Academic literature on the topic 'Bulk electrical conduction'
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Journal articles on the topic "Bulk electrical conduction"
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Semenenko, Bogdan, and Pablo Esquinazi. "Diamagnetism of Bulk Graphite Revised." Magnetochemistry 4, no. 4 (November 22, 2018): 52. http://dx.doi.org/10.3390/magnetochemistry4040052.
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Recently published structural analysis and galvanomagnetic studies of a large number of different bulk and mesoscopic graphite samples of high quality and purity reveal that the common picture assuming graphite samples as a semimetal with a homogeneous carrier density of conduction electrons is misleading. These new studies indicate that the main electrical conduction path occurs within 2D interfaces embedded in semiconducting Bernal and/or rhombohedral stacking regions. This new knowledge incites us to revise experimentally and theoretically the diamagnetism of graphite samples. We found that the c-axis susceptibility of highly pure oriented graphite samples is not really constant, but can vary several tens of percent for bulk samples with thickness t ≳ 30 μ m, whereas by a much larger factor for samples with a smaller thickness. The observed decrease of the susceptibility with sample thickness qualitatively resembles the one reported for the electrical conductivity and indicates that the main part of the c-axis diamagnetic signal is not intrinsic to the ideal graphite structure, but it is due to the highly conducting 2D interfaces. The interpretation of the main diamagnetic signal of graphite agrees with the reported description of its galvanomagnetic properties and provides a hint to understand some magnetic peculiarities of thin graphite samples.
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Chiu, Fu-Chien. "A Review on Conduction Mechanisms in Dielectric Films." Advances in Materials Science and Engineering 2014 (2014): 1–18. http://dx.doi.org/10.1155/2014/578168.
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The conduction mechanisms in dielectric films are crucial to the successful applications of dielectric materials. There are two types of conduction mechanisms in dielectric films, that is, electrode-limited conduction mechanism and bulk-limited conduction mechanism. The electrode-limited conduction mechanism depends on the electrical properties at the electrode-dielectric interface. Based on this type of conduction mechanism, the physical properties of the barrier height at the electrode-dielectric interface and the effective mass of the conduction carriers in dielectric films can be extracted. The bulk-limited conduction mechanism depends on the electrical properties of the dielectric itself. According to the analyses of bulk-limited conduction mechanisms, several important physical parameters in the dielectric films can be obtained, including the trap level, the trap spacing, the trap density, the carrier drift mobility, the dielectric relaxation time, and the density of states in the conduction band. In this paper, the analytical methods of conduction mechanisms in dielectric films are discussed in detail.
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Audoit, Jérémie, Lydia Laffont, Antoine Lonjon, Eric Dantras, and Colette Lacabanne. "Percolative silver nanoplates/PVDF nanocomposites: Bulk and surface electrical conduction." Polymer 78 (November 2015): 104–10. http://dx.doi.org/10.1016/j.polymer.2015.09.062.
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Revesz, A. G., G. A. Brown, and H. L. Hughes. "Bulk Electrical Conduction in the Buried Oxide of SIMOX Structures." Journal of The Electrochemical Society 140, no. 11 (November 1, 1993): 3222–29. http://dx.doi.org/10.1149/1.2221014.
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Mukai, Yusuke, and Minyoung Suh. "Enhancing the electrical properties of inkjet-printed silver ink by electrolyte sintering, photonic sintering, and electroless plating." Science of Sintering 53, no. 1 (2021): 119–26. http://dx.doi.org/10.2298/sos2101119m.
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Conductive inkjet printing is an emerging rapid manufacturing technology in the field of smart clothing and wearable electronics. The current challenge in conductive inkjet printing includes upgrading of electrical performance of printed inks to the equivalent level to traditional conductors such as bulk silver and copper, especially for high-performance electronic applications such as flexible antennas and circuits. Post-treatments are commonly employed to enhance the electrical conduction of inkjet-printed tracks. This research discusses the effects of electrolyte sintering, photonic sintering and electroless copper plating on the DC electrical resistance and resistivity of inkjet-printed silver nanoparticles. From experimental results and measurements, it was found that all the post-treatment methods effectively improved the electrical properties of printed silver ink, but in different ways. The lowest resistance of 4.5 ? (in 0.1 mm ? 10 mm) and thickest (4.5 ?m) conductor were achieved by electroless copper plating, whereas the lowest resistivity (7.5?10-8 ??m) and thinnest (1.0 ?m) conductor were obtained by photonic sintering.
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Hwang, Cheol Seong. "Bulk- or interface-limited electrical conductions in IrO2/(Ba,Sr)TiO3/IrO2 thin film capacitors." Journal of Materials Research 16, no. 12 (December 2001): 3476–84. http://dx.doi.org/10.1557/jmr.2001.0478.
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The electrical conduction behavior of sputter-grown (Ba,Sr)TiO3 thin films having IrO2 electrodes were studied under the assumption of a fully accumulated film having a negative space charge density of 1 × 1019 cm−3 at 25 °C. The negative space charge decreased the actual field strength in the film and resulted in a decreasing leakage current with increasing film thickness at a given applied field. The current conduction in a very low field, roughly less than 150 KV/cm, showed a linear current density–voltage (J–V) behavior at 25 °C. From that field to about 420 KV/cm, the bulk-limited Poole–Frenkel mechanism controlled the overall conduction property at room temperature. Under high field strength, from 420 KV/cm to 1 MV/cm, the interface-limited thermionic field emission mechanism was dominant. The dielectric constant obtained from Poole–Frenkel fitting was approximately 300 ± 50 at 25 °C, which was in qualitative agreement with the value obtained from low-frequency capacitance measurements. The detailed mechanisms of the linear and nonlinear field-dependent emission conductions were discussed with reference to the direction of band bending, not to the carrier concentration.
