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Synthesis and Fluorescence Properties of a Structurally Characterized Hetero-Hexanuclear Zn(II)-La(III) Salamo-Like Coordination Compound Containing Auxiliary Ligands
摘要： A hetero-hexanuclear Zn(II)-La(III) coordination compound, [{(ZnL)2La}2(bdc)2](NO3)2 (H2bdc = terephthalic acid) has been synthesized with a symmetric Salamo-like bisoxime, and characterized by elemental analyses, IR, UV-Vis, fluorescent spectroscopy, and single-crystal X-ray diffraction analysis. All of the Zn(II) ions are pentacoordinated by N2O2 donator atoms from the (L)2? unit and one oxygen atom from one terephthalate anion. The Zn(II) ions adopt trigonal bipyramidal geometries (τZn1 = 0.61, τZn2 = 0.56). The La(III) ions are decacoordinated in the Zn(II)-La(III) coordination compound and has a distorted bicapped square antiprism geometry. Meanwhile, the photophysical property of the Zn(II)-La(III) coordination compound was also measured and discussed.
关键词： crystal structure,photophysical property,Salamo-like bisoxime,Zn(II)-La(III) coordination compound
更新于2025-09-19 17:15:36
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Structure and Electron Mobility of ScN Films Grown on α-Al2O3(1 1 ˉ 02) Substrates
摘要： Scandium nitride (ScN) films were grown on α-Al2O3(1102) substrates using the molecular beam epitaxy method, and the heteroepitaxial growth of ScN on α-Al2O3(1102) and their electric properties were studied. Epitaxial ScN films with an orientation relationship (100)ScN || (1102)α-Al2O3 and [001]ScN || [1120]α-Al2O3 were grown on α-Al2O3(1102) substrates. Their crystalline orientation anisotropy was found to be small. In addition, [100] of the ScN films were tilted along [1101] of α-Al2O3(1102) in the initial stage of growth. The tilt angle between the film growth direction and [100] of ScN was 1.4–2.0? and increased with growth temperature. The crystallinity of the ScN films also improved with the increasing growth temperature. The film with the highest Hall mobility was obtained at the boundary growth conditions determined by the relationship between the crystallinity and the nonstoichiometric composition because the film with the highest crystallinity was obtained under the Sc-rich growth condition. The decreased Hall mobility with a simultaneous improvement in film crystallinity was caused by the increased carrier scattering by the ionized donors originating from the nonstoichiometric composition.
关键词： heterostructure,electric property,scandium nitride,thin film
更新于2025-09-19 17:15:36
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Enhanced dielectric property and energy density in poly(vinylidene fluoride-chlorotrifluoroethylene) nanocomposite incorporated with graphene functionalized with hyperbranched polyethylene- <i>graft</i> -poly(trifluoroethyl methacrylate) copolymer
摘要： Polymer film capacitors are attractive as promising candidates for potential applications in compact and efficient electric power systems. The development of a method for producing a polymer nanocomposite with enhanced dielectric property and a high energy density is a fundamental solution for electric storage in a film capacitor. In this work, a hyperbranched polyethylene-graft-poly(trifluoroethyl methacrylate) (HBPE-g-PTFEMA) copolymer was synthesized to exfoliate and functionalize graphene from natural graphite in chloroform on the basis of the CH–π non-covalent stacking between the HBPE-g-PTFEMA stabilizer and graphene. Examination of the morphologies by transmission electron microscopy (TEM) and atomic force microscopy (AFM) confirmed that the resulting graphene had a lateral size of 0.2–0.6 μm and a thickness of around 4 layers. The presence of peaks due to F in the X-ray photoelectron spectroscopy (XPS) spectra of graphene indicates that the fluorinated copolymer was attached to the surface of nanosheets. Few-layer graphene was introduced into a poly(vinylidene fluoride-chlorotrifluoroethylene) (P(VDF-CTFE)) matrix via simple solution casting. The relative content of the electroactive phase in the nanocomposite film increased because the phase transition from the α- to the β-phase was induced by the addition of graphene. The dielectric constant increased to 24.8 with a low dielectric loss of 0.06 at 100 Hz for a 0.8 vol% nanocomposite, and a released energy density of 4.6 J cm?3 with a charge–discharge efficiency of 62% at 250 MV m?1 was achieved with a 0.1 vol% nanocomposite, which was attributed to the combination of the large content of the electroactive phase and interfacial polarization. This strategy based on a nanocomposite with graphene exfoliated by a fluoropolymer sheds light on the mechanism of interfacial polarization and exhibits commendable prospects for applications in flexible film capacitors.
