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Nanosized particles, less than 100 nm in diameter, have been successfully synthesized by pulsed wire discharge (PWD). The powders prepared by PWD contained submicron-sized particles, in the range of 0.1 m-1 m in diameter. The existence of submicron-sized particles is attributed to liquid droplets due to lower energy deposition in the wire than vaporization energy of the whole wire. The effect of the energy deposition on particle size distribution was investigated with the copper powders prepared in the atmospheric gas of nitrogen. The energies deposited in the wire were estimated by measuring the currents and voltages for various discharge conditions. Under the conditions of high atmospheric pressure and fast-current rise, the energy deposition was significantly enhanced. The energy deposition mainly affects the quantity of submicron-sized particles that originates from unvaporized liquid droplets rather than the average particle size of nanosized powders.

Nanosize particles of aluminum nitride have been successfully synthesized by a pulsed wire discharge (PWD). Intense pulsed current through an aluminum wire evaporated the wire to produce a high‐density plasma. The plasma was then cooled by an ambient gas mixture of NH3/N2, resulting in nitridation. As a result, nanosize particles of aluminum nitride were formed. The average particle diameter was found to be ∼28 nm with a geometric standard deviation of 1.29. The maximum AlN content of 97% in the powders was achieved by optimizing various parameters: the gas pressure, the ratio of NH3 and N2, the wire diameter, the pulse width, and the input electrical energy. The ratio of the AlN powder production to the electrical energy consumption was evaluated as ∼40 g/(kW·h). Thus, PWD is a very efficient and promising method to synthesize nanosize powders of AlN.

Polycrystalline boron carbide (B4C) thin films have been prepared by a pulsed ion-beam evaporation technique without heating substrates or annealing samples. Here, we clearly demonstrate the possibility of preparing B4C thin films for electronic device applications.

The amorphous phase of hydrogenated carbon nitride, a-CN x :H (0 ≦x ≦1), films may have clusters consisting of a mixture of sp 2- and sp 3-hybridized materials with cluster sizes of 0.2–2 nm. The hydrogen termination limits the size of the carbon and carbon nitride clusters. It also influences the mechanical properties of the sample. In this experiment, the relationship between the hydrogen content and the mechanical properties of carbon and related materials was investigated using elastic recoil detection analysis (ERDA), nanoindentation techniques and Raman spectroscopy. The samples were classified into three categories of hardness: mechanically soft a-CN x :H (hardness: 1–8 GPa), mechanically hard a-CN x :H (8–30 GPa) and hard hydrogenated amorphous carbon (a-C:H) (more than 30 GPa). The hydrogen contents of the sample were 10–50 at.%, 5–40 at.%, and less than 3 at.% for soft a-CN x :H, hard a-CN x :H and hard a-C:H, respectively.

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