A smectic T phase of 1,4-dialkyl-1,4-diazoniabicyclo[2.2.2]octane dibromides

An unidentified phase X of 1,4-dialkyl-1,4-diazoniabicyclo[2.2.2]octane dibromides reported by Nogami et al. in 1985 was reinvestigated by differential scanning calorimetry, polarizing microscopy and temperature-dependent X-ray diffraction. The X phase was thus established as a smectic tetragonal (ST) mesophase which shows spontaneous homeotropic alignment.