AC Conductivity of Crystalline Materials and Glasses Ascribed to ADWPs

1995 ◽  
Vol 411 ◽  
Author(s):  
A. S. Nowick ◽  
A. V. Vaysleyb ◽  
H. Jain ◽  
X. Lu
Keyword(s):  
Frequency Dependence ◽  
Low Temperatures ◽  
Composition Dependence ◽  
Minimum Energy ◽  
Alkali Concentration ◽  
Loss Peak ◽  
Broad Distribution ◽  
Crystalline Materials ◽  
High Frequencies ◽  
Nearly Constant Loss

ABSTRACTThe behavior of the frequency dependence of the conductivity, σ(ω), of numerous crystalline materials and glasses is close to an ω1.0 dependence in the limit of low temperatures and/or high frequencies (referred to as the “nearly constant loss”, or NCL, regime). Detailed analysis of this behavior, including the frequency dependence of both ε′ and ε″, shows that it can be described phenomenologically as produced by a broad distribution of asymmetric double-well potentials (ADWPs) with low activation energies. In order to obtain an understanding of the atomic origins of such potentials, we investigate the composition dependence of this behavior in such materials as crystalline CeO2:1%Y3+ ceramics with variable [Y3+] and alkali germanate glasses with variable alkali concentration. The appearance of a discrete loss peak in CeO2: 1%Y3+ helps us understand the ADWPs as due to “off-symmetry” configurations that undergo wiggling motion between adjacent minimum-energy positions.

scholarly journals EXTENSION OF THE FREQUENCY-RANGE OF INTERFEROMETERS FOR THE "MAGNETIC" COMPONENTS OF GRAVITATIONAL WAVES?

2007 ◽  
Vol 22 (13) ◽  
pp. 2361-2381 ◽  
Author(s):  
CHRISTIAN CORDA
Keyword(s):  
Data Analysis ◽  
Frequency Dependence ◽  
Gravitational Waves ◽  
Response Functions ◽  
Frequency Range ◽  
Total Response ◽  
High Frequencies ◽  
Magnetic Components ◽  
Linear Dimensions ◽  
Dominant Part

Recently, with an enlightening treatment, Baskaran and Grishchuk have shown the presence and importance of the so-called "magnetic" components of gravitational waves (GW's), which have to be taken into account in the context of the total response functions of interferometers for GW's propagating from arbitrary directions. In this paper the analysis of the response functions for the magnetic components is generalized in its full frequency dependence, while in the work of Baskaran and Grishchuk the response functions were computed only in the approximation of wavelength much larger than the linear dimensions of the interferometer. It is also shown that the response functions to the magnetic components grow at high frequencies, differently from the values of the response functions to the well-known ordinary components that decrease at high frequencies. Thus the magnetic components could in principle become the dominant part of the signal at high frequencies. This is important for a potential detection of the signal at high frequencies and confirms that the magnetic contributions must be taken into account in the data analysis. More, the fact that the response functions of the magnetic components grow at high frequencies shows that, in principle, the frequency-range of Earth-based interferometers could extend to frequencies over 10000 Hz.

scholarly journals Processes of hypernuclei formation in relativistic ion collisions

2018 ◽  
Vol 171 ◽  
pp. 13001
Author(s):  
Alexander Botvina ◽  
Marcus Bleicher
Keyword(s):  
Experimental Research ◽  
Statistical Models ◽  
Low Temperatures ◽  
Particle Physics ◽  
Broad Distribution ◽  
High Energies ◽  
Intermediate Energies ◽  
Ion Collisions ◽  
High And Low Temperatures

The study of hypernuclei in relativistic ion collisions open new opportunities for nuclear and particle physics. The main processes leading to the production of hypernuclei in these reactions are the disintegration of large excited hyper-residues (target- and projectile-like), and the coalescence of hyperons with other baryons into light clusters. We use the transport, coalescence and statistical models to describe the whole reaction, and demonstrate the effectiveness of this approach: These reactions lead to the abundant production of multi-strange nuclei and new hypernuclear states. A broad distribution of predicted hypernuclei in masses and isospin allows for investigating properties of exotic hypernuclei, as well as the hypermatter both at high and low temperatures. There is a saturation of the hypernuclei production at high energies, therefore, the optimal way to pursue this experimental research is to use the accelerator facilities of intermediate energies, like FAIR (Darmstadt) and NICA (Dubna).

