We evaluate the potential of inserting metallic, metal-dielectric core-shell, and fully dielectric nanoparticles in ultrathin chalcopyrite solar cells to enhance absorption which experiences a significant drop for absorber thicknesses below 500 nm. For different integration positions at the front or at the rear of the solar cell structure theoretical expectations and potential benefits originating from light scattering, near-field enhancement and coupling into waveguide modes by the nanoparticles are presented. These benefits are always balanced against experimental challenges arising for particular geometries due to the very specific fabrication processes of chalcopyrite solar cells. In particular high absorber deposition temperatures as well as contact layers that are relatively thick compared to other devices need to be considered. Based on this, we will need to go beyond some geometries that have proven beneficial for other types of solar cells and identify the most promising configurations for chalcopyrite-based devices.

Hot indirect extrusion behaviors of fully dense 3 mol% Y2O3-stabilized ZrO2 polycrystals with a grain size of 80 nm were investigated by using a conical graphite die. During early extrusion at 1843 K and a constant compression stress of 60–80 MPa, the relative moving billet velocity (v0) shows a sharp maximum, followed by a continuous decrease until it reaches a steady-state v0 value. Visual observations of the material flow by using graphite foil markers indicate that the deformation zone at the steady-state v0 is well represented by a spherical velocity field. The decrease in v0 corresponds to the transition from heterogeneous to homogeneous deformation. The stress exponent (n) of 2.07 was obtained from the log–log plots of the steady-state v0 versus the external applied stress that is compensated by threshold and sliding friction stresses. This n value suggests plastic deformation through grain-boundary sliding in indirect extrusion.

A new lab-based aerosol jet fog (ajFOG) deposition system with an atomizer consisting of two opposing jets located within the deposition chamber is introduced and its capabilities are examined. The unique opposing configuration of the atomizer enables the formation of a highly uniform fog even from low volatility precursors. Aluminum oxide phosphate (AlPO) thin films were deposited onto Si wafers at room temperature and sub-atmospheric pressure by using an aqueous precursor. Films were characterized by spectroscopic ellipsometry, x-ray diffraction and reflectivity, scanning electron microscopy, and metal/oxide/semiconductor (MOS) capacitor electrical measurements. Film thickness uniformity, density, surface roughness, and charge transport mechanisms were found to be comparable to spin-coated thin films deposited using the same precursor, demonstrating the effectiveness of this aerosol technique. A process model was developed to predict film thickness as a function of precursor concentration, exposure time, fog settling time, and number of exposures.

The potency of many biomedical applications of gold nanoparticles (AuNPs); i.e., (i) bioimaging, (ii) diagnostic, (iii) therapeutic, (iv) drug carriers, and (v) immunochemical properties; are limited due its sensitivity toward salt and pH allowing variation in nanogeometry during practical applications. Such limitations directed the synthesis of AuNPs having extreme salt and pH resistant ability which has been undertaken in current research program. It has been found that the pH and salt tolerance ability of AuNPs are dependent on the nature of reducing and stabilizing agents. The use of organic amine containing reagents, i.e., polyethylenimine, 3-aminopropyltrimethoxysilane, in the presence of formaldehyde is examined that allows controlled and rapid synthesis of AuNPs having salt and pH tolerance ability. The mechanism justifying these properties of as-made AuNPs are presented herein. These reagents not only allow the synthesis of monometallic nanoparticles (NPs) but also enable the synthesis of bimetallic and trimetallic NPs. The synthesis of Au–Ag/Ag–Au, Pd-Au/Ag@(PdAu) NPs are examined involving the contribution of organic amine.

An electrodeposition method for growing epitaxial Co(OH)2 films on single crystalline gold (111), (100), and (110) substrates is described. The films were grown by electrochemical reduction of [Co(en)3]3+ in an alkaline electrolyte. The Co(OH)2 grew with a [0001] out-of-plane orientation on all the gold crystal orientations. The in-plane orientation follows the symmetry of the gold (111), (100), and (110) substrates. The Co(OH)2 can be converted to CoOOH by electrochemical oxidation in 1 M KOH at 95 °C, and after conversion remains epitaxial with a [0001] out-of-plane orientation. The CoOOH film can be further converted to epitaxial Co3O4 with a [111] out-of-plane orientation by decomposition of the CoOOH film in air at 300 °C. This synthesis method allows for a simple fabrication of epitaxial catalysts and could be useful to probe the catalytic activity of specific crystal planes.