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Chaudhry, Anurag, and M. Saif Islam. "Examining the Anomalous Electrical Characteristics Observed in InN Nanowires." Journal of Nanoscience and Nanotechnology 8, no. 1 (January 1, 2008): 222–27. http://dx.doi.org/10.1166/jnn.2008.n18.
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Research interest in InN has intensified in recent years because of its unique material properties and promising applications in electronic and photonic devices. Measurements on InN nanowires presented by Chang et al., [J. Electron. Mater. 35, 738 (2006)] showed an anomalous resistance behavior in InN nanowires with diameters less than 90 nm. We examine possible theories presented in literature to explain this intriguing observation. We propose that the presence of a high density electron accumulation layer at the surface of thin InN nanowires is the most probable cause for the uncharacteristic relationship between the total measured resistance and the ratio of length-to-area. High density surface electron accumulation layer, characteristic of InN films and nanowire, promotes a surface conduction path distinct from the bulk conduction. For large diameter nanowires, bulk conduction is likely to be the dominant mechanism while surface conduction is proposed to play a major role for small diameter InN nanowires.
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Patel, Satyanarayan, and Harekrishna Yadav. "Electrical conduction properties of the BZT–BST ceramics." Journal of Advanced Dielectrics 10, no. 06 (December 2020): 2050026. http://dx.doi.org/10.1142/s2010135x20500265.
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0.5Ba([Formula: see text][Formula: see text]O3-0.5([Formula: see text][Formula: see text]TiO3 (BZT–BST) has been explored in recent times for potential applications in energy harvesting, electrocaloric and energy storage. To this end, energy harvesting/conversion and storage applications require an understanding of the conduction and loss mechanisms. The conduction mechanism in BZT–BST ceramics is studied using impedance spectroscopy (IS) at 0.1 Hz−3 MHz and 100−600[Formula: see text]C. Impedance study reveals the presence of two types of relaxation processes due to grain and grain boundary contributions. The relaxation time and dc conductivity activation energies are obtained as 1.12/1.3 eV and 1.05/1.2eV for bulk/grain boundary, respectively, and found that oxygen vacancies dominated electrical behavior. The relaxation mechanism follows non-Debye-type behavior. The high resistance of the grain (bulk) in the ferroelectric region does not contribute to the high losses; the losses probably result from the phase transition. Also, BZT–BST ceramics exhibit a negative temperature coefficient of resistance (NTCR) behaviour. From a practical application point of view in the temperature regime of 25–65[Formula: see text]C, the loss’s contribution is low. The significant contributions of loss result from the response of phase-transition in this temperature range (25–65[Formula: see text]C).
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Triyono, D., S. N. Fitria, and U. Hanifah. "Dielectric analysis and electrical conduction mechanism of La1−xBixFeO3 ceramics." RSC Advances 10, no. 31 (2020): 18323–38. http://dx.doi.org/10.1039/d0ra02402c.
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Sharma, Pankaj, Fei-Xiang Xiang, Ding-Fu Shao, Dawei Zhang, Evgeny Y. Tsymbal, Alex R. Hamilton, and Jan Seidel. "A room-temperature ferroelectric semimetal." Science Advances 5, no. 7 (July 2019): eaax5080. http://dx.doi.org/10.1126/sciadv.aax5080.
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Coexistence of reversible polar distortions and metallicity leading to a ferroelectric metal, first suggested by Anderson and Blount in 1965, has so far remained elusive. Electrically switchable intrinsic electric polarization, together with the direct observation of ferroelectric domains, has not yet been realized in a bulk crystalline metal, although incomplete screening by mobile conduction charges should, in principle, be possible. Here, we provide evidence that native metallicity and ferroelectricity coexist in bulk crystalline van der Waals WTe2by means of electrical transport, nanoscale piezoresponse measurements, and first-principles calculations. We show that, despite being a Weyl semimetal, WTe2has switchable spontaneous polarization and a natural ferroelectric domain structure at room temperature. This new class of materials has tantalizing potential for functional nanoelectronics applications.
Dissertations / Theses on the topic "Bulk electrical conduction"
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Mutta, Geeta Rani. "Propriétés structurales, optiques et électroniques des couches d’InN et hétérostructures riches en indium pour applications optoélectroniques." Caen, 2012. http://www.theses.fr/2012CAEN2013.
