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Synthesis and investigation of structural, optical, dielectric and electronic properties of a new hybrid: [C13H21N2O2](Cd(SCN)3)
摘要： A new ferroelectric relaxor: [C13H21N2O2](Cd(SCN)3) procainium tris(thiocyanato) cadmiate(II) was synthesized and studied by single-crystal XRD. This compound crystallizes in the orthorhombic system with acentric space group Pna21. The crystal structure is formed of discrete ionic entities (C13H21N2O2)+ and [Cd(SCN)3]?. The cadmium atom has 3N3S hexa coordinated octahedral geometry. The sulfur atoms and the nitrogen atoms are in facial mode (fac). Each pair of cadmium atoms is triply bridged by μ-1,3-SCN–bridge. Consequently, a linear polymeric chain is formed. The procainium cations are bonded to these chains by hydrogen-bonding contacts and π–ring interaction. DSC measurement shows that this compound exhibits a diffuse ferro–paraelectric phase transition around 356 K. Dielectric study exhibits a relaxor behavior characterized by the transition temperature shifts toward higher temperature with the rise of frequency. This behavior was validated by the Vogel–Fulcher relationship and the modified Curie–Weiss law. The diffuseness parameter was γ = 1.96. The optical band gap Eg = 2.20 eV was estimated by diffuse reflection spectroscopy (DRS) investigation.
关键词： Ferroelectric relaxor,Structure,Conductivity,Modulus,Vogel–Fulcher model
更新于2025-09-19 17:15:36
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Nanostructuring of dense SnO2 ceramics by Spark Plasma Sintering
摘要： The spark plasma sintering (SPS) behaviour of pure SnO2 has been studied. Two different SnO2 powders have been studied: a commercial 50–200 nm one and 4–6 nm nanoparticles obtained by precipitation. It has demonstrated that it is not possible to keep pure SnO2 above 1223 K by SPS. Indeed, at 1248 K, SnO appears whereas at higher temperatures, samples are composed by SnO2 and metal Sn. Three different cycles have been developed that allow achieving high densities (≥94%). The study of the grain size shows that when the density increases the grain size increases to reach 60–70 nm for the high density samples. Therefore, SPS can be successfully used to produce dense nanostructured SnO2 ceramics without any sintering agent. Nanostructuring is very efficient to lower thermal conductivity as values as low as 6.59 and 3.99 W m?1.K?1 at 373 and 1000 K respectively, are measured in SPS nanostructured ceramics. Moreover, the transport properties of the dense ceramics are the best reported for undoped SnO2.
关键词： Spark plasma sintering,Tin oxide,Thermal conductivity,Thermoelectric,Nanostructuring
更新于2025-09-19 17:15:36
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Decomposing Electronic and Lattice Contributions in Optical Pump–X-ray Probe Transient Inner-Shell Absorption Spectroscopy of CuO
摘要： Electronic and lattice contributions to picosecond time-resolved X-ray absorption spectra (trXAS) of CuO at the oxygen K-edge are analyzed by comparing trXAS spectra, recorded using excitation wavelengths of 355 nm and 532 nm, to steady-state, temperature-dependent XAS measurements. The trXAS spectra at pump-probe time-delays ≥150 ps are dominated by lattice heating effects. Insight into the temporal evolution of lattice temperature profiles on timescales up to 100’s of nanoseconds after laser excitation are reported, on an absolute temperature scale, with a temporal sensitivity and a spatial selectivity on the order of 10’s of picoseconds and 10’s of nanometers, respectively, effectively establishing an 'ultrafast thermometer'. In particular, for the 532 nm experiment at ~5 mJ/cm2 fluence, both the initial sample temperature and its dynamic evolution are well captured by a one-dimensional thermal energy deposition and diffusion model. The thermal conductivity k = (1.3±0.4) W m–1 K–1 derived from this model is in good agreement with the literature value for CuO powder kpowder = 1.013 W m–1 K–1. For 355 nm excitation, a quantitative analysis of the experiments is hampered by the large temperature gradients within the probed sample volume owing to the small UV penetration depth. The impact of the findings on mitigating or utilizing photoinduced lattice temperature changes in future X-ray free electron laser (XFEL) experiments is discussed.
