Mechanism of synthesis of anatase TiO2 pigment from low concentration of titanyl sulfuric-chloric acid solution under hydrothermal hydrolysis

In order to investigate the influence of Cl-/SO42- molar ratios and hydrolysis temperature on the hydrolysis process and TiO2 pigment, H2TiO3 was prepared with a low concentration of titanyl sulfuric-chloric acid solution by hydrothermal hydrolysis. Under the optimal hydrolysis conditions, 1.5-2.2 mu m of H2TiO3 samples were achieved. After doping and calcination, anatase TiO2 pigments demonstrated excellent performance: the achromic ability of tinctorial strength (TCS) and blue phase index (SCX) were 1,429 and 4.07, respectively. As hydrolysis was a significant step in the process, the structure was simplified to a periodic structure of Ti[OH](H2O)(3)Cl(SO4) to simulate the cluster structures. Based on experimental results and density functional theory (DFT) calculation, the hydrolysis mechanism was presumed to be a process of anionic (OH-, Cl- and SO42-) competition reaction to explain the formation of anatase-type H2TiO3, and the crystal growth direction of H2TiO3 was also confirmed to be a (OA) and b (OB).