This study was financially supported by National Science Council of Taiwan, in the Project no. 98-2218-E-006-238.
Morphology, Chemical Composition and Phase Transformation of Hydrothermal Derived Sodium Titanate
Article first published online: 3 JUL 2012
© 2012 The American Ceramic Society
Journal of the American Ceramic Society
Volume 95, Issue 10, pages 3297–3304, October 2012
How to Cite
Li, M.-J., Chi, Z.-Y., Wu, Y.-C. (2012), Morphology, Chemical Composition and Phase Transformation of Hydrothermal Derived Sodium Titanate. Journal of the American Ceramic Society, 95: 3297–3304. doi: 10.1111/j.1551-2916.2012.05330.x
- Issue published online: 2 OCT 2012
- Article first published online: 3 JUL 2012
- Manuscript Accepted: 21 MAY 2012
- Manuscript Received: 19 SEP 2011
- National Science Council of Taiwan. Grant Number: 98-2218-E-006-238
This study intends to clarify the discrepancies on the effect of precursor size, chemical composition, and thermal behavior of Na-titanate obtained through a conventional hydrothermal reaction of anatase in a highly concentrated aqueous NaOH solution. According to experimental results, as well as that presented in related literatures, ultrafine anatase precursor favors nanofiber formation, whereas larger-particle anatase precursor forms nanotubes. The formation mechanism, in correlation with the precursor size and the resulting morphology of the obtained titanate product, is described in detail. According to X-ray Diffraction and Raman analyses, the as-formed Na-titanate is considered a quasi-disordered structure that allows the occupation of a wide range of Na into the titanate structure. An increased Na/Ti ratio is observed with increased temperature, which simultaneously results in a distortion of the titanate structure. Moreover, the as-synthesized Na-titanate is thermally unstable and tends to degrade into amorphous clusters after heat treatment at 300°C. Rod-like Na2Ti6O13 is recrystallized from the amorphous cluster at 700°C–800°C and becomes plate-like after annealing at 900°C via a parallel assembly of Na2Ti6O13 rods. An additional Na2Ti3O7 phase appears at high temperatures, exhibiting a relatively higher Na/Ti ratio.