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Les semi-conducteurs nitrures (AlN, GaN, InN) focalisent une activité de recherche intense en raison de nombreuses applications comme les diodes électroluminescentes, les composants de puissance ou hyperfréquence. Dans cette recherche, nous avons abordé le travail sous deux angles: a) la conduction électrique dans les couches d'InN produites par croissance épitaxiale aux jets moléculaires assistée par plasma (PAMBE) et une recherche sur l'origine de la forte émission bleue dans les puits de quantiques d'InGaN/GaN. L'accumulation d'électron en surface dans les couches d'InN constitue une limitation importante pour la fabrication de composants. Au cours de ce travail, nous avons exploré l'utilisation des mesures de bruit de basse fréquence sur les couches d'InN et pu accéder à leur conductivité électrique en volume. L'étude des puits quantiques d'InGaN/GaN, obtenue par croissance épitaxiale aux jets moléculaires (MBE) ou épitaxie en phase vapeurs aux organométalliques (MOVPE) , a été effectuée par analyses de la microstructure par microscopie électronique en transmission (MET, HRTEM et STEM) en corrélation avec les propriétés optiques d'un grand nombre d'échantillons provenant de conditions de croissance différentes. Ce travail nous a permis d'acquérir une vision plus critique du rôle des conditions de fabrication et des paramètres comme la morphologie, les fluctuations de composition et la présence des défauts en V sur les explications actuellement avancées pour la forte efficacité d'émission dans les puits quantiques d' InGaN/GaNThe nitride semiconductors (AlN, GaN, InN) are subject to a large research effort due to their numerous applications, such as light emitting diodes, high power and high frequency components. Following the trend, the aim of this dissertation has been twofold: first, we have probed the bulk electrical conduction in InN layers, second, we investigated the origin of the high emission efficiency in InGaN/GaN Quantum Wells (QWs). The surface electron accumulation in InN layers is still an important limitation to device applications. W have explored this point using low frequency noise measurements on Plasma Assisted Molecular Beam Epitaxy (PAMBE) InN layers and we demonstrated that the bulk electrical conductivity of InN can be accessed. The investigation of quantum wells produced by molecular beam epitaxy (MBE) or matalorganic vapour phase epitaxy (MOVPE), has been carried out through microstructural analyses by transmission electron microscopy techniques(TEM, HRTEM, STEM) in correlation with optica properties on a large number of samples grown in different growth conditions. This experimental work has allowed us to obtain a critical view on the role of the growth conditions and such parameters as the well morphology, composition fluctuations, as well as the V shaped defects on the current explanations of high emission efficiency in InGaN/GaN QWs
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Neuhold, Stephan Michael. "A hyper elastic conductor for bulk energy transfer in the wall of spoolable tubes for electric deep drilling /." Zürich : ETH, 2007. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=17358.
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"Analytical Modeling and Development of GaN-Based Point of Load Buck Converter with Optimized Reverse Conduction Loss." Master's thesis, 2020. http://hdl.handle.net/2286/R.I.62792.
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abstract: This work analyzes and develops a point-of-load (PoL) synchronous buck converter using enhancement-mode Gallium Nitride (e-GaN), with emphasis on optimizing reverse conduction loss by using a well-known technique of placing an anti-parallel Schottky diode across the synchronous power device. This work develops an improved analytical switching model for the GaN-based converter with the Schottky diode using piecewise linear approximations.
To avoid a shoot-through between the power switches of the buck converter, a small dead-time is inserted between gate drive switching transitions. Despite optimum dead-time management for a power converter, optimum dead-times vary for different load conditions. These variations become considerably large for PoL applications, which demand high output current with low output voltages. At high switching frequencies, these variations translate into losses that contribute significantly to the total loss of the converter. To understand and quantify power loss in a hard-switching buck converter that uses a GaN power device in parallel with a Schottky diode, piecewise transitions are used to develop an analytical switching model that quantifies the contribution of reverse conduction loss of GaN during dead-time.
The effects of parasitic elements on the dynamics of the switching converter are investigated during one switching cycle of the converter. A designed prototype of a buck converter is correlated to the predicted model to determine the accuracy of the model. This comparison is presented using simulations and measurements at 400 kHz and 2 MHz converter switching speeds for load (1A) condition and fixed dead-time values. Furthermore, performance of the buck converter with and without the Schottky diode is also measured and compared to demonstrate and quantify the enhanced performance when using an anti-parallel diode. The developed power converter achieves peak efficiencies of 91.7% and 93.86% for 2 MHz and 400 KHz switching frequencies, respectively, and drives load currents up to 6A for a voltage conversion from 12V input to 3.3V output.
In addition, various industry Schottky diodes have been categorized based on their packaging and electrical characteristics and the developed analytical model provides analytical expressions relating the diode characteristics to power stage performance parameters. The performance of these diodes has been characterized for different buck converter voltage step-down ratios that are typically used in industry applications and different switching frequencies ranging from 400 KHz to 2 MHz.Dissertation/Thesis
Masters Thesis Electrical Engineering 2020
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Kassier, Gunter Horst. "The characterization of bulk as-grown and annealed ZnO by the Hall effect." Diss., 2007. http://hdl.handle.net/2263/26646.
