Optical Spectra of Gadolinium(III) Ions in Melts of Alkali Metal Fluorides

Optical spectra of MF−GdF3 (M = Li, Na, K, and Cs) and NaF−CsF−GdF3 molten systems are presented. On the basis of spectral data, it has been determined that stable complex groups GdF63−\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\rm{GdF}_{6}^{3-}$$\end{document} are formed in these melts. In the molten LiF−GdF3 system, the GdF4−\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\rm{GdF}_{4}^-$$\end{document} group, which decomposes over time, is found along with the GdF63−\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\rm{GdF}_{6}^{3-}$$\end{document} complex group. It has been suggested that the number of cations in the second coordination sphere of the GdF63−\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\rm{GdF}_{6}^{3-}$$\end{document} groups decreases from 14 to 13 when passing from the melts of LiF, NaF to KF, CsF.