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Pseudo low-temperature sintering effect and microstructure evolution of SiBCO ceramics
No full textIncorporation of B atoms into SiOC ceramic can suppress the carbothermal reaction and improve the thermal stability. Polymer derived ceramics from single source preceramic polymer is a good solution but the B/Si ratio could not be efficiently adjusted. In this article, a simple, low cost, but efficient method to synthesize SiBCO preceramic polymers was introduced. The B/Si ratio could be adjusted from 1:10 to 5:10, and transformed into SiB0.05C0.66O1.22, SiB0.07C0.62O1.28, and SiB0.27C0.54O1.32 upon sintering. The boron content could be readily tuned and the pseudo low-temperature sintering effect was systematically investigated. The boron content of sintered SiBCO ceramics could reach 4.9 wt%. The addition of boron suppresses the crystallization of beta-SiC and improved thermal stability, indicating possible applications under harsh environments
Recent progress in the shape deformation of polymeric hydrogels from memory to actuation
No full textShape deformation hydrogels, which are one of the most promising and essential classes of stimuli-responsive polymers, could provide large-scale and reversible deformation under external stimuli. Due to their wet and soft properties, shape deformation hydrogels are anticipated to be a candidate for the exploration of biomimetic materials, and have shown various potential applications in many fields. Here, an overview of the mechanisms of shape deformation hydrogels and methods for their preparation is presented. Some innovative and efficient strategies to fabricate programmable deformation hydrogels are then introduced. Moreover, successful explorations of their potential applications, including information encryption, soft robots and bionomic systems, are discussed. Finally, remaining great challenges including the achievement of multiple stable deformation states and the combination of shape deformation and sensing are highlighted
Improving Corrosion Protection and Friction Resistance of Q235 Steel by Combining Noncovalent Action and Rotating Coating Method
No full textDeveloping waterborne epoxy (WEP) coatings with excellent corrosion resistance and tribological properties is a key aspect to solve the damage of Q235 steel. In this work, perylene bisimide (PBI) derivatives dispersion graphene (GR) were prepared by a pi-pi stacking, the highly orientated PBI0.5/GR(0)(.5)(%)/WEP coating will be prepared by the rotating coating method. Especially, the impedance value reached about 10(9) Omega.cm(2) when the PBI and GR ratio is 1:1. The impedance value of PBI0.5%/GR(0.5%)/WEP coating increased by 3 orders of magnitude compared with that of pure WEP coating (10(6) Omega.cm(2)). Additionally, the coefficient of friction of the coatings was 0.33; compared with that of WEP, the coefficient of friction decreased by 48%, and the wear resistance increased by 87.6%. The results show that the PBI0.5%/GR(0)(.5)(%) /WEP coatings exhibited excellent corrosion resistance and wear resistance properties due to the good dispersion and high orientation of PBI/GR in WEP. It is anticipated that our current work would guide the ongoing efforts to develop a more efficient method to overcome the poor dispersion of GR in waterborne epoxy resin and provide a green coating with excellent corrosion resistance and wear resistance properties
A trade-off between antifouling and the electrochemical stabilities of PEDOTs
No full textStrong nonspecific protein/cell adhesion on conducting polymer (CP)-based bioelectronic devices can cause an increase in the impedance or the malfunction of the devices. Incorporating oligo(ethylene glycol) or zwitterionic functionalities with CPs has demonstrated superior performance in the reduction of nonspecific adhesion. However, there is no report on the evaluation of the antifouling stability of oligo(ethylene glycol) and zwitterion-functionalized CPs under electrical stimulation as a simulation of the real situation of device operation. Moreover, there is a lack of understanding of the correlation between the molecular structure of antifouling CPs and the antifouling and electrochemical stabilities of the CP-based electrodes. To address the aforementioned issue, we fabricated a platform with antifouling poly(3,4-ethylenedioxythiophene) (PEDOT) featuring tri(ethylene glycol), tetra(ethylene glycol), sulfobetaine, or phosphorylcholine (PEDOT-PC) to evaluate the stability of the antifouling/electrochemical properties of antifouling PEDOTs before and after electrical stimulation. The results reveal that the PEDOT-PC electrode not only exhibits good electrochemical stability, low impedance, and small voltage excursion, but also shows excellent resistance toward proteins and HAPI microglial cells, as a cell model of inflammation, after the electrical stimulation. The stable antifouling/electrochemical properties of zwitterionic PEDOT-PC may aid its diverse applications in bioelectronic devices in the future
Charge-transfer induced multifunctional BCP:Ag complexes for semi-transparent perovskite solar cells with a record fill factor of 80.1%dagger
No full textFor semi-transparent perovskite solar cells (PSCs), the bombardment during the deposition of a transparent conductive oxide would inevitably damage the underlying soft materials, thereby inducing a high density of defects and creating an unfavorable band mismatch at the interface. Although interfacial buffer layers can be adopted to alleviate this bombardment damage, the device performance is still limited by the inferior fill factor (FF) due to the increased series resistance and the decreased carrier collection. In this work, a charge transfer induced 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP):Ag complex is employed to mediate the electrical contact between a C-60 electron-transport layer and sputtered indium-zinc oxide (IZO) top electrode. We demonstrate that the multifunctional BCP:Ag complex can (1) reduce the electron extraction barrier by pulling up the Fermi level of BCP, (2) create beneficial gap states for electron transport, (3) serve as a hole blocking layer to suppress charge recombination, and (4) protect the C-60 underlayer from the sputtering damage. As a result, the optimized electrical contact at the C-60/BCP:Ag/IZO interface significantly recovered the FF of the inverted semi-transparent perovskite solar cell from 71.8% to 80.1%, yielding a device efficiency of 18.19%. By using a 23.19% efficient silicon solar cell, we also demonstrate a four-terminal tandem configuration with a total efficiency of 27.59%
