The influence of fluoride ions on the equilibrium between titanium ions and titanium metal in fused alkali chloride melts

Jianxun Song, Qiuyu Wang, Jinyu Wu, Shuqiang Jiao, Hongmin Zhu

Research output: Contribution to journalArticlepeer-review

18 Citations (Scopus)

Abstract

KF is employed as a source of fluoride ions added to the melt to disclose the influence of fluoride on the disproportionation reactions of titanium ions, 3Ti2+ = 2Ti3+ + Ti, and 4Ti3+ = 3Ti4+ + Ti. The results reveal that the equilibrium transferred to the right direction for the first reaction and the apparent equilibrium constant increased sharply, mainly because of the formation of coordination compounds: TiFi3-i. The accurate values of the equilibrium constants referring to the formation reactions of Ti3+ + iF- = TiFi3-i (i = 1-6) in NaCl-KCl melt at 1023 K were evaluated with a best fit least squares method. It is also revealed that the stable states of the coordination compounds are TiF2+, TiF2+, TiF4- and TiF63-. Moreover, the Gibbs free energies for complex formation were estimated. Ti2+ was undetectable when the concentration of fluoride ion was high enough. The equilibrium constant for the formation reaction, Ti4- + 6F- = TiF62-, was evaluated. The equilibrium constant, Kc2, for the disproportionation reaction 4Ti3+ = 3Ti4+ + Ti, in chloride melt was determined as 0.015.

Original languageEnglish
Pages (from-to)421-432
Number of pages12
JournalFaraday Discussions
Volume190
DOIs
Publication statusPublished - 2016 Jan 1

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry

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