Ultralarge Dielectric Relaxation and Self-Recovery Triggered by Hydrogen-Bonded Polar Components

Subtle integration of rotatable polar components into dielectric crystals can contribute significantly to adjustable switching temperatures ( T_s) and dielectric relaxation behaviors. Currently, one of the biggest challenges lies in the design of optimal polar components with moderate motion resistance in a crystalline system. In this work, we demonstrate that under refrigerator conditions, rotatable hydrogen-bonded one-dimensional (1D) cationic chains, {[C₂H₆N₅]⁺} _n (C₂H₆N₅ = 3,5-diamino-1,2,4-triazolinium), and two-dimensional (2D) anionic layers, {[(H₂O)₂·SO₄]^2-} _n, can be generated in an organic salt, 3 ([C₂H₆N₅]₂·[(H₂O)₂·SO₄]). Compared with the nonhydrated precursor, 2 ([C₂H₇N₅]·[SO₄]), the rotation of these 1D and 2D ionic species triggers a reversible phase transition and dielectric switching in 3. In addition, the significantly sluggish rotation of the 1D cationic chains from parallel to unparallel stacking and the counter-clockwise rotation of the 2D anionic layers, compared with their reverse processes, induce a frequency-dependent dielectric response with a more highly adjustable heating T_s↑ than the cooling T_s↓. More importantly, 3 possesses excellent self-recovery ability attributed to the highly dynamic character of the hydrogen-bonded ionic species. The strategy here can provide a fairly good model for designing dielectric crystals with desired rotatable polar components.