Dual-channel control of ferroelastic domains in a host–guest inclusion compound

Abstract

Ferroelastics have attracted tremendous research interest not only because of their promising applications in mechanical switches but also owing to their important significance in mediating the coupling of electric and magnetic polarization in multiferroic materials. Herein, we successfully designed an above-room-temperature host–guest inclusion ferroelastic crystal, [(3,4-DFA)(18-crown-6)][TFSA] (3,4-DFA = 3,4-difluorobenzonium, TFSA = bis(trifluoromethanesulfonyl)ammonium) (1). By replacing the [PF₆] anion with the larger [TFSA] anion, the phase transition temperature (T_c) is successfully increased from 305 K in [(3,4-DFA)(18-crown-6)][PF₆] to 342 K in [(3,4-DFA)(18-crown-6)][TFSA]. Furthermore, the phase transition also changes from the mm2Fmm2-type non-ferroic isostructural one to mmmF2/m-type ferroelastic one. More importantly, the ferroelastic domains of [(3,4-DFA)(18-crown-6)][TFSA] can be not only switched under thermal stimulus, but also rapidly switched in situ under external stress. This work realizes that ferroelastic domains can be simultaneously controlled through two physical channels (temperature and stress), suggesting their great potential in dual-channel switches, and provides an efficient strategy to design more high-performance ferroic materials.