Effect of annealing on the dielectric parameters of ferroelectric TSiKN65

The ionic conductivity of ferroelectric liquid crystals used for pyroelectric detection is a measure of the noise contribution to the output of the device. This is obtained from a measurement of the dielectric loss of the liquid crystal material. An annealing procedure has been developed that reduces the ionic conductivity and hence the dielectric loss significantly. The procedure consists of subjecting the ferroelectric liquid crystal sample to an electric field in the isotropic phase and cooling it into the smectic phase at a certain rate. After measurement of the dielectric parameters, the sample is reheated into the isotropic phase and then cooled again at a slower rate into the smectic phase. The dielectric measurements are repeated again. The entire process is repeated for successively slower cooling rates. We present the results of the effect of this annealing treatment on the dielectric parameters and explain the origin of this phenomenon.