Field-induced transitions between antiferroelectric and ferrielectric phases

We have recently reported a new 3-layer field-induced ferrielectric (SmC*Fi1_2) phase, which can be accessed either from the usual ferrielectric 3-layer (SmC*Fi1) phase or as a two-stage process initially from the 4-layer (SmC*Fi2) phase. Simple analytical models can predict the threshold fields for the field-induced transitions from: (i) 4-layer to synclinic (SmC*); (ii) 4- to SmC*Fi1; (iii) SmC*Fi1 to 3 SmC*Fi1_2; and (iv)SmC*Fi1_2 to SmC*. Each of these thresholds is defined by equations involving the interlayer interaction strengths. We deduce the resulting field-temperature phase diagrams and show their agreement with experimental data.