Graphene is currently one of the most extensively studied materials because it displays a number of unique structural and electronic properties. A variety of methods are currently available for the growth of graphene; however, few are viable for large scale, cost-effective production of high quality graphene. Here, a novel growth process for few layer graphene using chemical vapor deposition (CVD) and a commercial iron nanopowder catalyst is described. This method is readily scalable so it can be used to produce a large volume of graphene sheets. Graphene sheets made from this process were characterized by Raman spectroscopy, and scanning and transmission electron microscopy. Raman spectroscopy shows that the product consists of few layer graphene sheets. This is the first reported method of utilizing nanoparticles to synthesize graphene by a CVD process, which typically produces multiwalled carbon nanotubes. A possible mechanism for the formation of graphene by this modified CVD process is discussed.

The conjugated polymer poly(2,5-dihexyl-1,4-phenylene-alt-2-amino-4,6-pyrimidine) was synthesized and used in the supramolecular functionalization of single-walled carbon nanotubes (SWNTs). It was found that this polymer can form strong supramolecular polymer–nanotube assembly and produce a stable composite in solution. The resulting polymerized nanotubes were analyzed by UV–Vis absorption and emission spectroscopy, thermogravimetry, transmission electron microscopy and scanning electron microscopy. It was found that the noncovalent functionalization did not damage the nanotube structure. The polymer content in the polymer–nanotube composite could be calculated to be 41% by thermogravimetry analysis. The composite exhibited certain solubility in dimethylacetamide (DMAc), where the solubility in the absence of excess free polymer solution is 78.7 mg L−1. The composite exhibited a conductivity of 0.005 S cm−1 and the anodic and cathodic peaks were observed at 0.47 and 0.37 V. Galvanostatical charge/discharge tests give good cycling behavior of maintaining a stable capacitance value of 66.7 F g−1 over 1000 cycles at a current load of 1 mA cm−2 without distinct drop.

The structure and phase transition behavior of monoclinic phase of the morphotropic phase boundary composition Pb(Sc1/2Nb1/2)O3]0.58 –[PbTiO3]0.42 (PSN–42PT) in lead scandium niobate–lead titanate (PSN–PT) system have been investigated by in situ high-temperature polarized light microscopy (PLM) and x-ray diffraction (XRD) studies. Temperature-dependent powder XRD studies of PSN–42PT indicated monoclinic structure at 25 °C and cubic structure at 400 °C. It is observed that the room temperature monoclinic structure transforms to cubic structure through an intermediate tetragonal structure. The temperature-induced domain changes at the phase transition are investigated on (001) face of unpoled PSN–42PT crystal while heating as well as cooling the crystal on hot stage of the PLM. Under crossed polar condition, the striplike polar domains observed at lower temperature vanish gradually with increasing temperature. In the vicinity of ferroelectric transition temperature, the mesosize domains that appeared in the variable temperature PLM images are in accordance with the monoclinic–tetragonal–cubic transition sequence concluded by in situ high-temperature XRD studies. The domain rotation corresponding to the structural transformation sequence is concluded for the first time in the PSN–42PT.

Sodium dodecyl sulfate (SDS) was chosen as the structure controller and surface modifier for hydrothermal preparation of surfactant-modified goethite (α-FeOOH) nanorods. The as-synthesized samples were characterized by transmission electron microscopy, x-ray diffraction, Fourier transform infrared spectroscopy, Brunauer, Emmett and Teller technique, and potentiometric titration. Adsorption study using methylene blue (MB) as a model pollutant was conducted onto the surfactant-modified goethite surface. The results showed that the surfactant-modified α-FeOOH nanorods had high adsorption capacity. MB could be efficiently removed from the solution at pH 5, initial MB concentration 200 mg/L, α-FeOOH dosage 0.5 g/L, and temperature 30 °C, with 96% removal ratio. The adsorption capacity was found to be as high as 385 mg/g. The adsorption kinetic data could be described well by the pseudo-second-order model. The isothermic data were highly fitted to Langmuir isotherm. High adsorption capacity and simple reaction conditions give this novel material good prospects in future applications.

