The refractory nature of BaTiO3 leads to limited densification and grain growth for films processed at low temperatures and a modest nonlinear dielectric response due to a marked sensitivity to physical scale and material quality. Adding liquid-forming sintering aids, common in bulk ceramics, to thin films enhances mass transport, leading to enhanced grain growth at lower temperatures. This work explores the effectiveness of a sputtered CuO buffer layer with BaO–B2O3 (BBO) fluxes to engineer the microstructure of BaTiO3 films. Grain size and homogeneity increase in the presence of even a ∼1 nm CuO layer. In general, grain size increases from 75 to 370 nm with an addition of 2.2% BBO and 8 nm CuO. Room temperature capacitance in fluxed films increases by a factor of 5 over pure films, and ferroelectric phase transitions are clearly observable in dielectric measurements. CuO–BBO proves effective on (0001) Al2O3 and (100) MgO substrates, although all microstructures are notably finer for the latter.

We propose a surface integral equation simulation scheme which incorporates the integral equation fast Fourier transform accelerative algorithm and domain decomposition method. Such scheme provides efficient and accurate solutions for substrate-supported non-periodic plasmonic array platforms with large number of building blocks and complex element geometry. The effect of array defects can be systematically and successfully studied taking advantage of the considerable flexibility of the domain decomposition approach. The proposed model will be of great advantage for fast and accurate characterization of graded-pattern plasmonic materials and metasurfaces.

The role of bottom-up and top-down synthesis methods on the nanotribological response of few layer graphene (FLG) in air and various liquid environments is reported. Oxidized FLG adhesion against Si increases by a factor of 2 as compared to non-oxidized samples. Also, it is reported that the FLG center-to-edge adhesion typically exhibits a decreasing tendency. In air, a highly lubricious nanotribological response (0.03–0.04) of both bottom-up and top-down prepared samples is measured. The frictional behavior of bottom-up synthesized FLG in different liquid environments is found to depend on the absence or presence of viscous aggregates in the respective liquid. A Stribeck-like behavior is suggested for viscous synthetic lubricants, such as silicone, present as the third body in the FLG/Si tip system. Such nanoscale behavior, indicating transitions in different lubrication regimes, may be particularly important for the further understanding of liquid–graphene interfaces in novel tribological and device applications.

Recent studies have shown the potential for nanocrystalline metals to possess excellent fatigue resistance compared to their coarse-grained counterparts. Although the mechanical properties of nanocrystalline metals are believed to be particularly susceptible to material defects, a systematic study of the effects of geometric discontinuities on their fatigue performance has not yet been performed. In the present work, nanocrystalline Ni–40 wt%Fe containing both intrinsic and extrinsic defects were tested in tension–tension fatigue. The defects were found to dramatically reduce the fatigue resistance, which was attributed to the relatively high notch sensitivity in the nanocrystalline material. Microstructural analysis within the crack-initiation zones underneath the defects revealed cyclically-induced abnormal grain growth (AGG) as a predominant deformation and crack initiation mechanism during high-cycle fatigue. The onset of AGG and the ensuing fracture is likely accelerated by the stress concentrations, resulting in the reduced fatigue resistance compared to the relatively defect-free counterparts.

Titania nanotube arrays were synthesized electrochemically by anodization of titanium foils, and the synthesized titania nanotubes were then implanted with indium ions. The effect of In-ions implantation on crystallization and phase transformation of titania was investigated using in-situ high-temperature X-ray diffraction and synchrotron radiation diffraction from room temperature to 1000 °C. Diffraction results show that crystalline anatase first appeared at 400 °C in both the non-implanted and the In-implanted materials. The temperature at which crystalline rutile temperature appeared was 600 °C for non-implanted materials and 700 °C for In-implanted materials, and the indium implantation inhibited the anatase-to-rutile transformation. Although In3+ is expected to increase oxygen vacancy concentration and then the rate of titania transformation, the observations are consistent with implanted In-ions occupying the Ti sublattice substitutionally and then inhibiting the transformation. The relatively difficult anatase-to-rutile transformation in the In-implanted material appears to result from the relatively large In3+ radius (0.080 nm). The In3+ partly replaces the Ti4+ (0.061 nm), which provides a greater structural rigidity and prevents relaxation in the Ti bonding environment.

