Groups of chloromethyl were randomly grafted to Janus composite particles and quaternization was carried out on the particles. The Janus material of titania–quaternary ammoniated poly(vinylbenzyl chloride–divinylbenzene) (TiO2–QApoly(VBC–DVB)) was investigated in detail. Results revealed that the anisotropic Janus material containing quaternary ammonium groups was synthesized successfully. The Janus material could be used as the phase transfer catalyst. The catalytic activity of the Janus material was confirmed by the esterification reaction of benzyl chloride and sodium acetate. In the presence of 0.5 wt.% (relative to benzyl chloride) of TiO2–QApoly(VBC–DVB), the esterification yield of benzyl acetate reached 87.6% when the molar ratio of sodium acetate anhydrous to benzyl chloride was 1.2. The catalyst exhibited a high activity and had no obvious loss of activity when recycled three times. Moreover, the Janus material was easily recovered by centrifugation and washed with ethanol and water.

A systematic experimental study on the exchange bias (EB) effect in a ferromagnet/antiferromagnet bilayer system is performed both in the static (dc) and dynamic (high frequency) timescale to clarify the effects of temperature and antiferromagnetic (AFM) layer thickness on the system's stability and magnetic properties. Our system consists of NiFe/IrMn. Both parallel and perpendicular domain walls are suggested to explain the static EB and coercivity behaviors. In the microwave region, peaks, which can only be suppressed at high temperatures with strong external fields, were observed in the AFM thickness dependencies of the dynamic effective field and resonance frequency. The temperature dependence of both static and dynamic parameters suggests different values of Néel temperatures. The dynamic results show a rotatable anisotropy contribution, which has a peak value at the blocking temperature and vanishes at the dynamic Néel temperature.

Zr-based bulk metallic glasses are promising engineering materials due to their good glass-forming abilities and unique combination of good strength (∼1.9 GPa) and medium stiffness. In this study, the corrosion behaviors of Zr–Co–Al–Ag BMGs, with silver content from 0 to 11 at.%, in NaCl and H2SO4 solutions were investigated. The corrosion resistance increased when the silver content increased. The oxidation behaviors of Zr–Co–Al–Ag BMGs were also studied. The oxidation kinetics of all the samples obeyed a two-stage parabolic rate law, which consisted of an initial transient oxidation followed by a steady-state oxidation stage. The addition of Ag was found to reduce the oxidation resistance of Zr–Co–Al–Ag BMGs. Some white nodules, possibly cobalt oxide, were observed when the Zr–Co–Al–Ag BMG with 8 at.% Ag was oxidized at high temperature.

A comprehensive understanding of the growth pattern of intermetallic compounds (IMCs) during solidification is critical to both the crystal-growth theory and its property optimization. In this article, growth pattern and three-dimensional (3D) morphology of primary Al6Mn IMC were investigated in directionally solidified Al–3 at.% Mn alloy at a wide range of growth rates. A transition from faceted (<60 μm/s) to nonfaceted growth (>100 μm/s) was observed with increasing growth rates. Correspondingly, 3D morphologies of primary Al6Mn change from a solid polyhedron to a hollow structure, and then to a dendrite. This kind of change is associated with the competitive growths of different crystal planes determined by the crystallographic anisotropy and growth kinetics of Al6Mn. A growth model based on atomic cluster attachment is proposed to reveal the growth transition, and a growth-rate ratio between different crystal planes is used to appropriately reveal the formation mechanism of different morphologies at low rates.

Thermally stable nanosized Al2O3 particles and carbon nanotubes (CNTs) are comparatively effective in simultaneous improvement of strength and ductility of wrought magnesium alloy AZ31 when incorporated in microstructure. Understanding the comparative effectiveness of these nanosized reinforcements on the high temperature deformation process of wrought AZ31 alloy is important for its potential wider automotive body application. The current study has revealed that both reinforcements are competitively effective in inducing matrix grain and intermetallic particles refinement and strengthening almost to a theoretically predicted value. Although high temperature flow stress of AZ31 was found to closely match due to incorporation of both of the nanosized reinforcements, alumina was more efficient in improving the failure strain of matrix alloy. Addition of remarkably a small amount of nanosized alumina particles or CNTs introduced huge potential in near net shape formability of AZ31 alloy at a temperature much below than the widely used 350 °C. Among the two reinforcements used in this study, alumina was found to be more efficient when compared to the effect of CNTs.

