The Mn site in Mn-doped Ga-As nanowires: an EXAFS study

We present an EXAFS study of the Mn atomic environment in Mn-doped GaAs nanowires. Mn doping has been obtained either via the diffusion of the Mn used as seed for the nanowire growth or by providing Mn during the growth of Au-induced wires. As a general finding, we observe that Mn forms chemical bonds with As but is not incorporated in a substitutional site. In Mn-induced GaAs wires, Mn is mostly found bonded to As in a rather disordered environment and with a stretched bond length, reminiscent of that exhibited by MnAs phases. In Au-seeded nanowires, along with stretched Mn-As coordination we have found the presence of Mn in a Mn-Au intermetallic compound.Comment: This is an author-created, un-copyedited version of an article accepted for publication in Semiconductor Science and Technology. IOP Publishing Ltd is not responsible for any errors or omissions in this version of the manuscript or any version derived from it. The definitive publisher-authenticated version is available online at doi:10.1088/0268-1242/27/8/08500

Fabrication by electron beam induced deposition and transmission electron microscopic characterization of sub-10-nm freestanding Pt nanowires

We present a method to reduce the size and improve the crystal quality of freestanding nanowires grown by electron beam induced deposition from a platinum metal organic precursor in a dual beam system. By freestanding horizontal growth and subsequent electron irradiation in a transmission electron microscope, sub-10-nm polycrystalline platinum nanowires have been obtained. A combined transmission electron microscopy-electron energy loss analysis has shown that the amorphous carbon, mixed to nanocrystalline platinum in the as-deposited material, is removed from the wires during irradiation. The same treatment progressively transforms nanocrystals dispersed in the amorphous matrix in a continuous polycrystalline platinum wire

Photocatalytic activity of zinc modified Bi2O3

The surface of alpha-Bi2O3 was modified by either impregnating Zn acetate or coating with a sol-gel containing Zn hydroxide. The surface modified Bi2O3 powders were evaluated by UV-Visible spectroscopy, Scanning Electron Microscopy (SEM), X-ray diffraction (XRD) and surface area analysis (BET). The photocatalytic performances were evaluated for the degradation of phenol, methylene blue and methyl orange. The variations in photocatalytic activity were correlated with morphology change. The presence of ZnO does not significantly prevent the progressive formation of photocatalytically inactive (BiO)(2)CO3, while the dye decolourization capability of nanocomposite is significantly preserved with respect to that of bare Bi2O

Synthesis, characterization and photocatalytic performance of transition metal tungstates

Tungstates of divalent transition metals (MIIWO4, M = CoII, NiII, CuII, ZnII) were synthesized by reaction of transition metal nitrates with sodium tungstate. The precipitates were then calcined at 500 \ub0C. The materials were characterized by means of ICP-AES elemental analysis, UV\u2013Visible spectroscopy, X-ray diffraction (XRD), Scanning Electron Microscopy (SEM) and surface area analysis. The higher activity for the decolourization of Methylene Blue (MB) and Methyl Orange (MO) of ZnWO4 compared to that of the other investigated tungstates was correlated with its strong tendency of excitons self-trapping

Transmission electron microscopy study of blisters in high-temperature annealed He and H co-implanted single-crystal silicon

Transmission electron microscopy has allowed us to draw the three-dimensional structure of blisters formed after high-temperature annealing of He-H co-implanted silicon by combining the unique capability of site-selective cross sectioning of the focused ion beam with conventional plan view images. It has been shown that blisters are formed by crystalline lamellae strongly bended, plastically deformed, and suspended over buried empty cavities. The volume of the protruding blister surface is almost equal to the buried empty volumes, thus suggesting a mechanism for blister formation based on H and He precipitation and migration of silicon atoms toward the surface

Silver-polysaccharide nanocomposite antimicrobial coatings for methacrylic thermosets.

Bisphenol A glycidylmethacrylate (BisGMA)/triethyleneglycol dimethacrylate (TEGDMA) thermosets are receiving increasing attention as biomaterials for dental and orthopedic applications; for both these fields, bacterial adhesion to the surface of the implant represents a major issue for the outcome of the surgical procedure. Moreover, the biological behaviour of these materials is influenced by their ability to establish proper interactions between their surface and the eukaryotic cells of the surrounding tissues, which is important for good implant integration. The aim of this work was to develop an antimicrobial non-cytotoxic coating for methacrylic thermosets by means of a nanocomposite material based on a lactose-modified chitosan and antibacterial silver nanoparticles. The coating was characterized by UV-vis spectrophotometry, optical microscopy, transmission electron microscopy (TEM) and scanning electron microscopy (SEM). In vitro tests were employed for a biological characterization of the material: antimicrobial efficacy tests were carried out with both Gram+ and Gram- strains. Osteoblast-like cell-lines, primary human fibroblasts and adipose-derived stem cells, were used for LDH cytotoxicity assays and Alamar blue cell proliferation assays. Cell morphology and distribution were evaluated by SEM and confocal laser scanning microscopy. In vitro results showed that the nanocomposite coating is effective in killing both bacterial strains and that this material does not exert any significant cytotoxic effect towards tested cells, which are able to firmly attach and proliferate on the surface of the coating. Such biocompatible antimicrobial polymeric films containing silver nanoparticles may have good potential for surface modification of medical devices, especially for prosthetic applications in orthopedics and dentistry