Studies of ferroelectric properties of novel liquid crystals with tetrafluorophenylene

Plotting polarization versus electric field with sine waveform is used to determine the ferroelectricity of liquid crystals in conjunction with other usual methods as optical polarizing microscope and differential scanning calorimeter. Results show that the liquid crystal with the molecular core structure of tetrafluorobiphenylene has a rather wide temperature range of ferroelectric mesophase SmC*, and 4'-[(s)-2-methylbutoxycarbonyl] phenyl 4-(4'-n-nonyloxy-2, 3, 5, 6-tetrafluorobiphenyl-1-ethynyl) benzoate exhibits the range of about 110/spl deg/C from 60 to 170/spl deg/C, the polarization of 8.9/spl times/10/sup -6/ C/m/sup 2/ and the tilt angle of 9.2 degrees at temperature 10/spl deg/C below curie point.