General phase diagram for antiferroelectric liquid crystals in dependence on enantiomeric excess

The phase diagram of the prototype antiferroelectric liquid crystal MHPOBC in dependence of enantiomeric excess was measured. It was shown that the SmCbeta phase in very pure samples is the SmCFI2 phase with a four layer structure, and only after small racemization it transforms into the ferroelectric SmC phase. The phase diagram was theoretically explained by taking into account longer range bilinear and short range biquadratic interlayer interactions, that lead to the distorted clock structures and first order transitions between them.