Organic dielectrics in high voltage cables

Energy Technology Data Exchange (ETDEWEB)

Vermeer, J

1962-03-01

It appears that the limit has been reached in the applicability of oil-impregnated paper as the dielectric for ehv cables, as with rising voltages the prevention of conductor losses becomes increasingly difficult, while the dielectric losses of the insulation, increasing as the square of the voltage, contribute to a greater extent to the temperature rise of the conductor. The power transmitting capacity of ehv cables reaches a maximum at 500 to 600 kV for these reasons. Apart from artificial cooling, a substantial improvement can be obtained only with the use of insulating materials with much lower dielectric losses; these can moreover be applied with a smaller wall thickness, but this means higher field strengths. Synthetic polymer materials meet these requirements but can be used successfully only in the form of lapped film tapes impregnated with suitable liquids. The electrical properties of these heterogeneous dielectrics, in particular, their impulse breakdown strengths are studied in detail.

Dielectric strength of voidless BaTiO{sub 3} films with nano-scale grains fabricated by aerosol deposition

Energy Technology Data Exchange (ETDEWEB)

Kim, Hong-Ki; Lee, Young-Hie, E-mail: yhlee@kw.ac.kr [Department of Electronics Materials Engineering, Kwangwoon University, Seoul (Korea, Republic of); Lee, Seung-Hwan [Department of Electronics Materials Engineering, Kwangwoon University, Seoul (Korea, Republic of); R and D Center, Samwha Capacitor, Yongin (Korea, Republic of); In Kim, Soo; Woo Lee, Chang [Department of Nano and Electronic Physics, Kookmin University, Seoul (Korea, Republic of); Rag Yoon, Jung [R and D Center, Samwha Capacitor, Yongin (Korea, Republic of); Lee, Sung-Gap [Department of Ceramic Engineering, Engineering Research Institute, Gyeongsang National University, Jinju (Korea, Republic of)

2014-01-07

In order to investigate the dielectric strength properties of the BaTiO{sub 3} films with nano-scale grains with uniform grain size and no voids, BaTiO{sub 3} films were fabricated with a thickness of 1 μm by an AD process, and the fabricated films were sintered at 800, 900, and 1000 °C in air and reducing atmosphere. The films have superior dielectric strength properties due to their uniform grain size and high density without any voids. In addition, based on investigation of the leakage current (intrinsic) properties, it was confirmed that the sintering conditions of the reducing atmosphere largely increase leakage currents due to generated electrons and doubly ionized oxygen vacancies following the Poole-Frenkel emission mechanism, and increased leakage currents flow at grain boundary regions. Therefore, we conclude that the extrinsic breakdown factors should be eliminated for superior dielectric strength properties, and it is important to enhance grain boundaries by doping acceptors and rare-earth elements.

Electric field strength in a silicon surface barrier detector with the presence of a dielectric plasma column

International Nuclear Information System (INIS)

Kanno, Ikuo

1994-01-01

The dynamic change of the electric field strength in a silicon surface barrier detector (SSBD) is studied. With the presence of a dielectric plasma column in the depletion layer of the SSBD, the electric field strength inside/outside the plasma column is suppressed/enhanced. As the length and the dielectric constant of the plasma column become shorter and smaller, the suppression and enhancement of the electric field strength become less. The electric field strength recovers the initial state, when the plasma column disappears. When the electrons and holes are inside/outside the dielectric plasma column, they have less/more electric potential than the one they have when there is no plasma column. During the movement of the electron/hole outside the plasma column to the positive/negative electrode, the enhanced electric field strength becomes smaller. Electron and hole pairs, which are the parts of the dielectric plasma column, arrive at positive and negative electrodes, having insufficient electric potential to induce the unit charge. This paper shows that the presence of a dielectric plasma column explains the main part of the residual defect in a SSBD. ((orig.))

Dielectric strength behaviour and mechanical properties of transparent insulation materials suitable to optical monitoring of partial discharges

International Nuclear Information System (INIS)

Lothongkam, Chaiyaporn

2014-01-01

A novel optical detection method for partial discharge in HV/EHV cable terminations has been proposed. Optical sensor fibres integrated into the HV equipment provide high sensitivity as well as immunity to electromagnetic interference and enable therefore on-line monitoring in electromagnetically noisy environment. The availability of optically transparent silicone rubbers that meet strict dielectric and mechanical criteria is a crucial prerequisite for the implementation of this method. The optically transparent silicone rubbers can be applied for the fabrication of a modern rubber stress cone as well as for the development of a new optical sensing element sensitive to PD activities. In this thesis, AC dielectric strength behaviour and mechanical properties of three types of commercially available silicone rubbers were investigated. One of the characterized silicone rubbers was a translucent type whereas the two others were optically transparent types, however with different chemical curing reactions. The measurements of tensile strength and elongation at break were carried out according to the ISO 37 standard. For investigation of the dielectric strength E b behaviour of the virgin and modified silicone rubbers, a new methodology was developed. It is, at the same time, highly reliable and efficient, saves time and reduces material consumption in comparison to previously reported methodologies. The key component of this methodology is a specifically developed test facility. Furthermore, the methodology comprises determinations for easy preparation and handling of high-quality test specimens. This test method provides various advantages over other methods that have previously been used for measurement of the fundamental quantity E b value of silicone rubbers. Both technical and economic demands are satisfied. The new facility also enables cost-effective routine tests in material research laboratories. The high quality of the obtained test results was verified by

Influence of refraction index strength on the light propagation in dielectrics material with periodic refraction index

International Nuclear Information System (INIS)

Hidayat, Arif; Latifah, Eny; Kurniati, Diana; Wisodo, Hari

2016-01-01

This study investigated the influence of refraction index strength on the light propagation in refraction index-varied dielectric material. This dielectric material served as photonic lattice. The behavior of light propagation influenced by variation of refraction index in photonic lattice was investigated. Modes of the guiding light were determined numerically using squared-operator iteration method. It was found that the greater the strength of refraction index, the smaller the guiding modes.

Dielectric elastomers, with very high dielectric permittivity, based on silicone and ionic interpenetrating networks

DEFF Research Database (Denmark)

Yu, Liyun; Madsen, Frederikke Bahrt; Hvilsted, Søren

2015-01-01

permittivity and the Young's modulus of the elastomer. One system that potentially achieves this involves interpenetrating polymer networks (IPNs), based on commercial silicone elastomers and ionic networks from amino- and carboxylic acid-functional silicones. The applicability of these materials as DEs...... are obtained while dielectric breakdown strength and Young's modulus are not compromised. These good overall properties stem from the softening effect and very high permittivity of ionic networks – as high as ε′ = 7500 at 0.1 Hz – while the silicone elastomer part of the IPN provides mechanical integrity...

Cast dielectric composite linear accelerator

Science.gov (United States)

Sanders, David M [Livermore, CA; Sampayan, Stephen [Manteca, CA; Slenes, Kirk [Albuquerque, NM; Stoller, H M [Albuquerque, NM

2009-11-10

A linear accelerator having cast dielectric composite layers integrally formed with conductor electrodes in a solventless fabrication process, with the cast dielectric composite preferably having a nanoparticle filler in an organic polymer such as a thermosetting resin. By incorporating this cast dielectric composite the dielectric constant of critical insulating layers of the transmission lines of the accelerator are increased while simultaneously maintaining high dielectric strengths for the accelerator.

Alignment of Boron Nitride Nanofibers in Epoxy Composite Films for Thermal Conductivity and Dielectric Breakdown Strength Improvement.

Science.gov (United States)

Wang, Zhengdong; Liu, Jingya; Cheng, Yonghong; Chen, Siyu; Yang, Mengmeng; Huang, Jialiang; Wang, Hongkang; Wu, Guanglei; Wu, Hongjing

2018-04-15

Development of polymer-based composites with simultaneously high thermal conductivity and breakdown strength has attracted considerable attention owing to their important applications in both electronic and electric industries. In this work, boron nitride (BN) nanofibers (BNNF) are successfully prepared as fillers, which are used for epoxy composites. In addition, the BNNF in epoxy composites are aligned by using a film casting method. The composites show enhanced thermal conductivity and dielectric breakdown strength. For instance, after doping with BNNF of 2 wt%, the thermal conductivity of composites increased by 36.4% in comparison with that of the epoxy matrix. Meanwhile, the breakdown strength of the composite with 1 wt% BNNF is 122.9 kV/mm, which increased by 6.8% more than that of neat epoxy (115.1 kV/mm). Moreover, the composites have maintained a low dielectric constant and alternating current conductivity among the range of full frequency, and show a higher thermal decomposition temperature and glass-transition temperature. The composites with aligning BNNF have wide application prospects in electronic packaging material and printed circuit boards.

Computation of Dielectric Response in Molecular Solids for High Capacitance Organic Dielectrics.

Science.gov (United States)

Heitzer, Henry M; Marks, Tobin J; Ratner, Mark A

2016-09-20

The dielectric response of a material is central to numerous processes spanning the fields of chemistry, materials science, biology, and physics. Despite this broad importance across these disciplines, describing the dielectric environment of a molecular system at the level of first-principles theory and computation remains a great challenge and is of importance to understand the behavior of existing systems as well as to guide the design and synthetic realization of new ones. Furthermore, with recent advances in molecular electronics, nanotechnology, and molecular biology, it has become necessary to predict the dielectric properties of molecular systems that are often difficult or impossible to measure experimentally. In these scenarios, it is would be highly desirable to be able to determine dielectric response through efficient, accurate, and chemically informative calculations. A good example of where theoretical modeling of dielectric response would be valuable is in the development of high-capacitance organic gate dielectrics for unconventional electronics such as those that could be fabricated by high-throughput printing techniques. Gate dielectrics are fundamental components of all transistor-based logic circuitry, and the combination high dielectric constant and nanoscopic thickness (i.e., high capacitance) is essential to achieving high switching speeds and low power consumption. Molecule-based dielectrics offer the promise of cheap, flexible, and mass producible electronics when used in conjunction with unconventional organic or inorganic semiconducting materials to fabricate organic field effect transistors (OFETs). The molecular dielectrics developed to date typically have limited dielectric response, which results in low capacitances, translating into poor performance of the resulting OFETs. Furthermore, the development of better performing dielectric materials has been hindered by the current highly empirical and labor-intensive pace of synthetic

Dielectric-Lined High-Gradient Accelerator Structure

Energy Technology Data Exchange (ETDEWEB)

Jay L. Hirshfield

2012-04-24

Rectangular particle accelerator structures with internal planar dielectric elements have been studied, with a view towards devising structures with lower surface fields for a given accelerating field, as compared with structures without dielectrics. Success with this concept is expected to allow operation at higher accelerating gradients than otherwise on account of reduced breakdown probabilities. The project involves studies of RF breakdown on amorphous dielectrics in test cavities that could enable high-gradient structures to be built for a future multi-TeV collider. The aim is to determine what the limits are for RF fields at the surfaces of selected dielectrics, and the resulting acceleration gradient that could be achieved in a working structure. The dielectric of principal interest in this study is artificial CVD diamond, on account of its advertised high breakdown field ({approx}2 GV/m for dc), low loss tangent, and high thermal conductivity. Experimental studies at mm-wavelengths on materials and structures for achieving high acceleration gradient were based on the availability of the 34.3 GHz third-harmonic magnicon amplifier developed by Omega-P, and installed at the Yale University Beam Physics Laboratory. Peak power from the magnicon was measured to be about 20 MW in 0.5 {micro}s pulses, with a gain of 54 dB. Experiments for studying RF high-field effects on CVD diamond samples failed to show any evidence after more than 10{sup 5} RF pulses of RF breakdown up to a tangential surface field strength of 153 MV/m; studies at higher fields were not possible due to a degradation in magnicon performance. A rebuild of the tube is underway at this writing. Computed performance for a dielectric-loaded rectangular accelerator structure (DLA) shows highly competitive properties, as compared with an existing all-metal structure. For example, comparisons were made of a DLA structure having two planar CVD diamond elements with a all-metal CERN structure HDS

Dielectric-Lined High-Gradient Accelerator Structure

International Nuclear Information System (INIS)

Hirshfield, Jay L.

2012-01-01

Rectangular particle accelerator structures with internal planar dielectric elements have been studied, with a view towards devising structures with lower surface fields for a given accelerating field, as compared with structures without dielectrics. Success with this concept is expected to allow operation at higher accelerating gradients than otherwise on account of reduced breakdown probabilities. The project involves studies of RF breakdown on amorphous dielectrics in test cavities that could enable high-gradient structures to be built for a future multi-TeV collider. The aim is to determine what the limits are for RF fields at the surfaces of selected dielectrics, and the resulting acceleration gradient that could be achieved in a working structure. The dielectric of principal interest in this study is artificial CVD diamond, on account of its advertised high breakdown field (∼2 GV/m for dc), low loss tangent, and high thermal conductivity. Experimental studies at mm-wavelengths on materials and structures for achieving high acceleration gradient were based on the availability of the 34.3 GHz third-harmonic magnicon amplifier developed by Omega-P, and installed at the Yale University Beam Physics Laboratory. Peak power from the magnicon was measured to be about 20 MW in 0.5 (micro)s pulses, with a gain of 54 dB. Experiments for studying RF high-field effects on CVD diamond samples failed to show any evidence after more than 10 5 RF pulses of RF breakdown up to a tangential surface field strength of 153 MV/m; studies at higher fields were not possible due to a degradation in magnicon performance. A rebuild of the tube is underway at this writing. Computed performance for a dielectric-loaded rectangular accelerator structure (DLA) shows highly competitive properties, as compared with an existing all-metal structure. For example, comparisons were made of a DLA structure having two planar CVD diamond elements with a all-metal CERN structure HDS operating at 30

Cellulose Triacetate Dielectric Films For Capacitors

Science.gov (United States)

Yen, Shiao-Ping S.; Jow, T. Richard

1994-01-01

Cellulose triacetate investigated for use as dielectric material in high-energy-density capacitors for pulsed-electrical-power systems. Films of cellulose triacetate metalized on one or both sides for use as substrates for electrodes and/or as dielectrics between electrodes in capacitors. Used without metalization as simple dielectric films. Advantages include high breakdown strength and self-healing capability.

Dielectric strength test to protection elements for live lines works

Directory of Open Access Journals (Sweden)

Carlos Eduardo Pinto-Salamanca

2017-06-01

Full Text Available This paper presents the design and assembly of a system of tests of sustained voltage to elements and equipment used in live line maneuvers through tests on gloves and dielectric rods, as these are the first points of contact to ensure safe operations. It means an advance for the creation of a laboratory certified in this type of tests at Universidad Pedagógica y Tecnológica de Colombia (UPTC Faculty of Duitama, considering that currently there are not laboratories that provide this service in Boyacá and Casanare. Dielectric strength tests were performed on personal protection elements and equipment under the parameters of ASTM D120, ASTM F496, ISO 60903, ASTM-F711 and IEEE 978, developing an assembly for testing gloves and dielectric rods with voltage levels up to 15 kV. The results validate the proposed system to outlook of circuit design and implementation, where tests were performed to establish dielectric capacities, in operating under open circuit conditions, with resistive load or short circuit. The compliance with the regulations established under the test sequences of safety parameters for the system and the follow-up to the tests was verified through the use of a management system for the generation of concepts of approval or rejection of the tested elements.

Homogeneous/Inhomogeneous-Structured Dielectrics and their Energy-Storage Performances.

Science.gov (United States)

Yao, Zhonghua; Song, Zhe; Hao, Hua; Yu, Zhiyong; Cao, Minghe; Zhang, Shujun; Lanagan, Michael T; Liu, Hanxing

2017-05-01

The demand for dielectric capacitors with higher energy-storage capability is increasing for power electronic devices due to the rapid development of electronic industry. Existing dielectrics for high-energy-storage capacitors and potential new capacitor technologies are reviewed toward realizing these goals. Various dielectric materials with desirable permittivity and dielectric breakdown strength potentially meeting the device requirements are discussed. However, some significant limitations for current dielectrics can be ascribed to their low permittivity, low breakdown strength, and high hysteresis loss, which will decrease their energy density and efficiency. Thus, the implementation of dielectric materials for high-energy-density applications requires the comprehensive understanding of both the materials design and processing. The optimization of high-energy-storage dielectrics will have far-reaching impacts on the sustainable energy and will be an important research topic in the near future. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Prediction on dielectric strength and boiling point of gaseous molecules for replacement of SF6.

Science.gov (United States)

Yu, Xiaojuan; Hou, Hua; Wang, Baoshan

2017-04-15

Developing the environment-friendly insulation gases to replace sulfur hexafluoride (SF 6 ) has attracted considerable experimental and theoretical attentions but without success. A computational methodology was presented herein for prediction on dielectric strength and boiling point of arbitrary gaseous molecules in the purpose of molecular design and screening. New structure-activity relationship (SAR) models have been established by combining the density-dependent properties of the electrostatic potential surface, including surface area and the statistical variance of the surface potentials, with the molecular properties including polarizability, electronegativity, and hardness. All the descriptors in the SAR models were calculated using density functional theory. The substitution effect of SF 6 by various functional groups was studied systematically. It was found that CF 3 is the most effective functional group to improve the dielectric strength due to the large surface area and polarizability. However, all the substitutes exhibit higher boiling points than SF 6 because the molecular hardness decreases. The balance between E r and T b could be achieved by minimizing the local polarity of the molecules. SF 5 CN and SF 5 CFO were found to be the potent candidates to replace SF 6 in view of their large dielectric strengths and low boiling points. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

High-pressure cell for simultaneous dielectric and neutron spectroscopy

Science.gov (United States)

Sanz, Alejandro; Hansen, Henriette Wase; Jakobsen, Bo; Pedersen, Ib H.; Capaccioli, Simone; Adrjanowicz, Karolina; Paluch, Marian; Gonthier, Julien; Frick, Bernhard; Lelièvre-Berna, Eddy; Peters, Judith; Niss, Kristine

2018-02-01

In this article, we report on the design, manufacture, and testing of a high-pressure cell for simultaneous dielectric and neutron spectroscopy. This cell is a unique tool for studying dynamics on different time scales, from kilo- to picoseconds, covering universal features such as the α relaxation and fast vibrations at the same time. The cell, constructed in cylindrical geometry, is made of a high-strength aluminum alloy and operates up to 500 MPa in a temperature range between roughly 2 and 320 K. In order to measure the scattered neutron intensity and the sample capacitance simultaneously, a cylindrical capacitor is positioned within the bore of the high-pressure container. The capacitor consists of two concentric electrodes separated by insulating spacers. The performance of this setup has been successfully verified by collecting simultaneous dielectric and neutron spectroscopy data on dipropylene glycol, using both backscattering and time-of-flight instruments. We have carried out the experiments at different combinations of temperature and pressure in both the supercooled liquid and glassy state.

Voltage-stabilised elastomers with increased relative permittivity and high electrical breakdown strength by means of phase separating binary copolymer blends of silicone elastomers

DEFF Research Database (Denmark)

A Razak, Aliff Hisyam; Yu, Liyun; Skov, Anne Ladegaard

2017-01-01

Increased electrical breakdown strength and increased dielectric permittivity of silicone-based dielectric elastomers are achieved by means of the addition of so-called voltage-stabilisers prepared from PDMS–PPMS copolymers as well as PDMS–PEG copolymers in order to compensate for the negative...... effect of softness on electrical stability of silicone elastomers. The voltage-stabilised elastomer, incorporating a high-permittivity PDMS–PEG copolymer, possesses increased relative permittivity, high electrical breakdown strength, excellent network integrity and low dielectric loss and paves the way...

Super dielectric capacitor using scaffold dielectric

OpenAIRE

Phillips, Jonathan

2018-01-01

Patent A capacitor having first and second electrodes and a scaffold dielectric. The scaffold dielectric comprises an insulating material with a plurality of longitudinal channels extending across the dielectric and filled with a liquid comprising cations and anions. The plurality of longitudinal channels are substantially parallel and the liquid within the longitudinal channels generally has an ionic strength of at least 0.1. Capacitance results from the migrations of...

A simple method for reducing inevitable dielectric loss in high-permittivity dielectric elastomers

DEFF Research Database (Denmark)

Madsen, Frederikke Bahrt; Yu, Liyun; Mazurek, Piotr Stanislaw

2016-01-01

elastomer matrix, with high dielectric permittivity and a low Young's modulus, aligned with no loss of mechanical stability, was prepared through the use of commercially available chloropropyl-functional silicone oil mixed into a tough commercial liquid silicone rubber silicone elastomer. The addition...... also decreased the dielectric losses of an elastomer containing dielectric permittivity-enhancing TiO2 fillers. Commercially available chloropropyl-functional silicone oil thus constitutes a facile method for improved silicone DEs, with very low dielectric losses.......Commercial viability of dielectric elastomers (DEs) is currently limited by a few obstacles, including high driving voltages (in the kV range). Driving voltage can be lowered by either decreasing the Young's modulus or increasing the dielectric permittivity of silicone elastomers, or a combination...

The Dielectric Behavior of Cyano-Substituted Poly imides

International Nuclear Information System (INIS)

Elshazly, E.S.; Abdelrahman, A.A.M.; Elmasry, M.A.A.

2013-01-01

A number of amorphous poly imides containing polar functional groups, cyano group, have been synthesized and investigated for potential use as high temperature piezoelectric sensors. The piezoelectric constants are related to the polarization. The remanent polarization and hence piezoelectric response of a material is determined by dielectric relaxation strength which is the difference in dielectric constant at the glass transition temperature vicinity. The intent of this work is to clarify the mechanism and key components required for developing piezoelectricity in amorphous polymers and further to apply this understanding in designing a unique high temperature piezoelectric polyimide. In this paper, experimental investigations of dielectric constant of piezoelectric cyano -substituted poly imides have been tested as a function of temperature to measure the dielectric relaxation strength in the glass transition temperature region.

High thermal conductivity lossy dielectric using a multi layer configuration

Science.gov (United States)

Tiegs, Terry N.; Kiggans, Jr., James O.

2003-01-01

Systems and methods are described for loss dielectrics. A loss dielectric includes at least one high dielectric loss layer and at least one high thermal conductivity-electrically insulating layer adjacent the at least one high dielectric loss layer. A method of manufacturing a loss dielectric includes providing at least one high dielectric loss layer and providing at least one high thermal conductivity-electrically insulating layer adjacent the at least one high dielectric loss layer. The systems and methods provide advantages because the loss dielectrics are less costly and more environmentally friendly than the available alternatives.

Electrode/Dielectric Strip For High-Energy-Density Capacitor

Science.gov (United States)

Yen, Shiao-Ping S.

1994-01-01

Improved unitary electrode/dielectric strip serves as winding in high-energy-density capacitor in pulsed power supply. Offers combination of qualities essential for high energy density: high permittivity of dielectric layers, thinness, and high resistance to breakdown of dielectric at high electric fields. Capacitors with strip material not impregnated with liquid.

A high energy density relaxor antiferroelectric pulsed capacitor dielectric

Energy Technology Data Exchange (ETDEWEB)

Jo, Hwan Ryul; Lynch, Christopher S. [Department of Mechanical and Aerospace Engineering, University of California, Los Angeles (UCLA), Los Angeles, California 90095 (United States)

2016-01-14

Pulsed capacitors require high energy density and low loss, properties that can be realized through selection of composition. Ceramic (Pb{sub 0.88}La{sub 0.08})(Zr{sub 0.91}Ti{sub 0.09})O{sub 3} was found to be an ideal candidate. La{sup 3+} doping and excess PbO were used to produce relaxor antiferroelectric behavior with slim and slanted hysteresis loops to reduce the dielectric hysteresis loss, to increase the dielectric strength, and to increase the discharge energy density. The discharge energy density of this composition was found to be 3.04 J/cm{sup 3} with applied electric field of 170 kV/cm, and the energy efficiency, defined as the ratio of the discharge energy density to the charging energy density, was 0.920. This high efficiency reduces the heat generated under cyclic loading and improves the reliability. The properties were observed to degrade some with temperature increase above 80 °C. Repeated electric field cycles up to 10 000 cycles were applied to the specimen with no observed performance degradation.

Physical and dielectric properties of irradiated polypropylene and poly(ethylene terephthalate)

International Nuclear Information System (INIS)

Kita, H.; Okamoto, K.

1986-01-01

The effect of high-energy electron irradiation in air and in nitrogen on the physical and dielectric properties of polypropylene and poly(ethylene terephthalate) has been studied by measurements of electric strength, dielectric constant, dissipation factor, tensile strength, gel fraction and molecular weight distribution. Electric strength of polypropylene was improved by irradiation, while dielectric properties of poly(ethylene terephthalate) were virtually unaffected by irradiation of 1.0-20 Mrad. Possible mechanisms for increasing electric strength are discussed from the point of view of degradation and oxidation taking place simultaneously with crosslinking of polypropylene. The maximum dose level to improve the electric strength of polypropylene is determined to be about 5 Mrad. (author)

Development and characterization of high temperature, high energy density dielectric materials to establish routes towards power electronics capacitive devices

Science.gov (United States)

Shay, Dennis P.

The maximum electrostatic energy density of a capacitor is a function of the relative permittivity (epsilonr) and the square of the dielectric breakdown strength (Eb). Currently, state-of-the art high temperature (>200 °C), SiC-based power electronics utilize CaZrO3-rich NP0/C0G-type capacitors, which have low relative permittivities of epsilonr ˜ 30-40, high breakdown strengths (> 1.0 MV/cm), and are chosen for their minimal change in energy storage with temperature. However, with operating temperatures exceeding the rated temperatures for such capacitors, there is an opportunity to develop new dielectric ceramics having higher energy densities and volumetric efficiencies at high temperatures (>200 °C) by utilizing higher permittivity dielectrics while maintaining high breakdown strengths via doping. The solid solution behavior of was characterized in order to determine the optimal composition for balancing permittivity and dielectric breakdown strength to obtain high energy densities at elevated temperatures. Characterization by X-ray diffraction (XRD) showed Vegard's law behavior across the solid solution with minimal 2nd phases. To determine a Ca(TixZr1-x)O3 composition that will also minimize electronic or band conduction, the optical properties of the Ca(TixZr1-x)O3 solid solution were investigated to identify a composition on the CaTiO3 - rich end of the solid solution with a large band gap. Both ultraviolet-visible diffuse reflectance spectroscopy (UV-Vis) and spectroscopic ellipsometry were utilized to determine the Ca(TixZr1-x)O3 band gaps and optical properties. The resistivity at 250 °C scaled with the band gap energy across the solid solution. Comparing the current-voltage (I--V) behavior at 250 °C for Ca(Tix-yMnyZr0.2)O3 (CTZ + Mn) where x = 0.7, 0.8, 0.9, and y = 0.005, it was found that the Ca(Ti 0.795Mn0.005Zr0.2)O3 composition showed the lowest current density and a decrease in current density of 5 orders of magnitude compared to the un

Dielectric properties of polymer-particle nanocomposites influenced by electronic nature of filler surfaces.

Science.gov (United States)

Siddabattuni, Sasidhar; Schuman, Thomas P; Dogan, Fatih

2013-03-01

The interface between the polymer and the particle has a critical role in altering the properties of a composite dielectric. Polymer-ceramic nanocomposites are promising dielectric materials for many electronic and power devices, combining the high dielectric constant of ceramic particles with the high dielectric breakdown strength of a polymer. Self-assembled monolayers of electron rich or electron poor organophosphate coupling groups were applied to affect the filler-polymer interface and investigate the role of this interface on composite behavior. The interface has potential to influence dielectric properties, in particular the leakage and breakdown resistance. The composite films synthesized from the modified filler particles dispersed into an epoxy polymer matrix were analyzed by dielectric spectroscopy, breakdown strength, and leakage current measurements. The data indicate that significant reduction in leakage currents and dielectric losses and improvement in dielectric breakdown strengths resulted when electropositive phenyl, electron-withdrawing functional groups were located at the polymer-particle interface. At a 30 vol % particle concentration, dielectric composite films yielded a maximum energy density of ~8 J·cm(-3) for TiO2-epoxy nanocomposites and ~9.5 J·cm(-3) for BaTiO3-epoxy nanocomposites.

Silicone elastomers with superior softness and dielectric properties

DEFF Research Database (Denmark)

Yu, Liyun; Madsen, Frederikke Bahrt; Zakaria, Shamsul Bin

Dielectric elastomers (DEs) change their shape and size under a high voltage or reversibly generate a high voltage when deformed. The obstacle of high driving voltages, however, limits the commercial viability of the technology at present. Driving voltage can be lowered by decreasing the Young......’s modulus and increasing the dielectric permittivity of silicone elastomers. One such prominent method of modifying the properties is by adding suitable additives. [1] The major drawbacks for adding solid fillers are agglomeration and increasing stiffness which is often accompanied by the decrease...... were determined by NMR and morphology structures were investigated by optical microscopy. The resulting elastomers were evaluated with respect to their dielectric permittivity, tear and tensile strengths, as well as electrical breakdown.The breakdown strength increased at low amounts of additives...

Experimental Study on High Electrical Breakdown of Water Dielectric

International Nuclear Information System (INIS)

Zhang Zicheng; Zhang Jiande; Yang Jianhua

2005-01-01

By means of a coaxial apparatus, pressurized water breakdown experiments with microsecond charging have been carried out with different surface roughness of electrodes and different ethylene glycol concentrations of ethylene glycol/water mixture. The experimental results about the breakdown stress and the effective time are presented. The breakdown stress is normalized to the situation that the effective time is transformed to 1 μs and analyzed. The conclusions are as follows: (1) the breakdown stress formula is modified to E = 0.561M A -1/10 t eff -1/N P 1/8 ; (2) the coefficient M is significantly increased by surface polishing and ethylene glycol additive; (3) it is accumulative for the capacity of improving electrical breakdown strength for surface polishing, ethylene glycol additive, and pressurization, of which pressurization is the most effective method; (4) the highest stress of 235.5 kV/cm is observed in ethylene glycol/water mixture with an ethylene glycol concentration of 80% at a hydrostatic pressure of 1215.9 kPa and is about one time greater than that in pure water at constant pressure; (5) for pressurization and surface polishing, the primary mechanism to improve the breakdown strength of water dielectric is the increase in the breakdown time delay. Research results indicate great potential in the application of the high power pulse conditioning system of water dielectric

Nanocomposite dielectrics in PbO-BaO-Na2O-Nb2O5-SiO2 system with high breakdown strength for high voltage capacitor applications.

Science.gov (United States)

Zhang, Qingmeng; Luo, Jun; Tang, Qun; Han, Dongfang; Zhou, Yi; Du, Jun

2012-11-01

Nanocomposite dielectrics in 6PbO-4BaO-20Na2O-40Nb2O5-30SiO2 system were prepared via melt-quenching followed by controlled crystallization. X-ray diffraction studies reveal that Pb2Nb2O7, Ba,NaNb5O15, NaNbO3 and PbNb2O6 phases are formed from the as-quenched glass annealed in temperature range from 700 degrees C to 850 degrees C. Ba2NaNb5O15, Pb2Nb2O7 crystallizes at 700 degrees C and then Pb2Nb2O7 disappears at 850 degrees C, while PbNb2O6 and NaNbO3 are formed at 850 degrees C. Microstructural observation shows that the crystallized particles are nanometer-sized and randomly distributed with glass matrix being often found at grain boundaries. The dielectric constant of the nanocomposites formed at different crystallization temperatures shows good frequency and electric field stability. The breakdown strength is slightly decreased when the glass-ceramics thickness is varied from 1 mm to 4 mm. The corresponding energy density could reach 2.96 J/cm3 with a breakdown strength of 58 kV/mm for thickness of 1 mm.

Pulse Power Capability Of High Energy Density Capacitors Based on a New Dielectric Material

Science.gov (United States)

Winsor, Paul; Scholz, Tim; Hudis, Martin; Slenes, Kirk M.

1999-01-01

A new dielectric composite consisting of a polymer coated onto a high-density metallized Kraft has been developed for application in high energy density pulse power capacitors. The polymer coating is custom formulated for high dielectric constant and strength with minimum dielectric losses. The composite can be wound and processed using conventional wound film capacitor manufacturing equipment. This new system has the potential to achieve 2 to 3 J/cu cm whole capacitor energy density at voltage levels above 3.0 kV, and can maintain its mechanical properties to temperatures above 150 C. The technical and manufacturing development of the composite material and fabrication into capacitors are summarized in this paper. Energy discharge testing, including capacitance and charge-discharge efficiency at normal and elevated temperatures, as well as DC life testing were performed on capacitors manufactured using this material. TPL (Albuquerque, NM) has developed the material and Aerovox (New Bedford, MA) has used the material to build and test actual capacitors. The results of the testing will focus on pulse power applications specifically those found in electro-magnetic armor and guns, high power microwave sources and defibrillators.

High thermal conductivity lossy dielectric using co-densified multilayer configuration

Science.gov (United States)

Tiegs, Terry N.; Kiggans, Jr., James O.

2003-06-17

Systems and methods are described for loss dielectrics. A method of manufacturing a lossy dielectric includes providing at least one high dielectric loss layer and providing at least one high thermal conductivity-electrically insulating layer adjacent the at least one high dielectric loss layer and then densifying together. The systems and methods provide advantages because the lossy dielectrics are less costly and more environmentally friendly than the available alternatives.

Enhancement of Dielectric Breakdown Strength and Energy Conversion Efficiency of Niobate Glass-Ceramics by Sc2O3 Doping

Science.gov (United States)

Xiao, Shi; Xiu, Shaomei; Yang, Ke; Shen, Bo; Zhai, Jiwei

2018-01-01

Niobate glass-ceramics K2O-SrO-Nb2O5-B2O3-Al2O3-SiO2 (KSN-BAS) doped with different amounts of Sc2O3 have been prepared through a melt quenching/controlled crystallization method, and the influence of the Sc2O3 content on their phase composition, microstructure, dielectric performance, and charge-discharge properties investigated. X-ray powder diffraction results showed that the peak positions of the KSr2Nb5O15 phase shifted to higher angle and the glass-ceramic microstructures were significantly improved by Sc2O3 addition. Based on these results, 0.5 mol.% Sc2O3 doping was found to achieve remarkable enhancement in energy storage density, which reached 9.63 ± 0.39 J/cm3 at dielectric breakdown strength of 1450.38 ± 29.01 kV/cm with high conversion efficiency of ˜ 92.1%. For pulsed power applications, discharge speed of 17 ns and power density of 0.48 MW/cm3 were obtained in the glass-ceramic with 0.5 mol.% Sc2O3. These results could provide a new design strategy for high-performance dielectric capacitors.

Characterization of a dielectric phantom for high-field magnetic resonance imaging applications

Energy Technology Data Exchange (ETDEWEB)

Duan, Qi, E-mail: Qi.Duan@nih.gov; Duyn, Jeff H.; Gudino, Natalia; Zwart, Jacco A. de; Gelderen, Peter van [Advanced MRI Section, Laboratory of Functional and Molecular Imaging, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland 20892 (United States); Sodickson, Daniel K.; Brown, Ryan [The Bernard and Irene Schwartz Center for Biomedical Imaging, Department of Radiology, New York University School of Medicine, New York, New York 10016 (United States)

2014-10-15

Purpose: In this work, a generic recipe for an inexpensive and nontoxic phantom was developed within a range of biologically relevant dielectric properties from 150 MHz to 4.5 GHz. Methods: The recipe includes deionized water as the solvent, NaCl to primarily control conductivity, sucrose to primarily control permittivity, agar–agar to gel the solution and reduce heat diffusivity, and benzoic acid to preserve the gel. Two hundred and seventeen samples were prepared to cover the feasible range of NaCl and sucrose concentrations. Their dielectric properties were measured using a commercial dielectric probe and were fitted to a 3D polynomial to generate a recipe describing the properties as a function of NaCl concentration, sucrose concentration, and frequency. Results: Results indicated that the intuitive linear and independent relationships between NaCl and conductivity and between sucrose and permittivity are not valid. A generic polynomial recipe was developed to characterize the complex relationship between the solutes and the resulting dielectric values and has been made publicly available as a web application. In representative mixtures developed to mimic brain and muscle tissue, less than 2% difference was observed between the predicted and measured conductivity and permittivity values. Conclusions: It is expected that the recipe will be useful for generating dielectric phantoms for general magnetic resonance imaging (MRI) coil development at high magnetic field strength, including coil safety evaluation as well as pulse sequence evaluation (including B{sub 1}{sup +} mapping, B{sub 1}{sup +} shimming, and selective excitation pulse design), and other non-MRI applications which require biologically equivalent dielectric properties.

Self-Healing, High-Permittivity Silicone Dielectric Elastomer

DEFF Research Database (Denmark)

Madsen, Frederikke Bahrt; Yu, Liyun; Skov, Anne Ladegaard

2016-01-01

possesses high dielectric permittivity and consists of an interpenetrating polymer network of silicone elastomer and ionic silicone species that are cross-linked through proton exchange between amines and acids. The ionically cross-linked silicone provides self-healing properties after electrical breakdown...... or cuts made directly to the material due to the reassembly of the ionic bonds that are broken during damage. The dielectric elastomers presented in this paper pave the way to increased lifetimes and the ability of dielectric elastomers to survive millions of cycles in high-voltage conditions....

Microstructure Study For Optimization Of Dielectric Property Of Electrical Porcelain

International Nuclear Information System (INIS)

Tak, S. K.; Shekhawat, M. S.; Mangal, R.

2010-01-01

Five sample mixtures of kaolin, ball clay, feldspar and Quartz were formulated and porcelain samples fabricated. Crystalline phases and mullite morphology were studied using XRD and SEM respectively. A composition of 30% kaolin, 15% ball clay, 30% feldspar and 25% quartz yielded a body with high dielectric strength of 19 kV/mm compare to an ISO graded product having dielectric strength 14.6 KV/mm after firing at 1225 deg. C.

Cyanoresin, cyanoresin/cellulose triacetate blends for thin film, dielectric capacitors

Science.gov (United States)

Yen, Shiao-Ping S. (Inventor); Lewis, Carol R. (Inventor); Cygan, Peter J. (Inventor); Jow, T. Richard (Inventor)

1996-01-01

Non brittle dielectric films are formed by blending a cyanoresin such as cyanoethyl, hydroxyethyl cellulose (CRE) with a compatible, more crystalline resin such as cellulose triacetate. The electrical breakdown strength of the blend is increased by orienting the films by uniaxial or biaxial stretching. Blends of high molecular weight CRE with high molecular weight cyanoethyl cellulose (CRC) provide films with high dielectric constants.

Analysis of electron interactions in dielectric gases

International Nuclear Information System (INIS)

Olivet, Aurelio; Duque, Daniel; Vega, Lourdes F.

2007-01-01

We present and discuss results concerning electron interactions processes of dielectric gases and their relationship with the macroscopic behavior of these gases, in particular, with their dielectric strength. Such analysis is based on calculating energies of reactions for molecular ionization, dissociative ionization, parent negative ion formation, and dissociative electron attachment processes. We hypothesize that the estimation of the required energy for a reduced number of processes that take place in electrically stressed gases could be related to the gas' capability to manage the electron flow during an electrical discharge. All calculations were done with semiempirical quantum chemistry methods, including an initial optimization of molecular geometry and heat of formation of the dielectric gases and all of species that appear during electron interaction reactions. The performance of semiempirical methods Austin model 1 and Parametric model 3 (PM3) was compared for several compounds, PM3 being superior in most cases. Calculations performed for a sample of nine dielectric gases show that electron attachment and detachment processes occur in different energy bands that do not overlap for any value of the dielectric strength. We have also analyzed the relationship between dielectric strength and two physical properties: electron affinity and ionization energy. Calculations performed for 43 dielectric gases show no clear correlation between them, although certain guidelines for the qualitative estimation of dielectric strength can still be assessed

Super soft silicone elastomers with high dielectric permittivity

DEFF Research Database (Denmark)

Madsen, Frederikke Bahrt; Yu, Liyun; Hvilsted, Søren

2015-01-01

Dielectric elastomers (DEs) have many favourable properties. The obstacle of high driving voltages, however, limits the commercial viability of the technology at present. Driving voltage can be lowered by decreasing the Young’s modulus and increasing the dielectric permittivity of silicone...... elastomers. A decrease in Young’s modulus, however, is often accompanied by the loss of mechanical stability and thereby the lifetime of the DE. New soft elastomer matrices with high dielectric permittivity and low Young’s modulus, with no loss of mechanical stability, were prepared by two different...... approaches using chloropropyl-functional silicone polymers. The first approach was based on synthesised chloropropyl-functional copolymers that were cross-linkable and thereby formed the basis of new silicone networks with high dielectric permittivity (e.g. a 43% increase). These networks were soft without...

Recent Progress on Ferroelectric Polymer-Based Nanocomposites for High Energy Density Capacitors: Synthesis, Dielectric Properties, and Future Aspects.

Science.gov (United States)

Prateek; Thakur, Vijay Kumar; Gupta, Raju Kumar

2016-04-13

Dielectric polymer nanocomposites are rapidly emerging as novel materials for a number of advanced engineering applications. In this Review, we present a comprehensive review of the use of ferroelectric polymers, especially PVDF and PVDF-based copolymers/blends as potential components in dielectric nanocomposite materials for high energy density capacitor applications. Various parameters like dielectric constant, dielectric loss, breakdown strength, energy density, and flexibility of the polymer nanocomposites have been thoroughly investigated. Fillers with different shapes have been found to cause significant variation in the physical and electrical properties. Generally, one-dimensional and two-dimensional nanofillers with large aspect ratios provide enhanced flexibility versus zero-dimensional fillers. Surface modification of nanomaterials as well as polymers adds flavor to the dielectric properties of the resulting nanocomposites. Nowadays, three-phase nanocomposites with either combination of fillers or polymer matrix help in further improving the dielectric properties as compared to two-phase nanocomposites. Recent research has been focused on altering the dielectric properties of different materials while also maintaining their superior flexibility. Flexible polymer nanocomposites are the best candidates for application in various fields. However, certain challenges still present, which can be solved only by extensive research in this field.

Flexible Ultrahigh-Temperature Polymer-Based Dielectrics with High Permittivity for Film Capacitor Applications

Directory of Open Access Journals (Sweden)

Zejun Pu

2017-11-01

Full Text Available In this report, flexible cross-linked polyarylene ether nitrile/functionalized barium titanate(CPEN/F-BaTiO3 dielectrics films with high permittivitywere prepared and characterized. The effects of both the F-BaTiO3 and matrix curing on the mechanical, thermal and dielectric properties of the CPEN/F-BaTiO3 dielectric films were investigated in detail. Compared to pristine BaTiO3, the surface modified BaTiO3 particles effectively improved their dispersibility and interfacial adhesion in the polymer matrix. Moreover, the introduction of F-BaTiO3 particles enhanced dielectric properties of the composites, with a relatively high permittivity of 15.2 and a quite low loss tangent of 0.022 (1 kHz when particle contents of 40 wt % were utilized. In addition, the cyano (–CN groups of functional layer also can serve as potential sites for cross-linking with polyarylene ether nitrile terminated phthalonitrile (PEN-Ph matrix and make it transform from thermoplastic to thermosetting. Comparing with the pure PEN-ph film, the latter results indicated that the formation of cross-linked network in the polymer-based system resulted in increased tensile strength by ~67%, improved glass transition temperature (Tg by ~190 °C. More importantly, the CPEN/F-BaTiO3 composite films filled with 30 wt % F-BaTiO3 particles showed greater energy density by nearly 190% when compared to pure CPEN film. These findings enable broader applications of PEN-based composites in high-performance electronics and energy storage devices materials used at high temperature.

Improved polymer nanocomposite dielectric breakdown performance through barium titanate to epoxy interface control

Energy Technology Data Exchange (ETDEWEB)

Siddabattuni, Sasidhar [Missouri University of Science and Technology (formerly the University of Missouri-Rolla), Chemistry Department, 400W. 11th Street, Rolla, MO 65409 (United States); Schuman, Thomas P., E-mail: tschuman@mst.edu [Missouri University of Science and Technology (formerly the University of Missouri-Rolla), Chemistry Department, 400W. 11th Street, Rolla, MO 65409 (United States); Dogan, Fatih [Missouri University of Science and Technology, Materials Science and Engineering Department, 1400N. Bishop Avenue, Rolla, MO 65409 (United States)

2011-11-15

Highlights: > A covalent filler-matrix interface improves the dielectric properties of a polymer-particle nanocomposite dielectric. > A covalent interface reduced the polymer free volume around the nanoparticles as assessed through T{sub g} measurements. > Composite T{sub g} was raised and breakdown strength improved for nanocomposites with a covalent polymer-particle interface. > A larger Maxwell-Wagner (MW) relaxation correlated with reduced breakdown strengths and energy storage densities. > The MW relaxation could be considered a dielectric defect regarding breakdown strength and energy storage density. - Abstract: A composite approach to dielectric design has the potential to provide improved permittivity as well as high breakdown strength and thus afford greater electrical energy storage density. Interfacial coupling is an effective approach to improve the polymer-particle composite dielectric film resistance to charge flow and dielectric breakdown. A bi-functional interfacial coupling agent added to the inorganic oxide particles' surface assists dispersion into the thermosetting epoxy polymer matrix and upon composite cure reacts covalently with the polymer matrix. The composite then retains the glass transition temperature of pure polymer, provides a reduced Maxwell-Wagner relaxation of the polymer-particle composite, and attains a reduced sensitivity to dielectric breakdown compared to particle epoxy composites that lack interfacial coupling between the composite filler and polymer matrix. Besides an improved permittivity, the breakdown strength and thus energy density of a covalent interface nanoparticle barium titanate in epoxy composite dielectric film, at a 5 vol.% particle concentration, was significantly improved compared to a pure polymer dielectric film. The interfacially bonded, dielectric composite film had a permittivity {approx}6.3 and at a 30 {mu}m thickness achieved a calculated energy density of 4.6 J/cm{sup 3}.

Improved polymer nanocomposite dielectric breakdown performance through barium titanate to epoxy interface control

International Nuclear Information System (INIS)

Siddabattuni, Sasidhar; Schuman, Thomas P.; Dogan, Fatih

2011-01-01

Highlights: → A covalent filler-matrix interface improves the dielectric properties of a polymer-particle nanocomposite dielectric. → A covalent interface reduced the polymer free volume around the nanoparticles as assessed through T g measurements. → Composite T g was raised and breakdown strength improved for nanocomposites with a covalent polymer-particle interface. → A larger Maxwell-Wagner (MW) relaxation correlated with reduced breakdown strengths and energy storage densities. → The MW relaxation could be considered a dielectric defect regarding breakdown strength and energy storage density. - Abstract: A composite approach to dielectric design has the potential to provide improved permittivity as well as high breakdown strength and thus afford greater electrical energy storage density. Interfacial coupling is an effective approach to improve the polymer-particle composite dielectric film resistance to charge flow and dielectric breakdown. A bi-functional interfacial coupling agent added to the inorganic oxide particles' surface assists dispersion into the thermosetting epoxy polymer matrix and upon composite cure reacts covalently with the polymer matrix. The composite then retains the glass transition temperature of pure polymer, provides a reduced Maxwell-Wagner relaxation of the polymer-particle composite, and attains a reduced sensitivity to dielectric breakdown compared to particle epoxy composites that lack interfacial coupling between the composite filler and polymer matrix. Besides an improved permittivity, the breakdown strength and thus energy density of a covalent interface nanoparticle barium titanate in epoxy composite dielectric film, at a 5 vol.% particle concentration, was significantly improved compared to a pure polymer dielectric film. The interfacially bonded, dielectric composite film had a permittivity ∼6.3 and at a 30 μm thickness achieved a calculated energy density of 4.6 J/cm 3 .

High energy density, long life energy storage capacitor dielectric system

International Nuclear Information System (INIS)

Nichols, D.H.; Wilson, S.R.

1977-01-01

The evolution of energy storage dielectric systems shows a dramatic improvement in life and joule density, culminating in a 50% to 300% life improvement of polypropylene film-paper-phthalate ester over paper-castor oil depending on service. The physical and electrical drawbacks of castor oil are not present in the new system, allowing the capacitor designer to utilize the superior insulation resistance, dielectric strength, and corona resistance to full advantage. The result is longer life for equal joule density or greater joule density for equal life. Field service proof of the film-Geconol system superiority is based on 5 megajoule in operation and 16 megajoule on order

Development of a dielectric ceramic based on diatomite-titania part two: dielectric properties characterization

Directory of Open Access Journals (Sweden)

Medeiros Jamilson Pinto

1998-01-01

Full Text Available Dielectric properties of sintered diatomite-titania ceramics are presented. Specific capacitance, dissipation factor, quality factor and dielectric constant were determined as a function of sintering temperature, titania content and frequency; the temperature coefficient of capacitance was measured as a function of frequency. Besides leakage current, the dependence of the insulation resistance and the dielectric strength on the applied dc voltage were studied. The results show that diatomite-titania compositions can be used as an alternative dielectric.

Polaron-electron assisted giant dielectric dispersion in SrZrO{sub 3} high-k dielectric

Energy Technology Data Exchange (ETDEWEB)

Borkar, Hitesh; Barvat, Arun; Pal, Prabir; Kumar, Ashok, E-mail: ashok553@nplindia.org [CSIR-National Physical Laboratory, Dr. K. S. Krishnan Marg, New Delhi 110012 (India); Academy of Scientific and Innovative Research (AcSIR), CSIR-National Physical Laboratory (CSIR-NPL) Campus, Dr. K S Krishnan Marg, New Delhi 110012 (India); Shukla, A. K. [CSIR-National Physical Laboratory, Dr. K. S. Krishnan Marg, New Delhi 110012 (India); Pulikkotil, J. J. [CSIR-National Physical Laboratory, Dr. K. S. Krishnan Marg, New Delhi 110012 (India); Academy of Scientific and Innovative Research (AcSIR), CSIR-National Physical Laboratory (CSIR-NPL) Campus, Dr. K S Krishnan Marg, New Delhi 110012 (India); Computation and Networking Facility, CSIR-National Physical Laboratory, New Delhi 110012 (India)

2016-06-07

The SrZrO{sub 3} is a well known high-k dielectric constant (∼22) and high optical bandgap (∼5.8 eV) material and one of the potential candidates for future generation nanoelectronic logic elements (8 nm node technology) beyond silicon. Its dielectric behavior is fairly robust and frequency independent till 470 K; however, it suffers a strong small-polaron based electronic phase transition (T{sub e}) linking 650 to 750 K. The impedance spectroscopy measurements revealed the presence of conducting grains and grain boundaries at elevated temperature which provide energetic mobile charge carriers with activation energy in the range of 0.7 to 1.2 eV supporting the oxygen ions and proton conduction. X-ray photoemission spectroscopy measurements suggest the presence of weak non-stoichiometric O{sup 2−} anions and hydroxyl species bound to different sites at the surface and bulk. These thermally activated charge carriers at elevated temperature significantly contribute to the polaronic based dielectric anomaly and conductivity. Our dielectric anomaly supports pseudo phase transition due to high degree of change in ZrO{sub 6} octahedral angle in the temperature range of 650–750 K, where electron density and phonon vibration affect the dielectric and conductivity properties.

Optimization of nitridation conditions for high quality inter-polysilicon dielectric layers

NARCIS (Netherlands)

Klootwijk, J.H.; Bergveld, H.J.; van Kranenburg, H.; Woerlee, P.H.; Wallinga, Hans

1996-01-01

Nitridation of deposited high temperature oxides (HTO) was studied to form high quality inter-polysilicon dielectric layers for embedded non volatile memories. Good quality dielectric layers were obtained earlier by using an optimized deposition of polysilicon and by performing a post-dielectric

Insight into the dielectric response of transformer oil-based nanofluids

Directory of Open Access Journals (Sweden)

Ming Dong

2017-02-01

Full Text Available The oil-based nanofluids with greater dielectric strength have attracted much attention as a crucial insulating materials in high-voltage oil-immersed power equipment. In fact, the different microstructures of the transformer oil-based nanofluids (TNFs would result in different dielectric properties. In this work, the broadband dielectric spectroscopy measurement was used to establish the linkage between the electric double layer (EDL and dielectric response properties of TNFs which was performed at 298K temperature and with frequency range from 10-2Hz∼106Hz. The modified Havriliak-Negami (HN model function was used to analyze the measured results. The results demonstrate that both the real and imaginary parts of dielectric spectra of two kinds of oil are composed of the conductivity and polarization process. Compared with pure oil, two polarization process could be observed for the TNFs, explained by the EDL structure reasonably. The introduction of the EDL structure provides an idea to account for the insulating strength improvement of TNFs for the first time.

Functional silicone copolymers and elastomers with high dielectric permittivity

DEFF Research Database (Denmark)

Madsen, Frederikke Bahrt; Daugaard, Anders Egede; Hvilsted, Søren

Dielectric elastomers (DEs) are a new and promising transducer technology and are often referred to as ‘artificial muscles’, due to their ability to undergo large deformations when stimulated by electric fields. DEs consist of a soft and thin elastomeric film sandwiched between compliant electrodes......, thereby forming a capacitor [1]. Silicone elastomers are one of the most used materials for DEs due to their high efficiency, fast response times and low viscous losses. The major disadvantage of silicone elastomers is that they possess relatively low dielectric permittivity, which means that a high...... electrical field is necessary to operate the DE. The necessary electrical field can be lowered by creating silicone elastomers with higher dielectric permittivity, i.e. with a higher energy density.The aim of this work is to create new and improved silicone elastomers with high dielectric permittivity...

The Electrical Breakdown of Thin Dielectric Elastomers

DEFF Research Database (Denmark)

Zakaria, Shamsul Bin; Morshuis, Peter H. F.; Yahia, Benslimane Mohamed

2014-01-01

Dielectric elastomers are being developed for use in actuators, sensors and generators to be used in various applications, such as artificial eye lids, pressure sensors and human motion energy generators. In order to obtain maximum efficiency, the devices are operated at high electrical fields....... This increases the likelihood for electrical breakdown significantly. Hence, for many applications the performance of the dielectric elastomers is limited by this risk of failure, which is triggered by several factors. Amongst others thermal effects may strongly influence the electrical breakdown strength....... In this study, we model the electrothermal breakdown in thin PDMS based dielectric elastomers in order to evaluate the thermal mechanisms behind the electrical failures. The objective is to predict the operation range of PDMS based dielectric elastomers with respect to the temperature at given electric field...

Enhanced dielectric and ferroelectric characteristics in Ca-modified BaTiO3 ceramics

Directory of Open Access Journals (Sweden)

Xiao Na Zhu

2013-08-01

Full Text Available Synergic modification of BaTiO3 ceramics was investigated by Ca-substitution, and the superior dielectric and ferroelectric properties were determined together with the structure evolution. X-ray diffraction (XRD analysis demonstrated a large solubility limit above x = 0.25 in Ba1−xCaxTiO3 solid solution where the fine grain structure was observed with increasing x. Room temperature dielectric constant as high as 1655 was achieved in the present ceramics together with the significantly reduced dielectric loss of 0.013 (x = 0.20 at 100 kHz, where the Curie temperature kept almost a constant while other two transition temperatures decreased continuously with increasing x. More importantly, the remanent polarization Pr and dielectric strength Eb were significantly enhanced by Ca-substitution, and the best Pr (11.34 μC/cm2 and the highest dielectric strength Eb (75 kV/cm were acquired at x = 0.25. The present ceramics should be very desirable for the applications such as high density energy storage devices.

