Epitaxial layers of insulating binary lanthanide oxides have been considered as potential alternative to conventional SiO2 for gate dielectric application in future Si-based MOSFET devices, which was investigated in more detail for epitaxial Gd2O3 and Nd2O3 as model systems. Additionally, the ability to integrate epitaxial dielectric barrier layers into Si structures can usher also in a variety of novel applications involving oxide/silicon/oxide heterostructures in diverse nanoelectronic and quantum-effect devices. Although epitaxial layers of such ionic oxides with excellent structural quality can be grown using molecular beam epitaxy, they often exhibit poor electrical properties such as high leakage current density, flat band instability, poor reliability etc. owing to the presence of electrically active charge defects, generated either during the oxide layer growth or typical subsequent CMOS process steps. Based on the origin and individual character of these defects, we review various aspects of defect prevention and passivation which lead to a significant improvement in the dielectric properties of the heterostructures.

A free standing 2D PS colloidal crystal with Au nanoshells/hydrogel composite film (CAuHCF) was fabricated by embedding a 2D PS colloidal crystal with Au nanoshells into a polyacrylic acid (PAA) hydrogel film. This CAuHCF can act as a visualized sensor with high diffraction intensity. The 2D PS colloidal crystal with Au nanoshells was prepared by depositing an Au layer on PS colloidal crystal obtained by interfacial self-assembly. The diffraction intensity of the CAuHCF was increased by about 30-fold than that of traditional 2D PS colloidal crystal/hydrogel composite film on transparent substrate due to large scattering cross section of Au shell. Such sensors based Au nanoshells array with the simple preparation process and the strong diffraction signal are promising ones for practical applications in visual detection. Additionally, with the simple preparation process and high diffraction intensity, other visualized sensors based different hydrogel matrix and the 2D PS colloidal crystal with Au nanoshells could be synthesized for monitoring various analysts.

Elastic strain is an effective and thus widely used parameter to control and modify the electrical, optical, and magnetic properties of crystalline solid-state materials. It has a large impact on device performance and enables adjusting the materials functionality. Here, we promote a micromechanical strain enhancement technology to achieve ultra-high strain in semiconductors. The here presented suspended membranes enable the accurate control of the strain on a wafer-scale by standard top-down fabrication methods making it attractive for both device applications and also, thanks to the simplicity of the method, for fundamental research. This review aims at discussing the process of strain enhancement and its usage as an investigation platform for strain-related physical properties. Furthermore, we present design rules and a detailed analysis of fracture effects limiting the strain enhancement.

N-doped single-crystal-like TiO2 is claimed to be a very promising material among various catalytic. In this paper, N-doped single-crystal-like TiO2 (N-S-TiO2) samples were firstly prepared by molten salt method with urea and mixed nitrates as synergistic doping agents, therein, the mixed nitrates works also as a morphology modifier to form a single-crystal-like structure in the sample. The nitrogen content in the N-S-TiO2 sample could be improved because of the adding of NaNO3 and KNO3 mixed nitrates compared with using urea as a single nitrogen source. UV–Vis absorption spectroscopy analysis indicated that the nitrogen doped TiO2 has a red shift of the light absorption edge. The presence of N–O bonds on the surface of the N-S-TiO2 samples could be confirmed by x-ray photoelectron spectroscopy. The degradation efficiency of N-S-TiO2 to methylene blue under visible light is the best compared with different TiO2 samples without the treatment of mixed nitrates.

SrTiO3 is an important photocatalyst for hydrogen evolution under solar light, a promising way to solve energy shortage. However, a rapid and efficient method to synthesize high-performance SrTiO3 used for this purpose still remains a challenge. In this work, we successfully prepared SrTiO3 catalyst with narrowed band gap through a rapid laser-melting method of a limited reaction time to seconds. The prepared SrTiO3 catalyst, which has a band gap of 3.05 eV, presents enhanced photocatalytic performance for hydrogen evolution under visible light. The evolution rate of laser-melted SrTiO3 is approximately 3.5 times higher than that of pristine SrTiO3. In addition, the magnetism in laser-melted SrTiO3 is also enhanced, which could not be observed in pristine SrTiO3, confirming the defective structure of the obtained laser-melted SrTiO3. The proposed laser-melting method will be a promising way to rapidly and efficiently synthesize homogeneous, solar-driven SrTiO3 photocatalyst for hydrogen evolution with rich defects and thus high-performance.

