Density functional study on the growing patterns and reactivity of small Sin and MSi(n-1) (M = Ni, Cu, Pd, Ag) aggregates.

CARLA LORENA HEREDIA; VERÓNICA FERRARESI CUROTTO

La Plata

Workshop; 4th Workshop on Novel Methods for Electronic Structure Calculations, and First Southamerican Congress on Materials; 2011

Universidad Nacional de La Plata

In this work, the relationship between tetragonal ZrO2 bulk type material and its nanoparticles (NPs) developed with different sizes and shapes, is studied to observe if any kind of destruction of the lattice periodicity appear both in a thin shell contiguous to the surface and in the whole NP, specially when the sizes are close to 2 nm. Methodologically, the relative stabilities of the NP are determined by calculating the their formation energies. The refinement of the distribution of distances of Zr-Zr and Zr-O sub-lattices, show clearly critical sizes in which a crystalline core co-exist with a disordered shell. This information are consistent with the size obtained from electronic density of states analyses in different shells in which the bulk behavior is found. Shells close to the NPs surface show atomic disorder seen by the introduction of states in the gap. This disorder depends on the shape and the atomic surface termination. In general when the NP size increases its crystalline core size increases too. What is herein found is that while the thickness of the amorphous layer remains at least for the sizes studied here, it increase when we change from faceted to spherical. Therefore, at the studied size range, crystalline cores are found in faceted NPs.