Synthesis and Characterization of High-Dielectric-Constant Nanographite-Polyurethane Composite

Science.gov (United States)

Mishra, Praveen; Bhat, Badekai Ramachandra; Bhattacharya, B.; Mehra, R. M.

2018-05-01

In the face of ever-growing demand for capacitors and energy storage devices, development of high-dielectric-constant materials is of paramount importance. Among various dielectric materials available, polymer dielectrics are preferred for their good processability. We report herein synthesis and characterization of nanographite-polyurethane composite with high dielectric constant. Nanographite showed good dispersibility in the polyurethane matrix. The thermosetting nature of polyurethane gives the composite the ability to withstand higher temperature without melting. The resultant composite was studied for its dielectric constant (ɛ) as a function of frequency. The composite exhibited logarithmic variation of ɛ from 3000 at 100 Hz to 225 at 60 kHz. The material also exhibited stable dissipation factor (tan δ) across the applied frequencies, suggesting its ability to resist current leakage.

Dielectric coatings on metal substrates

International Nuclear Information System (INIS)

Glaros, S.S.; Baker, P.; Milam, D.

1976-01-01

Large aperture, beryllium substrate-based mirrors have been used to focus high intensity pulsed laser beams. Finished surfaces have high reflectivity, low wavefront distortion, and high laser damage thresholds. This paper describes the development of a series of metallic coatings, surface finishing techniques, and dielectric overcoatings to meet specified performance requirements. Beryllium substrates were coated with copper, diamond-machined to within 5 micro-inches to final contour, nickel plated, and abrasively figured to final contour. Bond strengths for several bonding processes are presented. Dielectric overcoatings were deposited on finished multimetallic substrates to increase both reflectivity and the damage thresholds. Coatings were deposited using both high and low temperature processes which induce varying stresses in the finished coating substrate system. Data are presented to show the evolution of wavefront distortion, reflectivity, and damage thresholds throughout the many steps involved in fabrication

Structure and performance of dielectric films based on self-assembled nanocrystals with a high dielectric constant.

Science.gov (United States)

Huang, Limin; Liu, Shuangyi; Van Tassell, Barry J; Liu, Xiaohua; Byro, Andrew; Zhang, Henan; Leland, Eli S; Akins, Daniel L; Steingart, Daniel A; Li, Jackie; O'Brien, Stephen

2013-10-18

Self-assembled films built from nanoparticles with a high dielectric constant are attractive as a foundation for new dielectric media with increased efficiency and range of operation, due to the ability to exploit nanofabrication techniques and emergent electrical properties originating from the nanoscale. However, because the building block is a discrete one-dimensional unit, it becomes a challenge to capture potential enhancements in dielectric performance in two or three dimensions, frequently due to surface effects or the presence of discontinuities. This is a recurring theme in nanoparticle film technology when applied to the realm of thin film semiconductor and device electronics. We present the use of chemically synthesized (Ba,Sr)TiO3 nanocrystals, and a novel deposition-polymerization technique, as a means to fabricate the dielectric layer. The effective dielectric constant of the film is tunable according to nanoparticle size, and effective film dielectric constants of up to 34 are enabled. Wide area and multilayer dielectrics of up to 8 cm(2) and 190 nF are reported, for which the building block is an 8 nm nanocrystal. We describe models for assessing dielectric performance, and distinct methods for improving the dielectric constant of a nanocrystal thin film. The approach relies on evaporatively driven assembly of perovskite nanocrystals with uniform size distributions in a tunable 7-30 nm size range, coupled with the use of low molecular weight monomer/polymer precursor chemistry that can infiltrate the porous nanocrystal thin film network post assembly. The intercrystal void space (low k dielectric volume fraction) is minimized, while simultaneously promoting intercrystal connectivity and maximizing volume fraction of the high k dielectric component. Furfuryl alcohol, which has good affinity to the surface of (Ba,Sr)TiO3 nanocrystals and miscibility with a range of solvents, is demonstrated to be ideal for the production of nanocomposites. The

Vectorial analysis of dielectric photonic crystal VCSEL

DEFF Research Database (Denmark)

Chung, Il-Sug; Mørk, Jesper

2009-01-01

A new vertical-cavity surface-emitting laser structure employing a dielectric photonic crystal mirror has been suggested and been numerically investigated. The new structure has a smaller threshold gain, a moderate strength of single-transverse-mode operation, a high quality of emission beam free...

Thermal Experimental Analysis for Dielectric Characterization of High Density Polyethylene Nanocomposites

Directory of Open Access Journals (Sweden)

Ahmed Thabet Mohamed

2016-01-01

Full Text Available The importance of nanoparticles in controlling physical properties of polymeric nanocomposite materials leads us to study effects of these nanoparticles on electric and dielectric properties of polymers in industry In this research, the dielectric behaviour of High-Density Polyethylene (HDPE nanocomposites materials that filled with nanoparticles of clay or fumed silica has been investigated at various frequencies (10 Hz-1 kHz and temperatures (20-60°C. Dielectric spectroscopy has been used to characterize ionic conduction, then, the effects of nanoparticles concentration on the dielectric losses and capacitive charge of the new nanocomposites can be stated. Capacitive charge and loss tangent in high density polyethylene nanocomposites are measured by dielectric spectroscopy. Different dielectric behaviour has been observed depending on type and concentration of nanoparticles under variant thermal conditions.

Dependence of optical phase modulation on anchoring strength of dielectric shield wall surfaces in small liquid crystal pixels

Science.gov (United States)

Isomae, Yoshitomo; Shibata, Yosei; Ishinabe, Takahiro; Fujikake, Hideo

2018-03-01

We demonstrated that the uniform phase modulation in a pixel can be realized by optimizing the anchoring strength on the walls and the wall width in the dielectric shield wall structure, which is the needed pixel structure for realizing a 1-µm-pitch optical phase modulator. The anchoring force degrades the uniformity of the phase modulation in ON-state pixels, but it also keeps liquid crystals from rotating against the leakage of an electric field. We clarified that the optimal wall width and anchoring strength are 250 nm and less than 10-4 J/m2, respectively.

Charge transport in polycrystalline alumina materials: application to the optimization of dielectric breakdown strength; Transport de charges dans les alumines polycristallines: application a l'optimisation de la rigidite dielectrique

Energy Technology Data Exchange (ETDEWEB)

Touzin, M.

2005-12-15

Dielectric breakdown constitutes an important limitation in the use of insulating materials under high-tension since it leads to the local fusion and the sublimation of material. The microstructure (average grain size, intergranular phase) has a great influence on the ability of material to resist this catastrophic phenomenon. Indeed, the interfaces between the various phases constitute potential sites of trapping for the charges. The optimization of the dielectric breakdown strength of a polycrystalline alumina sintered with a liquid phase passes necessarily through the control of the microstructural parameters. Thus, it is shown that by controlling the conditions of the process (rate of sintering aids, powder grain size and thermal cycle), it is possible to control the density (by the average grain size) but also the nature (by the crystallization or not of anorthite) of the grain boundaries. The study of the influence of these two parameters as well temperature on the properties of charge transport and storage was carried out by methods ICM and SEMME. The results, interpreted in light of the numerical simulation of the charge transport in bulk alumina sample during electron beam irradiation, allowed to highlight behaviors, and the corresponding microstructures, favourable to the dielectric breakdown resistance according to the considered temperature. Thus, at room temperature a high density of interfaces (low grain size and crystallized intergranular phase) makes it possible material to durably trap a great amount of charges, which leads to a high dielectric strength. On the other hand, at higher temperature, the presence of shallow traps (vitreous intergranular phase) supports the charge diffusion and makes it possible to delay breakdown. (author)

Dielectric breakdown in silica-amorphous polymer nanocomposite films: the role of the polymer matrix.

Science.gov (United States)

Grabowski, Christopher A; Fillery, Scott P; Westing, Nicholas M; Chi, Changzai; Meth, Jeffrey S; Durstock, Michael F; Vaia, Richard A

2013-06-26

The ultimate energy storage performance of an electrostatic capacitor is determined by the dielectric characteristics of the material separating its conductive electrodes. Polymers are commonly employed due to their processability and high breakdown strength; however, demands for higher energy storage have encouraged investigations of ceramic-polymer composites. Maintaining dielectric strength, and thus minimizing flaw size and heterogeneities, has focused development toward nanocomposite (NC) films; but results lack consistency, potentially due to variations in polymer purity, nanoparticle surface treatments, nanoparticle size, and film morphology. To experimentally establish the dominant factors in broad structure-performance relationships, we compare the dielectric properties for four high-purity amorphous polymer films (polymethyl methacrylate, polystyrene, polyimide, and poly-4-vinylpyridine) incorporating uniformly dispersed silica colloids (up to 45% v/v). Factors known to contribute to premature breakdown-field exclusion and agglomeration-have been mitigated in this experiment to focus on what impact the polymer and polymer-nanoparticle interactions have on breakdown. Our findings indicate that adding colloidal silica to higher breakdown strength amorphous polymers (polymethyl methacrylate and polyimide) causes a reduction in dielectric strength as compared to the neat polymer. Alternatively, low breakdown strength amorphous polymers (poly-4-vinylpyridine and especially polystyrene) with comparable silica dispersion show similar or even improved breakdown strength for 7.5-15% v/v silica. At ∼15% v/v or greater silica content, all the polymer NC films exhibit breakdown at similar electric fields, implying that at these loadings failure becomes independent of polymer matrix and is dominated by silica.

Investigation of the dielectric recovery in synthetic air in a high voltage circuit breaker

International Nuclear Information System (INIS)

Seeger, M; Naidis, G; Steffens, A; Nordborg, H; Claessens, M

2005-01-01

The dielectric recovery of an axially blown arc in an experimental set-up based on a conventional HV circuit breaker was investigated both experimentally and theoretically. As a quenching gas, synthetic air was used. The investigated time range was from 10 μs to 10 ms after current zero (CZ). A fast rise in the dielectric strength during the first 100 μs, followed by a plateau and further rise later was observed. The dependences on the breaking current and pressure were determined. The measured dielectric recovery during the first 100 μs after CZ could be reproduced with good accuracy by computational fluid dynamics simulations. From that it could be deduced that the temperature decay in the axis does not depend sensitively on the pressure. The dielectric recovery during the first 100 μs scales therefore mainly with the filling pressure. The plateau in the breakdown characteristic is due to a hot vapour layer from the still evaporating PTFE nozzle surface

Humidity effects on wire insulation breakdown strength.

Energy Technology Data Exchange (ETDEWEB)

Appelhans, Leah

2013-08-01

Methods for the testing of the dielectric breakdown strength of insulation on metal wires under variable humidity conditions were developed. Two methods, an ASTM method and the twisted pair method, were compared to determine if the twisted pair method could be used for determination of breakdown strength under variable humidity conditions. It was concluded that, although there were small differences in outcomes between the two testing methods, the non-standard method (twisted pair) would be appropriate to use for further testing of the effects of humidity on breakdown performance. The dielectric breakdown strength of 34G copper wire insulated with double layer Poly-Thermaleze/Polyamide-imide insulation was measured using the twisted pair method under a variety of relative humidity (RH) conditions and exposure times. Humidity at 50% RH and below was not found to affect the dielectric breakdown strength. At 80% RH the dielectric breakdown strength was significantly diminished. No effect for exposure time up to 140 hours was observed at 50 or 80%RH.

Investigations on perturbations of microwave dielectric resonator thermometer

International Nuclear Information System (INIS)

Yu, Lili; Zhang, Guangming; Fernicola, V; Lu, Jinchuan

2017-01-01

Investigations of antenna probe length, antenna-dielectric distance, cavity filling and humidity on microwave resonator thermometer with respect to Q , spurious mode depression, coupling strength, accuracy, shock resistance or sensitivity were carried out in order to improve the dielectric resonator thermometer performance. Significant improvement of Q and depression of spurious mode coupling were obtained when the antenna length was reduced. It also turns out that the Q and spurious mode coupling strength vary with the distance between dielectric and antenna pin, as well under appropriate antenna length. Filling the cavity with nitrogen increases coupling strength but decrease frequency-temperature sensitivity compared to a vacuum-pumped cavity. Besides, preliminary results on the microwave resonator sensitivity to air humidity were obtained. (technical note)

Dielectric properties of polyhedral oligomeric silsesquioxane (POSS)-based nanocomposites at 77k

International Nuclear Information System (INIS)

Pan, Ming-Jen; Gorzkowski, Edward; McAllister, Kelly

2011-01-01

The goal of this study is to develop dielectric nanocomposites for high energy density applications at liquid nitrogen temperature by utilizing a unique nano-material polyhedral oligomeric silsesquioxanes (POSS). A POSS molecule is consisted of a silica cage core with 8 silicon and 12 oxygen atoms and organic functional groups attached to the corners of the cage. In this study, we utilize POSS for the fabrication of nanocomposites both as a silica nanoparticle filler to enhance the breakdown strength and as a surfactant for effective dispersion of high permittivity ceramic nanoparticles in a polymer matrix. The matrix materials selected for the study are polyvinylidene fluoride (PVDF) and poly(methyl methacrylate) (PMMA). The ceramic nanoparticles are barium strontium titanate (BST 50/50) and strontium titanate. The dielectric properties of the solution-cast nanocomposites films were correlated to the composition and processing conditions. We determined that the addition of POSS did not provide enhanced dielectric performance in PVDF- and PMMA-based materials at either room temperature or 77K. In addition, we found that the dielectric breakdown strength of PMMA is lower at 77K than at room temperature, contradicting literature data.

Dielectric constant and electrical conductivity of contaminated fine-grained soils and barrier materials

International Nuclear Information System (INIS)

Kaya, A.; Fang, H.Y.; Inyang, H.I.

1997-01-01

Characterization of contaminated fine-grained soils and tracking of contaminant migration within barriers have been challenging because current methods and/or procedures are labor and time-intensive, and destructive. To demonstrate the effective use of both dielectric constant and electrical conductivity in the characterization of contaminated fine-grained soils, pore fluids were prepared at different ionic strengths, and were used as permeates for kaolinite, bentonite and a local soil. Then, both dielectric constant and electrical conductivity of the soils were measured by means of a capacitor over a wide range of frequencies and moisture content. It was observed that although each soil has its unique dielectric constant and electrical conductivity at a given moisture content, increases in ionic strength cause a decrease in the dielectric constant of the system at very high frequencies (MHZ), whereas the dielectric constant increases at low frequencies (kHz). Electrical conductivity of a soil-water system is independent of frequency. However, it is a function of ionic strength of the pore fluid. It is clearly demonstrated that dielectric constant and electrical conductivity of soils are functions of both moisture content and ionic strength, and can be used to characterize the spatial and temporal levels of contamination. This method/procedure can be used in estimating the level of contamination as well as the direction of contaminant movement in the subsurface without the use of extensive laboratory testing. Based on obtained results, it was concluded that the proposed method/procedure is promising because it is non-destructive and provides a quick means of assessing the spatial distribution of contaminants in fine-grained soils and barriers

High Gain and High Directive of Antenna Arrays Utilizing Dielectric Layer on Bismuth Titanate Ceramics

Directory of Open Access Journals (Sweden)

F. H. Wee

2012-01-01

Full Text Available A high gain and high directive microstrip patch array antenna formed from dielectric layer stacked on bismuth titanate (BiT ceramics have been investigated, fabricated, and measured. The antennas are designed and constructed with a combination of two-, four-, and six-BiT elements in an array form application on microwave substrate. For gain and directivity enhancement, a layer of dielectric was stacked on the BiT antenna array. We measured the gain and directivity of BiT array antennas with and without the dielectric layer and found that the gain of BiT array antenna with the dielectric layer was enhanced by about 1.4 dBi of directivity and 1.3 dB of gain over the one without the dielectric layer at 2.3 GHz. The impedance bandwidth of the BiT array antenna both with and without the dielectric layer is about 500 MHz and 350 MHz, respectively, which is suitable for the application of the WiMAX 2.3 GHz system. The utilization of BiT ceramics that covers about 90% of antenna led to high radiation efficiency, and small-size antennas were produced. In order to validate the proposed design, theoretical and measured results are provided and discussed.

Study of HV Dielectrics for High Frequency Operation in Linear & Nonlinear Transmission Lines & Simulation & Development of Hybrid Nonlinear Lines for RF Generation

Science.gov (United States)

2015-08-27

As shown in [4], [5], the capacitors based on PZT (lead-zirconate- titanate) and BT dielectrics have dielectric BD strength of the order of 50 kV/cm...results. Depending on the nonlinearity properties of the capacitor dielectric , input pulse rise time, output pulse sharpening and or RF soliton... capacitors in a frequency range up to 2 MHz, below the resonant frequency of the both dielectrics . As seen in Fig. 1, PZTs have better performance than

STRENGTH OF NANOMODIFIED HIGH-STRENGTH LIGHTWEIGHT CONCRETES

Directory of Open Access Journals (Sweden)

NOZEMTСEV Alexandr Sergeevich

2013-02-01

Full Text Available The paper presents the results of research aimed at development of nanomodified high-strength lightweight concrete for construction. The developed concretes are of low average density and high ultimate compressive strength. It is shown that to produce this type of concrete one need to use hollow glass and aluminosilicate microspheres. To increase the durability of adhesion between cement stone and fine filler the authors offer to use complex nanodimensinal modifier based on iron hydroxide sol and silica sol as a surface nanomodifier for hollow microspheres. It is hypothesized that the proposed modifier has complex effect on the activity of the cement hydration and, at the same time increases bond strength between filler and cement-mineral matrix. The compositions for energy-efficient nanomodified high-strength lightweight concrete which density is 1300…1500 kg/m³ and compressive strength is 40…65 MPa have been developed. The approaches to the design of high-strength lightweight concrete with density of less than 2000 kg/m³ are formulated. It is noted that the proposed concretes possess dense homogeneous structure and moderate mobility. Thus, they allow processing by vibration during production. The economic and practical implications for realization of high-strength lightweight concrete in industrial production have been justified.

Dielectric properties of polycarbonate coated natural fabric Grewia tilifolia

CSIR Research Space (South Africa)

Ramana, CHVV

2011-12-01

Full Text Available attraction of bio-fiber reinforced composites lie in their low density and high strength. Polymer composites of a polycarbonate coated with natural fabric Grewia tilifolia were studied by means of dielectric properties in the frequency range 100 Hz to 1 MHz...

The electric strength of high-voltage transformers insulation at effect of partial dischargers

International Nuclear Information System (INIS)

Khoshravan, E.; Zeraatparvar, A.; Gashimov, A.M.; Mehdizadeh, R.N.

2001-01-01

Full text : In paper the change of electric strength of high-voltage transformers insulation at the effect of partial discharges with space charge accumulation was investigated. It is revealed that the effect of partial discharges of insulation materials results the reduction of their pulsing electric strength which can restore the own initial value at releasing of saved charge the volume of a material under condition of absence the ineversible structural changes in it. Researches of high-voltage transformers insulation's non-failure operation conditions show, that at increasing of insulation work time in a strong electrical field the reduction of average breakdown voltages with simultaneous increasing of spread in discharge voltage values takes place. It authentically testifies to reduction of short-time discharge voltage of insulation materials during their electrical aging. As the basic reason of insulation electrical aging the partial discharges occurring in gas cavities inside insulation were considered. It is known that the space charges will be formed in insulation elements of high-voltage devices which effects in dielectrical property of these elements including the electric strength and the space charge formation can occur also at partial discharges in an alternating voltage while the service of high-voltage transformers. In the given work the experiments in revealing separate influence partial discharges in pulsing electric strength of insulation materials at presence and at absence inside them the space charge were spent

High-Tensile Strength Tape Versus High-Tensile Strength Suture: A Biomechanical Study.

Science.gov (United States)

Gnandt, Ryan J; Smith, Jennifer L; Nguyen-Ta, Kim; McDonald, Lucas; LeClere, Lance E

2016-02-01

To determine which suture design, high-tensile strength tape or high-tensile strength suture, performed better at securing human tissue across 4 selected suture techniques commonly used in tendinous repair, by comparing the total load at failure measured during a fixed-rate longitudinal single load to failure using a biomechanical testing machine. Matched sets of tendon specimens with bony attachments were dissected from 15 human cadaveric lower extremities in a manner allowing for direct comparison testing. With the use of selected techniques (simple Mason-Allen in the patellar tendon specimens, whip stitch in the quadriceps tendon specimens, and Krackow stitch in the Achilles tendon specimens), 1 sample of each set was sutured with a 2-mm braided, nonabsorbable, high-tensile strength tape and the other with a No. 2 braided, nonabsorbable, high-tensile strength suture. A total of 120 specimens were tested. Each model was loaded to failure at a fixed longitudinal traction rate of 100 mm/min. The maximum load and failure method were recorded. In the whip stitch and the Krackow-stitch models, the high-tensile strength tape had a significantly greater mean load at failure with a difference of 181 N (P = .001) and 94 N (P = .015) respectively. No significant difference was found in the Mason-Allen and simple stitch models. Pull-through remained the most common method of failure at an overall rate of 56.7% (suture = 55%; tape = 58.3%). In biomechanical testing during a single load to failure, high-tensile strength tape performs more favorably than high-tensile strength suture, with a greater mean load to failure, in both the whip- and Krackow-stitch models. Although suture pull-through remains the most common method of failure, high-tensile strength tape requires a significantly greater load to pull-through in a whip-stitch and Krakow-stitch model. The biomechanical data obtained in the current study indicates that high-tensile strength tape may provide better repair

Silver Nanowire/MnO2 Nanowire Hybrid Polymer Nanocomposites: Materials with High Dielectric Permittivity and Low Dielectric Loss.

Science.gov (United States)

Zeraati, Ali Shayesteh; Arjmand, Mohammad; Sundararaj, Uttandaraman

2017-04-26

This study reports the fabrication of hybrid nanocomposites based on silver nanowire/manganese dioxide nanowire/poly(methyl methacrylate) (AgNW/MnO 2 NW/PMMA), using a solution casting technique, with outstanding dielectric permittivity and low dielectric loss. AgNW was synthesized using the hard-template technique, and MnO 2 NW was synthesized employing a hydrothermal method. The prepared AgNW:MnO 2 NW (2.0:1.0 vol %) hybrid nanocomposite showed a high dielectric permittivity (64 at 8.2 GHz) and low dielectric loss (0.31 at 8.2 GHz), which are among the best reported values in the literature in the X-band frequency range (8.2-12.4 GHz). The superior dielectric properties of the hybrid nanocomposites were attributed to (i) dimensionality match between the nanofillers, which increased their synergy, (ii) better dispersion state of AgNW in the presence of MnO 2 NW, (iii) positioning of ferroelectric MnO 2 NW in between AgNWs, which increased the dielectric permittivity of nanodielectrics, thereby increasing dielectric permittivity of the hybrid nanocomposites, (iv) barrier role of MnO 2 NW, i.e., cutting off the contact spots of AgNWs and leading to lower dielectric loss, and (v) AgNW aligned structure, which increased the effective surface area of AgNWs, as nanoelectrodes. Comparison of the dielectric properties of the developed hybrid nanocomposites with the literature highlights their great potential for flexible capacitors.

Development of High-Gradient Dielectric Laser-Driven Particle Accelerator Structures

Energy Technology Data Exchange (ETDEWEB)

Byer, Robert L. [Stanford Univ., CA (United States). Edward L. Ginzton Lab.

2013-11-07

The thrust of Stanford's program is to conduct research on high-gradient dielectric accelerator structures driven with high repetition-rate, tabletop infrared lasers. The close collaboration between Stanford and SLAC (Stanford Linear Accelerator Center) is critical to the success of this project, because it provides a unique environment where prototype dielectric accelerator structures can be rapidly fabricated and tested with a relativistic electron beam.

Large energy storage efficiency of the dielectric layer of graphene nanocapacitors

Science.gov (United States)

Bezryadin, A.; Belkin, A.; Ilin, E.; Pak, M.; Colla, Eugene V.; Hubler, A.

2017-12-01

Electric capacitors are commonly used in electronic circuits for the short-term storage of small amounts of energy. It is desirable however to use capacitors to store much larger energy amounts to replace rechargeable batteries. Unfortunately existing capacitors cannot store sufficient energy to be able to replace common electrochemical energy storage systems. Here we examine the energy storage capabilities of graphene nanocapacitors, which are tri-layer devices involving an Al film, Al2O3 dielectric layer, and a single layer of carbon atoms, i.e., graphene. This is a purely electronic capacitor and therefore it can function in a wide temperature interval. The capacitor shows a high dielectric breakdown electric field strength, of the order of 1000 kV mm-1 (i.e., 1 GV m-1), which is much larger than the table value of the Al2O3 dielectric strength. The corresponding energy density is 10-100 times larger than the energy density of a common electrolytic capacitor. Moreover, we discover that the amount of charge stored in the dielectric layer can be equal or can even exceed the amount of charge stored on the capacitor plates. The dielectric discharge current follows a power-law time dependence. We suggest a model to explain this behavior.

Large energy storage efficiency of the dielectric layer of graphene nanocapacitors.

Science.gov (United States)

Bezryadin, A; Belkin, A; Ilin, E; Pak, M; Colla, Eugene V; Hubler, A

2017-12-08

Electric capacitors are commonly used in electronic circuits for the short-term storage of small amounts of energy. It is desirable however to use capacitors to store much larger energy amounts to replace rechargeable batteries. Unfortunately existing capacitors cannot store sufficient energy to be able to replace common electrochemical energy storage systems. Here we examine the energy storage capabilities of graphene nanocapacitors, which are tri-layer devices involving an Al film, Al 2 O 3 dielectric layer, and a single layer of carbon atoms, i.e., graphene. This is a purely electronic capacitor and therefore it can function in a wide temperature interval. The capacitor shows a high dielectric breakdown electric field strength, of the order of 1000 kV mm -1 (i.e., 1 GV m -1 ), which is much larger than the table value of the Al 2 O 3 dielectric strength. The corresponding energy density is 10-100 times larger than the energy density of a common electrolytic capacitor. Moreover, we discover that the amount of charge stored in the dielectric layer can be equal or can even exceed the amount of charge stored on the capacitor plates. The dielectric discharge current follows a power-law time dependence. We suggest a model to explain this behavior.

Dielectric properties of PMMA/Soot nanocomposites.

Science.gov (United States)

Clayton, Lanetra M; Cinke, Martin; Meyyappan, M; Harmon, Julie P

2007-07-01

Dielectric analysis (DEA) of relaxation behavior in poly(methyl methacrylate) (PMMA) soot nanocomposites is described herein. The soot, an inexpensive material, consists of carbon nanotubes, amorphous and graphitic carbon and metal particles. Results are compared to earlier studies on PMMA/multi-walled nanotube (MWNT) composites and PMMA/single-walled nanotube (SWNT) composites. The beta relaxation process appeared to be unaffected by the presence of the soot, as was noted earlier in nanotube composites. The gamma relaxation region in PMMA, normally dielectrically inactive, was "awakened" in the PMMA/soot composite. This occurrence is consistent with previously published data on nanotube composites. The dielectric permittivity, s', increased with soot content. The sample with 1% soot exhibited a permittivity (at 100 Hz and 25 degrees C) of 7.3 as compared to 5.1 for neat PMMA. Soot increased the dielectric strength, deltaE, of the composites. The 1% soot sample exhibited a dielectric strength of 6.38, while the neat PMMA had a value of 2.95 at 40 degrees C. The symmetric broadening term (alpha) was slightly higher for the 1% composite at temperatures near the secondary relaxation and near the primary relaxation, but all samples deviated from symmetrical semi-circular behavior (alpha = 1). The impact of the soot filler is seen more clearly in dielectric properties than in mechanical properties studies conducted earlier.

Bimodal condensation silicone elastomers as dielectric elastomers

DEFF Research Database (Denmark)

Yu, Liyun; Madsen, Frederikke Bahrt; Skov, Anne Ladegaard

Lately, dielectric elastomers (DEs) which consist of an elastomer sandwiched between electrodes on both sides, have gained interest as materials for actuators, generators, and sensors. An ideal elastomer for DE uses is characterized by high extensibility, flexibility and good mechanical fatigue...... elastomers were prepared by mixing different mass ratios (9:1, 8:2, 7:3, 6:4, 5:5, 4:6) between long polydimethylsiloxane (PDMS) chains and short PDMS chains. The resulting elastomers were investigated with respect to their rheology, dielectric properties, tensile strength, electrical breakdown, as well.......Moreover, a series of elastomers with the same mass ratio (7:3) between long and short PDMS chains were made at different humidity (90%, 70%, 50%, 30%, 10%) at 23oC. The dielectric and mechincal properties of the resulting elastomers were shown to depend strongly on the atmospheric humidity level.In addition...

Modeling the dielectric logging tool at high frequency

International Nuclear Information System (INIS)

Chew, W.C.

1987-01-01

The high frequency dielectric logging tool has been used widely in electromagnetic well logging, because by measuring the dielectric constant at high frequencies (1 GHz), the water saturation of rocks could be known without measuring the water salinity in the rocks. As such, it could be used to delineate fresh water bearing zones, as the dielectric constant of fresh water is much higher than that of oil while they may have the same resistivity. The authors present a computer model, though electromagnetic field analysis, the response of such a measurement tool in a well logging environment. As the measurement is performed at high frequency, usually with small separation between the transmitter and receivers, some small geological features could be measured by such a tool. They use the computer model to study the behavior of such a tool across geological bed boundaries, and also across thin geological beds. Such a study could be very useful in understanding the limitation on the resolution of the tool. Furthermore, they could study the standoff effect and the depth of investigation of such a tool. This could delineate the range of usefulness of the measurement

Drift mobility of thermalized and highly energetic holes in thin layers of amorphous dielectric SiC

International Nuclear Information System (INIS)

Sielski, Jan; Jeszka, Jeremiasz K.

2012-01-01

The development of new technology in the electronics industry requires new dielectric materials. It is also important to understand the charge-carrier transport mechanism in these materials. We examined the hole drift mobility in amorphous SiC dielectric thin films using the time-of-flight (TOF) method. Charge carriers were generated using an electron gun. The generated holes gave a dispersive TOF signal and the mobility was low. For electric field strengths above 4 x 10 5 V cm -1 the drift mobility shows a very strong dependence on the electric field and a weak temperature dependence (transport of ''high-energy'' charge carriers). At lower electric fields and for thermalized charge carriers the mobility is practically field independent and thermally activated. The observed phenomenon was attributed to the changes in the effective energy of the generated carriers moving in the high electric fields and consequently in the density of localized states taking part in the transport. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Significant performance enhancement in AlGaN/GaN high electron mobility transistor by high-κ organic dielectric

International Nuclear Information System (INIS)

Ze-Gao, Wang; Yuan-Fu, Chen; Cao, Chen; Ben-Lang, Tian; Fu-Tong, Chu; Xing-Zhao, Liu; Yan-Rong, Li

2010-01-01

The electrical properties of AlGaN/GaN high electron mobility transistor (HEMT) with and without high-κ organic dielectrics are investigated. The maximum drain current I D max and the maximum transconductance g m max of the organic dielectric/AlGaN/GaN structure can be enhanced by 74.5%, and 73.7% compared with those of the bare AlGaN/GaN HEMT, respectively. Both the threshold voltage V T and g m max of the dielectric/AlGaN/GaN HEMT are strongly dielectric-constant-dependent. Our results suggest that it is promising to significantly improve the performance of the AlGaN/GaN HEMT by introducing the high-κ organic dielectric. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

High-pressure cell for simultaneous dielectric and neutron spectroscopy

DEFF Research Database (Denmark)

Sanz, Alejandro; Hansen, Henriette Wase; Jakobsen, Bo

2018-01-01

In this article, we report on the design, manufacture, and testing of a high-pressure cell for simultaneous dielectric and neutron spectroscopy. This cell is a unique tool for studying dynamics on different time scales, from kilo- to picoseconds, covering universal features such as the α relaxation......, a cylindrical capacitor is positioned within the bore of the high-pressure container. The capacitor consists of two concentric electrodes separated by insulating spacers. The performance of this setup has been successfully verified by collecting simultaneous dielectric and neutron spectroscopy data...

Coaxial two-channel high-gradient dielectric wakefield accelerator

Directory of Open Access Journals (Sweden)

G. V. Sotnikov

2009-06-01

Full Text Available A new scheme for a dielectric wakefield accelerator is proposed that employs a cylindrical multizone dielectric structure configured as two concentric dielectric tubes with outer and inner vacuum channels for drive and accelerated bunches. Analytical and numerical studies have been carried out for such coaxial dielectric-loaded structures (CDS for high-gradient acceleration. An analytical theory of wakefield excitation by particle bunches in a multizone CDS has been formulated. Numerical calculations are presented for an example of a CDS using dielectric tubes with dielectric permittivity 5.7, having external diameters of 2.121 and 0.179 mm with inner diameters of 2.095 and 0.1 mm. An annular 5 GeV, 6 nC electron bunch with rms length of 0.035 mm energizes a wakefield on the structure axis having an accelerating gradient of ∼600  MeV/m with a transformer ratio ∼8∶1. The period of the accelerating field is ∼0.33  mm. If the width of the drive bunch channel is decreased, it is possible to obtain an accelerating gradient of >1  GeV/m while keeping the transformer ratio approximately the same. Full numerical simulations using a particle-in-cell code have confirmed results of the linear theory and furthermore have shown the important influence of the quenching wave that restricts the region of the wakefield to within several periods following the drive bunch. Numerical simulations for another example have shown nearly stable transport of drive and accelerated bunches through the CDS, using a short train of drive bunches.

Possible Lead Free Nanocomposite Dielectrics for High Energy Storage Applications

Directory of Open Access Journals (Sweden)

Srinivas Kurpati

2017-03-01

Full Text Available There is an increasing demand to improve the energy density of dielectric capacitors for satisfying the next generation material systems. One effective approach is to embed high dielectric constant inclusions such as lead zirconia titanate in polymer matrix. However, with the increasing concerns on environmental safety and biocompatibility, the need to expel lead (Pb from modern electronics has been receiving more attention. Using high aspect ratio dielectric inclusions such as nanowires could lead to further enhancement of energy density. Therefore, the present brief review work focuses on the feasibility of development of a lead-free nanowire reinforced polymer matrix capacitor for energy storage application. It is expected that Lead-free sodium Niobate nanowires (NaNbO3 and Boron nitride will be a future candidate to be synthesized using simple hydrothermal method, followed by mixing them with polyvinylidene fluoride (PVDF/ divinyl tetramethyl disiloxanebis (benzocyclobutene matrix using a solution-casting method for Nanocomposites fabrication. The energy density of NaNbO3 and BN based composites are also be compared with that of lead-containing (PbTiO3/PVDF Nano composites to show the feasibility of replacing lead-containing materials from high-energy density dielectric capacitors. Further, this paper explores the feasibility of these materials for space applications because of high energy storage capacity, more flexibility and high operating temperatures. This paper is very much useful researchers who would like to work on polymer nanocomposites for high energy storage applications.

Extraction and dielectric properties of curcuminoid films grown on Si substrate for high-k dielectric applications

Energy Technology Data Exchange (ETDEWEB)

Dakhel, A.A.; Jasim, Khalil E. [Department of Physics, College of Science, University of Bahrain, P.O. Box 32038 (Bahrain); Cassidy, S. [Department of Basic Medical Sciences, Royal College of Surgeons in Ireland, Medical University of Bahrain, P.O. Box 15503 (Bahrain); Henari, F.Z., E-mail: fzhenari@rcsi-mub.com [Department of Basic Medical Sciences, Royal College of Surgeons in Ireland, Medical University of Bahrain, P.O. Box 15503 (Bahrain)

2013-09-20

Highlights: • The unknown insulating properties of curcuminoid extract are systematically studied. • Optical study gives a bandgap of 3.15 eV and a refractive index of 1.92 at 505 nm. • Turmeric is a high-k environmental friendly material for use in microelectronics. • Curcuminoid extract can be used as insulator of MIS devices with ε{sup ′}{sub ∞}≈54.2. -- Abstract: Curcuminoids were extracted from turmeric powder and evaporated in vacuum to prepare thin films on p-Si and glass substrates for dielectric and optical investigations. The optical absorption spectrum of the prepared amorphous film was not identical to that of the molecular one, which was identified by a strong wide absorption band in between ∼220 and 540 nm. The onset energy of the optical absorption of the film was calculated by using Hamberg et al. method. The dielectric properties of this material were systematically studied for future eco friendly applications in metal–insulator–semiconductor MIS field of applications. The complex dielectric properties were studied in the frequency range of 1–1000 kHz and was analysed in-terms of dielectric impedance Z{sup *}(ω) and modulus M{sup *}(ω). Generally, the curcuminoid complex can be considered as a high-k material and can be used in the environmental friendly production of microelectronic devices.

Extraction and dielectric properties of curcuminoid films grown on Si substrate for high-k dielectric applications

International Nuclear Information System (INIS)

Dakhel, A.A.; Jasim, Khalil E.; Cassidy, S.; Henari, F.Z.

2013-01-01

Highlights: • The unknown insulating properties of curcuminoid extract are systematically studied. • Optical study gives a bandgap of 3.15 eV and a refractive index of 1.92 at 505 nm. • Turmeric is a high-k environmental friendly material for use in microelectronics. • Curcuminoid extract can be used as insulator of MIS devices with ε ′ ∞ ≈54.2. -- Abstract: Curcuminoids were extracted from turmeric powder and evaporated in vacuum to prepare thin films on p-Si and glass substrates for dielectric and optical investigations. The optical absorption spectrum of the prepared amorphous film was not identical to that of the molecular one, which was identified by a strong wide absorption band in between ∼220 and 540 nm. The onset energy of the optical absorption of the film was calculated by using Hamberg et al. method. The dielectric properties of this material were systematically studied for future eco friendly applications in metal–insulator–semiconductor MIS field of applications. The complex dielectric properties were studied in the frequency range of 1–1000 kHz and was analysed in-terms of dielectric impedance Z * (ω) and modulus M * (ω). Generally, the curcuminoid complex can be considered as a high-k material and can be used in the environmental friendly production of microelectronic devices

Numerical investigation of dielectric barrier discharges

Science.gov (United States)

Li, Jing

1997-12-01

A dielectric barrier discharge (DBD) is a transient discharge occurring between two electrodes in coaxial or planar arrangements separated by one or two layers of dielectric material. The charge accumulated on the dielectric barrier generates a field in a direction opposite to the applied field. The discharge is quenched before an arc is formed. It is one of the few non-thermal discharges that operates at atmospheric pressure and has the potential for use in pollution control. In this work, a numerical model of the dielectric barrier discharge is developed, along with the numerical approach. Adaptive grids based on the charge distribution is used. A self-consistent method is used to solve for the electric field and charge densities. The Successive Overrelaxation (SOR) method in a non-uniform grid spacing is used to solve the Poisson's equation in the cylindrically-symmetric coordinate. The Flux Corrected Transport (FCT) method is modified to solve the continuity equations in the non-uniform grid spacing. Parametric studies of dielectric barrier discharges are conducted. General characteristics of dielectric barrier discharges in both anode-directed and cathode-directed streamer are studied. Effects of the dielectric capacitance, the applied field, the resistance in external circuit and the type of gases (O2, air, N2) are investigated. We conclude that the SOR method in an adaptive grid spacing for the solution of the Poisson's equation in the cylindrically-symmetric coordinate is convergent and effective. The dielectric capacitance has little effect on the g-factor of radical production, but it determines the strength of the dielectric barrier discharge. The applied field and the type of gases used have a significant role on the current peak, current pulse duration and radical generation efficiency, discharge strength, and microstreamer radius, whereas the external series resistance has very little effect on the streamer properties. The results are helpful in

From surface to volume plasmons in hyperbolic metamaterials: General existence conditions for bulk high-k waves in metal-dielectric and graphene-dielectric multilayers

DEFF Research Database (Denmark)

Zhukovsky, Sergei; Andryieuski, Andrei; Sipe, John E.

2014-01-01

-dielectric and recently introduced graphene-dielectric stacks. We confirm that short-range surface plasmons in thin metal layers can give rise to hyperbolic metamaterial properties and demonstrate that long-range surface plasmons cannot. We also show that graphene-dielectric multilayers tend to support high- k waves...

Dielectric characterization of high-performance spaceflight materials

Science.gov (United States)

Kleppe, Nathan; Nurge, Mark A.; Bowler, Nicola

2015-03-01

As commercial space travel increases, the need for reliable structural health monitoring to predict possible weaknesses or failures of structural materials also increases. Monitoring of these materials can be done through the use of dielectric spectroscopy by comparing permittivity or conductivity measurements performed on a sample in use to that of a pristine sample from 100 μHz to 3 GHz. Fluctuations in these measured values or of the relaxation frequencies, if present, can indicate chemical or physical changes occurring within the material and the possible need for maintenance/replacement. In this work, we establish indicative trends that occur due to changes in dielectric spectra during accelerated aging of various high-performance polymeric materials: ethylene vinyl alcohol (EVOH), Poly (ether ether ketone) (PEEK), polyphenylene sulfide (PPS), and ultra-high molecular weight polyethylene (UHMWPE). Uses for these materials range from electrical insulation and protective coatings to windows and air- or space-craft parts that may be subject to environmental damage over long-term operation. Samples were prepared by thermal exposure and, separately, by ultraviolet/water-spray cyclic aging. The aged samples showed statistically-significant trends of either increasing or decreasing real or imaginary permittivity values, relaxation frequencies, conduction or the appearance of new relaxation modes. These results suggest that dielectric testing offers the possibility of nondestructive evaluation of the extent of age-related degradation in these materials.

High-κ gate dielectrics: Current status and materials properties considerations

Science.gov (United States)

Wilk, G. D.; Wallace, R. M.; Anthony, J. M.

2001-05-01

Many materials systems are currently under consideration as potential replacements for SiO2 as the gate dielectric material for sub-0.1 μm complementary metal-oxide-semiconductor (CMOS) technology. A systematic consideration of the required properties of gate dielectrics indicates that the key guidelines for selecting an alternative gate dielectric are (a) permittivity, band gap, and band alignment to silicon, (b) thermodynamic stability, (c) film morphology, (d) interface quality, (e) compatibility with the current or expected materials to be used in processing for CMOS devices, (f) process compatibility, and (g) reliability. Many dielectrics appear favorable in some of these areas, but very few materials are promising with respect to all of these guidelines. A review of current work and literature in the area of alternate gate dielectrics is given. Based on reported results and fundamental considerations, the pseudobinary materials systems offer large flexibility and show the most promise toward successful integration into the expected processing conditions for future CMOS technologies, especially due to their tendency to form at interfaces with Si (e.g. silicates). These pseudobinary systems also thereby enable the use of other high-κ materials by serving as an interfacial high-κ layer. While work is ongoing, much research is still required, as it is clear that any material which is to replace SiO2 as the gate dielectric faces a formidable challenge. The requirements for process integration compatibility are remarkably demanding, and any serious candidates will emerge only through continued, intensive investigation.

High-k dielectrics as bioelectronic interface for field-effect transistors

Energy Technology Data Exchange (ETDEWEB)

Borstlap, D

2007-03-15

Ion-sensitive field-effect transistors (ISFETs) are employed as bioelectronic sensors for the cell-transistor coupling and for the detection of DNA sequences. For these applications, thermally grown SiO{sub 2} films are used as standard gate dielectric. In the first part of this dissertation, the suitability of high-k dielectrics was studied to increase the gate capacitance and hence the signal-to-noise ratio of bioelectronic ISFETs: Upon culturing primary rat neurons on the corresponding high-k dielectrics, Al{sub 2}O{sub 3}, yttria stabilised zirkonia (YSZ), DyScO{sub 3}, CeO{sub 2}, LaAlO{sub 3}, GdScO{sub 3} and LaScO{sub 3} proved to be biocompatible substrates. Comprehensive electrical and electrochemical current-voltage measurements and capacitance-voltage measurements were performed for the determination of the dielectric properties of the high-k dielectrics. In the second part of the dissertation, standard SiO{sub 2} ISFETs with lower input capacitance and high-k dielectric Al{sub 2}O{sub 3}, YSZ und DyScO{sub 3} ISFETs were comprehensively characterised and compared with each other regarding their signal-to-noise ratio, their ion sensitivity and their drift behaviour. The ion sensitivity measurements showed that the YSZ ISFETs were considerably more sensitive to K{sup +} and Na{sup +} ions than the SiO{sub 2}, Al{sub 2}O{sub 3} und DyScO{sub 3} ISFETs. In the final third part of the dissertation, bioelectronic experiments were performed with the high-k ISFETs. The shape of the signals, which were measured from HL-1 cells with YSZ ISFETs, differed considerably from the corresponding measurements with SiO{sub 2} and DyScO{sub 3} ISFETs: After the onset of the K{sup +} current, the action potentials measured with YSZ ISFETs showed a strong drift in the direction opposite to the K{sup +} current signal. First coupling experiments between HEK 293 cells, which were transfected with a K{sup +} ion channel, and YSZ ISFETs affirmed the assumption from the HL-1

High temperature dielectric studies of indium-substituted NiCuZn nanoferrites

Science.gov (United States)

Hashim, Mohd.; Raghasudha, M.; Shah, Jyoti; Shirsath, Sagar E.; Ravinder, D.; Kumar, Shalendra; Meena, Sher Singh; Bhatt, Pramod; Alimuddin; Kumar, Ravi; Kotnala, R. K.

2018-01-01

In this study, indium (In3+)-substituted NiCuZn nanostructured ceramic ferrites with a chemical composition of Ni0.5Cu0.25Zn0.25Fe2-xInxO4 (0.0 ≤ x ≤ 0.5) were prepared by chemical synthesis involving sol-gel chemistry. Single phased cubic spinel structure materials were prepared successfully according to X-ray diffraction and transmission electron microscopy analyses. The dielectric properties of the prepared ferrites were measured using an LCR HiTester at temperatures ranging from room temperature to 300 °C at different frequencies from 102 Hz to 5 × 106 Hz. The variations in the dielectric parameters ε‧ and (tanδ) with temperature demonstrated the frequency- and temperature-dependent characteristics due to electron hopping between the ions. The materials had low dielectric loss values in the high frequency range at all temperatures, which makes them suitable for high frequency microwave applications. A qualitative explanation is provided for the dependences of the dielectric constant and dielectric loss tangent on the frequency, temperature, and composition. Mӧssbauer spectroscopy was employed at room temperature to characterize the magnetic behavior.

The relationship between chemical structure and dielectric properties of plasma-enhanced chemical vapor deposited polymer thin films

Energy Technology Data Exchange (ETDEWEB)

Jiang Hao [Materials Sci and Tech Applications, LLC, 409 Maple Springs Drive, Dayton OH 45458 (United States)]. E-mail: hao.jiang@wpafb.af.mil; Hong Lianggou [Materials Sci and Tech Applications, LLC, 409 Maple Springs Drive, Dayton OH 45458 (United States); Venkatasubramanian, N. [Research Institute, University of Dayton, 300 College Park, Dayton, OH 45469-0168 (United States); Grant, John T. [Research Institute, University of Dayton, 300 College Park, Dayton, OH 45469-0168 (United States); Eyink, Kurt [Air Force Research Laboratory, Materials Directorate, 3005 Hobson Way, Wright-Patterson Air Force Base, OH 45433-7707 (United States); Wiacek, Kevin [Air Force Research Laboratory, Propulsion Directorate, 1950 Fifth Street, Wright-Patterson Air Force Base, OH 45433-7251 (United States); Fries-Carr, Sandra [Air Force Research Laboratory, Propulsion Directorate, 1950 Fifth Street, Wright-Patterson Air Force Base, OH 45433-7251 (United States); Enlow, Jesse [Air Force Research Laboratory, Materials Directorate, 3005 Hobson Way, Wright-Patterson Air Force Base, OH 45433-7707 (United States); Bunning, Timothy J. [Air Force Research Laboratory, Materials Directorate, 3005 Hobson Way, Wright-Patterson Air Force Base, OH 45433-7707 (United States)

2007-02-26

Polymer dielectric films fabricated by plasma enhanced chemical vapor deposition (PECVD) have unique properties due to their dense crosslinked bulk structure. These spatially uniform films exhibit good adhesion to a variety of substrates, excellent chemical inertness, high thermal resistance, and are formed from an inexpensive, solvent-free, room temperature process. In this work, we studied the dielectric properties of plasma polymerized (PP) carbon-based polymer thin films prepared from two precursors, benzene and octafluorocyclobutane. Two different monomer feed locations, directly in the plasma zone or in the downstream region (DS) and two different pressures, 80 Pa (high pressure) or 6.7 Pa (low pressure), were used. The chemical structure of the PECVD films was examined by X-ray photoelectron spectroscopy and Fourier-transform infrared spectroscopy. The dielectric constant ({epsilon} {sub r}) and dielectric loss (tan {delta}) of the films were investigated over a range of frequencies up to 1 MHz and the dielectric strength (breakdown voltage) (F {sub b}) was characterized by the current-voltage method. Spectroscopic ellipsometry was performed to determine the film thickness and refractive index. Good dielectric properties were exhibited, as PP-benzene films formed in the high pressure, DS region showed a F{sub b} of 610 V/{mu}m, an {epsilon} {sub r} of 3.07, and a tan {delta} of 7.0 x 10{sup -3} at 1 kHz. The PECVD processing pressure has a significant effect on final film structure and the film's physical density has a strong impact on dielectric breakdown strength. Also noted was that the residual oxygen content in the PP-benzene films significantly affected the frequency dependences of the dielectric constant and loss.

The relationship between chemical structure and dielectric properties of plasma-enhanced chemical vapor deposited polymer thin films

International Nuclear Information System (INIS)

Jiang Hao; Hong Lianggou; Venkatasubramanian, N.; Grant, John T.; Eyink, Kurt; Wiacek, Kevin; Fries-Carr, Sandra; Enlow, Jesse; Bunning, Timothy J.

2007-01-01

Polymer dielectric films fabricated by plasma enhanced chemical vapor deposition (PECVD) have unique properties due to their dense crosslinked bulk structure. These spatially uniform films exhibit good adhesion to a variety of substrates, excellent chemical inertness, high thermal resistance, and are formed from an inexpensive, solvent-free, room temperature process. In this work, we studied the dielectric properties of plasma polymerized (PP) carbon-based polymer thin films prepared from two precursors, benzene and octafluorocyclobutane. Two different monomer feed locations, directly in the plasma zone or in the downstream region (DS) and two different pressures, 80 Pa (high pressure) or 6.7 Pa (low pressure), were used. The chemical structure of the PECVD films was examined by X-ray photoelectron spectroscopy and Fourier-transform infrared spectroscopy. The dielectric constant (ε r ) and dielectric loss (tan δ) of the films were investigated over a range of frequencies up to 1 MHz and the dielectric strength (breakdown voltage) (F b ) was characterized by the current-voltage method. Spectroscopic ellipsometry was performed to determine the film thickness and refractive index. Good dielectric properties were exhibited, as PP-benzene films formed in the high pressure, DS region showed a F b of 610 V/μm, an ε r of 3.07, and a tan δ of 7.0 x 10 -3 at 1 kHz. The PECVD processing pressure has a significant effect on final film structure and the film's physical density has a strong impact on dielectric breakdown strength. Also noted was that the residual oxygen content in the PP-benzene films significantly affected the frequency dependences of the dielectric constant and loss

Properties of dielectric barrier discharges in different arrangements

International Nuclear Information System (INIS)

Pietsch, G.J.

2001-01-01

Dielectric barrier discharges (DBDs) occur in arrangements where at least one dielectric is positioned in a gas space in between conducting electrodes. When breakdown field strength is reached in such a device, charge carriers are created in the gas region, accelerated, multiplied and finally collected on the surface(s) of the dielectric(s). The charge accumulation on the dielectric creates a counter field to that resulting from the power supply and as all of these processes are rather fast, the discharge quenches rapidly. The dielectric has two tasks, it limits the transferred charge and by this the energy conversion and distributes the discharge over the electrode area. That is why DBDs are non-thermal discharges which exist even at atmospheric pressure

Structural-optical study of high-dielectric-constant oxide films

Energy Technology Data Exchange (ETDEWEB)

Losurdo, M. [Institute of Inorganic Methodologies and Plasmas, IMIP-CNR, Department of Chemistry and INSTM Universita di bari, Via Orabona 4, 70126 Bari (Italy)]. E-mail: maria.losurdo@ba.imip.cnr.it; Giangregorio, M.M. [Institute of Inorganic Methodologies and Plasmas, IMIP-CNR, Department of Chemistry and INSTM Universita di bari, Via Orabona 4, 70126 Bari (Italy); Luchena, M. [Institute of Inorganic Methodologies and Plasmas, IMIP-CNR, Department of Chemistry and INSTM Universita di bari, Via Orabona 4, 70126 Bari (Italy); Capezzuto, P. [Institute of Inorganic Methodologies and Plasmas, IMIP-CNR, Department of Chemistry and INSTM Universita di bari, Via Orabona 4, 70126 Bari (Italy); Bruno, G. [Institute of Inorganic Methodologies and Plasmas, IMIP-CNR, Department of Chemistry and INSTM Universita di bari, Via Orabona 4, 70126 Bari (Italy); Toro, R.G. [Dipartimento di Scienze Chimiche, Universita di Catania, and INSTM-UdR Catania, Viale A. Doria 6, I-95125 Catania (Italy); Malandrino, G. [Dipartimento di Scienze Chimiche, Universita di Catania, and INSTM-UdR Catania, Viale A. Doria 6, I-95125 Catania (Italy); Fragala, I.L. [Dipartimento di Scienze Chimiche, Universita di Catania, and INSTM-UdR Catania, Viale A. Doria 6, I-95125 Catania (Italy); Nigro, R. Lo [Istituto di Microelettronica e Microsistemi, IMM-CNR, Stradale Primosole 50, I-95121 Catania (Italy)

2006-10-31

High-k polycrystalline Pr{sub 2}O{sub 3} and amorphous LaAlO{sub 3} oxide thin films deposited on Si(0 0 1) are studied. The microstructure is investigated using X-ray diffraction and scanning electron microscopy. Optical properties are determined in the 0.75-6.5 eV photon energy range using spectroscopic ellipsometry. The polycrystalline Pr{sub 2}O{sub 3} films have an optical gap of 3.86 eV and a dielectric constant of 16-26, which increases with film thickness. Similarly, very thin amorphous LaAlO{sub 3} films have the optical gap of 5.8 eV, and a dielectric constant below 14 which also increases with film thickness. The lower dielectric constant compared to crystalline material is an intrinsic characteristic of amorphous films.

Properties-Adjustable Alumina-Zirconia Nanolaminate Dielectric Fabricated by Spin-Coating

Directory of Open Access Journals (Sweden)

Junbiao Peng

2017-11-01

Full Text Available In this paper, an alumina-zirconia (Al2O3-ZrO2 nanolaminate dielectric was fabricated by spin-coating and the performance was investigated. It was found that the properties of the dielectric can be adjusted by changing the content of Al2O3/ZrO2 in nanolaminates: when the content of Al2O3 was higher than 50%, the properties of nanolaminates, such as the optical energy gap, dielectric strength (Vds, capacitance density, and relative permittivity were relatively stable, while the change of these properties became larger when the content of Al2O3 was less than 50%. With the content of ZrO2 varying from 50% to 100%, the variation of these properties was up to 0.482 eV, 2.12 MV/cm, 135.35 nF/cm2, and 11.64, respectively. Furthermore, it was demonstrated that the dielectric strength of nanolaminates were influenced significantly by the number (n of bilayers. Every increment of one Al2O3-ZrO2 bilayer will enhance the dielectric strength by around 0.39 MV/cm (Vds ≈ 0.86 + 0.39n. This could be contributed to the amorphous alumina which interrupted the grain boundaries of zirconia.

