Compounds of poly(3-hydroxybutyrate) (PHB) and carbon black (CB) with CB content ranging between 0.5 and 10% were prepared in an internal mixer. The effect of heating and cooling rates on the crystallization and melting of PHB/CB compounds was investigated by differential scanning calorimetry (DSC), and its morphology analyzed by optical microscopy (OM). Results showed that PHB and its compounds partially crystallize from the melt during cooling and partially cold crystallize on reheating, with the amount of polymer crystallizing in each stage depending strongly on the cooling rate. Melting is usually shown in DSC scans as complex (double) peaks, which are influenced by the heating/reheating thermal cycles. The melting and cold crystallization temperatures, and the rates of phase change depend strongly on the cooling and heating rates and CB content. CB acts as a nucleating agent, promoting the melt and cold crystallization of PHB as well as increasing the number of spherulites, with a mild effect on the melting transition. Light microscopy images suggest that a secondary crystallization of PHB also occurs during storage at room temperature.

Micro/nanostructured goethite (α-FeOOH) was synthesized by a low-temperature water bath method based on the reaction of urea and FeSO4•7H2O at 95 °C. It has been shown that the as-prepared α-FeOOH consists of nearly spherical particles with about 0.5–1 μm in diameter. The microsized α-FeOOH particles are urchin-like in morphology and composed of nanosized leaf-like objects, with about 150–200 nm in length and about 30–50 nm in width, in radial arrangement, showing high specific surface area (∼118 m2/g). The formation of such urchin-like α-FeOOH could be described by a two-step process, or formation of spherical particles, and ethylene glycol-adsorption induced preferential growth of nanoleaves on the preformed spherical particles. Importantly, such micro/nanostructured α-FeOOH has exhibited much higher photocatalytic activity to the organic pollutants, such as Rhodamine 6G, and better re-usable performances than the goethite nanorod powders, exhibiting the good application potential in the environmental treatment. This study could provide a useful material for environmental pollution treatment.

Polyurethane open cell (PUOC) composites containing SiO2 and Al2O3 nanoparticles (NPs) were prepared. Scanning electron microscopy and Z-scan methods were used for observing porosity and detecting third-order nonlinear optical properties of related samples. Adding NPs into polymer matrix decreased the cell size and subsequently increased the porosity of samples. The nonlinear effects of samples were increased by adding 1 wt% of NPs into polymer in comparison with blanks. However, those features were decreased again through higher loading (up to 2.0 wt%) of NPs. The nonlinear refractive indices and nonlinear absorption coefficients of the synthesized samples were obtained in the order of 10−8 (cm2/W) with negative sign and 10−5 (cm/W), respectively. All the results suggest that the nonlinear coefficients of the synthesized samples can be controlled by NP contents in PUOC.

The production of aluminum nitride (AlN) from aluminum metal was investigated in this study. The nitridation of Al (in rod, powder, and thin-plate forms) was facilitated by dissolving the Al2O3 thin films formed on the Al samples with a molten fluoride mixture (KF–45 mol% AlF3, KF, or LiF–50 mol% KF). AlN was formed when NH3 gas was supplied to the Al sample (in both solid and liquid forms) wetted by molten fluoride mixture. The lowest temperature at which AlN was successfully produced was 773 K. No AlN was formed when N2 or H2–25% N2 gas was supplied to the Al sample, even when a molten fluoride mixture was used. The reaction rate for the nitridation of Al powder increased with the temperature and reached 99% after 3 h at 1173 K. AlN thin films of 2–5 μm thickness were formed on Al thin plates (0.075–1.0 mm thick) at 873 K.

A facile synthesis method was adapted to prepare Ortho-chloropolyaniline/graphite oxide (OPANI/GO) composites. The properties of these composites have been discussed based on different characterizations such as scanning electron microscopy, FTIR, and dielectric studies. The important peaks of benzenoid and quinoid rings in the spectrum confirm the formation of composites. Scanning electron microscopic studies indicate that the morphology of the prepared composites was influenced by different weight ratios of GO in OPANI and the resulting micrographs of these composites exhibited flaky and folded structures. The electrical conductivity study was carried out and found that 6 wt% of GO in PANI shows high conductivity value of 20 × 10−2 S/cm. The obtained results suggest an easy approach to prepare such novel nanocomposites with excellent dielectric properties which can be used in many technological applications.

