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基于独特的结构和性质, 石墨烯在很多领域都表现出了巨大的潜力. 作为制备石墨烯的主要母体材料, 石墨烯氧化物在室温条件下被观测到具有弱的铁电性. 石墨烯氧化物的表面和边界上会存在大量的羟基, 这些羟基有序重复排列而构成了一维的氢键链, 这些有序氢键链可能是石墨烯氧化物呈现铁电性能的主要原因. 相似文献
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Duo-Fu Li Yao-Zhen Wu Xiao-Li He Xiang-Hong Deng Jing Chen Jia Fu Prof. Dr. Yan Sui 《Chemphyschem》2023,24(13):e202300207
The organic salt chlorocholine perchlorate [ClCH2CH2N(CH3)3⋅ClO4] ( CCP ) is found to be a molecular ferroelectric with a high theoretical spontaneous polarization (Ps) value up to 17.09 μC cm−2. CCP exhibits two successive order-disorder phase transition at 332 and 365 K with space groups changing from Cc to Cmc21 and then P63/mmc, accompanied by unusual two-step ladder-like dielectric, SHG signal with obvious “on/off” contrasts. These findingings provides a further instance of exploring successive thermal-stimuli multi-responsive switching materials applied as switches and sensors. 相似文献
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The electronic and geometrical structures of neutral and negatively charged AlO5, AlO6, AlO7, AlO8, AlO9, AlO10, AlO11, AlO12, AlO15, AlO16, and AlO18 along with the corresponding series of ScOn and ScO oxides were investigated using density functional theory with generalized gradient approximation. We found that these species possess geometrically stable isomers for all values of n = 5–12, 15, 16, 18 and are thermodynamically stable for n = 5–7. The species with n = 16 are found to be octa‐dioxides M(η1‐O2)8 while the species with n = 15 and 18 are penta‐ozonides (η2‐O3)M(η1‐O3)4 and hexa‐ozonides M(η1‐O3)6, respectively. Geometrical configurations of a number of the lowest total energy states of Al and Sc oxides are different. Especially, drastic differences are found for the anion AlO and ScO pairs at n = 9, 10, and 11. The Sc? O bonds are longer than the Al? O bonds by ≈0.2 Å, which, in turn, slightly affects the corresponding interoxygen bond lengths. The charges on metal atoms are close to +2e in both Al series and to +1.5e in both Sc series. As an extra electron is delocalized over ligands in the presence of a large positive charge on the metal atom of the anions, the electron affinity (EA) of the neutrals along with the ionization energies of the anions are large and exceed the EAs of the halogen atoms in a number of cases. © 2011 Wiley Periodicals, Inc. J Comput Chem 2011 相似文献
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Micropatterning of the Ferroelectric Phase in a Poly(vinylidene difluoride) Film by Plasmonic Heating with Gold Nanocages 下载免费PDF全文
Jianhua Li Miaoxin Yang Xiaojun Sun Dr. Xuan Yang Dr. JiaJia Xue Dr. Chunlei Zhu Prof. Hong Liu Prof. Younan Xia 《Angewandte Chemie (International ed. in English)》2016,55(44):13828-13832
Polymer thin films with patterned ferroelectric domains are attractive for a broad range of applications, including the fabrication of tactile sensors, infrared detectors, and non‐volatile memories. Herein, we report the use of gold nanocages (AuNCs) as plasmonic nanostructures to induce a ferroelectric–paraelectric phase transition in a poly(vinylidene fluoride) (PVDF) thin film by leveraging its photothermal effect. This technique allows us to generate patterned domains of ferroelectric PVDF within just a few seconds. The incorporation of AuNCs significantly enhances the pyroelectric response of the ferroelectric film under near‐infrared irradiation. We also demonstrate the use of such patterned ferroelectric films for near‐infrared sensing/imaging. 相似文献
