Surface\nSelf-Diffusion Induced Sintering of Nanoparticles

Despite\nthe critical role of sintering phenomena in constraining\nthe long-term durability of nanosized particles, a clear understanding\nof nanoparticle sintering has remained elusive due to the challenges\nin atomically tracking the neck initiation and discerning different\nmechanisms. Through the integration of in situ transmission electron\nmicroscopy and atomistic modeling, this study uncovers the atomic\ndynamics governing the neck initiation of Pt–Fe nanoparticles\nvia a surface self-diffusion process, allowing for coalescence without\nsignificant particle movement. Real-time imaging reveals that thermally\nactivated surface morphology changes in individual nanoparticles induce\nsignificant surface self-diffusion. The kinetic entrapment of self-diffusing\natoms in the gaps between closely spaced nanoparticles leads to the\nnucleation and growth of atomic layers for neck formation. This surface\nself-diffusion-driven sintering process is activated at a relatively\nlower temperature compared to the classic Ostwald ripening and particle\nmigration and coalescence processes. The fundamental insights have\npractical implications for manipulating the morphology, size distribution,\nand stability of nanostructures by leveraging surface self-diffusion\nprocesses.