Dielectric behaviour of Nano-TiO2 bulks

Two kinds of nano-TiO2 samples, including nano-anatase and nano-rutile, were prepared by the hydrothermal method and the gas condensation method, respectively. Results of dielectric measurements are as follows: 1. Nano-TiO2 bulk samples (anatase and rutile) exhibit much higher dielectric constant than coarse-grain samples in the low measuring frequency range. 2. For both nano-anatase and nano-rutile: one peak appears in the spectrum of dielectric constant versus temperature, and it is located in the measuring temperature range of -150 to 150 degrees C for nano-anatase and in the measuring temperature range of 25 to 450 degrees C for nano-rutile. 3. For both nano-anatase and nano-rutile, in the spectrum of dielectric loss versus temperature there exists one peak. The mechanisms of the above-mentioned phenomena were discussed in detail.