Figure 1

Texture of compound IIIc in the $B2$ phase (for details see Ref. [15]). Texture observed (a) without electric field and (b) under the electric field of about 20 V/$\mu$m under crossed polarizers parallel to the edges of the photo. Photos (c) and (d) show overlapped DC and fan-shaped textures without electric field when one polarizer is turned by $6^{\circ }$ clockwise and anticlockwise from the crossed position. The width of every micrograph is about $150\mu \mathrm{m}$.Reuse & Permissions

Figure 2

Texture of compound Ia in the $B2$ phase before application of an electric field (details about compound in Ref. [15]). The microphotograph can serve as an example of the coexistence of DC structure and a fan-shaped texture. Fine fan-shaped texture having a sharp optical contrast surrounds the DC structure, which is optically isotropic. In DC the domains appear when the polarizers are decrossed by $6^{\circ }$. The width of the micrograph is about $250\mu \mathrm{m}$.Reuse & Permissions

Figure 3

The coordinate system of the bent-shaped molecule, which is situated in the smectic layer with the normal $\vec{N}$ parallel to the $z$ axis. The plane of the molecule (represented by a gray crescent-like object) is defined by director $\vec{n}$ and vector $\vec{p}$ parallel to the molecular polarization. The $\vec{c}$ director is a projection of $\vec{n}$ onto the layer plane $(x,y)$. Eulerian angles are defined using the coordinate system $(x,y,z)$: $\theta$ is the tilt of from the $z$ axis ($\theta$ is the apex angle of a cone, on the surface of which the director $\vec{n}$ is located). Azimuthal angle $\varphi$ describes the rotation of $\vec{n}$ around the $z$ axis transforming the $x$ axis to the $x^{\prime }$ axis and describes rotation $\vec{p}$ around $\vec{n}$ from the $x^{\prime }$ axis.Reuse & Permissions

Figure 4

Schematic drawing of the coexistence of DC and FCD structures in a planar sample. ${\vec{N}}_S$ is the surface normal. In DC structure grains are projected into the plane of drawing, but generally they can be also inclined with respect to that plane. In FCD structure parts of ellipses [projected to the plane of figure as lines (e)] and hyperbolas (h) are shown. In the thickness $d_{\text{FCD}}$ only one FCD occurs, which corresponds to the filling factor $k=1$.Reuse & Permissions

Figure 5

Schematic configurations of field transformed DC structures due to coalescence of DC grains. The thin lines in essentially defect-free regions (prisms) represent the smectic layers. The orientation of the spontaneous polarization ${\vec{P}}_S$ parallel to the smectic layers and to $\vec{E}$ is shown. (a) $\vec{E}$ orients molecular dipoles parallel to the field but does not eliminate relative rotations between prisms due to screw dislocations. (b) and (c) $\vec{E}$ perpendicular to the plane of the figure does not eliminate edge dislocations (depicted by symbol $\perp$) parallel to field direction (shown as $\otimes$). The resulting structure can be formed either (b) by alternatively inclined prisms (for alternate signs of curvatures) or (c) by prisms with one (positive or negative) curvature. The last can lead to creation of FCD structure.Reuse & Permissions