Thermal stability of titanate nanorods and titania nanowires formed from titanate nanotubes by heating

• Published in: Materials characterization 2014-12, Vol.98, p.26-36
• Main Authors: Brunatova, Tereza, Matej, Zdenek, Oleynikov, Peter, Vesely, Josef, Danis, Stanislav, Popelkova, Daniela, Kuzel, Radomir
• Format: Article
• Language: English
• Subjects: Anatase; ANISOTROPY; Cross-disciplinary physics: materials science; rheology; ELECTRON DIFFRACTION; Exact sciences and technology; HEATING; LINE BROADENING; MATERIALS SCIENCE; Mathematical models; NANOPARTICLES; Nanorods; NANOSCIENCE AND NANOTECHNOLOGY; NANOTUBES; NANOWIRES; Phase diagrams and microstructures developed by solidification and solid-solid phase transformations; PHASE STABILITY; PHASE TRANSFORMATIONS; Physics; POWDERS; PRECESSION; Precession electron diffraction; RUTILE; Solidification; Titanate nanorods; TITANATES; Titania nanowires; TITANIUM; Titanium dioxide; TITANIUM OXIDES; X-RAY DIFFRACTION
• ISSN: 1044-5803; 1873-4189; 1873-4189
• DOI: 10.1016/j.matchar.2014.10.008

The structure of titanate nanowires was studied by a combination of powder X-ray diffraction (XRD) and 3D precession electron diffraction. Titania nanowires and titanate nanorods were prepared by heating of titanate nanotubes. The structure of final product depended on heating conditions. Titanium nanotubes heated in air at a temperature of 850°C decomposed into three phases — Na2Ti6O13 (nanorods) and two phases of TiO2 — anatase and rutile. At higher temperatures the anatase form of TiO2 transforms into rutile and the nanorods change into rutile nanoparticles. By contrast, in the vacuum only anatase phases of TiO2 were obtained by heating at 900°C. The anatase transformation into rutile began only after a longer time of heating at 1000°C. For the description of anisotropic XRD line broadening in the total powder pattern fitting by the program MSTRUCT a model of nanorods with elliptical base was included in the software. The model parameters — rod length, axis size of the elliptical base, the ellipse flattening parameter and twist of the base could be refined. Variation of particle shapes with temperature was found. •Titanate nanotubes changed to particles of TiO2 and nanorods of Na2Ti6O13 at 850°C.•With heating time and temperature nanorods transformed to rutile nanoparticles.•X-ray diffraction powder pattern fitting indicated an elliptical shape of nanorod base.•No transition of titanate nanotubes to Na2Ti6O13 was found after heating in vacuum.•Heating of titanate nanotubes in vacuum leads to appearance of anatase nanowires.