Ti–Si–C–N thin films were deposited onto WC-Co substrates by industrial scale arc evaporation from Ti3SiC2 compound cathodes in N2 gas. Microstructure and hardness were found to be highly dependent on the wide range of film compositions attained, comprising up to 12 at.% Si and 16 at.% C. Nonreactive deposition yielded films consisting of understoichiometric TiCx, Ti, and silicide phases with high (27 GPa) hardness. At a nitrogen pressure of 0.25–0.5 Pa, below that required for N saturation, superhard, 45–50 GPa, (Ti,Si)(C,N) films with a nanocrystalline feathered structure were formed. Films grown above 2 Pa displayed crystalline phases of more pronounced nitride character, but with C and Si segregated to grain boundaries to form weak grain boundary phases. In abundance of N, the combined presence of Si and C disturbs cubic phase growth severely and compromises the mechanical strength of the films.

The electromigration (EM) behavior of the Cu/Sn–In/Cu solder model strip was investigated under the conditions of high electrical current density (10 kA/cm2) at various temperatures. The composition of indium (In) was 0, 4, 8, and 16 in wt%. The interconnection of Sn–In solder alloys with a Cu substrate was prepared by reflow soldering at 250 °C. Microstructural analysis confirmed that primary intermetallic compound formed at the interface of the Cu/Sn–In strip was Cu6(In,Sn)5 regardless of In contents. Sn grain size became finer as In content increased. After current stressing, electrical failure was caused by the formation of voids and cracks at the cathode because of the migration of Cu atoms. Sn–16In alloy that has fine grain structure exhibits excellent EM resistance primarily due to the retardation of Cu migration.

A single step gas phase method was developed to synthesize silica-coated iron oxide nanocomposite materials in a furnace aerosol reactor (FuAR) using premixed precursors. Synthesis of single component silica and magnetic iron oxide was studied to understand the decomposition mechanism of the precursors, identify the product crystal phase, and optimize the viable operating conditions for the controlled synthesis of nanocomposite material with desirable crystal phase, size, and morphology. The single component decomposition results are further extended to synthesize silica-coated magnetic iron oxide nanocomposite material using premixed precursor. A mechanism was proposed to explain the formation of SiO2-coated γ-Fe2O3 nanocomposite in a single step in a FuAR based on chemical kinetics and was verified by supporting characterization results. The synthesized magnetic γ-Fe2O3/SiO2 nanocomposite material was further tested for suspension stability, magnetic properties, and surface reactivity and was compared with uncoated γ-Fe2O3 nanoparticles to demonstrate improved surface properties.

The interplay of large strain and large strain rate during high-rate severe plastic deformation (HR-SPD) lead to dynamic temperature rise in situ that engenders a recovered microstructure whose characteristics are not just a function of the strain, but also of the strain rate and the coupled temperature rise during the deformation. In this work, we identify three classes of microstructures characterized by multistage recovery phenomena that take place during the high strain rate SPD of Cu. It is found that the first stage of this recovery is similar to the first stage of static recovery, which is characterized mainly by annihilation of dislocations. The second stage starts around 360 K and was characterized by dislocations getting arranged in tight cell boundaries and eventually into subgrain. Recovery stages were found to be followed by a stage of grain growth and recrystallization when the temperature in the deformation zone approaches 480 K.

The optimum glass formers in ternary La-TM-Al (TM = Co, Ni, Cu) alloys were pinpointed at alloys La69Co17Al14, La66Ni19Al15, and La66Cu20Al14, exhibiting critical sizes for full glass formation of 16, 12, and 5 mm, respectively. Cobalt is found to be the most favorable element for glass formation in La-based alloys. The optimum alloys in La-TM-Al show close composition but significantly different glass-forming ability (GFA). The mechanism of distinct effect of TM elements remains unclear, even discussed based on current GFA-related criteria and indicators.

