Interfacial effects on diffusion and densification in heterogeneous SiC nanoparticle sintering

Silicon carbide (SiC), as a typical representative of third-generation semiconductor materials, is widely used in the fabrication of high-performance semiconductor devices and advanced ceramics. However, the synergistic regulation mechanism of polytype heterogeneity and size effects on the sintering kinetics of SiC nanoparticles remains unclear. In this study, molecular dynamics simulations were performed to investigate the high-temperature solid-state sintering behavior of SiC nanoparticles with different polytype combinations and asymmetric particle size configurations. Structural identification, diffusion analysis, and atomic displacement vector analysis were further combined to reveal the microscopic densification mechanisms. The results show that the heterointerface in the 3C/6H-SiC system can regulate atomic diffusion pathways, causing atomic migration to preferentially contribute to pore elimination and interfacial densification, thereby improving densification efficiency. The asymmetric heterogeneous sintering models further indicate that the high surface curvature of small particles and the interfacial strain field synergistically induce asymmetric mass transport. In particular, small 3C-SiC particles exhibit higher atomic mobility and accelerate overall shrinkage. This study clarifies the atomistic mechanism by which polytype heterogeneity and size effects regulate the sintering kinetics of SiC nanoparticles, providing theoretical guidance for optimizing the densification process of nanoceramics.