scholarly journals Electron Percolation In Copper Infiltrated Carbon

2015 ◽  
Vol 66 (6) ◽  
pp. 339-343
Author(s):  
Stanislav Krcho
Keyword(s):  
Electrical Conductivity ◽  
Sharp Increase ◽  
Copper Concentration ◽  
Carbon Materials ◽  
Pore Radius ◽  
Critical Concentration ◽  
Effective Radius ◽  
Carbon Skeleton ◽  
Percolation Process ◽  
Effective Pore Radius

Abstract The work describes the dependence of the electrical conductivity of carbon materials infiltrated with copper in a vacuum-pressure autoclave on copper concentration and on the effective pore radius of the carbon skeleton. In comparison with non-infiltrated material the electrical conductivity of copper infiltrated composite increased almost 500 times. If the composite contained less than 7.2 vol% of Cu, a linear dependence of the electrical conductivity upon cupper content was observed. If infiltrated carbon contained more than 7.2 vol% of Cu, the dependence was nonlinear – the curve could be described by a power formula (x − xc)t. This is a typical formula describing the electron percolation process in regions containing higher Cu fraction than the critical one. The maximum measured electrical conductivity was 396 × 104 Ω−1 m−1 for copper concentration 27.6 vol%. Experiments and analysis of the electrical conductivity showed that electron percolation occurred in carbon materials infiltrated by copper when the copper volume exceeded the critical concentration. The analysis also showed a sharp increase of electrical conductivity in composites with copper concentration higher than the threshold, where the effective radius of carbon skeleton pores decreased to 350 nanometres.

scholarly journals The effective pore radius of screen wicks.

1990 ◽  
Vol 56 (521) ◽  
pp. 168-174 ◽  
Author(s):  
Hiroaki KOZAI ◽  
Hideaki IMURA ◽  
Yuji IKEDA
Keyword(s):  
Pore Radius ◽  
Effective Pore Radius

Carbon Materials and Their Modified Materials for Lithium Ion Battery Anodes : A Comprehensive Review

2021 ◽  
Author(s):  
Qiaoyu feng ◽  
Xueye Chen
Keyword(s):  
Electrical Conductivity ◽  
Carbon Materials ◽  
Negative Electrode ◽  
Lithium Ion ◽  
Lithium Ions ◽  
New Type ◽  
Metal Materials ◽  
Negative Electrode Material ◽  
Poor Stability ◽  
Carbon Based

<p>As a negative electrode material for lithium ion batteries (LIBs), carbon has a higher cycle life and higher safety. However, it has poor electrical conductivity, low charging and discharging platform, and poor stability of layered structure. Some carbon materials are complicated to make such as synthetic graphene, and the shape is difficult to control. Metal materials have good electrical conductivity, but due to the rapid volume expansion of lithium ions during the cycle of insertion and extraction, the electrodes are extremely quickly crushed and accompanied by extremely rapid capacity decay. Scholars have combined the advantages of carbon and metal materials to create a new type of carbon-based composite material. This article outlines the use of carbon based composite materials as lithium-ion electrodes to improve battery performance.</p>

A dynamic wicking technique for determining the effective pore radius of pregelatinized starch sheets

2004 ◽  
Vol 35 (3-4) ◽  
pp. 159-167 ◽  
Author(s):  
E.P Kalogianni ◽  
T Savopoulos ◽  
T.D Karapantsios ◽  
S.N Raphaelides
Keyword(s):  
Pore Radius ◽  
Pregelatinized Starch ◽  
Effective Pore Radius

Permeability and Effective Pore Radius Measurements for Heat Pipe and Fuel Cell Applications

2004 ◽  
Author(s):  
Brian M. Holley ◽  
Amir Faghri
Keyword(s):  
Fuel Cells ◽  
Pore Radius ◽  
Heat Pipes ◽  
Gas Diffusion ◽  
Carbon Paper ◽  
Permeability Measurement ◽  
Gas Diffusion Layers ◽  
Diffusion Layers ◽  
Sintered Metal ◽  
Effective Pore Radius

Permeability and effective pore radius of sintered metal powder and carbon paper samples, with specific application to fuel cells and heat pipes, were measured using the rate-of-rise test. The performance of wicks in heat pipes is characterized by effective pore radius and permeability, while the permeability measurement by itself is useful for modeling in-plane phenomena of gas diffusion layers in fuel cells. The rate-of-rise measurement technique is characterized by its simplicity and non-intrusiveness, but previous results have been considered inaccurate. In this study the amount of liquid in the samples was measured by sight for some samples but also by weight change for other samples, which is a new adaptation of the rate-of-rise test. Data is analyzed using an equation resulting from a simple model of the rising meniscus. Knowing the behavior of the equation is important when reducing data in order to obtain more accurate results. The methods used in experimentation and data reduction demonstrate the wider use and increased accuracy of the rate-of-rise test.

