Experimental evidences for a recently proposed mechanism of tin-induced crystallization of amorphous silicon are presented. The mechanism discusses a crystalline phase growth through cyclic processes of formation and decay of a super-saturated solution of silicon in molten tin at the interface with the amorphous silicon. The suggested mechanism is validated using a nonlinear dynamical model that takes into account the mass diffusion of the components of the system, heat transfer caused by latent (crystallization) heat release and amorphous silicon dissolution events, and concentration nonuniformities created by silicon crystallization. The analysis of a stationary-state solution of the model confirms the existence of periodic solutions for the partial volume of the crystalline phase and other system's variables. Possible applications of the proposed mechanism in manufacturing of cost-effective nanocrystalline silicon films for the third-generation solar cell technology are discussed.

Soft, sensitive, and conformable strain sensors can provide tactile sensation to prosthetic limbs and can be used for epidermal and wearable health monitoring. High strain sensitivity is often achieved by using piezoelectric ceramics, such as lead zirconate titanate (PZT), with known issues for large-area scalability, rigidity, and biocompatibility. Here, we report a nature-inspired, piezoresistive, soft, and benign core–shell nanofibrous sensor that exhibits an unprecedented gauge factor in excess of 60, arising from a reversible disjointing/jointing of a large number of interfiber junctions, consequently changing the current path and resistance in response to both tensile and compressive strains. Nanofiber textile sensor arrays are demonstrated with fast, low-voltage, accurate, and repeatable sensing over 1000 cycles for epidermal monitoring of limb and musculoskeletal movements and radial pulse waveform, for real-time monitoring of simulated intermittent Parkinson's tremors, and for biaxial tactile sensing and localization of point of touch.

Coal is an attractive fuel owing to its low price linked to its worldwide availability but combustion of coal generates very corrosive media especially near the superheater tubes. The present investigation is an attempt to evaluate the hot corrosion behavior of detonation-gun sprayed coatings of Cr3C2–NiCr, NiCrAlY + 0.4 wt% CeO2, and NiCoCrAlYTa on superfer 800H, exposed to low temperature super-heater zone of the coal-fired boiler. The specimens were hanged in the platen super-heater of coal-fired boiler where the gas temperature was around 900 °C ± 10 °C. Hot corrosion experiments were performed for 10 cycles, each cycle consisting of 100 h exposure followed by 1 h cooling at ambient temperature. All three coatings deposited on superfer 800H imparted better hot corrosion resistance than the bare uncoated one. The Cr3C2–NiCr coated superalloy performed better than the other two coatings in the given boiler environment.

The present research is focused on studying the evolution of microstructure and texture of a magnesium based alloy with the target composition Mg–3Al–1Zn–(0.5AgIn). Three samples A, B, and C were warm rolled at 300 °C to a cumulative reduction of 33% in 1, 2, and 8 passes, respectively. The optical microstructures and scanning electron microscopy (SEM) results revealed that sample A possessed more dynamic recrystallization (DRX) as compared to samples B and C. A split of basal pole from normal direction (ND) toward transverse direction (TD) was observed for sample A. However, as the number of passes was increased, the basal pole split was converted into a single peak for samples B and C. The basal intensity of sample C became almost double than that of sample A. It was concluded that a higher reduction per pass resulted in a larger volume fraction of DRXed grains and a weaker basal texture.

Model Fe–9Cr–xMo alloys with high Mo content alloys were cast to investigate the effect of Mo on the phase evolution and properties of the alloys. The Mo contents in the alloys were 5, 7, and 9 wt%, while the Cr content was held constant at 9 wt%. For comparison, a commercial A213T 9-P9 (Fe–9Cr–1Mo) alloy, widely used in the petrochemical industry, was also investigated. The alloys were heat-treated at temperatures between 450 and 650 °C and characterized by scanning electron microscopy, x-ray dispersive energy spectroscopy, and electron backscatter diffraction. Potentiodynamic linear polarization technique was used to evaluate the corrosion of the alloys in a 0.5 mol L−1 H2SO4 solution containing 0.1 mol L−1 NaCl. The results showed that the corrosion resistance of the alloys was affected by precipitation of the µ phase and that the Mo content in excess of 5% is deleterious to the corrosion resistance of the Fe–Cr–Mo alloys.

The interfacial reactions in Cu/Sn–52In/Cu interconnects during solid–solid (S–S) and liquid–solid (L–S) electromigration (EM) under a current density of 2.0 × 104 A/cm2 at 90 and 150 °C have been in situ studied using synchrotron radiation real-time imaging technology. The In atoms directionally migrate toward the cathode due to the back-stress induced by the preferential migration of the Sn atoms over the In atoms toward the anode during the S–S EM, resulting in the segregation of the Sn and In atoms at the anode and cathode, respectively. During the L–S EM, however, the In atoms directionally migrate toward the anode due to the negative effective charge number (Z*) of In rather than the back-stress. The polarity effect, i.e., the intermetallic compounds growing continuously at the anode while becoming thinner at the cathode, is more significant during the L–S EM than the S–S EM. Furthermore, the consumption rate of the cathode Cu during the L–S EM is three orders of magnitude higher than that in the case of the S–S EM because of the significantly higher EM-induced atomic flux in the liquid solder. The migrations of the Sn, In, and Cu atoms are discussed in terms of diffusion flux.

