In a thin film system involving dissimilar materials, the residual stresses and microstructural defects are inevitable due to the misfits of lattice structures and thermal properties of the materials. Unfortunately, the relationship between the stresses and interface defects is still unclear to date. This article aims to clarify such an important relationship by a finite element (FE) analysis incorporating the dislocation distribution from high-resolution transmission electron microscopy. Layer removal and Raman spectroscopy were also conducted to explore the film-thickness effect. It was found that that residual stress variation in a thin film system is caused by the coupled effect of lattice-thermal misfits and discrete interfacial dislocations, that the residual stresses are dependent on the film thickness, and that it is particularly important to identify the correct density of interface dislocations for an accurate residual stress calculation by a FE analysis.

The present study aims to determine the optimum radio frequency (RF) sputtering power to obtain the desired W–TiO2 nanotubes for the best photoelectrochemical (PEC) performance. Tungsten (W) was deposited on titania (TiO2) nanotube arrays via RF sputtering technique under different sputtering powers from 50 to 250 W. The optimum content of W on TiO2 nanotube arrays play a significant role in maximizing the photocurrent generation efficiency to promote charge separation by accumulation of photogenerated electrons. The sputtering power below 180 W exhibited high-ordered and unbroken TiO2 nanotube arrays. However, the sputtering power over 180 W exhibited broken nanotube arrays and an oxide layer was formed due to the impact of high energy ions accelerated by a high sputtering power. The TiO2 nanotube arrays sputtered with tungsten at 50 W showed a better photocurrent density (1.55 mA/cm2), with a photoconversion efficiency of 2.2% in the PEC performance among the samples due to the effective charge separation and reduced recombination center in the resultant W–TiO2 nanotubes.

Surface-functionalized magnetic nanoparticles were prepared by a facile one-pot solvothermal method in ethylene glycol solution. Zeta value, size, and magnetic properties could be well tuned by introducing different functional group molecules. Characterizations, including transmission electronic microscopy, scanning electronic microscopy, thermogravimetric analysis, x-ray powder diffraction and vibrating sample magnetometer, and Fourier transform infrared spectrophotometer demonstrated the efficiency of this simple and general synthesis strategy. The hydrophilic magnetic nanoparticles with various surface functional groups and zeta values were evidenced as excellent candidates for bioseparation by extracting DNA molecules from a model mixture of cell fractures.

The plane strain bulge test technique is a powerful and acknowledged technique for characterizing the mechanical behavior of thin films. In a bulge test analysis, the stress and strain are derived from the measured quantities using analytical approximations of the deformed geometry (bulge equations). To improve the bulge test, the systematic error introduced by these approximations is evaluated and quantified by scrutinizing the method on a finite element model of the bulge test, used as an idealized experiment.

Under the COMPASS (condensed-phase optimized molecular potentials for atomistic simulation studies) force field, the molecular dynamics (MD) simulation was applied to first-to-third generation nanosize amine-based and butanediamine-based graphite/dendrimers composites. In this paper, we briefly introduced the constructive process of the composite system by means of MD simulation. The stability and mechanism of six intercalation composites were studied with microcosmic figure and variational energy under the invariable NVT ensemble. The energy variety was analyzed using the radial distribution function. The results indicate that the bulk of the dendrimer is small, the graphite layer is easy to bend and its systematic total energy is higher, which lead to the instability of the composite system. Therefore, the 3G dendrimer is the most stable system.

The proton conducting perovskite MZr1−xLnxO3−δHz ceramics are promising electrolytic membranes for fuel cell and water steam electrolyser applications. Simultaneous elastic/quasielastic and diffraction neutron studies were performed in a wide temperature range (25–1150 °C) on protonated Yb-modified BaZrO3 ceramics: dense (97% of theoretical density) and ultradense (99%) using the triple axis spectrometers. The results allowed us to determine: (i) the real content of bulk protonic species ∼1–5 10−3 mol/mol, (ii) the structural modifications caused by the proton doping, and (iii) the bulk proton dynamics. The quasielastic neutron scattering (QNS) results are discussed in the light of neutron diffraction, conductivity, Raman, thermogravimetric, and thermal expansion measurements. The highest bulk proton motion appears in the temperature range where the structural modifications and the energy activation changes are detected. This allows defining the optimum temperature range for the proton dynamics between 400 and 560 °C.

