Dopant Segregation Analysis on Sb:SnO2 Nanocrystals

• Published in: Chemistry : a European journal 2011-10, Vol.17 (41), p.11515-11519
• Main Authors: Stroppa, Daniel G., Montoro, Luciano A., Beltrán, Armando, Conti, Tiago G., da Silva, Rafael O., Andrés, Juan, Leite, Edson R., Ramirez, Antonio J.
• Format: Article
• Language: English
• Subjects: antimony; Chemistry; doping; Electrons; molecular modeling; Nanocrystals; nanostructures; surface chemistry; tin
• ISSN: 0947-6539; 1521-3765
• DOI: 10.1002/chem.201100972

The development of reliable nanostructured devices is intrinsically dependent on the description and manipulation of materials’ properties at the atomic scale. Consequently, several technological advances are dependent on improvements in the characterization techniques and in the models used to describe the properties of nanosized materials as a function of the synthesis parameters. The evaluation of doping element distributions in nanocrystals is directly linked to fundamental aspects that define the properties of the material, such as surface‐energy distribution, nanoparticle shape, and crystal growth mechanism. However, this is still one of the most challenging tasks in the characterization of materials because of the required spatial resolution and other various restrictions from quantitative characterization techniques, such as sample degradation and signal‐to‐noise ratio. This paper addresses the dopant segregation characterization for two antimony‐doped tin oxide (Sb:SnO2) systems, with different Sb doping levels, by the combined use of experimental and simulated high‐resolution transmission electron microscopy (HRTEM) images and surface‐energy ab initio calculations. The applied methodology provided three‐dimensional models with geometrical and compositional information that were demonstrated to be self‐consistent and correspond to the systems’ mean properties. The results evidence that the dopant distribution configuration is dependent on the system composition and that dopant atom redistribution may be an active mechanism for the overall surface‐energy minimization. Crystal clear: The dopant segregation analysis for Sb:SnO2 with different compositions is presented by using an approach that combines HRTEM characterization and surface‐energy ab initio calculations (see figure). The results indicate that the segregation of the dopant atoms is dependent on the overall composition. A discussion based on the total energy minimization of the system is presented to clarify this finding.