Hydrothermal approach is widely used for the synthesis of zinc oxide (ZnO) nanowires. Zinc nitrate hexahydrate, zinc acetate and zinc chloride are three common salts that are used for synthesis. Among these, zinc nitrate hexahydrate is primarily used in many studies and zinc chloride is preferred for electrodeposition. In this work, zinc acetate dihydrate salt is used for the growth of ZnO nanowires and the effects of time, temperature, solution concentration and concentration ratios of the precursor chemicals are investigated. It is found that the growth time and solution concentration control the lengths of the nanowires, whereas the precursor concentration ratio and solution concentration control their diameter. High solution concentrations and high zinc acetate dihydrate concentrations lead to the development of thin film morphology. Optimum growth parameters are obtained and suggested for the use of zinc acetate dihydrate as a zinc source for growing ZnO nanowires with high aspect ratio (AR). The use of zinc acetate dihydrate leads to the formation of ZnO nanowires without impurities and eliminates the need for using extra capping agents.

High-power impulse magnetron sputtering (HiPIMS) is a promising sputtering-based ionized physical vapor deposition technique and is already making its way to industrial applications. The major difference between HiPIMS and conventional magnetron sputtering processes is the mode of operation. In HiPIMS the power is applied to the magnetron (target) in unipolar pulses at a low duty factor (<10%) and low frequency (<10 kHz) leading to peak target power densities of the order of several kilowatts per square centimeter while keeping the average target power density low enough to avoid magnetron overheating and target melting. These conditions result in the generation of a highly dense plasma discharge, where a large fraction of the sputtered material is ionized and thereby providing new and added means for the synthesis of tailor-made thin films. In this review, the features distinguishing HiPIMS from other deposition methods will be addressed in detail along with how they influence the deposition conditions, such as the plasma parameters and the sputtered material, as well as the resulting thin film properties, such as microstructure, phase formation, and chemical composition. General trends will be established in conjunction to industrially relevant material systems to present this emerging technology to the interested reader.

A TiO2/carbon nanotubes (TiO2/CNTs) composite was synthesized by chemical vapor deposition method with in situ growth of CNTs using hydrothermally treated TiO2 as the starting material. The nanocomposite was characterized by powder x-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy, high-resolution transmission electron microscopy, Raman spectrum, and nitrogen adsorption/desorption isotherms and was investigated as an anode material for lithium-ion batteries. The underlying mechanism for the improvement was analyzed by cyclic voltammetry and electrochemical impedance spectroscopy. The in situ synthesized composite showed better electrochemical performance than the pristine TiO2. The in situ formed CNTs not only supply an efficient conductive network but also keep the structural stability of the TiO2 particles, leading to improved electrochemical performance.

A common fingerprint of the electrically active point defects in semiconductors is the transition among their localized defect states upon excitation, which may result in characteristic absorption- or photoluminescence spectrum. Identification of such point defects by means of density functional theory (DFT) calculations with traditional (semi) local functionals suffers from two problems: the “band gap error” and the many-body nature of the electron-hole interaction of the excited state. We show that non local hybrid density functionals may effectively mimic the quasiparticle correction of the band edges and the defect levels within the band gap in group-IV semiconductors, thus they can effectively heal the “band gap error.” The electron-hole interaction can be calculated by time-dependent DFT (TD-DFT) method. Here, we apply TD-DFT on three topical examples: nitrogen-vacancy defect in diamond, silicon-vacancy and divacancy defects in silicon carbide that are candidates in effective development of solid-state quantum bits.

Dielectric measurements (permittivity and hysteresis loop) of monocrystals of bis-thiourea pyridinium bromide inclusion compound have revealed for the first time ferroelectric properties of the studied samples. In the present article, a model of ferroelectric ordering on the basis of single-crystal x-ray diffraction data is described. In the low-temperature phase, the spontaneous polarization is directed along the a axis and ferroelectricity is of the mixed type (displacement and order-disorder component), whereas in the intermediate phase the spontaneous polarization is directed along the c axis and ferroelectricity is of the order-disorder type.

