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Chemical Research in Chinese Universities 2015年第1期31卷 123-129页

作者： ZHANG Hui SHANG Yan CHEN Qingguo HAN Baozhong Key Laboratory of Engineering dielectrics and Its Application of Ministry of Education College of Chemical and Environmental Engineering Harbin University of Science and Technology Harbin 150080 P. R. China

A theoretical investigation on the dielectric insulation mechanism of sulfur hexafluoride（SF6） and its potential alternative gases at the atomic and molecular levels was made. The electronic structures of the molecules of them were calculated at the B3LYP/6-31 11＋G（d,p） level. The HOMO-LUMO energy gaps, ionization potentials, electron affinities, and dipole moments of the studied molecules at the ground state were obtained. The 11 isomerization reactions, with the harmonic vibration frequencies of the equilibrium geometries and the minimum energy path by the intrinsic reaction coordinate theory, were also obtained at the same level. The results show that the insulation gas, with the larger HOMO-LUMO energy gap, the higher ionization potential and the stronger electron affinity, can increase the dielectric breakdown strength efficiently, which is in good agreement with the available experimental finding. We suggested that the molecule with isomerization reaction occurring can dissipate the energy of hot electrons availably, which is favorable to the dielectric breakdown strength increasing for the SF6 potential alternative gas.

关键词： Dielectric breakdown strength Sulfur hexafluoride Transition state Mechanism

Spoof surface plasmons resonance effect and tunable electric response of improved metamaterial in the terahertz regime

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Chinese physics B 2015年第12期24卷 483-487页

作者：王玥张丽颖梅金硕张文超童一静 Department of Electrical Science and Technology Harbin University of Science and Technology Key Laboratory of Engineering dielectrics and Its Application Ministry of EducationHarbin University of Science and Technology School of Engineering and Applied Science George Washington University

We propose an improved design and numerical study of an optimized tunable plasmonics artificial material resonator in the terahertz regime. We demonstrate that tunability can be realized with a transmission intensity as much as - 61% in the lower frequency resonance, which is implemented through the effect of photoconductive switching under *** the higher frequency resonance, we show that spoof surface plasmons along the interface of metal/dielectric provide new types of electromagnetic resonances. Our approach opens up possibilities for the interface of metamaterial and plasmonics to be applied to optically tunable THz switching.

关键词： surface plasmons metamaterials terahertz resonance

Structural and AC electrical properties study of solid metal urea complexes

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Journal of Advanced dielectrics 2018年第2期8卷 60-66页

作者： Ragab Mahani Saleh D.Mekky Badr A.El Sayed Gamal S.EL-Bahy Azza Ward microwave physics and dielectrics Department National Research Centre 33 EL Bohouth St.(former EL Tahrir St.)Giza-Egypt-P.O.12622 Chemistry Department Faculty of ScienceAlazhar University Nasr CityCairoEgypt Spectroscopy Department National Research Centre 33 EL Bohouth St.(former EL Tahrir St.)Giza-Egypt-P.O.12622

The complexation of solid urea with(Co^(2+)),(Cu^(2+))or(Ni^(2+))ions has been studied by using dielectric spectroscopy technique over a wide frequency range at different temper ***'structure were investigated by XRD,FTIR and FT-Raman *** and Raman analy sis indicated that the urea coordinates with the metal atoms through the same oxygen-metal bond(O-M).Furthermore,XRD analysis showed that the samples have polycrystalline structure with single *** pemittivity of complexes was found at much higher values than that of the ligand(pure urea),showing structure ***,two relaxation peaks were observed in the dielectric loss spectra corresponding to the orientation po larization of urea molecule,and some parts of urea molecule may be NH2 *** relaxation peaks correspond to thermally activated because they were shifted to higher frequency with the temperature *** peak position for the low frequency relaxation peak was observed lht the same relaxation time(τ=7.6× 10^(-4) s),corresponding to the coordination mode through the same O-M *** of this work is the successful finding of the relationship between the crystalline phase,coordination mode and the dy namic molecular behavior of solid urea and its complexes using the dielectric spec-troscopy techn ique.

关键词： Urea complexes IR XRD permitivity

Top-gated graphene field-effect transistors on SiC substrates

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Chinese Science Bulletin 2012年第19期57卷 2401-2404页

作者： MA Peng JIN Zhi GUO JianNan PAN HongLiang LIU XinYu YE TianChun JIA YuPing GUO LiWei CHEN XiaoLong Department of microwave IC Institute of MicroelectronicsChinese Academy of SciencesBeijing 100029China Research&Development Center for Functional Crystals Beijing National Laboratory for Condensed Matter PhysicsInstitute of PhysicsChinese Academy of SciencesBeijing 100190China

We report on a demonstration of top-gated graphene field-effect transistors(FETs) fabricated on epitaxial SiC *** stacks,benzocyclobutene and atomic layer deposition Al2O3,are used as the gate dielectrics to maintain intrinsic carrier mobility of *** graphene FETs exhibit n-type transistor characteristics and the drain current is nearly linear dependence on gate and drain *** a low field-effect mobility of 40 cm2/(V s),a maximum cutoff frequency of 4.6 GHz and a maximum oscillation frequency of 1.5 GHz were obtained for the graphene devices with a gate length of 1 μm.

