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- 2018
- arbitrary coupling coefficients
- Dielectric resonator
- filtering
- coupler
- filtering balun
- dual-band
- dual-mode dielectric resonator (DR)
- Electronic Science and Technology
- Nantong University
- Sun Yat-Sen University
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Reorientational dynamics of organic cations in perovskite-like coordination polymers
摘要： Here we report the dynamics of organic cations as guest molecules in a perovskite host-framework. The molecular motion of CH3NH3+ (MAFe), (CH3)2NH2+ (DMAFe) and (CH3)3NH+ (TrMAFe) in the cage formed by KFe(CN)63? units was studied using a combination of experimental methods: (i) thermal analysis, (ii) dielectric and electric studies, (iii) optical observations, (iv) EPR and 1H NMR spectroscopy and (v) quasielastic neutron scattering (QENS). In the case of MAFe and TrMAFe, the thermal analysis reveals one solid-to-solid phase transition (PT) and two PTs for the DMAFe crystal. A markedly temperature-dependent dielectric constant indicates the tunable and switchable properties of the complexes. Also, their semiconducting properties are confirmed by a dc conductivity measurement. The broadband dielectric relaxation is analyzed for the TrMAFe sample in the frequency range of 100 Hz–1 GHz. QENS shows that we deal rather with the localized motion of the cation than a diffusive one. Three models, which concern the simultaneous rotation of the CH3 and/or NH3 group, π-flips and free rotations of the organic cation, are used to fit the elastic incoherent structure factor. The 1H NMR spin–lattice relaxation time for all compounds under study, as well as the second moments, has been measured in a wide temperature range. In all studied samples, the temperature dependence of the second moment of the proton NMR line indicated the gradual evolution of the molecular movements from the rigid state up to a highly disordered one.
关键词： quasielastic neutron scattering,phase transitions,perovskite,coordination polymers,dielectric properties,NMR spectroscopy,dynamics,organic cations
更新于2025-11-14 17:28:48
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Effect of HCl Cleaning on InSb-Al<sub>2</sub>O<sub>3</sub> MOS Capacitors
摘要： In this work, the role of HCl treatments on InSb surfaces and InSb-Al2O3 dielectric interfaces is characterised. X-ray photoelectron spectroscopy (XPS) measurements indicate that HCl diluted in and rinsed with isopropanol (IPA) results in a surface layer of InCl3 which is not present for similar HCl-water processes. Furthermore, this InCl3 layer desorbs from the surface between 200°C and 250°C. Metal-oxide-semiconductor capacitors (MOSCAPs) were fabricated using atomic layer deposition (ALD) of Al2O3 at 200°C and 250°C and the presence of InCl3 was associated with a +0.79 V flatband voltage shift. The desorption of the InCl3 layer at 250°C reversed this shift but the increased process temperature resulted in increased interface-trapped charge (Dit) and hysteresis voltage (VH). This shift in flatband voltage, which does not affect other figures of merit, offers a promising route to manipulate the threshold voltage of MOS transistors, allowing enhancement-mode and depletion-mode devices to be fabricated in parallel.
关键词： surface cleaning,III-V,ALD,Al2O3,InSb,dielectric interface,MOSCAP,HCl
更新于2025-11-14 17:28:48
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Effect of BaZr <sub/>0.4</sub> Ti <sub/>0.6</sub> O <sub/>3</sub> addition on electrical and magnetic properties of multiferroic (1-x)BiFeO <sub/>3</sub> -xBaTiO <sub/>3</sub> ceramics
摘要： The 0.75((1-x)BiFeO3-xBaTiO3)-0.25BaZr0.4Ti0.6O3 or 0.75(BFO-BTO)-0.25BZT ceramics (x = 0.23–0.27) have been prepared by solid state reaction method to studied the relationship between phase formation, dielectric and magnetic properties. The results found that the phase formations of calcined BFO-BTO and BZT powders are distorted rhombohedral and cubic structure, respectively. Moreover, the addition of BZT in BFO-BTO-BZT ceramics affected to the phase change dramatically according to increasing of BZT content compared to calcined BFO-BTO powders. All the samples showed cubic perovskite structure. The room temperature dielectric properties decreased with increasing of BTO content, the highest dielectric constant with low losses observed in 0.75(0.77BFO-0.23BTO)-0.25BZT ceramic. Furthermore, the ceramics displayed maximum dielectric constant temperature (Tm) above 360 °C. Interestingly, all ceramic compositions exhibited typical ferromagnetic hysteresis loop and the highest remanent magnetization observed in 0.75(0.77BFO-0.23BTO)-0.25BZT ceramic.
