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Sample records for extraordinary dielectric properties

  1. Dielectric properties of polyethylene

    International Nuclear Information System (INIS)

    Darwish, S.; Riad, A.S.; El-Shabasy, M.

    2005-01-01

    The temperature dependence of dielectric properties in polyethylene was measured in the frequency range from 10 to 105 Hz. The frequency dependence of the complex impedance in the complex plane could be fitted by semicircles. The system could be represented by an equivalent circuit of a bulk resistance in series with parallel surface resistance-capacitance combination. The relaxation time, has been evaluated from experimental results. Results reveal that the temperature dependence, is a thermally activated process

  2. Complex extraordinary dielectric function of Mg-doped lithium niobate crystals at terahertz frequencies

    Science.gov (United States)

    Kuznetsov, K. A.; Kitaeva, G. Kh.; Kovalev, S. P.; Germansky, S. A.; Buryakov, A. M.; Tuchak, A. N.; Penin, A. N.

    2016-08-01

    We study the dispersion of the extraordinary dielectric function real and imaginary parts in the wide terahertz-frequency range of the lowest polariton branch for bulk LiNbO3 and Mg:LiNbO3 crystals. At frequencies 0.1-2.5 THz, both dispersion parts are measured by means of standard time-domain terahertz spectroscopy, and at higher frequencies up to 5.5 THz, the dielectric function real part is determined using a common scheme of spontaneous parametric down-conversion under near-forward Raman scattering by phonon polaritons. A special approach is applied for measuring of the dielectric function imaginary part at frequencies 1-3 THz, based on the analysis of visibility of three-wave second-order interference under spontaneous parametric down-conversion. The generalized approximate expressions are obtained for complex dielectric function dispersion within the lower polariton branches of LiNbO3 and Mg:LiNbO3. It is shown that the well-known decrease in terahertz-wave absorption of lithium niobate crystals under Mg-doping is caused by changes in the defect structure and reduction of coupling of the terahertz-frequency polaritons with Debye relaxational mode.

  3. Extraordinary electronic properties in uncommon structure types

    Science.gov (United States)

    Ali, Mazhar Nawaz

    In this thesis I present the results of explorations into several uncommon structure types. In Chapter 1 I go through the underlying idea of how we search for new compounds with exotic properties in solid state chemistry. The ideas of exploring uncommon structure types, building up from the simple to the complex, using chemical intuition and thinking by analogy are discussed. Also, the history and basic concepts of superconductivity, Dirac semimetals, and magnetoresistance are briefly reviewed. In chapter 2, the 1s-InTaS2 structural family is introduced along with the discovery of a new member of the family, Ag0:79VS2; the synthesis, structure, and physical properties of two different polymorphs of the material are detailed. Also in this chapter, we report the observation of superconductivity in another 1s structure, PbTaSe2. This material is especially interesting due to it being very heavy (resulting in very strong spin orbit coulping (SOC)), layered, and noncentrosymmetric. Electronic structure calculations reveal the presence of a bulk 3D Dirac cone (very similar to graphene) that is gapped by SOC originating from the hexagonal Pb layer. In Chapter 3 we show the re-investigation of the crystal structure of the 3D Dirac semimetal, Cd3As2. It is found to be centrosymmetric, rather than noncentrosymmetric, and as such all bands are spin degenerate and there is a 4-fold degenerate bulk Dirac point at the Fermi level, making Cd3As2 a 3D electronic analog to graphene. Also, for the first time, scanning tunneling microscopy experiments identify a 2x2 surface reconstruction in what we identify as the (112) cleavage plane of single crystals; needle crystals grow with a [110] long axis direction. Lastly, in chapter 4 we report the discovery of "titanic" (sadly dubbed ⪉rge, nonsaturating" by Nature editors and given the acronym XMR) magnetoresistance (MR) in the non-magnetic, noncentrosymmetric, layered transition metal dichalcogenide WTe2; over 13 million% at 0.53 K in

  4. Surface properties of dielectrics

    International Nuclear Information System (INIS)

    Le Gressus, C.; Maire, P.; Duraud, J.P.; Lecayon, G.

    1988-03-01

    Importance of defects on dielectric behaviour (breakdown), mechanical behaviour (fracture, adhesion) and thermochemical behaviour of insulating materials is recalled. Then effect of a mechanical stress on breakdown voltage is studied. An experimental verification shows that fracture of Y 2 O 3 is propagated in grain boundaries enriched in oxygen vacancies for a non stoichiometric sample by local variation of dielectric constant [fr

  5. Dielectric Properties of Soils, Fort Carson, CO

    National Research Council Canada - National Science Library

    Curtis, John

    1996-01-01

    This report contains dielectric property measurement results for soils. The original data were collected in the form of the real and imaginary parts of the complex dielectric constant versus frequency...

  6. Dielectric properties of nanosilica filled epoxy nanocomposites

    Indian Academy of Sciences (India)

    M G Veena

    This paper presents the development of epoxy-silica nanocomposites and characterized for dielectric properties. The effect of ... However, at higher silica loading TEM showed inter-contactity of the particles. The dielectric constant (e. 0. ) ..... of the mechanical and permeability properties of nano- and micron-TiO2 filled epoxy ...

  7. Improvement in the microwave dielectric properties of ...

    Indian Academy of Sciences (India)

    Administrator

    Keywords. XRD; processing; phase; ceramics. 1. Introduction. Ceramics are extensively studied due to their unique microwave dielectric properties which make them potential candidate materials for manufacture of compact and low- cost dielectric resonators for wireless telecommunication devices (Reaney and Idles 2006).

  8. Characterization, Microstructure, and Dielectric properties of cubic pyrochlore structural ceramics

    KAUST Repository

    Li, Yangyang

    2013-05-01

    solutions have relative high dielectric constant and low dielectric loss. With increasing sintering temperature, the dielectric constant showed the maximum at 1150°C. The leakage current of BMN ceramic material is extraordinary small. When the voltage and thickness of the BMN capacitor are 4000V and 300um, the leakage current amounts only about 0.13-0.65 . The excellent physical and electrical properties make BMN thin films promising for potential tunable capacitor applications.

  9. In-beam dielectric properties of alumina

    International Nuclear Information System (INIS)

    Molla, J.; Ibarra, A.; Hodgson, E.R.

    1995-01-01

    The dielectric properties (permittivity and loss tangent) of a 99.7% purity alumina grade have been measured over a wide frequency range (1 kHz-15 GHz) before and after 2 MeV electron irradiation at different temperatures. The dielectric properties at 15 GHz were measured during irradiation. Both prompt and fluence effects are observed together with permanent changes which continue to evolve following irradiation. The behaviour is complex, consistent with both radiation induced electronic effects and aggregation processes. ((orig.))

  10. Resonance excitation and light concentration in sets of dielectric nanocylinders in front of a subwavelength aperture. Effects on extraordinary transmission.

    Science.gov (United States)

    Valdivia-Valero, F J; Nieto-Vesperinas, M

    2010-03-29

    We study the excitation of whispering gallery modes (WGM) in dielectric nanocylinders by light transmitted through a subwavelength slit in a metallic slab. Calculations are done both by the finite elements method and using FDTD simulations. We discuss the effect of that excitation on extraordinary transmission by the slit. In this way, we show the dominant role of the WGMs over the aperture enhanced transmission as regards the resulting transmitted intensity and its concentration inside the cylinders. When sets of these particles are placed in front of the slit, like linear or bifurcated chains, with or without bends, the concentration of WGMs is controlled by designing the geometry parameters, so that these surface waves are coupled by both waveguiding of the nanocylinder eigenmodes and by scattered propagating waves. Also, the choice of the wavelength and polarization of the illumination, allows to select the excitation of either bonding or antibonding states of the field transmitted through the aperture into the particles. These resonances are further enhanced when a beam emerges from the slit due to adding a periodic corrugation in the slab.

  11. 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.

  12. High field dielectric properties of piezoelectric materials

    Energy Technology Data Exchange (ETDEWEB)

    Stewart, M.; Cain, M

    1999-05-01

    These guidelines are intended to enable a user to perform high field dielectric measurements on piezoelectric ceramic materials such as PZT (lead zirconium titanate). Many of the properties of piezoelectric ceramics such as PZT are highly dependant on the applied field, and therefore to make intelligent design choices, the dielectric properties are required at these field levels. These guidelines cover measurements at a fixed frequency of 1 kHz, to enable comparison with measurements made at low field. The measurement methods could all safely be extended from line frequency up to several tens of kHz, to cover a broad range of applications. However, for frequencies in the MHz range and above different factors need to be considered which are not covered in this guide. The guidelines give some general advice on high field dielectric measurements followed by a detailed description of three different measurement methods:Schering bridge; impedance analysis; and PE hysteresis loop methods. (author)

  13. Dielectric properties of proton irradiated PES

    International Nuclear Information System (INIS)

    Shah, Nilam; Singh, N.L.; Singh, K.P.

    2005-01-01

    Polyethersulfone films were irradiated with 3 MeV proton beam at fluences ranging from 10 13 to 10 15 ions/cm 2 . AC electrical properties of irradiated samples were studied in the frequency range 100 Hz to 1MHz by LCR meter. There is an exponential increase in conductivity with frequency but the effect of irradiation is not significant. The dielectric loss/constant are observed to change with fluence. (author)

  14. Tunable dielectric properties of ferrite-dielectric based metamaterial.

    Directory of Open Access Journals (Sweden)

    K Bi

    Full Text Available A ferrite-dielectric metamaterial composed of dielectric and ferrite cuboids has been investigated by experiments and simulations. By interacting with the electromagnetic wave, the Mie resonance can take place in the dielectric cuboids and the ferromagnetic precession will appear in the ferrite cuboids. The magnetic field distributions show the electric Mie resonance of the dielectric cuboids can be influenced by the ferromagnetic precession of ferrite cuboids when a certain magnetic field is applied. The effective permittivity of the metamaterial can be tuned by modifying the applied magnetic field. A good agreement between experimental and simulated results is demonstrated, which confirms that these metamaterials can be used for tunable microwave devices.

  15. 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...

  16. 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.

  17. Modelling dielectric and magnetic properties of ferroconcrete

    Directory of Open Access Journals (Sweden)

    T. Frenzel

    2008-05-01

    Full Text Available This contribution discusses the modelling and parameterization of dielectric and magnetic properties of ferroconcrete by using numerical electromagnetic field analysis software. The software is based on the Method of Moments (MoM. The shielding effectiveness (SE of the ferroconcrete DUT was already measured in a study by order of the government. According to these results, the ferroconcrete DUT is modelled and calculated. Therefore the DUT is subdivided into two parts. The first part represents the reinforcement mesh; the second part represents the lossy concrete with complex permittivity. Afterwards, the reflection and transmission properties of numerical analysed building materials are validated and compared with the measurement results in a frequency range of 30–1000 MHz.

  18. Dielectric properties for prediction of moisture content in Vidalia onions

    Science.gov (United States)

    Microwave Sensing provides a means for nondestructively determining the amount of moisture in materials by sensing the dielectric properties of the material. In this study, dielectric properties of Vidalia onions were analyzed for moisture dependence at 13.36 GHz and 23°C for moisture content betwee...

  19. 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.

  20. Dielectric properties of barium titanate supramolecular nanocomposites.

    Science.gov (United States)

    Lee, Keun Hyung; Kao, Joseph; Parizi, Saman Salemizadeh; Caruntu, Gabriel; Xu, Ting

    2014-04-07

    Nanostructured dielectric composites can be obtained by dispersing high permittivity fillers, barium titanate (BTO) nanocubes, within a supramolecular framework. Thin films of BTO supramolecular nanocomposites exhibit a dielectric permittivity (εr) as high as 15 and a relatively low dielectric loss of ∼0.1 at 1 kHz. These results demonstrate a new route to control the dispersion of high permittivity fillers toward high permittivity dielectric nanocomposites with low loss. Furthermore, the present study shows that the size distribution of nanofillers plays a key role in their spatial distribution and local ordering and alignment within supramolecular nanostructures.

  1. Dielectrical properties of composites LDPE+CB

    Directory of Open Access Journals (Sweden)

    Škipina Blanka

    2010-01-01

    Full Text Available There is currently great interest in the technological properties of conductive polymer composites because their cost-performance balance. They have a wide range of industrial applications -in anti-static materials, self regulating heaters, current overload and overheating protection devices, and materials for electromagnetic radiation shielding. Measurements of the electrical properties of polymer composites are one of the most convenient and sensitive methods for studying polymer structure. A polymer composite differs substantially from a free polymer in a wide range of properties. The presence of filler affects both the electrical, as well as mechanical properties. One of the most important characteristics of conductive polymer composites is that their electrical conductivity increases nonlinearly with the increase of the concentration of filler particles. When the concentration of filler particles reaches a certain critical value, a drastic transition from an electrical insulator to a conductor is exhibited. This conductivity behavior resulting in a sudden insulator-conductor transition is ascribed to a percolation process, and the critical filler concentration at which the conductivity jump occurs is called ‘percolation threshold’. In the past few years, a lot of studies have been carried out to analyze the percolation phenomenon and mechanisms of the conductive behavior in conductive polymer composites. It has been established that the electrical conductivity of conductive polymer composites uncommonly depends on the temperature. Some of such composites show a sharp increase and/or decrease in electrical conductivity at specific temperatures. The conductive temperature coefficient (CTC of conductive polymer composites has been widely investigated. In these work we investigated how concentration of the CB affects the dielectrical properties of the composite LDPE+CB. The ac electrical conductivity, σac, for such composites was measured

  2. Synthesis and microwave dielectric properties of Ca substituted ...

    Indian Academy of Sciences (India)

    Administrator

    Extensive research has been carried out in the last three decades on dielectric ceramics due to their unique electri- cal properties which make them suitable candidates as dielectric resonators for microwave based wireless tele- communication industry by reducing the size and cost of filters and antennas in the circuit.

  3. Effect of Dielectric Property of Hydrous Dispersoid on Electrorheology

    Science.gov (United States)

    Kawai, Akiko; Uchida, Kunio; Kamiya, Kunio; Gotoh, Akihiro; Yoda, Satoshi; Urabe, Kei; Ikazaki, Fumikazu

    The effect of the dielectric property was investigated of titania and microcrystalline cellulose particles dispersed in a silicon oil on Electrorheology(ER). A commom understanding of the mechanism of ER is the electrical interaction by the interfacial polarization of dispersed particles. Block et al. reported the relaxation frequency of ER fluids, i. e. the rate of polarization, was very important to have an appreciable ER effect. We found that the free water on the cellulose and the titania particles dispersed in the silicon oil, which is respectively dehydrated below the temperature of ca. 110 and 300 degree centigrade, was necessary for an appreciable ER effect. The relation was measured between the water content and the dielectric properties such as dielectric constant ɛ ’ and dielectric loss factor ɛ ", as the water adsorbed on the particles was estimated to alter the dielectric properties of the ER fluid. Both the dielectric constant and the relaxation frequency, which is defined by the applied frequency for a peak of the dielectric loss factor, increased with the increase of the water content The relation was discussed between the ER effect and the dielectric properties.

  4. Millimeter wave and terahertz dielectric properties of biological materials

    Science.gov (United States)

    Khan, Usman Ansar

    Broadband dielectric properties of materials can be employed to identify, detect, and characterize materials through their unique spectral signatures. In this study, millimeter wave, submillimeter wave, and terahertz dielectric properties of biological substances inclusive of liquids, solids, and powders were obtained using Dispersive Fourier Transform Spectroscopy (DFTS). Two broadband polarizing interferometers were constructed to test materials from 60 GHz to 1.2 THz. This is an extremely difficult portion of the frequency spectrum to obtain a material's dielectric properties since neither optical nor microwave-based techniques provide accurate data. The dielectric characteristics of liquids such as cyclohexane, chlorobenzene, benzene, ethanol, methanol, 1,4 dioxane, and 10% formalin were obtained using the liquid interferometer. Subsequently the solid interferometer was utilized to determine the dielectric properties of human breast tissues, which are fixed and preserved in 10% formalin. This joint collaboration with the Tufts New England Medical Center demonstrated a significant difference between the dielectric response of tumorous and non-tumorous breast tissues across the spectrum. Powders such as anthrax, flour, talc, corn starch, dry milk, and baking soda have been involved in a number of security threats and false alarms around the globe in the last decade. To be able to differentiate hoax attacks and serious security threats, the dielectric properties of common household powders were also examined using the solid interferometer to identify the powders' unique resonance peaks. A new sample preparation kit was designed to test the powder specimens. It was anticipated that millimeter wave and terahertz dielectric characterization will enable one to clearly distinguish one powder from the other; however most of the powders had relatively close dielectric responses and only Talc had a resonance signature recorded at 1.135 THz. Furthermore, due to

  5. Improvement in the microwave dielectric properties of ...

    Indian Academy of Sciences (India)

    Administrator

    Microwave dielectric ceramics in the Sr1–xBaxCa4Nb4TiO17 (0 ≤ x ≤ 0⋅75) composition series were fabricated via a solid-state mixed oxide route. ... wavelengths of microwaves in a dielectric medium and free space, respectively. Several ceramic .... The reflections from all the compositions were identical and could be ...

  6. Aging of Dielectric Properties below Tg

    DEFF Research Database (Denmark)

    Olsen, Niels Boye; Dyre, Jeppe; Christensen, Tage Emil

    The dielectric loss at 1Hz in TPP is studied during a temperature step from one equilibrium state to another. In the applied cryostate the temperature can be equilibrated on a timescale of 1 second. The aging time dependence of the dielectric loss is studied below Tg applying temperature steps...

  7. Dielectric properties of human placenta, umbilical cord and amniotic fluid

    Science.gov (United States)

    Peyman, A.; Gabriel, C.; Benedickter, H. R.; Fröhlich, J.

    2011-04-01

    The dielectric properties of freshly delivered human placenta, umbilical cord and amniotic fluid have been acquired at 37 °C and in the frequency range of 200 MHz-10 GHz. The experimental data were fitted to a Cole-Cole expression. The results show that dielectric properties of the umbilical cord are significantly higher than placenta due to the presence of high water content Wharton's jelly. The results also demonstrate large differences in the dielectric properties of amniotic and cerebrospinal fluids. The data presented can be used in numerical simulations of the exposure of pregnant women to electromagnetic fields.

  8. Dielectric properties of human placenta, umbilical cord and amniotic fluid

    Energy Technology Data Exchange (ETDEWEB)

    Peyman, A [Physical Dosimetry Department, Health Protection Agency, Chilton, Didcot OX11 0RQ (United Kingdom); Gabriel, C [MCL-P, Newbury RG14 5PY, Berkshire (United Kingdom); Benedickter, H R; Froehlich, J, E-mail: Azadeh.peyman@hpa.org.uk [Electromagnetic Fields and Microwave Electronics Laboratory, Swiss Federal Institute of Technology, Zurich (Switzerland)

    2011-04-07

    The dielectric properties of freshly delivered human placenta, umbilical cord and amniotic fluid have been acquired at 37 deg. C and in the frequency range of 200 MHz-10 GHz. The experimental data were fitted to a Cole-Cole expression. The results show that dielectric properties of the umbilical cord are significantly higher than placenta due to the presence of high water content Wharton's jelly. The results also demonstrate large differences in the dielectric properties of amniotic and cerebrospinal fluids. The data presented can be used in numerical simulations of the exposure of pregnant women to electromagnetic fields. (note)

  9. Controlled Synthesis of Ultralong Carbon Nanotubes with Perfect Structures and Extraordinary Properties.

    Science.gov (United States)

    Zhang, Rufan; Zhang, Yingying; Wei, Fei

    2017-02-21

    Carbon nanotubes (CNTs) have drawn intensive research interest in the past 25 years due to their excellent properties and wide applications. Ultralong CNTs refers to the horizontally aligned CNT arrays which are usually grown on flat substrates, parallel with each other with large intertube distances. They usually have perfect structures, excellent properties, and lengths up to centimeters, even decimeters. Ultralong CNTs are promising candidates as building blocks for transparent displays, nanoelectronics, superstrong tethers, aeronautics and aerospace materials, etc. The controlled synthesis of ultralong CNTs with perfect structures is the key to fully exploit the extraordinary properties of CNTs. CNTs are typical one-dimensional single-crystal nanomaterials. It has always been a great challenge how to grow macroscale single-crystals with no defects. Thus, the synthesis of ultralong CNTs with no defect is of significant importance from both fundamental and industrial aspects. In this Account, we focus on our progress on the controlled synthesis of ultralong CNTs with perfect structures and excellent properties. A deep understanding of the CNT growth mechanism is the first step for the controlled synthesis of ultralong CNTs with high quality. We first introduce the growth mechanism for ultralong CNTs and the main factor affecting their structures. We then discuss the strategies to control the defects in the as-grown ultralong CNTs. With these approaches, ultralong high-quality CNTs with different structures can be obtained. By completely eliminating the factors which may induce defects in the CNT walls, ultralong CNTs with perfect structures can be obtained. Their chiral indices keep unchanged for several centimeters long along the axial direction of the CNTs. The defect-free structures render the ultralong CNTs with excellent electrical, mechanical and thermal properties. The as-grown ultralong CNTs exhibit superhigh mechanical strength (>100 GPa) and their

  10. Analysis of terahertz dielectric properties of pork tissue

    Science.gov (United States)

    Huang, Yuqing; Xie, Qiaoling; Sun, Ping

    2017-10-01

    Seeing that about 70% component of fresh biological tissues is water, many scientists try to use water models to describe the dielectric properties of biological tissues. The classical water dielectric models are Debye model, Double Debye model and Cole-Cole model. This work aims to determine a suitable model by comparing three models above with experimental data. These models are applied to fresh pork tissue. By means of least square method, the parameters of different models are fitted with the experimental data. Comparing different models on both dielectric function, the Cole-Cole model is verified the best to describe the experiments of pork tissue. The correction factor α of the Cole-Cole model is an important modification for biological tissues. So Cole-Cole model is supposed to be a priority selection to describe the dielectric properties for biological tissues in the terahertz range.

  11. Dielectric and photo-dielectric properties of TlGaSeS crystals

    Indian Academy of Sciences (India)

    Administrator

    The light sensi- tivity of the crystals, the improved dielectric properties and the lower biasing voltage obtained via photoexci- tation and the well-enhanced signal quality factor of the crystals make them ... The light intensity was altered by varying position of the source. ... excitation intensities being presented in the frequency.

  12. Silicone elastomers with superior softness and dielectric properties

    DEFF Research Database (Denmark)

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

    commercial elastomer, while the dielectric losses remained at a low level. The increase in dielectric permittivity stemmed from the high dipole moment of the chloride groups. Furthermore, the alkyl chloride units yielded a larger free volume resulted in a less dense material with a lower Young's modulus.[3]......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...

  13. UV response on dielectric properties of nano nematic liquid crystal

    Directory of Open Access Journals (Sweden)

    Kamal Kumar Pandey

    2018-03-01

    Full Text Available In this work, we investigate the effect of UV light irradiation on the dielectric parameters of nematic liquid crystal (5CB and ZnO nanoparticles dispersed liquid crystal. With addition of nanoparticles in nematic LC are promising new materials for a variety of application in energy harvesting, displays and photonics including the liquid crystal laser. To realize many applications, however we optimize the properties of liquid crystal and understand how the UV light irradiation interact the nanoparticles and LC molecules in dispersed/doped LC. The dielectric permittivity and loss factor have discussed the pure nematic LC and dispersed/doped system after, during and before UV light exposure. The dielectric relaxation spectroscopy was carried out in the frequency range 100 Hz–10 MHz in the nematic mesophase range. Keywords: Dielectric permittivity, Relaxation frequency, Nematic liquid crystal, UV light irradiation

  14. First-principles study of dielectric properties of cerium oxide

    International Nuclear Information System (INIS)

    Yamamoto, Takenori; Momida, Hiroyoshi; Hamada, Tomoyuki; Uda, Tsuyoshi; Ohno, Takahisa

    2005-01-01

    We have theoretically investigated the dielectric properties of fluorite CeO 2 as well as hexagonal and cubic Ce 2 O 3 by using first-principles pseudopotentials techniques within the local density approximation. Calculated electronic and lattice dielectric constants of CeO 2 are in good agreement with previous theoretical and experimental results. For Ce 2 O 3 , the hexagonal phase has a lattice dielectric constant comparable to that of CeO 2 , whereas the cubic phase has a much smaller one. We have concluded that the enhancement of the dielectric constant in CeO 2 epitaxially grown on Si is not due to its lattice expansion experimentally observed nor regular formation of oxygen vacancies in CeO 2

  15. Effect of Zr on dielectric, ferroelectric and impedance properties of ...

    Indian Academy of Sciences (India)

    Administrator

    Abstract. A polycrystalline sample of Zr-doped barium titanate (BaTiO3) was prepared by conventional solid state reaction method. The effect of Zr (0⋅15) on the structural and microstructural properties of BaTiO3 was investigated by XRD and SEM. The electrical properties (dielectric, ferroelectric and impedance spectro-.

  16. Effect of Zr on dielectric, ferroelectric and impedance properties of ...

    Indian Academy of Sciences (India)

    A polycrystalline sample of Zr-doped barium titanate (BaTiO3) was prepared by conventional solid state reaction method. The effect of Zr (0.15) on the structural and microstructural properties of BaTiO3 was investigated by XRD and SEM. The electrical properties (dielectric, ferroelectric and impedance spectroscopy) were ...

  17. Dielectric properties of plasma sprayed silicates subjected to additional annealing

    Czech Academy of Sciences Publication Activity Database

    Ctibor, Pavel; Sedláček, J.; Nevrlá, Barbara; Neufuss, Karel

    2017-01-01

    Roč. 10, č. 2 (2017), s. 105-114 ISSN 2008-2134 Institutional support: RVO:61389021 Keywords : Annealing * Dielectric properties * Plasma spraying * Silicates * Electrical properties * Insulators Subject RIV: JK - Corrosion ; Surface Treatment of Materials OBOR OECD: Coating and films http://pccc.icrc.ac.ir/Articles/1/18/990/

  18. Effect of aluminum addition on electrical properties, dielectric ...

    Indian Academy of Sciences (India)

    Effect of aluminum addition on electrical properties, dielectric characteristics, and its stability of (Pr, Co, Cr, Y)-added zinc oxide-based varistors. Choon-W Nahm. Electrical Properties Volume 33 Issue 3 June 2010 pp 239-245 ... Department of Electrical Engineering, Dongeui University, Busan 614-714, Republic of Korea ...

  19. Microwave measurement and modeling of the dielectric properties of vegetation

    Science.gov (United States)

    Shrestha, Bijay Lal

    Some of the important applications of microwaves in the industrial, scientific and medical sectors include processing and treatment of various materials, and determining their physical properties. The dielectric properties of the materials of interest are paramount irrespective of the applications, hence, a wide range of materials covering food products, building materials, ores and fuels, and biological materials have been investigated for their dielectric properties. However, very few studies have been conducted towards the measurement of dielectric properties of green vegetations, including commercially important plant crops such as alfalfa. Because of its high nutritional value, there is a huge demand for this plant and its processed products in national and international markets, and an investigation into the possibility of applying microwaves to improve both the net yield and quality of the crop can be beneficial. Therefore, a dielectric measurement system based upon the probe reflection technique has been set up to measure dielectric properties of green plants over a frequency range from 300 MHz to 18 GHz, moisture contents from 12%, wet basis to 79%, wet basis, and temperatures from -15°C to 30°C. Dielectric properties of chopped alfalfa were measured with this system over frequency range of 300 MHz to 18 GHz, moisture content from 11.5%, wet basis, to 73%, wet basis, and density over the range from 139 kg m-3 to 716 kg m-3 at 23°C. The system accuracy was found to be +/-6% and +/-10% in measuring the dielectric constant and loss factor respectively. Empirical, semi empirical and theoretical models that require only moisture content and operating frequency were determined to represent the dielectric properties of both leaves and stems of alfalfa at 22°C. The empirical models fitted the measured dielectric data extremely well. The root mean square error (RMSE) and the coefficient of determination (r2) for dielectric constant and loss factor of leaves

  20. Mixed 2D molecular systems: Mechanic, thermodynamic and dielectric properties

    Energy Technology Data Exchange (ETDEWEB)

    Beno, Juraj [Department of Physics, Faculty of Electrical Engineering and Information Technology, Slovak University of Technology, Ilkovicova 3, 812 19-SK Bratislava (Slovakia); Weis, Martin [Department of Physics, Faculty of Electrical Engineering and Information Technology, Slovak University of Technology, Ilkovicova 3, 812 19-SK Bratislava (Slovakia)], E-mail: Martin.Weis@stuba.sk; Dobrocka, Edmund [Department of Physics, Faculty of Electrical Engineering and Information Technology, Slovak University of Technology, Ilkovicova 3, 812 19-SK Bratislava (Slovakia); Institute of Electrical Engineering, Slovak Academy of Sciences, Dubravska cesta 9, 841 04-SK Bratislava (Slovakia); Hasko, Daniel [International Laser Centre, Ilkovicova 3, 812 19-SK Bratislava (Slovakia)

    2008-08-15

    Study of Langmuir monolayers consisting of stearic acid (SA) and dipalmitoylphosphatidylcholine (DPPC) molecules was done by surface pressure-area isotherms ({pi}-A), the Maxwell displacement current (MDC) measurement, X-ray reflectivity (XRR) and atomic force microscopy (AFM) to investigate the selected mechanic, thermodynamic and dielectric properties based on orientational structure of monolayers. On the base of {pi}-A isotherms analysis we explain the creation of stable structures and found optimal monolayer composition. The dielectric properties represented by MDC generated monolayers were analyzed in terms of excess dipole moment, proposing the effect of dipole-dipole interaction. XRR and AFM results illustrate deposited film structure and molecular ordering.

  1. Method to characterize dielectric properties of powdery substances

    Science.gov (United States)

    Tuhkala, M.; Juuti, J.; Jantunen, H.

    2013-07-01

    An open ended coaxial cavity method for dielectric characterization of powdery substance operating at 4.5 GHz in TEM mode is presented. Classical mixing rules and electromagnetic modeling were utilized with measured effective permittivities and Q factors to determine the relative permittivity and dielectric loss tangent of different powders with ɛr up to 30. The modeling enabled determination of the correction factor for the simplified equation for the relative permittivity of an open ended coaxial resonator and mixing rules having the best correlation with experiments. SiO2, Al2O3, LTCC CT 2000, ZrO2, and La2O3 powders were used in the experiments. Based on the measured properties and Bruggeman symmetric and Looyenga mixing rules, the determined dielectric characteristics of the powders exhibited good correlation with values in the literature. The presented characterization method enabled the determination of dielectric properties of powdery substances within the presented range, and therefore could be applied to various research fields and applications where dielectric properties of powders need to be known and controlled.

  2. Dielectric properties of hardwood species at microwave frequencies

    International Nuclear Information System (INIS)

    Sahin, H.; Ay, N.

    2004-01-01

    Dielectric measurements at 9.8 GHz and 2.45 GHz were made for the three hardwoods Euramerican hybrid poplar, alder, and oriental beech. The method used was based on Von Hippel's transmission line method. The measurements were carried out at room temperature of 20 deg - 24 deg C. The dielectric properties of the wood species were determined for the three principal structural directions at six different moisture conditions, covering the range of 0% to 28% moisture content. Results indicated that the behavior of all wood species studied is quantitatively similar. In general, the dielectric properties increase within the range studied with rising moisture content. The grain direction of the wood also plays a significant role

  3. Terahertz dielectric properties of multiwalled carbon nanotube/polyethylene composites

    Science.gov (United States)

    Dorozhkin, K. V.; Dunaevsky, G. E.; Sarkisov, S. Yu; Suslyaev, V. I.; Tolbanov, O. P.; Zhuravlev, V. A.; Sarkisov, Yu S.; Kuznetsov, V. L.; Moseenkov, S. I.; Semikolenova, N. V.; Zakharov, V. A.; Atuchin, V. V.

    2017-10-01

    The terahertz dielectric properties of multiwalled carbon nanotube/polyethylene (MWCNT/PE) composites prepared in different ways and with various contents of carbon nanotubes have been measured by terahertz time-domain spectroscopy. The experimental dielectric susceptibilities were modeled within effective medium approximation. The MWCNTs with average diameter of 9 nm produced by ethylene decomposition over FeCo catalyst were used in the experiments. Two types of composites were prepared by various mechanical mixing of MWCNT and polyethylene powders. The other two types of composites were fabricated employing ethylene polymerization on the MWCNTs before mechanical mixing with polyethylene powder. The samples with MWCNT concentration of 0.1, 0.5, 1 and 4 wt. % were prepared for each composite type. The measured dielectric susceptibilities were higher for composites made of nanotubes with preliminary polymerization of ethylene as compared to the composites produced by just mechanical mixing at equal concentrations of MWCNTs. It was also found that the dielectric susceptibilities of the MWCNT/PE composites can be satisfactory described within Maxwell–Garnett effective medium approximation at sufficient levels (>0.5–1 wt. %) of MWCNT contents. The obtained results confirm the possibility to produce MWCNT/PE composite materials with desired dielectric properties in terahertz range.

  4. Extraordinary Tales

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 20; Issue 10. Extraordinary Tales: Parasites Hijacking the Minds of Hosts. Felix Bast. General Article Volume 20 Issue 10 October 2015 pp ... Author Affiliations. Felix Bast1. Centre for Plant Sciences Central University of Punjab Bathinda 151 001, India ...

  5. Preparation, structural analysis and dielectric properties of Bi $ _ { ...

    Indian Academy of Sciences (India)

    Home; Journals; Pramana – Journal of Physics; Volume 58; Issue 5-6. Preparation, structural analysis and dielectric properties of Bi La 1 − FeO3 perovskite. V L Mathe K K Patankar M B Kothale S B Kulkarni P B Joshi S A Patil. Colossal Magnetoresistance & Other Materials Volume 58 Issue 5-6 May-June 2002 pp ...

  6. Dielectric and mechanical properties of plasma-sprayed olivine

    Czech Academy of Sciences Publication Activity Database

    Ctibor, Pavel; Neufuss, Karel; Pala, Zdeněk; Kotlan, Jiří; Soumar, J.

    2015-01-01

    Roč. 67, č. 2 (2015), s. 600-616 ISSN 1221-1451. [International Conference on Plasma Physics and Applications/16./. Magurele, Bucharest, 20.06.2013-25.06.2013] Institutional support: RVO:61389021 Keywords : olivine * plasma spraying * dielectric properties Subject RIV: JH - Ceramics, Fire-Resistant Materials and Glass Impact factor: 1.367, year: 2015 www.infim.ro/rrp

  7. Site-specific doping, tunable dielectric properties and intrinsic ...

    Indian Academy of Sciences (India)

    tive as well as quantitative dielectric properties. We also ... design [8]. Reduced TiMn samples also exhibit EPR signals (sextet pattern with hyper- fine splitting of around 84 Oe and Lande g factor of 2.005) due to the presence of Mn2+ .... ingly, doping small amounts (∼2%) of Mn ions at the Sr site induces sharp qualitative.

  8. Dielectric properties and structural dynamics of melt compounded ...

    Indian Academy of Sciences (India)

    Abstract. The dielectric properties of melt compounded hot-pressed nanocomposite films consisting of a poly(ethylene oxide) (PEO) and .... Prior to sample measurements, the open circuit calibration was performed to eliminate the ..... Here we present detailed structural analysis of PEO–OMMT nanocomposites using various ...

  9. Dielectric properties of biomass/biochar mixtures at microwave frequencies

    Science.gov (United States)

    Material dielectric properties are important for understanding their response to microwaves. Carbonaceous materials are considered good microwave absorbers and can be mixed with dry biomasses, which are otherwise low- loss materials, to improve the heating efficiency of biomass feedstocks. In this ...

  10. Tailoring magnetic and dielectric properties of rubber ferrite ...

    Indian Academy of Sciences (India)

    Unknown

    Abstract. Rubber ferrite composites containing various mixed ferrites were prepared for different compositions and various loadings. The magnetic and dielectric properties of the fillers as well as the ferrite filled matrixes were evaluated separately. The results are correlated. Simple equations are proposed to predetermine ...

  11. Effect of aluminum addition on electrical properties, dielectric ...

    Indian Academy of Sciences (India)

    Administrator

    added zinc oxide-based varistors. CHOON-W NAHM. Department of Electrical Engineering, Dongeui University, Busan 614-714, Republic of Korea. MS received 25 January 2009; revised 7 April 2009. Abstract. The electrical properties, dielectric characteristics, and its stability against d.c. accelerated aging stress of (Pr, Co, ...

  12. Sintering behaviour and microwave dielectric properties of a new ...

    Indian Academy of Sciences (India)

    427Nd0.182)TiO3; SmAlO3; microwave dielectric properties; oxygen octahedral distortion. 1. Introduction. The proliferation of commercial wireless technologies, such as cellular phones, global positioning systems and satellite broadcasting, has ...

  13. Electronic, mechanical and dielectric properties of silicane under tensile strain

    Energy Technology Data Exchange (ETDEWEB)

    Jamdagni, Pooja, E-mail: j.poojaa1228@gmail.com; Sharma, Munish; Ahluwalia, P. K. [Physics Department, Himachal Pradesh University, Shimla, Himachal Pradesh, India 171005 (India); Kumar, Ashok [Physics Department, Panjab University, Chandigarh, India, 160014 (India); Thakur, Anil [Physics Department, Govt. Collage Solan, Himachal Pradesh, India,173212 (India)

    2015-05-15

    The electronic, mechanical and dielectric properties of fully hydrogenated silicene i.e. silicane in stable configuration are studied by means of density functional theory based calculations. The band gap of silicane monolayer can be flexibly reduced to zero when subjected to bi-axial tensile strain, leading to semi-conducting to metallic transition, whereas the static dielectric constant for in-plane polarization increases monotonically with increasing strain. Also the EEL function show the red shift in resonance peak with tensile strain. Our results offer useful insight for the application of silicane monolayer in nano-optical and electronics devices.

  14. Electronic, mechanical and dielectric properties of silicane under tensile strain

    International Nuclear Information System (INIS)

    Jamdagni, Pooja; Sharma, Munish; Ahluwalia, P. K.; Kumar, Ashok; Thakur, Anil

    2015-01-01

    The electronic, mechanical and dielectric properties of fully hydrogenated silicene i.e. silicane in stable configuration are studied by means of density functional theory based calculations. The band gap of silicane monolayer can be flexibly reduced to zero when subjected to bi-axial tensile strain, leading to semi-conducting to metallic transition, whereas the static dielectric constant for in-plane polarization increases monotonically with increasing strain. Also the EEL function show the red shift in resonance peak with tensile strain. Our results offer useful insight for the application of silicane monolayer in nano-optical and electronics devices

  15. Preparation, structure and dielectric property of barium stannate titanate ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Wei Xiaoyong [Electronic Materials Research Laboratory, Key Laboratory of the Ministry of Education, Xi' an Jiaotong Univesity, Xi' an 710049 (China)]. E-mail: wdy@mail.xjtu.edu.cn; Yao Xi [Electronic Materials Research Laboratory, Key Laboratory of the Ministry of Education, Xi' an Jiaotong Univesity, Xi' an 710049 (China)

    2007-02-25

    The processing route of barium stannate titanate ceramics were optimized to prepare full composition range solid solution sample. The phase structure, microscopic morphology and dielectric properties of barium stannate titanate ceramics were studied. X-ray diffraction patterns indicated that the samples are of single perovskite structure. Linear empirical relationship between crystal lattice and tin content was proposed. This relationship is valid covering the full composition range, which suggests that this solid solution system is ultimate mutual soluble. The phase transition behavior was studied and a phase diagram was obtained based on the dielectric measurements.

  16. UV response on dielectric properties of nano nematic liquid crystal

    Science.gov (United States)

    Pandey, Kamal Kumar; Tripathi, Pankaj Kumar; Misra, Abhishek Kumar; Manohar, Rajiv

    2018-03-01

    In this work, we investigate the effect of UV light irradiation on the dielectric parameters of nematic liquid crystal (5CB) and ZnO nanoparticles dispersed liquid crystal. With addition of nanoparticles in nematic LC are promising new materials for a variety of application in energy harvesting, displays and photonics including the liquid crystal laser. To realize many applications, however we optimize the properties of liquid crystal and understand how the UV light irradiation interact the nanoparticles and LC molecules in dispersed/doped LC. The dielectric permittivity and loss factor have discussed the pure nematic LC and dispersed/doped system after, during and before UV light exposure. The dielectric relaxation spectroscopy was carried out in the frequency range 100 Hz-10 MHz in the nematic mesophase range.

  17. 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

  18. Study of dielectric properties of adulterated milk concentration and freshness

    Science.gov (United States)

    Jitendra Murthy, V.; Sai Kiranmai, N.; Kumar, Sanjeev

    2017-08-01

    The knowledge of dielectric properties may hold a potential to develop a new technique for quality evaluation of milk. The dielectric properties of water diluted cow’s milk with milk concentration from 70 percent to 100 percent stored during 36hour storage at 22°C and 144 hour at 5°C were measured at room temperature for frequencies ranging from 10 to 4500 MHz and at low, high & at microwave frequencies using X band bench and open-ended coaxial-line probe technology, along with electrical conductivity. The raw milk had the lowest dielectric constant (ɛ‧) when the frequency was higher than about 20M.Hz, and had the highest loss (ɛ″) or decepation factor tan (δ) at each frequency. The penetration depth (dp) increased with decreasing frequency, water content and storage time, which was large enough to detect dielectric properties changes in milk samples and provide large scale RF pasteurization processes. The loss factor can be an indicator in predicting milk concentration and freshness.

  19. A comparison between leaf dielectric properties of stressed and unstressed tomato plants

    NARCIS (Netherlands)

    Van Emmerik, T.H.M.; Steele-Dunne, S.C.; Judge, J.; Van de Giesen, N.C.

    2015-01-01

    Leaf dielectric properties influence microwave scattering from a vegetation canopy. The dielectric properties of leaves are primarily a function of leaf water content. Understanding the effect of water stress on leaf dielectric properties will give insight in how plant dynamics change as a result of

  20. Dielectric properties of materials at microwave frequencies

    Directory of Open Access Journals (Sweden)

    Ivo Křivánek

    2008-01-01

    Full Text Available The paper introduces the review of the present state of art in the measurement of the interaction of electromagnetic waves with different kinds of materials. It is analysis of the possibilities of the mea­surement of the interaction of high frequencies waves (microwaves with materials and proposal of the experimental method for the studies mentioned above.The electromagnetic field consists of two components: electric and magnetic field. The influence of these components on materials is different. The influence of the magnetic field is negligible and it has no impact on practical use. The influence of the electric field is strong as the interaction between them results in the creation of electric currents in the material (Křivánek and Buchar, 1993.Experiments focused on the evaluation of the complex dielectric permitivity of different materials have been performed. The permitivity of solid material is also measurable by phasemethod, when the specimen is a part of transmission sub-circuit. Microwave instrument for complex permittivity measurement works in X frequency band (8.2–12.5 GHz, the frequency 10.1 GHz was used for all the measurement in the laboratory of physics, Mendel University in Brno. The extensive number of experimental data have been obtained for different materials. The length of the square side of the ae­rial open end was 50 mm and internal dimensions of waveguides were 23 mm × 10 mm. The samples have form of the plate shape with dimensions 150 mm × 150 mm × 4 mm.

  1. GPR Laboratory Tests For Railways Materials Dielectric Properties Assessment

    Directory of Open Access Journals (Sweden)

    Francesca De Chiara

    2014-10-01

    Full Text Available In railways Ground Penetrating Radar (GPR studies, the evaluation of materials dielectric properties is critical as they are sensitive to water content, to petrographic type of aggregates and to fouling condition of the ballast. Under the load traffic, maintenance actions and climatic effects, ballast condition change due to aggregate breakdown and to subgrade soils pumping, mainly on existing lines with no sub ballast layer. The main purpose of this study was to validate, under controlled conditions, the dielectric values of materials used in Portuguese railways, in order to improve the GPR interpretation using commercial software and consequently the management maintenance planning. Different materials were tested and a broad range of in situ conditions were simulated in laboratory, in physical models. GPR tests were performed with five antennas with frequencies between 400 and 1800 MHz. The variation of the dielectric properties was measured, and the range of values that can be obtained for different material condition was defined. Additionally, in situ GPR measurements and test pits were performed for validation of the dielectric constant of clean ballast. The results obtained are analyzed and the main conclusions are presented herein.

  2. Equivalent circuit modeling of the dielectric properties of rubber wood at low frequency

    Science.gov (United States)

    Wan M. Daud; Kaida B. Khalid; Aziz H.A. Sidek

    2000-01-01

    Dielectric properties of rubber wood were studied at various moisture contents and grain directions at low frequencies from 10-2 to 105 Hz. Results showed that the moisture content of wood affected the dielectric properties considerably. Dielectric data at different anisotropic directions, i.e., longitudinal, radial, and...

  3. Measuring changes of radio-frequency dielectric properties of chicken meat during storage

    Science.gov (United States)

    Changes in dielectric properties of stored chicken meat were tracked by using a radio-frequency dielectric spectroscopy method. For this purpose, the dielectric properties were measured with an open-ended coaxial-line probe and vector network analyzer over a broad frequency range from 200 MHz to 20...

  4. Handbook on dielectric and thermal properties of microwaveable materials

    CERN Document Server

    Komarov, Vyacheslav V

    2012-01-01

    The application of microwave energy for thermal processing of different materials and substances is a rapidly growing trend in modern science and engineering. In fact, optimal design work involving microwaves is impossible without solid knowledge of the properties of these materials. Here s a practical reference that collects essential data on the dielectric and thermal properties of microwaveable materials, saving you countless hours on projects in a wide range of areas, including microwave design and heating, applied electrodynamics, food science, and medical technology. This unique book provides hard-to-find information on complex dielectric permittivity of media at industrial, scientific, and medical frequencies (430 MHz, 915MHz, 2.45GHz, 5.8 GHz, and 24.125GHz). Written by a leading expert in the field, this authoritative book does an exceptional job at presenting critical data on various materials and explaining what their key characteristics are concerning microwaves.

  5. Structural, dielectric and electrical properties of ...

    Indian Academy of Sciences (India)

    bronze structural family can be regarded (as being a deriva- tive of classical perovskite ... TB structural family. However, the complexity of TB struc- ture has provided many interesting and varieties of physical properties useful for applications. As TB is a .... characteristic peaks (which is different from those of the ingredients of ...

  6. Dielectric properties of plasma sprayed silicates

    Czech Academy of Sciences Publication Activity Database

    Ctibor, Pavel; Sedláček, J.; Neufuss, Karel; Dubský, Jiří; Chráska, Pavel

    -, č. 31 (2005), s. 315-321 ISSN 0272-8842 R&D Projects: GA ČR(CZ) GA202/03/0708 Institutional research plan: CEZ:AV0Z20430508 Keywords : Optical microscopy * electrical properties * silicates * insulators * plasma spraying Subject RIV: JH - Ceramics, Fire-Resistant Materials and Glass Impact factor: 0.702, year: 2005

  7. Synthesis, characterization, sintering and dielectric properties of ...

    Indian Academy of Sciences (India)

    Wintec

    The solution boils on heating and undergoes dehydration and decomposition leading to a smooth deflation and producing foam. The foam then ignites by itself ... Particulate properties of the combustion product were examined using transmission electron microscopy (TEM, Model-Hitachi H-600, Japan) operating at 200 kV.

  8. Dielectric properties of zirconium dioxide-based ceramics

    International Nuclear Information System (INIS)

    Vladimirova, O.S.; Gruzdev, A.I.; Koposova, Z.L.; Lyutsareva, L.A.

    1985-01-01

    This paper studies the dielectric properties of materials based on stabilized zirconium dioxide with Co 3 O 4 additions possessing a high temperature-coefficient of resistance. These materials are promising for manufacturing resistance temperature gages that work under an oxidizing atmosphere at 370-1270 degrees K. The obtained results indicate the possibility of developing temperature gases possessing highsensitivity from stabilized zirconium dioxide with Co 3 O 4 additions

  9. Effects of Bi doping on dielectric and ferroelectric properties

    Indian Academy of Sciences (India)

    [Pb0.95(La1−Bi)0.05][Zr0.53Ti0.47]O3 (PLBZT) ferroelectric thin films have been synthesized on indium tin oxide (ITO)-coated glass by sol–gel processing. PLBZT thin films were annealed at a relatively low temperature of 550 °C in oxygen ambient. Effects of Bi doping on structure, dielectric and ferroelectric properties of ...

  10. Materials Selection, Synthesis, and Dielectrical Properties of PVC Nanocomposites

    Directory of Open Access Journals (Sweden)

    Youssef Mobarak

    2013-01-01

    Full Text Available Materials selection process for electrical insulation application was carried out using Cambridge Engineering Selector (CES program. Melt mixing technique was applied to prepare polyvinyl-chloride- (PVC- nanofumed silica and nanomontmorillonite clay composites. Surface analysis and particles dispersibility were examined using scanning electron microscope. Dielectrical properties were assessed using Hipot tester. An experimental work for dielectric loss of the nanocomposite materials has been investigated in a frequency range of 10 Hz–50 kHz. The initial results using CES program showed that microparticles of silica and clay can improve electrical insulation properties and modulus of elasticity of PVC. Nano-montmorillonite clay composites were synthesized and characterized. Experimental analyses displayed that trapping properties of matrix are highly modified by the presence of nanofillers. The nanofumed silica and nanoclay particles were dispersed homogenously in PVC up to 10% wt/wt. Dielectric loss tangent constant of PVC-nanoclay composites was decreased successfully from 0.57 to 0.5 at 100 Hz using fillers loading from 1% to 10% wt/wt, respectively. Nano-fumed silica showed a significant influence on the electrical resistivity of PVC by enhancing it up to 1 × 1011 Ohm·m.

  11. Extraordinary properties of nematic phases of bent-core liquid crystals

    Science.gov (United States)

    Jákli, A.; Chambers, M.; Harden, J.; Madhabi, M.; Teeling, R.; Kim, J.; Li, Q.; Nair, G. G.; Éber, N.; Fodor-Csorba, K.; Gleeson, J. T.; Sprunt, S.

    2008-02-01

    We briefly review systematic and comprehensive studies on several chlorine-substituted bent-core liquid crystal materials in their nematic phases. The results, in comparison to rod-shaped molecules, are both extraordinary and technologically significant. Specifically: a) Electrohydrodynamic instabilities provide unique patterns including well defined, periodic stripes and optically isotropic structures. b) Rheological measurements using different probe techniques (dynamic light scattering, pulsed magnetic field, electrorotation) reveal that the ratio of the flow and rotational viscosities are over two orders of magnitudes larger in bentcore than in calamitic materials which proves that the molecule shape and not its size is responsible for this behaviour. c) Giant flexoelectric response, as measured by dynamic light scattering and by directly probing the induced current when the material is subject to oscillatory bend deformation, turns out to be more than three orders of magnitude larger than in calamitics and 50 times larger than molecular shape considerations alone would predict. The magnitude of this effect renders these materials as promising candidates for efficient conversion between mechanical and electrical energy. d) The converse of this effect when the bent-core material sandwiched between plastic substrates 4 times thicker than the liquid crystal material provided displacements in the range of 100nm that is sensitive to the polarity of the applied field thus suggesting applications as beam steering and precision motion controls.

  12. Dielectric properties of nickel doped bismuth lithium borate glasses

    Energy Technology Data Exchange (ETDEWEB)

    Dalal, Seema, E-mail: seemadal2014@gmail.com [Department of Physics, Baba Mast Nath University, Asthal Bohr, Rohtak-124001 (India); Department of Physics, Deenbandhu Chhotu Ram University of Science and Technology, Murthal-131039 (India); Dahiya, Sunita [Department of Physics, Baba Mast Nath University, Asthal Bohr, Rohtak-124001 (India); Ashima,; Khasa, S. [Department of Physics, Deenbandhu Chhotu Ram University of Science and Technology, Murthal-131039 (India)

    2016-05-23

    Glasses with composition xBi{sub 2}O{sub 3}•(30-x)Li{sub 2}O•70B{sub 2}O{sub 3} (x = 0, 2, 5, 7 and 10 mol% with codes BLBN1-5 respectively) containing 2 mol% of NiO were prepared via melt-quenching technique and dielectric properties are discussed. The dielectric properties have been studied using impedance spectroscopy. The frequency dependent conductivity investigations for prepared compositions have been carried out using impedance spectroscopy over a frequency range of 1 KHz to 5 MHz and in the temperature range of 300 K-523 K. The complex impedance data have been analyzed by using both the conductivity and the electric modulus formalisms. Standard dielectric behavior is observed in prepared samples. The ac conductivity variations satisfy the Arrhenius relation. The study of the equivalent circuit analysis up to a temperature of 473 K shows a significant change in the equivalent circuit with change in temperature and composition.

  13. Role of Ge incorporation in the physical and dielectric properties of ...

    Indian Academy of Sciences (India)

    The effect of Ge additive on the physical and dielectric properties of Se75Te25 and. Se85Te15 glassy ..... over a considerable distance, and the contribution to dielectric response can therefore be orders of magnitude ... 1 and 103 Hz. The sum of these four types of polarization represents the total polarization of a dielectric ...

  14. Structural, optical, morphological and dielectric properties of cerium oxide nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Prabaharan, Devadoss Mangalam Durai Manoharadoss [Department of Physics, NPR College of Engineering and Technology, Natham, Dindigul, Tamil Nadu (India); Sadaiyandi, Karuppasamy [Department of Physics, Alagappa Government Arts College, Karaikudi, Sivaganga, Tamil Nadu (India); Mahendran, Manickam [Department of Physics, Thiagarajar College of Engineering, Madurai, Tamil Nadu (India); Sagadevan, Suresh, E-mail: duraiphysics2011@gmail.com [Department of Physics, AMET University (India)

    2016-03-15

    Cerium oxide (CeO{sub 2}) nanoparticles were prepared by the precipitation method. The average crystallite size of cerium oxide nanoparticles was calculated from the X-ray diffraction (XRD) pattern and found to be 11 nm. The FT-IR spectrum clearly indicated the strong presence of cerium oxide nanoparticles. Raman spectrum confirmed the cubic nature of the cerium oxide nanoparticles. The Scanning Electron Microscopy (SEM) analysis showed that the nanoparticles agglomerated forming spherical-shaped particles. The Transmission Electron Microscopic (TEM) analysis confirmed the prepared cerium oxide nanoparticles with the particle size being found to be 16 nm. The optical absorption spectrum showed a blue shift by the cerium oxide nanoparticles due to the quantum confinement effect. The dielectric properties of cerium oxide nanoparticles were studied for different frequencies at different temperatures. The dielectric constant and the dielectric loss of the cerium oxide nanoparticles decreased with increase in frequency. The AC electrical conductivity study revealed that the conduction depended on both the frequency and the temperature. (author)

  15. Dielectrical properties of PANI/TiO{sub 2} nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Chaturmukha, V. S.; Naveen, C. S.; Rajeeva, M. P.; Avinash, B. S.; Jayanna, H. S.; Lamani, Ashok R., E-mail: ashok1571972@gmail.com [Department of PG Studies and Research in Physics, Kuvempu University, Shankaraghatta-577451, Shimoga, Karnataka (India)

    2016-05-23

    Conducting polyaniline/titanium dioxide (PANI/TiO{sub 2}) composites have been succesfully synthesized by insitu polymerization technique. The PANI/TiO{sub 2} nanocomposites of different compositions were prepared by varying weight percentage of TiO{sub 2} nanoparticles such as 10 wt%, 20 wt%, 30 wt%, 40 wt% and 50 wt% into the fixed amount of the aniline monomer. The prepared powder samples were characterized by X-ray diffractometer (XRD) and Scanning electron microscope (SEM). The intensity of diffraction peaks for PANI/TiO{sub 2} composites is lower than that for TiO{sub 2}. SEM pictures show that the nanocomposite were prepared in the form of long PANi chains decorated with TiO{sub 2} nanoparticles. The dielectric properties and AC conductivity were studied in the frequency range1K Hz–10M Hz. At higher frequencies, the composites exhibit almost zero dielectric loss and maximum value of σ{sub ac} is found for a concentration of 20 wt% TiO{sub 2} in polyaniline. The interface between polyaniline and TiO{sub 2} plays an important role in yielding a large dielectric constant in nanocomposites.

  16. Atomistic determination of flexoelectric properties of crystalline dielectrics

    Science.gov (United States)

    Maranganti, R.; Sharma, P.

    2009-08-01

    Upon application of a uniform strain, internal sublattice shifts within the unit cell of a noncentrosymmetric dielectric crystal result in the appearance of a net dipole moment: a phenomenon well known as piezoelectricity. A macroscopic strain gradient on the other hand can induce polarization in dielectrics of any crystal structure, even those which possess a centrosymmetric lattice. This phenomenon, called flexoelectricity, has both bulk and surface contributions: the strength of the bulk contribution can be characterized by means of a material property tensor called the bulk flexoelectric tensor. Several recent studies suggest that strain-gradient induced polarization may be responsible for a variety of interesting and anomalous electromechanical phenomena in materials including electromechanical coupling effects in nonuniformly strained nanostructures, “dead layer” effects in nanocapacitor systems, and “giant” piezoelectricity in perovskite nanostructures among others. In this work, adopting a lattice dynamics based microscopic approach we provide estimates of the flexoelectric tensor for certain cubic crystalline ionic salts, perovskite dielectrics, III-V and II-VI semiconductors. We compare our estimates with experimental/theoretical values wherever available and also revisit the validity of an existing empirical scaling relationship for the magnitude of flexoelectric coefficients in terms of material parameters. It is interesting to note that two independent groups report values of flexoelectric properties for perovskite dielectrics that are orders of magnitude apart: Cross and co-workers from Penn State have carried out experimental studies on a variety of materials including barium titanate while Catalan and co-workers from Cambridge used theoretical ab initio techniques as well as experimental techniques to study paraelectric strontium titanate as well as ferroelectric barium titanate and lead titanate. We find that, in the case of perovskite

  17. Dielectric Properties of 3D Printed Polylactic Acid

    Directory of Open Access Journals (Sweden)

    Claudius Dichtl

    2017-01-01

    Full Text Available 3D printers constitute a fast-growing worldwide market. These printers are often employed in research and development fields related to engineering or architecture, especially for structural components or rapid prototyping. Recently, there is enormous progress in available materials for enhanced printing systems that allow additive manufacturing of complex functional products, like batteries or electronics. The polymer polylactic acid (PLA plays an important role in fused filament fabrication, a technique used for commercially available low-budget 3D printers. This printing technology is an economical tool for the development of functional components or cases for electronics, for example, for lab purposes. Here we investigate if the material properties of “as-printed” PLA, which was fabricated by a commercially available 3D printer, are suitable to be used in electrical measurement setups or even as a functional material itself in electronic devices. For this reason, we conduct differential scanning calorimetry measurements and a thorough temperature and frequency-dependent analysis of its dielectric properties. These results are compared to partially crystalline and completely amorphous PLA, indicating that the dielectric properties of “as-printed” PLA are similar to the latter. Finally, we demonstrate that the conductivity of PLA can be enhanced by mixing it with the ionic liquid “trihexyl tetradecyl phosphonium decanoate.” This provides a route to tailor PLA for complex functional products produced by an economical fused filament fabrication.

  18. Dielectric loss property of strong acids doped polyaniline (PANi)

    Science.gov (United States)

    Amalia, Rianti; Hafizah, Mas Ayu Elita; Andreas, Manaf, Azwar

    2018-04-01

    In this study, strong acid doped polyaniline (PANi) has been successfully fabricated through the chemical oxidative polymerization process with various polymerization times. Nonconducting PANi resulting from the polymerization process at various polymerization times were then doped by a strong acid HClO4 to generate dielectric properties. Ammonium Persulfate (APS) as an initiator was used during Polymerization process to develop dark green precipitates which then called Emeraldine Base Polyaniline (PANi-EB). The PANi-EB was successively doped by strong acid HClO4 with dopant and PANi ratio 10:1 to enhance the electrical conductivity. The conductivity of doped PANi was evaluated by Four Point Probe. Results of evaluation showed that the conductivity values of HClO4 doped PANi were in the range 337-363 mS/cm. The dielectric properties of doped PANi were evaluated by Vector Network Analyzer (VNA) which suggested that an increase in the permittivity value in the conducting PANi. It is concluded that PANi could be a potential candidate for electromagnetic waves absorbing materials.

