Evidence for the flexo-electric effect in a nematic liquid crystal cell |
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| Authors: | G Barbero P Taverna Valabrega R Bartolino B Valenti |
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| Institution: | 1. Dipartimento di Fisica del Politecnico , C.so Duca degli Abruzzi 24, 10129 , Torino, Italy;2. GNSM, Unità di Cosenza, Dipartimento di Fisica, Università della Calabria, 87030 Arcavacata di Rende (Cosenza) , Italy;3. Dipartimento di Fisica del Politecnico , C.so Duca degli Abruzzi 24, 10129 , Torino, Italy;4. Unical Liquid Crystal Group, Dipartimento di Fisica, Università della Calabria, 87030 Arcavacata di Rende (Cosenza) , Italy;5. Instituto di Chimica Industriale, Università di Genova, C.so Europa 30, 16132 , Genova, Italy |
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| Abstract: | Abstract We present evidence for the flexo-electric effect in a hybrid aligned nematic cell containing 4-methoxybenzylidene-4'-n-butylaniline (MBBA) subject to d.c. excitation, by comparing the theoretical curve derived by including the flexo-electric term in the free energy with the experimental points. The agreement appears to be very good for MBBA doped with a small amount of an additive which shows reversible electrochemical reactions at very low redox potential; this allows us to determine the sum of the flexo-electric coefficients and the anchoring energy on the planar wall. For undoped MBBA the experimental results can be justified only by assuming a low voltage screening of the electric field, due to the presence of ionic impurities in the material. |
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