We present a bottom-up fabrication route to fabricate solid-solution Rh–Pd–Pt ternary alloy nanoparticles (NPs), with well-controlled compositions through femtosecond laser irradiation of a mixed solution of metallic ions, without any reducing agents and complicated processes. The structure of fabricated NPs was crystalline, and formation of solid-solution alloy formation was confirmed by electron and x-ray diffraction measurements. The crystalline nature of alloy NPs was also confirmed through high-resolution transmission electron microscope measurement. According to energy dispersive spectroscopy analysis, elemental composition of an individual NP was almost the same as the initial feeding ratio of ions in the mixed solutions. The electronic state of the element in alloy NPs was confirmed to be pure metal by XPS measurement. The structural studies of Rh–Pd–Pt NPs suggested that the demonstrated technique opens up a new dimension for the fabrication of NPs, which has well-controlled properties for practical use in various fields.

The reliability of nanomaterials depends on maintaining their specific sizes and structures. However, the stability of many nanomaterials in radiation environments remains uncertain due to the lack of a fully developed fundamental understanding of the radiation response on the nanoscale. To provide an insight into the dynamic aspects of single ion effects in nanomaterials, gold nanoparticles (NPs) with nominal diameters of 5, 20, and 60 nm were subjected to self-ion irradiation at energies of 46 keV, 2.8 MeV, and 10 MeV in situ inside of a transmission electron microscope. Ion interactions created a variety of far-from-equilibrium structures including small (∼1 nm) sputtered nanoclusters from the parent NPs of all sizes. Single ions created surface bumps and elongated nanofilaments in the 60 nm NPs. Similar shape changes were observed in the 20 nm NPs, while the 5 nm NPs were transiently melted or explosively broken apart.

The corrosion behavior of 2099 Al–Li alloy in NaCl aqueous solutions with different concentrations (1.5, 3.5, and 5.0% in mass fraction) was investigated. Its corrosion resistance was evaluated using electrochemical measurements together with full immersion tests. The results showed that the 2099 Al–Li alloy possessed good corrosion resistance in NaCl aqueous solutions. Its corrosion rate increased with increasing chloride ion concentration. The main form of corrosion failure was pitting corrosion. The impurity containing sulfur leads to surface pitting. The oxide films that formed during the manufacturing process offer a good resistance to corrosion. They are likely to suffer separation, cracking, and drop-off when immersed in aggressive NaCl aqueous solution. The good corrosion susceptibility of the alloy may be attributed to homogeneous coherent nanoscale precipitates.

Aiming to clarify the effects of initial states on hot deformation behavior of a powder metallurgy nickel-based superalloy FGH96, specimens in hot isostatic pressed (HIPed) and solution states were isothermally compressed in the temperature range of 1000–1150 °C and the strain rate range of 0.001–1.0 s−1. It revealed that the flow behavior of FGH96 was dependent on the initial states, in which the deformation resistance was higher in the solution state than that in the HIPed state at evaluated temperatures, and the differences became less when the temperature was higher than the γ′ dissolution temperature. The calculated hot activation energy using peak stresses are 590 and 1285 kJ mol−1 for HIPed and solution specimens. Comparison with HIPed specimen, the efficiency of power dissipation (η) in solution specimen is less, and the optimum workability regime moves to higher temperatures. Cracking and in-grain shear bands were observed in the specimens when compressed in flow instability areas.

Two types of carbon nanotube reinforced nickel (CNT/Ni) nanocomposites were processed, both involving spark plasma sintering (SPS) of precursor powders consisting of nickel and carbon nanotubes. The first type involved simple mechanical dry milling of nickel and CNT powders, followed by sintering using SPS, resulting in nanocomposites exhibiting a tensile yield strength of 350 MPa (about two times that of SPS processed monolithic nickel with a strength of 160 MPa) and about 30% elongation to failure. In contrast, the nanocomposites processed by SPS of powders prepared by molecular-level mixing (MLM) exhibited substantially higher tensile yield strength of 690 MPa but limited ductility with an 8% elongation to failure. While the former type of processing involving dry-milling is expected to be lower in cost as well as easy to scale-up, the latter type of processing technique involving MLM leads to a more homogeneous distribution of nanotubes, leading to extraordinarily high strength levels.

In this study, the precipitation behavior of the pretwinned extruded Mg–6Al–1Zn alloy was investigated. It was observed that the precipitates preferentially nucleated at the twin boundaries or within the preexistent twins. This distribution of the precipitates led to the distinguishing influences on subsequent compression and tension process, which were dominated by twinning and detwinning of the preexistent twins, respectively. The compressive yield strength after aging was a little lower than the stress when the precompression was interrupted, which meant that the impeding effect of precipitation on twin expansion was relatively smaller than that of dislocations induced by precompression. However, the tensile yield strength of aged samples was extremely higher than that of non-aged samples as the migration of the twin boundaries during detwinning was considerably hindered because of the preferential precipitation within the preexistent {10-12} twins.

