Sol-gel synthesis and properties of titanium dioxide for cosmetics
Three kinds of sunscreen agents,titanium dioxide,strontium titanate and barium titanate were synthesized by sol-gel method.Crystal structure characterization shows that titanium dioxide is tetragonal rutile phase TiO2,with space group P42/mnm(136).Strontium titanate is cubic crystal system with space group Pm-3m(221).Barium titanate is tetragonal with space group P4/mmm(123).It is found that titanium dioxide and barium titanate are pure phases,while strontium titanate contains a small amount of C-O functional groups.SEM and TEM results show that the particles of titanium dioxide,strontium titanate and barium titanate are approximately spherical,and the average particle size is 30,40 and 60 nm,respectively.The optical properties show that titanium dioxide,strontium titanate and barium titanate have high UV absorption coefficients,and the optical absorption coefficient of titanium dioxide can be extended to 400 nm.The calculated optical bandgap values of titanium dioxide,strontium titanate and barium titanate are 3.03,3.27 and 3.25 eV,respectively.The results show that titanium dioxide has a wide UV absorption capacity and uniform particle distribution,with a white color,which can be potentially used in various spices,sunscreen,saponin,white soap and toothpaste.