POLARIZATION MEASUREMENT OF NOVEL LIQUID-CRYSTALS WITH TETRAFLUOROBIPHENYLENE

Ferroelectricity and spontaneous polarization of two compounds were in vestigated by plotting polarization versus electric field with a sine waveform in conjunction with other conventional methods such as optica l polarizing microscopy and differential scanning calorimetry. The com pounds are 4'[(s)-2-methylbutoxycarbonyl] phenyl -n-nonyloxy-2,3,5,6-t etrafluorobiphenyl-1-ethynyl) benzoate and 4'-[(s)-2-methylbutoxycarbo nyl] phenyl 4 ''-[(4-n-nonyloxy-2,3,5,6-tetrafluorophenyl) ethynyl] be nzoate. They show polarizations of 8.9 and 12.6 x 10(-6) C/m(2) and ti lt angles of 9.2 and 20 degrees at the temperature at which 10 degrees C below their curie point, respectively. The curie point, that is, th e mesophase transition between the smectic A and the chiral smectic C phases occurs, was identified from the polarization versus electric fi eld hysteresis, and a ferroelectric phase temperature range of 108 deg rees C was found in these materials.