Relevant bibliographies by topics / Dielectric Properties / Dissertations / Theses
To see the other types of publications on this topic, follow the link: Dielectric Properties.

Dissertations / Theses on the topic 'Dielectric Properties'

Author: Grafiati
Published: 4 June 2021
Last updated: 1 February 2025

Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles

Select a source type:

Consult the top 50 dissertations / theses for your research on the topic 'Dielectric Properties.'

Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.

You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.

Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.

1

Hu, Chuan. "Study of the thermal properties of low k dielectric thin films /." Full text (PDF) from UMI/Dissertation Abstracts International, 2000. http://wwwlib.umi.com/cr/utexas/fullcit?p9992820.

Full text
APA, Harvard, Vancouver, ISO, and other styles
2

Paz, Ana Marta. "The dielectric properties of solid biofuels." Doctoral thesis, Mälardalens högskola, Akademin för hållbar samhälls- och teknikutveckling, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:mdh:diva-10500.

Full text
Abstract:
The use of bioenergy has been increasing due to efforts in fossil fuels replacement. Modern bioenergy technologies aim for high efficiency and low pollution levels, which increases the need for methods for the on-line characterization of biofuels. Dielectric methods have been identified as useful for the sensing of solid biofuels because they allow for rapid, nonhazardous, nondestructive, and bulk determination of material properties. The dielectric properties describe the interaction between the material and the electromagnetic waves. Dielectric properties are intrinsic of the materials and can therefore be used for the development of prediction models that can be applied regardless of the measurement technique. The study of the dielectric properties is also important as it improves the understanding of the dielectric behavior of the materials. This thesis focuses on the dielectric properties of solid biofuels and their use in the characterization of these materials. The work presented includes the development of new methods permitting the determination of the dielectric properties of solid biofuels with large particle size (waveguide method), broadband measurement of the dielectric properties (coaxial-line probe), and the use of a previously developed method for the accurate determination of the dielectric properties (free-space method). The results includes the dielectric properties of solid biofuels and their dependence on parameters such as frequency, moisture, density, and temperature. This thesis also presents semi-theoretical models for the determination of moisture content, which obtained a RMSEP of 4% for moisture contents between 34 and 67%, and an empirical model that resulted in a RMSEC of 0.3% for moisture contents between 4 and 13%. Finally, this thesis includes measurements of the influence of salt content on the dielectric properties and a discussion of its use for estimation of the ash content of solid biofuels. 
APA, Harvard, Vancouver, ISO, and other styles
3

Hawkes, J. J. "Hydration dependent dielectric properties of proteins." Thesis, Bucks New University, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.383159.

Full text
APA, Harvard, Vancouver, ISO, and other styles
4

Raj, N. "Dielectric and magnetic properties of superlattices." Thesis, University of Essex, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.381931.

Full text
APA, Harvard, Vancouver, ISO, and other styles
5

Giatti, Brandon. "Optical Properties of Nanostructured Dielectric Coatings." PDXScholar, 2014. https://pdxscholar.library.pdx.edu/open_access_etds/1940.

Full text
Abstract:
Solar cells have extrinsic losses from a variety of sources which can be minimized by optimization of the design and fabrication processes. Reflection from the front surface is one such loss mechanism and has been managed in the past with the usage of planar antireflection coatings. While effective, these coatings are each limited to a single wavelength of light and do not account for varying incident angles of the incoming light source. Three-dimensional nanostructures have shown the ability to inhibit reflection for differing wavelengths and angles of incidence. Nanocones were modeled and show a broadband, multi-angled reflectance decrease due to an effective grading of the index. Finite element models were created to simulate incident light on a zinc oxide nanocone textured silicon substrate. Zinc oxide is advantageous for its ease of production, benign nature, and refractive index matching to the air source region and silicon substrate. Reflectance plots were computed as functions of incident angle and wavelength of light and compared with planar and quintic refractive index profile models. The quintic profile model exhibits nearly optimum reflection minimization and is thus used as a benchmark. Physical quantities, including height, width, density, and orientation were varied in order to minimize the reflectance. A quasi-random nanocone unit cell was modeled to better mimic laboratory results. The model was comprised of 10 nanocones with differing structure and simulated a larger substrate by usage of periodic boundary conditions. The simulated reflectance shows approximately a 50 percent decrease when compared with a planar model. When a seed layer is added, simulating a layer of non-textured zinc oxide, on which the nanocones are grown, the reflectance shows a fourfold decrease when compared with planar models. At angles of incidence higher than 75 degrees, the nanocone model outperformed the quintic model.
APA, Harvard, Vancouver, ISO, and other styles
6

Rajgadkar, Ajay. "Characterization of Dielectric Films for Electrowetting on Dielectric Systems." Scholar Commons, 2010. http://scholarcommons.usf.edu/etd/3607.

Full text
Abstract:
Electrowetting is a phenomenon that controls the wettability of liquids on solid surfaces by the application of electric potential. It is an interesting method to handle tiny amounts of liquid on solid surfaces. In recent times, researchers have been investigating this phenomenon and have reported some unexplained behavior and degradation in the Electrowetting system performance. Electrowetting systems include the presence of electric field and different materials from metals to dielectrics and electrolytes that create an environment in which corrosion processes play a very important role. With the small dimensions of the electrodes, corrosion can cause failure quickly when the dielectric fails. In this work, commonly used dielectric films such as silicon dioxide and silicon nitride were deposited using Plasma Enhanced Chemical Vapor Deposition and characterized on the basis of thickness uniformity, etch rate measurements, Dry current – voltage measurements and Wet current – voltage measurements. Sputtered silicon dioxide films were also characterized using the same methods. The correlation between Dry I – V and Wet I – V measurements was studied and a comparison of dielectric quality of films based on these measurements is presented. Also, impact of different liquids on the dielectric quality of films was studied.
APA, Harvard, Vancouver, ISO, and other styles
7

Hinchcliffe, Claire. "Processing and properties of nanocomposite dielectric films." Thesis, University of Oxford, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.437011.

Full text
APA, Harvard, Vancouver, ISO, and other styles
8

Lisachuk, G. V., R. V. Kryvobok, Y. M. Pitak, O. Lapuzina, N. A. Kryvobok, and N. S. Maystat. "Radio-absorbing materials with adjustable dielectric properties." Thesis, Chuiko Institute of Surface Chemistry of National Academy of Sciences of Ukraine, 2018. http://repository.kpi.kharkov.ua/handle/KhPI-Press/38982.

Full text
APA, Harvard, Vancouver, ISO, and other styles
9

Moulart, Alexandre Marc. "High dielectric and conductive composites for electromagnetic crystals." Thesis, Georgia Institute of Technology, 2002. http://hdl.handle.net/1853/17092.

Full text
APA, Harvard, Vancouver, ISO, and other styles
10

Payton, Gerald C. "An investigation into the dielectric properties of selenium." DigitalCommons@Robert W. Woodruff Library, Atlanta University Center, 1987. http://digitalcommons.auctr.edu/dissertations/2840.

Full text
Abstract:
The nature of chalcogenides as electrets is virtually an unexplored arena. Electrets now exist in a variety of forms such as the electroelectret, thermal electret, photoelectret, radioelectret and magnetelectrets. An investigation of selenium as a dielectric is employed using the method necessary for the preparation of thermal electrets. The effect of the various parameters such as charging time, charging temperature and sample dimensions are investigated and observed. From these observations a conclusion can be made to the type of preferred orientation taking place in the material; be it dipole orientation, ion transfer or carrier displacement.
APA, Harvard, Vancouver, ISO, and other styles
11

Abbas, Zulkifly. "Determination of the dielectric properties of materials at microwave frequencies using rectangular dielectric waveguide." Thesis, University of Leeds, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.569541.

Full text
APA, Harvard, Vancouver, ISO, and other styles
12

Dutta, Saikat Swapan. "Water absorption and dielectric properties of Epoxy insulation." Thesis, Norwegian University of Science and Technology, Department of Electrical Power Engineering, 2008. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-9723.

