We report experimental results on two bent-shaped mesogens showing the $B_1$ phase. Contrary to the conventional $B_1$ structures, we have found that our compounds display a clear electro-optic effect in this phase. Under the influence of a 100-Hz square-wave electric field of moderate amplitude, an increase of the birefringence is observed. However, no switching current is detected, indicating that the materials remain antiferroelectric. For high enough fields, a drastic change in the texture occurs. This change is a phase transition to a $B_2$ phase, and shows the typical antiferroelectric switching of this phase. The induced $B_2$ phase has been identified to be homochiral. Upon removal of the field, the $B_1$ structure is recovered. Our study is based on differential scanning calorimetry, x-ray, electro-optics, polarization reversal, and dielectric measurements.

• Received 23 July 2003

DOI:https://doi.org/10.1103/PhysRevE.69.011703