Observation of a plastic crystalline phase in solid MBBA

Abstract

Wideline and high resolution NMR studies have been carried out in MBBA in its isotropic, nematic and solid phases. Isotropie and nematic spectra correspond to what has been reported earlier. In the solid phase, contrary to expectations, very intense narrow signals similar to signals of the isotropic phase have been observed for the first time at temperatures close to the solid ↔ nematic phase transition temperature. This indicates rapid reorientational or translational motion in the system. X-ray results however confirm the existence of translational order. The results are interpreted as indicative of the existence of a plastic crystalline phase in MBBA.