Full text
Abstract:

Characterization of Epoxy (diglycidyl ether of Bis-phenol A cured with Tri ethylene Tetra amine) without fillers was done. The Water absorption test at 95°C shows that at saturation the epoxy contains a water concentration of 2.089%. The diffusion coefficient of absorption is calculated as 0.021 cm2/s. The diffusion coefficient of desorption is calculated as 0.0987 cm2/s. The diffusion is almost 5 times faster than absorption. Also the material looses weight as the hydrothermal aging progresses. The water in the sample leads to chain scission which leads to the weight loss. The weight loss is more incase of absorption followed by desorption than only absorption. The chain scission leads to decrease in the mechanical strength by around 45%. The diffusion of water from the samples doesn’t affect the mechanical strength of the materials. The glass transition temperature reduces by 20°C with water inside the sample. The diffusion of water out of the sample only increases by around 10°C. The Dielectric response of the material shows that after the water absorption the sample shows high losses at lower frequencies. Also the increase in the real part of the permittivity increases with low frequency. The rapid increase in the real art of the permittivity of the material at lower frequencies can be attributed to a polarization at the electrode due both to accumulation of the charge carriers and to chain migrations. The breakdown test of the samples shows that with water in the sample the breakdown strength of the material decreases by 10 KV, but the material regains its dielectric strength when the water is diffused out. This shows that the chain scission and weight loss of the samples has no or minimum effect on the dielectric strength of the sample

APA, Harvard, Vancouver, ISO, and other styles
13

Mallinson, Phillip Martin. "Perovskite Microwave Dielectric Ceramics: Structure, Properties and Processing." Thesis, University of Liverpool, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.490899.

Full text
Abstract:
Perovskite Microwave Dielectric Ceralnics: Structure, Properties and Processing PhD thesis, Phillip M. Mallinson, University of Liverpool This thesis describes the synthesis and characterisation of several new hexagonal perovskite materials and the investigation into the processing of a commercial microwave dielectric. Chapter 1 is in two parts, the first gives an introduction to the perovskite and hexagonal perovskite structural types, and reviews the structure and properties of reported hexagonal perovskites with the AnBn-\03n general formula. The second part reviews the literature on the microwave dielectric material Ba3ZnTa209 (BZT). In Chapter 2 the details of the synthetic and analytical techniques employed are described. Chapter 3 describes the synthesis and characterisation of a number of new hexagonal perovskite materials. The eight layer compounds BagCoNb60 24 and BagCoTa6024 were found to crystallise with different structures in the space groups P 3ml and P63c11l respectively. A detailed structural description and comparison of the structures of the materials is given along with the dielectric and magnetic properties. The structure and dielectric properties of the six layer material Ba6Ca1l3Nb\4/30\g are also presented. Chapter 4 describes the synthesis and characterisation of two isostructural ten layer hexagonal perovskites with the formulas BalOMgo.25Ta7.903o and BaIOCoO.25Ta7.903o. Refinement of combined synchrotron X-ray and neutron powder diffraction data is used to determine the structures of the materials. The dielectric properties of the materials are reported and the links between dielectric loss and ordering and microstructure discussed. In Chapter 5 the results of an in-situ X-ray powder diffraction study of the ordering and domain growth ofBZT at temperatures between 1200 and 1500 °C is presented. The degree of ordering is quantified using two different methods and a rate of ordering calculated at each of the temperatures studied, from the rates of ordering the activation energy for cation transport is calculated. The ordered domain size is also quantified from the diffraction data and the dynamics compared to domain growth in other systems. Supplied by The British Library - 'The world's knowledge'
APA, Harvard, Vancouver, ISO, and other styles
14

Ieta, Adrian C. "Charge transfer & dielectric properties in hydrocarbon mixtures." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp03/MQ39835.pdf.

Full text
APA, Harvard, Vancouver, ISO, and other styles
15

Al-Dhhan, Z. T. "Dielectric properties of thin films based on CeO2̲." Thesis, Brunel University, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.380605.

Full text
APA, Harvard, Vancouver, ISO, and other styles
16

Stevenson, Paul John. "High field dielectric properties of hard PZT ceramics." Thesis, University of Manchester, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.556653.

Full text
Abstract:
At the present time there is an increasing demand for higher acoustic and electric power densities in piezoelectric transducers. The preferred material for such acoustic sources is hard (acceptor doped) lead zirconate titanate (PZT) ceramic due to a combination of desirable properties including high piezoelectric coupling factors, high ~, low electrical losses and good temperature stability. Four commercially available materials from two independent suppliers have been characterised; PZ26 and PZ28, obtained from Ferroperm Ltd, and PC4 and PC8 obtained from Morgan Matroc. The use of Mn as the acceptor dopant was found for the F erroperm materials, and Fe for the Morgan Matroc materials. A finer grain size was also observed in the Morgan Matroc materials by comparison with those from Ferroperm. Various dielectric properties of each material were investigated as a function of field amplitude, ageing time after poling and with regard to the effect of grain size and temperature. A 'threshold field' type of behaviour was observed for all materials followed by a linear increase in permittivity with field level. Such behaviour is related to the Rayleigh law, first introduced to model the behaviour of ferromagnetic materials. The most encouraging results were observed for the Morgan Matroc material with the PC8 exhibiting the most stable performance under high drive conditions. Linear plots of the real versus imaginary parts of the dielectric permittivity were observed for all materials as a function of field amplitude or ageing time an related to a ferroelectric domain wall translation mechanism. The corresponding values of tan Odw, the loss associated with domain wall translation were compared. Evidence was also found for intrinsic and reversible domain wall vibration contributions to the permittivity in the 'low field' region, while partial domain switching was observed on approaching the coercive field Ee. Field-driven de-ageing studies of poled and unpoled PZ26 ceramICS revealed a gradual reduction in the effective internal bias field Ei with time. For poled materials the reduction followed a logarithmic time law, whereas for unpoled materials an exponential decrease was observed.
APA, Harvard, Vancouver, ISO, and other styles
17

Farsari, Maria. "Dielectric and optical properties of organic photorefractive materials." Thesis, Durham University, 1996. http://etheses.dur.ac.uk/5226/.

Full text
Abstract:
The work presented in this thesis is derived from experimentation in the field of polymeric photorefractive materials. Low T(_g) polymeric composites were prepared, based on the well-known photoconductive polymer PVK (maximum 50% w/w), sensitized with TNF (2% w/w) and C(_60) (0.2% w/w), plasticized with ECZ (maximum 49.3% w/w) and doped with the nonlinear optical materials NPP (50% w/w), DAN (20% w/w), DED (5% w/w), DCNQI (0.5% w/w), ULTRA-DEMI (5% w/w) and DI-DEMI (2% w/w), and their dielectric, linear and non linear optical properties were investigated. All the materials, except DCNQI, exhibited good solubility and sample processibility. The dielectric properties of the composites at 1 KHz and 1 MHz were determined using a parallel-plate capacitance bridge. The dielectric constant and loss at 10 GHz were measured using a novel adaptation of the resonant cavity technique, which was designed for measurements at ambient and elevated temperatures. The method was used to measure of the dielectric constant and loss of two novel, high T(_g), electro-optic polymers at temperatures up to 100 ºC. The dielectric properties measured were typical of polymeric materials. The absorption coefficient and the refractive index at different wavelengths were measured using a spectrophotometer. For the refractive index, an interference fringe analysis was used. The nonlinear measurements consisted of second harmonic generation, to prove the nonhnearity of the composites, two-beam coupling measurements, to prove their photorefractivity and degenerate four-wave mixing to measure their diffraction efficiency. The NPP, DAN, DED and ULTRA-DEMI doped investigated composites exhibited second order nonlinearity with highest the one of ULTRA-DEMI, at 292 pm/V for 19 kV of corona poling field. The photorefractivity of the NPP, DAN and DED doped composites was proven at 632.8 nm, while ULTRA-DEMI doped composites photooxidized before any measurements were possible. The two-beam coupling coefficients measured were lower than 20 cm(^-3), while net gain was observed only in the NPP doped composite. The diffraction efficiencies of the NPP, DAN and DED doped composites were measured at 632.8 nm, and were found to be l0(^-5)-l0(^-6).
APA, Harvard, Vancouver, ISO, and other styles
18

Kenmuir, S. V. J. "Dielectric properties of some oxide and oxynitride glasses." Thesis, Durham University, 1986. http://etheses.dur.ac.uk/7083/.

