Dielectric Relations of Nematic 4-n-Heptylamino benzoic Acid in Mixtures with 4-Cyano benzoic Acid and 4-Fluoro benzoic Acid

Dielectric constants and the dielectric loss in the frequency range from 0.1–12 MHz were measured in the binary systems of 4-n-heptylamino benzoic acid with 4-cyano benzoic acid and 4-fluoro benzoic acid in the nematic phase. Not only the strong increase of dielectric anisotropy, but also the appearance of a Debye relaxation in the MHz range in both the mixtures proves the existence of the mixed associates. This model was proved by the temperature dependence of relaxation times and on chemical structure of the mixed associates, as well as, by the comparison with the measurements of one more binary system of acids.