Synthesis of cobalt boride nanoparticles and h-BN nanocage encapsulation by thermal plasma

Synthesis of cobalt boride nanoparticles and h-BN nanocage encapsulation were conducted using a triple direct current (DC) thermal plasma jet system. Mixed cobalt and boron powder were used as the starting material. The thermal plasma jet was generated using mixed Ar-N-2 and Ar-H-2 gases. The nanostructure of the synthesized nanoparticles varied according to the gas composition. In the Ar-N-2 plasma, the dissociated nitrogen anticipated a chemical reaction with the boron precursor and synthesized h-BN nanocages that encapsulated cobalt boride nanoparticles, additionally, c-BN nanoparticles were synthesized. In the Ar-H-2 plasma, only < 20 nm spherical cobalt boride nanoparticles were synthesized and their size distribution was controlled by the growth time or quenching rate, which was controlled by changing the flow rate of plasma forming gasses. These synthetic processes were comparatively investigated thermodynamically.