Interpenetrated polymer networks based on commercial silicone elastomers and ionic networks with high dielectric permittivity and self-healing properties

DEFF Research Database (Denmark)

Ogliani, Elisa; Yu, Liyun; Skov, Anne Ladegaard

the applicability. One method used to avoid this limitation is to increase the dielectric permittivity of the material in order to improve the actuation response at a given field. Recently, interpenetrating polymer networks (IPNs) based on covalently cross-linked commercial silicone elastomers and ionic networks...... from amino- and carboxylic acid- functional silicones have been designed[2] (Figure 1). This novel system provides both the mechanical stability and the high breakdown strength given by the silicone part of the IPNs and the high permittivity and the softening effect of the ionic network. Thus......,1 Hz), and the commercial elastomers RT625 and LR3043/30 provide thebest viscoelastic properties to the systems, since they maintain low viscous losses upon addition of ionic network. The values ofthe breakdown strength in all cases remain higher than that of the reference pure PDMS network (ranging...

Nanocomposites of TiO2/cyanoethylated cellulose with ultra high dielectric constants

International Nuclear Information System (INIS)

Madusanka, Nadeesh; Shivareddy, Sai G; Hiralal, Pritesh; Choi, Youngjin; Amaratunga, Gehan A J; Eddleston, Mark D; Oliver, Rachel A

2016-01-01

A novel dielectric nanocomposite containing a high permittivity polymer, cyanoethylated cellulose (CRS) and TiO 2 nanoparticles was successfully prepared with different weight percentages (10%, 20% and 30%) of TiO 2 . The intermolecular interactions and morphology within the polymer nanocomposites were analysed. TiO 2 /CRS nanofilms on SiO 2 /Si wafers were used to form metal–insulator–metal type capacitors. Capacitances and loss factors in the frequency range of 1 kHz–1 MHz were measured. At 1 kHz CRS-TiO 2 nanocomposites exhibited ultra high dielectric constants of 118, 176 and 207 for nanocomposites with 10%, 20% and 30% weight of TiO 2 respectively, significantly higher than reported values of pure CRS (21), TiO 2 (41) and other dielectric polymer-TiO 2 nanocomposite films. Furthermore, all three CRS-TiO 2 nanocomposites show a loss factor <0.3 at 1 kHz and low leakage current densities (10 −6 –10 −7 A cm −2 ). Leakage was studied using conductive atomic force microscopy and it was observed that the leakage is associated with TiO 2 nanoparticles embedded in the CRS polymer matrix. A new class of ultra high dielectric constant hybrids using nanoscale inorganic dielectrics dispersed in a high permittivity polymer suitable for energy management applications is reported. (paper)

Effects of Interphase Modification and Biaxial Orientation on Dielectric Properties of Poly(ethylene terephthalate)/Poly(vinylidene fluoride-co-hexafluoropropylene) Multilayer Films.

Science.gov (United States)

Yin, Kezhen; Zhou, Zheng; Schuele, Donald E; Wolak, Mason; Zhu, Lei; Baer, Eric

2016-06-01

Recently, poly(vinylidene fluoride) (PVDF)-based multilayer films have demonstrated enhanced dielectric properties, combining high energy density and high dielectric breakdown strength from the component polymers. In this work, further enhanced dielectric properties were achieved through interface/interphase modulation and biaxial orientation for the poly(ethylene terephthalate)/poly(methyl methacrylate)/poly(vinylidene fluoride-co-hexafluoropropylene) [PET/PMMA/P(VDF-HFP)] three-component multilayer films. Because PMMA is miscible with P(VDF-HFP) and compatible with PET, the interfacial adhesion between PET and P(VDF-HFP) layers should be improved. Biaxial stretching of the as-extruded multilayer films induced formation of highly oriented fibrillar crystals in both P(VDF-HFP) and PET, resulting in improved dielectric properties with respect to the unstretched films. First, the parallel orientation of PVDF crystals reduced the dielectric loss from the αc relaxation in α crystals. Second, biaxial stretching constrained the amorphous phase in P(VDF-HFP) and thus the migrational loss from impurity ions was reduced. Third, biaxial stretching induced a significant amount of rigid amorphous phase in PET, further enhancing the breakdown strength of multilayer films. Due to the synergistic effects of improved interfacial adhesion and biaxial orientation, the PET/PMMA/P(VDF-HFP) 65-layer films with 8 vol % PMMA exhibited optimal dielectric properties with an energy density of 17.4 J/cm(3) at breakdown and the lowest dielectric loss. These three-component multilayer films are promising for future high-energy-density film capacitor applications.

High-Efficiency Dielectric Metasurfaces for Polarization-Dependent Terahertz Wavefront Manipulation

KAUST Repository

Zhang, Huifang

2017-11-30

Recently, metasurfaces made up of dielectric structures have drawn enormous attentions in the optical and infrared regimes due to their high efficiency and designing freedom in manipulating light propagation. Such advantages can also be introduced to terahertz frequencies where efficient functional devices are still lacking. Here, polarization-dependent all-silicon terahertz dielectric metasurfaces are proposed and experimentally demonstrated. The metasurfaces are composed of anisotropic rectangular-shaped silicon pillars on silicon substrate. Each metasurface holds dual different functions depending on the incident polarizations. Furthermore, to suppress the reflection loss and multireflection effect in practical applications, a high-performance polarization-independent antireflection silicon pillar array is also proposed, which can be patterned at the other side of the silicon substrate. Such all-silicon dielectric metasurfaces are easy to fabricate and can be very promising in developing next-generation efficient, compact, and low-cost terahertz functional devices.

Exploring the mechanical strength of additively manufactured metal structures with embedded electrical materials

Energy Technology Data Exchange (ETDEWEB)

Li, J., E-mail: J.Li5@lboro.ac.uk; Monaghan, T.; Masurtschak, S.; Bournias-Varotsis, A.; Friel, R.J.; Harris, R.A.

2015-07-15

Ultrasonic Additive Manufacturing (UAM) enables the integration of a wide variety of components into solid metal matrices due to the process induced high degree of metal matrix plastic flow at low bulk temperatures. Exploitation of this phenomenon allows the fabrication of previously unobtainable novel engineered metal matrix components. The feasibility of directly embedding electrical materials within UAM metal matrices was investigated in this work. Three different dielectric materials were embedded into UAM fabricated aluminium metal-matrices with, research derived, optimal processing parameters. The effect of the dielectric material hardness on the final metal matrix mechanical strength after UAM processing was investigated systematically via mechanical peel testing and microscopy. It was found that when the Knoop hardness of the dielectric film was increased from 12.1 HK/0.01 kg to 27.3 HK/0.01 kg, the mechanical peel testing and linear weld density of the bond interface were enhanced by 15% and 16%, respectively, at UAM parameters of 1600 N weld force, 25 µm sonotrode amplitude, and 20 mm/s welding speed. This work uniquely identified that the mechanical strength of dielectric containing UAM metal matrices improved with increasing dielectric material hardness. It was therefore concluded that any UAM metal matrix mechanical strength degradation due to dielectric embedding could be restricted by employing a dielectric material with a suitable hardness (larger than 20 HK/0.01 kg). This result is of great interest and a vital step for realising electronic containing multifunctional smart metal composites for future industrial applications.

High dielectric permittivity elastomers from well-dispersed expanded graphite in low concentrations

DEFF Research Database (Denmark)

Daugaard, Anders Egede; Hassouneh, Suzan Sager; Kostrzewska, Malgorzata

2013-01-01

The development of elastomer materials with a high dielectric permittivity has attracted increased interest over the last years due to their use in for example dielectric electroactive polymers. For this particular use, both the electrically insulating properties - as well as the mechanical...

New theory of effective work functions at metal/high-k dielectric interfaces : application to metal/high-k HfO2 and la2O 3 dielectric interfaces

OpenAIRE

Shiraishi, Kenji; Nakayama, Takashi; Akasaka, Yasushi; Miyazaki, Seiichi; Nakaoka, Takashi; Ohmori, Kenji; Ahmet, Parhat; Torii, Kazuyoshi; Watanabe, Heiji; Chikyow, Toyohiro; Nara, Yasuo; Iwai, Hiroshi; Yamada, Keisaku

2006-01-01

We have constructed a universal theory of the work functions at metal/high-k HfO2 and La2O3 dielectric interfaces by introducing a new concept of generalized charge neutrality levels. Our theory systematically reproduces the experimentally observed work functions of various gate metals on Hf-based high-k dielectrics, including the hitherto unpredictable behaviors of the work functions of p-metals. Our new concept provides effective guiding principles to achieving near-bandedge work functions ...

Dynamics of dielectric barrier discharges in coplanar arrangements

International Nuclear Information System (INIS)

Gibalov, Valentin I; Pietsch, Gerhard J

2004-01-01

The development of a discharge channel in coplanar dielectric barrier arrangements is investigated numerically. Its behaviour in oxygen, like the spatial and temporal distributions of the field strength, charged and neutral particles and energy density, is described in detail. It is found that the streamer development is mainly determined by photoemission. A cathode layer appears near the position where the cathode directed streamer touches the dielectric surface. Secondary electron emission by ion collisions becomes significant and the parameters of the cathode layer are near those of a normal glow discharge. The charge transfer and energy release happen in the conductive channel of the discharge, which appears on the dielectric surface as a result of the cathode streamer development. The field strength in the conductive channel is nearly constant and about 70-100 Td in oxygen and air

On dielectric breakdown statistics

International Nuclear Information System (INIS)

Tuncer, Enis; James, D Randy; Sauers, Isidor; Ellis, Alvin R; Pace, Marshall O

2006-01-01

In this paper, we investigate the dielectric breakdown data of some insulating materials and focus on the applicability of the two- and three-parameter Weibull distributions. A new distribution function is also proposed. In order to assess the model distribution's trustworthiness, we employ the Monte Carlo technique and, randomly selecting data-subsets from the whole dielectric breakdown data, determine whether the selected probability functions accurately describe the breakdown data. The utility and strength of the proposed expression are illustrated distinctly by the numerical procedure. The proposed expression is shown to be a valuable alternative to the Weibull ones

High-Order Dielectric Metasurfaces for High-Efficiency Polarization Beam Splitters and Optical Vortex Generators

Science.gov (United States)

Guo, Zhongyi; Zhu, Lie; Guo, Kai; Shen, Fei; Yin, Zhiping

2017-08-01

In this paper, a high-order dielectric metasurface based on silicon nanobrick array is proposed and investigated. By controlling the length and width of the nanobricks, the metasurfaces could supply two different incremental transmission phases for the X-linear-polarized (XLP) and Y-linear-polarized (YLP) light with extremely high efficiency over 88%. Based on the designed metasurface, two polarization beam splitters working in high-order diffraction modes have been designed successfully, which demonstrated a high transmitted efficiency. In addition, we have also designed two vortex-beam generators working in high-order diffraction modes to create vortex beams with the topological charges of 2 and 3. The employment of dielectric metasurfaces operating in high-order diffraction modes could pave the way for a variety of new ultra-efficient optical devices.

New perovskite-related oxides having high dielectric constant ...

Indian Academy of Sciences (India)

Unknown

static and dynamic random access memories, the static dielectric constant of the material. ¶Dedicated to .... 1100°C. It is also observed from the SEM pictures that the materials are highly dense .... Both these oxides merit attention for their.

High resolution imaging of dielectric surfaces with an evanescent field optical microscope

NARCIS (Netherlands)

van Hulst, N.F.; Segerink, Franciscus B.; Bölger, B.

1992-01-01

An evanescent field optical microscope (EFOM) is presented which employs frustrated total internal reflection o­n a localized scale by scanning a dielectric tip in close proximity to a sample surface. High resolution images of dielectric gratings and spheres containing both topographic and

Influence of Conductive and Semi-Conductive Nanoparticles on the Dielectric Response of Natural Ester-Based Nanofluid Insulation

Directory of Open Access Journals (Sweden)

M. Z. H. Makmud

2018-02-01

Full Text Available Nowadays, studies of alternative liquid insulation in high voltage apparatus have become increasingly important due to higher concerns regarding safety, sustainable resources and environmentally friendly issues. To fulfil this demand, natural ester has been extensively studied and it can become a potential product to replace mineral oil in power transformers. In addition, the incorporation of nanoparticles has been remarkable in producing improved characteristics of insulating oil. Although much extensive research has been carried out, there is no general agreement on the influence on the dielectric response of base oil due to the addition of different amounts and conductivity types of nanoparticle concentrations. Therefore, in this work, a natural ester-based nanofluid was prepared by a two-step method using iron oxide (Fe2O3 and titanium dioxide (TiO2 as the conductive and semi-conductive nanoparticles, respectively. The concentration amount of each nanoparticle types was varied at 0.01, 0.1 and 1.0 g/L. The nanofluid samples were characterised by visual inspection, morphology and the dynamic light scattering (DLS method before the dielectric response measurement was carried out for frequency-dependent spectroscopy (FDS, current-voltage (I-V, and dielectric breakdown (BD strength. The results show that the dielectric spectra and I-V curves of nanofluid-based iron oxide increases with the increase of iron oxide nanoparticle loading, while for titanium dioxide, it exhibits a decreasing response. The dielectric BD strength is enhanced for both types of nanoparticles at 0.01 g/L concentration. However, the increasing amount of nanoparticles at 0.1 and 1.0 g/L led to a contrary dielectric BD response. Thus, the results indicate that the augmentation of conductive nanoparticles in the suspension can lead to overlapping mechanisms. Consequently, this reduces the BD strength compared to pristine materials during electron injection in high electric

Evolutionary search for new high-k dielectric materials: methodology and applications to hafnia-based oxides.

Science.gov (United States)

Zeng, Qingfeng; Oganov, Artem R; Lyakhov, Andriy O; Xie, Congwei; Zhang, Xiaodong; Zhang, Jin; Zhu, Qiang; Wei, Bingqing; Grigorenko, Ilya; Zhang, Litong; Cheng, Laifei

2014-02-01

High-k dielectric materials are important as gate oxides in microelectronics and as potential dielectrics for capacitors. In order to enable computational discovery of novel high-k dielectric materials, we propose a fitness model (energy storage density) that includes the dielectric constant, bandgap, and intrinsic breakdown field. This model, used as a fitness function in conjunction with first-principles calculations and the global optimization evolutionary algorithm USPEX, efficiently leads to practically important results. We found a number of high-fitness structures of SiO2 and HfO2, some of which correspond to known phases and some of which are new. The results allow us to propose characteristics (genes) common to high-fitness structures--these are the coordination polyhedra and their degree of distortion. Our variable-composition searches in the HfO2-SiO2 system uncovered several high-fitness states. This hybrid algorithm opens up a new avenue for discovering novel high-k dielectrics with both fixed and variable compositions, and will speed up the process of materials discovery.

Influence of the Category Discharge Processing on Strength Properties of Piezocomposites

International Nuclear Information System (INIS)

Ramazanov, M. A.

2006-01-01

Piezoelectric, dielectric and physicomechanical properties of polymeric piezocomposites on piezoceramics basis are one of the major operational devices of applications. During their application in various devices for a long time can be exposed to various influences for a long time. Piezoelectric, dielectric and strength properties of polymeric piezocomposites strongly depend from the interphase phenomena, and also on charges saved up on border of the unit between components of a composition. Therefore creation the preliminary centers localization for charges in a composition is an actual problem for development effective polymeric piezocomposites. In the given work results of a research preliminary discharge processing's of powders of polymer on strength properties and dielectric characteristics of polymeric compositions on a basis polyvinilidenftorid (PVDF), high density polyethylene and piezoceramic from tetragonal structure are poisoned. Piezoceramic had structure plumbum-zirconate-titanate (PZT). Powders of polymer have been subjected to discharge processing in a quartz glass tube with a diameter 15 mm which walls with 1 mm. It is earthed, from one end and to other end it is connected with high-voltage electrode. Compositions in a volumetric ratio of 90+10 % have been obtained at temperature 435Κ under pressure 15ΜΠa. After creation reception of samples they were exposed electrothermopolarization. It is experimentally established, that after discharge processing powders of polymer depending on of processing duration electric and mechanical durability, and also an accrued charge on border of the unit of phases up to the certain value increases, and then decreases. Also it is shown, hat influence of category processing on strength and dielectric characteristics of a composition on the basis of polymer PVDF is more than , has on polyethylene basis. Changes piezoelectric, dielectric it is supposed, that, and strength properties to an extreme piezocomposite

High Stability Pentacene Transistors Using Polymeric Dielectric Surface Modifier.

Science.gov (United States)

Wang, Xiaohong; Lin, Guangqing; Li, Peng; Lv, Guoqiang; Qiu, Longzhen; Ding, Yunsheng

2015-08-01

1,6-bis(trichlorosilyl)hexane (C6Cl), polystyrene (PS), and cross-linked polystyrene (CPS) were investigated as gate dielectric modified layers for high performance organic transistors. The influence of the surface energy, roughness and morphology on the charge transport of the organic thin-film transistors (OTFTs) was investigated. The surface energy and roughness both affect the grain size of the pentacene films which will control the charge carrier mobility of the devices. Pentacene thin-film transistors fabricated on the CPS modified dielectric layers exhibited charge carrier mobility as high as 1.11 cm2 V-1 s-1. The bias stress stability for the CPS devices shows that the drain current only decays 1% after 1530 s and the mobility never decreases until 13530 s.

High temperature measurements of the microwave dielectric properties of ceramics

International Nuclear Information System (INIS)

Baeraky, T.A.

1999-06-01

Equipment has been developed for the measurement of dielectric properties at high temperature from 25 to 1700 deg. C in the microwave frequency range 614.97 to 3620.66 MHz using the cavity perturbation technique, to measure the permittivity of a range of ceramic materials. The complex permittivities of the standard materials, water and methanol, were measured at low temperature and compared with the other published data. A statistical analysis was made for the permittivity measurements of water and methanol using sample holders of different diameter. Also the measurements of these materials were used to compare the simple perturbation equation with its modifications and alternation correction methods for sample shape and the holes at the two endplates of the cavity. The dielectric properties of solid materials were investigated from the permittivity measurements on powder materials, shown in table 4.7, using the dielectric mixture equations. Two kinds of ceramics, oxide and nitrides, were selected for the high temperature dielectric measurements in microwave frequency ranges. Pure zirconia, yttria-stabilised zirconia, and Magnesia-stabilised zirconia are the oxide ceramics while aluminium nitride and silicon nitride are the nitride ceramics. A phase transformation from monoclinic to tetragonal was observed in pure zirconia in terms of the complex permittivity measurements, and the conduction mechanism in three regions of temperature was suggested to be ionic in the first region and a mixture of ionic and electronic in the second. The phase transition disappeared with yttria-stabilised zirconia but it was observed with magnesia-stabilised zirconia. Yttria doped zirconia was fully stabilised while magnesia stabilised was partially stabilised zirconia. The dielectric property measurements of aluminium nitride indicated that there is a transition from AIN to AlON, which suggested that the external layer of the AIN which was exposed to the air, contains alumina. It was

Significantly Elevated Dielectric and Energy Storage Traits in Boron Nitride Filled Polymer Nano-composites with Topological Structure

Science.gov (United States)

Feng, Yefeng; Zhang, Jianxiong; Hu, Jianbing; Li, Shichun; Peng, Cheng

2018-03-01

Interface induced polarization has a prominent influence on dielectric properties of 0-3 type polymer based composites containing Si-based semi-conductors. The disadvantages of composites were higher dielectric loss, lower breakdown strength and energy storage density, although higher permittivity was achieved. In this work, dielectric, conductive, breakdown and energy storage properties of four nano-composites have been researched. Based on the cooperation of fluoropolymer/alpha-SiC layer and fluoropolymer/hexagonal-BN layer, it was confirmed constructing the heterogeneous layer-by-layer composite structure rather than homogeneous mono-layer structure could significantly reduce dielectric loss, promote breakdown strength and increase energy storage density. The former worked for a larger dielectric response and the latter layer acted as a robust barrier of charge carrier transfer. The best nano-composite could possess a permittivity of 43@100 Hz ( 3.3 times of polymer), loss of 0.07@100 Hz ( 37% of polymer), discharged energy density of 2.23 J/cm3@249 kV/cm ( 10 times of polymer) and discharged energy efficiency of 54%@249 kV/cm ( 5 times of polymer). This work might enlighten a facile route to achieve the promising high energy storage composite dielectrics by constructing the layer-by-layer topological structure.

Soft Functional Silicone Elastomers with High Dielectric Permittivty: Simple Additives vs. Cross-Linked Synthesized Copolymers

DEFF Research Database (Denmark)

Madsen, Frederikke Bahrt; Yu, Liyun; Skov, Anne Ladegaard

Though dielectric elastomers (DEs) have many favorable properties, the issue of high driving voltages limits the commercial viability of the technology. Improved actuation at lower voltages can be obtained by decreasing the Young’s modulus and/or decreasing the dielectric permittivity of the elas......Though dielectric elastomers (DEs) have many favorable properties, the issue of high driving voltages limits the commercial viability of the technology. Improved actuation at lower voltages can be obtained by decreasing the Young’s modulus and/or decreasing the dielectric permittivity...... of the elastomer. A decrease in Young’s modulus, however, is often accompanied by the loss of mechanical stability and thereby the lifetime of the DE whereas addition of high permittivity fillers such as metal oxides often increases Young’s modulus such that improved actuation is not accomplished. New soft...... silicone elastomers with high dielectric permittivity were prepared through the use of chloropropyl-functional silicones. One method was through the synthesis of modular cross-linkable chloropropyl-functional copolymers that allow for a high degree of chemical freedom such that a tuneable silicone...

A dielectric approach to high temperature superconductivity

International Nuclear Information System (INIS)

Mahanty, J.; Das, M.P.

1989-01-01

The dielectric response of an electron-ion system to the presence of a pair of charges is investigated. From the nature of the dielectric function, it is shown that a strong attractive pair formation is possible depending on the dispersion of the ion branches. The latter brings a reduction to the sound velocity which is used as a criterion for the superconductivity. By solving the BCS equation with the above dielectric function, we obtain a reasonable value of T/sub c/. 17 refs., 1 fig

A simple solution for reducing artefacts due to conductive and dielectric effects in clinical magnetic resonance imaging at 3 T

International Nuclear Information System (INIS)

Sreenivas, M.; Lowry, M.; Gibbs, P.; Pickles, M.; Turnbull, L.W.

2007-01-01

The quality of imaging obtained at high magnetic field strengths can be degraded by various artefacts due to conductive and dielectric effects, which leads to loss of signal. Various methods have been described and used to improve the quality of the image affected by such artefacts. In this article, we describe the construction and use of a simple solution that can be used to diminish artefacts due to conductive and dielectric effects in clinical imaging at 3 T field strength and thereby improve the diagnostic quality of the images obtained

A simple solution for reducing artefacts due to conductive and dielectric effects in clinical magnetic resonance imaging at 3 T

Energy Technology Data Exchange (ETDEWEB)

Sreenivas, M. [Department of Radiology (Yorkshire Deanery-East), Hull Royal Infirmary, Anlaby Road, Hull HU3 2JZ (United Kingdom)]. E-mail: aprilsreenivas@hotmail.com; Lowry, M. [Centre for Magnetic Resonance Investigations, University of Hull, Hull Royal Infirmary, Anlaby Road, 1PR, Hull HU3 2JZ (United Kingdom); Gibbs, P. [Centre for Magnetic Resonance Investigations, University of Hull, Hull Royal Infirmary, Anlaby Road, 1PR, Hull HU3 2JZ (United Kingdom); Pickles, M. [Centre for Magnetic Resonance Investigations, University of Hull, Hull Royal Infirmary, Anlaby Road, 1PR, Hull HU3 2JZ (United Kingdom); Turnbull, L.W. [Centre for Magnetic Resonance Investigations, University of Hull, Hull Royal Infirmary, Anlaby Road, 1PR, Hull HU3 2JZ (United Kingdom)

2007-04-15

The quality of imaging obtained at high magnetic field strengths can be degraded by various artefacts due to conductive and dielectric effects, which leads to loss of signal. Various methods have been described and used to improve the quality of the image affected by such artefacts. In this article, we describe the construction and use of a simple solution that can be used to diminish artefacts due to conductive and dielectric effects in clinical imaging at 3 T field strength and thereby improve the diagnostic quality of the images obtained.

A new soft dielectric silicone elastomer matrix with high mechanical integrity and low losses

DEFF Research Database (Denmark)

Madsen, Frederikke Bahrt; Yu, Liyun; Daugaard, Anders Egede

2015-01-01

Though dielectric elastomers (DEs) have many favourable properties, the issue of high driving voltages limits the commercial viability of the technology. Driving voltage can be lowered by decreasing the Young's modulus and increasing the dielectric permittivity of silicone elastomers. A decrease...... in Young's modulus, however, is often accompanied by the loss of mechanical stability and thereby the lifetime of the DE. A new soft elastomer matrix, with no loss of mechanical stability and high dielectric permittivity, was prepared through the use of alkyl chloride-functional siloxane copolymers...

Enhanced Energy-Storage Density and High Efficiency of Lead-Free CaTiO3-BiScO3 Linear Dielectric Ceramics.

Science.gov (United States)

Luo, Bingcheng; Wang, Xiaohui; Tian, Enke; Song, Hongzhou; Wang, Hongxian; Li, Longtu

2017-06-14

A novel lead-free (1 - x)CaTiO 3 -xBiScO 3 linear dielectric ceramic with enhanced energy-storage density was fabricated. With the composition of BiScO 3 increasing, the dielectric constant of (1 - x)CaTiO 3 -xBiScO 3 ceramics first increased and then decreased after the composition x > 0.1, while the dielectric loss decreased first and increased. For the composition x = 0.1, the polarization was increased into 12.36 μC/cm 2 , 4.6 times higher than that of the pure CaTiO 3 . The energy density of 0.9CaTiO 3 -0.1BiScO 3 ceramic was 1.55 J/cm 3 with the energy-storage efficiency of 90.4% at the breakdown strength of 270 kV/cm, and the power density was 1.79 MW/cm 3 . Comparison with other lead-free dielectric ceramics confirmed the superior potential of CaTiO 3 -BiScO 3 ceramics for the design of ceramics capacitors for energy-storage applications. First-principles calculations revealed that Sc subsitution of Ti-site induced the atomic displacement of Ti ions in the whole crystal lattice, and lattice expansion was caused by variation of the bond angles and lenghths. Strong hybridization between O 2p and Ti 3d was observed in both valence band and conduction band; the hybridization between O 2p and Sc 3d at high conduction band was found to enlarge the band gap, and the static dielectric tensors were increased, which was the essential for the enhancement of polarization and dielectric properties.

Comparison of Thermal Stability of Dry High-strength Concrete and Wet High-strength Concrete

Science.gov (United States)

Musorina, Tatiana; Katcay, Aleksandr; Selezneva, Anna; Kamskov, Victor

2018-03-01

High-strength concrete is a modern material, which occupies it`s own niche on the construction material market. It is applicable in a large-scale high-rise construction, particularly an underground construction is a frequently used solution for a space saving. Usually underground structure is related to a wet usage environment. Though not all properties of the high-strength concrete are investigated to the full extent. Under adverse climatic conditions of the Russian Federation one of the most important properties for constructional materials is a thermal capacity. Therefore, the main purpose of the paper is to compare a thermal capacity of the high-strength concrete in humid conditions and a thermal capacity of the high-strength concrete in dry operational condition. During the study dependency between thermal capacity and design wall thickness and ambient humidity has to be proven with two experiments. As a result the theoretical relation between thermal capacity characteristic - thermal inertia and wall thickness and ambient humidity was confirmed by the experimental data. The thermal capacity of a building is in direct ratio to the construction thickness. It follows from the experiments and calculations that wet high-strength concrete has less thermal stability.

Compressive Strength of Cometary Surfaces Derived from Radar Observations

Science.gov (United States)

ElShafie, A.; Heggy, E.

2014-12-01

Landing on a comet nucleus and probing it, mechanically using harpoons, penetrometers and drills, and electromagnetically using low frequency radar waves is a complex task that will be tackled by the Rosetta mission for Comet 67P/Churyumov-Gerasimenko. The mechanical properties (i.e. density, porosity and compressive strength) and the electrical properties (i.e. the real and imaginary parts of the dielectric constant) of the comet nucleus, constrain both the mechanical and electromagnetic probing capabilities of Rosetta, as well as the choice of landing site, the safety of the landing, and subsurface data interpretation. During landing, the sounding radar data that will be collected by Rosetta's CONSERT experiment can be used to probe the comet's upper regolith layer by assessing its dielectric properties, which are then inverted to retrieve the surface mechanical properties. These observations can help characterize the mechanical properties of the landing site, which will optimize the operation of the anchor system. In this effort, we correlate the mechanical and electrical properties of cometary analogs to each other, and derive an empirical model that can be used to retrieve density, porosity and compressive strength from the dielectric properties of the upper regolith inverted from CONSERT observations during the landing phase. In our approach we consider snow as a viable cometary material analog due to its low density and its porous nature. Therefore, we used the compressive strength and dielectric constant measurements conducted on snow at a temperature of 250 K and a density range of 0.4-0.9 g/cm3 in order to investigate the relation between compressive strength and dielectric constant under cometary-relevant density range. Our results suggest that compressive strength increases linearly as function of the dielectric constant over the observed density range mentioned above. The minimum and maximum compressive strength of 0.5 and 4.5 MPa corresponded to a

Performance of dielectric nanocomposites: matrix-free, hairy nanoparticle assemblies and amorphous polymer-nanoparticle blends.

Science.gov (United States)

Grabowski, Christopher A; Koerner, Hilmar; Meth, Jeffrey S; Dang, Alei; Hui, Chin Ming; Matyjaszewski, Krzysztof; Bockstaller, Michael R; Durstock, Michael F; Vaia, Richard A

2014-12-10

Demands to increase the stored energy density of electrostatic capacitors have spurred the development of materials with enhanced dielectric breakdown, improved permittivity, and reduced dielectric loss. Polymer nanocomposites (PNCs), consisting of a blend of amorphous polymer and dielectric nanofillers, have been studied intensely to satisfy these goals; however, nanoparticle aggregates, field localization due to dielectric mismatch between particle and matrix, and the poorly understood role of interface compatibilization have challenged progress. To expand the understanding of the inter-relation between these factors and, thus, enable rational optimization of low and high contrast PNC dielectrics, we compare the dielectric performance of matrix-free hairy nanoparticle assemblies (aHNPs) to blended PNCs in the regime of low dielectric contrast to establish how morphology and interface impact energy storage and breakdown across different polymer matrices (polystyrene, PS, and poly(methyl methacrylate), PMMA) and nanoparticle loadings (0-50% (v/v) silica). The findings indicate that the route (aHNP versus blending) to well-dispersed morphology has, at most, a minor impact on breakdown strength trends with nanoparticle volume fraction; the only exception being at intermediate loadings of silica in PMMA (15% (v/v)). Conversely, aHNPs show substantial improvements in reducing dielectric loss and maintaining charge/discharge efficiency. For example, low-frequency dielectric loss (1 Hz-1 kHz) of PS and PMMA aHNP films was essentially unchanged up to a silica content of 50% (v/v), whereas traditional blends showed a monotonically increasing loss with silica loading. Similar benefits are seen via high-field polarization loop measurements where energy storage for ∼15% (v/v) silica loaded PMMA and PS aHNPs were 50% and 200% greater than respective comparable PNC blends. Overall, these findings on low dielectric contrast PNCs clearly point to the performance benefits of

Equipment and Protocols for Quasi-Static and Dynamic Tests of Very-High-Strength Concrete (VHSC) and High-Strength High-Ductility Concrete (HSHDC)

Science.gov (United States)

2016-08-01

Concrete (VHSC) and High-Strength High-Ductility Concrete (HSHDC) En gi ne er R es ea rc h an d D ev el op m en t Ce nt er Brett A...Very-High-Strength Concrete (VHSC) and High-Strength High-Ductility Concrete (HSHDC) Brett A. Williams, Robert D. Moser, William F. Heard, Carol F...equipment and protocols for tests of both very-high-strength concrete (VHSC) and high- strength high-ductility concrete (HSHDC) to predict blast

Low-Temperature Solution-Processed Gate Dielectrics for High-Performance Organic Thin Film Transistors

Directory of Open Access Journals (Sweden)

Jaekyun Kim

2015-10-01

Full Text Available A low-temperature solution-processed high-k gate dielectric layer for use in a high-performance solution-processed semiconducting polymer organic thin-film transistor (OTFT was demonstrated. Photochemical activation of sol-gel-derived AlOx films under 150 °C permitted the formation of a dense film with low leakage and relatively high dielectric-permittivity characteristics, which are almost comparable to the results yielded by the conventionally used vacuum deposition and high temperature annealing method. Octadecylphosphonic acid (ODPA self-assembled monolayer (SAM treatment of the AlOx was employed in order to realize high-performance (>0.4 cm2/Vs saturation mobility and low-operation-voltage (<5 V diketopyrrolopyrrole (DPP-based OTFTs on an ultra-thin polyimide film (3-μm thick. Thus, low-temperature photochemically-annealed solution-processed AlOx film with SAM layer is an attractive candidate as a dielectric-layer for use in high-performance organic TFTs operated at low voltages.

Dielectric constant of ionic solutions: a field-theory approach.

Science.gov (United States)

Levy, Amir; Andelman, David; Orland, Henri

2012-06-01

We study the variation of the dielectric response of a dielectric liquid (e.g. water) when a salt is added to the solution. Employing field-theoretical methods, we expand the Gibbs free energy to first order in a loop expansion and calculate self-consistently the dielectric constant. We predict analytically the dielectric decrement which depends on the ionic strength in a complex way. Furthermore, a qualitative description of the hydration shell is found and is characterized by a single length scale. Our prediction fits rather well a large range of concentrations for different salts using only one fit parameter related to the size of ions and dipoles.

High strength alloys

Science.gov (United States)

Maziasz, Phillip James [Oak Ridge, TN; Shingledecker, John Paul [Knoxville, TN; Santella, Michael Leonard [Knoxville, TN; Schneibel, Joachim Hugo [Knoxville, TN; Sikka, Vinod Kumar [Oak Ridge, TN; Vinegar, Harold J [Bellaire, TX; John, Randy Carl [Houston, TX; Kim, Dong Sub [Sugar Land, TX

2010-08-31

High strength metal alloys are described herein. At least one composition of a metal alloy includes chromium, nickel, copper, manganese, silicon, niobium, tungsten and iron. System, methods, and heaters that include the high strength metal alloys are described herein. At least one heater system may include a canister at least partially made from material containing at least one of the metal alloys. At least one system for heating a subterranean formation may include a tubular that is at least partially made from a material containing at least one of the metal alloys.

High performance solution processed zirconium oxide gate dielectric appropriate for low temperature device application

Energy Technology Data Exchange (ETDEWEB)

Hasan, Musarrat; Nguyen, Manh-Cuong; Kim, Hyojin; You, Seung-Won; Jeon, Yoon-Seok; Tong, Duc-Tai; Lee, Dong-Hwi; Jeong, Jae Kyeong; Choi, Rino, E-mail: rino.choi@inha.ac.kr

2015-08-31

This paper reports a solution processed electrical device with zirconium oxide gate dielectric that was fabricated at a low enough temperature appropriate for flexible electronics. Both inorganic dielectric and channel materials were synthesized in the same organic solvent. The dielectric constant achieved was 13 at 250 °C with a reasonably low leakage current. The bottom gate transistor devices showed the highest mobility of 75 cm{sup 2}/V s. The device is operated at low voltage with high-k dielectric with excellent transconductance and low threshold voltage. Overall, the results highlight the potential of low temperature solution based deposition in fabricating more complicated circuits for a range of applications. - Highlights: • We develop a low temperature inorganic dielectric deposition process. • We fabricate oxide semiconductor channel devices using all-solution processes. • Same solvent is used for dielectric and oxide semiconductor deposition.

Characterization of dielectric properties of nanocellulose from wood and algae for electrical insulator applications.

Science.gov (United States)

Le Bras, David; Strømme, Maria; Mihranyan, Albert

2015-05-07

Cellulose is one of the oldest electrically insulating materials used in oil-filled high-power transformers and cables. However, reports on the dielectric properties of nanocellulose for electrical insulator applications are scarce. The aim of this study was to characterize the dielectric properties of two nanocellulose types from wood, viz., nanofibrillated cellulose (NFC), and algae, viz., Cladophora cellulose, for electrical insulator applications. The cellulose materials were characterized with X-ray diffraction, nitrogen gas and moisture sorption isotherms, helium pycnometry, mechanical testing, and dielectric spectroscopy at various relative humidities. The algae nanocellulose sample was more crystalline and had a lower moisture sorption capacity at low and moderate relative humidities, compared to NFC. On the other hand, it was much more porous, which resulted in lower strength and higher dielectric loss than for NFC. It is concluded that the solid-state properties of nanocellulose may have a substantial impact on the dielectric properties of electrical insulator applications.

Thermal, mechanical and dielectric properties of poly(vinyl alcohol)/graphene oxide composites

Science.gov (United States)

Rathod, Sunil G.; Bhajantri, R. F.; Ravindrachary, V.; Pujari, P. K.; Sheela, T.; Naik, Jagadish

2014-04-01

In this work the composite films of poly(vinyl alcohol) (PVA) doped with functionalized Graphene Oxide (GO) were prepared by solution casting method. The films were characterized using FT-IR, DSC, XRD, mechanical properties and dielectric studies at room temperature. FTIR spectra shows the formation of hydrogen bonds between hydroxyl groups of PVA and the hydroxy groups of GO. The DSC thermograms shows the addition of GO to PVA greatly improves the thermal stability of the composites. XRD patterns shows that the GO exfoliated and uniformly dispersed in PVA matrix. Mechanical properties are significantly improved in PVA/GO composites. The tensile strength increased from 8.2 to 13.7 MPa and the Young's modulus increased from 7.5 to 24.8 MPa for 5 wt% GO doped sample. Dielectric spectroscopy showed a highest dielectric constant for the 5 wt% GO doped PVA films. This work provides a potential design strategy on PVA/GO composite, which would lead to higher-performance, flexible dielectric materials, high charge-storage devices.

Interface Engineering and Gate Dielectric Engineering for High Performance Ge MOSFETs

Directory of Open Access Journals (Sweden)

Jiabao Sun

2015-01-01

Full Text Available In recent years, germanium has attracted intensive interests for its promising applications in the microelectronics industry. However, to achieve high performance Ge channel devices, several critical issues still have to be addressed. Amongst them, a high quality gate stack, that is, a low defect interface layer and a dielectric layer, is of crucial importance. In this work, we first review the existing methods of interface engineering and gate dielectric engineering and then in more detail we discuss and compare three promising approaches (i.e., plasma postoxidation, high pressure oxidation, and ozone postoxidation. It has been confirmed that these approaches all can significantly improve the overall performance of the metal-oxide-semiconductor field effect transistor (MOSFET device.

Investigation of High-k Dielectrics and Metal Gate Electrodes for Non-volatile Memory Applications

Science.gov (United States)

Jayanti, Srikant

Due to the increasing demand of non-volatile flash memories in the portable electronics, the device structures need to be scaled down drastically. However, the scalability of traditional floating gate structures beyond 20 nm NAND flash technology node is uncertain. In this regard, the use of metal gates and high-k dielectrics as the gate and interpoly dielectrics respectively, seem to be promising substitutes in order to continue the flash scaling beyond 20nm. Furthermore, research of novel memory structures to overcome the scaling challenges need to be explored. Through this work, the use of high-k dielectrics as IPDs in a memory structure has been studied. For this purpose, IPD process optimization and barrier engineering were explored to determine and improve the memory performance. Specifically, the concept of high-k / low-k barrier engineering was studied in corroboration with simulations. In addition, a novel memory structure comprising a continuous metal floating gate was investigated in combination with high-k blocking oxides. Integration of thin metal FGs and high-k dielectrics into a dual floating gate memory structure to result in both volatile and non-volatile modes of operation has been demonstrated, for plausible application in future unified memory architectures. The electrical characterization was performed on simple MIS/MIM and memory capacitors, fabricated through CMOS compatible processes. Various analytical characterization techniques were done to gain more insight into the material behavior of the layers in the device structure. In the first part of this study, interfacial engineering was investigated by exploring La2O3 as SiO2 scavenging layer. Through the silicate formation, the consumption of low-k SiO2 was controlled and resulted in a significant improvement in dielectric leakage. The performance improvement was also gauged through memory capacitors. In the second part of the study, a novel memory structure consisting of continuous metal FG

Enhancing electrical energy storage capability of dielectric polymer nanocomposites via the room temperature Coulomb blockade effect of ultra-small platinum nanoparticles.

Science.gov (United States)

Wang, Liwei; Huang, Xingyi; Zhu, Yingke; Jiang, Pingkai

2018-02-14

Introducing a high dielectric constant (high-k) nanofiller into a dielectric polymer is the most common way to achieve flexible nanocomposites for electrostatic energy storage devices. However, the significant decrease of breakdown strength and large increase of dielectric loss has long been known as the bottleneck restricting the enhancement of practical energy storage capability of the nanocomposites. In this study, by introducing ultra-small platinum (energy density of the Pt@PDA@BT nanocomposites is increased by nearly 70% because of the improved energy storage efficiency. This research provides a simple, promising and unique way to enhance energy storage capability of high-k polymer nanocomposites.

Enhanced performance in capacitive force sensors using carbon nanotube/polydimethylsiloxane nanocomposites with high dielectric properties

Science.gov (United States)

Jang, Hyeyoung; Yoon, Hyungsuk; Ko, Youngpyo; Choi, Jaeyoo; Lee, Sang-Soo; Jeon, Insu; Kim, Jong-Ho; Kim, Heesuk

2016-03-01

Force sensors have attracted tremendous attention owing to their applications in various fields such as touch screens, robots, smart scales, and wearable devices. The force sensors reported so far have been mainly focused on high sensitivity based on delicate microstructured materials, resulting in low reproducibility and high fabrication cost that are limitations for wide applications. As an alternative, we demonstrate a novel capacitive-type force sensor with enhanced performance owing to the increased dielectric properties of elastomers and simple sensor structure. We rationally design dielectric elastomers based on alkylamine modified-multi-walled carbon nanotube (MWCNT)/polydimethylsiloxane (PDMS) composites, which have a higher dielectric constant than pure PDMS. The alkylamine-MWCNTs show excellent dispersion in a PDMS matrix, thus leading to enhanced and reliable dielectric properties of the composites. A force sensor array fabricated with alkylamine-MWCNT/PDMS composites presents an enhanced response due to the higher dielectric constant of the composites than that of pure PDMS. This study is the first to report enhanced performance of capacitive force sensors by modulating the dielectric properties of elastomers. We believe that the disclosed strategy to improve the sensor performance by increasing the dielectric properties of elastomers has great potential in the development of capacitive force sensor arrays that respond to various input forces.Force sensors have attracted tremendous attention owing to their applications in various fields such as touch screens, robots, smart scales, and wearable devices. The force sensors reported so far have been mainly focused on high sensitivity based on delicate microstructured materials, resulting in low reproducibility and high fabrication cost that are limitations for wide applications. As an alternative, we demonstrate a novel capacitive-type force sensor with enhanced performance owing to the increased

High Dielectric Performance of Solution-Processed Aluminum Oxide-Boron Nitride Composite Films

Science.gov (United States)

Yu, Byoung-Soo; Ha, Tae-Jun

2018-04-01

The material compositions of oxide films have been extensively investigated in an effort to improve the electrical characteristics of dielectrics which have been utilized in various electronic devices such as field-effect transistors, and storage capacitors. Significantly, solution-based compositions have attracted considerable attention as a highly effective and practical technique to replace vacuum-based process in large-area. Here, we demonstrate solution-processed composite films consisting of aluminum oxide (Al2O3) and boron nitride (BN), which exhibit remarkable dielectric properties through the optimization process. The leakage current of the optimized Al2O3-BN thin films was decreased by a factor of 100 at 3V, compared to pristine Al2O3 thin film without a loss of the dielectric constant or degradation of the morphological roughness. The characterization by X-ray photoelectron spectroscopy measurements revealed that the incorporation of BN with an optimized concentration into the Al2O3 dielectric film reduced the density of oxygen vacancies which act as defect states, thereby improving the dielectric characteristics.

Dielectric and acoustical high frequency characterisation of PZT thin films

International Nuclear Information System (INIS)

Conde, Janine; Muralt, Paul

2010-01-01

Pb(Zr, Ti)O 3 (PZT) is an interesting material for bulk acoustic wave resonator applications due to its high electromechanical coupling constant, which would enable fabrication of large bandwidth frequency filters. The major challenge of the PZT solid solution system is to overcome mechanical losses generally observed in PZT ceramics. To increase the understanding of these losses in textured thin films, thin film bulk acoustic resonators (TFBAR's) based on PZT thin films with compositions either in the tetragonal region or at the morphotropic phase boundary and (111) or {100} textures were fabricated and studied up to 2 GHz. The dielectric and elastic materials coefficients were extracted from impedance measurements at the resonance frequency. The dispersion of the dielectric constant was obtained from impedance measurements up to 2 GHz. The films with varying compositions, textures and deposition methods (sol-gel or sputtering) were compared in terms of dielectric and acoustical properties.

Dielectric and acoustical high frequency characterisation of PZT thin films

Science.gov (United States)

Conde, Janine; Muralt, Paul

2010-02-01

Pb(Zr, Ti)O3 (PZT) is an interesting material for bulk acoustic wave resonator applications due to its high electromechanical coupling constant, which would enable fabrication of large bandwidth frequency filters. The major challenge of the PZT solid solution system is to overcome mechanical losses generally observed in PZT ceramics. To increase the understanding of these losses in textured thin films, thin film bulk acoustic resonators (TFBAR's) based on PZT thin films with compositions either in the tetragonal region or at the morphotropic phase boundary and (111) or {100} textures were fabricated and studied up to 2 GHz. The dielectric and elastic materials coefficients were extracted from impedance measurements at the resonance frequency. The dispersion of the dielectric constant was obtained from impedance measurements up to 2 GHz. The films with varying compositions, textures and deposition methods (sol-gel or sputtering) were compared in terms of dielectric and acoustical properties.

Do dielectric nanostructures turn metallic in high-electric dc fields?

Science.gov (United States)

Silaeva, E P; Arnoldi, L; Karahka, M L; Deconihout, B; Menand, A; Kreuzer, H J; Vella, A

2014-11-12

Three-dimensional dielectric nanostructures have been analyzed using field ion microscopy (FIM) to study the electric dc field penetration inside these structures. The field is proved to be screened within a few nanometers as theoretically calculated taking into account the high-field impact ionization process. Moreover, the strong dc field of the order of 0.1 V/Å at the surface inside a dielectric nanostructure modifies its band structure leading to a strong band gap shrinkage and thus to a strong metal-like optical absorption near the surface. This metal-like behavior was theoretically predicted using first-principle calculations and experimentally proved using laser-assisted atom probe tomography (APT). This work opens up interesting perspectives for the study of the performance of all field-effect nanodevices, such as nanotransistor or super capacitor, and for the understanding of the physical mechanisms of field evaporation of dielectric nanotips in APT.

Conductivity, dielectric behavior and FTIR studies of high molecular weight poly(vinylchloride)-lithium triflate polymer electrolytes

International Nuclear Information System (INIS)

Ramesh, S.; Chai, M.F.

2007-01-01

Thin films of high molecular weight polyvinyl chloride (PVC) with lithium triflate (LiCF 3 SO 3 ) salt were prepared by solution casting method. The ionic conductivity and dielectric measurements were carried out on these films over a wide frequency regime at various temperatures. The conductivity-temperature plots were found to obey classical Arrhenius relationship. The dielectric behavior was analysed using dielectric permittivity and dielectric modulus of the samples. FTIR studies show some simple overlapping and shift in peaks between high molecular weight polyvinyl chloride (PVC) with lithium triflate (LiCF 3 SO 3 ) salt in the polymer electrolyte complexes

Lattices of dielectric resonators

CERN Document Server

Trubin, Alexander

2016-01-01

This book provides the analytical theory of complex systems composed of a large number of high-Q dielectric resonators. Spherical and cylindrical dielectric resonators with inferior and also whispering gallery oscillations allocated in various lattices are considered. A new approach to S-matrix parameter calculations based on perturbation theory of Maxwell equations, developed for a number of high-Q dielectric bodies, is introduced. All physical relationships are obtained in analytical form and are suitable for further computations. Essential attention is given to a new unified formalism of the description of scattering processes. The general scattering task for coupled eigen oscillations of the whole system of dielectric resonators is described. The equations for the  expansion coefficients are explained in an applicable way. The temporal Green functions for the dielectric resonator are presented. The scattering process of short pulses in dielectric filter structures, dielectric antennas  and lattices of d...

Terahertz polarization converter based on all-dielectric high birefringence metamaterial with elliptical air holes

KAUST Repository

Zi, Jianchen

2018-02-15

Metamaterials have been widely applied in the polarization conversion of terahertz (THz) waves. However, common plasmonic metamaterials usually work as reflective devices and have low transmissions. All-dielectric metamaterials can overcome these shortcomings. An all-dielectric metamaterial based on silicon with elliptical air holes is reported to achieve high artificial birefringence at THz frequencies. Simulations show that with appropriate structural parameters the birefringence of the dielectric metamaterial can remain flat and is above 0.7 within a broad band. Moreover, the metamaterial can be designed as a broadband quarter wave plate. A sample metamaterial was fabricated and tested to prove the validity of the simulations, and the sample could work as a quarter wave plate at 1.76 THz. The all-dielectric metamaterial that we proposed is of great significance for high performance THz polarization converters.

Evaluation of polysulfone film as a capacitor dielectric material for neutron generator applications

International Nuclear Information System (INIS)

Sidnell, N.A.

1984-01-01

A modified polysulfone film, as manufactured by Bayer (West Germany), is a candidate dielectric material for applications where radiation resistant properties superior to those of Mylar polyester are required. In 1981 it was concluded that polysulfone films exhibited a dielectric strength 20 to 25% lower than Mylar at elevated temperatures of 74 0 C. Consequently, a new design comparable to the SA2954 Mylar capacitor was formulated with equivalent dielectric strength. This design also demonstrated an improvement in overall reliability as compared to the Mylar design when based on functional electrical test and environmental test performance. This design description and accompanying test results are presented in this report

Integration of atomic layer deposited high-k dielectrics on GaSb via hydrogen plasma exposure

Directory of Open Access Journals (Sweden)

Laura B. Ruppalt

2014-12-01

Full Text Available In this letter we report the efficacy of a hydrogen plasma pretreatment for integrating atomic layer deposited (ALD high-k dielectric stacks with device-quality p-type GaSb(001 epitaxial layers. Molecular beam eptiaxy-grown GaSb surfaces were subjected to a 30 minute H2/Ar plasma treatment and subsequently removed to air. High-k HfO2 and Al2O3/HfO2 bilayer insulating films were then deposited via ALD and samples were processed into standard metal-oxide-semiconductor (MOS capacitors. The quality of the semiconductor/dielectric interface was probed by current-voltage and variable-frequency admittance measurements. Measurement results indicate that the H2-plamsa pretreatment leads to a low density of interface states nearly independent of the deposited dielectric material, suggesting that pre-deposition H2-plasma exposure, coupled with ALD of high-k dielectrics, may provide an effective means for achieving high-quality GaSb MOS structures for advanced Sb-based digital and analog electronics.

Polypropylene/Polyaniline Nanofiber/Reduced Graphene Oxide Nanocomposite with Enhanced Electrical, Dielectric, and Ferroelectric Properties for a High Energy Density Capacitor.

Science.gov (United States)

Cho, Sunghun; Kim, Minkyu; Lee, Jun Seop; Jang, Jyongsik

2015-10-14

This work demonstrates a ternary nanocomposite system, composed of polypropylene (PP), redoped PANI (r-PANI) nanofibers, and reduced graphene oxides (RGOs), for use in a high energy density capacitor. r-PANI nanofibers were fabricated by the combination methods of chemical oxidation polymerization and secondary doping processes, resulting in higher conductivity (σ≈156 S cm(-1)) than that of the primarily doped PANI nanofibers (σ≈16 S cm(-1)). RGO sheets with high electron mobility and thermal stability can enhance the conductivity of r-PANI/RGO (σ≈220 S cm(-1)) and thermal stability of PP matrix. These findings could be extended to combine the advantages of r-PANI nanofibers and RGO sheets for developing an efficient means of preparing PP/r-PANI/RGO nanocomposite. When the r-PANI/RGO cofillers (10 vol %) were added to PP matrix, the resulting PP/r-PANI/RGO nanocomposite exhibited high dielectric constant (ε'≈51.8) with small dielectric loss (ε″≈9.3×10(-3)). Furthermore, the PP/r-PANI/RGO nanocomposite was used for an energy-harvesting device, which demonstrated high energy density (Ue≈12.6 J cm(-3)) and breakdown strength (E≈5.86×10(3) kV cm(-1)).

High voltage capacitor design and the determination of solid dielectric voltage breakdown

International Nuclear Information System (INIS)

Hutapea, S.

1976-01-01

The value of the external field intensity serves as an electrical insulating material and is a physical characteristic of the substance. Capacitor discharge in the dielectric medium are experimentally investigated. The high voltage power supply and other instrument needed are briefly discussed. Capacitors with working voltage of 30.000 volt and the plastic being used for dielectrics in the capacitors are also discussed. (author)

Dielectric characteristics of PZT 95/5 ferroelectric ceramics at high pressures

International Nuclear Information System (INIS)

Spears, R.K.

1978-01-01

The room temperature dielectric properties of a ferroelectric ceramic having a nominal composition of 95 atomic percent lead zirconate and 5 atomic percent lead titanate (designated as PZT 95/5) with a niobium dopant were examined at high hydrostatic pressures using a tetrahedral anvil apparatus. This ceramic has practical applications as a power source in which large quantities of charge are released by dynamic (shock wave) depolarization. Numerous mathematical models of this process have been proposed; however, the use of models has been limited because of the lack of high pressure electrical properties. This study attempted to provide these data on PZT 95/5 by determining the small signal and high electric field dielectric properties at pressures over 4 GPa

HIGH-GRADIENT, HIGH-TRANSFORMER-RATIO, DIELECTRIC WAKE FIELD ACCELERATOR

Energy Technology Data Exchange (ETDEWEB)

Hirshfield, Jay L

2012-04-12

The Phase I work reported here responds to DoE'ss stated need "...to develop improved accelerator designs that can provide very high gradient (>200 MV/m for electrons...) acceleration of intense bunches of particles." Omega-P's approach to this goal is through use of a ramped train of annular electron bunches to drive a coaxial dielectric wakefield accelerator (CDWA) structure. This approach is a direct extension of the CDWA concept from acceleration in wake fields caused by a single drive bunch, to the more efficient acceleration that we predict can be realized from a tailored (or ramped) train of several drive bunches. This is possible because of a much higher transformer ratio for the latter. The CDWA structure itself has a number of unique features, including: a high accelerating gradient G, potentially with G > 1 GeV/m; continuous energy coupling from drive to test bunches without transfer structures; inherent transverse focusing forces for particles in the accelerated bunch; highly stable motion of high charge annular drive bunches; acceptable alignment tolerances for a multi-section system. What is new in the present approach is that the coaxial dielectric structure is now to be energized by-not one-but by a short train of ramped annular-shaped drive bunches moving in the outer coaxial channel of the structure. We have shown that this allows acceleration of an electron bunch traveling along the axis in the inner channel with a markedly higher transformer ratio T than for a single drive bunch. As described in this report, the structure will be a GHz-scale prototype with cm-scale transverse dimensions that is expected to confirm principles that can be applied to the design of a future THz-scale high gradient (> 500 MV/m) accelerator with mm-scale transverse dimensions. We show here a new means to significantly increase the transformer ratio T of the device, and thereby to significantly improve its suitability as a flexible and effective component in

Joining Chemical Pressure and Epitaxial Strain to Yield Y-doped BiFeO3 Thin Films with High Dielectric Response

Science.gov (United States)

Scarisoreanu, N. D.; Craciun, F.; Birjega, R.; Ion, V.; Teodorescu, V. S.; Ghica, C.; Negrea, R.; Dinescu, M.

