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, {[C ₂ H ₆ N ₅ ] ⁺ } _n (C ₂ H ₆ N ₅ = 3,5-diamino-1,2,4-triazolinium), and two-dimensional (2D) anionic layers, {[(H ₂ O) ₂ ·SO ₄ ] ^2- } _n , can be generated in an organic salt, 3 ([C ₂ H ₆ N ₅ ] ₂ ·[(H ₂ O) ₂ ·SO ₄ ]). Compared with the nonhydrated precursor, 2 ([C ₂ H ₇ N ₅ ]·[SO ₄ ]), 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.