Raman spectroscopic and DTA studies of aqueous rare earth thiocyanate solutions

Abstract

Raman measurements were carried out for aqueous rare earth thiocyanate [Ln(SCN)3; Ln=La3+~Lu3+] solutions (R=20; R is moles of water per moles of salt) in the liquid state at room temperature and in the glassy state at liquid-nitrogen temperature. Raman band shifts for the C-S and C-N stretching bands of the SCN− ion indicated that the SCN− ion binds to a rare earth ion only at the N end. Thus, these solutions are better called as aqueous rare earth isothiocyanate solutions. Glass transition temperatures (Tg's) of these solutions were also measured. The Tg values have a distinct extended s-shape and are compared with the previous ones for aqueous rare earth chloride and perchlorate solutions. Series behavior of the Tg results is discussed in conjunction with the coordination number change in the middle of the series.