2016-05-01

BiFeO3 is one of the most promising multiferroic materials but undergoes two major drawbacks: low dielectric susceptibility and high dielectric loss. Here we report high in-plane dielectric permittivity (ε’ ∼2500) and low dielectric loss (tan δ priced target.

Dielectric and acoustical high frequency characterisation of PZT thin films

Energy Technology Data Exchange (ETDEWEB)

Conde, Janine; Muralt, Paul, E-mail: janine.conde@epfl.ch [Department of Materials Science, EPFL (Switzerland)

2010-02-15

Pb(Zr, Ti)O{sub 3} (PZT) is an interesting material for bulk acoustic wave resonator applications due to its high electromechanical coupling constant, which would enable fabrication of large bandwidth frequency filters. The major challenge of the PZT solid solution system is to overcome mechanical losses generally observed in PZT ceramics. To increase the understanding of these losses in textured thin films, thin film bulk acoustic resonators (TFBAR's) based on PZT thin films with compositions either in the tetragonal region or at the morphotropic phase boundary and (111) or {l_brace}100{r_brace} textures were fabricated and studied up to 2 GHz. The dielectric and elastic materials coefficients were extracted from impedance measurements at the resonance frequency. The dispersion of the dielectric constant was obtained from impedance measurements up to 2 GHz. The films with varying compositions, textures and deposition methods (sol-gel or sputtering) were compared in terms of dielectric and acoustical properties.

High strength ferritic alloy

International Nuclear Information System (INIS)

1977-01-01

A high strength ferritic steel is specified in which the major alloying elements are chromium and molybdenum, with smaller quantities of niobium, vanadium, silicon, manganese and carbon. The maximum swelling is specified for various irradiation conditions. Rupture strength is also specified. (U.K.)

High voltage research (breakdown strengths of gaseous and liquid insulators). Semiannual report, October 1, 1977--March 31, 1978

International Nuclear Information System (INIS)

Christophorou, L.G.; James, D.R.; Pai, R.Y.; Mathis, R.A.; Sauers, I.; Pace, M.O.; Bouldin, D.W.; Christodoulides, A.A.; Chan, C.C.

1978-06-01

The work on gas mixtures is focused on combinations of gases consisting of strongly electron-attaching components and one or more electron slowing-down components. Hypotheses based on the positions of electronically excited states are borne out experimentally in the low pressure ( 6 . Although the ionization cross section for Ar is very much greater than that for Ne, Ar is a superior buffer gas. A theoretical discussion is given which describes the relation between the dielectric strength of a gas to its physical parameters including the electron attachment cross section, the ionization cross section, the ionization potential, and the electron energy distribution function. Also discussed is the importance of perfluorination in hydrocarbons to effect an increase in the electron attachment cross section and electron affinity and a decrease in the ionization cross section, and hence an increase in dielectric strength. Attachment rates were measured as a function of the mean electron energy for a comprehensive list of perfluorocarbons. Breakdown voltages were determined for SF 6 and for SF 6 (20%)/N 2 (80%) as a function of temperature from -15 0 C to 85 0 C. Environmental aspects of gas dielectrics pertaining to gas decomposition and toxicity were studied

Conductivity, dielectric behavior and FTIR studies of high molecular weight poly(vinylchloride)-lithium triflate polymer electrolytes

Energy Technology Data Exchange (ETDEWEB)

Ramesh, S. [Faculty of Engineering and Science, Universiti Tunku Abdul Rahman, Setapak, 53300 Kuala Lumpur (Malaysia)]. E-mail: ramesh@mail.utar.edu.my; Chai, M.F. [Faculty of Engineering and Science, Universiti Tunku Abdul Rahman, Setapak, 53300 Kuala Lumpur (Malaysia)

2007-05-15

Thin films of high molecular weight polyvinyl chloride (PVC) with lithium triflate (LiCF{sub 3}SO{sub 3}) salt were prepared by solution casting method. The ionic conductivity and dielectric measurements were carried out on these films over a wide frequency regime at various temperatures. The conductivity-temperature plots were found to obey classical Arrhenius relationship. The dielectric behavior was analysed using dielectric permittivity and dielectric modulus of the samples. FTIR studies show some simple overlapping and shift in peaks between high molecular weight polyvinyl chloride (PVC) with lithium triflate (LiCF{sub 3}SO{sub 3}) salt in the polymer electrolyte complexes.

High-k 3D-barium titanate foam/phenolphthalein poly(ether sulfone)/cyanate ester composites with frequency-stable dielectric properties and extremely low dielectric loss under reduced concentration of ceramics

Science.gov (United States)

Zheng, Longhui; Yuan, Li; Guan, Qingbao; Liang, Guozheng; Gu, Aijuan

2018-01-01

Higher dielectric constant, lower dielectric loss and better frequency stability have been the developing trends for high dielectric constant (high-k) materials. Herein, new composites have been developed through building unique structure by using hyperbranched polysiloxane modified 3D-barium titanate foam (BTF) (BTF@HSi) as the functional fillers and phenolphthalein poly(ether sulfone) (cPES)/cyanate ester (CE) blend as the resin matrix. For BTF@HSi/cPES/CE composite with 34.1 vol% BTF, its dielectric constant at 100 Hz is as high as 162 and dielectric loss is only 0.007; moreover, the dielectric properties of BTF@HSi/cPES/CE composites exhibit excellent frequency stability. To reveal the mechanism behind these attractive performances of BTF@HSi/cPES/CE composites, three kinds of composites (BTF/CE, BTF/cPES/CE, BTF@HSi/CE) were prepared, their structure and integrated performances were intensively investigated and compared with those of BTF@HSi/cPES/CE composites. Results show that the surface modification of BTF is good for preparing composites with improved thermal stability; while introducing flexible cPES to CE is beneficial to fabricate composites with good quality through effectively blocking cracks caused by the stress concentration, and then endowing the composites with good dielectric properties at reduced concentration of ceramics.

High Dielectric Low Loss Transparent Glass Material Based Dielectric Resonator Antenna with Wide Bandwidth Operation

Science.gov (United States)

Mehmood, Arshad; Zheng, Yuliang; Braun, Hubertus; Hovhannisyan, Martun; Letz, Martin; Jakoby, Rolf

2015-01-01

This paper presents the application of new high permittivity and low loss glass material for antennas. This glass material is transparent. A very simple rectangular dielectric resonator antenna is designed first with a simple microstrip feeding line. In order to widen the bandwidth, the feed of the design is modified by forming a T-shaped feeding. This new design enhanced the bandwidth range to cover the WLAN 5 GHz band completely. The dielectric resonator antenna cut into precise dimensions is placed on the modified microstrip feed line. The design is simple and easy to manufacture and also very compact in size of only 36 × 28 mm. A -10 dB impedance bandwidth of 18% has been achieved, which covers the frequency range from 5.15 GHz to 5.95 GHz. Simulations of the measured return loss and radiation patterns are presented and discussed.

Contamination aspects in integrating high dielectric constant and ferroelectric materials into CMOS processes

OpenAIRE

Boubekeur, Hocine

2004-01-01

n memory technology, new materials are being intensively investigated to overcome the integration limits of conventional dielectrics for Giga-bit scale integration, or to be able to produce new types of non-volatile low power memories such as FeRAM. Perovskite type high dielectric constant films for use in Giga-bit scale memories or layered perovskite films for use in non-volatile memories involve materials to semiconductor process flows, which entail a high risk of contamination. The introdu...

High dielectric constant and energy density induced by the tunable TiO2 interfacial buffer layer in PVDF nanocomposite contained with core-shell structured TiO2@BaTiO3 nanoparticles

Science.gov (United States)

Hu, Penghao; Jia, Zhuye; Shen, Zhonghui; Wang, Peng; Liu, Xiaoru

2018-05-01

To realize application in high-capacity capacitors and portable electric devices, large energy density is eagerly desired for polymer-based nanocomposite. The core-shell structured nanofillers with inorganic buffer layer are recently supposed to be promising in improving the dielectric property of polymer nanocomposite. In this work, core-shell structured TO@BT nanoparticles with crystalline TiO2 buffer layer coated on BaTiO3 nanoparticle were fabricated via solution method and heat treatment. The thickness of the TO buffer layer can be tailored by modulating the additive amount of the titanate coupling agent in preparation process, and the apparent dielectric properties of nanocomposite are much related to the thickness of the TO layer. The relatively thin TO layer prefer to generate high polarization to increase dielectric constant while the relatively thick TO layer would rather to homogenize field to maintain breakdown strength. Simulation of electric field distribution in the interfacial region reveals the improving effect of the TO buffer layer on the dielectric properties of nanocomposite which accords with the experimental results well. The optimized nanoparticle TO@BT-2 with a mean thickness of 3-5 nm buffer layer of TO is effective in increasing both the ε and Eb in the PVDF composite film. The maximal discharged energy density of 8.78 J/cm3 with high energy efficiency above 0.6 is obtained in TO@BT-2/PVDF nanocomposite with 2.5 vol% loading close to the breakdown strength of 380 kV/mm. The present study demonstrates the approach to optimize the structure of core-shell nanoparticles by modulating buffer layer and provides a new way to further enlarge energy density in polymer nanocomposite.

Cluster synthesis of monodisperse rutile-TiO2 nanoparticles and dielectric TiO2-vinylidene fluoride oligomer nanocomposites

International Nuclear Information System (INIS)

Balasubramanian, Balamurugan; Kraemer, Kristin L; Valloppilly, Shah R; Ducharme, Stephen; Sellmyer, David J

2011-01-01

The embedding of oxide nanoparticles in polymer matrices produces a greatly enhanced dielectric response by combining the high dielectric strength and low loss of suitable host polymers with the high electric polarizability of nanoparticles. The fabrication of oxide-polymer nanocomposites with well-controlled distributions of nanoparticles is, however, challenging due to the thermodynamic and kinetic barriers between the polymer matrix and nanoparticle fillers. In the present study, monodisperse TiO 2 nanoparticles having an average particle size of 14.4 nm and predominant rutile phase were produced using a cluster-deposition technique without high-temperature thermal annealing and subsequently coated with uniform vinylidene fluoride oligomer (VDFO) molecules using a thermal evaporation source, prior to deposition as TiO 2 -VDFO nanocomposite films on suitable substrates. The molecular coatings on TiO 2 nanoparticles serve two purposes, namely to prevent the TiO 2 nanoparticles from contacting each other and to couple the nanoparticle polarization to the matrix. Parallel-plate capacitors made of TiO 2 -VDFO nanocomposite film as the dielectric exhibit minimum dielectric dispersion and low dielectric loss. Dielectric measurements also show an enhanced effective dielectric constant in TiO 2 -VDFO nanocomposites as compared to that of pure VDFO. This study demonstrates for the first time a unique electroactive particle coating in the form of a ferroelectric VDFO that has high-temperature stability as compared to conventionally used polymers for fabricating dielectric oxide-polymer nanocomposites.

Dielectric properties of NaF–B2O3 glasses doped with certain ...

Indian Academy of Sciences (India)

Dielectric constant ε, loss tan δ, a.c. conductivity σ and dielectric breakdown strength of NaF–B2O3 glasses ... Heat flow % ... peratures of these glasses were determined from the diffe- ... measured values of density d and calculated average.

Electrical Capacitance Volume Tomography with High-Contrast Dielectrics

Science.gov (United States)

Nurge, Mark

2010-01-01

The Electrical Capacitance Volume Tomography (ECVT) system has been designed to complement the tools created to sense the presence of water in nonconductive spacecraft materials, by helping to not only find the approximate location of moisture but also its quantity and depth. The ECVT system has been created for use with a new image reconstruction algorithm capable of imaging high-contrast dielectric distributions. Rather than relying solely on mutual capacitance readings as is done in traditional electrical capacitance tomography applications, this method reconstructs high-resolution images using only the self-capacitance measurements. The image reconstruction method assumes that the material under inspection consists of a binary dielectric distribution, with either a high relative dielectric value representing the water or a low dielectric value for the background material. By constraining the unknown dielectric material to one of two values, the inverse math problem that must be solved to generate the image is no longer ill-determined. The image resolution becomes limited only by the accuracy and resolution of the measurement circuitry. Images were reconstructed using this method with both synthetic and real data acquired using an aluminum structure inserted at different positions within the sensing region. The cuboid geometry of the system has two parallel planes of 16 conductors arranged in a 4 4 pattern. The electrode geometry consists of parallel planes of copper conductors, connected through custom-built switch electronics, to a commercially available capacitance to digital converter. The figure shows two 4 4 arrays of electrodes milled from square sections of copper-clad circuit-board material and mounted on two pieces of glass-filled plastic backing, which were cut to approximately square shapes, 10 cm on a side. Each electrode is placed on 2.0-cm centers. The parallel arrays were mounted with the electrode arrays approximately 3 cm apart. The open ends

Super Dielectric Materials.

Science.gov (United States)

Fromille, Samuel; Phillips, Jonathan

2014-12-22

Evidence is provided here that a class of materials with dielectric constants greater than 10⁵ at low frequency (dielectric materials (SDM), can be generated readily from common, inexpensive materials. Specifically it is demonstrated that high surface area alumina powders, loaded to the incipient wetness point with a solution of boric acid dissolved in water, have dielectric constants, near 0 Hz, greater than 4 × 10⁸ in all cases, a remarkable increase over the best dielectric constants previously measured for energy storage capabilities, ca. 1 × 10⁴. It is postulated that any porous, electrically insulating material (e.g., high surface area powders of silica, titania, etc. ), filled with a liquid containing a high concentration of ionic species will potentially be an SDM. Capacitors created with the first generated SDM dielectrics (alumina with boric acid solution), herein called New Paradigm Super (NPS) capacitors display typical electrostatic capacitive behavior, such as increasing capacitance with decreasing thickness, and can be cycled, but are limited to a maximum effective operating voltage of about 0.8 V. A simple theory is presented: Water containing relatively high concentrations of dissolved ions saturates all, or virtually all, the pores (average diameter 500 Å) of the alumina. In an applied field the positive ionic species migrate to the cathode end, and the negative ions to the anode end of each drop. This creates giant dipoles with high charge, hence leading to high dielectric constant behavior. At about 0.8 V, water begins to break down, creating enough ionic species to "short" the individual water droplets. Potentially NPS capacitor stacks can surpass "supercapacitors" in volumetric energy density.

Perovskite oxynitride LaTiOxNy thin films: Dielectric characterization in low and high frequencies

International Nuclear Information System (INIS)

Lu, Y.; Ziani, A.; Le Paven-Thivet, C.; Benzerga, R.; Le Gendre, L.; Fasquelle, D.; Kassem, H.

2011-01-01

Lanthanum titanium oxynitride (LaTiO x N y ) thin films are studied with respect to their dielectric properties in low and high frequencies. Thin films are deposited by radio frequency magnetron sputtering on different substrates. Effects of nitrogen content and crystalline quality on dielectric properties are investigated. In low-frequency range, textured LaTiO x N y thin films deposited on conductive single crystal Nb–STO show a dielectric constant ε′ ≈ 140 with low losses tanδ = 0.012 at 100 kHz. For the LaTiO x N y polycrystalline films deposited on conductive silicon substrates with platinum (Pt/Ti/SiO 2 /Si), the tunability reached up to 57% for a weak electric field of 50 kV/cm. In high-frequency range, epitaxial LaTiO x N y films deposited on MgO substrate present a high dielectric constant with low losses (ε′ ≈ 170, tanδ = 0.011, 12 GHz).

High-performance pentacene OTFT by incorporating Ti in LaON gate dielectric

Science.gov (United States)

Ma, Y. X.; Han, C. Y.; Tang, W. M.; Lai, P. T.

2017-07-01

Pentacene organic thin-film transistors (OTFT) using high-k LaTiON gate dielectric with different Ti contents are investigated. The LaxTi(1-x)ON films (with x = 1, 0.87, 0.76, and 0.67) are deposited by reactive sputtering followed by an annealing in N2 at 200 °C. The OTFT with La0.87Ti0.13ON can achieve a high carrier mobility of 2.6 cm2/V.s, a small threshold voltage of -1.5 V, a small sub-threshold swing of 0.07 V/dec, and a small hysteresis of 0.17 V. AFM and X-ray photoelectron spectroscopy reveal that Ti can suppress the hygroscopicity of La oxide to achieve a smoother dielectric surface, which can result in larger pentacene grains and thus higher carrier mobility. All the devices show a clockwise hysteresis because both the LaOH formation and Ti incorporation can generate acceptor-like traps in the gate dielectric.

Investigation of high- k yttrium copper titanate thin films as alternative gate dielectrics

International Nuclear Information System (INIS)

Monteduro, Anna Grazia; Ameer, Zoobia; Rizzato, Silvia; Martino, Maurizio; Caricato, Anna Paola; Maruccio, Giuseppe; Tasco, Vittorianna; Lekshmi, Indira Chaitanya; Hazarika, Abhijit; Choudhury, Debraj; Sarma, D D

2016-01-01

Nearly amorphous high- k yttrium copper titanate thin films deposited by laser ablation were investigated in both metal–oxide–semiconductor (MOS) and metal–insulator–metal (MIM) junctions in order to assess the potentialities of this material as a gate oxide. The trend of dielectric parameters with film deposition shows a wide tunability for the dielectric constant and AC conductivity, with a remarkably high dielectric constant value of up to 95 for the thick films and conductivity as low as 6  ×  10 −10 S cm −1 for the thin films deposited at high oxygen pressure. The AC conductivity analysis points out a decrease in the conductivity, indicating the formation of a blocking interface layer, probably due to partial oxidation of the thin films during cool-down in an oxygen atmosphere. Topography and surface potential characterizations highlight differences in the thin film microstructure as a function of the deposition conditions; these differences seem to affect their electrical properties. (paper)

Study of Dielectric Breakdown Performance of Transformer Oil Based Magnetic Nanofluids

Directory of Open Access Journals (Sweden)

Yuzhen Lv

2017-07-01

Full Text Available Research on the transformer oil-based nanofluids (NFs has been raised expeditiously over the past decade. Although, there is discrepancy in the stated results and inadequate understanding of the mechanisms of improvement of dielectric nanofluids, these nanofluids have emerged as a potential substitute of mineral oils as insulating and heat removal fluids for high voltage equipment. The transformer oil (TO based magnetic fluids (ferrofluids may be regarded as the posterity insulation fluids as they propose inspiring unique prospectus to improve dielectric breakdown strength, as well as heat transfer efficiency, as compared to pure transformer oils. In this work, transformer oil-based magnetic nanofluids (MNFs are prepared by dispersal of Fe3O4 nanoparticles (MNPs into mineral oil as base oil, with various NPs loading from 5 to 80% w/v. The lightning impulse breakdown voltages (BDV measurement was conducted in accordance with IEC 60897 by using needle to sphere electrodes geometry. The test results showed that dispersion of magnetic NPs may improve the insulation strength of MO. With the increment of NPs concentrations, the positive lightning impulse (LI breakdown strength of TO is first raised, up to the highest value at 40% loading, and then tends to decrease at higher concentrations. The outcomes of negative LI breakdown showed that BDV of MNFs, with numerous loadings, were inferior to the breakdown strength of pure MO. The 40% concentration of nanoparticles (optimum concentration was selected, and positive and negative LI breakdown strength was also further studied at different sizes (10 nm, 20 nm, 30 nm and 40 nm of NPs and different electrode gap distances. Augmentation in the BDV of the ferrofluids (FFs is primarily because of dielectric and magnetic features of Fe3O4 nanoaprticles, which act as electron scavengers and decrease the rate of free electrons produced in the ionization process. Research challenges and technical difficulties

Study of high-k gate dielectrics by means of positron annihilation

International Nuclear Information System (INIS)

Uedono, A.; Naito, T.; Otsuka, T.; Ito, K.; Shiraishi, K.; Yamabe, K.; Miyazaki, S.; Watanabe, H.; Umezawa, N.; Hamid, A.; Chikyow, T.; Ohdaira, T.; Suzuki, R.; Ishibashi, S.; Inumiya, S.; Kamiyama, S.; Akasaka, Y.; Nara, Y.; Yamada, K.

2007-01-01

High-dielectric constant (high-k) gate materials, such as HfSiO x and HfAlO x , fabricated by atomic-layer-deposition techniques were characterized using monoenergetic positron beams. Measurements of the Doppler broadening spectra of annihilation radiation and the lifetime spectra of positrons indicated that positrons annihilated from the trapped state by open volumes that exist intrinsically in amorphous structures of the films. The size distributions of the open volumes and the local atomic configurations around such volumes can be discussed using positron annihilation parameters, and they were found to correlate with the electrical properties of the films. We confirmed that the positron annihilation is useful technique to characterize the matrix structure of amorphous high-k materials, and can be used to determine process parameters for the fabrication of high-k gate dielectrics. (copyright 2007 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

High current electron beam acceleration in dielectric-filled RF cavities

International Nuclear Information System (INIS)

Faehl, R.J.; Keinigs, R.K.

1996-01-01

The acceleration of charged particles in radio frequency (RF) cavities is a widely used mode in high energy accelerators. Advantages include very high accelerating gradients and very stable phase control. A traditional limitation for such acceleration has been their use for intense, high current beam generation. This constraint arises from the inability to store a large amount of electromagnetic energy in the cavity and from loading effects of the beam on the cavity. The authors have studied a simple modification to transcend these limitations. Following Humphries and Huang, they have conducted analytic and numerical investigations of RF accelerator cavities in which a high dielectric constant material, such as water, replaces most of the cavity volume. This raises the stored energy in a cavity of given dimensions by a factor var-epsilon/var-epsilon 0 . For a water fill, var-epsilon/var-epsilon 0 ∼ 80, depending on the frequency. This introduction of high dielectric constant material into the cavity reduces the resonant frequencies by a factor of (var-epsilon/var-epsilon 0 ) 1/2 . This reduced operating frequency mans that existing high efficiency power supplies, at lower frequencies, can be used for an accelerator

Super Dielectric Materials

Directory of Open Access Journals (Sweden)

Samuel Fromille

2014-12-01

Full Text Available Evidence is provided here that a class of materials with dielectric constants greater than 105 at low frequency (<10−2 Hz, herein called super dielectric materials (SDM, can be generated readily from common, inexpensive materials. Specifically it is demonstrated that high surface area alumina powders, loaded to the incipient wetness point with a solution of boric acid dissolved in water, have dielectric constants, near 0 Hz, greater than 4 × 108 in all cases, a remarkable increase over the best dielectric constants previously measured for energy storage capabilities, ca. 1 × 104. It is postulated that any porous, electrically insulating material (e.g., high surface area powders of silica, titania, etc., filled with a liquid containing a high concentration of ionic species will potentially be an SDM. Capacitors created with the first generated SDM dielectrics (alumina with boric acid solution, herein called New Paradigm Super (NPS capacitors display typical electrostatic capacitive behavior, such as increasing capacitance with decreasing thickness, and can be cycled, but are limited to a maximum effective operating voltage of about 0.8 V. A simple theory is presented: Water containing relatively high concentrations of dissolved ions saturates all, or virtually all, the pores (average diameter 500 Å of the alumina. In an applied field the positive ionic species migrate to the cathode end, and the negative ions to the anode end of each drop. This creates giant dipoles with high charge, hence leading to high dielectric constant behavior. At about 0.8 V, water begins to break down, creating enough ionic species to “short” the individual water droplets. Potentially NPS capacitor stacks can surpass “supercapacitors” in volumetric energy density.

High voltage research (breakdown strengths of gaseous and liquid insulators). Semiannual report, October 1, 1977--March 31, 1978. [Summaries of research activities at Oak Ridge National Laboratory

Energy Technology Data Exchange (ETDEWEB)

Christophorou, L.G.; James, D.R.; Pai, R.Y.; Mathis, R.A.; Sauers, I.; Pace, M.O.; Bouldin, D.W.; Christodoulides, A.A.; Chan, C.C.

1978-06-01

The work on gas mixtures is focused on combinations of gases consisting of strongly electron-attaching components and one or more electron slowing-down components. Hypotheses based on the positions of electronically excited states are borne out experimentally in the low pressure (<1000 torr) breakdown measurements. The high pressure work shows dramatically the importance of the electron scattering cross section on breakdown strength by comparing Ar with Ne as single gases and in mixtures with SF/sub 6/. Although the ionization cross section for Ar is very much greater than that for Ne, Ar is a superior buffer gas. A theoretical discussion is given which describes the relation between the dielectric strength of a gas to its physical parameters including the electron attachment cross section, the ionization cross section, the ionization potential, and the electron energy distribution function. Also discussed is the importance of perfluorination in hydrocarbons to effect an increase in the electron attachment cross section and electron affinity and a decrease in the ionization cross section, and hence an increase in dielectric strength. Attachment rates were measured as a function of the mean electron energy for a comprehensive list of perfluorocarbons. Breakdown voltages were determined for SF/sub 6/ and for SF/sub 6/ (20%)/N/sub 2/(80%) as a function of temperature from -15/sup 0/C to 85/sup 0/C. Environmental aspects of gas dielectrics pertaining to gas decomposition and toxicity were studied.

Influence of silica fume on the strength of high strength concrete

International Nuclear Information System (INIS)

Akram, T.; Memon, S.A.; Khan, S.A.

2007-01-01

HSC (High Strength Concrete) does not become evident by a sudden change in the behavior of 'ordinary strength' concrete. There is a gradual effect that becomes more noticeable when the strength level exceeds about 40-45 MPa. There cannot be a precise level of strength which defines this change in effect. The effects are on strength and workability, requiring us to take into account in our mix proportioning, the ramifications of fineness of cement on workability and of type of aggregate and aggregate/cement ratio on strength. In fact, the selection of materials becomes more critical as the concrete strength increases and that if very high strength is required (100 MPa and higher), relatively few materials may be suitable. An experimental investigation is carried out to evaluate the feasibility of producing HSC using locally available materials and to study the influence of silica fume on the strength of HSC. The main variables in this research is amount of silica fume. The parameters that are kept constant are the amount of cement equal to 580 kg/m3, dosage of HRWRA (High Range Water Reducing Admictures) equal to 4 % by weight of cementitious materials and the ratio of fine aggregate to coarse aggregate (1:2.3). Test results revealed that it is feasible to produce HSC using locally available materials. The optimum percentage of silica fume was found to be 15 % by weight of cement. (author)

Polymer/metal oxide hybrid dielectrics for low voltage field-effect transistors with solution-processed, high-mobility semiconductors

Energy Technology Data Exchange (ETDEWEB)

Held, Martin; Schießl, Stefan P.; Gannott, Florentina [Department of Materials Science and Engineering, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen D-91058 (Germany); Institute for Physical Chemistry, Universität Heidelberg, Heidelberg D-69120 (Germany); Miehler, Dominik [Department of Materials Science and Engineering, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen D-91058 (Germany); Zaumseil, Jana, E-mail: zaumseil@uni-heidelberg.de [Institute for Physical Chemistry, Universität Heidelberg, Heidelberg D-69120 (Germany)

2015-08-24

Transistors for future flexible organic light-emitting diode (OLED) display backplanes should operate at low voltages and be able to sustain high currents over long times without degradation. Hence, high capacitance dielectrics with low surface trap densities are required that are compatible with solution-processable high-mobility semiconductors. Here, we combine poly(methyl methacrylate) (PMMA) and atomic layer deposition hafnium oxide (HfO{sub x}) into a bilayer hybrid dielectric for field-effect transistors with a donor-acceptor polymer (DPPT-TT) or single-walled carbon nanotubes (SWNTs) as the semiconductor and demonstrate substantially improved device performances for both. The ultra-thin PMMA layer ensures a low density of trap states at the semiconductor-dielectric interface while the metal oxide layer provides high capacitance, low gate leakage and superior barrier properties. Transistors with these thin (≤70 nm), high capacitance (100–300 nF/cm{sup 2}) hybrid dielectrics enable low operating voltages (<5 V), balanced charge carrier mobilities and low threshold voltages. Moreover, the hybrid layers substantially improve the bias stress stability of the transistors compared to those with pure PMMA and HfO{sub x} dielectrics.

Optical design for increased interaction length in a high gradient dielectric laser accelerator

OpenAIRE

Cesar, D.; Maxson, J.; Musumeci, P.; Shen, X.; England, R. J.; Wootton, K. P.

2018-01-01

We present a methodology for designing and measuring pulse front tilt in an ultrafast laser for use in dielectric laser acceleration. Previous research into dielectric laser accelerating modules has focused on measuring high accelerating gradients in novel structures, but has done so only for short electron-laser coupling lengths. Here we demonstrate an optical design to extend the laser-electron interaction to 1mm.

Poly(vinylidene fluoride) Flexible Nanocomposite Films with Dopamine-Coated Giant Dielectric Ceramic Nanopowders, Ba(Fe0.5Ta0.5)O3, for High Energy-Storage Density at Low Electric Field.

Science.gov (United States)

Wang, Zhuo; Wang, Tian; Wang, Chun; Xiao, Yujia; Jing, Panpan; Cui, Yongfei; Pu, Yongping

2017-08-30

Ba(Fe 0.5 Ta 0.5 )O 3 /poly(vinylidene fluoride) (BFT/PVDF) flexible nanocomposite films are fabricated by tape casting using dopamine (DA)-modified BFT nanopowders and PVDF as a matrix polymer. After a surface modification of installing a DA layer with a thickness of 5 nm, the interfacial couple interaction between BFT and PVDF is enhanced, resulting in less hole defects at the interface. Then the dielectric constant (ε'), loss tangent (tan δ), and AC conductivity of nanocomposite films are reduced. Meanwhile, the value of the reduced dielectric constant (Δε') and the strength of interfacial polarization (k) are introduced to illustrate the effect of DA on the dielectric behavior of nanocomposite films. Δε' can be used to calculate the magnitude of interfacial polarization, and the strength of the dielectric constant contributed by the interface can be expressed as k. Most importantly, the energy-storage density and energy-storage efficiency of nanocomposite films with a small BFT@DA filler content of 1 vol % at a low electric field of 150 MV/m are enhanced by about 15% and 120%, respectively, after DA modification. The high energy-storage density of 1.81 J/cm 3 is obtained in the sample. This value is much larger than the reported polymer-based nanocomposite films. In addition, the outstanding cycle and bending stability of the nanocomposite films make it a promising candidate for future flexible portable energy devices.

Nonlinear dielectric thin films for high-power electric storage with energy density comparable with electrochemical supercapacitors.

Science.gov (United States)

Yao, Kui; Chen, Shuting; Rahimabady, Mojtaba; Mirshekarloo, Meysam Sharifzadeh; Yu, Shuhui; Tay, Francis Eng Hock; Sritharan, Thirumany; Lu, Li

2011-09-01

Although batteries possess high energy storage density, their output power is limited by the slow movement of charge carriers, and thus capacitors are often required to deliver high power output. Dielectric capacitors have high power density with fast discharge rate, but their energy density is typically much lower than electrochemical supercapacitors. Increasing the energy density of dielectric materials is highly desired to extend their applications in many emerging power system applications. In this paper, we review the mechanisms and major characteristics of electric energy storage with electrochemical supercapacitors and dielectric capacitors. Three types of in-house-produced ferroic nonlinear dielectric thin film materials with high energy density are described, including (Pb(0.97)La(0.02))(Zr(0.90)Sn(0.05)Ti(0.05))O(3) (PLZST) antiferroelectric ceramic thin films, Pb(Zn(1/3)Nb(2/3))O(3-)Pb(Mg(1/3)Nb(2/3))O(3-)PbTiO(3) (PZN-PMN-PT) relaxor ferroelectric ceramic thin films, and poly(vinylidene fluoride) (PVDF)-based polymer blend thin films. The results showed that these thin film materials are promising for electric storage with outstandingly high power density and fairly high energy density, comparable with electrochemical supercapacitors.

Communication: Modeling electrolyte mixtures with concentration dependent dielectric permittivity

Science.gov (United States)

Chen, Hsieh; Panagiotopoulos, Athanassios Z.

2018-01-01

We report a new implicit-solvent simulation model for electrolyte mixtures based on the concept of concentration dependent dielectric permittivity. A combining rule is found to predict the dielectric permittivity of electrolyte mixtures based on the experimentally measured dielectric permittivity for pure electrolytes as well as the mole fractions of the electrolytes in mixtures. Using grand canonical Monte Carlo simulations, we demonstrate that this approach allows us to accurately reproduce the mean ionic activity coefficients of NaCl in NaCl-CaCl2 mixtures at ionic strengths up to I = 3M. These results are important for thermodynamic studies of geologically relevant brines and physiological fluids.

Microstructure and chemical analysis of Hf-based high-k dielectric layers in metal-insulator-metal capacitors

Energy Technology Data Exchange (ETDEWEB)

Thangadurai, P. [Department of Materials Engineering, Technion - Israel Institute of Technology, Haifa 32000 (Israel); Mikhelashvili, V.; Eisenstein, G. [Department of Electrical Engineering, Technion - Israel Institute of Technology, Haifa 32000 (Israel); Kaplan, W.D., E-mail: kaplan@tx.technion.ac.i [Department of Materials Engineering, Technion - Israel Institute of Technology, Haifa 32000 (Israel)

2010-05-31

The microstructure and chemistry of the high-k gate dielectric significantly influences the performance of metal-insulator-metal (MIM) and metal-oxide-semiconductor devices. In particular, the local structure, chemistry, and inter-layer mixing are important phenomena to be understood. In the present study, high resolution and analytical transmission electron microscopy are combined to study the local structure, morphology, and chemistry in MIM capacitors containing a Hf-based high-k dielectric. The gate dielectric, bottom and gate electrodes were deposited on p-type Si(100) wafers by electron beam evaporation. Four chemically distinguishable sub-layers were identified within the dielectric stack. One is an unintentionally formed 4.0 nm thick interfacial layer of Ta{sub 2}O{sub 5} at the interface between the Ta electrode and the dielectric. The other three layers are based on HfN{sub x}O{sub y} and HfTiO{sub y}, and intermixing between the nearby sub-layers including deposited SiO{sub 2}. Hf-rich clusters were found in the HfN{sub x}O{sub y} layer adjacent to the Ta{sub 2}O{sub 5} layer.

Influence of O{sub 2} on the dielectric properties of CO{sub 2} at the elevated temperatures

Energy Technology Data Exchange (ETDEWEB)

Rong, Mingzhe; Sun, Hao; Yang, Fei, E-mail: yfei2007@mail.xjtu.edu.cn; Wu, Yi, E-mail: wuyic51@mail.xjtu.edu.cn; Chen, Zhexin; Wang, Xiaohua; Wu, Mingliang [State Key Laboratory of Electrical Insulation and Power Equipment, Xi' an Jiaotong University, Xi' an Shaanxi 710049 (China)

2014-11-15

SF{sub 6} gas is widely used in the high voltage circuit breakers but considering its high global warming potential other substitutes are being sought. Among them CO{sub 2} was investigated and even has been used in some practical products. However, at room temperature, the dielectric properties of CO{sub 2} are relatively lower than SF{sub 6} and air. The goal of this work is to investigate a CO{sub 2}-based gas to improve the performance of the pure CO{sub 2}. In this paper, the dielectric properties of hot CO{sub 2}/O{sub 2} mixtures related to the dielectric recovery phase of the circuit breaker were investigated in the temperature range from 300 K to 4000 K and in the pressure range from 0.01 MPa to 1.0 MPa. The species compositions of hot CO{sub 2}/O{sub 2} were obtained based on Gibbs free energy minimization under the assumptions of local thermodynamic equilibrium and local chemical equilibrium. The reduced critical electric field strength of CO{sub 2}/O{sub 2} was determined by balancing electron generation and loss. These were calculated using the electron energy distribution function by solving the Boltzmann transport equation. The validity of the calculation method and the cross sections data was confirmed by comparing the measurements and calculations of the electron swarm data in previous work. The results indicate that in pure CO{sub 2} the critical electric field strength is higher only in higher temperature range. By adding the O{sub 2} into the CO{sub 2}, the critical electric field strength at lower temperature is effectively enhanced. CO{sub 2}/O{sub 2} mixtures have a much better dielectric strength than both the pure CO{sub 2} and air and thus have the potential to improve the CO{sub 2}-based gas circuit breakers. Similar conclusions can also be found in others’ work, which further confirm the validity of these results.

Dielectrics in electric fields

CERN Document Server

Raju, Gorur G

2003-01-01

Discover nontraditional applications of dielectric studies in this exceptionally crafted field reference or text for seniors and graduate students in power engineering tracks. This text contains more than 800 display equations and discusses polarization phenomena in dielectrics, the complex dielectric constant in an alternating electric field, dielectric relaxation and interfacial polarization, the measurement of absorption and desorption currents in time domains, and high field conduction phenomena. Dielectrics in Electric Fields is an interdisciplinary reference and text for professionals and students in electrical and electronics, chemical, biochemical, and environmental engineering; physical, surface, and colloid chemistry; materials science; and chemical physics.

Low percolation transitions in carbon nanotube networks dispersed in a polymer matrix: dielectric properties, simulations and experiments.

Science.gov (United States)

Simoes, Ricardo; Silva, Jaime; Vaia, Richard; Sencadas, Vítor; Costa, Pedro; Gomes, João; Lanceros-Méndez, Senentxu

2009-01-21

The low concentration behaviour and the increase of the dielectric constant in carbon nanotubes/polymer nanocomposites near the percolation threshold are still not well understood. In this work, a numerical model has been developed which focuses on the effect of the inclusion of conductive fillers in a dielectric polymer matrix on the dielectric constant and the dielectric strength. Experiments have been carried out in carbon nanotubes/poly(vinylidene fluoride) nanocomposites in order to compare to the simulation results. This work shows how the critical concentration is related to the formation of capacitor networks and that these networks give rise to high variations in the electrical properties of the composites. Based on numerical studies, the dependence of the percolation transition on the preparation of the nanocomposite is discussed. Finally, based on numerical and experimental results, both ours and from other authors, the causes of anomalous percolation behaviour of the dielectric constant are identified.

Yttrium scandate thin film as alternative high-permittivity dielectric for germanium gate stack formation

Energy Technology Data Exchange (ETDEWEB)

Lu, Cimang, E-mail: cimang@adam.t.u-tokyo.ac.jp; Lee, Choong Hyun; Nishimura, Tomonori; Toriumi, Akira [Department of Materials Engineering, The University of Tokyo, 7-3-1 Hongo, Tokyo 113-8656 (Japan); JST, CREST, 7-3-1 Hongo, Tokyo 113-8656 (Japan)

2015-08-17

We investigated yttrium scandate (YScO{sub 3}) as an alternative high-permittivity (k) dielectric thin film for Ge gate stack formation. Significant enhancement of k-value is reported in YScO{sub 3} comparing to both of its binary compounds, Y{sub 2}O{sub 3} and Sc{sub 2}O{sub 3}, without any cost of interface properties. It suggests a feasible approach to a design of promising high-k dielectrics for Ge gate stack, namely, the formation of high-k ternary oxide out of two medium-k binary oxides. Aggressive scaling of equivalent oxide thickness (EOT) with promising interface properties is presented by using YScO{sub 3} as high-k dielectric and yttrium-doped GeO{sub 2} (Y-GeO{sub 2}) as interfacial layer, for a demonstration of high-k gate stack on Ge. In addition, we demonstrate Ge n-MOSFET performance showing the peak electron mobility over 1000 cm{sup 2}/V s in sub-nm EOT region by YScO{sub 3}/Y-GeO{sub 2}/Ge gate stack.

Electrical Breakdown and Mechanical Ageing in Dielectric Elastomers

DEFF Research Database (Denmark)

Zakaria, Shamsul Bin

Dielectric elastomers (DE) are used in various applications, such as artificial eye lids, pressure sensors and human motion energy generators. For many applications, one of the major factors that limits the DE performance is premature electrical breakdown. There are many approaches that have been......, the lifetime of elastomer materials needs further investigation. Therefore, in the second strategy, several DE parameters such as Young’s moduli, breakdown strengths and dielectric permittivities of PDMS elastomers filled with hard filler particles were investigated after being subjected to pre...

Preparation and properties of mesoporous silica/bismaleimide/diallylbisphenol composites with improved thermal stability, mechanical and dielectric properties

Directory of Open Access Journals (Sweden)

2011-06-01

Full Text Available New composites with improved thermal stability, mechanical and dielectric properties were developed, which consist of 2,2'-diallylbisphenol A (DBA/4,4'-bismaleimidodiphenylmethane (BDM resin and a new kind of organic/inorganic mesoporous silica (MPSA. Typical properties (curing behavior and mechanism, thermal stability, mechanical and dielectric properties of the composites were systematically investigated, and their origins were discussed. Results show that MPSA/DBA/BDM composites have similar curing temperature as DBA/BDM resin does; however, they have different curing mechanisms, and thus different crosslinked networks. The content of MPSA has close relation with the integrated performance of cured composites. Compared with cured DBA/BDM resin, composites with suitable content of MPSA show obviously improved flexural strength and modulus as well as impact strength; in addition, all composites not only have lower dielectric constant and similar frequency dependence, more interestingly, they also exhibit better stability of frequency on dielectric loss. For thermal stability, the addition of MPSA to DBA/BDM resin significantly decreases the coefficient of thermal expansion, and improves the char yield at high temperature with a slightly reduced glass transition temperature. All these differences in macro-properties are attributed to the different crosslinked networks between MPSA/DBA/BDM composites and DBA/BDM resin.

Compressive and flexural strength of high strength phase change mortar

Science.gov (United States)

Qiao, Qingyao; Fang, Changle

2018-04-01

High-strength cement produces a lot of hydration heat when hydrated, it will usually lead to thermal cracks. Phase change materials (PCM) are very potential thermal storage materials. Utilize PCM can help reduce the hydration heat. Research shows that apply suitable amount of PCM has a significant effect on improving the compressive strength of cement mortar, and can also improve the flexural strength to some extent.

Investigation of 6T SRAM memory circuit using high-k dielectrics based nano scale junctionless transistor

Science.gov (United States)

Charles Pravin, J.; Nirmal, D.; Prajoon, P.; Mohan Kumar, N.; Ajayan, J.

2017-04-01

In this paper the Dual Metal Surround Gate Junctionless Transistor (DMSGJLT) has been implemented with various high-k dielectric. The leakage current in the device is analysed in detail by obtaining the band structure for different high-k dielectric material. It is noticed that with increasing dielectric constant the device provides more resistance for the direct tunnelling of electron in off state. The gate oxide capacitance also shows 0.1 μF improvement with Hafnium Oxide (HfO2) than Silicon Oxide (SiO2). This paved the way for a better memory application when high-k dielectric is used. The Six Transistor (6T) Static Random Access Memory (SRAM) circuit implemented shows 41.4% improvement in read noise margin for HfO2 than SiO2. It also shows 37.49% improvement in write noise margin and 30.16% improvement in hold noise margin for HfO2 than SiO2.

Investigation of dielectric breakdown in silica-epoxy nanocomposites using designed interfaces.

Science.gov (United States)

Bell, Michael; Krentz, Timothy; Keith Nelson, J; Schadler, Linda; Wu, Ke; Breneman, Curt; Zhao, Su; Hillborg, Henrik; Benicewicz, Brian

2017-06-01

Adding nano-sized fillers to epoxy has proven to be an effective method for improving dielectric breakdown strength (DBS). Evidence suggests that dispersion state, as well as chemistry at the filler-matrix interface can play a crucial role in property enhancement. Herein we investigate the contribution of both filler dispersion and surface chemistry on the AC dielectric breakdown strength of silica-epoxy nanocomposites. Ligand engineering was used to synthesize bimodal ligands onto 15nm silica nanoparticles consisting of long epoxy compatible, poly(glycidyl methacrylate) (PGMA) chains, and short, π-conjugated, electroactive surface ligands. Surface initiated RAFT polymerization was used to synthesize multiple graft densities of PGMA chains, ultimately controlling the dispersion of the filler. Thiophene, anthracene, and terthiophene were employed as π-conjugated surface ligands that act as electron traps to mitigate avalanche breakdown. Investigation of the synthesized multifunctional nanoparticles was effective in defining the maximum particle spacing or free space length (L f ) that still leads to property enhancement, as well as giving insight into the effects of varying the electronic nature of the molecules at the interface on breakdown strength. Optimization of the investigated variables was shown to increase the AC dielectric breakdown strength of epoxy composites as much as 34% with only 2wt% silica loading. Copyright © 2017 Elsevier Inc. All rights reserved.

Numerical and experimental investigation of dielectric recovery in supercritical N2

International Nuclear Information System (INIS)

Zhang, J; Van Heesch, E J M; Markosyan, A H; Ebert, U; Seeger, M; Van Veldhuizen, E M

2015-01-01

A supercritical (SC) nitrogen (N 2 ) switch is designed and tested. The dielectric strength and recovery rate of the SC switch are investigated by experiments. In order to theoretically study the discharge and recovery process of the SC N 2 switch under high repetition rate operation, a numerical model is developed. For SC N 2 with initial parameters of p = 80.9 bar and T = 300 K, the simulation results show that within several nanoseconds after the streamer bridges the switch gap, the spark is fully developed and this time depends on the applied electric field between electrodes. During the whole discharge process, the maximum temperature in the channel is about 20 000 K. About 10 µs after the spark excitation of 200 ns duration, the temperature on the axis decays to T axis  ⩽ 1500 K, mainly contributed by the gas expansion and heat transfer mechanisms. After 100 µs, the dielectric strength of the gap recovers to above half of the cold breakdown voltage due to the temperature decay in the channel. Both experimental and numerical investigations indicate that supercritical fluid is a good insulating medium that has a proved high breakdown voltage and fast recovery speed. (paper)

Theoretical and Experimental Studies of New Polymer-Metal High-Dielectric Constant Nanocomposites

Science.gov (United States)

Ginzburg, Valeriy; Elwell, Michael; Myers, Kyle; Cieslinski, Robert; Malowinski, Sarah; Bernius, Mark

2006-03-01

High-dielectric-constant (high-K) gate materials are important for the needs of electronics industry. Most polymers have dielectric constant in the range 2 materials with K > 10 it is necessary to combine polymers with ceramic or metal nanoparticles. Several formulations based on functionalized Au-nanoparticles (R ˜ 5 -— 10 nm) and PMMA matrix polymer are prepared. Nanocomposite films are subsequently cast from solution. We study the morphology of those nanocomposites using theoretical (Self-Consistent Mean-Field Theory [SCMFT]) and experimental (Transmission Electron Microscopy [TEM]) techniques. Good qualitative agreement between theory and experiment is found. The study validates the utility of SCMFT as screening tool for the preparation of stable (or at least metastable) polymer/nanoparticle mixtures.

Hysteresis behaviour of low-voltage organic field-effect transistors employing high dielectric constant polymer gate dielectrics

International Nuclear Information System (INIS)

Kim, Se Hyun; Yun, Won Min; Kwon, Oh-Kwan; Hong, Kipyo; Yang, Chanwoo; Park, Chan Eon; Choi, Woon-Seop

2010-01-01

Here, we report on the fabrication of low-voltage-operating pentacene-based organic field-effect transistors (OFETs) that utilize crosslinked cyanoethylated poly(vinyl alcohol) (CR-V) gate dielectrics. The crosslinked CR-V-based OFET could be operated successfully at low voltages (below 4 V), but abnormal behaviour during device operation, such as uncertainty in the field-effect mobility (μ) and hysteresis, was induced by the slow polarization of moieties embedded in the gate dielectric (e.g. polar functionalities, ionic impurities, water and solvent molecules). In an effort to improve the stability of OFET operation, we measured the dependence of μ and hysteresis on dielectric thickness, CR-V crosslinking conditions and sweep rate of the gate bias. The influence of the CR-V surface properties on μ, hysteresis, and the structural and morphological features of the pentacene layer grown on the gate dielectric was characterized and compared with the properties of pentacene grown on a polystyrene surface.

Improved dielectric constant and breakdown strength of γ-phase dominant super toughened polyvinylidene fluoride/TiO2 nanocomposite film: an excellent material for energy storage applications and piezoelectric throughput

Science.gov (United States)

Mehebub Alam, Md; Ghosh, Sujoy Kumar; Sarkar, Debabrata; Sen, Shrabanee; Mandal, Dipankar

2017-01-01

Titanium dioxide (TiO2) nanoparticles (NPs) embedded γ-phase containing polyvinylidene fluoride (PVDF) nanocomposite (PNC) film turns to an excellent material for energy storage application due to an increased dielectric constant (32 at 1 kHz), enhanced electric breakdown strength (400 MV m-1). It also exhibits a high energy density of 4 J cm-3 which is 25 times higher than that of virgin PVDF. 98% of the electroactive γ-phase has been acheived by the incorporation of TiO2 NPs and the resulting PNC behaves like a super-toughened material due to a dramatic improvement (more than 80%) in the tensile strength. Owing to their electroactive nature and extraordinary mechanical properties, PNC films have a strong ability to fabricate the piezoelectric nanogenerators (PNGs) that have recently been an area of focus regarding mechanical energy harvesting. The feasibility of piezoelectric voltage generation from PNGs is demostrated under the rotating fan that also promises further utility such as rotational speed (RPM) determination.

Numerical simulation of the leaky dielectric microdroplet generation in electric fields

Science.gov (United States)

Kamali, Reza; Manshadi, Mohammad Karim Dehghan

2016-07-01

Microdroplet generation has a vast range of applications in the chemical, biomedical, and biological sciences. Several devices are applied to produce microdroplets, such as Co-flow, T-junction and Flow-focusing. The important point in the producing process is controlling the separated fluid volume in these devices. On the other hand, a large number of liquids, especially aqueous one, are influenced by electric or magnetic fields. As a consequence, an electric field could be used in order to affect the separated fluid volume. In this study, effects of an electric field on the microdroplet generation in a Co-flow device are investigated numerically. Furthermore, effects of some electrical properties such as permittivity on the separating process of microdroplets are studied. Leaky dielectric and perfect dielectric models are used in this investigation. According to the results, in the microdroplet generating process, leaky dielectric fluids show different behaviors, when an electric field is applied to the device. In other words, in a constant electric field strength, the volume of generated microdroplets can increase or decrease, in comparison with the condition without the electric field. However, for perfect dielectric fluids, droplet volume always decreases with increasing the electric field strength. In order to validate the numerical method of this study, deformation of a leaky dielectric droplet in an electric field is investigated. Results are compared with Taylor theoretical model.

Vapor Phase Polymerization Deposition Conducting Polymer Nanocomposites on Porous Dielectric Surface as High Performance Electrode Materials

Institute of Scientific and Technical Information of China (English)

Ya jie Yang; Luning Zhang; Shibin Li; Zhiming Wang; Jianhua Xu; Wenyao Yang; Yadong Jiang

2013-01-01

We report chemical vapor phase polymerization（VPP） deposition of poly（3,4-ethylenedioxythiophene）（PEDOT） and PEDOT/graphene on porous dielectric tantalum pentoxide（Ta2O5） surface as cathode films for solid tantalum electrolyte capacitors. The modified oxidant/oxidant-graphene films were first deposited on Ta2O5 by dip-coating, and VPP process was subsequently utilized to transfer oxidant/oxidant-graphene into PEDOT/PEDOT-graphene films. The SEM images showed PEDOT/PEDOT-graphene films was successfully constructed on porous Ta2O5 surface through VPP deposition, and a solid tantalum electrolyte capacitor with conducting polymer-graphene nano-composites as cathode films was constructed. The high conductivity nature of PEDOT-graphene leads to resistance decrease of cathode films and lower contact resistance between PEDOT/graphene and carbon paste. This nano-composite cathode films based capacitor showed ultralow equivalent series resistance（ESR） ca. 12 m? and exhibited excellent capacitance-frequency performance, which can keep 82% of initial capacitance at 500 KHz. The investigation on leakage current revealed that the device encapsulation process has no influence on capacitor leakage current, indicating the excellent mechanical strength of PEDOT/PEDOT-gaphene films. This high conductivity and mechanical strength of graphene-based polymer films shows promising future for electrode materials such as capacitors, organic solar cells and electrochemical energy storage devices.

Structural, Optical, and Dielectric Investigations of the Relaxor PLZT 9,75/65/35 Ceramics Irradiated by High-Current Pulsed Electron Beam

CERN Document Server

Efimov, V V; Kalmikov, A V; Klevtsova, E A; Minashkin, V F; Novikova, N N; Sikolenko, V V; Skripnik, A V; Sternberg, A; Tiutiunnikov, S I; Yakovlev, V A

2002-01-01

First time comprehensive study of high-current pulsed electron irradiation effects on the structural, optical and dielectric properties of relaxor (Pb_{(1-x)}La^{x}(Zr_{0.65}Ti_{0.35})_{1-x/4}O_{3} ceramics with x=9.75% has been provided. The electron beam had the following parameters: energy E_{e}=250 keV, current density J_{e}=1000 A/cm^{2}, pulse duration tau = 300 ns, density 10^{15} electrons/cm^{2} per pulse. Infrared reflectivity spectra in the region of 100-2000 cm^{-1} were obtained in virgin, irradiated by 1500 pulses and annealed up to t=500^{circ}C ceramics. The reconstruction of perovskite ABO_{3} structure in irradiated samples has been studied by complex use of X-ray and neutron scattering and IR spectroscopy techniques revealing the changes in transverse and longitudinal phonon modes, oscillators strength and damping of modes. Radiation effects on temperature behaviour of dielectric permittivity in the region of phase transition were studied. The possible mechanisms of pulsed electron irradiat...

Relationship of Cure Temperature to Mechanical, Physical, and Dielectric Performance of PDMS Glass Composite for Electric Motor Insulation

Science.gov (United States)

Miller, Sandi G.; Becker, Kathleen; Williams, Tiffany S.; Scheiman, Daniel A.; McCorkle, Linda S.; Heimann, Paula J.; Ring, Andrew; Woodworth, Andrew

2017-01-01

Achieving NASAs aggressive fuel burn and emission reduction for N-plus-3 aircraft will require hybrid electric propulsion system in which electric motors driven by either power generated from turbine or energy storage system will power the fan for propulsion. Motors designed for hybrid electric aircraft are expected to operate at medium to high voltages over long durations in a high altitude service environment. Such conditions have driven research toward the development of wire insulation with improved mechanical strength, thermal stability and increased breakdown voltage. The silicone class of materials has been considered for electric wire insulation due to its inherent thermal stability, dielectric strength and mechanical integrity. This paper evaluates the dependence of these properties on the cure conditions of a polydimethyl-siloxane (PDMS) elastomer; where both cure temperature and base-to-catalyst ratio were varied. The PDMS elastomer was evaluated as a bulk material and an impregnation matrix within a lightweight glass veil support. The E-glass support was selected for mechanical stiffness and dielectric strength. This work has shown a correlation between cure conditions and material physical properties. Tensile strength increased with cure temperature whereas breakdown voltage tended to be independent of process variations. The results will be used to direct material formulation based on specific insulation requirements.

