Dielectric Properties of Ferroelectric Liquid Crystals with Diversified Molecular Structure |
| J.M. Czerwieca, R. Dąbrowskib, M. Żurowskab, D. Ziobrob and S. Wróbela
a Institute of Physics, Jagiellonian University, Reymonta 4, 30-059 Cracow, Poland b Institute of Chemistry, Military University of Technology, S. Kaliskiego 2, 00-908 Warsaw, Poland |
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| Mesomorphic, thermodynamic, electro optic and dielectric properties of three homologues of fluorosubstituted esters are described. Full chemical names of these compounds are as follows: (S)-(+)-4 (1-metyl-hepty-loksy)benzoate (6-penta-fluoro-propano-ynloxyhex 1-oxy) biphenyl-4-yl (in short 2F6BBiOC8), (S)-(+)-4 (1-metyl-hepty-loksy)benzoate (6-nona-fluoro-pentano-yloxyhex 1-oxy) biphenyl-4-yl (in short 4F6BBiOC8), (S)-(+)-4 (1-metyl-hepty-loksy)benzoate (6-trideca-fluoro-heptano-yloxyhex 1-oxy) biphenyl-4-yl (in short 6F6BBiOC8). The compounds exhibit ferroelectric smectic C* phase between crystalline and isotropic phase. Only one compound (6F6BBiOC8) shows antiferroelectric phase (SmC*A) observed by dielectric spectroscopy, but the range of this phase is narrow of about 2°. All three compounds exhibit in the SmC* phase Goldstone mode and Maxwell-Wagner relaxation hidden in the conductivity contribution at low frequencies, whereas in the SmC* A phase two anti-ferroelectric modes (AFM1) and (AFM2) contribute to the dielectric spectrum. The compounds were studied using differential scanning calorimetric, frequency domain dielectric spectroscopy, and reversal currents method to determine spontaneous polarization. |
| DOI: 10.12693/APhysPolA.117.553 Erratum DOI: 10.12693/APhysPolA.117.978 PACS numbers: 77.84.Nh, 78.15.+e, 64.70.M- |