hence, A. cathartica flower extracts mediated AgNPs which will be a new candidate for biomedical applications.

Supercapacitor has received intense interest due to its high-charge/discharge rate and high-power density. C/Fe2O3 layer with different C/Fe ratios were synthesized by a solution-based approach for supercapacitor application. The influence of synthesis conditions on their electrochemical performances was investigated. Cobalt was added into C/Fe2O3 and significant improved its performance. The optimal C/Fe2O3 sample gives a high specific capacitance of 85.3 F/g and the addition of Co3O4 further increase the capacitance of obtained C/Fe2O3/Co3O4 to 144.4 F/g at 5 A/g. This work demonstrates an efficient supercapacitor application of low-cost metal oxides and facile solution-based synthesis approach.

Nanomaterials have been intensively studied over the past decades with many advantages over traditional bulk materials in many applications. Nanomaterials' properties are largely governed by their chemical compositions, sizes, shapes, dimensions, morphologies and structures, which are primarily controlled with the chemical and/or physical fabrication methods and processes. This prospective will highlight recent progress on the modifications of oxide nanomaterials' properties by hydrogenation, namely heat treatment under hydrogen or hydrogen plasma environment, for various applications.

We demonstrate here the design, synthesis and characterization of two new chlorinated polymers, P(NDI2HD–T2Cl2) and P(NDI2OD–T2Cl2) based on N,N′-difunctionalized naphthalene diimide (NDI) and 3,3′-dichloro-2,2′-bithiophene (T2Cl2) moieties. Our results indicate that organic thin-film transistors (OTFTs) based on these new chlorinated polymers exhibit electron mobilities approaching 0.1 cm2V−1s−1 (I on:I off ~ 106–107), with far less ambipolarity due to their lower highest occupied molecular orbital energies, and they are more stable under deleterious high-humidity conditions (RH ~ 60%) and upon submersion in water, compared with those fabricated with the parent non-chlorinated polymers. In addition, OTFTs fabricated with the new chlorinated polymers exhibit excellent operational stabilities with <3% degradations upon bias-stress test.

We present two straightforward and cost-effective methods, based on metal-assisted chemical etching and a direct imprinting technique, to fabricate metal-covered porous amorphous silicon back reflectors for amorphous silicon solar cells. We demonstrate an increase of approximately 30% in both short-circuit current and overall efficiency with respect to a cell with a flat metal back reflector. This is achieved by implementing light trapping via either a roughened porous amorphous silicon layer or an imprinted periodic grating. This work provides a pathway to increase amorphous silicon solar cell efficiency via increased absorption without significantly impacting processing costs.

In this paper, hierarchical nanostructures of BiOBr/AgBr on electrospun carbon nanofibers (CNFs) were prepared by combination of electrospinning and carbonization. Compared with the smooth surface of CNFs, the rough surface with hierarchical nanostructures of BiOBr/AgBr can be obtained by adding the certain amount of BiOBr/AgBr precursors into the spinning solution. The as-prepared composite CNFs exhibited highly photocatalytic activities for degradation of rhodamine-B and reduction of p-nitrophenol under the visible-light irradiation and at room temperature. Furthermore, the as-prepared composite CNFs showed the favor separation, recovery, and cyclic utilization properties.

Among various material nanoarchitectures, the nanotube geometry has received incredible attention due to the unique properties provided by its high surface area as well as nanoscale wall thickness and the availability of a variety of techniques to fabricate them. Since the beginning of this century, anodization has emerged as one of the most effective techniques for the fabrication of functional oxide nanotubes. Oxide nanotubes of a number of metals and alloys have been developed using this versatile technique. We review here the research activities on anodic nanotubes of various binary, ternary, and multinary materials and their selected applications.

Engineering of a novel heterostructured oxide interface was used to enhance the oxygen surface exchange kinetics of La0.6Sr0.4Co0.2Fe0.8O3−δ (LSCF113) thin films. A single-layer decoration of mixed (LaSr)2CoO4±δ (LSC214) and La1−xSrxCoO3−δ (LSC113) and a double-layer decoration of stacked LSC214 and LSC113 grown on the LSCF113 markedly enhanced the surface exchange coefficients of the LSCF113 by up to ~1.5 orders of magnitude relative to the undecorated LSCF113. It is hypothesized that two different types of surface decorations can enable Sr segregation at the interface and surfaces of LSC113 and LSC214, leading to enhancement of the oxygen surface exchange kinetics of decorated LSCF113.

Direct electrical measurement of single grain boundaries is performed for ZnO-based multilayer ceramic varistors with fine grains of 2 µm, using a nano-prober. The effect of ZnO grains on non-linearity is shown to be significant. The microstructure is comprised at least two non-linear types as good- and bad-junctions. The numerical ratio of good to bad is estimated to be about one (non-linearity exponent α max ≥ 10) to two (<10), which is independent of microstructural development as grain growth. The grain control of twinning as well as crystal orientation and donor concentration is considered effective in the further improvement.

Surface patterned NiFe2O4 thin films exhibited large reduction in coercivity as compared with the films without surface patterning. Chemical analysis of the films revealed that there was no diffusion between the film and the substrate. Additional heating was shown to improve saturation magnetization without adverse effect on coercivity. The process of imprinting was eliminated as the possible cause of the phenomena as the flat stamp did not alter the magnetic properties of the film. Finally, it was shown that the orientation of the features with respect to the magnetic field does not have a significant effect on the magnetic response.

Photocatalytic reduction of carbon dioxide (CO2) into renewable hydrocarbon fuels using solar energy has gained much attention in the effort to conserve energy and enhance carbon cycling. This paper begins with a brief description of the basic concepts of the photocatalytic reduction of CO2, introduces some experimental challenges in the gas photoreaction system and provides a review of perovskite oxide semiconductor catalysts, including tantalates, niobates, titanates, zirconates and cerates, for use in the gas phase photoreduction of CO2. The prospects for the future research of CO2 photoreduction are also presented.

In this work, a composite nanofibrous scaffold of collagen/hydroxyapatite was prepared by electrospinning using a mild solvent. Hydroxyapatite particles dispersed into a collagen/acetic acid/water solution was electrospun to yield composite nanofibers. Scanning electron microscopy reveals nanofibers with an average diameter of 342 ± 67 nm, and a rough surface caused by the hydroxyapatite particles. Both X-ray and infrared spectroscopy confirmed the presence of the hydroxyapatite particles embedded in the collagen fibers. The inclusion of hydroxyapatite particles does not alter the native collagen structure. Lastly, these composite nanofibers support pre-osteoblast adhesion. These results show how “green” electrospinning could be used to generate nanocomposite scaffolds with potential biomedical applications.