Effects of the pH of Initial Solution on Hydrothermally Synthesized TiO2 Nanoparticles

In this paper, we focused on the effects of initial solution’s pH on the composition, structure and morphology of hydrothermally synthesized titanium oxide nanoparticles. TiCl4 and NaOH were used as titanium source and precipitant, respectively. Phase and structure determination of samples were obtained by X-ray diffraction (XRD) analysis. Scanning electron microscopy (SEM) images were used for size and morphology evaluation of the obtained particles. Also, simultaneous thermal analysis (STA) was used for phase transformation evaluation during calcination process. Results indicated that increase in initial pH of the solution could led to increase in crystallite size of hydrothermally obtained nanopowder which is because of enhanced growth condition by increasing hydroxide groups in the solution. Particle sizes of the synthesized nanopowders were smaller than 100 nm and the mean particle sizes decreased from 60 to 25 nm by increasing in initial pH from 3 to 7, respectively. The results also showed that at initial pH=9 the obtained synthesized nanopowders were in amorphous state and calcination in 700 ۫C was led to sodium titanate phase.