In this work new Raman spectroscopic experiments on rare earth metal-rare earth trihalide melts (Ln-LnX3 and LnX2-LnX3: Ln=Ce, Nd; X=Cl, I) and their mixtures in alkali halide eutectic solvents ((LiX-KX)eu; X=Cl, I) are presented. The neodymium and cerium systems have been selected because their metal-metal trihalide melts exhibit very different behavior of the specific electric conductivity as function of the metal concentration. On the one hand, in the Ce-systems it increases strongly which may be due to the formation of mobile electronic defect states. On the other hand, in the Nd-systems it shows only a shallow maximum at the composition of NdX2.5.