The isothermal oxidation experiments were carried out on several new γ/γ′-strengthened cobalt-base alloys Co–Al–W–4Cr–0.02X (X = La, Ce, Dy, Y) at 900 and 800 °C. Due to an appropriate content of additional elements, the change in the morphology occurred and it significantly improved the oxidation resistance compared with those without Cr, among which the one with La elements shows the best oxidation resistance. Multiple oxide layers are also formed during the oxidation process, with CoWO4 and CoAl2O4 phases in the outer layer, and Cr, Al, W, and Co (e.g., Cr2O3) in the middle layer. The inner layer consists of some Al2O3 oxides, while more protective Al2O3 oxide was formed, esp. at the temperature of 800 °C. Both Cr2O3 and Al2O3 oxides were effectively protective oxides, which can prevent the intrusion of oxygen into the alloy substrate. Moreover, a phase transformation (γ/γ′ to γ/Co3W) was observed at the interface between oxide layer and substrate.

There has been controversy over the localized corrosion mechanism of super-austenitic stainless steel weld due mainly to the lack of effective evaluation technique for identification of corrosion nucleation site in weld. For this reason, an electrochemical polarization method followed by an observation of microstructure using the back-scattered electron mode in field emission-scanning electron microscopy is used. To clarify the localized corrosion mechanism, energy dispersive spectroscopy line profile analyzed by transmission electron microscopy is additionally utilized. It clearly reveals that the selective corrosion is preferentially initiated around the σ-phase precipitated in the interdendritic region in weld. The local depletion of Cr and Mo around the σ-phase can be partly replenished by the diffusion of the elements into the depleted area during the subsequent heat treatment at 1180 °C.

Mo2Ni3Si–Al2O3 nanocomposite was synthesized using MoO3, Ni, Si, and Al as starting materials by mechanical alloying. The mechanically alloyed powders were consolidated by hot pressing. The morphology and structural evolution of composite powders were investigated by scanning electron microscopy (SEM) and x-ray diffraction (XRD). The microstructure and mechanical properties of the consolidated products were studied in detail. The results showed that Mo2Ni3Si–Al2O3 composite was obtained after 10 h of milling. The reaction mechanism mechanically induced self propagating reaction. The mean grain size of Mo2Ni3Si and Al2O3 after milling for 20 h were 15.9 and 32.4 nm, respectively. The Mo2Ni3Si–Al2O3 composite powders are stable during an annealing at 1000 °C. After consolidation, Mo2Ni3Si–Al2O3 composite has a high density (96.3%) and fine-grain (microns and submicrometer range). The hardness, flexure strength, and fracture toughness of Mo2Ni3Si–Al2O3 composite are 13 GPa, 533 MPa, and 6.29 MPa·m1/2, respectively. Meanwhile, the composite has higher strength at high temperature, and the strength remains stable up to 1000 °C (about 513 MPa).

In this study, the effects of Ag variations on dynamic recrystallization (DRX), texture, and mechanical properties of ultrafine-grained Mg–3Al–1Zn alloys are investigated. The results suggest that Ag segregation and Al–Zn–Ag clusters form in the Mg matrix with Ag addition less than 1 wt%, which retard DRX and the growth of the DRXed grains. The resulting grain size decreases from 513 to 316 nm. As the Ag addition increases to 2 wt%, the Mg54Ag17 phase precipitates along the grain boundary, which plays an important role in restricting DRXed grain growth via grain boundary pinning effect. The resulting grain size is 375 nm with a bimodal grain size distribution. The extrusion texture of the investigated alloys is in fairly scattered orientation distribution. The weak basal texture and ultrafine grain size lead to the high yield asymmetry ratio. The Ag-containing extruded alloys exhibit an increase in the tensile and compressive properties. The strengthening mechanisms due to grain refinement, dislocations, solid solution, precipitates, solute clusters, and segregation are discussed.

Various routes (unidirectional, cross, and three directions) normal and different speed rolling (DSR) are conducted on pure titanium sheet at 673 K and sequent 933 K annealing is followed. The results show that transverse direction (TD)-split double peak texture is kept during unidirectional rolling and a fiber basal texture is formed after cross and three-direction rolling. However, TD-split texture is preserved and rotates about 45° while the fiber basal texture is generated after cross and three direction rolling combining (DSTDR) DSR, respectively. This may be related to the changed strain path and induced shear deformation as well as thermal activation. Due to rotation of grains, the anisotropy of mechanical properties of Ti sheets decreases, especially in various DSR routes. Erichsen value is improved greatly in DSTDR specimens.

