Abstract: Apparatus for forming metallic crystalline nanoparticles includes a dispersion medium, first and second electrodes separated from each other by a predetermined span and being inserted into the dispersion medium. The electrodes are connected to a supply of electrical current at a preselected voltage. A filament is in contact with the two electrodes and is also inserted into the dispersion medium. Upon a first switch connecting the supply of electrical current to the electrodes, a pulsed current passes through the electrodes and the filament at a voltage preselected to disintegrate the filament into fragments, but does not create plasma from the filament.