  19. Direct measurement of the dielectric polarization properties of DNA

    Science.gov (United States)

    Cuervo, Ana; Dans, Pablo D.; Carrascosa, José L.; Orozco, Modesto; Gomila, Gabriel; Fumagalli, Laura

    2014-01-01

    The electric polarizability of DNA, represented by the dielectric constant, is a key intrinsic property that modulates DNA interaction with effector proteins. Surprisingly, it has so far remained unknown owing to the lack of experimental tools able to access it. Here, we experimentally resolved it by detecting the ultraweak polarization forces of DNA inside single T7 bacteriophages particles using electrostatic force microscopy. In contrast to the common assumption of low-polarizable behavior like proteins (εr ∼ 2–4), we found that the DNA dielectric constant is ∼8, considerably higher than the value of ∼3 found for capsid proteins. State-of-the-art molecular dynamic simulations confirm the experimental findings, which result in sensibly decreased DNA interaction free energy than normally predicted by Poisson–Boltzmann methods. Our findings reveal a property at the basis of DNA structure and functions that is needed for realistic theoretical descriptions, and illustrate the synergetic power of scanning probe microscopy and theoretical computation techniques. PMID:25136104

  20. Microstructure and dielectric properties of biocarbon nanofiber composites

    Science.gov (United States)

    Dai, Bo; Ren, Yong; Wang, Gaihua; Ma, Yongjun; Zhu, Pei; Li, Shirong

    2013-06-01

    A kind of web-like carbon with interconnected nanoribbons was fabricated using bacterial cellulose pyrolyzed at various temperatures, and the microwave dielectric properties were investigated. Bacterial cellulose was converted into carbonized bacterial cellulose (CBC) with a novel three-dimensional web built of entangled and interconnected cellulose ribbons when the carbonization temperature was below 1,200°C; the web-like structure was destroyed at a temperature of 1,400°C. Composites of CBC impregnated with paraffin wax exhibited high complex permittivity over a frequency range of 2 to 18 GHz, depending on the carbonization temperature. Both real and imaginary parts were the highest for CBC pyrolyzed at 1,200°C. The complex permittivity also strongly depended on CBC loadings. For 7.5 wt.% loading, the real and imaginary permittivities were about 12 and 4.3, respectively, and the minimum reflection loss was -39 dB at 10.9 GHz. For 30 wt.% loading, the real and imaginary permittivities were about 45 and 80, respectively, and the shielding efficiency was more than 24 dB in the measured frequency range and could be up to 39 dB at 18 GHz. The electromagnetic properties were assumed to correlate with both the dielectric relaxation and the novel web-like structure.

  1. Dielectric and Radiative Properties of Sea Foam at Microwave Frequencies: Conceptual Understanding of Foam Emissivity

    OpenAIRE

    Peter W. Gaiser; Magdalena D. Anguelova

    2012-01-01

    Foam fraction can be retrieved from space-based microwave radiometric data at frequencies from 1 to 37 GHz. The retrievals require modeling of ocean surface emissivity fully covered with sea foam. To model foam emissivity well, knowledge of foam properties, both mechanical and dielectric, is necessary because these control the radiative processes in foam. We present a physical description of foam dielectric properties obtained from the foam dielectric constant including foam skin depth; foam ...

  2. Dielectric properties of Al-substituted Co ferrite nanoparticles

    Indian Academy of Sciences (India)

    Administrator

    tric loss, ε″ and dielectric loss tangent, tan δ, have been studied for nanocrystalline ferrite samples as a func- tion of frequency. The dielectric constant and dielectric loss obtained for the nanocrystalline ferrites proposed by this technique possess lower value than that of the ferrites prepared by other methods for the same ...

  3. Dielectric properties of KDP-type ferroelectric crystals in the ...

    Indian Academy of Sciences (India)

    renormalized soft mode frequency, Curie temperature, dielectric constant and dielectric loss are evaluated. ... temperature and electric field dependences of soft mode frequency, dielectric constant and loss have been ... its ability to generate second- and third-harmonics of higher power Nd:YAG and. Nd:glass lasers [2].

  4. Dielectric properties of alumina/zirconia composites at millimeter wavelengths

    International Nuclear Information System (INIS)

    Molla, J.; Heidinger, R.; Ibarra, A.; Link, G.

    1994-01-01

    Alumina-zirconia composites with ZrO 2 contents up to 20% and negligible porosity were investigated at millimeter (mm) wavelengths to determine the changes appearing in the dielectric properties of pure alumina ceramics when unstabilized or partially stabilized ZrO 2 is added to improve the mechanical strength. It is demonstrated that it essential to distinguish between the contributions of the monoclinic and the tetragonal phase of zirconia (m-ZrO 2 , t-ZrO 2 ). Permittivity is raised with increasing content of either phases; the effective permittivity can be assessed by the rule of mixtures (Maxwell-Garnett formulation of the generalized Clasussius-Mossotti relation) using permittivity values of 10 for Al 2 O 3 , 14-21 for m-ZrO 2 and 40-45 for t-ZrO 2 . The permittivity data show only a small variation in the investigated range of 9-145 GHz. For the dielectric loss, there is evidence of a predominant contribution of m-ZrO 2 ; in addition, the marked increase in loss with frequency becomes sharper. The t-ZrO 2 , which is responsible for strengthening, does not show any significant influence on losses. It is therefore concluded, that ZrO 2 strengthening of alumina is feasible without affecting mm-wave losses at room temperature as long as the presence of m-ZrO 2 is avoided

  5. Electrical Conductivity and Dielectrical Properties of Bulk Methylene Green

    Science.gov (United States)

    El-Menyawy, E. M.; Zedan, I. T.; Mansour, A. M.

    2017-07-01

    Thermal stability, direct current electrical conductivity ( σ DC), alternating current electrical conductivity ( σ AC) and dielectric properties of bulk methylene green (MG) have been investigated. The thermal stability of MG was studied by differential scanning calorimetry and thermogravimetry techniques. Temperature dependence of σ DC showed that the MG has semiconductor behavior with two activation energies determined as 0.12 eV and 0.31 eV in the temperature range 303-343 K and 363-463 K, respectively. The σ AC of bulk MG was performed in the frequency range 150 Hz-5 MHz and temperature range 303-463 K. The dependence of AC conductivity on frequency for MG is found to satisfy Jonscher's universal power law, especially at high frequencies. The correlated barrier hopping model is found to be applicable in which the density of localized states is determined. The σ AC is thermally activated and the activation energy decreases with the increases in frequency. The variation of the real and imaginary parts of the dielectric constant with the frequency and temperature is explained.

  6. Study on chitosan film properties as a green dielectric

    Science.gov (United States)

    Nainggolan, I.; Nasution, T. I.; Putri, S. R. E.; Azdena, D.; Balyan, M.; Agusnar, H.

    2018-02-01

    Chitosan film dielectrics to produce an electrostatic capacitor were prepared by the solution cast technique. The charging and discharging of the capacitor were done using RC series circuit with DC voltage supply because chitosan has bipolar properties. First testing was by varying supply voltage of 1, 3, 5, 10 and 15 V, respectively, and could be determined that the most effective voltage for chitosan film can be well polarised is 5 V. The results of second testing for the use of 5 V supply showed that the capacitance of a chitosan film capacitor decreased with the increase in load value. For loads of 100, 1K, 10K, 100K and 1M Ω, the capacitance values of the chitosan film capacitor were 3.1725, 0.4136, 0.05379, 0.007917 and 0.001522 F, respectively. It was also found that the increase in voltage of the capacitor at charging process was faster for the lower load. Therefore, the research result has corresponded to the general formula that used to calculate the capacitance value and thus, the biopolymer chitosan has potential as a sustainable green dielectric.

  7. A Review: Origins of the Dielectric Properties of Proteins and Potential Development as Bio-Sensors

    Directory of Open Access Journals (Sweden)

    Fabien Bibi

    2016-08-01

    Full Text Available Polymers can be classified as synthetic polymers and natural polymers, and are often characterized by their most typical functions namely their high mechanical resistivity, electrical conductivity and dielectric properties. This bibliography report consists in: (i Defining the origins of the dielectric properties of natural polymers by reviewing proteins. Despite their complex molecular chains, proteins present several points of interest, particularly, their charge content conferring their electrical and dielectric properties; (ii Identifying factors influencing the dielectric properties of protein films. The effects of vapors and gases such as water vapor, oxygen, carbon dioxide, ammonia and ethanol on the dielectric properties are put forward; (iii Finally, potential development of protein films as bio-sensors coated on electronic devices for detection of environmental changes particularly humidity or carbon dioxide content in relation with dielectric properties variations are discussed. As the study of the dielectric properties implies imposing an electric field to the material, it was necessary to evaluate the impact of frequency on the polymers and subsequently on their structure. Characterization techniques, on the one hand dielectric spectroscopy devoted for the determination of the glass transition temperature among others, and on the other hand other techniques such as infra-red spectroscopy for structure characterization as a function of moisture content for instance are also introduced.

  8. A Review: Origins of the Dielectric Properties of Proteins and Potential Development as Bio-Sensors.

    Science.gov (United States)

    Bibi, Fabien; Villain, Maud; Guillaume, Carole; Sorli, Brice; Gontard, Nathalie

    2016-08-04

    Polymers can be classified as synthetic polymers and natural polymers, and are often characterized by their most typical functions namely their high mechanical resistivity, electrical conductivity and dielectric properties. This bibliography report consists in: (i) Defining the origins of the dielectric properties of natural polymers by reviewing proteins. Despite their complex molecular chains, proteins present several points of interest, particularly, their charge content conferring their electrical and dielectric properties; (ii) Identifying factors influencing the dielectric properties of protein films. The effects of vapors and gases such as water vapor, oxygen, carbon dioxide, ammonia and ethanol on the dielectric properties are put forward; (iii) Finally, potential development of protein films as bio-sensors coated on electronic devices for detection of environmental changes particularly humidity or carbon dioxide content in relation with dielectric properties variations are discussed. As the study of the dielectric properties implies imposing an electric field to the material, it was necessary to evaluate the impact of frequency on the polymers and subsequently on their structure. Characterization techniques, on the one hand dielectric spectroscopy devoted for the determination of the glass transition temperature among others, and on the other hand other techniques such as infra-red spectroscopy for structure characterization as a function of moisture content for instance are also introduced.

  9. Effect of dielectric confinement on optical properties of colloidal nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Rodina, A. V., E-mail: anna.rodina@mail.ioffe.ru [Russian Academy of Sciences, Ioffe Physicotechnical Institute (Russian Federation); Efros, Al. L., E-mail: efros@nrl.navy.mil [Naval Research Laboratory (United States)

    2016-03-15

    We review the effects caused by a large difference in the dielectric constants of a semiconductor and its surrounding in colloidal semiconductor nanostructures (NSs) with various shapes, e.g., nanocrystals, nanorods, and nanoplatelets. The difference increases the electron–hole interaction and consequently the exciton binding energy and its oscillator transition strength. On the other hand, this difference reduces the electric field of a photon penetrating the NS (the phenomenon is called the local field effect) and reduces the photon coupling to an exciton. We show that the polarization properties of the individual colloidal NSs as well as of their randomly oriented ensemble are determined both by the anisotropy of the local field effect and by the symmetry of the exciton states participating in optical transitions. The calculations explain the temperature and time dependences of the degree of linear polarization measured in an ensemble of CdSe nanocrystals.

  10. Scandium doped Strontium Titanate Ceramics: Structure, Microstructure, and Dielectric Properties

    Directory of Open Access Journals (Sweden)

    Tkach, Alexander

    2008-08-01

    Full Text Available Sc-doped strontium titanate (ST ceramics were synthesised by solid state reaction, according to the composition Sr1-1.5xScxTiO3 with x = 0-0.01. Structural properties and microstructure development was examined by XRD and SEM. The dielectric properties were evaluated as a function of the temperature and frequency in the radio frequency range. Lattice parameter, density and grain size, were found to decrease slightly with increasing Sc content. The dielectric permittivity and losses decrease also. Sc-doping has only a weak effect on the quantum paraelectric behaviour of ST and no dielectric anomaly was observed, what is probably related to the limited solubility of Sc on the Sr site of the perovskite lattice of ST.

    Se sintetizaron materiales cerámicos de titanato de estroncio dopado con escandio mediante reacción en estado sólido De acuerdo a la composición Sr1-1.5xScxTiO3 con x= 0-0.1. Las propiedades estructurales y el desarrollo microestructural se estudiaron mediante XRD y SEM. La propiedades dieléctricas se estudiaron como función de la temperatura y de la frecuencia en el rango de la frecuencias de radio. Se observó que los parámetros de red, la densidad y el tamaño del grano disminuyen ligeramente con el contenido en Sc. La permitividad dieléctrica y las perdidas también disminuyen. El dopado con Sc tiene un efecto muy ligero sobre el comportamiento paraeléctrico cuántico del titanato de estroncio y no se observó anomalías dioeléctricas , lo que está probablemente relacionado con la baja solubilidad del Sc en posiciones del Sr en la estructura tipo perovskita del titanato de estroncio.

  11. Dielectric properties of ligand-modified gold nanoparticles/SU-8 photopolymer based nanocomposites

    KAUST Repository

    Toor, Anju

    2017-04-15

    This article reports the enhanced dielectric properties of a photodefinable nanocomposite material containing sub–10 nm coated metal nanoparticles (NPs). The surface morphology of the synthesized dodecanethiol-functionalized gold NPs was characterized using the transmission electron microscopy (TEM). We investigated the particle agglomeration and dispersion during the various stages of the nanocomposite synthesis using TEM. Physical properties such as dielectric permittivity and dielectric loss were measured experimentally. The dependence of dielectric permittivity and loss tangent on particle concentration and frequency was studied. Nanocomposite films showed an approximately three times enhancement in average dielectric constant over the polymer base value and an average dielectric loss of 0.09 at 1 kHz, at a filler loading of 10% w/w.

  12. Microwave Dielectric Properties of Soil and Vegetation and Their Estimation From Spaceborne Radar

    Science.gov (United States)

    Dobson, M. Craig; McDonald, Kyle C.

    1996-01-01

    This paper is largely tutorial in nature and provides an overview of the microwave dielectric properties of certain natural terrestrial media (soils and vegetation) and recent results in estimating these properties remotely from airborne and orbital synthetic aperture radar (SAR).

  13. Numerical studies on the electromagnetic properties of the nonlinear Lorentz Computational model for the dielectric media

    International Nuclear Information System (INIS)

    Abe, H.; Okuda, H.

    1994-06-01

    We study linear and nonlinear properties of a new computer simulation model developed to study the propagation of electromagnetic waves in a dielectric medium in the linear and nonlinear regimes. The model is constructed by combining a microscopic model used in the semi-classical approximation for the dielectric media and the particle model developed for the plasma simulations. It is shown that the model may be useful for studying linear and nonlinear wave propagation in the dielectric media

  14. 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.

  15. 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.

  16. 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

  17. Dielectric Properties of Water in Butter and Water-AOT-Heptane Systems Measured using Terahertz Time-Domain Spectroscopy

    DEFF Research Database (Denmark)

    Møller, Uffe; Folkenberg, Jacob Riis; Jepsen, Peter Uhd

    2010-01-01

    We investigate the dielectric properties of water confined in nanometer-sized inverse micelles in mixtures of water, AOT, and heptane. We show that the dielectric properties of the confined water are dependent on the water pool size and different from those of bulk water. We also discuss...... the dielectric properties of different vegetable oils, lard, and butter, and use these properties to deduce the dielectric properties of water in butter, which are shown to deviate significantly from the dielectric properties of bulk water....

  18. Local Electronic And Dielectric Properties at Nanosized Interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Bonnell, Dawn A. [Univ. of Pennsylvania, Philadelphia, PA (United States)

    2015-02-23

    Final Report to the Department of Energy for period 6/1/2000 to 11/30/2014 for Grant # DE-FG02-00ER45813-A000 to the University of Pennsylvania Local Electronic And Dielectric Properties at Nanosized Interfaces PI: Dawn Bonnell The behavior of grain boundaries and interfaces has been a focus of fundamental research for decades because variations of structure and composition at interfaces dictate mechanical, electrical, optical and dielectric properties in solids. Similarly, the consequence of atomic and electronic structures of surfaces to chemical and physical interactions are critical due to their implications to catalysis and device fabrication. Increasing fundamental understanding of surfaces and interfaces has materially advanced technologies that directly bear on energy considerations. Currently, exciting developments in materials processing are enabling creative new electrical, optical and chemical device configurations. Controlled synthesis of nanoparticles, semiconducting nanowires and nanorods, optical quantum dots, etc. along with a range of strategies for assembling and patterning nanostructures portend the viability of new devices that have the potential to significantly impact the energy landscape. As devices become smaller the impact of interfaces and surfaces grows geometrically. As with other nanoscale phenomena, small interfaces do not exhibit the same properties as do large interfaces. The size dependence of interface properties had not been explored and understanding at the most fundamental level is necessary to the advancement of nanostructured devices. An equally important factor in the behavior of interfaces in devices is the ability to examine the interfaces under realistic conditions. For example, interfaces and boundaries dictate the behavior of oxide fuel cells which operate at extremely high temperatures in dynamic high pressure chemical environments. These conditions preclude the characterization of local properties during fuel cell

  19. Electronic and dielectric properties of MoS{sub 2}-MoX{sub 2} heterostructures

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, Munish, E-mail: munishsharmahpu@live.com; Jamdagni, Pooja; Ahluwalia, P. K, E-mail: pk-ahluwalia7@yahoo.com [Department. of Physics, Himachal Pradesh University, Shimla, H. P., 171005 (India); Kumar, Ashok [Department. of Physics, Panjab University, Chandigarh, 160014 (India)

    2015-05-15

    We present a comparative study of electronic and dielectric properties of MoS{sub 2}−MoX{sub 2} heteostructures (where X=S, Se, Te) within the framework of density functional theory (DFT). Electronic band structure, real and imaginary part of dielectric function, electron energy loss spectra and static dielectric constant have been calculated for each system and compared with one another. A systematic decrease/increase in band gap/static dielectric constant is observed as the X changes from S to Te. These results provide a physical basis for the potential applications of these heterostructures in optoelectronic devices.

  20. Effect of swift heavy ion (SHI) irradiation on dielectric properties of acetoacetanilide crystals

    Energy Technology Data Exchange (ETDEWEB)

    Prabhu, Sharada G.; Mohan Rao, P. E-mail: padakannayamrao@yahoo.com; Avasthi, D.K.; Guptha, Shiuli

    2001-03-01

    Dielectric properties of non-linear organic crystals of acetoacetanilide are studied before and after irradiation. Crystals are irradiated by 120 MeV Ag{sup 13+} ions. The variation of dielectric constant, dielectric loss, ac conductivity and the loss factor of both unirradiated and irradiated samples are measured, at different fluences. The defects produced due to irradiation, cause an increase in dielectric constant. At higher fluence, i.e. 10{sup 12} ions/cm{sup 2}, the defects are found to anneal out.

  1. Dielectric properties of piezoelectric 3–0 composites of lithium ferrite ...

    Indian Academy of Sciences (India)

    Unknown

    In the present work, piezoelectric 3–0 composites with lithium ferrite. (LiFe5O8) and barium titanate (BaTiO3) as the constituent phases, are synthesized. Barium titanate is a ferroelectric with widespread appli- cations as capacitor material because of its high dielectric constant. Dielectric properties are found to be dependent.

  2. Dielectric properties of dried vegetable powders and their temperature profile during radio frequency heating

    Science.gov (United States)

    Recently, Salmonella contamination was identified in low-moisture foods including dried vegetable powder. Radio Frequency (RF) dielectric heating is a potential alternative pasteurization method with short heating time. Dielectric properties of broccoli powder with 6.9, 9.1, 12.2, and 14.9%, w. b....

  3. Measuring and modeling of radiofrequency dielectric properties of chicken breast meat

    Science.gov (United States)

    Dielectric properties of chicken breast meat are important for both dielectric heating and quality sensing applications. In heating applications they allow optimization of energy transfer and uniformity of heating. In sensing applications, they can be used to predict quality attributes of the chicke...

  4. Influence of x-rays on the radiofrequency dielectric properties of ...

    African Journals Online (AJOL)

    The radiofrequency dielectric properties of x-irradiated and non-irradiated bovine kidney tissues have been investigated. The relative permittivity α , the dielectric loss factor α , and the a.c conductivity α of the tissues have been measured in the frequency range 1.0 to 50.0 MHz using a Marconi Q-meter, TF 1245 working in ...

  5. 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.

  6. Dielectric properties of Zea mays kernels - studies for microwave power processing applications

    Energy Technology Data Exchange (ETDEWEB)

    Surducan, Emanoil; Neamtu, Camelia; Surducan, Vasile, E-mail: emanoil.surducan@itim-cj.r [National Institute for Research and Development of Isotopic and Molecular Technologies, 65-103 Donath, 400293 Cluj-Napoca (Romania)

    2009-08-01

    Microwaves absorption in biological samples can be predicted by their specific dielectrical properties. In this paper, the dielectric properties ({epsilon}' and {epsilon}'') of corn (Zea mays) kernels in the 500 MHz - 20 GHz frequencies range are presented. A short analysis of the microwaves absorption process is also presented, in correlation with the specific thermal properties of the samples, measured by simultaneous TGA-DSC method.

  7. Influence of the temperature on the dielectric properties of epoxy resins

    OpenAIRE

    Dodd, S. J.; Chalashkanov, N. M.; Fothergill, J.; Dissado, L. A.

    2010-01-01

    Electrical degradation processes in epoxy resins, such as electrical treeing, were found to be dependent on the temperature at which the experiments were carried out. Therefore, it is of considerable research interest to study the influence of temperature on the dielectric properties of the polymers and to relate the effect of temperature on these properties to the possible electrical degradation mechanisms. In this work, the dielectric properties of two different epoxy resin systems have bee...

  8. Growth, characterization and dielectric property studies of gel grown ...

    Indian Academy of Sciences (India)

    Administrator

    Dielectric constant and dielectric loss have been calculated and discussed as a function of frequency at different temperatures. ... The stock solu- tion is added until the pH of the gel is set at the desired value. Test tubes were then tightly closed to prevent evaporation and contamination of the exposed surface of the gel by ...

  9. Infrared Dielectric Properties of Low-Stress Silicon Oxide

    Science.gov (United States)

    Cataldo, Giuseppe; Wollack, Edward J.; Brown, Ari D.; Miller, Kevin H.

    2016-01-01

    Silicon oxide thin films play an important role in the realization of optical coatings and high-performance electrical circuits. Estimates of the dielectric function in the far- and mid-infrared regime are derived from the observed transmittance spectrum for a commonly employed low-stress silicon oxide formulation. The experimental, modeling, and numerical methods used to extract the dielectric function are presented.

  10. Structural, dielectric and electrical properties of Sm-modified Pb ...

    Indian Academy of Sciences (India)

    Unknown

    diffraction (XRD) analysis, detailed temperature and frequency dependence dielectric measurements on them. The a.c. conductivity has been investigated over a wide range of temperature and the activation energy (Ea.c.) has also been calculated. It is observed that (i) the dielectric permittivity (ε) and loss tangent (tan δ) are.

  11. Effect of Biomass Waste Filler on the Dielectric Properties of Polymer Composites

    Directory of Open Access Journals (Sweden)

    Yew Been Seok

    2016-07-01

    Full Text Available The effect of biomass waste fillers, namely coconut shell (CS and sugarcane bagasse (SCB on the dielectric properties of polymer composite was investigated. The aim of this study is to investigate the potential of CS and SCB to be used as conductive filler (natural source of carbon in the polymer composite. The purpose of the conductive filler is to increase the dielectric properties of the polymer composite. The carbon composition the CS and SCB was determine through carbon, hydrogen, nitrogen and sulphur (CHNS elemental analysis whereas the structural morphology of CS and SCB particles was examined by using scanning electron microscope. Room temperature open-ended coaxial line method was used to determine the dielectric constant and dielectric loss factor over broad band frequency range of 200 MHz-20 GHz. Based on this study, the results found that CS and SCB contain 48% and 44% of carbon, which is potentially useful to be used as conductive elements in the polymer composite. From SEM morphology, presence of irregular shape particles (size ≈ 200 μm and macroporous structure (size ≈ 2.5 μm were detected on CS and SCB. For dielectric properties measurement, it was measured that the average dielectric constant (ε' is 3.062 and 3.007 whereas the average dielectric loss factor (ε" is 0.282 and 0.273 respectively for CS/polymer and SCB/polymer composites. The presence of the biomass waste fillers have improved the dielectric properties of the polymer based composite (ε' = 2.920, ε" = 0.231. However, the increased in the dielectric properties is not highly significant, i.e. up to 4.86 % increase in ε' and 20% increase in ε". The biomass waste filler reinforced polymer composites show typical dielectric relaxation characteristic at frequency of 10 GHz - 20 GHz and could be used as conducting polymer composite for suppressing EMI at high frequency range.

  12. Influence of color on dielectric properties of marinated poultry breast meat.

    Science.gov (United States)

    Samuel, D; Trabelsi, S

    2012-08-01

    The dielectric behavior of foods when exposed to radio-frequency and microwave electric fields is highly influenced by moisture content and the degree of water binding with constituents of the food materials. The ability to correlate specific food quality characteristics with the dielectric properties can lead to the development of rapid, nondestructive techniques for such quality measurements. Water-holding capacity is a critical attribute in meat quality. Up to 50% of raw poultry meat in the United States is marinated with mixtures of water, salts, and phosphates. The objective of this study was to determine if variations in breast meat color would affect the dielectric properties of marinated poultry meat over a broad frequency range from 500 MHz to 50 GHz. Poultry meat was obtained from a local commercial plant in Georgia (USA). Color and pH measurements were taken on the breast filets. Groups of breast filets were sorted into classes of pale and normal before adding marination pickup percentages of 0, 5, 10, and 15. Breast filets were vacuum-tumbled and weighed for pickup percentages. Dielectric properties of the filets were measured with a coaxial open-ended probe on samples equilibrated to 25°C. Samples from pale meat exhibited higher dielectric properties than samples from normal meat. No differences could be observed between samples from pale and normal meat after marination of the samples. Overall, dielectric properties increased as the marination pickup increased (α=0.05). Marination pickup strongly influenced the dielectric loss factor. Differences between samples marinated at different pickup levels were more pronounced at lower frequencies for the dielectric loss factor. As frequency increased, the differences between samples decreased. Differences in dielectric constant between samples were not as consistent as those seen with the dielectric loss factor.

  13. The review of various synthesis methods of barium titanate with the enhanced dielectric properties

    International Nuclear Information System (INIS)

    More, S. P.; Topare, R. J.

    2016-01-01

    The Barium Titanate is a very well known dielectric ceramic belongs to perovskite structure. It has very wide applications in the field of electronic, electro ceramic, electromechanical and electro-optical applications. Barium Titanate has very high dielectric constant as well as low dielectric loss. Substituted dielectrics are one of the most important technological compounds in modern electro ceramics. Its electrical properties can be tuned flexibly by a simple substitution technique. This has encouraged researchers to select a typical cation to be substituted at cationic sites. In the present paper, the review of various synthesis methods of Barium Titanate compound with the effect of different dopants, the grain size on the dielectric properties at various temperatures is discussed.

  14. Dielectric band structure of crystals: General properties, and calculations for silicon

    International Nuclear Information System (INIS)

    Car, R.; Baroni, S.; Tosatti, E.; Leelaprute, S.

    1981-02-01

    We shift the dielectric band structure method, orginially proposed by Baldereschi and Tosatti for the description of microscopic electronic screening in crystals. Some general properties are examined first, including the requirements of causality and stability. The specific test case of silicon is then considered. Dielectric bands are calculated, according to several different prescriptions for the construction of the dielectric matrix. It is shown that the results allow a very direct appraisal of the screening properties of the system, as well as of the quality of the dielectric model adopted. The electronic charge displacement induced by γsub(25') and X 3 phonon-like displacements of the atoms is also calculated and compared with the results of existent full self-consistent calculations. Conclusions are drawn on the relative accuracies of the dielectric band structures. (author)

  15. Microwave reflection measurements of the dielectric properties of concrete : final report.

    Science.gov (United States)

    1983-01-01

    The use of microwave reflection measurements to continuously and nondestructively monitor the hydration of concrete is described. The method relies upon the influence of the free-water content on the dielectric properties of the concrete. Use of the ...

  16. Dielectric properties of ligand-modified gold nanoparticle/SU-8 photopolymer based nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Toor, Anju, E-mail: atoor@berkeley.edu [Department of Mechanical Engineering, University of California, Berkeley, CA 94720 (United States); So, Hongyun, E-mail: hyso@berkeley.edu [Department of Mechanical Engineering, University of California, Berkeley, CA 94720 (United States); Pisano, Albert P. [Department of Mechanical Engineering, University of California, Berkeley, CA 94720 (United States); Department of Mechanical and Aerospace Engineering, University of California, San Diego, CA 92093 (United States)

    2017-08-31

    Highlights: • Ligand-modified gold NP/SU-8 nanocomposites were synthesized and demonstrated. • Particle agglomeration and dispersion were characterized with different NPs concentration. • Nanocomposites showed higher average dielectric permittivity compared to SU-8 only. • Relatively lower dielectric loss (average 0.09 at 1 kHz) was achieved with 10 % w/w NPs. - Abstract: This article reports the enhanced dielectric properties of a photodefinable polymer nanocomposite material containing sub–10 nm coated metal nanoparticles (NPs). The surface morphology of the synthesized dodecanethiol-functionalized gold NPs was characterized using the transmission electron microscopy (TEM). We investigated the particle agglomeration and dispersion during the various stages of the nanocomposite synthesis using TEM. Physical properties such as dielectric permittivity and dielectric loss were measured experimentally. The dependence of the dielectric permittivity and loss tangent on the particle concentration, and frequency was studied. Nanocomposite films showed an approximately three times enhancement in average dielectric constant over the polymer base value and an average dielectric loss of 0.09 at 1 kHz, at a filler loading of 10% w/w.

  17. A Broadband Quasi-optical System for Measuring the Dielectric Properties in the Terahertz Band

    Directory of Open Access Journals (Sweden)

    Liu Xiaoming

    2018-02-01

    Full Text Available To fulfill the requirements of the dielectric property measurement in the terahertz band, herein, a broadband quasi-optical system was designed and verified utilizing a planar scanning system. Additionally, the method of retrieving the dielectric parameters was discussed. Our experimental findings indicated that the measurement results were in good agreement with the theoretical results. Boron silicon, and deionized water were used for verifying the measurement, and the permittivity was obtained using a numerical method. We found that the dielectric properties were in good agreement with the typical values. This indicated that the proposed quasi-optical method effectively characterized the permittivity.

  18. Dielectric Properties of Landmine Fillers (Waxes and Sands)

    National Research Council Canada - National Science Library

    Curtis, John

    1997-01-01

    .... The original data were collected in the form of the real and imaginary parts of the complex dielectric constant versus frequency utilizing a Hewlett-Packard 8510C Vector Network Analyzer System...

  19. The effect of addition of Nd3+ on dielectric properties of Pb[Zr0 ...

    African Journals Online (AJOL)

    This work aims at, to study the influence of Nd3+ on the dielectric properties of a ceramics material of general formula: Pb[Zr0.45 Ti0.45 (Zn1/3, Sb2/3) 0.1]O3 and of structure perovskite. The selected samples were prepared by the method of synthesis with solid way. The study of the dielectric properties of the system ...

  20. Preparation of barium titanate nanoparticle sphere arrays and their dielectric properties.

    Science.gov (United States)

    Wada, Satoshi; Yazawa, Aki; Hoshina, Takuya; Kameshima, Yoshikazu; Kakemoto, Hirofumi; Tsurumi, Takaaki; Kuroiwa, Yoshihiro

    2008-09-01

    Barium titanate (BaTiO(3)) nanoparticles from 27 to 192 nm were prepared by the 2-step thermal decomposition method from barium titanyl oxalate nanoparticles. These particles were dispersed well into 1-propanol, and dense BaTiO(3); nanoparticle sphere arrays without stress-field were prepared by the meniscus method. Temperature dependence of dielectric properties was successfully measured using these dense nanoparticle sphere arrays, and size effect on dielectric properties was discussed.

  1. Dielectric properties of CdS nanoparticles synthesized by soft ...

    Indian Academy of Sciences (India)

    The power factor is then defined as sin δ, and the dissipation factor as tan δ. The product of the dielectric constant and the power factor is called the loss factor. It is proportional to the energy absorbed per cycle by the dielectric from the field. Cadmium sulphide is a direct band gap semiconductor with a band gap of 2.42 eV.

  2. Atomistic determination of flexoelectric properties of crystalline dielectrics

    OpenAIRE

    Maranganti, R.; Sharma, P.

    2009-01-01

    Upon application of a uniform strain, internal sub-lattice shifts within the unit cell of a non-centrosymmetric dielectric crystal result in the appearance of a net dipole moment: a phenomenon well known as piezoelectricity. A macroscopic strain gradient on the other hand can induce polarization in dielectrics of any crystal structure, even those which possess a centrosymmetric lattice. This phenomenon, called flexoelectricity, has both bulk and surface contributions: the strength of the bulk...

  3. Infrared Dielectric Properties of Low-stress Silicon Nitride

    Science.gov (United States)

    Cataldo, Giuseppe; Beall, James A.; Cho, Hsiao-Mei; McAndrew, Brendan; Niemack, Michael D.; Wollack, Edward J.

    2012-01-01

    Silicon nitride thin films play an important role in the realization of sensors, filters, and high-performance circuits. Estimates of the dielectric function in the far- and mid-IR regime are derived from the observed transmittance spectra for a commonly employed low-stress silicon nitride formulation. The experimental, modeling, and numerical methods used to extract the dielectric parameters with an accuracy of approximately 4% are presented.

  4. Dielectric properties of poly (1,4-phenylene ether-ether-sulfone)

    CERN Document Server

    Spasevska, H

    2002-01-01

    Dielectric properties of Poly (1,4-phenylene ether-ether-sulfone) are obtained from dielectric spectroscopy of the polymer pellet. The values of relative dielectric constant epsilon', dielectric losses epsilon sup , dielectric dissipation factor tan delta and complex impedance are obtained at temperature of 75 sup o C. The temperature dependence of these parameters is investigated for three frequencies (8x10 sup 4 Hz; 8x10 sup 5 Hz; 8x10 sup 6 Hz) of applied electric field. The specific conductivity sigma, which depends on temperature, is related to the ohmic resistance R, at temperature in the interval from 66 to 83 sup o C. Fitting the experimental data, the value of the activation energy U is obtained. (Original)

  5. Studies on dielectric properties of ferrocenylhydrazone coordinated polymers irradiated by γ-rays

    International Nuclear Information System (INIS)

    Lin Yun; Chen Jie; Lin Zhanru

    2007-01-01

    The three ferrocenylhydrazone coordinated metal polymers were synthesized (PZM). The effect of the 60 Co γ irradiation on microwave dielectric properties and their temperature-dielectric properties were studies. It has been found that the dielectric parameters (ε', tgδ) of coordinated polymers increase along with the absorbed doses and coordinated metals in order Cu, Co, Ni, However, the dependent curves of dielectric parameters on arise-down temperature are universal. On the other hand, the small changes in chemical structure before and after irradiation were confirmed by IR differential spectrometry and SEM. It is possible to make such coordinated polymers as a multifunctional polymeric material with optical, electric and magnetic properties, which may be potentially used in microwave communication. (authors)

  6. Dielectric Properties of Rhombohedral PbNb2O6

    Directory of Open Access Journals (Sweden)

    Kriti Ranjan Sahu

    2013-01-01

    Full Text Available Dielectric materials are needed in many electrical and electronic applications. So, basic characterizations need to be done for all dielectrics. PbNb2O6 (PN is ferroelectric and piezoelectric only in its orthorhombic phase, with potential high temperature applications. So, its rhombohedral phase, frequently formed as an undesirable impurity in the preparation of orthorhombic PN, has been ignored with respect to possible dielectric characterizations. Here, essentially single phase rhombohedral PN has been prepared, checking structure from XRD Rietveld Analysis, and the real and imaginary parts of permittivity measured in an Impedance Spectrometer (IS up to ~700∘C and over 20 Hz to 5.5 MHz range, for heating and some cooling runs. Variations, with temperature, of relaxation time constant (τ, AC and DC conductivity, bulk resistance, activation energy and capacitance have been explored from our IS data.

  7. Dielectric properties of PMMA-SiO2 hybrid films

    KAUST Repository

    Morales-Acosta, M. D.

    2010-03-01

    Organic-inorganic hybrid films were synthesized by a modified sol-gel process. PMMASiO2 films were prepared using methylmethacrylate (MMA), tetraethil-orthosilicate (TEOS) as silicon dioxide source, and 3-trimetoxi-silil-propil-methacrylate (TMSPM) as coupling agent. FTIR measurements were performed on the hybrid films to confirm the presence of PMMA-SiO2 bonding. In addition, metal-insulator-metal (MIM) devices were fabricated to study the dielectric constant of the films as function of frequency (1 KHz to 1 MHz). Electrical results show a weak trend of the dielectric constant of the hybrid films with MMA molar ratio. More importantly, the PMMA-SiO2 hybrid films showed a higher dielectric constant than SiO2 and PMMA layers, which is likely due to the presence of additional C-O-C bond. © (2010) Trans Tech Publications.

  8. Analysis of the dielectric properties of trunk wood in dominant conifer species from New England and Siberia

    Science.gov (United States)

    Ranson, K. J.; Rock, B. N.; Salas, W. A.; Smith, K.; Williams, D. L.

    1992-01-01

    Data were collected for dominant conifer species. Dielectric properties of trunk wood were measured using a C-band dielectric probe. For certain specimens, electrical resistance was also measured using a shigometer. The water status of the trees studies was determined either by use of a Scholander pressure chamber on branch samples collected simultaneously with dielectric measurements or by fresh-weight/dry-weight assessment of wood core samples extracted and analyzed with the dielectric probe and shigometer. Diurnal delectric properties and xylem water column tension are inversely correlated such that real and imaginary dielectric values drop as tension increases. The dielectric properties were positively correlated with wood core moisture content while electrical resistance was poorly correlated with wood core moisture content in one species studied. Results support the view that dielectric properties are strongly correlated with moisture status in trunk wood, and possibly ion concentrations associated with decay processes in damaged specimens.

  9. Changes of Dielectric Properties induced by Fast neutrons in Tissue Equivalent Plastic A-150

    International Nuclear Information System (INIS)

    Abdou, M.S.

    2000-01-01

    Tissue equivalent plastic A-150 (TEP A-150) samples are exposed to fast neutrons. Dielectric studies for TEP A-150 are carried out in the frequency range from 40 Hz to 4 MHz in the temperature range 295-343 K. The obtained data revealed that, both the dielectric properties and conductivity sigma ac (omega) of TEP A-150 are altered when irradiated by a relatively high fast neutron dose (15 Sv). The values of dielectric constant and conductivity are increased for the irradiated samples to about 24% than the blank samples

  10. 3D printed barium titanate/poly-(vinylidene fluoride) nano-hybrid with anisotropic dielectric properties

    DEFF Research Database (Denmark)

    Phatharapeetranun, N.; Ksapabutr, B.; Marani, D.

    2017-01-01

    Electrospun BaTiO3 nanofibers (BTNFs) are synthesized and blended in a poly(vinylidene fluoride) (PVDF) matrix to obtain a flexible nano-hybrid composite with high dielectric constant (flexible high-k). The blending is performed with different BTNF contents (0.6, 4.5, 20 vol%). The rheological...... material. The dielectric properties of the nano-hybrid are controlled by anisotropy with an enhancement in the nanofiber cross direction (⊥), where the dielectric constant k⊥ at 1 kHz is increased to ca. 200 from 13 of the PVDF matrix....

  11. Optically tuned dielectric property of barium titanate thin film by THz spectroscopy

    Science.gov (United States)

    Zhou, Siyan; Ji, Jie; Tian, Yue; Ling, Furi; Yu, Wenfeng

    2017-11-01

    The dielectric property of ferroelectric barium titanate (BaTiO3) thin film with optical field was investigated by terahertz time-domain spectroscopy at room temperature. Experimental results showed that dielectric constant of BTO film was increased with the optical pump powers, and tunability of the real part of dielectric constant could be reached to74%. The reason of realizing high modulation depth could be explained as photorefractive and photothermal effects. Furthermore, the variation of refractive index displayed a monotonically increase with the optical powers.

  12. Dielectric properties of gadolinium molybdate in low- and infralow frequency electric fields

    International Nuclear Information System (INIS)

    Galiyarova, N.M.; Gorin, S.V.; Dontsova, L.I.; Shil'nikov, A.V.; Shuvalov, L.A.; AN SSSR, Moscow

    1992-01-01

    Temperature dependences of complex dielectric permittivity of gadolinium molybdate (GMO) in low- (LF) and infralow-frequency (ILF) electric fields with 0.1 V·cm -1 amplitude within 0.25-10 4 Hz frequency range are studied. Substantial effect of the crystal prehistory on LF and ILF dielectric properties and domain structure state is revealed. An anomalous reduction of complex dielectric permittivity accompanied by the occurrence of the Debye LF-dispersion of permittivity is detected under the sample cooling from a nonpolar phase

  13. Dielectric and conductivity properties of composite polyaniline/polyurethane network

    Science.gov (United States)

    Liang, C.; Gest, J.; Leroy, G.; Carru, J.-C.

    2013-09-01

    In this work, we present the dielectric characterization of polyaniline/polyurethane composite. The samples consisting of 0.5%, 1%, and 5% of polyaniline were deposited on glass fiber, and the measurements were performed in a frequency range of 20 Hz to 20 GHz. The results showed a dielectric relaxation strongly dependent on the concentration of polyaniline. This phenomenon is explained by a theoretical model. In this model, we assume that the alternative conductivity of the polymer network systems is due to conducting clusters whose lengths followed a Gaussian distribution. Depending on their size and the frequency of the excitation signal, the clusters showed a resistive or capacitive effect.

  14. Dielectric properties of polyamide 12-chromium(III) oxide nanocomposites

    Science.gov (United States)

    Zuev, Vjacheslav V.; Shapoval, Ekaterina S.; Sakhatskii, Aleksandr S.

    2016-08-01

    Broadband dielectric spectroscopy was employed to study polymer nanocomposites based on PA12 filled with of nanosized chromium(III) oxide. The experimental dielectric data were analyzed within the formalisms of complex permittivity and electric modulus. Three relaxation processes and Maxwell-Wagner-Sillars (MWS) interfacial polarizations were observed. It was found that presence of nanosized amphoteric chromium(III) oxide leads to softening of polyamide matrix that manifested in decrease of the activation energy of the α- and β-relaxation processes and glass transition temperatures. The softening of polymer matrix is the reason of the decrease of mechanical strength of polymer nanocomposites as compared with neat PA12.

  15. Silicone rubbers for dielectric elastomers with improved dielectric and mechanical properties as a result of substituting silica with titanium dioxide

    Directory of Open Access Journals (Sweden)

    Liyun Yu

    2015-10-01

    Full Text Available One prominent method of modifying the properties of dielectric elastomers (DEs is by adding suitable metal oxide fillers. However, almost all commercially available silicone elastomers are already heavily filled with silica to reinforce the otherwise rather weak silicone network and the resulting metal oxide filled elastomer may contain too much filler. We therefore explore the replacement of silica with titanium dioxide to ensure a relatively low concentration of filler. Liquid silicone rubber (LSR has relatively low viscosity, which is favorable for loading inorganic fillers. In the present study, four commercial LSRs with varying loadings of silica and one benchmark room-temperature vulcanizable rubber (RTV were investigated. The resulting elastomers were evaluated with respect to their dielectric permittivity, tear and tensile strengths, electrical breakdown, thermal stability and dynamic viscosity. Filled silicone elastomers with high loadings of nano-sized titanium dioxide (TiO2 particles were also studied. The best overall performing formulation had 35 wt.% TiO2 nanoparticles in the POWERSIL® XLR LSR, where the excellent ensemble of relative dielectric permittivity of 4.9 at 0.1 Hz, breakdown strength of 160 V µm−1, tear strength of 5.3 MPa, elongation at break of 190%, a Young’s modulus of 0.85 MPa and a 10% strain response (simple tension in a 50 V μm−1 electric field was obtained.

  16. The Origin of the Improvement of Dielectric Property in the Modulated Structures: Electronic Structure Study

    International Nuclear Information System (INIS)

    Kim, J. D.; Choi, K. S.; Jung, D.; Yang, Y. S.

    2005-01-01

    The dielectric constants of ferroelectric materials are hundreds times bigger than those of normal dielectric compounds. It is necessary to possess stronger dielectric properties when a material is applied for the phase shifters, tunable filters, capacitors, non-volatile ferroelectric random access memory (FeRAM) devices, dynamic random access memory (DRAM) devices and steerable antennas. Many scientists, therefore, have tried to increase the dielectric property of ferroelectric materials by substituting the preexisting metals with various transition metals, and/or by changing the synthetic processes. Several compounds, for example, lead zirconate titanates [Pb(Ti 1-x Zr x )O 3 , PZT] and lead lanthanum zirconate titanates [(Pb 1-y La y )(Ti 1-x Zr x )O 3 , PLZT] have been successfully developed through the substitutional method

  17. Effect of cobalt doping on structural, optical and dielectric properties of TiO{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Stella, C., E-mail: stellachandran89@gmail.com; Prabhakar, Diva; Soundararajan, N.; Ramachandran, K. [School of Physics, Madurai Kamaraj University, Madurai – 625 021 (India)

    2016-05-23

    A diluted magnetic semiconductor (DMS) Co-doped TiO{sub 2} is studied here for dielectric properties. Undoped and Co-doped TiO{sub 2} samples were prepared by sol-gel method. The formation of anatase phase has been investigated by X-ray diffraction (XRD). UV-Vis absorption spectra show that the incorporation of Co into the TiO{sub 2} lattice leads to redshift in the optical response, as well as lowering the band gap energy. The defect oriented emissions were seen from photoluminescence (PL) study. The dielectric properties of pure and Co-doped TiO{sub 2} samples were studied in the frequency range of 10 Hz to 10 MHz at different temperatures. Doped sample exhibit low dielectric constant when compared with host system. Both dielectric constant and ac conductivity increases with temperature.

  18. Reflectance properties of one-dimensional metal-dielectric ternary photonic crystal

    Energy Technology Data Exchange (ETDEWEB)

    Pandey, G. N., E-mail: gnpandey2009@gmail.com [Department of Physics, Amity Institute of Applied Sciences, AmityUniversity, Noida (U.P.) (India); Kumar, Narendra [Department of Physics (CASH), Modi University of Science and Technology, Lakshmangarh, Sikar, Rajsthan (India); Thapa, Khem B. [Department of Physics, U I E T, ChhatrapatiShahu Ji Maharaj University, Kanpur- (UP) (India); Ojha, S. P. [Department of Physics IIT, Banaras Hindu University (India)

    2016-05-06

    Metallic photonic crystal has a very important application in absorption enhancement in solar cells. It has been found that an ultra-thin metallic layer becomes transparent due to internal scattering of light through the each interface of the dielectric and metal surfaces. The metal has absorption due to their surface plasmon and the plasmon has important parameters for changing optical properties of the metal. We consider ternary metallic-dielectric photonic crystal (MDPC) for having large probabilities to change the optical properties of the MDPC and the photonic crystals may be changed by changing dimensionality, symmetry, lattice parameters, Filling fraction and effective refractive index refractive index contrast. In this present communication, we try to show that the photonic band gap in ternary metal-dielectric photonic crystal can be significantly enlarged when air dielectric constant is considered. All the theoretical analyses are made based on the transfer matrix method together with the Drude model of metal.

  19. Enhanced dielectric properties of Fe-substituted TiO2 nanoparticles

    Science.gov (United States)

    Ali, T.; Ahmed, Ateeq; Naseem siddique, M.; Tripathi, P.

    2018-04-01

    We report the structural and dielectric properties Ti1-xFexO2 (0.00 conductivity have been determined as a function of frequency and composition of iron. At higher frequencies, the materials exhibited high AC Conductivity and low dielectric constant. The above theory could be explained by 'Maxwell Wagner Model' and may provide a new insight to fabricate nanomaterials having possible electrical application.

  20. Site-specific doping, tunable dielectric properties and intrinsic ...

    Indian Academy of Sciences (India)

    magnetization of SrMn (inset of (a)) and that of TiMn (inset of (b)) showing a linear dependence of magnetization on applied magnetic fields without any hysteresis. (d) The dielectric constant of SrMnTiMn in the presence and absence of a magnetic field of 1 Tesla (adapted from ref. [8]). 992. Pramana – J. Phys., Vol. 84, No.

  1. 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 ...

  2. Studies on conductivity and dielectric properties of polyaniline–zinc ...

    Indian Academy of Sciences (India)

    Unknown

    Abstract. In the present paper, we report electrical conductivity and dielectric studies on the composites of conducting polyaniline (PANI) with crystalline semiconducting ZnS powder, wherein PANI has been taken as inclusion and ZnS crystallites as the host matrix. From the studies, it has been observed that the value of.

  3. Dielectric properties of CdS nanoparticles synthesized by soft ...

    Indian Academy of Sciences (India)

    a distribution of relaxation times. The scaling behaviour of dielectric loss spectra sug- gests that the relaxation describes the same mechanism at various temperatures. The frequency-dependent electrical data are analysed in the framework of conductivity and modulus formalisms. The frequency-dependent conductivity ...

  4. Dielectric properties and structural dynamics of melt compounded ...

    Indian Academy of Sciences (India)

    OMMT concentration dependent dielectric and electric modulus relaxation times have revealed that the interactions compatibility between PEO molecules and dispersed OMMT nano-platelets in PEO matrix governs the PEO segmental dynamics. ... filler are extensively synthesized by solution intercalation. ∗. Author for ...

  5. Dielectric properties of KDP-type ferroelectric crystals in the ...

    Indian Academy of Sciences (India)

    Considering external electric field as well as third- and fourth-order phonon anharmonic interaction terms in the pseudospin-lattice coupled mode (PLCM) model Hamiltonian for KDP-type ferroelectrics, expressions for field-dependent shift, width, renormalized soft mode frequency, Curie temperature, dielectric constant and ...

  6. Structural and dielectric properties of phosphorous-doped PLZT ...

    Indian Academy of Sciences (India)

    The filtrate was then dried at 200◦C. The dried cake was crushed and thoroughly ground in an agate mortar and calcined at 600◦C for 2 h in an alumina ... For dielectric measurement sintered disc were ground and lapped to make the surface flat and parallel and subsequently electroded by applying silver paste on both the ...

  7. Synthesis and microwave dielectric properties of Ca substituted ...

    Indian Academy of Sciences (India)

    Keywords. Patch antenna; theoretical density; phase; ceramics. Abstract. Microwave dielectric ceramics in Sr1-CaLa4Ti4.93Zr0.07O17 (0 ≤ ≤ 0.5) composition series were processed via a solid-state sintering rout. X-ray diffraction revealed single phase ceramics. Ca substitutions for Sr tuned f towards zero with ...

  8. Investigation of differences in dielectric properties of marinated poultry meat

    Science.gov (United States)

    The dielectric behavior of foods when exposed to radio-frequency and microwave electric fields is highly influenced by moisture content and the degree of water binding with constituents of the food materials. If their interaction with the interior of the food materials can be correlated with quality...

  9. Structural and optical characterization of Cr2O3 nanostructures: Evaluation of its dielectric properties

    International Nuclear Information System (INIS)

    Abdullah, M. M.; Rajab, Fahd M.; Al-Abbas, Saleh M.

    2014-01-01

    The structural, optical and dielectric properties of as-grown Cr 2 O 3 nanostructures are demonstrated in this paper. Powder X-ray diffractometry analysis confirmed the rhombohedral structure of the material with lattice parameter, a = b = 4.953 Å; c = 13.578 Å, and average crystallize size (62.40 ± 21.3) nm. FE-SEM image illustrated the mixture of different shapes (disk, particle and rod) of as-grown nanostructures whereas; EDS spectrum confirmed the elemental purity of the material. FTIR spectroscopy, revealed the characteristic peaks of Cr–O bond stretching vibrations. Energy band gap (3.2 eV) of the nanostructures has been determined using the results of UV-VIS-NIR spectrophotometer. The dielectric properties of the material were checked in the wide frequency region (100Hz-30 MHz). In the low frequency region, the matrix of the dielectric behaves like source as well as sink of electrical energy within the relaxation time. Low value of dielectric loss exhibits that the materials posses good optical quality with lesser defects. The ac conductivity of the material in the high frequency region was found according to frequency power law. The physical-mechanism and the theoretical-interpretation of dielectric-properties of Cr 2 O 3 nanostructures attest the potential candidature of the material as an efficient dielectric medium

  10. Study of low weight percentage filler on dielectric properties of MCWNT-epoxy nanocomposites

    Directory of Open Access Journals (Sweden)

    Manindra Trihotri

    2016-09-01

    Full Text Available An attempt is made to study the effect of low weight percentage multiwall carbon nanotube (MWCNT powder on dielectric properties of MWCNT reinforced epoxy composites. For that MWCNT (of different low weight percentage reinforced epoxy composite was prepared by dispersing the MWCNT in resin. Samples were prepared by solution casting process and characterized for their dielectric properties such as dielectric constant (ε′, dielectric dissipation factor (tan δ and AC conductivity (σac. The main objective is the investigation of the dielectric properties of the prepared samples at the low weight percentage of the filler at different temperatures and frequencies. From the two mechanisms of electrical conduction, first the leakage current obtained by the formation of a percolation network in the matrix and the other by tunneling of electrons formed among conductors nearby (tunneling current; here we are getting conduction by the second mechanism. Generally, leakage current makes more contribution to conductivity than tunneling current. Dielectric dissipation factor at 250Hz frequency is greater than all other frequencies and starts increasing from 60∘C. The peak height of the transition temperature decreases with increasing frequency. This study shows that the addition of a low weight percentage of MWCNT can modify considerably the electrical behavior of epoxy nanocomposites without chemical functionalization of filler.

  11. Influence of Doping Concentration on Dielectric, Optical, and Morphological Properties of PMMA Thin Films

    Directory of Open Access Journals (Sweden)

    Lyly Nyl Ismail

    2012-01-01

    Full Text Available PMMA thin films were deposited by sol gel spin coating method on ITO substrates. Toluene was used as the solvent to dissolve the PMMA powder. The PMMA concentration was varied from 30 ~ 120 mg. The dielectric properties were measured at frequency of 0 ~ 100 kHz. The dielectric permittivity was in the range of 7.3 to 7.5 which decreased as the PMMA concentration increased. The dielectric loss is in the range of 0.01 ~ –0.01. All samples show dielectric characteristics which have dielectric loss is less than 0.05. The optical properties for thin films were measured at room temperature across 200 ~ 1000 nm wavelength region. All samples are highly transparent. The energy band gaps are in the range of 3.6 eV to 3.9 eV when the PMMA concentration increased. The morphologies of the samples show that all samples are uniform and the surface roughness increased as the concentration increased. From this study, it is known that, the dielectric, optical, and morphology properties were influenced by the amount of PMMA concentration in the solution.

  12. Millimeter-Wave Dielectric Properties of Single Crystal Ferroelectric and Dielectric Materials

    Energy Technology Data Exchange (ETDEWEB)

    McCloy, John S.; Korolev, Konstantin A.; Li, Zijing; Afsar, Mohammed N.; Sundaram, S. K.

    2011-01-03

    Transmittance measurements on various single crystal ferroelectric materials over a broad millimeter-wave frequency range have been performed. Frequency dependence of the complex dielectric permittivity has been determined in the millimeter wave region for the first time. The measurements have been employed using a free-space quasi-optical millimeter-wave spectrometer equipped with a set of high power backward wave oscillators (BWOs) as sources of coherent radiation, tunable in the range from 30 - 120 GHz. The uncertainties and possible sources of instrumentation and measurement errors related to the free-space millimeter-wave technique are discussed. This work has demonstrated that precise MMW permittivities can be obtained even on small thin crystals using the BWO quasi-optical approach.

  13. Structural Characteristics & Dielectric Properties of Tantalum Oxide Doped Barium Titanate Based Materials

    Directory of Open Access Journals (Sweden)

    Rubayyat Mahbub

    2012-11-01

    Full Text Available In this research, the causal relationship between the dielectric properties and the structural characteristics of 0.5 & 1.0 mol% Ta2O5 doped BaTiO3 based ceramic materials were investigated under different sintering conditions. Dielectric properties and microstructure of BaTio3 ceramics were significantly influenced by the addition of a small amount of Ta2O5. Dielectric properties were investigated by measuring the dielectric constant (k as a function of temperature and frequency. Percent theoretical density (%TD above 90% was achieved for 0.5 and 1.0 mol% Ta2O5 doped BaTiO3. It was observed that the grain size decreased markedly above a doping concentration of 0·5 mol% Ta2O5. Although fine grain size down to 200-300nm was attained, grain sizes in the range of 1-1.8µm showed the most alluring properties. The fine-grain quality and high density of the Ta2O5 doped BaTiO3 ceramic resulted in tenfold increase of dielectric constant. Stable value of dielectric constant as high as 13000-14000 was found in the temperature range of  55 to 80°C, for 1.0 mol% Ta2O5 doped samples with corresponding shift of Curie point to ~82°C. Experiments divulged that incorporation of a proper content of Ta2O5 in BaTiO3 could control the grain growth, shift the Curie temperature and hence significantly improve the dielectric property of the BaTiO3 ceramics.

  14. STRUCTURAL CHARACTERISTICS & DIELECTRIC PROPERTIES OF TANTALUM OXIDE DOPED BARIUM TITANATE BASED MATERIALS

    Directory of Open Access Journals (Sweden)

    Md. Fakhrul Islam

    2013-01-01

    Full Text Available In this research, the causal relationship between the dielectric properties and the structural characteristics of 0.5 & 1.0 mole % Ta2O5 doped BaTiO3 based ceramic materials were investigated under different sintering conditions. Dielectric properties and microstructure of BaTio3 ceramics were significantly influenced by the addition of a small amount of Ta2O5. Dielectric properties were investigated by measuring the dielectric constant (k as a function of temperature and frequency. Percent theoretical density (%TD above 90 % was achieved for 0.5 and 1.0 mole %Ta2O5 doped BaTiO3. It was observed that the grain size decreased markedly above a doping concentration of 0.5 mole % Ta2O5. Although fine grain size down to 200 - 300 nm was attained, grain sizes in the range of 1-1.8µm showed the most alluring properties. The fine-grain quality and high density of the Ta2O5 doped BaTiO3 ceramic resulted in tenfold increase of dielectric constant. Stable value of dielectric constant as high as 13000 - 14000 was found in the temperature range of 55 to 80 °C, for 1.0 mole % Ta2O5 doped samples with corresponding shift of Curie point to ~82 °C. Experiments divulged that incorporation of a proper content of Ta2O5 in BaTiO3 could control the grain growth, shift the Curie temperature and hence significantly improve the dielectric property of the BaTiO3 ceramics.

  15. 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

  16. Dielectric properties of wheat flour mixed with oat meal

    Science.gov (United States)

    Łuczycka, D.; Czubaszek, A.; Fujarczuk, M.; Pruski, K.

    2013-03-01

    Possibilities of using electric methods for determining admixtures of oat meal to wheat flour, type 650 are presented. In wheat flour, oat meal and mixtures containing 10, 20 and 30% of the oat meal, moisture, protein, starch and ash content, sedimentation value, yield and softening of wet gluten were determined. In samples containing 0, 5, 10, 15, 20, 25, 30 and 100% of oat meal, the dielectric loss factor and conductivity were determined using an impedance analyzer for electromagnetic field frequency ranging from 0.1-20 kHz. It was found that the dielectric loss factor varied for tested material. The best distinguishing between tested mixtures was obtained at the measuring electromagnetic field frequency of 20 kHz. The loss factor was significantly correlated with the yield of wet gluten and the sedimentation value, parameters indicating the amount and quality of gluten proteins in flour.

  17. Dielectric properties of piezoelectric 3–0 composites of lithium ferrite ...

    Indian Academy of Sciences (India)

    Piezoelectric 3–0 composite ceramics are prepared from a mixture of barium titanate and lithium ferrite phase constituents. Dielectric properties of composites are affected by a number of parameters that include electrical properties, size, shape and amount of constituent phases. The frequency dependent measurements ...

  18. Dielectric properties of piezoelectric 3–0 composites of lithium ferrite ...

    Indian Academy of Sciences (India)

    Unknown

    Abstract. Piezoelectric 3–0 composite ceramics are prepared from a mixture of barium titanate and lithium ferrite phase constituents. Dielectric properties of composites are affected by a number of parameters that include electrical properties, size, shape and amount of constituent phases. The frequency dependent measure-.

  19. Dielectric, thermal and mechanical properties of ADP doped PVA composites

    Science.gov (United States)

    Naik, Jagadish; Bhajantri, R. F.; Ravindrachary, V.; Rathod, Sunil G.; Sheela, T.; Naik, Ishwar

    2015-06-01

    Polymer composites of poly(vinyl alcohol) (PVA), doped with different concentrations of ammonium dihydrogen phosphate (ADP) has been prepared by solution casting. The formation of complexation between ADP and PVA was confirmed with the help of Fourier transforms infrared (FTIR) spectroscopy. Thermogravimetric analysis (TGA) shows thermal stability of the prepared composites. Impedance analyzer study revealed the increase in dielectric constant and loss with increase the ADP concentration and the strain rate of the prepared composites decreases with ADP concentration.

  20. Effects of Bi doping on dielectric and ferroelectric properties of ...

    Indian Academy of Sciences (India)

    Abstract. [Pb0·95(La1−yBiy)0·05][Zr0·53Ti0·47]O3 (PLBZT) ferroelectric thin films have been synthesized on indium tin oxide (ITO)-coated glass by sol–gel processing. PLBZT thin films were annealed at a relatively low tem- perature of 550 ◦C in oxygen ambient. Effects of Bi doping on structure, dielectric and ferroelectric ...

