Study of optical parameters of two fluorinated isothiocyanato nematic liquid crystals exhibiting high birefringence

• Autorzy: Devi T. K. , Choudhury B. , Bhattacharjee A. , Dabrowski R.

Identyfikatory

DOI

10.2478/s11772-014-0171-5

• Języki publikacji: EN

Abstrakty

EN

Optical studies have been carried out on two fluorinated isothiocyanato nematic liquid crystal (LC) compounds 4'-butylcyclohexyl-3, 5-difluoro-4-isothiocyanatobiphenyl and 4'-pentylcyclohexyl-3, 5-difluoro-4- isothiocynatobiphenyl. Transition temperatures of the two samples were confirmed using a polarizing microscope. The two LC compounds were found to exhibit fairly high clearing temperatures. Measurements of refractive indices of the two compounds were done by using thin prism method with He-Ne laser beam of wavelength 630 nm. Birefringence of the two LC compounds was calculated from the measured refractive indices. Both the compounds are found to display fairly high values of birefringence. Validation of a modified four-parameter model, based on Vuks equation describing the temperature dependence of refractive indices of the two liquid crystals, is also presented in this paper. The model is validated by fitting the experimentally measured values of refractive indices, birefringence and average refractive indices of the two nematic LCs with the theoretical values. In this paper, the calculation of order parameters of the LCs is presented by using two methods: direct extrapolation method based solely on the birefringence data and by using modified Vuks method based on Haller’s extrapolation. As observed from the obtained results, this procedure of calculating order parameter gives very reasonable results.

Słowa kluczowe

EN

fluorinated isothiocyanato nematic liquid crystals; Vuks equation; refractive index; birefringence; order parameter

• Wydawca: Stowarzyszenie Elektryków Polskich ; Polska Akademia Nauk ; Wojskowa Akademia Techniczna im. Jarosława Dąbrowskiego
• Czasopismo: Opto-Electronics Review
• Rocznik: 2014
• Tom: Vol. 22, No. 1
• Strony: 24--30
• Opis fizyczny: Bibliogr. 31 poz., wykr.

Twórcy

autor

Devi T. K.

• Department of Physics, NIT Silchar, Assam - 788010, India

autor

Choudhury B.

• Institute of Chemistry, Military University of Technology, 2 Kaliskiego Str., 00–908 Warsaw, Poland

autor

Bhattacharjee A.

• Department of Physics, NIT Silchar, Assam - 788010, India

autor

Dabrowski R.

• Institute of Chemistry, Military University of Technology, 2 Kaliskiego Str., 00–908 Warsaw, Poland

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