Narzędzia help

Preferencje help
Widoczny [Schowaj] Abstrakt
Liczba wyników
first previous next last
cannonical link button

http://yadda.icm.edu.pl:80/baztech/element/bwmeta1.element.baztech-article-BWA0-0051-0062

Czasopismo

Opto - Electronics Review

Tytuł artykułu

Dielectric spectroscopy of liquid crystals : electrodes resistivity and connecting wires inductance influence on dielectric measurements

Autorzy Perkowski, P. 
Treść / Zawartość http://www.wat.edu.pl/review/optor/contents.htm http://journals.pan.pl/dlibra/journal/opelre
Warianty tytułu
Języki publikacji EN
Abstrakty
EN Dielectric spectroscopy is a very useful experimental method for liquid crystal investigation. Electrodes made from indium tin oxide (ITO) or gold are widely used in measuring cells. During the dielectric spectroscopy measurements performed for smectic liquid crystalline mixture it was found that detection of some important relaxation modes in paraelectric SmA*, ferroelectric SmC* and antiferroelectric SmCA* phases for frequencies higher than 0.2–0.5 MHz is not possible. The measuring setup does not allow us to measure such relaxations due to its own dielectric response covering the dielectric response of liquid crystalline medium. One can observe the spurious contribution for high frequency part of the dielectric spectrum, due to non-zero resistivity of electrode material or non-zero inductivity of connecting wires. In this paper, the new model was introduced. Its final equations show how to calculate parameters of relaxations observed in liquid crystals, from dielectric response of the empty and filled measuring cell. The experimental proof of strong influence of measuring setup properties on effective (measured) values of dielectric permittivities was shown.
Słowa kluczowe
EN dielectric relaxation   dielectric spectroscopy   cut-off frequency   resonance frequency   liquid crystal  
Wydawca Stowarzyszenie Elektryków Polskich
Polska Akademia Nauk
Wojskowa Akademia Techniczna im. Jarosława Dąbrowskiego
Czasopismo Opto - Electronics Review
Rocznik 2012
Tom Vol. 20, No. 1
Strony 79--86
Opis fizyczny Bibliogr. 19 poz., wykr.
Twórcy
autor Perkowski, P.
  • Institute of Applied Physics, Military University of Technology, 2 Kaliskiego Str., 00-908 Warsaw, Poland, pperkowski@wat.edu.pl
Bibliografia
1. P. Perkowski, D. Łada, K. Ogrodnik, J. Rutkowska, W. Piecek, and Z. Raszewski, “Technical aspects of dielectric spectroscopy measurements of liquid crystals”, Opto−Electron. Rev. 16, 271–276 (2008).
2. M. Gu, Y. Yin, S.V. Shiyanovskii, and O.D. Lavrentovich, “Effects of dielectric relaxation on the director dynamics of uniaxial nematic liquid crystals”, Phys. Rev. E76, 061702 (2007).
3. M. Gupta, R. Dhar, V.K. Agrawal, R. Dąbrowski, and M. Tykarska, “Dielectric spectroscopy of a binary mixture of liquid crystals showing wide temperature range twisted grain boundary phase with re−entrant cholesteric phase”, Phys. Rev. E72, 021703 (2005).
4. D.M. Potukuchi, A.K. George, C. Carboni, S.H. Al−Harthi, and J. Naciri, “Low frequency dielectric relaxation, spontaneous polarization, optical tilt angle and response time investigations in a fluorinated ferroelectric liquid crystal, N125F2 (R*)”, Ferroelectrics 300, 79–93 (2004).
5. M. Wojciechowski, G.W. Bąk, and M. Tykarska, “Dielectric properties of LC mixture with induced antiferroelectric phase”, Opto−Electron. Rev. 16, 257–261 (2008).
6. R. Dhar, “An impedance model to improve the higher frequency limit of electrical measurements on the capacitor cell made from electrodes of finite resistances”, Indian J. Pure Ap. Phy. 42, 56–61 (2004).
7. M. Buivydas, F. Gouda, G. Andersson, S.T. Lagerwall, B. Stebler, J. Bömelburg, G. Heppke, and B. Gestblom, “Collective and non−collective excitations in antiferroelectric and ferrielectric liquid crystals studied by dielectric relaxation spectroscopy and electro−optic measurements”, Liq. Cryst. 23, 723–739 (1997).
8. A.K. Thakur, D.K. Sharma, S.P. Singh, S.S. Bawa, and A.M. Birdar, “Dielectric relaxation near the transition temperature of Sm C*−Sm A phase in electroclinic liquid crystal”, Ferroelectrics 289, 63–75 (2003).
9. P. Salamon, N. Éber, Á. Buka, J.T. Gleeson, S. Sprunt, and A. Jakli, “Dielectric properties of mixtures of a bent−core and a calamitic liquid crystal”, Phys. Rev. E81, 031711 (2010).
10. P. Perkowski, “Dielectric spectroscopy of liquid crystals. Theoretical model of ITO electrodes influence on dielectric measurements”, Opto−Electron. Rev. 17, 180–186 (2009).
11. P. Perkowski, “How to determine parameters of soft mode from dielectric spectroscopy performed in ITO cells?”, Opto−Electron. Rev. 19, 76–82 (2011).
12. P. Perkowski, “Numerical elimination methods of ITO cell contribution to dielectric spectra of ferroelectric liquid crystals”, Opto−Electron. Rev. 19, 176–182 (2011).
13. P. Perkowski, “How to determine the limits of using Afn function for extraction of ITO cell contribution to dielectric spectra?”, Phase Transit. 83, 836–843 (2010).
14. C.J.F. Bötcher and P. Bordewijk, Theory of Electric Polarization, Elsevier, 1978.
15. Relaxation Phenomena, edited by W. Haase and S. Wróbel Springer, 2003.
16. S.T. Lagerwall, Ferroelectric and Antiferroelectric Liquid Crystals, Wiley−VCH, 1999.
17. K.S. Cole and R.H. Cole, “Dispersion and absorption in dielectrics. Alternating current characteristics”, J. Chem. Phys. 9, 341–351 (1941).
18. D.W. Davidson and R.H. Cole, “Dielectric relaxation in glycerine”, J. Chem. Phys. 18, 1417–1417 (1950); D.W. Davidson and R.H. Cole, “Dielectric relaxation in glycerol, propylene glycol, and n−Propanol” J. Chem. Phys. 19, 1484–1491 (1951).
19. S. Havriliak and S. Negami, “A complex plane representation of dielectric and mechanical relaxation processes in some polymers”, Polymer 8, 161–210 (1967).
Kolekcja BazTech
Identyfikator YADDA bwmeta1.element.baztech-article-BWA0-0051-0062
Identyfikatory