Dielectric studies of dispersions of carbon nanotubes in liquid crystal 5CB
The frequency dependences of the imaginary ε″ and real ε′ parts of complex dielectric permittivity inherent to planarly aligned layers of nematic liquid crystals 5CB doped with multiwalled carbon nanotubes (CNT) were investigated in a wide range of frequencies (f = 10⁻²-10⁶ Hz) and CNT concentr...
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| Дата: | 2008 |
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| Автори: | , , |
| Формат: | Стаття |
| Мова: | English |
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Інститут фізики напівпровідників імені В.Є. Лашкарьова НАН України
2008
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| Назва видання: | Semiconductor Physics Quantum Electronics & Optoelectronics |
| Онлайн доступ: | http://dspace.nbuv.gov.ua/handle/123456789/119076 |
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| Назва журналу: | Digital Library of Periodicals of National Academy of Sciences of Ukraine |
| Цитувати: | Dielectric studies of dispersions of carbon nanotubes in liquid crystal 5CB / A. Koval'chuk, L. Dolgov, O. Yaroshchuk // Semiconductor Physics Quantum Electronics & Optoelectronics. — 2008. — Т. 11, № 4. — С. 337-341. — Бібліогр.: 21 назв. — англ. |
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Digital Library of Periodicals of National Academy of Sciences of Ukraine| id |
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irk-123456789-1190762017-06-04T03:03:57Z Dielectric studies of dispersions of carbon nanotubes in liquid crystal 5CB Koval'chuk, A. Dolgov, L. Yaroshchuk, O. The frequency dependences of the imaginary ε″ and real ε′ parts of complex dielectric permittivity inherent to planarly aligned layers of nematic liquid crystals 5CB doped with multiwalled carbon nanotubes (CNT) were investigated in a wide range of frequencies (f = 10⁻²-10⁶ Hz) and CNT concentrations (c = 0-0.25 wt.%). It has been shown that the studied frequency range can be divided in three parts according to behavior of ε′ (f) and ε″ (f) curves. The low-frequency range (10⁻² < f < 10¹ Hz) reflects the near-electrode processes in the cell. The ratio ε″/ε′ used to characterize these processes sharply grows if the concentration of CNT exceeds 0.05 wt.%. The moderate frequency range (10¹ < f < 10⁵ Hz) corresponds to the alternating current conductivity, σАС. At the nanotubes concentration less than 0.025 wt.%, σАС does not depend on the frequency that implies its ionic origin. In its turn, at the c ≥ 0.025 wt.%, σАС is a power function of the frequency that is typical for electronic hopping mechanism. The transition from the ionic to electronic conductivity can be explained by the percolation theory with the critical concentration of nanotubes 0.031 wt.% and percolation parameter 2.5. The high-frequency range (10⁵ < f < 10⁶ ) is mainly attributed to dipole volume polarization. For c < 0.05 wt.% such polarization is well described by the Debye equation. The time of dielectric relaxation in this frequency range increases with nanotubes content. This is explained by effective interaction of nanotubes with 5CB molecules. 2008 Article Dielectric studies of dispersions of carbon nanotubes in liquid crystal 5CB / A. Koval'chuk, L. Dolgov, O. Yaroshchuk // Semiconductor Physics Quantum Electronics & Optoelectronics. — 2008. — Т. 11, № 4. — С. 337-341. — Бібліогр.: 21 назв. — англ. 1560-8034 PACS 77.22.Ch, 77.84.Nh, 78.67.Ch http://dspace.nbuv.gov.ua/handle/123456789/119076 en Semiconductor Physics Quantum Electronics & Optoelectronics Інститут фізики напівпровідників імені В.Є. Лашкарьова НАН України |
| institution |
Digital Library of Periodicals of National Academy of Sciences of Ukraine |
| collection |
DSpace DC |
| language |
English |
| description |
The frequency dependences of the imaginary ε″ and real ε′ parts of complex
dielectric permittivity inherent to planarly aligned layers of nematic liquid crystals 5CB
doped with multiwalled carbon nanotubes (CNT) were investigated in a wide range of
frequencies (f = 10⁻²-10⁶
Hz) and CNT concentrations (c = 0-0.25 wt.%). It has been
shown that the studied frequency range can be divided in three parts according to
behavior of ε′ (f) and ε″ (f) curves. The low-frequency range (10⁻² < f < 10¹ Hz) reflects
the near-electrode processes in the cell. The ratio ε″/ε′ used to characterize these
processes sharply grows if the concentration of CNT exceeds 0.05 wt.%. The moderate
frequency range (10¹ < f < 10⁵
Hz) corresponds to the alternating current conductivity,
σАС. At the nanotubes concentration less than 0.025 wt.%, σАС does not depend on the
frequency that implies its ionic origin. In its turn, at the c ≥ 0.025 wt.%, σАС is a power
function of the frequency that is typical for electronic hopping mechanism. The transition
from the ionic to electronic conductivity can be explained by the percolation theory with
the critical concentration of nanotubes 0.031 wt.% and percolation parameter 2.5. The
high-frequency range (10⁵ < f < 10⁶
) is mainly attributed to dipole volume polarization.
For c < 0.05 wt.% such polarization is well described by the Debye equation. The time of
dielectric relaxation in this frequency range increases with nanotubes content. This is
explained by effective interaction of nanotubes with 5CB molecules. |
| format |
Article |
| author |
Koval'chuk, A. Dolgov, L. Yaroshchuk, O. |
| spellingShingle |
Koval'chuk, A. Dolgov, L. Yaroshchuk, O. Dielectric studies of dispersions of carbon nanotubes in liquid crystal 5CB Semiconductor Physics Quantum Electronics & Optoelectronics |
| author_facet |
Koval'chuk, A. Dolgov, L. Yaroshchuk, O. |
| author_sort |
Koval'chuk, A. |
| title |
Dielectric studies of dispersions of carbon nanotubes in liquid crystal 5CB |
| title_short |
Dielectric studies of dispersions of carbon nanotubes in liquid crystal 5CB |
| title_full |
Dielectric studies of dispersions of carbon nanotubes in liquid crystal 5CB |
| title_fullStr |
Dielectric studies of dispersions of carbon nanotubes in liquid crystal 5CB |
| title_full_unstemmed |
Dielectric studies of dispersions of carbon nanotubes in liquid crystal 5CB |
| title_sort |
dielectric studies of dispersions of carbon nanotubes in liquid crystal 5cb |
| publisher |
Інститут фізики напівпровідників імені В.Є. Лашкарьова НАН України |
| publishDate |
2008 |
| url |
http://dspace.nbuv.gov.ua/handle/123456789/119076 |
| citation_txt |
Dielectric studies of dispersions of carbon nanotubes in liquid crystal 5CB / A. Koval'chuk, L. Dolgov, O. Yaroshchuk // Semiconductor Physics Quantum Electronics & Optoelectronics. — 2008. — Т. 11, № 4. — С. 337-341. — Бібліогр.: 21 назв. — англ. |
| series |
Semiconductor Physics Quantum Electronics & Optoelectronics |
| work_keys_str_mv |
AT kovalchuka dielectricstudiesofdispersionsofcarbonnanotubesinliquidcrystal5cb AT dolgovl dielectricstudiesofdispersionsofcarbonnanotubesinliquidcrystal5cb AT yaroshchuko dielectricstudiesofdispersionsofcarbonnanotubesinliquidcrystal5cb |
| first_indexed |
2023-10-18T20:33:42Z |
| last_indexed |
2023-10-18T20:33:42Z |
| _version_ |
1796150522048151552 |