First observation of aS C * -S A-TGBA multicritical point in a pure compound

Abstract

High pressure experiments have been performed by thermobarometric analysis on two homologous (n=10 and 11) of the [3-fluoro-4((R) or (S)-methylheptyloxy) 4′-(4″-alkoxy-3″-fluorobenzoyloxy) tolans series, which both exhibit the TΓBA phase. The character (first or/and second order) of the transitions involving the TGBA phase are determined from thermobarograms. The pressure-temperature phase diagrams show that the TGBA phase is stabilized under high pressure for the two compounds. Forn=11 an inducedS A phase is observed under high pressures leading to the first experimental observation, on pressure-temperature phase diagram of pure compounds, of aS C * -S A-TGBA multicritical point, previously predicted by the Renn-Lubensky theory.