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A fully automated Temperature Dependent Hall (TDH) measurement setup has been assembled for the purposes of this study. This TDH setup is capable of measuring samples in the 20 K to 370 K temperature range. Sample sizes of up to 20 mm × 20 mm can be accommodated by the custom designed and manufactured sample holder. Samples with a resistance in the 1Ω to 250 MΩ range can be measured with this setup provided that the mobility of the sample is greater than 1 cm²/Vs. The computer program controlling the automated measurement processwas written in LabView™ version 6.1. Single crystal Zinc Oxide (ZnO) was the material under investigation in this study. Bulk ZnO samples grown by three different methods, namely pressurized melt growth, seeded chemical vapor transport (SCVT) growth and hydrothermal growth, were measured in the 20 K to 370 K range. The effect of annealing in argon atmosphere in the 550 ºC to 930 ºC range was investigated on all three ZnO types. In addition, hydrogen-implanted layers on semi-insulating hydrothermally grown ZnO were studied. These samples were annealed in the 200 ºC to 400 ºC range and Hall measurements in the 20 K to 330 K range were performed. Programs were written to fit, wherever possible, the obtained temperature dependent carrier concentration and mobility profiles to suitable theoretical models. The carrier concentration data was fitted to a multi-donor single acceptor charge balance equation for the purpose of extracting donor concentrations and activation energies. Before fitting, the data was corrected for the Hall scattering factor and, where necessary, for two-layer effects particularly a degenerate surface conduction channel that developed through annealing on the SCVT-grown and hydrothermally grown samples. The acceptor concentrations of the samples were obtained by fitting the mobility data to a model based on D.L. Rode’s method of solving the Boltzmann transport equation. Scattering mechanisms included in the model were piezoelectric and deformation potential acoustic modes, polar optic modes and ionized impurity scattering. It was found that the mobility data did not fit the model very well without assigning questionable values to other parameters, in this case the deformation potential. Plausible values for the acceptor concentration were however obtained. The carrier concentration data fitted the model well, but due to the large number of parameters to be extracted (up to six parameters in the case of three donors) there was often not much certainty in the extracted values This study shows that TDH analysis is a valuable tool to assess the quality of semiconductors. Bulk and degenerate surface (or interfacial) conduction are separated with relative ease, and shallow defect concentrations as well as compensation level concentrations could be extracted. The generally observed uncertainty in values obtained in the multi-parameter regression of carrier concentration data indicates that supplementary techniques such as photoluminescence are needed to support results obtained by the TDH technique.Dissertation (MSc (Physics))--University of Pretoria, 2007.
Physics
MSc
unrestricted
Books on the topic "Bulk electrical conduction"
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Saitoh, E. Topological spin current. Oxford University Press, 2017. http://dx.doi.org/10.1093/oso/9780198787075.003.0004.
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This chapter discusses another type of equilibrium-spin current similar to the exchange-spin current—the topological spin current. Topological spin currents are driven by topological-band structure and classified into bulk and surface topological spin currents. The former is confined onto electron-band manifolds, sometimes affecting their motions. This confinement is addressed through the standard method of combining the equations of motion and the Boltzmann equation for semi-classical electrons in a band. The latter class, on the other hand, is a surface-spin current, which is limited near surfaces of a three-dimensional system and flows along these surfaces. This type is known to appear in topological insulators, where the bulk is insulating but the surface or edge is electrically conducting due to the surface or edge state.
Book chapters on the topic "Bulk electrical conduction"
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Liu, Qing, Xiaobo Wu, and Liang Yin. "Fixed-Frequency Quasi-Sliding Mode Controller for Single-Inductor-Dual-Output Buck Converter in Pseudo-Continuous Conduction Mode." In Lecture Notes in Electrical Engineering, 697–704. Berlin, Heidelberg: Springer Berlin Heidelberg, 2011. http://dx.doi.org/10.1007/978-3-642-21747-0_89.
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Borage, Manthan Mangesh, Dipen M. Vachhani, and Rajesh Arya. "Design and Implementation of Feedback Controller for Nonisolated Switching DC-DC Buck Converter Operating in Continuous Current Conduction Mode." In Lecture Notes in Electrical Engineering, 263–76. Singapore: Springer Singapore, 2020. http://dx.doi.org/10.1007/978-981-15-7245-6_21.
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"PANI Thin Films for Solar Cells." In Advances in Chemical and Materials Engineering, 195–215. IGI Global, 2020. http://dx.doi.org/10.4018/978-1-5225-9896-1.ch007.
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After the breakthrough of conducting polymers, an incredible interest has been paid to integrate them in electronic component fabrication as an alternative to metals. Polyaniline is the most extensively studied material due to the ease of synthesis, better environmental stability, and enormous scope to modify its properties for solar cell applications. The electrical conductivity of PANI can be altered according to the need for the application where electronic devices made of conducting polymer composites are significantly dependent on the dielectric properties of the materials. Therefore, this chapter has been dedicated to the low-frequency AC conduction and dielectric studies of conducting PANI followed by having PANI thin films as efficient donor or acceptor bulk heterojunction layer to the hybrid solar cells.
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Enoki, Toshiaki, Morinobu Endo, and Masatsugu Suzuki. "Highly Conductive Graphite Fibers." In Graphite Intercalation Compounds and Applications. Oxford University Press, 2003. http://dx.doi.org/10.1093/oso/9780195128277.003.0012.
