Stability of SnO_2 nanocrystalline grains: a study at semi-empirical level

摘要

The purpose of this study is to get insight into the instability which is observed, under operative conditions, in the SnO_2 nanocrystalline materials. To this purpose, the binding and fragmentation energies of SnO_2 crystalline grains have been evaluated quantum mechanically at semi-empirical level using the extended Debye-Hueckel approximation (EHA). The grain structure is assumed to be an unreconstructed rutile lattice, as in the parent solid. The grain size and shape are variable and a parametric search has been carried out on both quantities. It has been found that the interplay of the grain composition and shape, rather than its size, has a primary role on the grain stability. These features represent a central difference with respect to the known properties of pure clusters whose energetics is uniquely dictated by the size.