  1. Synthesis and microwave dielectric properties of Ca substituted ...

    Indian Academy of Sciences (India)

    Administrator

    commercial applications as dielectric resonators (DRs) for base stations require high relative electric permittivity ... high positive τf precluded its application at microwave frequencies. Nd substitutions for La in SrLa4Ti5O17 ... (Aldrich, 99 + %) dried at ~ 185 °C and La2O3 (Aldrich,. 99⋅95%), ZrO2 (Aldrich, 99.95%), and TiO2 ...

  2. Dielectric properties of nanocrystalline Co-Mg ferrites

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, Jyoti, E-mail: jyotijoshi.phy2008@gmail.com [Department of Physics, University of Rajasthan, Jaipur (India); Sharma, Neha [Department of Physics, VEC Lakhanpur, Sarguja University, Ambikapur (C.G.) (India); Parashar, Jyoti; Saxena, V.K.; Bhatnagar, D. [Department of Physics, University of Rajasthan, Jaipur (India); Sharma, K.B. [Department of Physics, S. S. Jain Subodh P. G. College, Jaipur (India)

    2015-11-15

    Nanocrystalline powder samples with chemical formula Co{sub x}Mg{sub 1−x}Fe{sub 2}O{sub 4} (x = 0, 0.2, 0.4, 0.6, 0.8 and 1.0) have been synthesized by sol–gel auto combustion method using citric acid as fuel agent. The rietveld refinement study of x-ray diffraction patterns confirmed the spinel single phase formation for all samples. Dielectric constant (ε′), dielectric loss tangent (tan δ) and AC conductivity of Co{sub x}Mg{sub 1−x}Fe{sub 2}O{sub 4} ferrite nanoparticles have been measured at room temperature in the frequency range from 1000 Hz to 120 MHz. The dielectric dispersion observed at lower frequency region is attributed to Maxwell–Wagner two layer model, which is in agreement with Koops phenomenological theory. The observed results have been explained by polarization which is attributed to the electron exchange between Fe{sup 2+} and Fe{sup 3+} ions. The temperature variation of ε′ and tanδ for some particular frequencies were studied. The rapid increase in ε′ and tan δ has been explained using thermally activated electron exchange between Fe{sup 2+} ↔ Fe{sup 3+} and Co{sup 2+} ↔ Co{sup 3+} ions at adjacent octahedral sites. The role of interfacial polarization has been focused to explain the high dispersion in ε′ and tanδ with temperature observed at low frequencies. - Graphical abstract: (a) TEM image of Co{sub 0.4}Mg{sub 0.6}Fe{sub 2}O{sub 4} shows the nano size of the synthesized ferrite particles and (b) Dielectric constant behavior with frequency of Co{sub x}Mg{sub 1−x}Fe{sub 2}O{sub 4} ferrite.

  3. Structural, spectral and dielectric properties of piezoelectric–piezomagnetic composites

    International Nuclear Information System (INIS)

    Hemeda, O.M.; Tawfik, A.; Amer, M.A.; Kamal, B.M.; El Refaay, D.E.

    2012-01-01

    Composite materials of spinel ferrite (SF) NiZnFe 2 O 4 (NZF) and barium titanate (BT) BaTiO 3 were prepared by double sintering ceramic technique. X-ray diffraction patterns for the composite system (1–x) NZF+x BT, showed the presence of mainly of 2 phases, hence confirming the successful preparation of the composite. Some structural and microstructural parameters like porosity, X-ray density, particle size and lattice constant were deduced from the analysis of X-ray data for both phases. Scan electron microscope (SEM) analysis shows nearly a homogeneous microstructure with good dispersion of BT grains as well as the presence of some pores. There was also an enlargement of BT grains with increasing its content. Infra red (IR) spectra of the composite system indicate that BT content affects the intermolecular character of the SF phase. A rise in the dielectric constant occurred at high temperature which was attributed to the effect of space change resulting from the increase of the change carriers in the paramagnetic region. The dielectric loss (tan δ) decreased by increasing BT content. - Highlights: ► Double phase NZF-BT composite has a high magnetoelectric coefficient compared with other materials. ► This makes it strongly candidates for electromagnetic wave sensors. ► Addition of BT phase enhance dielectric constant which make it very useful for capacitor industry. ► Ni ferrite shifts the transition temperature of BT from 120 °C near room temperature. ► Decrease of dielectric loss which supply with good material with law eddy current loss for cores of t ransformers at microwave frequency.

  4. High-frequency dielectric properties of nanocomposite and ceramic titanates

    Czech Academy of Sciences Publication Activity Database

    Rinkevich, A.B.; Kuznetsov, E. A.; Perov, D.V.; Bovtun, Viktor; Kempa, Martin; Nuzhnyy, Dmitry; Savinov, Maxim; Samoilovich, M.I.; Klescheva, S.M.; Ryabkov, Y.I.; Tsvetkova, E.V.

    2015-01-01

    Roč. 14, č. 3 (2015), s. 585-592 ISSN 1536-125X R&D Projects: GA ČR GAP204/12/0232 Institutional support: RVO:68378271 Keywords : electromagnetic waveguide * opal matrix * transmission and reflection coefficients * microwave conductivity * dielectric spectra Subject RIV: BM - Solid Matter Physics ; Magnetism OBOR OECD: Condensed matter physics (including formerly solid state physics, supercond.) Impact factor: 1.702, year: 2015

  5. Dielectric properties, optimum formulation and microwave baking conditions of chickpea cakes.

    Science.gov (United States)

    Alifakı, Yaşar Özlem; Şakıyan, Özge

    2017-03-01

    The aim of this study was to correlate dielectric properties with quality parameters, and to optimize cake formulation and baking conditions by response surface methodology. Weight loss, color, specific volume, hardness and porosity were evaluated. The samples with different DATEM (0.4, 0.8 and 1.2%) and chickpea flour concentrations (30, 40 and 50%) were baked in microwave oven at different power (300, 350, 400 W) and baking times (2.50, 3.0, 3.50 min). It was found that microwave power showed significant effect on color, while baking time showed effect on weight loss, porosity, hardness, specific volume and dielectric properties. Emulsifier level affected porosity, specific volume and dielectric constant. Chickpea flour level affected porosity, color, hardness and dielectric properties of cakes. The optimum microwave power, baking time, DATEM level and chickpea flour level were found as 400 W, 2.84 min, 1.2% and 30%, respectively. The comparison between conventionally baked and the microwave baked cakes at optimum points showed that color difference, weight loss, specific volume and porosity values of microwave baked cakes were less than those of conventionally baked cakes, on the other hand, hardness values were higher. Moreover, a negative correlation between dielectric constant and porosity, and weight loss values were detected for microwave baked samples. A negative correlation between dielectric loss factor and porosity was observed. These correlations indicated that quality characteristics of a microwave baked cake sample can be assessed from dielectric properties. These correlations provides understanding on the behavior of food material during microwave processing.

  6. 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.

  7. Mechanical and dielectric properties of carbon nanotubes/poly (vinyl alcohol) nanocomposites

    Science.gov (United States)

    Amrin, Sayed; Deshpande, V. D.

    2016-05-01

    In this work, two series of nanocomposites of poly(vinyl alcohol) (PVA) incorporated with multiwalled carbon nanotubes (MWNT) and carboxyl functionalized multiwalled carbon nanotubes (MWNT-COOH) were fabricated using solution-cast method and their tensile and dielectric properties were studied. Tensile tests were carried out on composite films of MWNT/PVA and MWNT-COOH/PVA for different loading levels. Results show that overall mechanical properties of the MWNT-COOH/PVA composite was greatly improved as compared to the MWNT/PVA film. The dielectric properties of nanocomposites were investigated in a frequency range from 0.1Hz to 10MHz at room temperature respectively. Compared to MWNT/PVA composites, higher dielectric constant and ac conductivity was achieved in MWNT-COOH/PVA nanocomposite, which can be well explained by the interfacial polarization effect.

  8. Dielectric properties and electrical conductivity of flat micronic graphite/polyurethane composites

    Science.gov (United States)

    Plyushch, Artyom; Macutkevic, Jan; Kuzhir, Polina P.; Banys, Juras; Fierro, Vanessa; Celzard, Alain

    2016-03-01

    Results of broadband dielectric spectroscopy of flat micronic graphite (FMG)/polyurethane (PU) resin composites are presented in a wide temperature range (25-450 K). The electrical percolation threshold was found to lie between 1 and 2 vol. % of FMG. Above the percolation threshold, the composites demonstrated a huge hysteresis of properties on heating and cooling from room temperature up to 450 K, along with extremely high values of dielectric permittivity and electrical conductivity. Annealing proved to be a very simple but powerful tool for significantly improving the electrical properties of FMG-based composites. In order to explain this effect, the distributions of relaxation times were calculated by the complex impedance formalism. Below room temperature, both dielectric permittivity and electrical conductivity exhibited a very low temperature dependence, mainly caused by the different thermal properties of FMG and pure PU matrix.

  9. Dual-cycle dielectrophoretic collection rates for probing the dielectric properties of nanoparticles.

    Science.gov (United States)

    Bakewell, David J; Holmes, David

    2013-04-01

    A new DEP spectroscopy method and supporting theoretical model is developed to systematically quantify the dielectric properties of nanoparticles using continuously pulsed DEP collection rates. Initial DEP collection rates, that are dependent on the nanoparticle dielectric properties, are an attractive alternative to the crossover frequency method for determining dielectric properties. The new method introduces dual-cycle amplitude modulated and frequency-switched DEP (dual-cycle DEP) where the first collection rate with a fixed frequency acts as a control, and the second collection rate frequency is switched to a chosen value, such that, it can effectively probe the dielectric properties of the nanoparticles. The application of the control means that measurement variation between DEP collection experiments is reduced so that the frequency-switched probe collection is more effective. A mathematical model of the dual-cycle method is developed that simulates the temporal dynamics of the dual-cycle DEP nanoparticle collection system. A new statistical method is also developed that enables systematic bivariate fitting of the multifrequency DEP collection rates to the Clausius-Mossotti function, and is instrumental for determining dielectric properties. A Monte-Carlo simulation validates that collection rates improve estimation of the dielectric properties, compared with the crossover method, by exploiting a larger number of independent samples. Experiments using 200 nm diameter latex nanospheres suspended in 0.2 mS/m KCl buffer yield a nanoparticle conductivity of 26 mS/m that lies within 8% of the expected value. The results show that the dual-frequency method has considerable promise particularly for automated DEP investigations and associated technologies. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Correlation between dielectric/organic interface properties and key electrical parameters in PPV-based OFETs.

    Science.gov (United States)

    Todescato, Francesco; Capelli, Raffaella; Dinelli, Franco; Murgia, Mauro; Camaioni, Nadia; Yang, Mujie; Bozio, Renato; Muccini, Michele

    2008-08-21

    We report on the influence of the dielectric/organic interface properties on the electrical characteristics of field-effect transistors based on polyphenylenevinylene derivatives. Through a systematic investigation of the most common dielectric surface treatments, a direct correlation of their effect on the field-effect electrical parameters, such as charge carrier mobility, On/Off current ratio, threshold voltage, and current hysteresis, has been established. It is found that the presence of OH groups at the dielectric surface, already known to act as carrier traps for electrons, decreases the hole mobility whereas it does not substantially affect the other electrical characteristics. The treatment of silicon dioxide surfaces with gas phase molecules such as octadecyltrichlorosilane and hexamethyldisilazane leads to an improvement in hole mobility as well as to a decrease in current hysteresis. The effects of a dielectric polymer layer spin coated onto silicon dioxide substrates before deposition of the semiconductor polymer can be related not only to the OH groups density but also to the interaction between the dielectric and the semiconductor molecules. Specifically, the elimination of the OH groups produces the same effect observed with hexamethyldisilazane. The hole mobility values obtained with hexamethyldisilazane and polymer dielectrics are the highest reported to date for PPV-based field-effect transistors.

  11. Dielectric properties and microstructural characterization of cubic pyrochlored bismuth magnesium niobates

    KAUST Repository

    Zhang, Yuan

    2013-08-06

    Cubic bismuth pyrochlores in the Bi2O3 Bi 2O3-MgO-Nb2O5 Nb2O 5 system have been investigated as promising dielectric materials due to their high dielectric constant and low dielectric loss. Here, we report on the dielectric properties and microstructures of cubic pyrochlored Bi 1.5 MgNb 1.5 O 7 Bi1.5MgNb1.5O7 (BMN) ceramic samples synthesized via solid-state reactions. The dielectric constant (measured at 1 MHz) was measured to be ∼ 120 ∼120 at room temperature, and the dielectric loss was as low as 0.001. X-ray diffraction patterns demonstrated that the BMN samples had a cubic pyrochlored structure, which was also confirmed by selected area electron diffraction (SAED) patterns. Raman spectrum revealed more than six vibrational models predicted for the ideal pyrochlore structure, indicating additional atomic displacements of the A and O′ O\\' sites from the ideal atomic positions in the BMN samples. Structural modulations of the pyrochlore structure along the [110] and [121] directions were observed in SAED patterns and high-resolution transmission electron microscopy (HR-TEM) images. In addition, HR-TEM images also revealed that the grain boundaries (GBs) in the BMN samples were much clean, and no segregation or impure phase was observed forming at GBs. The high dielectric constants in the BMN samples were ascribed to the long-range ordered pyrochlore structures since the electric dipoles formed at the superstructural direction could be enhanced. The low dielectric loss was attributed to the existence of noncontaminated GBs in the BMN ceramics. © 2013 Springer-Verlag Berlin Heidelberg.

  12. Dielectric Properties of Zinc Oxide Leach Residues Relevant to Microwave Drying

    Science.gov (United States)

    Zhang, Weifeng; Luo, Zhumei; Chen, Junruo; Zhang, Libo; Liu, Peng

    2017-12-01

    This paper presents the first study on dielectric properties of zinc oxide leach residues (ZOLR) relating to microwave drying. Dielectric properties of ZOLR were measured by cylindrical cavity perturbation method. The three-dimensional response surface plots show that both the dielectric constant and the loss factor of ZOLR tend to decline while the penetration depth of the microwave energy in ZOLR increases in the process of microwave drying. The largest penetration depth of microwave energy in ZOLR is 50 mm. The results obtained from the experiments are useful not only in developing large-scale industrial microwave drying system but also in numerical simulating of the distribution of the temperature field of ZOLR.

  13. 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)

  14. Effects of SiO2 and TiO2 fillers on thermal and dielectric properties ...

    Indian Academy of Sciences (India)

    Administrator

    . In consideration of the desired properties of ... dielectric properties for its construction such as white back (rear glass dielectric layer), barrier rib ..... bution of residual SiO2 and TiO2 fillers in the glass matrix. The sintering of glass frits at such a ...

  15. Modeling of dielectric properties of complex fluids with an equation of state

    OpenAIRE

    Maribo-Mogensen, Bjørn; Kontogeorgis, Georgios M.; Thomsen, Kaj

    2013-01-01

    The static permittivity is a key property for describing solutions containing polar and hydrogen bonding compounds. However, the precise relationship between the molecular and dielectric properties is not well-established. Here we show that the relative permittivity at zero frequency (static permittivity) can be modeled simultaneously with thermodynamic properties. The static permittivity is calculated from an extension of the framework developed by Onsager, Kirkwood, and Fröhlich to associa...

  16. Influence of domain on grain size effects of the dielectric properties of BaTiO3 nanoceramics and nanoparticles

    International Nuclear Information System (INIS)

    Fang Chao; Chen Liangyan; Zhou Dongxiang

    2013-01-01

    The dielectric property of BaTiO 3 nanoparticles and nanoceramics has been studied on the basis of Ginsburg-Landau-Devonshire thermodynamic theory. In this paper, considering nanodomains, Landau coefficients have been written as a function of grain size, and the dielectric constant of the material has been calculated at a variety of temperatures and grain size. The results indicate that with decreasing grain size, the dielectric peak decreases. The two lower dielectric peaks of the orthorhombic-rhombohedral phase and tetragonal-orthorhombic phase move to higher temperature, while cubic-tetragonal phase dielectric peak moves to lower temperature. The dielectric constant of BaTiO 3 ceramics decreases with decreasing grain size. The dielectric constant peak at room temperature is at the grain size which is larger than the critical grain size 17-30 nm. The calculated result is consistent with the experimental data.

  17. Mechanical, dielectric, and physicochemical properties of impregnating resin based on unsaturated polyesterimides

    Science.gov (United States)

    Fetouhi, Louiza; Petitgas, Benoit; Dantras, Eric; Martinez-Vega, Juan

    2017-10-01

    This work aims to characterize the dielectric and the mechanical properties of a resin based on an unsaturated polyesterimide diluted in methacrylate reactive diluents used in the impregnation of rotating machines. The broadband dielectric spectrometry and the dynamic mechanical analysis were used to quantify the changes in dielectric and mechanical properties of the network PEI resin, as a function of temperature and frequency. The network characterizations highlight the presence of two main relaxations, α and α', confirmed by the differential scanning calorimetry analysis, showing the complexity of the chemical composition of this resin. The dielectric spectroscopy shows a significant increase in the dielectric values due to an increase of the material conductivity, while the mechanical spectroscopy shows an important decrease of the polymer rigidity and viscosity expressed by an important decrease in the storage modulus. The PEI resin shows a high reactivity when it is submitted in successive heating ramps, which involves in a post-cross-linking reaction. Contribution to the topical issue "Electrical Engineering Symposium (SGE 2016)", edited by Adel Razek

  18. Anisotropic Dielectric Properties of Carbon Fiber Reinforced Polymer Composites during Microwave Curing

    Science.gov (United States)

    Zhang, Linglin; Li, Yingguang; Zhou, Jing

    2018-01-01

    Microwave cuing technology is a promising alternative to conventional autoclave curing technology in high efficient and energy saving processing of polymer composites. Dielectric properties of composites are key parameters related to the energy conversion efficiency during the microwave curing process. However, existing methods of dielectric measurement cannot be applied to the microwave curing process. This paper presented an offline test method to solve this problem. Firstly, a kinetics model of the polymer composites under microwave curing was established based on differential scanning calorimetry to describe the whole curing process. Then several specially designed samples of different feature cure degrees were prepared and used to reflect the dielectric properties of the composite during microwave curing. It was demonstrated to be a feasible plan for both test accuracy and efficiency through extensive experimental research. Based on this method, the anisotropic complex permittivity of a carbon fiber/epoxy composite during microwave curing was accurately determined. Statistical results indicated that both the dielectric constant and dielectric loss of the composite increased at the initial curing stage, peaked at the maximum reaction rate point and decreased finally during the microwave curing process. Corresponding mechanism has also been systematically investigated in this work.

  19. Magnetic and dielectric properties of hexagonal InMnO.sub.3./sub..

    Czech Academy of Sciences Publication Activity Database

    Belik, A.A.; Kamba, Stanislav; Savinov, Maxim; Nuzhnyy, Dmitry; Tachibana, M.; Takayama-Muromachi, E.; Goian, Veronica

    2009-01-01

    Roč. 79, č. 5 (2009), 054411/1-054411/7 ISSN 1098-0121 R&D Projects: GA ČR(CZ) GA202/09/0682 Institutional research plan: CEZ:AV0Z10100520 Keywords : magnetoelectric multiferroics * phase transitions * dielectric spectroscopy * magnetic properties Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.475, year: 2009

  20. Dynamic dielectric properties of a wood liquefaction system using polyethylene glycol and glycerol

    Science.gov (United States)

    Mengchao Zhou; Thomas L. Eberhardt; Bo Cai; Chung-Yun Hse; Hui Pan

    2017-01-01

    Microwave-assisted liquefaction has shown potential for rapid thermal processing of lignocellulosic biomass. The efficiency of microwave heating depends largely on the dielectric properties of the materials being heated. The objective of this study was to investigate the dynamic interactions between microwave energy and the reaction system during the liquefaction of a...

  1. O3 ceramic doping on optical, thermal and dielectric properties of ...

    Indian Academy of Sciences (India)

    Administrator

    Abstract. Ba(Ti(0⋅9)Sn0⋅1)O3 (BTS) ceramic was prepared by a conventional ceramic processing. BTS– polycarbonate (PC) composites were prepared at different BTS concentrations by weight in order to study their optical and dielectric properties. The absorption coefficient (α) was determined in the wavelength range.

  2. Microstructure and microwave dielectric properties of (Zn1–x Mgx) 2 ...

    Indian Academy of Sciences (India)

    By appropriate Mg substitution for Zn, the sintering range is widened and the sintering temperature of Zn2SiO4 ceramics can be lowered effectively. SEM shows that Mg-substitution for Zn can promote the grain growth of Zn2SiO4. Moreover, the microwave dielectric properties strongly depended on the substitution content of ...

  3. Synthesis, transport and dielectric properties of polyaniline/Co3O4 ...

    Indian Academy of Sciences (India)

    TECS

    and dielectric properties are studied by sandwiching the pellets of these composites between the silver ele- ctrodes. It is observed that the values of conductivities increase up to 30 wt% of ... electrodes for rechargeable batteries, sensors, etc. Prepa- ration of composites of conducting polymer (PANI) has been considered to ...

  4. Synthesis, transport and dielectric properties of polyaniline/Co 3 O 4 ...

    Indian Academy of Sciences (India)

    Conducting polyaniline/cobaltous oxide composites have been synthesized using in situ deposition technique by placing fine graded/cobaltous oxide in polymerization mixture of aniline. The a.c. conductivity and dielectric properties are studied by sandwiching the pellets of these composites between the silver electrodes.

  5. Effect of medium dielectric constant on the physical properties of single-walled carbon nanotubes

    NARCIS (Netherlands)

    Gao, J.; Gomulya, W.; Loi, M. A.

    2013-01-01

    The photophysical properties of semiconducting single walled carbon nanotubes (SWNTs) in different environments are analyzed by steady-state and time-resolved photoluminescence (PL) spectroscopy. The PL emission of SWNTs shows a red shift with the increase of the dielectric constant of the

  6. Optical properties of colloidal semiconductor quantum dots in dielectric media: A natural potential well approach

    Science.gov (United States)

    Jeong, Hwajun; Shin, Seung Koo

    2018-01-01

    Colloidal quantum dots exhibit size-dependent optical properties due to quantum and dielectric confinements at the semiconductor/solvent boundary. To consider both confinement effects, we take a natural potential well approach that assumes separate potential wells for electron and hole which are surrounded by dielectric media. The potential well depths for electron and hole are set by the band offsets at the semiconductor/solvent heterojunction. The kinetic energy is calculated using an effective mass approximation and the electron-hole interaction energy is obtained by taking image charges into account. For cadmium chalcogenides, resulting transition energies agree well with size-dependent optical bandgaps from experiments.

  7. Dielectric properties of silicon aluminium oxides and boron nitride during heating to 2300 deg K

    International Nuclear Information System (INIS)

    Litovchenko, A.V.; Brekhovskikh, S.M.; Dem'yanov, V.V.

    1983-01-01

    Temperature dependences of permittivity and tangent of the angle of dielectric losses of melted quartz, alumooxide and nitride-boron ceramics at the frequency of approximately 10 10 Hz in the range from 300 to 2300 K, are obtained. Lambda-shape anomaly E(T) and tg delta(T) of quartz glass at approximately 1950 k with characteristic decrease E and tg delta in the liquid phase is established. The applicability of the resonator method (using graphite resonator) of measuring dielectric properties when heating samples at the temperature up to 2300 K, is shown

  8. Structure and Properties of Epitaxial Dielectrics on gallium nitride

    Science.gov (United States)

    Wheeler, Virginia Danielle

    GaN is recognized as a possible material for metal oxide semiconductor field effect transistors (MOSFETs) used in high temperature, high power and high speed electronic applications. However, high gate leakage and low device breakdown voltages limit their use in these applications. The use of high-kappa dielectrics, which have both a high permittivity (ε) and high band gap energy (Eg), can reduce the leakage current density that adversely affects MOS devices. La2O3 and Sc2O 3 are rare earth oxides with a large Eg (6.18 eV and 6.3 eV respectively) and a relatively high ε (27 and 14.1 respectively), which make them good candidates for enhancing MOSFET performance. Epitaxial growth of oxides is a possible approach to reducing leakage current and Fermi level pinning related to a high density of interface states for dielectrics on compound semiconductors. In this work, La2O3 and Sc2O 3 were characterized structurally and electronically as potential epitaxial gate dielectrics for use in GaN based MOSFETs. GaN surface treatments were examined as a means for additional interface passivation and influencing subsequent oxide formation. Potassium persulfate (K2(SO4)2) and potassium hydroxide (KOH) were explored as a way to achieve improved passivation and desired surface termination for GaN films deposited on sapphire substrates by metal organic chemical vapor deposition (MOCVD). X-ray photoelectron spectroscopy (XPS) showed that KOH left a nitrogen-rich interface, while K2(SO 4)2 left a gallium-rich interface, which provides a way to control surface oxide formation. K2(SO4)2 exhibited a shift in the O1s peak indicating the formation of a gallium-rich GaOx at the surface with decreased carbon contaminants. GaO x acts as a passivating layer prior to dielectric deposition, which resulted in an order of magnitude reduction in leakage current, a reduced hysteresis window, and an overall improvement in device performance. Furthermore, K2(SO4)2 resulted in an additional 0.4 eV of

  9. Improved Dielectric Properties of Polyvinylidene Fluoride Nanocomposite Embedded with Poly(vinylpyrrolidone)-Coated Gold Nanoparticles.

    Science.gov (United States)

    Toor, Anju; So, Hongyun; Pisano, Albert P

    2017-02-22

    A novel nanocomposite dielectric was developed by embedding polyvinylpyrrolidone (PVP)-encapsulated gold (Au) nanoparticles in the polyvinylidene fluoride (PVDF) polymer matrix. The surface functionalization of Au nanoparticles with PVP facilitates favorable interaction between the particle and polymer phase, enhancing nanoparticle dispersion. To study the effect of entropic interactions on particle dispersion, nanocomposites with two different particle sizes (5 and 20 nm in diameter) were synthesized and characterized. A uniform particle distribution was observed for nanocomposite films consisting of 5 nm Au particles, in contrast to the film with 20 nm particles. The frequency-dependent dielectric permittivity and the loss tangent were studied for the nanocomposite films. These results showed the effectiveness of PVP ligand in controlling the agglomeration of Au particles in the PVDF matrix. Moreover, the study showed the effect of particle concentration on their spatial distribution in the polymer matrix and the dielectric properties of nanocomposite films.

  10. Effect of Co doping on the structural and dielectric properties of ZnO nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Ram, Mast, E-mail: Mastram1999@yahoo.com; Bala, Kanchan; Sharma, Hakikat; Negi, N. S. [Himachal Pradesh University Summehill Shimla (India)

    2016-05-23

    This paper reports on the synthesis of Co doped Zn{sub 1-x}Co{sub x}O (x= 0.0, 0.01, 0.02, 0.03 and 0.05) nanoparticles by solution combustion method using urea as a fuel. The Structural and dielectric properties of the samples were studied. Crystallite sizes were obtained from X-ray diffraction (XRD) patterns whose values decreased with increase in Co concentration. The XRD study reveals that Co{sup 2+} ions substitute the Zn{sup 2+} ion without changing the wurtzite structure of pristine ZnO up to Co concentrations of 5%. The dielectric constants, dielectric loss (tanδ) and ac conductivity (σ{sub ac}) were studied as the function of frequency and composition, which have been explained by Maxwell-Wagner type interfacial polarization and discussed Koops phenomenological theory.

  11. Conductivity and Dielectric Relaxation Properties of Annealed Cr-Substituted Ni-Ferrite Nanoparticles

    Science.gov (United States)

    El-Ghazzawy, E. H.

    2017-10-01

    Nanocrystalline NiCr x Fe2- x O4 spinel samples with x = 0.1 and 0.2 have been synthesized by coprecipitation method and annealed at 620°C and 1175°C for 4 h. Their electrical properties were investigated as functions of frequency in the range of 100 Hz to 100 kHz and temperature in the range of 308 K to 358 K. The dielectric constant ( ɛ^' } ) and dielectric loss factor ( {tan} δ ) appeared to decrease with increasing frequency, while the alternating-current (AC) conductivity ( σ^' } ) increased. These dielectric parameters increased with increasing temperature. On the other hand, impedance spectroscopy gave Cole-Cole plots with only one semicircular arc for all the samples, indicating that the grain-boundary contribution was dominant in the conduction mechanism.

  12. The low-frequency dielectric properties of octopus arm muscle measured in vivo

    International Nuclear Information System (INIS)

    Hart, F.X.; Toll, R.B.; Berner, N.J.; Bennett, N.H.

    1996-01-01

    The conductance and capacitance of octopus arm are measured in vivo over the frequency range 5 Hz to 1 MHz. Measurement of these parameters for a number of electrode separations permits the determination of the variations in tissue conductivity and dielectric constant with frequency. In the range 1-100 kHz the conductivity is independent of the frequency f and the dielectric constant varies as f -1 . These results, in conjunction with those reported previously for frog skeletal muscle, are consistent with the fractal model for the dielectric properties of animal tissue proposed by Dissado. Transformation of the results to complex impedance spectra indicates the presence of a dispersion above 100 kHz. (author)

  13. Improved Dielectric Properties of Polyvinylidene Fluoride Nanocomposite Embedded with Poly(vinylpyrrolidone)-Coated Gold Nanoparticles

    KAUST Repository

    Toor, Anju

    2017-01-25

    A novel nanocomposite dielectric was developed by embedding polyvinylpyrrolidone (PVP)-encapsulated gold (Au) nanoparticles in the polyvinylidene fluoride (PVDF) polymer matrix. The surface functionalization of Au nanoparticles with PVP facilitates favorable interaction between the particle and polymer phase, enhancing nanoparticle dispersion. To study the effect of entropic interactions on particle dispersion, nanocomposites with two different particle sizes (5 and 20 nm in diameter) were synthesized and characterized. A uniform particle distribution was observed for nanocomposite films consisting of 5 nm Au particles, in contrast to the film with 20 nm particles. The frequency-dependent dielectric permittivity and the loss tangent were studied for the nanocomposite films. These results showed the effectiveness of PVP ligand in controlling the agglomeration of Au particles in the PVDF matrix. Moreover, the study showed the effect of particle concentration on their spatial distribution in the polymer matrix and the dielectric properties of nanocomposite films.

  14. Dielectric properties of binary mixtures of methyl iso butyl ketone and amino silicone oil

    Science.gov (United States)

    Shah, K. N.; Rana, V. A.; Trivedi, C. M.; Vankar, H. P.

    2017-05-01

    Dielectric permittivity ɛ*(ω) = ɛ' - jɛ″ of the binary mixtures of the methyl iso butyl ketone and amino silicone oil in the frequency range 100 Hz to 2 MHz were measured using precision LCR meter at 305.15 K. Relative complex permittivity spectra in the frequency range 100 Hz to 2 MHz, of the mixture solutions of varying concentrations is reported. Determined values of the permittivity at optical frequency of all the samples are also reported. The dielectric parameters are used to gain information about the effect of concentration variation of components of the mixtures on the dielectric properties. It also provides the information about electrode polarization phenomena taking place under the low frequency A.C. electric field.

  15. Dielectric properties of Ga{sub 2}O{sub 3}-doped barium iron niobate ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Sanjoom, Kachaporn [Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai, 50200 (Thailand); Thailand Center of Excellence in Physics, Commission on Higher Education, 328 Sri Ayutthaya Road, Bangkok, 10400 (Thailand); Pengpat, Kamonpan; Eitssayeam, Sukum; Tunkasiri, Tawee [Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai, 50200 (Thailand); Materials Science Research Center, Faculty of Science, Chiang Mai University, Chiang Mai, 50200 (Thailand); Rujijanagul, Gobwute [Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai, 50200 (Thailand); Materials Science Research Center, Faculty of Science, Chiang Mai University, Chiang Mai, 50200 (Thailand); Thailand Center of Excellence in Physics, Commission on Higher Education, 328 Sri Ayutthaya Road, Bangkok, 10400 (Thailand)

    2014-08-15

    Ga-doped BaFe{sub 0.5}Nb{sub 0.5}O{sub 3} (Ba(Fe{sub 1-x}Ga{sub x}){sub 0.5}Nb{sub 0.5}O{sub 3}) ceramics were fabricated and their properties were investigated. All ceramics showed perovskite structure with cubic symmetry and the solubility of Ga in BFN ceramics had a limit at x = 0.2. Examination of the dielectric spectra indicated that all ceramic samples presented high dielectric constants that were frequency dependent. The x = 0.2 ceramic showed a very high dielectric constant (ε{sub r} > 240 000 at 1 kHz) while the x = 0.4 sample exhibited high thermal stability of dielectric constant with low loss tangent from room temperature (RT) to 100 C with ε{sub r} > 28 000 (at 1 kHz) when compared to other samples. By using a complex impedance analysis technique, bulk grain, grain boundary, and electrode response were found to affect the dielectric behavior that could be related to the Maxwell-Wagner polarization mechanism. (copyright 2014 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  16. Dielectric properties of ZnO nanoparticles determined by time-domain THz spectroscopy

    International Nuclear Information System (INIS)

    Furka, D.; Furka, S.; Naftaly, M.; Janek, M.

    2017-01-01

    Increased demand for hybrid materials with catalytic and photocatalytic properties requires the preparation of new materials with low cost and appropriate parameters. As reasonable alternative with optical and thermoelectric behaviour were investigated Zinc oxide (ZnO) nanoparticles prepared by hydrothermal synthesis. ZnO is a semiconductor with a wide band gap ∼3.37 eV. The dielectric response of ZnO can be affected by morphology. Also different loading of ZnO in nanocomposite materials can affect resulting optical and dielectric properties. For this purpose, THz time domain spectroscopy was utilised to investigate the dielectric response of composite prepared from ZnO nanoparticles and polytetrafluoroethylene (teflon). The aim of our work was to characterize the frequency dependence of ZnO nanoparticles with different morphology and concentration in composite mixture on their complex dielectric properties. Such well-defined ZnO nanoparticles can find utilization in gas sensors with high resolution, and photocatalytic or optoelectric applications. (authors)

  17. Dielectric and Microwave Properties of Siloxane Rubber/Carbon Black Nanocomposites and Their Correlation

    Directory of Open Access Journals (Sweden)

    Omar A. Al-Hartomy

    2011-01-01

    Full Text Available In this paper, the dielectric and microwave properties of carbon black/siloxane rubber-based nanocomposites have been investigated in the frequency range from 1 GHz till 12 GHz according to the content of carbon black and the frequency. It has been established that the increasing frequency and filler content lead to an increase in the relative permittivity and tangent of dielectric loss angle. At higher filler content, the effects become more pronounced, especially those upon dielectric loss. It has been also established that there are two well-distinguished areas in all dependences of microwave properties on frequency and filler content increasing. The first is between 1 and 8 GHz wherein the reflection and attenuation of microwaves do not change considerably with frequency and filler content alternation while shielding effectiveness worsens. The second area is between 8 and 12 GHz wherein the reflection and attenuation of microwaves increase drastically with the increasing frequency and filler content. Shielding effectiveness improves, too. It has been established that in all cases the degree of correlation between dielectric and microwave properties evaluated on the basis of the coefficients of correlation calculation is perfect.

  18. 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.

  19. Dielectric response and transport properties of alkylammonium formate ionic liquids

    Science.gov (United States)

    Nazet, Andreas; Buchner, Richard

    2018-05-01

    Dielectric relaxation spectra of three members of the alkylammonium formate family of protic ionic liquids (PILs), namely, ethylammonium formate (EAF), n-butylammonium formate (BuAF), and n-pentylammonium formate (PeAF), as well as the pseudo-PIL triethylamine + formic acid (molar ratio 1:2; TEAF) have been studied over a wide frequency (50 MHz to 89 GHz) and temperature range (5-65 °C), complemented by measurements of their density, viscosity, and conductivity. It turned out that the dominating relaxation of EAF, BuAF, and PeAF arises from both cation and anion reorientations which are synchronized in their dynamics due to hydrogen bonding. Amplitudes and relaxation times of this mode reflect the—compared to nitrate—different nature of H bonding between the formate anion and ethylammonium cation, as well as increasing segregation of the PIL structure into polar and non-polar domains. The TEAF data suggest that its dominating relaxation is due to the rotation of the complex triethylamineṡ(formic acid)2 in which no significant proton transfer to an ion pair occurred. Weak dissociation of this complex into ions was postulated to account for the high conductivity of TEAF.

  20. 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

  1. Dielectric properties and relaxation of Bi0⋅ 5Na0⋅ 5TiO3 ...

    Indian Academy of Sciences (India)

    Home; Journals; Bulletin of Materials Science; Volume 30; Issue 6. Dielectric ... Abstract. A new member of lead-free piezoelectric ceramics of the BNT-based group, (1 – )Bi0.5Na0.5TiO 3 – x BaNb2O6, was prepared by conventional solid state reaction and its dielectric properties and relaxation was investigated.

  2. Site-specific doping, tunable dielectric properties and intrinsic ...

    Indian Academy of Sciences (India)

    2015-05-29

    May 29, 2015 ... Mn doping in SrTiO3 leads to the emergence of qualitatively distinct and novel physical properties. We show that Mn ions can be controllably doped at either of the perovskite (Sr) or (Ti) site as well as at both sites simultaneously and the resultant physical properties depend intimately on the particular ...

  3. 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.

  4. Structural, electrical and dielectric properties of nanocrystalline Mg-Zn ferrites

    International Nuclear Information System (INIS)

    Anis-ur-Rehman, M.; Malik, M.A.; Nasir, S.; Mubeen, M.; Khan, K.; Maqsood, A.

    2011-01-01

    The nanocrystalline Mg-Zn ferrites having general formula Mg/sub 1-x/Zn/sub x/Fe/sub 2/O/sub 4/ (x=0, 0.1, 0.2, 0.3, 0.4, 0. 5) were prepared by WOWS sol-gel route. All prepared samples were sintered at 700 deg. C for 2 h. X-ray powder diffraction (XRD) technique was used to investigate structural properties of the samples. The crystal structure was found to be spinel. The crystallite size, lattice parameters and porosity of samples were calculated by XRD data analysis as function of zinc concentration. The crystallite size for each sample was calculated using the Scherrer formula considering the most intense (3 1 1) peak and the range obtained was 34-68 nm. The dielectric constant, dielectric loss tangent and AC electrical conductivity of nanocrystalline Mg-Zn ferrites are investigated as a function of frequency. The dielectric constant, dielectric loss tangent increased with increase of Zn concentration. All the electrical properties are explained in accordance with Maxwell Wagner model and K/sub oops/ phenomenological theory. (author)

  5. Dielectric Properties and Characterisation of Titanium Dioxide Obtained by Different Chemistry Methods

    Directory of Open Access Journals (Sweden)

    Aleksandra Wypych

    2014-01-01

    Full Text Available We made comparison of titanium dioxide powders obtained from three syntheses including sol-gel and precipitation methods as well as using layered (tetramethylammonium titanate as a source of TiO2. The obtained precursors were subjected to step annealing at elevated temperatures to transform into rutile form. The transformation was determined by Raman measurements in each case. The resulting products were characterised using Raman spectroscopy and dynamic light scattering. The main goal of the studies performed was to compare the temperature of the transformation in three titania precursors obtained by different methods of soft chemistry routes and to evaluate dielectric properties of rutile products by means of broadband dielectric spectroscopy. Different factors affecting the electrical properties of calcinated products were discussed. It was found that sol-gel synthesis provided rutile form after annealing at 850°C with the smallest particles size about 20 nm, the highest value of dielectric permittivity equal to 63.7, and loss tangent equal to 0.051 at MHz frequencies. The other powders transformed to rutile at higher temperature, that is, 900°C, exhibit lower value of dielectric permittivity and had a higher value of particles size. The correlation between the anatase-rutile transformation temperature and the size of annealed particles was proposed.

  6. Electrophysical properties of microalloyed alumo-silicate ceramics as active dielectric

    Directory of Open Access Journals (Sweden)

    Purenović Jelena

    2013-01-01

    Full Text Available In this paper, electrophysical properties of porous alumo-silicate ceramics, modified by alloying with magnesium and microalloying with aluminum, were investigated. Complex multiphase system, as active microalloyed ceramics, has specific behavior under influence of external electrical field, which involves changes of dielectric losses and impedance, depending on frequency and temperature. Dielectric properties were measured in the frequency range 20 Hz - 1 MHz. Values for permittivity (εr ranged between 140 - 430. Order of magnitude for electrical resistivity was about 106 Ωm, for impedance 104 - 108 Ω, and loss tangent had values about and greater than 0.05. Current flow through active dielectric takes place through dielectric barrier and throughout conduction bands of thin aluminum and magnesium metal films. Permittivity has nonlinear distribution and complex functional dependences because of significant nonhomogeneity of active microalloyed ceramics. Lower values of electrical resistivity are the result of complex electron and ion transfer of charge through solid phase and pores, with decreased potential barriers height, due to the influence of additives, ingredients and defects. [Projekat Ministarstva nauke Republike Srbije, br. III 45012 i br. ON 172057

  7. Structural, magnetic and dielectric properties of magnesium doped nickel ferrite nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Moradmard, H. [Nanostructure Lab, Department of Physics, University of Guilan, Rasht (Iran, Islamic Republic of); Farjami Shayesteh, S., E-mail: saber@guilan.ac.ir [Nanostructure Lab, Department of Physics, University of Guilan, Rasht (Iran, Islamic Republic of); Tohidi, P.; Abbas, Z. [Department of Physics, University Putra Malaysia, 43400 UPM Serdang, Selangor (Malaysia); Khaleghi, M. [Nanostructure Lab, Department of Physics, University of Guilan, Rasht (Iran, Islamic Republic of)

    2015-11-25

    Magnesia doped nickel ferrite nanopowders (Ni{sub 1−x}Mg{sub x}Fe{sub 2}O{sub 4}, x = 0, 0.1, 0.3, 0.5, 0.7) have been synthesized by co-precipitation method and all samples were annealed at 900 °C. The structural, morphological and magnetic properties of the products were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FESEM), energy-dispersive X-ray (EDX) spectroscopy and vibrating sample magnetometer (VSM). Also microwave dielectric properties were measured at frequencies 1 GHz–12 GHz. XRD analysis indicates that all samples have spinel structure and there is not any extra phase in all samples. The increase in magnesia concentration caused to variation in the average crystallite size and lattice constant. Doping magnesia in nickel ferrite gave rise to a decrease in the saturation magnetization whereas doping led to increase in coercivity field. The parameters like dielectric constant, dielectric loss and ac conductivity of the nanoparticles samples are studied in the frequency range from 1 to 12 GHz. All these parameters show, size dependent variations. Complex dielectric permittivity of samples was decreased by increasing in frequency. - Highlights: • Co-precipitation synthesis of Mg doped Ni ferrite nanoparticles is reported. • Its structural, morphological, magnetic and dielectric behavior is studied. • Structural properties were characterized by XRD, SEM, and FTIR. • Doping magnesia in nickel ferrite gave rise to an increase in the H{sub C} field. • The particle size observed to change with increasing Mg concentration.

  8. 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.

  9. Effect of combined external uniaxial stress and dc bias on the dielectric property of BaTiO3-based dielectrics in multilayer ceramic capacitor: thermodynamics and experiments

    International Nuclear Information System (INIS)

    Yang Gang; Yue Zhenxing; Sun Tieyu; Gou Huanlin; Li Longtu

    2008-01-01

    The dielectric properties of (Nb, Y)-doped BaTiO 3 in a multilayer ceramic capacitor (MLCC) under combined external uniaxial compressive stress and dc bias field were investigated at room temperature by using a modified Ginsburg-Landau-Devonshire thermodynamic theory and the dielectric measurement. It is found that although dc bias decreases the dielectric properties dominantly, the influence of the external uniaixial compressive stress should not be neglected. When applied along a direction perpendicular to the internal electrode layer in the MLCC, the external uniaixal compressive stress will strengthen the negative effect of dc bias. In contrast, the external uniaxial compressive stress along a direction parallel to the internal electrode layer in the MLCC will increase the dielectric permittivity under dc bias field, i.e. improve the ε-V response of the MLCC. Furthermore, although there is a difference between the calculated permittivity and the measured permittivity, the effects of the combined external uniaxial compressive stress and dc bias field on the dielectric permittivity described through two approaches are in good agreement

  10. Nakula's Extraordinary Talent -44 ...

    Indian Academy of Sciences (India)

    Nakula's Extraordinary Talent. Mathematics From the Mahabharatha! After 12 years at TIFR,. Mumbai, C Musilijoined the University of. Hyderabad in 1979. He loves teaching as wen as telling appropriate. stories in support of new concepts, techniques etc., whenever possible. C Musili. An attempt is made here to provide a ...

  11. 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.

  12. Facile synthesis, dielectric properties and electrocatalytic activities of PMMA-NiFe2O4 nanocomposite

    International Nuclear Information System (INIS)

    Maji, Pranabi; Choudhary, Ram Bilash

    2017-01-01

    The paper deals with the dielectric and catalytic properties of poly (methyl methacrylate)-nikel ferrite (PMMA-NiFe 2 O 4 ) nanocomposite. The nanocomposite was prepared by using a general and facile synthesis strategy. Fourier transform infrared (FTIR) and X-ray diffraction (XRD) spectra confirmed the formation of PMMA-NiFe 2 O 4 nanocomposite. Field effect scanning electron microscopic (FESEM) and transmission electron microscopic (TEM) images revealed that NiFe 2 O 4 nanoparticles were uniformly distributed and were tightly adhered with PMMA matrix owing to surface modification with 3-methacryloyloxy propyl trimethoxy silane (KH-570). Thermal stability was enhanced by incorporation of NiFe 2 O 4 nanofillers. The nanocomposite showed high dielectric constant and low dielectric loss. The achieved dielectric and thermal property inferred the potential application of this material in energy storage and embedded electronics devices. Further, the as prepared nanocomposite also offered a remarkable electrochemical performance towards hydrogen peroxide (H 2 O 2 ) sensing. - Highlights: • PMMA-NiFe 2 O 4 nanocomposite was synthesized via free radical polymerization. • The nanocomposite exhibited high value of dielectric constant (51) and tanδ (0.3). • Thermal stability of the PMMA matrix was improved by the incorporation of NiFe 2 O 4. • The H 2 O 2 detection limit was estimated 44 μM when signal to noise (S/N) ration was 3. • The electrochemical sensitivity of H 2 O 2 was calculated 0.6727 μA mM -1 .

  13. Temperature-dependent dielectric properties in ITO/AF/Al device

    International Nuclear Information System (INIS)

    Choi, Hyun-Min; Kim, Won-Jong; Lee, Jong-Yong; Hong, Jin-Woong; Kim, Tae-Wan

    2010-01-01

    Temperature-dependent dielectric properties were studied in a device with a structure of ITO/amorphous fluoropolymer (AF)/Al. The AF was thermally deposited at a deposition rate of 0.1 A/s to a thickness of 20 nm under a pressure of 5 x 10 -6 Torr. From the dielectric properties of the device, an equivalent circuit for and the equivalent complex impedance Z eq of the device were obtained. The interfacial resistance was found to be approximately 38 Ω. As the temperature was increased, the radius of the Cole-Cole plot and β also increased for a constant applied voltage. However, as the applied voltage was increased, those values decreased at a constant temperature. These behaviors are thought to be due to an orientational polarization effect of the molecules inside the AF layer.

  14. Effects of γ-radiation on dielectric properties of LDPE-Al2O3 nanocomposites

    Science.gov (United States)

    Ciuprina, Florin; Zaharescu, Traian; Pleşa, Ilona

    2013-03-01

    Until now several methods for processing and characterization have been tested, and some theories and models have been proposed for these materials having a huge nanofiller-polymer interface area which seems to be the main responsible for their unique properties. The accelerated testing by irradiation of LDPE has been extensively studied in order to assess optimized formulation. The present paper characterizes LDPE modified with Al2O3 nanoparticles. The dispersed nanofiller was added in various concentrations (2, 5 and 10 wt%). The accelerated aging under γ-irradiation was accomplished for evaluation of material behavior to hard stressing environment. Dielectric properties (real part of the permittivity and tan delta) and oxidation resistance were discussed. An improvement of the dielectric losses is noticed for the tested nanocomposites at a radiation dose up to 20 kGy. The radiochemical stability studied by chemiluminescence provides satisfactory stability in the correlation with slight modification of basis polymer due to the inert feature of filler.

  15. Poly(Butylene Terephthalate Based Composites Containing Alumina Whiskers: Influence of Filler Functionalization on Dielectric Properties

    Directory of Open Access Journals (Sweden)

    Pietro Russo

    2014-01-01

    Full Text Available Poly(butylene terephthalate (PBT is one of the most widely used semicrystalline thermoplastics polyester because of its superior thermal and mechanical properties, high dimensional stability and excellent processability. In this research PBT-based nanocomposites, including various amounts (up to 10 wt% of commercial alumina whiskers, have been prepared by using a Brabender internal chamber mixer and analysed in terms of morphological features and dielectric properties. Specific attention has been focused on the effect of the filler functionalization considering 3-glycidoxy propylmethoxysilane (GPS or 3-methacryloxypropyltrimethoxysilane (MPS as coupling agents. Tests, performed on compounds filled with neat and functionalized alumina whiskers, show a clear dependence of relative dielectric permittivity εr, invariance of dissipation factor (tgδ, and a sensible increase of volume electrical resistivity (ρv with the filler’s content and are encouraging for a future introduction of such composites in many electrical applications.

  16. Effect of Zr on dielectric, ferroelectric and impedance properties of ...

    Indian Academy of Sciences (India)

    Administrator

    dependent electrical properties are correlated with micro- structural changes using appropriate equivalent circuits that match the ... Sawyer-Tower circuit. The remnant polarization (Pr) and coercive field (Ec) were ..... is observed that two parallel RC contributions, in series with each other, are found to best fit the experimental.

  17. Microstructure, dielectric and piezoelectric properties of lead-free ...

    Indian Academy of Sciences (India)

    To improve the piezoelectric properties of Bi0.5Na0.5TiO3-based ceramics, a new perovskite-type leadfree piezoelectric (1 – ... School of Materials Science and Engineering, Guilin University of Electronic Technology, Guilin, Guangxi 541004, People's Republic of China; School of Materials Science and Engineering, ...

  18. On structural, optical and dielectric properties of zinc aluminate ...

    Indian Academy of Sciences (India)

    with a normal spinel structure having all zinc cations in the tetrahedral and all aluminium cations in the octahedral ... rrite in the nano-regime show anomalous magnetic properties in that zinc ions instead of occupying ... (Roy et al 2006). Zinc aluminate can be con- sidered as the non-magnetic counterpart of zinc ferrite and.

  19. Dielectric properties of Al-substituted Co ferrite nanoparticles

    Indian Academy of Sciences (India)

    Administrator

    have a narrow particle size, thereby influencing structural, electrical, and magnetic properties of spinel ferrites. Cobalt ferrite based nanomaterials are known to be a good candidate for magneto optical recording and very promising for applications in high-density storage (Panda et al 2003; Abo El Ata et al 2004; Zaki 2005).

  20. Effects of Bi doping on dielectric and ferroelectric properties of ...

    Indian Academy of Sciences (India)

    However, when the Bi-doping content is more than 0·6, the pyrochlore phase appears and the remnant polarization Pr of PLBZT ... cal transparency, outstanding ferroelectric and electro-optic properties (Gaidi et al 2004; Khodorov .... of the pyrochlore phase appear. In addition, a slight shift of characteristic peaks in XRD pa-.

  1. The effect of water absorption on the dielectric properties of polyethylene hexagonal boron nitride nanocomposites

    Science.gov (United States)

    Ayoob, Raed; Alhabill, Fuad N.; Andritsch, Thomas; Vaughan, Alun S.

    2018-02-01

    The effect of water absorption on the dielectric response of polyethylene/hexagonal boron nitride nanocomposites has been studied by dielectric spectroscopy. The nanocomposites have been prepared with hBN concentrations ranging from 2 wt% to 30 wt%. Fourier transform infrared spectroscopy and thermogravimetric analysis revealed a very small amount of hydroxyl groups on the surface of hBN. Mass loss measurements showed that the nanocomposites did not absorb any water under ambient and dry conditions while there was some water absorption under wet conditions. The dielectric spectroscopy results showed a broad relaxation peak, indicative of different states of water with water shells of different thickness, which moved to higher frequencies with increasing water content. However, the dielectric losses were significantly lower than the losses reported in the literature of nanocomposites under wet conditions. In addition, all the absorbed water was successfully removed under vacuum conditions which demonstrated that the interactions between the water and the nanocomposites were very weak, due to the hydrophobic nature of the hBN surface. This is a highly useful property, when considering these materials for applications in electrical insulation.

  2. 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.

  3. Dielectric properties of liquid crystalline dimer mixtures exhibiting the nematic and twist-bend nematic phases.

    Science.gov (United States)

    Trbojevic, Nina; Read, Daniel J; Nagaraj, Mamatha

    2017-11-01

    A detailed investigation of the thermal and dielectric properties of a series of binary mixtures exhibiting the nematic (N) and twist-bend nematic (N_{TB}) liquid crystal phases is presented. The mixtures consist of an achiral, dimeric liquid crystal CB7CB, which forms the nematic and twist-bend nematic phases, and a calamitic liquid crystal 5CB, which shows the nematic phase. As the concentration of the calamitic liquid crystal is increased, the transition temperatures decrease linearly, and the width of the nematic phase increases. The enthalpies of phase transitions obtained from DSC measurements show that on increasing the concentration of 5CB in the binary mixtures, the enthalpy associated with the N-N_{TB} phase transitions reduces considerably compared to a clear first-order N-N_{TB} transition in pure CB7CB. The real and imaginary parts of the dielectric permittivity are measured as a function of frequency from 100 Hz to 2 MHz in the nematic and twist-bend nematic phases in planar and homeotropic devices. A significant decrease in the average dielectric permittivity as a function of temperature for mixtures forming the N_{TB} phase is observed. Measurements of the imaginary part of the dielectric permittivity show a relaxation peak in the measured frequency window for all of the mixtures exhibiting the N_{TB} phase. The activation energy associated with this relaxation process is calculated and is shown to remain constant irrespective of the composition of the mixtures.

  4. Controlling Dielectric and Magnetic Properties of PVdF/Magnetite Nanocomposite Fibre Webs

    Directory of Open Access Journals (Sweden)

    A. P. Venugopal

    2014-01-01

    Full Text Available The ability of filtration and separation media containing fibres to remove impurities from oil, water, and blood can be enhanced using magnetic fields. The ability to regulate the dielectric and magnetic behaviour of fibrous webs in terms of superparamagnetic or ferromagnetic properties by adjusting material composition is fundamental to meeting end-use requirements. Electrospun fibres were produced from PVdF (polyvinylidene fluoride and nanomagnetite (Fe3O4 nanoparticles from solutions of PVdF in dimethylacetamide containing Fe3O4 nanoparticle contents ranging from 3 to 10 wt%. Fibre dimensions, morphology, and nanoparticle agglomeration were characterised by environmental scanning electron microscopy (ESEM and field emission gun transmission electron microscopy (FEGTEM. Dielectric behaviour of the fibre webs was influenced by web porosity and the Fe3O4 nanoparticle content. Impedance analysis of the webs indicated an increase in dielectric constant of ∼80% by the addition of 10 wt% Fe3O4 nanoparticles compared to 100 wt% PVdF. The dielectric constants of the webs were compared with those obtained from the theoretical mixing models of Maxwell and Lichtenecker. Vibrating sample magnetometer (VSM magnetisation measurements indicated a blocking temperature above 300 K suggesting ferrimagnetic rather than superparamagnetic behaviour as a result of Fe3O4 nanoparticle agglomeration within fibres.

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

    Energy Technology Data Exchange (ETDEWEB)

    Pan, Ming-Jen; Gorzkowski, Edward; McAllister, Kelly, E-mail: pan@anvil.nrl.navy.mi [Multifunctional Materials Branch, Code 6350 U.S. Naval Research Laboratory 4555 Overlook Avenue SW, Washington, DC 20375 (United States)

    2011-10-29

    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.

  6. Morphological, Raman, electrical and dielectric properties of rare earth doped X-type hexagonal ferrites

    Energy Technology Data Exchange (ETDEWEB)

    Majeed, Abdul, E-mail: abdulmajeed2276@gmail.com [Department of Physics, The Islamia University of Bahawalpur, Bahawalpur 63100 (Pakistan); Center for Computational Materials Science, Department of Physics, University of Malakand, Chakdara, Dir (Lower) 18800 (Pakistan); Khan, Muhammad Azhar, E-mail: azhar.khan@iub.edu.pk [Department of Physics, The Islamia University of Bahawalpur, Bahawalpur 63100 (Pakistan); Raheem, Faseeh ur [Department of Physics, The Islamia University of Bahawalpur, Bahawalpur 63100 (Pakistan); Ahmad, Iftikhar [Center for Computational Materials Science, Department of Physics, University of Malakand, Chakdara, Dir (Lower) 18800 (Pakistan); Department of Physics, Abbottabad University of Science & Technology, Abbottabad (Pakistan); Akhtar, Majid Niaz [Department of Physics, COMSATS Institute of Information Technology, Lahore 54000 (Pakistan); Warsi, Muhammad Farooq [Department of Chemistry, The Islamia University of Bahawalpur, Bahawalpur 63100 (Pakistan)

    2016-12-15

    The influence of rare-earth metals (La, Nd, Gd, Tb, Dy) on morphology, Raman, electrical and dielectric properties of Ba{sub 2}NiCoRE{sub x}Fe{sub 28−}xO{sub 46} ferrites were studied. The scanning electron microscopy (SEM) exhibited the platelet like structure of these hexagonal ferrites. The surface morphology indicated the formation of ferrite grains in the nano-regime scale. The bands obtained at lower wave number may be attributed to the metal-oxygen vibration at octahedral site which confirm the development of hexagonal phase of these ferrites. The resonance peaks were observed in dielectric constant, dielectric loss factor and quality factor versus frequency graphs. These dielectric parameters indicate that these ferrites nano-materials are potential candidates in the high frequency applications. The enhancement in DC electric resistivity from 2.48×10{sup 8} to 1.20×10{sup 9} Ω cm indicates that the prepared materials are beneficial for decreasing the eddy current losses at high frequencies and for the fabrication of multilayer chip inductor (MLCI) devices.

  7. Modelling effective dielectric properties of materials containing diverse types of biological cells

    International Nuclear Information System (INIS)

    Huclova, Sonja; Froehlich, Juerg; Erni, Daniel

    2010-01-01

    An efficient and versatile numerical method for the generation of different realistically shaped biological cells is developed. This framework is used to calculate the dielectric spectra of materials containing specific types of biological cells. For the generation of the numerical models of the cells a flexible parametrization method based on the so-called superformula is applied including the option of obtaining non-axisymmetric shapes such as box-shaped cells and even shapes corresponding to echinocytes. The dielectric spectra of effective media containing various cell morphologies are calculated focusing on the dependence of the spectral features on the cell shape. The numerical method is validated by comparing a model of spherical inclusions at a low volume fraction with the analytical solution obtained by the Maxwell-Garnett mixing formula, resulting in good agreement. Our simulation data for different cell shapes suggest that around 1MHz the effective dielectric properties of different cell shapes at different volume fractions significantly deviate from the spherical case. The most pronounced change exhibits ε eff between 0.1 and 1 MHz with a deviation of up to 35% for a box-shaped cell and 15% for an echinocyte compared with the sphere at a volume fraction of 0.4. This hampers the unique interpretation of changes in cellular features measured by dielectric spectroscopy when simplified material models are used.

  8. Effect of neodymium substitution on the electric and dielectric properties of Mn-Ni-Zn ferrite

    Science.gov (United States)

    Agami, W. R.

    2018-04-01

    Ferrite samples of Mn0.5Ni0.1Zn0.4NdxFe2-xO4 (x = 0.0, 0.01, 0.02, 0.05, 0.075 and 0.1) have been prepared by usual ceramic method. The temperature and composition dependences of the dc electric resistivity (ρdc) were studied. The frequency and composition dependences of the ac electric resistivity (ρac) and dielectric parameters (dielectric constant ε' and dielectric loss ε'') have been investigated. ρdc was found to decrease with temperature for all samples while it increases with increasing Nd3+ concentration. On the other hand, ρac and the dielectric properties were found to decrease with increasing the frequency while ρac increases and both ε' and ε'' decrease with increasing Nd3+ concentration. These results were explained by the Maxwell-Wagner two-layer model and Koops's theory. The improvement in dc and ac electric resistivities shows that these prepared materials are valid for decreasing the eddy current losses at high frequencies, so they can be used in the fabrication of multilayer chip inductor (MLCI) devices.