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From the viewpoint of applications of GICs, a very interesting development is the enhancement in conductivity of the host graphite up to the range of metals, especially for pristine materials with fibrous forms. Much attention has been paid to the exploitation of the order of magnitude intercalation-induced enhancement of the electrical conductivity of graphite fibers for the fabrication of practical high-conductivity, lightweight conductors (Vogel et al., 1977; Goldberg and Kalnim, 1981; Manini et al., 1983, 1985; Murday et al., 1984; Meschi et al., 1986; Natarajan and Woollam, 1983; Natarajan et al., 1983a). The fiber geometry (large aspect length/diameter) ratio offers advantages relative to highly oriented pyrolytic graphite (HOPG) or bulk graphite for the measurement of several of the transport properties of GICs and for increasing the compositional stability of GICs both under ambient conditions and at elevated temperatures (Endo et al., 1981, 1983a). For bulk GICs, intercalation increases the density of carriers by the injection of electrons into the graphite planes in the case of donor guest species, and by injection of holes in the case of acceptor type (see Chapters 5 and 6). The intercalation-induced decrease in carrier mobility that results from the increased scattering by defects and the increased effective mass is outweighed by the larger increase in carrier density, resulting in a large conductivity enhancement as discussed in Section 6.1. The carriers are localized in the graphene planes, and for high-stage compounds (n ≥ 2) the carrier density falls off rapidly with distance from the graphite bounding layer owing to the screening of the charged intercalate layer by the surrounding graphite bounding layers. From an application standpoint, many of the applications of intercalated carbon fibers exploit the high specific conductivity of GICs, which can be expressed as a figure of merit in terms of the conductivity σ divided by the mass density ρm; for a good conductor like copper this is ~ 6 x 10−2 cm /gμΩ. For example, intercalated carbon fibers can provide a lightweight conductor for huge aircraft or motor vehicles, in which, respectively, about 1.5 tonne or 30 kg conventional metallic conductor is used.
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Rojac, Tadej. "Piezoelectric Nonlinearity and Hysteresis Arising from Dynamics of Electrically Conducting Domain Walls." In Hysteresis in Engineering [Working Title]. IntechOpen, 2021. http://dx.doi.org/10.5772/intechopen.98721.
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Macroscopic nonlinearity and hysteresis observed in the piezoelectric and dielectric responses of ferroelectric materials to external stimuli are commonly attributed to localized displacements of domain walls (DWs). The link between the macroscopic response and microscopic DW dynamics is provided by the well-known Rayleigh relations, extensively used to quantify the electrical and electromechanical behavior of ferroelectric ceramics and thin films under subswitching conditions. In this chapter, I will present an intriguing case where DWs exhibit enhanced electrical conductivity with respect to the bulk conductivity. By combining experimental data and modeling, it will be shown that the local conductivity, related to accumulation of charged points defect at DWs, does not only affect DW dynamics through DW-defect pinning interactions, as we may expect, but goes beyond it by affecting the macroscopic nonlinearity and hysteresis in a more complex manner. The major characteristics and implications of the underlying nonlinear Maxwell-Wagner piezoelectric relaxation, triggered by the presence and dynamics of conducting DWs, will be presented, reviewed and discussed in the framework of systematic multiscale analyses on BiFeO3 ceramics. The result may have implications in the development of promising BiFeO3-based compositions for high-temperature piezoelectric applications.
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Souier, Tewfik. "Conductive Probe Microscopy Investigation of Electrical and Charge Transport in Advanced Carbon Nanotubes and Nanofibers-Polymer Nanocomposites." In Handbook of Research on Nanoscience, Nanotechnology, and Advanced Materials, 343–75. IGI Global, 2014. http://dx.doi.org/10.4018/978-1-4666-5824-0.ch014.
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In this chapter, the main scanning probe microscopy-based methods to measure the transport properties in advanced polymer-Carbon Nanotubes (CNT) nanocomposites are presented. The two major approaches to investigate the electrical and charge transport (i.e., Electrostatic Force Microscopy [EFM] and Current-Sensing Atomic Force Microscopy [CS-AFM]) are illustrated, starting from their basic principles. First, the authors show how the EFM-related techniques can be used to provide, at high spatial resolution, a three-dimensional representation CNT networks underneath the surface. This allows the studying of the role of nanoscopic features such as CNTs, CNT-CNT direct contact, and polymer-CNT junctions in determining the overall composite properties. Complementary, CS-AFM can bring insight into the transport mechanism by imaging the spatial distribution of currents percolation paths within the nanocomposite. Finally, the authors show how the CS-AFM can be used to quantify the surface/bulk percolation probability and the nanoscopic electrical conductivity, which allows one to predict the macroscopic percolation model.
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Surya, Sumukh. "Mathematical Modeling of DC-DC Converters and Li Ion Battery Using MATLAB/Simulink." In Electric Vehicles and the Future of Energy Efficient Transportation, 104–43. IGI Global, 2021. http://dx.doi.org/10.4018/978-1-7998-7626-7.ch005.
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In the present work, three different methods for obtaining the DC response for modeling practical DC-DC buck and boost converters operating in continuous conduction mode (CCM) are demonstrated using MATLAB/Simulink. The method of selection for inductor, diode, and MOSFET for a DC-DC converter is discussed in detail. The governing equations for the non-ideal converters were derived using volt-sec and amp-sec balance equations. Mathematical modeling of basic converters was carried out using ‘commonly used blocks' reducing the dependence on SimPower System tool box in Simulink. The non-ideal parameters in the converter caused a drastic variation in the duty cycle and output voltage which in turn had an adverse effect on the efficiency. The transients in output voltages and inductor currents were observed. In addition, a Li ion polymer battery was mathematically modeled. Accurate battery modeling for pulse charging was proposed. A comparative analysis of 1, 2, …, 5 RC pair/s modeling of the battery was presented.
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Doveton, John H. "Porosity Volumetrics and Pore Typing." In Principles of Mathematical Petrophysics. Oxford University Press, 2014. http://dx.doi.org/10.1093/oso/9780199978045.003.0007.
