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As a development of the previous investigation on a specific intermolecular interaction in nematic liquid crystal (NLC) systems, new results of the experimental studies of the dielectric permittivity in NLCs based on biphenyls in the LC state and during the LC → IL phase transition are discussed in this work. Dielectric measurements were carried out on a frequency range from 10 to 〖10〗^4 Hz using the capacitive method. The absolute measurement accuracy of ε_⊥and ε_∥was maintained in all experiments and amounted to ± 0.02. A measuring field was fixed at E≈20 V∙〖cm〗^(-1)intensity in homogeneous and homeotropic alignment cells. Molecular orientation was determined by an external constant magnetic field of 0,3 T.
The analysis of the obtained frequency dependences of the components of the complex permittivity for the nematic phase of the studied LCs was carried out using the Debye equation:
ε^' (ω)=ε_∞+(ε_0-ε_∞)/(1+iωτ),
written in the form:
ε_k^' (ε_k^'' ω)=ε_0k-τ_k ε_k^'' ω
ε_k^' ((ε_k^'')/ω)=ε_∞k+1/τ_k (ε_k^'')/ω
where ε_∞ – is the high-frequency dielectric permittivity, ε_0 - is the low-frequency dielectric permittivity, τ – is the relaxation time, the symbol ∥ or ⊥is used instead of k, depending on the component under consideration. The experimental data were approximated using the Debye and Cole–Cole equations. Based on the experimental data, dependencies ε_k^' (ε_k^'' ω) and ε_k^' ((ε_k^'')/ω) were plotted, and the values of ε_(0⊥), ε_(0∥), and the relaxation times τ_(0⊥) and τ_(0∥) were determined.