Electro-rheological effect of blends composed of two liquid crystalline materials: composition dependence

2010 ◽  
Vol 37 (5) ◽  
pp. 599-605 ◽  
Author(s):  
Kosuke Kaneko ◽  
Atsuhiko Mandai ◽  
Yuichi Kamei ◽  
Yusuke Miwa ◽  
Naotake Nakamura
Keyword(s):  
Liquid Crystalline ◽  
Composition Dependence ◽  
Crystalline Materials ◽  
Liquid Crystalline Materials ◽  
Rheological Effect

scholarly journals Experimental study of microwave properties of composites filled with Permalloy powder

2018 ◽  
Vol 185 ◽  
pp. 02002
Author(s):  
Stanislav Y. Bobrovskii ◽  
Victor A. Garanov ◽  
Andrei S. Naboko ◽  
Alexei V. Osipov ◽  
Konstantin N. Rozanov
Keyword(s):  
Ferromagnetic Resonance ◽  
Skin Effect ◽  
Magnetic Loss ◽  
Spherical Particles ◽  
Loss Peak ◽  
Low Frequencies ◽  
High Frequencies ◽  
Permittivity And Permeability ◽  
Powder Particles ◽  
Shape Data

Frequency dependencies of permittivity and permeability of composites filled with Permalloy powder with various concentrations and shapes of particles have been measured and discussed. The powder particles of various shapes were obtained by mechanical milling of industrial Permalloy powder in organic media. Paraffin wax was used as a matrix for producing the composites. A shape data of the particles was obtained with an electron microscope. The permittivity and permeability were measured in the frequency range of 0.13 to 10 GHz. The shape of the particles changes from sphere to platelet with increase of milling time. The change leads to a shift of the ferromagnetic resonance (FMR) frequency and magnetic loss peak. It is shown that for larger particles, a decrease of the Q-factor of the ferromagnetic resonance is observed, which is explained by the strong influence of the skin effect. With increase of the concentration of the Permalloy particles in composite, the magnetic loss peak shifts to low frequencies. When the spherical particles are flattened, the resonance frequency shifts to high frequencies, which indicates that the shift to high frequencies due to the decrease of the skin effect and the change in the magnetic structure is stronger than the shift to the low frequencies by changing the shape and reducing the demagnetization.

scholarly journals A Frequency-Dependent Model for the Shape of the Fourier Amplitude Spectrum of Acceleration at High Frequencies

2020 ◽  
Vol 110 (6) ◽  
pp. 2743-2754 ◽  
Author(s):  
Annabel Haendel ◽  
John G. Anderson ◽  
Marco Pilz ◽  
Fabrice Cotton
Keyword(s):  
Frequency Dependence ◽  
Amplitude Spectrum ◽  
Frequency Interval ◽  
Borehole Data ◽  
High Frequencies ◽  
Dependent Model ◽  
Fourier Amplitude Spectrum ◽  
Log Linear ◽  
Frequency Dependent Model ◽  
Quality Factor Q

ABSTRACT The high-frequency decay term of the acceleration spectrum κ is a commonly used parameter in engineering seismology. In recent years, the assumption of a linearly decaying spectrum in log–linear space has been recognized to not always be valid as the value of κ depends on the analyzed frequency band. We present an alternative model for the spectral falloff in which the frequency dependence is explicitly taken into account. This is motivated by observations that the quality factor Q has a power-law dependence on frequency at high frequencies. The new model describes the spectral decay with the help of two variables, opposite to the single parameter κ. The approach is applied to borehole data of the EUROSEISTEST site in Greece. The misfit between modeled and observed spectra is reduced with the new approach compared with the classical kappa model. The new estimates compare well with κ estimates if the same frequency interval is considered but additionally allows for the capture of the frequency dependence of the spectral shape.

The anomalous skin effect

1952 ◽  
Vol 215 (1123) ◽  
pp. 481-497 ◽  
Keyword(s):  
Free Path ◽  
Low Temperatures ◽  
Skin Effect ◽  
Mean Free Path ◽  
Skin Depth ◽  
Surface Conductance ◽  
High Frequencies ◽  
Surface Imperfections ◽  
Anomalous Skin Effect ◽  
Cadmium Lead

The anomalous skin effect arises in good conductors at low temperatures and high frequencies when the electronic mean free path becomes comparable with or greater than the classically calculated skin depth. Measurements have been made on a number of metals at frequencies of 1200 and 3600 Mc/s, and the form of variation of r. f. surface conductance with d. c. conductivity agrees well with that predicted theoretically by Reuter & Sondheimer, assuming that the electrons are scattered diffusely when they hit the surface of the metal. From the results, estimates are made of the effective value of σ/ l , the ratio of d. c. conductivity to mean free path, and hence of the free surface area of the occupied region of k -space. The estimate for copper agrees well with that expected theoretically; those for silver and gold are rather lower than the theoretical values. For the other metals investigated, tin, cadmium, lead and aluminium, no theoretical estimates are available. The results are very sensitive to the presence of surface imperfections; the effect of these is discussed.

