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Subject: Materials chemistry × WGL Institute: IFWD ×

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    Mechanochemical route to the synthesis of nanostructured Aluminium nitride
    (London : Nature Publishing Group, 2016) Rounaghi, S.A.; Eshghi, H.; Scudino, S.; Vyalikh, A.; Vanpoucke, D.E.P.; Gruner, W.; Oswald, S.; Rashid, A.R. Kiani; Khoshkhoo, M. Samadi; Scheler, U.; Eckert, J.
    Hexagonal Aluminium nitride (h-AlN) is an important wide-bandgap semiconductor material which is conventionally fabricated by high temperature carbothermal reduction of alumina under toxic ammonia atmosphere. Here we report a simple, low cost and potentially scalable mechanochemical procedure for the green synthesis of nanostructured h-AlN from a powder mixture of Aluminium and melamine precursors. A combination of experimental and theoretical techniques has been employed to provide comprehensive mechanistic insights on the reactivity of melamine, solid state metal-organic interactions and the structural transformation of Al to h-AlN under non-equilibrium ball milling conditions. The results reveal that melamine is adsorbed through the amine groups on the Aluminium surface due to the long-range van der Waals forces. The high energy provided by milling leads to the deammoniation of melamine at the initial stages followed by the polymerization and formation of a carbon nitride network, by the decomposition of the amine groups and, finally, by the subsequent diffusion of nitrogen into the Aluminium structure to form h-AlN.
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    Dispersibility of vapor phase oxygen and nitrogen functionalized multi-walled carbon nanotubes in various organic solvents
    (London : Nature Publishing Group, 2016) Khazaee, Maryam; Xia, Wei; Lackner, Gerhard; Mendes, Rafael G.; Rümmeli, Mark; Muhler, Martin; Lupascu, Doru C.
    The synthesis and characterization of gas phase oxygen- and nitrogen-functionalized multi-walled carbon nanotubes (OMWCNTs and NMWCNTs) and the dispersibility of these tubes in organic solvents were investigated. Recently, carbon nanotubes have shown supreme capacity to effectively enhance the efficiency of organic solar cells (OSCs). A critical challenge is to individualize tubes from their bundles in order to provide homogenous nano-domains in the active layer of OSCs. OMWCNTs and NMWCNTs were synthesized via HNO3 vapor and NH3 treatments, respectively. Surface functional groups and the structure of the tubes were analyzed by temperature-programmed desorption, Fourier transform infrared spectroscopy, transmission electron microscopy, and Raman spectroscopy which confirmed the formation of functional groups on the tube surface and the enhancement of surface defects. Elemental analysis demonstrated that the oxygen and nitrogen content increased with increasing treatment time of the multi-walled carbon nanotube (MWCNT) in HNO3 vapor. According to ultra-violet visible spectroscopy, modification of the MWCNT increased the extinction coefficients of the tubes owing to enhanced compatibility of the functionalized tubes with organic matrices.