  9. Electrical and dielectric properties of foam injection-molded polypropylene/multiwalled carbon nanotube composites

    Energy Technology Data Exchange (ETDEWEB)

    Ameli, A.; Nofar, M.; Saniei, M.; Hossieny, N.; Park, C. B. [Microcellular Plastics Manufacturing Laboratory, Department of Mechanical and Industrial Engineering, University of Toronto, 5 King’s College Road, Toronto, Ontario, Canada M5S 3G8 (Canada); Pötschke, P. [Leibniz-Institut für Polymerforschung Dresden e.V. (IPF), Hohe Strasse 6, D-01069 Dresden (Germany)

    2015-05-22

    A combination of high dielectric permittivity (ε′) and low dielectric loss (tan δ) is required for charge storage applications. In percolative systems such as conductive polymer composites, however, obtaining high ε′ and low tan δ is very challenging due to the sharp insulation-conduction transition near the threshold region. Due to the particular arrangement of conductive fillers induced by both foaming and injection molding processes, they may address this issue. Therefore, this work evaluates the application of foam injection molding process in fabricating polymer nanocomposites for energy storage. Polypropylene-multiwalled carbon nanotubes (PP-MWCNT) composites were prepared by melt mixing and foamed in an injection molding process. Electrical conductivity (σ), ε′ and tan δ were then characterized. Also, scanning and transmission electron microscopy (SEM and TEM) was used to investigate the carbon nanotube’s arrangement as well as cellular morphology. The results showed that foam injection-molded composites exhibited highly superior dielectric properties to those of solid counterparts. For instance, foamed samples had ε′=68.3 and tan δ =0.05 (at 1.25 vol.% MWCNT), as opposed to ε′=17.8 and tan δ=0.04 in solid samples (at 2.56 vol.% MWCNT). The results of this work reveal that high performance dielectric nanocomposites can be developed using foam injection molding technologies for charge storage applications.

  10. Electrical and dielectric properties of foam injection-molded polypropylene/multiwalled carbon nanotube composites

    Science.gov (United States)

    Ameli, A.; Nofar, M.; Saniei, M.; Hossieny, N.; Park, C. B.; Pötschke, P.

    2015-05-01

    A combination of high dielectric permittivity (ɛ') and low dielectric loss (tan δ) is required for charge storage applications. In percolative systems such as conductive polymer composites, however, obtaining high ɛ' and low tan δ is very challenging due to the sharp insulation-conduction transition near the threshold region. Due to the particular arrangement of conductive fillers induced by both foaming and injection molding processes, they may address this issue. Therefore, this work evaluates the application of foam injection molding process in fabricating polymer nanocomposites for energy storage. Polypropylene-multiwalled carbon nanotubes (PP-MWCNT) composites were prepared by melt mixing and foamed in an injection molding process. Electrical conductivity (σ), ɛ' and tan δ were then characterized. Also, scanning and transmission electron microscopy (SEM and TEM) was used to investigate the carbon nanotube's arrangement as well as cellular morphology. The results showed that foam injection-molded composites exhibited highly superior dielectric properties to those of solid counterparts. For instance, foamed samples had ɛ'=68.3 and tan δ =0.05 (at 1.25 vol.% MWCNT), as opposed to ɛ'=17.8 and tan δ=0.04 in solid samples (at 2.56 vol.% MWCNT). The results of this work reveal that high performance dielectric nanocomposites can be developed using foam injection molding technologies for charge storage applications.

  11. Dielectric properties of CaCu2·9Co0·1Ti4O12 and CaCu3Ti3·9Co0 ...

    Indian Academy of Sciences (India)

    Ramirez et al 2000; Subramanian et al. 2000). These unique properties of CCTO make it a promis- ing material for microelectronic applications. But its high dielectric loss restricts its application in miniaturization of electronic devices. Dielectric ...

  12. Dielectric properties of some cadmium and mercury amino alcohol complexes at low temperatures

    Directory of Open Access Journals (Sweden)

    ALAA E. ALI

    2002-12-01

    Full Text Available The dielectric properties of some cadmium and mercury amino alcohol complexes were studied within the temperature range of 100–300 K at the frequencies of 100, 300 and 1000 kHz. The polarization mechanisms are suggested and the dependence of both e and tg d on both temperature and frequency are analyzed. The analysis of the data reveals semi-conducting features based mainly on the hopping mechanism.

  13. Dielectric properties of electron irradiated PbZrO3 thin films

    Indian Academy of Sciences (India)

    The present paper deals with the study of the effects of electron (8 MeV) irradiation on the dielectric and ferroelectric properties of PbZrO3 thin films grown by sol–gel technique. The films were (0.62 m thick) subjected to electron irradiation using Microtron accelerator (delivered dose 80, 100, 120 kGy). The films were well ...

  14. Relaxor behaviour and dielectric properties of BiFeO3 doped Ba ...

    Indian Academy of Sciences (India)

    2016-08-26

    Aug 26, 2016 ... Ba1−Bi(Ti0.9Zr0.1)1−FeO3 ( = 0–0.075) ceramics are prepared using a conventional solid state reaction method. X-ray diffraction shows the presence of a single phase. Addition of Bi3+ and Fe3+ strongly influences the crystal structure and dielectric properties of the ceramics. The evolution from a ...

  15. Dielectric and optical properties of glasses of CdO-B2O3 system

    International Nuclear Information System (INIS)

    Semin, V.N.; Mal'tsev, V.T.; Panich, A.E.

    1986-01-01

    Dielectric and optical properties of glasses of CdO-B 2 O 3 system are investigated. It is shown, that on changing the composition, cadmic-borate glasses undergo structural changes, similar to those, taking place in lead-borate glasses, and the maximum part of the boron atoms in the oxygen tetrahedral coordination is at CdO:B 2 O 3 =3:2

  16. Dielectric properties of electron irradiated PbZrO 3 thin films

    Indian Academy of Sciences (India)

    The present paper deals with the study of the effects of electron (8 MeV) irradiation on the dielectric and ferroelectric properties of PbZrO3 thin films grown by sol–gel technique. The films were (0.62 m thick) subjected to electron irradiation using Microtron accelerator (delivered dose 80, 100, 120 kGy). The films were well ...

  17. The effect of dielectric properties on the electrorheology of suspensions of silica particles coated with polyaniline

    Czech Academy of Sciences Publication Activity Database

    Lengálová, A.; Pavlínek, V.; Sáha, P.; Stejskal, Jaroslav; Kitano, T.; Quadrat, Otakar

    2003-01-01

    Roč. 321, 3-4 (2003), s. 411-424 ISSN 0378-4371 R&D Projects: GA AV ČR IAA4050313; GA MŠk ME 564 Institutional research plan: CEZ:AV0Z4050913; CEZ:MSM 265200015 Keywords : conducting polymer * dielectric properties * electrorheology Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.180, year: 2003

  18. Properties of Floquet-Bloch space harmonics in 1D periodic magneto-dielectric structures

    DEFF Research Database (Denmark)

    Breinbjerg, O.

    2012-01-01

    Recent years have witnessed a significant research interest in Floquet-Bloch analysis for determining the homogenized permittivity and permeability of metamaterials consisting of periodic structures. This work investigates fundamental properties of the Floquet-Bloch space harmonics in a 1......-dimensional magneto-dielectric lossless structure supporting a transverse-electric-magnetic Floquet-Bloch wave; in particular, the space harmonic permittivity and permeability, as well as the space harmonic Poynting vector....

  19. Effects of SiO 2 and TiO 2 fillers on thermal and dielectric properties ...

    Indian Academy of Sciences (India)

    2 and TiO2 fillers on thermal and dielectric properties of eco-friendly bismuth glass microcomposites of plasma display panels. Shiv Prakash Singh Karan Pal Anal Tarafder Mousumi Das Kalyandurg Annapurna Basudeb Karmakar. Composites ...

  20. THz - ToF Optical Layer Analysis (OLA) to determine optical properties of dielectric materials

    Science.gov (United States)

    Spranger, Holger; Beckmann, Jörg

    2017-02-01

    Electromagnetic waves with frequencies between 0.1 and 10 THz are described as THz-radiation (T-ray). The ability to penetrate dielectric materials makes T-rays attractive to reveal discontinuities in polymer and ceramic materials. THz-Time Domain Spectroscopy Systems (THz-TDS) are available on the market today which operates with THz-pulses transmitted and received by optically pumped semiconductor antennas. In THz-TDS the travelling time (ToF) and shape of the pulse is changed if it interacts with the dielectric material and its inherent discontinuities. A tomogram of the object under the test can be reconstructed from time of flight diffraction (ToFD) scans if a synthetic focusing aperture (SAFT) algorithm is applied. The knowledge of the base materials shape and optical properties is essential for a proper reconstruction result. To obtain these properties a model is assumed which describes the device under the test as multilayer structure composed of thin layers with different dielectric characteristics. The Optical Layer Analysis (OLA) is able to fulfill these requirements. A short description why the optical properties are crucial for meaningful SAFT reconstruction results will be given first. Afterwards the OLA will be derived and applied on representative samples to discuss and evaluate its benefits and limits.

  1. Fabrication and Dielectric Properties of AlN Filled Epoxy Nano-composites

    Energy Technology Data Exchange (ETDEWEB)

    Gao Naiui; Yu Xin; Jin Haiyun; He Bo; Dong Pu [State Key Laboratory of Electrical Insulation and Power Equipment, Xi' an Jiaotong University, Xi' an, 710049 (China); Gao Chao, E-mail: hyjin@mail.xjtu.edu.cn

    2011-10-29

    Epoxy resins were materials with excellent mechanical, electrical properties and good chemical stability. Thus, they had been used in various fields, especially in electrical and electronic application. However, because they were brittle material, the fields of application were limited. Adding nano-Aluminum Nitride (AlN) into Epoxy resins could improve the toughness of the composites, the thermal behaviors of composites could also be improved, but the influence on dielectric properties was not very clear. In this research, epoxy resin based composites were fabricated. The relationships between the dielectric properties and the nano-AlN particle content were investigated. The results showed that, both relative permittivity ({epsilon}{sub r}) and dielectric loss tangent (tan{delta}) decreased to be less than that of monolithic epoxy when nano-AlN particle content was no more than certain amount, the DC volume resistivity ({rho}{sub v}) and low frequency resistivity decreased with increasing nano-AlN content (in certain range of content). AC breakdown strength (E{sub B}) did not have an obvious tendency with nano-AlN content.

  2. Quantification of physical (roughness) and chemical (dielectric constant) leaf surface properties relevant to wettability and adhesion.

    Science.gov (United States)

    Nairn, Justin J; Forster, W Alison; van Leeuwen, Rebecca M

    2011-12-01

    Spray droplet adhesion is dependent not only on formulation and droplet parameters but also on the surface properties (physical and chemical) of the leaf. Quantifying these leaf surface properties would aid understanding and modelling of adhesion, helping to optimise spray formulations. Fractal dimensions (FDs) were used to quantify the relative leaf surface roughness of ten plant species. Static droplet contact angles were measured on each leaf surface, and wetting tension was calculated. Chemical profiles of the leaf surfaces were developed by evaluating contact angle behaviour relative to solution dielectric constants. The FDs of Cryo-SEM micrographs taken at 300× magnification gave the best correlation with adhesion. The wetting tension intercept had a strong relationship with mean adhesion, and successfully accounted for the wettability of the outlier species. The microroughness of the leaf surface, as revealed by Cryo-SEM, can be quantified by fractal dimension analysis. However, the wetting tension intercept is a more useful universal measure of the surface properties of the leaf (including roughness) as they pertain to adhesion. The slope of the wetting tension versus dielectric constant plot allowed preliminary quantification of the chemical contribution of leaf surface dielectric behaviour to adhesion. Copyright © 2011 Society of Chemical Industry.

  3. Fabrication and Dielectric Properties of AlN Filled Epoxy Nano-composites

    International Nuclear Information System (INIS)

    Gao Naiui; Yu Xin; Jin Haiyun; He Bo; Dong Pu; Gao Chao

    2011-01-01

    Epoxy resins were materials with excellent mechanical, electrical properties and good chemical stability. Thus, they had been used in various fields, especially in electrical and electronic application. However, because they were brittle material, the fields of application were limited. Adding nano-Aluminum Nitride (AlN) into Epoxy resins could improve the toughness of the composites, the thermal behaviors of composites could also be improved, but the influence on dielectric properties was not very clear. In this research, epoxy resin based composites were fabricated. The relationships between the dielectric properties and the nano-AlN particle content were investigated. The results showed that, both relative permittivity (ε r ) and dielectric loss tangent (tanδ) decreased to be less than that of monolithic epoxy when nano-AlN particle content was no more than certain amount, the DC volume resistivity (ρ v ) and low frequency resistivity decreased with increasing nano-AlN content (in certain range of content). AC breakdown strength (E B ) did not have an obvious tendency with nano-AlN content.

  4. Dielectric properties of glasses prepared by quenching melts of superconducting Bi-Ca-Sr-Cu-O cuprates

    Energy Technology Data Exchange (ETDEWEB)

    Varma, K. B. R.; Subbanna, G. N.; Ramakrishnan, T. V.; Rao, C. N. R.

    1989-07-03

    Glasses obtained from quenching melts of superconducting bismuth cuprates of the formula Bi/sub 2/(Ca,Sr)/sub /ital n/+1/Cu/sub /ital n//O/sub 2/ital n/+4/ with /ital n/=1 and 3 exhibit novel dielectric properties. They possess relatively high dielectric constants as well as high electrical conductivity. The novel dielectric properties of these cuprate glasses are likely to be of electronic origin. They exhibit a weak microwave absorption due to the presence of microcrystallites.

  5. Extraordinary biological properties of a new calcium hydroxyapatite/poly(lactide-co-glycolide)-based scaffold confirmed by in vivo investigation.

    Science.gov (United States)

    Jokanović, Vukoman; Čolović, Božana; Marković, Dejan; Petrović, Milan; Soldatović, Ivan; Antonijević, Djordje; Milosavljević, Petar; Sjerobabin, Nikola; Sopta, Jelena

    2017-05-24

    This study examined the potential of a new porous calcium hydroxyapatite scaffold covered with poly (lactide-co-glycolide) (PLGA) as a bone substitute, identifying its advantages over Geistlich Bio-Oss®, considered the gold standard, in in vivo biofunctionality investigations. Structural and morphological properties of the new scaffold were analyzed by scanning electron and atomic force microscopy. The biofunctionality assays were performed on New Zealand white rabbits using new scaffold for filling full-thickness defects of critical size. The evaluated parameters were: the presence of macrophages, giant cells, monoocytes, plasma cells, granulocytes, neoangiogenesis, fibroplasia, and the percentage of mineralization. Parallel biofunctionality assays were performed using Geistlich Bio-Oss®. The appearance of bone defects 12 weeks after the new scaffold implantation showed the presence of a small number of typical immune response cells. Furthermore, significantly reduced number of capillary buds, low intensity of fibroplasia and high degree of mineralization in a lamellar pattern indicated that the inflammation process has been almost completely overcome and that the new bone formed was in the final phase of remodeling. All biofunctionality assays proved the new scaffold's suitability as a bone substitute for applications in maxillofacial surgery. It showed numerous biological advantages over Geistlich Bio-Oss® which was reflected mainly as a lower number of giant cells surrounding implanted material and higher degree of mineralization in new formed bone.

  6. A Comparison of Dielectric Properties of Palm Oil with Mineral and Synthetic Types Insulating Liquid under Temperature Variation

    OpenAIRE

    Abdul Rajab; Aminuddin Sulaeman; Sudaryatno Sudirham; Suwarno

    2011-01-01

    Mineral oil is known to have a low biodegradability level and high susceptibility to the fire. These conditions motivate many researchers to look for alternative sources for insulating oil. One of the alternative liquid is palm oil. To verify the suitability of using palm oil as an insulating liquid, it is important to make dielectric properties comparison with the commonly used insulating liquid. This paper presents comparison of temperature effect on dielectric properties of palm...

  7. Computational study of dielectric function and optical properties of a graphane nano structure containing graphene quantum dot

    International Nuclear Information System (INIS)

    Sharma, Jyoti Dhar; Sharma, Munish; Kumar, Naveen; Ahluwalia, P K

    2013-01-01

    Ab-Initio computational study of dielectric function and optical properties of a graphane nano structure containing graphene quantum dot has been undertaken within Density Functional Theory using SIESTA code. Band structure, PDOS, real and imaginary parts of dielectric function, reflectance and energy loss have been calculated and frequencies corresponding to peak positions have been tabulated for each case. A comparison has been made with the corresponding properties of pristine graphene

  8. Changes in the dielectric properties of medaka fish embryos during development, studied by electrorotation

    Energy Technology Data Exchange (ETDEWEB)

    Shirakashi, Ryo, E-mail: aa21150@iis.u-tokyo.ac.jp [Institute of Industrial Science, The University of Tokyo, Tokyo 153-8505 (Japan); Mischke, Miriam [Lehrstuhl fuer Biotechnologie und Biophysik, Biozentrum, Universitaet Wuerzburg, Wuerzburg (Germany); Fischer, Peter [Physiologische Chemie, Biozentrum, Universitaet Wuerzburg, Wuerzburg (Germany); Memmel, Simon [Lehrstuhl fuer Biotechnologie und Biophysik, Biozentrum, Universitaet Wuerzburg, Wuerzburg (Germany); Krohne, Georg [Abteilung fuer Elektronenmikroskopie, Biozentrum, Universitaet Wuerzburg, Wuerzburg (Germany); Fuhr, Guenter R. [Lehrstuhl fuer Biotechnologie und Medizintechnik, Universitaet des Saarlandes, Saarbruecken (Germany); Zimmermann, Heiko [Lehrstuhl fuer Molekulare und Zellulaere Biotechnologie, Universitaet des Saarlandes, Saarbruecken (Germany); Sukhorukov, Vladimir L., E-mail: sukhorukov@biozentrum.uni-wuerzburg.de [Lehrstuhl fuer Biotechnologie und Biophysik, Biozentrum, Universitaet Wuerzburg, Wuerzburg (Germany)

    2012-11-09

    Highlights: Black-Right-Pointing-Pointer Electrorotation offers a non-invasive tool for dielectric analysis of fish embryos. Black-Right-Pointing-Pointer The three-shell dielectric model matches the rotation spectra of medaka eggs. Black-Right-Pointing-Pointer The capacitance value suggests a double-membrane structure of yolk envelope. -- Abstract: The Japanese medaka fish, Oryzias latipes, has become a powerful vertebrate model organism in developmental biology and genetics. The present study explores the dielectric properties of medaka embryos during pre-hatching development by means of the electrorotation (ROT) technique. Due to their layered structure, medaka eggs exhibited up to three ROT peaks in the kHz-MHz frequency range. During development from blastula to early somite stage, ROT spectra varied only slightly. But as the embryo progressed to the late-somite stage, the ROT peaks underwent significant changes in frequency and amplitude. Using morphological data obtained by light and electron microscopy, we analyzed the ROT spectra with a three-shell dielectric model that accounted for the major embryonic compartments. The analysis yielded a very high value for the ionic conductivity of the egg shell (chorion), which was confirmed by independent osmotic experiments. A relatively low capacitance of the yolk envelope was consistent with its double-membrane structure revealed by transmission electron microscopy. Yolk-free dead eggs exhibited only one co-field ROT peak, shifted markedly to lower frequencies with respect to the corresponding peak of live embryos. The dielectric data may be useful for monitoring the development and changes in fish embryos' viability/conditions in basic research and industrial aquaculture.

  9. Changes in the dielectric properties of medaka fish embryos during development, studied by electrorotation

    International Nuclear Information System (INIS)

    Shirakashi, Ryo; Mischke, Miriam; Fischer, Peter; Memmel, Simon; Krohne, Georg; Fuhr, Günter R.; Zimmermann, Heiko; Sukhorukov, Vladimir L.

    2012-01-01

    Highlights: ► Electrorotation offers a non-invasive tool for dielectric analysis of fish embryos. ► The three-shell dielectric model matches the rotation spectra of medaka eggs. ► The capacitance value suggests a double-membrane structure of yolk envelope. -- Abstract: The Japanese medaka fish, Oryzias latipes, has become a powerful vertebrate model organism in developmental biology and genetics. The present study explores the dielectric properties of medaka embryos during pre-hatching development by means of the electrorotation (ROT) technique. Due to their layered structure, medaka eggs exhibited up to three ROT peaks in the kHz–MHz frequency range. During development from blastula to early somite stage, ROT spectra varied only slightly. But as the embryo progressed to the late-somite stage, the ROT peaks underwent significant changes in frequency and amplitude. Using morphological data obtained by light and electron microscopy, we analyzed the ROT spectra with a three-shell dielectric model that accounted for the major embryonic compartments. The analysis yielded a very high value for the ionic conductivity of the egg shell (chorion), which was confirmed by independent osmotic experiments. A relatively low capacitance of the yolk envelope was consistent with its double-membrane structure revealed by transmission electron microscopy. Yolk-free dead eggs exhibited only one co-field ROT peak, shifted markedly to lower frequencies with respect to the corresponding peak of live embryos. The dielectric data may be useful for monitoring the development and changes in fish embryos’ viability/conditions in basic research and industrial aquaculture.

  10. Dielectric and Radiative Properties of Sea Foam at Microwave Frequencies: Conceptual Understanding of Foam Emissivity

    Directory of Open Access Journals (Sweden)

    Peter W. Gaiser

    2012-04-01

    Full Text Available Foam fraction can be retrieved from space-based microwave radiometric data at frequencies from 1 to 37 GHz. The retrievals require modeling of ocean surface emissivity fully covered with sea foam. To model foam emissivity well, knowledge of foam properties, both mechanical and dielectric, is necessary because these control the radiative processes in foam. We present a physical description of foam dielectric properties obtained from the foam dielectric constant including foam skin depth; foam impedance; wavelength variations in foam thickness, roughness of foam layer interfaces with air and seawater; and foam scattering parameters such as size parameter, and refraction index. Using these, we analyze the scattering, absorption, reflection and transmission in foam and gain insights into why volume scattering in foam is weak; why the main absorption losses are confined to the wet portion of the foam; how the foam impedance matching provides the transmission of electromagnetic radiation in foam and maximizes the absorption; and what is the potential for surface scattering at the foam layers boundaries. We put all these elements together and offer a conceptual understanding for the high, black-body-like emissivity of foam floating on the sea surface. We also consider possible scattering regimes in foam.

  11. An experimental study of electrical and dielectric properties of consolidated clayey materials

    International Nuclear Information System (INIS)

    Comparon, L.

    2005-06-01

    This study is devoted to the electrical and dielectric properties of consolidated clays. A better understanding of the conduction and polarization phenomena in clays is necessary to better interpret in situ measurements in terms of water saturation and texture. An experimental study was carried out on synthetic clay samples (kaolinite and smectite) compacted with various water contents, porosities and mineralogical compositions, on a large frequency range, using three laboratory setups. The electrical properties of natural argillites (from ANDRA) were then investigated. We found that the response of the synthetic samples is mainly controlled by water content on the whole frequency range; two polarization phenomena were observed, which were related to the Maxwell-Wagner polarization and the electrical double layer polarization around the clay particles. The electrical response of argillites is more complex; it is controlled by water content but also by the microstructure of the rock. In these rocks, the electrical and dielectric anisotropies are high; anisotropy was also measured for the synthetic clays. The existing models explain the high frequency limit of the dielectric permittivity of the clayey materials, but the low frequency part of the spectra (≤1 MHz) needs theoretical developments. (author)

  12. Effect of lanthanum substitution on dielectric relaxation, impedance response, conducting and magnetic properties of strontium hexaferrite

    Energy Technology Data Exchange (ETDEWEB)

    Want, Basharat, E-mail: bawant@kashmiruniversity.ac.in; Bhat, Bilal Hamid; Ahmad, Bhat Zahoor

    2015-04-05

    Highlights: • The substitution of La affects the dielectric and magnetic properties of strontium hexaferrite. • The electric behaviour of the compound follows the Koop’s phenomenological theory. • The impedance study shows the role of grain boundaries to the electric properties of the compound. • The substitution of La to strontium hexaferrite reduces the resistive nature of grain boundaries. - Abstract: Lanthanum strontium hexaferrite Sr{sub 1−x}La{sub x}Fe{sub 12}O{sub 19} (x = 0, 0.08, 0.13 , 0.18) has been successfully synthesized by using citrate-precursor method and characterized by different techniques. The X-ray diffraction results revealed that the sample is crystalline in nature and is of single phase with the space group P63/mmc. The dielectric, conducting and impedance related studies have been carried out as a function of frequency and concentration of lanthanum in the frequency ranges of 20 Hz–3 MHz. Impedance studies were performed in the frequency domain to distinguish between bulk and grain boundary contributions of the material to the overall dielectric response. The electric response of the material was also modeled by an equivalent circuit and different circuit parameters were calculated. Magnetic characterization of the material was also performed and the effect of lanthanum concentration was studied. The hysteresis loop obtained from the magnetometer showed that with the increase of lanthanum concentration, the saturation magnetisation decreases while as coercivity increases.

  13. Mechanical and dielectric properties of SEBS modified by graphite inclusion and composite interface

    Science.gov (United States)

    Grigorescu, Ramona Marina; Ciuprina, Florin; Ghioca, Paul; Ghiurea, Marius; Iancu, Lorena; Spurcaciu, Bogdan; Panaitescu, Denis Mihaela

    2016-02-01

    Tough and flexible dielectrics were prepared using graphite (G), a natural and low-cost resource, as filler in polystyrene-b-(ethylene-co-butylene)-b-polystyrene (SEBS) and maleinized SEBS (SEBS-MA) matrices. The disintegration of graphite in submicron particles was accomplished by the shear forces during the melt processing step and it was highlighted by atomic force microscopy. Simultaneous increase of tensile strain, strength and Young's modulus was noticed for SEBS/G and SEBS-MA/G composites compared to unfilled matrices, this remarkable feature being previously reported only for some nanocomposites. Moreover, an exponential variation of the dielectric permittivity with the volume fraction of G was obtained. Higher reinforcing efficiency and better dielectric properties were observed in SEBS-MA/G composites, compared to the corresponding SEBS/G composites, due to the stronger polymer-filler interface and better dispersion of graphite. This study brings new insights into nanolevel properties of SEBS composites and it opens new perspectives on high performance composites by using graphite instead of expensive graphene and efficient melt mixing process.

  14. STRUCTURAL, DIELECTRIC AND MAGNETIC PROPERTIES OF Fe-DOPED SrZrO₃ CERAMICS

    Directory of Open Access Journals (Sweden)

    Chunhong Tang

    2016-03-01

    Full Text Available SrZrO₃-based perovskite oxides have been extensively studied for their outstanding physical characteristics, chemical stability, and mechanical properties. With the recent development of multiferroics, room temperature ferromagnetism is expected to be introduced to ferroelectric or dielectric materials by magnetic ion doping in order to obtain single-phase magnetoelectric or magnetodielectric materials. In this work, SrZrO₃ and SrZr0.9375Fe0.0625O3 ceramics were fabricated by a conventional solid-state reaction method. Their structural, dielectric and magnetic properties were carefully investigated. It was found that Fe-doping could effectively improve the dielectric constant of SrZrO₃. Moreover, ferromagnetism with a Curie temperature of about 685 K was successfully introduced by a small amount of Fe dopant. The saturation magnetization and coercive field of SrZrO₃ and SrZr0.9375Fe0.0625O3 ceramics were 3.0 emu/g and 1.3 kOe, respectively, at room temperature. The origin and mechanism of ferromagnetism introduced by Fe dopant is discussed based on the valence fluctuation of Fe ions.

  15. Dielectric properties of lava flows west of Ascraeus Mons, Mars

    Science.gov (United States)

    Carter, L.M.; Campbell, B.A.; Holt, J.W.; Phillips, R.J.; Putzig, N.E.; Mattei, S.; Seu, R.; Okubo, C.H.; Egan, A.F.

    2009-01-01

    The SHARAD instrument on the Mars Reconnaissance Orbiter detects subsurface interfaces beneath lava flow fields northwest of Ascraeus Mons. The interfaces occur in two locations; a northern flow that originates south of Alba Patera, and a southern flow that originates at the rift zone between Ascraeus and Pavonis Montes. The northern flow has permittivity values, estimated from the time delay of echoes from the basal interface, between 6.2 and 17.3, with an average of 12.2. The southern flow has permittivity values of 7.0 to 14.0, with an average of 9.8. The average permittivity values for the northern and southern flows imply densities of 3.7 and 3.4 g cm-3, respectively. Loss tangent values for both flows range from 0.01 to 0.03. The measured bulk permittivity and loss tangent values are consistent with those of terrestrial and lunar basalts, and represent the first measurement of these properties for dense rock on Mars. Copyright 2009 by the American Geophysical Union.

  16. Extraordinary role of Ce-Ni elements on the electrical and magnetic properties of Sr-Ba M-type hexaferrites

    Energy Technology Data Exchange (ETDEWEB)

    Iqbal, Muhammad Javed, E-mail: mjiqauchem@yahoo.com [Surface and Solid State Chemistry Laboratory, Department of Chemistry, Quaid-i-Azam University, Islamabad 45320 (Pakistan); Farooq, Saima [Surface and Solid State Chemistry Laboratory, Department of Chemistry, Quaid-i-Azam University, Islamabad 45320 (Pakistan)

    2009-11-15

    The structural, electrical and magnetic behavior of Sr{sub 0.5}Ba{sub 0.5-x}Ce{sub x}Fe{sub 12-y}Ni{sub y}O{sub 19} (where x = 0.00-0.10; y = 0.00-1.00) hexaferrite nanomaterials are reported in this paper. The structural analysis indicates that the Ce-Ni doped Sr-Ba M-type hexaferrite samples synthesized by the co-precipitation method are stoichiometric, single magnetoplumbite phase with crystallite sizes in the range of 35-48 nm. The dc-electrical resistivity of the pure Sr-Ba hexaferrite is enhanced to almost 10{sup 2} times by doping with Ce-Ni contents of x = 0.06; y = 0.60. The dielectric constant and dielectric loss tangent decrease to values {approx}14 and <0.2, respectively, by increasing the frequency up to 1 MHz. Small relaxation peaks at frequencies >10{sup 5} Hz are observed for the samples with Ce content of x > 0.06. The values of saturation magnetization increase from 66.32 to 84.33 emu/g and remanance magnetization from 42.64 to 56.01 emu/g but coercivity decreases from 2.85 to 1.59 kOe by substitution of Ce-Ni. Sharp ferri-paramagnetic transition is observed in the samples, which is confirmed by DSC results. Ce-Ni substitution acts to reduce the electron-hopping between Fe{sup 2+}/Fe{sup 3+} ions and also improves the magnetic properties. These characteristics are desirable for their possible use in microwave and chip devices.

  17. Microstructure and Dielectric Properties of LPCVD/CVI-SiBCN Ceramics Annealed at Different Temperatures

    Directory of Open Access Journals (Sweden)

    Jianping Li

    2017-06-01

    Full Text Available SiBCN ceramics were introduced into porous Si3N4 ceramics via a low-pressure chemical vapor deposition and infiltration (LPCVD/CVI technique, and then the composite ceramics were heat-treated from 1400 °C to 1700 °C in a N2 atmosphere. The effects of annealing temperatures on microstructure, phase evolution, dielectric properties of SiBCN ceramics were investigated. The results revealed that α-Si3N4 and free carbon were separated below 1700 °C, and then SiC grains formed in the SiBCN ceramic matrix after annealing at 1700 °C through a phase-reaction between free carbon and α-Si3N4. The average dielectric loss of composites increased from 0 to 0.03 due to the formation of dispersive SiC grains and the increase of grain boundaries.

  18. Temperature dependent dielectric properties and ion transportation in solid polymer electrolyte for lithium ion batteries

    Science.gov (United States)

    Sengwa, R. J.; Dhatarwal, Priyanka; Choudhary, Shobhna

    2016-05-01

    Solid polymer electrolyte (SPE) film consisted of poly(ethylene oxide) (PEO) and poly(methyl methacrylate) (PMMA) blend matrix with lithium tetrafluroborate (LiBF4) as dopant ionic salt and poly(ethylene glycol) (PEG) as plasticizer has been prepared by solution casting method followed by melt pressing. Dielectric properties and ionic conductivity of the SPE film at different temperatures have been determined by dielectric relaxation spectroscopy. It has been observed that the dc ionic conductivity of the SPE film increases with increase of temperature and also the decrease of relaxation time. The temperature dependent relaxation time and ionic conductivity values of the electrolyte are governed by the Arrhenius relation. Correlation observed between dc conductivity and relaxation time confirms that ion transportation occurs with polymer chain segmental dynamics through hopping mechanism. The room temperature ionic conductivity is found to be 4 × 10-6 S cm-1 which suggests the suitability of the SPE film for rechargeable lithium batteries.

  19. Dielectric function and thermodynamic properties of jellium in the G W approximation

    Science.gov (United States)

    Van Houcke, Kris; Tupitsyn, Igor S.; Mishchenko, Andrey S.; Prokof'ev, Nikolay V.

    2017-05-01

    The fully self-consistent GW approximation is an established method for electronic structure calculations. Its most serious deficiency is known to be an incorrect prediction of the dielectric response. In this work, we examine the GW approximation for the homogeneous electron gas and find that problems with the dielectric response are drastically improved by enforcing the particle-number conservation law in the polarization function. We also find that previously reported data for the ground-state energy contradict each other well outside of reported error bounds. Some of these results created a false impression of how accurate the fully self-consistent GW approximation is. Our two independent implementations of the G W method agree with the data plotted in X.-Z. Yan [Phys. Rev. E 84, 016706 (2011)], 10.1103/PhysRevE.84.016706, thus confirming only that data set. We also present values for other key Fermi-liquid properties.

  20. Laboratory studies of electrical properties of insulating materials. [thermal insulation of spacecraft dielectrics

    Science.gov (United States)

    Nanevicz, J. E.; Adamo, R. C.; Grier, N.

    1978-01-01

    The characteristics of satellites are influenced by the electrical properties of the dielectric exterior. It was found in simulated space environment tests that the electrical conductivities of dielectrics are affected as the result of interactions with various components of the environment. The degree to which the conductivity was affected varied with material. In some instances the changes found to occur could be used to advantage, particularly if they could be enhanced. For example, the increased electrical conductivity of Kapton resulting from solar illumination could be used to advantage to eliminate the charge storage leading to electrical breakdown during magnetic substorms. Similarly the relative immunity of FEP Teflon to change from response to the space environment makes it a logical choice as a solar cell cover in a high-voltage solar array.

  1. Observation of modified radiative properties of cold atoms in vacuum near a dielectric surface

    International Nuclear Information System (INIS)

    Ivanov, V V; Cornelussen, R A; Heuvell, H B van Linden van den; Spreeuw, R J C

    2004-01-01

    We have observed a distance-dependent absorption linewidth of cold 87 Rb atoms close to a dielectric-vacuum interface. This is the first observation of modified radiative properties in vacuum near a dielectric surface. A cloud of cold atoms was created using a magneto-optical trap (MOT) and optical molasses cooling. Evanescent waves (EW) were used to observe the behaviour of the atoms near the surface. We observed an increase of the absorption linewidth by up to 25% with respect to the free-space value. Approximately half the broadening can be explained by cavity quantum electrodynamics (CQED) as an increase of the natural linewidth and inhomogeneous broadening. The remainder we attribute to local Stark shifts near the surface. By varying the characteristic EW length we have observed a distance dependence characteristic for CQED

  2. Thermal and Dielectric Properties of a New Ferroelectric LaBGeO5

    Science.gov (United States)

    Onodera, Akira; Strukov, Boris A.; Belov, Alexander A.; Taraskin, Sergei A.; Haga, Hisashi; Yamashita, Haruyasu; Uesu, Yoshiaki

    1993-12-01

    Thermal and dielectric properties of LaBGeO5, a new ferroelectric with a stillwellite-type structure are investigated. The specific heat, Cp, shows one clear anomaly (\\varDelta S{=}0.114 R) at 802.5 K. The basic thermodynamic parameters are determined on the basis of the Landau theory. However, an additional hump in Cp was found in a different sample just above Tc. This dependence on samples is confirmed by the measurements of dielectric constants. The appearance of the new intermediate phase may be caused by some impurities or defects. The Rhodes-Wohlfarth plot suggests that the nature of the phase transitions is of the displacive-type.

  3. Research Update: Polyimide/CaCu3Ti4O12 nanofiber functional hybrid films with improved dielectric properties

    Directory of Open Access Journals (Sweden)

    Yang Yang

    2013-11-01

    Full Text Available This work reports the excellent dielectric properties of polyimide (PI embedded with CaCu3Ti4O12 (CCTO nanofibers. The dielectric behaviors were investigated over a frequency of 100 Hz–1 MHz. It is shown that embedding CCTO nanofibers with high aspect ratio (67 is an effective means to enhance the dielectric permittivity and reduce the percolation threshold. The dielectric permittivity of PI/CCTO nanofiber composites is 85 with 1.5 vol.% loading of filler, also the dielectric loss is only 0.015 at 100 Hz. Monte Carlo simulation was used to investigate the percolation threshold of CCTO nanofibers reinforced polyimide matrix by using excluded volume theory and soft, hard-core models. The results are in good agreement with the percolation theory and the hard-core model can well explain the percolation phenomena in PI/CCTO nanofiber composites. The dielectric properties of the composites will meet the practical requirements for the application in high dielectric constant capacitors and high energy density materials.

  4. Enhanced dielectric properties of surface hydroxylated bismuth ferrite–Poly (vinylidene fluoride-co-hexafluoropropylene composites for energy storage devices

    Directory of Open Access Journals (Sweden)

    Srikanta Moharana

    2016-12-01

    Full Text Available Dielectric properties of Poly (vinylidene fluoride-co-hexafluoropropylene (PVDF-HFP based composites with surface hydroxylated BiFeO3 (h-BFO particles were prepared by solution casting techniques. The h-BFO fillers were synthesized from BiFeO3 in aqueous solution of H2O2. The result showed that the dielectric properties of the h-BFO-PVDF-HFP composite exhibits better dielectric properties than that of the unmodified BFO-PVDF-HFP composites. Meanwhile, the 30 wt% of h-BFO-PVDF-HFP composite showed higher dielectric constant, better suppressed dielectric loss, high remnant polarization and high electrical conductivity. It is suggested that the strong interaction between h-BFO particles and PVDF-HFP matrix at the interface is the key role in the enhancement of the dielectric properties. It is helpful to understand the influence of surface hydroxylation on the interfaces between the filler and the polymer matrix. The outcome of this study may be exploited in the progress of high energy storage device applications.

  5. Dielectric and thermophysical properties of different beef meat blends over a temperature range of -18 to +10°C.

    Science.gov (United States)

    Farag, K W; Lyng, J G; Morgan, D J; Cronin, D A

    2008-08-01

    Dielectric and thermophysical properties of three different beef meat blends (lean, fat and 50:50 mixture) were evaluated over a range of temperatures from -18 to +10°C. In the region of thawing (-3 to -1°C), dielectric constant (ε') and dielectric loss factor (ε') values for radio frequency (RF) and microwave (MW) were significantly higher (Pthermal conductivity (k), specific heat (c) and thermal diffusivity (α) also showed significant changes (Pfood technologists in the context of rapid defrosting of meat products.

  6. Influence of nanogold additives on phase formation, microstructure and dielectric properties of perovskite BaTiO3 ceramics

    Science.gov (United States)

    Nonkumwong, Jeeranan; Ananta, Supon; Srisombat, Laongnuan

    2015-06-01

    The formation of perovskite phase, microstructure and dielectric properties of nanogold-modified barium titanate (BaTiO3) ceramics was examined as a function of gold nanoparticle contents by employing a combination of X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray, Archimedes principle and dielectric measurement techniques. These ceramics were fabricated from a simple mixed-oxide method. The amount of gold nanoparticles was found to be one of the key factors controlling densification, grain growth and dielectric response in BaTiO3 ceramics. It was found that under suitable amount of nanogold addition (4 mol%), highly dense perovskite BaTiO3 ceramics with homogeneous microstructures of refined grains (~0.5-3.1 μm) and excellence dielectric properties can be produced.

  7. Studies of ferroelectric and dielectric properties of pure and doped barium titanate prepared by sol-gel method

    Energy Technology Data Exchange (ETDEWEB)

    Bisen, Supriya; Mishra, Ashutosh; Jarabana, Kanaka M. [School of Physics, Vigyan Bhawan, Devi Ahilya University, Khandwa Road Indore-452001 (India)

    2016-05-23

    In this work, Barium Titanate (BaTiO{sub 3}) powders were synthesized via Sol-Gel auto combustion method using citric acid as a chelating agent. We study the behavior of ferroelectric and dielectric properties of pure and doped BaTiO{sub 3} on different concentration. To understand the phase and structure of the powder calcined at 900°C were characterized by X-ray Diffraction shows that tetragonal phase is dominant for pure and doped BTO and data fitted by Rietveld Refinement. Electric and Dielectric properties were characterized by P-E Hysteresis and Dielectric measurement. In P-E measurement ferroelectric loop tracer applied for different voltage. The temperature dependant dielectric constant behavior was observed as a function of frequency recorded on hp-Hewlett Packard 4192A, LF impedance, 5Hz-13Hz analyzer.

  8. Dielectric elastomer for stretchable sensors: influence of the design and material properties

    Science.gov (United States)

    Jean-Mistral, C.; Iglesias, S.; Pruvost, S.; Duchet-Rumeau, J.; Chesné, S.

    2016-04-01

    Dielectric elastomers exhibit extended capabilities as flexible sensors for the detection of load distributions, pressure or huge deformations. Tracking the human movements of the fingers or the arms could be useful for the reconstruction of sporting gesture, or to control a human-like robot. Proposing new measurements methods are addressed in a number of publications leading to improving the sensitivity and accuracy of the sensing method. Generally, the associated modelling remains simple (RC or RC transmission line). The material parameters are considered constant or having a negligible effect which can lead to serious reduction of accuracy. Comparisons between measurements and modelling require care and skill, and could be tricky. Thus, we propose here a comprehensive modelling, taking into account the influence of the material properties on the performances of the dielectric elastomer sensor (DES). Various parameters influencing the characteristics of the sensors have been identified: dielectric constant, hyper-elasticity. The variations of these parameters as a function of the strain impact the linearity and sensitivity of the sensor of few percent. The sensitivity of the DES is also evaluated changing geometrical parameters (initial thickness) and its design (rectangular and dog-bone shapes). We discuss the impact of the shape regarding stress. Finally, DES including a silicone elastomer sandwiched between two high conductive stretchable electrodes, were manufactured and investigated. Classic and reliable LCR measurements are detailed. Experimental results validate our numerical model of large strain sensor (>50%).

  9. DIELECTRIC AND PYROELECTRIC PROPERTIES OF THE COMPOSITES OF FERROELECTRIC CERAMIC AND POLY(VINYL CHLORIDE

    Directory of Open Access Journals (Sweden)

    M.Olszowy

    2003-01-01

    Full Text Available The dielectric and pyroelectric properties of lead zirconate titanate/poly(vinyl chloride [PZT/PVC] and barium titanate/poly(vinyl chloride [BaTiO3/ PVC] composites were studied. Flexible composites were fabricated in the thin films form (200-400 μm by hot-pressed method. Powders of PZT or BaTiO3 in the shape of ≤ 75 μm ceramics particles were dispersed in a PVC matrix, providing composites with 0-3} connectivity. Distribution of the ceramic particles in the polymer phase was examined by scanning electron microscopy. The analysis of the thermally stimulated currents (TSC have also been done. The changes of dielectric and pyroelectric data on composites with different contents of ceramics up to 40% volume were investigated. The dielectric constants were measured in the frequency range from 600 Hz to 6 MHz at room temperature. The pyroelectric coefficient for BaTiO3/PVC composite at 343 K is about 35 μC/m2K which is higher than that of β-PVDF (10 μC/m2 K.

  10. Structure and dielectric properties in the radio frequency range of polymer composites based on vanadium dioxide

    Directory of Open Access Journals (Sweden)

    Kolbunov V.R.

    2015-06-01

    Full Text Available Polymer composites with active fillers are recently considered to be promising materials for the design of new functional devices with controllable properties and are intensively investigated. Dielectric studies are one of the most effective methods for studying structural features and mechanisms of conductivity formation for this type of two-component systems. The paper presents research results of the dielectric characteristics in the range of radio frequency of 50 kHz — 10 MHz and temperature range of 30—60°C of polyethylene composites of vanadium dioxide with different volume fractions of filler. Two dispersion areas were found: a high-frequency area caused by the Maxwell charge separation on the boundaries of the polyethylene matrix — conductive filler of VI2 crystallites, and a low frequency area associated with the presence of the transition layer at this boundary. The relative permittivity of the composite has a tendency to a decrease in absolute value with increasing temperature. The analysis of the low-frequency dependence of the dielectric constant of the value of the filler’s volume fraction revealed that the investigated composite belongs to two-component statistical mixtures with a transition layer between the components.

  11. SHI induced modification in structural, optical, dielectric and thermal properties of poly ethylene oxide films

    Energy Technology Data Exchange (ETDEWEB)

    Patel, Gnansagar B.; Bhavsar, Shilpa [Department of Physics, The M.S. University of Baroda, Vadodara 390002 (India); Singh, N.L., E-mail: nl.singh-phy@msubaroda.ac.in [Department of Physics, The M.S. University of Baroda, Vadodara 390002 (India); Singh, F.; Kulriya, P.K. [Inter University Accelerator Centre, Aruna Asaf Ali Marg, New Delhi 110067 (India)

    2016-07-15

    Poly ethylene oxide (PEO) films were synthesized by solution cast method. These self-standing films were exposed with 60 MeV C{sup +5} ion and 100 MeV Ni{sup +7} ion at different fluences. SHI induced effect was investigated by employing various techniques. The crystalline size decreased upon irradiation as observed from XRD analysis. FTIR analysis reveals the decrement in the peak intensity upon irradiation. Tauc’s method was used to determine the optical band gap (E{sub g}), which shows decreasing trends with increase of fluence. The dielectric properties were investigated in the frequency range 10 Hz to 10 MHz for unirradiated and irradiated films. The dielectric constant remains same for the broad-spectrum of frequency and increases at lower frequency. The dielectric loss also moderately influence as a function of frequency due to irradiation. DSC analysis validated the results of XRD. Scanning electron microscopy (SEM) reveals that there is significant change in the surface morphology due to irradiation.

  12. Influence of Sn and Pb Ions Substitutions on Dielectric Properties of Barium Titanate

    Directory of Open Access Journals (Sweden)

    Bąk W.

    2016-06-01

    Full Text Available The results of the microstructural and dielectric measurements of (Ba1-xPbx(Ti1-xSnxO3 (BPTSx (x = 0, 0.05, 0.10, 0.30 polycrystalline samples are presented. The samples were obtained by means of a high temperature synthesis and their expected stoichiometry was confirmed by energy dispersive spectroscopy (EDS measurements. The dielectric properties of BPTSx were studied with the use of broadband dielectric spectroscopy. The measurements over a wide range of temperature (from 140 K to 600 K and frequency (from 0.1 Hz to 10 MHz were performed. The experimental results indicate an influence of Pb ions in a sublattice A and Sn ions in a sublattice B substitution on paraelectric - ferroelectric phase transition parameters. Diffused phase transitions from a paraelectric to ferroelectric state (for x = 0.10 and x = 0.30 were observed. From the electric modulus measurements in the frequency domain the relaxation times and the activation energy were determined.

  13. Effect of gamma radiation on dielectric and mechanical properties of modified fluoroplastic PTFE

    Science.gov (United States)

    Romanov, Boris; Kostromin, Valeriy; Bedenko, Sergey; Knyshev, Vladimir; Mukhnurov, Ilya; Matias, Rodrigo Roman

    2018-03-01

    The influence of gamma radiation on dielectric and mechanical characteristics of modified fluoroplast PTFE-4 MBK is considered in this paper. The material was exposed to Gamma-ray source GU-200 (Joint-stock company «Research Institute of Instruments», Lytkarino, Russia). The results of the research have shown that the relative permittivity and the tangent of the dielectric loss angle of PTFE-4 MBK samples at doses 4.105-1.106 Gy monotonically increase by 2.9 and 9.4%, respectively, compared to un-exposed material. The research of the mechanical properties of PTFE-4 MBK showed a maximum stress of up to 13.8 MPa and a maximum strain of 252% at doses of 8.104 Gy. It has been demonstrated that modified PTFE-4 MBK has good dielectric characteristics and withstanding high mechanical stress. We propose to use the results of the research for choosing cables and wiring location used in nuclear and space industry.

  14. The dielectric properties of neutron irradiated snake venom and its pathological impact

    International Nuclear Information System (INIS)

    Hanafy, M.S.; Rahmy, N.A.; Abd El-Khalek, M.M.

    1999-01-01

    The changes in the dielectric properties of a saline solution of Cerastes cerastes snake venom after irradiation with low-level doses of fast neutrons from a Cf-252 source, were investigated. The pathological changes in the internal organs such as liver, kidney spleen, lung and heart of the rats injected with unirradiated and irradiated venom were also studied. The changes in the molecular structure of a diluted saline solution of snake venom were measured through dielectric relaxation studies in the frequency range 0.1-10 MHz at 4±0.5 deg C. The absorption spectra of the venom solution were measured in the wavelength range 200 to 600 nm. The results indicated remarkable changes in the molecular radii, shape, relaxation time and dielectric increment of the venom molecules as a result of irradiation. Also, the intensities of the absorption bands of the venom solution decreased as a result of the irradiation process. Furthermore, the pathological examination results indicated that the toxicity of the irradiated venom decreased as compared with that of unirradiated venom, hence increasing the chance of repair of the affected organs. (author)

  15. Conduction mechanism and dielectric properties of pure and composite resorcinol formaldehyde aerogels doped with silver

    Science.gov (United States)

    Attia, S. M.; Abdelfatah, M. S.; Mossad, M. M.

    2017-07-01

    Pure and composite Resorcinol-Formaldehyde (RF) aerogel samples were prepared by sol-gel process using KOH as a catalyst and doped with silver nanoparticles at different concentrations (1.2×10-4, 2.4×10-4, 3.6×10-4, and 4.8×10-4 wt.% at catalyst ratio 0.024 wt.%). DC electrical conductivity σdc, AC electrical conductivity σ‧, and the dielectric properties of the prepared samples have been measured at different frequencies and temperatures. The results show that σ‧ increases with increasing frequency. The values of σ‧ range from ˜10-4 Ω-1m-1 to around unity at room temperature. The analysis of the results of σ‧(ω, T) reveals that the large overlapping polaron (OLP) is the most favorable mechanism to describe the conduction mechanism in these samples. The behavior of the dielectric constant with the frequency of these samples is normal, where it decreases with increasing frequency, while the behavior of dielectric loss tangent tanδ exhibits a peaking behavior at relatively higher temperature.

  16. Analysis of Dielectric Properties On Agricultural Waste for Microwave Communication Application

    Directory of Open Access Journals (Sweden)

    Zulkifli Nurul Ain

    2017-01-01

    Full Text Available This paper presents the analysis of dielectric properties of agricultural waste for microwave communication application such as microwave absorber and antenna. The residues products – rice straw, rice husk, banana leaves and sugar cane bagasse were studied in the range between 1-20GHz. Firstly, the 2 types of resins namely Epoxy der 331 and Polyamine clear hardener were mixed with the agricultural waste materials to produce the small size of agricultural waste sample. Then, the sample were measured using PNA network analyzer. The permittivity and tangent loss of different agricultural waste samples have been measured using dielectric probe technique. Besides, other objectives of this paper is to replace the conventional printed circuit board (PCB using FR4, Taconic, and Roger material with the agricultural waste material. Besides that, the different percentage of filer for each agricultural waste materials were also investigated to specify the best material to be used as the substrate board and as the resonant material. the result shows the average of dielectric constants and the average of the tangent loss of agricultural waste materials.

  17. Electromagnetic Properties of Multiphase Dielectrics A Primer on Modeling, Theory and Computation

    CERN Document Server

    Zohdi, Tarek I

    2012-01-01

    Recently, several applications, primarily driven by microtechnology, have emerged where the use of materials with  tailored  electromagnetic  (dielectric) properties are necessary for a successful  overall design.  The ``tailored'' aggregate properties are achieved by combining an easily moldable  base matrix with particles  having dielectric properties that are chosen to deliver (desired) effective properties. In many cases, the analysis of such materials requires the simulation of the macroscopic and microscopic electromagnetic response, as well as its resulting coupled thermal response,  which can be important to determine possible failures in ``hot spots.'' This necessitates   a stress analysis. Furthermore, because, oftentimes, such processes initiate degratory chemical processes, it can be necessary to also include models for these processes as well.   A central  objective of this work is to provide basic models and numerical solution strategies to analyze the coupled response of such mat...

  18. Effect of dielectric medium on the nonclassical properties of nonlinear sphere coherent states

    Directory of Open Access Journals (Sweden)

    E Amooghorban

    2014-04-01

    Full Text Available In order to investigate the effect of a medium with dissipation and dispersion and also the curvature of the physical space on the properties of the incident quantum states, we use the quantization of electromagnetic field based on phenomenological approach to obtain input-output relations between radiations on both sides of dielectric slab. By using these relations the fidelity, the Wigner function, and also the quantum correlation of the outgoing state through dielectric slab are obtained for a situation in which the rightward incident state is a nonlinear coherent state on a sphere and the leftward incident state is a vacuum state. Here, the incident states are considered monochromatic and the modeling of the medium is given by the Lorentz' model. Accordingly, we study nonclassical properties of the output states such as the quantum entanglement. It will be observed that the nonclassical properties of the outgoing states depend strongly on the optical property of the medium and also on the curvature of the physical state.

  19. Mechanical and dielectric properties of epoxy/dicyclopentadiene bisphenol cyanate ester/glass fabric composites

    Directory of Open Access Journals (Sweden)

    2008-02-01

    Full Text Available The impact and flexural strengths of epoxy-dicyclopentadiene bisphenol cyanate ester (EP-DCPDCE hybrid thermoset as well as the interlaminar shear strength (ILSS and flexural strength of the composites consisting of the hybrid thermoset and glass fabric were studied. It is found that the addition of epoxy resin (EP-51 can improve the mechanical properties, particularly, the impact strength of DCPDCE matrix and the ILSS of glass fabric reinforced composites. The improvements of the mechanical properties were obvious when the content of EP-51 is from 15 to 30 wt%. The investigations of the interphase of composites by scanning electron microscope (SEM and dynamic mechanical analysis (DMA confirm the improvement of mechanical properties of the composites. However the addition of EP-51 has negative effects on the thermal and dielectric property of the composites.

  20. A many-particle quantum-kinetic formalism for describing properties of light emitters in frozen dielectrics

    International Nuclear Information System (INIS)

    Gladush, M.G.

    2017-01-01

    A many particle quantum-kinetic formalism is suggested to derive the Maxwell-Bloch-type equations which describe the interaction of quantum emitters with light in a frozen dielectric. It is shown that the quantum-kinetic formalism can meet the concept of local variations of dielectric properties and their influence on the emitter. The definitions of the local response and the effective refractive index in macroscopically homogeneous media are discussed.

  1. EFFECTS OF NEODYMIUM DOPING ON DIELECTRIC AND OPTICAL PROPERTIES OF Ba(1-xNdxTi1.005O3 CERAMICS

    Directory of Open Access Journals (Sweden)

    Zhang W.

    2013-06-01

    Full Text Available This paper investigated the optical properties and dielectric properties of neodymium doped BaTiO3 ceramics prepared by Ba(1-xNdxTi1.005O3 powders synthesized via a hydrothermal method. The effects of Nd3+ ions content on the structure, dielectric properties and optical properties of the ceramics were studied. The structural analysis performed on the X-ray diffractometer shows that the phase compositions of all ceramics are tetragonal phase structure. The red shift of the absorption edge indicates the presence of defect energy levels which was proved by the UV-Vis-NIR diffuse reflection spectra. Dielectric property measurements show that Nd-doped BaTiO3 ceramics possess improved dielectric properties at low Nd3+ contents (x = 0.001 and 0.002, as demonstrated by decreased dependence to frequency for both the dielectric constant and dielectric loss.

  2. Optical and microwave dielectric properties of pulsed laser deposited Na{sub 0.5}Bi{sub 0.5}TiO{sub 3} thin film

    Energy Technology Data Exchange (ETDEWEB)

    Joseph, Andrews; Goud, J. Pundareekam; Raju, K. C. James [School of Physics, University of Hyderabad, Hyderabad, Telangana 500046 (India); Emani, Sivanagi Reddy [Advanced Center of Research in High Energy Materials (ACRHEM), School of Physics, University of Hyderabad, Telangana 500046 (India)

    2016-05-23

    Optical properties of pulsed laser deposited (PLD) sodium bismuth titanate thin films (NBT), are investigated at wavelengths of 190-2500 nm. Microwave dielectric properties were investigated using the Split Post Dielectric Resonator (SPDR) technique. At 10 GHz, the NBT films have a dielectric constant of 205 and loss tangent of 0.0373 at room temperature. The optical spectra analysis reveals that NBT thin films have an optical band gap E{sub g}=3.55 eV and it has a dielectric constant of 3.37 at 1000 nm with dielectric loss of 0.299. Hence, NBT is a promising candidate for photonic device applications.

  3. Review of temperature dependence of thermal properties, dielectric properties, and perfusion of biological tissues at hyperthermic and ablation temperatures.

    Science.gov (United States)

    Rossmanna, Christian; Haemmerich, Dieter

    2014-01-01

    The application of supraphysiological temperatures (>40°C) to biological tissues causes changes at the molecular, cellular, and structural level, with corresponding changes in tissue function and in thermal, mechanical and dielectric tissue properties. This is particularly relevant for image-guided thermal treatments (e.g. hyperthermia and thermal ablation) delivering heat via focused ultrasound (FUS), radiofrequency (RF), microwave (MW), or laser energy; temperature induced changes in tissue properties are of relevance in relation to predicting tissue temperature profile, monitoring during treatment, and evaluation of treatment results. This paper presents a literature survey of temperature dependence of electrical (electrical conductivity, resistivity, permittivity) and thermal tissue properties (thermal conductivity, specific heat, diffusivity). Data of soft tissues (liver, prostate, muscle, kidney, uterus, collagen, myocardium and spleen) for temperatures between 5 to 90°C, and dielectric properties in the frequency range between 460 kHz and 3 GHz are reported. Furthermore, perfusion changes in tumors including carcinomas, sarcomas, rhabdomyosarcoma, adenocarcinoma and ependymoblastoma in response to hyperthmic temperatures up to 46°C are presented. Where appropriate, mathematical models to describe temperature dependence of properties are presented. The presented data is valuable for mathematical models that predict tissue temperature during thermal therapies (e.g. hyperthermia or thermal ablation), as well as for applications related to prediction and monitoring of temperature induced tissue changes.

  4. Study on Structural and Dielectric Properties of Ultra-Low-Fire Integratable Dielectric Film for High-Frequency and Microwave Application

    Science.gov (United States)

    Qu, Sheng; Zhang, Jihua; Wu, Kaituo; Wang, Lei; Chen, Hongwei

    2018-03-01

    In this study, ultra-low-fire ceramic composites of Zn2Te3O8-30 wt.%TiTe3O8 (ZTT) were prepared by a solid-state reaction method. Densified at 600°C, the best microwave dielectric properties at 8.5 GHz were measured with the ɛ r , tan δ, Q × f, and τ f as 25.6, 1.5 × 10-4, 56191 GHz and 1.66 ppm/°C, respectively. Thin films of ultra-low-fire ZTT were prepared by a radio-frequency magnetron sputtering method. ZTT films which deposited on Au/NiCr/SiO2/Si (100) substrates at 200°C showed good adhesion. From ultra-low-fire ceramic to ultra-low-fire ZTT thin films, the latter maintained all the good high-frequency dielectric properties of the former: high dielectric constant ( ɛ r ˜ 25) and low dissipation factor (tan δ < 5×10-3), low leakage current density (˜ 10-9 A/cm2) and ultra low processing temperature. These excellent properties of the ultra-low-fire ZTT thin film make it possible to be integrated in MMIC and be applied in the research of GaN and GaAs MOSFET devices.

  5. 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.

  6. A Comparison of Dielectric Properties of Palm Oil with Mineral and Synthetic Types Insulating Liquid under Temperature Variation

    Directory of Open Access Journals (Sweden)

    Abdul Rajab

    2011-11-01

    Full Text Available Mineral oil is known to have a low biodegradability level and high susceptibility to the fire. These conditions motivate many researchers to look for alternative sources for insulating oil. One of the alternative liquid is palm oil. To verify the suitability of using palm oil as an insulating liquid, it is important to make dielectric properties comparison with the commonly used insulating liquid. This paper presents comparison of temperature effect on dielectric properties of palm oil with mineral type insulating liquid and silicone oil. The measured parameters were breakdown voltage, dissipation factor (tan δ, and dielectric constant. Breakdown voltage measurement was performed in accordance with IEC 156 standard, whereas, the dissipation factor and dielectric constant measurement were conducted based on IEC 60247 standard test methods. The results showed that variations of dielectric properties of palm oil to the temperature change, in general, have the same tendency with those of commonly used insulating liquids i.e. mineral oil and silicone oil. Breakdown voltages and dissipation factors of all tested oils were increased, while their dielectric constants were slightly decreased with the increase of temperature.

  7. A combined diffraction and dielectric properties investigation of Ba3MnNb2O9 complex perovskites

    International Nuclear Information System (INIS)

    Liu Yun; Withers, Ray L.; Whichello, A.P.; Noren, Lasse; Ting, Valeska; Brink, Frank; Fitz Gerald, John D.