关键词： graphene,poly(vinylidene fluoride-chlorotrifluoroethylene),hyperbranched copolymer,nanocomposite,energy density,dielectric property
更新于2025-09-19 17:15:36
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Polymeric fibers and microporous films by photo-crosslinking of triphenylene-derived liquid crystals
摘要： Two series of photoreactive discotic liquid crystals consisting of a triphenylene core and six cinnamate units with one (TPC1n) or two (TPC2n) n-alkoxy groups (CnH2n+1O; n = 10–14), respectively, as peripheral groups are synthesized. Both of them are polymerized into ?bers up to 2 mm long by UV irradiation in liquid paraf?n in the columnar LC temperature ranges. The ?ber structures seem to be preconstructed in liquid paraf?n. In addition, TPC2n are shown to form microporous ?lms up to 15 μm in diameter by simply casting the solutions of some solvents followed by drying for several minutes in air at room temperature. Photoirradiation of the ?lms in the LC temperature range converts them to polymeric ones while preserving the microporous and hexagonally ordered structure. From comparison with TPC1n and the hydrogenated derivative of TPC212, the porous ?lm-forming property is suggested to result from the combination of the double bond of the cinnamoyl group and the two long alkoxy chains on the phenyl ring.
关键词： microporous ?lm,cinnamate,self-assembly,photo-crosslinking,structure-property relations,photopolymerization,triphenylene-derived liquid crystals,?ber,membranes
更新于2025-09-19 17:15:36
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Theoretical studies on the structures, material properties, and IR spectra of polymorphs of 3,4-bis(1H-5-tetrazolyl)furoxan
摘要： Theoretical studies on the structures, densities, and heats of formation of conformational isomers of 3,4-bis(1H-5-tetrazolyl)furoxan (H2BTF) were performed based on density functional theory (DFT) calculations. Two stable planar conformational isomers, the face-to-back and the back-to-face conformers, and one stable slightly twisted conformer, the back-to-back conformer, were predicted for H2BTF at the M06-2X/6–311 + G(d,p) level of theory. The face-to-back conformer was calculated to be the most stable conformational isomer on the potential energy surface. No stable face-to-face conformer, whether planar or tilted, was identified in the calculations. The Vienna Ab Initio Simulation Package (VASP) was used in combination with molecular dynamics simulation to explore the stable crystal forms and the densities of the stable conformational isomers. Two of them exhibited high densities: the face-to-back conformer with P21 symmetry (2.01 g/cm3) and the back-to-back conformer with Pna21 symmetry (2.05 g/cm3). Their heats of formation were also predicted to be high when calculated at the same DFT level. The detonation pressures and velocities of these polymorphs, as calculated using the EXPLO5 program, are well above those of many advanced high energy density materials, pointing to the potential use of these conformers as novel explosives with good detonation performance. Also, IR spectra are shown to be able to distinguish these denser polymorphs of H2BTF. This study suggests that it could be worth investigating whether denser polymorphs of H2BTF can be grown.
关键词： 3,4-Bis(1H-5-tetrazolyl)furoxan,Detonation property,HEDM,Heat of formation,Density
更新于2025-09-19 17:15:36
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Charge transport properties in organic D-A mixed-stack complexes based on corannulene and sumanene derivatives-a theoretical study
摘要： A series of corannulene and sumanene derivatives (C-series and S-series) has been designed as organic D-A mixed-stack cocrystal complexes. The intermolecular interaction energies, frontier molecular orbitals, super-exchange electronic coupling and visualization of the orbital overlap integrals have been investigated by means of DFT method. The molecular stacking configuration in the crystal was predicted by calculating the interaction potential energy. The super-exchange mechanism has been applied to study the charge transport properties. It can be predicted that the C-series D/A complexes have potential superiority of electron transport, especially for C/C-5F. Nevertheless, the S-series D/A complexes have intrinsic electron transport weakness. Our findings can provide a better understanding of the structure-property relationship of corannulenes and sumanenes as novel D-A mixed-stack cocrystal charge-transfer systems.
