Three-dimensional (3D) nanostructures and nanodevices have attracted tremendous interest in the past few years due to their special mechanical and physical properties. Nanodevices using 3D nanostructures as the building blocks have been demonstrated to exhibit multifunctionality and functions that conventional planar devices cannot achieve. In this article, we report and review focused ion beam techniques for direct site-specific growth of 3D nanostructures and postgrowth shape modification of freestanding nanostructures by ion beam-induced chemical vapor deposition and ion-beam-irradiation-induced plastic bending, respectively. Such techniques have shown nanometer-scale resolution and accuracy in the fabrication of metallic nanoelectrodes, 3D pickup coils, nanogaps, and multibranched structures. Characterization of the resulting nanostructures shows that focused ion beam techniques allow conducting and superconducting freestanding 3D structures to be tailored in size, geometry, and integrated with planar electronic, mechanical, and superconducting nanodevices, potentially enabling lab-on-a-chip experiments.

An extended version of self-consistent field (SCF) theory that was recently introduced by the authors [Li et al., J. Chem. Phys.137, 024906, (2012)] is used to study the phase behavior of a polymer blend with reversible crosslinks. The system consists of symmetric AB diblock copolymers and homopolymers of type A and B. We consider reversible crosslinks that can form between the diblock copolymers with a crosslink strength z and crosslink weights ωA and ωB for monomers of type A and B, respectively. Crosslinks between homopolymers are disabled. We present a phase diagram as a function of the A fraction of homopolymers $\phi _{\rm{\alpha }}^{{\rm{rel}}}$, the crosslink strength z, and the crosslink asymmetry ∆ω = ωA − ωB. A hexagonal phase is found for suitably large $\phi _{\rm{\alpha }}^{{\rm{rel}}}$, and suitably small z and $\left| {\Delta {\rm{\omega }}} \right|$. Otherwise the system forms a lamellar phase. A deeper insight into the phase behavior is gained from analyzing the free energy contributions in the hexagonal and the lamellar phase with the help of the capabilities of the extended SCF theory developed by us.

In the present study, polymerizable ionic liquids (ILs), 1-[n-(methacryloyloxy)alkyl]-3-methylimidazolium bromides (n = 2, 6, 7, or 10), were synthesized in high yields. Moreover, the compounds obtained (n = 6, 7, or 10) were used in the preparation of composite materials comprising a polymerized IL matrix and a nonpolymerizable IL additive, 1-ethyl-3-methylimidazolium tetrafluoroborate ([EMIM][BF4]) in various proportions (up to 75% vol/vol of [EMIM][BF4]). The UV-radiation-initiated photopolymerization process was monitored in situ by measuring the resistivities of the mixtures. An increase in [EMIM][BF4] content in the composites led to an increase in the ionic conductivities of the materials while retaining their solid state at levels as high as 40% vol/vol of the [EMIM][BF4] content. The 40% vol/vol composites had conductivities of approximately 10−4 S/cm compared to the conductivities of 10−5 S/cm for the corresponding neat polymerized ILs. Above this [EMIM][BF4] content, the materials were sticky gels, and from 50% vol/vol onwards, entirely liquid.

Benzoxazine resins are a new class of thermosetting phenolic resins that have emerged in recent decades, overcoming the traditional properties of epoxy and phenolic resins applied in the aerospace industry. The incorporation of low mass concentration of carbon nanotube (CNT) in polymer matrices can produce structural materials with superior properties. Thus, this work aims to prepare nanostructured composite benzoxazine resin/CNT and to evaluate the cure kinetic study by differential scanning calorimetry of neat benzoxazine resin and their nanostructured composites produced. Calculations of the activation energy, the reaction order, and kinetic constants are performed by a nonisothermal procedure. In general, it was observed that CNTs act as catalysts for curing the benzoxazine matrix without affecting the initial and final cure temperatures.

In this work, the effects of annealing treatment on the crystalline structure and mechanical property changes of polypropylene random copolymer (PPR) were comparatively investigated. Wide angle x-ray diffraction and differential scanning calorimetry were used to study the crystalline structure evolution of the annealed PPR sample. The relaxation behavior of the annealed PPR sample was analyzed using dynamic mechanical analysis. The mechanical properties and the toughening mechanism were also investigated. The results showed that the crystalline structure evolution of the annealed PPR sample depended on the annealing temperature. Due to the largely increased molecular chain mobility in the amorphous region, which promoted the plastic deformation of the annealed PPR sample under the impact condition, largely enhanced impact strength was achieved at a moderate annealing temperature. Further results showed that relatively shorter annealing duration could induce the apparent changes of crystalline structure and mechanical properties of the PPR sample.

