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

作者：Isogai Tomohiro^*; Nakai Takaaki; Inoue Hidemi; Nakanishi Kenta; Kohara Shinji; Saito Morihiro; Inaba Minoru; Tasaka Akimasa

来源：Journal of Physical Chemistry B, 2011, 115(31): 9593-9603.

DOI：10.1021/jp110867k

To understand the ionic and nonionic species in (CH(3))(4)NF center dot mHF, (CH(3))(3)N center dot mHF, (C(2)H(5))(4)NF center dot mHF, and (C(2)H(5))(3)N center dot mHF melts, the structures of these melts were investigated by infrared spectroscopy, NMR, and high-energy X-ray diffraction. Infrared spectra revealed that three kinds of fluorohydrogenate anions, (FH)(n)F(-) (n = 1, 2, and 3), and molecular hydrofluoric acid (HF) are present in every melt. Ionic conductivity and viscosity of these melts were measured and correlated with their cationic structure. The ionic conductivity of the R(4)N(+)-systems was higher than that of corresponding R(3)NH(+)-systems because a strong N-H center dot center dot center dot F(HF)(n) interaction prevents the motion of R(3)NH(+) cations in the R(3)N center dot mHF melts. (CH(3))(4)N(+) and (CH(3))(3)NH(+) cations gave higher ionic conductivity than (C(2)H(5))(4)N(+) and (C(2)H(5))(3)NH(+) cations, respectively, because the ionic radii of former cations were smaller than those of latter. 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.

• 出版日期2011-8-11