This article reports on microstructure and dielectric properties of Ba0.5Sr0.5Ti1−3y/2WyO3 ceramics. Dielectric peaks of the Ba0.5Sr0.5Ti1−3y/2WyO3 ceramics were markedly suppressed, broadened, and shifted to low temperature with increasing content of W. The limit of W incorporating into the barium strontium titanate (BST) lattice was y = 0.02. Two second phases (BaWO4 and Ba2Ti5O12) were formed above the solid solution limit of W in BST. The doping mechanism represents a new approach to develop microwave tunable materials. Dielectric properties of the Ba0.5Sr0.5Ti1−3y/2WyO3 ceramics could be optimized by the content of W. The sample with y = 0.05 had ε′ of 431, quality factor of 365 (at 2.111 GHz), and tunability of 11.5%, which makes a potential candidate for tunable microwave device applications in the wireless communication.

Cu6Sn5 is a critical intermetallic compound in soldering operations. Conventional equilibrium phase diagrams show that this compound is of either a hexagonal or monoclinic structure at temperatures above and below 186 °C, respectively. Under nonequilibrium conditions, the crystal structure is dependent on composition, temperature, and processing history. The effect of Zn, Au, and In on the hexagonal to monoclinic polymorphic transformation in Cu6Sn5 intermetallics is investigated using variable temperature synchrotron powder x-ray diffraction and differential scanning calorimetry. It is revealed that, as in the case of trace Ni additions, the alloying elements Zn and Au completely stabilize the hexagonal Cu6Sn5 and prevent the phase transformation. In contrast, In additions only partially stabilize the hexagonal Cu6Sn5.

Low temperature (25 °C–80 °C) synthesis of zinc oxide (ZnO) nanoparticles (<20 nm) at short synthesis periods (∼30 min) was achieved by precipitation. The precipitation system was formed using zinc acetate dihydrate as zinc source, ethylene glycol (EG) as solvent and polyvinyl pyrrolidone (PVP) as chelating agent. The size of spherical ZnO nanoparticles was manipulated by the choice of precipitation temperature (13.0 ± 1.9 nm at 25 °C and 9.0 ± 1.3 nm at 80 °C), which essentially changes the nature of adsorption events between ZnO crystals and organic molecules. The particle size can also be regulated by the amount of chelating agent as a result of further enhancement in adsorption between ZnO crystals and organic additives. The spherical ZnO nanoparticles were agglomerated into triangular form when different solvent was used – by substituting water for EG, which has different adsorption ability. Accordingly, formation and growth mechanisms controlling the size and morphology of ZnO nanoparticles have been proposed.

High permittivity antimony-doped tin oxide (ATO)/polyimide (PI) composite films consisting of narrow size distribution ATO fillers prepared by inverse microemulsion method and PI host are synthesized by in situ polymerization. The microstructure and thermal stability of composite films are characterized by scanning electron microscopy and thermal gravimetric analyses, respectively. Dielectric properties of composite films with different concentrations of ATO particles of variable size are investigated in the frequency range of 102 to 2.5 × 106 Hz. The hydrophilic surface of ATO is not helpful of tight connection between the filler and host. The addition of ATO contributes slight increase of the thermal stability. However, the permittivity of composite films can be remarkably increased due to Maxwell–Wagner–Sillars polarization as well as a large number of tiny capacitors formed by ATO particles with narrow distribution and small size. The dielectric constant behavior of composite films fits well to the usual percolation theory.

