The thermal decomposition of dilute solutions of K2CO3 in the ternary fluoride eutectic (Li, Na, K)F (FLINAK) at 750°C was studied both by chemical analysis of quenched melts and in situ by a potentiometric method. The carbonate simultaneously vaporizes as M2CO3 and decomposes: CO32−=CO2+O2− , until a steady state is reached where the major part of the carbonate is retained in the melt. Voltammetric study of the carbonate reduction shows that the reduction is not direct but goes via the prior reduction of alkali metal: (1) M++e=M , (2) 4M+M2CO3=C+3M2O .

The thermal decomposition of dilute solutions of K2CO3 in the ternary fluoride eutectic (Li, Na, K)Fhas been studied at 750°C. The carbonate simultaneously vaporizes as M2CO3 and decomposes yielding CO2 and O2′ until a steady state is reached where the major part of carbonate is retained in the melt.