Low-temperature synthesis of K2Ta2O3F6

New method for obtaining pure powdered K2Ta2O3F6 was suggested through fluorination of ammonium tantalum hydroxide with NH4HF2/KF at room temperature. The main reaction product (NH4)2KTaOF6 was assumed to be a precursor. K2Ta2O3F6 can be obtained by calcining the precursor at 300 °C. The reaction of (NH4)2KTaOF6 with NH4HF2 may take place at 200–250 °C, resulting the formation of NH4KTaF7. The thermal decomposition of NH4KTaF7 resulted in KTaF6 at 300 °C for 1 h. Hydrolysis of KTaF6 produces K2Ta2O3F6 at 300 °C for 2–3 h.