关键词： X-ray absorption spectroscopy,Ultrafast X-ray spectroscopy,CuO,lattice heating,thermal conductivity
更新于2025-09-19 17:15:36
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Enhancing the structural, optical and electrical properties of ZnO nanopowders through (Al+Mn) doping
摘要： Undoped ZnO and Zn0.97-xAl0.03MnxO (x = 0, 1, 2 and 3%) nanopowders (NPs) were synthesized by co-precipitation method. They were characterized by X-ray diffraction (XRD), Fourier transformed infrared (FTIR), Raman, UV-visible, photoluminescence (PL) and impedance spectroscopies. All samples exhibit a single phase wurtzite type. The average crystallite size lying between 22 and 42 nm was found to increase for all doped ZnO samples. The optical transmission in the visible region was improved due to doping. The optical band gap is in the range of 3-3.4 eV and was found to decrease up to 2% of Mn content but slightly increases with further doping. All PL spectra exhibit two emission peaks in UV and visible regions. The deconvolution of the visible emission peak reveals different emissions for all samples. An additional yellow emission is noticed for (Al+Mn) ZnO doped samples suggesting that the incorporation of aluminum and manganese in the zinc oxide host lattice enhances luminescence properties of ZnO. The ac conductivity (σac) was found to follow Jonscher’s power law and was improved with doping. Cole-Cole plots of all samples were suitably fitted to a circuit consisting in a parallel combination of a resistance and a constant phase element (CPE).
关键词： optical properties,XRD,doping,conductivity,ZnO nanopowder
更新于2025-09-19 17:15:36
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Phonon scattering by dislocations in GaN
摘要： Crystal imperfections such as dislocations strongly influence the performance and thermal transport behavior of GaN-based devices. We show that the experimental data used to parameterize the effect of dislocations on the thermal conductivity can be explained using only the reported film thickness and point defect concentrations. The analysis highlights the boundary-scattering-governed reduction of thermal conductivity in GaN, which had been underestimated in earlier models. To quantify the influence of dislocations on the thermal transport in GaN, we adopt a Green’s function approach based on accurate ab-initio interatomic force constants. While calculations at the level of density functional theory are necessary for 3-phonon and point defect scattering, we show that scattering due to dislocations can be satisfactorily approximated using semiempirical potentials. This makes the Green’s function approach to dislocation scattering a quantitatively predictive, yet computationally practical, method for obtaining detailed phonon scattering rates.
关键词： Dislocation,Phonon Scattering,Density Functional Theory,GaN,Thermal Conductivity
更新于2025-09-19 17:15:36
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Silver Nanowire Ink for Flexible Circuit on Textiles
摘要： Low cost electronics implemented in textiles could pave the way to a fully new generation of smart products in the fields of healthcare, sport, fashion, and safety. Although many methods have found their way into the market, many problems still need to be solved and much progress has to be made to enable the commercial exploitation of such products. In this paper, silver nanowires of 60–100 nm in diameter and 8–15 μm in length were achieved by the polyol solvothermal method, and aqueous silver nanowire conductive inks were prepared with the synthesized silver nanowires as the conductive phase, in the presence of polyaniline, guar, and hydrochloric acid. The conductive inks were printed on cotton fabric substrate by screen printing process. The effects of the amount of silver nanowires, layers of coating, and treatment temperature on the microstructure and electrical properties of samples were investigated by scanning electron microscopy and the four-point probe method. The results show that the conductivity and densification of the samples increased with increased amount of silver nanowires, layers of coating, and treatment temperature. The heat treatment helped to improve densification of the silver nanowires and conductivity of the sample. The resistance of the samples increased after bending due to loosening of the overlap between the silver nanowires.