EFFECTS OF ELECTRODE RESISTANCE ON THE DIELECTRIC BEHAVIORS OF Au/BaxSr1−xTiO3/La1.1Sr0.9NiO4 CAPACITORS

2016 ◽  
Vol 23 (04) ◽  
pp. 1650028
Author(s):  
JIE QIU ◽  
GUOZHEN LIU ◽  
JÉRÔME WOLFMAN
Keyword(s):  
Frequency Dependence ◽  
High Frequency ◽  
Electronic Devices ◽  
Equivalent Circuit Model ◽  
Simulation Studies ◽  
Oxide Electrode ◽  
Theoretical Simulation ◽  
High Frequencies ◽  
Electrode Resistance ◽  
Apparent Deviation

BaxSr[Formula: see text]TiO3 ([Formula: see text]) (BST) thin films were prepared on La[Formula: see text]Sr[Formula: see text]NiO4 (LSNO)/SrTiO3 (STO) structure by combinatorial pulsed laser deposition (comb-PLD). The capacitances of the Au/BST/LSNO capacitors exhibited strong frequency dependence especially when the applied frequency was higher than 10[Formula: see text]kHz. On the basis of an equivalent circuit model, we presented a theoretical simulation of the relationships between capacitance and frequency for the capacitors with different electrode serial resistances. Based on the fitting results, the observed strong frequency dependence of the measured capacitance at high frequency in our study could be ascribed to the large serial resistance of 750 [Formula: see text] for oxide electrode LSNO. Further simulation studies found that large serial resistance (1000 [Formula: see text]) could result in an apparent deviation from the intrinsic dielectric properties especially at high frequencies ([Formula: see text]100[Formula: see text]kHz) for capacitors with capacitances above 1[Formula: see text]nF. Our results provide useful information for the design of all-oxide electronic devices.

Study of the Location of Implanted Fluorine Atoms in Silicon and Germanium through Their Nuclear Quadrupole Interactions

1996 ◽  
Vol 51 (5-6) ◽  
pp. 560-564 ◽  
Author(s):  
Stacie S. Nunes ◽  
S. Sulaiman ◽  
N. Sahoo ◽  
T. P. Das ◽  
M. Frank ◽  
...  
Keyword(s):  
Minimum Energy ◽  
Wave Functions ◽  
Dangling Bonds ◽  
Hyperfine Parameters ◽  
Frequency Signal ◽  
Crystalline Materials ◽  
Hartree Fock ◽  
Surface Sites ◽  
Nuclear Quadrupole ◽  
Silicon And Germanium

Abstract Time Differential Perturbed Angular Distribution (TDPAD) measurements of the nuclear quadrupole hyperfine parameters for 19F* implanted into amorphous, polycrystalline and crystalline silicon and germanium are reported and reviewed. Two signals are observed in the crystalline materials (≈ 35 and 23 MHz in silicon, ≈ 33 and 27 MHz in germanium) while only one is detected in the amorphous and polycrystalline samples (≈ 22 MHz in silicon, ≈ 27 in germanium). Impurity sites in these materials were modeled using a Hartree-Fock cluster procedure. The Intrabond, Antibond, and Substitutional sites in the bulk were studied in both silicon and germanium. The ATOP and Intrabond Surface sites were also studied in silicon and the results extended to germa-nium. Lattice relaxation effects were incorporated by employing a geometry optimization method to obtain minimum energy configurations for the clusters modelling each site. The electronic wave functions were obtained for each optimized cluster by applying Unresctricted Hartree-Fock theory, and these wave functions were used to calculate the nuclear quadrupole hyperfine parameters at the site of the fluorine nucleus. Comparison of the theoretical hyperfine parameters to the experimental values indicates that 19F* located in the Intrabond and Intrabond surface sites could readily explain the higher frequency signal that has been observed. 19F* in the Antibond and the surface ATOP sites yield hyperfine parameters consistent with the low frequency signal observed in the crystalline materials and the single signal observed in the amorphous (or polycrystalline) materials. Examina-tion of these two sites, in view of other available experimental evidence including the temperature dependence of the TDPAD signals, leads to the conclusion that the lower frequency signal is due to 19F* implants which have come to rest at the site of dangling bonds in the bulk. These dangling bonds are created as a result of damage generated in the individual collision cascades during the implantation process.

Frequency Dependence of Resistivity of High-Purity Copper at Low Temperatures

1993 ◽  
Vol 32 (Part 1, No. 7) ◽  
pp. 3199-3203 ◽  
Author(s):  
Hiroshi Nakane ◽  
Tsuneo Watanabe ◽  
Mineo Kobayashi ◽  
Takasu Hashimoto
Keyword(s):  
Frequency Dependence ◽  
High Purity ◽  
Low Temperatures ◽  
Purity Copper
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