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Binary blends of ferroelectric (vinylidene fluoride-trifluorethylene) copolymer [P(VDF-TrFE)] and amorphous poly(methyl-methacrylate) (PMMA) were investigated over the full range of composition, for the copolymer with 50 mol % of trifluorethylene. Dielectric measurements confirmed that the system becomes amorphous when the PMMA contents exceed 40 wt %. The observed dielectric losses could be attributed to the ferroelectric transition of the copolymer and to molecular relaxations, characteristic of the individual polymers. We demonstrate the thermally activated nature of the β-PMMA and β-P(VDF-TrFE) relaxations, with activation energies of 29.3 and 13.5 kcal/mol, respectively. We also demonstrate that the β-P(VDF-TrFE) relaxation cannot be attributed only to the copolymer glass transition and that its origin is not in the crystalline region, based on experimental evidences. © 1999 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 37: 2996–3002, 1999 相似文献
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Wuqian Guo Xitao Liu Shiguo Han Yi Liu Zhiyun Xu Prof. Maochun Hong Prof. Junhua Luo Prof. Zhihua Sun 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(33):13983-13988
Although two-dimensional (2D) metal–halide double perovskites display versatile physical properties due to their huge structural compatibility, room-temperature ferroelectric behavior has not yet been reported for this fascinating family. Here, we designed a room-temperature ferroelectric material composed of 2D halide double perovskites, (chloropropylammonium)4AgBiBr8, using an organic asymmetric dipolar ligand. It exhibits concrete ferroelectricity, including a Curie temperature of 305 K and a notable spontaneous polarization of ≈3.2 μC cm−2, triggered by dynamic ordering of the organic cation and the tilting motion of heterometallic AgBr6/BiBr6 octahedra. Besides, the alternating array of inorganic perovskite sheets and organic cations endows large mobility-lifetime product (μτ=1.0×10−3 cm2 V−1) for detecting X-ray photons, which is almost tenfold higher than that of CH3NH3PbI3 wafers. As far as we know, this is the first study on an X-ray-sensitive ferroelectric material composed of 2D halide double perovskites. Our findings afford a promising platform for exploring new ferroelectric materials toward further device applications. 相似文献
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Synchrotron X-ray powder diffraction patterns were collected at the European Synchrotron Radiation Facility (ESRF, Grenoble, France) on powder samples of PbTiO3 (tetragonal, Z=1 P4mma=3.9036(1) Å and c=4.1440(2) Å at room conditions) applying external pressure using a diamond anvil cell. Data were collected at four different temperatures (room temperature, 462, 538 and 623 K) up to the phase transition to the cubic phase (Z=1, Pm3ma=3.8647(4) Å at RT and 11.6 GPa). Analyzing the behavior of the cell parameters obtained by the Rietveld refinement, we were able to extract the dependence of the critical temperature on external pressure. The bulk moduli of the lead titanate were calculated for the first time. The progressive decrease of the distortion of the Pb and Ti coordination polyhedra with pressure allows to propose a structural explanation of the first-/second-order cross-over in the ferroelectric-paralectric phase transition on applying pressure. 相似文献
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Patrick J. Schexnailder Akhilesh K. Gaharwar Rush L. Bartlett II Brandon L. Seal Gudrun Schmidt 《Macromolecular bioscience》2010,10(12):1416-1423
Controlling cell adhesion on a biomaterial surface is associated with the long‐term efficacy of an implanted material. Here we connect the material properties of nanocomposite films made from PEO physically cross‐linked with layered silicate nanoparticles (Laponite) to cellular adhesion. Fibroblast cells do not adhere to pure PEO, but they attach to silicate containing nanocomposites. Under aqueous conditions, the films swell and the degree of swelling depends on the nanocomposite composition and film structure. Higher PEO compositions do not support cell proliferation due to little exposed silicate surfaces. Higher silicate compositions do allow significant cell proliferation and spreading. These bio‐nanocomposites have potential for the development of biomedical materials that can control cellular adhesion.
