<Original Papers>Studies on the Production of Tantalum by Electrolysis of Fused Salt.(III) : On the Ionic Form and the Equilibrium of the Fused Salt

The purpose of the present work is to investigate what are the character and the ionic form of the components making up the electrolytic bath in the fused state. The alkali sides of the binary phase diagrams, KF-K_2TaF_7,KCl-K_2TaF_7,KBr-K_2TaF_7,KF-KCl・K_2TaF_7,KBr-KF・K_2TaF_7,and NaCl-K_2TaF_7 were made out. The freezing point depression equation was applied to the liquidus curves of the alkali halides on the assumption of the eutectic diagrams as follows : [numerical formula] where [numerical formula]. N_+ and N_- were adopted Temkin ionic mole fraction. The complex ionic equilibrium were concluded from the agreement of the measured value with the theoretical. TaF_7^+F^-=TaF_8^ TaF_7^+Cl^-=TaF_7Cl^ The relation between the equilibrium constants K_1 and K_2 was K_1>K_2