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Abstract: Core-shelled structures such as zinc oxide (ZnO) on carbon nanotubes (CNTs) give rise to interesting material properties. In this work, a triple-layered core–shell–shell structure is presented where the effects of fluorine (F) incorporation on the outmost shell of the ZnO-CNT structure are studied. The samples prepared ranged from a short 2min to a 30min immersion in carbon tetraflouride (CF4) plasma. In addition, its effects on the electron emission properties also studied and it is shown that the plasma immersions create thinner field emitters with sharp tiny wrinkles giving rise to more electron emission sites and higher enhancement factor. In addition, X-ray photoelectron spectroscopy measurements showed that F ions replace O in ZnO coatings during immersion process, thus increasing the electrical conductivity and shifts the Fermi level of ZnO upwards. Both physical and electronic effects further contribute to a lower threshold field. [Copyright &y& Elsevier]

Abstract: ZrAlN/ZrB2 multilayered superlattice coatings with modulation periods ranging from 20nm to 60nm were grown in magnetron sputtering chamber. X-ray diffraction (XRD), scanning electron microscopy (SEM) and nanoindention were employed to investigate the influence of modulation period on microstructure and mechanical properties of the multilayers. The sharp interfaces and nanoscale multilayered modulation were confirmed by SEM and XRD. The coating with modulation period of 40nm and modulation ratio of 1:3 showed a marked polycrystalline structure with the strong mixture of ZrAlN (111), ZrB2 (001) and ZrB2 (101) textures. Meanwhile, it also possessed the highest hardness (36.4GPa), elastic modulus (477GPa), critical fracture load (76.48mN), and lower residual stress, compared to those with other modulation periods and monolithic coatings. [Copyright &y& Elsevier]

Abstract: The laser surface cladding of an AZ91D magnesium alloy with Al and Al2O3 powders was investigated using a pulsed Nd:YAG laser. The optimum ratio of Al to Al2O3 and the suitable range of laser processing parameters were identified. The resulting microstructure in the modified surface layer was examined and the wear resistance property was evaluated. The results show that the wear resistance of the laser treated samples was much superior to that of the untreated samples. [Copyright &y& Elsevier]

Abstract: The effects of laser surface melting (LSM) on microstructure of magnesium alloy containing Al8.57%, Zn 0.68%, Mn0.15%, Ce0.52% were investigated. In the present work, a pulsed Nd:YAG laser was used to melt and rapidly solidify the surface of the magnesium alloy with the objective of changing microstructure and improving the corrosion resistance. The results indicate that laser-melted layer contains the finer dendrites and behaviors good resistance corrosion compared with the untreated layer. Furthermore, the absorption coefficient of the magnesium alloy has been estimated according to the numeral simulation of the thermal conditions. The formation process of fine microstructure in melted layers was investigated based on the experimental observation and the theoretical analysis. Some simulation results such as the re-solidification velocities are obtained. The phase constitutions of the melted layers determined by X-ray diffraction were β-Mg17Al12 and α-Mg as well as some phases unidentified. [Copyright &y& Elsevier]

Interfaces in complex oxide heterostructures provide a new platform for creating novel functionalities. Up to now, the investigation on manipulating vertical interface in vertically aligned nanocomposite films is very limited. By manipulating vertical interface, a significantly reduction of leakage current and Ohmic conduction behavior were achieved in BaTiO 3 :Sm 2 O 3 films, which may enable the design of advanced nanostructures with emergent functionalities. • Ohmic conduction behavior was realized up to 1000 kV/cm. • Leakage current of BaTiO 3 is reduced by the formation of sharp vertical interface. • Enhanced ferroelectric polarization in BaTiO 3. Interface in complex oxide heterostructures provides a new platform for uncovering emergent physical phenomena and engineering novel functionalities. Compared to the control of lateral interface in bilayer or multilayer complex oxide films, the investigation on manipulating the vertical interface in vertically aligned nanocomposite films is rarely studied so far. Here, the vertical interface effect on the leakage behavior of vertically aligned nanocomposite BaTiO 3 :Sm 2 O 3 films grown on (1 1 1) Nb-SrTiO 3 (Nb-STO) substrates is reported. We found that the vertical interface without visible misfit dislocations is formed between BaTiO 3 and Sm 2 O 3. Consequently, the leakage mechanism is determined to be Ohmic conduction up to an electric field of 1000 kV/cm. Also, the leakage current is reduced to be around 3 × 10−7 A/cm2, which is almost two and three orders of magnitude lower than that of BaTiO 3 :Sm 2 O 3 /(0 0 1) Nb-STO and pure BaTiO 3 /(1 1 1) Nb-STO films, respectively. This work demonstrates the ability to realize Ohmic conductive mechanism at high electric field and further provides a new pathway to reduce leakage current and improve ferroelectric polarization of ferroelectric oxide films by manipulating the vertical interface, which opens the door to the design of advanced nanostructures with the emergent functionalities. [ABSTRACT FROM AUTHOR]