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DaltonTransactions An international journal of inorganic chemistry rsc. li/ dalton Volume 53 Number 45 7 December 2024 Pages 18057- 18386 ISSN 1477- 9226 PAPER Minoru Osada et al. Ferroelectricity in CsPb 2 Nb 3 O 10 and exfoliated 2D nanosheets [Extracted from the article]

Pb-based perovskites play pivotal roles in ferroelectric research. In the search for new Pb-based ferroelectrics, we investigated the ferroelectric properties of Dion–Jacobson type CsPb2Nb3O10 and exfoliated 2D nanosheets. Ferroelectricity in CsPb2Nb3O10 was demonstrated for the first time. CsPb2Nb3O10 adopted a polar tetragonal structure with a modest TC = 260 °C and polarization PS = 7.93 μC cm−2; the polarization mainly arose from the out-of-plane displacements of Nb5+ ions and nearby oxygens. CsPb2Nb3O10 layered perovskite offers additional advantages for tailoring ferroelectric nanomaterials, as exfoliated 2D nanosheets provide novel platforms for investigating ferroelectric properties down to the 2D limit. Piezoresponse force microscopy confirmed stable ferroelectricity even in exfoliated 2D Pb2Nb3O10 nanosheets. [ABSTRACT FROM AUTHOR]

Ferroelectric polymers are of great interest due to their intrinsic processing capabilities, superior to classic inorganic ferroelectric materials. For example, polyvinylidene fluoride (PVDF) and derivatives have been incorporated into multiple device architectures for information storage and transfer. Here we report an additional advantage of organic ferroelectrics as their flexibility allows for the preparation of composites with spin crossover (SCO) probes to tune their ferroelectric parameters by external stimuli. We demonstrate how the saturation polarization and coercive field of a ferroelectric [Fe(NH2trz)3](NO3)2/PVDF composite film depends on the spin state of the [Fe(NH2trz)3](NO3)2, opening a thermal hysteresis and delivering a ferroelectric material with a memory effect. This switching may now be used to tune the function of a device, adding additional information states to the elemental binary logic. Additional evidence of the synergy between the two components of these films was also found in the glass transition of the PVDF component that induces small changes in the paramagnetic component. [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]

Non-toxic molecular ferroelectrics have attracted significant interest due to their unique flexibility, low costs, and environmental friendliness. However, such materials with narrow bandgaps and ferroelectricity above room temperature (RT) are still scarce. Herein, we present a brand-new lead-free molecular ferroelectric [C8N2H22]1.5[Bi2I9] synthesized hydrothermally. [C8N2H22]1.5[Bi2I9] features a zero-dimensional (0D) structure with a polar space group of Pc, as confirmed by single-crystal X-ray diffraction and second-harmonic generation (SHG) analyses. The RT hysteresis loop reveals the intrinsic ferroelectricity of [C8N2H22]1.5[Bi2I9] with a spontaneous polarization (Ps) of 1.3 μC cm−2. A visible-light optical bandgap has been confirmed by UV-vis spectroscopy and theoretical calculations. A notable ferroelectric photovoltaic (PV) effect has been revealed in [C8N2H22]1.5[Bi2I9]-based photoelectric devices with an open-circuit voltage (Voc) of 0.39 V and a short-circuit current density (Jsc) of 2.3 μA cm−2 under AM 1.5G illumination. The PV performance can be significantly enhanced by tuning the ferroelectric polarization, achieving a maximum Voc of 0.47 V and Jsc of about 50 μA cm−2. This study offers a novel member of the 0D lead-free hybrid organic–inorganic molecular ferroelectric family possessing great promise for optoelectronic devices. [ABSTRACT FROM AUTHOR]

Kaolinite possesses a structure with asymmetrically layered 1 : 1 dioctahedral aluminum silicate, and this structural property provides a useful platform for creating new cost-efficient functional materials that require noncentrosymmetric crystal packing. In this study, we prepared three covalently grafted kaolinites of propanediol (PD)/butanediol (BD)/glycerol (GL) by forming Al−O−C bonds between the OH groups of PD/BD/GL and the surface of kaolinite (K). Three covalently grafted kaolinites (K-PD, K-BD and K-GL) were characterized by X-ray diffraction, infrared spectroscopy, thermogravimetric analysis, scanning electron microscopy and microanalysis for C, H and N elements. The test of K-PD, K-BD and K-GL stirred with water at ambient conditions for 3 days demonstrated these hybrids showing extra high chemical stability to water. The dielectric spectra of three hybrids show two-step dielectric relaxation in the range of 1–107 Hz, and the P−E measurements revealed the existence of ferroelectricity at room temperature with the spontaneous polarization, the remanent polarization and the coercive field of ∼0.014 μC cm−2, ∼0.008 μC cm−2 and ∼0.426 kV cm−1 for K-PD, ∼0.017 μC cm−2, ∼0.011 μC cm−2 and ∼0.645 kV cm−1 for K-BD, and ∼0.018 μC cm−2, ∼0.011 μC cm−2 and ∼0.141 kV cm−1 for K-GL, respectively. [ABSTRACT FROM AUTHOR]

Nano-ferroelectric materials have excellent piezoelectric performance and can degrade organic dye by ultrasonic vibration in an aqueous solution. Here, BaTiO3 (BT) nanoparticles were prepared by a sol–gel/hydrothermal method and further applied in dye degradation in wastewater. BT nanoparticles exhibited excellent catalytic performance for organic dye molecule degradation through the piezo–Fenton synergistic effect. It was found that both the degradation efficiency and reaction rate were boosted by the increase of the molecular weight of organic dyes. The degradation efficiency toward different organic dyes exhibited a trend of CR > ABK > TH > RhB > MB > MO. For example, a high piezo–Fenton-catalytic degradation ratio of 82.8% at 5 min and 0.337 min−1 rate constant were achieved for the CR dye solution (10 mg L−1), which were 3.2 and 6.4 times the corresponding values of piezo-catalytic only degradation. These results mainly originate from the intrinsic properties of BT nanoparticles that can enhance the separation of charge and promote the formation of hydrogen peroxide (H2O2) and hydroxyl radicals (·OH) under ultrasonic vibration. Furthermore, the reaction of Fe(II) with H2O2 can further enhance the formation of ·OH, which can accelerate the degradation of organic dyes. These results indicate that the piezo–Fenton synergistic effect may provide a new clue for the development of the wastewater treatment field under mechanical vibration. [ABSTRACT FROM AUTHOR]