Molecular Ferroelectric Piperidine‐4‐ylmethanaminium Perchlorate with Superior Switchable Dielectric Properties

Abstract

A new piperidyl-based molecular ferroelectric piperidine-4ylmethanaminium perchlorate (compound 1) has been successfully synthesized, which undergoes a reversible phase transition around T c = 258.8 K. The spontaneous polarization of compound 1 is about 0.63 μC/cm 2 and coercive field as small as 1.14 kV/cm at 192 K. The variable-temperature single-crystal X-ray diffraction reveals that the space group transforms from a polar space group of P2 1 at 173 K to a centrosymmetric space group of P2 1 2 1 2 1 at 293 K. Especially, the dielectric anomaly at the phase transition temperature increases more than 4 times, which indicates potential applications in switchable dielectric devices.[a] X.

Dielectric Response Behavior and Displacement‐Type Metal‐Free Organic‐Inorganic Hybrid Phase Transition Material: trans‐(NH3C6H10NH3)[NO3]2

“…The DSC measurement of compound 1 is performed at the scanning rate of 10 K ⋅ min −1 , and the temperature changes from 220 K to 320 K. As depicted in Figure 1, exothermic and endothermic peaks are observed at 245 K and 307 K, respectively, which implies that 1 is a reversible phase transition compound. Moreover, the large thermal hysteresis (62 K) illustrates that the phase transition is first‐order phase transition [25,31,32] . The thermal enthalpy value measured during cooling is ΔH=1.385 J/g.…”

“…Moreover, the large thermal hysteresis (62 K) illustrates that the phase transition is first-order phase transition. [25,31,32] The thermal enthalpy value measured during cooling is ΔH = 1.385 J/g. The corresponding entropy variation obtained by the formula ΔS = ΔH/T.…”

“…One of the effective strategies for designing and constructing organic‐inorganic phase transition compounds is to combine organic cations and inorganic anions [19–22] . In particular, organic ammonium cations combine with inorganic acid anions to form the metal‐free phase transition compounds [23–27] . With the change of temperature, cations or anions are apt to undergo displacement or order‐disorder motion, leading to phase transition.…”

“…[19][20][21][22] In particular, organic ammonium cations combine with inorganic acid anions to form the metal-free phase transition compounds. [23][24][25][26][27] With the change of temperature, cations or anions are apt to undergo displacement or order-disorder motion, leading to phase transition. For example, Daszkiewicz's group found a new material (H 2 NA)[NO 3 ] (H 2 NA = 2-nitroanilinium).…”

Significance of considering pellet molding pressure and dielectric experimental conditions in the [dielectric constant—temperature] response of switchable dielectric molecular materials: illustration on dabcoHBF4 polycrystals

“…Recently, molecular switchable dielectric compounds have received considerable attention as functional electric materials potentially envisioned for application in the field of molecular electronics (memories), energy harvesting, phase shifters, data communications, and so on [1][2][3][4][5][6]. These systems, mostly made of cationic/anionic pair of molecules, exhibit a solid-solid structural phase transition: at the molecular scale, the switching between low and high dielectric states originates from motional change of the polar counterpart occurring at the vicinity of the transition temperature TC: below TC, the ionic building blocks are fully ordered within the crystal network, resulting in a poorly polarizable material while above TC, the degrees of freedom gained by the disordered molecules allows an easy orientation of the local dipoles when an electric field is applied, resulting thus in a large variation of the permittivity.…”