    2005-01-01

    A combined synthesis, diffraction and dielectric properties investigation of the dependence (and effect) of Mn 2+ /Nb 5+ ordering in Ba 3 MnNb 2 O 9 (BMN) upon annealing atmosphere and processing conditions has been carried out. Annealing in different atmospheres was not found to significantly alter either nominal stoichiometry or structure type. The obtained structure type (disordered metrically cubic or ordered trigonal) as well as the measured electrical properties (in particular, the dielectric loss) were, however, found to be sensitive to the synthesis route. Samples obtained via solid-state reaction were found to be predominantly of 1:2 Mn 2+ /Nb 5+ ordered, P3-bar m1 trigonal structure type whereas samples obtained via an aqueous solution route were found to be of a Mn 2+ /Nb 5+ 'disordered', metrically cubic structure type. All solid-state synthesized samples showed reasonable dielectric properties. The microwave dielectric constant and dielectric quality factor, Q, at 8GHz of an as-synthesized BMN sample were 38 and 100, respectively. By contrast, the dielectric loss of the metrically cubic, Mn 2+ /Nb 5+ 'disordered' samples obtained via an aqueous solution synthesis process were significantly worse

  8. Massive photon properties in 3D photonic crystals, filled by dielectrics or metals

    International Nuclear Information System (INIS)

    Gorelik, V S

    2009-01-01

    The optical properties of 3D photonic crystals-artificial opals, consisting of monosized silica globules-have been investigated. The volume between globules was filled by various dielectrics or metals. The dispersion law of electromagnetic waves of this type of crystal has been obtained. It was shown that the sign of photonic mass in globular photonic crystals may be positive or negative for different points on dispersion curves. The value of the effective mass of photons depends on the refractive index of the substance infiltrated into the globular photonic crystal.

  9. Dielectric and spectral properties of DMAAS ferroelectric crystals doped with chromium

    Science.gov (United States)

    Kapustianik, V.; Czapla, Z.; Tchukvinskyi, R.; Batiuk, A.; Eliyachevskyy, Yu.; Korchak, Yu.; Rudyk, V.

    2004-01-01

    This paper presents the results of investigations of the dielectric and spectral properties of NH2(CH3)2Al(SO4)2 × 6 H2O crystals doped with chromium. In particular, it is shown that the dopant noticeably changes the temperature of ferroelectric phase transition and corresponding thermal dipole relaxation with a critical slowing-down at Tc1. The Cr3+ ions were used as a convenient probe for investigations of crystalline structure. On the basis of absorption and luminescence spectroscopy and resonance Raman scattering study it has been shown that the metal-hydrate complexes in the investigated crystals possess the considerably distorted octahedral shape. (

  10. Electronic and dielectric properties of vacancy clusters as quantum dot in silicane

    Energy Technology Data Exchange (ETDEWEB)

    Mohan, Brij, E-mail: brijmohanhpu@yahoo.com; Sharma, Munish; Ahluwalia, P. K. [Department of Physics, Himachal Pradesh University, Shimla-171005 (India); Kumar, Ashok [Department of Physics, Panjab University, Chandigarh-160014 (India)

    2015-06-24

    First principal study of electronic and dielectric properties of a silicane nanostructure containing cluster of vacancies as quantum dot (QD) has been investigated within density functional theory (DFT). Electronic band structure and corresponding density of states show the decrease in band gap with increasing size of quantum dot. A band gap of 0.38 eV has been achieved for silicane containing 3QD. Electron energy loss spectra (EEL) function shows additional plasmonic features for QD containing silicane in visible region, which may have potential applications in optoelectronic devices.

  11. Dielectrophoretic manipulation of human chromosomes in microfluidic channels: extracting chromosome dielectric properties

    DEFF Research Database (Denmark)

    Clausen, Casper Hyttel; Dimaki, Maria; Buckley, Sonia

    2011-01-01

    of manipulation combined with a custom designed microfluidic system containing the required electrodes for dielectrophoresis experiments. Our results show that although this system is presently not able to distinguish between the different chromosomes, it can provide average data for the dielectric properties...... of human chromosomes in polyamine buffer. These can then be used to optimize system designs for further characterization and even sorting. The experimental data from the dielectrophoretic manipulation were combined with theoretical calculations to extract a range of values for the permittivity...

  12. Electro-optic and dielectric properties of new binary ferroelectric and antiferroelectric liquid crystalline mixtures

    Czech Academy of Sciences Publication Activity Database

    Fitas, J.; Marzec, M.; Kurp, K.; Żurowska, M.; Tykarska, M.; Bubnov, Alexej

    2017-01-01

    Roč. 44, č. 9 (2017), s. 1468-1476 ISSN 0267-8292 R&D Projects: GA MŠk(CZ) LD14007; GA ČR GA15-02843S Grant - others:EU - ICT(XE) COST Action IC1208 Institutional support: RVO:68378271 Keywords : liquid crystals * ferroelectric and antiferroelectric phase * binary mixture * dielectric spectroscopy * switching time * tilt angle Subject RIV: JJ - Other Materials OBOR OECD: Nano-materials (production and properties) Impact factor: 2.661, year: 2016

  13. Femtosecond laser excitation of dielectric materials: experiments and modeling of optical properties and ablation depths

    DEFF Research Database (Denmark)

    Wædegaard, Kristian Juncher; Frislev, Martin Thomas; Balling, Peter

    2013-01-01

    Modeling of the interaction between a dielec- tric material and ultrashort laser pulses provides the tem- poral evolution of the electronic excitation and the optical properties of the dielectric. Experimentally determined re- flectances and ablation depths for sapphire are compared to the calcul...... to the calculations. A decrease in reflectance at high fluences is observed experimentally, which demonstrates the neces- sity of a temperature-dependent electron scattering rate in the model. The comparison thus provides new constraints on the optical parameters of the model....

  14. Optical properties of mesoporous photonic crystals, filled with dielectrics, ferroelectrics and piezoelectrics

    Directory of Open Access Journals (Sweden)

    V. S. Gorelik

    2017-12-01

    Full Text Available At present, it is very important to create new types of mirrors, nonlinear light frequency transformers and optical filters with controlled optical properties. In this connection, it is of great interest to study photonic crystals. Their dielectric permittivity varies periodically in space with a period permitting Bragg diffraction of light. In this paper, we have investigated the optical properties of mesoporous three-dimensional (3D opal-type and one-dimensional (1D anodic alumina photonic crystals, filled with different dielectrics, ferroelectrics and piezoelectrics. We have compared the optical properties of initial mesoporous photonic crystals and filled with different substances. The possibility of mesoporous photonic crystals using selective narrow-band light filters in Raman scattering experiments and nonlinear mirrors has been analyzed. The electromagnetic field enhancing in the case of exciting light frequency close to the stop band edges has been established. The optical harmonics and subharmonics generation in mesoporous crystals, filled with ferroelectrics and piezoelectrics was proposed.

  15. Effect of Microwave Heating on the Dielectric Properties and Components of Iron-Fortified Milk

    Directory of Open Access Journals (Sweden)

    Xiao-shu Tang

    2017-01-01

    Full Text Available With the iron-fortified milk as research object, this paper makes a research on the influence of iron on the dielectric properties and wave absorption properties and effect of nutritional components, such as casein and whey protein in milk, and thermostability in the process of microwave heating, and rapid heat transfer method in ferrous gluconate–milk and ferrous chloride–milk, respectively. The results show that the iron of ionic form has greater influence to convert microwave to heat energy and the effect of microwave absorption properties was greater for ferrous chloride than for ferrous gluconate at high concentration. The effect of different forms of iron on the composition of milk was different, and the composition of milk systems was more stable by microwave heating, but the rapid heat transfer method is superior in the aim of increasing the nutritional value of milk. The ferrous gluconate–milk system has a better thermal stability than ferrous chloride–milk system. From the aspect of dielectric induction, the paper discovers the response rules of iron and evaluates the microwave thermal safety of the traditional and the iron-fortified products by microwave heating.

  16. Influence of Ni{sup 2+} substitution on the structural, dielectric and magnetic properties of Cu–Cd ferrite nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Hashim, Mohd., E-mail: md.hashim09@gmail.com [Department of Applied Physics, Aligarh Muslim University, Aligarh 202 002 (India); Alimuddin [Department of Applied Physics, Aligarh Muslim University, Aligarh 202 002 (India); Shirsath, Sagar E. [Spin Device Technology Centre, Department of Information Engineering, Shinshu University, Nagano 380-8553 (Japan); Kotnala, R.K. [National Physical Laboratory (CSIR), Dr. K.S. Krishnan Road, New Delhi 110 012 (India); Meena, Sher Singh [Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai 400 085 (India); Kumar, Shalendra [Department of Physics, Pohang University of Science and Technology, Pohang 790 784 (Korea, Republic of); Roy, Aashis [Department of Materials Science, Gulbarga University, Gulbarga 585106, Karnataka (India); Jotania, R.B. [Department of Physics, University School of Sciences, Gujarat University, Ahmedabad 380 009 (India); Bhatt, Pramod [Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai 400 085 (India); Kumar, Ravi [Centre for Material Science Engineering, National Institute of Technology, Hamirpur, HP 171 005 (India)

    2013-10-05

    Highlights: •XRD and IR measurements reveal the formation of Cu–Cd–FeO in spinel phase. •The dielectric response shows decreasing trend while resistivity increases with enhancing the doping ion content. •Temperature dependent magnetization study shows that the magnetization and Curie temperature increases with increase in Ni{sup 2+} substitution. -- Abstract: Nanoparticles with compositions of Cu{sub 0.4−0.5x}Cd{sub 0.2}Ni{sub 0.4+x}Fe{sub 2−0.5x}O{sub 4} (0.0 ⩽ x ⩽ 0.5) were successfully synthesized by a citrate–nitrate sol–gel auto combustion route. The combusted powder was calcinated at four hours in a furnace and then slowly cooled to room temperature. The analysis methods of FTIR, XRD, FESEM, VSM and dielectric measurements were used to characterize prepared magnetic particles. The effect of Ni{sup 2+} substitution on structural, magnetic and dielectric properties of Cu–Cd ferrite nanoparticles was studied. The comprehensive studies on compositional and frequency dependent dielectric properties were carried out by means of AC conductivity (σ{sub ac}), imaginary dielectric constant (ε′′), loss tangent (tan δ), impedance and dielectric modulus (real and imaginary) measurements in frequency range of 50 Hz–5 MHz at room temperature. The structural properties investigated by using X-ray diffraction, scanning electron microscopy, and Fourier transform infrared spectroscopy. X-ray diffraction pattern and FTIR results revealed that synthesized samples are in single phase. It is observed that the dielectric constant (ε′′) and dielectric loss (tan δ) value decreases with increase in Ni{sup 2+} concentration (x). At low frequency the Maxwell type interfacial polarization was observed. Magnetization measurement shows that the Curie temperature of the samples increases with Ni{sup 2+} concentration, which is explained by a change in the A–O–B super exchange interaction.

  17. 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.

  18. 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

  19. 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.

  20. Nonlinear Dielectric Properties of Yeast Cells Cultured in Different Environmental Conditions

    Science.gov (United States)

    Kawanishi, Gomon; Fukuda, Naoki; Muraji, Masafumi

    The harmonics of the electric current through yeast suspensions, the nonlinear dielectric properties of yeast cells, have particular patterns according to the biological activity of the cells and the measurement of these patterns is a technique for determining the activity of living cells. The concentration of glucose and oxygen in yeast culture medium influences the manifestation of fermentation or respiration of yeast cells. Measurements were made with yeast cells (Saccharomyces cerevisiae) cultured aerobically and anaerobically in sufficient glucose concentration, aerobic fermentation and anaerobic fermentation, and aerobically in limited glucose concentration, respiration. The results showed that the harmonics were barely apparent for yeast cells in aerobic fermentation and respiratory; however, cells in the anaerobic fermentation displayed substantial third and fifth harmonics. We can say that environmental condition affects the yeast cells' nonlinear properties, from another viewpoint, the measurements of the nonlinear properties are available to determine the activity of yeast cells adjusted to the conditions of their cultivation.

  1. Magneto-thermal and dielectric properties of biferroic YCrO3 prepared by combustion synthesis

    International Nuclear Information System (INIS)

    Duran, A.; Arevalo-Lopez, A.M.; Castillo-Martinez, E.; Garcia-Guaderrama, M.; Moran, E.; Cruz, M.P.; Fernandez, F.; Alario-Franco, M.A.

    2010-01-01

    Microstructural, magnetothermal and dielectric properties of YCrO 3 powders prepared by combustion and solid state methods have been studied by a combination of XRD, specific heat, magnetization and permittivity measurements. The TEM and XRD characterization confirm that the combustion powders are amorphous plate-like agglomerates of nano-sized crystalline particles. A more uniform grain size along with an increase of the relative density is observed by SEM in the sintered samples prepared by combustion route with respect to those produced by solid state reaction. Similar to the material obtained through solid state synthesis, the material prepared by the combustion method also shows spin canted antiferromagnetic ordering of Cr +3 (S=3/2) at ∼140 K, which is shown by magnetization as well as λ-type anomaly in the total specific heat. Furthermore, the magnetic contribution to the total specific heat reveals spin fluctuations above T N and a spin reorientation transition at about 60 K. Both YCrO 3 compounds show a diffuse phase transition at about 450 K, typical of a relaxor ferroelectric, which is characterized by a broad peak in the real part of the dielectric permittivity as a function of temperature, with the peak decreasing in magnitude and shifting to higher temperature as the frequency increases. The relaxor dipoles are due to the local non-centrosymmetric structure. Furthermore, the high loss tangent in a broad range of temperature as well as conductivity analysis indicates a hopping mechanism for the electronic conductivity as we believe it is a consequence of the outer d 3 -shell, which have detrimental effects on the polarization and the pooling process in the YCrO 3 bulk material. The more uniform particle size and higher density material synthesized through the combustion process leads to an improvement in the dielectric Properties. - Graphical abstract: Combustion method: An alternative route for synthesized a new family of multiferroics. Amorphous

  2. Structural, electrical properties and dielectric relaxations in Na+-ion-conducting solid polymer electrolyte

    Science.gov (United States)

    Arya, Anil; Sharma, A. L.

    2018-04-01

    In this paper, we have studied the structural, microstructural, electrical, dielectric properties and ion dynamics of a sodium-ion-conducting solid polymer electrolyte film comprising PEO8-NaPF6+  x wt. % succinonitrile. The structural and surface morphology properties have been investigated, respectively using x-ray diffraction and field emission scanning electron microscopy. The complex formation was examined using Fourier transform infrared spectroscopy, and the fraction of free anions/ion pairs obtained via deconvolution. The complex dielectric permittivity and loss tangent has been analyzed across the whole frequency window, and enables us to estimate the DC conductivity, dielectric strength, double layer capacitance and relaxation time. The presence of relaxing dipoles was determined by the addition of succinonitrile (wt./wt.) and the peak shift towards high frequency indicates the decrease of relaxation time. Further, relations among various relaxation times ({{τ }{{\\varepsilon \\prime}}}>~{{τ }tanδ }>{{τ }z}>{{τ }m} ) have been elucidated. The complex conductivity has been examined across the whole frequency window; it obeys the Universal Power Law, and displays strong dependency on succinonitrile content. The sigma representation ({{σ }\\prime\\prime}~versus~{{σ }\\prime} ) was introduced in order to explore the ion dynamics by highlighting the dispersion region in the Cole–Cole plot ({{\\varepsilon }\\prime\\prime}~versus~{{\\varepsilon }\\prime} ) in the lower frequency window; increase in the semicircle radius indicates a decrease of relaxation time. This observation is accompanied by enhancement in ionic conductivity and faster ion transport. A convincing, logical scheme to justify the experimental data has been proposed.

  3. The electrical and dielectric properties of the Au/Ti/HfO2/n-GaAs structures

    Science.gov (United States)

    Karabulut, Abdulkerim; Türüt, Abdulmecit; Karataş, Şükrü

    2018-04-01

    In this work, temperature dependent electrical and dielectric properties of the Au/Ti/HfO2/n-GaAs structures were investigated using capacitance-voltage (C-V) and conductance-voltage (G-V) measurements in the temperature range of 60-320 K by steps of 20 K at 1 MHz. The dielectric constant (ε‧), dielectric loss (ε″), dielectric loss tangent (tanδ) and ac electrical conductivities (σac) have been calculated as a function of temperature. These values of the ε‧, ε″, tanδ and σac have been found to be 2.272, 5.981, 2.631 and 3.32 × 10-6 (Ω-1cm-1) at 80 K, respectively, 1.779, 2.315, 1.301 and 1.28 × 10-6 (Ω-1cm-1), respectively at 320 K. These decrease of the dielectric parameters (ε‧, ε″, tanδ and σac) have been observed at high temperatures. The experimental results show that electrical and dielectric properties are strongly temperature and bias voltage dependent.

  4. Effect of cation disorder on structural, magnetic and dielectric properties of La2MnCoO6 double perovskite.

    Science.gov (United States)

    Barón-González, A J; Frontera, C; García-Muñoz, J L; Rivas-Murias, B; Blasco, J

    2011-12-14

    The origin of dielectric anomalies and magnetodielectric response of La(2)MnCoO(6) has been investigated by means of ultra-high resolution synchrotron x-ray powder diffraction, neutron powder diffraction, resistivity, magnetization and dielectric measurements. The study has been performed on two different bulk samples presenting different degrees of Mn/Co order: 95 and 74%. Beside the well-known influence on magnetic properties, our results show that the main effect of disorder lies on the electrical resistivity. Bond distances clearly show Mn(4+)/Co(2+) valence states in the well-ordered sample, while for the disordered one this picture still holds. AC resistivity data show dielectric anomalies and a small magnetodielectric effect, but impedance complex plane analyses prove that these phenomena appear at the frequency-temperature region where extrinsic effects dominate the dielectric response. © 2011 IOP Publishing Ltd

  5. Effect of cation disorder on structural, magnetic and dielectric properties of La2MnCoO6 double perovskite

    International Nuclear Information System (INIS)

    Barón-González, A J; Frontera, C; García-Muñoz, J L; Rivas-Murias, B; Blasco, J

    2011-01-01

    The origin of dielectric anomalies and magnetodielectric response of La 2 MnCoO 6 has been investigated by means of ultra-high resolution synchrotron x-ray powder diffraction, neutron powder diffraction, resistivity, magnetization and dielectric measurements. The study has been performed on two different bulk samples presenting different degrees of Mn/Co order: 95 and 74%. Beside the well-known influence on magnetic properties, our results show that the main effect of disorder lies on the electrical resistivity. Bond distances clearly show Mn 4+ /Co 2+ valence states in the well-ordered sample, while for the disordered one this picture still holds. AC resistivity data show dielectric anomalies and a small magnetodielectric effect, but impedance complex plane analyses prove that these phenomena appear at the frequency-temperature region where extrinsic effects dominate the dielectric response. (paper)

  6. Electrical and dielectric properties of TiO2 and Fe2O3 doped fly ash

    Indian Academy of Sciences (India)

    Scanning electron microscopy (SEM); X-ray diffraction (XRD); FTIR; electrical properties; dielectric properties. 1. Introduction. Coal-based thermal power plants are necessary for the increased generation of electricity. The end product of coal from power plants are fly ash. The accumulated fly ash is a matter of great concern ...

  7. Thermal stability and dielectric properties of nano-SiO2-doped cellulose

    Science.gov (United States)

    Zhang, Song; Tang, Chao; Hao, Jian; Wang, Xiaobo

    2017-07-01

    We report the thermal stability and dielectric properties of nano-SiO2-doped cellulose. Molecular dynamics simulations were performed using an undoped cellulose model (C0), a nano-SiO2-doped cellulose model with untreated surface unsaturated bonds (C1), and a nano-SiO2-doped cellulose model for which surface unsaturated O atoms were treated with -H and surface unsaturated Si atoms were treated with -OH (C2). The simulation results showed that the mechanical properties of C1 and C2 were better than those of C0 and were optimal when the content of nano-SiO2 was 5%. The simulation results for C2 were more accurate than those for the other models, and thus, C2 provides theoretical support for the construction of a reasonable model of nano-SiO2 and cellulose in the future. The temperature at which the free volume fraction of C2 jumps was 50 K higher than that for C0, and the thermal stability of C2 was better than that of C0. Experimental results showed that the maximum tensile strength of the insulation paper was obtained when the content of nano-SiO2 was 5%. Moreover, at this content of nano-SiO2, the dielectric constant was lowest and closest to that of transformer insulation oil, which will improve the distribution of the electric field and thus the overall breakdown performance of oil-paper insulation systems.

  8. A hybrid waveguide cell for the dielectric properties of reservoir rocks

    International Nuclear Information System (INIS)

    Siggins, A F; Gunning, J; Josh, M

    2011-01-01

    A hybrid waveguide cell is described for broad-band measurements of the dielectric properties of hydrocarbon reservoir rocks. The cell is designed to operate in the radio frequency range of 1 MHz to 1 GHz. The waveguide consists of 50 Ω coaxial lines feeding into a central cylindrical section which contains the sample under test. The central portion of the waveguide acts as a circular waveguide and can accept solid core plugs of 38 mm diameter and lengths from 2 to 150 mm. The central section can also be used as a conventional coaxial waveguide when a central electrode with spring-loaded end collets is installed. In the latter mode the test samples are required to be in the form of hollow cylinders. An additional feature of the cell is that the central section is designed to telescope over a limited range of 1–2 mm with the application of an axial load. Effective pressures up to 35 MPa can be applied to the sample under the condition of uniaxial strain. The theoretical basis of the hybrid waveguide cell is discussed together with calibration results. Two reservoir rocks, a Donnybrook sandstone and a kaolin rich clay, are then tested in the cell, both as hollow cylinders in coaxial mode and in the form of solid core plugs. The complex dielectric properties of the two materials over the bandwidth of 1 MHz to 1 GHz are compared with the results of the two testing methods

  9. Structural and Interfacial Effects on the Dielectric Properties of PVDF and its Composites for Energy Storage

    Science.gov (United States)

    Jones, Jennifer; Mayo, Anthony; Zhu, Lei; Tolk, Norman; Mu, Richard

    2014-03-01

    High energy density capacitors based on dielectric polymers are a focus of increasing research effort motivated by the possibility to realize compact and flexible energy storage devices. Multilayered ferroelectric polyvinylidene fluoride (PVDF) systems are fabricated using enabling technology in co-extrusion for increased energy storage efficiency. These micro- and nano-layered polymeric systems result in much improved device performance and a three-time enhancement of capacitive electrical energy density has been demonstrated. PVDF thin film nanocomposites with ZnO nanofillers have also been fabricated and evaluated for further enhancement of energy density storage. To understand the physics of why these multilayered and nanocomposite systems perform better than single layer PVDF we are developing characterization techniques using confocal second harmonic generation (SHG), electric field induced second harmonic (EFISH) and Raman laser spectroscopy. Our results have shown that the combination of Raman and SHG is a very sensitive, non-destructive and versatile technique that can be used to study the ferroelectric and structural properties of these systems. The addition of the EFISH technique allows the interrogation of structural and dielectric properties within individual layers and at the interfaces.

  10. Effects of Ti doping on the dielectric properties of HfO2 nanoparticles

    Science.gov (United States)

    Pokhriyal, S.; Biswas, S.

    2016-05-01

    We report the effects of Ti doping on the dielectric properties of HfO2 [Hf1-xTixO2 (x = 0.2-0.8)] nanoparticles at room temperature. The Hf1-xTixO2 nanoparticles were synthesized by a wet chemical process. The structural and morphological properties of the derived samples were analyzed with X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and high resolution transmission electron microscopy (HRTEM). Impedance analysis was performed in pelletized samples in the frequency range of 1 MHz to 1 GHz. The obtained results were analyzed in correlation with microstructure and doping concentration in the derived samples. The average size of the Hf1-xTixO2 nanoparticles is typically in the range of 4-8 nm depending on the processing temperature. The Hf1-xTixO2 nanoparticles show reduction in crystallinity with the increase in Ti doping. The dielectric constants of the derived samples decrease with the increase in frequency. The ac-conductivity in the samples increases with the increase in frequency irrespective of Ti concentration and shows significant drop with the increase in Ti concentration at all frequencies.

  11. Microwave-assisted sintering of non-stoichiometric strontium bismuth niobate ceramic: Structural and dielectric properties

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Rajveer [Department of Physics and Astrophysics, University of Delhi, New Delhi 110007 (India); Department of Physics, Atmaram Sanatan Dharma College, University of Delhi, Dhaula Kuan, New Delhi 110021 (India); Luthra, Vandna [Department of Physics, Gargi College, University of Delhi, Siri Fort Road, New Delhi 110049 (India); Tandon, R.P., E-mail: ram_tandon@hotmail.com [Department of Physics and Astrophysics, University of Delhi, New Delhi 110007 (India)

    2016-11-01

    In recent years the microwave sintering has been utilized for the synthesis of materials in enhancement of the properties. In this paper strontium bismuth niobate (Sr{sub 0.8}Bi{sub 2.2}Nb{sub 2}O{sub 9}:SBN) bulk ceramic has been synthesized by microwave reactive sintering and conventional heating techniques. A relative density of 99.6% has been achieved for microwave sintered SBN, which is higher than that of (98.81%) conventionally sintered SBN. The phase formation of SBN synthesized by both processes has been confirmed by X-ray diffraction (XRD). The surface morphology of SBN was observed by scanning electron microscopy (SEM). The microstructure was found to be more uniform in case of SBN sintered by microwave sintering. The dielectric properties of SBN were studied as a function of frequency in the temperature range of 30–500 °C. Both the samples synthesized by two different processes were found to follow Curie–Weiss law above the transition temperature. The Curie temperature was found to be higher for microwave sintered SBN. The dielectric constant and the transition temperature were observed to be higher for SBN ceramic synthesized by microwave sintering technique. The ac and dc activation energy values were also found to be higher for microwave sintered SBN as compared to conventional sintering technique.

  12. In-plane microwave dielectric properties of paraelectric barium strontium titanate thin films with anisotropic epitaxy

    Science.gov (United States)

    Simon, W. K.; Akdogan, E. K.; Safari, A.; Bellotti, J. A.

    2005-08-01

    In-plane dielectric properties of ⟨110⟩ oriented epitaxial (Ba0.60Sr0.40)TiO3 thin films in the thickness range from 25-1200nm have been investigated under the influence of anisotropic epitaxial strains from ⟨100⟩ NdGaO3 substrates. The measured dielectric properties show strong residual strain and in-plane directional dependence. Below 150nm film thickness, there appears to be a phase transition due to the anisotropic nature of the misfit strain relaxation. In-plane relative permittivity is found to vary from as much as 500-150 along [11¯0] and [001] respectively, in 600nm thick films, and from 75 to 500 overall. Tunability was found to vary from as much as 54% to 20% in all films and directions, and in a given film the best tunability is observed along the compressed axis in a mixed strain state, 54% along [11¯0] in the 600nm film for example.

  13. 160 MeV Ni12+ ion irradiation effects on the dielectric properties of polyaniline nanotubes

    International Nuclear Information System (INIS)

    Hazarika, J.; Nath, Chandrani; Kumar, A.

    2012-01-01

    We report on the dielectric properties and a.c. conductivity studies of CSA doped polyaniline nanotubes. Nanotubes of 47–100 nm diameter, were synthesized by the self-assembly method and irradiated using Ni 12+ ions of 160 MeV energy with fluences of 1 × 10 10 , 5 × 10 10 , 1 × 10 11 and 3 × 10 11 ions/cm 2 . X-ray diffraction studies reveal an increase in the degree of crystallinity and consequently, the extent of order of the nanotubes with increasing fluence, but show a lower degree of crystallinity at higher fluence. The decrease in d-spacing for the (100) reflections with fluence is ascribed to the decrease in the tilt angle of the aligned polymer chains. A significant change was seen after irradiation in dielectric and electrical properties which may be correlated with the increased carrier concentration and structural modifications in the polymer films. The surface conductivity of films increases with increasing fluence, which also decreases at higher fluence. The a.c. conduction mechanism for the nanotubes could be explained in terms of correlated barrier hopping model. The existence of polarons as the major charge carriers in the present nanotube system was confirmed by the low values of polaron binding energy, found to decrease with fluence. The hopping distance increases with fluence indicating that the hopping probability increases with fluence.

  14. Synthesis and characterization of multiferroic Sm-doped BiFeO{sub 3} nanopowders and their bulk dielectric properties

    Energy Technology Data Exchange (ETDEWEB)

    Yotburut, Benjaporn [School of Physics, Institute of Science, Suranaree University of Technology, Nakhon Ratchasima 30000 (Thailand); Thongbai, Prasit [Department of Physics, Faculty of Science, Khon Kaen University, Khon Kaen 40002 (Thailand); Yamwong, Teerapon [National Metals and Materials Technology Center (MTEC), Thailand Science Park, Pathumthani 12120 (Thailand); Maensiri, Santi, E-mail: santimaensiri@g.sut.ac.th [School of Physics, Institute of Science, Suranaree University of Technology, Nakhon Ratchasima 30000 (Thailand); SUT Center of Excellence on Advanced Functional Materials, Suranaree University of Technology, Nakhon Ratchasima 30000 (Thailand)

    2017-09-01

    Highlights: • Bi{sub 1−x}Sm{sub x}FeO{sub 3} nanopowders were prepared by a simple co-precipitation method. • The prepared samples were well characterized by XRD, TEM, SEM, and XAS. • The XANES spectra identified the valence state of Fe ion in all nanopowders as 3+. • Increasing in applied dc bias voltage from 0 to 20 V causes a decrease in the dielectric constant. • The relaxation activation energy of a LFR is larger than that of a HFR. - Abstract: Multiferroic Bi{sub 1−x}Sm{sub x}FeO{sub 3} (x = 0, 0.05, 0.1, 0.2, and 0.3) nanopowders with particle sizes of 69–22.6 nm were prepared by a simple co-precipitation method. The structure and morphology of the samples were examined using X-ray diffraction (XRD) and scanning electron microscopy (SEM). The XRD patterns confirmed the phase transition from rhombohedral to orthorhombic phases. The results of X-ray absorption spectroscopy (XAS) data indicate that the oxidation state of Fe in the sample was Fe{sup 3+}. The results of magnetic properties revealed the enhancement of weak ferromagnetic property with increasing Sm doping in BFO nanopowders. SEM images revealed that the average grain size decreased with an increase in Sm concentration. Undoped BFO ceramics exhibited a high dielectric constant ε′ ∼1.1 × 10{sup 4} and a low loss tangent of tan δ ∼0.5 at room temperature for 1 kHz. The room temperature dielectric constant decreased with increasing concentration of Sm doping and the dielectric relaxation peaks were observed at x ≤ 0.1. The dielectric relaxation peaks which were observed at all frequency ranges were x ≤ 0.1 samples which were attributed to Maxwell-Wagner relaxation. As the temperature increased, great increases in dielectric permittivity were observed in all the Bi{sub 1−x}Sm{sub x}FeO{sub 3} samples. The effects of grain boundaries on the dielectric properties of Sm-doped BFO ceramics were investigated by measuring the dielectric responds in the frequencies of 100 Hz–1

  15. The effect of compaction parameters and dielectric composition on properties of soft magnetic composites

    International Nuclear Information System (INIS)

    Xiao Ling; Yu Lie; Sun, Y H

    2011-01-01

    This paper investigated the effect of compaction parameters and dielectric composition on mechanical, magnetic and electrical properties of iron-organosilicon epoxy resin soft magnetic composites. In this work, iron powders with high purity were covered by an organic material (organosilicon epoxy resin) and then by coupling agent (KH-550). The coated powders were then cold compacted at 600, 800 and 1000 MPa and cured under vacuum respectively. The results show that the saturation magnetic flux density and electrical resistivity are dependent on compaction pressure and resin content. Increase in the organic phase content leads to decrease of the saturation magnetic flux density, while increase of the electrical resistivity. Furthermore, the samples with 0.9 wt% resins + 0.1 wt% coupling agent at compaction pressure of 800 MPa shows better properties than the others.

  16. The optical properties of transferred graphene and the dielectrics grown on it obtained by ellipsometry

    Science.gov (United States)

    Kasikov, Aarne; Kahro, Tauno; Matisen, Leonard; Kodu, Margus; Tarre, Aivar; Seemen, Helina; Alles, Harry

    2018-04-01

    Graphene layers grown by chemical vapour deposition (CVD) method and transferred from Cu-foils to the oxidized Si-substrates were investigated by spectroscopic ellipsometry (SE), Raman and X-Ray Photoelectron Spectroscopy (XPS) methods. The optical properties of transferred CVD graphene layers do not always correspond to the ones of the exfoliated graphene due to the contamination from the chemicals used in the transfer process. However, the real thickness and the mean properties of the transferred CVD graphene layers can be found using ellipsometry if a real thickness of the SiO2 layer is taken into account. The pulsed laser deposition (PLD) and atomic layer deposition (ALD) methods were used to grow dielectric layers on the transferred graphene and the obtained structures were characterized using optical methods. The approach demonstrated in this work could be useful for the characterization of various materials grown on graphene.

  17. Preparation and dielectric property of Ag-PVA nano-composite

    International Nuclear Information System (INIS)

    Feng Qunqiang; Dang Zhimin; Li Na; Cao Xiaolong

    2003-01-01

    The property of nano-powder was reviewed with emphasis on its Coulomb blockade effects. Ag-colloid of different concentration with different particle size was prepared. Ag-PVA composite colloid was obtained by mixing Ag-colloid with PVA solution. TEM showed that Ag particles (<100 nm) were uniformly dispersed in PVA. The resistivity at room and low temperatures and breakdown field strength of samples were investigated. The results show that dielectric properties of composite change while Ag content or distributing state changes. The composite with 20-30 nm Ag particles has a higher resistivity and breakdown field than its matrix. In a word, Coulomb blockade effects of metal powders could improve resistivity and breakdown field of its matrix

  18. Atomic-scale microstructures, Raman spectra and dielectric properties of cubic pyrochlore-typed Bi1.5MgNb1.5O7 dielectric ceramics

    KAUST Repository

    Li, Yangyang

    2014-07-01

    Single-phase cubic pyrochlore-typed Bi1.5MgNb 1.5O7 (BMN) dielectric ceramics were synthesized at temperatures of 1050-1200 °C by solid-state reaction method. Their atomic-scale microstructures and dielectric properties were investigated. X-ray diffraction patterns revealed that the BMN ceramics had an average cubic pyrochlore structure, whereas the Raman spectra indicated that they had an essentially cubic symmetry with small local deviations at the A and O\\' sites of the cubic pyrochlore structure. This was confirmed by selected electron area diffraction (SAED) patterns, where the reflections of {442} (not allowed in the cubic pyrochlore with Fd3̄m symmetry) were clearly observed. SEM and TEM images revealed that the average grain size was increased with the sintering temperature, and an un-homogeneous grain growth was observed at high temperatures. HRTEM images and SAED patterns revealed the single-crystalline nature of the BMN ceramic grains. Energy dispersive spectroscopy (EDS) elemental mapping studies indicated that the compositional distributions of Bi, Mg, Nb and O elements in the ceramic grains were homogenous, and no elemental precipitation was observed at the grain boundary. Quantitative EDS data on ceramic grains revealed the expected cationic stoichiometry based on the initial composition of Bi1.5MgNb1.5O7. Dielectric constants of all the BMN samples exhibited almost frequency independent characteristic in the frequency range of 102-106 Hz, and the highest value was 195 for the BMN ceramics sintered at sintered at 1150 °C with the highest bulk density. The dielectric losses were stable and less than 0.002 in the frequency range of 102-105 Hz. The high dielectric constants of the present BMN samples can be ascribed to the local atomic deviations at the A and O\\' sites from the ideal atomic positions of the pyrochlore structure, which affect the different polarization mechanisms in the BMN ceramics, and which in turn enhance the dielectric

  19. Electronic transport and dielectric properties of low-dimensional structures of layered transition metal dichalcogenides

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Ashok, E-mail: ashok.1777@yahoo.com; Ahluwalia, P.K., E-mail: pk_ahluwalia7@yahoo.com

    2014-02-25

    Graphical abstract: We present electronic transport and dielectric response of layered transition metal dichalcogenides nanowires and nanoribbons. Illustration 1: Conductance (G) and corresponding local density of states(LDOS) for LTMDs wires at applied bias. I–V characterstics are shown in lowermost panels. Highlights: • The studied configurations show metallic/semiconducting nature. • States around the Fermi energy are mainly contributed by the d orbitals of metal atoms. • The studied configurations show non-linear current–voltage (I–V) characteristics. • Additional plasmonic features at low energy have been observed for both wires and ribbons. • Dielectric functions for both wires and ribbons are anisotropic (isotropic) at low (high) energy range. -- Abstract: We present first principle study of the electronic transport and dielectric properties of nanowires and nanoribbons of layered transition metal dichalcogenides (LTMDs), MX{sub 2} (M = Mo, W; X = S, Se, Te). The studied configuration shows metallic/semiconducting nature and the states around the Fermi energy are mainly contributed by the d orbitals of metal atoms. Zero-bias transmission show 1G{sub 0} conductance for the ribbons of MoS{sub 2} and WS{sub 2}; 2G{sub 0} conductance for MoS{sub 2}, WS{sub 2}, WSe{sub 2} wires, and ribbons of MoTe{sub 2} and WTe{sub 2}; and 3G{sub 0} conductance for WSe{sub 2} ribbon. The studied configurations show non-linear current–voltage (I–V) characteristics. Negative differential conductance (NDC) has also been observed for the nanoribbons of the selenides and tellurides of both Mo and W. Furthermore, additional plasmonic features below 5 eV energy have been observed for both wires and ribbons as compared to the corresponding monolayers, which is found to be red-shifted on going from nanowires to nanoribbons.

  20. Magnetic and dielectric properties of Fe3BO6 nanoplates prepared through self-combustion method

    Science.gov (United States)

    Kumari, Kalpana

    In the present investigation, a facile synthesis method is explored involving a self-combustion of a solid precursor mixture of iron oxide Fe2O3 and boric acid (H3BO3) using camphor (C10H16O) as fuel in ambient air in order to form a single phase Fe3BO6 crystallites. X-ray diffraction (XRD), Field emission electron microscopy (FESEM), magnetic, and dielectric properties of as prepared sample are studied. From XRD pattern, a single phase compound is observed with an orthorhombic crystal structure (Pnma space group), with average crystallite size of 42nm. A reasonably uniform size distribution of the plates and self-assemblies is retained in the sample. A magnetic transition is observed in dielectric permittivity (at ˜445K) and power loss (at ˜435K) when plotted against temperature. A weak peak occurs near 330K due to the charge reordering in the sample. For temperatures above the transition temperature, a sharp increase of the dielectric loss is observed which occurs due to the presence of thermally activated charge carriers. A canted antiferromagnetic Fe3+ ordering in a Fe3BO6 lattice with a localized charge surface layer is an apparent source of exhibiting a ferroelectric feature in this unique example of a centrosymmetric compound. An induced spin current over the Fe sites thus could give rise to a polarization hysteresis loop. Due to the presence of both ferromagnetic as well as polarization ordering, Fe3BO6 behaves like a single phase multiferroic ceramics.

  1. Effect of Nb doping on sintering and dielectric properties of PZT ceramics

    Directory of Open Access Journals (Sweden)

    Ali Mirzaei

    2016-09-01

    Full Text Available The extensive use of piezoelectric ceramics such as lead zirconate titanate (PZT in different applications became possible with the development of donor or acceptor dopants. Therefore, studies on the effect of dopants on the properties of PZT ceramics are highly demanded. In this study undoped and 2.4 mol% Nb-doped PZT (PZTN powders were successfully obtained by a solid-state reaction and calcination at 850 °C for 2 h. Crystallinity and phase formation of the prepared powders were studied using X-ray diffraction (XRD. In order to study morphology of powders, scanning electron microscopy (SEM was performed. The crystalline PZT and Nb-doped PZT powders were pelleted into discs and sintered at 1100, 1150 and 1200 °C, with a heating rate of 10 °C/min, and holding time of 1–6 h to find the optimum combination of temperature and time to produce high density ceramics. Microstructural characterization was conducted on the fractured ceramic surfaces using SEM. Density measurements showed that maximal density of 95% of the theoretical density was achieved after sintering of PZT and PZTN ceramics at 1200 °C for 2 h and 4 h, respectively. However, the results of dielectric measurements showed that PZTN ceramics have higher relative permittivity (εr ∼17960 with lower Curie temperature (∼358 °C relative to PZT (εr = 16000 at ∼363 °C as a result of fine PZTN structure as well as presence of vacancies. In addition, dielectric loss (at 1 kHz of PZT and PZTN ceramics with 95% theoretical density was 0.0087 and 0.02, respectively. The higher dielectric loss in PZTN was due to easier domain wall motions in PZTN ceramics.

  2. Magnetic and dielectric properties of Fe3BO6 nanoplates prepared through self-combustion method

    Directory of Open Access Journals (Sweden)

    Kalpana Kumari

    2017-12-01

    Full Text Available In the present investigation, a facile synthesis method is explored involving a self-combustion of a solid precursor mixture of iron oxide Fe2O3 and boric acid (H3BO3 using camphor (C10H16O as fuel in ambient air in order to form a single phase Fe3BO6 crystallites. X-ray diffraction (XRD, Field emission electron microscopy (FESEM, magnetic, and dielectric properties of as prepared sample are studied. From XRD pattern, a single phase compound is observed with an orthorhombic crystal structure (Pnma space group, with average crystallite size of 42nm. A reasonably uniform size distribution of the plates and self-assemblies is retained in the sample. A magnetic transition is observed in dielectric permittivity (at ∼445K and power loss (at ∼435K when plotted against temperature. A weak peak occurs near 330K due to the charge reordering in the sample. For temperatures above the transition temperature, a sharp increase of the dielectric loss is observed which occurs due to the presence of thermally activated charge carriers. A canted antiferromagnetic Fe3+ ordering in a Fe3BO6 lattice with a localized charge surface layer is an apparent source of exhibiting a ferroelectric feature in this unique example of a centrosymmetric compound. An induced spin current over the Fe sites thus could give rise to a polarization hysteresis loop. Due to the presence of both ferromagnetic as well as polarization ordering, Fe3BO6 behaves like a single phase multiferroic ceramics.

  3. Enhanced dielectric properties of poly(vinylidene fluoride) composites filled with nano iron oxide-deposited barium titanate hybrid particles.

    Science.gov (United States)

    Zhang, Changhai; Chi, Qingguo; Dong, Jiufeng; Cui, Yang; Wang, Xuan; Liu, Lizhu; Lei, Qingquan

    2016-09-16

    We report enhancement of the dielectric permittivity of poly(vinylidene fluoride) (PVDF) generated by depositing magnetic iron oxide (Fe3O4) nanoparticles on the surface of barium titanate (BT) to fabricate BT-Fe3O4/PVDF composites. This process introduced an external magnetic field and the influences of external magnetic field on dielectric properties of composites were investigated systematically. The composites subjected to magnetic field treatment for 30 min at 60 °C exhibited the largest dielectric permittivity (385 at 100 Hz) when the BT-Fe3O4 concentration is approximately 33 vol.%. The BT-Fe3O4 suppressed the formation of a conducting path in the composite and induced low dielectric loss (0.3) and low conductivity (4.12 × 10(-9) S/cm) in the composite. Series-parallel model suggested that the enhanced dielectric permittivity of BT-Fe3O4/PVDF composites should arise from the ultrahigh permittivity of BT-Fe3O4 hybrid particles. However, the experimental results of the BT-Fe3O4/PVDF composites treated by magnetic field agree with percolation theory, which indicates that the enhanced dielectric properties of the BT-Fe3O4/PVDF composites originate from the interfacial polarization induced by the external magnetic field. This work provides a simple and effective way for preparing nanocomposites with enhanced dielectric properties for use in the electronics industry.

  4. Nuclear and Physical Properties of Dielectrics under Neutron Irradiation in Fast (BN-600) and Fusion (DEMO-S) Reactors

    Science.gov (United States)

    Blokhin, D. A.; Chernov, V. M.; Blokhin, A. I.

    2017-12-01

    Nuclear and physical properties (activation and transmutation of elements) of BN and Al2O3 dielectric materials subjected to neutron irradiation for up to 5 years in Russian fast (BN-600) and fusion (DEMO-S) reactors were calculated using the ACDAM-2.0 software complex for different post-irradiation cooling times (up to 10 years). Analytical relations were derived for the calculated quantities. The results may be used in the analysis of properties of irradiated dielectric materials and may help establish the rules for safe handling of these materials.

  5. Dielectric relaxation and optical properties of 4-amino-3-mercapto-6 ...

    Indian Academy of Sciences (India)

    2016-12-03

    , Cairo, Egypt. 2National ... conductor material. Application of the dielectric modulus formulism gives a simple method for evaluating the activation energy of the dielectric relaxation. .... 3D-mapped surface for very small area.

  6. Silicone rubbers for dielectric elastomers with improved dielectric and mechanical properties as a result of substituting silica with titanium dioxide

    DEFF Research Database (Denmark)

    Yu, Liyun; Skov, Anne Ladegaard

    2016-01-01

    metal oxide filled elastomer may contain too much filler. We therefore explore the replacement of silica with titanium dioxide to ensure a relatively low concentration of filler. Liquid silicone rubber (LSR) has relatively low viscosity, which is favorable for loading inorganic fillers. In the present...... and dynamic viscosity. Filled silicone elastomers with high loadings of nano-sized titanium dioxide (TiO2) particles were also studied. The best overall performing formulation had 35 wt.% TiO2 nanoparticles in the POWERSIL® XLR LSR, where the excellent ensemble of relative dielectric permittivity of 4.9 at 0...

  7. Electroactive Phase Induced Bi4Ti3O12-Poly(Vinylidene Difluoride) Composites with Improved Dielectric Properties

    Science.gov (United States)

    Bhardwaj, Sumit; Paul, Joginder; Chand, Subhash; Raina, K. K.; Kumar, Ravi

    2015-10-01

    Lead-free ceramic-polymer composite films containing Bi4Ti3O12 (BIT) nanocrystals as the active phase and poly(vinylidene difluoride) as the passive matrix were synthesized by spin coating. The films' structural, morphological, and dielectric properties were systemically investigated by varying the weight fraction of BIT. Formation of electroactive β and γ phases were strongly affected by the presence of BIT nanocrystals. Analysis was performed by Fourier-transform infrared and Raman spectroscopy. Morphological studies confirmed the homogeneous dispersion of BIT particles within the polymer matrix. The composite films had dielectric constants as high as 52.8 and low dielectric loss of 0.1 at 100 Hz when the BIT content was 10 wt.%. We suggest that the enhanced electroactive phase content of the polymer matrix and interfacial polarization may contribute to the improved dielectric performance of these composite films. Dielectric modulus analysis was performed to enable understanding of the dielectric relaxation process. Non-Debye-type relaxation behavior was observed for the composite films at high temperature.

  8. Transport and dielectric properties of double perovskite Pr2CoFeO6

    Science.gov (United States)

    Pal, Arkadeb; Singh, A.; Gangwar, V. K.; Chatterjee, Sandip

    2018-04-01

    The transport and dielectric measurements have been investigated for the polycrystalline double perovskite Pr2CoFeO6. In the temperature dependent resistivity measurement, we have observed semiconducting nature of the sample with activation energy 0.246 eV. In dielectric measurement as a function of temperature, a giant value of dielectric constant is observed at room temperature, the frequency dependence suggests a relaxor type dielectric relaxation.

  9. Electron beam and gamma ray irradiated polymer electrolyte films: Dielectric properties

    Directory of Open Access Journals (Sweden)

    S. Raghu

    2016-04-01

    Full Text Available In this study, polymer electrolyte films were irradiated with electron beam (EB and Gamma ray (GR at 50 and 150 kGy. The induced chemical changes in films due to irradiations have been confirmed from the Fourier Transform Infra red (FT-IR spectra. The X-ray Diffractometry (XRD results show that crystallinity decreases by ∼20% in EB and ∼10% in GR irradiated films respectively compared to non-irradiated film. The micro structural arrangement was investigated by Scanning Electronic Microscopy (SEM and the images reveal that there is a substantial improvement in the surface morphology in irradiated films. The real (ε′ and imaginary (ε″ dielectric constant and AC conductivity are found to increase with increase in irradiation dose. Improved dielectric properties and conductivity (1.74 x 10−4 & 1.15 x 10−4 S/cm, respectively, for EB and GR irradiated films at room temperature after irradiation and it confirm that EB and GR irradiation can be simple and effective route to obtaining highly conductive polymer electrolytes. From this study it is confirm that EB is more effectiveness than GR irradiation.

  10. Structural and dielectric properties of doped ferrite nanomaterials suitable for microwave and biomedical applications

    Directory of Open Access Journals (Sweden)

    Imran Sadiq

    2015-10-01

    Full Text Available The sol–gel auto-combustion method was adopted to synthesize nanomaterials of single-phase X-type hexagonal ferrites with the composition of Sr2−xGdxNi2Fe28−yCdyO46 (x=0.00, 0.02, 0.04, 0.06, 0.08, 0.10 and y=0, 0.1, 0.2, 0.3, 0.4, 0.5. The structural properties were carried out by XRD analysis and the lattice parameters show variation with the doping of Gd–Cd. The average particle size measured by TEM was in the range of 8–10 nm which is beneficial in obtaining suitable signal-to-noise ratio in recording media and biomedical applications. The room temperature resistivity enhanced with the increase of the dopant concentration. The increase in resistivity indicates that the synthesized materials can be considered good for the formation of the multilayer chip inductors (MLCIs as well as for the reduction of eddy current losses. The dielectric constant decreased with the increase in the frequency which is the general reported trend of the hexagonal ferrites and can be explained on the basis of Koop׳s theory and Maxwell–Wagner polarization-model. The abnormal dielectric behavior indicates the formation of small polarons in the material. The maximum value of tangent loss at low frequencies reflects the application of these materials in medium frequency devices (MF.

  11. Dielectric properties of amorphous Zr–Al–O and Zr-Si-O thin films

    Directory of Open Access Journals (Sweden)

    T. A. Naoi

    2015-03-01

    Full Text Available We have systematically studied the composition dependence of the dielectric properties of Zr1-xAlxO2-x/2 and Zr1-xSixO2. An essentially linear variation of the static dielectric constant, εs, was observed as a function of composition, x, for compositions rich in the p-block element, i.e., x > 0.4, for both chemical systems. However an abrupt change in εs is found near x ≈ 0.35, associated with the onset of crystallinity in as-deposited films. Breakdown fields do not show a comparable composition dependence. Measurements of the index of refraction at optical frequencies, combined with a simple Clausius–Mossotti interpretation, indicates that low-frequency (ionic contributions to the polarizability exhibit systematic deviation with respect to values linearly interpolated from the endmembers. These trends are not consistently affected by the presence of crystalline order, but are related to changes associated with heterogeneous local oxygen coordination and bonding.

  12. Effect of La doping on crystalline orientation, microstructure and dielectric properties of PZT thin films

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Wencai; Li, Qi; Wang, Xing [Dalian Univ. of Technology, Dalian (China). School of Mechanical Engineering; Yin, Zhifu [Jilin Univ., Changchun (China). Faculty of the School of Mechanical Science and Engineering; Zou, Helin [Dalian Univ. of Technology, Dalian (China). Key Lab. for Micro/Nano Systems and Technology

    2017-11-01

    Lanthanum (La)-modified lead zirconate titanate (PLZT) thin films with doping concentration from 0 to 5 at.-% have been fabricated by sol-gel methods to investigate the effects of La doping on crystalline orientation, microstructure and dielectric properties of the modified films. The characterization of PLZT thin films were performed by X-ray diffractometry (XRD), scanning electron microscopy (SEM) and precision impedance analysis. XRD analysis showed that PLZT films with La doping concentration below 4 at.-% exhibited (100) preferred orientation. SEM results indicated that PLZT films presented dense and columnar microstructures when La doping concentration was less than 3 at.-%, while the others showed columnar microstructures only at the bottom of the cross section. The maximum dielectric constant (1502.59 at 100 Hz) was obtained in a 2 at.-% La-doped film, which increased by 53.9 % compared with undoped film. Without introducing a seed layer, (100) oriented PLZT thin films were prepared by using conventional heat treatment process and adjusting La doping concentration.

  13. Synthesis and dielectric properties of ferroelectric-ferrimagnetic PZT-SFMO composites

    Directory of Open Access Journals (Sweden)

    Alexander V. Petrov

    2017-03-01

    Full Text Available Ferrimagnetic-ferroelectric composite materials on the base of Pb0.85Zr0.53Ti0.47O3– Sr2FeMoO6–δ (PZT-SFMO compounds have been prepared by a complex ceramic technology and a modified sol-gel synthesis. The dielectric properties of the PZT-SFMO composites with the PZT concentrations of 55 wt% and less, as well as of pure SFMO, are caused by the Maxwell-Wagner relaxation and a huge electrical conductivity. In contrast, in pure PZT the ferroelectric phase transition is clearly expressed in the static dielectric permittivity anomaly. Moreover, in all investigated composites, similarly to pure SFMO, the electrical conductivity anomaly is observed in the range from 560–540 K. This indicates that the composites with PZT concentrations of 55 wt% and higher are above the electrical and magnetic percolation threshold, in a good agreement with the excluded volume theory. In PZT-SFMO composites the DC electrical conductivity increases with SFMO concentration almost in a power law fashion, while the activation energy of the DC conductivity decreases under certain conditions.

  14. Effect of particle size on structural, magnetic and dielectric properties of manganese substituted nickel ferrite nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, E. Ranjith, E-mail: ranjueaswar@gmail.com [Sri Ramakrishna Mission Vidyalaya, Swami Shivananda Higher Secondary School, Coimbatore- 641020, Tamil Nadu (India); Kamzin, Aleksandr S. [Ioffe Physical–Technical Institute of RAS, St.-Petersburg 194026 (Russian Federation); Prakash, T. [Department of Science and Humanities, Tamilnadu College of Engineering, Karumathampatti, Coimbatore-641 659, Tamil Nadu (India)

    2015-03-15

    Mn substituted NiFe{sub 2}O{sub 4} ferrite nanoparticles (Mn–NiFe{sub 2}O{sub 4}) were synthesized by the auto-combustion method. Their actions were carried out at different fuel ratios (50%, 75% and 100%). The nanoparticles have been investigated by X-ray powder diffraction, scanning electron microscopy and transmission electron microscopy. The average crystallite size of the synthesized and annealed samples was between 25 and 75 nm, which were found to be dependent on both fuel ratio and annealing temperatures. However, lattice parameters, interplanar spacing and grain size were controlled by varying the fuel ratio. Magnetic characterizations of the nanoparticles were carried out using a vibrating sample magnetometer at room temperature. The saturation magnetization was computed and found to lie between 6 emu/g and 57 emu/g depending on the particle size of the studied sample. The coercivity was found to exhibit non-monotonic behavior with the particle size. Such behavior can be accounted for by the combination between surface anisotropy and thermal energies. The value of dielectric constant and dielectric loss was found to exhibit almost linear dependence on the particle size. - Highlights: • An auto-combustion method support to prepare less size of particles. • The excellent magnetic properties obtained by as-burnt samples. • Nature of the ferrite was affected with increasing annealing temperature.

  15. Magneto-dielectric properties of polymer- Fe3O4 nanocomposites

    Science.gov (United States)

    Yang, Ta-I.; Brown, Rene N. C.; Kempel, Leo C.; Kofinas, Peter

    The aim of this research is to elucidate the size effect of magnetic nanoparticles on the resultant magneto-dielectric properties of polymer nanocomposites at radio frequencies. The block copolymer of [styrene-b-ethylene/butylene-b-styrene] (SEBS) was utilized as a matrix for the templating of magnetic nanoparticles. Surfactant-modified iron oxide ( Fe3O4) nanoparticles of various sizes were successfully synthesized by a seed-mediated growth method. The surfactant prevented Fe3O4 aggregation and provided compatibility with the polymer matrix. The nucleation and growth of Fe3O4 nanoparticles was controlled by changing the concentration ratio of surfactant to iron-precursor. The free iron ions present during synthesis are the major factor contributing to the growth of larger particles. The Fe3O4 nanoparticle critical size for superparamagnetic to ferrimagnetic transition was determined to be near 30 nm at room temperature. The dielectric permittivity (ɛr) of the polymer composite increased with increasing amount of Fe3O4 doping, and was not influenced by nanoparticle size. However, the magnetic permeability ( μr) of the composites was significantly influenced by the size of Fe3O4 nanoparticles templated within the block copolymer matrix due to thermal energy fluctuations from the nanoparticle surroundings.

  16. Dielectric Property of Silicate-Doped CaBi4Ti4O15 Thin Films

    Science.gov (United States)

    Ogawa, Shota; Kondoh, Yohta; Kimura, Junichi; Funakubo, Hiroshi; Uchida, Hiroshi

    2012-09-01

    Thin films of silicate-doped CaBi4Ti4O15 were fabricated to enhance the insulating property of one-axis-oriented CaBi4Ti4O15 films under an applied electric field. The crystalline phase of CaBi4Ti4O15, a type of bismuth layer-structured dielectric (BLSD) compound, was successfully grown on (100)LaNiO3/(111)Pt/TiO2/(100)Si with the preferential orientation of the (001) plane by the addition of bismuth silicate with a nominal composition of Bi12SiO20 up to 1.00%. The crystallographic orientation of the (001)BLSD plane normal to the substrate surface was degraded by excessive bismuth silicate addition above 1.50%. The breakdown electric field was increased by bismuth silicate addition up to 2.00% without the degraded relative dielectric permittivity (ɛr) of approximately 230. The bismuth silicate could precipitate between the grain boundaries in the CaBi4Ti4O15 films without an interface reaction or a solid solution that enhances the insulating behavior of the BLSD films.

  17. CdSe nanocrystals ingrained dielectric nanocomposites: synthesis and photoluminescence properties

    Science.gov (United States)

    Dey, Chirantan; Goswami, Madhumita; Karmakar, Basudeb

    2015-01-01

    Cadmium selenide (CdSe) nanocrystals ingrained dielectric nanocomposites in a B2O3-SiO2-Al2O3-Na2O-K2O borosilicate glass system were synthesized by a single step in situ melt quenching technique. The sizes of the nanocrystals as well as the band gap of the nanocomposites were controlled by both concentration of CdSe and post thermal treatment duration. The nanocomposites were characterized by different instrumental techniques including detailed photoluminescence studies. The sizes of the CdSe nanocrystals were found to alter in the range 4-16 nm as estimated from the effective mass approximation model and optical absorption spectroscopy. However, the TEM analysis revealed the generation of two different size ranges, 3-4 and 23-45 nm, of the particles within the dielectric matrix. Selected area diffraction (SAED) and x-ray diffraction (XRD) patterns authenticate the formation of hexagonal nanostructures of CdSe. These nanocomposites were found to be capable of exhibiting strong visible red luminescence around 715 nm on excitation at 446 nm. This has originated from the electron-hole recombination of CdSe nanocrystal and defects or traps related transitions. The properties of these nanocomposites advocate their significant applications as semiconductor based luminescent materials.

  18. Effect of Sb-doping on the morphology and dielectric properties of chrysanthemum-like ZnO nanowire clusters

    Science.gov (United States)

    Yan, Jun-Feng; You, Tian-Gui; Zhang, Zhi-Yong; Tian, Jiang-Xiao; Yun, Jiang-Ni; Zhao, Wu

    2012-09-01

    Chrysanthemum-like ZnO nanowire clusters with different Sb-doping concentrations were prepared using a hydrothermal process. The microstructures, morphologies, and dielectric properties of the as-prepared products were characterized by X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), field emission environment scanning electron microscope (FEESEM), and microwave vector network analyzer respectively. The results indicate that the as-prepared products are Sb-doped ZnO single crystallines with a hexagonal wurtzite structure, the flower bud saturation degree Fd is obviously different from that of the pure ZnO nanowire clusters, the good dielectric loss property is found in Sb-doped ZnO products with low density, and the dielectric loss tangent tanδe increases with the increase of the Sb-doping concentration in a certain concentration range.

  19. Phase evolution and dielectric properties of MgTi2O5 ceramic sintered with lithium borosilicate glass

    International Nuclear Information System (INIS)

    Shin, Hyunho; Shin, Hee-Kyun; Jung, Hyun Suk; Cho, Seo-Yong; Hong, Kug Sun

    2005-01-01

    Phase evolution, densification, and dielectric properties of MgTi 2 O 5 dielectric ceramic, sintered with lithium borosilicate (LBS) glass, were studied. Reaction between LBS glass and MgTi 2 O 5 was significant in forming secondary phases such as TiO 2 and (Mg,Ti) 2 (BO 3 )O. The glass addition was not necessarily deleterious to the dielectric properties due to the formation of TiO 2 : permittivity increased and temperature coefficient of resonance frequency could be tuned to zero with the addition of LBS glass, although the inevitable glass-induced decrease of quality factor was not retarded by the formation of TiO 2 . The sintered specimen with 10 wt% LBS fired at 950 deg. C for 2 h showed permittivity of 19.3, quality factor of 6800 GHz, and τ f of -16 ppm/ deg. C

  20. In-waveguide measurements of MMW dielectric properties of ceramic materials for the US fusion reactor materials research program

    International Nuclear Information System (INIS)

    Kennedy, J.C. III; Farnum, E.F.; Clinard, F.W. Jr.

