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Tian C.,MOE Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed Matter | Ding C.,Xian Jiaotong University | Liu S.,CAS Institute of Physics | Yang S.,MOE Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed Matter | And 5 more authors.
ACS Nano | Year: 2011

Using three-dimensional finite-difference time-domain (FDTD) simulation, we described a systematic investigation on the electric field enhancement of the silver corrugated nanowires. The enhancement factor (EF) of surface-enhanced Raman scattering (SERS) for corrugated nanowires can be markedly increased by 1 or 2 orders of magnitude as compared with the smooth nanowires. Moreover, the EF can be further increased with nanoparticle attachment on the corrugated Ag nanowires owing to the coupling between the discrete plasmon state of the nanoparticles and continuum plasmon states of the corrugated nanowire or the crossed corrugated nanowires. The surface plasmonic field distribution of Ag nanowires can be effectively controlled by the polarization of the incident light. Raman spectrum measurements show that the relatively dense corrugated nanowires exhibit a relatively high reproducibility and SERS enhancement attributed to the elimination of polarization-dependent SERS-anisotropic enhancement via the overlapping of randomly distributed Ag nanowires. Such nanostructures as potential nanoantennas offer a route to optimize plasmon coupling for designing miniaturization integration. © 2011 American Chemical Society. Source


Liu C.H.,MOE Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed Matter | Ding C.H.,Xian Jiaotong University
Wear | Year: 2010

In this study, HFIS304 coating comprising NiCr (80/20) matrix (60 wt%) combined with Cr2O3 (20 wt%), Ag (10 wt%) and eutectic BaF2/CaF2 (10 wt%) as solid self-lubricants additives has been successfully prepared by cold isostatic pressing and high-frequency induction sintering (HFIS) on a Ni-based superalloy rod. The microstructure of HFIS304 was fine and dense, the size of Cr2O3, BaF2/CaF2 particles was below 1 μm, and that of Ag particles about 1 μm. The tribological properties of HFIS304 composites against Inconel X-750 were examined. The wear resistance and friction coefficient of the HFIS304 were superior to that of the PS304 in the temperature range from room temperature to 600 °C. The improvement in wear resistance of the HFIS304 was discussed in the terms of its microstructural characteristics. Additionally, the model of high temperature self-lubricating particles was proposed. © 2009 Elsevier B.V. All rights reserved. Source


Li J.,Xian Jiaotong University | Hu X.,Xian Jiaotong University | Gao G.,Xian Jiaotong University | Ding S.,Xian Jiaotong University | And 4 more authors.
Journal of Materials Chemistry C | Year: 2013

For potential application in high energy storage capacitors with high energy density and low energy loss, three sets of poly(vinylidene fluoride-co-trifluoroethylene-co-chlorotrifluoroethylene) [P(VDF-TrFE-CTFE)] grafted with poly(methacrylic ester)s, including poly(methyl methacrylate) (PMMA), poly(ethyl methacrylate) (PEMA) and poly(butyl methacrylate) (PBMA) copolymers, are designed and investigated carefully. Due to their intermediate polarity, relatively high glass transition temperature, and excellent compatibility with PVDF chains, the poly(methacrylic ester) segments introduced could not only dramatically weaken the coupling interactions of oriented polar crystals, but could also accelerate the reversal switching of polar crystal domains along the applied electric field, which leads to well hindered remnant polarization. As a result, the displacement-electric field (D-E) hysteresis behaviors of the graft copolymers could be tuned from typical ferroelectric to either antiferroelectric or linear shape under high electric field. Meanwhile, significantly reduced energy loss and effectively improved energy discharging efficiency were obtained. Compared with PMMA and PBMA, PEMA with intermediate polarity and grafting length exhibits more suitable confinement of the F-P transition of P(VDF-TrFE-CTFE), and thus more desirable energy storage properties are observed in the resultant copolymers. These findings may help to deeply understand the ferroelectric nature of PVDF based fluoropolymers and design new energy storage capacitor materials with high discharged energy density and low energy loss. This journal is © 2013 The Royal Society of Chemistry. Source


Tan S.,Xian Jiaotong University | Li J.,Xian Jiaotong University | Gao G.,Xian Jiaotong University | Li H.,CAS Institute of Chemistry | And 2 more authors.
Journal of Materials Chemistry | Year: 2012

Fluoropolymer containing unsaturation, an important intermediate for many reactions such as radical addition and Michael addition reaction, could be either utilized to synthesize fluoropolymer with desired functions or cured for rubber applications, which has rarely been investigated because of the absence of a synthetic strategy. A facile method to synthesize fluoropolymer with tunable unsaturation via controlled dehydrochlorination of commercially available poly(vinylidene fluoride-co-chlorotrifluoroethylene) (P(VDF-co-CTFE)) catalyzed by tertiary monoamines under mild conditions has been reported in this work. The resultant copolymers are carefully characterized with nuclear magnetic resonance (NMR), Fourier transform infrared (FTIR), and thermal gravimetric analysis (TGA). It has been shown that the elimination could be well controlled by employing proper solvent, catalyst and reaction conditions. The typical side reactions catalyzed with amines, such as Michael addition reaction and main chain scission during the dehydrofluorination of fluoropolymer, could be avoided in the present reaction system. The kinetics results indicate that the elimination reaction is in a bi-molecular mechanism (E2), which is well recognized in strong base-catalyzed elimination of halogenated hydrocarbon. The concentration, alkalinity and steric bulk of the catalysts, the polarity and capability to absorb HCl acid of solvents, and the reaction time and temperature exhibit dominant influences on the dehydrochlorination of P(VDF-co-CTFE). The fluoropolymer containing unsaturation is readily cured with peroxide, and the crosslinked fluoropolymer exhibits excellent solvent resistance and mechanical properties. © 2012 The Royal Society of Chemistry. Source


Li J.,Xian Jiaotong University | Tan S.,Xian Jiaotong University | Ding S.,Xian Jiaotong University | Li H.,CAS Institute of Chemistry | And 3 more authors.
Journal of Materials Chemistry | Year: 2012

In this work, we report a novel antiferroelectric-like performance at high poling fields obtained in poly(ethyl methacrylate) (PEMA) grafted poly(vinylidene fluoride-co-trifluoroethylene) (P(VDF-TrFE)) series copolymers for application as high energy density and low loss capacitor dielectrics films. Compared with the pristine P(VDF-TrFE) random copolymer, an enhanced discharged energy density but a lowered energy loss has been observed as more PEMA is grafted. This novel antiferroelectric-like behavior at high poling field was explained by the crystalline impediment and polarization confinement effect induced by PEMA side chains. The highest discharged energy density of 14 J cm-3 and a low loss of 30% at 550 MV m-1 are achieved in the sample containing 22 wt% PEMA. This finding represents one of the effective routes to design potential dielectric polymer films for high energy storage applications. © The Royal Society of Chemistry 2012. Source

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