Competition between ferroelectric and antiferroelectric interactions stabilizing varieties of phases in binary mixtures of smectic liquid crystals

An electric field-temperature ( E-T ) phase diagram has been drawn for several binary mixtures of antiferroelectric liquid crystals using conoscopic observation. All the possible phases are SmA-SmC α * -SmC * -new antiferroelectric phase-new ferrielectric phase-SmC γ * -new ferrielectric phase-SmC A * , some of which appear in the above regular order. Two Devil's staircases are necessary to elucidate systematic understanding of successive phase transitions among ferroelectric, ferrielectric and antiferroelectric phases: one is a staircase of SmC α * ( q T ) already discussed by Takanishi et al . and the other is a staircase of SmC A * ( q T ). Competition between an antiferroelectric interaction responsible for SmC A * and a ferroelectric one for SmC * is considered to stabilize a variety of phases, SmC A * ( q T ).