Molecular Dynamics of Flexible Polar Cations in a Variable Confined Space: Toward Exceptional Two-Step Nonlinear Optical Switches

High-temperature sequential structural transitions with distinct switchable dielectric behaviors in two organic ionic plastic crystals: [C4H11NBr] [ClO4] and [C4H11NBr] [BF4]

[C₄H₁₁NBr] [ClO₄] and [C₄H₁₁NBr] [BF₄] undergo phase transitions from an ordered phase to plastic phase accompanied by switchable dielectric anomalies.

Switchable dielectric phase transition behaviors in two organic–inorganic copper(ii) halides with distinct coordination geometries

Two organic–inorganic copper(ii) halides with distinct coordination geometries show noteworthy switchable dielectric phase transition behaviors.

Visualization of Room-Temperature Ferroelectricity and Polarization Rotation in the Thin Film of Quinuclidinium Perrhenate

Recently, a plastic crystal of quinuclidinium perrhenate (HQReO_{4}) was reported to have the feasibility of controlling the crystallographic orientation in the grown crystal, but the corresponding temperature window is only about 22 K (345-367 K). Such a narrow window and uncertain ferroelectricity at room temperature would extremely limit its application potential. In this report, we prepared a large area high-quality polycrystalline thin film of HQReO_{4} and for the first time observed ferroelectricity in the temperature range from 298 to 367 K. Density functional theory calculations revealed the origin of room-temperature ferroelectricity is ascribed to the collaborative flipping of HQ (protonated quinuclidine) and ReO_{4}^{-}, which is dynamically preferred in the presence of a N─H⋯O hydrogen bond. A local piezoresponse force microscopy measurement was also employed to study the mechanisms of multiaxial polarization rotation and domain dynamics. By extending the ferroelectric temperature window to room temperature and the extraordinary thin-film processability, HQReO_{4} would certainly become a suitable candidate for next generation ferroelectric materials.

Sequential dielectric phase transitions induced by the vibrations of water molecules in an organic-inorganic hybrid halide (N-(2-ammoniumethyl)piperazinium) CuCl5·2H2O

Organic-inorganic hybrids represent a new type of material showing promising properties. In this report, sequential dielectric transitions have been studied in an organic-inorganic hybrid halide, (N-2-AP)CuCl₅·2H₂O (N-2-AP = N-(2-ammoniumethyl)piperazinium) (1). The packing structure of 1 displays discrete [CuCl₅]^3- rectangular pyramids and N-2-AP cations, which are linked by two water molecules, forming infinite hydrogen bond networks with inorganic and organic components along the b-axis. Characterization studies containing differential scanning calorimetry (DSC) measurements, variable-temperature X-ray diffraction and dielectric measurements were performed to investigate the phase transitions in 1. The deuterated sample of 1 (named 2) also exhibits a similar behavior to that in 1, but shows different phase transition temperatures in dielectric transitions. The arresting deuterated effect strongly confirms that the phase transitions in 1 are attributable to the local vibrations of water molecules resulting from the variation of hydrogen-bonding interactions.

High-temperature structural phase transition coupled with dielectric switching in an organic-inorganic hybrid crystal: [NH3(CH2)2Br]3CdBr5

Molecular bistable switches (electrical switches "ON" and "OFF") represent a class of highly desirable intelligent materials due to their sensitive switchable responses, simple and environmentally friendly processing, light weight, and mechanical flexibility. In particular, these switches above room temperature with potential practical application are rarely reported. In this work, a new zigzag chained organic-inorganic hybrid compound [NH₃(CH₂)₂Br]₃CdBr₅ (1), which displays rapidly sensitive dielectric switching reversibility and remarkable switching antifatigue, has been successfully synthesized. Systematic characterization including differential scanning calorimetry measurements (DSC), dielectric measurements, and variable-temperature structural analyses was performed to reveal the phase transition of 1. A couple of reversible heat anomaly peaks at 335.6/323.8 K with a large hysteresis (ca. 11.8 K) were observed in the DSC curve, indicating the first-order type of phase transition. 1 exhibits an obvious dielectric switching at around 327 K, which makes 1 a potential switchable dielectric material. Variable-temperature structural analyses show that the cationic order-disorder motion is the main attribution for the phase transition of 1.

A near-room-temperature organic–inorganic hybrid ferroelectric: [C6H5CH2CH2NH3]2[CdI4]

The features of synchronously switchable dielectric constant, SHG, and pyroelectric current provide a promising multifunctional switching material applied in the field of electrical/optical switches and sensors at near room temperature.

[(CH3)3PCH2OH][CdBr3] is a perovskite-type ferroelastic compound above room temperature

[(CH₃)₃PCH₂OH][CdBr₃] is a perovskite-type ferroelastic compound above room temperature, in which domain structures were observed.

Reversible structural phase transition, ferroelectric and switchable dielectric properties of an adduct molecule of hexamethylenetetramine ferrocene carboxylic acid

An unprecedented metallo-organic ferroelectric, the adduct of hexamethylenetetramine ferrocene carboxylic acid displays a reversible structural phase transition around 187 K.

Photoluminescent-dielectric duple switch in a perovskite-type high-temperature phase transition compound: [(CH3)3PCH2OCH3][PbBr3]

A perovskite-type high-temperature phase transition compound, ([(CH₃)₃PCH₂OCH₃][PbBr₃], 1), displays a remarkable bistable photoluminescent-dielectric duple switching behavior.

Dielectric and nonlinear optical dual switching in an organic–inorganic hybrid relaxor [(CH3)3PCH2OH][Cd(SCN)3]

[(CH₃)₃PCH₂OH][Cd(SCN)₃] exhibits dielectric and nonlinear optical dual switching with reversible phase transition as an organic–inorganic hybrid relaxor.

Exceptional bi-step switching of quadratic nonlinear optical properties in a one-dimensional channel compound

A new solid-state channel compound shows exceptional bi-step switching between three distinct nonlinear optical states.

Prominent dielectric transitions in layered organic–inorganic hybrids: (isoamyl-ammonium)2CdX4 (X = Cl and Br)

Two new organic–inorganic layered perovskite-type hybrid compounds demonstrate different dynamic motions of cations, contributing to a significant difference in dielectric transitions.

A high-temperature organic–inorganic ferroelectric with outstanding switchable dielectric characteristics

A new molecular ferroelectric is discovered in an organic–inorganic hybrid compound, (C₆H₅NH₃)₂CdCl₄, which undergoes a reversible order–disorder ferroelectric phase transition at 369 K.

A symmetry breaking phase transition-triggered high-temperature solid-state quadratic nonlinear optical switch coupled with a switchable dielectric constant in an organic–inorganic hybrid compound

The compound exhibits switchable SHG effect and tunable dielectric behaviors, associated with its symmetry breaking phase transition.