Resonant Raman scattering is highly desired for material study. It is experimentally not easy to reach the resonant scattering interaction between an incident photon and a material due to the limited available laser wavelengths. In this study, by employing silver plasmonic nanoparticles deposited on glass substrate and by in situ adjusting the cadmium sulfide (CdS) band gap through heat treatment, resonant Raman scattering condition (laser wavelength of 514.5 nm) was fully achieved in nanocrystalline CdS thin films. The dramatically enhanced Raman scattering allowed us to in situ monitor the phase transition that occurred during the heat treatment and to quantitatively characterize the fraction of the zincblende (cubic) CdS in the main base of wurtzite (hexagonal) CdS. Raman multi‐phonon and the corresponding high‐order scattering modes were observed due to the much enhanced surface nanoplasmonic electric field. Copyright © 2016 John Wiley & Sons, Ltd.

A series of alluaudite Na2 Fe3-x Mnx (PO4 )3 microcompounds, which self-assembled from primary nanorods, were prepared successfully through a solvothermal method. As a promising candidate cathode for sodium-ion batteries, it is necessary to obtain a deeper understanding of the relationship between the structure and physicochemical properties of these materials. The local electronic and geometric environments were systematically investigated, for the first time, by using a combination of soft/hard X-ray absorption, IR, and Mössbauer spectroscopy. The results show that the electrochemical performance is not only associated with morphology, but also with the electronic and crystalline structure. With the introduction of manganese into the lattice, the long-range order maintains the isostructural framework and the lattice parameters expand as expected. However, for short-range order, PO4 tetrahedra and MO6 octahedra (M=Fe and Mn) become more severely distorted as a function of Mn concentration. Meanwhile, larger MnO6 octahedra will compress the space of FeO6 octahedra, which will result in stronger core/electron-electron interactions for Fe, as characterized by hard/soft X-ray absorption spectra. These slight changes in the electronic and local structures lead to different electrochemical performances with changes to the manganese content. Moreover, other physicochemical properties, such as magnetic behavior, are also confirmed to be correlated with these different electron interactions and local geometric environments.

Broad and low‐intensity Raman peaks are usually expected from nanocrystalline thin semiconductor films. The inherently weak Raman scattering phenomenon can be further deteriorated by unwanted background signals preventing the successful Raman analysis of an analyte. In this study, the resonant and surface‐enhanced Raman scattering techniques were combined to detect CuO and Cu2O phases in the partially oxidized nanocrystalline copper film that were otherwise undetectable. Heat treatment resulted in increased oxidation and phase transition from multiphase to single CuO phase that was in situ observed by temperature‐dependent Raman measurements. Detailed understanding of the film properties and substrate interaction was made by using several characterization techniques.

The concentration and small size of nanodiamonds (NDs) plays a crucial role in the mechanical performance of epoxy-based nanocomposites by modifying the interface strength. Herein, we systemically analyzed the relation between the high concentration and small size of ND and the fracture properties of its epoxy-based nanocomposites. It was observed that there is a two-fold increase in fracture toughness and a three-fold increase in fracture energy. Rationally, functionalized-NDs (F-NDs) showed a much better performance for the nanocomposite than pristine NDs (P-NDs) because of additional functional groups on its surface. The F-ND/epoxy nanocomposites exhibited rougher surface in contrast with the P-ND/epoxy, indicating the presence of a strong interface. We found that the interfaces in F-ND/epoxy nanocomposites at high concentrations of NDs overlap by making a web, which can efficiently hinder further crack propagation. In addition, the de-bonding in P-ND/epoxy nanocomposites occurred at the interface with the appearance of plastic voids or semi-naked particles, whereas the de-bonding for F-ND/epoxy nanocomposites happened within the epoxy molecular network instead of the interface. Because of the strong interface in F-ND/epoxy nanocomposites, at high concentrations the de-bonding within the epoxy molecular network may lead to subsequent cracks, parallel to the parent crack, via crack splitting which results in a fiber-like structure on the fracture surface. The plastic void growth, crack deflection and subsequent crack growth were correlated to higher values of fracture toughness and fracture energy in F-ND/epoxy nanocomposites.

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AlN epilayers were grown on a 2-inch [0001] conventional flat sapphire substrate (CSS) and a nano-patterned sapphire substrate (NPSS) by metalorganic chemical vapor deposition. In this work, the effect of the substrate template and temperature on stress and optical properties of AlN films has been studied by using Raman spectroscopy, X-ray diffraction (XRD), transmission electron microscopy (TEM), UV-visible spectrophotometer and spectroscopic ellipsometry (SE). The AlN on NPSS exhibits lower compressive stress and strain values. The biaxial stress decreases from 1.59 to 0.60 GPa for AlN on CSS and from 0.90 to 0.38 GPa for AlN on NPSS sample in the temperature range 80–300 K, which shows compressive stress. According to the TEM data, the stress varies from tensile on the interface to compressive on the surface. It can be deduced that the nano-holes provide more channels for stress relaxation. Nano-patterning leads to a lower degree of disorder and stress/strain relaxes by the formation of the nano-hole structure between the interface of AlN epilayers and the substrate. The low crystal disorder and defects in the AlN on NPSS is confirmed by the small Urbach energy values. The variation in bandgap (Eg) and optical constants (n, k) with temperature are discussed in detail. Nano-patterning leads to poor light transmission due to light scattering, coupling, and trapping in nano-holes.

Since the successful separation of graphene from its bulk counterpart, two-dimensional (2D) layered materials have become the focus of research for their exceptional properties. The layered hexagonal boron nitride (h-BN), for instance, offers good lubricity, electrical insulation, corrosion resistance, and chemical stability. In recent years, the wide-band-gap layered h-BN has been recognized for its broad application prospects in neutron detection and quantum information processing. In addition, it has become very important in the field of 2D crystals and van der Waals heterostructures due to its versatility as a substrate, encapsulation layer, and a tunneling barrier layer for various device applications. However, due to the poor adhesion between h-BN and substrate and its high preparation temperature, it is very difficult to prepare large-area and denseh-BN films. Therefore, the controllable synthesis of h-BN films has been the focus of research in recent years. In this paper, the preparation methods and applications of h-BN films on III–V compounds are systematically summarized, and the prospects are discussed.

Surface plasmon (SP)-enhanced quantum-well (QW) LEDs have proved their potential in replacing conventional lighting devices for their high-performance capabilities in ultraviolet (UV), blue and green spectral ranges. The SP-enhanced QW-LEDs have applications in light emission enhancement, light polarization, color conversion, and speed modulation. The electric field of the plasmonic mode of a metal couples with the exciton energy of QWs in resonance results in efficiency enhancement to several folds. The strength of the SP–QW coupling is mainly influenced by the type of metal used for SP enhancement, the metal nanostructure geometry, and the penetration depth of the SP fringing field in the p-GaN. The use of an appropriate dielectric interlayer between the metal and the p-GaN allows further control over SP resonance with QW emission wavelength. The penetration depth defines the p-GaN thickness and the QW period number for effective SP–QW coupling. The optimization of these parameters is key to achieve high efficiencies in SP-enhanced QW-LEDs for various applications. This review explains the SP enhancement mechanism and the key challenges facing the SP enhancement of QW-LEDs. The main factors that affect the SP–QW coupling have been explained in detail based on recent reports devoted to this field.