In this study, bulk and multifoil diffusion couple experiments were conducted to examine the interdiffusion process in Ni–Pt and Co–Pt binary alloy systems. Inter-, intrinsic-, and tracer-diffusion coefficients at different temperatures, and as a function of the composition, were estimated by using the experimental data. Results show that in both the alloy systems, Pt is the slower diffusing species, and hence the interdiffusion process is controlled by either Ni or Co. The thermodynamic driving force makes the intrinsic diffusion coefficients of Co and Ni higher in the range of 30–70 at.%. The low activation energy for Co and Ni impurity diffusion in Pt compared with Pt in Ni and Co indicates that the size of the atoms plays an important role. The vacancy wind effects on the diffusion process are examined in detail, and it was demonstrated that its contribution falls within the experimental scatter and hence can be neglected.

An atomistic scheme is developed based on constructed n-body potential to investigate the glass-forming composition region and atomic configurations in Ni–Zr–Ti system. The glass-forming ranges derived from the n-body potentials through molecular dynamics simulations for the binary Ni–Zr, Ni–Ti, Zr–Ti, and ternary Ni–Zr–Ti systems turns out to be very compatible with theoretical studies and experimental observations. Moreover, the coordination numbers (CNs), microchemical inhomogeneity parameter, and Honeycutt and Anderson pair analysis are also computed to exam the local atomic configurations during crystal-to-amorphous phase transition. It is found that average total CNs of amorphous phases are significantly larger compared with those in solid solution counterparts, owing to the increased fractions of CNs from 13 to 16. A tendency in forming the chemical short-range orders also exists in binary and ternary metallic glasses in the Ni–Zr–Ti system and icosahedra-related atomic configurations play important role in forming those orders.

This research investigates the combination of electrochemical deposition and postdeposition vapor annealing as a method for the fabrication of Bi2Te3 layers. The galvanostatic deposition of Bi2Te3 thin films is characterized as a function of electrolyte composition and deposition-current density. Material with near-stoichiometric composition can be synthesized from electrolytes containing 20 mM Te and 30 mM Bi ions and a deposition-current density of 3.75 mA/cm2. All deposited samples show n-type behavior with Seebeck coefficients around −55 μV/K. An equilibrium annealing process in Te atmosphere is used to readjust the composition of the material after the deposition, consistently leading to tellurium-rich Bi2Te3 with a Te content of 60.4 ± 0.4 at%. At a temperature of 250 °C, an annealing duration of 60 h is sufficient for the material properties to reach a steady state, with a Seebeck coefficient of −130 μV/K.

Experimental and simulation studies have shown that decreasing the grain size below a critical value results in softening rather than hardening in both the yield stress and flow stress of nanomaterials. In this work, a gradient plasticity framework is presented that can capture this softening behavior by treating grain boundaries as a separate phase with a finite thickness. The theoretical expression obtained for the yield stress as a function of the grain size can capture numerous experimental data that exhibit this “normal” to “abnormal” Hall–Petch transition, and an analytical equation is obtained that can predict the grain size at which this transition occurs. Furthermore, analytical expressions are obtained for the flow stress in nanomaterials, and they are in precise agreement with atomistic simulations on nanocrystalline Cu, which predict that below a critical grain size the flow stress decreases proportional to it.

The temperature dependence of the various electric relaxation times in the perovskite oxide CaCu3Ti4O12 (CCTO) is determined (i) by trap state spectroscopy and (ii) by the dielectric loss function. A similarity in both number and properties of the (i) and (ii) relaxation times was found, suggesting that the dielectric response is strongly correlated with the trap state relaxation, although some differences remain. One or more dipoles developing charged trap states are considered responsible, and the experimental dielectric response of CCTO and Mn substituted CCTO are explored.

