Rutile nanoparticles have been synthesized by acid hydrolysis of titanium isopropoxide by low-temperature dissolution-reprecipitation process. High-resolution transmission electron micrographs of the rutile colloidal solution show needle-shaped rutile nanoparticles with the dimensions of 10–30 nm in diameter and 100–150 nm in length. X-ray diffraction (XRD) data show the existence of only the rutile polymorph in TiO2 powder with a crystallite size of 11.3 nm. The dielectric constant of rutile nanoparticles has been found to be 57 at 10 MHz AC frequency and DC conductance as 2.3 × 10−6 S/cm. Transmission electron micrographs and XRD data analysis imply that the rutile crystallites are self-organized in a regular fashion to produce multilayer three-dimensional linear clusters. The clusters have been found to be microporous (average porosity 1.4 nm) with high specific surface area (132.2 m2/g). At higher concentration, the clusters aggregate to produce interconnected network of star- or flower-like structures. This organized crystalline microporous metal-oxide semiconductor might find various practical applications.

A facile method is developed to synthesize ion-based π-conjugated polymer nanoparticles. The polymer chosen is anionic poly(2-methoxy-5-propyloxysulfonate phenylene vinylene); MPS-PPV. The synthesis is based on nanoagglomeration via polyion association (termed as NAPA method) that includes polyion complex formation and subsequent globulization to fabricate nanoarchitectures in water-based liquid. Salient features include no spectral shift in the UV–vis absorption upon the nanoparticle formation, in contrast to a common observation that conjugated polymer nanoparticles made by a reprecipitation method exhibit blue shift in their peak. This behavior suggests the absence of further bending or kinking of the polymer backbone during nanoglobulization. Fluorescence peak energy is size dependent; the larger the particle size is, the lower is its fluorescence energy. This can be dominantly ascribed to the increased contribution of sole excitation of the chromophoric segments that have a long effective conjugation length. Because a small (large) particle has a large (small) surface-to-volume ratio, the blue-site (red-site) fluorescence is associated with the surface (inner) region of the polymer nanoparticles, respectively.

Multifunctionalized nanoparticles have a great attention owing to their unique advantages as ideal tools for gene/drug delivery, bioimaging, labeling, or intracellular tracking in biomedical applications. In the present work, azole functional Poly(glycidyl methacrylate) (PGMA) grafted hollow silica sphere (HSS) nanoparticles synthesized and characterized as biomaterials. For the preparation of HSS particles, a two-step method based on the sol–gel process was used in this study. HSS grafted with PGMA by free radical polymerization of (glycidyl methacrylate) (GMA) and HSPGMA (PGMA grafted HSS) modified with 5-aminotetrazole (ATet), 3-amino-1,2,4-triazole (ATri), and 1H-1,2,4-triazole (Tri) to obtain 1,2,4-triazole functional PGMA grafted HSS (HSPGMA-Tri), 5-aminotetrazole functional PGMA grafted HSS (HSPGMA-Tet) and 5-Amino-Triazole functional PGMA grafted HSS (HSPGMA-ATri) molecules via ring opening of the epoxide ring. Azole functional PGMA grafted HSS composites were doped with phosphoric acid. Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and atomic force microscopy (AFM) analyses were confirmed the grafting and modification of HSS. TGA and DSC were used to examine the thermal stability and homogeneity of the materials.

Thermoelectric generation is one of the strongest candidates for recovering the waste heat from industry and transportation. Some of oxides and silicides are considered to be promising thermoelectric materials because of their high oxidation resistance. Several types of modules using p-type Ca3Co4O9/n-type CaMnO3 and p-type MnSi1.75/n-type Mn3Si4Al2 have been prepared and shown around 4 kW/m2 of maximum power density. The present study described the challenging enhancement of the thermoelectric figure of merit ZT of both oxide and silicide compounds. Introduction of secondary phases and low bulk density using a partial melting method is found to be effective for reducing phonon thermal conductivity in the promising Bi2Sr2Co2Ox. The grain size and distribution of the secondary phases can be controlled by optimizing the parameters of the partial melting method. On the other hand, detailed crystallographic structure of a new n-type Mn3Si4Al2 is clarified and leads to the enhancement of the ZT values by elemental substitution.