关键词： graphene radio frequency(RF) field-effect transistor(FET) SiC

Large spatial shifts of reflected light beam off biaxial hyperbolic materials

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Chinese physics B 2023年第11期32卷 465-471页

作者：沈加国哈思内恩宋浩元周胜付淑芳王选章王暄张强 Key Laboratory for Photonic and Electronic Bandgap Materials Chinese Ministry of Educationand School of Physics and Electronic EngineeringHarbin Normal UniversityHarbin 150025China School of Integrated Circuits Engineering Research Center for Functional CeramicsWuhan National Laboratory for OptoelectronicsHuazhong University of Science and TechnologyWuhan 430030China Key Laboratory of Engineering dielectrics and Its Application Ministry of EducationHarbin University of Science and TechnologyHarbin 150080China

Many optical systems that deal with polarization rely on the adaptability of controlling light reflection in the lithography-free nanostructure. In this study, we explore the Goos–H?nchen(GH) shift and Imbert–Fedorov(IF) shift in a biaxial hyperbolic film on a uniaxial hyperbolic substrate. This research statistically calculates and analyzes the GH shift and IF shift for the natural biaxial hyperbolic material(NBHM). We select the surface with the strongest anisotropy within the NBHM and obtain the complex beam-shift spectrum. By incorporating the NBHM film, the GH shift caused by a transversely magnetic incident-beam on the surface increases significantly compared with that on the uniaxial hyperbolic material. The maximum of GH shift can reach 86 λ0at about 841 cm-1when the thickness of NBHM is 90 nm, and the IF shift can approach 2.7 λ0for a circularly-polarized beam incident on a 1700-nm-thick NBHM. It is found that the spatialshift increases when a highly anisotropic hyperbolic polariton is excited in hyperbolic material, where the shift spectrum exhibits an oscillating behaviour accompanied with sharp shift peak(steep slope). This large spatial shift may provide an alternative strategy to develop novel sub-micrometric optical devices and biosensors.

关键词： Goos-Hanchen shift Imbert-Fedorov shift α-MoO_(3)

Doping effect of SrZrO_(3) on KNLN ceramics structure and their dielectric properties

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Journal of Advanced dielectrics 2018年第5期8卷 28-34页

作者： Emad Ewais Ragab Mahani Samy Mostafa Adel Ahmedx Refractory and Ceramic Materials Division(RCMD)Central Metallurgical R&D Institute P.O.87 Helwan 11421 CairoEgypt microwave physics and dielectrics Department National Research Centre 33 EL Bohouth st.(former EL Tahrirst.)P.O.12622 GizaEgypt Tabbin Institute for Metallurgical Studies(TIMS)P.O.109 Helwan 11421 CairoEgypt Chemistry Department Helwan University HelwanCairoEgypt

In this work,lead-free systems;(1-x)(K_(0.465)Na_(0.465)Li_(0.07))NbO_(3)–xSrZrO_(3)(x=0,0.005,0.050,0.095 and 0.14)were synthesized by the conventional solid-state reaction ***,SEM,densification parameter as well as dielectric parameters of the obtained KNLN ceramics were *** analysis showed the formation of orthorhombic perovskite structure in all investigated ***_(3)(SZ)inhibited the grain growth and increased the distribution of grains uniformly in the micro*** addition,SZ changed the crystalline system of KNLN ceramics *** a consequence,the permittivity,dielectric loss as well as AC conductivity decreased *** ceramics of x=0.005 are characterized by low conductivity(10-10 S/cm),low dielectric loss(0.005)and relatively high permittivity(34).They can be useful for the electrical capacitors fabrication and filtering out noise from signals in resonant *** frequencies lower than 105 Hz,DC conductivity and separation of the charges at the interfaces were found to dominate the electrical behavior of ceramics,whereas at higher frequencies,a faster or dipole polarization may become more dominated.A broad peak has been observed in the imaginary part of electric modulus revealing to the non-Debye dielectric relaxation *** mechanical tunneling(QMT)was found to be the most suitable to characterize the electrical conduction mechanism in the ceramic compounds.

关键词： Lead-free ceramics KNLN dielectric properties.

Long-range surface plasmon polaritons with subwavelength mode expansion in an asymmetrical system

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Chinese physics B 2009年第8期18卷 3535-3541页

作者：陈建军李智龚旗煌 State Key Laboratory for Mesoscopic physics and Department of physics Peking University

Long-range surface plasmon polariton （LRSPP） modes in an asymmetrical system, in which the thin metal film is sandwiched between a semi-infinite substrate and a high permittivity polymer film with a finite thickness, are theoret~ ically calculated and analyzed. Due to the high permittivity of the polymer film, at proper polymer film thicknesses, the index-matching condition of the dielectrics at both sides of the metal can be satisfied for supporting LRSPP modes, and the electromagnetic field above the metal can be localized well. It is found that these LRSPP modes have both long propagation lengths and subwavelength mode expansion above the metal at the optimal polymer film thickncsses. Furthermore, the requirements on the refractive index and the thickness of the polymer film to support LRSPP modes at the optimal thicknesses are found to be not critical.