To find the optimal Quenching and Partitioning (Q&P) process parameters of low-alloy wear resistant steel, various Q&P processes including quenching temperature, partitioning temperature and partitioning time were designed and tested by using orthogonal experiment method. Through analysis of orthogonal experiment, quenching temperature was the most important influential factor on the impact toughness and hardness, and partitioning time played a critical role on tensile strength. The optimal Q&P heat treatment parameters of low alloy wear resistant steel were partitioning at 350 °C for 10 min immediately after quenching at 100 °C. The microstructure of samples was composed of martensite laths and retained austenite. The relative volume fraction of retained austenite increased with the increase of quenching temperature and decreased gradually with the lengthening of partitioning time. Combining the results of Energy dispersive spectrometer, the reason for decrease of retained austenite was the existence of carbide precipitation and the carbide was (Fe, Cr)3C7. Compared to the traditional heat treatment of quenching and low temperature tempering, the samples under Q&P treatment displayed higher toughness and maintained relatively high tensile strength and wear resistance.

The effect of strain range on dynamic strain aging (DSA) is discussed based on the low cycle fatigue tests for different strain ranges conducted for 316L stainless steel at strain rate of 1 × 10−3 s−1. The variations of stress drop and hardening ratio are both compared for different strain ranges. The variations of stress drop are attributed to the dependence of vacancy concentration on strain range. The hardening ratio is higher at 600 °C than those at 20 °C and secondary hardening behavior occurs for larger strain range. The dependence of DSA on the number of cycles and the wave type for different stages are analyzed. Obvious DSA is observed in first few cycles, followed by weakening serrated yielding. However, the serrated yielding occurs again before fatigue failure. The difference of serrated yielding can be explained by the types of atom atmospheres at different cycles. A serrated wave is observed for smaller strain ranges, however, A, B, A + B, C, and B + C serrated waves can be found at different cycles for larger strain range. Finally, the crack nucleation and propagation on fracture surfaces are characterized by scanning electron microscope (SEM).

Segmented nanoporous WO3 is prepared via anodization with an electrolyte containing 1 M Na2SO4 and 0.07–0.7 g of NH4F. Annealing (500 °C for 1 h) was also performed to induce crystallinity in WO3. More pores (50–80 nm in diameter) and thicker porous layer were formed by increasing the amount of NH4F (400 nm for 0.3 g of NH4F). However, further increase of the NH4F amount to 0.5 and 0.7 g did not increase the porous layer thickness. Segmented nanoporous structure formation was attributed to the dissolution of anodic oxide by H+ and F− ions in the electrolyte, as well as the healing process induced by the electric field. The photocatalytic activity of the WO3 samples was evaluated through degradation of methyl orange solution. The as-anodized sample showed lower photocatalytic ability in comparison with the annealed sample because of the amorphous behavior of as-anodized WO3.

The structural organization of the palliostracum—the dominant part of the shell which is formed by the mantle cells—of Glycymeris glycymeris (Linné 1758) is comprised of five hierarchical levels with pronounced structural commonalities and deviations from other crossed-lamellar shells. The hierarchical level known as second order lamellae, present within other crossed-lamellar shells, is absent highlighting a short-coming of the currently used nomenclature. On the mesoscale, secondary microtubules penetrate the palliostracum and serve as crack arrestors. Moreover, the growth lamellae follow bent trajectories possibly impacting crack propagation, crack deflection, and energy dissipation mechanisms whilst circumventing delamination. Finally, at least two structural elements are related to external circatidal and circaanular stimuli. This emphasizes that endogeneous rhythms may contribute and (co-)control the self-organization of a complex mineralized tissue and that it is insufficient to rely fully on a reductionistic approach when studying biomineralization.

A scale formed by heat treatment of Ti in a nitrogen atmosphere containing oxygen at an extremely low partial pressure exhibited an exceptional degree of hydroxyapatite (HAp) formation in a simulated body fluid. Scanning transmission electron microscopy and electron energy loss spectroscopy indicated that the subsurface of this scale was composed of nitrogen doped rutile-type TiO2. The N-K edge energy-loss near edge structure spectrum of this layer in conjunction with the theoretical spectra of possible compounds obtained using the augmented plane wave plus local orbital band method suggested that oxygen sites were replaced by two nitrogens, resulting in an effective charge of +2. The enhanced HAp forming ability of this scale is likely related to the positively charged surface induced by the presence of N. Conversely, the subsurface scale formed by heat treatment in air, in which N is not found, leads to much slower HAp coverage, believed to be related to the lack of surface charge.

In nanocrystalline (nc) metals, it is still not clear how local grain boundary (GB) structures accommodate GB migration at atomic scales and what dominates the motion of atoms at the inherently unstable GB front. Here, we report the adjustment of the local GB structures at atomic scales during self-driven GB migration, simultaneously involving GB dissociation, partial dislocation emission from GB, and faceting/defaceting in the nc Cu. Furthermore, we reveal that the fundamental of GB migration ability is closely related to the local structure, i.e. the GB segment consisting of “hybrid” structural units and delocalized GB dislocations is relatively unstable.