Carbonised polyaniline and polypyrrole: towards advanced nitrogen-containing carbon materials

2013 ◽  
Vol 67 (8) ◽  
Author(s):  
Gordana Ćirić-Marjanović ◽  
Igor Pašti ◽  
Nemanja Gavrilov ◽  
Aleksandra Janošević ◽  
Slavko Mentus
Keyword(s):  
Electrical Conductivity ◽  
Carbon Materials ◽  
Modern Technology ◽  
Electron Microscopies ◽  
Transmission Electron ◽  
Elemental Analyses ◽  
Adsorption Desorption

AbstractPolyaniline (PANI) and polypyrrole (PPY) undergo carbonisation in an inert/reduction atmosphere and vacuum, yielding different nitrogen-containing carbon materials. This contribution reviews various procedures for the carbonisation of PANI and PPY precursors, and the characteristics of obtained carbonised PANI (C-PANI) and carbonised PPY (C-PPY). Special attention is paid to the role of synthetic procedures in tailoring the formation of C-PANI and C-PPY nanostructures and nanocomposites. The review considers the importance of scanning and transmission electron microscopies, XPS, FTIR, Raman, NMR, and EPR spectroscopies, electrical conductivity and adsorption/desorption measurements, XRD, and elemental analyses in the characterisation of C-PANIs and C-PPYs. The application of C-PANI and C-PPY in various fields of modern technology is also reviewed.

Multiple Small Angle Neutron Scattering Characterization of the Densification of Alumina

1989 ◽  
Vol 166 ◽  
Author(s):  
S. Krueger ◽  
G.C. Long ◽  
R.A. Page
Keyword(s):  
Neutron Scattering ◽  
Small Angle ◽  
Small Angle Neutron Scattering ◽  
Pore Radius ◽  
Intermediate Stage ◽  
Sample Density ◽  
Microstructure Morphology ◽  
Interconnected Pore ◽  
Effective Pore Radius

ABSTRACTMultiple small angle neutron scattering (MSANS) was used to follow the evolution of the pore size distribution in α-Al2O3through the intermediate and final stages of sintering. This technique makes it possible to determine microstructure morphology in the 0.08 to 10 μm size regime under conditions where the total scattering cross-section is dominated by elastic incoherent multiple scattering, as is often the case for ceramics. The MSANS results indicate an initial decrease in the effective pore radius from 0.19 μm at 57% of theoretical density (TD) to 0.17 μm at 79% TD. As the sample density further increased, there was a transition region after which the effective pore radius grew rapidly to ≤0.5 μm at 98% TD. Standard Porod analysis on scattering by the same samples also indicates a transition between the intermediate and final stages of processing. Both sets of results support a topological model of sintering in which the interconnected pore network in the intermediate stage of sintering decays in a stable manner. The pores become fewer, while retaining the same diameter, as densification proceeds. In the final stage, isolated pores remain.

The effect of copper supply on vegetative and seed yield of pasture legumes and the field calibration of a tissue test for detecting copper deficiency. II. Strawberry clover (Trifolium fragiferum L.)

