A new approach to the high-yield synthesis of nanoparticles by spark discharge

Abstract

A new approach to the high-yield synthesis of nanoparticles in the multi-gap (up to 12) spark discharge generator operating at a repetition rate as high as 2.5 kHz is discussed. This approach allows to increase the production rate by a factor of up to 100 as compared to the conventional approach utilizing single gap generator operating in the self-breakdown mode. In the case of spark erosion of aluminum electrodes in the air atmosphere, the production rate of 300 mg/h has been achieved. From the analysis of transmission electron microscopy images it was found that primary particles of the synthesized material are nearly spherical in shape and their size is 11 nm; these primary particles are united into larger objects (∼80 nm) with fractal structure. The fraction of amorphous phase is 54% and the rest 46% is of cubic γ-Al2O3 phase with the mean crystallite size of 12 nm as determined from X-ray diffraction analysis. The specific surface area of the nanoparticles determined by BET method is equal 180 m2/g.