Ferroelectric transition of a chiral molecular crystal BINOL2DMSO

TL;DR

This study investigates the phase transitions in the chiral molecular crystal BINOL2DMSO, revealing ferroelectric behavior and structural changes at specific temperatures through various experimental techniques.

Contribution

It provides new insights into the ferroelectric transition and structural deformation of BINOL2DMSO, a chiral molecular crystal, with detailed phase transition characterization.

Findings

Two phase transitions at 190 K and 125 K.

Ferroelectricity associated with the first transition.

Structural change from tetragonal to monoclinic.

Abstract

We report dielectric, thermodynamical, acoustic, and optical properties of a chiral molecular crystal, 1,1'-bi-2-naphthol 2-dimethylsulfoxide (BINOL2DMSO). We find two successive phase transitions at Tc1=190 K and Tc2=125 K. The first transition at Tc1 is characterized by an order-disorder transition of the guest molecules DMSO along with ferroelectricity. At the second transition of Tc2, the crystal structure deforms from tetragonal to monoclinic, leading to domain formation. Low-temperature x-ray diffraction suggests that the space group changes from P4_12_12 (P4_32_12) to P4_1 (P4_3) at Tc1, and down to P112_1 at Tc2.