Scheme 2. Coupling between the ferroelectricity of 3BC and M+-inclusion (M+)0.5(1) in the mixed Colh phase of (3BC)0.9[(M+)y·(1)·(X−)y]0.1 salts with M+ = Na+, K+, and Cs+. (a) Coexistence of the ferroelectric domain of 3BC (blue column) and ionic channel of (M+)y·(1)·(X−)y; M+X− = Na+PF6−, K+PF6−, and Cs+(CO32−)0.5. The ionic conduction along the electric field (E) generates a local electric field (Eloc) along the columnar direction. (b) 50%-occupied (M+)0.5([18]crown-6) ionic channels of (Na+)0.5([18]crown-6), (K+)0.5([18]crown-6), and (Cs+)0.5([18]crown-6) under electric field E.
