Morphological change from nano-cube to nano-sphere by addition of Ni to W in RF thermal plasma synthesis

Y-M Kim, H. Na, W. Lee, B-J Lee, N-M Hwang, H. Choi
Korea Institute of Industrial Technology, KR

Keywords: RF thermal plasma, W and Ni-W nanoparticle synthesis, morphological evolution, Monte Carlo simulation

Summary:

Pure W and W-Ni nano-particles were effectively synthesized by feeding thermo-physically favorable oxide feedstock micro-powder into argon-hydrogen thermal plasma. During the process, feedstock particle underwent a vaporization, reduction, and condensation pathway. Significant amount of nano-cube is observed for tungsten nano-particle. However, Ni addition had a crucial influence on nano-particle morphology and W-Ni nano-particle became sphere. Morphological evolution was also investigated by a Canonical Ensemble Monte Carlo simulation. The shape evolution of pure W and Ni-W nanopaticles could be explained as a result of surface segregation of added Ni components and the disturbance of surface energy anisotropy due to the Ni-rich layer formed on the W surface.