A general symmetry argument is presented, and experiments on newly synthesized p-decyloxybenzylidene p'-amino 2-methyl butyl cinnamate are described, demonstrating that chiral smectic C and H liquid crystals are ferroelectric. Some of the properties of this new class of ferro-electrics are discussed

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Optical birefringence and temperature range of the biaxial nematic phase in a lyotropic liquid crystal High-resolution x-ray measurements have been performed at the synchrotron of LURE (Orsay) to study both uniaxial (discotic and calami tic ) and biaxial nematic lyomesophases of the mixture K-laurate, I-decanol, and 0 2 0. The variations of the densitometric profiles of the diffracted bands are analyzed vs temperature. They are shown to be consistent with the model of similar micellar aggregates in the three nematic phases, undergoing different orientational fluctuations. It is moreover discussed that the micelles have, on the average, the shape of biaxial platelets with a (1/2/3) anisotropy, and that they build the same pseudolamellar structure in each nematic phase.