Full text
Abstract:
The main part of this thesis describes dielectric studies on a series of oxynitride glasses prepared at Wolfson Centre for High Strength Materials, University of Newcastle upon Tyne. Bridge techniques were used to determine the room temperature values of permittivity (ε') and dielectric loss (ε") for some Y-Al-Si and Nd-Al-Si oxynitride glasses and for further compositions in the Mg-Al-Sl and Ca-Al-Si systems. Over the range 500 Hz to 10 KHz the frequency dependencies of ε' and conductivity (σ) were found to be in good agreement with the Universal law of dielectric response i.e. (ε'- ε (_∞)) oc ω((^n-1) and σ (ω) oc ω(^n) giving n = 1.0 ± 0.1 for all compositions examined. In all four systems the addition of nitrogen increased the permittivity while, at each concentration of nitrogen (including the oxide glasses) the permittivity increased with cation type in the order magnesium, yttrium, calcium, neodymlum. As regards the higher frequency regime coaxial line techniques were used to determine, at room temperature, both ε' and ε" for some Mg-Al-Si, Ca-Al-Si and Y-Al-Si oxynitride glasses over the frequency range 500 MHz to 5 GHz. Here the frequency dependencies of ε' and ε" are also consistent with the Universal Law of dielectric response in that (ε'- ε(_∞)) oc ω((^n-1)) and ε" oc ω((^n-1)) for all glass compositions. The high experimental value of the exponent (n = 1.0 ± 0.1) suggested the limiting form of lattice loss situation. In this frequency range (as also at the lower frequencies) the addition of nitrogen increased the permittivity and it was confirmed that in both the oxide and oxynitride glasses ε' is influenced by the cation, being increased with cation type in the order magnesium, yttrium, calcium as at lower frequencies. At still higher frequencies, in the microwave region, special cavity perturbation methods of measurement were developed and used. Preliminary studies are also reported on the temperature dependencies of ε' and ε" for a similar range of glass compositions and on the optical behaviour of the oxynitride glasses both in the visible and infra-red regions of the spectrum. In the Appendices summaries are given of published papers on oxynitride glasses (Appendix I) and also on single crystal MgO, Fe/MgO, Cr/MgO and Co/MgO (Appendix II) a study which formed an addendum to the main work.
APA, Harvard, Vancouver, ISO, and other styles
19

Waters, Cecilia Anne. "Optical, spectroscopic and dielectric properties of metal nanoparticles." Thesis, University of Liverpool, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.433996.

Full text
APA, Harvard, Vancouver, ISO, and other styles
20

Groenewald, Nico Albert. "Measuring the dielectric properties of crushed copper ore." Thesis, Stellenbosch : University of Stellenbosch, 2010. http://hdl.handle.net/10019.1/5230.

Full text
Abstract:
Thesis (MScEng (Process Engineering))--University of Stellenbosch, 2010.
ENGLISH ABSTRACT: Previous work has shown that microwave heating of mineral ores induces micro cracks within the ore structure, which can be attributed to the difference in the adsorption of microwaves amongst the different mineral phases. This reduces the energy required during subsequent grinding and enhances the liberation of valuable minerals. In order to design microwave applicators for this purpose, knowledge of the effective dielectric properties of the crushed ore is required. Of particular interest is the effective complex permittivity of the bulk crushed ore. The measurement of the effective permittivity of a large volume of crushed ore is most readily accomplished using the waveguide measurement technique. In this method a representative sample of the material is placed in a defined and fixed volume in a standard size rectangular section metallic waveguide. The magnitude and phase angle of the transmitted and reflected low power microwaves through and from the sample are measured. The complex permittivity can be extracted from these so-called scattering, or Sij parameters. In this study the effective complex permittivities for two porphyry copper ores and a copper carbonatite ore were determined as a function of particle size distribution (-26.5+2mm) using two sizes of waveguide (WR284 and WR340). The sample holders incorporate dielectric windows for the location of the material under test. The extraction of dielectric properties from Sij parameter measurements is problematic using standard algorithms in such cases. Accordingly a new Database Extraction (DBE) Algorithm has been developed. In this method, a database of scattering parameters is established through electromagnetic modelling of the measurement system. A search algorithm is used to determine the effective complex permittivity of the modelled load whose scattering parameters provide the best fit to the experimental data. The goodness of the experimental fit of the simulated to the measured Sij parameters is determined by a root mean squared deviation minimisation metric. Results show that the method can be used successfully to determine an effective complex permittivity for a bulk volume of the crushed material. It is concluded that the dielectric property extraction over the full operational frequency interval (2.3-3 GHz) is preferred as it has a larger degree of extraction confidence and hence reliability. Results show that with increasing particle size, the experimental fit between the simulated and measured Sij parameters becomes increasingly poor, as wall effect become more prominent. The effect is most prominent for the smaller WR284 waveguide size. It is shown that for a waveguide size of similar size to the particle size, the Sij parameter fitting is poorer compared to when a larger waveguide size is used. The extracted complex permittivity reproducibility between repeated dielectric property measurements is improved for the WR340 waveguide size, as the extractions in the WR284 waveguide is dominated by the combined particle size and wall-effects of the sample holder. Ore mineralogy is identified as a key parameter that influences the dielectric properties of the crushed ore. For ores with a dominant microwave absorbent mineral phase, the dielectric constant and loss factor is found to be larger, compared with ores with a more dominant microwave transparent gangue mineral phase.
AFRIKAANSE OPSOMMING: Navorsing toon dat die verhitting van mineraal erts, met mikrogolwe, mikroskaal frakture in die mineraalstruktuur teweeg bring weens die verskil in die adsorpsie van mikrogolwe in die verskillende mineraalfases. Gevolglik verminder die energievereiste vir die vergruising van die erts en verbeter die vrystelling van waardevolle minerale wat vasgevang is in die mineraalmatriks. Vir die ontwerp van mikrogolfapplikators vir dié doel, word die effektiewe diëlektriese eienskappe van die vergruisde erts benodig. Van spesifieke belang is die effektiewe komplekse permittiwiteit van die erts. Die effektiewe permittiwiteit van `n vergruisde materiaal monster word met behulp van die golfgeleier tegniek gemeet. Vir dié tegniek word `n verteenwoordigende monster van die materiaal in `n rigiede volume in `n standaard grootte reghoekige golfgeleier geplaas. Die grootte en fasehoek komponente van die deurgelate en weerkaatste mikrogolwe deur en van die oppervlak van die materiaal word gemeet. Die komplekse permittiwiteit van die vergruisde materiaal kan geëkstrakteer word vanaf hierdie sogenaamde verspreide, of Sij parameters. In hierdie studie word die effektiewe permitiwiteit van twee porforie koper ertse en `n koper karbonatiet erts bepaal as funksie van partikel grootte (-26.5+2 mm) deur gebruik te maak van twee standaard grootte golfgeleiers. Die monster houers inkorporeer diëlektriese vensters om die vergruisde materiaal monster in posisie te hou. In so `n geval is die ekstraksie van die diëlektriese eienskappe vanuit die Sij parameter metings problematies. Gevolglik is ‘n nuwe Databasis Ekstraksie Algoritme ontwikkel wat `n databasis van verspreide parameters opstel deur die elektromagnetiese simulasie van die metingsisteem. `n Soek-algoritme word gebruik om die effektiewe komplekse permitiwiteit van die gesimuleerde monster te bepaal wat die beste ooreenstem met dié van die gemete eksperimentele Sij parameter data. Die mate van ooreenstemming tussen die parameters, word bepaal aan die hand van die minimaliserings prosedure. Resultate toon dat dié metode geskik is vir die bepaling van die effektiewe komplekse permitiwiteit van die vergruisde monster. Dit word vasgestel dat die betroubaarheid van die geëkstraeerde Sij parameters, en gevolglik die diëlektriese eienskappe van die erts, toeneem indien die algoritme oor `n groter frekwensie band uitgevoer word. Resultate toon verder dat met toenemende partikel grootte, die mate waartoe die absolute grootte en fasehoek komponente van die gesimuleerde en gemete Sij parameters ooreenstem, versleg. Dit word toegeskryf aan wand-effekte. Hierdie verskynsel is veral opmerklik vir die kleiner grootte golfgeleier. Dit word getoon dat vir metings waar die golfgeleier dieselfde orde grootte geometriese afmetings het as die vergruisde erts self, die passing tussen die gesimuleerde en gemete Sij parameters swakker is, wanneer dit vergelyk word met metings waar dit nie die geval is nie. Die reproduseerbaarheid van die geëkstraeerde diëlektriese eienskap waardes verbeter vir lesings wat uitgevoer word in `n groter grootte golfgeleier. Laasgenoemde word toegeskryf aan die meer dominante wand-effekte wat kenmerklik is vir `n kleiner golfgeleier. Erts mineralogie word geïdentifiseer as `n sleutel parameter wat die diëlektriese eienskappe van die vergruisde materiaal beïnvloed. Beide die diëlektriese konstante en verliesfaktor is groter vir ertse met `n oorheersende mikrogolf absorberende mineraalfase.
APA, Harvard, Vancouver, ISO, and other styles
21

