Ferroelastic Hybrid Bismuth Bromides with Dual Dielectric Switches

Ferroelastics,
as an important member of ferroic materials, play
an invaluable role in energy conversion, information processing, and
mechanical switches. However, to date, it remains an arduous task
to construct molecular ferroelastics with dielectric bistability/switching
characteristics. Within this context, moreover, controlling the multiswitching
behavior in dielectrics has been a great challenge, while imparting
them with other fascinating properties (ferroelasticity and semiconducting
features) is even more laborious. Here, through a molecular modification
strategy, we successfully designed an organic–inorganic hybrid
ferroelastic with a band gap of 2.58 eV, (DMTBA)3Bi2Br9 (DMTBA = N,N-dimethyl-tert-butylaminium), which exhibits dual-dielectric
switching characteristics at 425 and 188 K. These attributes make
it a multifunctional material for multipurpose sensors, mechanical
switches, and photoelectric devices. Compared to other methyl-substituted
products, (N,N-dimethyl-tert-butylaminium)3Bi2Br9 and (N,N,N-trimethyl-tert-butylaminium)3Bi2Br9, proper molecular interactions and dynamics of DMTBA cations should
be responsible for its ferroelasticity with dual dielectric switches.
We expect that this study would throw light on the rational design
of new hybrid ferroelastics with multifunctional characteristics.