Effect of Temperature on the Structural, Morphological and Optical Properties of Hydrothermally Synthesised Titanium Dioxide

Three samples of titanium dioxide nanoparticles were prepared by hydrothermal treatment at three different temperatures (140ºC, 180ºC, 220ºC) using a strong acid (HNO3). The precursors were heated for 8 hours to form the TiO2 structure, and then thin films were formed on a glass base using a spin coater, then structural properties were studied.The lattice constants were equal to a = b = 3784 Å, c = 9515 Å for all samples and the crystal structure is tetragonal. FESEM imaging showed that the surface was smooth with few pores and the grain size was about 117.298 ~ 148.355 nm for sample1 (prepared at 140ºC), 85 ~ 124.981 nm for sample2 prepared at 180ºC and 56.545 ~ 89.056 nm for sample3 prepared at 220ºC. Uv-v characterisation has shown that the first structure has a higher transmittance than the other two structures for visible light beam, but in general all samples have low absorbance for all spectral regions. The band gab energy was increased as the heating temperature increased where it was around 2.62 eV for sample1 and 2.82 eV for structure2 also sample3 has a wider band gab around 2.86eV.