Vanadium oxide nanowires have gained increasing interest as the electrode materials for Li-ion batteries. This article presents the recent developments of vanadium oxide nanowire materials and devices in Li-ion batteries. First, we will describe synthesis and construction of vanadium oxide nanowires. Then, we mainly focus on the electrochemical performances of vanadium oxide nanowires, such as VO2, V2O5, hydrated vanadium oxides, LiV3O8, silver vanadium oxides, etc. Moreover, design and in situ characterization of the single nanowire electrochemical device are also discussed. The challenges and opportunities of vanadium oxide nanowire electrode materials will be discussed as a conclusion to push the fundamental and practical limitations of this kind of nanowire materials for Li-ion batteries.

The Si–P system at high temperatures up to 6 wt%P was investigated. Silicon–phosphorus alloys were prepared through the melting of silicon–phosphorus mixtures in closed silica tubes. Microstructural studies indicated two phases in the alloys, i.e., a solid solution of P in Si and the intermediate compound SiP. Thermal analysis technique was applied to study the phase transformations in the alloys at elevated temperatures. It was observed that SiP is melted at 1139 ± 2 °C. A eutectic reaction in the system, in which liquid Si–P alloy is transformed to SiP and a solid solution of P in Si was observed at 1129 ± 2 °C. Moreover, the liquidus and solidus on the silicon-rich part of the phase diagram were determined as:

Solidus: TS = −75.03 CP + 1414 (°C) 0.35 < CP < 1 wt%P

Liquidus: TL = −6.74 CP + 1414 (°C) CP < 6 wt%P

The distribution coefficient of P in Si was calculated as k0 = 0.09 using the obtained solidus and liquidus at low concentrations.

Sn/Ni–8.0 at.%V (Ni–7.0 wt%V) couples are prepared and the interfacial reactions at 210 and 250 °C are examined. In the early stage of reaction at 250 °C, a T phase is formed as a result of fast diffusion of Sn into the Ni–8.0 at.%V substrate. With a longer reaction, the outer region of the T phase transforms to a Ni-depletion layer, which has not been observed previously. Both the T phase and the Ni-depletion layer are analyzed using transmission electronic microscopy. This newly found Ni-depletion layer is composed of Sn and nanosize “VSn2(V2Sn3)” particulates. The solid/solid reaction paths in the Sn/Ni–8.0 at.%V couples evolve from Sn/T/Ni–V, Sn/Ni3Sn4/T/Ni–V to Sn/Ni3Sn4/VSn2(V2Sn3). During the liquid/solid reactions, the paths are liquid/T/Ni–V, liquid/liquid + Ni3Sn4/T/Ni–V, liquid/liquid + Ni3Sn4/liquid + VSn2(V2Sn3)/T/Ni–V, and liquid/liquid + Ni3Sn4/liquid + VSn2(V2Sn3).

Core–shell structured Sn/carbon nanotube (CNT) was prepared by one-pot chemical vapor deposition (CVD) method in N2/C2H2 (10% C2H2) using nanosized SnO2 as the starting material. The obtained one-dimensional material is composed of a disordered carbon shell and a single-crystalline Sn nanorod core. The diameter of the Sn nanorod and the thickness of the carbon shell are around 40–50 and 4–5 nm, respectively, when the CVD reaction was carried out at 650 °C for 2 h. The core–shell structured Sn/CNT exhibits improved electrochemical performance compared with bare Sn with a diameter of around 100 nm. A reversible capacity of around 350 mAh/g can be retained after 20 cycles at 50 mA/g for Sn/CNT, while for bare Sn, the capacity drops rapidly to 100 mAh/g after the same cycles.

Surface-enhanced Raman scattering (SERS) coupled with micro- or nanofluidics integrated into optofluidic devices offer many advantages over conventional SERS conducted under static conditions. Higher reproducibility, larger intensity, as well as greater enhancement can be achieved by efficient mixing of analytes and SERS enhancers under a continuous flow. Progress and advances in the past 10 years, including the design of channels and efficient mixing conditions, assemblies of SERS substrates for optimal enhancement, and advantages of optofluidic-SERS analysis, are reviewed. Recent results show that optofluidic-SERS effectively overcomes many of the difficulties and limitations plaguing conventional SERS and the novel technique has enormous application potential.

