Transition between two orthogonal polar phases in symmetric bent-core liquid crystals

A unique phase transition between a uniaxial orthogonal phase with random polar order SmAPR and orthogonal antiferroelectric phase SmAPA is found in a series of symmetric achiral bent-core liquid crystals. The phase transition is weakly first order or continuous. The X-ray diffraction, electro-optical, optical second harmonic generation and dielectric methods, confirmed that the phase transition occurs from a locally polar ordered phase to a macroscopically antiferroelectrically ordered phase.