关键词： conductive coating,silver nanowires,textile,conductivity
更新于2025-09-19 17:15:36
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Rapid fabrication of silver nanoparticle/polydopamine functionalized polyester fibers
摘要： In this paper, silver nanoparticles functionalized poly(ethylene terephthalate) (PET) fibers with antimicrobial activity, electrical conductivity and good coating stability are reported. Firstly, silver plated PET fibers were fabricated by rapid polydopamine (PDA) modification followed by electroless plating. Secondly, the surface morphologies and compositions of PDA modified and silver coated PET fibers were characterized by employing scanning electron microscopy, atomic force microscopy, X-ray diffraction and energy dispersive spectrometry. Finally, the antimicrobial properties and electrical conductivity of the silver plated PET fibers were investigated. The results showed that the silver coated PET fibers exhibited excellent antimicrobial activity to both Escherichia coli and Staphylococcus aureus (with an antimicrobial efficiency of 100 and 99.99%, respectively), and that the antimicrobial activity was well maintained after washing. The silver coated PET fibers showed electrical resistance of 0.76 Ω per 1 cm, indicating good conductivity. It was also demonstrated that the silver layer that formed had good mechanical durability, as indicated by conductivity measurements during tensile loading and observation of the surface morphology of the fibers under various modes of deformation.
关键词： silver nanoparticles,electrical conductivity,antimicrobial,PET fibers,polydopamine
更新于2025-09-19 17:15:36
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Fabrication of Chromatic Electronic Textiles Synthesized by Conducting Polymer
摘要： Most of the electronic textiles (e-textiles) were fabricated by carbon-based materials such as graphene, carbon nanotube (CNT), and hybrids of graphene and CNTs due to their high electrical conductivity, flexibility, and good stability. However, it is difficult to synthesize a colored e-textiles because the carbon-based e-textiles have only a black color. In this study, we produced the chromatic e-textiles synthesized with different conductive polymer such as polyaniline, polythiophene, and poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate). The chromatic e-textiles were simply fabricated by soaking commercial cotton into an aqueous conductive polymer solution. The chromatic e-textiles were characterized by scanning electron microscopy, X-ray photoelectron spectroscopy, and Fourier transform infrared spectroscopy. The electrical conductivity of the chromatic e-textiles was the order of 10?3 S/cm, which was maintained even under bending.
关键词： Electronic textiles,Electrical conductivity,Conductive polymer
更新于2025-09-19 17:15:36
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Optical characterization of Peierls instability of zigzag-edge phosphorene nanoribbons
摘要： It has been demonstrated that the bare zigzag-edge phosphorene nanoribbons (zPNRs) were regularly believed as metals. However, some first-principle work [EPL108, 47005 (2014); PRB94, 075422 (2016)] suggested that zPNRs could be Peierls-gapped semiconductor due to the edge-reconstructions. In this work, we study the optical characterization of edge-Peierls-instability (EPI) in zPNRs based on the tight-binding calculations. Responding to EPI, an additional infrared absorption can be observed in the polarized-optical-conductivity-spectrum which is resonant to the Peierls gap. This new peak could be either singlet or doublet, which is determined by the ribbons embracing even- or odd-number zigzag chains. Moreover, it is unraveled that the opening of the Peierls gap is intimately related to the formation of the isolated edge-state subbands near the Fermi level.
关键词： Optical conductivity spectrum,Peierls instability,Tight-binding calculations,Zigzag-edge phosphorene nanoribbons
更新于2025-09-19 17:15:36
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Capacitance–Resistive PEDOT:PSS Cotton Fabric Satisfied Jonscher’s Law with Index Exceeding One
摘要： Jonscher’s law is investigated in the context of PEDOT:PSS impregnated conductive cotton fabric for frequencies from 10 Hz to 13 MHz and temperatures from 30°C to 100°C using complex impedance spectroscopy. The drop-casting and drying method was used to prepare samples of conductive cotton fabric with low and high concentrations of dopant. Argand plots of the ratio of AC–DC conductivities of the conductive fabric demonstrated the presence of reactance at high frequencies at each concentration of dopant. Regression analysis demonstrated that Jonscher’s power law was obeyed over a significant range of high frequencies. The hopping frequency and Jonscher index are found to depend on the concentration of dopant, but are insensitive to temperature over the range used in this study. By contrast with numerous experimental studies reporting that the Jonscher index is less than one, this experimental investigation found that Jonscher’s index exceeded one. We further investigated whether or not the hopping frequency identified by regression corresponded to a natural frequency arising in the Argand plot of the complex conductivity ratio. Considerations of curvature and phase angle identified two candidate frequencies, but neither was close to the hopping frequency identified by regression.
关键词： capacitance,Argand,regression,conductivity,Cotton
更新于2025-09-19 17:15:36