    1992-01-01

    The objective is to obtain accurate measurements of dielectric properties of candidate ceramic insulating materials for fusion reactors. As part of an IEA collaboration, a set of round-robin materials was purchased for comparing dielectric measurements at laboratories in the United Kingdom, Spain, Germany, US, and Japan. P. Pells at Aldermasten, UK, purchased MACOR 9658, a glass-mica composite, and Roger Stoller, from ORNL, purchased WESGO AL-300 and AL-995, polycrystalline alumina standards. The authors obtained some of each of these materials for making these measurements. The results have been shared with the other IEA partners, and P. Pells is preparing a summary document. They used the millimeter wave apparatus described below and elsewhere in detail to measure the dielectric properties of these materials at 90 to 100 Ghz at room temperature. The nominal purity of AL-300 was 0.967; the nominal purity of AL-995 was 0.995. Their method was to measure the power transmission coefficient. They used computerized data reduction techniques to compute k (the dielectric constant) and tanδ (the loss tangent) directly from transmission maxima and their corresponding frequencies; to verify this method, they applied the same technique to theoretically derived channel spectra that were obtained by solving exactly the complex transmission coefficient, given k and tanδ. The alumina material with a lower level of purity resulted in higher loss but lower dielectric constant. They obtained dielectric constants that were higher for all the materials than manufacturer-reported values taken at lower frequencies. In addition, they obtained higher dielectric constant values than those found by other investigators at 100 GHz for AL-995 and MACOR. Tanδ values were in good agreement with those of other investigators obtained by free-space methods and dispersive Fourier-transform techniques in the same frequency range

  1. Modeling of dielectric properties of complex fluids with an equation of state.

    Science.gov (United States)

    Maribo-Mogensen, Bjørn; Kontogeorgis, Georgios M; Thomsen, Kaj

    2013-03-28

    The static permittivity is a key property for describing solutions containing polar and hydrogen bonding compounds. However, the precise relationship between the molecular and dielectric properties is not well-established. Here we show that the relative permittivity at zero frequency (static permittivity) can be modeled simultaneously with thermodynamic properties. The static permittivity is calculated from an extension of the framework developed by Onsager, Kirkwood, and Fröhlich to associating mixtures. The thermodynamic properties are calculated from the cubic-plus-association (CPA) equation of state that includes the Wertheim association model as formulated in the statistical associating fluid theory (SAFT) to account for hydrogen bonding molecules. We show that, by using a simple description of the geometry of the association, we may calculate the Kirkwood g-factor as a function of the probability of hydrogen bond formation. The results show that it is possible to predict the static permittivity of complex mixtures over wide temperature and pressure ranges from simple extensions of well-established theories simultaneously with the calculation of thermodynamic properties.

  2. Influence of domain on grain size effects of the dielectric properties of BaTiO{sub 3} nanoceramics and nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Fang Chao, E-mail: yyohjh@sina.com [Department of Electrical and Electronic Engineering, Wuhan Polytechnic University, Wuhan 430023 (China); Chen Liangyan [Department of Electrical and Electronic Engineering, Wuhan Polytechnic University, Wuhan 430023 (China); Zhou Dongxiang [Department of Electronic Science and Technology, Huazhong University of Science and Technology, Wuhan City Hubei Province 430074 (China)

    2013-01-15

    The dielectric property of BaTiO{sub 3} nanoparticles and nanoceramics has been studied on the basis of Ginsburg-Landau-Devonshire thermodynamic theory. In this paper, considering nanodomains, Landau coefficients have been written as a function of grain size, and the dielectric constant of the material has been calculated at a variety of temperatures and grain size. The results indicate that with decreasing grain size, the dielectric peak decreases. The two lower dielectric peaks of the orthorhombic-rhombohedral phase and tetragonal-orthorhombic phase move to higher temperature, while cubic-tetragonal phase dielectric peak moves to lower temperature. The dielectric constant of BaTiO{sub 3} ceramics decreases with decreasing grain size. The dielectric constant peak at room temperature is at the grain size which is larger than the critical grain size 17-30 nm. The calculated result is consistent with the experimental data.

  3. Influence of Magnetite Nanoparticles on the Dielectric Properties of Metal Oxide/Polymer Nanocomposites Based on Polypropylene

    Science.gov (United States)

    Maharramov, A. A.; Ramazanov, M. A.; Di Palma, Luca; Shirinova, H. A.; Hajiyeva, F. V.

    2018-01-01

    Structure and dielectric properties of polymer nanocomposites based on isotactic polypropylene and iron oxide (Fe3O4) nanoparticles are studied. Distribution of magnetite nanoparticles in a polymer matrix was studied by scanning electron microscopy (SEM, Carl Zeiss). Dielectric properties of nanocomposites were examined by means of E7-21 impedance spectrometer in the frequency range of 102-106 Hz and temperature interval of 298-433 K. The frequency and temperature dependences of the dielectric permittivity ɛ, as well as the temperature dependence of log (ρ) were constructed. It is shown that introduction of the magnetite (Fe3O4) nanoparticles into a polypropylene matrix increases the dielectric permittivity of nanocomposites. An increase in the dielectric permittivity is explained by the increase in the polarization ability of nanocomposites. It is found that a decrease in the specific resistance with increasing temperature up to 318 K is associated with an increase in the ionic conductivity of nanocomposites. An increase in the resistance at temperatures higher than 358 K is due to the destruction of the crystalline phase of the polymer, as a result of which the distance between the Fe3O4 nanoparticles increases.

  4. The role of fuel concentration on particle size and dielectric properties of manganese substituted zinc ferrite nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Ranjith Kumar, E., E-mail: ranjueaswar@gmail.com; Jayaprakash, R.

    2014-10-01

    Mn substituted ZnFe{sub 2}O{sub 4} nanoparticles were prepared by the auto-combustion method using different fuel ratios of 50%, 75% and 100%.The powders were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and energy dispersive X-ray spectrum (EDX). Also, the dielectric behaviors of the samples were investigated for different annealing temperatures. The X-ray diffraction patterns indicated that the annealed samples resulted in the formation of crystalline powder and the presence of α-Fe{sub 2}O{sub 3} as a secondary phase. The average crystallite sizes of the samples are from ∼12 to 60 nm. The external morphology and microstructure of the samples are tested by SEM and TEM. The effect of annealing temperature and particle size on dielectric properties such as dielectric constant (έ) and dielectric loss (D) of the spinel Mn{sub x}Zn{sub 1−x}Fe{sub 2}O{sub 4} nanoparticles was measured using impedance analyzer in the frequency range 100 kHz–5 MHz. - Highlights: • An auto-combustion method support to prepare less size of particles. • The fuel ratio influences the dielectric properties of the samples. • Nature of the ferrites was affected with increasing annealing temperature.

  5. Role of anionic and cationic surfactants on the structural and dielectric properties of ZrO{sub 2} nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Sidhu, Gaganpreet Kaur; Kumar, Rajesh, E-mail: rajeshbaboria@gmail.com

    2017-01-15

    Highlights: • Synthesis of Zirconia nanoparticles with and without surfactants by co- precipitation method. • Surface modification of ZrO{sub 2} nanoparticles. • Phase transition with different concentration of surfactants. • Dielectric behavior of bare, CTAB assisted and SDS assisted ZrO{sub 2} nanoparticles. - Abstract: In the present paper, we report the synthesis of Cetyltrimethylammonium Bromide (CTAB) and Sodium dodecyl sulfate (SDS) assisted Zirconia (ZrO{sub 2}) nanoparticles by co-precipitation method. The effect of surfactant concentration on the structural and dielectric properties has been extensively studied. X-ray diffraction studies reveal the formation of tetragonal phase in the ZrO{sub 2} nanoparticles prepared by lower CTAB concentration. However, for higher concentration of CTAB some traces of monoclinic phase appeared along with tetragonal phase. SDS assisted nanoparticles shows crystalline tetragonal phase with lower concentration of SDS and amorphous nature with higher concentrations of SDS. FTIR results show the presence of Zr–O symmetrical stretching vibrations at tetrahedral site. The dielectric properties of all samples have been studied from 10 Hz to 1 MHz, revealing the low value of dielectric constant with CTAB and very high value with SDS as compared to bare ZrO{sub 2} nanoparticles. The dielectric behaviour of the bare and surfactant assisted nanoparticles has been correlated with the phase transition, size of nanoparticles and the nature of surfactants.

  6. 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.

  7. Interactions of light with rough dielectric surfaces - Spectral reflectance and polarimetric properties

    Science.gov (United States)

    Yon, S. A.; Pieters, C. M.

    1988-01-01

    The nature of the interactions of visible and NIR radiation with the surfaces of rock and mineral samples was investigated by measuring the reflectance and the polarization properties of scattered and reflected light for slab samples of obsidian and fine-grained basalt, prepared to controlled surface roughness. It is shown that the degree to which radiation can penetrate a surface and then scatter back out, an essential criterion for mineralogic determinations based on reflectance spectra, depends not only upon the composition of the material, but also on its physical condition such as sample grain size and surface roughness. Comparison of the experimentally measured reflectance and polarization from smooth and rough slab materials with the predicted models indicates that single Fresnel reflections are responsible for the largest part of the reflected intensity resulting from interactions with the surfaces of dielectric materials; multiple Fresnel reflections are much less important for such surfaces.

  8. Optical properties of multilayer metal-dielectric nanofilms with all-evanescent modes.

    Science.gov (United States)

    Feng, Simin; Elson, J; Overfelt, Pamela

    2005-05-30

    We present a systematic study of mode characteristics of multilayer metal-dielectric (M-D) nanofilm structures. This structure can be described as a coupled-plasmon-resonantwaveguide (CPRW), a special case of coupled-resonator optical waveguide (CROW). Similar to a photonic crystal, the M-D is periodic, but there is a major difference in that the fields are evanescent everywhere in the M-D structure as in a nanoplasmonic structure. The transmission coefficient exhibits periodic oscillation with increasing number of periods. As a result of surface-plasmon-enhanced resonant tunneling, a 100% transmission occurs periodically at certain thicknesses of the M-D structure, depending on the wavelength, lattice constants, and excitation conditions. This structure indicates that a transparent material can be composed from non-transparent materials by alternatively stacking different materials of thin layers. The general properties of the CPRW and resonant tunneling phenomena are discussed.

  9. Effect of illumination on the dielectrical properties of P3HT:PC70BM nanocomposites

    Science.gov (United States)

    Hamza, Saidi; Mhamdi, Asya; Aloui, Walid; Bouazizi, Abdelaziz; Khirouni, Kamel

    2017-05-01

    In this work, the effects of light-generated carriers on the dielectric properties of the structure ITO/PEDOT: PSS/P3HT:PC70BM/Al were carried out. Impedance spectroscopy was performed at an applied bias equal to the open-circuit. From the real and imaginary part of the impedance, a dipolar relaxation type was observed, which decreased in the presence of light due to an increase in the electron mobility. The Cole-Cole diagram fit using a parallel model R-CPE equivalent circuit leads to the comparison of parallel resistances (R p) and capacitance (CPE) in dark and under illumination. The decrease of R p is related to the increases in the photo-generated charge carrier density. The increase in the capacitance is related to the enhancement of the P3HT/PCBM interface homogeneity.

  10. Parameter Optimization in the Synthesis of BZT Ceramics to Achieve Good Dielectric Properties

    Directory of Open Access Journals (Sweden)

    A. Frattini

    2013-01-01

    Full Text Available The powder synthesis of barium zirconate titanate (BZT (BaZrTiO3 from the mechanochemical activation of BaCO3, ZrO2, and TiO2 was studied. The grinding effect, by using a planetary ball milling, on the crystallization temperature of BZT powders was analyzed. X-ray diffractometry, differential thermal analysis, thermogravimetric analysis, and scanning electronic microscopy (SEM were used as characterization methods. The crystallization behavior of powders activated by high-energy grinding and the effect of grinding time on the BZT crystallization were analyzed. After grinding by 4 h, the BaZr(0.05Ti(0.95O3 sample was almost fully crystallized at . The results of dielectric and ferroelectric properties show that high-energy ball milling is a practical and promising way to prepare BZT ceramics.

  11. A study of the dielectric and magnetic properties of multiferroic materials using the Monte Carlo method

    Directory of Open Access Journals (Sweden)

    A. Sosa

    2012-03-01

    Full Text Available A study of the dielectric and magnetic properties of multiferroic materials using the Monte Carlo (MC method is presented. Two different systems are considered: the first, ferroelectric-antiferromagnetic (FE-AFM recently studied by X. S. Gaoand J. M. Liu and the second antiferroelectric-ferromagnetic (AFE-FM. Based on the DIFFOUR-Ising hybrid microscopic model developed by Janssen, a Hamiltonian that takes into account the magnetoelectric coupling in both ferroic phases is proposed. The obtained results show that the existence of such coupling modifies the ferroelectric and magnetic ordering in both phases. Additionally, it is shown that the presence of a magnetic or an electric field influences the electric polarization and the magnetization, respectively, making evident the magnetoelectric effect.

  12. Phase evolution and microwave dielectric properties of A5M5O17-type ceramics

    Directory of Open Access Journals (Sweden)

    Ali Murad

    2017-07-01

    Full Text Available A number of A5M5O17 (A = Na, Ca, Sr, La, Nd, Sm, Gd, Dy, Yb; B = Ti, Nb, Ta type compounds were prepared by a solid-state sintering route and characterized in terms of structure, microstructure and microwave dielectric properties. The compatibility of rare earths with mixed niobate/tantalate and titanate phases was investigated. The larger ionic radii mismatch resulted in the formation of pyrochlore and/or mixed phases while in other cases, pure A5M5O17 phase was formed. The samples exhibited relative permittivity in the range of 35 to 82, quality factor (Q × fo = 897 GHz to 11946 GHz and temperature coefficient of resonance frequency (τf = -120 ppm/°C to 318 ppm/°C.

  13. Optical clearing: impact of optical and dielectric properties of clearing solutions on pulmonary tissue mechanics.

    Science.gov (United States)

    Schwenninger, David; Priebe, Hans-Joachim; Schneider, Matthias; Runck, Hanna; Guttmann, Josef

    2017-07-01

    Optical clearing allows tissue visualization under preservation of organ integrity. Optical clearing of organs with a physiological change in three-dimensional geometry (such as the lung) would additionally allow visualization of macroscopic and microscopic tissue geometry. A prerequisite, however, is the preservation of the native tissue mechanics of the optically cleared lung tissue. We investigated the impact of optical and dielectric properties of clearing solutions on biomechanics and clearing potency in porcine tissue strips of healthy lungs. After fixation, bleaching, and rehydration, four methods of optical clearing were investigated using eight different protocols. The mechanical and optical properties of the cleared lung tissue strips were investigated by uniaxial tensile testing and by analyzing optical transparency and translucency for red, green, and blue light before, during, and after the biochemical optical clearing process. Fresh tissue strips were used as controls. Best balance between efficient clearing and preserved mechanics was found for clearing with a 1:1 mixture of dimethyl sulfoxide (DMSO) and aniline. Our findings show that 1 ) the degree of tissue transparency and translucency correlated with the refractive index of the clearing solution index ( r = 0.976, P = 0.0004; and r = 0.91, P = 0.0046, respectively), 2 ) tissue mechanics were affected by dehydration and the type of clearing solution, and 3 ) tissue biomechanics and geometry correlated with the dielectric constant of the clearing solution ( r = -0.98, P mechanics, our results help to compose optimal clearing solutions. In addition, the results allow conclusions on the molecular interaction of solvents with collagen fibers in tissue, thereby consolidating existing theories about the functionality of collagen. Copyright © 2017 the American Physiological Society.

  14. Electrical resistivity and dielectric properties of helical microorganism cells coated with silver by electroless plating

    Energy Technology Data Exchange (ETDEWEB)

    Cai, Jun, E-mail: jun_cai@buaa.edu.cn [Bionic and Micro/Nano/Bio Manufacturing Technology Research Center, School of Mechanical Engineering and Automation, Beihang University, Beijing 100191 (China); Lan, Mingming; Zhang, Deyuan; Zhang, Wenqiang [Bionic and Micro/Nano/Bio Manufacturing Technology Research Center, School of Mechanical Engineering and Automation, Beihang University, Beijing 100191 (China)

    2012-09-01

    Highlights: Black-Right-Pointing-Pointer We use the microorganism cells as forming templates to fabricate the bio-based conductive particles. Black-Right-Pointing-Pointer The microorganism cells selected as forming templates are Spirulina platens, which are of natural helical shape and high aspect ratio. Black-Right-Pointing-Pointer The sliver-coated Spirulina cells are a kind of lightweight conductive particles. Black-Right-Pointing-Pointer The composites containing sliver-coated Spirulina cells exhibit a lower percolation value. - Abstract: In this paper, microorganism cells (Spirulina platens) were used as forming templates for the fabrication of the helical functional particles by electroless silver plating process. The morphologies and ingredients of the coated Spirulina cells were analyzed with scanning electron microscopy and energy dispersive spectrometer. The crystal structures were characterized by employing the X-ray diffraction. The electrical resistivity and dielectric properties of samples containing different volume faction of sliver-coated Spirulina cells were measured and investigated by four-probe meter and vector network analyzer. The results showed that the Spirulina cells were successfully coated with a uniform silver coating and their initial helical shapes were perfectly kept. The electrical resistivity and dielectric properties of the samples had a strong dependence on the volume content of sliver-coated Spirulina cells and the samples could achieve a low percolation value owing to high aspect ratio and preferable helical shape of Spirulina cells. Furthermore, the conductive mechanism was analyzed with the classic percolation theory, and the values of {phi}{sub c} and t were obtained.

  15. Dielectric characterisation of soil

    NARCIS (Netherlands)

    Hilhorst, M.A.

    1998-01-01

    The potential of dielectric measuring techniques for soil characterisation has not been fully explored. This is attributed to the complex and incomplete theory on dielectrics, as well as to the lack of sensors suited for practical applications.

    The theory on dielectric properties of soils is

  16. Optical, magnetic, and dielectric properties of opal matrices with intersphere nanocavities filled with crystalline multiferroic, piezoelectric, and segnetoelectric materials

    Czech Academy of Sciences Publication Activity Database

    Samoilovich, M.I.; Rinkevich, A.B.; Bovtun, Viktor; Belyanin, A.F.; Kempa, Martin; Nuzhnyy, Dmitry; Tsvetkov, M.Yu.; Klescheva, S.M.

    2013-01-01

    Roč. 83, č. 11 (2013), s. 2132-2147 ISSN 1070-3632 R&D Projects: GA ČR GAP204/12/0232 Institutional support: RVO:68378271 Keywords : composites * opal matrices * optical, magnetic, and dielectric properties Subject RIV: JI - Composite Materials Impact factor: 0.418, year: 2013

  17. Effect of the piezoelectric ceramic filler dielectric constant on the piezoelectric properties of PZT-epoxy composites

    NARCIS (Netherlands)

    Khaliq, J.; Deutz, D.B.; Frescas, J.A.C.; Vollenberg, P.; Hoeks, T.; Zwaag, S. van der; Groen, P.

    2017-01-01

    Piezoelectric composites made from soft and hard lead zirconium titanate (PZT) particles as filler and an epoxy as the matrix were prepared by dielectrophoresis and studied for their piezoelectric properties. It was found that the dielectric constant of the piezoelectric filler plays a significant

  18. Electrical, dielectric, and optical properties of Sb2O3–Li2O–MoO3 glasses

    Czech Academy of Sciences Publication Activity Database

    Kubliha, M.; Soltani, M.T.; Trnovcová, V.; Legouera, M.; Labaš, V.; Kostka, Petr; Le Coq, D.; Hamzaoui, M.

    2015-01-01

    Roč. 428, NOV 15 (2015), s. 42-48 ISSN 0022-3093 R&D Projects: GA ČR GAP106/12/2384 Institutional support: RVO:67985891 Keywords : lithium molybdenum–antimonite glass es * electrical conductivity * electrical relaxation * dielectric response * optical properties Subject RIV: JH - Ceramics, Fire-Resistant Materials and Glass Impact factor: 1.825, year: 2015

  19. Densification and dielectric properties of SrO–Al2O3–B2O3 ceramic ...

    Indian Academy of Sciences (India)

    Abstract. The influence of SrO (0·0–5·0 wt%) on partial substitution of alpha alumina (corundum) in ceramic com- position (95 Al2O3–5B2O3) have been studied by co-precipitated process and their phase composition, microstruc- ture, microchemistry and microwave dielectric properties were studied. Phase composition ...

  20. Structure, dielectric, and magnetic properties of Sr.sub.2./sub.TiMnO.sub.6./sub. ceramics

    Czech Academy of Sciences Publication Activity Database

    Preethi Meher, K.R.S.; Savinov, Maxim; Kamba, Stanislav; Goian, Veronica; Varma, K.B.R.

    2010-01-01

    Roč. 108, 09 (2010), 094108/1-094108/9 ISSN 0021-8979 R&D Projects: GA ČR(CZ) GA202/09/0682 Institutional research plan: CEZ:AV0Z10100520 Keywords : magnetic and dielectric properties * perovskite Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.064, year: 2010

  1. Polymer blends of poly(2-cyanoethyl vinyl ether) and poly(methyl methacrylate) with improved dielectric properties for flexible electronics

    Czech Academy of Sciences Publication Activity Database

    Piana, Francesco; Kredatusová, Jana; Paruzel, Bartosz; Pfleger, Jiří

    2017-01-01

    Roč. 11, č. 9 (2017), s. 731-737 ISSN 1788-618X R&D Projects: GA MŠk(CZ) LO1507 Institutional support: RVO:61389013 Keywords : polymer blends and alloys * dielectric properties * differential scanning calorimetry Subject RIV: CD - Macromolecular Chemistry OBOR OECD: Polymer science Impact factor: 2.983, year: 2016

  2. Enhanced dielectric properties of epoxy resin with high content of nano-Al2O3 composites

    Science.gov (United States)

    Xu, Dandan; Wang, Tingting; Han, Xinghao; Qiao, Ru

    2018-01-01

    Epoxy resin was modified by adding different contents (30%, 60% wt.) of nano-Al2O3 particles, which were modified by silicon coupling agent KH560 (γ-amino propyl triethoxy silane), in the form of nano-Al2O3 particles/epoxy composites, via casting method to improve the dielectric properties. The chemical structures of modified and unmodified nano-Al2O3 particles and the morphologies of composites fractures were characterized by Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM) respectively. And the thermal property and dielectric properties were also investigated. The results showed the modified nano-Al2O3 particles well dispersed in the epoxy matrix and the thermal stability of composites was improved. And the dielectric constant of the composites was up to 14 when the content of nano-Al2O3 was 60%, which was 2 times larger than that of pure epoxy. Moreover, the composites also exhibited good dielectric property under high frequencies ranged from 1x107 to 4x107 Hz.

  3. An analysis of the microwave dielectric properties of solvent-oil feedstock mixtures at 300-3000 MHz.

    Science.gov (United States)

    Terigar, Beatrice G; Balasubramanian, Sundar; Boldor, Dorin

    2010-08-01

    Microwaves can be a more efficient method than traditional thermal treatment to deliver the energy required for heating in solvent-oil extraction due to its volumetric, direct coupling with the material. An understanding of the behavior of dielectric properties of solvent-feedstock mixtures is important for designing and optimizing any microwave-based extraction process. In this study rice bran and soybean flour were mixed separately with four different solvents (methanol, ethanol, hexane and isopropanol) at different ratios (1:2, 1:1, 2:1 w/w). For the samples mixed with ethanol, the dielectric properties were measured at 23, 30, 40 and 50 degrees C, while for all other sample-solvent mixtures experiments were performed at room temperature. Dielectric properties were determined using a vector network analyzer and dielectric probe kit using the open-ended coaxial probe method in the frequency range of 300 MHz to 3 GHz. Results from the study indicate that dielectric constants were dependent on frequency and were strongly influenced by temperature, mix ratio and solvent type. The dielectric loss of all mixtures except those with hexane (which were virtually zero) varied with frequency and temperature, solvent type, and mix ratio. Most of the results presented are emphasized at 433, 915 and 2450 MHz, frequencies allocated by the Federal Communication Commission (F.C.C.) for microwave applications. The results of the study, presented here for the first time to our knowledge, will help in selection of appropriate solvent, mixing ratio and frequency for designing microwave-assisted oil extraction systems. Copyright 2010. Published by Elsevier Ltd.

  4. 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.

  5. Low-temperature phase transition in γ-glycine single crystal. Pyroelectric, piezoelectric, dielectric and elastic properties

    Energy Technology Data Exchange (ETDEWEB)

    Tylczyński, Zbigniew, E-mail: zbigtyl@amu.edu.pl [Faculty of Physics, Adam Mickiewicz University, Umultowska 85, 61-614 Poznań (Poland); Busz, Piotr [Institute of Molecular Physics, Polish Academy of Science, Smoluchowskiego 17, 60-179 Poznań (Poland)

    2016-11-01

    Temperature changes in the pyroelectric, piezoelectric, elastic and dielectric properties of γ-glycine crystals were studied in the range 100 ÷ 385 K. The pyroelectric coefficient increases monotonically in this temperature range and its value at RT was compared with that of other crystals having glycine molecules. A big maximum in the d14 component of piezoelectric tensor compared by maximum in attenuation of the resonant face-shear mode were observed at 189 K. The components of the elastic stiffness tensor and other components of the piezoelectric tensor show anomalies at this temperature. The components of electromechanical coupling coefficient determined indicate that γ-glycine is a weak piezoelectric. The real and imaginary part of the dielectric constant measured in the direction perpendicular to the trigonal axis show the relaxation anomalies much before 198 K and the activation energies were calculated. These anomalies were interpreted as a result of changes in the NH{sub 3}{sup +} vibrations through electron-phonon coupling of the so called “dynamical transition”. The anomalies of dielectric constant ε*{sub 11} and piezoelectric tensor component d{sub 14} taking place at 335 K are associated with an increase in ac conductivity caused by charge transfer of protons. - Graphical abstract: Imaginary part of dielectric constant in [100] direction. - Highlights: • Piezoelectric, elastic and dielectric constants anomalies were discovered at 189 K. • These anomalies were interpreted as a result of so called “dynamical transition”. • Relaxational dielectric anomaly was explained by the dynamics of glycine molecules. • Pyroelectric coefficient of γ-glycine was determined in a wide temperature range. • Complex dielectric & piezoelectric anomalies at 335 K were caused by protons hopping.

  6. Characterization and study of dielectric and electrical properties of CaBi4Ti4O15 (CBT) added with Bi2O3

    International Nuclear Information System (INIS)

    Freitas, D.B.; Campos Filho, M.C.; Sales, J.C.; Silva, P.M.O.; Sombra, A.S.

    2011-01-01

    The ceramic perovskite CaBi 4 Ti 4 O 15 (CBT) of space group A21am, Aurivillius family with deficiency A 5 B 4 O 15 cation has been prepared by solid state method in a planetary ball mill of high energy. The reagents samples were ground and calcined and then added with Bi 2 O 3 (2% wt.) This work aims to characterize by X-ray diffraction to study the electrical properties and dielectric properties of (CBT). The x-ray diffraction revealed the formation of single orthorhombic phase. As for the dielectric properties (dielectric constant and dielectric loss) were measured at 30 deg C to 450 deg C, through which can be verified the presence of thermally activated processes. This phase has properties very relevant for possible use in capacitive devices, miniaturized filters, dielectric resonators antennas and oscillators. (author)

  7. Dielectric properties of nanosilica/low-density polyethylene composites: The surface chemistry of nanoparticles and deep traps induced by nanoparticles

    Directory of Open Access Journals (Sweden)

    S. Ju

    2014-09-01

    Full Text Available Four kinds of nanosilica particles with different surface modification were employed to fabricate low-density polyethylene (LDPE composites using melt mixing and hot molding methods. The surface chemistry of modified nanosilica was analyzed by X-ray photoelectron spectroscopy. All silica nanoparticles were found to suppress the space charge injection and accumulation, increase the volume resistivity, decrease the permittivity and dielectric loss factor at low frequencies, and decrease the dielectric breakdown strength of the LDPE polymers. The modified nanoparticles, in general, showed better dielectric properties than the unmodified ones. It was found that the carrier mobility, calculated from J–V curves using the Mott-Gurney equation, was much lower for the nanocomposites than for the neat LDPE.

  8. An investigation of structural, magnetic and dielectric properties of R2NiMnO6 (R = rare earth, Y)

    International Nuclear Information System (INIS)

    Booth, R.J.; Fillman, R.; Whitaker, H.; Nag, Abanti; Tiwari, R.M.; Ramanujachary, K.V.; Gopalakrishnan, J.; Lofland, S.E.

    2009-01-01

    We have investigated the structure, magnetic and dielectric properties of the double perovskite oxides, R 2 NiMnO 6 (R = Pr, Nd, Sm, Gd, Tb, Dy, Ho and Y). We could refine powder X-ray diffraction patterns of all the phases on the basis of monoclinic (P2 1 /n) double perovskite structure where Ni and Mn atoms are ordered at 2c and 2d sites, respectively. All the phases are ferromagnetic insulators exhibiting relatively low dielectric loss and dielectric constants in the range 15-25. The ferromagnetic ordering temperature of the R 2 NiMnO 6 series seems to correlate better with the radius of R 3+ atoms than with the average Ni-O-Mn angle (φ) in the double perovskite structure. These results are consistent with all samples having Mn 4+ and Ni 2+ with minimal antisite disorder.

  9. Relationship between the dielectric and mechanical properties and the ratio of epoxy resin to hardener of the hybrid thermosetting polymers

    International Nuclear Information System (INIS)

    Dias Filho, Newton Luiz; Aquino, Hermes Adolfo de; Pires, Geovanna; Caetano, Laercio

    2006-01-01

    The relationship between the dielectric properties (dielectric constant, ε'', and loss factor, ε''; activation energy, E a ) and the ratio of epoxy resin (OG) to hardener of the epoxy resin thermosetting polymers was investigated. The amplitude of the ε'' peak decreases with increasing OG content until about 73 wt.% and slightly increases at higher OG content. The temperature of the position of the ε'' peak increases with the increasing of OG content, reaching maximum values for compositions in the range of 67 and 73 wt.%, and then it decreases sharply at higher OG content. The activation energy obtained from dielectric relaxation increased with increasing wt.% OG up to around 70 wt.%. Further increase in concentration of OG up to 83 wt.% reduced E a . The curves of tensile modulus and fracture (author)

  10. Effects of temperature, moisture, and metal salt content on dielectric properties of rice bran associated with radio frequency heating.

    Science.gov (United States)

    Ling, Bo; Liu, Xiaoli; Zhang, Lihui; Wang, Shaojin

    2018-03-13

    Dielectric heating including microwave (MW) and radio frequency (RF) energy has been regarded as alternative thermal treatments for food processing. To develop effective rice bran (RB) stabilization treatments based on RF and MW heating, dielectric properties (DPs) with dielectric constant (ε') and loss factor (ε″) of RB samples at frequencies (10-3000 MHz), temperatures (25-100 °C), moisture content (MC, 10.36-24.69% w.b.) and three metal salt levels (0.05-2.00%) were determined by an open-ended coaxial probe and impedance analyzer. Results indicated that both ε' and ε″ of RB samples increased with increasing temperature and MC. The increase rate was greater at higher temperature and moisture levels than at lower levels, especially at frequencies lower than 300 MHz. Cubic order models were developed to best fit the relationship between DPs of RB samples and temperature/MC at five frequencies with R 2 greater than 0.994. Both ε″ and RF heating rate of RB samples increased significantly with added NaCl (2%), KCl (1%) and Na 6 O 18 P 6 (2%). The obtained data are useful in developing computer models and simulating dielectric heating for RB stabilization and may also provide theoretical basis for synergistic stabilization of RB under combined dielectric heating with metal salts.

  11. Effect of substitution group on dielectric properties of 4H-pyrano [3, 2-c] quinoline derivatives thin films

    Science.gov (United States)

    H, M. Zeyada; F, M. El-Taweel; M, M. El-Nahass; M, M. El-Shabaan

    2016-07-01

    The AC electrical conductivity and dielectrical properties of 2-amino-6-ethyl-5-oxo-4-(3-phenoxyphenyl)-5,6-dihydro-4H-pyrano[3, 2-c]quinoline-3-carbonitrile (Ph-HPQ) and 2-amino-4-(2-chlorophenyl)-6-ethyl-5-oxo-5,6-dihydro-4H-pyrano [3, 2-c] quinoline-3-carbonitrile (Ch-HPQ) thin films were determined in the frequency range of 0.5 kHz-5 MHz and the temperature range of 290-443 K. The AC electrical conduction of both compounds in thin film form is governed by the correlated barrier hopping (CBH) mechanism. Some parameters such as the barrier height, the maximum barrier height, the density of charges, and the hopping distance were determined as functions of temperature and frequency. The phenoxyphenyl group has a greater influence on those parameters than the chlorophenyl group. The AC activation energies were determined at different frequencies and temperatures. The dielectric behaviors of Ph-HPQ and Ch-HPQ were investigated using the impedance spectroscopy technique. The impedance data are presented in Nyquist diagrams for different temperatures. The Ch-HPQ films have higher impedance than the Ph-HPQ films. The real dielectric constant and dielectric loss show a remarkable dependence on the frequency and temperature. The Ph-HPQ has higher dielectric constants than the Ch-HPQ.

  12. Effect of Barium Titanate Particles on Dielectric and Electro-Optical Properties of a Smectic-a Liquid Crystal

    Science.gov (United States)

    Ramazanov, M. A.; Imamaliyev, A. R.; Humbatov, Sh. A.; Agamaliev, Z. A.

    2018-02-01

    The effect of submicron ferroelectric BaTiO3 particles on the dielectric and electro-optical properties of the smectic-A liquid crystal (LC) with a high negative dielectric anisotropy is investigated. It is shown that the addition of BaTiO3 particles with a weight amount of 1% reduces insignificantly the transverse dielectric permittivity component ɛ ⊥ of, but significantly increases the longitudinal dielectric permittivity component ɛ // of the smectic-A LC. As a result, the anisotropy of the dielectric permittivity Δɛ = ɛ // - ɛ ⊥ of the smectic-A LC decreases. The addition of BaTiO3 particles shifts the dispersion ɛ ⊥ toward lower frequencies. Both components of the electrical conductivity of LC colloid + BaTiO3 are an order of magnitude higher than of the pure LC. The threshold voltage of the homeotropic-planar transition of the colloid is twice smaller, and its velocity is 6 times higher in comparison with the pure LC. A simple model explaining qualitatively all results obtained is presented.

  13. Crystal Structure and Dielectric Property of Bismuth Layer-Structured Dielectric Films with c-Axis Preferential Crystal Orientation

    Science.gov (United States)

    Mizutani, Yuki; Kiguchi, Takanori; Konno, Toyohiko J.; Funakubo, Hiroshi; Uchida, Hiroshi

    2010-09-01

    Thin films of bismuth layer-structured dielectrics (BLSDs), CaBi4Ti4O15, and SrBi4Ti4O15, were prepared by a chemical solution deposition (CSD) technique on various substrates, such as (111)Pt/TiO2/(100)Si, (100)LaNiO3/(111)Pt/TiO2/(100)Si, and (100)SrRuO3∥(100)SrTiO3 substrates. Conductive perovskite oxide LaNiO3 with (100) preferential crystal orientation was introduced into the interface between the BLSD film and the (111)Pt/TiO2/(100)Si substrate to control the crystal orientation of BLSD by lattice matching between pseudo-perovskite blocks in the BLSD crystal and the (100)LaNiO3 plane with the perovskite structure. The (00l) planes of BLSD crystals were preferentially oriented on the substrate surface of the (100)LaNiO3/(111)Pt/TiO2/(100)Si, whereas randomly-oriented BLSD crystals with lower crystallinity were only obtained on the surface of (111)Pt/TiO2/(100)Si substrate. The (001)-oriented BLSD films exhibited the leakage current densities below 10-7 A/cm2 at ±50 kV/cm, which is significantly lower than those for randomly-oriented films, above 10-6 A/cm2, The room-temperature dielectric constants (ɛr) of CaBi4Ti4O15 and SrBi4Ti4O15 thin films on the (100)LaNiO3/(111)Pt/TiO2/(100)Si substrate were both approximately 250, while those on the (100)SrRuO3∥(100)SrTiO3 substrate were approximately 220. The temperature dependence of the capacitances for the CaBi4Ti4O15 and SrBi4Ti4O15 films on the (100)LaNiO3/(111)Pt/TiO2/(100)Si substrate were approximately +17 and +10%, respectively, in the temperature range from 25 to 400 °C. These values were slightly larger than those of epitaxial BLSD films, but smaller than those of (Ba,Sr)TiO3 films.

  14. Physico-Mechanical, Dielectric, and Piezoelectric Properties of PVDF Electrospun Mats Containing Silver Nanoparticles

    Directory of Open Access Journals (Sweden)

    Ahmed A. Issa

    2017-10-01

    Full Text Available Poly(vinylidene fluoride (PVDF is a piezoelectric material with outstanding physical and mechanical properties. The piezoelectric properties depend on the β-phase content of this polymer, while the physical and mechanical properties depend on the morphology and degree of crystallinity of the material. Silver has antibacterial effects, and silver nanoparticles (Ag-NPs have large surface areas rich in electrons. In this paper, we produced electrospun PVDF fibrous mats that contained different contents of Ag-NPs between 0% and 1.0%. The β-content in PVDF was found to increase by about 8% for Ag-NPs content of 0.4–0.6%. The electrospun fiber mats had a higher β-crystalline content, nano-pores were visible on the fiber surfaces, and the tensile strength and thermal stability were improved. Dielectric analysis indicated weak interfacial adhesion between the PVDF and Ag-NPs. Good piezoelectric response was observed in the electrospun fibers containing 0.4% AgNPs, which shows a good correlation between the β-crystalline phase content of the composites and its energy-harvesting application.

  15. Measurement of sugar content of watermelon using near-infrared reflectance spectroscopy in comparison with dielectric property

    Science.gov (United States)

    Tao, Xuemei; Bao, Yidan

    2006-09-01

    The sugar content of watermelon is important to its taste thus influences the market. It's difficult to know whether the melon is sweet or not for consumers. We tried to develop a convenient meter to determine the sugar of watermelon. The first objective of this paper was to demonstrate the feasibility of using a near-infrared reflectance spectrometer (NIRS) to investigate the relationship between sugar content of watermelon and absorption spectra. The NIRS reflectance of nondestructive watermelon was measured with a Visible/NIR spectrophotometer in 325-1075nm range. The sugar content of watermelon was obtained with a handhold sugar content meter. The second objective was to measure the watermelon's dielectric property, such as dielectric resistance, capacitance, quality factor and dielectric loss. A digital electric bridge instrument was used to get the dielectric property. The experimental results show that they were related to watermelon's sugar content. A comparison between the two methods was made in the paper. The model derived from NIRS reflection is useful for class identification of Zaochun Hongyu watermelon though it's not quite accurate in sweetness prediction (the max. deviation is 0.7). Electric property bears little relation to sugar content of watermelon at this experiment and it couldn't be used as non-destructive inspection method.

  16. Synthesis, structural, dielectric and magnetic properties of polyol assisted copper ferrite nano particles

    Energy Technology Data Exchange (ETDEWEB)

    Pavithradevi, S. [Assistant Professor, Department of Physics, Park College of Engineering and Technology, Coimbatore (India); Suriyanarayanan, N., E-mail: madurasuri2210@yahoo.com [Prof & Head, Department of Physics, Government College of Technology, Coimbatore (India); Boobalan, T. [Lecturer, Department of Physics, PSG Polytechnic College, Coimbatore (India)

    2017-03-15

    Nanocrystalline copper ferrite CuFe{sub 2}O{sub 4} is synthesized by co-precipitation method in ethylene glycol as chelating agent, using sodium Hydroxide as precipitator at pH 8. The as synthesized CuFe{sub 2}O{sub 4} is annealed at temperatures of 350 °C, 700 °C, and 1050 °C for 2 h respectively. The thermal analysis of the synthesized sample is done by TG technique. It is shown that at 260 °C ethylene glycol has evaporated completely and after 715 °C, spinel ferrite is formed with a cubic structure. The calculated lattice parameters are in agreement with the reported values. FTIR spectra of CuFe{sub 2}O{sub 4} nano particles are as synthesized and annealed at 1050 °C and recorded between 400 cm{sup −1} and 4000 cm{sup −1}. It shows that when the temperature increases ethylene glycol gradually evaporates. Finally, nano crystalline single phase spinel ferrite is obtained. X-ray diffraction (XRD) and electron diffraction (EDS) studies show that the sample is indexed as the face centered cubic spinel structure. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) indicated that the particles are flaky and spherical with the crystallite size in the range of 25–34 nm. From the dielectric studies, the dielectric constant decreases as the frequency increases. Low value of dielectric loss at higher frequencies suggests that the material is suitable for high frequency applications. AC conductivity increases with frequency. The magnetic properties of the samples are measured using a vibrating sample magnetometer (VSM) at room temperature, which shows that the sample exhibited a typical super paramagnetic behavior at low temperature. The saturation magnetization, remanant magnetism, and coercivity increases with applied field. - Highlights: • Complete removal of hematite phase along with ethylene glycol at 1050 °C. • Large decrease in particle sizes noticed along with ethylene glycol. • Ethylene glycol improves purity of the

  17. 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.

  18. 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

  19. A large-scale study of the ultrawideband microwave dielectric properties of normal, benign and malignant breast tissues obtained from cancer surgeries

    Energy Technology Data Exchange (ETDEWEB)

    Lazebnik, Mariya [Department of Electrical and Computer Engineering, University of Wisconsin, Madison, WI (United States); Popovic, Dijana [Department of Electrical and Computer Engineering, University of Calgary, Calgary, AB (Canada); McCartney, Leah [Department of Electrical and Computer Engineering, University of Calgary, Calgary, AB (Canada); Watkins, Cynthia B [Department of Electrical and Computer Engineering, University of Wisconsin, Madison, WI (United States); Lindstrom, Mary J [Department of Biostatistics and Medical Informatics, University of Wisconsin, Madison, WI (United States); Harter, Josephine [Department of Pathology, University of Wisconsin, Madison, WI (United States); Sewall, Sarah [Department of Pathology, University of Wisconsin, Madison, WI (United States); Ogilvie, Travis [Department of Pathology, University of Calgary, Calgary, AB (Canada); Magliocco, Anthony [Department of Pathology, University of Calgary, Calgary, AB (Canada); Breslin, Tara M [Department of Surgery, University of Wisconsin, Madison, WI (United States); Temple, Walley [Department of Surgery and Oncology, University of Calgary, Calgary, AB (Canada); Mew, Daphne [Department of Surgery and Oncology, University of Calgary, Calgary, AB (Canada); Booske, John H [Department of Electrical and Computer Engineering, University of Wisconsin, Madison, WI (United States); Okoniewski, Michal [Department of Electrical and Computer Engineering, University of Calgary, Calgary, AB (Canada); Hagness, Susan C [Department of Electrical and Computer Engineering, University of Wisconsin, Madison, WI (United States)

    2007-10-21

    The development of microwave breast cancer detection and treatment techniques has been driven by reports of substantial contrast in the dielectric properties of malignant and normal breast tissues. However, definitive knowledge of the dielectric properties of normal and diseased breast tissues at microwave frequencies has been limited by gaps and discrepancies across previously published studies. To address these issues, we conducted a large-scale study to experimentally determine the ultrawideband microwave dielectric properties of a variety of normal, malignant and benign breast tissues, measured from 0.5 to 20 GHz using a precision open-ended coaxial probe. Previously, we reported the dielectric properties of normal breast tissue samples obtained from reduction surgeries. Here, we report the dielectric properties of normal (adipose, glandular and fibroconnective), malignant (invasive and non-invasive ductal and lobular carcinomas) and benign (fibroadenomas and cysts) breast tissue samples obtained from cancer surgeries. We fit a one-pole Cole-Cole model to the complex permittivity data set of each characterized sample. Our analyses show that the contrast in the microwave-frequency dielectric properties between malignant and normal adipose-dominated tissues in the breast is considerable, as large as 10:1, while the contrast in the microwave-frequency dielectric properties between malignant and normal glandular/fibroconnective tissues in the breast is no more than about 10%.

  20. A large-scale study of the ultrawideband microwave dielectric properties of normal, benign and malignant breast tissues obtained from cancer surgeries

    Science.gov (United States)

    Lazebnik, Mariya; Popovic, Dijana; McCartney, Leah; Watkins, Cynthia B.; Lindstrom, Mary J.; Harter, Josephine; Sewall, Sarah; Ogilvie, Travis; Magliocco, Anthony; Breslin, Tara M.; Temple, Walley; Mew, Daphne; Booske, John H.; Okoniewski, Michal; Hagness, Susan C.

    2007-10-01

    The development of microwave breast cancer detection and treatment techniques has been driven by reports of substantial contrast in the dielectric properties of malignant and normal breast tissues. However, definitive knowledge of the dielectric properties of normal and diseased breast tissues at microwave frequencies has been limited by gaps and discrepancies across previously published studies. To address these issues, we conducted a large-scale study to experimentally determine the ultrawideband microwave dielectric properties of a variety of normal, malignant and benign breast tissues, measured from 0.5 to 20 GHz using a precision open-ended coaxial probe. Previously, we reported the dielectric properties of normal breast tissue samples obtained from reduction surgeries. Here, we report the dielectric properties of normal (adipose, glandular and fibroconnective), malignant (invasive and non-invasive ductal and lobular carcinomas) and benign (fibroadenomas and cysts) breast tissue samples obtained from cancer surgeries. We fit a one-pole Cole-Cole model to the complex permittivity data set of each characterized sample. Our analyses show that the contrast in the microwave-frequency dielectric properties between malignant and normal adipose-dominated tissues in the breast is considerable, as large as 10:1, while the contrast in the microwave-frequency dielectric properties between malignant and normal glandular/fibroconnective tissues in the breast is no more than about 10%.

  1. Effect of strontium doping on dielectric, ferroelectric and piezoelectric properties of PLZTN ceramics

    International Nuclear Information System (INIS)

    Ramam, Koduri; Lopez, Marta

    2007-01-01

    Ceramic compositions of [Pb 1-x-y La x Sr y ][(Zr z Ti 1-z ) (1-(x/4)-(5/4)k) Nb k ]O 3 (PLSZTN), where y = 0, 0.5, 1.0 and 1.5 mol% have been fabricated by solid-state reaction method. Introduction of strontium in PLZTN lattice showed ferroelectric tetragonal nature and further increment of Sr 2+ favored intensified tetragonality. Microstructure studies revealed that grain growth enhanced with the addition of Sr 2+ and inter-diffusion between multiple ions promoted apparent density in the ceramics. The substitution of isovalent Sr 2+ at Pb-site and donor pentavalent Nb 5+ at Zr/Ti-site enhanced the dielectric constant (ε RT = 2384) while decreasing the Curie temperature (T c ). The substitution of 1.5 mol% Sr evidently increased ferroelectric properties (remanent (P r = 32.66 μC/cm 2 ) and spontaneous (P s = 38.54 μC/cm 2 ) polarization), respectively. Sr-modified PLZTN showed a significant influence on the piezoelectric properties which enhanced till 1.5 mol% Sr in PLZTN ceramic system, which may be applicable for possible sensor and actuator applications

  2. Effects of air dielectric barrier discharge plasma treatment time on surface properties of PBO fiber

    International Nuclear Information System (INIS)

    Wang Qian; Chen Ping; Jia Caixia; Chen, Mingxin; Li Bin

    2011-01-01

    In this paper, the effects of air dielectric barrier discharge (DBD) plasma treatment time on surface properties of poly(p-phenylene benzobisoxazole) (PBO) fiber were investigated. The surface characteristics of PBO fiber before and after the plasma treatments were analyzed by dynamic contact angle (DCA) analysis, scanning electron microscopy (SEM), atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS). DCA measurements indicated that the surface wettability of PBO fiber was improved significantly by increasing the fiber surface free energy via air DBD plasma treatments. The results were confirmed by the improvement of adhesion of a kind of thermoplastic resin to PBO fiber which was observed by SEM, showing that more resin was adhering evenly to the fiber surface. AFM measurement revealed that the surface topography of PBO fiber became more complicated and the surface roughness was greatly enhanced after the plasma treatments, and XPS analysis showed that some new polar groups (e.g. -O-C=O) were introduced on plasma treated PBO fiber surface. The results of this study also showed that the surface properties of PBO fiber changed with the elongation of plasma treatment time.

  3. Dispersion of dielectric permittivity and magnetic properties of solid solution PZT–PFT

    Directory of Open Access Journals (Sweden)

    Skulski Ryszard

    2015-09-01

    Full Text Available In this paper we present the results of investigations into ceramic samples of solid solution (1-x(PbZr0.53Ti0.47O3- x(PbFe0.5Ta0.503 (i.e. (1-xPZT-xPFT with x = 0.25, 0.35 and 0.45. We try to find the relation between the character of dielectric dispersion at various temperatures and the composition of this solution. We also describe the magnetic properties of investigated samples. With increasing the content of PFT also mass magnetization and mass susceptibility increase (i.e. magnetic properties are more pronounced at every temperature. The temperature dependences of mass magnetization and re­ciprocal of mass susceptibility have similar runs for all the compositions. However, our magnetic investigations exhibit weak antiferromagnetic ordering instead of the ferromagnetic one at room temperature. We can also say that up to room tempera­ture any magnetic phase transition has not occurred. It may be a result of the conditions of the technological process during producing our PZT-PFT ceramics.

  4. Specific Features of the Structure and the Dielectric Properties of Sodium-Bismuth Titanate-Based Ceramics

    Science.gov (United States)

    Politova, E. D.; Golubko, N. V.; Kaleva, G. M.; Mosunov, A. V.; Sadovskaya, N. V.; Bel'kova, D. A.; Stefanovich, S. Yu.

    2018-03-01

    The phase formation, specific features, and the dielectric properties of the ceramics of compositions from the region of morphotropic interface in the (Na0.5Bi0.5)TiO3-BaTiO3 system modified by Bi(Mg0.5Ti0.5)O3 and also low-melting additions KCl, NaCl-LiF, CuO, and MnO2 that favor the control of the stoichiometry and the properties of the ceramics have been studied. The ceramics are characterized by ferroelectric phase transitions that are observed as jumps at temperatures near 400 K and maxima at T m 600 K in the temperature dependences of the dielectric permittivity. The phase transitions at 400 K demonstrate the relaxor behavior indicating the existence of polar domains in the nonpolar matrix. An increase in the content of Bi(Mg0.5Ti0.5)O3 favor a decrease in the electrical conductivity and dielectric losses of the samples, and the relative dielectric permittivity at room temperature ɛrt is retained quite high, achieving the highest values ɛrt = 1080-1350 in the ceramics modified with KCl.

  5. Phase modification and dielectric properties of a cullet-paper ash-kaolin clay-based ceramic

    Science.gov (United States)

    Samah, K. A.; Sahar, M. R.; Yusop, M.; Omar, M. F.

    2018-03-01

    Novel ceramics from waste material made of ( x) paper ash-(80 - x) cullet-20 kaolin clay (10wt% ≤ x ≤ 30wt%) were successfully synthesized using a conventional solid-state reaction technique. Energy-dispersive X-ray analysis confirmed the presence of Si, Ca, Al, and Fe in the waste material for preparing these ceramics. The influence of the cullet content on the phase structures and the dielectric properties of these ceramics were systematically investigated. The impedance spectra were verified in the range from 1 Hz to 10 MHz at room temperature. The phase of the ceramics was found to primarily consist of wollastonite (CaSiO3), along with minor phases of γ-dicalcium silicate (Ca2SiO4) and quartz (SiO2). The sample with a cullet content of 55wt% possessed the optimum wollastonite structure and exhibited good dielectric properties. An increase of the cullet content beyond 55wt% resulted in a structural change from wollastonite to dicalcium silicate, a decrease in dielectric constant, and an increase in dielectric loss. All experimental results suggested that these novel ceramics from waste are applicable for electronic devices.

  6. Phase analysis and dielectric properties of ceramics in PbO–MgO ...

    Indian Academy of Sciences (India)

    sintering these phases at 1000°C the perovskite phase content decreased. The dielectric constant of the compo- site materials formed by the ceramic route was in the region of 14 to 20 and varied little with frequency. The composites obtained by the molten salt method, however, showed much larger dielectric constants in ...

  7. Effect of Insulation Properties on the Field Grading of Solid Dielectric DC Cable

    DEFF Research Database (Denmark)

    Boggs, S.; Damon, Dwight Hill; Hjerrild, Jesper

    2001-01-01

    The development of solid dielectric dc transmission class cable is a priority throughout much of the world, to avoid risks associated with placing hydrocarbon fluids in underwater environments. The conductivity of polymeric solid dielectrics tends to be a strong function of temperature and electric...

  8. Dielectric properties of Na1–xKxNbO3 in orthorhombic phase

    Indian Academy of Sciences (India)

    Unknown

    methyl alcohol. The mixture was calcined in a platinum crucible, in air, at 950°C for 1 h. The calcined materials were weighed to ensure complete carbonate removal. The calcined ... Observed frequency dependence of dielectric constant and dielectric loss ... Temperature dependence of loss tangent in NaNbO3, at different ...

  9. 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

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

    Energy Technology Data Exchange (ETDEWEB)

    Takahashi, Susumu, E-mail: 143453501@ccalumni.meijo-u.ac.jp [Graduate School of Science and Technology, Meijo University, 1-501 Shiogamaguchi, Tempaku-ku, Nagoya 4688502 (Japan); Imai, Yusuke [National Institute of Advanced Industrial Science and Technology (AIST), 2268-98 Anagahora, Shimoshidami, Moriyama-ku, Nagoya 463-8560 (Japan); Kan, Akinori [Graduate School of Science and Technology, Meijo University, 1-501 Shiogamaguchi, Tempaku-ku, Nagoya 4688502 (Japan); Hotta, Yuji [National Institute of Advanced Industrial Science and Technology (AIST), 2268-98 Anagahora, Shimoshidami, Moriyama-ku, Nagoya 463-8560 (Japan); Ogawa, Hirotaka [Graduate School of Science and Technology, Meijo University, 1-501 Shiogamaguchi, Tempaku-ku, Nagoya 4688502 (Japan)

    2014-12-05

    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{sup −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{sub r}) of the composites ranged between 2.25 and 3.39. The estimation of ε{sub 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{sup −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.

  11. Consequence of cobalt on structural, optical and dielectric properties in ZnO nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Zia, Amir, E-mail: amirziaphysics@hotmail.com [Center for Emerging Sciences, Engineering & Technology (CESET), Islamabad (Pakistan); Ahmed, S. [Center for Emerging Sciences, Engineering & Technology (CESET), Islamabad (Pakistan); Advanced Electronics Laboratory, International Islamic University, Islamabad (Pakistan); Shah, N.A.; Anis-ur-Rehman, M. [COMSATS, Institute of Information Technology, Islamabad (Pakistan); Khan, E.U. [Center for Emerging Sciences, Engineering & Technology (CESET), Islamabad (Pakistan); Basit, M. [Centre for Solid State Physics, Punjab University (Pakistan)

    2015-09-15

    The critical role of cobalt dopant in ZnO nanostructures with different cobalt concentrations has been explored on the basis of structural, optical and dielectric mechanisms. X-ray diffraction (XRD) analysis shows that the Co{sup +2} ions replace Zn{sup +2} ions in the ZnO matrix, producing lattice strain. Diffused Reflectance Spectroscopy (DRS) shows a red shift in optical energy band gap with increase in cobalt content, along with the presence of transitions in high spin states due to tetrahedrally coordinated cobalt ions. The dielectric characterization explains the disparity in dynamic dielectric parameters like capacitance, dielectric constant, tangent loss, AC conductivity and impedance as a function of frequency. Capacitance and both static and dynamic dielectric constants found to be decreasing with cobalt addition. The anomaly in these pronounced parameters can address the key problems of the material at higher frequencies device operation.

  12. Improved dielectric properties, mechanical properties, and thermal conductivity properties of polymer composites via controlling interfacial compatibility with bio-inspired method

    Science.gov (United States)

    Ruan, Mengnan; Yang, Dan; Guo, Wenli; Zhang, Liqun; Li, Shuxin; Shang, Yuwei; Wu, Yibo; Zhang, Min; Wang, Hao

    2018-05-01

    Surface functionalization of Al2O3 nano-particles by mussel-inspired poly(dopamine) (PDA) was developed to improve the dielectric properties, mechanical properties, and thermal conductivity properties of nitrile rubber (NBR) matrix. As strong adhesion of PDA to Al2O3 nano-particles and hydrogen bonds formed by the catechol groups of PDA and the polar acrylonitrile groups of NBR, the dispersion of Al2O3-PDA/NBR composites was improved and the interfacial force between Al2O3-PDA and NBR matrix was enhanced. Thus, the Al2O3-PDA/NBR composites exhibited higher dielectric constant, better mechanical properties, and larger thermal conductivity comparing with Al2O3/NBR composites at the same filler content. The largest thermal conductivity of Al2O3-PDA/NBR composite filled with 30 phr Al2O3-PDA was 0.21 W/m K, which was 122% times of pure NBR. In addition, the Al2O3-PDA/NBR composite filled with 30 phr Al2O3-PDA displayed a high tensile strength about 2.61 MPa, which was about 255% of pure NBR. This procedure is eco-friendly and easy handling, which provides a promising route to polymer composites in application of thermal conductivity field.

  13. Influence of mashed potato dielectric properties and circulating water electric conductivity on radio frequency heating at 27 MHz.

    Science.gov (United States)

    Wang, Jian; Olsen, Robert G; Tang, Juming; Tang, Zhongwei

    2008-01-01

    Experiments and computer simulations were conducted to systematically investigate the influence of mashed potato dielectric properties and circulating water electric conductivity on electromagnetic field distribution, heating rate, and heating pattern in packaged food during radio frequency (RF) heating processes in a 6 kW, 27 MHz laboratory scale RF heating system. Both experimental and simulation results indicated that for the selected food (mashed potato) in this study, the heating rate decreased with an increase of electric conductivity of circulating water and food salt content. Simplified analytical calculations were carried out to verify the simulation results, which further indicated that the electric field distribution in the mashed potato samples was also influenced by their dielectric properties and the electric conductivity of the surrounding circulating water. Knowing the influence of water electric conductivity and mashed potato dielectric properties on the heating rate and heating pattern is helpful in optimizing the radio frequency heating process by properly adjusting these factors. The results demonstrate that computer simulation has the ability to demonstrate influence on RF heat pattern caused by the variation of material physical properties and the potential to aid the improvement on construction and modification of RF heating systems.

  14. Adsorption and electronic properties of pentacene on thin dielectric decoupling layers

    Directory of Open Access Journals (Sweden)

    Sebastian Koslowski

    2017-07-01

    Full Text Available With the increasing use of thin dielectric decoupling layers to study the electronic properties of organic molecules on metal surfaces, comparative studies are needed in order to generalize findings and formulate practical rules. In this paper we study the adsorption and electronic properties of pentacene deposited onto h-BN/Rh(111 and compare them with those of pentacene deposited onto KCl on various metal surfaces. When deposited onto KCl, the HOMO and LUMO energies of the pentacene molecules scale with the work functions of the combined KCl/metal surface. The magnitude of the variation between the respective KCl/metal systems indicates the degree of interaction of the frontier orbitals with the underlying metal. The results confirm that the so-called IDIS model developed by Willenbockel et al. applies not only to molecular layers on bare metal surfaces, but also to individual molecules on thin electronically decoupling layers. Depositing pentacene onto h-BN/Rh(111 results in significantly different adsorption characteristics, due to the topographic corrugation of the surface as well as the lateral electric fields it presents. These properties are reflected in the divergence from the aforementioned trend for the orbital energies of pentacene deposited onto h-BN/Rh(111, as well as in the different adsorption geometry. Thus, the highly desirable capacity of h-BN to trap molecules comes at the price of enhanced metal–molecule interaction, which decreases the HOMO–LUMO gap of the molecules. In spite of the enhanced interaction, the molecular orbitals are evident in scanning tunnelling spectroscopy (STS and their shapes can be resolved by spectroscopic mapping.

  15. Change in Dielectric Properties in the Microwave Frequency Region of Polypyrrole–Coated Textiles during Aging

    Directory of Open Access Journals (Sweden)

    Eva Hakansson

    2016-07-01

    Full Text Available Complex permittivity of conducting polypyrrole (PPy-coated Nylon-Lycra textiles is measured using a free space transmission measurement technique over the frequency range of 1–18 GHz. The aging of microwave dielectric properties and reflection, transmission and absorption for a period of 18 months is demonstrated. PPy-coated fabrics are shown to be lossy over the full frequency range. The levels of absorption are shown to be higher than reflection in the tested samples. This is attributed to the relatively high resistivity of the PPy-coated fabrics. Both the dopant concentration and polymerisation time affect the total shielding effectiveness and microwave aging behaviour. Distinguishing either of these two factors as being exclusively the dominant mechanism of shielding effectiveness is shown to be difficult. It is observed that the PPy-coated Nylon-Lycra samples with a p-toluene sulfonic acid (pTSA concentration of 0.015 M and polymerisation times of 60 min and 180 min have 37% and 26% decrease in total transmission loss, respectively, upon aging for 72 weeks at room temperature (20 °C, 65% Relative humidity (RH. The concentration of the dopant also influences the microwave aging behaviour of the PPy-coated fabrics. The samples with a higher dopant concentration of 0.027 mol/L pTSA are shown to have a transmission loss of 32.6% and 16.5% for short and long polymerisation times, respectively, when aged for 72 weeks. The microwave properties exhibit better stability with high dopant concentration and/or longer polymerization times. High pTSA dopant concentrations and/or longer polymerisation times result in high microwave insertion loss and are more effective in reducing the transmission and also increasing the longevity of the electrical properties.

