Silicon oxide nanoparticles comprising an amorphous network of SiO.sub.x having silicon nanoparticles embedded in the amorphous SiO.sub.x network where x is less than or equal to two, made by a method comprising generating a direct current electric arc between an anode comprised of silicon and a metal cathode in a chamber containing oxygen, subjecting the silicon of the anode to the plasma generated by the electric arc to vaporize silicon within the chamber, allowing silicon oxide nanoparticles to form in the chamber, quenching the silicon oxide nanoparticles on a surface within the chamber positioned adjacent the silicon anode, and collecting the silicon oxide nanoparticles from the surface.