Electrical and electrochemical properties of the passive layer formed on 304L austenitic stainless steel are investigated by means of both conductive atomic force microscopy in air and electrochemical atomic force microscopy in chloride-containing media. The maps of local electrical conductivity of the oxide overlayer exhibit different patterns depending on the surface conditions after mechanical or electrochemical polishing. In particular, the passive film covering strain-hardened regions reveals a higher electrical conductivity. The local enhancement of the electrical conduction is explained by local changes of the stoichiometry of the passive film. Moreover, the highly conductive regions lead to a local breakdown of the native oxide in chloride-containing media and favor the initiation of localized pits.

We report synthesis of nanosize LiFePO4 and C-LiFePO4 powders with a narrow particle size distribution (20–30 nm) by ethanol-based sol–gel method using lauric acid (LA) as a surfactant for high specific capacity lithium-ion battery cathode material. X-ray diffraction measurements demonstrated that the samples were single-phase materials without any impurity phases. The average crystallite size was found to decrease slightly from 29 nm to approximately 23 nm with carbon coating. The ratio of the Raman D-band (∼1350 cm−1) to G-band (∼1590 cm−1) intensities (ID/IG) and electronic conductivity of these materials show strong dependence on the amount of surfactant coverage. Remarkably, cell prepared with carbon-coated LiFePO4 synthesized using 0.25 M solution of LA showed a very large specific capacity approaching the theoretical limit of 170 mAh/g, in stark contrast to the specific capacity of cell consisting of pure of LiFePO4 (∼75 mAh/g) measured at the same C/2 discharge rate.

Nanofiber yarns with controlled twist levels were prepared by twisting a narrow fibrous strip cut directly from electrospun nanofiber mats. The effects of fiber morphology, diameter and orientation, as well as the yarn twist level on the yarn tensile properties were examined. For the yarns made from randomly oriented fine uniform nanofibers (e.g., diameter 359 nm) and beaded nanofibers, the tensile strength increased with increasing the yarn twist level. Higher fiber diameter (e.g., 634 nm) led to the tensile strength having an initial increase and then decrease trend. The modulus increased with the twist level for all the yarns studied. However, the elongation at break increased initially with the twist level and subsequently decreased. The orientation of aligned fibers within the fiber strip greatly influenced the yarn tensile properties. When the fibers were oriented along the fiber length direction, both tensile strength and modulus were the largest.

We have created hybrids of functionalized single wall carbon nanotubes (fSWCNTs) and also multiwall CNTs (fMWCNTs) with PBT/PTMO, a block copolymer of semicrystalline poly(butyl terephthalate) (PBT) with amorphous oxytetramethylene (PTMO). For both single wall (SW) and multiwall (MW) carbon nanotubes (CNTs) tensile modulus and strain at break as a function of CNTs’ concentration (cCNT) show maxima. Elongation at break is enhanced by the nanotubes, a plasticizing effect—much stronger for SWCNTs because they have less contact points per unit area with the matrix and also are more flexible. Repetitive tensile tests were also performed; each loading cycle resulted in lowering the tensile modulus. Brittleness B(cCNT) diagrams show minima. New results for CNT hybrids fit an earlier general diagram for determination of viscoelastic recovery in sliding wear (f) as a function of brittleness (B); the original equation with unchanged parameters covers also these results. Volumetric wear was determined after abrasion on a pin-on-disk tribometer. Minima are seen on the volumetric wear versus cCNT diagrams, similar to those on the B(cCNT) diagrams.

Multiwalled carbon nanotubes (MWCNTs) obtained using ethylene as a carbon source and nanocrystalline iron as a catalyst were used as the initial material. The functionalization of MWCNTs was carried out using chlorine in the liquid and gas phase. In the second case, the reaction was conducted in the temperature range from 50 to 450 °C for 2 h. The presence of chlorine species on the surface of chlorinated samples was confirmed by x-ray photoelectron spectroscopy (XPS). A quantitative analysis of metal impurity content was validated by means of thermogravimetric analysis. Better results of metal removal were achieved when the chlorination process was conducted in the gas phase and the ratio of metal in samples amounted from 2.3% to 5.1%.

