Hideki Tanaka

Boron nitride nanotubes, webs, and coexisting amorphous phase formed by the plasma jet method

Boron nitride (BN) nanotubes were prepared by a high-temperature plasma jet method. While the BN nanotubes were found in quantity on the surface of a BN sintered disk, amorphous BN webs were found dominant in the water-cooled collector. These structures were studied on the basis of transmission electron microscopy observations. One of them was composed of 21 layers grown coaxially with a regular spacing of 0.34 nm and their tip ends were terminated with parallel bases of the coaxial cylindrical shapes. The diameter of the innermost tube was 0.6 nm and this dimension is in fairly good agreement with the diameters of the smallest BN fullerenes.

Improvement of electrochemical properties of MCMB powders through reactive ICP modification

Abstract Mesocarbon microbeads (MCMB) powders were treated in Arue5f8H2, Arue5f8N2, Arue5f8H2ue5f8CO2, and Arue5f8N2ue5f8CO2 RF inductively coupled plasmas (ICP). Plasma treatment modified the surface morphology, structure, and chemical composition of the powders. The surface of the Arue5f8N2 plasma-treated particles was covered with a fine condensate, while the surface of Arue5f8N2ue5f8CO2 plasma-treated particles became rough and had no condensate. The discharge capacity and first charge/discharge efficiency of the plasma-treated MCMB powders was higher than those of the original one. Plasma modification of MCMB gave rise to an improvement of the electrochemical properties making it suitable for use as the anode of a lithium-ion rechargeable battery.