TiO2 nanotubes have been demonstrated with promising future in photoelectrocatalytic (PEC)_ applications and deposition of Pt nanoparticles on TiO2 has been widely used to enhance their PEC activities. However, those Pt nanoparticles are normally randomly deposited on the surface of TiO2 nanotubes. Selective deposition of Pt nanoparticles is important to achieve better charge separation. In this study, we reported an electrochemical activation step to prepare TiO2 nanotubes deposited with Pt nanoparticles on their open ends. The “activation step” played a key role in achieving a clean surface of the TiO2 nanotubes, thus ensuring the uniform growth of Pt nanoparticles and efficient photogenerated electrons transportation. The Pt-A-TiO2 films have photocatalytic activities in hydrogen generation and methyl orange degradation with a high hydrogen generation rate of 0.74 mL/h/cm2, three times that of the pure TiO2 nanotubes (0.24 mL/h/cm2). Thus, this study demonstrated an effective method for improving the performance of Pt/TiO2 photocatalyst.

Bimetallic catalyst Ni–Fe/SiO2 microspheres were obtained by reducing bimetallic (Ni,Fe2+)3Si2O5(OH)4 microspheres with controllable morphology structure in situ under the hydrogen atmosphere at 650 °C, which are synthesized via one-step self-template method under hydrothermal conditions. The TEM images indicate the formation process of the different morphology and the synthesis conditions of bimetallic Ni–Fe silicate were obtained. Bimetallic catalyst Ni–Fe/SiO2 (reduced) hollow microspheres had the smaller surface area and the bigger pore diameter than that of (Ni,Fe2+)3Si2O5(OH)4 (unreduced) hollow microspheres because the reduction reaction under high temperature may make part pores in nanosheets collapsing and metal particles aggregating easily for the strong magnetism. For synergistic effect of nickel ion and iron ion, the reaction conditions of the chosen catalyst with higher activity were decreased from 140 °C–24 h + 180 °C −12 h for iron silicate hydroxide to 140 °C–12 h. Ni–Fe/SiO2 core-shell microspheres exhibited excellent catalytic activity with a conversion of nitrobenzene reaching 94% within 2 h, which is 82% higher than Fe/SiO2.

The rheological behavior of composites made with high-density polyethylene (HDPE) and chitosan was studied. Composites were prepared by melt processing in a laboratory internal mixer. Maleic anhydride grafted HDPE (PE-g-MA) was used as compatibilizer to enhance the dispersion of chitosan in the HDPE matrix. Different percentages of chitosan and compatibilizer (up to a maximum of 25 phr) were added into HDPE to prepare composites. Characterization of the composites with parallel plate rheometer and laboratory internal mixer revealed that the presence of chitosan increases the complex viscosity, loss modulus, storage modulus and the torque (i.e., melt viscosity), and the combination chitosan/compatibilizer has a similar, if slighter, effect. At higher filler levels it is clear that the PE-g-MA affected the microstructure of the compounds, possibly increasing matrix–filler interactions and acting as an effective compatibilizer.

Natural rubber (NR) is expected to enhance impact strength of poly(lactic acid) (PLA). Because the polarity difference of NR and PLA leads PLA/NR blends having phase separation and poor mechanical properties, this research aimed to synthesize NR-graft-PLA (NR–PLA) via esterification of maleated NR (NR-MAH) with PLA. The role of NR–PLA used as a compatibilizer on mechanical and thermal properties of the PLA/NR blends was studied. Maximum grafted PLA level at 66.8% (w/w) was reached when NR-MAH was esterified with PLA [2/1 (w/w) PLA/NR-MAH] catalyzed by 0.05 M 4-dimethylaminopyridine at 140 °C. The addition of 5% (w/w) NR–PLA [36.6% (w/w) grafted PLA content] into PLA/NR blend [80/20 (w/w)] increased Izod impact strength of the neat PLA plate from 28.9 J/m to 62.7 J/m due to partial miscibility of blends attested by morphology analysis and Molau test. Hydrolytic degradation of PLA/NR blends with and without the addition of NR–PLA was also examined.

This study investigated the tribological behaviors of carbon fiber (CF) reinforced epoxy (EP) composites immersed in 10 wt% sulfuric acid solution for different numbers of days. The tribological properties of the composites were evaluated as a function of their different fiber orientations (0°, 45°, 90°, and normal orientation). The CF/EP composites showed a favorable anticorrosion performance, as assessed by electrochemical corrosion tests, due to the tightly stacked CF. Meanwhile, the wear tests indicated that the CF orientation had a significant effect on the tribological performance. Composites with 45° CF orientation exhibited the lowest friction coefficient, whereas those with 90° CF orientation had lowest wear rate, which was 6 times lower than that of composites with normal CF orientation. Moreover, the surface microstructures of the worn surfaces were observed by scanning electron microscopy (SEM) to determine the corresponding wear mechanisms.