Copper oxide (CuO) nanosheets synthesized in polyvinylpyrrolidone (PVP) were characterized with respect to antimicrobial activity by quick precipitation method. Different sizes and shapes of CuO nanosheets were obtained by simple variations of PVP concentrations. The x-ray diffraction results revealed the formation of pure-phase CuO with monoclinic structure. Transmission electron microscopy analysis showed that the average ratio of length to width of these nanosheets increased with increasing PVP concentrations. Due to the quantum size effect, CuO nanosheets exhibit a blue shift in the ultraviolet-visible spectra. Field emission scanning electron microscopy results showed that as the concentration of PVP increased, well-defined morphologies were formed on the surface of the products. Energy dispersive analysis of x-ray clearly confirmed the presence of Cu and O with an atomic ratio of 1:1. Fourier transform infrared spectroscopy results showed that C=O in PVP coordinated with CuO and formed a protective layer. The mechanism of the reaction was also discussed. CuO nanosheets in suspension showed activity against a range of bacterial pathogens and fungi with minimum bactericidal concentrations (MBCs) ranging from 100 to 5000 µg/mL. The extent of the inhibition zones and the MBCs was found to be size-dependent.

Calcium phosphates (CaPs) are major chemical constituents of mammalian bone. Their osteoconductivity in vitro and in vivo has encouraged their use in biomaterial applications such as implant materials and drug delivery. High aspect ratio nanoparticles are attractive for many biomedical applications; however, precise control of the phase and morphology is challenging. The impact of fuel-to-oxidant ratio, pH, and cation chemistry on morphology and phase was studied for CaP-based compositions by microwave-assisted solution combustion synthesis (MASCS) in a urea–nitrate (fuel–oxidant) system. An initial calcium to phosphate ratio of 1.5 was used. Highly crystalline hydroxyapatite (HA) and biphasic CaP nanoparticle compositions were produced as confirmed by x-ray diffraction, scanning electron microscopy, and transmission electron microscopy. MASCS was capable of synthesizing high aspect ratio (∼5 to 20) single and biphasic CaP nanoparticles with diameters ranging from 250 to 500 nm and lengths between 2 and 10 μm.

A novel Ba2MgMoO6:Eu3+ orange-red phosphor was synthesized by the Pechini method and characterized by x-ray diffraction. Photoluminescence properties of BaMgMoO6:Eu3+ phosphors have been represented in the excitation and emission spectra. The charge transfer (CT) band of Ba2MgMoO6 host is situated at near-ultraviolet (UV) region, whose central wave length and bandwidth are 394 and 80 nm, respectively. And it matches well the emission wave length from near-UV light emitting diodes (LEDs). The most intensive emission of 5D0 → 7F1 (598 nm) of Eu3+ in Ba2MgMoO6:Eu3+ is much narrow with a full width at half-maximum less than 2 nm under excitation with either CT band or 394 nm. And a low concentration quenching occurs in Ba2MgMoO6:Eu3+, and the optimal doping concentration is about 0.05. The mechanism of charge and energy transfer from Ba2MgMoO6 host to Eu3+ is proposed and analyzed on the basis of its crystal structure. In a word, Ba2MgMoO6:Eu3+ may be a promising orange-red component for near UV white LEDs.

The linear elastic recovery measured from the nanoindentation unloading curve of a film/substrate system was used to determine the practical work for delamination using the proposed energy balance method and to estimate the delaminated area using the Hertz contact loaded model. The practical work for delamination was then calculated by dividing the external mechanical work required for generating interfacial crack by the delaminated area. The finite element model simulation demonstrated that the energy method was feasible and the estimation of delamination area using the Hertz model was accurate. The practical works for delamination in the plasma-enhanced chemical vapor deposition SiNx/GaAs film/substrate systems estimated using this method were in the range of 1–2.3 J/m2, which were in reasonably good agreement with those obtained from our another experimental approach.

A systematic study was done to understand the influence of volume fractions and bilayer spacings for metal/nitride multilayer coating using finite element method (FEM). An axisymmetric model was chosen to model the real situation by incorporating metal and substrate plasticity. Combinations of volume fractions and bilayer spacings were chosen for FEM analysis consistent with experimental results. The model was able to predict trends in cracking with respect to layer spacing and volume fraction. Metal layer plasticity is seen to greatly influence the stress field inside nitride. It is seen that the thicker metal induces higher tensile stresses inside nitride and hence leads to lower cracking loads. Thin metal layers <10 nm were seen to have curved interfaces, and hence, the deformation mode was interfacial delamination in combination with edge cracking. There is an optimum seen with respect to volume fraction ∼13% and metal layer thickness ∼30 nm, which give maximum crack resistance.