关键词： charge transport property,corannulene,DFT,sumanene,D-A mixed-stack cocrystal
更新于2025-09-19 17:15:36
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Microstructure and properties of TiAlN/AlN multilayers with different modulation periods
摘要： The effects of thicknesses of AlN layer on microstructures and properties of TiAlN/AlN multilayers were studied. TiAlN/AlN multilayers had been deposited on 304 stainless steels by magnetron sputtering system. The microstructure and properties of the multilayers were characterized by X-ray diffraction, vicker hardness tester, atomic force microscopy, and friction abrasion tester. The results show that under “template effect” of TiAlN layer, AlN layer is changed into face-centered cubic and grow epitaxially with TiAlN layer. The superhardness effect could be generated in the region with sharp interface. With the thickness of AlN layer in TiAlN/AlN multilayers, the properties of multilayer are firstly increase and then decrease. When the AlN layer thickness is 3.2nm, the multilayer has excellent properties. The hardness of multilayer is 30.98GPa, the roughness of multilayer is 20.2nm, and the coefficient of friction of multilayer is 0.61.
关键词： Tribological property,Hardness,Modulation period,TiAlN/AlN
更新于2025-09-19 17:15:36
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Oxygen controlled E-beam evaporation deposited p-SnOx thin film for photosensitive devices
摘要： Thin SnOx films of different thicknesses at different oxygen pressures were deposited on glass substrate using reactive E-beam evaporation technique. Significant changes in the optical and structural properties of the films with change in oxygen pressure are observed. Experimentally obtained absorption coefficient and band gap of SnOx suggests its prospective use as suitable absorber material for photoconductive and photovoltaic devices. In addition to the oxygen pressure, thickness of SnOx layer has also an important role on its optical and structural properties.
关键词： Semiconductor,Tin oxide,Optical property,Crystal structure,Thin film
更新于2025-09-19 17:13:59
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Laser processing as a high-throughput method to investigate microstructure-processing-property relationships in multiprincipal element alloys
摘要： A direct laser deposition processing method was applied to construct compositional and microstructural libraries of AlxCoCrFeNi in an efficient and high-throughput manner. Among the compositions (x ? 0.51 e1.25) and quench rates (26e6400 K/s) studied, most of the laser deposited alloys exhibit a cellular microstructure, similar to the cast materials. The microstructural feature sizes were found to follow a power law relationship with the quench rate. The dependence of the microhardness on microstructural length scale was also investigated and observed to follow a Hall-Petch relationship. This study indicates that laser processing is an effective method for rapidly and efficiently evaluating multiprincipal element alloys and their microstructures.
关键词： Direct laser deposition,High-entropy alloys,Mechanical property,Microstructure
更新于2025-09-19 17:13:59
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[IEEE 2019 16th China International Forum on Solid State Lighting & 2019 International Forum on Wide Bandgap Semiconductors China (SSLChina: IFWS) - Shenzhen, China (2019.11.25-2019.11.27)] 2019 16th China International Forum on Solid State Lighting & 2019 International Forum on Wide Bandgap Semiconductors China (SSLChina: IFWS) - Thermal Simulations of a UV LED module with nanosilver sintered die attach process on graphene-coated copper substrates
摘要： Massive multiple-input multiple-output is a promising physical layer technology for 5G wireless communications due to its capability of high spectrum and energy efficiency, high spatial resolution, and simple transceiver design. To embrace its potential gains, the acquisition of channel state information is crucial, which unfortunately faces a number of challenges, such as the uplink pilot contamination, the overhead of downlink training and feedback, and the computational complexity. In order to reduce the effective channel dimensions, researchers have been investigating the low-rank (sparse) properties of channel environments from different viewpoints. This paper then provides a general overview of the current low-rank channel estimation approaches, including their basic assumptions, key results, as well as pros and cons on addressing the aforementioned tricky challenges. Comparisons among all these methods are provided for better understanding and some future research prospects for these low-rank approaches are also forecasted.
关键词： angle reciprocity,low-rank property,Massive MIMO,channel sparsity,channel estimation
更新于2025-09-19 17:13:59