Journal Article

PUBDB-2020-04473

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Effect of fluorinated achiral chain length on structural, dielectric and electro-optic properties of two terphenyl based antiferroelectric liquid crystals

Dey, K. C.Extern* ; Mandal, P. K. (Corresponding author)Extern* ; Kula, P.

2020
Elsevier New York, NY [u.a.]

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Please use a persistent id in citations: doi:10.1016/j.molliq.2019.112056

Report No.: I-20170021

Abstract: Two antiferroelectric liquid crystals of different fluorinated chain length have been studied. Although both exhibit antiferroelectric (SmC$_A$*), ferroelectric (SmC*) and paraelectric (SmA*) phases, melting point decreases with increasing achiral chain length but clearing point shows opposite trend. Thermal ranges of SmC$_A$* and SmC* phases exhibit odd-even effect like the dipole moments and spontaneous polarization. Layer spacings, average intermolecular distances and correlation lengths across the smectic planes also increase with chain length. Temperature dependence of layer spacings, x-ray tilt, optical tilt and spontaneous polarization suggest tricritical nature of SmC*–SmA* transition. Dielectric increments decrease with increased achiral chain. Both soft mode and Goldstone mode critical frequencies decrease with decreasing temperature in the lower derivative but opposite behaviour is observed in the higher derivative. Both the compounds show Curie–Weiss behaviour in soft mode near SmC*–SmA* transition temperature (T$_c$). Goldstone mode critical frequency is much higher in the higher derivative. Both in-phase and anti-phase antiferroelectric modes are observed in SmC$_A$* phase in the higher derivative but in the lower derivative only anti-phase antiferroelectric mode is observed. Optical tilts suggest orthoconic nature of the SmC$_A$* phase of both the compounds. Ferroelectric- antiferroelectric transition temperature decreases with increasing ac field in both compounds.

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Contributing Institute(s):

1. DOOR-User (DOOR ; HAS-User)

Research Program(s):

1. 6G3 - PETRA III (POF3-622) (POF3-622)
2. FS-Proposal: I-20170021 (I-20170021) (I-20170021)
3. INDIA-DESY - INDIA-DESY Collaboration (2020_Join2-INDIA-DESY) (2020_Join2-INDIA-DESY)

Experiment(s):

1. PETRA Beamline P07 (PETRA III)

Appears in the scientific report 2020

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Database coverage:
; Clarivate Analytics Master Journal List ; Current Contents - Physical, Chemical and Earth Sciences ; Ebsco Academic Search ; Essential Science Indicators ; IF < 5 ; JCR ; Nationallizenz ; SCOPUS ; Science Citation Index Expanded ; Web of Science Core Collection

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