Semiclathrate hydrate (SCH), a kind of clathrate hydrates, consists of hydrogen bonded water molecules and guest substances like quaternary ammonium/phosphonium salts. In the present study, ionic conductivity/resistivity of tetra-n-butylammonium bromide (TBAB) SCH was evaluated by AC impedance spectroscopy at 263–280K. In the annealing process, the resistivities were gradually changed: the resistivities decreased at the lower temperature, whereas the resistivities increased at the higher temperature which was close to solid-liquid phase equilibrium temperature of TBAB SCH. The results may be caused by different annealing process. AC impedance spectroscopic method can be applied to monitoring the SCH crystals and their boundaries.