Ytterbium monosilicate (Yb2SiO5) is a promising candidate for environmental barrier coating. However, its mechanical and thermal properties are not well understood. In this work, the structural, mechanical, and thermal properties of Yb2SiO5 are studied by combining density functional theory and chemical bond theory calculations. Based on the calculated equilibrium crystal structure, heterogeneous bonding nature and distortion of the structure are revealed. Meanwhile, the full set of elastic constants, polycrystalline mechanical properties, and elastic anisotropy of Yb2SiO5 are presented. In addition, the minimum thermal conductivity of Yb2SiO5 was determined to be 0.74 W m−1 K−1. The theoretical results highlight the potential application of Yb2SiO5 in a thermal and environmental barrier coating.

Utilization of PbZrxTi1−xO3 (PZT) nanofibers as functional flexible fillers in sensing and energy harvesting applications requires uniform, submicrometer fibers with a large aspect ratio. Previous studies concentrated on the rheological effects on the fiber's diameter and morphology. However, reports on the effect of electric field on these fiber properties are still scarce. In this paper, the effects of surface charge and electric field on the fiber branching are decoupled. We show unequivocally that the external electric field governs this phenomenon. Low viscosity (∼0.12 Pa s) PZT sols yielded a sharp step-like transition from a large to a small diameter regime at electric fields above 0.8 kV/cm. On the other hand, high viscosity sols (∼0.74 Pa s) yielded a transition from a single to a bimodal distribution at the same electric field, due to the branching effect. An ability to obtain a single or bimodal diameter distribution in the range of 100–800 nm was demonstrated.

By combining high-resolution transmission electron microscopy and scanning transmission electron microscopy with analytical capability, we investigated the nanostructure of a textured hematite photoanode with columnar grains obtained by the colloidal deposition of magnetite nanocrystals. This initial report describes in detail the structure and chemistry of the α-Fe2O3/SnO2:F interface by identifying semicoherent and incoherent interfaces as well as a localized interdiffusion layer of Sn and Fe at the interface (∼100 nm in length). Our study indicates that unintentional doping by tin at a high sintering temperature is not significant in enhancing hematite photoanode performance for water oxidation. The correlation of nanoscale morphology with photoelectrochemical characterization facilitated the identification of the beneficial effect of a preferential growth direction of a hematite film along the [110] axis for water-splitting efficiency.

In the present research, the microstructures and mechanical properties of Al–Si–Cu alloy matrix composites reinforced with nanosized alumina (Al2O3) and zirconia (ZrO2) were investigated. For this purpose, Al2O3 particulates were replaced with different wt% of ZrO2 to improve microstructure and mechanical properties. The T6 heat treatment was also performed to investigate mechanical properties in heat-treated condition. Tensile testing, hardness measurement, optical microscopy, x-ray diffraction (XRD), energy dispersive spectroscopy, and scanning electron microscope examination were used to characterize the behavior of composite and matrix. The highest tensile strength was achieved in the specimen containing 1.25 wt% ZrO2 and 0.75 wt% Al2O3, which shows an increase to 36% in comparison with the nonreinforced base alloy. The hardness values indicated 11% increase following the heat treatment. Fracture surface examinations revealed a transition from ductile fracture mode in as-cast aluminum alloy to rather brittle in Al–Si–Cu alloy matrix hybrid composites.

Highly luminescent CdTe quantum dots (QDs) were prepared through a fast, facile, and straightforward method. The crystal structure, particle size, optical properties as well as molecular interactions between the CdTe QDs and their capping agents have been investigated by high resolution transmission electron microscopy, selected area electron diffraction, scanning transmission electron microscope–energy dispersive x-ray spectroscopy, UV-vis absorption, photoluminescence, and Fourier transform infrared, respectively. The results illustrate that the CdTe nanoparticles exhibit cubic structure and the average crystallite size is 2.3 nm. Meanwhile, fluorescence and UV-vis spectroscopic techniques were used to study the interaction between hemin and the well-defined CdTe QDs. In weak basic media, the fluorescence of CdTe QDs was quenched notably by hemin, and the quenching values were proportional to the concentration of the quencher in a certain range. The quenching mechanism was discussed to be a dynamic quenching procedure, collisional process, and hemin as a fluorescence quencher donated its electron to CdTe QDs to occupy the hole and accordingly disrupted the electron–hole recombination.