Zn1.98Mn0.02P2O7 was synthesized by the wet chemical route. The purity of the phase and the oxidation state of manganese ion were investigated by x-ray diffraction (XRD) and electron paramagnetic resonance (EPR). Structural phase transition in α-Zn2P2O7 was investigated by high-temperature XRD (HTXRD), differential scanning calorimetry (DSC), and EPR studies. There is a distinct signature of phase transitions between 390 and 400 K in our powder sample by EPR and HTXRD. There was a sharp reduction in the volume of unit cell, while going from alpha to beta phase; with discontinuity in 405 K, which confirmed the transition to be of first order. Similarly, the effect of temperature on zero-field splitting parameter (D) also showed that there is a sudden jump (discontinuity) in the value at around 400 K (phase transition temperature) confirming the transition to be of first order. DSC studies corroborated these findings.

Solutions to the technical challenge of bonding and joining bulk metallic glasses have long been sought after due to the exceptional property sets displayed by this class of engineering materials. Here, we demonstrate the ability to deposit a compositionally and functionally graded hybrid coupling layer using sol–gel processing methods to promote adhesion at the metallic glass–epoxy interface. In this study, we fine-tune the molecular composition by varying the sol Zr:Si ratio, altering film properties that consequently influence crack path selection at the interface. When optimized, up to 3-fold improvements in the adhesive/cohesive properties of these structural bond lines can be attained, with the highest GC values correlating with cohesive cracking through the hybrid. We also demonstrate the ability of these hybrid structures to significantly reduce the influence of moisture-assisted degradation as evidenced by reductions in crack growth rates of over two orders of magnitude and increased threshold limits.

Great research efforts to investigate the glass-forming ability (GFA) in alloys have been made, leading to an observation that a pinpoint composition produces the best glass-forming characteristics. The reason for this observation is still unknown, limiting the development of bulk metallic glasses (MGs) with a relatively large size. In this work, systematic experimental measurements coupled with calculations were performed to address this issue using the NiNb binary alloy system. It is found that the atomic-level packing efficiency and the clusters-level regularity parameters strongly contribute to their GFA. In particular, the best glass former found in a pinpoint composition possesses the local maximum of the atomic-packing efficiency and the highest degree of the cluster regularity. This work provides an understanding of GFA from atomic and cluster levels and will shed light on the development of more MGs with relatively large critical casting sizes.

This study investigated the microstructure and machining characteristics of a Zr38.5Ti16.5Cu15.25Ni9.75Be20 bulk metallic glass (Zr-BMG) alloy machined using electro-discharge machining (EDM). After EDM, the hardening effect near the outer surface of the electro-discharge machined (EDMed) Zr-BMG alloy originated from the surface carbides of the recast layer, ZrC and TiC. The thickness of the recast layer, crater size, and the surface roughness increased with greater pulse energy. Furthermore, the EDM can generate a porous recast layer and convert the Zr-BMG alloy surface into a carbide surface, which is a potential method to fabricate biomaterials. Experimental results also show that the material removal rate of this alloy in the EDM process was significantly related to the pulse current IP and pulse duration τP. Many electro-discharge craters and recast materials were observed on the surface of the EDMed Zr-BMG alloy. The surface roughness of the EDMed Zr-BMG alloy was found to obey the empirical equation of Ra = β(IP × τP)α.

The liquid impingement erosion behavior of a zirconium-based bulk metallic glass (BMG), Zr44Ti11Cu10Ni10Be25, was evaluated in this study. For comparison, commonly used hydroturbine steel was evaluated under the same test conditions. BMG demonstrated more than four times higher resistance against cavitation erosion compared with hydroturbine steel. The unusually high erosion resistance for BMG is attributed to its uniform amorphous structure with no grain boundaries, higher hardness, and ability to accommodate strain through localized shear bands.

Al–7Si/gray iron bimetal composites with a sound metallurgical bonding were obtained by a gravity die casting process. The surface treatments of the gray iron specimen including fluxing and hot dipping were applied to forming a complete metallurgical bonding layer at the Al–7Si/gray iron interface. In addition, the effect of Mn in dipping bath on the microstructure of the Al–7Si/gray iron interfacial bond zone has been studied in an Al–7Si alloy containing five different levels of Mn ranging from 0 to 5 wt%. Microstructure analysis indicates that addition of Mn in dipping bath can eliminate the harmful needle-like phase (β-Al5FeSi) as the Mn content is no less than 1.5 wt% and also plays an important role in facilitating the growth of intermetallic phases [α-Al15(FexMn1−x)3Si2] and the metallurgical bonding layer. The sound metallurgical bonding formed at the Al–7Si/gray iron interface is attributed to combining the effect of surface treatments and selection of Mn content.