Ab Initio Studies of Structure, Electronic Properties, and Relative Stability of SnO2 Nanoparticles as a Function of Stoichiometry, Temperature, and Oxygen Partial Pressure

Relative stability of nanocrystals of rutile SnO2 with defined sizes and controlled stoichiometry was studied, allowing the full relaxations of nanoparticle (NP) atoms. Once stabilized in energy, the structure was analyzed by a refinement of the pair distribution function (PDF) of the Sn–Sn and Sn–O pairs. The calculated pair distribution functions Gcalc(r) of our NP’s larger than 3 nm indicate a rutile crystalline core of 2.4 nm size, which are well-compared with recent Gexp(r) determined from XRD experiments. Therefore, distorted surface layers are decreased to 0.25–0.30 nm width, for stoichiometric and oxygen in excess NP’s. This finding is confirmed by the inspection of the core electronic density of states (DOS), determined with the projected density of states (PDOS) of atoms included in radii sizes of 0.5, 0.7, 0.9, 1.1, and 1.5 nm. The deviation of the NP total DOS from the bulk total DOS is analyzed inspecting the PDOS contributions of cation and anion sublattices, for atoms placed in the core, in...