We report on a kerfless exfoliation approach to further reduce the costs of crystalline silicon photovoltaics making use of evaporated Al as a double functional layer. The Al serves as the stress inducing element to drive the exfoliation process and can be maintained as a rear contacting layer in the solar cell after exfoliation. The 50–70 µm thick exfoliated Si layers show effective minority carrier lifetimes around 180 µs with diffusion lengths of 10 times the layer thickness. We analyze the thermo-mechanical properties of the Al layer by x-ray diffraction analysis and investigate its influence on the exfoliation process. We evaluate the approach for the implementation into solar cell production by determining processing limits and estimating cost advantages of a possible solar cell design route. The Al–Si bilayers are mechanically stable under processing conditions and exhibit a moderate cost savings potential of 3–36% compared to other c-Si cell concepts.

Deformation mechanics in equal channel angular pressing (ECAP) was studied in situ using digital image correlation (DIC) and infra-red (IR) thermography. In a prototypical experiment in an optical and IR transparent die, the deformation of commercially pure lead (Pb) is observed using high-speed optical and IR cameras. From the resulting time-sequence images of metal-flow in the deformation zone, DIC is used to characterize the zone of severe plastic deformation (SPD) as a function of the scale of deformation (sample dimensions), deformation speed, and die geometry. The temperature rise in the deformation zone was characterized using IR thermography and the results were compared against theoretical estimates. These observations provide direct insights into the mechanics of SPD in ECAP, which can offer strategies for microstructure control, process optimization, and miniaturization of ECAP.

In this study, the interfacial adhesion of Cu and TiN on an annealed borophosphosilicate glass (BPSG) in a multilayer material stack was investigated. The two material systems, Cu/BPSG and TiN/BPSG, are representatives for weak and strong interfaces, respectively. A weak and a strong interface was chosen to identify possible differences in the fracture path selection for the multilayer material systems. To investigate this, in situ 4-point-bending experiments were performed under an optical microscope and in a scanning electron microscope. Complementary ex situ 4-point-bending experiments were carried out on the identical material systems. These tests revealed that for the two analyzed systems there is a large discrepancy in the success rate of failure along the interface of interest, which is a prerequisite for determining the corresponding interface energy release rate. This phenomenon can be understood by using theoretical findings of earlier studies reported in the literature, which are in agreement with the experimental outcome of the in situ 4-point-bending measurements presented here.

A series of zeolite–zeolite composites were prepared by a two-step hydrothermal crystallization procedure in which the mixture of presynthesized ZSM-5 zeolite acts as nutrients for the growth of postsynthesized Y zeolite, and the as-synthesized products are denoted as MFI–FAU. The structural, crystalline, and textural properties of the as-synthesized materials, as well as the references Y, ZSM-5, and a corresponding physical mixture composed of Y and ZSM-5 zeolite, were characterized by x-ray powder diffraction (XRD), Fourier transform infrared spectrum (FTIR), temperature-programmed desorption of ammonia, N2 adsorption–desorption, scanning electron microscopy, energy-dispersive spectrometry, and Thermogravimetry. The results show that the ratio of Y to ZSM-5 in the composite can be adjusted by controlling the hydrothermal treatment time of the second-step synthesis. Steric hindrance provoked by the concurrently growing crystals offers the postsynthesized Y zeolite phase, a relatively smaller size. A hierarchical pores system, which results from the extraction of silicon species from ZSM-5 and the polycrystalline accumulation of Y zeolite, has been created in the zeolite–zeolite composite. Catalytic performances of the zeolite–zeolite composite catalysts as well as the references catalysts were investigated during the catalytic cracking of isopropylbenzene. As compared with the corresponding physical mixture, the composite catalysts display the excellent catalytic performances with a higher conversion of isopropylbenzene as well as a longer catalytic life because of the introduced hierarchical pores system and the formation of special composite structure.

A novel method for the analysis of the mechanical properties of thin films is presented and uses a modified Winkler (bed of springs) approach to estimate indentation hardness and reduced modulus using nanoindentation data. This method is especially useful in situations where significant plastic deformation occurs in the thin film resulting in pileup of material and a divergence from accepted tip area calculations. The model has been adapted into a MATLAB® script and its derivation is presented. A proof of concept study was completed using Au thin films over a range of thickness and deposition methods. Results are compared with traditional nanoindentation analysis methods and validated against the Hall–Petch relationship. It can be seen that this modified Winkler approach accurately predicts material pile-up as well as contact area for films up to 500 nm in thickness.