Transition metal dichalcogenides such as WS2 show exciting promise in electronic and optoelectronic applications. Significant variations in the transport, Raman, and photoluminescence (PL) can be found in the literature, yet it is rarely addressed why this is. In this report, Raman and PL of monolayered WS2 produced via different methods are studied and distinct features that indicate the degree of crystallinity of the material are observed. While the intensity of the LA(M) Raman mode is found to be a useful indicator to assess the crystallinity, PL is drastically more sensitive to the quality of the material than Raman spectroscopy. We also show that even exfoliated crystals, which are usually regarded as the most pristine material, can contain large amounts of defects that would not be apparent without Raman and PL measurements. These findings can be applied to the understanding of other two-dimensional heterostructured systems.

In this study, the MnOx–FeOy hollow nanospheres with solid solution structure were prepared by supercritical antisolvent (SAS) process. The average particle size was about 50 nm, and average pore diameter was 7 nm. By applying the SAS method, novel nonsupported MnOx–FeOy catalysts with a Mn/Fe mass ratio of 1:1 showed rather high selective catalytic reduction activity and broad active temperature window. The NOx conversion rate reached 97% at 220 °C, and maintained above 92% from 180 to 260 °C. The experiment results showed that iron doping could cause the apparent change of MnOx morphology and structure, which enhanced the oxidative ability of manganese species and increased surface active oxygen species. Meanwhile, compared with traditional methods, the SAS process could efficiently enhance the interaction between manganese and iron, and produce smaller size and larger pore volume nanoparticles with more active sites on the surface.

(KxNa1−x)NbO3 films were deposited on Nb-doped (100)SrTiO3 substrates at 240 °C for times between 1 and 6 h by a hydrothermal method. Over this time series, the measured (K + Na)/Nb ratio of the films was found to remain constant, but the bulk K/(K + Na) ratio, x, decreased from an initial value of 0.75–0.56. It was determined that film growth initially proceeded through crystallization of the K-rich phase (K0.75Na0.25)NbO3. For film growth times greater than 3 h, a second perovskite phase with a smaller unit cell volume was detected, with an estimated composition of (K0.36Na0.64)NbO3. As such, the measured bulk composition value x = 0.56 was determined to be the result of a combination of these two phases, as opposed to originating from a single phase. Cross-sectional transmission electron microscopy analyses of films prepared for 6 h revealed that they consist of two layers in the direction normal to the substrate; this bilayer-type structure, only observed for hydrothermal growth of this material, is considered to arise from the large solubility mismatch between the Nb precursor and KOH and NaOH in the growth solution.

Tungsten foams with directional, controlled porosity were created by directional freeze-casting of aqueous WO3 powder slurries, subsequent freeze-drying by ice sublimation, followed by reduction and sintering under flowing hydrogen gas to form metallic tungsten. Addition of 0.51 wt% NiO to the WO3 slurry improved the densification of tungsten cell walls significantly at sintering temperatures above 1250 °C, yielding densely sintered W–0.5 wt% Ni walls with a small fraction of closed porosity (<5%). Slurries with powder volume fractions of 15–35 vol% were solidified and upon reduction and sintering the open porosity ranges from 27–66% following a linear relation with slurry solid volume fraction. By varying casting temperature and powder volume fraction, the wall thickness of the tungsten foams was controlled in the range of 10–50 µm. Uniaxial compressive testing at 25 and 400 °C, below and above the brittle-to-ductile-transition temperature of W, yields compressive strength values of 70–96 MPa (25 °C) and 92–130 MPa (400 °C).

In the recent years, carbon fiber reinforced polymer (CFRP) composites have formed a very important class of tribo-engineering materials in nonlubricated condition. The usage of CFRPs has been growing at a substantial rate that leads to the increasing amount of waste generated from end-of-life components and manufacturing scrap. In the present paper, the role of as-received (rCF-AR) and cryogenic treated (rCF-T) recycled carbon fiber (rCF) reinforcements were investigated on the tribological behavior of epoxy composites by using a micro pin-on-disc tribotester apparatus under dry sliding condition. The wear behavior of the composites was analyzed based on three different sliding velocities and loads at a constant sliding distance. The results showed that the reinforcement effect of rCF-T as compared to rCF-AR has enhanced the wear resistance of epoxy composite, which is attributed to the improved adhesion between the treated rCFs and epoxy matrix.