关键词： composite,dielectric properties,ferromagnetic hysteresis loops,BFO-BTO,BZT
更新于2025-11-14 17:28:48
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Electro-Thermal Formation of Uniform Lying Helix Alignment in a Cholesteric Liquid Crystal Cell
摘要： We demonstrated previously that the temperature of a sandwich-type liquid crystal cell with unignorable electrode resistivity could be electrically increased as a result of dielectric heating. In this study, we take advantage of such an electro-thermal effect and report on a unique electric-field approach to the formation of uniform lying helix (ULH) texture in a cholesteric liquid crystal (CLC) cell. The technique entails a hybrid voltage pulse at frequencies f1 and, subsequently, f2, which are higher and lower than the onset frequency for the induction of dielectric heating, respectively. When the cell is electrically sustained in the isotropic phase by the voltage pulse of V = 35 Vrms at f1 = 55 kHz or in the homeotropic state with the enhanced ionic effect at V = 30 Vrms and f1 = 55 kHz, our results indicate that switching of the voltage frequency from f1 to f2 enables the succeeding formation of well-aligned ULH during either the isotropic-to-CLC phase transition at f2 = 1 kHz or by the electrohydrodynamic effect at f2 = 30 Hz. For practical use, the aligning technique proposed for the first time in this study is more applicable than existing alternatives in that the obtained ULH is adoptable to CLCs with positive dielectric anisotropy in a simple cell geometry where complicated surface pretreatment is not required. Moreover, it is electrically switchable to other CLC textures such as Grandjean planar and focal conic states without the need of a temperature controller for the phase transition, the use of ion-rich LC materials, or mechanical shearing for textural transition.
关键词： cholesteric liquid crystals,uniform lying helix,dielectric heating
更新于2025-11-14 17:28:48
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Photo-rechargeable Organic-Inorganic Dye Integrated Polymeric Power Cell with Superior Performances and Durability
摘要： In present work, we propose a simple and unique approach to design a light-weight, low-cost, self-charging power cell with considerable capacity to generate and store photo-charges named as self-charged photo-power cell (SCPPC). Initially, highly electroactive sodium dodecyl sulphate (SDS) incorporated poly (vinylidene fluoride) (PVDF) composite thin films with a large dielectric constant ~ 525 are synthesized via simplistic solution casting process. Then as-prepared high dielectric SDS/PVDF thin film has been used as a charge storage medium in combination with a inorganic-organic dye film i.e. ZnO NPs-Eosin Y- polyvinyl pyrrolidone film as photoelectrons generator in our SCPPC. An open circuit voltage ~ 1.2 V is attained after charging SCPPC under illumination light with intensity ~110 mW /cm2 and then discharge fully with a constant current density ~ 4.5 mA/cm2. Specific areal capacitance ~ 450 F/m2 is obtained with a large energy and power density of ~ 90 mWh/m2 and 54 W/m2. The improved overall efficiency ~3.78 % along with 89 % storage efficiency leads to promising application possibilities of our rechargeable photo-power cell. The recyclability i.e. recharge-ability and storage durability of the photo-power cell are also checked for 35 days without no such reduction in voltage generation and storage. Also multi-coloured light emitting diodes have been lighten up using the photo-power cell as power source.
关键词： storage,PVDF,dielectric,self-charging,SDS
更新于2025-11-14 17:28:48
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High-efficiency synthesis of high-performance K0.5Na0.5NbO3 ceramics
摘要： Pure (K0.5Na0.5)NbO3 (KNN) ceramics with high density, fine and uniform-size grains were prepared by mechanochemical activation-assisted process. The time of synthesis is only 100 min, which is 72% - 93% shorter than the 6-24h of the conventional solid-state method. Compared to samples prepared by conventional solid-state method, both the microstructure evolvement and electric properties were explored in detail. Results show the electric properties was significantly improved. Moreover, the dielectric and ferroelectric properties of obtained KNN ceramics exhibit strong dependence on the crystal size of the initial powders. The optimized ceramics HKNN100 showed a quite high energy storage performance, i.e., large electric energy storage density (Wtol=1.612 J/cm3) and recoverable energy storage density (Wrec=0.431 J/cm3), which can be mainly ascribed to the large dielectric breakdown strength (DBS=110 kV/cm). Our works demonstrated that mechanochemical activation-assisted method possesses advantages for high-efficiency preparation of KNN or KNN-based ceramics.