Shape-memory epoxy is receiving considerable attention because of its superior mechanical and thermal properties and excellent shape-memory performance. In this study, a novel series of shape-memory epoxy resins are prepared using hydro-epoxy, hexahydrophthalic anhydride, and diglycidyl 4,5-epoxy tetrahydro phthalate (TDE-85) to further improve the recovery force of shape-memory epoxy resins. The thermal, mechanical, and shape-memory properties of the shape-memory epoxy resin system are investigated by differential scanning calorimetry, dynamic mechanical analysis, bend test, and shape recovery test. Results indicate that the glass transition temperature (Tg), rubber modulus, and room-temperature bend strength increase as TDE-85 content increases. Investigation of the shape-memory behavior of the resin reveals that full recovery can be achieved after only several minutes when the temperature is equal to or above Tg. The shape recovery time decreases with the increase in TDE-85 content at Tg, Tg + 10 °C, and Tg + 20 °C. These results are attributed to the increase in TDE-85 content.

(CrTaTiVZr)Nx coatings were deposited via reactive radio frequency magnetron sputtering. The effects of N2 flow at 0–8 SCCM on the chemical composition, microstructure, and mechanical properties of the films were investigated. The coatings deposited at a N2 flow of ≤2 SCCM showed a featureless structure with an amorphous phase. When the N2 flow was at 4 SCCM, two distinct layers were observed, namely, the bottom layer (close to the substrate) with an amorphous structure and the top layer with a fibrous structure and face-centered cubic phase. When the N2 flow was further increased, the structure was converted from fibers to columns with larger grains. Accordingly, the maximum hardness value of 36.4 GPa was achieved at a N2 flow of 4 SCCM, thereby indicating that (CrTaTiVZr)Nx coatings may be suitable as hard protective coatings.

A flexible Fe2O3–SnO2–graphene (GNs) film material was synthesized based on a method of physical blending. The product is characterized by x-ray powder diffraction, scanning electron microscopy, transmission electron microscopy, and x-ray photoelectron spectroscopy. The results show that the Fe2O3–SnO2 particles are uniformly distributed among GN layers, and the film can be used as working electrode directly without any binder or conductor. The binder-free Fe2O3–SnO2–GNs film shows high charge capacity and good cycling life both in half and full cells. The Fe2O3–SnO2–GNs film delivers an initial discharge capacity of 946 mA h g−1 at 100 mA g−1 and maintains a capacity of 538 mA h g−1 after 90 cycles in half cell. For full cell, the film also exhibits a high capacity of 334 mA h g−1 at 100 mA g−1 after 30 cycles.

The creep behavior of advanced 9%Cr-1 (BM1) and advanced 9%Cr-2 (BM2) dissimilar welded joints was investigated in this paper, and also the microstructures were elaborately characterized. Based on the fitting with MATLAB, a 3-D curved surface describing the primary and steady-state creep stage was achieved. The comparison of the microstructures of the precreep and aftercreep welded joints shows that δ-ferrite distribution in the heat affected zone (HAZ) of BM2 side plays an important role in determining creep rupture strength. Fracture occurred at the overtempered heat affected zone (OT-HAZ) adjacent to BM2 after creep tests at 538 °C under different stress loads. Microhardness tests revealed that the OT-HAZ adjacent to BM2 has the lowest hardness value compared with the whole welded joint. Numerous creep voids occurring around δ-ferrite, carbides, and grain boundaries were observed on the specimen after creep test. They concentrated and grew up to microcracks, and then induced the fracture at OT-HAZ. Many second phases were also observed in the grain boundary after creep, and the tempered martensite boundaries in the HAZ gradually become obscure as the creep time increases.

Laser metal deposition (LMD) additive manufacturing was used to deposit Inconel 625 matrix composites reinforced with nano-TiC particles. The effects of laser energy input per unit length (E) on the densification level, microstructural features, mircohardness, and wear property were investigated. The relatively low E induced insufficient liquid with higher viscosity, thus inhibiting the melted liquid from spreading out smoothly. As a result, a large number of micropores and reduced densification level of LMD-processed parts were obtained. When the E of 100 kJ/m was properly settled, the obtainable densification level generally approached 98.8%. The TiC reinforcements experienced successive microstructural changes from agglomeration to uniform distribution with coarsening grain, as the applied E increased. The nearly fully dense parts using optimal experimental parameters achieved an increased average microhardness of 330 HV0.2, resultant considerably low coefficient of friction of 0.41 and reduced wear rate of 5.4 × 10−4 mm3/(N m) in dry sliding wear tests.