Synthesis of well-defined sodium yttrium fluoride (NaYF4) nanocrystals has been achieved in nonpolar solvents, but these nanocrystals possess a hydrophobic surface and need to be surface-modified for various biological applications. Development of facile aqueous solution method to synthesize one-dimensional NaYF4 with a hydrophilic surface still remains challenging. Herein, we demonstrate a simple route to prepare hydrophilic NaYF4 nanorods by using hydrophobic NaYF4 nanospheres as precursor. It is interesting to find that hydrothermal treatment of oleic acid-capped NaYF4 nanocrystals can not only induce anisotropic growth of these nanocrystals but also change their surface properties. The hydrophilic NaYF4 nanorods synthesized in this work has been well characterized and possible formation mechanism has also been discussed.

Control of the electrical properties of ZnO is difficult to achieve. Doping is affected by the presence of a n-type background. Magnetotransport measurements can extract detailed information on donors and acceptors, but characterization is complicated by effects such as the surface conductivity. This conducting layer can be activated by ambient illumination or by heating in the absence of oxygen. There are considerable differences in the behavior of the various polar and nonpolar crystal faces. This paper provides an overview of the properties of ZnO surface conductivity, as well as the methods which have been implemented to account for it while interpreting carrier transport measurements.

Comparisons of structural, optical, and magnetic properties between KY(WO4)2 (KYW) powders doped with Gd3+ from 0.5 up to 100 mol% and KGd(WO4)2and KYW single crystals have been made. For this purpose, x-ray diffraction (XRD), infrared (IR), Raman, and electron paramagnetic resonance (EPR) spectra were collected. The XRD studies have verified the quality of the synthesis of compounds and have shown the differences in the positions of the diffraction peaks due to the change in concentration of gadolinium ions. Raman and IR spectra confirmed that the phases are isostructural. The optimization of the spin Hamiltonian parameters and EPR data simulation was achieved by using the electron paramagnetic resonance and nuclear magnetic resonance (EPR-NMR) program. Changes in kind of magnetic interactions were found and analyzed from the point of view of their dependence of the compound form (powder, single crystal), temperature, and gadolinium ion concentration. The investigated compounds revealed complex interactions between gadolinium ions both in a type and a strength.

The unique set of mechanical properties found in rigid biological tissues, which combine high strength and stiffness with superior toughness, offer inspiration for the design of advanced functional structural materials with outstanding performance. This paper reports on the first utilization of one such biogenic material—siliceous sponge spicules, the skeletal elements of sponges (Poriphera)—as a unique naturally nanostructured template for vacuum deposition, while also reporting on the effects of the required chemical and thermal treatments for template preparation on the material’s microstructure and mechanical properties. The confined space within the central channel of spicules from the sponge Euplectella acts simultaneously as a nanotemplate and as a biogenic, optically transparent, glassy microchamber for the preparation of micrometer-sized clusters of fullerene-C60 through vacuum deposition onto the nanostructured surface. This biological material allows an unprecedented and unique microporous morphology of C60 particles to be obtained.

A sulfonated activated carbon fiber catalyst (SACF) was prepared through γ-irradiation-induced grafting of styrene onto the surface of activated carbon fiber (ACF) with an irradiation dose of 0.837 kGy/h for 48 h that was then sulfonated with chlorosulfonic acid under mild reaction conditions. Scanning electron microscopy observation showed that the ACF was wrapped by a thin layer of copolymer, and Fourier transfer infrared spectroscopy analysis indicated that sulfonic acid groups were successfully introduced onto the ACF. Pore structure analysis based on nitrogen adsorption isotherms at 77 K demonstrated that pore parameters of ACF were well maintained after the process of grafting and sulfonation modification. Proper conditions for the SACF preparation were sulfonated at 80 °C for 1.5 h in the 20% mass percentage of chlorosulfonic acid solution using ACF precursor, whose acid density could reach 1.47 mmol/g. The sulfonated ACF was used as catalyst for the esterification of acetic acid and ethanol. Evaluation of the catalytic activity of SACF showed evident advantages over other typical catalyst, with a turnover frequency value of 0.780 min−1, about five times higher than Nafion.