A comprehensive understanding of the growth pattern of intermetallic compounds (IMCs) during solidification is critical to both the crystal-growth theory and its property optimization. In this article, growth pattern and three-dimensional (3D) morphology of primary Al6Mn IMC were investigated in directionally solidified Al–3 at.% Mn alloy at a wide range of growth rates. A transition from faceted (<60 μm/s) to nonfaceted growth (>100 μm/s) was observed with increasing growth rates. Correspondingly, 3D morphologies of primary Al6Mn change from a solid polyhedron to a hollow structure, and then to a dendrite. This kind of change is associated with the competitive growths of different crystal planes determined by the crystallographic anisotropy and growth kinetics of Al6Mn. A growth model based on atomic cluster attachment is proposed to reveal the growth transition, and a growth-rate ratio between different crystal planes is used to appropriately reveal the formation mechanism of different morphologies at low rates.

The influence of aging treatment on shape memory effect (SME) and wear resistance of Fe–20Mn–5Si–10Cr–5Ni–0.7V–0.2N (mass%) alloy was investigated. Results showed that vanadium nitride (VN) particles precipitated during aging treatment, and the amount and size of the particles increased with increasing aging time. The sample aged for 8 h exhibited the maximal shape recovery ratio of 74% (compared with that of 16% for unaged) and favorable wear resistance in both dry wear and oil-lubricant wear conditions. The fine VN particles are the key factor to improve the SME by strengthening the alloy and acting as preferential nucleation sites for martensite. However, more and larger particles due to further aging treatment appeared to have negative effects on the SME and wear resistance. After oil-lubricant friction, there existed large amounts of friction-stress-induced ε martensite in the worn surface of the sample. As a result, the wear resistance of samples in oil-lubricant wear condition was remarkably higher than that in dry wear condition.

Bi2O2CO3/ZnWO4 composite photocatalysts have been successfully synthesized by a mixed calcination method after hydrothermal process. The catalysts were characterized by powder x-ray diffraction, scanning electron microscopy, transmission electron microscopy, high resolution transmission electron microscopy, x-ray photoelectron spectroscopy, and UV-vis diffuse reflectance spectrum. The results showed that the hierarchical Bi2O2CO3/ZnWO4 nanocomposites were obtained by mixed grinding calcination method and Bi2O2CO3 nanospheres grow on the primary ZnWO4 particles. The Bi2O2CO3/ZnWO4 composites exhibit higher photocatalytic activities compared to pure ZnWO4 and Bi2O2CO3 particles under UV light irradiation. Furthermore, the excellent photocatalytic efficiency of the Bi2O2CO3/ZnWO4 composite was deduced closely related to Bi2O2CO3/ZnWO4 heterojunctions whose presence is generally regarded to be a favorable factor for the separation of photogenerated electrons and holes.

Confining light metal hydrides in micro- or mesoporous scaffolds is considered to be a promising way to overcome the existing challenges for these materials, e.g. their application in hydrogen storage. Different techniques exist which allow us to homogeneously fill pores of a host matrix with the respective hydride, thus yielding well defined composite materials. For this report, the ordered mesoporous carbon CMK-3 was taken as a support for LiAlH4 realized by a solution impregnation method to improve the hydrogen desorption behavior of LiAlH4 by nanoconfinement effects. It is shown that upon heating, LiAlH4 is unusually oxidized by coordinated tetrahydrofuran solvent molecules. The important result of the herein described work is the finding of a final composite containing nanoscale aluminum oxide inside the pores of the CMK-3 carbon host instead of a metal or alloy. This newly observed unusual oxidation behavior has major implications when applying these compounds for the targeted synthesis of homogeneous metal–carbon composite materials.

Pure single-crystalline bismuth (III) sulfide (Bi2S3) nanowires with lengths of the long and short axes being 1.58–1.75 μm and 40 nm were prepared by a simple surfactant-assisted reflux method in the presence of thioacetamide, which served as both the sulfur source and a “soft template” in the formation of bismuth sulfide nanostructures. The effects of different surfactant, surfactant molecular weight, solvent medium, and sulfur source on the morphology, structure, and phase composition of the as-prepared Bi2S3 products were discussed. The formation of long Bi2S3 nanowires was probably via the mechanism of pyrolysis of bismuth (III) sulfide complexes dimer and continuous growth of crystalline nuclei along rod-shaped micelles originated from “soft-template” of polyethylene glycol (PEG-800). Besides, ultraviolet–visible spectroscopic (UV-Vis), and photoluminescent (PL) Bi2S3 band features indicated that the nanowires have excellent optical properties, in the optical field of potential applications.