Static electropulsing-induced phase transformations of a cold-drawn ZA27 alloy wire were studied by using x-ray diffraction, backscattered scanning electron microscopy, and electron backscattered diffraction (EBSD) techniques. By using EBSD, phases with close microstructure are discriminated, based on transmission electron microscopy determined lattice parameters of phases. Thus, it was quantitatively detected that electropulsing tremendously accelerated phase transformations in two stages: (i) η′S and ε′T decomposed sequentially (in a way of quenching) and (ii) ε′T and η′S formed via reverse decompositions (in a way of up-quenching).

Regenerated silk fibroin (RSF) fibers were directly dry-spun from RSF aqueous solutions into air. To improve mechanical properties of fiber, the as-spun fibers were postdrawn in 80 vol.% ethanol aqueous solution, in which an immersion process was performed subsequently. With the increase in draw ratio, the fibers show substantial improvements of orientation and mechanical properties. Quantitative analysis of Fourier transform infrared spectroscopy indicates that the ratio of β-sheet to α-helix conformation increases sharply at the beginning of immersion process, then approaches a constant value after 90 min of immersion. All fibers exhibit very smooth surfaces. There is no obvious relationship between the pH of the spinning dope and the mechanical properties of the regenerated fibers. The breaking stress of the posttreated fiber is improved up to 301 MPa, which approaches that of degummed silk. The posttreated fiber is over three times the breaking energy of degummed silk.

We have demonstrated that the microstructure of thick pentaerythritol tetranitrate (PETN) films can be controlled using physical vapor deposition by varying the film/substrate interface. PETN films were deposited on silicon and fused silica with and without a thin layer of sputtered aluminum to demonstrate the effects of the interface on subsequent film growth. Evolution of surface morphology, average density, and surface roughness as a function of film thickness were characterized using surface profilometry, scanning electron microscopy, and atomic force microscopy. Significant variations in density, pore size, and surface morphology were observed in films deposited on the different substrates. In addition, x-ray diffraction experiments showed that while films deposited on bare fused silica or silicon had only weak texturing, films deposited on a sputtered aluminum layer were highly oriented, with a strong (110) out-of-plane texture.

Based on a citric acid-assisted hydrothermal method, series of Ce3+/Tb3+ activated fluorides have been synthesized. By controlling the amount of KNO3, the final products evolve from the Ce3+/Tb3+ codoped orthorhombic phase GdF3 to the Ce3+/Tb3+ codoped cubic phase KGdF4. The concentration of Ce3+ has great effects on the crystalline phases and the morphologies of final products. The Ce3+ concentration dependent samples illustrate the appearance of the hexagonal phase solid solution CeF3–GdF3–TbF3 in the final products. When the Ce3+ concentration is 20 mol%, the sample Ce20 presents the hexagonal phase CeF3 but the diffraction peaks move to higher degree. The x-ray diffraction patterns suggest the phase evolution of final products, the field emission scanning electron microscopy images present the variation in morphology of samples, and the photoluminescence excitation and emission spectra as well as the luminescent dynamic curves illustrate the optical properties of samples.

In reactive templated grain growth (RTGG), oriented template crystals are used to seed both phase formation and crystallographic orientation in textured ceramics. This mechanism differs substantially from templated grain growth (TGG), in which texture forms via grain growth mechanism. In this work, characteristics of both RTGG and TGG processes are evaluated in [001] textured Sr0.61Ba0.39Nb2O6 ceramics produced from reactive SrNb2O6 and BaNb2O6 matrix powders and acicular KSr2Nb5O15 (KSN) templates. Above 1100 °C, SrxBa1−xNb2O6 (SBN) forms by oriented nucleation and growth on KSN (the RTGG process) and by nucleation of nonoriented matrix grains. RTGG occurs without densification or coarsening until phase formation is complete (∼1250 °C) and accounts for ∼60% of the texture in dense SBN ceramics. A later TGG process occurs from 1250–1350 °C and is characterized by simultaneous densification, grain growth, and additional texture development.