An apparatus for the synthesis of multi-component substances, comprising entities of at least two elements, molecules, grains, crystals, structural units, or phases of matter, in which the scale of the distribution of the elements, molecules, or phases of matter may range from on the order of nanometers or less, to about one millimeter, depending upon the specific materials and process conditions that are chosen. The apparatus of the present invention comprises a vacuum chamber, a target assembly, an energy source for generating a plasma containing materials ablated from the target assembly, and a reagent gas supply for directing gas into the vacuum chamber toward the plasma.