An extruded Mg–8Gd–4Y–1Nd–0.5Zr alloy was preheated at 500 °C for 0.5 h and then subjected to hot compression to a true strain of 0.69 at temperature 450 °C and a strain rate of 0.2 s−1. It is observed that boundaries of small grains (∼3 μm) in the extruded alloy are decorated with irregular-shaped particles; small grains show a weak texture of three main components of $\left\langle {0001} \right\rangle //{\rm{TD}}$ , $\left\langle {11\overline 2 1} \right\rangle //{\rm{ND}}$ , and $\left\langle {10\overline 1 0} \right\rangle //{\rm{ED}}$ . Dynamic recrystallization is concurrent with dynamic precipitation of particles during hot compression, resulting in both a uniform grain structure and a redistribution of particles. The retained particles before compression keep the texture unchanged during compression, leading to the same texture type of $\left\langle {0001} \right\rangle //{\rm{TD}}$ of the compressed alloy as that of the preheated alloy. The compressed alloy exhibits a better aging hardening ability than the extruded alloy. After peak aging, the compressed alloy presents an ultimate tensile strength of 416 MPa, a yield tensile strength of 317 MPa, and an elongation of 2.7%.

We present the results of a mixed-space approach, based on first-principles calculations, to investigate phonon dispersions and thermal properties of Mg2Si and Mg2Sn, including the bulk modulus, Grüneisen parameter, heat capacity, and Debye temperature. It is shown that good agreements are obtained between the calculated results and available experimental data for both phonon dispersions and thermal properties. The phonon dispersions are accurately calculated compared with experimental data due to the high-quality description of LO–TO splitting and transverse acoustic branches along the Γ-K-X symmetry line. We also calculate the heat capacity CP and Debye temperature of Mg2Si1−xSnx alloys (x = 0.375, 0.5, 0.625, 0.875). The CP values at high temperature range from 0.5 to 0.7 J/g/K and ΘD values at room temperature from 332 to 384 K as the Sn content decreases from 0.875 to 0.375.

A phase transfer method was developed to prepare Mg(OH)2 nanosheets and a subsequent adsorption–calcination process was followed to obtain lamellar MgO nanostructures. The as-prepared MgO nanosheets also showed a superior adsorption property of Congo red. Transmission electron microscopy and x-ray diffractometer results indicated that the as-obtained Mg(OH)2 was plate-shaped with a hexagonal crystal structure where MgO possessed a lamellar structure with a cubic phase. The maximum adsorption capacities of Mg(OH)2 and MgO were reached up to 1820 and 2650 mg g−1, respectively. The high adsorption capacity might be related to the particle geometry and large surface area (87.97 m2 g−1 for Mg(OH)2 and 132.31 m2 g−1 for MgO). The adsorbents can be easily regenerated for five times without any significant loss in their adsorption property. The adsorption behaviors of the Mg(OH)2 and MgO adsorbents showed that the adsorption kinetics and isotherms were in good agreement with pseudo-second-order rate equation and Freundlich adsorption model.

Nanocrystalline cellulose (NCC) whisker obtained from acid hydrolysis of cotton was incorporated into the freezing polymerized PNIPA/clay hydrogels to prepare inorganic–organic hybrid nanocomposite hydrogels (named as C-NC gels). The influence of NCC on the properties of C-NC gels was investigated systematically. It was found that all C-NC gels exhibit similar lower critical solution temperature as that of NCC-free gels, being independent of the NCC content. However, with the increase of NCC content in C-NC gels, the swelling ability of gels decreases slightly while the response rate of gels increases gradually, the gels with high content of NCC exhibit an ultrarapid deswelling rate due to the amount of interconnected micropores appeared inside the gels. Moreover, the enhancement effect of increased NCC on the gels is significant, which is also determined by the swelling degree of gels directly. Comparably, for the gels with the same content of NCC, higher strength was found when the gels were kept in lower swelling ratio due to the stronger interaction of NCC through hydrogen bond in the gels.

The mechanical properties of nanoscale free-standing polymer thin films exhibit size dependence due to surface effects. However, it remains a challenge to determine the length scales at which differences are exhibited between film and bulk polymer properties. Here we use molecular dynamics simulations to uncover the dependence of elastic modulus (E) of free-standing films on film thickness and bulk properties. Comparison of the glass transition temperature (T g) and E indicates that T g converges to the bulk value slightly faster as the film thickness increases. The free-surface effects that give rise to a depression in E and T g are observed to be stronger for polymers with weaker intermolecular interactions. The most intriguing aspect of our study is the finding that despite the observed decrease in the modulus of the film up to a thickness of over 100 nm, the local stress distribution reveals that the preserved length scale of perturbation of the free surface is only several nanometers.