  16. Dielectric and Magnetic Properties of Two-Phase Composite System: Mn-Zn or Ni-Zn ferrites in Dielectric Matrices

    Science.gov (United States)

    Salem, Mohamed M.; Morchenko, Alexander T.; Panina, Larissa V.; Kostishyn, Vladimir G.; Andreev, Valery G.; Bibikov, Sergey B.; Nikolaev, Alexey N.

    The development of novel electromagnetic materials for various applications largely depends on ferrite composites with optimal combination of constituent elements. The evaluation of their dielectric and magnetic properties is important in understanding the physical properties and potential for specific use. In this work, permittivity and permeability spectra of composite materials based on granulated soft magnetic Mn-Zn and Ni-Zn ferrites in paraffin, polyvinyl acetate glue and silicone sealant matrices were investigated for different ferrite phase concentrations and ferrite granule sizes. Mn-Zn ferrites are characterized by a relatively large conductivity and their composites show unusual behavior for the real part of the permittivity which can be essentially higher than the values observed for bulk ferrite samples, especially at low frequencies. The permittivity spectra also demonstrate a strong frequency dispersion which is not seen for bulk ceramic ferrites. Ni-Zn ferrite composites with very large electrical resistance do not show these effects and their microwave properties are consistent with the behavior of the constituent phases. The observed permittivity enhancement is explained on the basis of the conductive properties of the ferrite granules and the equivalent capacitance effect. The effective permittivity calculated from an equivalent capacitor circuit gives a qualitative agreement with the experimental data at lower frequencies. However, the origin of the frequency dispersion remains unclear. The developed composites have a potential for applications in broadband absorbers since they combine magnetic and electric losses along with a strong frequency dispersion of the permittivity.

  17. Effects of La{sub 2}O{sub 3}-doping and sintering temperature on the dielectric properties of BaSrTiO{sub 3} ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Hong Wei; Chang, Chun Rui [College of Science, North China University of Science and Technology, Hebei Province (China); Li, Yuan Liang [Hebei Provincial Key Laboratory of Inorganic Nonmetallic Materials, North China University of Science and Technology, Hebei Province (China); Yan, Chun Liang [Analysis and Testing Center, North China University of Science and Technology, Hebei Province (China)

    2016-03-15

    Using BaCO{sub 3}, SrCO{sub 3} and TiO{sub 2}, et al as crude materials, La{sub 2}O{sub 3} as dopant, Ba{sub 0.8}Sr{sub 0.2}TiO{sub 3} (BST) Ceramics of perovskite structure were prepared by solid state reaction method. We investigated the effects of La{sub 2}O{sub 3} -doping and sintering temperature on the dielectric properties of BaSrTiO{sub 3} ceramics. The experiment results show that: The amount of La{sub 2}O{sub 3} can increase the dielectric constant of the sample, with the doping amount increasing, the dielectric constant increases. The sintering temperature has also significant impact on the dielectric properties. The dielectric constant of the sample reaches its highest point at 1280 °C. (author)

  18. Heat treatment effects on dielectric properties of SRFe{sub 12}O{sub 19} hexaferrite prepared by an SHS route

    Energy Technology Data Exchange (ETDEWEB)

    Panchal, Nital R.; Jotania, Rajshree B., E-mail: natal_panchal@yahoo.co.in, E-mail: rbjotania@gmail.com [Department of Physics, University School of Sciences, Gujarat University, Ahmedabad (India)

    2011-07-01

    The M-type Strontium Hexaferrite SRFe{sub 12}O{sub 19} particles were prepared by a Self propagating High temperature Synthesis (SHS) route. Precursors were heated under two different conditions: microwave heating for 30 minutes and sintered at 950 deg C for 4 hrs. The dielectric properties: dielectric constant ({epsilon}{sup '}), dielectric loss (tan {delta} ) and ac conductivity ({sigma}{sub ac}) were measured at room temperature in the frequency range from 100 Hz to 2 MHz. The samples present a non-linear behavior for the dielectric constant at 1 kHz, 100 kHz and 2 MHz. The dielectric properties of prepared Strontium Hexaferrite samples were discussed in view of applications as a material for microwave devices, permanent magnets and high density magnetic recording media. (author)

  19. Facile synthesis, dielectric properties and electrocatalytic activities of PMMA-NiFe{sub 2}O{sub 4} nanocomposite

    Energy Technology Data Exchange (ETDEWEB)

    Maji, Pranabi; Choudhary, Ram Bilash, E-mail: rbcism@gmail.com

    2017-06-01

    The paper deals with the dielectric and catalytic properties of poly (methyl methacrylate)-nikel ferrite (PMMA-NiFe{sub 2}O{sub 4}) nanocomposite. The nanocomposite was prepared by using a general and facile synthesis strategy. Fourier transform infrared (FTIR) and X-ray diffraction (XRD) spectra confirmed the formation of PMMA-NiFe{sub 2}O{sub 4} nanocomposite. Field effect scanning electron microscopic (FESEM) and transmission electron microscopic (TEM) images revealed that NiFe{sub 2}O{sub 4} nanoparticles were uniformly distributed and were tightly adhered with PMMA matrix owing to surface modification with 3-methacryloyloxy propyl trimethoxy silane (KH-570). Thermal stability was enhanced by incorporation of NiFe{sub 2}O{sub 4} nanofillers. The nanocomposite showed high dielectric constant and low dielectric loss. The achieved dielectric and thermal property inferred the potential application of this material in energy storage and embedded electronics devices. Further, the as prepared nanocomposite also offered a remarkable electrochemical performance towards hydrogen peroxide (H{sub 2}O{sub 2}) sensing. - Highlights: • PMMA-NiFe{sub 2}O{sub 4} nanocomposite was synthesized via free radical polymerization. • The nanocomposite exhibited high value of dielectric constant (51) and tanδ (0.3). • Thermal stability of the PMMA matrix was improved by the incorporation of NiFe{sub 2}O{sub 4.} • The H{sub 2}O{sub 2} detection limit was estimated 44 μM when signal to noise (S/N) ration was 3. • The electrochemical sensitivity of H{sub 2}O{sub 2} was calculated 0.6727 μA mM{sup -1}.

  20. Effect of Dielectric Properties of a Solvent-Water Mixture Used in Microwave-Assisted Extraction of Antioxidants from Potato Peels

    Directory of Open Access Journals (Sweden)

    Ashutosh Singh

    2014-02-01

    Full Text Available The dielectric properties of a methanol-water mixture were measured at different temperatures from 20 to 80 °C at two frequencies 915 MHz and 2450 MHz. These frequencies are most commonly used on industrial and domestic scales respectively. In this study, the dielectric properties of a methanol-water mixture were found to be dependent on temperature, solvent concentration, and presence of plant matrix. Linear and quadratic equations were developed to establish the dependency between factors. At 2450 MHz, the dielectric constant of methanol-water mixtures was significantly affected by concentration of methanol rather than by temperature, whereas the dielectric loss factor was significantly affected by temperature rather than by methanol concentration. Introduction of potato peel led to an increase in the effect of temperature on the dielectric properties of the methanol fractions. At 915 MHz, both the dielectric properties were significantly affected by the increase in temperature and solvent concentration, while the presence of potato peel had no significant effect on the dielectric properties. Statistical analysis of the dissipation factor at 915 and 2450 MHz revealed that both temperature and solvent concentration had a significant effect on it, whereas introduction of potato peels at 915 MHz reduced the effect of temperature as compared to 2450 MHz. The total phenolic yield of the microwave-assisted extraction process was significantly affected by the solvent concentration, the dissipation factor of the methanol-water mixture and the extraction time.

  1. Study of dielectric properties of biodegradable composites using (Poly)lactic acid and Luffa fiber

    Science.gov (United States)

    Parida, Chhatrapati; Patra, Subhasree; Mohanta, Kamal lochan; Dash, Sarat kumar; Parashar, S. K. S.

    2017-05-01

    Composites were made from bio degradable polymer (poly)lactic acid and lignocellulosic materials derived from natural fibers of luffa cylindrica using injection moulding technique. Before reinforcement in the poymer, the fibers were subjected to chemical treatments like alkali treatment, bleaching and acid hydrolysis. Frequency dependence of dielectric parameters like dielectric constant, di electric loss and ac conductivity of the composites were investigated in the frequency range from 1000Hz to 1MHz. The effect of wt of fiber in the composites on the above mentioned dielectric parameters were also evaluated. The experimental results show that the values of dielectric constant, ac conductivity and loss factor increase with increase in wt of fiber in the polymer matrix. However when fibers exposed to alkali treatment, bleaching and acid hydrolysis were incorporated in to the matrix, the composites showed inferior dielectric response compared to composites having fibers exposed to alkali treatment and bleaching only. It was also found that dielectric constant and dielectric loss factor of all the composite samples decreased with increase in frequency of the applied field. However, the ac conductivity of all the samples is found to increase with increase in frequency.

  2. Thermodynamic theory of intrinsic finite size effects in PbTiO3 nanocrystals. II. Dielectric and piezoelectric properties

    Science.gov (United States)

    Akdogan, E. K.; Safari, A.

    2007-03-01

    We compute the intrinsic dielectric and piezoelectric properties of single domain, mechanically free, and surface charge compensated PbTiO3 nanocrystals (n-Pt) with no depolarization fields, undergoing a finite size induced first order tetragonal→cubic ferrodistortive phase transition. By using a Landau-Devonshire type free energy functional, in which Landau coefficients are a function of nanoparticle size, we demonstrate substantial deviations from bulk properties in the range <150 nm. We find a decrease in dielectric susceptibility at the transition temperature with decreasing particle size, which we verify to be in conformity with predictions of lattice dynamics considerations. We also find an anomalous increase in piezocharge coefficients near ˜15 nm , the critical size for n-Pt.

  3. Dielectric properties and soft modes in semiconducting (Pb, Sn, Ge)Te

    Science.gov (United States)

    Jantsch, W.

    The narrow-gap semiconductors PbTe, SnTe, GeTe and their alloys exhibit a tendency for a ferroelectric displacive phase transition from a high-temperature rocksalt structure to a rhombohedral phase at low temperatures. The critical temperatures vary within an exceedingly wide range: -70 K(PbTe) up to 650 K(GeTe). Owing to the outstanding simplicity of their crystal structure and their well-known electronic properties, the instability and the chemical trends of Tc can be understood in terms of a quantitative pseudopotential model (Sect.5.2). Phenomenological models explain the temperature dependence of the soft mode outside the critical regime fairly well (Sect.5.1). Critical phenomena, however, deserve further attention: the anomalies of the static dielectric constant (Sects.3.1 and 5.3) and the influence of defects are possibly related to a central peak. Additional systematic investigations on the nature and influence of defects are required to obtain more insight into this highly interesting field of general importance.

  4. High-Temperature Dielectric Properties of Aluminum Nitride Ceramic for Wireless Passive Sensing Applications.

    Science.gov (United States)

    Liu, Jun; Yuan, Yukun; Ren, Zhong; Tan, Qiulin; Xiong, Jijun

    2015-09-08

    The accurate characterization of the temperature-dependent permittivity of aluminum nitride (AlN) ceramic is quite critical to the application of wireless passive sensors for harsh environments. Since the change of the temperature-dependent permittivity will vary the ceramic-based capacitance, which can be converted into the change of the resonant frequency, an LC resonator, based on AlN ceramic, is prepared by the thick film technology. The dielectric properties of AlN ceramic are measured by the wireless coupling method, and discussed within the temperature range of 12 °C (room temperature) to 600 °C. The results show that the extracted relative permittivity of ceramic at room temperature is 2.3% higher than the nominal value of 9, and increases from 9.21 to 10.79, and the quality factor Q is decreased from 29.77 at room temperature to 3.61 at 600 °C within the temperature range.

  5. High-Temperature Dielectric Properties of Aluminum Nitride Ceramic for Wireless Passive Sensing Applications

    Directory of Open Access Journals (Sweden)

    Jun Liu

    2015-09-01

    Full Text Available The accurate characterization of the temperature-dependent permittivity of aluminum nitride (AlN ceramic is quite critical to the application of wireless passive sensors for harsh environments. Since the change of the temperature-dependent permittivity will vary the ceramic-based capacitance, which can be converted into the change of the resonant frequency, an LC resonator, based on AlN ceramic, is prepared by the thick film technology. The dielectric properties of AlN ceramic are measured by the wireless coupling method, and discussed within the temperature range of 12 °C (room temperature to 600 °C. The results show that the extracted relative permittivity of ceramic at room temperature is 2.3% higher than the nominal value of 9, and increases from 9.21 to 10.79, and the quality factor Q is decreased from 29.77 at room temperature to 3.61 at 600 °C within the temperature range.

  6. Current-voltage hysteresis and dielectric properties of PVA coated MWCNT film

    Science.gov (United States)

    Das, Amit Kumar; Meikap, Ajit Kumar

    2017-12-01

    In this work, we have prepared polyvinyl alcohol (PVA) coated multiwall carbon nanotube (MWCNT) film by an in situ chemical oxidative preparation technique. The thermogravimetric analysis clearly explains the thermal degradation of pure polymer and polymer nanocomposite film. We have studied the AC electrical transport properties and current-voltage (I-V) characteristic of PVA-MWCNT composites within the temperature range 300 ≤ T ≤ 423 K and frequency range 150 Hz ≤ f ≤ 2 MHz. It is observed that the dielectric constant of the composite film increases significantly. The frequency variation of AC conductivity follows the power law ( ωS ) and a sharp transition from small polaron tunneling to correlated barrier hopping model is found. The imaginary part of electric modulus shows non-Debye type asymmetric behaviour. The impedance spectroscopy shows the negative temperature coefficient of resistance of the composite film. Nyquist plot of the composite film at different temperatures is established from impedance measurement. The current-voltage characteristic (under ± 20 V) shows hysteresis behaviour and field dependent resistance. We simulate the experimentally observed current density-electric field data with the established theory.

  7. Structural and magneto-dielectric property of (1-x)SBT-xLSMO nanocomposite thin films

    International Nuclear Information System (INIS)

    Maity, Sarmistha; Bhattacharya, D.; Dhar, A.; Ray, S.K.

    2009-01-01

    Full text: In recent years, interest in multiferroic materials has been increasing due to their potential applications. As single-phase multiferroic materials have very low room temperature magnetoelectric coefficient, recent studies have been concentrated on the possibility of attaining a coupling between the two order parameters by designing composites with magnetostrictive and piezoelectric phases via stress mediation. Composite thin films with homogenous matrix, composition spread with terminal layers being ferromagnetic and ferroelectric, layer-by-layer growth, superlattices, as well as epitaxial growth of ferromagnetic and ferroelectric layers on suitable substrates are been currently considered. In the present work, a nanostructured composite thin film of strontium bismuth tantalate (SBT) (ferroelectric layer) and lanthanum strontium manganese oxide (LSMO) (ferromagnetic layer) were fabricated using pulsed laser deposition. Phase separated multiferroic thin films with thickness varying from 50nm to 150nm were deposited from composite target (1-x)SBT-xLSMO with x=0.2, 0.5, 0.8. Grazing angle X-ray diffraction study combined with photo electron spectroscopy with depth profiling was carried out to study the phase separation. Interface quality of the thin film on silicon substrate was studied by Rutherford backscattering spectroscopy. Influence of film thickness and composition (x) on the electrical property of film was examined using impedance spectroscopy. The composite films exhibited ferroelectric as well as ferromagnetic characteristics at room temperature. A small kink in the dielectric spectra near the Neel temperature of LSMO confirmed the magneto-electric effect in the nanocomposite films

  8. Dielectric properties for SF6 and SF6 mixtures predicted from basic data

    International Nuclear Information System (INIS)

    Kline, L.E.; Davies, D.K.; Chen, C.L.; Chantry, P.J.

    1978-01-01

    α and eta, the ionization and attachment coefficients, and (E/N)*, the limiting breakdown electric field-to-gas density ratio, in SF 6 and SF 6 mixtures were calculated by numerically solving the Boltzmann equation for the electron energy distribution. The calculations require a knowledge of several electron collision cross sections. Published momentum transfer and ionization cross sections for SF 6 were used. Various attachment cross sections for SF 6 were measured by using electron beam techniques with mass spectrometric ion detection. A total cross section for electronic excitation of SF 6 was determined by comparing the predicted values of α, eta, and (E/N)* with measured values obtained from spatial current growth experiments in SF 6 in uniform fields over an extended range of E/N. With this self-consistent set of SF 6 cross sections, together with published He cross sections, it was then possible to predict the dielectric properties of SF 6 --He mixtures. Published experimental values of α for these mixtures lie between the values of α calculated with and without ionization of SF 6 by excited He atoms. Published experimental values of (E/N)* agree with the calculations to within 5%. 11 figures

  9. Optical and dielectrical properties of 2-hydroxy-1-naphthylideneaniline and its derivatives

    Energy Technology Data Exchange (ETDEWEB)

    El-Ghamaz, N.A. [Physics Department, Faculty of Science, Damietta University, Damietta 34517 (Egypt); Shoair, A.F., E-mail: abdel_shoair@yahoo.com [Chemistry Department, Faculty of Science, Damietta University, Damietta 34517 (Egypt); El-Shobaky, A.R.; Abo-Yassin, H.R. [Chemistry Department, Faculty of Science, Damietta University, Damietta 34517 (Egypt)

    2016-08-15

    The optical and electrical properties of 2-Hydroxy-1-naphthylideneaniline and its derivatives (HL{sub n}) have been investigated. The spectral distribution of absorption (α) coefficient for the ligands HL{sub 1} and HL{sub 4} showed five absorption peaks and shoulders which are assigned as π–π* and n–π* transitions. The optical energy gap (E{sub g}) for HL{sub 1} and HL{sub 4} is investigated and found to be in the range of 2.09–2.27 eV depending on the function group and the type of electronic transition. The ac conductivity measurements showed a semiconductor behavior. The electrical conduction mechanism was also investigated and found to be correlated barrier-hopping (CBH) and quantum mechanical tunneling (QMT) mechanisms depending on the function group. The effect of adsorbed NH{sub 3} gas on the electrical conductivity and dielectric constants of ligand HL{sub 3} was also investigated.

  10. Structural, dielectric and magnetic properties of cobalt ferrite prepared using auto combustion and ceramic route

    International Nuclear Information System (INIS)

    Murugesan, C.; Perumal, M.; Chandrasekaran, G.

    2014-01-01

    Cobalt ferrite is synthesized by using low temperature auto combustion and high temperature ceramic methods. The prepared samples have values of lattice constant equal to 8.40 Å and 8.38 Å for auto combustion and ceramic methods respectively. The FTIR spectrum of samples of the auto combustion method shows a high frequency vibrational band at 580 cm −1 assigned to tetrahedral site and a low frequency vibrational band at 409 cm −1 assigned to octahedral site which are shifted to 590 cm −1 and 412 cm −1 for the ceramic method sample. SEM micrographs of samples show a substantial difference in surface morphology and size of the grains between the two methods. The frequency dependent dielectric constant and ac conductivity of the samples measured from 1 Hz to 2 MHz at room temperature are reported. The room temperature magnetic hysteresis parameters of the samples are measured using VSM. The measured values of saturation magnetization, coercivity and remanent magnetization are 42 emu/g, 1553 Oe, 18.5 emu/g for the auto combustion method, 66.7 emu/g, 379.6 Oe, and 17.3 emu/g for the ceramic method, respectively. The difference in preparation methods and size of the grains causes interesting changes in electrical and magnetic properties

  11. Dielectric properties for SF6 and SF6 mixtures predicted from basic data

    International Nuclear Information System (INIS)

    Kline, L.E.; Davies, D.K.; Chen, C.L.; Chantry, P.J.

    1979-01-01

    We have calculated α and eta, the ionization and attachment coefficients, and (E/N) *, the limiting breakdown electric-field--to--gas-density ratio, in SF 6 and SF 6 mixtures by numerically solving the Boltzmann equation for the electron energy distribution. The calculations require a knowledge of several electron collision cross sections. Published momentum transfer and ionization cross sections for SF 6 were used. We measured various attachment cross sections for SF 6 using electron-beam techniques with mass spectrometric ion detection. We determined a total cross section for electronic excitation of SF 6 by comparing the predicted values of α, eta, and (E/N) * with our measured values obtained from spatial current growth experiments in SF 6 in uniform fields over an extended range of E/N. With this self-consistent set of SF 6 cross sections, together with published He and N 2 cross sections, it was then possible to predict the dielectric properties of SF 6 -He and SF 6 -N 2 mixtures. Published experimental values of α for the SF 6 -He mixtures lie between the values of α calculated with and without ionization of SF 6 by excited He atoms. Published experimental values of (E/N) * agree with our calculations to within 5% in both the SF 6 -He and the SF 6 -N 2 mixtures

  12. Effect of SrTiO3 on dielectric and piezoelectric properties of NBT

    Science.gov (United States)

    Rajani Malathi, A.; Kumar, G. S.; Prasad, G.

    2015-02-01

    Composites of (1 - x)Na0.5Bi0.5TiO3-(x)SrTiO3, where x = 0.05, 0.10, 0.15, 0.2, 0.3 and 0.9 are studied. Individual compounds are synthesized by sol gel, and composites are prepared by solid-state sintering process. Through the analysis of X-ray diffraction, lattice parameters are obtained and, from scanning electron microscope (SEM), micro-structure of the samples is observed. The depolarization temperature (Td) and the Curie temperature (Tc) are determined from dielectric studies. Relaxor behavior of the samples is interpreted using modified Curie Weiss law. Control of polarization in sodium bismuth titanate (NBT) is achieved using strontium titanate (SrTiO3-ST) and studied through polarization vs. electric field (PE) loops and piezoelectric measurements. The intra-granual and inter-granual effects on the electrical properties of the ceramics are studied from impedance analysis.

  13. Structural, magnetic, dielectric and bonding properties of BiMnO3 grown by co-precipitation technique

    Directory of Open Access Journals (Sweden)

    S. Hanif

    Full Text Available In this work, powders of BiMnO3 (BMO are prepared by using co-precipitation method. The effect of sintering temperature on the physical properties is observed. The X-ray diffraction (XRD reveals monoclinic structure, while the surface morphology observed by scanning electron microscopy (SEM indicates sintering temperature dependent grain growth and an increased surface uniformity. The paramagnetic behavior is exhibited by the grown samples at room temperature (RT, which is due to the ordering temperature well below RT. The dielectric constant and the dielectric loss decay with frequency, which is due to the dipole relaxation. Moreover, Mn–O and Bi–O vibrational bands have been observed in the range 800–850 cm−1 and 500–600 cm−1, respectively. The prepared samples find potential application as a multiferroic material, with simultaneous control over both the magnetism and the dielectric characteristics. Keywords: Multiferroics, Paramagnetism, Co-precipitation, Dielectric constant, Surface morphology

  14. Zirconium titanate thin film prepared by surface sol-gel process and effects of thickness on dielectric property

    CERN Document Server

    Kim, C H

    2002-01-01

    Single phase of multicomponent oxide ZrTiO sub 4 film could be prepared through surface sol-gel route simply by coating the mixture of 100mM zirconium butoxide and titanium butoxide on Pt/Ti/SiO sub 2 /Si(100) substrate, following pyrolysis at 450 .deg. C, and annealing it at 770 .deg. C. The dielectric constant of the film was reduced as the film thickness decreased due to of the interfacial effects caused by layer/electrode and a few voids inside the multilayer. However, the dielectric property was independent of applied dc bias sweeps voltage (-2 to +2 V). The dielectric constant of bulk film, 31.9, estimated using series-connected capacitor model was independent of film thickness and frequency in the measurement range, but theoretical interfacial thickness, t sub i , was dependent on the frequency. It reached a saturated t sub i value, 6.9 A, at high frequency by extraction of some capacitance component formed at low frequency range. The dielectric constant of bulk ZrTiO sub 4 pellet-shaped material was 3...

  15. Ferromagnetic resonance and dielectric and magnetic properties of pure and diluted ferrites in millimeter waves

    Science.gov (United States)

    Afsar, Mohammed N.; Chen, Shu; Korolev, Konstantin A.

    2009-04-01

    Transmittance measurements on pure and diluted barium ferrites, nickel zinc manganese ferrites, and nickel cobalt copper ferrites in millimeter wave-frequency range from 30to120GHz have been performed for the first time. A free space millimeter wave magneto-optical approach has been successfully employed for the dielectric and magnetic characterization of ferrite materials. Simultaneous determination of dielectric permittivity and magnetic permeability has been carried out from a single set of transmittance measurements. Frequency dependences of the magnetic permeability and dielectric permittivity on pure and diluted ferrites in millimeter waves have been obtained.

  16. Dielectric materials for electrical engineering

    CERN Document Server

    Martinez-Vega, Juan

    2013-01-01

    Part 1 is particularly concerned with physical properties, electrical ageing and modeling with topics such as the physics of charged dielectric materials, conduction mechanisms, dielectric relaxation, space charge, electric ageing and life end models and dielectric experimental characterization. Part 2 concerns some applications specific to dielectric materials: insulating oils for transformers, electrorheological fluids, electrolytic capacitors, ionic membranes, photovoltaic conversion, dielectric thermal control coatings for geostationary satellites, plastics recycling and piezoelectric poly

  17. Correlation between infrared, THz and microwave dielectric properties of vanadium doped antiferroelectric BiNbO.sub.4./sub..

    Czech Academy of Sciences Publication Activity Database

    Kamba, Stanislav; Wang, H.; Berta, Milan; Kadlec, Filip; Petzelt, Jan; Zhou, D.; Yao, X.

    2006-01-01

    Roč. 26, - (2006), s. 2861-2865 ISSN 0955-2219 R&D Projects: GA ČR(CZ) GA202/04/0993; GA MŠk(CZ) OC 525.20 Institutional research plan: CEZ:AV0Z10100520 Keywords : sintering * spectroscopy * dielectric properties * insulators * microwave resonators Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.576, year: 2006

  18. Effect of nano-silica on dielectric properties and space charge behavior of epoxy resin under temperature gradient

    Science.gov (United States)

    Li, Yuanyuan; Tian, Muqin; Lei, Zhipeng; Zhang, Jianhua

    2018-03-01

    Epoxy resin (EP) nanodielectrics with the mass fraction of nano-silica (SiO2) between 0 and 5 wt% were manufactured. The influence of SiO2 content on the dielectric properties of EP nanodielectrics was studied. It is found that the dielectric properties are the best when the SiO2 content is 0.5 wt%. We further tested and analyzed the dielectric properties of pure EP and EP nanodielectrics with 0.5 wt% SiO2 at the temperature ranging from 40 to 200 °C. The results show that the complexity permittivity and space charge accumulation of the samples increase significantly at low frequency and the temperature above T g. The complexity permittivity and space charge accumulation of the nanocomposites with the loading of 0.5 wt%, however, are smaller than that of pure EP. These results indicate that the interface area between nano-silica and EP matrix suppresses the motions of molecular chains and the migration of charge carriers.

  19. Microwave Dielectric Properties of XM46 and a Surrogate Liquid Propellant

    National Research Council Canada - National Science Library

    Bossoli, Robert

    1998-01-01

    .... The dielectric constant (permittivity) of LP was determined in support of possible studies of the feasibility of using microwave energy to preheat LP for more consistent electric ignition in regenerative liquid propellant guns (RLPG...

  20. Effect of Pre-Strain on the Dielectric and Dynamic Mechanical Properties of HSIII Silicone

    National Research Council Canada - National Science Library

    Szabo, J. P; Underhill, R. S; Rawji, M; Keough, I. A

    2006-01-01

    ...% uni-axial pre strain. The mechanical loss factor was unaffected by pre strain. The real and imaginary parts of the complex dielectric permittivity were also unaffected by the application of a biaxial pre strain...

  1. Midfield microscope : Exploring the extraordinary

    NARCIS (Netherlands)

    Docter, M.W.

    2008-01-01

    In this thesis the development of the midfield microscope is presented. This is a microscope in which the extraordinary transmission (EOT) through sub-wavelength hole-arrays is applied. Before trying to combine microscopy and EOT, we look at them separately. In chapter 1 an overview is given of the

  2. Comparative study of dielectric properties of MgNb2O6 prepared by ...

    Indian Academy of Sciences (India)

    Unknown

    Wakino K, Nishikawa T, Ishikawa Y and Tamura H 1990 Br. Ceram. Trans. J. 89 39. Yoon K H, Cho Y S and Kang D H 1995 J. Mater. Sci. 30 4244. Figure 5. Variation of the dielectric constant (ε) and dielectric loss (D) with frequency at room temperature for. MgNb2O6 prepared by the molten salt method. Figure 6. Variation ...

  3. Dielectric properties of Na1–xKxNbO3 in orthorhombic phase

    Indian Academy of Sciences (India)

    Unknown

    σ = ε0ωK tan δ, where ε0 is the permittivity of free space, tan δ the loss tangent, and ω = 2πf, f the applied frequency. 5. Results and discussion. Observed frequency dependence of dielectric constant and dielectric loss, at room temperature, for different x values in Na1–xKxNbO3 samples has been shown in fig- ures 3 and 4, ...

  4. Investigations on electrical conductivity and dielectric properties of Na doped ZnO synthesized from sol gel method

    Energy Technology Data Exchange (ETDEWEB)

    Tabib, Asma; Sdiri, Nasr [Laboratoire de Physico-Chimie des Matériaux Minéraux et leurs Applications, Centre National de Recherches en Sciences des Matériaux, B.P. 95 Hammam-Lif, 2050 (Tunisia); Elhouichet, Habib, E-mail: habib.elhouichet@fst.rnu.tn [Laboratoire de Physico-Chimie des Matériaux Minéraux et leurs Applications, Centre National de Recherches en Sciences des Matériaux, B.P. 95 Hammam-Lif, 2050 (Tunisia); Département de Physique, Faculté des Sciences de Tunis, University Tunis El Manar, Tunis 2092 (Tunisia); Férid, Mokhtar [Laboratoire de Physico-Chimie des Matériaux Minéraux et leurs Applications, Centre National de Recherches en Sciences des Matériaux, B.P. 95 Hammam-Lif, 2050 (Tunisia)

    2015-02-15

    Highlights: • ZnO nanoparticles doped with Na were prepared from sol-gel method. • Electric conductivity and dielectric properties were investigated. • The ZnO conductivity is estimated to be of p-type for critical Na doping of 1.5% at. - Abstract: Na doped ZnO nanoparticles (NPs) were elaborated by sol gel technique. The X-ray diffraction patterns show that the peaks are indexed to the hexagonal structure without any trace of an extra phase. Electric and dielectric properties were investigated using complex impedance spectroscopy. The impedance spectra were analyzed in terms of equivalent circuits involving resistors, capacitors and constant phase elements (CPE). The contribution of grain boundary resistance to the total resistance of the system is remarkable. The AC conductivity increases with temperature following the Arrhenius law, with single apparent activation energy for conduction process. The frequency dependence of the electric conductivity follows a simple power law behavior, in according to relation σ{sub AC}(ω) = σ(0) + A ω{sup s}, where s is smaller than 1. The analysis of dc conductivity indicates that the conduction is ionic in nature. The study of its variation, at fixed temperature, with Na content shows sharp decrease which is explained by the formation of Na{sub Zn} acceptor. It was found that the dc conductivity reaches its minimum value for critical Na concentration of 1.5% at which the conductivity is estimated to be of p-type. Impedance and modulus study reveals the temperature dependent non-Debye type relaxation phenomenon. Dielectric studies revealed a promising dielectric properties (relatively high ε′ at low frequencies and low loss at high frequencies). In the low-frequency region, the values of M′ tends to zero suggesting negligible or absent electrode polarization phenomenon. The frequency dependent maxima in the imaginary modulus are found to obey to Arrhenius law.

  5. Thermal, optical and dielectric properties of phase stabilized δ - Dy-Bi2O3 ionic conductors

    Science.gov (United States)

    Bandyopadhyay, Swagata; Dutta, Abhigyan

    2017-03-01

    In this work, we have investigated the thermal, structural, optical and dielectric properties of Bi1-xDyxO1.5-δ (0.10≤x≤0.40) ionic conductors prepared by citrate auto-ignition method. The Thermo gravimetric-DTA analysis and X-Ray Diffraction pattern confirm the single δ-phase stabilization of doped system beyond 25 mol% doping concentration. XRD analysis also indicates that average crystallite size is maximum and micro strain is minimum for Bi0.75Dy0.25O1.5-δ composition. The optical band gap of the prepared compositions is obtained from the Ultraviolet- Visible spectroscopy that shows a red shift with the increase in Dy content. The presence of different structural bonds is confirmed from FT-IR spectroscopy analysis. Ionic transport property of the prepared compositions has been analyzed using Nyquist plot for dc conduction and Nernst-Einstein relation for ac conduction mechanism. This analysis indicates that the composition Bi0.75Dy0.25O1.5-δ shows highest conductivity. The dielectric properties of these ionic conductors have been analyzed using Havriliak-Negami (HN) formalism. The dielectric permittivity ε' (ω) of all the prepared compositions is found to be within the range 1.61-3.63(x102) in S.I. unit. Analysis of electric modulus data reveals that dielectric and modulus relaxation follows same mechanism. The time-temperature superposition principle has been verified from the scaling of modulus spectra.

  6. Structural, magnetic, and dielectric properties of multiferroic Co1−xMgxCr2O4 nanoparticles

    International Nuclear Information System (INIS)

    Kamran, M.; Ullah, A.; Rahman, S.; Tahir, A.; Nadeem, K.; Anis ur Rehman, M.; Hussain, S.

    2017-01-01

    Highlights: • Properties of multiferroic Co 1−x Mg x Cr 2 O 4 nanoparticles have been studied. • XRD showed that CoCr 2 O 4 and MgCr 2 O 4 are cubic normal spinel structure. • Rietveld refinement of XRD showed no impurity phases. • T c and T s showed decreasing trend with increasing Mg concentration. • Dielectric properties were improved for x = 0.6 Mg concentration. - Abstract: We examined the structural, magnetic, and dielectric properties of Co 1−x Mg x Cr 2 O 4 nanoparticles with composition x = 0, 0.2, 0.4, 0.5, 0.6, 0.8 and 1 in detail. X-ray diffraction (XRD) revealed normal spinel structure for all the samples. Rietveld refinement fitting results of the XRD showed no impurity phases which signifies the formation of single phase Co 1−x Mg x Cr 2 O 4 nanoparticles. The average crystallite size showed a peak behaviour with maxima at x = 0.6. Raman and Fourier transform infrared (FTIR) spectroscopy also confirmed the formation of single phase normal spinel for all the samples and exhibited dominant vibrational changes for x ≥ 0.6. For x = 0 (CoCr 2 O 4 ), zero field cooled/field cooled (ZFC/FC) magnetization curves showed paramagnetic (PM) to ferrimagnetic (FiM) transition at T c = 97 K and a conical spiral magnetic order at T s = 30 K. The end members CoCr 2 O 4 (x = 0) and MgCr 2 O 4 (x = 1) are FiM and antiferromagnetic (AFM), respectively. T c and T s showed decreasing trend with increasing x, followed by an additional AFM transition at T N = 15 K for x = 0.6. The system finally stabilized and changed to highly frustrated AFM structure at x = 1 due to formation of pure MgCr 2 O 4 . High field FC curves (5T) depicted nearly no effect on spiral magnetic state, which is attributed to strong exchange B-B magnetic interactions at low temperatures. Dielectric parameters showed a non-monotonous behaviour with Mg concentration and were explained with the help of Maxwell-Wagner model and Koop’s theory. Dielectric properties were improved for

  7. A Facile Strategy to Enhance the Dielectric and Mechanical Properties of MWCNTs/PVDF Composites with the Aid of MMA-co-GMA Copolymer

    Directory of Open Access Journals (Sweden)

    Shixin Song

    2018-02-01

    Full Text Available A facile strategy is adopted to prepare carboxylic functionalized multiwalled carbon nanotube (c-MWCNT modified high dielectric constant (high-k poly(vinylidene fluoride (PVDF composites with the aid of methyl methacrylate-co-glycidyl methacrylate copolymer (MG. The MG is miscible with PVDF and the epoxy groups of the copolymer can react with the carboxylic groups of c-MWCNT, which induce the uniform dispersion of c-MWCNT and a form insulator layer on the surface of c-MWCNT. The c-MWCNTs/MG/PVDF composites with 8 vol % c-MWCNT present excellent dielectric properties with high dielectric constant (~448 and low dielectric loss (~2.36 at the frequency of 1 KHz, the dielectric loss is much lower than the c-MWCNT/PVDF composites without MG. The obvious improvement in dielectric properties ascribes to the existence of MG, which impede the direct contact of c-MWCNTs and PVDF and avoid the formation of conductive network. Therefore, we propose a practical and simple strategy for preparing composites with excellent dielectric properties, which are promising for applications in electronics devices.

  8. A Facile Strategy to Enhance the Dielectric and Mechanical Properties of MWCNTs/PVDF Composites with the Aid of MMA-co-GMA Copolymer.

    Science.gov (United States)

    Song, Shixin; Xia, Shan; Jiang, Shangkun; Lv, Xue; Sun, Shulin; Li, Quanming

    2018-02-27

    A facile strategy is adopted to prepare carboxylic functionalized multiwalled carbon nanotube (c-MWCNT) modified high dielectric constant (high- k ) poly(vinylidene fluoride) (PVDF) composites with the aid of methyl methacrylate-co-glycidyl methacrylate copolymer (MG). The MG is miscible with PVDF and the epoxy groups of the copolymer can react with the carboxylic groups of c-MWCNT, which induce the uniform dispersion of c-MWCNT and a form insulator layer on the surface of c-MWCNT. The c-MWCNTs/MG/PVDF composites with 8 vol % c-MWCNT present excellent dielectric properties with high dielectric constant (~448) and low dielectric loss (~2.36) at the frequency of 1 KHz, the dielectric loss is much lower than the c-MWCNT/PVDF composites without MG. The obvious improvement in dielectric properties ascribes to the existence of MG, which impede the direct contact of c-MWCNTs and PVDF and avoid the formation of conductive network. Therefore, we propose a practical and simple strategy for preparing composites with excellent dielectric properties, which are promising for applications in electronics devices.

  9. Structural, electric and dielectric properties of Eu-doped SrBi2Nb2O9 ceramics obtained by co-precipitation route

    Directory of Open Access Journals (Sweden)

    Mohamed Afqir

    2018-03-01

    Full Text Available This paper presents a study of the structure and dielectric properties of Eu-doped SrBi2Nb2O9 ceramics prepared by co-precipitation route and sintered at 850 °C. The materials were examined using XRD and FTIR methods. XRD data indicated the formation of well crystallized structure of the pure and doped SrBi2Nb2O9, without the presence of undesirable phases. FTIR spectra do not bring a significant shift in the band positions. Moreover, the AC conductivity, dielectric constant and dielectric loss of the ceramics were determined through the frequency range [50 kHz–1 MHz]. In particular, the dielectric constant (ε′ and dielectric losses (tan δ of the SrBi2Nb2O9 and SrBi1.6Eu0.4Nb2O9 ceramics were measured as a function of temperature at various frequencies.

  10. Electro-optic and magneto-dielectric properties of multifunctional nitride and oxide materials

    Science.gov (United States)

    Dixit, Ambesh

    with a spin polarization of ˜40% +/- 5% , suggesting strong correlation between electron carriers and observed ferromagnetism. Another In-based multifunctional material that has been explored is defect-rich In2O3. This system exhibits numerous interesting properties such as being simultaneously transparent and electrically conducting and above room temperature ferromagnetism together with semiconducting properties. The oxygen stoichiometry in In2O3 plays a crucial role in determining its optical, electronic, and magnetic properties. The effect of oxygen vacancies on different physical properties has been investigated. Our results suggest that as grown, nearly stoichiometric In2O 3 thin films exhibit strong photopersistent current with very long carrier lifetime. Heat treatment under reduced oxygen environment creates oxygen vacancies in these films, producing electron donors. Thus vacuum annealed In2O 3 becomes a highly degenerate n-type conductor. Oxygen deficient In 2O3 can be used as transparent conducting oxide without any further doping, which allows the conductivity to be switched reversibly by thermal annealing in air or vacuum. In addition highly oxygen deficient In 2O3 films exhibit ferromagnetism above room temperature. We have also investigated oxide based magnetoelectric multiferroics which show simultaneous magnetic and ferroelectric properties. This study included detailed investigations of YMnO3, Ni3V2O 8 and FeVO4, where we have investigated FeVO4 a new multiferroic system in the vanadate family. The main focus of this project was to understand the microscopic origin of the magnetoelectric coupling and cross-control of different ferroic order parameters in these system. We have synthesized bulk Ni3V2O8 and FeVO4 ceramics and characterized the thermal, magnetic, dielectric and magnetodielectric response of these samples in bulk form. To understand the cross-control of magnetic and ferroelectric order parameter we deposited thin films of Ni 3V2O8 and Fe

  11. An electrorotation technique for measuring the dielectric properties of cells with simultaneous use of negative quadrupolar dielectrophoresis and electrorotation.

    Science.gov (United States)

    Han, Song-I; Joo, Young-Don; Han, Ki-Ho

    2013-03-07

    This paper presents an effective electrorotation technique for measuring the dielectric properties of cells using a superposed electrical signal, which can simultaneously generate negative quadrupolar dielectrophoretic (nQDEP) force and electrorotational (ROT) torque. The proposed technique involves a three-dimensional (3D) octode, which includes four electrodes arranged in a crisscross pattern on the top and bottom of a microchannel, respectively. A single cell was trapped in the center of the 3D octode by the nQDEP force and simultaneously rotated by the ROT torque. Using the proposed electrorotation technique, ROT spectra of human leukocyte subpopulations (T and B lymphocytes, granulocytes, and monocytes) and metastatic human breast (SkBr3) and lung (A549) cancer cell lines were accurately measured without any disturbance. Torque on the cells generated by the ROT signal was analyzed theoretically based on the single-shell dielectric model for the cells. Furthermore, the dielectric properties of the cells, such as area-specific membrane capacitance and cytoplasm conductivity, were extracted using the measured ROT spectra and the analyzed torque.

  12. Effect of milling process on the microwave dielectric properties of Ba2Ti9O20 materials

    International Nuclear Information System (INIS)

    Chang, C.-B.; Leou, K.-C.; Chia, C.-T; Cheng, C.-S.; Chou, C.-C.; Lin, I-N.

    2006-01-01

    The effects of the milling process on the characteristics of Ba 2 Ti 9 O 20 materials were investigated. The chemical analyses using transmission electron microscopy (EDAX in TEM) revealed that the SiO 2 species incorporated into the Ba 2 Ti 9 O 20 materials were expelled by the Ba 2 Ti 9 O 20 grains. It induced the dissociation of the Ba 2 Ti 9 O 20 materials near the grain boundaries and degraded the microwave dielectric properties of the materials. The same phenomenon was assumed to be the procedure by which the high-energy-milling (HEM) process using Si 3 N 4 grinding media (Si 3 N 4 -HEM) deleteriously influenced the microwave dielectric properties for the Ba 2 Ti 9 O 20 materials. Utilizing the three-dimensional-milling (3DM) process in place of the Si 3 N 4 -HEM one markedly improved the characteristics of the Ba 2 Ti 9 O 20 materials. The 3DM-processed samples own the same crystallinity as the HEM-processed ones but possess a pronouncedly more uniform microstructure and, therefore, exhibit a superior quality factor [(Q x f) 3DM = 28 500 GHz and (Q x f) HEM = 21,900 GHz] with the same large dielectric constant (K = 38-39), when sintered at the same conditions (1350 0 C/4 h). Such a phenomenon is ascribed to the fact that the 3DM process can pulverize the powders efficiently but induce no SiO 2 -contamination

  13. Frequency, moisture content, and temperature dependent dielectric properties of potato starch related to drying with radio-frequency/microwave energy.

    Science.gov (United States)

    Zhu, Zhuozhuo; Guo, Wenchuan

    2017-08-24

    To develop advanced drying methods using radio-frequency (RF) or microwave (MW) energy, dielectric properties of potato starch were determined using an open-ended coaxial-line probe and network analyzer at frequencies between 20 and 4,500 MHz, moisture contents between 15.1% and 43.1% wet basis (w.b.), and temperatures between 25 and 75 °C. The results showed that both dielectric constant (ε') and loss factor (ε″) were dependent on frequency, moisture content, and temperature. ε' decreased with increasing frequency at a given moisture content or temperature. At low moisture contents (≤25.4% w.b.) or low temperatures (≤45 °C), ε″ increased with increasing frequency. However, ε″ changed from decrease to increase with increasing frequency at high moisture contents or temperatures. At low temperatures (25-35 °C), both ε' and ε″ increased with increasing moisture content. At low moisture contents (15.1-19.5% w.b.), they increased with increasing temperature. The change trends of ε' and ε″ were different and dependent on temperature and moisture content at their high levels. The penetration depth (d p ) decreased with increasing frequency. RF treatments may provide potential large-scale industrial drying application for potato starch. This research offers useful information on dielectric properties of potato starch related to drying with electromagnetic energy.

  14. Enhancement in dielectric and magnetic properties of Ni–Zn ferrites prepared by sol–gel method

    Energy Technology Data Exchange (ETDEWEB)

    Nasir, S. [Applied Thermal Physics Laboratory, Department of Physics, COMSATS Institute of Information Technology, Islamabad 44000, Pakistan. (Pakistan); Department of Materials Science and Engineering, Zhejiang University (China); Saleemi, A.S.; Fatima-tuz-Zahra [Applied Thermal Physics Laboratory, Department of Physics, COMSATS Institute of Information Technology, Islamabad 44000, Pakistan. (Pakistan); Anis-ur-Rehman, M., E-mail: marehman@comsats.edu.pk [Applied Thermal Physics Laboratory, Department of Physics, COMSATS Institute of Information Technology, Islamabad 44000, Pakistan. (Pakistan)

    2013-09-25

    Highlights: •Cr-Zn co-doped Ni-Zn ferrites were prepared with a newly reported sol gel method. •Phase purity and a very good control of crystallite and particle size are obtained. •Low eddy current losses are obtained due to low dielectric losses. •Operational frequency of doped Ni-Zn ferrites could be increased up to GHz ranges. -- Abstract: Due to its high permeability, Mn–Zn ferrite is the material of choice for high frequency applications up to a few MHz. At increased operational frequency, Ni–Zn ferrites are more suitable than Mn–Zn ferrites due to their low eddy current losses and low dielectric losses. To combine all these properties and to increase the operational frequency up to GHz, we have prepared Ni{sub 0.5}Zn{sub 0.5}Cr{sub x}Mn{sub 0.5−x}Fe{sub 1.5}O{sub 4} (x = 0.1, 0.2, 0.3, 0.4, 0.5), with a simplified sol gel method. Prepared samples show high saturation magnetization, low coercivity, and low dielectric loss. The dielectric loss in the frequency range 1 MHz to 1.3 GHz remained almost constant as the Cr content was increased in the samples. The crystallite size and lattice parameters of these samples were calculated from X-ray Diffraction (XRD) data analysis. The crystallite size for each sample was calculated using the Scherrer formula considering the most intense peak (3 1 1) and the results were compared with the Scanning Electron Microscope (SEM) images of these samples. Powder X-ray diffraction (XRD) patterns confirmed the single phase spinel structure for these samples. Wayne Kerr Precession Component Analyzer 6440B and Agilent E4991 Impedance Analyzer were used to study the dielectric constant (ε′) and the dielectric loss tangent (tan δ) of these samples as a function of frequency in the frequency range 100 Hz to 1 MHz and 1 MHz to 1.29 GHz respectively. Quantum design PPMS model 6700 was used to study the magnetic properties of these samples.

  15. Effect of surface modification of BiFeO3 on the dielectric, ferroelectric, magneto-dielectric properties of polyvinylacetate/BiFeO3 nanocomposites

    Directory of Open Access Journals (Sweden)

    O. P. Bajpai

    2014-09-01

    Full Text Available Bismuth ferrite (BiFeO3 is considered as one of the most promising materials in the field of multiferroics. In this work, a simple green route as well as synthetic routes has been used for the preparation of pure phase BiFeO3. An extract of Calotropis Gigantea flower was used as a reaction medium in green route. In each case so formed BiFeO3 particles are of comparable quality. These particles are in the range of 50–60 nm and exhibit mixed morphology (viz., spherical and cubic as confirmed by TEM analysis. These pure phase BiFeO3 nanoparticles were first time surface modified effectively by mean of two silylating agent’s viz., tetraethyl orthosilicate (TEOS and (3-Aminopropyltriethoxysilane (APTES. Modified and unmodified BiFeO3 nanoparticles were efficiently introduced into polyvinylacetate (PVAc matrix. It has been shown that nanocomposite prepared by modified BiFeO3 comprise superior dispersion characteristics, improved ferroelectric properties and favorable magneto-dielectric properties along with excellent wettability in compare to nanocomposite prepared by unmodified BiFeO3. These preliminary results demonstrate possible applications of this type of nanocomposites particularly in the field of multiferroic coating and adhesives.

  16. Correlation of Bulk Dielectric and Piezoelectric Properties to the Local Scale Phase Transformations, Domain Morphology, and Crystal Structure Modified

    Energy Technology Data Exchange (ETDEWEB)

    Priya, Shashank [Virginia Polytechnic Inst. and State Univ. (Virginia Tech), Blacksburg, VA (United States); Viehland, Dwight [Virginia Polytechnic Inst. and State Univ. (Virginia Tech), Blacksburg, VA (United States)

    2014-12-14

    Three year program entitled “Correlation of bulk dielectric and piezoelectric properties to the local scale phase transformations, domain morphology, and crystal structure in modified lead-free grain-textured ceramics and single crystals” was supported by the Department of Energy. This was a joint research program between D. Viehland and S. Priya at Virginia Tech. Single crystal and textured ceramics have been synthesized and characterized. Our goals have been (i) to conduct investigations of lead-free piezoelectric systems to establish the local structural and domain morphologies that result in enhanced properties, and (ii) to synthesize polycrystalline and grain oriented ceramics for understanding the role of composition, microstructure, and anisotropy

  17. Preparation, characterization, dielectric properties and diffusion studies of styrene butadiene rubber (SBR)/manganous tungstate (MnWO4) nanocomposites

    Science.gov (United States)

    Jasna, V. C.; Ramesan, M. T.

    2017-06-01

    Nanocomposites based on SBR with different content of manganous tungstate nanoparticles were prepared and characterized by FTIR, UV-visible spectroscopy, XRD, SEM, TGA, DSC and impedance analysis. The interaction between nanoparticles and the elastomer was clear from the shift in peaks of UV and FTIR. XRD and SEM analysis showed the uniform arrangement of nanoparticles in SBR matrix. Glass transition temperature, thermal stability and dielectric properties of composites were enhanced by the addition of nanoparticles. Sorption studies of nanocomposites were done in aromatic solvents at different temperature. Sorption data obtained were used to estimate the thermodynamic properties.

  18. Growth, Optical, Dielectric and Ferroelectric Properties of Non-Linear Optical Single Crystal: Glycine-Phthalic Acid

    Science.gov (United States)

    Suresh, Sagadevan

    2016-11-01

    Single crystals of glycine-phthalic acid (GPA) were grown by slow evaporation process using aqueous solution. X-ray diffraction analysis was used to examine its cell structure and it was found that the GPA crystal corresponded to the orthorhombic system. To identify absorption range and cut-off wavelength for the GPA crystal, UV-visible spectrum was recorded. UV-visible spectroscopy was used to study the optical constants such as the refractive index, the extinction coefficient, electrical susceptibility, and optical conductivity. As a function of different frequencies and temperatures, the dielectric constant and the dielectric loss were examined. The electrical properties like plasma energy, Penn gap, Fermi energy, and polarizability were determined for the analysis of the second harmonic generation (SHG). Using the Kurtz powder technique, the SHG of the GPA crystal was studied. Investigations relating to hysteresis were carried out to ascertain the ferroelectric nature of the material.

  19. Optical properties and thermal stability of LaYbO3 ternary oxide for high-k dielectric application

    Science.gov (United States)

    Su, Wei-tao; Yang, Li; Li, Bin

    2011-01-01

    A new ternary rare oxide dielectric LaYbO3 film had been prepared on silicon wafers and quartz substrates by reactive sputtering method using a La-Yb metal target. A range of analysis techniques was performed to determine the optical band gap, thermal stability, and electrical property of the deposited samples. It was found the band gap of LaYbO3 film was about 5.8 eV. And the crystallization temperature for rapid thermal annealing (20 s) was between 900 and 950 °C. X-ray photoelectron spectroscopy results indicate the formation of the SiO2 and silicate in the interface between silicon wafer and LaYbO3 film. The dielectric constant is about 23 from the calculation of capacitance-voltage curve, which is comparable higher than previously reported La2O3 or Yb2O3 film.

  20. Dielectric and piezoelectric properties of lead-free (Bi,Na)TiO3-based thin films

    Science.gov (United States)

    Abazari, M.; Safari, A.; Bharadwaja, S. S. N.; Trolier-McKinstry, S.

    2010-02-01

    Dielectric and piezoelectric properties of morphotropic phase boundary (Bi,Na)TiO3-(Bi,K)TiO3-BaTiO3 epitaxial thin films deposited on SrRuO3 coated SrTiO3 substrates were reported. Thin films of 350 nm thickness exhibited small signal dielectric permittivity and loss tangent values of 750 and 0.15, respectively, at 1 kHz. Ferroelectric hysteresis measurements indicated a remanent polarization value of 30 μC/cm2 with a coercive field of 85-100 kV/cm. The thin film transverse piezoelectric coefficient (e31,f) of these films after poling at 600 kV/cm was found to be -2.2 C/m2. The results indicate that these BNT-based thin films are a potential candidate for lead-free piezoelectric devices.

  1. 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...... these improved properties are achieved without consequently increased Young’s moduli and decreased breakdown strength compared, for example, with other silicone elastomers containing fillers. In particular, the interpenetrating systems show dielectric permittivity ε’ from 6,7 to 2 x 103 at low frequencies (0...

  2. Properties of PZT thick film made on LTCC substrates with dielectric intermediate layers

    Science.gov (United States)

    DÄ browski, Arkadiusz; Golonka, Leszek

    2016-11-01

    Results of experiments on application of various interlayers between LTCC (Low Temperature Cofired Ceramics) substrate and thick-film PZT (Lead Zirconate - Titanate) are described in this work. Thick-film intermediate layers were based on several dielectric materials: TiN, Al2O3, SiC, TiO2, SiC, YSZ, BN. Seven screen printable pastes were prepared on the base of powders of mentioned materials with addition of glass and organic vehicle. The substrates were made of 951 (DuPont), CeramTapeGC (CeramTec) and HL2000 (Heraeus) LTCC tapes. Sandwich type transducers, consisting of barrier layer, gold bottom electrode, PZT layer and silver top electrode were prepared and characterized. Basic piezoelectric parameters - permittivity, effective charge constant (d33(eff)) and remanent polarization were determined. The best properties were obtained for substrates made of 951. In general, interlayers based on TiO2, SiC and Al2O3 improved permittivity and charge constant comparing to bare substrates. For example, for 951 substrate the PZT layer exhibited d33(eff) equal to 160, 215, 250 and 230 pC/N for bare substrate, TiO2 interlayer, SiC interlayer and Al2O3 interlayer, respectively. In case of CeramTape GC substrates determined permittivity was equal to 215, 245, 235 and 275 for bare substrate, TiO2 interlayer, SiC interlayer and Al2O3 interlayer, respectively. In case of TiN and BN materials the parameters were considerably deteriorated.

  3. Properties of reactively radio frequency-magnetron sputtered (Zr,Sn)TiO4 dielectric films

    International Nuclear Information System (INIS)

    Huang, C.-L.; Hsu, C.-H.

    2004-01-01

    Zirconium tin titanium oxide doped 1 wt % ZnO thin films on n-type Si substrate were deposited by rf magnetron sputtering at a fixed rf power of 350 W with various argon-oxygen (Ar/O 2 ) mixture and different substrate temperatures. Electrical properties and microstructures of ZnO-doped (Zr 0.8 Sn 0.2 )TiO 4 thin films prepared by rf magnetron sputtering on n-type Si(100) substrates at different Ar/O 2 ratios and substrate temperatures have been investigated. The surface structural and morphological characteristics analyzed by x-ray diffraction, scanning electron microscopy, and atomic force microscope were sensitive to the deposition conditions, such as Ar/O 2 ratio (100/0-80/20) and substrate temperature (350 deg. C-450 deg. C). The selected-area diffraction pattern showed that the deposited films exhibited a polycrystalline microstructure. All films exhibited ZST (111) orientation perpendicular to the substrate surface and the grain size as well as the deposition rate of the films increased with the increase of both the Ar partial pressure and the substrate temperature. At a Ar/O 2 ratio of 100/0, rf power level of 350 W and substrate temperature of 450 deg. C, the Zr 0.8 Sn 0.2 TiO 4 films with 6.44 μm thickness possess a dielectric constant of 42 (at 10 MHz), a dissipation factor of 0.065 (at 10 MHz), and a leakage current density of 2x10 -7 A/cm 2 at an electrical field of 1 kV/cm

  4. Characterization of dielectric materials

    Energy Technology Data Exchange (ETDEWEB)

    King, Danny J.; Babinec, Susan; Hagans, Patrick L.; Maxey, Lonnie C.; Payzant, Edward A.; Daniel, Claus; Sabau, Adrian S.; Dinwiddie, Ralph B.; Armstrong, Beth L.; Howe, Jane Y.; Wood, III, David L.; Nembhard, Nicole S.

    2017-06-27

    A system and a method for characterizing a dielectric material are provided. The system and method generally include applying an excitation signal to electrodes on opposing sides of the dielectric material to evaluate a property of the dielectric material. The method can further include measuring the capacitive impedance across the dielectric material, and determining a variation in the capacitive impedance with respect to either or both of a time domain and a frequency domain. The measured property can include pore size and surface imperfections. The method can still further include modifying a processing parameter as the dielectric material is formed in response to the detected variations in the capacitive impedance, which can correspond to a non-uniformity in the dielectric material.

  5. Dielectric, magnetic, ferroelectric, and Mossbauer properties of bismuth substituted nanosized cobalt ferrites through glycine nitrate synthesis method

    Science.gov (United States)

    Routray, Krutika L.; Sanyal, Dirtha; Behera, Dhrubananda

    2017-12-01

    CoFe2-xBixO4 nanoferrites with x = 0, 0.05, 0.1, 0.5, and 1.0 have been synthesized by the glycine nitrate process. The present study investigates the effect of Bi3+ substitution on the microstructural, dielectric, ferroelectric, magnetic, and Mossbauer properties of CoFe2O4 nanoparticles. The X-ray diffraction technique was used to confirm the phase purity and estimate the crystallite size which revealed the formation of a secondary phase when Bi3+ concentration exceeds x = 0.5. Transmission electron microscopy indicated the formation of grains by aggregation of small crystallites with a reduction in grain size to 20 nm with an increase in Bi3+ content and also divulged the lattice parameter value to be 8.378 Å, confirming the crystalline nature of the synthesised sample. Dielectric properties performed in the frequency range of 100 Hz to 1 MHz determined that the dielectric behavior is attributed to the Maxwell-Wagner polarization and the activation energy of the specimens is calculated from the dielectric measurements. The hysteresis curve indicated the ferrimagnetic nature of the samples. The samples also exhibited a well saturated P-E loop with gradual lowering in remenant polarization, coercive field, and saturation polarization with an increase in bismuth concentration. Mössbauer spectroscopy analysis confirmed the changes in magnetic moment of ions, their coupling with neighbouring ions, and cation exchange interactions. Owing to the high physical, thermal, and chemical stabilities, these magnetic ceramics, CoFe2-xBixO4, possesses tremendous potential in major understanding of magnetism and in magnetic recording applications for high density information storage.

