Synthesis of tabular‐shaped β‐silicon nitride particles by carbothermal reduction‐nitridation

Abstract We investigated the effect of additives on the crystal shape of β‐silicon nitride (β‐Si 3 N 4 ) synthesized via the carbothermal reduction‐nitridation process. When SrF 2 was used as an additive, tabular β‐Si 3 N 4 crystals with an aspect ratio of 0.3–0.5 were obtained. The oxygen content within the crystal lattice of the β‐Si 3 N 4 particles varied with the synthesis conditions, reaching 0.94 wt% in samples synthesized at 1600°C for 10 h. The morphology of the β‐Si 3 N 4 crystals was found to be significantly influenced by the surface tension of the silicate glass formed during synthesis, its wettability on silicon nitride, and the vapor pressure of the alkaline earth oxide ( AE O). Specifically, the use of additives with high vapor pressure and low cation field strength suppressed grain growth after Si 3 N 4 nucleation. The volatilization of the AE O then depleted the liquid phase, leading to the formation of β‐Si 3 N 4 crystals with a low aspect ratio. The newly synthesized tabular‐shaped particles hold potential as heat‐dissipating fillers capable of improving heat dissipation in the thickness direction.