Vibrational modes and structure of the LaCl 3[sbnd]CsCl melts

Abstract

Raman spectra of the LaCl 3 CsCl melt mixtures at ten different compositions, including solid and molten LaCl 3 have been measured at temperatures up to 900 °C. The systematic spectral changes with composition and the invariance of the spectra on temperature are discussed in terms of the melt structure and in relation to other lanthanide halide–alkali halide melt mixtures. The data suggest that in CsCl-rich mixtures the predominant species present are the LnC l 6 3 − “octahedral” while in LaCl 3-rich melts a network-like structure of chloride bridged coordination polyhedra is formed. Most likely the predominant coordination of La 3+ remains six-fold at all compositions. The reduced isotropic and anisotropic Raman spectra are calculated and compared with the recently published simulated Raman spectra of the same melt mixtures.