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The primary objective of porosity estimations based on measurements made either from petrophysical logs or core is the volume of pore space within the rock, given simply by the equation: . . . Φ = Vp/Vb . . . The Greek letter, phi, is the standard symbol for porosity and is expressed in this equation as the ratio of the volume of void space (Vp) to the bulk volume of the rock (Vb). The simplest concepts of porosity are generally explained in terms of the packing of spheres as the sum of the pore volume of the space between the spheres. There are five basic arrangements of uniform-sized spheres that can be constructed: simple cubic, orthorhombic, double-nested, face-centered cubic, and rhombohedral packing (Hook, 2003). Each has a geometrically defined pore volume that represents an upper limit for granular rocks whose constituent grains have a variety of sizes and shapes and whose pore volumes have been reduced by compaction and diagenetic cements. This intergranular model is a useful starting point for the characterization of pores in clastic rocks and will be considered first, before reviewing the additional complexities of pore geometry introduced by dissolution in carbonate rocks. The solid framework of a sandstone consists of a nonconductive “matrix” dominated by quartz, but commonly with accessory nonconductive minerals, and conductive clay minerals, whose electrical properties are caused by cation exchange with ions in saline formation water. It is important to distinguish between connected and unconnected pores, as well as larger pores that sustain fluid movement in contrast to smaller pores filled with capillary-bound water. A graphic presentation of these components is widely used in the petrophysical literature as a reference basis to disentangle terminology that can be confusing and contradictory. In particular, the term “effective porosity” has different meanings that vary from one technical discipline to another. In their review of porosity terms, Wu and Berg (2003) concluded that many core analysts considered all porosity to be effective, log analysts excluded clay-bound water, while petroleum engineers excluded both clay-bound and capillary-bound from porosity consideration, thereby restricting effective porosity to pores occupied by mobile fluids.
Conference papers on the topic "Bulk electrical conduction"
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Miyazaki, Koji. "Heat Conduction of a Porous Material." In ASME 2009 Second International Conference on Micro/Nanoscale Heat and Mass Transfer. ASMEDC, 2009. http://dx.doi.org/10.1115/mnhmt2009-18247.
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In this study we introduce our numerical and experimental works for the thermal conductivity reduction by using a porous material. Recently thermal conductivity reduction has been one of the key technologies to enhance the figure of merit (ZT) of a thermoelectric material. We carry out numerical calculations of heat conduction in porous materials, such as, phonon Boltzmann transport (BTE), molecular dynamics simulations (MD), in order to investigate the mechanism of the thermal conductivity reduction of a porous material. In the BTE, we applied the periodic boundary conditions with constant heat flux to calculate the effective thermal conductivity of porous materials. In the MD simulation, we calculated phonon properties of Si by using the Stillinger-Weber potential at constant temperature with periodic boundary conditions in the x, y and z directions. Phonon dispersion curves of single crystal of Si calculated from MD results by time-space 2D FFT are agreed well with reference data. Moreover, the effects of nano-porous structures on both the phonon group velocity and the phonon density of states (DOS) are discussed. At last, we made a porous p-type Bi2Te3 by nano-particles prepared by a beads milling method. The thermal conductivity is one-fifth of that of a bulk material as well as keeping the same Seebeck coefficient as the bulk value. However electrical conductivity was much reduced, and the ZT was only 0.048.
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Park, Jong-Jin, and Minoru Taya. "Design of Micro-Arrayed Thin Film Thermocouples (TFTC)." In ASME 2003 International Electronic Packaging Technical Conference and Exhibition. ASMEDC, 2003. http://dx.doi.org/10.1115/ipack2003-35040.
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We designed the thin film thermocouples (TFTC) made by T-type (Copper-Constantan) thermocouple arrays in order to measure temperature distribution at higher spatial resolutions. This sensor consists of a few different layers; silicon wafer, thin aluminum nitride (AlN) layer, and thin film thermocouple layers. The thickness of the thin aluminum nitride (AlN) layer is 100nm and the layer is located between silicon wafer and thin film thermocouples to construct an electrical insulator and thermal conductor. T-type (Copper-Constantan) thermocouples are deposited on the aluminum nitride (AlN) layer over the silicon wafer and the copper thickness and constantan thickness are 50nm, repectively. The sensor area is 10mm × 10mm, and has 10 × 10 junction arrays, and each junction has 100μm × 100μm surface area. According to the measured data, electrical resistivitives of thin films are almost 5 times greater than those of bulk materials. This is based on the comparison of thermal simulation and measured data of 1-D heat conduction in steady state. Seebeck coefficients between copper bulk material and constantan thin film are calculated and the weight factor is defined due to Seebeck coefficient mismatches of bulk materials and thin films. Thermal simulation of 2-dimensional heat conduction in steady state calculated by finite element analysis and compared with the measured data, resulting in a good agreement between simulations and measured data.
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Watkins, Bobby G., and Jeffrey Streator. "Simulation of Thermal Effects in Stationary and Sliding Electrical Contacts." In STLE/ASME 2008 International Joint Tribology Conference. ASMEDC, 2008. http://dx.doi.org/10.1115/ijtc2008-71301.
