Dielectric investigations on a liquid crystalline compound showing wide ferrielectric and antiferroelectric phases

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Abstract
Dielectric, pyroelectric and calorimetric measurements on the antiferroelectric compound (R) 1-Methylheptyl-4′-(4′-n decyloxybenzoyloxy)-biphenyl-4-carboxylate, denoted as 10B1M7, showing a broad ferrielectric SmCγ* phase have been performed. The investigations of dielectric permittivity and loss were done as functions of frequency, dc biasing field and temperature for the whole mesogenic range in cells with different thicknesses. The dielectric behaviour is compared with the results from DSC measurements, thermal polarizing microscopy and to literature. The determination of spontaneous polarisation by different techniques (hysteresis method, current reversal method, pyroelectric technique) has also been included. A new phase, denoted as SmCx* phase, was found below SmCγ*phase.In the higher ordered phases below the SmCA* phase a very strong activated process has been observed which is not described up to now.
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