Influence of growth temperature on titanium sulphide nanostructures: from trisulphide nanosheets and nanoribbons to disulphide nanodiscs.

We report the fabrication and characterization of titanium sulphide nanostructures using a chemical vapour transport (CVT) method. In CVT, reactions occur between titanium and sulphur powder in the vapor phase for TiS x nanostructure growth. Systematic studies on the effect of temperature, consequent structural evolution and optical properties were investigated by various characterization techniques. A series of experiments were performed by maintaining a fixed compositional ratio (1 : 3) of Ti and S within a temperature range from 400 °C to 650 °C. On increasing the temperature from 400 °C to 650 °C; a gradual change in morphology was obtained from nanosheets (NS) to mixed phase nanoribbons and nanosheets (NS: NR), nanoribbons (NR), and nanodiscs (ND) of titanium sulphide, which was confirmed using SEM/TEM analysis. Then, the composition of titanium sulphides was studied using XRD, EDX and Raman spectroscopic techniques and it is observed that NS, NR and NS: NR have the composition ratio of TiS 3 whereas ND has a ratio of TiS 2 . The phenomenon of decomposition of TiS 3 into TiS 2 at elevated temperatures was explained using thermogravimetric analysis (TGA) and differential thermal analysis (DTA) along with pictorial representations. The optical properties of the prepared TiS 3 /TiS 2 nanostructures were studied using UV-vis and photoluminescence spectroscopy. It is concluded that composition ratio of Ti and S as well as the temperature variation plays a crucial role in the formation of different Ti-S nanostructures with unique optical, electronic and thermal properties.