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Sliding electrical contacts are subject to surface damage and wear, which can be enhanced by the heating at the interface arising from electrical contact resistance. For example, in electromagnetic launcher (EML) technology, thermally assisted wear processes can result in unacceptable levels of material loss at the armature-rail interface. The control of the interface tribology in sliding electrical contacts requires an understanding of the Joule heating in the vicinity of the interface. In the current study, a multiphysics numerical simulation is conducted of transient heat conduction in both a stationary and a sliding electrical contact. The interface under investigation consists of a flat-ended aluminum cylindrical pin sliding against an aluminum rail. Electrical contact resistance is modeled by introducing a thin layer of high resistivity between the pin and the rail. Results show that shortly after sliding has commenced, (1) the maximum temperature rise occurs in the bulk of the pin rather than at the interface, (2) the bulk of the Joule heat goes into the rail, and (3) that sliding can have a significant effect on the temperature field, even when the speed is quite low.
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Miyazaki, Koji. "Heat Conduction in a Nano-Porous Material and Its Application." In ASME 2011 9th International Conference on Nanochannels, Microchannels, and Minichannels. ASMEDC, 2011. http://dx.doi.org/10.1115/icnmm2011-58293.
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In this study we introduce our numerical and experimental works for the thermal conductivity reduction by using a porous material. Recently thermal conductivity reduction has been one of the key technologies to enhance the figure of merit (ZT) of a thermoelectric material. We carry out numerical calculations of heat conduction in porous materials, such as, phonon Boltzmann transport (BTE), molecular dynamics simulations (MD), in order to investigate the mechanism of the thermal conductivity reduction of a porous material. In the BTE, we applied the periodic boundary conditions with constant heat flux to calculate the effective thermal conductivity of porous materials. In the MD simulation, we calculated phonon properties of Si by using the Stillinger-Weber potential at constant temperature with periodic boundary conditions in the x,y and z directions. Phonon dispersion curves of single crystal of Si calculated from MD results by time-space 2D FFT are agreed well with reference data. Moreover, the effects of nano-porous structures on both the phonon group velocity and the phonon density of states (DOS) are discussed. At last, we made a porous p-type Bi2Te3 by using self-assembly. The average diameter of the holes was 20 nm, and the average pitch of the hexagonally arranged holes was 50 nm. The measured cross-plane thermal conductivity is 0.25W/(m·K). The thermal conductivity of the thin film is extremely lower than that of the bulk material without any major decrease in the electrical conductivity. The figure of merit of Bi0.4Te3Sb1.6 is enhanced to 1.8 at room temperature (300K) by the formation of a porous thin film.
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Liu, Wenjun, and Mehdi Asheghi. "Thermal Conduction in Ultra-Thin Pure and Doped Single Crystal Silicon Layers at High Temperatures." In ASME 2005 Summer Heat Transfer Conference collocated with the ASME 2005 Pacific Rim Technical Conference and Exhibition on Integration and Packaging of MEMS, NEMS, and Electronic Systems. ASMEDC, 2005. http://dx.doi.org/10.1115/ht2005-72540.
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This work presents the in-plane thermal conductivity data for pure as well as boron (1.6 × 1021 /cm3), arsenic (2.3 × 1020 /cm3) and phosphorus (2.3 × 10 20/cm3) doped silicon layers of thickness 30 and 50 nm at high temperature. The steady-state Joule heating and electrical resistance thermometry is used to measure lateral thermal conductivity of suspended silicon layers. Thermal conductivity data for pure and lightly doped single crystalline silicon layers can be interpreted using thermal conductivity integral and relaxation time approximation for phonon-boundary and phonon-impurity scattering rates. No additional fitting parameters are used in this work; in contrast with previous studies that required an unusually large phonon-impurity scattering coefficient to match the predictions to the thermal conductivity data for bulk doped silicon. This paper was also originally published as part of the Proceedings of the ASME 2005 Pacific Rim Technical Conference and Exhibition on Integration and Packaging of MEMS, NEMS, and Electronic Systems.
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Rittinon, Pornvitoo, Ken Suzuki, and Hideo Miura. "Improvement of Thermal Conductivity of Electroplated Copper Thin-Film Interconnections by Controlling Their Micro Texture." In ASME 2014 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/imece2014-36863.
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Copper thin films are indispensable for the interconnections in the advanced electronic products, such as TSV (Trough Silicon Via), fine bumps, and thin-film interconnections in various devices and interposers. However, it has been reported that both electrical and mechanical properties of the films vary drastically comparing with those of conventional bulk copper. The main reason for the variation can be attributed to the fluctuation of the crystallinity of grain boundaries in the films. Porous or sparse grain boundaries show very high resistivity and brittle fracture characteristic in the films. Thus, the thermal conductivity of the electroplated copper thin films should be varied drastically depending on their micro texture based on the Wiedemann-Franz’s law. Since the copper interconnections are used not only for the electrical conduction but also for the thermal conduction, it is very important to quantitatively evaluate the crystallinity of the polycrystalline thin-film materials and clarify the relationship between the crystallinity and thermal properties of the films. The crystallinity of the interconnections were quantitatively evaluated using an electron back-scatter diffraction method. It was found that the porous grain boundaries which contain a significant amount of vacancies increase the local electrical resistance in the interconnections, and thus, cause the local high Joule heating. Such porous grain boundaries can be eliminated by control the crystallinity of the seed layer material on which the electroplated copper thin film is electroplated.