The effects of W, Re, Cr, and Mo on microstructural stability, such as the morphology of γ′ phase and the topologically close-packed (TCP) phase precipitation are systematically investigated in eleven kinds of Ni-based single crystal superalloys containing certain amounts of Co, Al, and Ta. After heat treatment, all the designed alloys show different sizes of γ′ phases with typical cuboidal morphology occupying 75% of the total volume. With increasing Re content, the size of γ′ decreases obviously, while the size of γ′ decreases slightly with increasing Cr and Mo contents. Increasing W does not affect the size of γ′. As a result of thermal exposure at 1000 °C for 1000 h, some acicular, rod-like, and blocky TCP phases are precipitated in most alloys. It is noted that Mo and Re can strongly promote the precipitation of TCP phase, but W has no obvious effect on TCP phase precipitation. In addition, transmission electron microscope analysis indicates that these TCP phases are σ phase, μ phase, and R phase.

In this study, we used thermo–mechanical control process (TMCP) technique to investigate the effect of arisen dislocation density and texture components on hydrogen induced cracking susceptibility in as-received API X60 pipeline steel. Dislocations and texture components appeared during cold rolling and annealing treatments. X-ray diffraction and electron backscatter diffraction measurements were used to study these phenomena. We observed that the cold rolling and annealing treatments produced higher dislocation density in deformed and recovered regions. The increase of dislocation density also caused the increased hydrogen trap density. Macro-texture studies by x-ray method indicates that initial weak texture of as-received X60 steel was changed from ζ-fiber to γ-fiber and θ-fiber in 90% cold rolled and annealed specimen. Therefore, the number of grains with 〈100〉||ND orientation which had a harmful effect on hydrogen induced cracking susceptibility increased. The {100} dominant texture and high density of hydrogen traps mitigated against any possible benefits of the other microstructural parameters such as coincidence site lattice boundaries and grain size. As a result, we could not consider this process as a suitable method to increase hydrogen induced cracking resistance in pipeline steel.

The effect of Ta concentration on the fundamental mechanical properties of W–Ta alloys has been studied from first principles study. The lattice constants, the cell volumes, and the formation energies of the W1−x Ta x (x = 0.0625, 0.125, 0.1875, 0.25, 0.3125, 0.5, 0.5625, 0.625, 0.75) alloys were calculated. It is shown that Ta alloying in bcc W lattice is an infinite solid solution and the W0.5Ta0.5 have the lowest formation energy. With the optimized geometry and lattice, the elastic constants are calculated and then the elastic moduli and other mechanical parameters are derived. Results show that although the mechanical strength of the W–Ta alloys is lower than that of pure W metal, it is much higher than that of pure Ta metal. On the other hand, the B/G ratio and the Poisson's ratio of the W–Ta alloys is much higher than that of pure W, and even higher than that of pure Ta, indicating that Ta alloying can improve the ductility of bcc W substantially.

The oxidation behavior of bulk ZrSi2 at 700, 1000, and 1200 °C in ambient air has been investigated. Parabolic to cubic oxide layer growth kinetics was confirmed by weight gain measurements and the average oxide layer thickness was 470 nm, 6.7 µm, and 37 µm at 700 °C, 1000 °C, and 1200 °C, respectively, after 5 h oxidation tests. Evolution of compositionally modulated nano/micro structures was confirmed in the oxide layer. At 700 °C, Si diffusion resulted in discontinuous Si-rich oxide phases in amorphous Zr–Si–O matrix. At 1000 °C, complex multilayered structures such as fine and coarse irregular spinodal structures, wavy Si-rich oxide, and Si-rich islands evolved. At 1200 °C, additional nucleation of nanoscale ZrO2 particulate phase was observed. The spinodal structures were confirmed to be crystalline ZrO2 and amorphous SiO2, and the thermodynamic driving force for phase evolution has been explained by extension of liquid miscibility gap in the binary ZrO2–SiO2 phase diagram.

A self-made die with large cross section (180.2 × 22.2 mm) for equal channel angular pressing (ECAP) was used to study the influence of two different pressing routes (C X and C Y ) on refining homogeneity of high-purity aluminum plates. Microstructures were investigated by optical microscopy (OM) and electron back scatter diffraction (EBSD) methods, and micro-hardness and tensile tests were taken to evaluate deformation degree across the cross section and mechanical properties, respectively. The results indicate that pressing routes of ECAP have a great influence on structure homogeneity of plate samples. The route C Y leads to fine grains with better homogeneity because the same deformation direction is taken through each pass. Coarse columnar crystals with 3–4 mm change to 68.6 μm nearly equiaxed grains and a strong cube texture forms after four C Y passes, and corresponding mechanical properties increase by a factor compared to as-cast plate.