This article aims to provide a fundamental understanding of the deformation mechanisms of NiTi shape memory alloy (SMA) during the wear process at different temperatures when different microstructures are present. Three temperature regimes were selected namely, T < Mf, As < T < Af, and T > Af, where fully martensitic, martensite co-existing with austenite, and fully austenitic microstructures were formed, respectively. When T < Mf, it was observed that the coefficient of friction had decreased initially and thereafter stabilized at a lower value with increasing wear cycles. More decrease was found when the temperature was near to As. Furthermore, when tested above Af, the coefficient of friction had decreased more significantly under higher load. Difference in the trend of coefficient of friction at different temperatures is originated from the different deformation mechanisms involved in the wear process, particularly the martensite detwinning process, the stress-induced phase transformation process, and the plastic deformation of martensite.

We theoretically investigated the structural and thermoelectric properties of Mg2Si with Al and Sb (Na and B) as n-type (p-type) impurities. Supercell calculations involving relaxation of the atomic positions using an ab initio pseudo-potential method were performed. The formation energies, Eform,i, for the i = Mg, Si, and 4b sites, and consequently, the energetically preferred sites occupied by the impurities, were discussed. The calculated Eform,i were used to estimate the impurity-site occupancy probabilities, pi(T), based on the canonical distribution in the equilibrium state, i.e., pi(T) ∝ exp(−Eform,i/kBT) (Boltzmann constant: kB, temperature: T), and the resultant effects on the carrier concentration. Next, an all-electron full-potential linearized augmented-plane-wave calculation was performed based on the optimized structures, and the temperature dependence of the thermoelectromotive force (the Seebeck coefficient) was evaluated using the Boltzmann transport equation. The calculated and experimental results for n-type doped systems were compared.

Progress toward combining time-resolved experiments with periodic three-dimensional analysis of the evolved microstructural state has been made recently. In situ electron microscopy is used to observe in real time the development of irradiation defects and the influence of these defects on dislocation behavior. Three-dimensional characterization provides information on the true spatial distribution of defects and clarifies effects of the free surfaces in thin films. This quasi-four dimensional analysis approach has been applied to understand the formation of channels in irradiated alloys, the depth distribution of ion damage in an electron transparent foil, and the dislocation channel interactions with grain boundaries. The new insight obtained from these experiments is highlighted and contrasted with findings from simulations.

This work focused on ascertaining the effect of pile-up during indentation of thin films on substrates. Conventional understanding has postulated that differences in contact area resulting from pile-up or sink-in significantly alter the extraction of material properties. In this work, the specific case of pile-up with compliant, plastically deforming films on stiff, nonplastically deforming substrates was studied. Several literature methods to assess pile-up were leveraged, and a new technique was developed and validated to quantify projected pile-up. Indentation testing was performed on gold films of multiple thicknesses on several ceramic-based substrates. The results indicated that the degree of pile-up was solely a function of indent depth into the film. Pile-up was not influenced by film thickness or substrate elastic modulus. In other words, the pile-up development was insensitive to the presence of the substrate and how it contributes to the composite's elastic properties. In such case, if the elastic response of the film/substrate composite was independent of the degree of pile-up, then elastic data acquired from unloading did not require a contact area correction. The findings are confirmed using the Zhou–Prorok model for extracting film elastic properties for both gold and platinum films.

In this paper, the Ni-decorated ZnO photocatalysts with magnetic separable characteristics were prepared by a simple replacing-hydrothermal process for the first time. The as-synthesized composites were characterized by powder x-ray diffraction, UV–visible diffuse reflectance spectroscopy, x-ray photoelectron spectroscopy, scanning electron microscope, transmission electron microscopy, and so on. It is found that the introduction of Ni (as Ni0 and Ni2+ forms) turned the morphologies of ZnO photocatalysts, enhanced photoabsorption in a visible light region, and increased amount of surface adsorbed oxygen. The photodegradation test of anthraquinone dye (reactive brilliant blue KN-R) indicated that the Ni-decorated ZnO photocatalysts have better activities as compared to the ZnO reference. The enhancement of photocatalytic activity of Ni-decorated ZnO photocatalysts can be attributed to the existence of Ni2+ doping, Ni0/ZnO heterostructure, and abundant-adsorbed oxygen (as the electronic scavenges), which caused efficient separation of electron–hole pairs in Ni-decorated ZnO photocatalysts. Furthermore, the introduction of metallic Ni also endued ZnO with good magnetic recoverability. The re-collected experiments by external magnetic field indicated that Ni-decorated ZnO as a magnetically recoverable photocatalyst is acceptable.

