Multiple Ferroic Orderings in Lead-Free Hybrid Material Induced by Molecular Asymmetric Modification

The characteristics of multiple ferroic orderings can
afford potential
applications such as mechanical switches, energy conversion, and pressure
sensors. However, it remains a tremendous challenge to achieve multiple
ferroic orderings due to rigorous requirements for certain symmetry
in the crystal lattice and symmetry breaking. The organic–inorganic
halide material has been regarded as possessing great potential for
ferroelectric and ferroelastic phase transition for its unique structures.
Herein, by modifying molecular symmetries, we successfully obtained
the lead-free hybrid halide material (AMP)2SbBr5 (AMP = 2-Amino-2-methyl-1-propanol). With the help of hydroxyl insertion,
the mirror symmetry was broken, realizing ferroelectric and ferroelastic
phase transitions. The lone-pair electron activity as well as the
directional ordering of the organic cations triggered the saturated
polarization of 11.28 μC cm–2, which is the
largest polarization ever found in antimony-based molecular ferroelectrics.
This study enhanced lead-free molecular ferroelectric development
and offers instructive inspiration for designing multiple ferroic
orderings.