X-ray and neutron diffraction are particularly useful for characterizing ferroelectric materials in situ, e.g., during application of temperature, pressure, electric field, and stress. In this review, we introduce many experimental approaches for such measurements and highlight important discoveries in ferroelectrics that utilized diffraction. We focus our examples on polycrystalline ferroelectrics, though many of the approaches and analysis methods can also be applied to thin films and single crystals. Methods discussed for characterization of structure include, phase identification, line profile analysis, whole pattern fitting, pair distribution functions, and the x-ray diffraction based three-dimensional microscopy. Further advancement of these and other techniques offers potential for continued important contributions to the fundamental understanding of ferroelectric materials.

The nanoscale precipitation induced by 1.8 MeV ion irradiation in Cu1−xVx thin films, with x ≈ 0.09 and 0.91, was studied by atom probe tomography. For the Cu91V9 alloys, irradiation in the range of 300–500 °C led to steady-state compositional patterning of V-rich nanoprecipitates. V nanoprecipitates larger than ∼10 nm in diameter, moreover, contained Cu-rich cores, resulting in an unusual “cherry-pit” nanostructure. The number of these pits within one precipitate increased with the precipitate size, but with the volume fraction of pits within a given precipitate remaining roughly constant, from ∼1.5 to 5%. Similar irradiations performed on V91Cu9 also resulted in an enhanced precipitation reaction, but with smaller Cu-rich nanoprecipitates, <3 nm in diameter, and no “cherry pits.” These results are rationalized using recent atomistic simulations that have explored the conditions for stabilizing by ion irradiation “cherry-pit” nanostructures in immiscible A–B alloy systems, such as Cu–V.

Morphologically controllable copper sulfide (CuS) nanoneedle, nanowall, and nanosheet networks on copper substrates have been fabricated by a simple, facile, and fast method based on low-temperature chemical vapor deposition through simply adjusting the reaction conditions such as the temperature and flow rate of argon gas. The compositional and structural analyses indicated that all the obtained nano-networks were single-crystalline. And their growths were possibly controlled by a solid–liquid–solid mechanism. The photocatalytic activities of the different shaped CuS nanostructures have been evaluated by their photodegradation on rhodamine B and methylene blue in aqueous phase, which revealed that in both cases the CuS nanoneedles nano-network exhibited better performance than the other two nanostructures.

We investigate the structural evolution of Er/Si nanoclusters obtained in co-implanted fused silica upon annealing via Raman spectroscopy and transmission electron microscopy. The effect of annealing temperature (900–1200 °C) on the nature and the relative fraction of the formed amorphous-Si, Si nanocrystals (Si-nc), and amorphous Er nanoparticles (Er-np) was determined in this ternary Er–Si–O system, showing a change of growth regime above 1100 °C due to the formation of mixed Er/O/Si aggregates. We observe that the nucleation and growth of amorphous Er-np and Si-nc are mutually affected. The 2-fold increase in the size of Er-np when no excess Si+ is present in the matrix indicates that the formation of Si-nc in the proximity of Er clusters hinders Er diffusivity above 1100 °C. This finding shows the importance of nanoclustering for improving the thermal stability of Er-doped silica systems.

In this contribution, the structural, mechanical, and thermal properties of MSiO4 have been investigated theoretically and the anisotropy of elastic properties has been discussed in detail. The heterogeneous bonding nature was revealed from density functional theory computations and chemical bond theory (CBT). The Young's modulus and shear modulus of MSiO4 were anisotropic and the anisotropy on different planes was quite different. The thermal expansion coefficients of MSiO4 estimated from CBT were 5.1 × 10−6 and 4.4 × 10−6 K−1 for ZrSiO4 and HfSiO4, respectively. These results were quite consistent with the experiments. The temperature dependent thermal conductivities of MSiO4 were estimated from Slack's model, the minimum thermal conductivity was predicted to be 1.54 and 1.24 W m−1 K−1 for ZrSiO4 and HfSiO4, respectively. Our theoretical results show that MSiO4 are excellent thermal barrier materials with good tolerance to withstand the mechanical damage.

Monophasic Sn1−xCoxO2 (x = 0.05, 0.10, and 0.15) nanoparticles with tetragonal structure have been successfully synthesized by solvothermal method using oxalate precursor route. Powder x-ray diffraction and selected area electron diffraction studies confirmed highly crystalline cassiterite SnO2 structure. The contraction of lattice constants confirmed the incorporation of Co2+ in SnO2 host lattice. Hexagonal nanoparticles with average grain size of 8–13 nm have been formed. With the increasing Co content, the decreasing crystallite size of SnO2 with increasing surface areas from 194 to 219 m2/g was found. The percentage reflectance increases on increasing the cobalt concentration, and a noticeable blue shift appeared. The band gap was found to be 3.85, 3.91, and 4.09 eV, respectively. Co-doped SnO2 showed distinct magnetic behavior with different Co2+ concentration. For x = 0.05 and 0.10, nanoparticles showed paramagnetism with antiferromagnetic interaction, however, on further increasing x = 0.15, the nanoparticles showed canted antiferromagnetic coupling.