Two novel series of cathode materials LiFe1−xMxPO4/C (x ≈ 0.0040; M = Mn, Fe, Co, Ni, Cu, and Zn) composites based on metal phthalocyanines (MPc) and metal tetrasulfophthalocyanines (MPcTs) to modify lithium iron phosphate (LiFePO4) for lithium-ion batteries (LIBs) are in situ prepared by solvothermal and calcination techniques. Structures and morphologies of all the composites are characterized by normal methods. To evaluate the electrochemical performance of the composites, the charge/discharge capabilities, rate performance, cycling stabilities, cyclic voltammetry profiles, and electrochemical impedance spectroscopy plots of the LIBs using them as cathode materials are measured carefully. The results indicate that most of the composites deliver highly improved initial discharge capacity and show remarkable reversibility and cycling stabilities. Especially, composites using MPcTs as additives are more efficient for the improvement of specific capacity, rate capability, reversibility, and cycling stability.

Metallic zinc nanoparticles are generated in two compositional ranges of borosilicate glasses upon 200 and 300 keV electron beam irradiation in a transmission electron microscope. Irradiation effects are studied either with a stationary electron beam as a time series or with spatially varying beams for line-scan patterning. The size of the zinc nanodots formed is inversely related to the distance from the center of the electron beam, and growth from 5 to 50 nm over time via ripening can be observed. Line-scan patterning via both thermal gun and field emission gun electron irradiation has been successfully achieved. Our findings also show the occurrence of self-organized particle ordering, such as formation of chains. Metal nanoparticles have a tendency to migrate toward the glass fragment center, unless high intensity radiation ablates the glass matrix, when Zn particles remain decorating the surface. High-resolution lattice imaging, scanning transmission electron microscopy, and electron energy loss spectroscopy are used to confirm particle identity.

A noncentrosymmetric aluminum borate crystal, Al5BO9, was obtained via high-temperature solution method. Considering the structure diversities of Al5BO9, the single crystal structure was cautiously redetermined before the investigation. The fundamental building blocks of the structure are BO3 triangles, AlO4 tetrahedra, and AlO6 octahedra. Since Al5BO9 only consists of strong covalent B–O and Al–O bonds, it is worth investigating the structure–optical property relationship thoroughly, especially the linear and nonlinear optical properties. To gain further insight into the origin of the nonlinear optical response of Al5BO9, the electronic structure calculations, second harmonic generation (SHG)-weighted electron density, and dipole moment of polyhedra were analyzed in detail. All evidences deduced from calculated results indicate that the SHG contribution from the Al–O polyhedra is more pronounced than that of the BO3 group in Al5BO9, which is anticipated to open a window for the search and design of new inorganic materials.

A quantitative analysis of In concentration in InGaN/GaN multiquantum wells in light-emitting diodes was carried out using high-resolution transmission electron microscopy (HRTEM) and high-angle annual dark-field scanning TEM (HAADF-STEM). The In composition in InGaN was evaluated by the precise measurement of c-lattice parameters in the HRTEM micrographs, which increase with increasing In composition. The reliability of the results was confirmed by high-resolution x-ray diffraction measurements and Rutherford backscattering spectrometry. Quantitative In compositions can, therefore, be determined using HRTEM. We tried to determine the quantitative In compositions in InGaN by analyzing the intensity profiles of the HAADF-STEM images. However, several problems were encountered, such as differences in the thickness of the region observed, carbon contamination, and ion beam damage during specimen preparation. Therefore, relative differences in composition were observed in the HAADF-STEM images.

The macroscopic properties of materials exposed to irradiation are determined by radiation damage effects which occur on the nanoscale. These phenomena are complex dynamic processes in which many competing mechanisms contribute to the evolution of the microstructure and thus to its end-state. To explore and understand the behavior of existing materials and to develop new technologies, it is highly advantageous to be able to observe the microstructural effects of irradiation as they occur. Transmission electron microscopy with in situ ion irradiation is ideally suited to this kind of study. This review focuses on some of the important factors in designing this type of experiment including sample preparation and ion beam selection. Also presented are a brief history of the development of this technique and an overview of the instruments in operation today including the latest additions.