title: Prediction of dopant atom distribution on nanocrystals using thermodynamic arguments.
abstract: A theoretical approach aiming at the prediction of segregation of dopant atoms on nanocrystalline systems is discussed here. It considers the free energy minimization argument in order to provide the most likely dopant distribution as a function of the total doping level. For this, it requires as input (i) a fixed polyhedral geometry with defined facets, and (ii) a set of functions that describe the surface energy as a function of dopant content for different crystallographic planes. Two Sb-doped SnO2 nanocrystalline systems with different morphology and dopant content were selected as a case study, and the calculation of the dopant distributions expected for them is presented in detail. The obtained results were compared to previously reported characterization of this system by a combination of HRTEM and surface energy calculations, and both methods are shown to be equivalent. Considering its application pre-requisites, the present theoretical approach can provide a first estimation of doping atom distribution for a wide range of nanocrystalline systems. We expect that its use will support the reduction of experimental effort for the characterization of doped nanocrystals, and also provide a solution to the characterization of systems where even state-of-art analytical techniques are limited.
authors.affiliation: Brazilian Nanotechnology National Laboratory, 13083-970, Brazil.
authors.forename: Daniel G
authors.initials: DG
authors.lastname: Stroppa
authors.forename: Luciano A
authors.initials: LA
authors.lastname: Montoro
authors.forename: Antonio
authors.initials: A
authors.lastname: Campello
authors.forename: Lourdes
authors.initials: L
authors.lastname: Gracia
authors.forename: Armando
authors.initials: A
authors.lastname: Beltrán
authors.forename: Juan
authors.initials: J
authors.lastname: Andrés
authors.forename: Edson R
authors.initials: ER
authors.lastname: Leite
authors.forename: Antonio J
authors.initials: AJ
authors.lastname: Ramirez