The modification of near-eutectic Al–Si alloy with samarium additions (0–0.9 wt.% content) has been studied. The thermal analysis results indicated that the addition of Sm in Al–12Si alloy caused a depression of eutectic temperature (∆T E). And it was found that Sm was capable of breaking down the primary α-A1 phases, giving rise to an increment in the number of dendrites. Simultaneous primary Si refinement and eutectic modification were achieved by Sm addition. When 0.6 wt.% Sm was added to the alloy, the silicon in Al–12Si alloy was best refined and showed a fully modified, fine fibrous eutectic structure; the primary α-Al phase appears as a slightly dual dendritic-cellular nature and a pine-tree structure. Moreover, the mechanical properties were investigated by the tensile test. A good combination of ultimate tensile strength (217 MPa) and elongation (1.3%) was obtained when the addition of Sm was up to 0.6 wt.%.

This paper discusses tensile testing of small samples of nanocrystalline Al6061-T6 alloy obtained from an unusual application of machining as a severe plastic deformation process. Ultrafine grained (UFG) shavings obtained from plane-strain cutting show higher hardness than the bulk material in agreement with existing literature. Application of restricted contact tools and extrusion-machining was explored to obtain shavings with minimum curvature to aid in tensile test specimen preparation. A novel method to prepare small tensile test specimens from these shavings has been described. During the tensile testing of UFG material, strains were measured using digital image correlation of natural speckles on the specimen. Specimens made from the UFG material had higher tensile strength and yield stress than the bulk, while ductility was lower. Lower values of Young's modulus were observed during the tensile testing of small specimens made from UFG as well as bulk material.

The fabrication of a temperature sensor based on graphene nanoplatelets (GNPs) is reported. A preheat process was carried out and the micrographs of both original and preheat-treated GNPs are observed and compared. Nonlinear temperature variation of resistance is observed and humidity interference is found to be negligible. Region of 10–60 °C (the linear region) is selected as the sensor range and further studied. High sensitivity of GNPs can be seen and the temperature coefficient of resistance (TCR) of 0.0371 is calculated, higher than that of multiwall carbon nanotubes (MWCNTs) and many other materials reported in references. Great repeatability and small hysteresis are obtained. The time constant of the GNPs film is about 5 s, much shorter than that of MWCNTs film. The result suggests that GNPs have potential applications for use in highly sensitive and fast-response temperature sensors.

MTiO3 (M = Ca, Ni, and Zn) nanocrystals were prepared via a facile ethylene glycol-mediated synthesis route followed by calcination in air. The structures and morphologies of nanocrystals were characterized by x-ray diffraction, Raman spectroscopy, transmission electron microscopy, and scanning electron microscopy. The results indicated that CaTiO3 and NiTiO3 are orthorhombic phase, while the ZnTiO3 is orthorhombic phase. The activity of the CaTiO3 nanocrystals for water splitting into H2 was obviously higher than those of the NiTiO3 and ZnTiO3 nanocrystals, which could be attributed to the more negative conduction band position of CaTiO3 than NiTiO3 and ZnTiO3. The Brunauer–Emmett–Teller system-based surface areas of samples are 19.03, 21.13, and 4.17 m2/g for CaTiO3, NiTiO3, and ZnTiO3 nanocrystals, respectively. In addition, the activity of the CaTiO3 nanocrystals increased with increase in the sintering temperature of samples.

Silver-decorated titanium dioxide (Ag/TiO2) nanotube (NT) arrays were successfully prepared using a two-step synthesis route comprised of an anodic oxidation procedure followed by photochemical reduction using ultraviolet irradiation. The resulting Ag/TiO2 NT arrays were characterized using scanning electron microscopy, transmission electron microscopy, x-ray diffraction, and UV-vis diffusion reflectance spectrometry. The characterization results indicated that the silver decoration significantly enhanced the light absorption capability of the TiO2 NT arrays in the visible spectral range. The visible light photocatalytic activity of the subject NT arrays was investigated. The experimental results showed the photocatalytic activity of silver-decorated titanium dioxide Ag/TiO2 NT arrays to be dependent on the size of the silver particles. The improved visible light absorption can be attributed to plasmonic effects induced by particle size phenomenon. The Ag/TiO2 NT arrays exhibit promising application for photocatalytic degradation of dye solutions and pollutants in water using visible irradiation.

Solution-processed CuInGaS2 (CIGS) thin-film solar cells are promising for large-scale commercialization due to their economic process although the efficiency still needs to be improved to compete with vacuum-based materials. Systematic studies were performed to optimize the series and shunt resistance of hydrazine-based CIGS solar cells. Optimization was achieved through compositional adjustment of copper (Cu) near the p–n junction and gallium (Ga) near the back contact. Cu adjustments optimized the shunt resistance between 4000 and 5000 Ω cm2. Ga adjustments optimized the series resistance to 2 Ω cm2. Shunt and series resistance play vital roles in the fill factor. Fill factor was hence improved upward of 0.80 with the optimization of Cu and Ga. Chemical etching was also conducted to investigate the durability of the materials and to remove small crystals near the interface. Device conversion efficiencies were improved up to 12.4%. This study provides the implications for improving the device performance of chalcogenide solar cell materials.