Local supersaturation dictated branching and faceting of submicrometer PbS particles with cubic growth habit.

Abstract

Hierarchical cubelike submicrometer PbS particles consisting of truncated octahedrons, cuboctahedrons, and cubes were prepared in ethylene glycol solution under favorable high mole ratio of thiourea (Tu) to Pb(AC)2 (R(S/Pb)) via a pumping process. A qualitative analysis based on the classical nucleation theory coupled with the crystal growth theory is employed to interpret the observed experimental phenomena. By varying the concentration of reactants, R(S/Pb), and reaction temperature, it is possible to tune the local supersaturation degree (LSD), which is determined by the number of nuclei and overall growth unit (or concentration), surrounding each growing particle that dictates the branching and faceting of PbS particle. Relatively high LSD that is required for branching growth could be achieved at lower concentration of Tu and reaction temperature. Increasing the concentration of Tu and reaction temperature resulted in less LSD and yielded cubic PbS particles.