Raman spectroscopic study of molten SmCl3-ACl systems (A = Li, Na, K)

Raman spectra of molten SmCl3-ACl systems (A=Li, Na, K) were measured at different compositions and temperatures. The spectra showed polarized peaks centered at about 256 cm(-1) in the whole range of concentration and depolarized peaks at about 120 cm(-1) in the low concentration range of SmCl3. These Raman shifts were identified as the totally symmetric stretching vibration v(1) and the degenerate bending vibration v(5) of octahedral SmCl63- complex anion, respectively. Peak splitting of the isotropic component was recognized clearly in the reduced Raman spectra of mixtures. Clustering of complex anions is thought to occur in the melts. However, the clustering might be restrained when the SmCl3 concentration became relatively low by adding LiCl, NaCl or KCl. The v(5) peak was the strongest at the SmCl3 concentration of 25 mol% in the SmCl3-KCl system among the three systems. The temperature effect on the Raman shift, reflecting the structural change, was negligibly small between 823 K and 1023 K. (C) 1999 Elsevier Science S.A. All rights reserved.