Radiation Characteristics Enhancement of Dielectric Resonator Antenna Using Solid/Discrete Dielectric Lenses

Directory of Open Access Journals (Sweden)

H. A. E. Malhat

2015-02-01

Full Text Available The radiation characteristics of the dielectric resonator antennas (DRA is enhanced using different types of solid and discrete dielectric lenses. One of these approaches is by loading the DRA with planar superstrate, spherical lens, or by discrete lens (transmitarray. The dimensions and dielectric constant of each lens are optimized to maximize the gain of the DRA. A comparison between the radiations characteristics of the DRA loaded with different lenses are introduced. The design of the dielectric transmitarray depends on optimizing the heights of the dielectric material of the unit cell. The optimized transmitarray achieves 7 dBi extra gain over the single DRA with preserving the circular polarization. The proposed antenna is suitable for various applications that need high gain and focused antenna beam.

Fabrication of Nonvolatile Memory Effects in High-k Dielectric Thin Films Using Electron Irradiation

International Nuclear Information System (INIS)

Park, Chanrock; Cho, Daehee; Kim, Jeongeun; Hwang, Jinha

2010-01-01

Electron Irradiation can be applied towards nano-floating gate memories which are recognized as one of the next-generation nonvolatile memory semiconductors. NFGMs can overcome the preexisting limitations encountered in Dynamic Random Access Memories and Flash memories with the excellent advantages, i. e. high-density information storage, high response speed, high compactness, etc. The traditional nano-floating gate memories are fabricated through multi-layered nano structures of the dissimilar materials where the charge-trapping portions are sandwiched into the high-k dielectrics. However, this work reports the unique nonvolatile responses in single-layered high-k dielectric thin films if irradiated with highly accelerated electron beams. The implications of the electron irradiation will be discussed towards high-performance nano-floating gate memories

Microscopic theoretical study of frequency dependent dielectric constant of heavy fermion systems

Science.gov (United States)

Shadangi, Keshab Chandra; Rout, G. C.

2017-05-01

The dielectric polarization and the dielectric constant plays a vital role in the deciding the properties of the Heavy Fermion Systems. In the present communication we consider the periodic Anderson's Model which consists of conduction electron kinetic energy, localized f-electron kinetic energy and the hybridization between the conduction and localized electrons, besides the Coulomb correlation energy. We calculate dielectric polarization which involves two particle Green's functions which are calculated by using Zubarev's Green's function technique. Using the equations of motion of the fermion electron operators. Finally, the temperature and frequency dependent dielectric constant is calculated from the dielectric polarization function. The charge susceptibility and dielectric constant are computed numerically for different physical parameters like the position (Ef) of the f-electron level with respect to fermi level, the strength of the hybridization (V) between the conduction and localized f-electrons, Coulomb correlation potential temperature and optical phonon wave vector (q). The results will be discussed in a reference to the experimental observations of the dielectric constants.

Dynamics of dielectric barrier discharges in different arrangements

International Nuclear Information System (INIS)

Gibalov, Valentin I; Pietsch, Gerhard J

2012-01-01

Based on experimental results, numerical investigations of dielectric barrier discharges (DBDs) have been performed in three basic configurations: in the volume, coplanar and surface discharge arrangements. It is shown that the DBD dynamics is the same in all arrangements and it is determined by the development of a few principal constituents, i.e. cathode- and anode-directed streamers, discharge channel, cathode layer and surface charges. It is found that the anode- and cathode-directed streamers appear with a highly conductive channel in between. The interaction of the streamers with conductive and dielectric surfaces determines the filamentary or homogeneous appearance of the discharge and its properties. The cathode-directed streamer is a self-sustaining phenomenon, which moves in a gas gap or along an electrode driven by a positive loop-back between photoemission and electron multiplication. The anode-directed streamer plays a subsidiary role. Depending on the kind of gas (electronegative or electropositive) and/or the degree of development of the cathode-directed streamer, the field strength in the conductive channels changes significantly. When the cathode-directed streamer touches the electrode surface, a cathode layer appears with parameters close to those of normal glow discharges. In volume discharge arrangements the movement of the streamers results in the appearance of Lichtenberg figures on dielectric surfaces. (paper)

Ab-initio study of the dielectric response of high-permittivity perovskites for energy storage

International Nuclear Information System (INIS)

Do-Amaral-De-Andrade-Sophia, Gustavo

2014-01-01

Many of materials based on transition metals have a wide range of applications, such as the storage of energy, due to their peculiar properties (high-dielectric constants, ferro-electricity,...). The knowledge of their bulk properties is essential in designing targeted devices with high performance. For instance, ABO 3 perovskites are peculiarly interesting for their atomic structural flexibility, allowing high number of atoms substitution and giving them specific chemical and electrical properties compared to the pure compounds. In this context, first principles calculations can be useful to understand the structural and electronic properties of these materials. The pressure-induced giant dielectric anomaly of ABO 3 perovskites has been investigated at the ab initio level. Its mechanism has been analyzed in terms of thermodynamic phase stability, structural and phonon contributions and Born effective charges. It is shown that the IR-active soft phonon is responsible for the anomaly. This mode always involves a displacement and a deformation of the oxygen octahedra, while the roles of A and B ions vary among the materials and between high- and low-pressure phase transitions. A sharp increase in the phonon amplitude near the phase transition gives rise to the dielectric anomaly. The use of hybrid functionals is required for agreement with experimental data. The calculations show that the dielectric anomaly in the pressure-induced phase transitions of these perovskites is a property of the bulk material. (author)

Race for novel high-index all-dielectric and hybrid metal-dielectric nanophotonic materials: Pit-stop optical tests

Science.gov (United States)

Kudryashov, S. I.; Saraeva, I. N.; Ivanova, A. K.; Kudryavtseva, A. D.; Tchiernega, N. V.; Ionin, A. A.; Kuchmizhak, A. A.; Zayarny, D. A.

2017-09-01

Magnetic dipolar Mie-resonance of nanodiamonds supports their highly-efficient stimulated low-frequency Raman scattering via nanosecond laser excitation of their fundamental breathing mode, with strong additional plasmonic enhancement of the Raman conversion efficiency upon ablative capping of the resonant nanodiamond core by a silver nanoshell with a broad overlapping electrical dipolar Mie-resonance. Also, crystalline selenium nanoparticles, exhibiting the high refractive index in the visible/near-IR ranges, were demonstrated as promising all-dielectric sensing building nanoblocks in nanophotonics.

Manipulation of dielectric Rayleigh particles using highly focused elliptically polarized vector fields.

Science.gov (United States)

Gu, Bing; Xu, Danfeng; Rui, Guanghao; Lian, Meng; Cui, Yiping; Zhan, Qiwen

2015-09-20

Generation of vectorial optical fields with arbitrary polarization distribution is of great interest in areas where exotic optical fields are desired. In this work, we experimentally demonstrate the versatile generation of linearly polarized vector fields, elliptically polarized vector fields, and circularly polarized vortex beams through introducing attenuators in a common-path interferometer. By means of Richards-Wolf vectorial diffraction method, the characteristics of the highly focused elliptically polarized vector fields are studied. The optical force and torque on a dielectric Rayleigh particle produced by these tightly focused vector fields are calculated and exploited for the stable trapping of dielectric Rayleigh particles. It is shown that the additional degree of freedom provided by the elliptically polarized vector field allows one to control the spatial structure of polarization, to engineer the focusing field, and to tailor the optical force and torque on a dielectric Rayleigh particle.

Development of LTCC Materials with High Mechanical Strength

International Nuclear Information System (INIS)

Kawai, Shinya; Nishiura, Sousuke; Terashi, Yoshitake; Furuse, Tatsuji

2011-01-01

We have developed LTCC materials suitable for substrates of RF modules used in mobile phone. LTCC can provide excellent solutions to requirements of RF modules, such as down-sizing, embedded elements and high performance. It is also important that LTCC material has high mechanical strength to reduce risk of fracture by mechanical impact. We have established a method of material design for high mechanical strength. There are two successive steps in the concept to achieve high mechanical strength. The first step is to improve mechanical strength by increasing the Young's modulus, and the second step is either further improvement through the Young's modulus or enhancement of the fracture energy. The developed material, so called high-strength LTCC, thus possesses mechanical strength of 400MPa, which is twice as strong as conventional material whose mechanical strength is approximately 200MPa in typical. As a result, high-strength LTCC shows an excellent mechanical reliability, against the drop impact test for example. The paper presents material design and properties of LTCC materials.

Study on creep of fiber reinforced ultra-high strength concrete based on strength

Science.gov (United States)

Peng, Wenjun; Wang, Tao

2018-04-01

To complement the creep performance of ultra-high strength concrete, the long creep process of fiber reinforced concrete was studied in this paper. The long-term creep process and regularity of ultra-high strength concrete with 0.5% PVA fiber under the same axial compression were analyzed by using concrete strength (C80/C100/C120) as a variable. The results show that the creep coefficient of ultra-high strength concrete decreases with the increase of concrete strength. Compared with ACI209R (92), GL2000 models, it is found that the predicted value of ACI209R (92) are close to the experimental value, and the creep prediction model suitable for this experiment is proposed based on ACI209R (92).

Ceramic-polymer nanocomposites with increased dielectric permittivity and low dielectric loss

International Nuclear Information System (INIS)

Bhardwaj, Sumit; Paul, Joginder; Raina, K. K.; Thakur, N. S.; Kumar, Ravi

2014-01-01

The use of lead free materials in device fabrication is very essential from environmental point of view. We have synthesized the lead free ferroelectric polymer nanocomposite films with increased dielectric properties. Lead free bismuth titanate has been used as active ceramic nanofillers having crystallite size 24nm and PVDF as the polymer matrix. Ferroelectric β-phase of the polymer composite films was confirmed by X-ray diffraction pattern. Mapping data confirms the homogeneous dispersion of ceramic particles into the polymer matrix. Frequency dependent dielectric constant increases up to 43.4 at 100Hz, whereas dielectric loss decreases with 7 wt% bismuth titanate loading. This high dielectric constant lead free ferroelectric polymer films can be used for energy density applications

Trends of microwave dielectric materials for antenna application

International Nuclear Information System (INIS)

Sulong, T. A. T.; Osman, R. A. M.; Idris, M. S.

2016-01-01

Rapid development of a modern microwave communication system requires a high quality microwave dielectric ceramic material to be used as mobile and satellite communication. High permittivity of dielectric ceramics leads to fabrication of compact device for electronic components. Dielectric ceramics which used for microwave applications required three important parameters such as high or appropriate permittivity (ε_r), high quality factor (Q _f ≥ 5000 GH z) and good temperature coefficient of resonant frequency (τ_f). This paper review of various dielectric ceramic materials used as microwave dielectric materials and related parameters for antenna applications.

Preparation and Dielectric Properties of SiC/LSR Nanocomposites for Insulation of High Voltage Direct Current Cable Accessories.

Science.gov (United States)

Shang, Nanqiang; Chen, Qingguo; Wei, Xinzhe

2018-03-08

The conductivity mismatch in the composite insulation of high voltage direct current (HVDC) cable accessories causes electric field distribution distortion and even insulation breakdown. Therefore, a liquid silicone rubber (LSR) filled with SiC nanoparticles is prepared for the insulation of cable accessories. The micro-morphology of the SiC/LSR nanocomposites is observed by scanning electron microscopy, and their trap parameters are characterized using thermal stimulated current (TSC) tests. Moreover, the dielectric properties of SiC/LSR nanocomposites with different SiC concentrations are tested. The results show that the 3 wt % SiC/LSR sample has the best nonlinear conductivity, more than one order of magnitude higher than that of pure LSR with improved temperature and nonlinear conductivity coefficients. The relative permittivity increased 0.2 and dielectric loss factor increased 0.003, while its breakdown strength decreased 5 kV/mm compared to those of pure LSR. Moreover, the TSC results indicate the introduction of SiC nanoparticles reduced the trap level and trap density. Furthermore, the SiC nanoparticles filling significantly increased the sensitivity of LSR to electric field stress and temperature changes, enhancing the conductivity and electric field distribution within the HVDC cable accessories, thus improving the reliability of the HVDC cable accessories.

Comparison of three dielectric barrier discharges regarding their physical characteristics and influence on the adhesion properties on maple, high density fiberboards and wood plastic composite

International Nuclear Information System (INIS)

Peters, F; Wieneke, S; Ohms, G; Viöl, W; Hünnekens, B; Militz, H

2017-01-01

In this study, three different dielectric barrier discharges, based on the same setup and run with the same power supply, are characterized by emission spectroscopy with regards to the reduced electrical field strength, and the rotational, vibrational and electron temperature. To compare discharges common for the treatment on wood, a coplanar surface barrier discharge, a direct dielectric barrier discharge and a jet system/remote plasma are chosen. To minimize influences due to the setups or power, the discharges are realized with the same electrodes and power supply and normalized to the same power. To evaluate the efficiency of the different discharges and the influence on treated materials, the surface free energy is determined on a maple wood, high density fiberboard and wood plastic composite. The influence is measured depending on the treatment time, with the highest impact in the time of 5 s. (paper)

Comparison of three dielectric barrier discharges regarding their physical characteristics and influence on the adhesion properties on maple, high density fiberboards and wood plastic composite

Science.gov (United States)

Peters, F.; Hünnekens, B.; Wieneke, S.; Militz, H.; Ohms, G.; Viöl, W.

2017-11-01

In this study, three different dielectric barrier discharges, based on the same setup and run with the same power supply, are characterized by emission spectroscopy with regards to the reduced electrical field strength, and the rotational, vibrational and electron temperature. To compare discharges common for the treatment on wood, a coplanar surface barrier discharge, a direct dielectric barrier discharge and a jet system/remote plasma are chosen. To minimize influences due to the setups or power, the discharges are realized with the same electrodes and power supply and normalized to the same power. To evaluate the efficiency of the different discharges and the influence on treated materials, the surface free energy is determined on a maple wood, high density fiberboard and wood plastic composite. The influence is measured depending on the treatment time, with the highest impact in the time of 5 s.

Off Axis Growth of Strontium Titanate Films with High Dielectric Constant Tuning and Low Loss

Science.gov (United States)

Kampangkeaw, Satreerat

2002-03-01

Using off-axis pulsed laser deposition, we have grown strontium titanate (STO) films on neodymium gallate (NGO) and lanthanum aluminate (LAO) substrates. We measured the film dielectric constant and loss tangent as a function of temperature in the 10kHz to 1 MHz frequency range. We found that the loss is less than 0.01 We also obtained a figure of merit from the relative variation of the dielectric constant divided by the loss tangent. The obtained figured of merit at 35K and 1MHz is about 1000 comparable to bulk values. The dielectric constant of these films can be changed by a factor of 4-8 in the presence of a DC electric field up to 5V/μm. The films show significant variations of dielectric properties grown on different substrates at different locations respect to the axis of the plume. The STO films on LAO having high dielectric constant and dielectric tuning were grown in region near the center of the plume. On the other hand, STO on NGO shows this effect only on the films grown far from the plume axis.

Review on fatigue behavior of high-strength concrete after high temperature

Science.gov (United States)

Zhao, Dongfu; Jia, Penghe; Gao, Haijing

2017-06-01

The fatigue of high-strength concrete after high temperature has begun to attract attention. But so far the researches work about the fatigue of high-strength concrete after high temperature have not been reported. This article based on a large number of literature. The research work about the fatigue of high-strength concrete after high temperature are reviewed, analysed and expected, which can provide some reference for the experimental study of fatigue damage analysis.

Optimized extraction conditions from high power-ECRIS by dedicated dielectric structures

International Nuclear Information System (INIS)

Schachter, L.; Dobrescu, S.; Stiebing, K.E.

2012-01-01

The MD-method of enhancing the ion output from ECR ion sources is well established and basically works via two mechanisms, the regenerative injection of cold electrons from an emissive dielectric layer on the plasma chamber walls and via the cutting of compensating wall currents, which results in an improved ion extraction from the plasma. As this extraction from the plasma becomes a more and more challenging issue for modern ECRIS installations with high microwave power input, a series of experiments was carried out at the 14 GHz ECRIS of the Institut fuer Kernphysik in Frankfurt/Main, Germany (IKF). In contrast to our earlier work, in these experiments emphasis was put on the second of the above mechanisms namely to influence the sheath potential at the extraction by structures with special dielectric properties. Two different types of dielectric structures, Tantalum-oxide and Aluminium oxide (the latter also being used for the MD-method) with dramatically different electrical properties were mounted on the extraction electrode of the IKF-ECRIS, facing the plasma. For both structures an increase of the extracted ion beam currents for middle and high charge states by 60-80 % was observed. The method can also be applied to other ECR ion sources for increasing the extracted ion beam performances. The paper is followed by the slides of the presentation. (authors)

Dielectric Properties of PE/Clay Nanocomposites

Directory of Open Access Journals (Sweden)

E. David

2013-01-01

Full Text Available Polyethylene/nanoclay specimens containing from 0 to 5% nanoclays were prepared from a commercially available premixed PE/nanoclay masterbatch containing 50% wt of nanoclay. The masterbatch was diluted to the desired concentration by adding PE along with various amounts of compatibilizer in order to achieve the best possible dispersion of the nanoclay platelets. The dielectric response of the compounded samples was investigated using a combination of time and frequency-domain spectroscopy in order to cover a wide frequency window. Both techniques were in good agreement when the time-domain data was transformed into frequency-domain data. Despite their low concentration, the addition of the dispersed nanoclays led to a significant alteration of the material dielectric response in the form of the appearance of various interfacial relaxation processes and an increase of charge carrier transport within the insulation material. Moreover, an onset of nonlinear charge transport process was observed at moderate fields for specimens containing a relatively low level of nanoclays. The high-field breakdown strength was shown to have been improved by the incorporation of the nanoparticles, particularly when the exfoliation was enhanced by the use of a maleic anhydride grafted polyethylene compatibilizer.

Trends of microwave dielectric materials for antenna application

Energy Technology Data Exchange (ETDEWEB)

Sulong, T. A. T., E-mail: tuanamirahtuansulong@gmail.com; Osman, R. A. M., E-mail: rozana@unimap.edu.my [School of Microelectronic Engineering, Universiti Malaysia Perlis, Pauh Putra Campus, 02600 Arau, Perlis (Malaysia); Idris, M. S., E-mail: sobri@unimap.edu.my [Sustainable Engineering Research Cluster, School of Material Engineering, Universiti Malaysia Perlis, Blok B, Taman Pertiwi Indah, Seriab, 01000 Kangar, Perlis (Malaysia)

2016-07-19

Rapid development of a modern microwave communication system requires a high quality microwave dielectric ceramic material to be used as mobile and satellite communication. High permittivity of dielectric ceramics leads to fabrication of compact device for electronic components. Dielectric ceramics which used for microwave applications required three important parameters such as high or appropriate permittivity (ε{sub r}), high quality factor (Q {sub f} ≥ 5000 GH z) and good temperature coefficient of resonant frequency (τ{sub f}). This paper review of various dielectric ceramic materials used as microwave dielectric materials and related parameters for antenna applications.

High temperature dielectric function of silicon, germanium and GaN

Energy Technology Data Exchange (ETDEWEB)

Leyer, Martin; Pristovsek, Markus; Kneissl, Michael [Technische Universitaet Berlin (Germany). Institut fuer Festkoerperphysik

2010-07-01

In the last few years accurate values for the optical properties of silicon, germanium and GaN at high temperatures have become important as a reference for in-situ analysis, e.g. reflectometry. Precise temperature dependent dielectric measurements are necessary for the growth of GaInP/GaInAs/Ge triple-junction solar cells and the hetero epitaxy of GaN on silicon and sapphire. We performed spectroscopic ellipsometry (SE) measurements of the dielectric function of silicon, germanium and GaN between 1.5 eV and 6.5 eV in the temperature range from 300 K to 1300 K. The Samples were deoxidized chemically or by heating. High resolution SE spectra were taken every 50 K while cooling down to room temperature. The temperature dependence of the critical energies is compared to literature. Measurements for germanium showed a shift of the E{sub 2} critical point of {proportional_to}0.1 eV toward lower energies. The reason for this behavior is a non-negligible oxide layer on the samples in the literature.

Tungsten trioxide as high-{kappa} gate dielectric for highly transparent and temperature-stable zinc-oxide-based thin-film transistors

Energy Technology Data Exchange (ETDEWEB)

Lorenz, Michael; Wenckstern, Holger von; Grundmann, Marius [Universitaet Leipzig, Fakultaet fuer Physik und Geowissenschaften, Institut fuer Experimentelle Physik II, Linnestr. 5, 04103 Leipzig (Germany)

2012-07-01

We demonstrate metal-insulator-semiconductor field-effect transistors with high-{kappa}, room-temperature deposited, highly transparent tungsten trioxide (WO{sub 3}) as gate dielectric. The channel material consists of a zinc oxide (ZnO) thin-film. The transmittance and resistivity of WO{sub 3} films was tuned in order to obtain a highly transparent and insulating WO{sub 3} dielectric. The devices were processed by standard photolithography using lift-off technique. On top of the WO{sub 3} dielectric a highly transparent and conductive oxide consisting of ZnO: Al 3% wt. was deposited. The gate structure of the devices exhibits an average transmittance in the visible spectral range of 86%. The on/off-current ratio is larger than 10{sup 8} with off- and gate leakage-currents below 3 x 10{sup -8} A/cm{sup 2}. Due to the high relative permittivity of {epsilon}{sub r} {approx} 70, a gate voltage sweep of only 2 V is necessary to turn the transistor on and off with a minimum subthreshold swing of 80 mV/decade. The channel mobility of the transistors equals the Hall-effect mobility with a value of 5 cm{sup 2}/Vs. It is furthermore shown, that the devices are stable up to operating temperatures of at least 150 C.

Improved Gate Dielectric Deposition and Enhanced Electrical Stability for Single-Layer MoS2 MOSFET with an AlN Interfacial Layer.

Science.gov (United States)

Qian, Qingkai; Li, Baikui; Hua, Mengyuan; Zhang, Zhaofu; Lan, Feifei; Xu, Yongkuan; Yan, Ruyue; Chen, Kevin J

2016-06-09

Transistors based on MoS2 and other TMDs have been widely studied. The dangling-bond free surface of MoS2 has made the deposition of high-quality high-k dielectrics on MoS2 a challenge. The resulted transistors often suffer from the threshold voltage instability induced by the high density traps near MoS2/dielectric interface or inside the gate dielectric, which is detrimental for the practical applications of MoS2 metal-oxide-semiconductor field-effect transistor (MOSFET). In this work, by using AlN deposited by plasma enhanced atomic layer deposition (PEALD) as an interfacial layer, top-gate dielectrics as thin as 6 nm for single-layer MoS2 transistors are demonstrated. The AlN interfacial layer not only promotes the conformal deposition of high-quality Al2O3 on the dangling-bond free MoS2, but also greatly enhances the electrical stability of the MoS2 transistors. Very small hysteresis (ΔVth) is observed even at large gate biases and high temperatures. The transistor also exhibits a low level of flicker noise, which clearly originates from the Hooge mobility fluctuation instead of the carrier number fluctuation. The observed superior electrical stability of MoS2 transistor is attributed to the low border trap density of the AlN interfacial layer, as well as the small gate leakage and high dielectric strength of AlN/Al2O3 dielectric stack.

DIELECTRICALLY-LOADED WAVEGUIDE AS A MICROWAVE UNDULATOR FOR HIGH BRILLANCE X-RAYS AT 45 – 90 KeV

Energy Technology Data Exchange (ETDEWEB)

Kustom, R. L.; Waldschmidt, G.; Nassiri, A.

2017-06-01

The HEM12 mode in a cylindrical, dielectrically-loaded waveguide provides E and H fields on the central axis that are significantly higher than the fields on the conducting walls. This structure, operating near the cutoff frequency of the HEM12 mode, spans a frequency range where the wavelength and phase velocity vary significantly. This property can be exploited to generate undulator action with short periods for the generation of high brightness xrays. The frequency range of interest would be from 18 to 34.5-GHz. The goal would be to generate x-rays on the fundamental mode over a range of 45 to 90-keV.The tunability would be achieved by changing the source frequency while maintaining a constant on-axis equivalent undulator field strength of 0.5-T.

Study of dielectric and piezoelectric properties of CNT reinforced PZT-PVA 0-3 composite

Science.gov (United States)

Vyas, Prince; Prajapat, Rampratap; Manmeeta, Saxena, Dhiraj

2016-05-01

Ferroelectric ceramic/polymer composites have the compliance of polymers which overcome the problems of brittleness in ceramics. By imbedding piezoelectric ceramic powder into a polymer matrix, 0-3 composites with good mechanical properties and high dielectric breakdown strength can be developed. The obtained composites of 0-3 connectivity exhibit the piezoelectric properties of ceramics and flexibility, strength and lightness of polymer. These composites can be used in vibration sensing and transducer applications specially as piezoelectric sensors. A potential way to improve piezoelectric& dielectric properties of theses composites is by inclusion of another conductive phase in these composites as reported in the literature. In present work, we prepared PZT-PVA 0-3 composites with 60% ceramic volume fraction reinforced with CNTs with volume ranging from 0 to 1.5 vol%. These CNT reinforced composites were obtained using hot press method with thickness of 200 µm having 0-3 conductivity. These composites were poled applying DC voltage. Dielectric properties of these samples were obtained in a wide frequency range (100 Hz to 1 Mhz) at room temperature. The piezoelectric properties of these composites were analyzed by measuring piezoelectric charge constants (d33). The dielectric and piezoelectric properties of these composites were studied as a function of CNT volume content. In these reinforced composites, CNTs act as a conductive filler dispersed in the matrix which in turn facilitates poling and results in an increase of the piezoelectric properties of the composite due to formation of percolation path through the composites. With a CNT content of 0.3 vol.% in PZT/PVA/CNTs, an increase of 61.3 % was observed in piezoelectric strain factors (d33). In these CNT reinforced composites, a substantial increase (approx. 67%) was also observed in dielectric constant and approximately 89% increase was observed in dielectric loss factor. Results so obtained are in the good

Dielectric nanoresonators for light manipulation

Science.gov (United States)

Yang, Zhong-Jian; Jiang, Ruibin; Zhuo, Xiaolu; Xie, Ya-Ming; Wang, Jianfang; Lin, Hai-Qing

2017-07-01

Nanostructures made of dielectric materials with high or moderate refractive indexes can support strong electric and magnetic resonances in the optical region. They can therefore function as nanoresonators. In addition to plasmonic metal nanostructures that have been widely investigated, dielectric nanoresonators provide a new type of building blocks for realizing powerful and versatile nanoscale light manipulation. In contrast to plasmonic metal nanostructures, nanoresonators made of appropriate dielectric materials are low-cost, earth-abundant and have very small or even negligible light energy losses. As a result, they will find potential applications in a number of photonic devices, especially those that require low energy losses. In this review, we describe the recent progress on the experimental and theoretical studies of dielectric nanoresonators. We start from the basic theory of the electromagnetic responses of dielectric nanoresonators and their fabrication methods. The optical properties of individual dielectric nanoresonators are then elaborated, followed by the coupling behaviors between dielectric nanoresonators, between dielectric nanoresonators and substrates, and between dielectric nanoresonators and plasmonic metal nanostructures. The applications of dielectric nanoresonators are further described. Finally, the challenges and opportunities in this field are discussed.

On high temperature strength of carbon steels

International Nuclear Information System (INIS)

Ichinose, Hiroyuki; Tamura, Manabu; Kanero, Takahiro; Ihara, Yoshihito

1977-01-01

In the steels for high temperature use, the oxidation resistance is regarded as important, but carbon steels show enough oxidation resistance to be used continuously at the temperature up to 500 deg. C if the strength is left out of consideration, and up to 450 deg. C even when the strength is taken into account. Moreover, the production is easy, the workability and weldability are good, and the price is cheap in carbon steels as compared with alloy steels. In the boilers for large thermal power stations, 0.15-0.30% C steels are used for reheater tubes, main feed water tubes, steam headers, wall water tubes, economizer tubes, bypass pipings and others, and they account for 70% of all steel materials used for the boilers of 350 MW class and 30% in 1000 MW class. The JIS standard for the carbon steels for high temperature use and the related standards in foreign countries are shown. The high temperature strength of carbon steels changes according to the trace elements, melting and heat treatment as well as the main compositions of C, Si and Mn. Al and N affect the high temperature strength largely. The characteristics of carbon steels after the heating for hours, the factors controlling the microstructure and high temperature strength, and the measures to improve the high temperature strength of carbon steels are explained. (Kako, I.)

Strength Gain Properties up to five-year age of high-strength mass concrete

International Nuclear Information System (INIS)

Mitarai, Y.; Shigenobu, M.; Hiramine, T.; Inoue, K.; Nakane, S.; Ohike, T.

1991-01-01

Genkai No.3 plant of Kyushu Electric Power Co., Inc. presently under construction is a PWR type nuclear power plant with 1180 MW power output, and a prestressed concrete containment vessel (PCCV) was adopted for the reactor. The concrete used for the construction of the PCCV is the mass concrete with the wall thickness of 1.3 m in the general parts of the cylinder, and about 2 m at buttresses. It is the high strength concrete of the specified strength 420 kgf/cm 2 . As the preliminary study for the construction using such high strength mass concrete, the examination was carried out on the strength gain property of structural concrete using full scale simulated members. The various problems in the quality control were contemplated based on the results of the examination, and were reflected to actual construction, designating 13 weeks as the age for strength control, in order to build the concrete structures with high reliability. In this report, the outline of the study on the strength gain up to 5 year age carried out in the preliminary study is discussed. The experimental method, the method of evaluating structural strength, the mixing proportion of concrete and the results are reported. (K.I.)

High-strength concrete and the design of power plant structures

International Nuclear Information System (INIS)

Puttonen, J.

1991-01-01

Based on the literature, the design of high-strength concrete structures and the suitability of high-strength concrete for the power plant structures have been studied. Concerning the behavior of structures, a basic difference between the high-strength concrete and the traditional one is that the ductility of the high-strength concrete is smaller. In the design, the non-linear stress-strain relationship of the high-strength concrete has to be taken into account. The use of the high-strength concrete is economical if the strength of the material can be utilized. In the long term, the good durability and wear resistance of the high-strength concrete increases the economy of the material. Because of the low permeability of the high-strength concrete, it is a potential material in the safety-related structures of nuclear power plants. The study discovered no particular power plant structure which would always be economical to design of high-strength concrete. However, the high-strength concrete was found to be a competitive material in general

Thermal dielectric function

International Nuclear Information System (INIS)

Moneta, M.

1999-01-01

Thermal dielectric functions ε(k,ω) for homogeneous electron gas were determined and discussed. The ground state of the gas is described by the Fermi-Dirac momentum distribution. The low and high temperature limits of ε(k,ω) were related to the Lindhard dielectric function and to ε(k, omega) derived for Boltzmann and for classical momentum distributions, respectively. (author)

Optimization of large-scale fabrication of dielectric elastomer transducers

DEFF Research Database (Denmark)

Hassouneh, Suzan Sager

Dielectric elastomers (DEs) have gained substantial ground in many different applications, such as wave energy harvesting, valves and loudspeakers. For DE technology to be commercially viable, it is necessary that any large-scale production operation is nondestructive, efficient and cheap. Danfoss......-strength laminates to perform as monolithic elements. For the front-to-back and front-to-front configurations, conductive elastomers were utilised. One approach involved adding the cheap and conductive filler, exfoliated graphite (EG) to a PDMS matrix to increase dielectric permittivity. The results showed that even...... as conductive adhesives were rejected. Dielectric properties below the percolation threshold were subsequently investigated, in order to conclude the study. In order to avoid destroying the network structure, carbon nanotubes (CNTs) were used as fillers during the preparation of the conductive elastomers...

Interface Study on Amorphous Indium Gallium Zinc Oxide Thin Film Transistors Using High-k Gate Dielectric Materials

Directory of Open Access Journals (Sweden)

Yu-Hsien Lin

2015-01-01

Full Text Available We investigated amorphous indium gallium zinc oxide (a-IGZO thin film transistors (TFTs using different high-k gate dielectric materials such as silicon nitride (Si3N4 and aluminum oxide (Al2O3 at low temperature process (<300°C and compared them with low temperature silicon dioxide (SiO2. The IGZO device with high-k gate dielectric material will expect to get high gate capacitance density to induce large amount of channel carrier and generate the higher drive current. In addition, for the integrating process of integrating IGZO device, postannealing treatment is an essential process for completing the process. The chemical reaction of the high-k/IGZO interface due to heat formation in high-k/IGZO materials results in reliability issue. We also used the voltage stress for testing the reliability for the device with different high-k gate dielectric materials and explained the interface effect by charge band diagram.

Interface Study on Amorphous Indium Gallium Zinc Oxide Thin Film Transistors Using High-k Gate Dielectric Materials

International Nuclear Information System (INIS)

Lin, Y. H.; Chou, J. C.

2015-01-01

We investigated amorphous indium gallium zinc oxide (a-IGZO) thin film transistors (TFT_s) using different high-Κ gate dielectric materials such as silicon nitride (Si_3N_4) and aluminum oxide (Al_2O_3) at low temperature process (<300 degree) and compared them with low temperature silicon dioxide (SiO_2). The IGZO device with high-Κ gate dielectric material will expect to get high gate capacitance density to induce large amount of channel carrier and generate the higher drive current. In addition, for the integrating process of integrating IGZO device, post annealing treatment is an essential process for completing the process. The chemical reaction of the high-κ/IGZO interface due to heat formation in high-Κ/IGZO materials results in reliability issue. We also used the voltage stress for testing the reliability for the device with different high-Κ gate dielectric materials and explained the interface effect by charge band diagram.

Lanthanum titanium perovskite compound: Thin film deposition and high frequency dielectric characterization

International Nuclear Information System (INIS)

Le Paven, C.; Lu, Y.; Nguyen, H.V.; Benzerga, R.; Le Gendre, L.; Rioual, S.; Benzegoutta, D.; Tessier, F.; Cheviré, F.

2014-01-01

Perovskite lanthanum titanium oxide thin films were deposited on (001) MgO, (001) LaAlO 3 and Pt(111)/TiO 2 /SiO 2 /(001)Si substrates by RF magnetron sputtering, using a La 2 Ti 2 O 7 homemade target sputtered under oxygen reactive plasma. The films deposited at 800 °C display a crystalline growth different than those reported on monoclinic ferroelectric La 2 Ti 2 O 7 films. X-ray photoelectron spectroscopy analysis shows the presence of titanium as Ti 4+ ions, with no trace of Ti 3+ , and provides a La/Ti ratio of 1.02. The depositions being performed from a La 2 Ti 2 O 7 target under oxygen rich plasma, the same composition (La 2 Ti 2 O 7 ) is proposed for the deposited films, with an unusual orthorhombic cell and Cmc2 1 space group. The films have a textured growth on MgO and Pt/Si substrates, and are epitaxially grown on LaAlO 3 substrate. The dielectric characterization displays stable values of the dielectric constant and of the losses in the frequency range [0.1–20] GHz. No variation of the dielectric constant has been observed when a DC electric field up to 250 kV/cm was applied, which does not match a classical ferroelectric behavior at high frequencies and room temperature for the proposed La 2 Ti 2 O 7 orthorhombic phase. At 10 GHz and room temperature, the dielectric constant of the obtained La 2 Ti 2 O 7 films is ε ∼ 60 and the losses are low (tanδ < 0.02). - Highlights: • Lanthanum titanium oxide films were deposited by reactive magnetron sputtering. • A La 2 Ti 2 O 7 chemical composition is proposed, with an unusual orthorhombic cell. • At 10 GHz, the dielectric losses are lower than 0.02. • No variation of the dielectric constant is observed under DC electric biasing

Comprehensive Study of Lanthanum Aluminate High-Dielectric-Constant Gate Oxides for Advanced CMOS Devices

Directory of Open Access Journals (Sweden)

Masamichi Suzuki

2012-03-01

Full Text Available A comprehensive study of the electrical and physical characteristics of Lanthanum Aluminate (LaAlO3 high-dielectric-constant gate oxides for advanced CMOS devices was performed. The most distinctive feature of LaAlO3 as compared with Hf-based high-k materials is the thermal stability at the interface with Si, which suppresses the formation of a low-permittivity Si oxide interfacial layer. Careful selection of the film deposition conditions has enabled successful deposition of an LaAlO3 gate dielectric film with an equivalent oxide thickness (EOT of 0.31 nm. Direct contact with Si has been revealed to cause significant tensile strain to the Si in the interface region. The high stability of the effective work function with respect to the annealing conditions has been demonstrated through comparison with Hf-based dielectrics. It has also been shown that the effective work function can be tuned over a wide range by controlling the La/(La + Al atomic ratio. In addition, gate-first n-MOSFETs with ultrathin EOT that use sulfur-implanted Schottky source/drain technology have been fabricated using a low-temperature process.

Thermal Conductivity and High-Frequency Dielectric Properties of Pressureless Sintered SiC-AlN Multiphase Ceramics

Directory of Open Access Journals (Sweden)

Jialin Gu

2018-06-01

Full Text Available SiC-AlN multiphase ceramics with 10 wt. %Y2O3-BaO-SiO2 additives were fabricated by pressureless sintering in a nitrogen atmosphere. The effects of SiC contents and sintering temperatures on the sinterability, microstructure, thermal conductivity and high-frequency dielectric properties were characterized. In addition to 6H-SiC and AlN, the samples also contained Y3Al5O12 and Y4Al2O9. SiC-AlN ceramics sintered with 50 wt. % SiC at 2173 K exhibited the best thermal diffusivity and thermal conductivity (26.21 mm2·s−1 and 61.02 W·m−1·K−1, respectively. The dielectric constant and dielectric loss of the sample sintered with 50 wt. % SiC and 2123 K were 33–37 and 0.4–0.5 at 12.4–18 GHz. The dielectric constant and dielectric loss of the samples decreased as the frequency of electromagnetic waves increased from 12.4–18 GHz. The dielectric thermal conductivity properties of the SiC-AlN samples are discussed.

High temperature dielectric properties of (BxNyOz thin films deposited using ion source assisted physical vapor deposition

Directory of Open Access Journals (Sweden)

N. Badi

2015-12-01

Full Text Available The dielectric integrity has been one of the major obstacle in bringing out capacitor devices with suitable performance characteristics at high temperatures. In this paper, BxNyOz dielectric films for high temperature capacitors solutions are investigated. The films were grown on silicon substrate by using ion source assisted physical vapor deposition technique. The as-grown films were characterized by SEM, XRD, and XPS. The capacitor structures were fabricated using BxNyOz as a dielectric and titanium as metal electrodes. The elaborated devices were subjected to electrical and thermal characterization. They exhibited low electrical loss and very good stability when subjected to high temperature for a prolonged period of time.

On the nature of high field charge transport in reinforced silicone dielectrics: Experiment and simulation

Energy Technology Data Exchange (ETDEWEB)

Huang, Yanhui, E-mail: huangy12@rpi.edu; Schadler, Linda S. [Department of Material Science and Engineering, Rensselaer Polytechnic Institute, 110 8th street, Troy, New York 12180 (United States)

2016-08-07

The high field charge injection and transport properties in reinforced silicone dielectrics were investigated by measuring the time-dependent space charge distribution and the current under dc conditions up to the breakdown field and were compared with the properties of other dielectric polymers. It is argued that the energy and spatial distribution of localized electronic states are crucial in determining these properties for polymer dielectrics. Tunneling to localized states likely dominates the charge injection process. A transient transport regime arises due to the relaxation of charge carriers into deep traps at the energy band tails and is successfully verified by a Monte Carlo simulation using the multiple-hopping model. The charge carrier mobility is found to be highly heterogeneous due to the non-uniform trapping. The slow moving electron packet exhibits a negative field dependent drift velocity possibly due to the spatial disorder of traps.

Development of K-Basin High-Strength Homogeneous Sludge Simulants and Correlations Between Unconfined Compressive Strength and Shear Strength

Energy Technology Data Exchange (ETDEWEB)

Onishi, Yasuo; Baer, Ellen BK; Chun, Jaehun; Yokuda, Satoru T.; Schmidt, Andrew J.; Sande, Susan; Buchmiller, William C.

2011-02-20

K-Basin sludge will be stored in the Sludge Transport and Storage Containers (STSCs) at an interim storage location on Central Plateau before being treated and packaged for disposal. During the storage period, sludge in the STSCs may consolidate/agglomerate, potentially resulting in high-shear-strength material. The Sludge Treatment Project (STP) plans to use water jets to retrieve K-Basin sludge after the interim storage. STP has identified shear strength to be a key parameter that should be bounded to verify the operability and performance of sludge retrieval systems. Determining the range of sludge shear strength is important to gain high confidence that a water-jet retrieval system can mobilize stored K-Basin sludge from the STSCs. The shear strength measurements will provide a basis for bounding sludge properties for mobilization and erosion. Thus, it is also important to develop potential simulants to investigate these phenomena. Long-term sludge storage tests conducted by Pacific Northwest National Laboratory (PNNL) show that high-uranium-content K-Basin sludge can self-cement and form a strong sludge with a bulk shear strength of up to 65 kPa. Some of this sludge has 'paste' and 'chunks' with shear strengths of approximately 3-5 kPa and 380-770 kPa, respectively. High-uranium-content sludge samples subjected to hydrothermal testing (e.g., 185 C, 10 hours) have been observed to form agglomerates with a shear strength up to 170 kPa. These high values were estimated by measured unconfined compressive strength (UCS) obtained with a pocket penetrometer. Due to its ease of use, it is anticipated that a pocket penetrometer will be used to acquire additional shear strength data from archived K-Basin sludge samples stored at the PNNL Radiochemical Processing Laboratory (RPL) hot cells. It is uncertain whether the pocket penetrometer provides accurate shear strength measurements of the material. To assess the bounding material strength and

Dielectric and thermal properties of isotactic polypropylene/hexagonal boron nitride composites for high-frequency applications

International Nuclear Information System (INIS)

Takahashi, Susumu; Imai, Yusuke; Kan, Akinori; Hotta, Yuji; Ogawa, Hirotaka

2014-01-01

Highlights: • The degree of orientation of the hBN could be controlled by the fabrication process. • The dielectric constants of composites ranged between 2.25 and 3.39. • The dielectric loss of composites was on the order of 10 −4 for all compositions. • The thermal conductivity were improved by controlling orientation of hBN. - Abstract: Dielectric composites aimed for high frequency applications were prepared by using anisotropic hexagonal boron nitride (hBN) particles as a fillers and isotactic polypropylene (iPP) as polymer matrix. Dielectric and thermal properties of the composites were studied, focusing on the filler orientation in the plate-shape specimens and filler concentration up to 40 vol%. The degree of orientation of the filler was controlled by the composite fabrication process. Hot-pressing gave relatively random orientation of the filler in the matrix, while injection molding induced a high orientation. Dielectric constant (ε r ) of the composites ranged between 2.25 and 3.39. The estimation of ε r based on the Bruggeman mixing model agreed well with the measured value. Low dielectric losses (tan δ) at microwave frequencies, on the order of 10 −4 , were obtained for all the compositions. Through-thickness thermal conductivity (k) of the hot-pressed samples showed a drastic increase with increasing the filler concentration, reaching up to 2.1 W/m K at 40 vol% of hBN. The filler concentration dependence of k was less significant for the injection molded composites. In-plane thermal expansion was almost independent on the filler orientation, while the coefficient of thermal expansion for the thickness direction of the hot-pressed sample was reduced to approximately half of the injection molded counterpart. These differences in thermal conductivity and thermal expansion are thought to arise from the difference in hBN filler orientation

Microwave dielectric study of polar liquids at 298 K

Science.gov (United States)

Maharolkar, Aruna P.; Murugkar, A.; Khirade, P. W.

2018-05-01

Present paper deals with study of microwave dielectric properties like dielectric constant, viscosity, density and refractive index for the binary mixtures of Dimethylsulphoxide (DMSO) and Methanol over the entire concentration range were measured at 298K. The experimental data further used to determine the excess properties viz. excess static dielectric constant, excess molar volume, excess viscosity& derived properties viz. molar refraction&Bruggman factor. The values of excess properties further fitted with Redlich-Kister (R-K Fit) equation to calculate the binary coefficients and standard deviation. The resulting excess parameters are used to indicate the presence of intermolecular interactions and strength of intermolecular interactions between the molecules in the binary mixtures. Excess parameters indicate structure breaking factor in the mixture predominates in the system.

Applicability of point-dipoles approximation to all-dielectric metamaterials

DEFF Research Database (Denmark)

Kuznetsova, S. M.; Andryieuski, Andrei; Lavrinenko, Andrei

2015-01-01

All-dielectric metamaterials consisting of high-dielectric inclusions in a low-dielectric matrix are considered as a low-loss alternative to resonant metal-based metamaterials. In this paper we investigate the applicability of the point electric and magnetic dipoles approximation to dielectric meta......-atoms on the example of a dielectric ring metamaterial. Despite the large electrical size of high-dielectric meta-atoms, the dipole approximation allows for accurate prediction of the metamaterials properties for the rings with diameters up to approximate to 0.8 of the lattice constant. The results provide important...... guidelines for design and optimization of all-dielectric metamaterials....

Temporal variation of dielectric properties of preserved blood

International Nuclear Information System (INIS)

Hayashi, Yoshihito; Oshige, Ikuya; Katsumoto, Yoichi; Omori, Shinji; Yasuda, Akio; Asami, Koji

2008-01-01

Rabbit blood was preserved at 277 K in Alsever's solution for 37 days, and its dielectric permittivity was monitored in a frequency range from 0.05 to 110 MHz throughout the period. The relaxation time and Cole-Cole parameter of the interfacial polarization process for erythrocytes remained nearly constant during the first 20 days and then started to increase and decrease, respectively. On the other hand, the relaxation strength and the cell volume fraction continued to decrease for 37 days, but the decrease rates of both changed discontinuously on about the 20th day. Microscope observation showed that approximately 90% of the erythrocytes were spinous echinocytes at the beginning of preservation and started to be transformed into microspherocytes around the 20th day. Therefore, dielectric spectroscopy is a sensitive tool to monitor the deterioration of preserved blood accompanied by morphological transition of erythrocytes through the temporal variation of their dielectric properties

High-strain actuator materials based on dielectric elastomers

DEFF Research Database (Denmark)

Pelrine, R.; Kornbluh, R.; Kofod, G.

2000-01-01

Dielectric elastomers are a new class of actuator materials that exhibit excellent performance. The principle of operation, as well as methods to fabricate and test these elastomers, is summarized here. The Figure is a sketch of an elastomer film (light gray) stretched on a frame (black) and patt......Dielectric elastomers are a new class of actuator materials that exhibit excellent performance. The principle of operation, as well as methods to fabricate and test these elastomers, is summarized here. The Figure is a sketch of an elastomer film (light gray) stretched on a frame (black...

Electrophoretically applied dielectrics for amorphous metal foils used in pulsed power saturable reactors

International Nuclear Information System (INIS)

Sharp, D.J.; Harjes, H.C.; Mann, G.A.

1989-01-01

Amorphous metal foil-wound inductors have been tested as ferromagnetic saturable inductive elements for pulsed-power (multi-terawatt) switching modules in the inertial confinement fusion program at Sandia National Laboratories. In simulated capacitor testing premature dielectric breakdown of thin polyethylene terephthalate film insulation in the inductor windings occurs at considerably below 2500 V. This appears to be due to inadvertant dielectric damage from micro-spikes on the amorphous foil surface. Electron micrographs and dielectric breakdown data illustrate that electrophoretically-applied dielectric coatings, deposited from organic aqueous colloid dispersions, can be used to provide insulating coatings on the foil which provide a 240% improvement (6000 V) in the breakdown strength of wound amorphous foil inductors. The theory and operation of a dedicated electrophoretic continuous coating system is described. The machine was constructed and successfully applied for dielectric coating of amorphous metal foil. Additional possible applications exist for practical dielectric coating of metallic films or foils used in various commercial wound-type capacitor structures. 7 refs., 9 figs

500 C Electronic Packaging and Dielectric Materials for High Temperature Applications

Science.gov (United States)

Chen, Liang-yu; Neudeck, Philip G.; Spry, David J.; Beheim, Glenn M.; Hunter, Gary W.

2016-01-01

High-temperature environment operable sensors and electronics are required for exploring the inner solar planets and distributed control of next generation aeronautical engines. Various silicon carbide (SiC) high temperature sensors, actuators, and electronics have been demonstrated at and above 500C. A compatible packaging system is essential for long-term testing and application of high temperature electronics and sensors. High temperature passive components are also necessary for high temperature electronic systems. This talk will discuss ceramic packaging systems developed for high temperature electronics, and related testing results of SiC circuits at 500C and silicon-on-insulator (SOI) integrated circuits at temperatures beyond commercial limit facilitated by these high temperature packaging technologies. Dielectric materials for high temperature multilayers capacitors will also be discussed. High-temperature environment operable sensors and electronics are required for probing the inner solar planets and distributed control of next generation aeronautical engines. Various silicon carbide (SiC) high temperature sensors, actuators, and electronics have been demonstrated at and above 500C. A compatible packaging system is essential for long-term testing and eventual applications of high temperature electronics and sensors. High temperature passive components are also necessary for high temperature electronic systems. This talk will discuss ceramic packaging systems developed for high electronics and related testing results of SiC circuits at 500C and silicon-on-insulator (SOI) integrated circuits at temperatures beyond commercial limit facilitated by high temperature packaging technologies. Dielectric materials for high temperature multilayers capacitors will also be discussed.

On the dielectric strengths of atmospheric plasma sprayed Al2O3 ,Y2O3 , ZrO2 - 7% Y2O3 and (Ba,Sr)TiO3 coatings

Czech Academy of Sciences Publication Activity Database

Kotlan, Jiří; Seshadri, R.C.; Sampath, S.; Ctibor, Pavel; Pala, Zdeněk; Mušálek, Radek

2015-01-01

Roč. 41, č. 9 (2015), s. 11169-11176 ISSN 0272-8842 R&D Projects: GA ČR GB14-36566G Institutional support: RVO:61389021 Keywords : X-ray methods * Grain size * Electrical properties * Insulators * Dielectric strength Subject RIV: JH - Ceramics, Fire-Resistant Materials and Glass Impact factor: 2.758, year: 2015 http://www.sciencedirect.com/science/article/pii/S0272884215009955#

Towards the accurate electronic structure descriptions of typical high-constant dielectrics

Science.gov (United States)

Jiang, Ting-Ting; Sun, Qing-Qing; Li, Ye; Guo, Jiao-Jiao; Zhou, Peng; Ding, Shi-Jin; Zhang, David Wei

2011-05-01

High-constant dielectrics have gained considerable attention due to their wide applications in advanced devices, such as gate oxides in metal-oxide-semiconductor devices and insulators in high-density metal-insulator-metal capacitors. However, the theoretical investigations of these materials cannot fulfil the requirement of experimental development, especially the requirement for the accurate description of band structures. We performed first-principles calculations based on the hybrid density functionals theory to investigate several typical high-k dielectrics such as Al2O3, HfO2, ZrSiO4, HfSiO4, La2O3 and ZrO2. The band structures of these materials are well described within the framework of hybrid density functionals theory. The band gaps of Al2O3, HfO2, ZrSiO4, HfSiO4, La2O3 and ZrO2are calculated to be 8.0 eV, 5.6 eV, 6.2 eV, 7.1 eV, 5.3 eV and 5.0 eV, respectively, which are very close to the experimental values and far more accurate than those obtained by the traditional generalized gradient approximation method.

Dielectric material options for integrated capacitors

NARCIS (Netherlands)

Ruhl, G.; Lehnert, W.; Lukosius, M.; Wenger, C.; Baristiran Kaynak, C.; Blomberg, T.; Haukka, S.; Baumann, P.K.; Besling, W.F.A.; Roest, A.L.; Riou, B.; Lhostis, S.; Halimaou, A.; Roozeboom, F.; Langereis, E.; Kessels, W.M.M.; Zauner, A.; Rushworth, S.A.

2014-01-01

Future MIM capacitor generations will require significantly increased specific capacitances by utilization of high-k dielectric materials. In order to achieve high capacitance per chip area, these dielectrics have to be deposited in three-dimensional capacitor structures by ALD or AVD (atomic vapor

Dielectric properties of the ITER TFMC insulation after low temperature reactor irradiation

International Nuclear Information System (INIS)

Humer, K.; Weber, H.W.; Hastik, R.; Hauser, H.; Gerstenberg, H.

2001-01-01

The insulation system for the Toroidal Field Model Coil of ITER is a fiber reinforced plastic (FRP) laminate, which consists of a combined Kapton/R-glass-fiber reinforcement tape, vacuum-impregnated with an epoxy DGEBA system. Pure disk shaped laminates, disk shaped FRP/stainless-steel sandwiches, and conductor insulation prototypes were irradiated at 5 K in a fission reactor up to a fast neutron fluence of 10 22 m -2 (E>0.1MeV) to investigate the radiation induced degradation of the dielectric strength of the insulation system. After warm-up to room temperature, swelling, weight loss, and the breakdown strength were measured at 77 K. The sandwich swells by 4% at a fluence of 5x10 21 m -2 and by 9% at 1x10 22 m -2 . The weight loss of the FRP is 2% at 1x10 22 m -2 . The dielectric strength remained unchanged over the whole dose range. (author)

Dielectric relaxation in Yb-doped SrZrO3

International Nuclear Information System (INIS)

Kamishima, O; Abe, Y; Ishii, T; Kawamura, J; Hattori, T

2004-01-01

The dielectric constant of the proton conductor SrZr 1-x Yb x O 3 (x 0-0.1) was measured as a function of temperature and frequency. Two well-defined relaxation peaks were observed in SrZrO 3 doped with more than 1 mol% of Yb. The assignment of the two dielectric relaxations is discussed in terms of IR spectra and by free energy calculation for a miscibility of dopant Yb ions. The Yb concentration dependence of the relaxation strength of the two dielectric relaxations is in agreement with the results calculated from the free energy. The two relaxations can be assigned to a reorientation of a single Yb-OH dipole and of Yb-OH dipoles associated with Yb-clusters. The attractive energy for Yb-clustering in SrZrO 3 is evaluated at about -85 meV

Layered Cu-based electrode for high-dielectric constant oxide thin film-based devices

International Nuclear Information System (INIS)

Fan, W.; Saha, S.; Carlisle, J.A.; Auciello, O.; Chang, R.P.H.; Ramesh, R.

