Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 36 for “"dielectric response"”.
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Angle resolved dielectric response in carbon nanotubes
The thesis "Anlre resolved dielectric response in carbon nanotubes" is dedicated to expounding the the anisotropy in the fundamental dielectric response of carbon nanotubes. While nanotubes are along their axis essentially planar graphene, the rolled up topology gives rise to entirely new …
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Low-temperature dielectric response of beta-alumina at 16 GHz
Microwave techniques are used to measure the dielectric response of M$\sp+$ beta alumina at 16 GHz for temperatures between 0.3 and 20K. (M$\sp+$ refers to the monovalent cations Na, K, Ag, or Li.) These measurements include cw observations of the absorption and the dispersion, and the recovery of …
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Time-dependent dielectric response of polymer nanoparticulate composites containing rapidly oscillating source terms
… of the homogenized equations for the macroscopic response of time-dependent dielectric composites that contain space charges varying spatially at the length scale of the microstructure and that are subjected to alternating electric fields. The focus is on dielectrics with periodic microstructures …
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Dielectric response and interactions in low-dimensional carbon materials from first principles calculations
Includes bibliographical references (p. 155-162).
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Molecular dynamics investigation of the long wavelength dielectric response of classical dipolar liquids using Bloch function methods
… then applied to the longitudinal and transverse dielectric constants of dipolar fluids subject to static electric fields, both Stockmayer and polarisable dipole fluids. This is used to verify the ratio of the transverse and longitudinal susceptibility being the dielectric constant, in the limit q …
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Identification and Characterization of Shallow Impurity States in Gallium-Arsenide and Indium-Phosphide Using Photothermal Ionization Spectroscopy
A model of far infrared (FIR) dielectric response of shallow impurity states in a semiconductor has been developed and is presented for the specific case of the shallow donor transitions in high purity epitaxial GaAs. The model is quite general, however, and should be applicable with slight …
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Identification and characterization of shallow impurity states in gallium arsenide and indium phosphide using photothermal ionization spectroscopy
A model of far infrared (FIR) dielectric response of shallow impurity states in a semiconductor has been developed and is presented for the specific case of the shallow donor transitions in high purity epitaxial GaAs. The model is quite general, however, and should be applicable with slight …
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Investigating Hydration and Dynamics of Biomolecules in Solutions using High Precision Terahertz Spectroscopy
… the dynamics and structure of water, and as a response, water will form hydration layers around biomolecules. The dynamics of hydration water, as well as hydrated proteins, lead to translation, rotation, and oscillating dipoles that, in turn, give rise to absorption in the …
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Structure-property relationships in strontium barium niobate relaxor ferroelectrics
… x) have been performed using a combination of dielectric spectroscopy, Sawyer-Tower polarization techniques, and transmission electron microscopy (TEM). The dielectric response was found to be strongly dependent on crystallographic orientation, in distinct comparison to the nearly orientation …
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Orientation dependence of dielectric susceptibilities and switching characteristics in epitaxial ferroelectric thin films
… walls play an important role in determining the response of ferroelectrics to applied stimuli. While contributions to ferroelectric properties from the intrinsic response of the polarization within a domain and so-called extrinsic contributions from the motion of domain walls have been studied, …
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Assessment of dielectric models and their application to polymer matrix composites
… spheres embedded in the epoxy matrix on the dielectric behavior of composite was investigated in the 100 Hz to 100 kHz range. It was found that the dielectric constant of epoxy matrix can be reduced by mixing the matrix with hollow ceramic spherical inclusions. To predict the effective …
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Bridging the gap between atomistic and continuum models to predict dielectric and thermodynamic properties of confined fluids
… the structure but also accurately describe the dielectric permittivity and its anisotropic nature in the confinement. Using the CG potentials in EQT we show that neglecting the tensorial form of the dielectric permittivity in the Poisson equation leads to incorrect screening and orientational …
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Empirical Nanotube Model: Applications to Water Channels and Nano -Oscillators
… reveal that a K+ ion induces a strong dielectric response in the nanotube wall, which helps to trap the ion inside the tube and force the ion to oscillate at a terahertz frequency. Such a nano-oscillator may hold potential applications as a room temperature terahertz wave detector.
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Probing Collective Motions and Hydration Dynamics of Biomolecules by a Wide Range Dielectric Spectroscopy
… conformational changes of protein in water. In response, we have developed a highly sensitive megahertz-to-terahertz dielectric spectroscopy system to probe the hydration shells as well as large-scale dynamics of these biomolecules. Thereby, we have deduced the conformation flexibility of …
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Cross linked sulphonated poly (ether ether ketone) for the development of polymer electrolyte membrane fuel cell
… as fuel cell membranes. Analysis of the dielectric response by Cole-Cole, Havrilak and Negami and Williams and Watts equations indicated that the dipole relaxation was broadened and becoming more asymmetric with cross link density. The sulphonation of the cross linked PEEK in concentrated …
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Competing polar and nonpolar distortions and phase transitions in low-dimensional materials
… in such systems due to the coupling of the dielectric response of the film with common structural distortions of the perovskite systems employed, namely the rotations of oxygen octahedra (tilts). We show that continuous or discontinuous, and simultaneous or separate appearances of tilts and …
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Studying Interactions of Gas Molecules with Nanomaterials Loaded in a Microwave Resonant Cavity
… in TE011 mode was used to study the adsorption response of single walled carbon nanotubes (SWCNTs) and other nanomaterials for different types of gas molecules. The range of the frequency signal as a probe was chosen as geometry dependent range between 9.1 -9.8 GHz. A highly specific range can …
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Developing spectroscopic ellipsometry to study II-VI and diluted magnetic semiconductors
… oxide overlayer which distorts the intrinsic dielectric response of the sample, a chemical etching technique using dilute NI40H solution was developed. The successful removal of the oxide overlayer on ZnSe was confirmed via the XPS technique. For diluted magnetic semiconductors (DMS), we found …
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Semi-Empirical Studies on Electronic Properties and Applications of Carbon Nanotubes
… carbon nanotubes. First, we study the transverse dielectric response and discuss its dependence on nanotube geometry, field strength and position of the Fermi level. We find significant modification of the band structure at the strong field limit. Band gap opening/closing is predicted for …
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Molecular simulations of the interaction of microwaves with fluids
… fundamental understanding of the causes of the response of the material, defined by constitutive relations for its complex, frequency-dependent dielectric constant, can only be achieved through the study of processes occurring at the molecular scale. The fluctuation-dissipation theorem relates …
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