In this work we perform a theoretical calculation in order to reconstitute the （E-T） phase diagram of a chiral smectic liquid crystal in the vicinity of the SmA-SmCα＊ transition. This reconstruction is carried out...In this work we perform a theoretical calculation in order to reconstitute the （E-T） phase diagram of a chiral smectic liquid crystal in the vicinity of the SmA-SmCα＊ transition. This reconstruction is carried out on the basis of a thermo-dynamic calculation of the slope of the curve joining the SmC＊ domain and the unwound SmC＊. An empiric correction of the mean field term of Landau De-Gennes development is necessary to accomplish this reconstruction. Thereafter, an experimental validation is performed to verify our calculations.展开更多
In ferroelectric liquid crystals, phase transitions can be induced by an electric field. The current constant method allows these transition to be quickly localized and thus the（E, T） phase diagram of the studied pr...In ferroelectric liquid crystals, phase transitions can be induced by an electric field. The current constant method allows these transition to be quickly localized and thus the（E, T） phase diagram of the studied product can be obtained.In this work, we make a slight modification to the measurement principles based on this method. This modification allows the characteristic parameters of ferroelectric liquid crystal to be quantitatively measured. The use of a current square signal highlights a phenomenon of ferroelectric hysteresis with remnant polarization at null field, which points out an effect of memory in this compound.展开更多
文摘In this work we perform a theoretical calculation in order to reconstitute the （E-T） phase diagram of a chiral smectic liquid crystal in the vicinity of the SmA-SmCα＊ transition. This reconstruction is carried out on the basis of a thermo-dynamic calculation of the slope of the curve joining the SmC＊ domain and the unwound SmC＊. An empiric correction of the mean field term of Landau De-Gennes development is necessary to accomplish this reconstruction. Thereafter, an experimental validation is performed to verify our calculations.
文摘In ferroelectric liquid crystals, phase transitions can be induced by an electric field. The current constant method allows these transition to be quickly localized and thus the（E, T） phase diagram of the studied product can be obtained.In this work, we make a slight modification to the measurement principles based on this method. This modification allows the characteristic parameters of ferroelectric liquid crystal to be quantitatively measured. The use of a current square signal highlights a phenomenon of ferroelectric hysteresis with remnant polarization at null field, which points out an effect of memory in this compound.