Although atomic layer deposition (ALD) has been used for many years as an industrial manufacturing method for microprocessors and displays, this versatile technique is finding increased use in the emerging fields of plasmonics and nanobiotechnology. In particular, ALD coatings can modify metallic surfaces to tune their optical and plasmonic properties, to protect them against unwanted oxidation and contamination, or to create biocompatible surfaces. Furthermore, ALD is unique among thin film deposition techniques in its ability to meet the processing demands for engineering nanoplasmonic devices, offering conformal deposition of dense and ultrathin films on high-aspect-ratio nanostructures at temperatures below 100 °C. In this review, we present key features of ALD and describe how it could benefit future applications in plasmonics, nanosciences, and biotechnology.

The effect of Mn incorporation into lead titanate (PbTiO3, abbreviated as PT) host lattice is being studied, and the corresponding variation with regard to tetragonality, radiative emission, and ferroelectric response is highlighted. The Mn doping has a weak dependency on the average crystallite size and is found to be within 34–39 nm for both Mn-free and Mn-included PT nanostructures. The tetragonality (c/a ratio) is found to increase with Mn level thus giving a maximum value of 1.061 for 10% Mn doping (Mn/Ti = 0.1). Further, a prominent splitting of (001) and (100) peaks in the diffractograms confirms the tetragonal characteristics of PT nanosystem. Apart from the luminescence peaks due to direct electron deexcitation and the localized states observable in the violet and blue regimes, the association of Mn2+-related orange–red emission (λ = 580 nm) was observed for Mn-incorporated PT systems. The P-E hysteresis trace exhibited a minimum tilting of ∼28° for a system that contained 10% Mn level. As a consequence of polarization switching, the effect of Mn content on remnant polarization and critical field is discussed in the light of domain wall motion and depolarization field due to surface dielectric layers. The injection of magnetic ions into nanoscale ferroelectrics is promising, which would bring insight to the understanding of charge–spin interactions for application in polarization reversal/switching elements.

Solid solutions of Ba1−xPbxZrO3 (0 ≤ x ≤ 0.75) have been synthesized successfully by polymeric citrate precursor method for the first time. The solid solutions were characterized by powder x-ray diffraction (XRD), scanning electron microscopy, transmission electron microscopy, and surface area studies. XRD studies reveal the monophasic nature of these highly crystalline nanoparticles (except few impurity of ZrO2 in PbZrO3). Lattice parameter of Ba1−xPbxZrO3 (0.20 ≤ x ≤ 0.75) decreases with increasing the Pb content. Dielectric properties of these nanoparticles were investigated as a function of frequency and temperature. The dielectric constant for x = 0.15 showed a maximum value of 75.5.

Polypropylene–clay (Cloisite Na+) composites with clay contents in weight percentage (wt%) ranging from 1 to 15% were characterized for crystallization mechanism and kinetics. Combination of differential scanning calorimetry, transmission electron microscopy (TEM), and polarized light microscopy was used to investigate the crystallization behavior. Different crystallization mechanisms were observed in the matrix with 1–5 wt% nanoclay compared to the matrix with 10 and 15 wt% of nanoclay additive. TEM micrographs revealed intercalated and flocculated morphology for all the concentrates. At lower wt%, well-dispersed clay platelets acted as antinucleating agent and reduced polymer chain mobility. At high wt%, nucleation rate overcomes the slow diffusion rate. In the case of samples with higher wt% of nanoclay additives, segregation and precipitation of clay was observed in the interspherulite region. On the basis of crystallization kinetics and morphology results, a schematic model of the nanocomposite formation is proposed.

This study investigates spherical indentation of plastically graded materials (PGMs). The hardness of these materials decreases with depth due to microstructural or compositional changes. To predict the behavior of PGM, the knowledge of the plastic properties of the surface and the substrate is necessary. In this work, the spherical indentation technique is applied on carbonitrided steels to obtain their mechanical properties. First, spherical indentation was applied to characterize homogenous materials using inverse analysis. The comparison with tensile test’s results shows that the inverse analysis using spherical indentation data is a reliable method to determine the plastic properties of homogeneous materials. In the second part spherical indentation was used to characterize carbonitrided steels using inverse analysis to obtain plastic properties of the surface. The results show that spherical indentation using inverse analysis has a real potential for evaluating mechanical properties of PGM.

