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Ceramica  2012 

Modifica??o da estabilidade dos polimorfos de TiO2 nanométrico pelo excesso de superfície de SnO2

DOI: 10.1590/S0366-69132012000100009

Keywords: tio2, sno2, surface excess, polymorph stability, nanoparticles.

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Abstract:

some oxides present stable polymorph forms only for nanometric size. anatase (tio2) 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 sno2 on the polymorph stability of nanosized tio2 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 sno2 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.

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