Effect of calcinations on electrical properties of TiO2 nanotubes

作者：Vijayan Pournami P; Thomas Marykutty; George K C^*

来源：Journal of Applied Physics, 2012, 112(10): 104308.

DOI：10.1063/1.4759358

Nanotubes of TiO2 synthesized by hydrothermal method are treated at three different temperatures (400, 600, and 800 degrees C). Calcinations cause phase change as evidenced from x-ray diffraction patterns. AC conductivity studies done on as prepared TiO2 and calcined samples in the frequency range 100Hz-1MHz and at various temperatures between 303 and 423 K. AC conductivity increases with the calcination followed by a decrease which can be attributed to rutile formation. Surface defects are responsible for the ac conductivity change. PL spectrum shows the presence of surface oxygen vacancies and self trapped excitons in TiO2 nanotubes and annealed samples. The variable range hopping dominates the mode of electrical transport at low temperature and thermally activated process at high temperature. Conductivity is at its maximum for the sample calcined at 400 degrees C. There is a transition temperature in between the variable range hopping and thermally activated process, which differs with calcinations.

• 出版日期2012-11-15