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, B2O3, 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.