title: Hydrothermal synthesis and characterization of nanorods of various titanates and titanium dioxide.
abstract: The formation process of titania based nanorods during hydrothermal synthesis starting from an amorphous TiO2.nH2O gel has been investigated. Sodium tri-titanate (Na2Ti3O7) particles with a rodlike morphology were prepared by a simple hydrothermal process in the presence of a concentrated NaOH aqueous solution. The ion exchange reaction of the synthesized Na2Ti3O7 nanorods with HCl under ultrasonic treatment promotes a complete sodium substitution and the formation of H2Ti3O7 nanorods. Low-temperature annealing of the as-produced nanorods of Na2Ti3O7 and H2Ti3O7 leads to a loss of the layered crystal structure and the formation of nanorods of condensed framework phases-sodium hexa-titanate (Na2Ti6O13) and metastable TiO2-B phases, respectively. These transformations proceed without a significant change in particle morphology. The nanostructures were investigated by scanning electron microscopy (SEM), powder X-ray diffraction (XRD), the Brunauer-Emmett-Teller (BET) method, thermogravimetric analysis (TGA), and Raman spectroscopy. The structural defects of the synthesized nanorods were investigated by high-resolution electron microscopy. The presence of planar defects can be attributed to the exfoliation of the zigzag ribbon layers into two-dimensional titanates as well as to the condensation of the layers of TiO6 octahedra into three-dimensional frameworks.
authors.affiliation: Department of Materials Science, Moscow State University, Moscow 119992, Russia. kolenko@msl.titech.ac.jp
authors.forename: Yury V
authors.initials: YV
authors.lastname: Kolen'ko
authors.forename: Kirill A
authors.initials: KA
authors.lastname: Kovnir
authors.forename: Anton I
authors.initials: AI
authors.lastname: Gavrilov
authors.forename: Alexei V
authors.initials: AV
authors.lastname: Garshev
authors.forename: Johannes
authors.initials: J
authors.lastname: Frantti
authors.forename: Oleg I
authors.initials: OI
authors.lastname: Lebedev
authors.forename: Bulat R
authors.initials: BR
authors.lastname: Churagulov
authors.forename: Gustaaf
authors.initials: G
authors.lastname: Van Tendeloo
authors.forename: Masahiro
authors.initials: M
authors.lastname: Yoshimura