InGaN/GaN green light-emitting diodes (LEDs) have been prepared by metal-organic chemical vapor deposition with various growth temperatures for p-GaN layer. The structural and optoelectronic properties of as-grown multiple quantum wells (MQWs) and LEDs are studied in detail. It reveals that with the growth of p-GaN layer, the crystalline qualities of the as-grown n-GaN layer are improved significantly, while the optoelectronic properties of MQWs are decreased dramatically. Furthermore, the mechanisms for the effect of p-GaN growth temperature on the properties of InGaN/GaN green LEDs are proposed. It is demonstrated that the p-GaN layer grown at a suitable temperature of 950 °C shows the highest optoelectronic properties due to the fact that this suitable temperature for p-layer growth is good for the Mg doping and would not cause the fluctuation of indium in the MQWs, and eventually benefits to the effective recombination of carriers. This work provides an optimized p-GaN layer growth temperature for realizing highly efficient InGaN/GaN green LED devices.

Flexible touch sensors with high sensitivity show promise in biomedical diagnostics and for artificial “electronic skin” for robotics or prosthetic devices. For “electronic skin” applications, there exists a need for low-cost, scalable methods for producing pixels that sense both medium (10–100 kPa) and low pressures (<10 kPa). Here, the “breath figures” (BFs) method, a simple, self-assembly-based method for producing honeycomb-structured porous polymer films, was used to prepare pattern compressible, and microstructured dielectric layers for capacitive pressure sensors. Porous polystyrene BFs films served as molds for structuring polydimethylsiloxane dielectrics. Pressure sensing devices containing the BFs-molded dielectrics consistently gave pressure response with little hysteresis, high sensitivities at lower applied pressures, and improved sensitivity at higher pressures. Analysis of microstructure geometries and pressure sensor performance suggests that structures with higher aspect ratios (height-to-width) produce less hysteresis, and that less uniform, more polydisperse structures yield a more linear pressure response.

Nanoparticle-sized powders have seen more and more use in many of today's applications. As particle size decreases, many properties change including the ability to embed the small particles in liquids and other media. With decreasing size, however, surface energy becomes more important and can dictate the final shape of the particle. In applications based on polar molecules attaching to the nanoparticle surface, the surface morphology can become a key design parameter. A nucleation and growth model has been constructed for truncated body-centered cubic derivative materials, along with an update to previously published work on face-centered cubic materials. The model shows that for (110)- and (111)-truncations of a cube with a specified surface energy for each surface, the critical nuclei and equilibrium growth shapes are the same, supporting the theory of self-similar growth that had only been mentioned previously, but never proven. In this analysis, saddle points play an important role in determining the critical nuclei for comparison with the equilibrium growth shapes.

The influence of aging treatment on the shape memory effect and corrosion resistance of a newly developed Fe–Mn–Si–Cr–Ni-based alloy containing C, N, and V elements was investigated. Results showed that V(CN) and Cr23C6 particles, precipitated during aging, could improve the shape recovery ratio to 72%, compared with that of 21% for the solution treated sample, when the alloy was aged for 24 h. The corrosion behavior in 0.5 M H2SO4 solution was almost the same for all the samples, barring a slight difference in the passivation range. In addition, the passivation current and critical current required for the onset of passivation of the aged samples were almost triple that of the unaged. In 3.5% NaCl solution the corrosion behavior of all aged samples was that of general dissolution with localized attack (pitting), which can be attributed to the micro-cathodic effect of the V(CN) and Cr23C6 particles precipitated during aging. Although the best corrosion resistance in both H2SO4 and NaCl solutions was shown by the solution treated sample, 24 h-aged sample exhibited an improved corrosion resistance, ascribed to the improved chemical homogeneity of the austenite matrix due to long aging time (24 h).

The local micromechanical properties of two cyclic olefin copolymers (COCs) under an applied strain were measured using quasi-static (QS) and dynamic nanoindentation. Samples were prepared by compression molding and tested at five various applied strain levels, leading to a variation in pileup around the residual indentation impression. The variation in the resulting pileup morphology and the subsequent perceived changes in modulus and hardness as a function of applied strain was quantified for these COCs. The perceived mechanical properties determined using both QS and dynamic tests were influenced by the relative out of plane deformation, and as such provide a method to map local variations in residual stresses and strains without the need to measure residual impression pileup for each indentation. The dynamically measured properties appear to provide a more consistent correlation with both the applied strain and pile up behavior around the indents than the modulus and hardness determined from QS nanoindentation.

