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Platelet graphite nanofibers (PGNFs) and turbostratic carbon nanofibers (TSCNFs) were synthesized by the pyrolysis of 3 and 10 vol% chloroform in ethanol, respectively, in the presence of Ni catalyst at 700 °C. Auger electron spectrometry analysis reveals that the participation of chloroform in the synthesis led to Ni–Cl bonding on the surface of the catalysts, resulting in a relatively poor crystalline layer and a coarse surface. Furthermore, the Ni–Cl compound affected the melting point and mobility of Ni, changing the morphology and geometrical shape of Ni particles. A low amount of chlorine in the catalyst led to the formation of smaller catalyst particles with a flat surface, resulting in graphene nanosheets stacked perpendicular to the fiber axis, which became PGNFs. In contrast, a high amount of chlorine in the catalyst led to the aggregation of the catalyst and thus the formation of large catalyst particles with a rough surface, resulting in the random stacking of graphene nanosheets, which became TSCNFs. The participation of chlorine was found to be important in the synthesis of the PGNFs and TSCNFs. [ABSTRACT FROM AUTHOR]

Abstract: The synthesis of tapered carbon nanotubes (TCNTs) by the thermal decomposition of poly(ethylene glycol) at 800°C using Ni as a catalyst is reported. The TCNTs consist of a 50nm diameter graphite tube terminated by a tapered tip, which is about 1μm in length and 20nm in diameter in the tip end. The catalyst particle contained in the tapered tip was found to be a cylindrical with a diameter of about 20nm. Electron microscopy revealed that the catalyst was a single crystal of NiCx and the graphene layers were grown in the [110] direction of the catalyst, forming TCNTs. The unique morphology of the catalyst particle played an important role in the formation of TCNTs. The field emission properties of the TCNTs exhibited a lower turn-on voltage (Eturn-on =3.2V/μm), lower threshold fields voltage (Ethreshold =5.2V/μm) and higher field-enhancement factor β than did multi-walled CNTs. [Copyright &y& Elsevier]

Abstract: The sol–gel method using and was used to prepare -doped nanopowders with particle sizes ranging from 50 to 200nm. This preparation was followed by a calcination process at . The effects which the Eu/Gd composition ratio and calcination temperature had on the phosphor structure and its luminescent properties were then investigated. Phosphor structure was examined by X-ray diffraction, field emission scanning electron microscopy, and transmission electron microscopy. The results confirm that the material consists of particles exhibiting good crystallinity. Photoluminescence and cathodoluminescence measurements of the particles show red emission at the 612nm () wavelength. The optimal molar concentration for obtaining the highest PL intensity for was 7% of (calcinated at for 2h). [Copyright &y& Elsevier]

Abstract: A red-emitting phosphor material, Gd2Ti2O7:Eu3+, V4+, by added vanadium ions is synthesized using the sol–gel method. Phosphor characterization by high-resolution transmission electron microscopy shows that the phosphor possesses a good crystalline structure, while scanning electron microscopy reveals a uniform phosphor particle size in the range of 230–270nm. X-ray photon electron spectrum analysis demonstrates that the V4+ ion promotes an electron dipole transition of Gd2Ti2O7:Eu3+ phosphors, causing a new red-emitting phenomenon, and CIE value shifts to x=0.63, y=0.34 (a purer red region) from x=0.57, y=0.33 (CIE of Gd2Ti2O7:Eu3+). The optimal composition of the novel red-emitting phosphor is about 26% of V4+ ions while the material is calcinated at 800 °C. The results of electroluminescent property of the material by field emission experiment by CNT-contained cathode agreed well with that of photoluminescent analysis. [Copyright &y& Elsevier]

Abstract: Multiwalled carbon nanotubes (MWNTs) were synthesized using a chemical vapor deposition floating feed method in a vertical reactor. Effects of the preparation variables on the average diameter of carbon nanotubes were systematically examined using the fractional factorial design (FFD), path of the steepest ascent, and central composite design (CCD) coupled with the response surface methodology. From the FFD study, the main and interactive effects of reaction temperature, methane flow rate, and chamber pressure were concluded to be the key factors influencing the diameter of MWNTs. Two empirical models, representing the dependence of the diameter of carbon nanotubes at the vicinities around maximum (420nm) and minimum (15nm) on the reaction temperature and methane flow rate, were constructed in two independent CCD studies. These models, shown as contour diagrams, indicated that the diameter of carbon nanotubes generally increased with increasing reaction temperature and methane flow rate. Based on both models, the diameter of MWNTs from 15 to 420nm can be controlled precisely by using a continuous CVD fabrication method. [Copyright &y& Elsevier]