Dynamics of the Flexoelectric Effect

The dynamics of the flexoelectric effect have not been thoroughly studied as yet. Reference [188] investigated the frequency spectrum of the helium- 

Reference [189] examined theoretically the behavior of a nematic layer (with a geometry similar to Fig. 4.29(c)) in an alternating field with allowance for the flexoelectric eflFect. Euler s equation for the volume of a sample (see (4.29)) is written in the hnearized form (sin 0 0, cos 0 1) 

Here corresponds to different anchoring energies at the two opposing surfaces i = 1,2) which have coordinates of d/2 d is the thickness of the layer). Prom (4.76) it is evident that the flexoelectric effect creates mechanical stress on the surfaces of the sample. 

Due to the above-mentioned results [188, 189] the flexoelectric response is considerable in a narrow frequency region limited by the frequency of the structural relaxation fs / d where K is the average elastic co- 

FIGURE 4.33. Calculation of the flexoelectric coefficients for (a) pear-shaped molecules (b) banana-shaped molecules and (c) the quadrupole model of the flexoelectric effect [200]. 

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The dynamics of the flexoelectric effect have been studied [97, 98]. For a nematic layer with a geometry similar to that shown in Fig. 12c and finite dielectric anisotropy, the torque belance equation for the bulk of a sample, written in the linearized form (sin0=0, cos0 l)... 

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