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Wuqian Guo Xitao Liu Shiguo Han Yi Liu Zhiyun Xu Maochun Hong Junhua Luo Zhihua Sun 《Angewandte Chemie (International ed. in English)》2020,59(33):13879-13884
Although two‐dimensional (2D) metal–halide double perovskites display versatile physical properties due to their huge structural compatibility, room‐temperature ferroelectric behavior has not yet been reported for this fascinating family. Here, we designed a room‐temperature ferroelectric material composed of 2D halide double perovskites, (chloropropylammonium)4AgBiBr8, using an organic asymmetric dipolar ligand. It exhibits concrete ferroelectricity, including a Curie temperature of 305 K and a notable spontaneous polarization of ≈3.2 μC cm?2, triggered by dynamic ordering of the organic cation and the tilting motion of heterometallic AgBr6/BiBr6 octahedra. Besides, the alternating array of inorganic perovskite sheets and organic cations endows large mobility‐lifetime product (μτ=1.0×10?3 cm2 V?1) for detecting X‐ray photons, which is almost tenfold higher than that of CH3NH3PbI3 wafers. As far as we know, this is the first study on an X‐ray‐sensitive ferroelectric material composed of 2D halide double perovskites. Our findings afford a promising platform for exploring new ferroelectric materials toward further device applications. 相似文献
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A Molecular Ferroelectric Showing Room‐Temperature Record‐Fast Switching of Spontaneous Polarization 下载免费PDF全文
Prof. Zhihua Sun Xianfeng Yi Kewen Tao Chengmin Ji Xitao Liu Dr. Lina Li Shiguo Han Prof. Anmin Zheng Prof. Maochun Hong Prof. Junhua Luo 《Angewandte Chemie (International ed. in English)》2018,57(31):9833-9837
Fast switching of spontaneous polarization (Ps) is one of the most essential requirements for ferroelectrics used in the field of data storage. However, in contrast to inorganic counterparts, the low operating frequency (<500 Hz) for molecular ferroelectrics severely hinders their large‐scale applications. Herein, for the first time, we achieved the room‐temperature fastest switching of the Ps in a new molecular ferroelectric, N‐methylmorpholinium trinitrophenolate ( 1 ), which displays notable ferroelectricity (Ps=3.2 μc cm?2). Strikingly, electric polarizations of 1 have been switched under a record‐high frequency of 263 kHz, and this performance remains stable without any obvious fatigue after ca. 2×105 switching cycles. To our knowledge, 1 is the first organic ferroelectric to switch polarization at such a high operating frequency, exceeding the majority of organic ferroelectrics, which opens up new possibilities for its potential in the field of non‐volatile memory. 相似文献
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Shingo Maeda Yusuke Hara Ryo Yoshida Shuji Hashimoto 《Macromolecular rapid communications》2008,29(5):401-405
A novel self‐oscillating gel actuator with gradient structure, which generates a pendulum motion by fixing one edge of the gel without external stimuli was achieved. The gel was synthesized by copolymerizing the ruthenium catalyst for the Belousov‐Zhabotinsky reaction with N‐isopropylacrylamide and 2‐acrylamido‐2‐methylpropane sulfonic acid. Furthermore, we clarified that the period and amplitude for the self‐oscillating behavior of the gel actuator are controllable by changing the composition, temperature, and size of the gel. The maximum amplitude of the novel gel actuator is about a 100 times larger than that of the conventional self‐oscillating gel system.
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The blending between poly(methyl methacrylate) (PMMA) and ferroelectric (vinylidene fluoride‐trifluorethylene) [P(VDF‐TrFE)] copolymer chains has been investigated by Fourier transform infrared (FTIR) spectroscopy over the full range of composition, for the copolymer with 50 mol % of trifluorethylene [TrFE]. The FTIR spectra revealed an absorption band at 1643 cm−1, characteristic of the blend and absent in the individual constituents. We attributed this band to the interaction of the carbonyl group of the PMMA side chains with the disordered helical chains present in the amorphous region of the P(VDF‐TrFE). We investigated the consequences of adding PMMA onto the formation of the all trans conformation of the copolymer chains and we demonstrated that the effects of thermal heating on the spectra are relevant only for the samples where the ferroelectric semicrystalline phase is present. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 34–40, 2000 相似文献
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Transition Metal Oxides for the Oxygen Reduction Reaction: Influence of the Oxidation States of the Metal and its Position on the Periodic Table 下载免费PDF全文
Electrocatalysts have been developed to meet the needs and requirements of renewable energy applications. Metal oxides have been well explored and are promising for this purpose, however, many reports focus on only one or a few metal oxides at once. Herein, thirty metal oxides, which were either commercially available or synthesized by a simple and scalable method, were screened for comparison with regards to their electrocatalytic activity towards the oxygen reduction reaction (ORR). We show that although manganese, iron, cobalt, and nickel oxides generally displayed the ability to enhance the kinetics of oxygen reduction under alkaline conditions compared with bare glassy carbon, there is no significant correlation between the position of a metal on the periodic table and the electrocatalytic performance of its respective metal oxides. Moreover, it was also observed that mixed valent (+2, +3) oxides performed the poorest, compared with their respective pure metal oxides. These findings may be of paramount importance in the field of renewable energy. 相似文献
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Electronic structure of ferroelectric PbTiO3 and BaTiO3 is calculated by the full potential linearized augmented plane wave method. The total energy as a function of the displacement of Ti-cation is obtained for PbTiO3 and BaTiO3 at different cell volumes. At experimental cell volume, Ti-displacement lowers the total energy and the ferroelectricity is stable. When the cell volume is reduced to 90%, total energy is increased with Ti-displacement and ferroelectricity will disappear. The cell volume effect is also confirmed by comparison of the density of states of Ti and O at different cell volumes. 相似文献