Ayoob, Raed. "Dielectric properties of hexagonal boron nitride polymer nanocomposites." Thesis, University of Southampton, 2017. https://eprints.soton.ac.uk/417272/.

Full text
Abstract:
There is a growing research interest in polymer nanocomposite materials due to their potential in enhancing dielectric properties. However, a considerable amount of variability exists in the literature regarding the electrical performance of polymer nanocomposites, and therefore the underlying mechanisms underpinning their electrical properties are still far from fully understood. Possible reasons for the existing inconsistencies could be due to different material preparation techniques, different nanoparticle dispersion states, unknown filler content, inconsistent sample storage conditions, and unknown water level content in the samples. Determining the principal factors that dominate the electrical behaviour of polymer nanocomposites could allow engineers to tailor the electrical properties of dielectrics for their specific application. As a result, the work reported in this thesis was mainly set out to explore the factors governing the electrical properties of polymer nanocomposites such that the inconsistencies in the literature can be better understood, and consequently eliminated. This thesis investigated the performance of hexagonal boron nitride (hBN) nanocomposites based on two thermoplastic polymers: polystyrene and polyethylene. Prior to producing any nanocomposites, the hBN particles were characterised using different techniques. The characterisation primarily revealed that the boron nitride particles are in the hexagonal form and the surface of hBN contains a scarce amount of hydroxyl groups. Polystyrene nanocomposites were prepared containing identical amounts of hBN dispersed in different solvents in an attempt to obtain different dispersion states, as a result of different hBN/solvent interactions. The effect of solvent processing was negligible on the dispersion state of the hBN in the polystyrene; no observable difference in the dispersion and electrical properties was reported although the presence of hBN resulted in a slight increase in the breakdown strength relative to the unfilled polystyrene. A range of polyethylene nanocomposites were produced containing different amounts of hBN to understand the effect of the dispersion or aggregation state of the hBN on the breakdown strength. The results revealed that the nanocomposites, regardless of the morphology, exhibited a monotonic increase in breakdown strength with increasing hBN content from 2 wt % to 30 wt %, while maintaining the low dielectric losses of the unfilled polyethylene. While the hBN was found to have a strong nucleating effect on the polyethylene, it was determined that the local change in morphology was not the cause of the enhanced breakdown strength as both the polyethylene nanocomposites obtained by rapid crystallisation, where the development of spherulites was suppressed, and the amorphous polystyrene nanocomposites, also exhibited an improved breakdown strength. Further experiments indicated that the polyethylene nanocomposites did not absorb any moisture from the environment in ambient conditions, and absorbed a very small amount of water even in the 30 wt % polyethylene/hBN nanocomposite when completely immersed in water. Dielectric spectroscopy measurements revealed that the surface hydroxyl groups on the hBN are most likely located only on the edge surfaces of the hBN rather than basal surfaces. The water was most likely loosely bound to the hBN particles, where local water clusters formed. It was remarkable that a percolating water network was not formed in a nanocomposite consisting of an already percolating hBN network, which was largely attributed to the surface chemistry of hBN. Despite the presence of water in the system, the hBN nanocomposites continued to exhibit an enhanced breakdown strength in comparison to the unfilled polyethylene. Therefore, this thesis demonstrated that the electrical behaviour of polymer nanocomposites is most likely dominated by the surface state of the nanoparticles and how the particles interact with the charge carriers; any other effects due to local morphological changes or nanoparticle dispersion are considered to be secondary reasons for changes in the electrical properties.
APA, Harvard, Vancouver, ISO, and other styles
22

Liu, Huijin. "The elastic and dielectric properties of structural ceramics." Thesis, University of Bath, 1999. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.285312.

Full text
APA, Harvard, Vancouver, ISO, and other styles
23

Chung, Colin. "Dielectrophoretic investigations of internal cell properties." Thesis, University of Edinburgh, 2015. http://hdl.handle.net/1842/10044.

Full text
Abstract:
Dielectrophoresis (DEP) is a term which describes the motion of polarisable particles induced by a non-uniform electric field. It has been the subject of research into a variety of fields including nanoassembly, particle filtration and biomedicine. The application of DEP to the latter has gained significant interest in recent years, driven by the development of microfluidic “Lab-on-a-chip” devices designed to perform sophisticated biochemical processes. It provides the ability to characterise and selectively manipulate cells based on their distinct dielectric properties in a manner which is non-invasive and label free, by using electrodes which can be readily integrated with microfluidic channels. Under appropriate conditions a biological cell will experience a DEP force directing it either towards or away from concentrations in the electric field. At a so-called “crossover frequency” the cell is effectively invisible to the field resulting in no DEP force, a response typically observed in the 1 kHz to 1 MHz range. Its value is a function of cell membrane dielectric properties and has been the subject of research directed at devices capable of using it to both characterise and sort cells. The aim of this work was to investigate the behaviour of a higher frequency crossover referred to as fxo2, predicted to occur in the 1 MHz to 1 GHz range. At these frequencies the electric field is expected to penetrate the cell membrane and behave as a function of intracellular dielectric properties. Standard lithography techniques have been used to fabricate electrodes carefully designed to operate at these frequencies. The existence of fxo2 was then confirmed in murine myeloma cells, in good agreement with dielectric models derived from impedance spectroscopy. A temperature dependent decrease in its value was observed with respect to the time that cells were suspended in a DEP solution. This decrease is consistent with previous studies which indicated an efflux of intracellular ions under similar conditions. An analytical derivation of fxo2 demonstrates its direct proportionality to intracellular conductivity. Direct control of the crossover was achieved by using osmotic stress to dilute the intracellular compartment and thereby alter its conductivity. By using a fluorophore which selectively binds to potassium, a strong relationship has been demonstrated between the value of fxo2 and the concentration of intracellular potassium. Measurements of fxo2 for an unfed culture demonstrated a correlation with viability and subtle shifts in its distribution were caused by the early stages of chemically induced apoptosis.
APA, Harvard, Vancouver, ISO, and other styles
24

Castro, Armando Josà Neves de. "Estudo das Propriedades DielÃtricas da Matriz CerÃmica FeNbTiO6:(ZnO)x para aplicaÃÃes em Radio-FrequÃncia (RF) e Micro-ondas." Universidade Federal do CearÃ, 2014. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=11535.