2003-01-01

Ti-Al/Cu/Ta multilayered electrodes were fabricated on SiO 2 /Si substrates by ion beam sputtering deposition, to overcome the problems of Cu diffusion and oxidation encountered during the high dielectric constant (κ) materials integration. The Cu and Ta layers remained intact through the annealing in oxygen environment up to 600 deg. C. The thin oxide layer, formed on the Ti-Al surface, effectively prevented the oxygen penetration toward underneath layers. Complex oxide (Ba x Sr 1-x )TiO 3 (BST) thin films were grown on the layered Ti-Al/Cu/Ta electrodes using rf magnetron sputtering. The deposited BST films exhibited relatively high permittivity (150), low dielectric loss (0.007) at zero bias, and low leakage current -8 A/cm 2 at 100 kV/cm

Fabrication of Composite Filaments with High Dielectric Permittivity for Fused Deposition 3D Printing.

Science.gov (United States)

Wu, Yingwei; Isakov, Dmitry; Grant, Patrick S

2017-10-23

Additive manufacturing of complex structures with spatially varying electromagnetic properties can enable new applications in high-technology sectors such as communications and sensors. This work presents the fabrication method as well as microstructural and dielectric characterization of bespoke composite filaments for fused deposition modeling (FDM) 3D printing of microwave devices with a high relative dielectric permittivity ϵ = 11 in the GHz frequency range. The filament is composed of 32 vol % of ferroelectric barium titanate (BaTiO 3 ) micro-particles in a polymeric acrylonitrile butadiene styrene (ABS) matrix. An ionic organic ester surfactant was added during formulation to enhance the compatibility between the polymer and the BaTiO 3 . To promote reproducible and robust printability of the fabricated filament, and to promote plasticity, dibutyl phthalate was additionally used. The combined effect of 1 wt % surfactant and 5 wt % plasticizer resulted in a uniform, many hundreds of meters, continuous filament of commercial quality capable of many hours of uninterrupted 3D printing. We demonstrate the feasibility of using the high dielectric constant filament for 3D printing through the fabrication of a range of optical devices. The approach herein may be used as a guide for the successful fabrication of many types of composite filament with varying functions for a broad range of applications.

Inkjet 3D printing of UV and thermal cure silicone elastomers for dielectric elastomer actuators

Science.gov (United States)

McCoul, David; Rosset, Samuel; Schlatter, Samuel; Shea, Herbert

2017-12-01

Dielectric elastomer actuators (DEAs) are an attractive form of electromechanical transducer, possessing high energy densities, an efficient design, mechanical compliance, high speed, and noiseless operation. They have been incorporated into a wide variety of devices, such as microfluidic systems, cell bioreactors, tunable optics, haptic displays, and actuators for soft robotics. Fabrication of DEA devices is complex, and the majority are inefficiently made by hand. 3D printing offers an automated and flexible manufacturing alternative that can fabricate complex, multi-material, integrated devices consistently and in high resolution. We present a novel additive manufacturing approach to DEA devices in which five commercially available, thermal and UV-cure DEA silicone rubber materials have been 3D printed with a drop-on-demand, piezoelectric inkjet system. Using this process, 3D structures and high-quality silicone dielectric elastomer membranes as thin as 2 μm have been printed that exhibit mechanical and actuation performance at least as good as conventionally blade-cast membranes. Printed silicone membranes exhibited maximum tensile strains of up to 727%, and DEAs with printed silicone dielectrics were actuated up to 6.1% area strain at a breakdown strength of 84 V μm-1 and also up to 130 V μm-1 at 2.4% strain. This approach holds great potential to manufacture reliable, high-performance DEA devices with high throughput.

Terahertz-frequency dielectric response of liquids

DEFF Research Database (Denmark)

Jepsen, Peter Uhd; Møller, Uffe; Cooke, David

The dielectric response of liquids spans many decades in frequency. The dielectric response of a polar liquid is typically determined by relaxational dynamics of the dipolar moments of the liquid. In contrast, the dielectric response of a nonpolar liquid is determined by much weaker collision......-induced dipole moments. In the polar liquid water the fastest relaxational dynamics is found at terahertz frequencies, just below the first intermolecular vibrational and librational modes. In this presentation we will discuss optical terahertz spectroscopic techniques for measurement of the full dielectric...... function of liquids at terahertz frequencies. We will review the current understanding of the high-frequency dielectric spectrum of water, and discuss the relation between the dielectric spectrum and the thermodynamic properties of certain aqueous solutions....

Superconductivity suppression near metal-dielectric in transition highly disordered systems

International Nuclear Information System (INIS)

Kuchinskij, Eh.Z.; Sadovskij, M.V.; Ehrkabaev, M.A.

1997-01-01

The effects of temperature suppression of superconducting transition T c within wide limits of disorders values from low-disordered to highly-disordered ones caused by formation of the Coulomb gap in the states density are studied on the bases of the earlier proposed self consistent theory on the metal-dielectric. It is shown that the proposed theory gives satisfactory description of experimental data for a number of the systems under study

Temporal variation of dielectric properties of preserved blood

Energy Technology Data Exchange (ETDEWEB)

Hayashi, Yoshihito [Life Science Laboratory, Materials Laboratories, Sony Corporation, Sony Bioinformatics Center, Tokyo Medical and Dental University, Bunkyo-ku, Tokyo 113-8510 (Japan); Oshige, Ikuya [Life Science Laboratory, Materials Laboratories, Sony Corporation, Sony Bioinformatics Center, Tokyo Medical and Dental University, Bunkyo-ku, Tokyo 113-8510 (Japan); Katsumoto, Yoichi [Life Science Laboratory, Materials Laboratories, Sony Corporation, Sony Bioinformatics Center, Tokyo Medical and Dental University, Bunkyo-ku, Tokyo 113-8510 (Japan); Omori, Shinji [Life Science Laboratory, Materials Laboratories, Sony Corporation, Sony Bioinformatics Center, Tokyo Medical and Dental University, Bunkyo-ku, Tokyo 113-8510 (Japan); Yasuda, Akio [Life Science Laboratory, Materials Laboratories, Sony Corporation, Sony Bioinformatics Center, Tokyo Medical and Dental University, Bunkyo-ku, Tokyo 113-8510 (Japan); Asami, Koji [Laboratory of Molecular Aggregation Analysis, Division of Multidisciplinary Chemistry, Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011 (Japan)

2008-01-07

Rabbit blood was preserved at 277 K in Alsever's solution for 37 days, and its dielectric permittivity was monitored in a frequency range from 0.05 to 110 MHz throughout the period. The relaxation time and Cole-Cole parameter of the interfacial polarization process for erythrocytes remained nearly constant during the first 20 days and then started to increase and decrease, respectively. On the other hand, the relaxation strength and the cell volume fraction continued to decrease for 37 days, but the decrease rates of both changed discontinuously on about the 20th day. Microscope observation showed that approximately 90% of the erythrocytes were spinous echinocytes at the beginning of preservation and started to be transformed into microspherocytes around the 20th day. Therefore, dielectric spectroscopy is a sensitive tool to monitor the deterioration of preserved blood accompanied by morphological transition of erythrocytes through the temporal variation of their dielectric properties.

Lanthanum titanium perovskite compound: Thin film deposition and high frequency dielectric characterization

Energy Technology Data Exchange (ETDEWEB)

Le Paven, C., E-mail: claire.lepaven@univ-rennes1.fr [Institut d' Electronique et de Télécommunications de Rennes (IETR, UMR-CNRS 6164), Equipe Matériaux Fonctionnels, IUT Saint Brieuc, Université de Rennes 1, 22000 Saint Brieuc (France); Lu, Y. [Institut d' Electronique et de Télécommunications de Rennes (IETR, UMR-CNRS 6164), Equipe Matériaux Fonctionnels, IUT Saint Brieuc, Université de Rennes 1, 22000 Saint Brieuc (France); Nguyen, H.V. [Institut d' Electronique et de Télécommunications de Rennes (IETR, UMR-CNRS 6164), Equipe Matériaux Fonctionnels, IUT Saint Brieuc, Université de Rennes 1, 22000 Saint Brieuc (France); CEA LETI, Minatec Campus, 38054 Grenoble (France); Benzerga, R.; Le Gendre, L. [Institut d' Electronique et de Télécommunications de Rennes (IETR, UMR-CNRS 6164), Equipe Matériaux Fonctionnels, IUT Saint Brieuc, Université de Rennes 1, 22000 Saint Brieuc (France); Rioual, S. [Laboratoire de Magnétisme de Brest (EA CNRS 4522), Université de Bretagne Occidentale, 29000 Brest (France); Benzegoutta, D. [Institut des Nanosciences de Paris (INSP, UMR CNRS 7588), Université Pierre et Marie Curie, 75005 Paris (France); Tessier, F.; Cheviré, F. [Institut des Sciences Chimiques de Rennes (ISCR, UMR-CNRS 6226), Equipe Verres et Céramiques, Université de Rennes 1, 35000 Rennes (France); and others

2014-02-28

Perovskite lanthanum titanium oxide thin films were deposited on (001) MgO, (001) LaAlO{sub 3} and Pt(111)/TiO{sub 2}/SiO{sub 2}/(001)Si substrates by RF magnetron sputtering, using a La{sub 2}Ti{sub 2}O{sub 7} homemade target sputtered under oxygen reactive plasma. The films deposited at 800 °C display a crystalline growth different than those reported on monoclinic ferroelectric La{sub 2}Ti{sub 2}O{sub 7} films. X-ray photoelectron spectroscopy analysis shows the presence of titanium as Ti{sup 4+} ions, with no trace of Ti{sup 3+}, and provides a La/Ti ratio of 1.02. The depositions being performed from a La{sub 2}Ti{sub 2}O{sub 7} target under oxygen rich plasma, the same composition (La{sub 2}Ti{sub 2}O{sub 7}) is proposed for the deposited films, with an unusual orthorhombic cell and Cmc2{sub 1} space group. The films have a textured growth on MgO and Pt/Si substrates, and are epitaxially grown on LaAlO{sub 3} substrate. The dielectric characterization displays stable values of the dielectric constant and of the losses in the frequency range [0.1–20] GHz. No variation of the dielectric constant has been observed when a DC electric field up to 250 kV/cm was applied, which does not match a classical ferroelectric behavior at high frequencies and room temperature for the proposed La{sub 2}Ti{sub 2}O{sub 7} orthorhombic phase. At 10 GHz and room temperature, the dielectric constant of the obtained La{sub 2}Ti{sub 2}O{sub 7} films is ε ∼ 60 and the losses are low (tanδ < 0.02). - Highlights: • Lanthanum titanium oxide films were deposited by reactive magnetron sputtering. • A La{sub 2}Ti{sub 2}O{sub 7} chemical composition is proposed, with an unusual orthorhombic cell. • At 10 GHz, the dielectric losses are lower than 0.02. • No variation of the dielectric constant is observed under DC electric biasing.

Nonlinear electroelastic deformations of dielectric elastomer composites: II - Non-Gaussian elastic dielectrics

Science.gov (United States)

Lefèvre, Victor; Lopez-Pamies, Oscar

2017-02-01

This paper presents an analytical framework to construct approximate homogenization solutions for the macroscopic elastic dielectric response - under finite deformations and finite electric fields - of dielectric elastomer composites with two-phase isotropic particulate microstructures. The central idea consists in employing the homogenization solution derived in Part I of this work for ideal elastic dielectric composites within the context of a nonlinear comparison medium method - this is derived as an extension of the comparison medium method of Lopez-Pamies et al. (2013) in nonlinear elastostatics to the coupled realm of nonlinear electroelastostatics - to generate in turn a corresponding solution for composite materials with non-ideal elastic dielectric constituents. Complementary to this analytical framework, a hybrid finite-element formulation to construct homogenization solutions numerically (in three dimensions) is also presented. The proposed analytical framework is utilized to work out a general approximate homogenization solution for non-Gaussian dielectric elastomers filled with nonlinear elastic dielectric particles that may exhibit polarization saturation. The solution applies to arbitrary (non-percolative) isotropic distributions of filler particles. By construction, it is exact in the limit of small deformations and moderate electric fields. For finite deformations and finite electric fields, its accuracy is demonstrated by means of direct comparisons with finite-element solutions. Aimed at gaining physical insight into the extreme enhancement in electrostriction properties displayed by emerging dielectric elastomer composites, various cases wherein the filler particles are of poly- and mono-disperse sizes and exhibit different types of elastic dielectric behavior are discussed in detail. Contrary to an initial conjecture in the literature, it is found (inter alia) that the isotropic addition of a small volume fraction of stiff (semi-)conducting/high

Influence of Low Speed Rolling Movement on High Electrical Breakdown for Water Dielectric with Microsecond Charging

International Nuclear Information System (INIS)

Zhang Zicheng; Zhang Jiande; Yang Jianhua

2006-01-01

By means of a coaxial apparatus, high electrical breakdown experiments are carried out in the rest state and the low speed rolling state with microsecond charging and the experimental results are analyzed. The conclusions are: (1) the breakdown stress of water dielectric in the rolling state is in good agreement with that in Martin formula, and so is that in the rest state; (2) the breakdown stress of water dielectric in the rolling state is about 5% higher than that in the rest state; (3) the results simulated with ANSYS demonstrate that the breakdown stress of water dielectric decreases when the bubbles appear near the surface of electrodes; (4) the primary mechanism to increase the breakdown stress of water dielectric in the rolling state is that the bubbles are driven away and the number of bubbles near the surface of electrodes is decreased by rolling movement

Comparison and Analysis of Steel Frame Based on High Strength Column and Normal Strength Column

Science.gov (United States)

Liu, Taiyu; An, Yuwei

2018-01-01

The anti-seismic performance of high strength steel has restricted its industrialization in civil buildings. In order to study the influence of high strength steel column on frame structure, three models are designed through MIDAS/GEN finite element software. By comparing the seismic performance and economic performance of the three models, the three different structures are comprehensively evaluated to provide some references for the development of high strength steel in steel structure.

Silicone-based Dielectric Elastomers

DEFF Research Database (Denmark)

Skov, Anne Ladegaard

Efficient conversion of energy from one form to another (transduction) is an important topic in our daily day, and it is a necessity in moving away from the fossil based society. Dielectric elastomers hold great promise as soft transducers, since they are compliant and light-weight amongst many...... energy efficient solutions are highly sought. These properties allow for interesting products ranging very broadly, e.g. from eye implants over artificial skins over soft robotics to huge wave energy harvesting plants. All these products utilize the inherent softness and compliance of the dielectric...... elastomer transducers. The subject of this thesis is improvement of properties of silicone-based dielectric elastomers with special focus on design guides towards electrically, mechanically, and electromechanically reliable elastomers. Strategies for improving dielectric elastomer performance are widely...

A threshold-voltage model for small-scaled GaAs nMOSFET with stacked high-k gate dielectric

International Nuclear Information System (INIS)

Liu Chaowen; Xu Jingping; Liu Lu; Lu Hanhan; Huang Yuan

2016-01-01

A threshold-voltage model for a stacked high-k gate dielectric GaAs MOSFET is established by solving a two-dimensional Poisson's equation in channel and considering the short-channel, DIBL and quantum effects. The simulated results are in good agreement with the Silvaco TCAD data, confirming the correctness and validity of the model. Using the model, impacts of structural and physical parameters of the stack high-k gate dielectric on the threshold-voltage shift and the temperature characteristics of the threshold voltage are investigated. The results show that the stacked gate dielectric structure can effectively suppress the fringing-field and DIBL effects and improve the threshold and temperature characteristics, and on the other hand, the influence of temperature on the threshold voltage is overestimated if the quantum effect is ignored. (paper)

Medium band gap polymer based solution-processed high-κ composite gate dielectrics for ambipolar OFET

Science.gov (United States)

Canımkurbey, Betül; Unay, Hande; Çakırlar, Çiğdem; Büyükköse, Serkan; Çırpan, Ali; Berber, Savas; Altürk Parlak, Elif

2018-03-01

The authors present a novel ambipolar organic filed-effect transistors (OFETs) composed of a hybrid dielectric thin film of Ta2O5:PMMA nanocomposite material, and solution processed poly(selenophene, benzotriazole and dialkoxy substituted [1,2-b:4, 5-b‧] dithiophene (P-SBTBDT)-based organic semiconducting material as the active layer of the device. We find that the Ta2O5:PMMA insulator shows n-type conduction character, and its combination with the p-type P-SBTBDT organic semiconductor leads to an ambipolar OFET device. Top-gated OFETs were fabricated on glass substrate consisting of interdigitated ITO electrodes. P-SBTBDT-based material was spin coated on the interdigitated ITO electrodes. Subsequently, a solution processed Ta2O5:PMMA nanocomposite material was spin coated, thereby creating the gate dielectric layer. Finally, as a gate metal, an aluminum layer was deposited by thermal evaporation. The fabricated OFETs exhibited an ambipolar performance with good air-stability, high field-induced current and relatively high electron and hole mobilities although Ta2O5:PMMA nanocomposite films have slightly higher leakage current compared to the pure Ta2O5 films. Dielectric properties of the devices with different ratios of Ta2O5:PMMA were also investigated. The dielectric constant varied between 3.6 and 5.3 at 100 Hz, depending on the Ta2O5:PMMA ratio.

Slippage of steel in high and normal strength concrete

International Nuclear Information System (INIS)

Ahmed, K.; Siddiqi, Z.A.; Yousaf, M.

2007-01-01

Composite action of any reinforced concrete member is only possible if sufficient bond strength exists between steel reinforcing bars and concrete, which can adequately transfer shear stress between them. Bond strength is a function of compressive strength of concrete and hence high strength concrete has higher bond strength (1-2). Therefore required development length can be reduced. In order to investigate the effect of development length on bond stress and slip relationships, experimental investigation was carried out. In this experimentation 24 pull-out samples of high strength concrete and normal strength concrete were casted and tested. The results of this investigation revealed that by increasing the development length from 5db to 10db bond strength increases for both high and normal strength concrete as shown in Figure 11, 12 and 13. However in case of normal strength concrete increase in bond strength is more compared to that in high strength concrete as it is clear from Figure 11 and Figure 13. The increase in bond strength is observed even at 10db development length but the extent is less for 19 mm than 16 mm bars as shown in Figure 12 and Figure 13. This is in agreement with the earlier findings of Chen et al (3) and Harajli et al (1). However in case of HSC the total slippage at 10db is 50% greater than at 5db. This may be due to the fact that more no of concrete keys participate in resisting the slippage. (author)

Effects of Complex Structured Anodic Oxide Dielectric Layer Grown in Pore Matrix for Aluminum Capacitor.

Science.gov (United States)

Shin, Jin-Ha; Yun, Sook Young; Lee, Chang Hyoung; Park, Hwa-Sun; Suh, Su-Jeong

2015-11-01

Anodization of aluminum is generally divided up into two types of anodic aluminum oxide structures depending on electrolyte type. In this study, an anodization process was carried out in two steps to obtain high dielectric strength and break down voltage. In the first step, evaporated high purity Al on Si wafer was anodized in oxalic acidic aqueous solution at various times at a constant temperature of 5 degrees C. In the second step, citric acidic aqueous solution was used to obtain a thickly grown sub-barrier layer. During the second anodization process, the anodizing potential of various ranges was applied at room temperature. An increased thickness of the sub-barrier layer in the porous matrix was obtained according to the increment of the applied anodizing potential. The microstructures and the growth of the sub-barrier layer were then observed with an increasing anodizing potential of 40 to 300 V by using a scanning electron microscope (SEM). An impedance analyzer was used to observe the change of electrical properties, including the capacitance, dissipation factor, impedance, and equivalent series resistance (ESR) depending on the thickness increase of the sub-barrier layer. In addition, the breakdown voltage was measured. The results revealed that dielectric strength was improved with the increase of sub-barrier layer thickness.

Methods of making a high dielectric constant, resistive phase of YBa2Cu3OX and methods of using the same

International Nuclear Information System (INIS)

Testardi, L.R.

1991-01-01

This patent describes an electrical device. It comprises a dielectric material configured so as to have a pair of opposite sides, the dielectric material comprising a high dielectric constant, high electrical resistivity material phase of yttrium barium copper oxide obtained by heating the yttrium barium copper oxide to at least about 850 degrees Celsius and then quenching the yttrium barium copper oxide from the at least about 850 degrees Celsius at a sufficiently rapid rate so as to produce the high dielectric constant, high electrical resistivity material phase in the yttrium barium copper oxide; a first plate means for storing electrical charge provided on a first one of the pair of opposite sides of the dielectric material; a second plate means for storing electrical charge provided on a second one of the pair of opposite sides of the dielectric material; a first lead means adjacent to and in electrical contact with the first plate means for permitting electrical contact to the first plate means; and a second lead means adjacent to and in electrical contact with the second plate means for permitting electrical contact to the second plate means; wherein the electrical device is a capacitor having a useful, desired capacitance and is adapted to be used in diverse electrical and electronic applications for the storage of electrical charge

The possibility of using high strength reinforced concrete

International Nuclear Information System (INIS)

Miura, Nobuaki

1991-01-01

There is recently much research about and developments in reinforced concrete using high strength concrete and reinforcement. As a result, some high-rise buildings and nuclear buildings have been constructed with such concrete. Reinforced concrete will be stronger in the future, but there is a limit to its strength defined by the character of the materials and also by the character of the reinforced concrete members made of the concrete and reinforcement. This report describes the merits and demerits of using high strength reinforced concrete. (author)

Fabrication of Composite Filaments with High Dielectric Permittivity for Fused Deposition 3D Printing

Directory of Open Access Journals (Sweden)

Yingwei Wu

2017-10-01

Full Text Available Additive manufacturing of complex structures with spatially varying electromagnetic properties can enable new applications in high-technology sectors such as communications and sensors. This work presents the fabrication method as well as microstructural and dielectric characterization of bespoke composite filaments for fused deposition modeling (FDM 3D printing of microwave devices with a high relative dielectric permittivity ϵ = 11 in the GHz frequency range. The filament is composed of 32 vol % of ferroelectric barium titanate (BaTiO 3 micro-particles in a polymeric acrylonitrile butadiene styrene (ABS matrix. An ionic organic ester surfactant was added during formulation to enhance the compatibility between the polymer and the BaTiO 3 . To promote reproducible and robust printability of the fabricated filament, and to promote plasticity, dibutyl phthalate was additionally used. The combined effect of 1 wt % surfactant and 5 wt % plasticizer resulted in a uniform, many hundreds of meters, continuous filament of commercial quality capable of many hours of uninterrupted 3D printing. We demonstrate the feasibility of using the high dielectric constant filament for 3D printing through the fabrication of a range of optical devices. The approach herein may be used as a guide for the successful fabrication of many types of composite filament with varying functions for a broad range of applications.

Pentacene based thin film transistors with high-k dielectric Nd2O3 as a gate insulator

International Nuclear Information System (INIS)

Sarma, R.; Saikia, D.

2010-01-01

We have investigated the pentacene based Organic Thin Film Transistors (OTFTs) with high-k dielectric Nd 2 O 3 . Use of high dielectric constant (high-k) gate insulator Nd 2 O 3 reduces the threshold voltage and sub threshold swing of the OTFTs. The calculated threshold voltage -2.2V and sub-threshold swing 1V/decade, current ON-OFF ratio is 1.7 X 10 4 and mobility is 0.13cm 2 /V.s. Pentacene film is deposited on Nd 2 O 3 surface using two step deposition method. Deposited pentacene film is found poly crystalline in nature. (author)

Perovskite oxynitride LaTiO{sub x}N{sub y} thin films: Dielectric characterization in low and high frequencies

Energy Technology Data Exchange (ETDEWEB)

Lu, Y.; Ziani, A. [Institut d' Electronique et de Telecommunications de Rennes (IETR) UMR-CNRS 6164, groupe ' Antennes et Hyperfrequences' , University of Rennes 1, UEB, IUT Saint Brieuc, 18 rue Henri Wallon, 22004 Saint Brieuc cedex (France); Le Paven-Thivet, C., E-mail: claire.lepaven@univ-rennes1.fr [Institut d' Electronique et de Telecommunications de Rennes (IETR) UMR-CNRS 6164, groupe ' Antennes et Hyperfrequences' , University of Rennes 1, UEB, IUT Saint Brieuc, 18 rue Henri Wallon, 22004 Saint Brieuc cedex (France); Benzerga, R.; Le Gendre, L. [Institut d' Electronique et de Telecommunications de Rennes (IETR) UMR-CNRS 6164, groupe ' Antennes et Hyperfrequences' , University of Rennes 1, UEB, IUT Saint Brieuc, 18 rue Henri Wallon, 22004 Saint Brieuc cedex (France); Fasquelle, D. [Laboratoire d' Etude des Materiaux et des Composants pour l' Electronique (LEMCEL) UPRES-EA 2601, University of Littoral-Cote d' Opale, 50 rue Ferdinand Buisson, F-62228 Calais cedex (France); Kassem, H. [Laboratoire de l' Integration du Materiau au Systeme(IMS) UMR-CNRS 5218, groupe Materiaux, University of Bordeaux 1, 16 avenue Pey-Berland, 33607 Pessac (France); and others

2011-11-01

Lanthanum titanium oxynitride (LaTiO{sub x}N{sub y}) thin films are studied with respect to their dielectric properties in low and high frequencies. Thin films are deposited by radio frequency magnetron sputtering on different substrates. Effects of nitrogen content and crystalline quality on dielectric properties are investigated. In low-frequency range, textured LaTiO{sub x}N{sub y} thin films deposited on conductive single crystal Nb-STO show a dielectric constant {epsilon} Prime Almost-Equal-To 140 with low losses tan{delta} = 0.012 at 100 kHz. For the LaTiO{sub x}N{sub y} polycrystalline films deposited on conductive silicon substrates with platinum (Pt/Ti/SiO{sub 2}/Si), the tunability reached up to 57% for a weak electric field of 50 kV/cm. In high-frequency range, epitaxial LaTiO{sub x}N{sub y} films deposited on MgO substrate present a high dielectric constant with low losses ({epsilon} Prime Almost-Equal-To 170, tan{delta} = 0.011, 12 GHz).

Strength of precast concrete shear joints reinforced with high-strength wire ropes

DEFF Research Database (Denmark)

Joergensen, Henrik B.; Hoang, Linh Cao; Hagsten, Lars German

2017-01-01

This paper concerns the in-plane shear strength of connections between precast concrete wall elements reinforced with looped high-strength wire ropes. The looped wire ropes are pre-installed in so-called ‘wire boxes’ which function as shear keys. Although only a small amount of research...... on the shear strength of such connections can be found in the literature, this type of connection is increasingly being used because wire ropes are much more construction-friendly than traditional U-bars. A rigid plastic upper bound model for the shear strength of wall connections reinforced with looped wire...... ropes that are pre-installed in wire boxes is presented along with test results on the shear strength of connections with double-wire boxes. It is shown that the plastic solution agrees well with both the obtained test results and results from previously conducted tests....

A threshold-voltage model for small-scaled GaAs nMOSFET with stacked high-k gate dielectric

Science.gov (United States)

Chaowen, Liu; Jingping, Xu; Lu, Liu; Hanhan, Lu; Yuan, Huang

2016-02-01

A threshold-voltage model for a stacked high-k gate dielectric GaAs MOSFET is established by solving a two-dimensional Poisson's equation in channel and considering the short-channel, DIBL and quantum effects. The simulated results are in good agreement with the Silvaco TCAD data, confirming the correctness and validity of the model. Using the model, impacts of structural and physical parameters of the stack high-k gate dielectric on the threshold-voltage shift and the temperature characteristics of the threshold voltage are investigated. The results show that the stacked gate dielectric structure can effectively suppress the fringing-field and DIBL effects and improve the threshold and temperature characteristics, and on the other hand, the influence of temperature on the threshold voltage is overestimated if the quantum effect is ignored. Project supported by the National Natural Science Foundation of China (No. 61176100).

Improved linearity in AlGaN/GaN metal-insulator-semiconductor high electron mobility transistors with nonlinear polarization dielectric

International Nuclear Information System (INIS)

Gao, Tao; Xu, Ruimin; Kong, Yuechan; Zhou, Jianjun; Kong, Cen; Dong, Xun; Chen, Tangsheng

2015-01-01

We demonstrate highly improved linearity in a nonlinear ferroelectric of Pb(Zr 0.52 Ti 0.48 )-gated AlGaN/GaN metal-insulator-semiconductor high electron mobility transistor (MIS-HEMT). Distinct double-hump feature in the transconductance-gate voltage (g m -V g ) curve is observed, yielding remarkable enhancement in gate voltage swing as compared to MIS-HEMT with conventional linear gate dielectric. By incorporating the ferroelectric polarization into a self-consistent calculation, it is disclosed that in addition to the common hump corresponding to the onset of electron accumulation, the second hump at high current level is originated from the nonlinear polar nature of ferroelectric, which enhances the gate capacitance by increasing equivalent dielectric constant nonlinearly. This work paves a way for design of high linearity GaN MIS-HEMT by exploiting the nonlinear properties of dielectric

Dielectric elastomers with novel highly-conducting electrodes

Science.gov (United States)

Böse, Holger; Uhl, Detlev

2013-04-01

Beside the characteristics of the elastomer material itself, the performance of dielectric elastomers in actuator, sensor as well as generator applications depends also on the properties of the electrode material. Various electrode materials based on metallic particles dispersed in a silicone matrix were manufactured and investigated. Anisotropic particles such as silver-coated copper flakes and silver-coated glass flakes were used for the preparation of the electrodes. The concentration of the metallic particles and the thickness of the electrode layers were varied. Specific conductivities derived from resistance measurements reached about 100 S/cm and surmount those of the reference materials based on graphite and carbon black by up to three orders of magnitude. The high conductivities of the new electrode materials can be maintained even at very large stretch deformations up to 200 %.

Three-Sheet Spot Welding of Advanced High-Strength Steels

DEFF Research Database (Denmark)

Nielsen, Chris Valentin; Friis, Kasper Storgaard; Zhang, W.

2011-01-01

The automotive industry has introduced the three-layer weld configuration, which represents new challenges compared to normal two-sheet lap welds. The process is further complicated by introducing high-strength steels in the joint. The present article investigates the weldability of thin, low....... The weld mechanisms are analyzed numerically and compared with metallographic analyses showing how the primary bonding mechanism between the thin, low-carbon steel sheet and the thicker sheet of high-strength steel is solid-state bonding, whereas the two high-strength steels are joined by melting, forming...... a weld nugget at their mutual interface. Despite the absence of the typical fusion nugget through the interface between the low-carbon steel and high-strength steel, the weld strengths obtained are acceptable. The failure mechanism in destructive testing is ductile fracture with plug failure....

Preparation of dielectrics HR mirrors from colloidal oxide suspensions containing organic polymer binders

International Nuclear Information System (INIS)

Thomas, I.M.

1994-01-01

Colloidal suspensions of oxides have been used to prepare dielectric HR (high reflective) mirrors, specifically for high power fusion case applications, on substrates up to 38 cm square using a meniscus coater. These coatings consist of porous quarterwave layers of alternating high and low refractive index oxides. Silica was used as the low index oxide and AlOOH, ZrO 2 , or HfO 2 as the high index material. Coatings were weak because of low particle-to-particle adhesion. Use of organic polymer binders in the high index component was found to increase strength, thereby improving the laser damage threshold and also reducing the number of layers required for 99% reflection due to increased refractive index

Nonlinear Dielectric Response of Water Treed XLPE Cable Insulation

Energy Technology Data Exchange (ETDEWEB)

Hvidsten, Sverre

1999-07-01

Condition assessment of XLPE power cables is becoming increasingly important for the utilities, due to a large number of old cables in service with high probability of failure caused by water tree degradation. The commercial available techniques are generally based upon measurements of the dielectric response, either by time (polarisation/depolarisation current or return voltage) or frequency domain measurements. Recently it has been found that a high number of water trees in XLPE insulated cables causes the dielectric response to increase more than linearly with increasing test voltage. This nonlinear feature of water tree degraded XLPE insulation has been suggested to be of a great importance, both for diagnostic purposes, and for fundamental understanding of the water tree phenomenon itself. The main purpose of this thesis have been to study the nonlinear feature of the dielectric response measured on watertreed XLPE insulation. This has been performed by dielectric response measurements in both time and frequency domain, numerical calculations of losses of simplified water tree models, and fmally water content and water permeation measurements on single water trees. The dielectric response measurements were performed on service aged cable samples and laboratory aged Rogowski type objects. The main reason for performing laboratory ageing was to facilitate diagnostic testing as a function of ageing time of samples containing mainly vented water trees. A new method, based upon inserting NaC1 particles at the interface between the upper semiconductive screen and the insulation, was found to successfully enhance initiation and growth of vented water trees. AC breakdown strength testing show that it is the vented water trees that reduce the breakdown level of both the laboratory aged test objects and service aged cable samples. Vented water treeing was found to cause the dielectric response to become nonlinear at a relatively low voltage level. However, the measured

Electrical Properties of Thin-Film Capacitors Fabricated Using High Temperature Sputtered Modified Barium Titanate

Directory of Open Access Journals (Sweden)

Robert Mamazza

2012-04-01

Full Text Available Simple thin-film capacitor stacks were fabricated from sputter-deposited doped barium titanate dielectric films with sputtered Pt and/or Ni electrodes and characterized electrically. Here, we report small signal, low frequency capacitance and parallel resistance data measured as a function of applied DC bias, polarization versus applied electric field strength and DC load/unload experiments. These capacitors exhibited significant leakage (in the range 8–210 μA/cm2 and dielectric loss. Measured breakdown strength for the sputtered doped barium titanate films was in the range 200 kV/cm −2 MV/cm. For all devices tested, we observed clear evidence for dielectric saturation at applied electric field strengths above 100 kV/cm: saturated polarization was in the range 8–15 μC/cm2. When cycled under DC conditions, the maximum energy density measured for any of the capacitors tested here was ~4.7 × 10−2 W-h/liter based on the volume of the dielectric material only. This corresponds to a specific energy of ~8 × 10−3 W-h/kg, again calculated on a dielectric-only basis. These results are compared to those reported by other authors and a simple theoretical treatment provided that quantifies the maximum energy that can be stored in these and similar devices as a function of dielectric strength and saturation polarization. Finally, a predictive model is developed to provide guidance on how to tailor the relative permittivities of high-k dielectrics in order to optimize their energy storage capacities.

Effect of neutron radiation on the dielectric, mechanical and thermal properties of ceramics for RF transmission windows

International Nuclear Information System (INIS)

Hazelton, C.; Rice, J.; Snead, L.L.; Zinkle, S.J.

1998-01-01

The behavior of electrically insulating ceramics was investigated before and after exposure to neutron radiation. Mechanical, thermal and dielectric specimens were studied after exposure to a fast neutron dose of 0.1 displacements per atom (dpa) at Oak Ridge National Laboratory (ORNL). Four materials were compared to alumina: polycrystalline spinel, aluminum nitride, sialon and silicon nitride. Mechanical bend tests were performed before and after irradiation. Thermal diffusivity was measured using a room temperature laser flash technique. Dielectric loss factor was measured at 105 MHz with a special high resolution resonance cavity. The materials exhibited a significant degradation of thermal diffusivity and an increase in dielectric loss tangent. The flexural strength and physical dimensions were not significantly affected by the 0.1 dpa level of neutron radiation. The aluminum nitride and S silicon nitride showed superior RF window performance over the sialon and the alumina. The results are compared to radiation studies on similar materials

Infrared and THz spectroscopy of nanostructured dielectrics

Directory of Open Access Journals (Sweden)

Jan Petzelt

2009-09-01

Full Text Available Results achieved using the infrared/THz spectroscopy of various inhomogeneous dielectrics in the Department of Dielectrics, Institute of Physics, Prague, during the last decade are briefly reviewed. The discussion concerns high-permittivity ceramics with inevitable low-permittivity dead layers along the grain boundaries, relaxor ferroelectrics with highly anisotropic polar nano-regions, classical matrix-type composites, core-shell composites, filled nanoporous glasses, polycrystalline and epitaxial thin films, heterostructures and superlattices on dielectric substrates. The analysis using models based on the effective medium approach is discussed. The importance of depolarizing field and of the percolation of components on the effective ac dielectric response and the excitations contributing to it are emphasized.

High-strength mineralized collagen artificial bone

Science.gov (United States)

Qiu, Zhi-Ye; Tao, Chun-Sheng; Cui, Helen; Wang, Chang-Ming; Cui, Fu-Zhai

2014-03-01

Mineralized collagen (MC) is a biomimetic material that mimics natural bone matrix in terms of both chemical composition and microstructure. The biomimetic MC possesses good biocompatibility and osteogenic activity, and is capable of guiding bone regeneration as being used for bone defect repair. However, mechanical strength of existing MC artificial bone is too low to provide effective support at human load-bearing sites, so it can only be used for the repair at non-load-bearing sites, such as bone defect filling, bone graft augmentation, and so on. In the present study, a high strength MC artificial bone material was developed by using collagen as the template for the biomimetic mineralization of the calcium phosphate, and then followed by a cold compression molding process with a certain pressure. The appearance and density of the dense MC were similar to those of natural cortical bone, and the phase composition was in conformity with that of animal's cortical bone demonstrated by XRD. Mechanical properties were tested and results showed that the compressive strength was comparable to human cortical bone, while the compressive modulus was as low as human cancellous bone. Such high strength was able to provide effective mechanical support for bone defect repair at human load-bearing sites, and the low compressive modulus can help avoid stress shielding in the application of bone regeneration. Both in vitro cell experiments and in vivo implantation assay demonstrated good biocompatibility of the material, and in vivo stability evaluation indicated that this high-strength MC artificial bone could provide long-term effective mechanical support at human load-bearing sites.

A Comprehensive Study on Dielectric Properties of Volcanic Rock/PANI Composites

Science.gov (United States)

Kiliç, M.; Karabul, Y.; Okutan, M.; İçelli, O.

2016-05-01

Basalt is a very well-known volcanic rock that is dark colored and relatively rich in iron and magnesium, almost located each country in the world. These rocks have been used in the refused rock industry, to produce building tiles, construction industrial, highway engineering. Powders and fibers of basalt rocks are widely used of radiation shielding, thermal stability, heat and sound insulation. This study examined three different basalt samples (coded CM-1, KYZ-13 and KYZ-24) collected from different regions of Van province in Turkey. Polyaniline (PANI) is one of the representative conductive polymers due to its fine environmental stability, huge electrical conductivity, as well as a comparatively low cost. Also, the electrical and thermal properties of polymer composites containing PANI have been widely studied. The dielectric properties of Basalt/Polyaniline composites in different concentrations (10, 25, 50 wt.% PANI) have been investigated by dielectric spectroscopy method at the room temperature. The dielectric parameters (dielectric constants, loss and strength) were measured in the frequency range of 102 Hz-106 Hz at room temperature. The electrical mechanism change with PANI dopant. A detailed dielectrically analysis of these composites will be presented.

Investigating the performance and properties of dielectric elastomer actuators as a potential means to actuate origami structures

International Nuclear Information System (INIS)

Ahmed, S; Ounaies, Z; Frecker, M

2014-01-01

Origami engineering aims to combine origami principles with advanced materials to yield active origami shapes, which fold and unfold in response to external stimuli. This paper explores the potential and limitations of dielectric elastomers (DEs) as the enabling material in active origami engineering. DEs are compliant materials in which the coupled electro-mechanical actuation takes advantage of their low modulus and high breakdown strength. Until recently, prestraining of relatively thick DE materials was necessary in order to achieve the high electric fields needed to trigger electrostatic actuation without inducing a dielectric breakdown. Although prestrain improves the breakdown strength of the DE films and reduces the voltage required for actuation, the need for a solid frame to retain the prestrain state is a limitation for the practical implementation of DEs, especially for active origami structures. However, the recent availability of thinner DE materials (50 μm, 130 μm, 260 μm) has made DEs a likely medium for active origami. In this work, the folding and unfolding of DE multilayered structures, along with the realization of origami-inspired 3D shapes, are explored. In addition, an exhaustive study on the fundamentals of DE actuation is done by directly investigating the thickness actuation mechanism and comparing their performance using different electrode types. Finally, changes in dielectric permittivity as a function of strain, electrode type and applied electric field are assessed and analyzed. These fundamental studies are key to obtaining more dramatic folding and to realizing active origami structures using DE materials. (paper)

Temperature and directional dependences of the infrared dielectric function of free standing silicon nanowire

Energy Technology Data Exchange (ETDEWEB)

Kazan, M.; Bruyant, A.; Sedaghat, Z.; Arnaud, L.; Blaize, S.; Royer, P. [Laboratoire de Nanotechnologie et d' Instrumentation Optique, Institut Charles Delaunay, Universite de Technologie de Troyes, CNRS FRE 2848, 12 Rue Marie Curie, 10010 Troyes, Cedex (France)

2011-03-15

An approach to calculate the infrared dielectric function of semiconductor nanostructures is presented and applied to silicon (Si) nanowires (NW's). The phonon modes symmetries and frequencies are calculated by means of the elastic continuum medium theory. The modes strengths and damping are calculated from a model for lattice dynamics and perturbation theory. The data are used in anisotropic Lorentz oscillator model to generate the temperature and directional dependences of the infrared dielectric function of free standing Si NW's. Our results showed that in the direction perpendicular to the NW axis, the complex dielectric function is identical to that of bulk Si. However, along the NW axis, the infrared dielectric function is a strong function of the wavelength. (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Laser amplification in excited dielectrics

DEFF Research Database (Denmark)

Winkler, Thomas; Haahr-Lillevang, Lasse; Sarpe, Cristian

2018-01-01

Wide-bandgap dielectrics such as glasses or water are transparent at visible and infrared wavelengths. This changes when they are exposed to ultrashort and highly intense laser pulses. Different interaction mechanisms lead to the appearance of various transient nonlinear optical phenomena. Using...... these, the optical properties of dielectrics can be controlled from the transparent to the metal-like state. Here we expand this range by a yet unexplored mechanism in excited dielectrics: amplification. In a two-colour pump-probe experiment, we show that a 400nm femtosecond laser pulse is coherently...

PREFACE: Dielectrics 2009: Measurement Analysis and Applications

Science.gov (United States)

Vaughan, Alun; Williams, Graham

2009-07-01

The conference Dielectrics 2009: Measurements, Analysis and Applications represents a significant milestone in the evolution of dielectrics research in the UK. It is reasonable to state that the academic study of dielectrics has led to many fundamental advances and that dielectric materials underpin the modern world in devices ranging from field effect transistors, which operate at extremely high fields, albeit low voltages, to the high voltage plants that provide the energy that powers our economy. The origins of the Dielectrics Group of the Institute of Physics (IOP), which organized this conference, can be traced directly back to the early 1960s, when Professor Mansel Davies was conducting research into the dielectric relaxation behaviour of polar liquids and solids at The Edward Davies Chemical Laboratories of the University College of Wales, Aberystwyth. He was already well-known internationally for his studies of molecular structure and bonding of small molecules, using infra-red-spectroscopy, and of the physical properties of hydrogen-bonded liquids and solids, using thermodynamic methods. Dielectric spectroscopy was a fairly new area for him and he realized that opportunities for scientists in the UK to gather together and discuss their research in this developing area of physical chemistry/chemical physics were very limited. He conceived the idea of forming a Dielectrics Discussion Group (DDG), which would act as a meeting point and provide a platform for dielectrics research in the UK and beyond and, as a result, a two-day Meeting was convened in the spring of 1968 at Gregynog Hall of the University of Wales, near Newtown, Montgomeryshire. It was organized by Mansel Davies, Alun Price and Graham Williams, all physical chemists from the UCW, Aberystwyth. Fifty scientists attended, being a mix of physical chemists, theoretical chemists, physicists, electrical engineers, polymer and materials scientists, all from the UK, except Dr Brendan Scaife of Trinity

Dielectric and electro-optical parameters of two ferroelectric liquid crystals: a comparative study

International Nuclear Information System (INIS)

Kumar Misra, Abhishek; Kumar Srivastava, Abhishek; Shukla, J P; Manohar, Rajiv

2008-01-01

Dielectric relaxation and an electro-optical study of two ferroelectric liquid crystals having different spontaneous polarizations (Felix 16/100 and Felix 17/000) showing SmC* and SmA phases have been performed in the temperature range 30-80 compfn C. The experimental data have been used to determine different relaxation parameters, viz. distribution parameter, relaxation frequency, dielectric strength and rotational viscosity. The Goldstone mode of dielectric permittivity has been well observed for both the samples under investigation. The activation energy of both the samples has also been determined by the best theoretical fitting of the Arrhenius plot. We have also evaluated the optical response time and anchoring energy coefficients from electro-optical measurement techniques for these samples.

Ultimate Scaling of High-κ Gate Dielectrics: Higher-κ or Interfacial Layer Scavenging?

Directory of Open Access Journals (Sweden)

Takashi Ando

2012-03-01

Full Text Available Current status and challenges of aggressive equivalent-oxide-thickness (EOT scaling of high-κ gate dielectrics via higher-κ ( > 20 materials and interfacial layer (IL scavenging techniques are reviewed. La-based higher-κ materials show aggressive EOT scaling (0.5–0.8 nm, but with effective workfunction (EWF values suitable only for n-type field-effect-transistor (FET. Further exploration for p-type FET-compatible higher-κ materials is needed. Meanwhile, IL scavenging is a promising approach to extend Hf-based high-κ dielectrics to future nodes. Remote IL scavenging techniques enable EOT scaling below 0.5 nm. Mobility-EOT trends in the literature suggest that short-channel performance improvement is attainable with aggressive EOT scaling via IL scavenging or La-silicate formation. However, extreme IL scaling (e.g., zero-IL is accompanied by loss of EWF control and with severe penalty in reliability. Therefore, highly precise IL thickness control in an ultra-thin IL regime ( < 0.5 nm will be the key technology to satisfy both performance and reliability requirements for future CMOS devices.

Multipactor susceptibility on a dielectric with two carrier frequencies

Science.gov (United States)

Iqbal, Asif; Verboncoeur, John; Zhang, Peng

2018-04-01

This work investigates multipactor discharge on a single dielectric surface with two carrier frequencies of an rf electric field. We use Monte Carlo simulations and analytical calculations to obtain susceptibility diagrams in terms of the rf electric field and normal electric field due to the residual charge on the dielectric. It is found that in contrast to the single frequency case, in general, the presence of a second carrier frequency of the rf electric field increases the threshold of the magnitude of the rf electric field to initiate multipactor. The effects of the relative strength and phase, and the frequency separation of the two carrier frequencies are examined. The conditions to minimize mulitpactor are derived.

Experimental investigation of the dielectric properties of soil under hydraulic loading

International Nuclear Information System (INIS)

Bittner, Tilman; Bore, Thierry; Karlovšek, Jurij; Scheuermann, Alexander; Wagner, Norman

2017-01-01

An experimental set-up was developed in order to determine the coupled hydraulic, dielectric and mechanical properties of granular media under hydraulic loading. The set-up consisted of a modified column for permeability tests involving a flow meter and pressure transducers along the sample to quantify the hydraulic gradient. A newly developed open-ended coaxial probe allowed the measurement of the frequency dependent dielectric permittivity of the material under test. The shear strength of the sample within the column was measured using a conventional vane shear device. In this paper, the overall set-up is introduced with focus on the open-ended coaxial probe. The design and calibration of the probe are introduced in detail. A numerical study showed that the sensitive cylindrical volume of the probe was approximately 150 mm in diameter with a depth of 65 mm. An investigation with glass beads showed that the set-up allowed the parameterization of the hydraulic, mechanic and dielectric parameters of granular materials under the influence of vertical flow. A satisfactorily good correlation between porosity and the real part of the dielectric permittivity was detected. The critical hydraulic gradient defining the transition of a fixed bed of particles to fluidization was characterized by a sharp peak in the evolution of the hydraulic conductivity and could easily be determined from the measurements. The shear strength of the material under test reduces linearly with increasing hydraulic gradient. Future investigations will be carried out to provide the required parameterizations for experimental and numerical investigations of the internal erosion of granular media. (paper)

Improved linearity in AlGaN/GaN metal-insulator-semiconductor high electron mobility transistors with nonlinear polarization dielectric

Energy Technology Data Exchange (ETDEWEB)

Gao, Tao [Fundamental Science on EHF Laboratory, University of Electronic Science and Technology of China (UESTC), Chengdu 611731 (China); Science and Technology on Monolithic Integrated Circuits and Modules Laboratory, Nanjing Electronic Devices Institute, Nanjing 210016 (China); Xu, Ruimin [Fundamental Science on EHF Laboratory, University of Electronic Science and Technology of China (UESTC), Chengdu 611731 (China); Kong, Yuechan, E-mail: kycfly@163.com; Zhou, Jianjun; Kong, Cen; Dong, Xun; Chen, Tangsheng [Science and Technology on Monolithic Integrated Circuits and Modules Laboratory, Nanjing Electronic Devices Institute, Nanjing 210016 (China)

2015-06-15

We demonstrate highly improved linearity in a nonlinear ferroelectric of Pb(Zr{sub 0.52}Ti{sub 0.48})-gated AlGaN/GaN metal-insulator-semiconductor high electron mobility transistor (MIS-HEMT). Distinct double-hump feature in the transconductance-gate voltage (g{sub m}-V{sub g}) curve is observed, yielding remarkable enhancement in gate voltage swing as compared to MIS-HEMT with conventional linear gate dielectric. By incorporating the ferroelectric polarization into a self-consistent calculation, it is disclosed that in addition to the common hump corresponding to the onset of electron accumulation, the second hump at high current level is originated from the nonlinear polar nature of ferroelectric, which enhances the gate capacitance by increasing equivalent dielectric constant nonlinearly. This work paves a way for design of high linearity GaN MIS-HEMT by exploiting the nonlinear properties of dielectric.

High-density carrier-accumulated and electrically stable oxide thin-film transistors from ion-gel gate dielectric.

Science.gov (United States)

Fujii, Mami N; Ishikawa, Yasuaki; Miwa, Kazumoto; Okada, Hiromi; Uraoka, Yukiharu; Ono, Shimpei

2015-12-18

The use of indium-gallium-zinc oxide (IGZO) has paved the way for high-resolution uniform displays or integrated circuits with transparent and flexible devices. However, achieving highly reliable devices that use IGZO for low-temperature processes remains a technological challenge. We propose the use of IGZO thin-film transistors (TFTs) with an ionic-liquid gate dielectric in order to achieve high-density carrier-accumulated IGZO TFTs with high reliability, and we discuss a distinctive mechanism for the degradation of this organic-inorganic hybrid device under long-term electrical stress. Our results demonstrated that an ionic liquid or gel gate dielectric provides highly reliable and low-voltage operation with IGZO TFTs. Furthermore, high-density carrier accumulation helps improve the TFT characteristics and reliability, and it is highly relevant to the electronic phase control of oxide materials and the degradation mechanism for organic-inorganic hybrid devices.

Rationally designed polyimides for high-energy density capacitor applications.

Science.gov (United States)

Ma, Rui; Baldwin, Aaron F; Wang, Chenchen; Offenbach, Ido; Cakmak, Mukerrem; Ramprasad, Rampi; Sotzing, Gregory A

2014-07-09

Development of new dielectric materials is of great importance for a wide range of applications for modern electronics and electrical power systems. The state-of-the-art polymer dielectric is a biaxially oriented polypropylene (BOPP) film having a maximal energy density of 5 J/cm(3) and a high breakdown field of 700 MV/m, but with a limited dielectric constant (∼2.2) and a reduced breakdown strength above 85 °C. Great effort has been put into exploring other materials to fulfill the demand of continuous miniaturization and improved functionality. In this work, a series of polyimides were investigated as potential polymer materials for this application. Polyimide with high dielectric constants of up to 7.8 that exhibits low dissipation factors (dielectric constant and band gap. Correlations of experimental and theoretical results through judicious variations of polyimide structures allowed for a clear demonstration of the relationship between chemical functionalities and dielectric properties.

Dielectric-filled radiofrequency linacs

Energy Technology Data Exchange (ETDEWEB)

Faehl, R J; Keinigs, R K; Pogue, E W [Los Alamos National Lab., NM (United States)

1997-12-31

High current, high brightness electron beam accelerators promise to open up dramatic new applications. Linear induction accelerators are currently viewed as the appropriate technology for these applications. A concept by Humphries and Hwang may permit radiofrequency accelerators to fulfill the same functions with greater simplicity and enhanced flexibility. This concept involves the replacement of vacuum rf cavities with dielectric filled ones. Simple analysis indicates that the resonant frequencies are reduced by a factor of ({epsilon}{sub 0}/{epsilon}){sup 1/2} while the stored energy is increased by {epsilon}/{epsilon}{sub 0}. For a high dielectric constant like water, this factor can approach 80. A series of numerical calculations of simple pill-box cavities was performed. Eigenfunctions and resonant frequencies for a full system configuration, including dielectric material, vacuum beamline, and a ceramic window separating the two have been computed. These calculations are compared with the results of a small experimental cavity which have been constructed and operated. Low power tests show excellent agreement. (author). 4 figs., 8 refs.

Cathode fall measurement in a dielectric barrier discharge in helium

Energy Technology Data Exchange (ETDEWEB)

Hao, Yanpeng; Zheng, Bin; Liu, Yaoge [School of Electric Power, South China University of Technology, Guangzhou 510640 (China)

2013-11-15

A method based on the “zero-length voltage” extrapolation is proposed to measure cathode fall in a dielectric barrier discharge. Starting, stable, and discharge-maintaining voltages were measured to obtain the extrapolation zero-length voltage. Under our experimental conditions, the “zero-length voltage” gave a cathode fall of about 185 V. Based on the known thickness of the cathode fall region, the spatial distribution of the electric field strength in dielectric barrier discharge in atmospheric helium is determined. The strong cathode fall with a maximum field value of approximately 9.25 kV/cm was typical for the glow mode of the discharge.

A Flexible Capacitive Sensor with Encapsulated Liquids as Dielectrics

Directory of Open Access Journals (Sweden)

Yasunari Hotta

2012-03-01

Full Text Available Flexible and high-sensitive capacitive sensors are demanded to detect pressure distribution and/or tactile information on a curved surface, hence, wide varieties of polymer-based flexible MEMS sensors have been developed. High-sensitivity may be achieved by increasing the capacitance of the sensor using solid dielectric material while it deteriorates the flexibility. Using air as the dielectric, to maintain the flexibility, sacrifices the sensor sensitivity. In this paper, we demonstrate flexible and highly sensitive capacitive sensor arrays that encapsulate highly dielectric liquids as the dielectric. Deionized water and glycerin, which have relative dielectric constants of approximately 80 and 47, respectively, could increase the capacitance of the sensor when used as the dielectric while maintaining flexibility of the sensor with electrodes patterned on flexible polymer substrates. A reservoir of liquids between the electrodes was designed to have a leak path, which allows the sensor to deform despite of the incompressibility of the encapsulated liquids. The proposed sensor was microfabricated and demonstrated successfully to have a five times greater sensitivity than sensors that use air as the dielectric.

High efficiency on-chip Dielectric Resonator Antennna using micromachining technology

KAUST Repository

Sallam, Mai O.

2015-10-26

In this paper, a novel cylindrical Dielectric Resonator Antenna (DRA) operating at 60 GHz is introduced. The antenna is fabricated using a high-resistivity silicon wafer. The DR is defined in the wafer using micromachining technology. The feeding network is located at the other side of the wafer. The proposed antenna is simulated using HFSS and the results are verified by measurements. The antenna radiation is mainly along the broadside direction. The measured gain, radiation efficiency, and bandwidth are 7 dBi, 74.65%, and 2.23 GHz respectively. The antenna is characterized by high polarization purity where the maximum cross-polarization is -15 dB. © 2015 IEEE.

