Tilted smectic layers of a SmC* liquid crystal between homeotropically treated plates

We investigated SmC* films sandwiched between silane coated glass prates an d observed formation of textures exhibiting a uniform tilt of the smectic l ayers with respect to the boundary prates. The layer tilt angle increases f rom zero to 14 degrees as the sample is cooled from the smectic A phase to room temperature. These films show linear electro-optical effects because t he permanent polarization can be aligned so that it has a component paralle l to the applied field without changing the layer structure. Our analysis i ndicates that mainly two effects determine the layer tilt. On the one hand, the surface tension tends to minimise the layer tilt. On the other hand, t he surface energy promotes the director to be normal to the boundary plates .