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Low Dielectric Poly(imide siloxane) Films Enabled by a Well-Defined Disiloxane-Linked Alkyl Diamine
摘要： This paper presents an e?cient pathway to achieve the dielectric constant as low as 2.48 @ 25 °C, 1 MHz for nonporous poly(imide siloxane) ?lms with mechanical and thermal robustness. A symmetric disiloxane-linked alkyl diamine, bis(aminopropyl)tetramethyldisiloxane (BATMS) with a well-de?ned molecular formula NH2CH2CH2CH2Si-(CH3)2OSi(CH3)2CH2CH2CH2NH2, has been used to controllably reduce the dielectric constant of the polymer ?lms by adjusting the loading of BATMS. The thermal stability of all the polymer ?lms remains robust with T5 and T10 no less than 458 and 472 °C, respectively, while the glass-transition temperature decreases with increasing incorporation of ?exible disiloxane-alkyl segments into a polymer backbone. There exists a consistent regularity between the thermal, optical, and dielectric properties with the loading amount of BATMS in the polymer ?lms, inferring that the disiloxane-alkyl segments are homogeneously distributed in the polymer backbone. Charge-transfer complex inhibition of polymer ?lms by disiloxane segments has been revealed by an enlarged d-spacing in wide-angle X-ray di?raction spectra and a blue shift in ?lm ?uorescence emission spectra. The combined low dielectric constant, robust mechanical and thermal stability, and improved hydrophobicity make the series of BATMS-resulting poly(imide siloxane) ?lms promising candidates for sophisticated ?exible microelectronic application.
关键词： BATMS,dielectric constant,thermal stability,poly(imide siloxane),charge-transfer complex
更新于2025-09-12 10:27:22
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Backbone Fluorination of Polythiophenes Improves Device Performance of Non-Fullerene Polymer Solar Cells
摘要： Polythiophenes (PTs) are promising donor materials for the industrialization of polymer solar cells (PSCs) due to the merits of easy synthesis, low cost, and large-scale producibility. The rapid progress of non-fullerene acceptors requires the development of new PTs for use in non-fullerene PSCs. In this work, we present a set of PTs with different degree of backbone fluorination (P6T-F00, P6T-F50, P6T-F75, and P6T-F100) to investigate the effect of fluorination on the photovoltaic properties of PTs in non-fullerene PSCs. Upon increasing fluorine content, the PTs tend to have higher crystallinity, higher absorption coefficients, and enhanced relative dielectric constants. When blended with a non-fullerene acceptor EH-IDTBR, the blend films show increased photoluminescence quenching efficiency, reduced charge recombination loss, and extended charge carrier lifetime along with increasing fluorine content of PTs. These positive factors collectively result in dramatically improved power conversion efficiency from 4.3% for P6T-F00:EH-IDTBR to 7.3% for P6T-F100:EH-IDTBR, which is superior to the champion binary non-fullerene PSCs based on P3HT. Our results demonstrate that PTs are promising donor materials for non-fullerene PSCs via backbone fluorination.
关键词： polythiophenes,polymer solar cells,backbone fluorination,dielectric constant,non-fullerene acceptors
更新于2025-09-11 14:15:04
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[IEEE 2019 IEEE 2nd Ukraine Conference on Electrical and Computer Engineering (UKRCON) - Lviv, Ukraine (2019.7.2-2019.7.6)] 2019 IEEE 2nd Ukraine Conference on Electrical and Computer Engineering (UKRCON) - Study of Perspective of Gaseous Dielectric Parameters Monitoring with Use of Coupled Biconical Resonators
摘要： The advantages of using coupled biconical resonators for monitoring the parameters of gaseous dielectrics are considered in the paper. In this case, one of the resonators is the reference one. Application of coupled biconical resonators makes it possible to detect deviations of the dielectric constant and loss tangent of the test medium with values of the order of 10-4 and 10-5 correspondingly.
关键词： coupled resonators,Q-factor,biconical resonator,resonance frequency,the complex dielectric constant
更新于2025-09-11 14:15:04
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Design and Analysis of Alphabetical Slots of Patch Antenna for Mobile Optical Communication at 60?GHz
摘要： In the last decade, huge development has been seen in the field of wireless communication. The performance depends on the shape and size of the antenna. The future aim of wireless communication is to provide data with high speed data range even in harsh geographical areas. Here aim is to design and compare the E and H slot, T-slot, O-slot and U-slot antenna. The designed patch antenna operates at a frequency of 60 GHz with maximum antenna gain and minimum radiation loss using high frequency structure simulator (HFSS). We will use Rogers RT/duroid 5880 as substrate due to its suitable mechanical and insulating properties. Resonant frequency used will be 60 GHz and height will be 1.6 mm, 1.57 mm, 1.6 mm and 0.508 mm for E and H slot, T-slot, O-slot and U-slot, respectively.
