Role of an intermediate phase in solid state reaction of hydrous titanium oxide with potassium carbonate

The reaction mechanism between hydrous titanium oxide and potassium carbonate at low temperatures was investigated by using XRD, TG, Raman spectra and TEM. In spite of the TiO2/K2O mole ratio in mixtures, the solid state reactions always consisted of two stages. In the first stage (500-640 °C), K2Ti3O7 nanocrystallites with layered structure were formed by the direct reaction of TiO2 and K2CO3 which was clearly confirmed by TG studies in CO2 atmosphere. In the second stage (≥640 °C), the TiO2/K2O mole ratio in mixtures affected the solid state reaction mechanism remarkably. A new transformation mechanism was found for mixtures with TiO2/K2O mole ratio of 4. The separation between the two stages could be used to control the morphologies and microstructures of potassium titanates by adjusting CO2 partial pressure in atmosphere.