Crystal Orientation-Dependent Oxidation of Epitaxial TiN Films with Tunable Plasmonics
No full textTitanium nitride (TiN) is a paradigm of refractory transition metal nitrides with great potential in vast applications. Generally, the plasmonic performance of TiN can be tuned by oxidation, which was thought to be only temperature-, oxygen partial pressure-, and time-dependent. Regarding the role of crystallographic orientation in the oxidation and resultant optical properties of TiN films, little is known thus far. Here we reveal that both the oxidation resistance behavior and the plasmonic performance of epitaxial TiN films follow the order of (001) < (110) < (111). The effects of crystallographic orientation on the lattice constants, optical properties, and oxidation levels of epitaxial TiN films have been systematically studied by combined high-resolution X-ray diffraction, spectroscopic ellipsometry, X-ray absorption spectroscopy, and X-ray photoemission spectroscopy. To further understand the role of crystallographic orientation in the initial oxidation process of TiN films, density-functional-theory calculations are carried out, indicating the energy cost of oxidation is (001) < (110) < (111), consistent with the experiments. The superior endurance of the (111) orientation against mild oxidation can largely alleviate the previously stringent technical requirements for the growth of TiN films with high plasmonic performance. The crystallographic orientation can also offer an effective controlling parameter to design TiN-based plasmonic devices with desired peculiarity, for example, superior chemical stability against mild oxidation or large optical tunability upon oxidation
Designing novel organic inhibitor loaded MgAl-LDHs nanocontainer for enhanced corrosion resistance
No full textThe combination of LDHs nanocontainer and organic inhibitor demonstrates a great prospect in the field of corrosion protection. Whereas the traditional ion exchange method has a low efficiency owing to the small space and the firm force between the LDHs laminates. A high-efficiency approach of intercalating organic inhibitor into the LDHs is delivered in this work. The MgAl-LDHs loaded with 5-aminoindazole (AIA) were synthesized by separating the layered structures of hydrotalcites into single-layer nanosheets and then restructuring the exfoliated nanosheets with organic inhibitor. The as-synthesized LDHs-AIAdisplayed a controlled release behavior and excellent anti-corrosion performance on the copper in 3.5 wt% NaCl solution, which were characterized by UV-vis spectra and electrochemical tests. Furthermore, a series of structure and morphology tests involving SEM, TEM, XRD, FTIR, XPS and TGA were also used for further analysis the LDHs. And the analysis of corrosion products and the anti-corrosion mechanism were carried out by SEM, XRD tests. The theoretical calculations concerning the adsorption of corrosion inhibitors on the copper surface were also investigated. It can be concluded that the inhibitor-loaded LDHs have the ability to adjustably release the corrosion inhibitor in corrosive medium, thereafter the corrosion inhibitor can adsorb onto the active sites of copper surface to prevent corrosion
Proximate Quantum Spin Liquid on Designer Lattice
No full textComplementary to bulk synthesis, here we propose a designer lattice with extremely high magnetic frustration and demonstrate the possible realization of a quantum spin liquid state from both experiments and theoretical calculations. In an ultrathin (111) CoCr2O4 slice composed of three triangular and one kagome cation planes, the absence of a spin ordering or freezing transition is demonstrated down to 0.03 K, in the presence of strong antiferromagnetic correlations in the energy scale of 30 K between Co and Cr sublattices, leading to the frustration factor of similar to 1000. Persisting spin fluctuations are observed at low temperatures via low-energy muon spin relaxation. Our calculations further demonstrate the emergence of highly degenerate magnetic ground states at the 0 K limit, due to the competition among multiply altered exchange interactions. These results collectively indicate the realization of a proximate quantum spin liquid state on the synthetic lattice
All annealing-free solution-processed highly flexible organic solar cells
No full textAn all annealing-free solution-manufacturing is regarded as a technological advancement for the development of flexible organic solar cells (OSCs), which can prevent the distortion of plastic substrates, avoid destroying the active components of the devices, and simplify the device fabrication. Here, we report an efficient all annealing-free solution-processed flexible OSC integrated on a soft polyethylene (PE) substrate. The transparent anodes, hole-transport layers, active layers and electron-transport layers are solution-processed at room temperature without thermal annealing treatments. Thanks to both the as-developed gentle superacid doping and air-drying treatments at room temperature that enable a high-merit flexible anode on the soft PE substrates, the annealing-free flexible OSCs yield a high efficiency of 14.66% along with a high power-per-weight of 6.33 W g(-1), which is close to that (15.73%) of thermally annealed rigid OSCs based on indium tin oxide anodes. Due to the mild annealing-free solution-processing and the soft PE substrates having an extremely low Young's modulus of only 0.2 GPa, the flexible OSCs maintain a high flexibility in a harsh bending test
The enhanced magnetic properties of FeSiCr powder cores composited with carbonyl iron powder
No full textToroid-shaped Fe-based soft magnetic powder cores (SMPCs) were prepared by cold pressing commercial FeSiCr and carbonyl iron powder (CIP) insulated with epoxy resin. The effect of the CIP mass ratio on the magnetic properties of powder cores, which included the dependences of the effective permeability (mu(e)), DC bias characteristic, and core loss (P-cv), was investigated. By optimizing the CIP content, the mu(e) of the magnetic powder cores reaches 31 when the CIP content is 30 wt%, and it exhibits a stable permeability in the frequency range up to 1 MHz. Meanwhile, the DC bias characteristic increases to 78%, and the P-cv is minimized to 1684 mW/cm(3), which is reduced by 15% at 50 mT and 250 kHz