A novel approach to simultaneously enhance the Seebeck coefficient and electrical conductivity in rutile phase of TiO2 nanostructures

Abstract

In the present study, we have used a novel technique to simultaneously enhance the Seebeck coefficient and electrical conductivity of Titanium Dioxide (TiO2) nanostructured by grown by a simple sol-gel method. X-Ray Diffraction (XRD) data has demonstrated the pure rutile phase of TiO2 with the planes (1 1 0), (1 0 1), (2 0 0), (1 1 1), (2 1 0), (2 1 1) and (2 0 0). It was observed that the best crystallinity for samples was achieved at annealing temperature 800 °C. We argue that titanium (Ti+4) and oxygen (O−2) atoms get thermal energy due to the high temperature annealing process and move to their designated places in the crystal structure. Raman spectroscopy measurements have further confirmed the formation of the rutile phase of TiO2 and its atomic vibrations in the lattice crystal structure. We have observed Raman peaks at 446.98 and 698.8 cm−1 with Eg and A1g modes of TiO2 rutile structure respectively while Scanning Electron Microscope (SEM) images are also supported the XRD and Raman results as well. Seebeck coefficient and electrical conductivity have obeyed the increasing trend simultaneously (−286.6 μV/°C and 110 S/cm) and maximum values were obtained for the sample annealed at 800 °C. The enhancement in the Seebeck coefficient and electrical conductivity was related to energy filtering effect and demonstrated in the manuscript with supporting results.