关键词： surface plasmon polaritons field intensity confinement long propagation length integrated optics

Melt-spun thin ribbons of shape memory TiNiCu alloy for micromechanical applications

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International Journal of Smart and Nano Materials 2011年第2期2卷 68-77页

作者： A.V.Shelyakov N.N.Sitnikov V.V.Koledov D.S.Kuchin A.I.Irzhak N.Yu.Tabachkova Department of Solid State physics and Nanosystems National Research Nuclear University“MEPhI”Kashirskoe shosse 31115409 MoscowRussian Federation Department of physics of Magnetic Phenomena Kotelnikov Institute of Radio-Engineering and Electronics of Russian Academy of SciencesMohovaya st.11/7125009 MoscowRussian Federation Department of Material Science of Semiconductors and dielectrics National University of Science and Technology“MISiS”Leninsky prospect 4119049 MoscowRussian Federation

The development of micromechanical devices(MEMS and NEMS)on the basis of nanostructured shape memory alloys is reported.A Ti_(50)Ni_(25)Cu_(25)(at.%)alloy fabricated by the melt spinning technique in the form of a ribbon with a thickness around 40µm and a width about 1.5 mm was chosen as a starting *** parameters were optimized to produce the alloy in an amorphous *** thickness of the ribbon was reduced to 5–14µm by means of electrochemical polishing.A nanostructural state of the thin ribbons was obtained via the dynamic crystallization of the amorphous alloy by application of a single electric pulse with duration in the range of 300–900µs.A microtweezers prototype with a composite cantilever of 0.8µm thick and 8µm long was developed and produced on the basis of the obtained nanostructured thin ribbons by means of the focused ion beam *** deformation of the micromanipulator was achieved by heating using semiconductor laser radiation in a vacuum chamber of scanning ion-probe microscope.

关键词： melt-spun ribbon shape memory alloy composite micromanipulator microtweezers

Theoretical investigation of structural and optical properties of semi-fluorinated bilayer graphene

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Chinese physics B 2016年第3期25卷 357-361页

作者：伞晓娇韩柏赵景庚 Natural Science Research Center Academy of Fundamental and Interdisciplinary Sciences Harbin Institute of Technology Harbin 150080 China Key Laboratory of Engineering dielectrics and Its Application Ministry of Education Harbin University of Science and Technology Harbin 150080 China College of Electrical & Electronic Engineer Harbin 150080 China

We have studied the structural and optical properties of semi-fluorinated bilayer graphene using density functional theory. When the interlayer distance is 1.62A, the two graphene layers in AA stacking can form strong chemical bonds. Under an in-plane stress of 6.8 GPa, this semi-fluorinated bilayer graphene becomes the energy minimum. Our calculations indicate that the semi-fluorinated bilayer graphene with the AA stacking sequence and rectangular fluorinated configuration is a nonmagnetic semiconductor （direct gap of 3.46 eV）. The electronic behavior at the vicinity of the Fermi level is mainly contributed by the p electrons of carbon atoms forming C=C double bonds. We compare the optical properties of the semi- fluorinated bilayer graphene with those of bilayer graphene stacked in the AA sequence and find that the semi-fluorinated bilayer graphene is anisotropic for the polarization vector on the basal plane of graphene and a red shift occurs in the [010] polarization, which makes the peak at the low-frequency region located within visible light. This investigation is useful to design polarization-dependence optoelectronic devices.

关键词： bilayer graphene fluorinated configuration optical properties density functional theory

Surface plasmon polaritons of symmetric and asymmetric metamaterial slabs

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Chinese physics B 2010年第2期19卷 439-449页

作者：张惠芳曹迪陶峰杨希华王燕阎晓娜白丽华 Department of physics Shanghai University

The p and s-polarized surface plasmon polaritons （SPPs） of symmetric and asymmetric slabs formed arbitrarily by four types of conventional materials： dielectrics, negative dielectric permittivity materials, negative magnetic permeability materials, and left-handed materials are comprehensively analysed. The existence regions, dispersion relations, and excitation of SPPs in different frequency regions are investigated in detail. For symmetric slabs, the numbers and the frequency positions of surface polariton branches are quite different. At the same time, the pairs of the p or s-polarized SPP branches occur in the same frequency range. For asymmetric slabs, the SPP branches in mid- and high-frequency ranges are greatly different. In addition, the slab thickness has a great effect on SPPs of asymmetric and symmetric slabs. The attenuated total reflection spectra for the cases of p and s polarizations in these slabs are also calculated.

关键词： surface plasmon polaritons meta-materials symmetric and asymmetric slabs attenuated total reflection technique