Understanding of Non-Classical Crystal Growth via Particle Assembly via In Situ Liquid Cell TEM

The nanoparticle assembly into structures of superlattices and crystals attracts great attention due to their unique optical, thermoelectric, magnetic, energy storage, and catalytic properties. Understanding of mechanisms of particle assembly and interaction between active species can help to establish conditions to control the assembly process and structures of superlattices and crystals, which are closely tied to the physical and chemical properties. However, little is known about the driving forces and controlling factors during the process of particle self-assembly. In this work, we analyzed dynamic information of the process and investigated the Van der Waals force, steric hindrance, Brownian force, and the hydrodynamic force, based on measured particle positions and velocities by directly observing the process of particle self-assembly and tracking individual particles as a function of time via in situ TEM. We studied the crystal surface interactions as a function of pH, electrolyte type, and concentration. We further studied the crystal growth process via particle-oriented attachment, a special type of particle assembly. The results of this work enable the control of particle assembly and the resulting structures and the design of materials with tailored properties.