Mechanism of synthesis of anatase TiO 2 pigment from low concentration of titanyl sulfuric–chloric acid solution under hydrothermal hydrolysis

In order to investigate the influence of Cl − /SO 4 2− molar ratios and hydrolysis temperature on the hydrolysis process and TiO 2 pigment, H 2 TiO 3 was prepared with a low concentration of titanyl sulfuric–chloric acid solution by hydrothermal hydrolysis. Under the optimal hydrolysis conditions, 1.5–2.2 μm of H 2 TiO 3 samples were achieved. After doping and calcination, anatase TiO 2 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](H 2 O) 3 Cl(SO 4 ) 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 SO 4 2− ) competition reaction to explain the formation of anatase‐type H 2 TiO 3 , and the crystal growth direction of H 2 TiO 3 was also confirmed to be a (OA) and b (OB).