关键词： Dielectric properties,Ferroelectricity,(K0.5Na0.5)NbO3 Ceramics,Mechanochemical activation,Microstructure
更新于2025-11-14 17:04:02
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High-Mobility Inkjet-Printed Indium-Gallium-Zinc-Oxide Thin-Film Transistors Using Sr-Doped Al2O3 Gate Dielectric
摘要： In this paper, we demonstrate high-mobility inkjet-printed indium-gallium-zinc-oxide (IGZO) thin-film transistors (TFTs) using a solution-processed Sr-doped Al2O3 (SAO) gate dielectric. Particularly, to enhance to the electrical properties of inkjet-printed IGZO TFTs, a linear-type printing pattern was adopted for printing the IGZO channel layer. Compared to dot array printing patterns (4 × 4 and 5 × 5 dot arrays), the linear-type pattern resulted in the formation of a relatively thin and uniform IGZO channel layer. Also, to improve the subthreshold characteristics and low-voltage operation of the device, a high-k and thin (~10 nm) SAO film was used as the gate dielectric layer. Compared to the devices with SiO2 gate dielectric, the inkjet-printed IGZO TFTs with SAO gate dielectric exhibited substantially high field-effect mobility (30.7 cm2/Vs). Moreover, the subthreshold slope and total trap density of states were also significantly reduced to 0.14 V/decade and 8.4 × 1011/cm2·eV, respectively.
关键词： metal-oxide semiconductors,thin-film transistors,high-k dielectric,high mobility,inkjet printing
更新于2025-11-14 15:19:41
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Direct laser writing of birefringent photonic crystals for the infrared spectral range
摘要： Infrared optical photonic crystals fabricated using direct laser writing, which is based on the two-photon polymerization of suitable monomers, have received substantial interest since the emergence of this process. Two-photon polymerization could be a disruptive technology for the fabrication of all-dielectric photonic crystals in the infrared spectral range, as it allows the synthesis of large scale arrays of uniform structures with arbitrary geometries and arrangements. However, all-dielectric photonic crystals that provide birefringent optical responses in the infrared spectral range have not yet been demonstrated using direct laser writing techniques. Here, the authors explore the form birefringence observed in photonic crystals composed of arrays of subwavelength-sized slanted polymer microwires. The photonic crystals investigated here were fabricated in a single fabrication step using direct laser writing of an infrared transparent photoresist (IP-Dip). A strong contrast of the cross-polarized re?ectance of photonic crystals as a function of the in-plane orientation is observed in the mid-infrared spectral range at λ ≈ 6:5 μm. This observation is indicative of an anisotropic optical behavior. Finite element based techniques corroborate the experimentally observed responses qualitatively.
关键词： two-photon polymerization,direct laser writing,infrared spectral range,birefringent photonic crystals,all-dielectric photonic crystals
更新于2025-11-14 15:18:02
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Silver nanoparticle-loaded filter paper: Innovative assembly method by nonthermal plasma and facile application for the reduction of methylene blue
摘要： In this study, silver nanoparticles (AgNPs) were loaded onto commercial filter paper using a simple “suspending-discharging-washing” process. Nanosecond pulse dielectric barrier discharge (NP-DBD) plasma was used to perform the in-situ reduction-loading process in a plate-to-plate DBD reactor during the five-minute fabrication process. Gaseous ethanol was used as the reducing agent under an argon gas plasma treatment. There was no thermal treatment, which prefers the formation of small nanoparticles. Transmission electron microscopy showed that the synthesized AgNPs were well-dispersed over the surface of the filter paper. The synthesized nanoparticles were hemispherical and crystalline. Fourier transform infrared spectroscopy showed that the cellulose skeletons had been mostly maintained after the plasma discharge. The catalytic activity of the AgNPs paper was evaluated by the reduction reaction of methylene blue (MB) with sodium borohydride (NaBH4) using a straightforward filtration process.
关键词： silver nanoparticles,dielectric barrier discharge,nanoparticles synthesis,nonthermal plasma
更新于2025-11-14 15:14:40
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Revealing the correlation between molecular structure and dielectric properties of carbonyl‐containing polyimide dielectrics
摘要： Polymer dielectrics with outstanding heat resistance and advanced dielectric properties are of great importance for high-temperature capacitors in the applications of hostile circumstances. In this work, a series of aromatic carbonyl-containing polyimides (CPI) are prepared from the carbonyl dianhydride and different diamines. The correlation between molecular structure (i.e., different linked structure ( O , CH2 , SO2 ) in diamines, the length of repeating unit and the linked position (para-para or meta-meta), and properties is revealed in detail to obtain CPI dielectrics with excellent thermal resistance (glass transition temperature, Tg: 241~352°C), reasonably high dielectric constant (3.99~5.23), low dissipation factor (0.00307~0.00395), and admirable breakdown strength (425~552 MV/m) simultaneously. Particularly, CPI-5 with carbonyl structure in dianhydride and sulfonyl group in diamine proves to exhibit discharged energy density and charge–discharge efficiency of 6.34 J/cm3 and 92.3% at 500 MV/m, respectively. In addition, CPI-5 also displays stable dielectric properties in temperature range of ?50?200°C. ? 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47883.
关键词： dielectric properties,films,thermal properties,polyimides
更新于2025-11-14 14:48:53