In the present paper, 10 vol%TiC/Ti–6Al–3Sn–3.5Zr–0.4Mo–0.75Nb–0.35Si composite produced via in situ casting technique was tested in the temperature range from room temperature to 900 °C and much attention was paid on the microstructural evolution during high-temperature tensile test. It was found that the variation of microstructures in deformation zones with strain exhibited different trends at different temperatures. Below 600 °C, dislocation density increased with strain over the entire strain range. As temperature increased to 700 °C, dislocations proliferated rapidly in the initial deformation and then dislocation annihilated through dynamic recovery. Above 800 °C, the variation of microstructures in deformation zones with strain was similar to that at 700 °C at the beginning but at higher strain, dynamic recrystallization (DRX) occurred, leading to the formation of equiaxed microstructure. Microstructural evolution in deformation zones corresponded to the variation of tensile stress–strain characteristics with temperature, reflecting the hardening or softening feature of matrix. Dynamic recovery ascribed to the flow softening of the composite at 700 °C, while flow softening is owing to dynamic recovery and DRX above 800 °C. In addition, matrix softening should show different trends in different temperature ranges.

The hot deformation behavior of as-cast AZ91 magnesium alloy reinforced by SiC nanoparticles (SiCp/AZ91 nanocomposite) was investigated using hot compression test. Compared with unreinforced AZ91 alloy, peak stress of the SiCp/AZ91 nanocomposite achieved faster and high temperature deformation ability which was enhanced by the addition of SiC nanoparticles. The values of n for the AZ91 alloy and nanocomposite were 6.9 and 4.6, while the values of Q were 207.96 kJ/mol and 184.6 kJ/mol, respectively. The processing map showed the optimum processing conditions for the nanocomposite mainly concentrated at 523–673 K/0.018–0.001 s−1 and the maximum power dissipation efficiency was found to be 36% at a temperature of 673 K and the strain rate of 0.001 s−1. Based on the constitutive equation and processing map, the deformation mechanism for the present nanocomposite should be dominated by the mechanism of dynamic recrystalization.

Different volume fractions (0.5–4.5 vol%) of carbon nanotubes (CNTs) were used to reinforce a binary Fe50Co soft magnetic alloy. The first method for dispersion involved dry mixing and ball milling of the powder, while the second included wet mixing in dimethylformamide under ultrasonic agitation, drying and then dry ball milling. The powders were consolidated using spark plasma sintering. Tensile test and SEM analyses were performed to characterize the mechanical properties and the fracture surface of the sintered materials. The best magnetic and mechanical properties were achieved using the first method. A maximum enhancement in tensile strength of around 20% was observed in the 0.5 vol% CNT composite with improved elongation compared to the monolithic Fe50Co alloy. In addition, the magnetic properties were enhanced by adding CNTs up to 1 vol%, and an improvement in densification was observed in composites up to 1.5 vol% CNT with respect to monolithic Fe50Co alloy.

An eco-friendly, green aqueous technique for the preparation of NiO–Ag bimetallic and its individual monometallic nanoparticles (NPs) is succinctly described by utilizing nontoxic and abundantly available tannic acid at room temperature. The so-synthesized nanoscale particles were characterized using various techniques including HRTEM, DLS, zeta potential, SAED, SEM, EDAX, XRD, IR, and UV–vis spectroscopy. These monometallic and bimetallic NPs have a narrow size distribution with spherical morphology. Moreover, the average diameters of all these three different NPs are almost identical and ranges from 7 nm to 10 nm as measured from HRTEM. DLS readings further confirm that the so synthesized particles are in nano range. A comparative catalytic efficacy of the ensuing nanoparticulate materials were assayed employing photodegradation and chemical reduction of methyl violet (MV) at room temperature. NiO–Ag NPs exhibits higher catalytic potential and it took only 15 min to completely reduce MV in presence of NaBH4. The rate constants for both the chemical reduction and photodegradation reactions follow the order: kNiO–Ag bimetallic NPs > kNiO NPs > kAg NPs > kuncat. Higher catalytic performance of the bimetallic system is reckoned on composition effect which basically results due to synergistic electronic effect.