Effect of calcination conditions on hydrophilicity of titanium dioxide films

Abstract

Titanium dioxide was prepared via a sol-gel method using titanium isopropoxide as a precursor. Borosilicate glass slide was employed as a support for titanium dioxide thin film. Calcination conditions, namely, calcinations temperature and calcinations atmosphere, were varied to investigate their effects on hydrophilic property of titania thin films. Titania thin film that was calcined under stagnant air at 550 ํC possessed the smallest saturated contact angle. As calcinations temperature decreased, the saturated contact angle of the sample grew larger. The increase was attributed to lower Ti[superscript 3+] surface defect and the presence of less rutile phase in the sample. Regarding calcinations atmosphere, the smallest saturated contact angel was observed in the sample that was calcined under stagnant air probably due to the highest Ti[superscript 3+] surface defect. Then further surface modification of the sample was done by employing two-step calcinations process. The first step involved calcinations under air flow so as to transform amorphous titania to titania crystals. The, the sample was calcined under hydrogen flow in the second step to create more Ti[superscript 3+] surface defect. We found that small saturated contact angle could be obtained even at a lower calcinations temperature by using the two-step calcinations process, when compared to the single-step calcinations process