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NTRODUCTION

LIQUID crystals are widely used in many applications such as memory devices, displays, and optical related applications. The prerequisite conditions for any liquid crystal to be commercially used are high magnitudes of spontaneous polarization, optimum response times, and wide ferroelectric thermal range. Around the globe, many research groups[1–6] are engaged in designing novel molecular structure and synthesizing new series of chiral liquid crystals that caters to the commercial applicability. Based on our previous work on different types of ferroelectric mesogens,[7–11] design and characterization of liquid crystal, dodecyl{4-(3-(4hippuratoxy phenyl)–2–choloro-1-oxy-propanyl) benzoate, which exhibits high spontaneous polarization and optimum response times with reasonable ferroelectric thermal range, are carried out. The properties of this newly synthesized liquid crystal are characterized for the first time and the results are discussed in the present work. II.

EXPERIMENTAL

Measurements of the compound are made with the help of polyamide coated buffed cells with 5-lm gap (Instec Inc., Boulder, CO). The cells are filled by capillary action, with dodecyl{4-(3-(4-hippuratoxy phenyl)–2–choloro-1-oxy-propanyl) benzoate in its isotropic state. The sample temperature is controlled

M.L.N. MADHU MOHAN, B. ARUNACHALAM, and C.R. ARAVINDH SANKAR are with the Liquid Crystal Research Laboratory, Bannari Amman Institute of Technology, Sathyamangalam, India 638 401. Contact e-mail: [email protected] Manuscript submitted March 4, 2007. Article published online March 13, 2008 1192—VOLUME 39A, MAY 2008

to ±0.1 °C and monitored by a temperature controller. The temperature controller with the cell is placed on the hot stage of a polarizing microscope (Nikon E600 POL, Tokyo, Japan) for visual observation. Simultaneous onset of the ferroelectric phase along with polarizing switching is observed, and the corresponding textures are recorded by digital camera (Nikon DS-U1, Tokyo, Japan), and (ACT-2U) is used to capture and analyze the recorded textures. Temperature variation of the tilt angle is evaluated using the optical extinction method.[12] Spontaneous polarization measurements are carried out by the field reversal method;[13] the corresponding current polarization profile is digitized using a digital storage oscilloscope (Yokogawa DL1520, Tokyo, Japan) and recorded in a computer via the HPIB module (NI 763507, Bangalore, India). Storage retrieval and analysis of these data are done[14] using the LabVIEW software tool. The variation of capacitance is measured with the aid of Aplab-4910 (Thane, India) at 1 KHz.

III.

RESULTS AND DISCUSSION

A. Polarizing Microscopic Studies The phase variants and their transition temperatures were determined from the characteristic textural observations[15] under a polarized microscope. The ferroelectric liquid crystal dodecyl{4-(3-(4-hippuratoxy phenyl)– 2–choloro-1-oxy-propanyl) benzoate exhibited focal conic fan texture in smectic-A phase, while the smectic C* phase is identified as fo