Double hydrogen bonded ferroelectric liquid crystals: A study of field induced transition (FiT) |
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| Authors: | VN Vijayakumar MLN Madhu Mohan |
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| Institution: | 1. Department of Physics, Condensed Matter Research Laboratory (CMRL), Bannari Amman Institute of Technology, Sathyamangalam 638 401, India;2. Department of Chemistry, Bannari Amman Institute of Technology, Sathyamangalam 638 401, India;3. Post Graduate and Research Department of Chemistry, Sri Ramakrishna Mission Vidyalaya, College of Arts and Science, Coimbatore 641 020, India;4. Department of Physics, Erode Sengunthar Engineering College, Perundurai 638 057, India;1. Department of Physics, Government Arts College for Women, (Autonomous), Pudukkottai-622 001, Tamil Nadu, India;2. Nanotechnology & Catalysis Research Centre, University of Malaya, Kuala Lumpur 50603, Malaysia;1. Department of Physics, Arasu Engineering College, Kumbakonam 612 501, India;2. PG and Research, Department of Physics, Government Arts College (Autonomous) (Affiliated to Bharathidasan University, Tiruchirapalli), Kumbakonam 612 001, India |
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| Abstract: | A novel series of chiral hydrogen bonded liquid crystals have been isolated. Hydrogen bond was formed between chiral nonmesogen ingredient levo tartaric acid and mesogenic p-n-alkoxybenzoic acids. Phase diagram was constructed from the transition temperatures obtained by DSC and polarizing optical microscopic (POM) studies. Thermal and electrical properties exhibited by three complexes namely LTA+8BA, LTA+7BA and LTA+5BA were discussed. Salient feature of the present work was the observation of a reentrant smectic ordering in LTA+8BA complex designated as Cr1 phase. This reentrant phenomenon was confirmed by DSC thermograms, optical textures of POM and temperature variation of capacitance and dielectric loss studies. Tilt angle was measured in smectic C1 and reentrant smectic Cr1 phases. Another interesting feature of the present investigation was the observation of a field induced transition (FiT) in the LTA+nBA homologous series. Three threshold field values were noticed which give rise to two new phases (E1 and E2) induced by electric field and on further enhancement of the applied field the mesogen behaves like an optical shutter. FiT is reversible in the sense that when applied field is removed the original texture was restored. |
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