Study of high temperature phase of titanate nanotubes

Tereza Brunatova¹, Zdenek Matej¹,Peter Oleynikov², Stanislav Danis¹,
Daniela Popelkova³,Radomir Kuzel¹

¹Charles University, Faculty of Mathematics and Physics, Dept.of Condensed Matter Physics, Prague, Czech Republic

²Stockholm University, Dept. of Materials and Environmental Chemistry, Stockholm University, SE-106 91 Stockholm, Sweden

³Institute of Macromolecular Chemistry, Academy of Sciences of the Czech Republic, Prague, Czech Republic

Titanate nanotubes (Ti-NT) are very promising material with many possible applications in bionedicine, in solar cells, lithium batteries, fuel cells etc [1]. Their structure is not fully undertood and there exists several possible stuctures of Ti-NT [1]. The study of temperature stability of Ti-NT is important because some of possible applications of Ti-NT require heating [1]. By heating of Ti-NT titanate nanowires are obtained. Similarly to Ti-NT several possible phases of titanate nanowires can be discovered as for example: Na₂Ti₆O₁₃ [2], Na₂Ti₃O₇ [2], rutile phase of TiO₂ [2-4], anatase phase of TiO₂ [2], [3], beta TiO₂ [4]. The final structure depends also on the amount of sodium ions if some are present in original Ti-NT sample.

In this contribution, the structure of Ti-NT will be briefly introduced and mainly the structure of titanate nanorods and titania nanowires will be discused. The study of titanate nanorods was done by combination of powder X-ray diffraction and 3D rotation electron diffraction. The titanate nanorods were prepared by heating of titanate nanotubes up to 850 C. The structure of final product at 850 C depends on heating conditions and time of heating. We studied samples - heated in air and in vacuum. The heating in air were done in following way: firstly the sample was heated at 850C for 105 minutes and for 1000 minutes, the last heating was at 900C for 1000 minutes. The heating in vacuum was don similar way: firstly heated at 850C for 105 minutes and 3000 minutes, then at 900C for 3000 minutes and last heating was at 1000C for 3000 minutes. Differences between samples heated in air and vacuum are that in air is observed sodium hexatitanate, anatase and rutile but sample heated in vacuum has only visible diffraction lines from anatase witch afterwards transform to rutile.

[1] Bavykin DF. V.,Walsh F. C.: Titanate and titania nanotubes, synthesis, properties and application, RSC Publishing, 2010

[2] Morgado E., jr, de Abreu M. A. S., Pravia O. R. C., Marinkovic B. A., Jardim P. M., rizzo R.C., Araujo A.S.: A study on the structure and thermal stability of titanate nanotubes as a function of sodium content, Solid State Science, 8, 2006

[3] Yu J., Yu H., Cheng B., Trapalis C.: Effects of calcination temperature on the microstructures and photocatalytic activity of titanate nanotubes, Journal of Molecular Catalysis A, 249, 2006

[4] Suzuki Y., Yoshikawa S.: Synthesis and thermal analysis of Tio2-deriveted nanotubes prepared by the hydrotherma method, Jounal Material Res., 19, 2004