Direct synthesis of nano-sized glass powders with spherical shape by RF (radio frequency) thermal plasma

A new route for obtaining very small, spheroid glass powders is demonstrated using an RF (radio frequency) thermal plasma system. During the process, four kinds of chemicals, here SiO₂, B₂O ₃, BaCO₃, and K₂CO₃, were mixed at pre-set weight ratios, spray-dried, calcined at 250 °C for 3 h, and crushed into fragments. Then, they were successfully reformed into nano-sized amorphous powders (< 200 nm) with spherical shape by injecting them along the centerline of an RF thermal plasma reactor at ~ 24 kW. The as-synthesized powders show negligible (< 1%) composition changes when compared with the injected precursors of raw material compounds.