Structure and stability of monodisperse 1.4-nm ZnS particles stabilized by mercaptoethanol

Extremely small 1.4-nm size mercaptoethanol-stabilized ZnS clusters have been synthesized with narrow size distribution. The structure of these clusters was studied by wide-angle X-ray scattering. The scattering curves were compared with the calculated scattered intensity of a variety of model clusters (ZnS)(N) and different defect types via Debye functions. In the as-received state the pattern is best described by a fragment of the zinc blende lattice, with N approximate to 30, and a defective stacking of three to four (111) planes. A large improvement of the simulation is gained by introducing liquidlike disorder to the model structure. This raises the unanswered question of a "real" liquid state of these small clusters at room temperature, The cluster matrix is thermally stable to 583 K. Above this temperature the primary cluster coalesce to form larger particles. Annealed at 1013 K the particles grow to > 4.0 nm with a highly defective zinc blende structure.