Lectures on the Electrical Properties of Materials

Solymár, L.; Walsh, Donald D.; Miller, Whitney

doi:10.1119/1.1987989

Cited by 49 publications

(39 citation statements)

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“…Field emission results are usually analyzed by the FowlerNordheim (F-N) theory, which describes the emission of electrons from a metal as quantum-mechanical tunneling enhanced by a strong electric field [26][27][28]. The F-N equation can be written as:…”

Section: Field Emission Properties Of Fwcnts/teos Thin Film Field Emimentioning

confidence: 99%

Effect of few-walled carbon nanotube crystallinity on electron field emission property

Jeong¹,

Lee²,

Lee³

et al. 2011

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We discuss the influence of few-walled carbon nanotubes (FWCNTs) treated with nitric acid and/or sulfuric acid on field emission characteristics. FWCNTs/tetraethyl orthosilicate (TEOS) thin film field emitters were fabricated by a spray method using FWCNTs/TEOS sol one-component solution onto indium tin oxide (ITO) glass. After thermal curing, they were found tightly adhered to the ITO glass, and after an activation process by a taping method, numerous FWCNTs were aligned preferentially in the vertical direction. Pristine FWCNT/ TEOS-based field emitters revealed higher current density, lower turn-on field, and a higher field enhancement factor than the oxidized FWCNTs-based field emitters. However, the unstable dispersion of pristine FWCNT in TEOS/N,N-dimethylformamide solution was not applicable to the field emitter fabrication using a spray method. Although the field emitter of nitric acid-treated FWCNT showed slightly lower field emission characteristics, this could be improved by the introduction of metal nanoparticles or resistive layer coating. Thus, we can conclude that our spray method using nitric acid-treated FWCNT could be useful for fabricating a field emitter and offers several advantages compared to previously reported techniques such as chemical vapor deposition and screen printing.

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Section: Field Emission Properties Of Fwcnts/teos Thin Film Field Emimentioning

confidence: 99%

Effect of few-walled carbon nanotube crystallinity on electron field emission property

Jeong¹,

Lee²,

Lee³

et al. 2011

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“…There are two principal electrical properties, namely, (i) the relative permittivity (ε r ), which is a measure of the electrical polarization of the material (Mahmood et al 2012) that takes place when an electric field is applied and (ii) the electrical conductivity (σ ), which is a measure of the conduction current resulted from an electric field through the material (see e.g. Keller 1966;Solymar et al 2014). These properties can provide valuable information about the macro-and microscopic properties of geological formations.…”

Section: Introductionmentioning

confidence: 99%

Geoelectrical characterization of carbonate and silicate porous media in the presence of supercritical CO₂–water flow

Abidoye

Das

2015

Geophys. J. Int.

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S U M M A R YThe relative permittivity (ε r ) and the electrical conductivity (σ ) of porous media are known to be functions of water saturation (S). As such, their measurements can be useful in effective characterisations and monitoring of geological carbon sequestration using geoelectrical measurement techniques. In this work, the effects of pressure, temperature and salt concentration on bulk ε r -S and σ -S relationships were investigated for carbonate (limestone) and silicate porous media (both unconsolidated domains) under dynamic and quasi-static supercritical CO 2 (scCO 2 )-brine/water flow. In the silica sand sample, the bulk ε r (ε b ) for scCO 2 -water decreases as the temperature increases. On the contrary, slight increase was seen in the ε b with temperature in the carbonate sample for the scCO 2 -water system. These trends are more conspicuous at high water saturation. The ε b -S curves for the scCO 2 -water flow in the silica sand also show clear dependency on the domain pressure, where ε b increases as the domain pressure increases. Furthermore, the bulk σ (σ b ), at any particular saturation for the scCO 2 -brine system rises as the temperature increases with more significant increase found at very high water saturation. Both ε b and σ b values are found to be greater in the limestone than silica sand porous samples for similar porosity values. Based on different injection rates investigated, we do not find significant dynamic effects in the ε b -S and σ b -S relationships for the scCO 2 -brine/water system. As such, geoelectrical characteristics can be taken as reliable in the monitoring of two-phase flow system in the porous media. It can be inferred from the results that the geoelectrical techniques are highly dependent on water saturation. This dependence is more conspicuous at higher water saturation. Different mathematical models examined show their reliability at different water saturation ranges. The polynomial fit developed in this work takes into consideration the fluid pressure in the system as well as the initial bulk relative permittivity prior to the injection of CO 2 . The polynomial fit shows a good reliability in the prediction of the geo-electrical properties of the CO 2 -water-porous media system, especially at higher water saturation. In comparison, the mixing model from the literature shows more reliability in the prediction of similar property at lower water saturation.

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“…The sample chamber was evacuated and back-filled with He and heated from room temperature to 900 K using an IR furnace. s is measured using standard four-point probe technique [92]. The S is calculated by measuring average induced voltage resulting from temperature gradients provided by resistive Pt coils located beneath one electrode.…”

Section: Electrical Conductivity/seebeck Coefficient Measurementsmentioning

confidence: 99%

Electron Microscopy for Characterization of Thermoelectric Nanomaterials

2013

Transmission Electron Microscopy Characterization of Nanomaterials

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Lectures on the Electrical Properties of Materials

Cited by 49 publications

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Effect of few-walled carbon nanotube crystallinity on electron field emission property

Effect of few-walled carbon nanotube crystallinity on electron field emission property

Geoelectrical characterization of carbonate and silicate porous media in the presence of supercritical CO₂–water flow

Electron Microscopy for Characterization of Thermoelectric Nanomaterials

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Lectures on the Electrical Properties of Materials

Cited by 49 publications

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Effect of few-walled carbon nanotube crystallinity on electron field emission property

Effect of few-walled carbon nanotube crystallinity on electron field emission property

Geoelectrical characterization of carbonate and silicate porous media in the presence of supercritical CO2–water flow

Electron Microscopy for Characterization of Thermoelectric Nanomaterials

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Geoelectrical characterization of carbonate and silicate porous media in the presence of supercritical CO₂–water flow