We have investigated the effects of crystal structure and size of Li[Ni1/3Co1/3Mn1/3]O2 (L333) cathodes on the performance of lithium-ion batteries. Cation ordering and particle sizes were determined as a function of annealing temperature with subsequent electrochemical performance monitored by cyclic voltammetry (CV) and charge–discharge testing. With increasing annealing temperature, L333 exhibits a greater cation ordering, which subsequently benefitted cell performance. However, higher annealing temperatures yielded larger crystal sizes, which resulted in a decrease in high rate discharge capacity and a significant capacity fade. This is attributed to an increase in lattice parameter and volume expansion during cycling, with the largest crystal sizes displaying the most significant structural changes due to the lower strain accommodation.

Transmission electron microscopy (TEM) studies provide mechanistic understanding of nanoscale processes, whereas advanced synchrotron XRD (SXRD) enables precise measurements on volumes that are more representative of bulk materials. Therefore, the combined strengths of these techniques can provide new insight into irradiation-induced mechanistic processes. In the present study, their application to Zircaloy-2, proton-irradiated to 2.3, 4.7, and 7.0 dpa at 2 MeV and 350 °C and neutron-irradiated to 9.5 and 13.1 × 1025 n m−2 are exemplified. The application of correlative spectral imaging and structural TEM investigations to the phase transformation of Zr(Fe,Nb)2 precipitates in Low-Sn ZIRLO™, neutron-irradiated to 8.9–9 × 1025 n m−2, demonstrates the possibility of a Cr core nucleation site. Anomalous broadening is observed in SXRD profiles, which is believed to be caused by defect clusters and precursors to dislocation loop nucleation. The challenges to quantitative analysis of dislocations by SXRD are highlighted with reference to the segregation of Fe and Ni to basal planes and dislocation cores, observed by spectral imaging in the TEM.

The effect of gamma radiation in vacuum on the isothermal crystallization kinetics of syndiotactic polystyrene (sPS) was investigated via differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR), and x-ray diffraction (XRD). Amorphous sPS samples were irradiated in vacuum, heated to 310 °C, cooled down to crystallization temperatures (Tcs) from 220 to 260 °C, and annealed for different times. Upon reheating, overlapping endothermic melting peaks depicted the various crystallization forms, α, β, and β′. The endotherms were resolved using Gaussian functions relating enthalpy changes to the endothermic envelope. Isothermal crystallization kinetic data were analyzed using Avrami's model with Gaussian functions. The extent of crystallization of β and β′ forms increased with increasing crystallization time and temperature, while that of α form decreased. Crystallization half-time followed a modified Arrhenius equation. Crystallization activation energies for the β and β′ forms of sPS increased with increasing radiation doses. The results are compared to those of air irradiated sPS reported in the literature.

A novel sort of cellular titanium foam with the porosity of 86–90% and the main-pore size of 0.5–3.0 mm was successfully prepared. Such foam exhibited a compressive curve showing three regimes: the initial elasticity, the middle zigzag plateau, and the final “densification.” This “densification” presented a course that the broken pieces continually accumulated in those pores which were unbroken or not entirely broken. The fracture morphology suggested that the compressive failure was typically brittle for this titanium foam. The electromagnetic shielding performance was investigated in the radio wave frequency range (0.3–3000 MHz) for this foam, which showed an evident effectiveness with a good performance at low frequencies. On the whole, the effectiveness would be superior while the porosity of the sample was relatively small. It could be inferred that the present foam samples would perform their electromagnetic shielding mainly by the reflection loss mechanism in the low-frequency range, and give priority to the absorption loss mechanism at the upper-frequencies.

Novel 1–1.5 μm BiOCl0.5Br0.5 composite microspheres were prepared by coprecipitation method, then calcined at different temperatures. The BiOCl0.5Br0.5 samples before and after calcination were characterized by powder x-ray diffraction, thermogravimetric analysis, N2-physical adsorption, scanning electron microscopy, Fourier transformed infrared spectroscopy, and UV-Vis diffuse reflectance spectroscopy. The photocatalytic activity of the samples was evaluated by photocatalytic degradation of Rhodamine B under visible light irradiation. The results showed that the thermostability of BiOCl0.5Br0.5 composite microspheres is lower than BiOCl and higher than BiOBr. Heat treatment at low 500 °C could obviously improve the crystallinity of BiOCl0.5Br0.5 microspheres, resulting in a significant increase in activity. BiOCl0.5Br0.5 microspheres calcined at 450 °C displayed the highest activity and stability. At elevated temperature calcination (600–800 °C), phase transition occurred over BiOCl0.5Br0.5. Br element was gradually lost and new phase of Bi24O31Br10 appeared. High temperature calcination did not change the morphology of BiOCl0.5Br0.5, but the surface area and surface OH groups decreased, which resulted in a large decrease in activity.

Copper–silver core–shell nanowires were synthesized using a combination of two methods: electrodeposition in a polycarbonate membrane as a template for the synthesis of a copper core and a galvanic replacement reaction for the elaboration of a silver shell. A comparative study between aqueous and ionic liquid media was performed for the silver shell elaboration. The kinetics of the reaction in both media was monitored by using energy dispersive x-ray spectroscopy. The shape and size of the nanowires were observed by both scanning electron microscopy and transmission electron microscopy. The core–shell structure was determined by electron energy loss spectroscopy analyses for the Cu90Ag10 composition. A homogenous silver shell was formed in aqueous media. Whereas in ionic solvent, well defined silver crystals were obtained at the surface of the nanowires but without a total formation of a silver shell structure.