The structure of β-Na2TiO3 was refined. The formation/transformation mechanisms and ion-exchange properties of α-, β-, and γ-Na2TiO3 were investigated.

To improve the use of natural rutile ore with fine particle size and high contents of MgO and CaO in China, a novel pre-treatment method of natural rutile ore by NaOH roasting to prepare a-Na 2 TiO 3 for TiO 2 production was proposed. g-Na 2 TiO 3 is a stable by-product that can lead to serious caking in the reactor and low titanium yield. Thus, structural control in alkali roasting is necessary. The influence of particle size of natural rutile ore, NaOH-toore mass ratio, roasting temperature and roasting time on the crystal forms of Na 2 TiO 3 was systematically investigated. The optimized reaction parameters were as follows: average particle size of natural rutile ore, À9.2 mm; NaOH-to-rutile mass ratio, 1.2; roasting temperature, 5508C; and roasting time, 70 min. In these conditions, the titanium conversion and the fraction of a-Na 2 TiO 3 exceeded 99.5% and 98%, respectively. Moreover, the addition of H 2 O or as-prepared partial a-Na 2 TiO 3 as crystal seeds into the reaction system could prepare the roasting product with a-Na 2 TiO 3 as its main phase using À45 mm (À325 mesh) natural rutile ore.

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 μm 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)3Cl(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).