Full text
APA, Harvard, Vancouver, ISO, and other styles
25

Duong, Danny. "The complex dielectric properties of aqueous ammonia from 2 GHz - 8.5 GHz in support of the NASA Juno mission." Thesis, Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/42891.

Full text
Abstract:
A new model for the complex dielectric constant, ε, of aqueous ammonia (NH4OH) has been developed based on laboratory measurements in the frequency range between 2-8.5 GHz for ammonia concentrations of 0-8.5 %NH3/volume and temperatures between 277-297 K. The new model has been validated for temperatures up to 313 K, but may be consistently extrapolated up to 475 K and ammonia concentrations up to 20 %NH3/volume. The model fits 60.26 % of all laboratory measurements within 2σ uncertainty. The new model is identical to the Meissner and Wentz (2004) model of the complex dielectric constant of pure water, but it contains a correction for dissolved ammonia. A description of the experimental setups, uncertainties associated with the laboratory measurements, the model fitting process, the new model, and its application to approximating jovian cloud opacity for NASA's Juno mission to Jupiter are provided.
APA, Harvard, Vancouver, ISO, and other styles
26

Li, Wensheng. "Dielectric properties and defects structure of lead tungstate crystal." HKBU Institutional Repository, 2000. http://repository.hkbu.edu.hk/etd_ra/222.

Full text
APA, Harvard, Vancouver, ISO, and other styles
27

Hinedi, Mohamad Fahd 1964. "HIGH FREQUENCY DIELECTRIC PROPERTIES OF POLYIMIDES FOR MULTILAYER INTERCONNECT STRUCTURES." Thesis, The University of Arizona, 1987. http://hdl.handle.net/10150/276497.

Full text
Abstract:
One of the most important electrical requirements in high performance electronic systems or high speed integrated circuits, is to process larger numbers of electrical signals at much higher speeds. Signal propagation delay must be minimized in order to maximize signal velocities. Therefore, material with low dielectric constant and low dissipation factor is being sought. In this thesis research measurements of dielectric constant and dissipation factor were performed on commercially available polyimides that are used in multilayer interconnect structures. Capacitor structures with a polyimide dielectric were measured up to a 1GHz frequency and 220°C temperature. Polyimides were concluded to be compatible for use in high performance systems such as multilayer interconnect structures.
APA, Harvard, Vancouver, ISO, and other styles
28

Helgeson, Anders. "Analysis of dielectric response measurement methods and dielectric properties of resin-rich insulation during processing." Doctoral thesis, KTH, Electric Power Systems, 2000. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-2972.

Full text
Abstract:

The dielectric diagnostic methods ofpolarisation/depolarisation currents and recovery voltage,which are time domain methods, and capacitance and tandmeasurements at different frequencies, which is a frequencydomain method, have been studied here. In the first part of thethesis, these measurement methods are analysed and evaluated.Three different types of insulation systems are included in theevaluation, oil/paper ("high" loss), resin-rich mica tape("medium" loss) and cross-linked polyethylene, XLPE, ("low"loss). These three systems have different dielectric responsein both shape and magnitude. Conclusions are made regardingchoice of measurement method depending on the dielectricresponse of the insulation material. Examples are also given ofhow to estimate conductivity and the dielectric responsefunction in the time domain from measurements with a finitecharging period.

Furthermore, relations between time domain and frequencydomain and the possibilities of Fourier transforming data fromone domain to the other are discussed. Fourier transforming isdone with a spline approximation technique, the Hamonapproximation and by fitting base functions that have analyticFourier transforms to measured data. These techniques arereviewed with special attention to the problem of estimatingdata outside the measurement window.

The second part of the thesis includes studies of the changeof dielectric properties during the manufacturing stage of acomposite insulation used in high voltage rotating machines.The insulation consists of a resin-rich mica tape with wovenglass or polyester film (PET) as carrier material. The aim wasto improve the quality of the composite insulation byoptimising the heat and pressure cycle used in theproduction.

A test cell has been designed and built to be able toprocess simple parallel plate samples under conditions similarto the factory process. With a maximum heating rate of 9°C/min and a maximum cooling rate of 20° C/min arbitrarytemperature paths could be programmed. All samples wereprocessed under static pressure in the MPa range.

The chemical reaction during curing of the resin-rich micatape was studied with differential scanning calorimetry (DSC).A simple reaction rate model was fit to the DSC measurementsmaking it possible to calculate the degree of curing during anarbitrary temperature path.

The change of dielectric response with time during curingunder different temperature paths and at a constant pressurewas monitored. Both laboratory experiments and factorymeasurements have been made and based on these measurements asimple network model is proposed to explain the measureddielectric response in terms of material structure and degreeof curing.

Keywords: Dielectric response, diagnostic methods, Hamon,Fourier transform, rotating-machine, insulation, resin-rich,mica tape, curing, process, monitoring, differential scanningcalorimetry (DSC), network model.

APA, Harvard, Vancouver, ISO, and other styles
29

Al, Kabsh Asma. "Optical properties and energy applications of MoS2." OpenSIUC, 2018. https://opensiuc.lib.siu.edu/dissertations/1636.

Full text
Abstract:
Transition metal Dichalcogenide MoS2in the monolayer and few-layer form have generated intense interest in the fundamental and applied research community due to its surprisingly strong light-matter interactions, strong excitonic effect, and unique elec-tronic and chemical activity at the edges. In this thesis work, I have conducted a series of synergistic experimental and computational investigations focused on understanding the fundamental optical properties of few-layer MoS2(experiment with supporting computational calculations) and its potential application into the electrochemical reduction of CO2(computational)In the first part of the thesis, I show that sulfur vacancies affect the optical properties of few-layer thin films deposited using magnetron sputtering. In particular, I show that sulfur vacancies can obscure the well-defined A/B excitons in MoS2. Next, while contributing with the process of developing high-quality MoS2films, I designed an approach to accurately determine the optical constants by combining transmission spectroscopy with spectroscopic ellipsometry. The method, which we call Transmission-assisted spectroscopic ellipsometry (TASE), is demonstrated on high-quality MoS2films deposited on transparent and absorbing substrates. Next, Transmission spectroscopy combined with the Kramers-Kronig consistent optical model was employed to determine the complex dielectric function of few-layer MoS2in the broadband energy range of 0.7-6.5 eV. Optical transitions leading to peaks in the dielectric functions are assigned to the band structure. In particular, a new peak is observed and assigned at 4.5 eV in few-layer MoS2. Finally, I have examined the effectiveness of doped MoS2on the catalytic activity for CO reduction using density functional theory method. The structural calculation shows that doping Mo edge site of MoS2with transition metals that have higher work function than Mo atom results a lowering in the CO adsorption energy which suppresses the dissociation reaction and enhances the hydrogenation reaction. The Bader charge analysis shows that the dopant atom does not contribute to CO adsorption directly but it reduces the charge density at the edge atom that is indicated from the Density of states.
APA, Harvard, Vancouver, ISO, and other styles
30

Alshami, Ali Saleh. "Dielectric properties of biological materials : a physical-chemical approach." Online access for everyone, 2007. http://www.dissertations.wsu.edu/Dissertations/Spring2007/A_Alshami_053107.pdf.

Full text
APA, Harvard, Vancouver, ISO, and other styles
31

Swarup, Arvind. "Experimental characterisation of the dielectric properties of tumor tissues." Thesis, University of Ottawa (Canada), 1987. http://hdl.handle.net/10393/5162.

Full text
APA, Harvard, Vancouver, ISO, and other styles
32

Shinton, S. E. "Optical and dielectric properties of polymer dispersed liquid crystals." Thesis, Swansea University, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.639025.

