Solubility of TiO₂ in NaF-CaF₂-BaF₂ Melts

The solubility of TiO₂ in NaF-CaF₂-BaF₂ ternary eutectic melts was investigated at the temperature range of 1025–1150 °C. The least-squares equation was obtained from the relationship between the reciprocal temperature and the natural logarithm of the titanium concentration in the melts saturated with TiO₂. The corresponding partial molar enthalpy of dissolution of TiO₂ was found to be 188 kJ/mol. The titanium saturation concentration was 3.73 wt% at 1100 °C. From the titanium concentration change with the added amount of TiO₂ at different holding time after a final stirring, it was found that not only complete dissolution of TiO₂ but also enough sedimentation of excessive TiO₂ should be guaranteed to obtain more reliable solubility data. The holding time of 10 h was found to be enough for the excessive TiO₂ particles to settle down in our experimental conditions. It is noteworthy that in case of adding TiO₂ in excess of its solubility, the Ba_1.12(Ti₈O₁₆) phase was observed at the lower and bottom of the solidified salt ingots.