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This paper presents the method for fabricating size-selected nickel nanoparticles (diameter: 5−20 nm) coated with nickel oxide shells (thickness: about 2 nm). The core−shell particles were synthesized by a series of sequential gas-phase processes including pulsed laser ablation, aerosol postannealing, size-classification, compulsory oxidation, and aerosol-jet deposition. The change in the size distribution of the generated particles due to postannealing was measured by a low-pressure differential mobility analyzer (LP-DMA) coupled with a Faraday cup electrometer. The peak size decreased as the postannealing temperature rose, indicating that a sintering and restructuring of the agglomerates was taking place. In the high-resolution TEM (HRTEM) observation, the Ni particles of less than 15 nm in diameter were found to be spherical and single crystal after the annealing at 1073 K. The 20 nm particles were also spherical, but they remained polycrystalline due to insufficient annealing treatment required for ...

A process was investigated to irradiate a continuous-wave CO 2 laser (4.5 kW) on graphite powder with a mean diameter of 5 μm in a flow of Ar or He gas at 30 or 200 Torr. The film produced on a Ni substrate in the Ar flow at 200 Torr showed the Raman bands of C 60 and C 70 , and the C 60 /C 70 ratio was estimated to be 5/1 by MALDI-TOF mass spectrometry. The film formation process is discussed on the basis of an analysis of laser-irradiated powder, which included 0.01 wt% of C 60 , by UV–Vis absorption, and by observations of the plumes and SEM images.

For the size selection of magnetic nano particles produced in laser ablation, a low pressure differential mobility analyzer (LPDMA) was constructed. The LPDMA was characterized using the transmission electron microscopy (TEM) image of laser-ablated CoPt nano particles. Using TEM image, the geometrical standard deviation, σg, was measured to be around 1.13. The dependence of the performance of LPDMA on the gas path temperature and the pressure was measured using an electrode which measures the number of the selected particles. The size-selected magnetic nano-particles were deposited on Si substrates, whose magnetizations were measured by SQUID. It was found that nano-particles with a diameter of 20 nm have different temperature dependences from nano-particles with a diameter of 40 nm and the coercivity of 40 nm dia. nano-particles is smaller than that of 20 nm dia. nano-particles.

This paper presents a method for fabricating size-selected nickel nanoparticles coated with oxide shells (shell thickness of about 2 nm). The size of the generated particles was controlled by a low-pressure differential mobility analyzer. The total mass of the deposited particles was estimated on the basis of their measured electric current. A high-resolution transmission electron microscope was used to observe the morphologies of the particles. We successfully synthesized a series of monodispersed (geometric standard deviation

A semi-continuous process for the synthesis of fullerenes is described. This novel process incorporated a carbon powder feed system in combination with a continuous-wave CO 2 laser irradiation source. The carbon powder contained no fullerenes but did contain graphite crystals and amorphous carbons of selected particle sizes (5, 10, or 20 μm), and selected irregular or spherical particle shapes. The method was successfully used to deposit C 60 and C 70 powders and films continuously. Laser irradiation of the carbon powder produced an observable laser plume. The experimental results and mechanism for the process are discussed.

Nanometer-sized particles of silicon and titanium dioxide were generated by Nd:YAG laser ablation of solid substrates in a low pressure atmosphere. A low-pressure differential mobility analyzer (LP-DMA) was used to control the size of generated particles. The LP-DMA and a transmission electron microscopy (TEM) were used to measure the change in size distribution and morphology of nanoparticles with laser power and pressure. Finally, we succeeded to synthesize the almost spherical nanoparticles of 2-50 nm in diameter.