Full text
Abstract:
Polymer Dispersed Liquid Crystals (PDLCs) are attracting considerable attention for new optical displays. This thesis describes the synthesis of PDLC materials, fabrication of cells and study of their optical and dielectric behaviour. This work includes two areas of research. Predominantly it is an investigation of the properties of PDLCs prepared using Polymerisation Phase Separation (PIPS) by UV irradiation of mutually soluble liquid crystal (LC) and pre-polymer materials, developed for use in PDLC systems. A limited study of liquid crystal gels completes the thesis. We demonstrate that the electro-optical response of a PDLC is due to alignment of the LC phase, illustrated by comparison of the dielectric behaviour of the PDLC and LC in an aligning field. It is evident from this work that there is solubility of the LC component in the polymer that forms the continuous phase. Therefore, only at higher concentrations of the LC component (above 30%) will the PDLC be formed, and in such materials, the continuous phase contains dissolved LC material. Variation of experimental conditions under which samples are prepared, by changing the composition, temperature of cure and the presence of aligning fields, leads to modifications in the structure and properties of PDLCs, which are investigated. Techniques to study the dielectric, electro-optic and optical properties have been applied to the range of samples prepared. Such studies give information on the alignment of the LC phase in a PDLC in directing electric fields. It is demonstrated that dielectric relaxation spectroscopy (DRS) provides direct information on the macroscopic orientation and voltage induced changes in the alignment of gels produced in the presence and absence of electric fields. Our studies show that DRS, in combination with optical techniques, provides a powerful means for studying the alignment of LC molecules in PDLCs and gels.
APA, Harvard, Vancouver, ISO, and other styles
33

Donnelly, N. J. "Dielectric and electromechanical properties of PMN-PT thin films." Thesis, Queen's University Belfast, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.426713.

Full text
APA, Harvard, Vancouver, ISO, and other styles
34

Pevzner, Boris. "Transport and dielectric properties of thin fullerene (C₆₀) films." Thesis, Massachusetts Institute of Technology, 1996. http://hdl.handle.net/1721.1/41403.

Full text
APA, Harvard, Vancouver, ISO, and other styles
35

Rimbi, Morris. "Wood microwave dielectric heating and measurement of material properties." Thesis, Stellenbosch : Stellenbosch University, 2004. http://hdl.handle.net/10019.1/50231.

Full text
Abstract:
Thesis (PhD)--University of Stellenbosch, 2004.
ENGLISH ABSTRACT: Microwave heating technology is extensively used in households, is well-established in certain industries and is being explored in others. lts attraction is that it is quick, energy efficient, clean and can be used to heat materials of both high and low thermal conductivities. Successful application of the technology requires knowledge of both material properties and microwave equipment. Commercial fixtures for measuring dielectric properties are not widely available and are usually created in-house. The domestic oven magnetron is easily available and can be used in prototype microwave systems but applicators for specific applications need development. This thesis covers three main areas, namely; dielectric measurement fixtures, microwave applicators and chokes, and drying of wood. The first part of the thesis presents four dielectric measurement fixtures, one commercial and the others in-house. The design and calibration of the in-house fixtures is presented. An intercomparison of the performance of the four fixtures is carried out by measuring the permittivities of well characterised dielectrics: teflon and perspex. The most convenient fixture is used to measure the dielectric properties of wood at different moisture contents. The second part covers the design of a slotted waveguide fed microwave applicator and a choke. The design of the slotted feed is carried out analytically with and without mutual coupling between the slots. A semi-empirical design using a finite element package is done independent of the analytical approach and the results are compared. The choke is rigorously characterised using a procedure which avoids de-embedding. The third and last section reports on the wood drying experiments carried out in the applicator, simulated and mapped heating patterns of drying wood, and a mock-up industrial wood drying facility.
AFRIKAANSE OPSOMMING: Mikrogolfverhittingstegnologie word wyd gebruik in huishoudings, is goed gevestig in sekere nywerhede en moontlike gebruike daarvan op ander gebiede word gedurig ondersoek. Die vernaamste voordele is dat dit vinnig, energiedoeltreffend en skoon is en dat dit gebruik kan word om materiale van beide hoë en lae termiese geleidingsvermoë te verhit. Suksesvolle toevoeging van die tegnologie vereis kennis van beide materiale-eienskappe en mikrogolftoerusting. Kommersiële apparaat vir die meet van diëlektriese eienskappe is nie wyd beskikbaar nie en word gewoonlik "binnenshuis" ontwikkel. Die huishoudelike mikrogolfoond magnetron is geredelik beskikbaar en kan in prototipe mikrogolfstelsels gebruik word, maar toevoegers geskik vir spesifieke gebruike moet ontwikkel word. Hierdie proefskrif dek drie hoofgebiede, naamlik: diëlektriese metingsapparaat, mikrogolftoevoegers en smoorders, en die droging van hout. Die eerste deel van die proefskrif handeloor vier diëlektriese metingsapparate, een kommersiëel en die ander "binnenshuis". Die ontwerp en kalibrasie van die "binnenshuis" apparate word aangebied. 'n Tussenvergelyking van die verrigtinge van die vier apparate word gedoen deur die meting van baie bekende diëlektrikums: teflon en perspex. Die mees gerieflike apparaat word gebruik vir die meet van die diëlektriese eienskappe van hout teen verskillend voginhoude. Die tweede deel dek die ontwerp van 'n smoorder en 'n mikrogolf toevoeger wat deur 'n gegleufde golfgeleier gevoer word. Die ontwerp van die gegleufde golfgeleier word beide met en sonder wedersydse koppeling tussen die gleuwe, analities gedoen. 'n Semi-empiriese ontwerp wat van 'n eindige-element pakket gebruik maak, is onafhanklik van die analitiese benadering gedoen. Die resultate word dan vergelyk. Die smoorder word deur 'n prosedure wat "de-embedding" vermy, streng gekarakteriseer. Die derde en laaste afdeling behandel die eksperimentele droging van hout binne die toevoeger. Simulasies en verhittingspatrone van die hout wat gedroog word, sowel as die "mock-up(model van die voorgestelde)" nywerheids houtdroogkamer, word gegee.
APA, Harvard, Vancouver, ISO, and other styles
36

Klein, Robert James. "Dielectric properties of conductive ionomers." 2007. http://www.etda.libraries.psu.edu/theses/approved/WorldWideIndex/ETD-1742/index.html.

Full text
APA, Harvard, Vancouver, ISO, and other styles
37

Li, Yi-Sian, and 李羿賢. "Dielectric Properties of Guss Asphalt." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/56552245873546738978.

Full text
Abstract:
碩士
國立成功大學
土木工程學系碩博士班
97
For the quality of pavement density, the core test of Guss asphalt on an orthotropic steel deck bridge would damage the deck, and the location after that test would be a weakness for erosion, so need to use a non-destructive pavement density measurement. The process of non-destructive methods by an electromagnetic way, the dielectric constant is one of the most important parameters to influence behavior of an electromagnetic way. This study measured the dielectric properties of Guss mastic, aggregate, and Guss asphalt specimens by network analyzer and an open-ended coaxial probe, and discussed the relationship between the dielectric constant and air void, density, bitumen content, and temperature at 2.55GHz frequency range. Then this study established the dielectric mixing model and the density predicting model, and furthermore measured density of Guss asphalt specimens by the nonnuclear pavement density gauge PaveTacker, then the PaveTacker value after calibration was compared with measured value. The results showed linear relationship between air void and the dielectric constant, density and the dielectric constant, and R2 was about 0.6. The influence of bitumen content on the dielectric constant was not significant. In temperature range, the dielectric constant of Guss asphalt specimens decreased with the cooling of temperature in 90�薡 to 60�薡. As for the dielectric mixing model of Guss asphalt, the dielectric constant value of the specimens was calculated by the dielectric constant and volume fraction of Guss mastic, aggregate, pulverized limestone, and air. And for the density predicting model of Guss asphalt, the density value of Guss asphalt was calculated by the dielectric constant value, R2 of the regression of the density value by calculating of the density value by measured was 0.78. Moreover, this study calibrated the nonnuclear pavement density gauge PaveTacker value, and R of the regression of the PaveTracker value after calibration of the density value by measured was raised 0.89 from 0.38.
APA, Harvard, Vancouver, ISO, and other styles
38

Maharaj, Saritarani. "Dielectric properties of Polymer Electrolyte." Thesis, 2012. http://ethesis.nitrkl.ac.in/3565/1/Sarita_thesis.pdf.

