Abstract:A new method to characterize microwave electromagnetic (EM) absorption of a bulk carbon nanotube (CNT) material is proposed and experimentally evaluated in this paper. The method is based on the measurement of microwave transmission through a capacitive-resonator aperture (CRA) in a conductive screen loaded with a CNT sample under test. This method allows to measure microwave permittivity and absorption of thin samples (~ 0.1μm-10μm thick) with linear dimensions much smaller than the wavelength of radiation in… Show more
“…CNT Synthesis: The carbon nanotube assemblies in this work were produced in a floating-catalyst chemical vapor deposition system that had been previously reported. [36] Hydrogen gas carries ferrocene powder (130 sccm) and liquid thiophene vapor (90 sccm) from bubbling systems into the furnace where they thermally decompose to form the catalyst particles. The hydrogen carrier gas (1350 sccm) also helped maintain the iron particles' catalytic activity by etching amorphous carbon coatings.…”
An atmospheric‐pressure plasma system is developed and is used to treat carbon nanotube assemblies, producing a hybrid carbon‐zinc structure. This system is integrated into a floating‐catalyst chemical vapor deposition furnace used for the synthesis of macroscopic assemblies of carbon nanotubes to allow for the in‐line, continuous, and single‐step production of nano‐composite materials. Material is deposited from a sacrificial zinc wire in the form of nanoparticles and can coat the surface of the individual carbon nanotubes as they form. Additionally, it is found that the deposited materials penetrate further into the carbon nanotube matrix than a comparable post‐synthesis deposition, improving the uniformity of the material through the thickness. Thus, a single‐step metal‐based coating and carbon nanotube synthesis process which can form the basis of production scale manufacturing of metal‐carbon nanotube composite materials with an atmospheric‐pressure plasma system are demonstrated.
“…CNT Synthesis: The carbon nanotube assemblies in this work were produced in a floating-catalyst chemical vapor deposition system that had been previously reported. [36] Hydrogen gas carries ferrocene powder (130 sccm) and liquid thiophene vapor (90 sccm) from bubbling systems into the furnace where they thermally decompose to form the catalyst particles. The hydrogen carrier gas (1350 sccm) also helped maintain the iron particles' catalytic activity by etching amorphous carbon coatings.…”
An atmospheric‐pressure plasma system is developed and is used to treat carbon nanotube assemblies, producing a hybrid carbon‐zinc structure. This system is integrated into a floating‐catalyst chemical vapor deposition furnace used for the synthesis of macroscopic assemblies of carbon nanotubes to allow for the in‐line, continuous, and single‐step production of nano‐composite materials. Material is deposited from a sacrificial zinc wire in the form of nanoparticles and can coat the surface of the individual carbon nanotubes as they form. Additionally, it is found that the deposited materials penetrate further into the carbon nanotube matrix than a comparable post‐synthesis deposition, improving the uniformity of the material through the thickness. Thus, a single‐step metal‐based coating and carbon nanotube synthesis process which can form the basis of production scale manufacturing of metal‐carbon nanotube composite materials with an atmospheric‐pressure plasma system are demonstrated.
“…In (2), ( ) and ( ) are the real parts of the complex-valued relative permittivity of the host medium and contaminant respectively. A is a constant that depends on the sensor geometry [41] and, in general, the permittivity of the sample, and can be found from comparing the reflection spectra of an empty (unloaded) sensor and a sensor loaded with a calibrated sample under test, (e.g. clean soil).…”
Section: B Mathematical Model Of the S11 Resonance Frequency Shiftmentioning
confidence: 99%
“…The resonance frequency fL of a microwave sensor loaded with a material sample with real-part relative permittivity , and the resonance frequency fU of an unloaded sensor (air) are connected by the relation [41]…”
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