Physicochemical properties of fluoride melts containing niobium

Physicochemical properties of fluoride melts containing niobium 

Based on Equation (55), it was concluded/assumed that niobium-containing oxyfluoride melts are characterized by the formation of complex ions NbOF63 Systematic investigations of the electro-conductivity of niobium-containing fluoride and oxyfluoride melts were not performed. Some measurements were performed on the molten mixtures KC1 - K2NbF7, KC1 - KF - K2NbF7 by 

Kuznetsov, Polyakov and Stangrit [317, 318] and on KC1 - NaCl - NaF -K2NbF7 by Kovalev, Ioffe and Datlina [319], all in the concentration range of up to 20-25% mass of K2NbF7. In all cases, maximum electro-conductivity was observed at concentrations of about 5-10% mass of K2NbF7. The peaking of the electro-conductivity is explained by the occurrence of two processes with opposite characters. The increase in electro-conductivity is related to the increase in the concentration of potassium ions [319] and fluorine ions [317, 318], whereas the drop in conductivity results from a decrease in free volume due to an increase in NbF72 ion concentration. 

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