Single-Crystal MgO Hollow Nanospheres Formed in RF Impulse Discharge Plasmas

Abstract

Spherical MgO nanoparticles with a hollow inside, that is, MgO hollow nanospheres, were created in Ar/O2plasma produced by radio frequency (RF) impulse discharge using a Mg rod electrode. The hollow nanospheres were found on the SiO2plates placed near the powered Mg electrode. The electron refraction pattern showed that each nanosphere was made of a single crystal of MgO. Since the shape was spherical, these nanoparticles seemed to be created during the levitation in the plasma without touching any walls. The formation mechanism with a quasiliquid cooling model was also discussed.