Analysis of Cationic Structure in Some Room Temperature Molten Fluorides and Dependence of Their Ionic Conductivity and Viscosity on HF-Concentration

摘要

To understand the ionic and non-ionic species in (CH_3)_4NF-mHF, (CH_3)_3N-mHF, (C_2H_5)_4NF-mHF, and (C_2H_5)_3N-mHF melts, the structures of these melts were investigated by infrared spectroscopy, NMR and high-energy X-ray diffraction. IR spectra revealed that the complex fluoride anions such as (HF)_nF~-(n = 1, 2, 3) and molecular HF are present in all melts. Ionic conductivity and viscosity of these melts were measured and correlated with their cationic structure. The ionic conductivity of the R4N~+-systems was higher than those of corresponding R_3NH~--systems. (CH_3)_4N~+ and (CH_3)_3NIT~+ cation gave higher ionic conductivity than (C_2H_5)_4N~+ and (C_2H_5)_3NH~+ cation, respectively. It was concluded that these effects on ionic conductivity can be explained by the cationic structure and the concentration of molecular HF in the melts.