High efficiency on-chip Dielectric Resonator Antennna using micromachining technology

KAUST Repository

Sallam, Mai O.; Serry, Mohamed; Shamim, Atif; De Raedt, Walter; Sedky, Sherif; Vandenbosch, Guy A. E.; Soliman, Ezzeldin A.

2015-01-01

In this paper, a novel cylindrical Dielectric Resonator Antenna (DRA) operating at 60 GHz is introduced. The antenna is fabricated using a high-resistivity silicon wafer. The DR is defined in the wafer using micromachining technology. The feeding network is located at the other side of the wafer. The proposed antenna is simulated using HFSS and the results are verified by measurements. The antenna radiation is mainly along the broadside direction. The measured gain, radiation efficiency, and bandwidth are 7 dBi, 74.65%, and 2.23 GHz respectively. The antenna is characterized by high polarization purity where the maximum cross-polarization is -15 dB. © 2015 IEEE.

High temperature dielectric properties of spent adsorbent with zinc sulfate by cavity perturbation technique

Energy Technology Data Exchange (ETDEWEB)

Lin, Guo [State Key Laboratory of Complex Nonferrous Metal Resources Clean Utilization, Kunming University of Science and Technology, Kunming, Yunnan 650093 (China); Faculty of Metallurgical and Energy Engineering, Kunming University of Science and Technology, Kunming, Yunnan 650093 (China); Key Laboratory of Unconventional Metallurgy, Ministry of Education, Kunming, Yunnan 650093 (China); National Local Joint Laboratory of Engineering Application of Microwave Energy and Equipment Technology, Kunming, Yunnan 650093 (China); Liu, Chenhui [State Key Laboratory of Complex Nonferrous Metal Resources Clean Utilization, Kunming University of Science and Technology, Kunming, Yunnan 650093 (China); Key Laboratory of Unconventional Metallurgy, Ministry of Education, Kunming, Yunnan 650093 (China); National Local Joint Laboratory of Engineering Application of Microwave Energy and Equipment Technology, Kunming, Yunnan 650093 (China); Faculty of Chemistry and Environment, Yunnan Minzu University, Kunming, Yunnan 650093 (China); Zhang, Libo, E-mail: libozhang77@163.com [State Key Laboratory of Complex Nonferrous Metal Resources Clean Utilization, Kunming University of Science and Technology, Kunming, Yunnan 650093 (China); Faculty of Metallurgical and Energy Engineering, Kunming University of Science and Technology, Kunming, Yunnan 650093 (China); Key Laboratory of Unconventional Metallurgy, Ministry of Education, Kunming, Yunnan 650093 (China); National Local Joint Laboratory of Engineering Application of Microwave Energy and Equipment Technology, Kunming, Yunnan 650093 (China); and others

2017-05-15

Highlights: • Cavity perturbation technique is employed to measure the dielectric properties. • Microwave absorption capability of ZnO is poor from 20 °C to 850 °C. • Dielectric properties of spent absorbent and zinc sulfate are influenced by temperature especially in high temperature stage. • Penetration depths and heating curve indicate spent adsorbent and ZnO·2ZnSO{sub 4}, ZnSO{sub 4} are excellent microwave absorber. • The pore structures of spent adsorbent are improved significantly by microwave-regeneration directly. - Abstract: Dielectric properties of spent adsorbent with zinc sulfate are investigated by cavity perturbation technique at 2450 MHz from 20 °C to approximately 1000 °C. Two weight loss stages are observed for spent adsorbent by thermogravimetric-differential scanning calorimeter (TG-DSC) analysis, and zinc sulfate is decomposed to ZnO·2ZnSO{sub 4} and ZnO at about 750 °C and 860 °C. Microwave absorption capability of ZnSO{sub 4} increases with increasing temperature and declines after ZnO generation on account of the poor dielectric properties. Dielectric properties of spent adsorbent are dependent on apparent density and noticed an interestingly linearly relationship at room temperature. The three parameters increase gently from 20 °C to 400 °C, but a sharp increase both in real part and imaginary part are found subsequently due to the volatiles release and regeneration of carbon. And material conductivity is improved, which contributes to the π-electron conduction appearance. Relationship between penetration depth and temperature further elaborate spent adsorbent is an excellent microwave absorber and the microwave absorption capability order of zinc compounds is ZnO·2ZnSO{sub 4}, ZnSO{sub 4} and ZnO. Heating characteristics suggest that heating rate is related with dielectric properties of materials. The pore structures of spent adsorbent are improved significantly and the surface is smoother after microwave-regeneration.

Mechanical properties of high-strength concrete

Science.gov (United States)

Mokhtarzadeh, Alireza

This report summarizes an experimental program conducted to investigate production techniques and mechanical properties of high strength concrete in general and to provide recommendations for using these concretes in manufacturing precast/prestressed bridge girders. Test variables included total amount and composition of cementitious material (portland cement, fly ash, and silica fume), type and brand of cement, type of silica fume (dry densified and slurry), type and brand of high-range water-reducing admixture, type of aggregate, aggregate gradation, maximum aggregate size, and curing. Tests were conducted to determine the effects of these variables on changes in compressive strength and modulus of elasticity over time, splitting tensile strength, modulus of rupture, creep, shrinkage, and absorption potential (as an indirect indicator of permeability). Also investigated were the effects of test parameters such as mold size, mold material, and end condition. Over 6,300 specimens were cast from approximately 140 mixes over a period of 3 years.

Identifying dielectric and resistive electrode losses in high-density capacitors at radio frequencies

NARCIS (Netherlands)

Tiggelman, M.P.J.; Reimann, K.; Liu, J.; Klee, M.; Keur, W.; Mauczock, R.; Schmitz, Jurriaan; Hueting, Raymond Josephus Engelbart

2008-01-01

A regression-based technique is presented which distinguishes the dielectric loss from the resistive loss of high density planar capacitors in a very wide bandwidth of 0.1–8 GHz. Moreover, the procedure yields useful results if the capacitor deviates from a lumped element model and indicates when

Experimental Characterization of Dielectric Properties in Fluid Saturated Artificial Shales

OpenAIRE

Beloborodov, Roman; Pervukhina, Marina; Han, Tongcheng; Josh, Matthew

2017-01-01

High dielectric contrast between water and hydrocarbons provides a useful method for distinguishing between producible layers of reservoir rocks and surrounding media. Dielectric response at high frequencies is related to the moisture content of rocks. Correlations between the dielectric permittivity and specific surface area can be used for the estimation of elastic and geomechanical properties of rocks. Knowledge of dielectric loss-factor and relaxation frequency in shales is critical for t...

Characterization of concrete properties from dielectric properties using ground penetrating radar

International Nuclear Information System (INIS)

Lai, W.L.; Kou, S.C.; Tsang, W.F.; Poon, C.S.

2009-01-01

This paper presents the experimental results of a study of the relationships between light-weight (LWAC) and normal aggregate concrete (NAC) properties, as well as radar wave properties that are derived by using ground penetrating radar (GPR). The former (LWAC) refers to compressive strength, apparent porosity and saturated density, while the latter (NAC) refers to real part of dielectric permittivity (ε' or real permittivity) and wave energy level (E). Throughout the test period of the newly cast concrete cured for 90 days, the above mentioned material properties gradually changed which can be attributed to the effects of cement hydration, different types of aggregates and initial water to binder ratios. A number of plots describing various properties of concrete such as dielectric, strength and porosity perspectives were established. From these plots, we compare the characteristics of how much and how fast free water was turned to absorbed water in LWAC and NAC. The underlying mechanisms and a mechanistic model are then developed.

Dielectric spectroscopy of watermelons for quality sensing

Science.gov (United States)

Nelson, Stuart O.; Guo, Wen-chuan; Trabelsi, Samir; Kays, Stanley J.

2007-07-01

Dielectric properties of four small-sized watermelon cultivars, grown and harvested to provide a range of maturities, were measured with an open-ended coaxial-line probe and an impedance analyser over the frequency range from 10 MHz to 1.8 GHz. Probe measurements were made on the external surface of the melons and also on tissue samples from the edible internal tissue. Moisture content and soluble solids content (SSC) were measured for internal tissue samples, and SSC (sweetness) was used as the quality factor for correlation with the dielectric properties. Individual dielectric constant and loss factor correlations with SSC were low, but a high correlation was obtained between the SSC and permittivity from a complex-plane plot of dielectric constant and loss factor, each divided by SSC. However, SSC prediction from the dielectric properties by this relationship was not as high as expected (coefficient of determination about 0.4). Permittivity data (dielectric constant and loss factor) for the melons are presented graphically to show their relationships with frequency for the four melon cultivars and for external surface and internal tissue measurements. A dielectric relaxation for the external surface measurements, which may be attributable to a combination of bound water, Maxwell-Wagner, molecular cluster or ion-related effects, is also illustrated. Coefficients of determination for complex-plane plots, moisture content and SSC relationship, and penetration depth are also shown graphically. Further studies are needed for determining the practicality of sensing melon quality from their dielectric properties.

Effect of organo clay on curing, mechanical and dielectric properties of NR/SBR blends

Science.gov (United States)

Ravikumar, K.; Joseph, Reji; Ravichandran, K.

2018-04-01

Natural rubber (NR) and styrene butadiene rubber (SBR) based elastomeric blends reinforced with organically modified Sodium bentonite clay were prepared by two roll mills. Vulcanization parameters such as minimum and maximum torque values scorch and cure times are measured by Oscillating Disc Rheometer. Mechanical properties such as Tensile strength, modulus at 100%, 200% and 300% elongation and elongation at break and Hardness were measured by Universal testing machine and Durometer Shore A hardness meter respectively. Dielectric properties such as dielectric constant (ε’), dissipation factor (tanδ) and volume resistivity (ρv) were measured at room temperature. The curing studies show that torque values are increasing in NR/SBR blends by increase NR content. The scorch and optimum cure time in NR/SBR blends reinforced organo modified clay was found through increase in the SBR content. This may be due to better processing safety of the NR/SBR blends reinforced with organo modified clay. Mechanical properties show that addition of SBR in blends, tensile strength, elongation modulus increases, but 100% modulus slightly increases and no change was observed in Hardness. Dielectric studies show that dielectric constant of NR and SBR rubbers are almost same, it may due to their non-polar nature. But addition of SBR in NR/SBR blend, dielectric constant gradually increases and maximum value observed at 50/50 ratio. But no considerable change was observed in dissipation factor. Frequency dependant resistivity shows that volume resistivity was not changed with respect to frequency up to 3.5 kHz and beyond that the frequency dependence resistivity was found.

Dielectric properties of carbon nanotubes/epoxy composites.

Science.gov (United States)

Peng, Jin-Ping; Zhang, Hui; Tang, Long-Cheng; Jia, Yu; Zhang, Zhong

2013-02-01

Material with high dielectric properties possesses the effect of energy storage and electric field homogenization, which plays an important role in the electrical and electronics domain, especially in the capacitor, electrical machinery and cable realm. In this paper, epoxy-based nanocomposites with high dielectric constant were fabricated by adding pristine and ozone functionalized multi-wall carbon nanotubes (MWCNTs). In the process-related aspect, the favorable technological parameter was obtained via reasonable arrangement and consideration of the dispersing methods including high-speed stirring and three-roller mill. As a result, a uniform dispersion status of MWCNTs in matrix has been guaranteed, which was observed by scanning and transmission electron microscopy. Meanwhile, the influence of different MWCNTs contents and diverse frequencies on the dielectric properties was compared. It was found that the dielectric constant of nano-composites decreased gradually with the increasing of frequency (10(3)-10(6) Hz). Moreover, as the content of MWCNTs increasing, the dielectric constant reached to a maximum of about 1,328 at 10(3) Hz when the pristine MWCNTs content was 0.5 wt.%. Accordingly, the DC conductivity results could interpret the peak value phenomenon by percolation threshold of MWCNTs. In addition, at the fixed content, the dielectric constant of epoxy-based nano-composites with ozone functionalized MWCNTs was lower than that of pristine ones.

A methodology for the preparation of nanoporous polyimide films with low dielectric constants

International Nuclear Information System (INIS)

Jiang Lizhong; Liu Jiugui; Wu Dezhen; Li Hangquan; Jin Riguang

2006-01-01

A method to generate nanoporous polyimide films with low dielectric constants was proposed. The preparation consisted of two steps. Firstly, a polyimide/silica hybrid film was prepared via sol-gel process. Secondly, the hybrid film was treated with hydrofluoric acid to remove the dispersed silica particles, leaving pores with diameters between 20 and 120 nm, depending on the size of silica particles. Both hybrid and porous films were subjected to a variety of characterizations including transmission electron microscopy observation, dielectric constant measurement and tensile strength measurement

Process and Microstructure to Achieve Ultra-high Dielectric Constant in Ceramic-Polymer Composites

Science.gov (United States)

Zhang, Lin; Shan, Xiaobing; Bass, Patrick; Tong, Yang; Rolin, Terry D.; Hill, Curtis W.; Brewer, Jeffrey C.; Tucker, Dennis S.; Cheng, Z.-Y.

2016-01-01

Influences of process conditions on microstructure and dielectric properties of ceramic-polymer composites are systematically studied using CaCu3Ti4O12 (CCTO) as filler and P(VDF-TrFE) 55/45 mol.% copolymer as the matrix by combining solution-cast and hot-pressing processes. It is found that the dielectric constant of the composites can be significantly enhanced–up to about 10 times – by using proper processing conditions. The dielectric constant of the composites can reach more than 1,000 over a wide temperature range with a low loss (tan δ ~ 10−1). It is concluded that besides the dense structure of composites, the uniform distribution of the CCTO particles in the matrix plays a key role on the dielectric enhancement. Due to the influence of the CCTO on the microstructure of the polymer matrix, the composites exhibit a weaker temperature dependence of the dielectric constant than the polymer matrix. Based on the results, it is also found that the loss of the composites at low temperatures, including room temperature, is determined by the real dielectric relaxation processes including the relaxation process induced by the mixing. PMID:27767184

High-cycle electromechanical aging of dielectric elastomer actuators with carbon-based electrodes

Science.gov (United States)

de Saint-Aubin, C. A.; Rosset, S.; Schlatter, S.; Shea, H.

2018-07-01

We present high-cycle aging tests of dielectric elastomer actuators (DEAs) based on silicone elastomers, reporting on the time-evolution of actuation strain and of electrode resistance over millions of cycles. We compare several types of carbon-based electrodes, and for the first time show how the choice of electrode has a dramatic influence on DEA aging. An expanding circle DEA configuration is used, consisting of a commercial silicone membrane with the following electrodes: commercial carbon grease applied manually, solvent-diluted carbon grease applied by stamping (pad printing), loose carbon black powder applied manually, carbon black powder suspension applied by inkjet-printing, and conductive silicone-carbon composite applied by stamping. The silicone-based DEAs with manually applied carbon grease electrodes show the shortest lifetime of less than 105 cycles at 5% strain, while the inkjet-printed carbon powder and the stamped silicone-carbon composite make for the most reliable devices, with lifetimes greater than 107 cycles at 5% strain. These results are valid for the specific dielectric and electrode configurations that were tested: using other dielectrics or electrode formulations would lead to different lifetimes and failure modes. We find that aging (as seen in the change in resistance and in actuation strain versus cycle number) is independent of the actuation frequency from 10 Hz to 200 Hz, and depends on the total accumulated time the DEA spends in an actuated state.

Elaboration and dielectric characterization of a doped ferroelectric ...

African Journals Online (AJOL)

... 1150,1180 and 1200 °C successively to optimize the sintering temperature optimal where the density of the sample is maximum (near theoretical density) and therefore the product has better physical quality. The study of dielectric properties of all samples showed a high permittivity dielectric εr = 18018, low dielectric loss: ...

Note: On the dielectric constant of nanoconfined water

OpenAIRE

Zhang, Chao

2018-01-01

Investigations of dielectric properties of water in nanoconfinement are highly relevant for various applications. Here, using a simple capacitor model, we show that the low dielectric constant of nanoconfined water found in molecular dynamics simulations can be largely explained by the so-called dielectric dead-layer effect known for ferroelectric nanocapacitors.

Formability Characterization of a New Generation High Strength Steels

Energy Technology Data Exchange (ETDEWEB)

Sriram Sadagopan; Dennis Urban; Chris Wong; Mai Huang; Benda Yan

2003-05-16

Advanced high strength steels (AHSS) are being progressively explored by the automotive industry all around the world for cost-effective solutions to accomplish vehicle lightweighting, improve fuel economy, and consequently reduce greenhouse emissions. Because of their inherent high strength, attractive crash energy management properties, and good formability, the effective use of AHSS such as Duel Phase and TRIP (Transformation Induced Plasticity) steels, will significantly contribute to vehicle lightweighting and fuel economy. To further the application of these steels in automotive body and structural parts, a good knowledge and experience base must be developed regarding the press formability of these materials. This project provides data on relevant intrinsic mechanical behavior, splitting limits, and springback behavior of several lots of mild steel, conventional high strength steel (HSS), advanced high strength steel (AHSS) and ultra-high strength steel (UHSS), supplied by the member companies of the Automotive Applications Committee (AAC) of the American Iron and Steel Institute (AISI). Two lots of TRIP600, which were supplied by ThyssenKrupp Stahl, were also included in the study. Since sheet metal forming encompasses a very diverse range of forming processes and deformation modes, a number of simulative tests were used to characterize the forming behavior of these steel grades. In general, it was found that formability, as determined by the different tests, decreased with increased tensile strength. Consistant with previous findings, the formability of TRIP600 was found to be exceptionally good for its tensile strength.

High dielectric permittivity and improved mechanical and thermal properties of poly(vinylidene fluoride) composites with low carbon nanotube content: effect of composite processing on phase behavior and dielectric properties.

Science.gov (United States)

Kumar, G Sudheer; Vishnupriya, D; Chary, K Suresh; Patro, T Umasankar

2016-09-23

The composite processing technique and nanofiller concentration and its functionalization significantly alter the properties of polymer nanocomposites. To realize this, multi-walled carbon nanotubes (CNT) were dispersed in a poly(vinylidene fluoride) (PVDF) matrix at carefully selected CNT concentrations by two illustrious methods, such as solution-cast and melt-mixing. Notwithstanding the processing method, CNTs induced predominantly the γ-phase in PVDF, instead of the commonly obtained β-phase upon nanofiller incorporation, and imparted significant improvements in dielectric properties. Acid-treatment of CNT improved its dispersion and interfacial adhesion significantly with PVDF, and induced a higher γ-phase content and better dielectric properties in PVDF as compared to pristine CNT. Further, the γ-phase content was found to be higher in solution-cast composites than that in melt-mixed counterparts, most likely due to solvent-induced crystallization in a controlled environment and slow solvent evaporation in the former case. However, interestingly, the melt-mixed composites showed a significantly higher dielectric constant at the onset of the CNT networked-structure as compared to the solution-cast composites. This suggests the possible role of CNT breakage during melt-mixing, which might lead to higher space-charge polarization at the polymer-CNT interface, and in turn an increased number of pseudo-microcapacitors in these composites than the solution-cast counterparts. Notably, PVDF with 0.13 vol% (volume fraction, f c  = 0.0013) of acid-treated CNTs, prepared by melt-mixing, displayed the relative permittivity of ∼217 and capacitance of ∼5430 pF, loss tangent of ∼0.4 at 1 kHz and an unprecedented figure of merit of ∼10(5). We suggest a simple hypothesis for the γ-phase formation and evolution of the high dielectric constant in these composites. Further, the high-dielectric composite film showed marked improvements in mechanical and thermal

Comparison of neat and photo-crosslinked polyvinylidene fluoride-co-hexafluoropropylene thin film dielectrics formed by spin-coating

International Nuclear Information System (INIS)

Iyore, O.D.; Roodenko, K.; Winkler, P.S.; Noriega, J.R.; Vasselli, J.J.; Chabal, Y.J.; Gnade, B.E.

2013-01-01

We report the characterization of photo-crosslinked polyvinylidene fluoride-co-hexafluoropropylene (PVDF-HFP) thin film, metal–insulator–metal capacitors fabricated using standard semiconductor processing techniques. We characterize the capacitors using in-situ vibrational spectroscopy during thermally-assisted poling and correlate the Fourier transform infrared spectroscopy (FTIR) results with X-ray diffraction (XRD) results. FTIR analysis of the neat PVDF-HFP showed α → β transformations during poling at room temperature and at 55 °C. α → β transformations were observed for the crosslinked polymer only during poling at 55 °C. XRD data revealed that photo-crosslinking caused the polymer to partially crystallize into the β-phase. The similar behavior of the neat and crosslinked samples at 55 °C suggests that a higher activation energy was needed for α → β transformations in crosslinked PVDF-HFP during poling. Electrical measurements showed that photo-crosslinking had no significant effect on the dielectric constant and dielectric loss of PVDF-HFP. However, the dielectric strength and maximum energy density of the crosslinked polymer were severely reduced. - Highlights: • Polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP) dielectrics were studied. • Phase transformations were observed only at 55 °C for the crosslinked PVDF-HFP. • Crosslinking had no strong effect on the dielectric constant of PVDF-HFP. • Breakdown strengths were 620 MVm −1 and 362 MVm −1 for neat and crosslinked films

High-voltage pulsed life of multistressed polypropylene capacitor dielectric

International Nuclear Information System (INIS)

Laghari, J.R.

1992-01-01

High-voltage polypropylene capacitors were aged under singular as well as simultaneous multiple stresses (electrical, thermal, and radiation) at the University of Buffalo's 2 MW thermal nuclear reactor. These stresses were combined neutron-gamma radiation with a total dose of 1.6 x 10 6 rad, electrical stress at 40 V rms /μm, and thermal stress at 90 degrees C. After exposure, the polypropylene dielectric was tested for life (number of pulses to fail) under high-voltage high-repetition-rate (100 pps) pulses. Pulsed life data were also compared with ac life data. Results show that radiation stress causes the most degradation in life, either acting alone or in combination with other stresses. The largest reduction in life occurs when polypropylene is aged under simultaneous multiple stresses (electrical, thermal, and radiation). In this paper, it is shown that pulsed life can be equivalently compared with ac life

Resonant cavity light-emitting diodes based on dielectric passive cavity structures

Science.gov (United States)

Ledentsov, N.; Shchukin, V. A.; Kropp, J.-R.; Zschiedrich, L.; Schmidt, F.; Ledentsov, N. N.

2017-02-01

A novel design for high brightness planar technology light-emitting diodes (LEDs) and LED on-wafer arrays on absorbing substrates is proposed. The design integrates features of passive dielectric cavity deposited on top of an oxide- semiconductor distributed Bragg reflector (DBR), the p-n junction with a light emitting region is introduced into the top semiconductor λ/4 DBR period. A multilayer dielectric structure containing a cavity layer and dielectric DBRs is further processed by etching into a micrometer-scale pattern. An oxide-confined aperture is further amended for current and light confinement. We study the impact of the placement of the active region into the maximum or minimum of the optical field intensity and study an impact of the active region positioning on light extraction efficiency. We also study an etching profile composed of symmetric rings in the etched passive cavity over the light emitting area. The bottom semiconductor is an AlGaAs-AlAs multilayer DBR selectively oxidized with the conversion of the AlAs layers into AlOx to increase the stopband width preventing the light from entering the semiconductor substrate. The approach allows to achieve very high light extraction efficiency in a narrow vertical angle keeping the reasonable thermal and current conductivity properties. As an example, a micro-LED structure has been modeled with AlGaAs-AlAs or AlGaAs-AlOx DBRs and an active region based on InGaAlP quantum well(s) emitting in the orange spectral range at 610 nm. A passive dielectric SiO2 cavity is confined by dielectric Ta2O5/SiO2 and AlGaAs-AlOx DBRs. Cylindrically-symmetric structures with multiple ring patterns are modeled. It is demonstrated that the extraction coefficient of light to the air can be increased from 1.3% up to above 90% in a narrow vertical angle (full width at half maximum (FWHM) below 20°). For very small oxide-confined apertures 100nm the narrowing of the FWHM for light extraction can be reduced down to 5�

Dielectric inspection of erythrocyte morphology

International Nuclear Information System (INIS)

Hayashi, Yoshihito; Oshige, Ikuya; Katsumoto, Yoichi; Omori, Shinji; Yasuda, Akio; Asami, Koji

2008-01-01

We performed a systematic study of the sensitivity of dielectric spectroscopy to erythrocyte morphology. Namely, rabbit erythrocytes of four different shapes were prepared by precisely controlling the pH of the suspending medium, and their complex permittivities over the frequency range from 0.1 to 110 MHz were measured and analyzed. Their quantitative analysis shows that the characteristic frequency and the broadening parameter of the dielectric relaxation of interfacial polarization are highly specific to the erythrocyte shape, while they are insensitive to the cell volume fraction. Therefore, these two dielectric parameters can be used to differentiate erythrocytes of different shapes, if dielectric spectroscopy is applied to flow-cytometric inspection of single blood cells. In addition, we revealed the applicability and limitations of the analytical theory of interfacial polarization to explain the experimental permittivities of non-spherical erythrocytes

Dielectric inspection of erythrocyte morphology

Energy Technology Data Exchange (ETDEWEB)

Hayashi, Yoshihito; Oshige, Ikuya; Katsumoto, Yoichi; Omori, Shinji; Yasuda, Akio [Life Science Laboratory, Materials Laboratories, Sony Corporation, Sony Bioinformatics Center, Tokyo Medical and Dental University, Bunkyo-ku, Tokyo 113-8510 (Japan); Asami, Koji [Laboratory of Molecular Aggregation Analysis, Division of Multidisciplinary Chemistry, Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011 (Japan)], E-mail: Yoshihito.Hayashi@jp.sony.com

2008-05-21

We performed a systematic study of the sensitivity of dielectric spectroscopy to erythrocyte morphology. Namely, rabbit erythrocytes of four different shapes were prepared by precisely controlling the pH of the suspending medium, and their complex permittivities over the frequency range from 0.1 to 110 MHz were measured and analyzed. Their quantitative analysis shows that the characteristic frequency and the broadening parameter of the dielectric relaxation of interfacial polarization are highly specific to the erythrocyte shape, while they are insensitive to the cell volume fraction. Therefore, these two dielectric parameters can be used to differentiate erythrocytes of different shapes, if dielectric spectroscopy is applied to flow-cytometric inspection of single blood cells. In addition, we revealed the applicability and limitations of the analytical theory of interfacial polarization to explain the experimental permittivities of non-spherical erythrocytes.

Visible-Frequency Dielectric Metasurfaces for Multiwavelength Achromatic and Highly Dispersive Holograms.

Science.gov (United States)

Wang, Bo; Dong, Fengliang; Li, Qi-Tong; Yang, Dong; Sun, Chengwei; Chen, Jianjun; Song, Zhiwei; Xu, Lihua; Chu, Weiguo; Xiao, Yun-Feng; Gong, Qihuang; Li, Yan

2016-08-10

Dielectric metasurfaces built up with nanostructures of high refractive index represent a powerful platform for highly efficient flat optical devices due to their easy-tuning electromagnetic scattering properties and relatively high transmission efficiencies. Here we show visible-frequency silicon metasurfaces formed by three kinds of nanoblocks multiplexed in a subwavelength unit to constitute a metamolecule, which are capable of wavefront manipulation for red, green, and blue light simultaneously. Full phase control is achieved for each wavelength by independently changing the in-plane orientations of the corresponding nanoblocks to induce the required geometric phases. Achromatic and highly dispersive meta-holograms are fabricated to demonstrate the wavefront manipulation with high resolution. This technique could be viable for various practical holographic applications and flat achromatic devices.

The effect of polymer type on electric breakdown strength on a nanosecond time scale

Institute of Scientific and Technical Information of China (English)

Zhao Liang; Su Jian-Cang; Pan Ya-Feng; Zhang Xi-Bo

2012-01-01

Based on the concepts of fast polarization,effective electric field and electron impact ionization criterion,the effect of polymer type on electric breakdown strength (EBD) on a nanosecond time scale is investigated,and a formula that qualitatively characterizes the relation between the electric breakdown strength and the polymer type is derived.According to this formula,it is found that the electric breakdown strength decreases with an increase in the effective relative dielectric constants of the polymers.By calculating the effective relative dielectric constants for different types of polymers,the theoretical relation for the electric breakdown strengths of common polymers is predicted.To verify the prediction,the polymers of PE (polyethylene),PTFE (polytetrafluoroethelene),PMMA (organic glass) and Nylon are tested with a nanosecond-pulse generator.The experimental result shows EBD (PTFE) ＞ EBD (PMMA) ＞ EBD (Nylon) ＞ EBD (PE).This result is consistent with the theoretical prediction.

Fatigue strength of repaired cracks in welded connections made of very high strength steels

NARCIS (Netherlands)

Akyel, A.

2017-01-01

For cyclically loaded structures, fatigue design becomes one of the important design criteria. The state of art shows that with modification of the conventional structural design methodology, the use of very high strength steels may have a positive effect on fatigue strength of welded connections.

A High-Voltage Class D Audio Amplifier for Dielectric Elastomer Transducers

DEFF Research Database (Denmark)

Nielsen, Dennis; Knott, Arnold; Andersen, Michael A. E.

2014-01-01

Dielectric Elastomer (DE) transducers have emerged as a very interesting alternative to the traditional electrodynamic transducer. Lightweight, small size and high maneuverability are some of the key features of the DE transducer. An amplifier for the DE transducer suitable for audio applications...... is proposed and analyzed. The amplifier addresses the issue of a high impedance load, ensuring a linear response over the midrange region of the audio bandwidth (100 Hz – 3.5 kHz). THD+N below 0.1% are reported for the ± 300 V prototype amplifier producing a maximum of 125 Var at a peak efficiency of 95 %....

High energy density capacitors fabricated by thin film technology

International Nuclear Information System (INIS)

Barbee, T W; Johnson, G W; Wagner, A V.

1999-01-01

Low energy density in conventional capacitors severely limits efforts to miniaturize power electronics and imposes design limitations on electronics in general. We have successfully applied physical vapor deposition technology to greatly increase capacitor energy density. The high dielectric breakdown strength we have achieved in alumina thin films allows high energy density to be achieved with this moderately low dielectric constant material. The small temperature dependence of the dielectric constant, and the high reliability, high resistivity, and low dielectric loss of Al 2 O 3 , make it even more appealing. We have constructed single dielectric layer thin film capacitors and shown that they can be stacked to form multilayered structures with no loss in yield for a given capacitance. Control of film growth morphology is critical for achieving the smooth, high quality interfaces between metal and dielectric necessary for device operation at high electric fields. Most importantly, high rate deposition with extremely low particle generation is essential for achieving high energy storage at a reasonable cost. This has been achieved by reactive magnetron sputtering in which the reaction to form the dielectric oxide has been confined to the deposition surface. By this technique we have achieved a yield of over 50% for 1 cm 2 devices with an energy density of 14 J per cubic centimeter of Al 2 O 3 dielectric material in 1.2 kV, 4 nF devices. By further reducing defect density and increasing the dielectric constant of the material, we will be able to increase capacitance and construct high energy density devices to meet the requirements of applications in power electronics

Thermodynamics and instability of dielectric elastomer (Conference Presentation)

Science.gov (United States)

Liu, Liwu; Liu, Yanju; Leng, Jinsong; Mu, Tong

2017-04-01

Dielectric elastomer is a kind of typical soft active material. It can deform obviously when subjected to an external voltage. When a dielectric elastomer with randomly oriented dipoles is subject to an electric field, the dipoles will rotate to and align with the electric field. The polarization of the dielectric elastomer may be saturated when the voltage is high enough. When subjected to a mechanical force, the end-to-end distance of each polymer chain, which has a finite contour length, will approach the finite value, reaching a limiting stretch. On approaching the limiting stretch, the elastomer stiffens steeply. Here, we develop a thermodynamic constitutive model of dielectric elastomers undergoing polarization saturation and strain-stiffening, and then investigate the stability (electromechanical stability, snap-through stability) and voltage induced deformation of dielectric elastomers. Analytical solution has been obtained and it reveals the marked influence of the extension limit and polarization saturation limit on its instability. The developed thermodynamic constitutive model and simulation results would be helpful in future to the research of dielectric elastomer based high-performance transducers.

Low-temperature fabrication of sputtered high-k HfO2 gate dielectric for flexible a-IGZO thin film transistors

Science.gov (United States)

Yao, Rihui; Zheng, Zeke; Xiong, Mei; Zhang, Xiaochen; Li, Xiaoqing; Ning, Honglong; Fang, Zhiqiang; Xie, Weiguang; Lu, Xubing; Peng, Junbiao

2018-03-01

In this work, low temperature fabrication of a sputtered high-k HfO2 gate dielectric for flexible a-IGZO thin film transistors (TFTs) on polyimide substrates was investigated. The effects of Ar-pressure during the sputtering process and then especially the post-annealing treatments at low temperature (≤200 °C) for HfO2 on reducing the density of defects in the bulk and on the surface were systematically studied. X-ray reflectivity, UV-vis and X-ray photoelectron spectroscopy, and micro-wave photoconductivity decay measurements were carried out and indicated that the high quality of optimized HfO2 film and its high dielectric properties contributed to the low concentration of structural defects and shallow localized defects such as oxygen vacancies. As a result, the well-structured HfO2 gate dielectric exhibited a high density of 9.7 g/cm3, a high dielectric constant of 28.5, a wide optical bandgap of 4.75 eV, and relatively low leakage current. The corresponding flexible a-IGZO TFT on polyimide exhibited an optimal device performance with a saturation mobility of 10.3 cm2 V-1 s-1, an Ion/Ioff ratio of 4.3 × 107, a SS value of 0.28 V dec-1, and a threshold voltage (Vth) of 1.1 V, as well as favorable stability under NBS/PBS gate bias and bending stress.

Optimization of silver-dielectric-silver nanoshell for sensing applications

International Nuclear Information System (INIS)

Shirzaditabar, Farzad; Saliminasab, Maryam

2013-01-01

In this paper, resonance light scattering (RLS) properties of a silver-dielectric-silver nanoshell, based on quasi-static approach and plasmon hybridization theory, are investigated. Scattering spectrum of silver-dielectric-silver nanoshell has two intense and clearly separated RLS peaks and provides a potential for biosensing based on surface plasmon resonance and surface-enhanced Raman scattering. The two RLS peaks in silver-dielectric-silver nanoshell are optimized by tuning the geometrical dimensions. In addition, the optimal geometry is discussed to obtain the high sensitivity of silver-dielectric-silver nanoshell. As the silver core radius increases, the sensitivity of silver-dielectric-silver nanoshell decreases whereas increasing the middle dielectric thickness increases the sensitivity of silver-dielectric-silver nanoshell

Thermally switchable dielectrics

Science.gov (United States)

Dirk, Shawn M.; Johnson, Ross S.

2013-04-30

Precursor polymers to conjugated polymers, such as poly(phenylene vinylene), poly(poly(thiophene vinylene), poly(aniline vinylene), and poly(pyrrole vinylene), can be used as thermally switchable capacitor dielectrics that fail at a specific temperature due to the non-conjugated precursor polymer irreversibly switching from an insulator to the conjugated polymer, which serves as a bleed resistor. The precursor polymer is a good dielectric until it reaches a specific temperature determined by the stability of the leaving groups. Conjugation of the polymer backbone at high temperature effectively disables the capacitor, providing a `built-in` safety mechanism for electronic devices.

High-Performance Flexible Single-Crystalline Silicon Nanomembrane Thin-Film Transistors with High- k Nb2O5-Bi2O3-MgO Ceramics as Gate Dielectric on a Plastic Substrate.

Science.gov (United States)

Qin, Guoxuan; Zhang, Yibo; Lan, Kuibo; Li, Lingxia; Ma, Jianguo; Yu, Shihui

2018-04-18

A novel method of fabricating flexible thin-film transistor based on single-crystalline Si nanomembrane (SiNM) with high- k Nb 2 O 5 -Bi 2 O 3 -MgO (BMN) ceramic gate dielectric on a plastic substrate is demonstrated in this paper. SiNMs are successfully transferred to a flexible polyethylene terephthalate substrate, which has been plated with indium-tin-oxide (ITO) conductive layer and high- k BMN ceramic gate dielectric layer by room-temperature magnetron sputtering. The BMN ceramic gate dielectric layer demonstrates as high as ∼109 dielectric constant, with only dozens of pA current leakage. The Si-BMN-ITO heterostructure has only ∼nA leakage current at the applied voltage of 3 V. The transistor is shown to work at a high current on/off ratio of above 10 4 , and the threshold voltage is ∼1.3 V, with over 200 cm 2 /(V s) effective channel electron mobility. Bending tests have been conducted and show that the flexible transistors have good tolerance on mechanical bending strains. These characteristics indicate that the flexible single-crystalline SiNM transistors with BMN ceramics as gate dielectric have great potential for applications in high-performance integrated flexible circuit.

Enhancing breakdown strength and energy storage performance of PVDF-based nanocomposites by adding exfoliated boron nitride

Science.gov (United States)

Xie, Yunchuan; Wang, Jian; Yu, Yangyang; Jiang, Wanrong; Zhang, Zhicheng

2018-05-01

Polymer/ceramic nanocomposites are promising dielectrics for high energy storage density (Ue) capacitors. However, their low breakdown strength (Eb) and high dielectric loss due to heterogeneous structure seriously limit their applications under high electric field. In this work, boron nitride nano-sheets (BNNS) exfoliated from BN particles were introduced into PVDF-based BaTiO3 (mBT) binary composites to reduce the dielectric loss and promote the Ue. The effects of BNNS on the dielectric properties, especially breakdown resistance, and energy storage performance of the resultant composites were carefully investigated by comparing with the composites without BNNS. The introduction of BNNS could significantly improve Eb and Ue of the final composites. Ternary composite with particle contents of 6 wt% BNNS and 5 wt% mBT presented a Eb of about 400 MV/m and Ue of 5.2 J/cm3, which is 40% and 30% superior to that of the binary composite with 5 wt% mBT, respectively. That may be attributed to the 2D structure, high bulk electrical resistivity, and fine dispersion in PVDF of BNNS, which is acting as an efficient insulating barrier against the leakage current and charges conduction. The depression effect of BNNS onto the charge mobility and the interfacial polarization of the polymer composites is finely addressed, which may offer a promising strategy for the fabrication of high-k polymer composites with low loss.

Graphene/Pentacene Barristor with Ion-Gel Gate Dielectric: Flexible Ambipolar Transistor with High Mobility and On/Off Ratio.

Science.gov (United States)

Oh, Gwangtaek; Kim, Jin-Soo; Jeon, Ji Hoon; Won, EunA; Son, Jong Wan; Lee, Duk Hyun; Kim, Cheol Kyeom; Jang, Jingon; Lee, Takhee; Park, Bae Ho

2015-07-28

High-quality channel layer is required for next-generation flexible electronic devices. Graphene is a good candidate due to its high carrier mobility and unique ambipolar transport characteristics but typically shows a low on/off ratio caused by gapless band structure. Popularly investigated organic semiconductors, such as pentacene, suffer from poor carrier mobility. Here, we propose a graphene/pentacene channel layer with high-k ion-gel gate dielectric. The graphene/pentacene device shows both high on/off ratio and carrier mobility as well as excellent mechanical flexibility. Most importantly, it reveals ambipolar behaviors and related negative differential resistance, which are controlled by external bias. Therefore, our graphene/pentacene barristor with ion-gel gate dielectric can offer various flexible device applications with high performances.

Behavior of Rubber Materials under Exposure to High Electric Fields

DEFF Research Database (Denmark)

Candela Garolera, Anna; Holbøll, Joachim; Henriksen, M,

2013-01-01

The effect of high electrical stress on rubber materials is investigated by performing breakdown tests and tracking resistance tests on selected samples. The study is focused on the relationship between the dielectric strength and the thickness of the samples, as well as the influence of the inte......The effect of high electrical stress on rubber materials is investigated by performing breakdown tests and tracking resistance tests on selected samples. The study is focused on the relationship between the dielectric strength and the thickness of the samples, as well as the influence...... of the interfaces between different layers of material. Tracking resistance tests are also performed on the rubber material. The purpose is to provide a complete study of the applicability of the rubber material in thunderstorm environments....

Dielectric silicone elastomers with mixed ceramic nanoparticles

International Nuclear Information System (INIS)

Stiubianu, George; Bele, Adrian; Cazacu, Maria; Racles, Carmen; Vlad, Stelian; Ignat, Mircea

2015-01-01

Highlights: • Composite ceramics nanoparticles (MCN) with zirconium dioxide and lead zirconate. • Dielectric elastomer films wDith PDMS matrix and MCN as dielectric filler. • Hydrophobic character—water resistant and good flexibility specific to siloxanes. • Increased value of dielectric constant with the content of MCN in dielectric films. • Increased energy output from uniaxial deformation of the dielectric elastomer films. - Abstract: A ceramic material consisting in a zirconium dioxide-lead zirconate mixture has been obtained by precipitation method, its composition being proved by wide angle X-ray powder diffraction and energy-dispersive X-ray spectroscopy. The average diameter of the ceramic particles ranged between 50 and 100 nm, as revealed by transmission electron microscopy images. These were surface treated and used as filler for a high molecular mass polydimethylsiloxane-α,ω-diol (Mn = 450,000) prepared in laboratory, the resulted composites being further processed as films and crosslinked. A condensation procedure, unusual for polydimethylsiloxane having such high molecular mass, with a trifunctional silane was approached for the crosslinking. The effect of filler content on electrical and mechanical properties of the resulted materials was studied and it was found that the dielectric permittivity of nanocomposites increased in line with the concentration of ceramic nanoparticles

Dielectric silicone elastomers with mixed ceramic nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Stiubianu, George, E-mail: george.stiubianu@icmpp.ro [“Petru Poni” Institute of Macromolecular Chemistry, Aleea Gr. Ghica Voda 41A, Iasi 700487 (Romania); Bele, Adrian; Cazacu, Maria; Racles, Carmen; Vlad, Stelian [“Petru Poni” Institute of Macromolecular Chemistry, Aleea Gr. Ghica Voda 41A, Iasi 700487 (Romania); Ignat, Mircea [National R& D Institute for Electrical Engineering ICPE-CA Bucharest, Splaiul Unirii 313, District 3, Bucharest 030138 (Romania)

2015-11-15

Highlights: • Composite ceramics nanoparticles (MCN) with zirconium dioxide and lead zirconate. • Dielectric elastomer films wDith PDMS matrix and MCN as dielectric filler. • Hydrophobic character—water resistant and good flexibility specific to siloxanes. • Increased value of dielectric constant with the content of MCN in dielectric films. • Increased energy output from uniaxial deformation of the dielectric elastomer films. - Abstract: A ceramic material consisting in a zirconium dioxide-lead zirconate mixture has been obtained by precipitation method, its composition being proved by wide angle X-ray powder diffraction and energy-dispersive X-ray spectroscopy. The average diameter of the ceramic particles ranged between 50 and 100 nm, as revealed by transmission electron microscopy images. These were surface treated and used as filler for a high molecular mass polydimethylsiloxane-α,ω-diol (Mn = 450,000) prepared in laboratory, the resulted composites being further processed as films and crosslinked. A condensation procedure, unusual for polydimethylsiloxane having such high molecular mass, with a trifunctional silane was approached for the crosslinking. The effect of filler content on electrical and mechanical properties of the resulted materials was studied and it was found that the dielectric permittivity of nanocomposites increased in line with the concentration of ceramic nanoparticles.

Influence of Water Absorption on Volume Resistivity and the Dielectric Properties of Neat Epoxy Material

KAUST Repository

Sulaimani, Anwar Ali

2014-07-15

Influence of Water Absorption on the Dielectric Properties and Volume Resistivity of Neat Epoxy Material Anwar Ali Sulaimani Epoxy resins are widely used materials in the industry as electrical insulators, adhesives and in aircrafts structural components because of their high mechanical sti ness, strength and high temperature and chemical resistance properties. But still, the in uence of water uptake due to moisture adsorption is not fully understood as it detrimentally modi es the electrical and chemical properties of the material. Here, we investigate the in uence of water moisture uptake on the neat epoxy material by monitoring the change in the volume resistivity and dielectric properties of epoxy material at three di erent thickness con gurations: 0.250 mm, 0.50 mm and 1 mm thicknesses. Gravimetric analysis was done to monitor the mass uptake behaviour, Volume Resistivity was measured to monitor the change in conductivity of the material, and the dielectric properties were mapped to characterise the type of water mechanism available within the material during two ageing processes of sorption and desorption. Two-stage behaviours of di usion and reaction have been identi ed by the mass uptake analysis. Moreover, the plot of volume resistivity versus mass uptake has indi- cated a non-uniform relationship between the two quantities. However, the analysis of the dielectric spectrum at medium range of frequency and time has showed a change 5 in the dipolar activities and also showed the extent to which the water molecules can be segregated between bounding to the resin or existing as free water.

Advanced high strength steels for automotive industry

Energy Technology Data Exchange (ETDEWEB)

Galan, J.; Samek, L.; Verleysen, P.; Verbeken, K.; Houbert, Y.

2012-11-01

The car industry is facing pressure because of the growing demand for more fuel-efficient passenger cars. In order to limit energy consumption and air pollution the weight of the car body has to be reduced. At the same time, high levels of safety have to be guaranteed. In this situation, the choice of material becomes a key decision in car design. As a response to the requirements of the automotive sector, high strength steels and advanced high strength steels have been developed by the steel industry. These modern steel grades offer an excellent balance of low cost, light weight and mechanical properties. (Author) 48 refs.

Engineering Performance of High Strength Concrete Containing Steel Fibre Reinforcement

Directory of Open Access Journals (Sweden)

Md Azree Othuman Mydin

2013-09-01

Full Text Available The development and utilization of the high strength concrete in the construction industry have been increasing rapidly. Fiber reinforced concrete is introduced to overcome the weakness of the conventional concrete because concrete normally can crack under a low tensile force and it is known to be brittle. Steel fibre is proved to be the popular and best combination in the high strength concrete to result the best in the mechanical and durability properties of high strength concrete with consideration of curing time, steel fibre geometry, concrete grade and else more. The incorporation of steel fibre in the mortar mixture is known as steel fibre reinforced concrete have the potential to produce improvement in the workability, strength, ductility and the deformation of high strength concrete. Besides that, steel fibre also increases the tensile strength of concrete and improves the mechanical properties of the steel fibre reinforced concrete. The range for any high strength concrete is between 60MPa-100MPa. Steel fibre reinforced concrete which contains straight fibres has poorer physical properties than that containing hooked end stainless steel fibre due to the length and the hooked steel fibre provide a better effective aspects ratio. Normally, steel fibre tensile strength is in the range of 1100MPa-1700MPa. Addition of less steel fibre volumes in the range of 0.5% to 1.0% can produce better increase in the flexural fatigue strength. The strength can be increased with addition of steel fibre up to certain percentage. This paper will review and present some basic properties of steel fibre reinforced concrete such as mechanical, workability and durability properties.

Thermally Stable Siloxane Hybrid Matrix with Low Dielectric Loss for Copper-Clad Laminates for High-Frequency Applications.

Science.gov (United States)

Kim, Yong Ho; Lim, Young-Woo; Kim, Yun Hyeok; Bae, Byeong-Soo

2016-04-06

We report vinyl-phenyl siloxane hybrid material (VPH) that can be used as a matrix for copper-clad laminates (CCLs) for high-frequency applications. The CCLs, with a VPH matrix fabricated via radical polymerization of resin blend consisting of sol-gel-derived linear vinyl oligosiloxane and bulky siloxane monomer, phenyltris(trimethylsiloxy)silane, achieve low dielectric constant (Dk) and dissipation factor (Df). The CCLs with the VPH matrix exhibit excellent dielectric performance (Dk = 2.75, Df = 0.0015 at 1 GHz) with stability in wide frequency range (1 MHz to 10 GHz) and at high temperature (up to 275 °C). Also, the VPH shows good flame resistance without any additives. These results suggest the potential of the VPH for use in high-speed IC boards.

Perfect coupling of light to a periodic dielectric/metal/dielectric structure

Science.gov (United States)

Wang, Zhengling; Li, Shiqiang; Chang, R. P. H.; Ketterson, John B.

2014-07-01

Using the finite difference time domain method, it is demonstrated that perfect coupling can be achieved between normally incident light and a periodic dielectric/metal/dielectric structure. The structure serves as a diffraction grating that excites modes related to the long range surface plasmon and short range surface plasmon modes that propagate on continuous metallic films. By optimizing the structural dimensions, perfect coupling is achieved between the incident light and these modes. A high Q of 697 and an accompanying ultrasharp linewidth of 0.8 nm are predicted for a 10 nm silver film for optimal conditions.

Infrared gas phase study on plasma-polymer interactions in high-current diffuse dielectric barrier discharge

NARCIS (Netherlands)

Liu, Y.; Welzel, S.; Starostin, S. A.; van de Sanden, M. C. M.; Engeln, R.; de Vries, H. W.

2017-01-01

A roll-to-roll high-current diffuse dielectric barrier discharge at atmospheric pressure was operated in air and Ar/N2/O2 gas mixtures. The exhaust gas from the discharge was studied using a high-resolution Fourier-transform infrared spectrometer in the range from 3000 to 750?cm-1 to unravel the

Weld Design, Testing, and Assessment Procedures for High Strength Pipelines

Science.gov (United States)

2011-12-20

Long-distance high-strength pipelines are increasingly being constructed for the efficient transportation of energy products. While the high-strength linepipe steels and high productivity welding processes are being applied, the procedures employed f...

Thermosetting resins with high fractions of free volume and inherently low dielectric constants.

Science.gov (United States)

Lin, Liang-Kai; Hu, Chien-Chieh; Su, Wen-Chiung; Liu, Ying-Ling

2015-08-18

This work demonstrates a new class of thermosetting resins, based on Meldrum's acid (MA) derivatives, which have high fractions of free volume and inherently low k values of about 2.0 at 1 MHz. Thermal decomposition of the MA groups evolves CO2 and acetone to create air-trapped cavities so as to reduce the dielectric constants.

Experimental Characterization of Dielectric Properties in Fluid Saturated Artificial Shales

Directory of Open Access Journals (Sweden)

Roman Beloborodov

2017-01-01

Full Text Available High dielectric contrast between water and hydrocarbons provides a useful method for distinguishing between producible layers of reservoir rocks and surrounding media. Dielectric response at high frequencies is related to the moisture content of rocks. Correlations between the dielectric permittivity and specific surface area can be used for the estimation of elastic and geomechanical properties of rocks. Knowledge of dielectric loss-factor and relaxation frequency in shales is critical for the design of techniques for effective hydrocarbon extraction and production from unconventional reservoirs. Although applicability of dielectric measurements is intriguing, the data interpretation is very challenging due to many factors influencing the dielectric response. For instance, dielectric permittivity is determined by mineralogical composition of solid fraction, volumetric content and composition of saturating fluid, rock microstructure and geometrical features of its solid components and pore space, temperature, and pressure. In this experimental study, we investigate the frequency dependent dielectric properties of artificial shale rocks prepared from silt-clay mixtures via mechanical compaction. Samples are prepared with various clay contents and pore fluids of different salinity and cation compositions. Measurements of dielectric properties are conducted in two orientations to investigate the dielectric anisotropy as the samples acquire strongly oriented microstructures during the compaction process.

Survey of Processing Methods for High Strength High Conductivity Wires for High Field Magnet Applications

Energy Technology Data Exchange (ETDEWEB)

Han, K.; Embury, J.D.

1998-10-01

This paper will deal with the basic concepts of attaining combination of high strength and high conductivity in pure materials, in-situ composites and macrocomposites. It will survey current attainments, and outline where some future developments may lie in developing wire products that are close to the theoretical strength of future magnet applications.

Survey of Processing Methods for High Strength High Conductivity Wires for High Field Magnet Applications

International Nuclear Information System (INIS)

Han, K.; Embury, J.D.

1998-01-01

This paper will deal with the basic concepts of attaining combination of high strength and high conductivity in pure materials, in-situ composites and macrocomposites. It will survey current attainments, and outline where some future developments may lie in developing wire products that are close to the theoretical strength of future magnet applications

Measurement of surface charges on the dielectric film based on field mills under the HVDC corona wire

Science.gov (United States)

Donglai, WANG; Tiebing, LU; Yuan, WANG; Bo, CHEN; Xuebao, LI

2018-05-01

The ion flow field on the ground is one of the significant parameters used to evaluate the electromagnetic environment of high voltage direct current (HVDC) power lines. HVDC lines may cross the greenhouses due to the restricted transmission corridors. Under the condition of ion flow field, the dielectric films on the greenhouses will be charged, and the electric fields in the greenhouses may exceed the limit value. Field mills are widely used to measure the ground-level direct current electric fields under the HVDC power lines. In this paper, the charge inversion method is applied to calculate the surface charges on the dielectric film according to the measured ground-level electric fields. The advantages of hiding the field mill probes in the ground are studied. The charge inversion algorithm is optimized in order to decrease the impact of measurement errors. Based on the experimental results, the surface charge distribution on a piece of quadrate dielectric film under a HVDC corona wire is studied. The enhanced effect of dielectric film on ground-level electric field is obviously weakened with the increase of film height. Compared with the total electric field strengths, the normal components of film-free electric fields at the corresponding film-placed positions have a higher effect on surface charge accumulation.

Materials Fundamentals of Gate Dielectrics

CERN Document Server

Demkov, Alexander A

2006-01-01

This book presents materials fundamentals of novel gate dielectrics that are being introduced into semiconductor manufacturing to ensure the continuous scalling of the CMOS devices. This is a very fast evolving field of research so we choose to focus on the basic understanding of the structure, thermodunamics, and electronic properties of these materials that determine their performance in device applications. Most of these materials are transition metal oxides. Ironically, the d-orbitals responsible for the high dielectric constant cause sever integration difficulties thus intrinsically limiting high-k dielectrics. Though new in the electronics industry many of these materials are wel known in the field of ceramics, and we describe this unique connection. The complexity of the structure-property relations in TM oxides makes the use of the state of the art first-principles calculations necessary. Several chapters give a detailed description of the modern theory of polarization, and heterojunction band discont...

Dielectric and photo-dielectric properties of TlGaSeS crystals

Indian Academy of Sciences (India)

Administrator

cDepartment of Physics, Middle East Technical University, 06800 Ankara, Turkey. MS received ... The crystals are observed to exhibit a dark high frequency effective dielectric constant value of ~ 10\\65 x ... communication systems. Keywords.

Optimisation of Silicone-based Dielectric Elastomer Transducers by Means of Block Copolymers - Synthesis and Compounding

DEFF Research Database (Denmark)

A Razak, Aliff Hisyam

through the use of a multi-walled carbon nanotube (MWCNT) in a PDMS-PEG matrix as a compliant electrode of dielectric elastomers. The conductive PDMS-PEG copolymer was incorporated with surface-treated MWCNT, in order to obtain highly conductive elastomer. The prepared sample with 4 parts per hundred...... enhancing the electrical breakdown strength of silicone by using an aromatic voltage stabiliser. Here, polyphenylmethylsiloxane (PPMS), which contained aromatic voltage stabilisers, was bonded covalently to PDMS through a hydrosilylation reaction obtaining PDMS-PPMS copolymers. The synthesised copolymers...

