title: Phase transformation in titania nanocrystals by the oriented attachment mechanism: the role of the pH value.
abstract: The oriented attachment (OA) mechanism has been investigated as an important process in the formation of anisotropic nanostructures such as depicted. The results showed that the control of a desired phase in this system may be attained by the control of OA mechanism through pH value, obtaining several morphologies.A new synthetic method for TiO(2) nanocrystals starting from metallic Ti and hydrogen peroxide was developed, in order to obtain minimal interferences to evaluate phase transformation in the system. The results revealed that the crystal morphology appeared to be dictated by the pH value, which shows a strong dependence on the surface energy. The involvement of the oriented attachment (OA) mechanism is important to modify the morphology and, hence, the distribution of the surface energy and confirmed that the mechanism can accelerate certain phase transitions, albeit pH dependence in terms of how the mechanism affects the final particle morphology and direction of crystalline growth. The importance of the mechanism was also apparent in extremely basic conditions, which indicates a possible correlation with the formation of hydrogen titanate nanostructures.
authors.affiliation: EMBRAPA Instrumentação Agropecuária, Rua XV de Novembro, 1452-13560-970, CP 741, São Carlos, SP, Brazil. caue@cnpdia.embrapa.br
authors.forename: Caue
authors.initials: C
authors.lastname: Ribeiro
authors.forename: Cristiano M
authors.initials: CM
authors.lastname: Barrado
authors.forename: Emerson R
authors.initials: ER
authors.lastname: de Camargo
authors.forename: Elson
authors.initials: E
authors.lastname: Longo
authors.forename: Edson R
authors.initials: ER
authors.lastname: Leite