Copper–zinc alloy (Cu/Zn) powders with different Zn to Cu molar ratios were prepared by the combustion synthesis technique using a CuO + 0.15(C2H4)n + kZn (0.2 ≤ k ≤ 1.6 mol) reactive mixture. Depending on the Zn concentration, the combustion wave developed a temperature between 950 and 1040 °C and passed through the sample with a speed of 0.04–0.08 cm/s, resulting in almost single-stage temperature distributions. Cu/Zn alloy powders with Zn concentrations ranging from 0.5 to 45 wt% were obtained. It was shown that alloy particles become spherical and well dispersed with increasing Zn concentration. Inert dilution test with KCl salt was also performed to determine the influence of temperature degradation in the combustion wave on the morphology and composition of alloy powders.

The illumination instabilities of nanocrystalline ZnO thin-film transistors (TFT) with HfO2 gate dielectrics are reported via zero gate bias multiwave length illumination stress method. TFT ID–VG curves exhibit a negative threshold voltage shift together with an increase in ID off current and increase in subthreshold slope with increasing photon energy and illumination time. Analysis of transistor characteristics indicates that one component governing negative threshold voltage shifts is a decrease in grain boundary-trapped charge areal density due to illumination. This relationship can be explained by conduction based on thermionic emission over potential barriers formed at the ZnO crystallite boundaries. ID off-state current trends with photon energy in a manner consistent with exponentially decreasing absorption below the conduction band edge.

In this work, a novel core–shell structured hybrid graphene oxide-encapsulated silica (GO–SiO2) was first fabricated via an electrostatic assembly between negatively charged graphene oxide (GO) sheets and positively charged sub-micro-sized silica. Then, the new kind of hybrid filler was used for the in situ preparation of poly(ethylene terephthalate) (PET)/GO–SiO2 composites. The microstructure and mechanical properties of the prepared composites were analyzed by scanning electron microscopy, transmission electron microscopy, thermogravimetric analysis, dynamic mechanical analysis measurements, and tensile test. It was found that GO could be covalently assembled onto the subsized silica surface via its plenty of functional groups that can also provide strong interaction with the PET. As a result, a uniform dispersion of GO–SiO2 hybrids and enhanced interfacial adhesion as well as improved mechanical property have been evidenced. The new concept of using GO as a potent inorganic fillers surface modifier may broaden the use of GO and provides a new idea for the design and fabrication of advanced polymer composites.

With regard to the micromechanical characterization of particle–matrix composites like Li-ion electrode materials, we utilized nanoindentation technique as a method for quantifying the Young’s modulus of a single ceramic particle with a diameter of a few micrometers, which was embedded in a softer polymeric matrix. For the experiments, we used reference composites having high Young’s modulus and high hardness ratios of up to 100 (particle/matrix) and filler contents of 10 and 80 vol%. We further performed finite element simulations to understand the indentation process of single particles. It was found that depending on filler content, particle size, and particle/matrix properties, a significant error up to 75% may occur when characterizing single particles by nanoindentation. We finally propose a framework by using standard nanoindentation methods with conventional data analysis as well as an additional postprocess evaluation to determine the Young’s modulus of single particles and we discuss its limitations.

The local mechanical properties of ferritic and austenitic domains in a duplex stainless steel are locally studied by nanoindentation. The elastic and plastic properties of the two phases are determined. Without any specific surface treatment (chemical or electrochemical), the austenitic and ferritic domains present in the duplex stainless steel are distinguished using magnetic force microscopy. The magnetic scans allow nanoindentation results to be assigned to the respective phase, yielding the local mechanical properties of the duplex steel. The magnetic scans also show a sharp transition between the phases that is maintained even inside indentations. The ferrite phase is found to supersede austenite in the elastic modulus, hardness, and strain-hardening exponent, while both phases possess similar yield strength. Interface properties are a weighted average of the phase properties.