Electropolymerization is a promising approach to produce thin films of active organic conjugated materials on a desired conducting substrate. In this work, an electropolymerization study has been carried out on two diketopyrrolopyrrole (DPP)-based monomers 2,5-bis(2-butyloctyl)-3,6-di(furan-2-yl)pyrrolo[3,4-c]pyrrole-1,4(2H,5H)-dione (BO-DPPF) and 2,5-bis(2-butyloctyl)-3,6-di(thiophen-2-yl)pyrrolo[3,4-c]pyrrole-1,4(2H,5H)-dione (BO-DPPT). These monomers consist of thiophene and furan heterocyclic moieties attached to a DPP core with a common solubilizing alkyl chain (butyl-octyl). The properties of these monomers were analyzed via differential scanning calorimetry, thermogravimetric analysis, UV–Vis spectrometry (UV) and photoluminescence. Cyclic voltammetry (CV) studies indicate the presence of irreversible oxidation and reduction reactions. The electropolymerization of BO-DPPF and BO-DPPT electron-deficient monomers to form polymer films on a glassy carbon electrode is achieved by applying a potential between −2 V and 2 V versus ferrocene for up to 50 cycles. The properties of the polymers were investigated using the cyclic voltammetry (CV) technique.

The effects of alkaline earth strontium (Sr) additions on the microstructure and properties of Al–Si–Ge–Zn alloys and brazed joints were investigated. The results showed that the appropriate addition of Sr changed the morphology of β-GeSi phases from coarse needle-like to fine granular shapes effectively. Sr addition prevented the growth of Si by Sr adsorbing on the Si surface and caused the formation of many twins in Si. Sr addition had little impact on the melting temperature of the filler metals, but the spreading areas of Al–Si–Ge–Zn–xSr filler metals increased firstly and then decreased with the increase of Sr addition. In addition, the Sr addition optimized the microstructure of the brazed joints and improved the mechanical properties. Sound joints with high shear strength up to 152.4 ± 2.5 MPa could be obtained by applying Al–9.5Si–10Ge–15Zn–0.7Sr (all in wt%) filler metal.

The object of the present investigations was to evaluate the effect of flash butt welding parameters on microstructures and mechanical properties of HSLA 590CL welded joints in wheel rims by adjusting welding parameters separately. The amount of Widmanstatten ferrites and bainite in the weld metal, and grain size were observed with the adjustment of welding parameters. The tensile strength of welded joints met the strength requirement of wheel rims steels, but the tensile strength and tensile fracture were different in different welding parameters. Micro-hardness distributions of welded joints in different welding parameters were similar, that is the maximum micro-hardness occurred in the weld and micro-hardness decreased from the weld to base metal. A certain degree of softening phenomenon was found in the heat affected zone (HAZ), which should result from the heat input in the flash butt welding. Two failure mechanisms of wheel rims in the expanding process were investigated. The first type fractured at the HAZ and showed ductile fracture characteristics, the crack initiation located at the thinning location. The second type fractured at the weld and showed brittle fracture characteristics.

The dissimilar MIG welding of Mg alloy and ultra-high strength steel was investigated. The results indicated that the Mg-steel joints had characteristics of welding-brazing and included weld zone, bond zone, and interface zone. The weld zone with an equiaxed grain structure mainly consisted of α-Mg and α-Mg + β-Mg17Al12 phases when AZ31 and AZ61 filler metals were used respectively. The interface zone presents a double-layer structures: the AlFe3 layer at steel side and the Mg(Fe, Al)O4 + Mg3.1Al0.9 layer at Mg side, and their evolution process has been summarized. The joint strength was improved obviously at the heat input of 1987–2100 J/cm due to eliminating incomplete joining defects and cracks in the interface zone. With AZ61 filler metal, the weld Al content was 6.24%, the joint strength was elevated from 174 MPa for AZ31 filler metal to 201 MPa (83.8% of Mg alloy base metal), which is related to the increased Al promoting the interface reaction.

Microstructure and electrochemical behavior of stainless steel weld overlay cladding exposed to post weld heat treatment (PWHT) were investigated, wherein pitting and intergranular corrosion behaviors of the cladding material were evaluated by potentiodynamic polarization and double loop electrochemical potentiokinetic reactivation methods. The results indicated that inclusions, multiple element (Mn, Si, and Al) oxides distributed randomly in the cladding material with a size less than 1 μm. PWHT contributed to carbides precipitation along the δ/γ phase interface and the formation of Cr-depleted zone in the austenite phase. Inclusions acted as the pitting sites in the sample as welded. PWHT reduced the pitting potential and contributed to the formation of larger and deeper pits, which nucleated around the δ/γ phase interface primarily. Existence of carbides and Cr-depleted zone dominated the loss of intergranular corrosion resistance after PWHT.