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Michopoulos, John G., Marcus Young, and Athanasios Iliopoulos. "Multiscale and Multifield Multiphysics of High Current Pulse Static Contact With Rough Surfaces." In ASME 2013 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/detc2013-12879.
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We are presenting a multi-field and multiscale theory leading to derivations of physical properties from surface topography and bulk material properties for the interface between two rough surfaces in contact activated by mechanical load and high current pulses. At the macro-scale our proposed model involves multi-field coupling of conduction and induction currents with heat conduction induced by Joule heating. The structural mechanics of the conducting materials are also considered. At the meso-scale and micro-scale the associated model contains an asperity based comprehensive model that leads to homogenized macro scale properties for the interface boundary. The mechanical pressure and the repulsion effect from electric current through the micro-contacts are accounted for as well. Numerical analysis results illustrate the dependence of the derived properties on the surface characteristics, external load and the electric current. Finally, the entire framework is applied to an actual conductor configuration of hollow cylinders under compression and a high current pulse to demonstrate the feasibility of the entire approach.
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Liu, Wenjun, and Mehdi Asheghi. "Thermal Conductivity of Ultra Thin Single Crystal Silicon Layers: Part I — Experimental Measurements at Room and Cryogenic Temperatures." In ASME 2004 International Mechanical Engineering Congress and Exposition. ASMEDC, 2004. http://dx.doi.org/10.1115/imece2004-62105.
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Self-heating in deep submicron transistors (e.g., Silicon-on-insulator and strained-Si) and thermal engineering of many nanoscale devices such as nanocalorimeters and high-density thermomechanical data storage are strongly influenced by thermal conduction in ultra-thin silicon layers. The lateral thermal conductivity of single-crystal silicon layers of thicknesses 20 and 100 nm at temperatures between 30 and 300 K was measured using Joule heating and electrical-resistance thermometry in suspended microfabricated structures. In general, a large reduction in thermal conductivity resulting from phonon-boundary scattering, particularly at low temperatures, is observed. Thermal conductivity of the 20 nm thick silicon layer at room temperature is nearly 22 W m−1K−1, compared to the bulk value, 148 W m−1K−1. The predictions of the classical thermal conductivity theory that accounts for the reduced phonon mean free paths based on a solution of the Boltzmann transport equation along a layer agrees well with the experimental results.
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Zhang, Shu, Yizhang Yang, Yoed Rabin, Katayun Barmak, and Mehdi Asheghi. "A Novel Experimental Procedure and Technique for Smallscale Calorimetry." In ASME/JSME 2007 Thermal Engineering Heat Transfer Summer Conference collocated with the ASME 2007 InterPACK Conference. ASMEDC, 2007. http://dx.doi.org/10.1115/ht2007-32894.
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By definition, a differential scanning calorimetry (DSC) requires a sample structure and a refrence structure to obtain the latent heat of a speicman. We propose a novel approach, named Phase Transition Calorimetry (PTC), to obtain the specimen’s latent heat by using only the signal from the sample bridge. The new setup and procedure are primarily based on electrical resistance heating and thermometry and the parametric estimation method by solving the heat conduction equation with and without the phase transformation. The new setup has two major advantages over widely used DSC setups: there are no errors associated with heat loss to the surroundings, and the uncertainty resulting from the difference between the sample and the reference is eliminated by removing the reference structure. Experimental validation of the new setup and procedure is demonstrated by measuring the latent heat of thin layers of tin. This was found to be 4.1×108 Jm−3, which is different within 5% from the literature values of bulk specimens.
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Bieri, N. R., S. E. Haferl, D. Poulikakos, and C. P. Grigoropoulos. "Manufacturing of Electrically Conductive Microstructures by Dropwise Printing and Laser Curing of Nanoparticle-Suspensions." In ASME 2002 International Mechanical Engineering Congress and Exposition. ASMEDC, 2002. http://dx.doi.org/10.1115/imece2002-33859.
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A novel method for the manufacturing of electric microconductors for semiconductor and other devices is presented. The method brings together three technologies: controlled (on demand) printing, laser curing, and the employment of nanoparticles of matter, possessing markedly different properties (here, melting point) than their bulk counterparts. A suspension of gold particles in toluene solvent is employed to print electrically conducting line patterns utilizing a modified on demand ink jet printing process. To this end, microdroplets of 80–100 μm diameters are deposited on a moving substrate such that the droplets form continuous lines. Focused laser irradiation is utilized in order to evaporate the solvent, melt the metal nanoparticles in the suspension, and sinter the suspended particles to form continuous, electrically conducting gold microlines on a substrate. The ultra fine particles in the suspension have a diameter size range of 2 – 5 nm. Due to curvature effects of such small particles, the melting point is markedly lower (400°C) than that of bulk gold (1063°C). Thermodynamic aspects of the effect of particle size on the melting and evaporation temperatures of gold and toluene, respectively, are discussed in the paper. The structure and line width of the cured line as a function of the laser irradiation power and stage velocity are reported in detail. Preliminary measurements of the electrical conductivity are represented.
Reports on the topic "Bulk electrical conduction"
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Scherer, Michelle M., and Kevin M. Rosso. 2015 Progress Report/July 2016: Iron Oxide Redox Transformation Pathways: The Bulk Electrical Conduction Mechanism. Office of Scientific and Technical Information (OSTI), July 2016. http://dx.doi.org/10.2172/1271183.
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