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Subsurface damage (SSD) introduced from abrasive machining significantly degrades the reliability and lifetime of glass ceramics. In this work, nanoindentation tests were performed on the cross section near the lapped surface to determine the nanomechanical properties of subsurface layer of a lapped BK7. Remarkable differences were found between SSD layer and its bulk counterpart in terms of load-displacement characteristics and nanomechanical response. The nanomechanical parameters (hardness and elastic modulus) of subsurface layer follow an exponential descending trend with the shortening of distance from lapped surface, which is consistent with the increase of crack density. The ratio of hardness to elastic modulus decreases exponentially with increasing subsurface depth until it reaches bulk material, which suggests that SSD layer has lower plasticity. Furthermore, the crack distribution becomes a critical parameter for characterizing the hardness gradient in SSD layer.

Functional gradient systems have important applications in many areas. Although a 2D dielectric structure that serves as the gradient index medium for controlling electromagnetic waves is well established, it may not be suitable for application in 3D case. In this paper, we present a method to realize functional gradient systems with 3D integrated micro/macrostructure. The homogenization of the structure is studied in detail by conducting band diagram analysis. The analysis shows that the effective medium approximation is valid even when periodicity is comparable to wavelength. The condition to ensure the polarization-invariant, isotropic, and frequency-independent property is investigated. The scheme for the design and fabrication of 3D systems requiring spatial material property distribution is presented. By using the vat photopolymerization process, a large overall size of macrostructure at the system level and precise fine features of microstructure at the unit cell level are realized, thus demonstrating considerable scalability of the system for wave manipulation.

Nanolaminates consisting of individual amorphous Cu-Zr-Al layers and nanocrystalline Cu layers on Si substrates were prepared by alternatively magnetron sputtering and hardness measurements were conducted upon nanoindentation with a standard Berkovich indenter. Indentation hardness showed a strong size effect in single Cu-Zr-Al film, its decline trend was slower in the nanolaminates with thinner amorphous layers. While experimental hardness was obviously below the expected rule-of-mixture value for all the nanolaminates. Finite element modelling (FEM) analysis was performed in each sample to explore stress distribution beneath indenter. A higher proportion of Cu layers has been involved into plastic region than the nominal value. Besides, interfacial barrier strength was estimated for each sample. The experimental results could be well described by the modified rule of mixture integrated with true ratio of Cu to Cu-Zr-Al in plastic region and the interface strengthen effect.

Upon nanoindentation, the rate-jump method and creep test were conducted on Cu Zr Al metallic glassy films with thickness of 500 nm, 900 nm and 1500 nm. Based on the strain rate sensitivities (SRS) estimated by the two methods, the shear transformation zone (STZ) volumes of all the samples could be determined, respectively. Both experiment results show STZ volume increases with the film thickness increasing. In addition, substrate effect was carefully excluded on the present measurements. The variation trend of STZ volume was discussed in terms of free volume content, which was thought to be concerned with the sputtering process.

Well-dispersed mesoporous SiO2 colloidal spheres (MSCSs) were prepared with hexadecyltrimethyl ammonium phosphomolybdate (M-6) as template. The MSCSs were characterized by scanning electron microscopy, transmission electron microscopy, X-ray powder diffraction, and Fourier transform infrared spectroscopy, etc. The diameter and the uniform pore size of the MSCSs are similar to 200 nm and similar to 2.85 nm, respectively. By rational tuning the synthesis conditions such as the concentration of M-6, the volume ratio of water to ethanol, the amount of tetraethoxysilane, etc., the morphology, size and dispersity of the SiO2 products can be easily controlled. The formation mechanism of the as-prepared MSCSs was also proposed. Treated with sulfuric acid, the resulted MSCSs exhibited excellent catalytic activity in the synthesis of biodiesel via the esterification of long-chain free fatty acids. Crown Copyright (C) 2015 Published by Elsevier B.V. All rights reserved.

Well-dispersed Ag/AgBr colloidal spheres and the corresponding reduced graphene oxide (RGO) hybridized nanocomposite, Ag/AgBr/RGO, were synthesized by a simple one-step polyolthermal method. By rational tuning the synthesis conditions such as the content of polyvinylpyrrolidone (PVP), hexadecyltrimethyl ammonium bromide (CTAB), and the initial reaction temperature, the morphology, size and dispersity of the Ag/AgBr products can be easily controlled. The formation mechanism of as-prepared Ag/AgBr colloidal spheres was further proposed. The hybridization of Ag/AgBr spheres with RGO enhanced the composite catalytic performance, and the Ag/AgBr/RGO hybrid exhibited excellent catalytic activity and stability towards decomposition of Rhodamine B (RhB) under sunlight irradiation.