Search

The double-wave method is widely used in ferroelectric measurements to eliminate the effects of conductance and capacitance components while preserving the ferroelectric domain contribution. However, in polycrystalline ferroelectric material, the assumption of the evolution of domains by the double-wave method no longer applies due to the domain back switch of de-field, and the domain contribution calculated by the current subtraction method is also problematic. Therefore, we proposed a new method to calculate the charge contribution of conductance and eliminate the conductance interference in the hysteresis loop. Finally, the feasibility of this new method is verified in many typical polycrystalline ferroelectric materials. This work provides a path for the study of ferroelectric properties of some high conductivity materials. [ABSTRACT FROM AUTHOR]

Molecular ferroelectric materials have been widely used in capacitors and sensors due to their low cost, light weight, flexibility and good biocompatibility. Organic–inorganic hybrid complexes, on the other hand, have received a great deal of attention in the luminescence field due to their low cost and simple preparation. The combination of ferroelectricity and photoluminescence in organic–inorganic hybrid materials not only leads to tunable optical properties, but also enriches potential applications of multifunctional ferroelectrics in optoelectronic devices. Here, we report a new luminescent ferroelectric material (1,3-dicyclohexylimidazole)2MnCl4 (DHIMC). Thermogravimetric analysis (TGA) was used to measure the mass change of the material at a measurement rate of 20 K min−1 from room temperature to 900 K, and we found that this material has good thermostability, which is up to 383 K. Meanwhile, UV-vis measurements showed that it is also a fluorescent material emitting a strong green fluorescence at the wavelength of 525 nm. The ferroelectricity of the crystal was determined by two different methods: the Sawyer–Tower method and the double-wave method (DWM). Particularly, the single crystal experiences a phase transition from the ferroelectric phase to the paraelectric phase during the heating/cooling process at 318 K/313 K and the space group changes from P1¯ (centrosymmetric) to P1 (non-centrosymmetric). This work will enrich multifunctional luminescent ferroelectric materials and their application in display and sensing. [ABSTRACT FROM AUTHOR]

Multi‐functionalized lead‐free organic‐inorganic hybrid ferroelectrics have recently realized diverse applications especially for optoelectronics and photovoltaics. Herein, the chiral Zn‐based organic−inorganic hybrids are discovered: [(R)‐(−)‐2‐methylpiperazine‐1,4‐diium][Zn(H2O)6]•(SO4)2 (RMPZnS2, space group P21) and [(S)‐(+)‐2‐methylpiperazine‐1,4‐diium]2[Zn(H2O)6]•(SO4)3 (SMP2ZnS3, space group P21212). Through experimental and computational investigations, it is found that RMPZnS2 is a ferroelectric with considerable large polarization value (P ≈ 9.5 µC cm−2) along b–axis, and its ferroelectric‐paraelectric phase transition is switched by rotation of organic cations. Meanwhile, it also possesses a fascinating photovoltaic effect driven by the polar charges at solar‐blind UV region, endowing it with the potential of self‐driven photodetection. In addition, white‐light emissions of the RMPZnS2 and SMP2ZnS3 are observed. The enhanced luminescence by heating is especially suitable for the application in white light‐emitting diodes. Overall, these chiral emission ferroelectrics at the supramolecular level will largely expand their applications in multidisciplinary fields. [ABSTRACT FROM AUTHOR]

The metal-coordinated complex tris(2-hydroxyethyl)ammonium trichloro cadmium(II) (TATC) with a space group of P21/c at room temperature was obtained in aqueous solution. A paraelectric–ferroelectric phase transition (from the monoclinic P21/c phase to the monoclinic P21 phase) occurs at a temperature of 270 K/247 K in the heating/cooling process, which belongs to the order–disorder type transition, and is consistent with the thermodynamic analysis from DSC results. The λ-shape dielectric anomaly follows the Curie–Weiss law with a 105.8-fold change at a frequency of 500 Hz. The maximum value of the pyroelectric coefficient Pe is about 0.11 μC cm−2 K−1, which is higher than the classical ferroelectric crystal TGS (5.5 × 10−2 μC cm−2 K−1). The maximum value of the related figures of merit (FOMs) M1 and M2 at a frequency of 1 MHz is 0.0108 cm2 μC−1 and 0.0245 cm3/2 J−1/2, respectively, which is higher than that of TGS (4 × 10−3 cm2 μC−1 and 0.01 cm3/2 J−1/2). The compensation method (the Sawyer–Tower method) and the double-wave method were used to obtain ferroelectric hysteresis loops and display the ferroelectricity of TATC. The spontaneous polarization and the coercive field of TATC can reach about 1.4 μC cm−2 and 0.3 kV cm−1, respectively. The intense dielectric anomaly and the near-room-temperature Tc value indicate that TATC can be an applicable dielectric switching material. [ABSTRACT FROM AUTHOR]