Abstrakt
Thermal stability of titanate nanotubes (Ti-NT) was studied in temperature range from room temperature up to 1000 A degrees C in three different atmospheres-in air, vacuum and helium-and differences were observed. In air, vacuum and helium, the release of adsorbed and crystal water was detected in temperatures up to 200 A degrees C.
Transformation of the initial structure to anatase form of TiO2 was found independently of the atmosphere used. But in air the transformation to anatase occurred at lower temperature.
The difference between these atmospheres was approximately 100 A degrees C. However, only in air, the transformation to sodium hexatitanate and rutile form of TiO2 occurred at higher temperatures.
In vacuum, only the anatase phase was detected up to 800 A degrees C. In helium, the transformation to rutile was observed but not to sodium hexatitanate.
The changes of the initial structure of Ti-NT during the elevation of temperature were studied by combination of in situ powder X-ray diffraction, differential scanning calorimetry, thermal gravimetric analysis and mass spectroscopy.