Sublimation and related thermal stability of PbSe nanocrystals with effective size control evidenced by in situ transmission electron microscopy

Abstract The stability of nanomaterials has great influence on their applications. As the opposite process of material growth, sublimation is closely related to material thermal stability. Here, the sublimation process of PbSe nanocrystals as a typical case is studied at atomic scale, and the related size, surface and interface effects are discussed. Due to the interaction of electron beam and surface organic ligands, the sizes of nanocrystals are effectively controlled via introduction of electron beam at different growth stages, which facilitates direct observation of the size dependence of sublimation process. The nanocrystals of less than 10 nm in size show directional sublimation, and those of larger size sublimate uniformly. At the contact interface of nanocrystals with slightly different orientations, the strain fields accelerate local sublimation, while the dislocation motions retard local sublimation, which lead to the deviation of fracture interface from original contact interface. The systematical study of size/surface/interface dependent sublimation behaviors of PbSe nanocrystals facilitates better understanding of the stability of related materials during sublimation as well as crystal growth as the reversed process.