Full text
Abstract:
A series of polymer electrolyte having Na+ ion as the principal charge carrier has been prepared by solution casting technique and analyzed with different experimental techniques. In the present study, sodium iodide (NaI) was taken as the salt and poly (ethylene oxide), PEO was taken as the polymer host for polymer-salt complexation. Solution cast method was used to prepare polymer electrolytes of different polymer to salt ratio (O/Na= 0, 20, 40, 60, 80, 100). The structural characterization was carried out using X-ray diffraction. The XRD pattern showed the formation of polymer-salt complexation with the existence of both crystalline and amorphous phases in the materials. This semicrystalline nature of polymer electrolyte was observed by microstructural characterization using Scanning Electron Microscope. The electrical properties of polymer electrolytes were carried out using complex impedance analysis in the frequency range of 100 mHz to 1MHz at room temperature. Dielectric properties, a.c. conductivity and impedance data were analyzed with respect to different frequency and different compositions.
APA, Harvard, Vancouver, ISO, and other styles
39

Behera, Pallavi Suhasinee. "Dielectric properties of polymer electrolyte." Thesis, 2012. http://ethesis.nitrkl.ac.in/3570/1/PALLAVI.pdf.

Full text
Abstract:
The preliminary structural, microstructural and dielectric properties of the polymer electrolytes based on Polyethylene oxide (PEO) as polymer and Sodium Iodide (NaI) as salt were investigated. The samples were prepared by solution cast method by taking different concentration of O/Na ratio (i.e., O/Na =0, 20, 40, 60, 80, 100). The structural characterization was carried out by using X ray diffraction (XRD) technique which shows that the polymer electrolyte is semi-crystalline in nature. From the XRD data the crystallite size and inter planar spacing of the polymer electrolyte were also calculated. The surface morphology was analysed by Scanning electron microscope (SEM) which shows the presence of spherulites which is the crystalline phase and it is separated by amorphous boundary. The electrical properties of the polymer electrolyte were studied using complex impedance analysis. In order to optimize the conductivity and dielectric properties, dielectric parameter, ac conductivity, and impedance of the polymer electrolyte samples were analysed.
APA, Harvard, Vancouver, ISO, and other styles
40

Ruei-ZhungLee and 李瑞中. "Improved Dielectric Properties and Applications of ZnTiNb2O8 Microwave Dielectric Ceramics." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/53697400866674740761.

Full text
APA, Harvard, Vancouver, ISO, and other styles
41

Lin, Shih-Hung, and 林士弘. "Improved Microwave Dielectric Properties and Application of Mg0.95Co0.05TiO3 Dielectric Ceramics." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/79398852645936487319.

Full text
Abstract:
碩士
國立成功大學
電機工程學系碩博士班
93
Improved Microwave Dielectric Properties and Applications of Mg0.95Co0.05TiO3 Ceramics Shih-Hung Lin* Cheng-Liang Huang** Department of Electrical Engineering National Cheng Kung University, Taiwan, R.O.C. Abstract The microwave properties of Mg0.95Co0.05TiO3dielectric ceramic materials are discussed in this paper. By adding different sintering aids ZnO and CuO respectively, we study the existence effects of liquid phase for the microwave properties of Mg0.95Co0.05TiO3. The experiment results show that with 1wt% ZnO addition can efficiently reduce sintering temperature from 1350 oC to 1250 oC, and we obtain that the dielectric properties are εr~28，Q×f~50000(GHz) and τf~14(ppm/oC). Concerning about the negative value of τf , we choose adding the Zn0.975Ca0.025TiO3 (+30(ppm/oC)) to adjust the value approaching to zero. At 1200 oC, 0.7Mg0.95Co0.05TiO3-0.3Zn0.975Ca0.025TiO3appears the best property: εr~22.6, Q×f~57000(7GHz) andτf~0(ppm/oC) . Hence, the microwave properties of dielectric ceramic materials is improved.. Hence, the microwave properties of Mg0.95Co0.05TiO3 dielectric ceramic materials is improved. In addition, we design and fabricate a third order compact elliptic function low-pass filters using microstrip stepped-impedance hairpin resonators with 1.8GHz 3dB cutoff frequency on FR4、Al2O3、 Mg0.95Co0.05TiO3 substrate. *The Author **The Advisor
APA, Harvard, Vancouver, ISO, and other styles
42

Borthakur, Swarnal Ho P. S. "The effects of post-ash cleaning and chemical treatments on the dielectric properties and reliability of Cu/low-k interconnect structures." 2005. http://repositories.lib.utexas.edu/bitstream/handle/2152/1826/borthakurs44073.pdf.

Full text
APA, Harvard, Vancouver, ISO, and other styles
43

Zhe-WeiXie and 謝哲偉. "Microwave Dielectric Properties and Microwave Applications of 0.9Li2MgTi3O8-0.1Li2ZnTi3O8 Dielectric Ceramics." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/04456037954712865085.

Full text
APA, Harvard, Vancouver, ISO, and other styles
44

Chang, Chia-Hao, and 張家豪. "Dielectric Properties of Polyaniline／Silver Nanocomposites." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/63424323859831872735.

Full text
Abstract:
碩士
中原大學
物理研究所
99
Abstract In this study, we mixed dedoped polyaniline powder (average diameter of 150 nm) with silver nanoparticles (~ 150nm) in various ratios uniformly. These nanocomposite mixtures were compressed into pellets and their electrical properties were analyzed. We found that when the volume-volume percentage (v/v%) of silver particles was over 6%, percolation effect occurred, and the percolation threshold was much less than that (~16v/v%) of the classical percolation theory. This phenomenon might be due to the aggregation of silver particles in the mixing process. The conductivity of the percolated nanocomposite sample was 1.94×10-2 S/cm, which was much higher than that of pure polyaniline (2.63×10-8 S/cm). In the analysis of the dielectrical properties of the samples, the relative dielectric constant was found to be negative when the percolation effect occurred. It could be explained by referring the electron gas model. The results of our AC conductivity measurements also showed that the percolation threshold of our experiment is different from that of the classical theory. The pressure of the sample compress process also affected the DC conductivity of the nanocomposites. The conductivity increased with increasing pressure. After annealing treatment, we found that the DC conductivity of the sample compressed by lower pressure decreased obviously, and the AC conductivity had a similar behavior. The relative dielectric constant increased with increasing pressure, and decreased with increasing frequency. Finally, the polyaniline/Ag nanocomposites were investigated through variable temperature electrical measurements, and the I-V curves of the nanocomposites were analyzed at low temperature.
APA, Harvard, Vancouver, ISO, and other styles
45

Tsai, Chih-Hung, and 蔡志泓. "Microwave dielectric properties of YNbO4 ceramics." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/92325415580090647450.