1989 ◽  
Vol 40 (4) ◽  
pp. 833
Author(s):  
JD McFarlane
Keyword(s):  
Seed Production ◽  
Seed Yield ◽  
Dry Matter ◽  
Copper Concentration ◽  
Copper Deficiency ◽  
Critical Concentration ◽  
Dry Matter Production ◽  
Pasture Legumes ◽  
Critical Range ◽  
Matter Production

Seven rates of copper were applied to the soil prior to the sowing of strawberry clover (Trifolium fragiferumL. cv. Palestine) on an alkaline peat deficient in copper. Symptoms of copper deficiency were evident only on the untreated plots where the clover did not set seed nor persist into the second year.Over five years� production, 1.0 kg Cu/ha continued to provide adequate copper, with regular dressings of superphosphate, for maximum dry matter production and seed yield. It was found that seed yield was more sensitive than vegetative dry matter yield to sub-optimal copper supply. At the lowest rate of applied copper (0.125 kg/ha), the vegetative yield ranged from 53% to 80% of the maximum harvest yield, whereas the seed yield ranged from 15% to 50% of maximum yield.For tissue sampled in the spring, the proposed critical range for copper concentration in the youngest open leaf (YOL) for vegetative dry matter production is 3-35 mg Cu/kg whereas that for seed production is 4.5-5.5 mg Cu/kg. At other times of the year the critical concentrations were higher. It was not clear if this was due to environmental conditions or changing internal requirements for copper.The critical copper concentration range in whole top (WT) tissue of 3.0-4.0 mg/kg for vegetative dry matter production could be applied to all samplings. For seed yield the critical range for copper concentration in WT was 4.0-5.0 mg/kg for the spring harvests. The critical copper concentration in seed for seed production was 5.0-6.0 mg/kg. In the pasture situation a critical concentration of 5.0-6.0 mg Cu/kg in the WT should be adopted when the animal requirement is considered.

scholarly journals Biomass-derived carbon electrodes for supercapacitors and hybrid solar cells: towards sustainable photo-supercapacitors

2021 ◽  
Author(s):  
Nilanka M. Keppetipola ◽  
Céline Olivier ◽  
Thierry Toupance ◽  
Ludmila Cojocaru
Keyword(s):  
Electrical Conductivity ◽  
Solar Cells ◽  
Electrochemical Properties ◽  
Carbon Materials ◽  
Low Cost ◽  
Carbon Electrodes ◽  
Hybrid Solar Cells ◽  
Potential Applications ◽  
Electrodes For Supercapacitors

Due to their outstanding electrochemical properties, electrical conductivity, flexibility, and low-cost, carbon materials open up new opportunities for the design of compact devices with a wide variety of potential applications....

scholarly journals Assessing the Critical Multifunctionality Threshold for Optimal Electrical, Thermal, and Nanomechanical Properties of Carbon Nanotubes/Epoxy Nanocomposites for Aerospace Applications

Aerospace ◽  
2019 ◽  
Vol 6 (1) ◽  
pp. 7 ◽  
Author(s):  
Aikaterini-Flora Trompeta ◽  
Elias Koumoulos ◽  
Sotirios Stavropoulos ◽  
Theodoros Velmachos ◽  
Georgios Psarras ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Carbon Nanotubes ◽  
Thermal Stability ◽  
Electrical Conductivity ◽  
Critical Concentration ◽  
Epoxy Composites ◽  
Micro Computed Tomography ◽  
Epoxy Nanocomposites ◽  
Aerospace Structures ◽  
Nanomechanical Properties

Epoxy composites are widely used in primary aerospace structures, where high impact damage properties are necessary. However, challenges appear when multiple functionalities, including electrical and thermal conductivity, are needed in parallel with increased mechanical properties. The current study aims at the assessment of a critical concentration of multiwalled carbon nanotubes (MWCNTs), incorporated in epoxy resin, which will indicate a threshold for optimal electrical, thermal and mechanical properties. For the evaluation of this optimal concentration, electrical conductivity, thermal stability and nanomechanical properties (Young modulus and nanohardness) have been assessed, for epoxy nanocomposites with 0 to 15 parts per hundred resin per weight (phr) MWCNTs. Percolation theory was applied to study the electrical conductivity for different contents of MWCNTs in the epoxy nanocomposite system. Thermogravimetric analysis was employed for the assessment of the epoxy composites’ thermal properties. Nanohardness and elastic modulus were measured, and the hardness versus modulus index was calculated. Emphasis was given to the dispersion of MWCNTs in the epoxy matrix, which was assessed by both microscopy techniques and X-ray micro–computed tomography. A correlation between the optimum dispersion and MWCNTs content in terms of electrical conductivity, thermal stability, and nanomechanical properties revealed a threshold concentration at 3 phr, allowing the manufacturing of aerospace structures with multifunctional properties.

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