The influence of hot rolling on the evolution of the interface microstructure as well as mechanical properties of the Mg/Al explosive welding composite plates was investigated. The hardening phenomenon induced by explosive welding could be eliminated effectively through preheating treatment. An intermetallic compound layer consisting of Al3Mg2 and Mg17Al12 was observed at the Mg/Al interface after annealing at 400 °C. The composite plate then was hot rolled at 400 °C with different reduction ratios. The composite plates presented different degrees of warp and edge cracks with increasing the reduction ratio. At the reduction ratio of 30%, the coordination deformation ability of the constituent Mg and Al alloys is consistent with the composite plate. The results showed that the tensile strength and the elongation of the composite plates increased significantly after hot rolling owing to the dynamic recrystallization and the intermetallic compounds thickness decrease during hot rolling.

The effect of aluminizing and Cu electroplating of the steel insert in fabrication of Al-matrix bimetal on the microstructure and mechanical properties of the interface layer was investigated. Compound casting process was used to fabricate Al-matrix bimetals reinforced with coated steel insert. The microstructures at the interface region were studied using light optical and scanning electron microscopes and energy dispersive X-ray spectroscopy. The interfacial shear strengths of the fabricated bimetals were compared using push-out test. The results showed that electroplating with copper and aluminizing of steel insert in aluminum matrix led to significant improvement of metallurgical bonding between the steel and aluminum cast matrix. Cu-coated insert contained a thicker and uniform reaction layer formed at the interface between the steel insert and aluminum matrix compared to aluminized coated insert. The results of push-out tests indicated higher interfacial shear strength for the bimetal with Cu-coated insert despite possessing a larger thickness.

Crystallized FeB and Fe2B powders were synthesized by a molten salt method with elemental Fe and B powders as starting materials. The results indicated that the presence of molten NaCl/KCl salts and the excess of Fe or B powders were essential to obtain pure FeB or Fe2B powders. The formation mechanism of iron borides was investigated by examining the phase compositions of the obtained products with different molar ratio of Fe/B. It was found that Fe powders firstly reacted with B powders to form Fe2B phase, and FeB phase formed from the reaction between Fe2B and excessive B. The as-synthesized FeB and Fe2B powders had a uniform short-rod and plate like morphology, respectively. Both FeB and Fe2B exhibited typical soft magnetic behavior. The saturation magnetization and the coercivity were 36.4 emu/g and 15.5 kA/m for FeB, 126.9 emu/g and 6.1 kA/m for Fe2B, respectively. The electrochemical performances of the as-synthesized FeB powders were evaluated by cyclic voltammetry, galvanostatic charge–discharge and electrochemical impedance test.

High iodine containing oxides are of interest as biocidal components in energetic applications requiring fast exothermic reactions with metallic fuels. Aerosol techniques offer a convenient route and potentially direct route for preparation of small particles with high purity, and are a method proven to be amenable and economical to scale-up. Here, we demonstrate the synthesis of various iodine oxide/iodic acid microparticles by a direct one-step aerosol method from iodic acid. By varying temperature and humidity, we produced near phase pure δ-HIO3, HI3O8, and I2O5 as determined by X-ray diffraction. δ-HIO3, a previously unknown phase, was confirmed in this work. In addition, scanning electron microscopy was used to examine the morphology and size of those prepared iodine oxide/iodic acid particles and the results show that all particles have an irregularly spherical shape. Thermogravimetric/differential scanning calorimetry measurement results show that HIO3 dehydrates endothermically to HI3O8, and then to I2O. I2O5 decomposes to I2 and O2.

Aluminum (Al) nanoparticles are synthesized by wire explosion process (WEP) in an inert ambience of argon. Thermodynamic analysis and structural characterization of nano Al particles are made in the present work. Transmission electron microscopy (TEM) characterization has shown that the Al nanoparticles produced are spherical in shape and it follows a lognormal distribution. A unimodal size dependent thermodynamic model is formulated to understand the size dependent thermal behavior of aluminum nanoparticles. Three different melting modes such as, homogeneous melting mode (HMM), liquid skin melting (LSM) and liquid nucleation and growth (LNG) are assumed to understand the melting behavior of aluminum nanoparticles synthesized by the WEP process. The effect of saturation ratio on the nucleation rate and the impingement factor is also discussed. The size dependent melting and enthalpy of fusion of Al nanoparticles predicted by thermodynamic model are in tandem with the DSC results.