关键词： dielectric constant,millimeter frequency,microstrip patch antenna,substrate
更新于2025-09-11 14:15:04
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Local valence electronic states of silicon (sub)oxides on HfO2/Si-(sub)oxide/Si(110) and HfSi2/Si-(sub)oxide/Si(110) Islands
摘要： The effect on the local valence electronic states of Sin+ suboxide components (n = 2, 3, and 4) of hafnium deposited on a low-index Si(110) substrate is investigated by Si-L23VV Auger electron Sin+-2p photoelectron coincidence spectroscopy (Si-L23VV-Sin+-2p APECS), and the chemical states and stabilities are discussed. Hafnium-covered Si(110) is immediately oxidized to HfO2 and SiO2 because hafnium serves as an effective catalyst for Si oxidation. Therefore, a HfO2/Sin+-(sub)oxide/Si(110) [HfO2/Sin+/Si(110)] structure is easily formed (n = 1, 2, 3, and 4). Oxygen diffusion from HfO2 layers toward the Si(110) substrate is promoted by annealing at 923 K. Oxygen atom desorption from the HfO2/Sin+/Si(110) surface occurs after annealing at 1073 K, and HfSi2 islands (i-HfSi2) are formed with a partly exposed Si(110)-16 × 2 double domain (DD) surface. i-HfSi2 shows low reactivity toward O2 molecules, whereas the exposed Si(110)-16 × 2 DD surface is immediately oxidized. Here, a i-HfSi2/Sin+-(sub)oxide/Si(110) structure is formed. Furthermore, we measure the Si-L23VV-Sin+-2p APECS spectra of Sin+ in the HfO2/Sin+/Si(110) and the i-HfSi2/Sin+/Si(110) structures (n = 2, 3, and 4) to evaluate the local valence electronic states of the Sin+ (sub)oxide components. The binding energy at the valence band maximum (BEVBM) of Sin+ in the i-HfSi2/Sin+/Si(110) structure is lower than 1.5 ± 0.7 eV as compared to that in the HfO2/Sin+/Si(110) structure (n = 2, 3, and 4). The local valence electric states of the nearest neighbors and the second neighbors through oxygen of Sin+ are determined to affect those of the Sin+ atom (n = 2, 3, and 4). The Sin+ atoms in the i-HfSi2/Sin+/Si(110) structure can directly bond to hafnium atoms as the nearest neighbors and most commonly have Sim+ atoms in lower ionic valence states as second neighbors (m < 4), whereas the Sin+ atoms in the HfO2/Sin+/Si(110) structure cannot form this bond. In addition, the existence of Hf silicide and Si in lower ionic valence states can reduce the band gap of the HfO2/Si(110) structure.
关键词： High-dielectric-constant material,X-ray photoelectron spectroscopy,Local valence electronic states at surface and interface,Synchrotron radiation,Auger photoelectron coincidence spectroscopy,Metal-insulator-semiconductor structure
更新于2025-09-11 14:15:04
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[IEEE 2018 Conference on Precision Electromagnetic Measurements (CPEM 2018) - Paris, France (2018.7.8-2018.7.13)] 2018 Conference on Precision Electromagnetic Measurements (CPEM 2018) - Metrological Challenge for Scanning Microwave Microscopy
摘要： We have demonstrated a near-field scanning microscopy (NSOM) based on an atomic force microscope (AFM) for characterization of high dielectric constant materials. The NSOM is applied to measure the dielectric constant of high dielectric constant materials by using a near-field microwave microscope. The NSOM is based on a cantilever with a sharp tip that is used to scan the sample surface. The microwave signal is applied to the tip and the reflected signal is detected by a microwave detector. The dielectric constant of the sample is determined by the phase shift of the reflected signal. The NSOM can measure the dielectric constant of materials with high spatial resolution. The NSOM is used to measure the dielectric constant of high dielectric constant materials such as BaTiO3, SrTiO3, and Pb(Zr,Ti)O3. The dielectric constant of these materials is measured with high accuracy and high spatial resolution.
关键词： dielectric constant,high dielectric constant materials,microwave,AFM,NSOM
更新于2025-09-10 09:29:36
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[IEEE 2018 12th International Congress on Artificial Materials for Novel Wave Phenomena (Metamaterials) - Espoo, Finland (2018.8.27-2018.9.1)] 2018 12th International Congress on Artificial Materials for Novel Wave Phenomena (Metamaterials) - Practical Isotropy and Anisotropy of 3-D Printed Artificial Foam-Like Dielectrics with Antenna Applications
摘要： The models, limitations and realization of homogenized foam-like 3-D printed dielectrics have been presented applying different fully symmetrical unit cells. The strategy for control of the absolute values of the resultant isotropic equivalent dielectric constant of these artificial dielectrics has been presented and verified and a possible anisotropy has been minimized.
