Temperature dependence of dielectric properties of the liquid crystal 6CB with the embedded Ag₇GeS₅I nanoparticles

• Опубліковано в: : Semiconductor Physics Quantum Electronics & Optoelectronics
• Дата: 2020
• Автори: Poberezhets, S.I., Kovalchuk, O.V., Studenyak, I.P., Kovalchuk, T.M., Poberezhets, I.I., Lacková, V., Timko, M., Kopčanský, P.
• Формат: Стаття
• Мова: Англійська
• Опубліковано: Інститут фізики напівпровідників імені В.Є. Лашкарьова НАН України 2020
• Теми: Semiconductor Physics
• Онлайн доступ: https://nasplib.isofts.kiev.ua/handle/123456789/215720
• Назва журналу: Digital Library of Periodicals of National Academy of Sciences of Ukraine
• Цитувати: Temperature dependence of dielectric properties of the liquid crystal 6CB with the embedded Ag₇GeS₅I nanoparticles / S.I. Poberezhets, O.V. Kovalchuk, I.P. Studenyak, T.M. Kovalchuk, I.I. Poberezhets, V. Lackova, M. Timko, P. Kopcansky // Semiconductor Physics Quantum Electronics & Optoelectronics. — 2020. — Т. 23, № 2. — С. 129-135. — Бібліогр.: 18 назв. — англ.

Within the frequency range 10⁻¹–10⁵ Hz under the temperatures 293–295 K, the dielectric properties of a planar-oriented nematic liquid crystal 6CB with the embedded of 0.1% superionic conductor Ag₇GeS₅I nanoparticles have been investigated. It has been shown that for the whole temperature range, the obtained frequency dependences of the components ε' and ε" composing the complex dielectric function can be separated into 3 sections. The dispersion of ε' and ε" for the lowest frequencies (less than 10² Hz) is described by the Debye equation and is caused by the rotation of the dipole moments of LC molecules under the action of electric field within the angles corresponding to the fluctuations of the order parameter in a thin near-electrode layer. It has been shown that the temperature dependence of the value of inverse relaxation time for such a process is described by straight lines in the Arrhenius coordinates within each mesophase. The activation energies for these dependences have been estimated for each mesophase. It should be noted that within the middle range of frequencies (10²–10⁴ Hz), for each temperature, one can separate a section where the magnitude of the conductivity does not depend on the frequency. The conductivity in these sections is equal to the conductivity of LC with the nanoparticles. It has been found that both the value of inverse relaxation time and the value of conductivity change according to the Arrhenius law with temperature. The activation energies for the temperature dependence of conductivity and the temperature dependence of inverse relaxation time have been estimated, and it has been shown that they are close (for the nematic phase) and equal (for the isotropic phase). In the highest frequency section of the dielectric spectrum (10⁴–10⁵ Hz), the conductivity of the mixture 6CB + 0.1 wt.% Ag₇GeS₅I changes according to the power law of the frequency. It has been suggested that a sharp increase in the conductivity of 6CB with nanoparticles of the superionic conductor Ag₇GeS₅I at a concentration of 0.1 wt.% was caused by the sharp increase in the electronic component of conductivity through Ag₇GeS₅I nanoparticles.