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The temperature dependence of the Seebeck coefficient, the electrical and thermal conductivities of individual β-silicon carbide nanowires produced by combustion in a calorimetric bomb were studied using a suspended micro-resistance thermometry device that allows four-point probe measurements to be conducted on each nanowire. Additionally, crystal structure and growth direction for each measured nanowire was directly obtained by transmission electron microscopy analysis. The Fermi level, the carrier concentration, and mobility of each nanostructure were determined using a combination of Seebeck coefficient and electrical conductivity measurements, energy band structure and transport theory calculations. The temperature dependence of the thermal and electrical conductivities of the nanowires was explained in terms of contributions from boundary, impurity, and defect scattering.

Self-propagating high-temperature synthesis (SHS) can be regarded as an efficient method to obtain new nanomaterials. Different starting mixtures of magnesium powder with various carbonates (Li 2 CO 3 , Na 2 CO 3 , CaCO 3 , FeCO 3 , (NH 4 ) 2 CO 3 ) were tried and the auto-thermal reactions were carried out under both reactive (air) and neutral atmosphere (argon) with an initial pressure of 1 or 10 atm to yield novel nanomaterials. Both SiC nanofibres and novel branched SiC nanostructures were also obtained from Si/polytetrafluoroethylene (PTFE) mixtures and their synthesis and purification have been optimized. The application of those one-dimensional (1-D) SiC nanostructures as a composite filler is presented.

Beta-SiC (cubic phase) nanowires (SiCNWs) have been grown spontaneously during the autothermal selfpropagating high-temperature synthesis (SHS) from elemental silicon and poly(tetrafluoroethylene) (PTFE) powder mixtures in oxygen-enriched atmosphere. The combustion process was on-line monitored using highspeed photography in order to estimate the reaction processing time which was well below 1 s. From the emission spectroscopy the averaged combustion temperature was evaluated to be close to 2000 K. The products were characterized by wet chemical analysis, X-ray diffraction, scanning and transmission microscopy, and Raman spectroscopy. The raw products were processed by wet chemistry to obtain pure (above 90%) well-crystallized one-dimensional single crystals of SiCNWs.

We present the results of exploratory research on the fast synthesis of few‐layered graphite via a self‐propagating high‐temperature synthesis (SHS). We reported previously that different solid carbonates and gaseous carbon oxides could be directly converted into novel nanocarbons using strong reducers and SHS approach. In the current work, such combustion synthesis (CS) is extended toward the direct and efficient reduction and exfoliation of graphite oxide (GO) or fluorinated graphite (CFx) using different reducers (Si, Mg, NaN3, Li3N) into few‐layered graphene (FLG).

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Abstract

We present the exploratory results on fast combustion synthesis (CS) of carbon-related nanomaterials including the exfoliated graphite. We found earlier that different solid compositions containing strong reducers and carbon-bearing oxidizers could yield carbon vapors that may instantly condense toward 1D and 2D nanocarbons. Here, such a combustion route is extended toward the processing of the mixtures of a strong reducer (Mg, Si, AlH 3 , CaH 2 , or BH 3 NH 3 ) and a strong oxidizer (C 2.78 F 2 , TEFLON 1 PTFE (CF 2 ) n or PVC (C 2 H 3 Cl) n ) in a heterogeneous, efficient, autothermic, high-pressure, and high-temperature reaction. The combustions were carried out both under neutral (Ar) and active atmosphere (CO 2 ) at the starting pressure equal to 10 atm. The solid products (layered graphite and nanocarbides) were chemically purified and characterized using XRD, SEM, TEM, and Raman spectroscopy.Combustion synthesis reaction chambers.