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In hunting for safe and cost-effective materials for post-Li-ion energy storage, the design and synthesis of high-performance solid electrolytes (SEs) for all-solid-state batteries are bottlenecks. Many issues associated with chemical stability during processing and storage and use of the SEs in ambient conditions need to be addressed. Now, the effect of water as well as oxyhdryl group (. OH) on NaBi3 O4 Cl2 are investigated by evaluating ionic conductivity. The presence of water and . OH results in an increase in ionic conductivity of NaBi3 O4 Cl2 owing to diffusion of H2 O into NaBi3 O4 Cl2 , partially forming binding . OH through oxygen vacancy repairing. Ab initio calculations reveal that the electrons significantly accumulate around . OH and induce a more negative charge center, which can promote Na+ hopping. This finding is fundamental for understanding the essential role of H2 O in halide-based SEs and provides possible roles in designing water-insensitive SEs through control of defects.

Poly(3-hexylthiophene) (P3HT) films with various molecular weights (MWs) were successfully prepared, and both their molecular structures and thermoelectric (TE) properties were investigated. It was found that the molecular weight of P3HT had an important effect on the carrier-transport properties by affecting the molecular structure and, as a result, also had an effect on the TE performance. The electrical conductivity of the P3HT films first increased upon increasing the molecular weight and then decreased at high molecular weights, whereas the Seebeck coefficient remained at the same level. As a result, the P3HT-M50k (MW≈50 000 g mol-1 ) film reached an electrical conductivity of (103.8±1.2) S cm, which is more than 20 times higher than the electrical conductivity of P3HT-M10k (MW≈10 000 g mol-1 ) and almost 30 % higher than the electrical conductivity of P3HT-M100k (MW≈100 000 g mol-1 ). Consequently, the maximum TE power factor of P3HT-M50k at room temperature was as high as (22.6±0.6) μW mK-2 , which is much higher than that of either P3HT-M10k or P3HT-M100k . Microstructure analysis combined with C-AFM suggested that carrier transport between most of the ordered and amorphous regions was unconnected in films with low molecular weights, and this resulted in a high migration barrier and poor carrier mobility. Upon increasing the molecular weight, the long molecular chain provided enough connectivity for the charge to move through the ordered regions, which decreased the carrier barrier and increased carrier mobility. Therefore, both the conductivity and Seebeck coefficient were significantly improved. However, a too-high molecular weight could cause more folding of the polymer chain, which would deteriorate the electrical-transport properties. The experimental results not only reveal the intrinsic effect of molecular weight on the electric transporting properties of conducting polymers but also suggest that molecular-weight engineering is an effective way to design and screen high-performance polymer TE materials.

Unlike traditional water splitting in an aqueous medium, direct decomposition of atmospheric water is a promising way to simultaneously dehumidify the living space and generate power. Here, a tailored superhygroscopic hydrogel, a catalyst, and a solar cell are integrated into a humidity digester that can break down ambient moisture into hydrogen and oxygen, creating an efficient electrochemical cell. The function of the hydrogel is to harvest moisture from ambient humidity and transfer the collected water to the catalyst. Barium titanate and vertical 2D MoS2 nanosheets are integrated as the catalyst: the negatively polarized cathode can enhance the electron transport and attract H+ to the MoS2 surface for water reduction, while water oxidation takes place at the positively polarized anode. By employing this mechanism, it is possible to maintain the relative humidity in a medium-sized room at

This paper presents the mechanical polishing effects on the surface domains and crystal structures of relaxor-based Pb(Zn 1/3 Nb 2/3 )O 3 ―PbTiO 3 (PZN-PT) single crystals. In normal sample preparation processes, a "surface deformed layer" composed of distorted crystal structures is produced due to intense compression caused by several polishing steps using a series of lapping films down to 1 μm in particle size. This "surface deformed layer" may contribute to dissimilar properties compared with those of the interior, and also result in pop-in events in the load-displacement curve (P―h curve) during nanoindentation. An anomaly in the X-ray diffraction (XRD) profiles is also found, demonstrating a broad minor peak besides the major peak in the intensity. In addition, Piezoresponse Force Microscopy reveals that the domain structures on the crystal surface appear to be distorted and aligned along the polishing direction. Therefore, a controlled fine polishing procedure using Al 2 O 3 slurry of 0.3 μm particle size is adopted to remove this "surface deformed layer." After polishing to mirror finish, the macroscopic orientations of the domain walls agree well with the permissible domain wall directions. The topography is also altered analogous with the polarization direction. More specifically, the upward domains constitute a depression of ∼10 nm compared with the downward domains, suggesting a different hardness for the head and tail domain sections. Furthermore, the minor peak in the XRD and the pop-in event in the nanoindentation P―h curve are successfully eliminated after this fine polishing procedure. The removal of the surface layer may also lower the coercive field of the crystals, thus enabling ferroelectric control with a smaller voltage.

It is well known that the lower bound to exact solutions in linear fracture problems can be easily obtained by the displacement compatible finite element method (FEM) together with the singular crack tip elements. It is, however, much more difficult to obtain the upper bound solutions for these problems. This paper aims to formulate a novel singular node-based smoothed finite element method (NS-FEM) to obtain the upper bound solutions for fracture problems. In the present singular NS-FEM, the calculation of the system stiffness matrix is performed using the strain smoothing technique over the smoothing domains (SDs) associated with nodes, which leads to the line integrations using only the shape function values along the boundaries of the SDs. A five-node singular crack tip element is used within the framework of NS-FEM to construct singular shape functions via direct point interpolation with proper order of fractional basis. The mix-mode stress intensity factors are evaluated using the domain forms of the interaction integrals. The upper bound solutions of the present singular NS-FEM are demonstrated via benchmark examples for a wide range of material combinations and boundary conditions. Copyright © 2010 John Wiley & Sons, Ltd.