  6. Dielectric properties of water in Triton X-100 (nonionic detergent)-water mixtures

    International Nuclear Information System (INIS)

    Asami, Koji

    2007-01-01

    Dielectric measurements were carried out for mixtures of Triton X-100 (TX, a nonionic detergent with a poly(ethylene oxide) chain) and water with or without electrolytes over a frequency range of 1 MHz to 10 GHz to study the structure and dynamics of water molecules in the mixtures. Dielectric relaxation was found above 100 MHz, being assigned to the dielectric relaxation of water. The intensity of the dielectric relaxation was proportional to the water content above 0 deg. C. Below the freezing temperature of bulk water, the relaxation intensity decreased at TX concentrations (C TX ) below 50 wt% at -10 deg. Cand below 60 wt% at -20 deg. Cbecause frozen water shifts the dielectric relaxation to a frequency region far below 1 MHz. This indicated that there is no bulk water at C TX above 50 wt% and that at least two water molecules per ethylene oxide (EO) unit are tightly associated with the ethylene oxide chain. The low-frequency conductivity of the mixtures of TX and electrolyte solutions was well represented by Bruggeman's mixture equation at C TX below 40 wt%, if two water molecules per EO unit form an insulating shell surrounding TX micelles

  7. Sintering and dielectric properties of a technical porcelain prepared from economical natural raw materials

    Energy Technology Data Exchange (ETDEWEB)

    Kasrani, S.; Harabi, A.; Barama, S.-E.; Foughali, L.; Benhassine, M. T., E-mail: souad478@yahoo.fr, E-mail: harabi52@gmail.com, E-mail: sebarama@usa.com, E-mail: foughali_lazhar@yahoo.fr, E-mail: mtb25dz@gmail.com [Ceramics Lab. Mentouri University of Constantine (Algeria); Aldhayan, D.M., E-mail: aldhayan@ksu.edu.sa [Chemistry Department, Riyadh, King Saud University (Saudi Arabia)

    2016-10-15

    In this study, the production of a technical porcelain, for the ceramic dielectric applications by using economical natural raw materials, was investigated. The basic porcelain composition was selected consisting of 30 wt% kaolin, 45 wt% potash-feldspar and 25 wt% quartz. The obtained phases in the sintered samples were investigated by X-ray diffraction, Fourier transform infrared spectroscopy analysis, and scanning electron microscopy images. It has been confirmed by these techniques that the main crystalline phases were quartz and mullite. Dielectric measurements of technical porcelains have been carried out at 1 kHz from room temperature to 200 °C. The dielectric constant, loss factor, dielectric loss tangent, and resistivity of the porcelain sample sintered at 1160 °C were 22-25, 0.32-1.80, 0.006-0.07, and 0.2-9 x 10{sup 13} Ω.cm, respectively. The value of dielectric constant was significantly high when compared to that of conventional porcelains which did not exceed generally 9. (author)

  8. A critical appraisal of the zero-multipole method: Structural, thermodynamic, dielectric, and dynamical properties of a water system

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Han, E-mail: wang-han@iapcm.ac.cn [CAEP Software Center for High Performance Numerical Simulation, Huayuan Road 6, 100088 Beijing, China and Zuse Institute Berlin (ZIB), Berlin (Germany); Nakamura, Haruki [Institute for Protein Research, Osaka University, 3-2 Yamadaoka, Suita, Osaka 565-0871 (Japan); Fukuda, Ikuo, E-mail: ifukuda@protein.osaka-u.ac.jp [Institute for Protein Research, Osaka University, 3-2 Yamadaoka, Suita, Osaka 565-0871 (Japan); RIKEN (The Institute of Physical and Chemical Research), 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan)

    2016-03-21

    We performed extensive and strict tests for the reliability of the zero-multipole (summation) method (ZMM), which is a method for estimating the electrostatic interactions among charged particles in a classical physical system, by investigating a set of various physical quantities. This set covers a broad range of water properties, including the thermodynamic properties (pressure, excess chemical potential, constant volume/pressure heat capacity, isothermal compressibility, and thermal expansion coefficient), dielectric properties (dielectric constant and Kirkwood-G factor), dynamical properties (diffusion constant and viscosity), and the structural property (radial distribution function). We selected a bulk water system, the most important solvent, and applied the widely used TIP3P model to this test. In result, the ZMM works well for almost all cases, compared with the smooth particle mesh Ewald (SPME) method that was carefully optimized. In particular, at cut-off radius of 1.2 nm, the recommended choices of ZMM parameters for the TIP3P system are α ≤ 1 nm{sup −1} for the splitting parameter and l = 2 or l = 3 for the order of the multipole moment. We discussed the origin of the deviations of the ZMM and found that they are intimately related to the deviations of the equilibrated densities between the ZMM and SPME, while the magnitude of the density deviations is very small.

  9. The effect of flexoelectricity on the dielectric properties of inhomogeneously strained ferroelectric thin films

    Energy Technology Data Exchange (ETDEWEB)

    Catalan, G [Institut Mediterrani d' Estudis Avancats (IMEDEA), C/Miquel Marques 21, Esporles 07190, Mallorca (Spain); Sinnamon, L J [Department of Pure and Applied Physics, Queen' s University of Belfast, University Road, Belfast BT7 1NN (United Kingdom); Gregg, J M [Department of Pure and Applied Physics, Queen' s University of Belfast, University Road, Belfast BT7 1NN (United Kingdom)

    2004-04-07

    Recent experimental measurements of large flexoelectric coefficients in ferroelectric ceramics suggest that strain gradients can affect the polarization and permittivity behaviour of inhomogeneously strained ferroelectrics. Here we present a phenomenological model of the effect of flexoelectricity on the dielectric constant, polarization, Curie temperature (T{sub C}), temperature of maximum dielectric constant (T{sub m}) and temperature of the onset of reversible polarization (T{sub ferro}) for ferroelectric thin films subject to substrate-induced epitaxial strains that are allowed to relax with thickness, and the qualitative and quantitative predictions of the model are compared with experimental results for (Ba{sub 0.5}Sr{sub 0.5})TiO{sub 3} thin films on SrRuO{sub 3} electrodes. It is shown that flexoelectricity can play an important role in decreasing the maximum dielectric constant of ferroelectric thin films under inhomogeneous in-plane strain, regardless of the sign of the strain gradient.

  10. The effect of flexoelectricity on the dielectric properties of inhomogeneously strained ferroelectric thin films

    International Nuclear Information System (INIS)

    Catalan, G; Sinnamon, L J; Gregg, J M

    2004-01-01

    Recent experimental measurements of large flexoelectric coefficients in ferroelectric ceramics suggest that strain gradients can affect the polarization and permittivity behaviour of inhomogeneously strained ferroelectrics. Here we present a phenomenological model of the effect of flexoelectricity on the dielectric constant, polarization, Curie temperature (T C ), temperature of maximum dielectric constant (T m ) and temperature of the onset of reversible polarization (T ferro ) for ferroelectric thin films subject to substrate-induced epitaxial strains that are allowed to relax with thickness, and the qualitative and quantitative predictions of the model are compared with experimental results for (Ba 0.5 Sr 0.5 )TiO 3 thin films on SrRuO 3 electrodes. It is shown that flexoelectricity can play an important role in decreasing the maximum dielectric constant of ferroelectric thin films under inhomogeneous in-plane strain, regardless of the sign of the strain gradient

  11. Influence of graphene nanoparticles on optical and dielectric properties of PVA-PEDOT:PSS blend composite

    Science.gov (United States)

    Hebbar, Vidyashree; Bhajantri, R. F.; Naik, Jagadish

    2017-05-01

    The composite films of PVA-PEDOT:PSS blend filled with synthesized Graphene oxide (GO) and reduced Graphene oxide (RGO) nanoparticles were prepared by solvent casting technique. The microstructural changes are confirmed in Fourier transform infrared (FTIR) spectroscopy. The UV-Visible absorption spectra exhibit peaks of GO along with a characteristic peak of PVA-PEDOT:PSS blend. The morphological effect is studied with Atomic Force Microscope (AFM). The dielectric parameters such as dielectric constant and dielectric loss increase with increase in wt.% of GO and RGO nanoparticles. The AC conductivities of the prepared nanocomposites measured with impedance analyzer shows maximum for 5 wt.% of GO nanoparticles doped PVA-PEDOT:PSS composites at high frequency.

  12. Electric and Hydraulic Properties of Carbon Felt Immersed in Different Dielectric Liquids

    Directory of Open Access Journals (Sweden)

    Alexey Kossenko

    2018-04-01

    Full Text Available Electroconductive carbon felt (CF material, having a permeable structure and significant electroconductive surface, is widely used for electrodes in numerous electrochemical applications such as redox flow batteries, fuel cells, electrochemical desalination apparatus, etc. The internal structure of CF is composed of different lengths of carbon filaments bonded together. This structure creates a large number of stochastically oriented and stochastically linked channels that have different lengths and cross sections. Therefore, the CF hydraulic permeability is similar to that of porous media and is determined by the internal empty volume and arrangement of carbon fibers. Its electroconductivity is ensured by the conductivity of the carbon filaments and by the electrical interconnections between fibers. Both of these properties (permeability and electrical conductivity are extremely important for the efficient functioning of electrochemical devices. However, their influences counter each other during CF compressing. Increasing the stress on a felt element provides supplementary electrical contacts of carbon filaments, which lead to improved electrical conductivity. Thus, the active surface of the felt electrode is increased, which also boosts redox chemical reactions. On the other hand, compressed felt possesses reduced hydrodynamic permeability as a result of a diminished free volume of porous media and intrinsic channels. This causes increasing hydrodynamic expenditures of electrolyte pumping through electrodes and lessened cell (battery efficiency. The designer of specific electrochemical systems has to take into account both of these properties when selecting the optimal construction for a cell. This article presents the results of measurements and novel approximating expressions of electrical and hydraulic characteristics of a CF during its compression. Since electrical conductivity plays a determining role in providing electrochemical

  13. Electric and Hydraulic Properties of Carbon Felt Immersed in Different Dielectric Liquids.

    Science.gov (United States)

    Kossenko, Alexey; Lugovskoy, Svetlana; Averbukh, Moshe

    2018-04-23

    Electroconductive carbon felt (CF) material, having a permeable structure and significant electroconductive surface, is widely used for electrodes in numerous electrochemical applications such as redox flow batteries, fuel cells, electrochemical desalination apparatus, etc. The internal structure of CF is composed of different lengths of carbon filaments bonded together. This structure creates a large number of stochastically oriented and stochastically linked channels that have different lengths and cross sections. Therefore, the CF hydraulic permeability is similar to that of porous media and is determined by the internal empty volume and arrangement of carbon fibers. Its electroconductivity is ensured by the conductivity of the carbon filaments and by the electrical interconnections between fibers. Both of these properties (permeability and electrical conductivity) are extremely important for the efficient functioning of electrochemical devices. However, their influences counter each other during CF compressing. Increasing the stress on a felt element provides supplementary electrical contacts of carbon filaments, which lead to improved electrical conductivity. Thus, the active surface of the felt electrode is increased, which also boosts redox chemical reactions. On the other hand, compressed felt possesses reduced hydrodynamic permeability as a result of a diminished free volume of porous media and intrinsic channels. This causes increasing hydrodynamic expenditures of electrolyte pumping through electrodes and lessened cell (battery) efficiency. The designer of specific electrochemical systems has to take into account both of these properties when selecting the optimal construction for a cell. This article presents the results of measurements and novel approximating expressions of electrical and hydraulic characteristics of a CF during its compression. Since electrical conductivity plays a determining role in providing electrochemical reactions, it was

  14. Magnetic and dielectric properties of perovskite type nanocrystalline SrFeO3-δ

    International Nuclear Information System (INIS)

    Manimuthu, P.; Ashok Kumar, K.; Ezhilarasi, V.S.; Venkateswaran, C.

    2012-01-01

    SrFeO 3δ belongs to the Ruddelson-Popper class of system exhibiting technologically interesting electronic and magnetic properties. Stoichiometric SrFeO 3 is metallic and helical antiferromagnet with a Neel temperature (T N ) of 134 K. In particular, SrFeO 3 with Fe in the 4+ state receives greatest attention. The unusual valence state of Fe 4+ in the octahedral site is unstable during the high temperature annealing process and gradually reduces to stable Fe 3+ . Due to this charge conversion, oxygen vacancies are formed for charge compensation. Depending on the oxygen content, the material possesses different structural and electronic properties. For δ= 0, 0.13, 0.27 and 0.5, it takes cubic-SrFeO 3 , tetragonal-SrFeO 2 . 87 (Sr 8 Fe 8 O 23 ), orthorhombic-SrFeO 2.73 , (Sr 4 Fe 4 O 11 ) and brownmilletrate-orthorhombic-SrFeO 2.5 (Sr 2 Fe 2 O 5 ) phases, respectively. Any intermediate composition results in a mixture of two neighbouring phases. So, SrFeO 3-δ has gained interest not only because of iron in 4+ state but also due to its oxygen deficiency. The perovskite type nanocrystalline SrFeO 3δ has been prepared by thermal decomposition method. X-ray diffraction (XRD) shows that the prepared sample is in cubic perovskite phase. HRSEM image shows nanocrystalline sized particles of irregular shape with large agglomerations. Room temperature magnetization and Mösbauer measurements reveal paramagnetic behavior. Thermo-magnetization curve clearly shows a Neel transition temperature around 106 K which is lower than that of the stoichiometric SrFeO 3 (T N = 134 K). From the Mössbauer result, three charge states of Fe ions (i.e., Fe 4+ , Fe 3.5+ and Fe 3+ ) are evident. The corresponding oxygen deficient phase has been identified from the relative areas of three Fe ions in the sample and is found to be δ ∼ 0.19. Electrical and dielectric behaviors of the sample have been analyzed using an impedance analyzer from 303 K to 473 K. The results will be discussed

  15. Reverse micellar synthesis, structural characterization and dielectric properties of Sr-doped BaZrO{sub 3} nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Ahmad, Tokeer, E-mail: tahmad3@jmi.ac.in [Nanochemistry Laboratory, Department of Chemistry, Jamia Millia Islamia, New Delhi, 110025 (India); Ubaidullah, Mohd [Nanochemistry Laboratory, Department of Chemistry, Jamia Millia Islamia, New Delhi, 110025 (India); Department of Chemistry, Banasthali University, Tonk, Rajasthan, 304022 (India); School of Science and Technology, Glocal University, Mirzapur, Saharanpur, 247121, Uttar Pradesh (India); Shahazad, Mohd [Nanochemistry Laboratory, Department of Chemistry, Jamia Millia Islamia, New Delhi, 110025 (India); Kumar, Dinesh [Department of Chemistry, Banasthali University, Tonk, Rajasthan, 304022 (India); Al-Hartomy, Omar A. [Department of Physics, Faculty of Science, King Abdulaziz University, Jeddah, 21589 (Saudi Arabia)

    2017-01-01

    Sr-doped BaZrO{sub 3} nanoparticles with strontium content varying from 5 to 20 mol % were successfully synthesized by reverse micellar method at 900 °C for the first time. Systematic studies have been carried out to establish the structural and electrical properties of the as prepared nanoparticles. These nanoparticles were characterized using powder X-ray diffraction, transmission electron microscopy, BET surface area and dielectric measurements. X-ray diffraction analysis showed the formation of monophasic and highly crystalline nanoparticles which could be indexed in cubic BaZrO{sub 3} with contraction of lattice on strontium substitution. A monotonic shift of diffraction pattern towards higher angel confirms the formation of solid solutions of Ba{sub 1−x}Sr{sub x}ZrO{sub 3} (0.05 ≤ x ≤ 0.20) which was corroborating well with lattice parameter studies. Transmission electron microscopic studies showed the formation of cubic, spherical and hexagonal nanoparticles with an average grain size of 40–65 nm. Energy dispersive X-ray spectroscopic studies confirmed the presence of dopant (Sr{sup 2+}) in the BaZrO{sub 3} matrix and estimated chemical species corroborate well with the loaded composition. Specific surface area of the solid solution comes out to be in the range of 104–244 m{sup 2} g{sup -1}. Smallest particle of size 40 nm shows highest surface area 244 m{sup 2} g{sup -1} for 20 mol% Sr-doped BaZrO{sub 3}. Dielectric and impedance studies were also carried out as a function of frequency and temperature to explore the electrical properties of Sr-doped BaZrO{sub 3}. The dielectric constant of Ba{sub 1−x}Sr{sub x}ZrO{sub 3} (0.05 ≤ x ≤ 0.20) was found to be in the range of 13–25 for x = 0.05 to x = 0.20 with nearly similar dielectric loss of the order of 0.02. The conductance increases linearly with increase in frequency at room temperature, however the impedance has an inverse effect. - Highlights: • Monophasic nanocrystalline Ba{sub 1

  16. 47 CFR 32.7600 - Extraordinary items.

    Science.gov (United States)

    2010-10-01

    ... FOR TELECOMMUNICATIONS COMPANIES Instructions For Other Income Accounts § 32.7600 Extraordinary items... extraordinary. Extraordinary events and transactions are distinguished by both their unusual nature and by the infrequency of their occurrence, taking into account the environment in which the company operates. This...

  17. Massive dielectric properties enhancement of MWCNTs/CoFe2O4 nanohybrid for super capacitor applications

    Science.gov (United States)

    Khan, Muhammad Zarrar; Gul, Iftikhar Hussain; Anwar, Humaira; Ameer, Shahid; Khan, Ahmad Nawaz; Khurram, Aqeel Ahsan; Nadeem, Kashif; Mumtaz, Muhammad

    2017-02-01

    Nanohybrids of CoFe2O4/MWCNTs with increasing MWCNTs loading from 0.0%, 0.5%, 1%, 1.5%, 2% and 5% by weight were prepared by a novel method of dispersion using ortho-xylene as a dispersive medium for the first time. In our current research, nanoparticles of cobalt ferrite were synthesized via wet chemical co-precipitation route. Non-magnetic MWCNTs matrix was dispersed uniformly in the synthesized ferrite nanoparticles using ortho-xylene as a polar solvent. and Impedance Analyzer were utilized to effectively investigate the synthesized nanohybrid. The obtained X-Ray Powder Diffraction (XRD) images confirm the pure Face Centered Cubic (FCC) single phase of CoFe2O4/MWCNTs nanohybrid. The average crystallite size remains within the range of 26±6 nm. Scanning Electron Microscopy (SEM) results showed aggregation of ferrite nanoparticles on MWCNTs. Fourier Transform Infrared Spectroscopy (FTIR) was utilized to study the band positions. The dielectric properties were found to be massively enhanced with increased loadings of MWCNTs. The dielectric constant (ε/) was massively enhanced from 45 for pure cobalt ferrites to 4.32×1012 for 5% MWCNTs loading at 100 Hz. The dielectric and tangent losses also increased from 21 and 0.47 for pure cobalt ferrites to 2.33×1017 and 5.39×104 at 100 Hz for 5% MWCNTs loading respectively indicating that this area of research should further be exploited in the realm of super capacitors applications.

  18. Effect of orthorhombic distortion on dielectric and piezoelectric properties of CaBi4Ti4O15 ceramics

    Science.gov (United States)

    Tanwar, Amit; Sreenivas, K.; Gupta, Vinay

    2009-04-01

    High temperature bismuth layered piezoelectric and ferroelectric ceramics of CaBi4Ti4O15 (CBT) have been prepared using the solid state route. The formation of single phase material with orthorhombic structure was verified from x-ray diffraction and Raman spectroscopy. The orthorhombic distortion present in the CBT ceramic sintered at 1200 °C was found to be maximum. A sharp phase transition from ferroelectric to paraelectric was observed in the temperature dependent dielectric studies of all CBT ceramics. The Curie's temperature (Tc=790 °C) was found to be independent of measured frequency. The behavior of ac conductivity as a function of frequency (100 Hz-1 MHz) at low temperatures (<500 °C) follows the power law and is attributed to hopping conduction. The presence of large orthorhombic distortion in the CBT ceramic sintered at 1200 °C results in high dielectric constant, low dielectric loss, and high piezoelectric coefficient (d33). The observed results indicate the important role of orthorhombic distortion in determining the improved property of multicomponent ferroelectric material.

  19. Electrical and materials properties of ZrO2 gate dielectrics grown by atomic layer chemical vapor deposition

    Science.gov (United States)

    Perkins, Charles M.; Triplett, Baylor B.; McIntyre, Paul C.; Saraswat, Krishna C.; Haukka, Suvi; Tuominen, Marko

    2001-04-01

    Structural and electrical properties of gate stack structures containing ZrO2 dielectrics were investigated. The ZrO2 films were deposited by atomic layer chemical vapor deposition (ALCVD) after different substrate preparations. The structure, composition, and interfacial characteristics of these gate stacks were examined using cross-sectional transmission electron microscopy and x-ray photoelectron spectroscopy. The ZrO2 films were polycrystalline with either a cubic or tetragonal crystal structure. An amorphous interfacial layer with a moderate dielectric constant formed between the ZrO2 layer and the substrate during ALCVD growth on chemical oxide-terminated silicon. Gate stacks with a measured equivalent oxide thickness (EOT) of 1.3 nm showed leakage values of 10-5 A/cm2 at a bias of -1 V from flatband, which is significantly less than that seen with SiO2 dielectrics of similar EOT. A hysteresis of 8-10 mV was seen for ±2 V sweeps while a midgap interface state density (Dit) of ˜3×1011 states/cm eV was determined from comparisons of measured and ideal capacitance curves.

  20. Dielectric properties, impedance analysis and modulus behavior of CaTiO{sub 3} ceramic prepared by solid state reaction

    Energy Technology Data Exchange (ETDEWEB)

    Wong, Y.J., E-mail: yjeng_86@hotmail.com [Department of Physics, Faculty of Science, Universiti Putra Malaysia, 43400 Serdang, Selangor (Malaysia); Hassan, J., E-mail: jumiah@science.upm.edu.my [Department of Physics, Faculty of Science, Universiti Putra Malaysia, 43400 Serdang, Selangor (Malaysia); Advanced Materials and Nanotechnology Laboratory, Institute of Advanced Technology (ITMA), Universiti Putra Malaysia, 43400 Serdang, Selangor (Malaysia); Hashim, M., E-mail: mansor@science.upm.edu.my [Department of Physics, Faculty of Science, Universiti Putra Malaysia, 43400 Serdang, Selangor (Malaysia); Advanced Materials and Nanotechnology Laboratory, Institute of Advanced Technology (ITMA), Universiti Putra Malaysia, 43400 Serdang, Selangor (Malaysia)

    2013-09-15

    Highlights: •A single phase orthorhombic CaTiO{sub 3} structure with sub-micron grains is produced. •The frequency exponent ‘s’ is temperature dependent and explained by CBH model. •The dielectric constant and loss tangent are frequency and temperature dependent. •The modulus plot reveals the presence of thermally activated dielectric relaxation. •Cole-cole plot reveals two primary relaxation processes exist in the sample. -- Abstract: Calcium titanate (CaTiO{sub 3}) with the general formula for perovskites, ABO{sub 3}, is of technological importance, particularly with regard to dielectric properties. In this work, CaTiO{sub 3} ceramic material was prepared by the conventional solid state reaction method. The dielectric properties, impedance characteristics and modulus behavior of the CaTiO{sub 3} ceramic material sintered at 1240 °C were investigated in the frequency range of 10{sup −2}–10{sup 6} Hz and temperature range of 100–250 °C. The XRD analysis of the sintered CaTiO{sub 3} shows that it is an orthorhombic structure with lattice parameters a = 5.4398 Å, b = 7.6417 Å, and c = 5.3830 Å. The FESEM micrograph shows a significant difference in grain size distribution ranging from 0.26 to 2.32 μm. The AC conductivity, σ{sub AC}, is found to increase with increasing temperature within the frequency range of 10{sup −2}–10{sup 6} Hz confirming the hopping of electrons to be the conduction mechanism. Due to the decreasing values of the frequency exponent s with increasing temperature, the results of the σ{sub AC} are discussed using the correlated barrier height (CBH) model. For dielectric studies, the dielectric constant, ε′ is found to decrease with increasing frequency. In the whole temperature range of 100–250 °C, high and low frequency plateau are observed. Each converges at high frequency (>10{sup 5} Hz) for all the temperatures. The frequency dependence of loss tangent, tan δ, decreases with rise in temperature, with the

  1. Synergistic effect of functionally active methacrylate polymer and ZnO nanoparticles on optical and dielectric properties

    Energy Technology Data Exchange (ETDEWEB)

    Ilangovan, Pugazhenthi; Sakvai, Mohammed Safiullah; Kottur, Anver Basha, E-mail: kanverbasha@gmail.com

    2017-06-01

    A crucial need to design a functionally active polymer hybrid for the protection of material structure that are exposing to harmful Ultra Violet radiation (UV). In this paper a poly(pyridine-4-yl-methyl) methacrylate ZnO nanocomposite (PPyMMA/ZnO) was developed by in-situ solution polymerization. The X-ray diffraction (XRD) studies confirmed that the nanocomposite is homogeneous with good compatibility between the two counterparts. The morphological variation arises owing to the incorporation of OA-ZnO in the PPyMMA were observed by using electron microscope techniques. The thermal behaviour of PPyMMA and its ZnO nanocomposites were analysed by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The dielectric properties of the polymer and its ZnO nanocomposites were studied over a wide range of temperature (30–300 °C) at frequency 100 KHz. An optical study was carried out to test the optical properties of PPyMMA/ZnO (2, 5 and 5%), which reveals that 2% ZnONPs loading exhibits an excellent UV shielding properties. - Highlights: • The PPyMMA/ZnO was prepared by in-situ solution polymerization. • The OA-ZnO were incorporated during the solution polymerization of PPyMMA. • The PPyMMA/ZnO nanocomposite exhibit an improved dielectric property. • The PPyMMA with OA-ZnO nanocomposite show an excellent UV-shielding.

  2. Synergistic effect of functionally active methacrylate polymer and ZnO nanoparticles on optical and dielectric properties

    International Nuclear Information System (INIS)

    Ilangovan, Pugazhenthi; Sakvai, Mohammed Safiullah; Kottur, Anver Basha

    2017-01-01

    A crucial need to design a functionally active polymer hybrid for the protection of material structure that are exposing to harmful Ultra Violet radiation (UV). In this paper a poly(pyridine-4-yl-methyl) methacrylate ZnO nanocomposite (PPyMMA/ZnO) was developed by in-situ solution polymerization. The X-ray diffraction (XRD) studies confirmed that the nanocomposite is homogeneous with good compatibility between the two counterparts. The morphological variation arises owing to the incorporation of OA-ZnO in the PPyMMA were observed by using electron microscope techniques. The thermal behaviour of PPyMMA and its ZnO nanocomposites were analysed by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The dielectric properties of the polymer and its ZnO nanocomposites were studied over a wide range of temperature (30–300 °C) at frequency 100 KHz. An optical study was carried out to test the optical properties of PPyMMA/ZnO (2, 5 and 5%), which reveals that 2% ZnONPs loading exhibits an excellent UV shielding properties. - Highlights: • The PPyMMA/ZnO was prepared by in-situ solution polymerization. • The OA-ZnO were incorporated during the solution polymerization of PPyMMA. • The PPyMMA/ZnO nanocomposite exhibit an improved dielectric property. • The PPyMMA with OA-ZnO nanocomposite show an excellent UV-shielding.

  3. Electrical Properties of Ultrathin Hf-Ti-O Higher k Gate Dielectric Films and Their Application in ETSOI MOSFET.

    Science.gov (United States)

    Xiong, Yuhua; Chen, Xiaoqiang; Wei, Feng; Du, Jun; Zhao, Hongbin; Tang, Zhaoyun; Tang, Bo; Wang, Wenwu; Yan, Jiang

    2016-12-01

    Ultrathin Hf-Ti-O higher k gate dielectric films (~2.55 nm) have been prepared by atomic layer deposition. Their electrical properties and application in ETSOI (fully depleted extremely thin SOI) PMOSFETs were studied. It is found that at the Ti concentration of Ti/(Ti + Hf) ~9.4%, low equivalent gate oxide thickness (EOT) of ~0.69 nm and acceptable gate leakage current density of 0.61 A/cm 2 @ (V fb  - 1)V could be obtained. The conduction mechanism through the gate dielectric is dominated by the F-N tunneling in the gate voltage range of -0.5 to -2 V. Under the same physical thickness and process flow, lower EOT and higher I on /I off ratio could be obtained while using Hf-Ti-O as gate dielectric compared with HfO 2 . With Hf-Ti-O as gate dielectric, two ETSOI PMOSFETs with gate width/gate length (W/L) of 0.5 μm/25 nm and 3 μm/40 nm show good performances such as high I on , I on /I off ratio in the magnitude of 10 5 , and peak transconductance, as well as suitable threshold voltage (-0.3~-0.2 V). Particularly, ETSOI PMOSFETs show superior short-channel control capacity with DIBL <82 mV/V and subthreshold swing <70 mV/decade.

  4. Effects of Mn doping on structural, dielectric and multiferroic properties of BiFeO{sub 3} nanoceramics

    Energy Technology Data Exchange (ETDEWEB)

    Dhanalakshmi, B., E-mail: deepthi0527@gmail.com [Department of Physics, Andhra University, Visakhapatnam, 530003 (India); Pratap, K. [Thin Film Magnetism Group, Cavendish Laboratory, Department of Physics, University of Cambridge, Cambridge, CB3 0HE (United Kingdom); Rao, B. Parvatheeswara; Rao, P.S.V. Subba [Department of Physics, Andhra University, Visakhapatnam, 530003 (India)

    2016-08-15

    Undoped and Mn doped multiferroic BiFeO{sub 3} nanoparticles were synthesized by sol-gel autocombustion method. Structural studies on the samples were carried out by X-ray diffraction, scanning electron microscopy, energy dispersive spectroscopy, thermogravimetry and Fourier transform infrared spectroscopy techniques. Dielectric and conductivity measurements on the samples have been made in a wide range of frequencies and temperatures. BFO sample exhibits typical dielectric behaviour whereas the Mn doped BFO sample shows anomalous dielectric behaviour which has been attributed to charge carrier hopping mechanisms initiated by structural inhomogeneities and formation of Bi/O vacancies. Ferroelectric and magnetic studies on the samples were made by the corresponding hysteresis loop measurements. The results indicate that the doping of Mn in bismuth sites in the BiFeO{sub 3}, in spite of the enhanced conductivity, has produced considerable improvements both in remnant electric polarization (from 0.0811 to 0.6241 μC/mm{sup 2}) and saturation magnetization (from 0.53 to 2.54 emu/g) due to the enhanced magnetically driven distortion of spiral spin cycloid by the presence of Mn in mixed valance states. The improved ferroelectric and ferromagnetic properties and the possible magnetoelectric coupling between the ferroic orders of the Mn doped BiFeO{sub 3} makes it suitable for magnetoelectric devices. - Highlights: • Undoped and Mn doped BiFeO{sub 3} nanoparticles were synthesized and characterized by XRD, SEM, EDS, FTIR and TG-DTA techniques. • Chemical synthesis of BiFeO{sub 3} and Mn doped BiFeO{sub 3} leads to perovskite R3c phase with fine grained microstructures. • Mn doping brings in Mn{sup 3+} ⇔ Mn{sup 4+} conduction mechanism resulting in higher conductivity and high dielectric constants. • Mn doping causes increases in ferroelectric and magnetic orders due to enhanced magnetic ordering.

  5. Dielectric properties of solution-grown-undoped and acrylic-acid ...

    Indian Academy of Sciences (India)

    The variation of capacity with temperature is attributed to thermal expansion in the lower temperature region to the orientation of dipolar molecules in the neighbourhood of glass transition temperature ... Firstly, it enhances the chain mobility and secondly, it increases the dielectric loss by forming charge transfer complexes.

  6. Dielectric properties of solution-grown-undoped and acrylic-acid ...

    Indian Academy of Sciences (India)

    Dielectric capacities and losses were measured, in the temperature (50–170°C) and frequency (01–100 kHz range), for undoped and acrylic acid (AA) doped ethyl cellulose (EC) films (thickness about 20 m) with progressive increase in the concentration of dopant in the polymer matrix. The variation of capacity with ...

  7. Effect of Interfacial Polarization and Water Absorption on the Dielectric Properties of Epoxy-Nanocomposites

    NARCIS (Netherlands)

    Marx, Philipp; Wanner, Andrea; Zhang, Zucong; Jin, H.; Tsekmes, I.A.; Smit, J.J.; Kern, Wolfgang; Wiesbrock, Frank

    2017-01-01

    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

  8. Synthesis, structural and dielectric properties of 0.8PMN–0.2PT ...

    Indian Academy of Sciences (India)

    2017-08-29

    ) ceramics in MLC and actuator applica- tions due to its high dielectric constant and high electrostatic strain of 0.1% with low hysteresis. Further, it is an attractive replacement for BaTiO3 in MLC as it can be sintered at lower.

  9. Dielectric properties study of surface engineered nanoTiO2/epoxy ...

    Indian Academy of Sciences (India)

    2018-02-02

    Feb 2, 2018 ... [13,14]. These surface-treated ceramic nanoparticles can pro- vide improved dispersion and film quality that has potential to improve the dielectric breakdown strengths when added to polymer matrices compared with ... and phenyl phosphate (PP), were obtained from TCI Chem- icals (India) Pvt. Ltd. and ...

  10. Synthesis, structural and dielectric properties of 0.8 PMN–0.2 PT ...

    Indian Academy of Sciences (India)

    Home; Journals; Bulletin of Materials Science; Volume 40; Issue 5. Synthesis, structural and dielectric ... S A BAND2. Department of Physics, J D College Of Engineering and Management (JDCOEM), Nagpur 441501, India; Department of Physics, Yeshwantrao Chavan College of Engineering, Nagpur 441110, India ...

  11. Dielectric relaxation and optical properties of 4-amino-3-mercapto-6 ...

    Indian Academy of Sciences (India)

    ... evaluating the activation energy of the dielectric relaxation. The activation energy from the DC conductivity and the relaxation time are quite similar suggesting a hopping mechanism for AMT. The optical band gap of AMT is investigated using spectrophotometric measurement of transmittance at normal incidence of light in ...

  12. Synthesis, structural and dielectric properties of 0.8PMN–0.2PT ...

    Indian Academy of Sciences (India)

    2017-08-29

    Aug 29, 2017 ... C resulted in single-phase perovskite formation. However, high density >90% is achieved only after 1170. ◦. C. Microstructural analysis revealed that grain size increases with increase in sintering temperature. A significant increase in the peak of dielectric permittivity only after 1150. ◦. C owing to increase in ...

  13. Role of Ge incorporation in the physical and dielectric properties of ...

    Indian Academy of Sciences (India)

    The role of the third element Ge, as an impurity in the two pure binary Se75Te25 and Se85Te15 glassy alloys has been discussed in terms of the nature of covalent bonding and electronegativity difference between the elements used in making the aforesaid glassy systems. Keywords. Chalcogenide glasses; dielectric ...

  14. Characterization and Optical and Dielectric Properties of Polyvinyl Chloride/Silica Nanocomposites Films

    Directory of Open Access Journals (Sweden)

    T. Abdel-Baset

    2016-01-01

    Full Text Available Silica nanoparticles were synthesized by a sol-gel method and mixed with different amounts of polyvinyl chloride (PVC to get nanocomposite films. The samples were characterized by XRD, HR-TEM, SEM, and FTIR. High resolution transmission electron microscopy (HR-TEM proved that the average particle size of the nanosilica is 15 nm. The scanning electron microscopy (SEM showed that the nanosilica was well dispersed on the surface of the PVC films. Fourier Transform Infrared (FTIR spectra for nanocomposite films intimate a significant change in the intensity of the characteristic peaks of the functional group with addition of nanosilica. The optical band gap was found to decrease with the addition of nanosilica while the refractive index increased. The dielectric constant ε′, the dielectric loss modulus M′′, and AC conductivity (σAC were also studied. It was found that ε′ increases with temperature for all samples, clear dielectric α-relaxation observed from dielectric loss M′′ around the glass temperature (Tg, and this could be related to micro-Brownian motion of the main PVC chain. The activation energy was calculated, and the AC conductivity could be a hopping one. The results of this work are discussed and compared with previously obtained data.

  15. Dielectric and thermal properties of the methacrylate polymer bearing chalcone side group

    Science.gov (United States)

    Çelik, Taner; Coşkun, Mehmet Fatih

    2018-04-01

    The 1-(1-benzofuran-2yl)-3-(4-hydroxyphenyl)propen-1-one (compound 1) from the reaction between 1-(1-benzofuran-2-yl) ethanone and 4-hydroxybenzaldehyde was firstly synthesized. And secondly, we synthesized 4-[3-(1-benzofuran-2-yl)-3-oxoprop-1-en-1-yl] phenyl chloroacetate (compound 2) as the result of the reaction between the compound 1 and chloroacetyl chloride. The monomer was prepared by the reaction of compound 2 and sodium methacrylate. The monomer was polymerized using the free radicalic polymerization method (FRP). The structure characterization of the polymer was determined utilizing 1H,13C- NMR and FT-IR techniques. Thermal behaviour of the homopolymer was studied by measurements of TGA and DSC. For thermal decomposition kinetics of homopolymer, Flynn-Wall-Ozawa method was applied to thermogravimetry curves. The dielectric measurements were studied using the impedance analyzer technique at a frequency which varied between 100 Hz and 20 kHz Hz depending on the alternating current (AC) conductivities. The dielectric parameters such as dielectric constant and dielectric loss are changed with the temperature.

  16. Dynamic mechanical and dielectric properties of ethylene vinyl acetate/carbon nanotube composites

    Czech Academy of Sciences Publication Activity Database

    Valentová, H.; Ilčíková, M.; Czaniková, K.; Špitalský, Z.; Šlouf, Miroslav; Nedbal, J.; Omastová, M.

    2014-01-01

    Roč. 53, č. 3 (2014), s. 496-512 ISSN 0022-2348 R&D Projects: GA TA ČR TE01020118 Institutional support: RVO:61389013 Keywords : carbon nanotubes * dielectric relaxation spectroscopy * dynamic mechanical analysis Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 0.740, year: 2014

  17. Effects of LiF on microwave dielectric properties of 0.25Ca0.8Sr0 ...

    Indian Academy of Sciences (India)

    Administrator

    telecommunications. Generally, it is not easy to find materials which satisfy these three characteristics for microwave dielectric applications, because the materials with high dielectric constant have a high dielectric loss and large τf value. After the dielectric characteristics of the perovskite structure A1–xA′xBO3 are reported ...

  18. Light in complex dielectrics

    NARCIS (Netherlands)

    Schuurmans, F.J.P.

    1999-01-01

    In this thesis the properties of light in complex dielectrics are described, with the two general topics of "modification of spontaneous emission" and "Anderson localization of light". The first part focuses on the spontaneous emission rate of an excited atom in a dielectric host with variable

  19. Dielectric properties of (SWCNTs)x GdBa2CuO7‑δ superconductor nanocomposites

    Science.gov (United States)

    Anas, M.; Ebrahim, S.; Eldeen, I. G.; Awad, R.; Abou-Aly, A. I.

    2017-11-01

    Gd-123 superconducting phase was prepared by solid-state reaction technique. Single-walled carbon nanotubes (SWCNTs) were added in Gd-123 superconducting matrix with different concentrations during the final sintering process to obtain (SWCNTs)x GdBa2Cu3O7‑δ (x = 0.0-0.1 wt.%) nanoparticles-superconductor composite. The influence of SWCNTs addition on the phase formation, structural, morphological, superconducting and dielectric properties of Gd-123 phase was investigated. It was found that SWCNTs addition enhance the phase formation and does not change the crystal structure of the host Gd-123 superconducting phase. The superconducting properties of Gd-123 samples were improved after the addition of SWCNTs up to x = 0.06 wt.% due to the enhancement in intergrain connectivity by healing up of micro-cracks and reduction of defects, while these properties were retarded with further increase in x. The dielectric response of (SWCNTs)x Gd-123 superconducting phase with x = 0.0, 0.01, 0.04, 0.05, 0.06 and 0.1 wt.% was measured from 100 KHz to 5 MHz at 77 K. The results reveal that for both real (𝜀‧) and imaginary (𝜀″) parts of dielectric constant, the frequency of dispersion increased by increasing SWCNTs amount up to 0.06 wt.%, then this frequency shifted to lower values for x > 0.06 wt.%. The results were discussed according to the presence and interference of both interfacial and dipolar polarizations.

  20. Determination of basic state parameters and characterization of optical, dielectric and fluorescence properties of calcium boro lactate (CaBL)

    International Nuclear Information System (INIS)

    Vijayalakshmi, A.; Balraj, V.

    2016-01-01

    This paper describes the calculation of basic solid state parameters like penn gap, plasma energy, polarizability and fermi energy for calcium boro lactate single crystal. calcium boro lactate crystals were developed by solution growth method. Single crystal diffraction studies carried out and calculated basic solid state criterion for the CaBL compound. optical nature of these compound explained by using UV-Visible spectrum. Electro-optic behaviour of the crystal explained by dielectric studies. Light emitting properties explained by fluorescence studies. (author)

  1. Modification of electronic properties of top-gated graphene devices by ultrathin yttrium-oxide dielectric layers.

    Science.gov (United States)

    Wang, Lin; Chen, Xiaolong; Wang, Yang; Wu, Zefei; Li, Wei; Han, Yu; Zhang, Mingwei; He, Yuheng; Zhu, Chao; Fung, Kwok Kwong; Wang, Ning

    2013-02-07

    We report the structure characterization and electronic property modification of single layer graphene (SLG) field-effect transistor (FET) devices top-gated using ultrathin Y(2)O(3) as dielectric layers. Based on the Boltzmann transport theory within variant screening, Coulomb scattering is confirmed quantitatively to be dominant in Y(2)O(3)-covered SLG and a very few short-range impurities have been introduced by Y(2)O(3). Both DC transport and AC capacitance measurements carried out at cryogenic temperatures demonstrate that the broadening of Landau levels is mainly due to the additional charged impurities and inhomogeneity of carriers induced by Y(2)O(3) layers.

  2. Development of accurate UWB dielectric properties dispersion at CST simulation tool for modeling microwave interactions with numerical breast phantoms

    International Nuclear Information System (INIS)

    Maher, A.; Quboa, K. M.

    2011-01-01

    In this paper, a reformulation for the recently published dielectric properties dispersion models of the breast tissues is carried out to be used by CST simulation tool. The reformulation includes tabulation of the real and imaginary parts versus frequency on ultra-wideband (UWB) for these models by MATLAB programs. The tables are imported and fitted by CST simulation tool to second or first order general equations. The results have shown good agreement between the original and the imported data. The MATLAB programs written in MATLAB code are included in the appendix.

  3. Dielectric properties of vertically aligned multi-walled carbon nanotubes in the terahertz and mid-infrared range

    Science.gov (United States)

    Thomson, Mark D.; Zouaghi, Wissem; Meng, Fanqi; Wiecha, Matthias M.; Rabia, Kaneez; Heinlein, Thorsten; Hussein, Laith; Babu, Deepu; Yadav, Sandeep; Engstler, Jörg; Schneider, Jörg J.; Nicoloso, Norbert; Rychetský, Ivan; Kužel, Petr; Roskos, Hartmut G.

    2018-01-01

    We investigate the broadband dielectric properties of vertically aligned, multi-wall carbon nanotubes (VACNT), over both the terahertz (THz) and mid-infrared spectral ranges. The nominally undoped, metallic VACNT samples are probed at normal incidence, i.e. the response is predominantly due to polarisation perpendicular to the CNT axis. A detailed comparison of various conductivity models and previously reported results is presented for the non-Drude behaviour we observe in the conventional THz range (up to 2.5 THz). Extension to the mid-infrared range reveals an absorption peak at \

  4. Effect of H + ion implantation on structural, morphological, optical and dielectric properties of L-arginine monohydrochloride monohydrate single crystals

    Science.gov (United States)

    Sangeetha, K.; Babu, R. Ramesh; Kumar, P.; Bhagvannarayana, G.; Ramamurthi, K.

    2011-06-01

    L-arginine monohydrochloride monohydrate (LAHCl) single crystals have been implanted with 100 keV H + ions at different ion fluence ranging from 10 12 to 10 15 ions/cm 2. Implanted LAHCl single crystals have been investigated for property changes. Crystal surface and crystalline perfection of the pristine and implanted crystals were analyzed by atomic force microscope and high-resolution X-ray diffraction studies, respectively. Optical absorption bands induced by colour centers, refractive index and birefringence, mechanical stability and dielectric constant of implanted crystals were studied at different ion fluence and compared with that of pristine LAHCl single crystal.

  5. Extraordinary magnetic and structural properties of the off-stoichiometric and the Co-doped Ni.sub.2./sub.MnGa Heusler alloys under high pressure

    Czech Academy of Sciences Publication Activity Database

    Kamarád, Jiří; Albertini, F.; Arnold, Zdeněk; Fabbrici, S.; Kaštil, Jiří

    2014-01-01

    Roč. 77, Sep (2014), s. 60-67 ISSN 1359-6454 R&D Projects: GA ČR GAP204/12/0692 Institutional support: RVO:68378271 Keywords : Heusler alloys * martensitic transformation * magnetic properties * high pressure Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 4.465, year: 2014

  6. Highly aligned graphene/polymer nanocomposites with excellent dielectric properties for high-performance electromagnetic interference shielding.

    Science.gov (United States)

    Yousefi, Nariman; Sun, Xinying; Lin, Xiuyi; Shen, Xi; Jia, Jingjing; Zhang, Biao; Tang, Benzhong; Chan, Mansun; Kim, Jang-Kyo

    2014-08-20

    Nanocomposites that contain reinforcements with preferred orientation have attracted significant attention because of their promising applications in a wide range of multifunctional fields. Many efforts have recently been focused on developing facile methods for preparing aligned graphene sheets in solvents and polymers because of their fascinating properties including liquid crystallinity and highly anisotropic characteristics. Self-aligned in situ reduced graphene oxide (rGO)/polymer nanocomposites are prepared using an all aqueous casting method. A remarkably low percolation threshold of 0.12 vol% is achieved in the rGO/epoxy system owing to the uniformly dispersed, monolayer graphene sheets with extremely high aspect ratios (>30000). The self-alignment into a layered structure at above a critical filler content induces a unique anisotropy in electrical and mechanical properties due to the preferential formation of conductive and reinforcing networks along the alignment direction. Accompanied by the anisotropic electrical conductivities are exceptionally high dielectric constants of over 14000 with 3 wt% of rGO at 1 kHz due to the charge accumulation at the highly-aligned conductive filler/insulating polymer interface according to the Maxwell-Wagner-Sillars polarization principle. The highly dielectric rGO/epoxy nanocomposites with the engineered structure and properties present high performance electromagnetic interference shielding with a remarkable shilding efficiency of 38 dB. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Dielectric properties of liquid systems: study of interactions in the systems carbon tetrachloride with benzene, toluene, and p-xylene

    Directory of Open Access Journals (Sweden)

    Adrián H. Buep

    2014-12-01

    Full Text Available Intermolecular associations in liquid systems of non-polar and slightly polar compounds were studied through excess molar volumes (VEM and excess dielectric properties (εE and n2ED for mixtures of carbon tetrachloride (CCl4 with benzene (C6H6, toluene (C6H5CH3, and p-xylene (p-(CH32C6H4. These excess properties were calculated from measurements of density (ρ, static permittivity (ε, and refractive index (nD over the whole range of concentrations at 298.15 K. The values of the excess dielectric properties for these mixtures were fitted in two different ways, one through least squares using the Redlich–Kister equation and the other using a model developed to explain deviations from ideality. The first fit was found to be descriptive while the second gave the equilibrium constant values for the interaction products actually formed in the mixtures and the respective electronic polarizabilities and dipole moments, indicating the existence of interaction products.

  8. Effect of A-site substitution on crystal component and dielectric properties in Bi0.5Na0.5TiO3 ceramics

    International Nuclear Information System (INIS)

    Qu Yanfang; Shan Dan; Song Jianjing

    2005-01-01

    A-site replacement is common used in optimizing the electric properties of Bi 0.5 Na 0.5 TiO 3 (abbreviated to BNT). The effect of Ba 2+ doping in BNT capacitor ceramics is investigated here. After the samples containing 6 at.% Ba 2+ was sintered at 1180 deg. C for 2 h, capacitor ceramics with enhanced dielectric properties was fabricated, compared with pure BNT ceramics. It can be concluded from the experiment results that Ba 2+ replaced the ions in A-site, and the lattice structure was altered, which led to the improvement of dielectric properties in BNT ceramics. Then we discussed the phase transformation process from room temperature to 400 deg. C according to the dielectric properties-temperature graphs

  9. SU-F-E-10: Student-Driven Exploration of Radiographic Material Properties, Phantom Construction, and Clinical Workflows Or: The Extraordinary Life of CANDY MAN

    Energy Technology Data Exchange (ETDEWEB)

    Mahon, RN; Riblett, MJ; Hugo, GD [Virginia Commonwealth University, Richmond, VA (United States)

    2016-06-15

    Purpose: To develop a hands-on learning experience that explores the radiological and structural properties of everyday items and applies this knowledge to design a simple phantom for radiotherapy exercises. Methods: Students were asked to compile a list of readily available materials thought to have radiation attenuation properties similar to tissues within the human torso. Participants scanned samples of suggested materials and regions of interest (ROIs) were used to characterize bulk attenuation properties. Properties of each material were assessed via comparison to a Gammex Tissue characterization phantom and used to construct a list of inexpensive near-tissue-equivalent materials. Critical discussions focusing on samples found to differ from student expectations were used to revise and narrow the comprehensive list. From their newly acquired knowledge, students designed and constructed a simple thoracic phantom for use in a simulated clinical workflow. Students were tasked with setting up the phantom and acquiring planning CT images for use in treatment planning and dose delivery. Results: Under engineer and physicist supervision, students were trained to use a CT simulator and acquired images for approximately 60 different foodstuffs, candies, and household items. Through peer discussion, students gained valuable insights and were made to review preconceptions about radiographic material properties. From a subset of imaged materials, a simple phantom was successfully designed and constructed to represent a human thorax. Students received hands-on experience with clinical treatment workflows by learning how to perform CT simulation, create a treatment plan for an embedded tumor, align the phantom for treatment, and deliver a treatment fraction. Conclusion: In this activity, students demonstrated their ability to reason through the radiographic material selection process, construct a simple phantom to specifications, and exercise their knowledge of clinical

  10. SU-F-E-10: Student-Driven Exploration of Radiographic Material Properties, Phantom Construction, and Clinical Workflows Or: The Extraordinary Life of CANDY MAN

    International Nuclear Information System (INIS)

    Mahon, RN; Riblett, MJ; Hugo, GD

    2016-01-01

    Purpose: To develop a hands-on learning experience that explores the radiological and structural properties of everyday items and applies this knowledge to design a simple phantom for radiotherapy exercises. Methods: Students were asked to compile a list of readily available materials thought to have radiation attenuation properties similar to tissues within the human torso. Participants scanned samples of suggested materials and regions of interest (ROIs) were used to characterize bulk attenuation properties. Properties of each material were assessed via comparison to a Gammex Tissue characterization phantom and used to construct a list of inexpensive near-tissue-equivalent materials. Critical discussions focusing on samples found to differ from student expectations were used to revise and narrow the comprehensive list. From their newly acquired knowledge, students designed and constructed a simple thoracic phantom for use in a simulated clinical workflow. Students were tasked with setting up the phantom and acquiring planning CT images for use in treatment planning and dose delivery. Results: Under engineer and physicist supervision, students were trained to use a CT simulator and acquired images for approximately 60 different foodstuffs, candies, and household items. Through peer discussion, students gained valuable insights and were made to review preconceptions about radiographic material properties. From a subset of imaged materials, a simple phantom was successfully designed and constructed to represent a human thorax. Students received hands-on experience with clinical treatment workflows by learning how to perform CT simulation, create a treatment plan for an embedded tumor, align the phantom for treatment, and deliver a treatment fraction. Conclusion: In this activity, students demonstrated their ability to reason through the radiographic material selection process, construct a simple phantom to specifications, and exercise their knowledge of clinical

  11. Tunable dielectric properties of TiO2 thin film based MOS systems for application in microelectronics

    Science.gov (United States)

    Gyanan; Mondal, Sandip; Kumar, Arvind

    2016-12-01

    Post-deposition annealing (PDA) is an inherent part of a sol-gel fabrication process to achieve the optimum device performance, especially in CMOS applications. Annealing removes the oxygen vacancies and improves the structural order of the dielectric films. The process also reduces the interface related defects and improves the interfacial properties. Here, we applied a sol-gel spin-coating technique to prepare high-k TiO2 films on the p-Si substrate. These films were fired at 400 °C for the duration of 20, 40, 60 and 80 min to know the effects of annealing time on the device characteristics. The current-voltage (I-V) and capacitance-voltage (C-V) characteristics of annealed TiO2 films were examined in Al/TiO2/p-Si device configuration at room temperature. The 60 min annealed film gives the optimum performance and contained 69.5% anatase and 39.5% rutile phase with refractive index 2.40 at 550 nm. The C-V and I-V characteristic showed a significant dependence on annealing time such as variation in dielectric constant and leakage current. This allows us to tune the various electrical properties of MOS systems. The accumulation capacitance (Cox), dielectric constant (κ) and the equivalent oxide thickness (EOT) of the film fired for 60 min were found to be 458 pF, 33, and 4.25 nm, respectively with a low leakage current density (3.13 × 10-7 A/cm2) fired for 80 min at -1 V. The current conduction mechanisms at high bias voltage were dominated by trap-charge limited current (TCLC), while at small voltages, space charge limited current (SCLC) was more prominent.

  12. Influence of cobalt ions on spectroscopic and dielectric properties of Sb2O3 doped lithium fluoroborophosphate glasses

    Science.gov (United States)

    Kumar, G. Ravi; Srikumar, T.; Rao, M. C.; Venkat Reddy, P.; Srinivasa Rao, Ch

    2018-03-01

    Glasses with compositions (20–x) LiF–10 Sb2O3–10 B2O3–60 P2O5: x CoO (0 disorder in the glass network with increasing concentration of CoO up to 0.15 mol%. The reversal trend has been observed beyond 0.15 mol% suggesting an increasing polymerization of glass network. The optical properties of LiF–Sb2O3–B2O3–P2O5: CoO glasses were analyzed by optical absorption and photoluminescence studies. The observations from OA and PL spectral studies suggested that the gradual increase of octahedral Co2+ ions with the increase in the concentration of CoO up to 0.15 mol%. At higher concentration i.e. above 0.15 mol% of CoO, there was a reduction in the concentration of octahedral Co2+ ions. The electrical properties of the glass samples were studied by both DC and AC conductivity studies. The dielectric dispersion analysis was also performed on the prepared glass samples. The results of these studies indicated that there is a mixed conduction (both ionic and polaronic) and the polaron hoping seems to prevail over ionic conduction in the glasses containing CoO less than 0.15 mol%. The increasing space charge polarization is responsible for enhanced values of dielectric constant, dielectric loss and AC conductivity for all frequency and temperature ranges with the increase in concentration of CoO up to 0.15 mol%.

  13. Microstructure and microwave dielectric properties of Na1/2Sm1/2TiO3 filled PTFE, an environmental friendly composites

    Science.gov (United States)

    Luo, Fuchuan; Tang, Bin; Yuan, Ying; Fang, Zixuan; Zhang, Shuren

    2018-04-01

    A study on Na1/2Sm1/2TiO3 filled and glassfiber reinforced polytetrafluoroethylene (PTFE) composites was described. The GF content was a fixed value of 4 wt%, and the NST content in the composite matrix changed from 26 to 66 wt%. The paper consisted of the manufactural process of the composite and the effects of filler content on the properties of the substrate, such as morphology, moisture absorption, density, dielectric properties and temperature coefficient of dielectric constant. As NST filler loading increased from 26 to 66 wt%, the dielectric constant and loss tangent experienced a continuously increase while the development in τε was opposite. X-Ray Diffraction, FTIR and XPS were used to analyze the microstructure of modified ceramic powder. It was proved that the silane coupling agent has been grafted on the NST surface successfully. At last, the NST/GF filled PTFE composites exhibited good dielectric constant (εr = 4.95), low dielectric loss (tan δ = 0.00147), acceptable water absorption (0.036) and temperature coefficient of dielectric constant (τε = -164) at filler loading of 4 wt% GF and 46 wt% NST.

  14. Electrical properties and radiation hardness of SOI systems with multilayer buried dielectric

    International Nuclear Information System (INIS)

    Barchuk, I.P.; Kilchitskaya, V.I.; Lysenko, V.S.

    1997-01-01

    In this work SOI structures with buried SiO 2 -Si 3 N 4 -SiO 2 layers have been fabricated by the ZMR-technique with the aim of improving the total dose radiation hardness of the buried dielectric layer. To optimize the fabrication process, buried layers were investigated by secondary ion mass spectrometry before and after the ZMR process, and the obtained results were compared with electrical measurements. It is shown that optimization of the preparation processes of the initial buried dielectric layers provides ZMR SOI structures with multilayer buried isolation, which are of high quality for both Si film interfaces. Particular attention is paid to the investigation of radiation-induced charge trapping in buried insulators. Buried isolation structures with a nitride layer exhibit significant reduction of radiation-induced positive charge as compared to classical buried SiO 2 layers produced by either the ZMR or the SIMOX technique

  15. Dielectric Properties of Cd1-xZnxSe Thin Film Semiconductors

    International Nuclear Information System (INIS)

    Wahab, L.A.; Farrag, A.A.; Zayed, H.A.

    2012-01-01

    Cd 1-x Zn x Se (x=0, 0.5 and 1) thin films of thickness 300 nm have been deposited on highly cleaned glass substrates (Soda-lime glass) by thermal evaporation technique under pressure 10-5 Torr. The crystal structure, lattice parameters and grain size were determined from X-ray diffraction patterns of these films. The dielectric response and ac conductivity of the films are investigated in the frequency range from 80 Hz to 5 MHz and temperature range from 300 K to 420 K. AC conductivity increases linearly with the frequency according to the power relation σ a c (ψ)=A (ψ) s . The dielectric constant and loss show low values at high frequencies. The relaxation time t, resistance R and capacitance C were calculated from Nyquist diagram. The behavior can be modeled by an equivalent parallel RC circuit.

  16. Radio-frequency dielectric properties of some tropical African leaf vegetables

    International Nuclear Information System (INIS)

    Laogun, A.A.; Ajayi, N.O.

    1985-03-01

    The variation of the relative permittivity epsilon'sub(r), the loss factor epsilon'' and a.c. conductivity σ with the frequency of an applied electromagnetic field over the range 0.5 to 50 MHz has been studied in the leaf and stem tissues of three tropical vegetables viz - amaranthus, bitter leaf and okra. This is with a view to investigate the molecular structure and dielectric heating characteristics of the leaves and stems in the different vegetables considered. The Cole-Cole plots of the data showed that in all cases, both the stems and leaves exhibited a spread of relaxation times, indicating heterogeneity of structure. In general, the a.c. conductivity and the dielectric energy loss factor also appear to be much larger in the vegetable stems than in the leaves, suggesting that energy dissipation in stems is greater than in the leaves. (author)

  17. Gamma-irradiation effect on dielectric properties of vanadate doped polyvinyl alcohol

    International Nuclear Information System (INIS)

    Abo-Ellil, M.S.; Ahmed, M.A.; El-Ahdal, M.A.

    1997-01-01

    The real part of the dielectric constant (ε) for different concentrations (1%, 2% and 3% by wt.) of the ammonium meta vanadate doped polyvinyl alcohol was measured as a function of temperature and frequency. Different γ-ray doses (2.0, 5.0 and 10kGy) were used for samples irradiation. The dielectric constant of the samples reveals more than one peak depending on the vanadate concentration as well as the applied frequency. The main relaxation peak was discussed with reference degradation and crosslinking that vary drastically with the γ-dose. The hump that appeared at high temperature was found to be due to order-disorder transition. The variation of the internal dynamic viscosity of the sample by irradiation was found to play a role in the polarization process as well as (ε) values. Gradual increase in (ε) was obtained by increasing the γ-dose. (author)

  18. Dielectric properties of supramolecular ionic structures obtained from multifunctional carboxylic acids and amines

    DEFF Research Database (Denmark)

    Gonzalez, Lidia; Yu, Liyun; Hvilsted, Søren

    2014-01-01

    networks, formed by mixing multifunctional carboxylic acids such as citric acid (CA), tricarballylic acid (TCAA), trimesic acid (TMA), ethylenediaminetetraacetic acid (EDTA) and diethylenetriaminepentaacetic acid (DETPA) with two di ff erent Je ff amine polyetheramines (designated as D400 and D2000......), are investigated. Here the relative dielectric permittivities of the supramolecular ionic structures formed with the multifunctional carboxylic acids were lower than those from the supramolecular ionic structures formed with the two carboxymethyl ether-terminated poly(ethylene glycol)s....

  19. Dynamics of nonequilibrium conductivity of dielectrics with polaration properties controlled by in ection

    International Nuclear Information System (INIS)

    Arkhipov, V.I.; Rudenko, A.I.

    1979-01-01

    The effect of changes of radiation stimulation permittivity on nonequilibrium conductivity of dielectrics and high-resistance conductors in a radiation field has been studied theoretically. The plane-parallel sample under the constant voltage has been irradiated by penetrating radiation. The uniform radiation caused the transfer the current carriers from traps to the conduction band. The dependence of permittivity on charged traps concentration is shown to lead to negative nonequilibrium conductivity of high-resistance materials

  20. HIGH-FREQUENCY DIELECTRIC-PROPERTIES OF ALKALI AND ALKALI-HALIDE BORATE GLASSES

    NARCIS (Netherlands)

    VERHOEF, AH; DENHARTOG, HW

    Time domain reflectometry (TDR) measurements have been carried out on glasses of compositions (B2O3)1-x(Li2O)x and (B2O3)1-x-y(Li2O)x(Li2Cl2)y. Dielectric spectra have been obtained in the frequency range of 5 MHz to 10 GHz and in temperature intervals from room temperature up to values in the