Nanoporous carbon monoliths with different pore structures were obtained by carbonizing cured phenol–formaldehyde (PF) resin/poly(methyl methacrylate) (PMMA) blends. The effect of the molecular weight of PMMA, reaction activity of PF, and content ratio of compositions on the pore structure of carbon monoliths was systematically investigated, with emphasis on controlling the morphology of the nanostructure and pore size distribution. Nanostructures were an important factor in determining the compressive strength of porous carbon monoliths. The relationship between the nanoporous structure of carbon monoliths and compressive strength was revealed. Co-continuous pores provided escape channels for those volatile gases produced in the carbonization process to escape, reducing inner stress of the carbon materials. During compressive loading, co-continuous pores could also help to scatter and absorb the stress and energy. Porous carbon monoliths with a compressive strength of 34 MPa were obtained, and the compressive strength increased by 580% compared with that of carbon monoliths obtained from pure PF.

The mechanical behavior of human hair is determined by the interaction of trichocyte alpha keratin protein, matrix, and disulfide bonds crosslinking. Much effort has been spent to understand the link between the microscopic structure and the macroscopic fiber properties. Here we apply a mesoscopic coarse-grained model of the keratin macrofilament fibril combined with an analytical solution based on the concept of entropic hyperelasticity of the protein helix to investigate the link between the microscopic structure and the macroscopic properties of keratin fibers. The mesoscopic model provides good agreement with a wide range of experimental results. Based on the mesoscopic model, the predicted stress–strain curve of hair fibers agrees well with our own experimental measurements. The disulfide crosslink between the microfibril–matrix and matrix–matrix contributes to the initial modulus and provides stiffening at larger deformation of the trichocyte keratin fibers. The results show that the disulfide bonds reinforce the macrofilament and enhance the robustness of the macrofilament by facilitating the microfilaments to deform cooperatively. The availability of a mesoscopic model of this protein opens the possibility to further explore the relationship between microscopic chemical structure and macroscopic performance for a bottom-up description of soft materials.

LiFe1/3Mn1/3Co1/3PO4 (LFMC) has been synthesized by a microwave-assisted hydrothermal technique. During the crystal growth, two evolutionary routes coexist and compete with each other after the nuclei have been stably formed. One of them is the continuous growth of single particles and the other one is agglomeration. The size and morphology of the products are determined by the interplay of the two competing routes. The growth morphology is quantitatively analyzed from first principle calculations. A phase diagram is constructed, which guides to control the morphology by adjusting CM and pH. Static magnetic properties imply long range antiferromagnetic order below TN = 39 K and a paramagnetic Curie–Weiss-like behavior with θ = 75 K and peff = 5.51 μB at high temperatures. Cyclic voltammetry shows two distinct peaks corresponding to the Fe2+/Fe3+ and Co2+/Co3+ redox couples, respectively, whereas the Mn2+/Mn3+ redox couple is not observed due to its sluggish kinetics induced by the Jahn–Teller effect of Mn3+.

Copper microcantilevers were produced by focused ion beam milling and tested in situ using a scanning electron microscope. To provide different interfaces for piling up dislocations, cantilevers were fabricated to be single crystalline, bicrystalline, or single crystalline with a slit in the region of the neutral axis. The aim of the experiment was to study the influence of dislocation pile-ups on (i) strength and (ii) Bauschinger effects in micrometer-sized, focused ion beam milled bending cantilevers. The samples were loaded monotonically for several times under displacement control. Even though the cantilevers exhibited the same nominal strain gradient the strength varied by 34% within the three cantilever geometries. The Bauschinger effect can be promoted and prohibited by the insertion of different interfaces.

Steel coils coated with Zn–Mg alloy containing high Mg content develop dark rust when exposed to an extremely limited amount of aqueous environment. To understand the nature of the dark rust and its formation mechanism, the steel is evaluated by the immersion test and high temperature–humidity test followed by critical evaluation with transmission electron microscopy for cross-sectional observation, field-emission scanning electron microscopy for surface morphology observation, Auger electron spectroscopy and glow discharge spectroscopy for identification of chemical composition as a function of depth. The results indicate that the dark rust is formed by precipitation of Mg-based corrosion product on the outermost surface when the steel is exposed to aqueous environment at high temperature. This is due mainly to preferential dissolution of Mg phases by the galvanic action with MgZn2 and Mg2Zn11 composed of the coating layer, and easy precipitation of Mg2+ ion in a form of Mg(OH)2 in a limited volume of the condensed water film on the surface.