A hyperbranched epoxy resin has been synthesized by using epichlorohydrin, bisphenol-A, and hyperbranched polyether polyol by a low-temperature polycondensation technique in the presence of a base. The reaction parameters of this polycondensation reaction were optimized, and 5 N aqueous sodium hydroxide solution, (54 ± 1) °C reaction temperature and 3 h reaction time were found to be the best. The degree of branching of the resin was found to be 0.57 as determined from 13C nuclear magnetic resonance spectroscopy (Fig. 3). This hyperbranched epoxy resin was cured with poly(amido amine) hardener at 120 °C for a specified period of time. The resin exhibits very good crosscut adhesive strength (100%). The cured films showed moderate impact strength (60 cm), good scratch resistance (5.5 kg), good gloss (82 at 60°), thermostability up to 270 °C, and good chemical resistance in various chemical media. All these results indicate its suitability to be used as an advanced surface coating material.

Depending on the application of nanoparticles, certain characteristics of the product quality such as size, morphology, abrasion resistance, specific surface, and tendency to agglomeration are important. These characteristics are a function of the physicochemical properties of the nanostructured material and, thus, of the process parameters of the particle synthesis. Because of econimical reasons in large-scale production such as pyrolysis or precipitation processes, nanosized particles are produced not as single primary particles but rather as aggregates or agglomerates. The application properties of these aggregates are strongly affected by the micromechanical properties, which can be measured via nanoindentation. In this study, a flat punch method was used. For the measurements, model aggregates out of sol–gel produced silica with varying primary particle size and strength of solid bonds were used. Generally, the micromechanical properties can be characterized by measuring the micromechanical properties via nanoindentation and be described by different theoretical models.

The Bosch process is a high-speed, deep reactive ion etching technology for silicon, which has both excellent flexibility and selectivity. For better understanding and control of the time evolution of the feature profile during the Bosch process, an accurate, predictive, and fast simulation tool would be useful. In this article, a simplified model for three-dimensional simulation of the Bosch process is proposed. Etching is modeled by an isotropic etching rate superposed by an anisotropic term. For the passivation cycle, a perfect conformal deposition is assumed corresponding to a constant deposition rate. Level set method was used for tracking the surface evolution. Since the etching and deposition rates are the model input parameters which are not computed, the computational time is significantly reduced. Calculation results presented here illustrate some typical applications of the Bosch process.

We studied the correlation between shear-induced crystallization and rheological behavior of syndiotactic polystyrene. It was found that after applying a steady shear flow around the nominal melting temperature (Tm = 270 °C), crystal growth rate was accelerated compared with the quiescent state and a morphology of oriented lamellae (kebabs) was observed. On the other hand, no obvious morphological change was observed when applying a shear flow with relatively slow shear rate. We discussed a possibility that the difference of crystal growth rate and morphology could be attributed to the competition between shear rate and relaxation time such as reptation time. Our rheological results suggested that when the imposed shear rate is close to the reciprocal of reptation time, oriented lamellae (kebabs) are observed but extended-chain crystals (shishs) cannot be formed since the chain segments between adjacent entanglements remain unstretched.

Indentations tests have been performed on two standard materials SiO2 and Si (100) using two Berkovich indenters presenting different tip defects. Estimations of the tip radii deduced from analyses of maximal applied load versus contact depth and stiffness versus contact depth curves have been compared for experimental observation of each indenter tip obtained with atomic force microscopy (AFM). Results indicate that the determination of the tip defect from data extracted form load–displacement curves is partly dependent on the mechanical properties of the tested material. Then, an original study is proposed to evidence the influence of the tip defect on mechanical response during indentation. Experimental AFM observations of the tip indenter geometries have been introduced in finite element software MSC MARC to reproduce indentation tests on bulk material surfaces. We demonstrated at very shallow penetration depth (less than 50 nm) that the real indenter tip defects have to be considered in the simulation runs, especially to identify accurately the rheological parameters of the tested surface.