We report on the study of the characteristics of indium–tin oxide (ITO) films prepared by well-controlled and reproducible DC magnetron sputtering in argon with consequent annealing in oxygen atmosphere. The structural, electrical, and optical properties of the ITO films were investigated. It was found that the films deposited in argon atmosphere with a commercial ITO target have low transparency and high resistivity. The lower value of the resistivity around 3 × 10−4 Ω cm and the higher value of the figure of merit of 7.4 × 10−3 Ω−1 for 200 nm thick films are obtained after postannealing the films at the optimal temperature T = 300 °C for 1 h. It was found experimentally that postannealing at different temperatures allows tuning effective work function of the ITO films in the range of 4.2–5.5 eV. The latter is an important issue for applications in optoelectronic devices. The fabrication method is useful for the fabrication of ITO films with high electro-optical parameters on flexible polyimide substrates.

A three-dimensional nanostructured graphene oxide–Mn3O4 hybrid was synthesized by a coprecipitation method and used as an anode material of lithium ion batteries, which reached an initial specific capacity of 1400 mA h/g. This method was developed to simplify the process of fabricating uniform composite nanomaterials for abundant applications. In this work, Mn3O4 particles were coordinately distributed on the surface of reduced graphene oxide nanosheets to avoid detrimental stacking of graphene layers by forming 3D nanostructures, as characterized by a scanning electron microscope. As demonstrated by the in situ observation of a scanning probe microscope, severe pulverization of Mn3O4 particles during charge/discharge processing was significantly abstained when graphene layers constrained swelling and shrinkage. The as-prepared graphene–Mn3O4 nanomaterials exhibited a large specific capacity of 949 mA h/g, high-rechargeable efficiency of ∼98%, and exceptional cyclic stability. After 100 constant-current charging/discharging cycles at 100 mA/g, the specific capacity remained at 792 mA h/g with a coulombic efficiency of 98.1%. Furthermore, the coprecipitation method proposed in this work provides a strategy to fabricate other nanostructured composites for different kinds of applications.

We describe aspects of transmission electron microscopy (TEM) technique to image and quantify the defect state following neutron or ion irradiation with an emphasis on experimental considerations. After outlining various neutron and ion irradiation scenarios, including some sample preparation suggestions, we discuss methods to measure defect densities, size distributions, structures, and interstitial or vacancy nature. The importance of the image simulations of Zhou is suggested for guidance to the most accurate quantification of the defect state. It is hoped that the usefulness of the present paper will be greatest for those experiments that compare defect states in materials after different irradiation conditions, or especially those studies designed to benchmark advanced computer model simulations of defect production and evolution. The successful simulation of the defect state in bulk samples neutron irradiated to high dose at high temperature is a goal to which the suggestions in this paper can contribute.

Predicting the impact of cross-links on the mechanics of carbon nanotube-based materials is a challenging endeavor, as the micro- and nanostructure is composed of continuous nanofibers, discontinuous interfaces, and covalent bridges. Here we demonstrate a new modeling solution in the context of the distinct element method (DEM). By representing nanotubes as bonded cylinder segments undergoing van der Waals adhesion, viscous friction, and contact bonding, we are able to simulate how cross-linking transforms a soft bundle into a strong one. We predict that the sp3-sp cross-links formed by interstitial carbon atoms can improve the tensile strength by an order of magnitude, in agreement with experiment and molecular dynamics simulations. The DEM methodology allows performing the multiscale simulation needed for developing strategies to further enhance the mechanical performance.

A novel strain-rate jump method was developed for the plane-strain bulge test and used to investigate the time-dependent deformation behavior of gold thin films in the thickness range 100–400 nm. The experimental method is based on an abrupt variation of the pressurization rate. The evaluated strain-rate sensitivity was found to be five times higher for films in freestanding condition (m = 0.094) than for films tested on a SiNx substrate (m = 0.020). Bulge creep tests confirmed this increased time-dependence. The observation of the surface of the freestanding films after the creep tests provided evidence of apparent grain boundary sliding taking place next to intragranular plastic deformation. The out-of-plane deformation was presumably favored by the columnar microstructure of the samples, with grains extending between both free surfaces. In the case of SiNx-supported films, grain boundary sliding was prevented by the good adhesion of gold to the SiNx substrate.