Discrete Conjugated Porphyrin Tapes with an Exceptionally Small Bandgap

An Ag^I‐promoted meso–meso coupling reaction has been extended to prepare discrete 100 nm long linear arrays of porphyrins. Oxidation of the resulting phenyl end‐capped meso–meso linked porphyrins using a combination of 2,3‐dichloro‐5,6‐dicyano‐1,4‐benzoquinone (DDQ) and Sc^III(OTf)₃ directly produces fully π‐conjugated fused porphyrin arrays (porphyrin tapes) of 10 nm molecular size. This research news article presents their synthesis, X‐ray crystal structures, and optical and electronic properties. Among these, the extremely small highest occupied molecular orbital–lowest unoccupied molecular orbital (HOMO–LUMO) optical gaps that reach into the infrared region suggest many applications of these compounds in materials science.     

A novel polymer electrolyte based on polydioxolane polyurethane with Na+ single‐ionic conductivity

A series of novel polyurethane ionomers with polydioxolane (PDXL) as soft segment was prepared and characterized by Fourier transform infrared spectroscopy, differential scanning calorimetry, and dynamic mechanical analysis. The ionomers obtained were Na⁺ single‐ionic conductors. Their ionic conductivity and water absorption were tested. At medium temperature (> 75°C), the conductivity of ∼ 10⁻⁵ s cm⁻¹ was reached. The temperature dependence of conductivity could not be well expressed by both Arrhenius and VTF equations. When ionization level was fixed, the conductivity increased as the Mn of PDXL decreased. We also discussed the effect of ionization level on water absorption. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 1711–1719, 1999     

大截面分割导体的结构设计与制造

为满足500 kV交联聚乙烯绝缘超高压电力电缆的研制需要,在总结多次大截面分割导体(800 mm2及以上)结构设计与制作经验的基础上,已顺利完成了1 200,2 500 mm2分割导体的制作,本文以1 200 mm2分割导体的结构设计、制造为例,介绍了大截面分割导体结构设计与制造。     

Highly textured Gd2Zr2O7 films grown on textured Ni-5 at.%W substrates by solution deposition route: Growth, texture evolution, and microstructure dependency

Growth, texture evolution and microstructure dependency of solution derived Gd₂Zr₂O₇ films deposited on textured Ni-5 at.%W substrates have been extensively studied. Influence of processing parameters, in particular annealing temperature and dwell time, as well as thickness effect on film texture and morphology are investigated in details. It is found that a rotated cube-on-cube epitaxy of Gd₂Zr₂O₇< 110>//NiW<100> in-plane texture forms as soon as the (004) out-plane texture appears, implying that epitaxial growth dominates the crystallization processes. Thermal energy plays an important role in minimizing the difference of interfacial energy along two directions in the anisotropic metallic substrate. Growth of Gd₂Zr₂O₇ films displays an ultrafast kinetics under optimized conditions. Independency of sharp epitaxial (004) and polycrystalline (222) orientation is revealed from further synchrotron diffraction studies. Fully covered films with a broad thickness range exhibit a high degree of biaxial orientation, similar surface morphology with crack free and nano-size grains microstructure, seemingly independent of neither heat treatment nor thickness. Particularly, we compared the porosity of the film surface and body according to surface or cross-sectional observation and Rutherford Backscattering Spectrometry analysis, pointing to inhomogeneous structure through film thickness, i.e., dense in the surface layer but porous in the body. This is attributed to trapped gas generated during either decomposition or crystallization in the thicker films. This work not only demonstrates a route for producing textured Gd₂Zr₂O₇ buffer layers with dense structure directly on technical substrates, but also provides some fundamental understandings related to chemical solution derived films grown on metallic substrates.     

结冰分裂导线舞动振幅分析

针对结冰分裂导线舞动问题,从功能的角度提出了一种舞动振幅的分析方法。导出了舞动振幅经历一个周期增量的表达式。所导出的舞动振幅增量的表达式说明了作用在结冰分裂导线上的气动力的各项在舞动振幅不同阶段的作用。得到的结论是:当舞动的振幅较小时,气动力中常数项与线性项的功是气动力总功中的主要部分;当舞动的振幅为中等时,气动力中常数项与线性项的功与非线性项的功在气动力总功中的比例相近;当舞动的振幅为较大时,气动力中非线性项的功在气动力总功中的比例大于常数项与线性项的功在气动力总功中的比例。     

Novel Nd2WO6-type Sm2−xAxM1−yByO6−δ (A = Ca, Sr; M = Mo, W; B = Ce, Ni) mixed conductors

In the present work, we have explored novel Nd₂WO₆-type structure Sm_2−xA_xM_1−yB_yO_6−δ (A = Ca, Sr; M = Mo, W; B = Ce, Ni) as precursor for the development of solid oxide fuel cells (SOFCs) anodes. The formation of single-phase monoclinic structure was confirmed by powder X-ray diffraction (PXRD) for the A- and B-doped Sm₂MO₆ (SMO). Samples after AC measurements under wet H₂ up to 850 °C changed from Nd₂WO₆-type structure into Sm₂MoO₅ due to the reduction of Mo^VI that was confirmed by PXRD and is consistent with literature. The electrical conductivity was determined using 2-probe AC impedance and DC method and was compared with 4-probe DC method. The total electrical conductivity obtained from these two different techniques was found to vary within the experimental error over the investigated temperature of 350-650 °C. Ionic and electronic conductivity were studied using electron-blocking electrodes technique. Among the samples studied, Sm_1.8Ca_0.2MoO_6−δ exhibits total conductivity of 0.12 S cm⁻¹ at 550 °C in wet H₂ with an activation energy of 0.06 eV. Ca-doped SMO appears to be chemically stable against reaction with YSZ electrolyte at 800 °C for 24 h in wet H₂. The ionic transference number (t_i) of Sm_1.9Ca_0.1MoO_6−δ in wet H₂ at 550 °C (pO₂ = 10^−25.5 atm) was found to be about 0.012 after subtraction of electrical lead resistance from the 2-probe AC data and showed predominate electronic conductors.     

Nanostructured membranes and electrodes with sulfonic acid functionalized carbon nanotubes

Herein we report the covalent functionalization of multiwall carbon nanotubes by grafting sulfanilic acid and their dispersion into sulfonated poly(ether ether ketone). The nanocomposites were explored as an option for tuning the proton and electron conductivity, swelling, water and alcohol permeability aiming at nanostructured membranes and electrodes for application in alcohol or hydrogen fuel cells and other electrochemical devices. The nanocomposites were extensively characterized, by studying their physicochemical and electrochemical properties. They were processed as self-supporting films with high mechanical stability, proton conductivity of 4.47 × 10⁻² S cm⁻¹ at 30 °C and 16.8 × 10⁻² S cm⁻¹ at 80 °C and 100% humidity level, electron conductivity much higher than for the plain polymer. The methanol permeability could be reduced to 1/20, keeping water permeability at reasonable values. The ratio of bound water also increases with increasing content of sulfonated filler, helping in keeping water in the polymer in conditions of low external humidity level.