One-step synthesis and its mechanism of potassium hexatitanate whiskers from potassium dititanate and metatitanic acid

The high price of potassium hexatitanate (K2Ti6O13) whiskers restricts its broad applications. The current production method is composed of complex processes and generates a large amount of wastewater. In this work, we propose a new one-step synthesis approach for producing potassium hexatitanate whiskers. Potassium dititanate and metatitanic acid are mixed at the ratio of TiO2/K2O = 4 and then calcined at 1000 °C to synthesize potassium hexatitanate whiskers. We used XRD, SEM, TG-DSC, and other characterization techniques combined with thermodynamic calculations to study the synthesis mechanism of such one-step process. The thermodynamic calculations show that the reaction free energy of K2Ti6O13 whiskers synthesized by this process is negative even at room temperature, confirming that this process has a higher reactivity than the conventional synthesis approach by K2CO3 and TiO2. Moreover, the melting of K2Ti2O5 at 916 °C provides a necessary environment for the crystal growth of K2Ti6O13 nanoparticles, which is the key to the preparation of K2Ti6O13 whiskers. This new synthesis approach will significantly reduce the producing cost of K2Ti6O13 whiskers, thereby expanding its applications.