Full text
Abstract:
碩士
崑山科技大學
電子工程研究所
101
YNbO4 microwave dielectric ceramics prepared by a reaction-sintering process were investigated. The mixture of raw materials was sintered directly and no calcination stage was involved. Single phase YNbO4 ceramics with monoclinic structure were obtained. Sintering temperature was lowered with the addition of CuO and some Cu-rich phases formed at the grain boundaries. Maximum density 5.14 g/cm3 and shrinkage 15.02% were found in 1250oC/6h sintering YNbO4 with 0.3wt.％ CuO addition（YNC3）. Maximum density 5.09 g/cm3 and shrinkage 16.9% were found in 1100oC/6h sintering YNbO4 with 0.3wt.％ CuO addition（YNC5）. Microwave dielectric properties: εr＝15.53, Qxf＝14,174 GHz (10.33GHz) and τf＝－39.73 ppm/oC were obtained for 1300oC/6h sintering YNC3 ceramics. εr＝15.69, Qxf＝18,420 GHz (10.17GHz) and τf＝－35.76 ppm/oC were obtained for 1250oC/6h sintering YNC5 ceramics.
APA, Harvard, Vancouver, ISO, and other styles
46

HU, Lun-Wei, and 胡倫維. "Dielectric properties of polymer thin films." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/3rj937.

Full text
Abstract:
碩士
中原大學
物理研究所
106
The effect of charge transport mechanism on the dielectric properties of polymers and polymers/composites has been studied by impedance spectroscopy in frequency range from 20 Hz to 3 MHz. At first, the polyaniline (PANI) samples were discussed. The PANI powder synthesized from chemical oxidative polymerization was de-doped by NaOH, dissolved in NMP solvent, and then casted in the form of polyaniline emeraldine base (PANI EB) thin film. Whereas the polyaniline emeraldine salt (PANI ES) thin film was redoped by putting PANI EB thin film into an HCl solvent for 24 hours. The PANI EB thin films had low conductivity about 1×〖10〗^(-11) S/cm, low dielectric loss (1 ~ 0.03), and low dielectric constant at 20 Hz. On the other hand, the PANI ES thin films with charge transport by π-π bonding possessed high conductivity (2×〖10〗^(-6) S/cm) and high dielectric loss (~ 100) at 20 Hz. The counter ions from acidic dopants also contributed the polarization density and led to a large dielectric constant. Next, polyimide (PI) samples were made by using different thermos-imidization temperatures (150℃, 270℃, and 350℃) to control the asymmetry along polymeric chains and the density of hydrophilic functional groups. Compared to PIB-270℃ and PIB-350℃, PIB-150℃ sample had more hydrophilic functional groups, and hence showed a sensitive frequency dependence of dielectric constant and possessed a larger dielectric loss. Then, the polyimide samples with and without carbon black (PI/CB and PI) were chosen to study their dielectric properties. A dielectric absorption peak (f_max) was observed at around 200 Hz in PI/CB at room temperature. This peak increased with increasing temperature, which was matched to the Debye relaxation model. An activation energy of 340 ± 13 meV corresponding to interface polarization in heterostructure was calculated from the Arrhenius plot. Finally, the dielectric properties of epoxy samples mixed with different weight percentages (1, 5, 15, and 20 wt%) of UiO-66-NH2 (epoxy/UiO-66-NH2) were studied. Because of the hydrophilic functional groups in UiO-66-NH2, as the samples removed from the vacuum system to atmospheric environment for measurement, the adsorbed water molecules resulted an increasing dielectric constant with respect to time, and the corresponding fmax for Debye relaxation was shifted to higher frequency and approached to nearly equilibrium after 72 hours.
APA, Harvard, Vancouver, ISO, and other styles
47

"Dielectric microspheres as optical cavities." Chinese University of Hong Kong, 1988. http://library.cuhk.edu.hk/record=b5885964.

Full text
APA, Harvard, Vancouver, ISO, and other styles
48

Lin, Chen-yu, and 林震宇. "Synthesis,analysis and dielectric properties of (Ba,Sr)Sm2Ti4O12 microwave dielectric ceramic." Thesis, 1998. http://ndltd.ncl.edu.tw/handle/94349369171876984045.

Full text
APA, Harvard, Vancouver, ISO, and other styles
49

Lin, Zhen-Yu, and 林震宇. "Synthesis,analysis and dielectric properties of (Ba,Sr)Sm2Ti4O12 microwave dielectric ceramic." Thesis, 1998. http://ndltd.ncl.edu.tw/handle/34179504151203878287.

Full text
APA, Harvard, Vancouver, ISO, and other styles
50

"Dielectric behavior of colloidal suspensions." 2005. http://library.cuhk.edu.hk/record=b5892657.

Full text
Abstract:
Yam Chi Tong = 懸浮顆粒之介電反應 / 任智堂.
Thesis (M.Phil.)--Chinese University of Hong Kong, 2005.
Includes bibliographical references (leaves 76-79).
Text in English; abstracts in English and Chinese.
Yam Chi Tong = xuan fu ke li zhi jie dian fan ying / Ren Zhitang.
Chapter 1 --- Introduction --- p.1
Chapter 2 --- Spectral Representation of a Pair of Polydisperse Cylinders --- p.3
Chapter 2.1 --- Introduction --- p.3
Chapter 2.2 --- Multiple Image Method --- p.4
Chapter 2.2.1 --- Polydispersity in Size --- p.6
Chapter 2.2.2 --- Polydispersity in Permittivity --- p.7
Chapter 2.3 --- Spectral Representation --- p.9
Chapter 2.3.1 --- Polydisperse Size Cylinders --- p.10
Chapter 2.3.2 --- Polydisperse Permittivity Cylinders --- p.12
Chapter 2.4 --- Numerical Results --- p.13
Chapter 2.4.1 --- Polydispersity in Size --- p.14
Chapter 2.4.2 --- Polydispersity in Permittivity --- p.17
Chapter 2.5 --- Conclusion --- p.22
Chapter 3 --- Dielectric Behaviors of Polydisperse Colloidal Suspensions --- p.24
Chapter 3.1 --- Introduction --- p.24
Chapter 3.2 --- Dielectric Dispersion Spectral Representation --- p.26
Chapter 3.3 --- Polydisperse Colloidal Suspensions --- p.28
Chapter 3.4 --- Numerical Results --- p.30
Chapter 3.4.1 --- Monodisperse Limit --- p.31
Chapter 3.4.2 --- Influence of the Medium Conductivities --- p.32
Chapter 3.4.3 --- Effect of Conductivity Contrasts --- p.34
Chapter 3.4.4 --- Effect of Varying the Volume Fractions --- p.37
Chapter 3.5 --- Conclusion --- p.41
Chapter 4 --- Dielectric Behaviors of Shelled Cell Suspensions --- p.43
Chapter 4.1 --- Introduction --- p.43
Chapter 4.2 --- Shelled Spherical Particle Model --- p.46
Chapter 4.2.1 --- Intrinsic Dispersions --- p.47
Chapter 4.3 --- Numerical Results --- p.49
Chapter 4.3.1 --- One Type of Shelled Cells --- p.51
Chapter 4.3.2 --- Mixture of Two Types of Shelled Cells --- p.60
Chapter 4.4 --- Conclusion --- p.62
Chapter 5 --- Dielectric Behaviors of Compositionally Graded Films --- p.64
Chapter 5.1 --- Introduction --- p.64
Chapter 5.2 --- Discrete Layer Model --- p.65
Chapter 5.2.1 --- Linear Profiles --- p.67
Chapter 5.2.2 --- Gaussian Profiles --- p.67
Chapter 5.3 --- Continuously Graded Model --- p.68
Chapter 5.3.1 --- Linear Profiles --- p.68
Chapter 5.3.2 --- Gaussian Profiles --- p.69
Chapter 5.4 --- Conclusion --- p.72
Chapter 6 --- Summary --- p.74
Bibliography --- p.76
Chapter A --- The Maxwell-Garnett Approximation --- p.80
Chapter B --- The Bergman-Milton Spectral Representation --- p.82
APA, Harvard, Vancouver, ISO, and other styles
You might also be interested in the bibliographies on the topic 'Dielectric Properties' for other source types:
Journal articles Books
We offer discounts on all premium plans for authors whose works are included in thematic literature selections. Contact us to get a unique promo code!

To the bibliography