Structural, optical and charge transport study of rutile TiO2 nanocrystals at two calcination temperatures

In this study the influence of two different calcination temperatures 80 degrees C and 450 degrees C on the structural, optical and charge transport properties of rutile TiO2 nanocrystals has been investigated. TiO2 nanocrystals have been prepared at low temperature by a simple hydrolysis method using titanium tetrachloride as starting precursor. The results of X-ray diffraction (XRD) showed that the prepared nanocrystals have a rutile tetragonal crystalline structure. Specific surface area of 80 degrees C and 450 degrees C calcinated rutile TiO2 nanocrystals are 25.38 x 10(5) cm(2)/g and 7.61 x 10(5) cm(2)/g respectively, which has been calculated by X-ray diffraction data. Williamson-Hall plot results indicate the presence of compressive strain at 80 degrees C and tensile strain at 450 degrees C. Ultraviolet-visible (UV-vis) absorption spectroscopy is used to calculate the band gap of the material and the shift in absorption edge and it has been observed that the absorption spectra are strongly modified by the calcination temperature. The red-shift in photoluminescence (PL) is attributed to the change in strain from compressive to tensile. Photoconductivity (PC) measurements showed that capture cross-section of 80 degrees C (R1) and 450 degrees C (R2) calcinated rutile nanocrystals are 55.10 x 10(-10) and 39.50 x 10(-10) cm(2) respectively. High value of electron life-time, low value of radiative recombination and a four order increase in photogenerated charge carriers have been reported for the rutile TiO2 nanocrystals calcinated at 450 degrees C. Crown Copyright (C) 2011 Published by Elsevier B.V. All rights reserved.