Modificação da estabilidade dos polimorfos de Ti0 2 nanométrico pelo excesso de superfície de Sn0 2

Abstract

Some oxides present stable polymorph forms only for nanometric size. Anatase (Ti0 2) is stable in nanosized particles while the rutile phase is stable for larger ones. This results from the surface energies contribution, which modifies the total energy of the system and the phase stability. In turn, surface energy can be altered by the heterogeneous additives distribution, such as surface segregation or surface excess. This study investigated the action of the Sn0 2 on the polymorph stability of nanosized Ti0 2 prepared by polymeric precursor derived from the Pechini method. It appears that there is a strong effect on the stability of anatase and rutile with the Sn0 2 concentration while various surface properties are altered as well as a strong change in particle size, indicating that even though there are no large differences in the charge and size between the two cations, a surface phenomenon may underlie the stability of crystalline phases.