Improved Dielectric Properties and Energy Storage Density of Poly(vinylidene fluoride-co-hexafluoropropylene) Nanocomposite with Hydantoin Epoxy Resin Coated BaTiO3.

Science.gov (United States)

Luo, Hang; Zhang, Dou; Jiang, Chao; Yuan, Xi; Chen, Chao; Zhou, Kechao

2015-04-22

Energy storage materials are urgently demanded in modern electric power supply and renewable energy systems. The introduction of inorganic fillers to polymer matrix represents a promising avenue for the development of high energy density storage materials, which combines the high dielectric constant of inorganic fillers with supernal dielectric strength of polymer matrix. However, agglomeration and phase separation of inorganic fillers in the polymer matrix remain the key barriers to promoting the practical applications of the composites for energy storage. Here, we developed a low-cost and environmentally friendly route to modifying BaTiO3 (BT) nanoparticles by a kind of water-soluble hydantoin epoxy resin. The modified BT nanoparticles exhibited homogeneous dispersion in the ferroelectric polymer poly(vinylidene fluoride-co-hexafluoropropylene) (P(VDF-HFP)) matrix and strong interfacial adhesion with the polymer matrix. The dielectric constants of the nanocomposites increased significantly with the increase of the coated BT loading, while the dielectric loss of the nanocomposites was still as low as that of the pure P(VDF-HFP). The energy storage density of the nanocomposites was largely enhanced with the coated BT loading at the same electric field. The nanocomposite with 20 vol % BT exhibited an estimated maximum energy density of 8.13 J cm(-3), which was much higher than that of pure P(VDF-HFP) and other dielectric polymers. The findings of this research could provide a feasible approach to produce high energy density materials for practical application in energy storage.

SUCCESS AND PITFALLS OF THE DIELECTRIC CONTINUUM MODEL IN QUANTUM-CHEMICAL CALCULATIONS

NARCIS (Netherlands)

DEVRIES, AH; VANDUIJNEN, PT; JUFFER, AH

1993-01-01

Recently we presented an extension of the direct reaction field (DRF) method, in which a quantum system and a set of point charges and interacting polarizabilities are embedded in a continuum that is characterized by a dielectric constant epsilon and a finite ionic strength. The reaction field of

Dielectric properties of hybrid perovskites and drift-diffusion modeling of perovskite cells

Science.gov (United States)

Pedesseau, L.; Kepenekian, M.; Sapori, D.; Huang, Y.; Rolland, A.; Beck, A.; Cornet, C.; Durand, O.; Wang, S.; Katan, C.; Even, J.

2016-03-01

A method based on DFT is used to obtained dielectric profiles. The high frequency Ɛ∞(z) and the static Ɛs(z) dielectric profiles are compared for 3D, 2D-3D and 2D Hybrid Organic Perovskites (HOP). A dielectric confinement is observed for the 2D materials between the high dielectric constant of the inorganic part and the low dielectric constant of the organic part. The effect of the ionic contribution on the dielectric constant is also shown. The quantum and dielectric confinements of 3D HOP nanoplatelets are then reported. Finally, a numerical simulation based on the SILVACO code of a HOP based solar cell is proposed for various permittivity of MAPbI3.

Numerical Model of High Strength Concrete

Science.gov (United States)

Wang, R. Z.; Wang, C. Y.; Lin, Y. L.

2018-03-01

The purpose of this paper is to present a three-dimensional constitutive model based on the concept of equivalent uniaxial strain. closed Menetrey-Willam (CMW) failure surfaces which combined with Menetrey-Willam meridian and the cap model are introduced in this paper. Saenz stress-strain model is applied and adjusted by the ultimate strength parameters from CMW failure surface to reflect the latest stress or strain condition. The high strength concrete (HSC) under tri-axial non-proportional loading is considered and the model in this paper performed a good prediction.

Atomic layer deposition of dielectrics for carbon-based electronics

Energy Technology Data Exchange (ETDEWEB)

Kim, J., E-mail: jiyoung.kim@utdallas.edu; Jandhyala, S.

2013-11-01

Carbon based nanomaterials like nanotubes and graphene have emerged as future generation electronic materials for device applications because of their interesting properties such as high-mobility and ability to carry high-current densities compared to conventional semiconductor materials like silicon. Therefore, there is a need to develop techniques to integrate robust gate dielectrics with high-quality interfaces for these materials in order to attain maximum performance. To date, a variety of methods including physical vapor deposition, atomic layer deposition (ALD), physical assembly among others have been employed in order to integrate dielectrics for carbon nanotube and graphene based field-effect transistors. Owing to the difficulty in wetting pristine surfaces of nanotubes and graphene, most of the ALD methods require a seeding technique involving non-covalent functionalization of their surfaces in order to nucleate dielectric growth while maintaining their intrinsic properties. A comprehensive review regarding the various dielectric integration schemes for emerging devices and their limitations with respect to ALD based methods along with a future outlook is provided. - Highlights: • We introduce various dielectric integration schemes for carbon-based devices. • Physical vapor deposition methods tend to degrade device performance. • Atomic layer deposition on pristine surfaces of graphene and nanotube is difficult. • We review different seeding techniques for atomic layer deposition of dielectrics. • Compare the performance of graphene top-gate devices with different dielectrics.

Atomic layer deposition of dielectrics for carbon-based electronics

International Nuclear Information System (INIS)

Kim, J.; Jandhyala, S.

2013-01-01

Carbon based nanomaterials like nanotubes and graphene have emerged as future generation electronic materials for device applications because of their interesting properties such as high-mobility and ability to carry high-current densities compared to conventional semiconductor materials like silicon. Therefore, there is a need to develop techniques to integrate robust gate dielectrics with high-quality interfaces for these materials in order to attain maximum performance. To date, a variety of methods including physical vapor deposition, atomic layer deposition (ALD), physical assembly among others have been employed in order to integrate dielectrics for carbon nanotube and graphene based field-effect transistors. Owing to the difficulty in wetting pristine surfaces of nanotubes and graphene, most of the ALD methods require a seeding technique involving non-covalent functionalization of their surfaces in order to nucleate dielectric growth while maintaining their intrinsic properties. A comprehensive review regarding the various dielectric integration schemes for emerging devices and their limitations with respect to ALD based methods along with a future outlook is provided. - Highlights: • We introduce various dielectric integration schemes for carbon-based devices. • Physical vapor deposition methods tend to degrade device performance. • Atomic layer deposition on pristine surfaces of graphene and nanotube is difficult. • We review different seeding techniques for atomic layer deposition of dielectrics. • Compare the performance of graphene top-gate devices with different dielectrics

The assessment of bond strength between heat damaged concrete and high strength fibre reinforced concrete

Science.gov (United States)

Zahid, M. Z. A. Mohd; Muhamad, K.

2017-09-01

The aim of this study is to assess the bond strength between heat damaged concrete and high strength fibre reinforced concrete (HPFRC). Firstly, this paper presents the various steps taken to prepare the HPFRC with self-compacting property. The minimum targeted slump flow is 600 mm and minimum targeted compressive strength is 80 MPa. The key mix variables considered are such as type of superplasticizer, water cement ratio and silica fume content. Then, the bond strength between the heat damaged concrete with HPFRC was examined. The experimental parameters are heating temperature, surface treatment technique and curing method and the results show that, all experimental parameters are significantly affected the bond strength between heat damaged concrete and HPFRC.

Polymethyl methacrylate (PMMA)-bismuth ferrite (BFO) nanocomposite: low loss and high dielectric constant materials with perceptible magnetic properties.

Science.gov (United States)

Tamboli, Mohaseen S; Palei, Prakash K; Patil, Santosh S; Kulkarni, Milind V; Maldar, Noormahmad N; Kale, Bharat B

2014-09-21

Herein, poly(methyl methacrylate)-bismuth ferrite (PMMA-BFO) nanocomposites were successfully prepared by an in situ polymerization method for the first time. Initially, the as prepared bismuth ferrite (BFO) nanoparticles were dispersed in the monomer, (methyl methacrylate) by sonication. Benzoyl peroxide was used to initiate the polymerization reaction in ethyl acetate medium. The nanocomposite films were subjected to X-ray diffraction analysis (XRD), (1)H NMR, field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), atomic force microscopy (AFM), thermogravimetric analysis (TGA), infrared spectroscopy (IR), dielectric and magnetic characterizations. The dielectric measurement of the nanocomposites was investigated at a frequency range of 10 Hz to 1 MHz. It was found that the nanocomposites not only showed a significantly increased value of the dielectric constant with an increase in the loading percentage of BFO as compared to pure PMMA, but also exhibited low dielectric loss values over a wide range of frequencies. The values of the dielectric constant and dielectric loss of the PMMA-BFO5 (5% BFO loading) sample at 1 kHz frequency was found be ~14 and 0.037. The variation of the ferromagnetic response of the nanocomposite was consistent with the varying volume percentage of the nanoparticles. The remnant magnetization (Mr) and saturation magnetization (Ms) values of the composites were found to be enhanced by increasing the loading percentage of BFO. The value of Ms for PMMA-BFO5 was found to be ~6 emu g(-1). The prima facie observations suggest that the nanocomposite is a potential candidate for application in high dielectric constant capacitors. Significantly, based on its magnetic properties the composite will also be useful for use in hard disk components.

Temperature dependence of the dielectric properties of rubber wood

Science.gov (United States)

Mohammed Firoz Kabir; Wan M. Daud; Kaida B. Khalid; Haji A.A. Sidek

2001-01-01

The effect of temperature on the dielectric properties of rubber wood was investigated in three anisotropic directions—longitudinal, radial, and tangential, and at different measurement frequencies. Low frequency measurements were conducted with a dielectric spectrometer, and high frequencies used microwave applied with open-ended coaxial probe sensors. Dielectric...

Comparison of neat and photo-crosslinked polyvinylidene fluoride-co-hexafluoropropylene thin film dielectrics formed by spin-coating

Energy Technology Data Exchange (ETDEWEB)

Iyore, O.D.; Roodenko, K.; Winkler, P.S. [Materials Science and Engineering Department, The University of Texas at Dallas, Richardson, TX 75080 (United States); Noriega, J.R.; Vasselli, J.J. [Electrical Engineering Department, The University of Texas at Tyler, Tyler, TX 75799 (United States); Chabal, Y.J. [Materials Science and Engineering Department, The University of Texas at Dallas, Richardson, TX 75080 (United States); Gnade, B.E., E-mail: gnade@utdallas.edu [Materials Science and Engineering Department, The University of Texas at Dallas, Richardson, TX 75080 (United States)

2013-12-02

We report the characterization of photo-crosslinked polyvinylidene fluoride-co-hexafluoropropylene (PVDF-HFP) thin film, metal–insulator–metal capacitors fabricated using standard semiconductor processing techniques. We characterize the capacitors using in-situ vibrational spectroscopy during thermally-assisted poling and correlate the Fourier transform infrared spectroscopy (FTIR) results with X-ray diffraction (XRD) results. FTIR analysis of the neat PVDF-HFP showed α → β transformations during poling at room temperature and at 55 °C. α → β transformations were observed for the crosslinked polymer only during poling at 55 °C. XRD data revealed that photo-crosslinking caused the polymer to partially crystallize into the β-phase. The similar behavior of the neat and crosslinked samples at 55 °C suggests that a higher activation energy was needed for α → β transformations in crosslinked PVDF-HFP during poling. Electrical measurements showed that photo-crosslinking had no significant effect on the dielectric constant and dielectric loss of PVDF-HFP. However, the dielectric strength and maximum energy density of the crosslinked polymer were severely reduced. - Highlights: • Polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP) dielectrics were studied. • Phase transformations were observed only at 55 °C for the crosslinked PVDF-HFP. • Crosslinking had no strong effect on the dielectric constant of PVDF-HFP. • Breakdown strengths were 620 MVm{sup −1} and 362 MVm{sup −1} for neat and crosslinked films.

High-strength beryllium block

International Nuclear Information System (INIS)

Pinto, N.P.; Keith, G.H.

1977-01-01

Beryllium billets hot isopressed using fine powder of high purity have exceptionally attractive properties; average tensile ultimate, 0.2% offset yield strength and elongation are 590 MPa, 430 MPa and 4.0% respectively. Properties are attributed to the fine grain size (about 4.0 μm average diameter) and the relatively low levels of BeO present as fine, well-dispersed particles. Dynamic properties, e.g., fracture toughness, are similar to those of standard grade, high-purity beryllium. The modulus of beryllium is retained to very high stress levels, and the microyield stress or precision elastic limit is higher than for other grades, including instrument grades. Limited data for billets made from normal-purity fine powders show similar room temperature properties. (author)

''Z'' Facility Dielectric Oil Clean-Up

International Nuclear Information System (INIS)

Alessandri, Daniel; Bloomquist, Doug; Donovan, Guy; Feltz, Greg; Grelle, Nibby; Guthrie, Doug; Harris, Mark; Horry, Mike; Lockas, Mike; Potter, Jimmy; Pritchard, Chuck; Steedly, Jim.

1999-01-01

In August of 1998 the Z facility leaked approximately 150 gallons of deionized water into the dielectric oil of the Energy Storage Section (ESS). After processing the oil to remove existing particulate and free water the dielectric breakdown strength increased from the mid 20kV range to values in excess of 40 kV. 40 kV is above historical operating levels of about 35 kV. This, however, was not enough to allow 90 kV charging of the Marx Generators in the ESS. Further analysis of the oil showed dissolved water at a saturated level (70 - 80 ppm) and some residual particulate contamination smaller than 3 microns. The dissolved water and particulate combination was preventing the 90 kV charging of the Marx Generators in the ESS. After consulting with the oil industry it was determined that nitrogen sparging could be used to remove the dissolved water. Further particulate filtering was also conducted. After approximately 20 hours of sparging the water content in the ESS was reduced to 42 ppm which enabled Marx charging to 90 kV

Crystallization of high-strength nano-scale leucite glass-ceramics.

Science.gov (United States)

Theocharopoulos, A; Chen, X; Wilson, R M; Hill, R; Cattell, M J

2013-11-01

Fine-grained, high strength, translucent leucite dental glass-ceramics are synthesized via controlled crystallization of finely milled glass powders. The objectives of this study were to utilize high speed planetary milling of an aluminosilicate glass for controlled surface crystallization of nano-scale leucite glass-ceramics and to test the biaxial flexural strength. An aluminosilicate glass was synthesized, attritor or planetary milled and heat-treated. Glasses and glass-ceramics were characterized using particle size analysis, X-ray diffraction and scanning electron microscopy. Experimental (fine and nanoscale) and commercial (Ceramco-3, IPS Empress Esthetic) leucite glass-ceramics were tested using the biaxial flexural strength (BFS) test. Gaussian and Weibull statistics were applied. Experimental planetary milled glass-ceramics showed an increased leucite crystal number and nano-scale median crystal sizes (0.048-0.055 μm(2)) as a result of glass particle size reduction and heat treatments. Experimental materials had significantly (p0.05) strength difference. All other groups' mean BFS and characteristic strengths were found to be significantly different (pglass-ceramics with high flexural strength. These materials may help to reduce problems associated with brittle fracture of all-ceramic restorations and give reduced enamel wear. Copyright © 2013 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Energy storage in ceramic dielectrics

International Nuclear Information System (INIS)

Love, G.R.

1990-01-01

Historically, multilayer ceramic capacitors (MLC's) have not been considered for energy storage applications for two primary reasons. First, physically large ceramic capacitors were very expensive and, second, total energy density obtainable was not nearly so high as in electrolytic capacitor types. More recently, the fabrication technology for MLC's has improved significantly, permitting both significantly higher energy density and significantly lower costs. Simultaneously, in many applications, total energy storage has become smaller, and the secondary requirements of very low effective series resistance and effective series inductance (which, together, determine how efficiently the energy may be stored and recovered) have become more important. It is therefore desirable to reexamine energy storage in ceramics for contemporary commercial and near-commercial dielectrics. Stored energy is proportional to voltage squared only in the case of paraelectric insulators, because only they have capacitance that is independent of bias voltage. High dielectric constant materials, however, are ferroics (that is ferroelectric and/or antiferroelectric) and display significant variation of effective dielectric constant with bias voltage

High performance unipolar inverters by utilizing organic field-effect transistors with ultraviolet/ozone treated polystyrene dielectric

International Nuclear Information System (INIS)

Huang, Wei; Yu, Xinge; Fan, Huidong; Yu, Junsheng

2014-01-01

High performance unipolar inverters based on a significant variation of threshold voltage (V th ) of organic field-effect transistors (OFETs), which was realized by introducing UV/ozone (UVO) treatment to polystyrene (PS) dielectric, were fabricated. A controllable V th shift of more than 10 V was obtained in the OFETs by adjusting the UVO treating time, and the unipolar inverters exhibited inverting voltage near 1/2 driving voltage and a noise margin of more than 70% of ideal value. From the analysis of scanning electron microscopy, atom force microscopy, and X-ray photoelectron spectroscopy, the dramatic controllable V th of OFETs, which played a key role in high performance unipolar inverters, was attributed to the newly generated oxygen functional groups in the PS dielectric induced by UVO treatment.

Identification of structural relaxation in the dielectric response of water

DEFF Research Database (Denmark)

Hansen, Jesper Schmidt; Kisliuk, Alexander; Solokov, Alexei P.

2016-01-01

One century ago pioneering dielectric results obtained for water and n-alcohols triggered the advent of molecular rotation diffusion theory considered by Debye to describe the primary dielectric absorption in these liquids. Comparing dielectric, viscoelastic, and light scattering results, we...... unambiguously demonstrate that the structural relaxation appears only as a high-frequency shoulder in the dielectric spectra of water. In contrast, the main dielectric peak is related to a supramolecular structure, analogous to the Debye-like peak observed in monoalcohols....

Al2O3 nanocrystals embedded in amorphous Lu2O3 high-k gate dielectric for floating gate memory application

International Nuclear Information System (INIS)

Yuan, C L; Chan, M Y; Lee, P S; Darmawan, P; Setiawan, Y

2007-01-01

The integration of nanoparticles has high potential in technological applications and opens up possibilities of the development of new devices. Compared to the conventional floating gate memory, a structure containing nanocrystals embedded in dielectrics shows high potential to produce a memory with high endurance, low operating voltage, fast write-erase speeds and better immunity to soft errors [S. Tiwari, F. Rana, H. Hanafi et al. 1996 Appl.Phys. Lett. 68, 1377]. A significant improvement on data retention [J. J. Lee, X. Wang et al. 2003 Proceedings of the VLSI Technol. Symposium, p33] can be observed when discrete nanodots are used instead of continuous floating gate as charge storage nodes because local defect related leakage can be reduced efficiently. Furthermore, using a high-k dielectric in place of the conventional SiO2 based dielectric, nanodots flash memory is able to achieve significantly improved programming efficiency and data retention [A. Thean and J. -P. Leburton, 2002 IEEE Potentials 21, 35; D. W. Kim, T. Kim and S. K. Banerjee, 2003 IEEE Trans. Electron Devices 50, 1823]. We have recently successfully developed a method to produce nanodots embedded in high-k gate dielectrics [C. L. Yuan, P. Darmawan, Y. Setiawan and P. S. Lee, 2006 Electrochemical and Solid-State Letters 9, F53; C. L. Yuan, P. Darmawan, Y. Setiawan and P. S. Lee, 2006 Europhys. Lett. 74, 177]. In this paper, we fabricated the memory structure of Al 2 O 3 nanocrystals embedded in amorphous Lu 2 O 3 high k dielectric using pulsed laser ablation. The mean size and density of the Al 2 O 3 nanocrystals are estimated to be about 5 nm and 7x1011 cm -2 , respectively. Good electrical performances in terms of large memory window and good data retention were observed. Our preparation method is simple, fast and economical

High-energy behavior of field-strength interactions

International Nuclear Information System (INIS)

Levin, D.N.

1976-01-01

It is known that spontaneously broken gauge theories are the only renormalizable theories of massive spin-one particles with mass dimension less than or equal to 4. This paper describes a search for renormalizable interactions with higher mass dimension. Specifically, we examine the high-energy behavior of a class of models which involve field-strength interactions. Power counting shows that the high-energy behavior of these models is no worse than the naively estimated high-energy behavior of a gauge theory in the U gauge. Therefore, there may be a ''soft'' symmetry-breaking mechanism (for instance, a soft divergence of an antisymmetric tensor current) which enforces renormalizable high-energy behavior in the same way that spontaneously broken gauge invariance guarantees the renormalizability of gauge theories. This hope is supported by the existence of ''gauge theories'' of strings, which describe analogous interactions of strings and field strengths. Unfortunately, this idea is tarnished by explicit calculations in which renormalizability is imposed in the form of unitarity bounds. These unitarity bounds imply that all possible field-strength couplings must be zero and that the remaining interactions describe a spontaneously broken gauge theory. Thus this result supports an earlier conjecture that gauge theories are the only renormalizable theories of massive vector bosons

Poly(methyl methacrylate) as a self-assembled gate dielectric for graphene field-effect transistors

Energy Technology Data Exchange (ETDEWEB)

Sanne, A.; Movva, H. C. P.; Kang, S.; McClellan, C.; Corbet, C. M.; Banerjee, S. K. [Microelectronics Research Center, University of Texas, Austin, Texas 78758 (United States)

2014-02-24

We investigate poly(methyl methacrylate) (PMMA) as a low thermal budget organic gate dielectric for graphene field effect-transistors (GFETs) based on a simple process flow. We show that high temperature baking steps above the glass transition temperature (∼130 °C) can leave a self-assembled, thin PMMA film on graphene, where we get a gate dielectric almost for “free” without additional atomic layer deposition type steps. Electrical characterization of GFETs with PMMA as a gate dielectric yields a dielectric constant of k = 3.0. GFETs with thinner PMMA dielectrics have a lower dielectric constant due to decreased polarization arising from neutralization of dipoles and charged carriers as baking temperatures increase. The leakage through PMMA gate dielectric increases with decreasing dielectric thickness and increasing electric field. Unlike conventional high-k gate dielectrics, such low-k organic gate dielectrics are potentially attractive for devices such as the proposed Bilayer pseudoSpin Field-Effect Transistor or flexible high speed graphene electronics.

Low velocity impact behaviour of ultra high strength concrete panels

Indian Academy of Sciences (India)

Ultra high strength concrete; panel; drop weight test; impact analysis;. ABAQUS. 1. Introduction. Ultra high strength concrete ... Knight (2012) investigated the dynamic behaviour of steel fibre reinforced concrete plates under impact loading with ...

Impact of oxygen precursor flow on the forward bias behavior of MOCVD-Al2O3 dielectrics grown on GaN

Science.gov (United States)

Chan, Silvia H.; Bisi, Davide; Liu, Xiang; Yeluri, Ramya; Tahhan, Maher; Keller, Stacia; DenBaars, Steven P.; Meneghini, Matteo; Mishra, Umesh K.

2017-11-01

This paper investigates the effects of the oxygen precursor flow supplied during metalorganic chemical vapor deposition (MOCVD) of Al2O3 films on the forward bias behavior of Al2O3/GaN metal-oxide-semiconductor capacitors. The low oxygen flow (100 sccm) delivered during the in situ growth of Al2O3 on GaN resulted in films that exhibited a stable capacitance under forward stress, a lower density of stress-generated negative fixed charges, and a higher dielectric breakdown strength compared to Al2O3 films grown under high oxygen flow (480 sccm). The low oxygen grown Al2O3 dielectrics exhibited lower gate current transients in stress/recovery measurements, providing evidence of a reduced density of trap states near the GaN conduction band and an enhanced robustness under accumulated gate stress. This work reveals oxygen flow variance in MOCVD to be a strategy for controlling the dielectric properties and performance.

THE STUDY OF HIGH DIELECTRIC CONSTANT MECHANISM OF La-DOPED Ba0.67Sr0.33TiO3 CERAMICS

Science.gov (United States)

Xu, Jing; He, Bo; Liu, Han Xing

It is a common and effective method to enhance the dielectric properties of BST ceramics by adding rare-earth elements. In this paper, it is important to analyze the cause of the high dielectric constant behavior of La-doped BST ceramics. The results show that proper rare earth La dopant (0.2≤x≤0.7) may greatly increase the dielectric constant of BST ceramics, and also improve the temperature stability, evidently. According to the current-voltage (J-V) characteristics, the proper La-doped BST ceramics may reach the better semiconductivity, with the decrease and increase in La doping, the ceramics are insulators. By using the Schottky barrier model and electric microstructure model to find the surface or grain boundary potential barrier height, the width of the depletion layer and grain size do play an important role in impacting the dielectric constant.

Study on Fatigue Characteristics of High-Strength Steel Welds

Energy Technology Data Exchange (ETDEWEB)

Chang, Hong Suk; Yoo, Seung Won; Park, Jong Chan [Hyundai Motor Group, Seoul (Korea, Republic of)

2015-03-15

High-strength steel has replaced mild steel as the material of choice for truck decks or frames, owing to the growing demand for lightweight vehicles. Although studies on the weld fatigue characteristics of mild steel are available, studies on high-strength steels have been seldom conducted. In this study, firstly, we surveyed a chosen number of approaches and selected the Radaj method, which uses the notch factor approach, as the one suitable for evaluating the fatigue life of commercial vehicles. Secondly, we obtained the S-N curves of HARDOX and ATOS60 steel welds, and the F-N curves of the T-weld and overlapped-weld structures. Thirdly, we acquired a general S-N curve of welded structures made of high-strength steel from the F-N curve, using the notch factor approach. Fourthly, we extracted the weld fatigue characteristics of high-strength steel and incorporated the results in the database of a commercial fatigue program. Finally, we compared the results of the fatigue test and the CAE prediction of the example case, which demonstrated sufficiently good agreement.

Electrical characterization of ALD HfO2 high-k dielectrics on ( 2 ¯ 01) β-Ga2O3

Science.gov (United States)

Shahin, David I.; Tadjer, Marko J.; Wheeler, Virginia D.; Koehler, Andrew D.; Anderson, Travis J.; Eddy, Charles R.; Christou, Aris

2018-01-01

The electrical quality of HfO2 dielectrics grown by thermal atomic layer deposition at 175 °C on n-type ( 2 ¯ 01) β-Ga2O3 has been studied through capacitance- and current-voltage measurements on metal-oxide-semiconductor capacitors. These capacitors exhibited excellent electrical characteristics, including dual-sweep capacitance-voltage curves with low hysteresis and stretch-out and a frequency-stable dielectric constant of k˜14 when measured between 10 kHz and 1 MHz. The C-V curves exhibited a uniform and repeatable +1.05 V shift relative to the ideal case when swept from 3.5 to -5 V, yielding positively measured flatband (+2.15 V) and threshold (+1.05 V) voltages that may be useful for normally off n-channel Ga2O3 devices. Using the Terman method, an average interface trap density of 1.3 × 1011 cm-2.eV-1 was obtained between 0.2 and 0.6 eV below the conduction band edge. The forward bias current-voltage characteristic was successfully fitted to the Fowler-Nordheim tunneling model at a field strength of 5 MV/cm, allowing an extraction of a 1.3 eV conduction band offset between HfO2 and Ga2O3, which matches the value previously determined from x-ray photoelectron spectroscopy. However, a temperature dependence in the leakage current was observed. These results suggest that HfO2 is an appealing dielectric for Ga2O3 device applications.

Dielectric platforms for surface-enhanced spectroscopies (Conference Presentation)

Science.gov (United States)

Maier, Stefan A.

2016-03-01

Plasmonic nanostructures serve as the main backbone of surface enhanced sensing methodologies, yet the associated optical losses lead to localized heating as well as quenching of molecules, complicating their use for enhancement of fluorescent emission. Additionally, conventional plasmonic materials are limited to operation in the visible part of the spectrum. We will elucidate how nanostructures consisting of conventional and polar dielectrics can be employed as a highly promising alternative platform. Dielectric nanostructures can sustain scattering resonances due to both electric and magnetic Mie modes. We have recently predicted high enhanced local electromagnetic field hot spots in dielectric nanoantenna dimers, with the hallmark of spot sizes comparable to those achievable with plasmonic antennas, but with lower optical losses. Here, we will present first experimental evidence for both fluorescence and Raman enhancement in dielectric nanoantennas, including a direct determination of localized heating, and compare to conventional Au dimer antennas. The second part of the talk will focus on the mid-infrared regime of the electromagnetic spectrum, outlining possibilities for surface enhanced infrared absorption spectroscopy based on polar and hyperbolic dielectrics.

High strength tungsten heavy alloys with molybdenum additions

International Nuclear Information System (INIS)

Bose, A.; Sims, D.M.; German, R.M.

1987-01-01

Tungsten heavy alloys are candidates for numerous applications based on the unique combination of high density, high strength, and high ductility coupled with excellent machinability. Though there has been considerable research on heavy alloys, the primary focus has been on the ductility. These alloys are well suited for ballistic uses due to their high densities and it is expected that for superior ballistic performance, a high hardness, high strength and moderate ductility alloy would be ideal. The major goal of this investigation was to obtain heavy alloys with hardness greater than HRA 72. It is evident from the phase diagrams that molybdenum, which goes into solution in tungsten, nickel and iron, could act as a potential strengthening addition. With this in view, tungsten heavy alloys with molybdenum additions were fabricated from mixed elemental powders. A baseline composition of 90W-7Ni-3Fe was chosen to its good elongation and moderate strength. The molybdenum additions were made by replacing the tungsten. Compared to the baseline properties with no molybdenum addition, the strength and hardness showed a continuous increase with molybdenum addition. The ductility of the alloy continued to decrease with increasing molybdenum content, but even with 16% wt. % molybdenum of the elongation was still around 6%. An interesting facet of these alloying additions is the grain refinement that is brought about by adding to molybdenum to the system. The grain refinement is related to the lower solubility of tunbsten in the matrix due to partial displacement by molybdenum

Effect of Interfacial Polarization and Water Absorption on the Dielectric Properties of Epoxy-Nanocomposites

Directory of Open Access Journals (Sweden)

Philipp Marx

2017-05-01

Full Text Available Five types of nanofillers, namely, silica, surface-silylated silica, alumina, surface-silylated alumina, and boron nitride, were tested in this study. Nanocomposites composed of an epoxy/amine resin and one of the five types of nanoparticles were tested as dielectrics with a focus on (i the surface functionalization of the nanoparticles and (ii the water absorption by the materials. The dispersability of the nanoparticles in the resin correlated with the composition (OH content of their surfaces. The interfacial polarization of the thoroughly dried samples was found to increase at lowered frequencies and increased temperatures. The β relaxation, unlike the interfacial polarization, was not significantly increased at elevated temperatures (below the glass-transition temperature. Upon the absorption of water under ambient conditions, the interfacial polarization increased significantly, and the insulating properties decreased or even deteriorated. This effect was most pronounced in the nanocomposite containing silica, and occurred as well in the nanocomposites containing silylated silica or non-functionalized alumina. The alternating current (AC breakdown strength of all specimens was in the range of 30 to 35 kV·mm−1. In direct current (DC breakdown tests, the epoxy resin exhibited the lowest strength of 110 kV·mm−1; the nanocomposite containing surface-silylated alumina had a strength of 170 kV·mm−1. In summary, water absorption had the most relevant impact on the dielectric properties of nanocomposites containing nanoparticles, the surfaces of which interacted with the water molecules. Nanocomposites containing silylated alumina particles or boron nitride showed the best dielectric properties in this study.

Increasing Lean Mass and Strength: A Comparison of High Frequency Strength Training to Lower Frequency Strength Training.

Science.gov (United States)

Thomas, Michael H; Burns, Steve P

The purpose of this study was to determine the effect strength training frequency has on improvements in lean mass and strength. Participants were 7 women and 12 men, age ( χ̄ = 34.64 years ± 6.91 years), with strength training experience, training age ( χ̄ = 51.16 months ± 39.02 months). Participants were assigned to one of two groups to equal baseline group demographics. High frequency training group (HFT) trained each muscle group as the agonist, 3 times per week, exercising with 3 sets per muscle group per session (3 total body workouts). Low frequency training group (LFT) trained each muscle group as the agonist one time per week, completing all 9 sets during that one workout. LFT consisted of a routine split over three days: 1) pectoralis, deltoids, and triceps; 2) upper back and biceps; 3) quadriceps, hamstrings, calves, and abdominals. Following eight weeks of training, HFT increased lean mass by 1.06 kg ± 1.78 kg, (1.9%), and LFT increased lean mass by .99 kg ± 1.31 kg, (2.0%). HFT strength improvements on the chest press was 9.07 kg ± 6.33 kg, (11%), and hack squat 20.16 kg ± 11.59 kg, (21%). LFT strength improvements on chest press was 5.80kg ± 4.26 kg, (7.0%), and hack squat 21.83 kg ± 11.17 kg, (24 %). No mean differences between groups were significant. These results suggest that HFT and LFT of equal set totals result in similar improvements in lean mass and strength, following 8 weeks of strength training.

The color dielectric model of QCD

International Nuclear Information System (INIS)

Pirner, H.-J.; Massachusetts Inst. of Tech., Cambridge, MA; Massachusetts Inst. of Tech., Cambridge, MA

1992-01-01

This paper demonstrates the emergence of valence gluons and their bound states, the glueballs from perturbative quantum chromodynamics (QCD). We discuss the phenomenological constraints and theoretical method needed to generate effective glueballs actions. We show how color dielectric confinement works naively and in the lattice model of color dielectrics. This lattice model is derived for SU(2) color by a blockspinning Monte Carlo renormalization group procedure. We interpret the resulting long-distance as a strongly interacting lattice string theory where the valence link gluon fields randomize in the color dielectric background which mimics the integrated out high-frequency gluon modes in the vacuum. The fluctuations of the color dielectric fields are related to color neutral glueballs modes. We give the extension of this color dielectric SU(2) theory for general SU(N) with quarks and address the problems associated with combining confinement and chiral symmetry breaking. Finally we prove the efficiency of the effective theory in applications to the heavy quark system, the the baryon, to the nucleon-nucleon interaction, to baryon models and the gluon plasma transition. In all those cases the behavior of the higher energy gluons can be monitored via the color dielectric fields. An increase in the energy density from ''deconfining'' the higher frequency modes inside the flux tube or in thermally excited matter shows up as an increase in the value of the color dielectric field and its associated energy density. (Author)

High power testing oa ANL X-band dielectric-loaded accelerating structures

International Nuclear Information System (INIS)

Power, J. G.; Gai, W.; Jing, C.; Konecny, R.; Gold, S. H.; Kinkead, A. K.

2002-01-01

In the second phase of a program to develop a compact accelerator based on a dielectric-loaded accelerating structure, we have conducted high power tests on a traveling-wave and a standing-wave prototype. Indications are that the traveling-wave structure achieved an accelerating gradient of 3-5 MV/m before the input coupling window failed, while the standing wave structure was poorly matched at high power due to contamination of copper residue on its coupling window. To solve both of these problems, a new method for coupling RF into the structures has been developed. The new couplers and the rest of the modular structure are currently under construction and will be tested at the Naval Research Laboratory shortly

A Molecular Dynamics Study of Crosslinked Phthalonitrile Polymers: The Effect of Crosslink Density on Thermomechanical and Dielectric Properties

Directory of Open Access Journals (Sweden)

Janel Chua

2018-01-01

Full Text Available In this work, molecular dynamics (MD and molecular mechanics (MM simulations are used to study well-equilibrated models of 4,4′-bis(3,4-dicyanophenoxybiphenyl (BPh–1,3-bis(3-aminophenoxybenzene (m-APB phthalonitrile (PN system with a range of crosslink densities. A cross-linking technique is introduced to build a series of systems with different crosslink densities; several key properties of this material, including thermal expansion, mechanical properties and dielectric properties are studied and compared with experimental results. It is found that the coefficient of linear thermal expansion predicted by the model is in good agreement with experimental results and indicative of the good thermal stability of the PN polymeric system. The simulation also shows that this polymer has excellent mechanical property, whose strength increases with increasing crosslink density. Lastly and most importantly, the calculated dielectric constant—which shows that this polymer is an excellent insulating material—indicates that there is an inverse relation between cross-linking density and dielectric constant. The trend gave rise to an empirical quadratic function which can be used to predict the limits of attainable dielectric constant for highly crosslinked polymer systems. The current computational work provides strong evidence that this polymer is a promising material for aerospace applications and offers guidance for experimental studies of the effect of cross-linking density on the thermal, mechanical and dielectric properties of the material.

High-strength high-conductivity Cu-Nb microcomposite sheet fabricated via multiple roll bonding

International Nuclear Information System (INIS)

Jha, S.C.; Delagi, R.G.; Forster, J.A.; Krotz, P.D.

1993-01-01

Copper-niobium microcomposites are a new class of high-strength high-conductivity materials that have attractive properties for room- and elevated-temperature applications. Since Nb has little solid solubility in Cu, addition of Nb to Cu does not affect its conductivity. Copper-niobium microcomposites are melted and cast so that the microstructure of cast Cu-Nb ingots consists of 1- to 10 μm Nb dendrites uniformly distributed within the copper matrix. Extensive wire drawing with a true processing strain (η> 12) of Cu-Nb alloy leads to refinement and elongation of Nb dendrites into 1- to 10 nm-thick filaments. The presence of such fine Nb filaments causes a significant increase in the strength of Cu-Nb wires. The tensile strength of heavily drawn Cu-Nb wires was determined to be significantly higher than the values predicted by the rule of mixtures. This article reports the fabrication of high-strength Cu-Nb microcomposite sheet by multiple roll bonding. It is difficult and impractical to attain high processing strains (η>3) by simple cold rolling. In most practical cold-rolling operation, the thickness reduction does not exceed 90 pct (η ≅2). Therefore, innovative processing is required to generate high strength in Cu-Nb microcomposite sheet. Multiple roll bonding of Cu-Nb has been utilized to store high processing strain ( η>10) in the material and refine the Nb particle size within the copper matrix. This article describes the microstructure, mechanical properties, and thermal stability of roll-bonded Cu-Nb microcomposite sheet

Dielectric dispersion and thermodynamic behavior of stearic acid binary mixtures with alcohol as co-solvent using time domain reflectometry

Directory of Open Access Journals (Sweden)

M. Maria Sylvester

2017-08-01

Full Text Available Dielectric permittivity and relaxation dynamics of binary and ternary mixture of stearic acid on various concentration and their thermodynamic effects are studied. The static dielectric constant (ε0, dielectric permittivity (ε′ and dielectric loss (ε′′ are found by bilinear calibration. The relaxation time (τ, dielectric strength (Δε and the excess permittivity (εE are found. The thermodynamic parameters such as enthalpy (ΔH, entropy (ΔS and Gibb’s free energy (ΔG are evolved. The significant changes in dielectric parameters are due to the intramolecular and intermolecular interactions in response to the applied frequency. The permittivity spectra of stearic acid–alcohol in the frequency range of 10MHz to 30GHz have been measured using picoseconds Time Domain Reflectometry (TDR. The dielectric parameters (ε0, ε′, ε′′ are found by bilinear calibration method. Influence of temperature in intermolecular interaction and the relaxation process are also studied. The FT-IR spectral analysis reveals that the conformation of functional groups and formation for hydrogen bonding are present in both binary and ternary mixtures of stearic acid.

AN OVERVIEW OF HIGH VOLTAGE DIELECTRIC MATERIAL FOR TRAVELING WAVE KICKER MAGNET APPLICATION

International Nuclear Information System (INIS)

ZHANG, W.; SANDBERG, J.; TUOZZOLO, J.; CASSEL, R.; DUCIMETIERE, L.; JENSEN, C.; BARNES, M.; WAIT, G.; WANG, J.

2002-01-01

Pulsed high power fast kickers are being used to change beam trajectories in particle accelerators. The fast rise and fall time of pulse waveform demands a transmission line structure for the kicker deflector design. The ideal design will be parallel metal plates. However, it uses very long straight sections to achieve the required deflection. In accelerators with constrained straight sections, high permeability materials such as ferrite have to be used to gain deflection efficiency. The transmission line kicker magnet is also referred as traveling wave kicker magnet. Its construction is based on distributed 1-C cells along the longitudinal direction. The magnetic cells and capacitive cells are interleaved to simulate the characteristic impedance of a transmission line to minimize pulse reflection, and provide adequate frequency bandwidth to transmit the kicker pulse with fast rise and fall time. The magnetic cells are usually made of ferrite ceramics, but the capacitive cells have been made with different materials. For traveling wave kickers with higher impedance, the parallel plate vacuum capacitor has been used in CERN and KEK design. Others have used ceramic capacitors, printed circuit boards, and high permittivity ceramics as the capacitive cell. The high dielectric material has the advantage of compactness for low impedance kicker magnet construction. It continues to be very attractive for future kicker magnet applications. The high voltage phenomena associated with high dielectric ceramic materials have been widely reported in many industrial application areas. Their implication in the traveling wave magnet application has to be well understood. In this presentation, the areas requiring further quantitative study will be outlined

Effect of microstructure on the high temperature strength of nitride

Indian Academy of Sciences (India)

Effect of microstructure on the high temperature strength of nitride bonded silicon carbide composite. J Rakshit P K Das. Composites Volume ... The effect of these parameters on room temperature and high temperature strength of the composite up to 1300°C in ambient condition were studied. The high temperature flexural ...

Tensile strength/yield strength (TS/YS) ratios of high-strength steel (HSS) reinforcing bars

Science.gov (United States)

Tavio, Anggraini, Retno; Raka, I. Gede Putu; Agustiar

2018-05-01

The building codes such as American Concrete Institute (ACI) 318M-14 and Standard National Indonesia (SNI) 2847:2013 require that the ratio of tensile strength (TS) and yield strength (YS) should not less than 1.25. The requirement is based on the assumption that a capability of a structural member to develop inelastic rotation capacity is a function of the length of the yield region. This paper reports an investigation on various steel grades, namely Grades 420, 550, 650, and 700 MPa, to examine the impact of different TS/YS ratios if it is less or greater than the required value. Grades 550, 650, and 700 MPa were purposely selected with the intention to examine if these higher grades are still promising to be implemented in special structural systems since they are prohibited by the building codes for longitudinal reinforcement, whereas Grade 420 MPa bars are the maximum limit of yield strength of reinforcing bars that is allowable for longitudinal reinforcement of special structural systems. Tensile tests of these steel samples were conducted under displacement controlled mode to capture the complete stress-strain curves and particularly the post-yield response of the steel bars. From the study, it can be concluded that Grade 420 performed higher TS/YS ratios and they were able to reach up to more than 1.25. However, the High Strength Still (HSS) bars (Grades 550, 600, and 700 MPa) resulted in lower TS/YS ratios (less than 1.25) compared with those of Grade 420 MPa.

[Compressive and bend strength of experimental admixed high copper alloys].

Science.gov (United States)

Sourai, P; Paximada, H; Lagouvardos, P; Douvitsas, G

1988-01-01

Mixed alloys for dental amalgams have been used mainly in the form of admixed alloys, where eutectic spheres are blend with conventional flakes. In the present study the compressive strength, bend strength and microstructure of two high-copper alloys (Tytin, Ana-2000) is compared with three experimental alloys prepared of the two high copper by mixing them in proportions of 3:1, 1:1 and 1:3 by weight. The results revealed that experimental alloys inherited high early and final strength values without any significant change in their microstructure.

High-efficient light absorption of monolayer graphene via cylindrical dielectric arrays and the sensing application

Science.gov (United States)

Zhou, Peng; Zheng, Gaige

2018-04-01

The efficiency of graphene-based optoelectronic devices is typically limited by the poor absolute absorption of light. A hybrid structure of monolayer graphene with cylindrical titanium dioxide (TiO2) array and aluminum oxide (Al2O3) spacer layer on aluminum (Al) substrate has been proposed to enhance the absorption for two-dimensional (2D) materials. By combining dielectric array with metal substrate, the structure achieves multiple absorption peaks with near unity absorbance at near-infrared wavelengths due to the resonant effect of dielectric array. Completed monolayer graphene is utilized in the design without any demand of manufacture process to form the periodic patterns. Further analysis indicates that the near-field enhancement induced by surface modes gives rise to the high absorption. This favorable field enhancement and tunability of absorption not only open up new approaches to accelerate the light-graphene interaction, but also show great potential for practical applications in high-performance optoelectronic devices, such as modulators and sensors.

High-frequency dielectric study of proustite crystals Ag3AsS3

Science.gov (United States)

Bordovsky, V. A.; Gunia, N. Yu; Castro, R. A.

2014-12-01

The dielectric properties of the crystals proustite in the frequency of 106-109 Hz and a temperature range of 173 to 473 K were studied. The dispersion of the dielectric parameters indicates the existence of non-Debye relaxation mechanism correlates with structural changes in the phase transition region. The charge transfer is temperature activated with an activation energy of 2.40 ± 0.01 eV.

High-impact strength acrylic denture base material processed by autoclave.

Science.gov (United States)

Abdulwahhab, Salwan Sami

2013-10-01

To investigate the effect of two different cycles of autoclave processing on the transverse strength, impact strength, surface hardness and the porosity of high-impact strength acrylic denture base material. High Impact Acryl was the heat-cured acrylic denture base material included in the study. A total of 120 specimens were prepared, the specimens were grouped into: control groups in which high-impact strength acrylic resins processed by conventional water-bath processing technique (74°C for 1.5 h then boil for 30 min) and experimental groups in which high-impact strength acrylic resins processed by autoclave at 121°C, 210 kPa .The experimental groups were divided into (fast) groups for 15 min, and (slow) groups for 30 min. To study the effect of the autoclave processing (Tuttnauer 2540EA), four tests were conducted transverse strength (Instron universal testing machine), impact strength (Charpy tester), surface hardness (shore D), and porosity test. The results were analyzed to ANOVA and LSD test. In ANOVA test, there were highly significant differences between the results of the processing techniques in transverse, impact, hardness, and porosity test. The LSD test showed a significant difference between control and fast groups in transverse and hardness tests and a non-significant difference in impact test and a highly significant difference in porosity test; while, there were a highly significant differences between control and slow groups in all examined tests; finally, there were a non-significant difference between fast and slow groups in transverse and porosity tests and a highly significant difference in impact and hardness tests. In the autoclave processing technique, the slow (long) curing cycle improved the tested physical and mechanical properties as compared with the fast (short) curing cycle. The autoclave processing technique improved the tested physical and mechanical properties of High Impact Acryl. Copyright © 2013 Japan Prosthodontic Society

Dielectric Properties of Flocculated Water-in-Oil Emulsions

Energy Technology Data Exchange (ETDEWEB)

Skodvin, T.

1995-12-31

When an offshore oil field is near completion, water occupies a large fraction of the available pore volume. Thus, in collecting the oil and gas reserves, one has to deal with a high co-production of either formation- or injected water. This doctoral thesis focuses on the effect of water-in-oil emulsions on the dielectric properties, in particular the effect of flocculation. Various dielectric models are applied to obtain methods for qualitative and quantitative characterization of the flocculated state. Permittivity and measurement of dielectric properties are discussed as a basis for the interpretation of the dielectric properties of the emulsions. Various flocculation models are presented. It is concluded that the dielectric properties of water-in-oil emulsions are strongly influenced by continuously ongoing processes in the system. Because of flocculation and sedimentation the traditional dielectric mixture models cannot satisfactorily predict the dielectric behaviour. The experimentally obtained permittivities for the emulsions can be reproduced by including flocculation in the models and treating the floc aggregates as spheroids or subsystems with dielectric properties given by the degree of flocculation. The models discussed have difficulties reproducing the complete frequency behaviour found experimentally. This is probably because the dielectric relaxation may be influenced by processes not included in the models, such as the effects of dipolar or multipolar interactions between the droplets. For further research it is recommended that rheological and dielectric measurements be combined. 227 refs., 61 figs., 16 tabs.

Dielectric Properties of Flocculated Water-in-Oil Emulsions

Energy Technology Data Exchange (ETDEWEB)

Skodvin, T

1996-12-31

When an offshore oil field is near completion, water occupies a large fraction of the available pore volume. Thus, in collecting the oil and gas reserves, one has to deal with a high co-production of either formation- or injected water. This doctoral thesis focuses on the effect of water-in-oil emulsions on the dielectric properties, in particular the effect of flocculation. Various dielectric models are applied to obtain methods for qualitative and quantitative characterization of the flocculated state. Permittivity and measurement of dielectric properties are discussed as a basis for the interpretation of the dielectric properties of the emulsions. Various flocculation models are presented. It is concluded that the dielectric properties of water-in-oil emulsions are strongly influenced by continuously ongoing processes in the system. Because of flocculation and sedimentation the traditional dielectric mixture models cannot satisfactorily predict the dielectric behaviour. The experimentally obtained permittivities for the emulsions can be reproduced by including flocculation in the models and treating the floc aggregates as spheroids or subsystems with dielectric properties given by the degree of flocculation. The models discussed have difficulties reproducing the complete frequency behaviour found experimentally. This is probably because the dielectric relaxation may be influenced by processes not included in the models, such as the effects of dipolar or multipolar interactions between the droplets. For further research it is recommended that rheological and dielectric measurements be combined. 227 refs., 61 figs., 16 tabs.

Improving Strength-Ductility Balance of High Strength Dual-Phase Steels by Addition of Vanadium

Science.gov (United States)

Gong, Yu; Hua, M.; Uusitalo, J.; DeArdo, A. J.

For galvanized or galvannealed steels to be commercially successful, they must exhibit several attributes: (i) easy and inexpensive processing in the hot mill, cold mill and on the coating line, (ii) high strength with good formability and spot weldability, and (iii) good corrosion resistance, especially after cold forming. For good corrosion resistance, the coating must have sufficient coverage, be of uniform thickness, and most importantly, the coating must survive the cold stamping or forming operation. The purpose of this paper is to present research aiming at improving the steel substrate, such that high strength can be obtained while maintaining good global formability (tensile ductility), local formability (sheared-edge ductility), and good spot weldability. It is well-known that the strength of DP steels is controlled by several factors, including the amount of martensite found in the final microstructure. Recent research has revealed that the amount of austenite formed during intercritical annealing can be strongly influenced by the annealing temperature and the pre-annealing conditions of the hot band (coiling temperature) and cold band (% cold reduction). Current experiments have explored the combination of pre-annealing conditions and four annealing practices to help define the best practice to optimize the strength-formability balance in these higher strength DP steels. The steels used in these experiments contained (i) low carbon content for good spot weldability, (ii) the hardenability additions Mo and Cr for strength, and (iii) V for grain refinement, precipitation hardening and temper resistance. When processed correctly, these steels exhibited UTS levels up to 1000MPa, total elongation to 25%, reduction in area to 45%, and Hole Expansion Ratios to 50%. The results of this program will be presented and discussed.

Complex dielectric modulus and relaxation response at low microwave frequency region of dielectric ceramic Ba6-3xNd8+2xTi18O54

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Chian Heng Lee

2014-10-01

Full Text Available The desirable characteristics of Ba6-3xNd8+2xTi18O54 include high dielectric constant, low loss tangent, and high quality factor developed a new field for electronic applications. The microwave dielectric properties of Ba6-3xNd8+2xTi18O54, with x = 0.15 ceramics at different sintering temperatures (600–1300°C were investigated. The phenomenon of polarization produced by the applied electric field was studied. The dielectric properties with respect to frequency from 1 MHz to 1.5 GHz were measured using Impedance Analyzer, and the results were compared and analyzed. The highest dielectric permittivity and lowest loss factor were defined among the samples. The complex dielectric modulus was evaluated from the measured parameters of dielectric measurement in the same frequency range, and used to differentiate the contribution of grain and grain boundary.

Failure analysis of high strength pipeline with single and multiple corrosions

International Nuclear Information System (INIS)

Chen, Yanfei; Zhang, Hong; Zhang, Juan; Li, Xin; Zhou, Jing

2015-01-01

Highlights: • We study failure of high strength pipelines with single corrosion. • We give regression equations for failure pressure prediction. • We propose assessment procedure for pipelines with multiple corrosions. - Abstract: Corrosion will compromise safety operation of oil and gas pipelines, accurate determination of failure pressure finds importance in residual strength assessment and corrosion allowance design of onshore and offshore pipelines. This paper investigates failure pressure of high strength pipeline with single and multiple corrosions using nonlinear finite element analysis. On the basis of developed regression equations for failure pressure prediction of high strength pipeline with single corrosion, the paper proposes an assessment procedure for predicting failure pressure of high strength pipeline with multiple corrosions. Furthermore, failure pressures predicted by proposed solutions are compared with experimental results and various assessment methods available in literature, where accuracy and versatility are demonstrated

A Study of Dip-Coatable, High-Capacitance Ion Gel Dielectrics for 3D EWOD Device Fabrication

Directory of Open Access Journals (Sweden)

Carlos E. Clement

2017-01-01

Full Text Available We present a dip-coatable, high-capacitance ion gel dielectric for scalable fabrication of three-dimensional (3D electrowetting-on-dielectric (EWOD devices such as an n × n liquid prism array. Due to the formation of a nanometer-thick electric double layer (EDL capacitor, an ion gel dielectric offers two to three orders higher specific capacitance (c ≈ 10 μF/cm2 than that of conventional dielectrics such as SiO2. However, the previous spin-coating method used for gel layer deposition poses several issues for 3D EWOD device fabrication, particularly when assembling multiple modules. Not only does the spin-coating process require multiple repetitions per module, but the ion gel layer also comes in risks of damage or contamination due to handling errors caused during assembly. In addition, it was observed that the chemical formulation previously used for the spin-coating method causes the surface defects on the dip-coated gel layers and thus leads to poor EWOD performance. In this paper, we alternatively propose a dip-coating method with modified gel solutions to obtain defect-free, functional ion gel layers without the issues arising from the spin-coating method for 3D device fabrication. A dip-coating approach offers a single-step coating solution with the benefits of simplicity, scalability, and high throughput for deposition of high-capacitance gel layers on non-planar EWOD devices. An ion gel solution was prepared by combining the [EMIM][TFSI] ionic liquid and the [P(VDF-HFP] copolymer at various wt % ratios in acetone solvent. Experimental studies were conducted to fully understand the effects of chemical composition ratios in the gel solution and how varying thicknesses of ion gel and Teflon layers affects EWOD performance. The effectiveness and potentiality of dip-coatable gel layers for 3D EWOD devices have been demonstrated through fabricating 5 × 1 arrayed liquid prisms using a single-step dip-coating method. Each prism module has

Laser amplification in excited dielectrics

Science.gov (United States)

Winkler, Thomas; Haahr-Lillevang, Lasse; Sarpe, Cristian; Zielinski, Bastian; Götte, Nadine; Senftleben, Arne; Balling, Peter; Baumert, Thomas

2018-01-01

Wide-bandgap dielectrics such as glasses or water are transparent at visible and infrared wavelengths. This changes when they are exposed to ultrashort and highly intense laser pulses. Different interaction mechanisms lead to the appearance of various transient nonlinear optical phenomena. Using these, the optical properties of dielectrics can be controlled from the transparent to the metal-like state. Here we expand this range by a yet unexplored mechanism in excited dielectrics: amplification. In a two-colour pump-probe experiment, we show that a 400 nm femtosecond laser pulse is coherently amplified inside an excited sapphire sample on a scale of a few micrometres. Simulations strongly support the proposed two-photon stimulated emission process, which is temporally and spatially controllable. Consequently, we expect applications in all fields that demand strongly localized amplification.

Study of dielectric liquids at room temperature for high energy x ray Tomography