关键词： antenna applications,3-D printed dielectrics,dielectric anisotropy,isotropic equivalent dielectric constant
更新于2025-09-10 09:29:36
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Growth, vibrational, optical, thermal, magnetic and dielectric behavior of organo-metallic tetramethylammonium cadmium chloride crystal
摘要： Single crystals of tetramethylammonium cadmium chloride were grown by slow evaporation technique. The single-crystal X-ray diffraction revealed that the crystal belongs to hexagonal crystal system with P63/m space group. The crystalline nature of the grown crystal was measured by power X-ray diffraction. The presence of functional groups was identi?ed using Fourier transform infrared and Fourier transform Raman studies. The optical absorption studies showed that the grown crystal transmit most of the incident radiation in the range of 200–800 nm. The diamagnetic property of the grown crystal has been analyzed by vibrating sample magnetometer. The mechanical stability of crystal is analyzed by Vickers microhardness study. Dielectric measurements were taken to analyze the dielectric constant and dielectric loss at different frequencies and temperatures. The thermal stability of grown crystals was con?rmed by thermogravimetry/differential thermal analysis. Thermal stability of the compound was entered up to 208 (cid:3)C.
关键词： Fourier transform infrared,Thermogravimetry/differential thermal analysis,Organo-metallic crystal,Fourier transform Raman,Vibrating sample magnetometer,Dielectric constant
更新于2025-09-10 09:29:36
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Effect of Doped Sb2O3 on the Electrical Properties of TiO2-Based Ceramics with the Dual Function of a Varistor–Capacitor
摘要： TiO2-based varistor–capacitor ceramics co-doped with fixed Nb2O5, MnO2, Sm2O3 and various content of Sb2O3 are prepared, and then the effect of Sb2O3 on electrical properties of TiO2 varistor–capacitor ceramics is investigated. The results indicate that addition of Sb2O3 effectively decreases breakdown voltage (E1mA), while having less impact on the nonlinear coefficient (a). E1mA initially increases and then decreases with Sb2O3 increasing; contrarily, relative dielectric constant (er) decreases first and then increases. It is found that composition of 98.3%TiO2-0.8%Nb2O5-0.3%MnO2-0.3%Sm2O3-0.3%Sb2O3 is obtained with a low breakdown voltage of 2.3 V/mm, nonlinear coefficient of 2.0, high relative dielectric constant of 7.6 9 104 and low dissipation factor of 0.25, which is consistent with the narrowest grain boundary barriers in the composition. The nonlinear coefficient initially increases and then decreases with increase of Sb2O3; it reaches a maximum value of 2.9 at 0.2 mol.% Sb2O3, which is consistent with the highest grain boundary barriers in the composition. In order to explain the nonlinear current–voltage characteristics, a grain boundary defect barrier model was introduced.
关键词： grain boundary defect barrier model,Varistor ceramics,nonlinear properties,relative dielectric constant
更新于2025-09-10 09:29:36
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Towards solution-processable, thermally robust, transparent polyimide-chain-end tethered organosilicate nanohybrids
摘要： The main challenge to developing future display substrates is to synthesize flexible substrate materials that also have excellent optical and thermal properties, and low thermal expansion number. In this study, a novel trifluoromethylated asymmetric aromatic diamine, 4-[[4-(4-amino-2-trifluoromethylphenoxy)phenyl]sulfonyl-3-(trifluoromethyl)]benzenamine (AFPSFB), was synthesized through nucleophilic substitution. Conventional two-step polycondensation of AFPSFB with commercially available tetracarboxylic dianhydrides enabled the fabrication of fully or semi-aromatic polyimides (PIs). The resulting PIs were highly soluble in polar aprotic solvents with good optical and thermal properties. Next, polyhedral oligomeric silsesquioxane containing an amine group (NH2-POSS) was reacted with the resulting soluble PI. All the PI-POSS nanohybrids displayed excellent optical properties, including high transparency (> 91% at 400 nm), low refractive index (< 1.5589), and very small birefringence (< 0.0025 at 637 nm). End-capping of the POSS and chemical bonding between the POSS and PIs significantly enhanced the thermal and electrical properties. The results provide useful information for designing molecular architectures for manufacturing high-performance flexible substrates in future display devices.
关键词： Organosilicate,Optical transparency,Dielectric constant,Thermal stability,Soluble polyimide
更新于2025-09-10 09:29:36