Well dispersed silicon nanospheres synthesized by RF thermal plasma treatment and their high thermal conductivity and dielectric constant in polymer nanocomposites

In this paper, well dispersed Si nanospheres (Si-NSs) were successfully synthesized via a simple and efficient method by using radio-frequency (RF) thermal plasma treatment. Structures and morphologies of the prepared samples were characterized by various techniques, including XRD, EDX, FESEM, HRTEM, SAED, BET and Raman spectroscopy. It is found that the obtained Si-NSs present uniform spherical shape and smooth surface. The effects of experimental parameters (including quenching gas and length of reaction path) on morphology and size distribution of Si particles were investigated. The growth mechanism of Si nanoparticles in the thermal plasma was discussed. Si-NS/phenolic resin (PR) composites were fabricated and their performances including thermal stability, thermal conductivity, and dielectric properties were measured. It indicates the composites exhibit high thermal conductivity (6.2 W m(-1) K-1) and dielectric constants of 106 at 100 Hz, which implies they are applicable for energy storage-capacitors. The high thermal conductivity and dielectric constant can be attributed to their uniform spherical shape and smooth surface, which enable them to disperse uniformly in the polymer matrix.