Single-phase crystalline ZnSnP2 nanowires have been prepared via simple chemical vapor deposition method using powdered Zn and SnP3 as the precursors in a custom-built tube furnace reactor. The sublimed precursors were allowed to react with thermally evaporated Sn nanoparticles to yield ZnSnP2 nanowire films over areas of 40 mm2. The cumulative observations suggest that the Sn nanoparticles served both as the growth seed and main contributor of Sn. Prolonged growth time favored formation of Zn3P2 nanowires when the Sn supply was exhausted. For optimal growth conditions, surface and bulk elemental analyses showed homogenous elemental distribution of Zn, Sn, and P, with chemical composition close to 1:1:2 stoichiometry. Powder x-ray diffraction data and Raman scattering of the nanowire films along with single-nanowire analysis using high-resolution transmission electron microscopy indicated that the as-prepared ZnSnP2 nanowires possessed a sphalerite crystal structure, as opposed to the antisite defect-free chalcopyrite structure. Photoelectrochemical measurements in aqueous electrolyte showed that the as-prepared ZnSnP2 nanowires are capable of sustaining stable cathodic photoresponse under white light illumination. Overall, this study presented a benign and straightforward approach to prepare single-phase Zn-based phosphide nanowires suitable for energy conversion applications.

Yttrium disilicates (Y2Si2O7), well known for its complex polymorphism, are promising candidates for high-temperature structural materials and environmental barrier coatings due to their good properties in harsh environments. In this study, the crystal structure, elastic stiffness, and temperature dependence of the lattice thermal conductivity of β-, γ-, and δ-Y2Si2O7 are studied using first-principles calculations. Divergences of elastic stiffness are attributed to the different crystal structures and bonding strength of the polymorphs. Specially, the Si–O–Si bridge of δ phase bends with an angle of 158.1°, and this configuration enhances the bonding heterogeneity but weakens the bonding strength and stability. According to the prediction of lattice thermal conductivity using the Debye–Slack model, β-, γ-, and δ-Y2Si2O7 are characterized with very low thermal conductivity. In addition, the deviation of lattice thermal conductivities of Y2Si2O7 polymorphs is dominated by two vital factors, anharmonicity of phonon scattering and complexity of crystal structure. The present method could be used to investigate the specific factors dominating lattice thermal conductivity and may promisingly be generalized to search novel candidates with extremely low lattice thermal conductivity.

The electrophysical and structural properties of InAlAs/InGaAs/InAlAs quantum wells (QWs) with thin InAs inserts were investigated by means of Hall effect measurements and scanning transmission electron microscopy. The analyzed heterostructures are nearly the same ones using for high electron mobility transistors manufacturing except for heavily doped contact top layer. The increase of the electron mobility and concentration in the heterostructures with thin InAs layers in the center of the InGaAs QW as compared with the uniform QW was found and this effect strongly depended on the technological conditions during growth of the InAs inserts. The dependence of the InAs insert structural quality and heterointerface width on the As4 beam equivalent pressure PAs was revealed. The decreased PAs is required for obtaining uniform and smooth InAs inserts as opposed to higher PAs resulting in the interface spreading and lateral composition inhomogeneity of the InAs insert.

In this work, we report an experimental technique with nanometer resolution to reveal the microstructural mechanism for electric fatigue in ferroelectrics. The electric field in situ transmission electron microscopy (TEM) was used to directly visualize the domain evolution during the fatigue process in a 0.7Pb(Mg1/3Nb2/3)O3–0.3PbTiO3 ceramic. The structure–property relationship was well demonstrated by combining the microscopic observations with corresponding dielectric, piezoelectric, and ferroelectric properties measured on bulk specimens. It was found that the domain switching capability was substantially suppressed after 103 cycles of bipolar fields, leading to an immobilized domain configuration thereafter. Correspondingly, a pronounced degradation of the functionality of the ceramic was manifested, accompanying with a coercive field bumping and polarization current density peak broadening. The reduction of the polarization, dielectric constant, and piezoelectric coefficient were found to follow a power-law relation. Seed inhibition mechanism was suggested to be responsible for the observed fatigue behaviors.

The initial microscale mechanisms and materials interfacial process responsible for hydration of calcium silicates are poorly understood even in model systems. The lack of a measured microscale chemical signature has confounded understanding of growth mechanisms and kinetics for microreaction volumes. Here, we use Raman and optical spectroscopies to quantify hydration and environmental carbonation of tricalcium silicates across length and time scales. We show via spatially resolved chemical analysis that carbonate formation during the initial byproduct in microscale reaction volumes is significant, even for subambient CO2 levels. We propose that the competition between carbonation and hydration is enhanced strongly in microscale reaction volumes by increased surface-to-volume ratio relative to macroscale volumes, and by increased concentration of dissolved Ca2+ ions under poor hydration conditions that promote evaporation. This in situ analysis provides the first direct correlation between microscale interfacial hydration and carbonation environments and chemically defined reaction products in cementitious materials.