Abstract: We have found that a pulsed DC supply is surprisingly beneficial in the use of sputter deposition for creating nanoparticles. The deposition rate is increased, and the particle size can be tuned so that it clusters around a specific value. A method of sputter deposition is therefore disclosed, comprising the steps of providing a magnetron, a sputter target, and an AC power supply or a pulsed DC power supply for the magnetron, sputtering particles from the sputter target into a chamber containing an inert gas, allowing the particles to coalesce into nanoparticles, and controlling the frequency of said AC power supply or said pulsed DC power supply to take one of a plurality of frequency values, each frequency value corresponding to a respective size distribution of said nanoparticles. The power supply frequency is preferably between 75 kHz and 150 kHz as this appears to yield optimal results. A corresponding apparatus for generating nanoparticles is also disclosed.

Abstract: Composite nanoparticles can be produced by a processing apparatus comprising a source of charged, moving nanoparticles or a first material and a first size, apparatus for imposing a like potential in a region lying in the path of the nanoparticles, and a physical vapour deposition source of a second material directed toward the region, thereby to produce nanoparticles of a second and greater size being a composite of the first and second materials. The apparatus for imposing a like potential can comprise one or more conductive rings surrounding the path of the nanoparticles, each at a successively lower potential. The physical vapour deposition source can be one or more of a sputter target, or an evaporative source, or another PVD source. There can be a plurality of physical vapour deposition sources, thereby allowing a larger region in which the shell is deposited. All of the physical vapour deposition sources can deposit the same material, for a uniform shell.