A generalized gradient smoothing technique and a smoothed bilinear form of Galerkin weak form have been recently proposed by Liu et al. to create a wide class of efficient smoothed point interpolation methods (PIMs) using the background mesh of triangular cells. In these methods, displacement fields are constructed by polynomial or radial basis shape functions and strains are smoothed over the smoothed domain associated with the nodes or the edges of the triangular cells. This paper summarizes and assesses bound property, convergence rate and computational efficiency for these methods. It is found that: (1) the incorporation of the PIMs with the node-based strain smoothing operation allows us to obtain an upper bound to the exact solution in the strain energy; (2) the incorporation of the PIMs with the edge-based strain smoothing operation using triangular background mesh can produce a solution of ‘ultra-accuracy’ and ‘super-convergence’; (3) the edge-based strain smoothing operation together with the linear interpolation can provide better computational efficiency compared with other smoothed PIMs and the finite element method when the same triangular mesh is used. These conclusions have been examined and confirmed by intensive examples. Copyright © 2009 John Wiley & Sons, Ltd.

This paper describes an experimental measurement of the residual stress field around Berkovich and Knoop indentations on the surface of soda-lime glass. The isostress contours of both the residual tensile and compressive stress are presented. The results are compared with similar measurements around Vickers indentations on the same glass. The residual stress field around all three different shapes of indentations is clearly nonequal biaxial, with characteristic differences in the form of the stress contours that relate to each specific shape. The results for Berkovich indentation are compared with finite element (FEM) numerical calculations. Some general conclusions related to the sharp indentations are deduced from this study.

Large-area, 2D, anisotropic, direct growth of nanostructures is considered an effective and straightforward way to readily fulfill transparent, flexible technology requirements. In addition, formation of thin hybrid structures by combining with another 2D material brings about dimensional advantages, such as intimate heterostructure functionalities, large specific area, and optical transparency. Here, we demonstrate 2D planar growth of thin Ni(OH)2 nanosheets on arbitrary rigid and soft supports, by exploiting the growth strategies of oriented attachment induced by interfacial chemistry and the intrinsic driving force of layered structure constitution. Moreover, large-scale 2D heterohybrids have successfully been prepared by direct conformal growth of Ni(OH)2 nanosheets overlying MoO3 nanobelts. Unlike the exfoliation and transfer of 2D materials technique, this approach minimizes multiple process contamination and physical-handling structural defects. Accordingly, proof-of-concept flexible electrochromism is demonstrated in view of its prerequisite to the access of a large homogeneous material coating. The as-synthesized 2D layered structure affirms its optical and electrochemical superiority through the display of wide optical modulation, high coloration efficiency, good cyclic stability, and flexibility.

The chemical environment is one aspect of the oral environment, which could have an appreciable influence on the in vivo degradation of composite restoratives. The effects of chemical media on surface hardness of four composite restoratives (Silux [SX], Z100 [ZO], Ariston [AR] and Surefil [SF]) were investigated. The relationship between hardness and the thickness of the degradation layer was also studied. Thirty six specimens (3 x 4 x 2 mm) were made for each material. Following polymerization, the specimens were stored in artificial saliva at 37 degrees C for 24 h. The specimens were then randomly divided into six groups of six, subjected to microhardness testing (load = 500 gf, dwell time = 15 s) and stored in the following chemicals for 1 week at 37 degrees C: artificial saliva (S), distilled water (W), 0.02 N citric acid (C), 0.02 N lactic acid (L), heptane (H) and 75-25% ethanol-water solution (E). After conditioning, the specimens were again subjected to hardness testing and sectioned. Change in hardness (DH) was computed and the thickness of the degradation layer (DL) was measured using a computerized image analysis system at 600x magnification. Results of statistical analysis (ANOVA/Scheffe's [P0.05]) of DH based on materials were as follows: SX - Eall other mediums; ZO - WC; and AR - S, W, EH (indicates significantly greater hardness change). No significant difference in DH was observed between the different chemicals for SF. The effects of chemical media on DH were found to be material dependent. A significant but weak positive correlation (Pearson's correlation [P0.05]) exists between change in hardness and thickness of the degradation layer.

A new technique is developed to measure the residual stress field around Vickers indentations in glass and ceramics. This technique uses a small indentation as a microprobe to measure the residual stress at a specific position near a large indentation. The approach is based on the observation that the crack lengths of the small indentation are changed under the influence of the residual stress field created by the large indentation. A simple fracture mechanics model is derived to calculate the residual stress from the measurement of the changes of the crack lengths of the small indentation. The results show that the residual stress around Vickers indentations is a nonequal biaxial field; both tensile and compressive stresses exist around a sharp indentation and decrease as the distance from the center of indentation increases. This technique can be easily extended to many other cases of residual stress in ceramics and composites.

Results of dynamic fatigue experiments in water at room temperature on an indented Al2O3/25 wt% SiC whisker composite material have shown that this composite has a high resistance to slow crack growth. Aging tests in water revealed that the residual stress due to the indentation does not play an important role, and interrupted fatigue tests showed that the crack starts to grow at very low stress intensities, but the velocity is very low. Detailed fractography indicated that the slow crack growth path is intergranular in the whisker composite. The slow crack growth behavior in the whisker composite is discussed in association with the indentation residual stress, the change of the crack shape during the bending test. These results are compared with a bio-grade Al2O3 with lower resistance to slow crack growth, and important differences are pointed out.