Iron-filled multi-walled carbon nanotubes for terahertz applications: effects of interfacial polarization, screening and anisotropy

Sedelnikova, Olga V.; Korovin, E. Yu.; Dorozhkin, K. V.; Kanygin, M. A.; Архипов, В. Е.; Shubin, Yu. V.; Zhuravlev, V. A.; Suslyaev, V. I.; Bulusheva, L. G.; Окотруб, А. В.

doi:10.1088/1361-6528/aaae43

Cited by 11 publications

(7 citation statements)

References 57 publications

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“…A continuous supply of the reaction mixture for 1.5 h led to the formation of a vertically aligned CNT array on the substrate surface. The iron content in the CNT array was ~3.5 wt % [ 39 ].…”

Section: Methodsmentioning

confidence: 99%

Hydrogen Plasma Treatment of Aligned Multi-Walled Carbon Nanotube Arrays for Improvement of Field Emission Properties

et al. 2020

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Vertically aligned carbon nanotube (CNT) arrays show potential for the development of planar low-voltage emission cathodes. The characteristics of cathodes can be improved by modifying their surface, e.g., by hydrogen plasma treatment, as was performed in this work. The surface of multi-walled CNT arrays grown on silicon substrates from toluene and ferrocene using catalytic chemical vapor deposition was treated in a high-pressure (~104 Pa) microwave reactor. The structure, composition, and current-voltage characteristics of the arrays were studied before and after hydrogen plasma treatment at various power values and durations. CNT tips were destroyed and catalytic iron was released from the CNT channels. The etching rate was influenced by iron particles that formed on the array surface. The lower emission threshold in the plasma-treated arrays than in the initial sample is explained by the amplification factor of the local electric field increasing due to graphene structures of unfolded nanotube layers that formed at the CNT tips.

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Section: Methodsmentioning

confidence: 99%

Hydrogen Plasma Treatment of Aligned Multi-Walled Carbon Nanotube Arrays for Improvement of Field Emission Properties

et al. 2020

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“…The universal conductivity behavior has been observed also by Polley et al [233,234] In the first paper [233] the authors used SW CNT/polymer composites where the conductivity of the samples was tuned by changing the CNT length (up to 15 µm) and the weight fraction. [235] Shuba et al [236] proposed short-length p-doped CTNs as building blocks for high-epsilon materials in the THz range. The conductivity or permittivity of CNT-containing composites was shown to be tuned by the concentration of Au nanoparticles at the sidewalls [234] or, e.g., by concentration of iron in iron-filled MW CNTs embedded in a polymer.…”

Section: Thz Response Of Carbon Nanotubesmentioning

confidence: 99%

Terahertz Spectroscopy of Nanomaterials: a Close Look at Charge‐Carrier Transport

Kužel

Němec

2019

Advanced Optical Materials

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Transport of charges is a fundamental process in many high-tech applications including photovoltaic or optoelectronic devices, but also in more ordinary components such as unsophisticated wires and other circuitry. The development of nanotechnologies resulted in the fabrication of highly complex materials consisting of a large variety of nanosized elements, which inevitably involve a multitude of charge transport processes occurring on various time-and length-scales. Figure 1 summarizes the most common nanoelements with high application potential.For example, the electrodes employed in Grätzel solar cells [1] are composed of percolated networks of a huge number of metal oxide nanoparticles (top-left panel in Figure 1). Colloidal nanocrystals form the basis for thin film electronics and flexible electronic devices. [2] The synthetic approaches control their composition, size and electronic structure (energy levels, density of states within the bands and in the bandgap) and the charge-carrier transport. [2,3] Nanowires and nanotubes made of conventional semiconductors are quasi 1D systems combining Terahertz spectroscopy has been used for almost two decades for investigations of nanomaterials, including nanocrystals, nanoparticles, nanowires, nanotubes or 2D crystals. Its great importance stems from the fact that it is a noncontact method and, owing to its high frequency and broadband character, it is capable of characterizing charge transport properties within individual nano-objects but also among them. In addition, probing of photoinitiated ultrafast charge dynamics is possible thanks to the sub-picosecond time resolution. Despite this unprecedented potential, the interpretation of the measured terahertz conductivity spectra in many materials is still intensively debated. Herein is presented a review of the experiments performed on nanostructures of conventional semiconductors and on carbon nanomaterials (graphene and carbon nanotubes) during the past decade. The state of the art of the theoretical formalism is provided and discussed, including the intrinsic response, as well as the role of inherent heterogeneity and of the experimental conditions.

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“…According to AAS analysis, acid treatment removes most of the catalyst nanoparticles, however, the samples still contains some residual iron contaminations (1–3 wt.%). One can suggests that acids mainly react with the surface nanoparticles, meanwhile the treatment with a solution of acids could also partially remove the particles encapsulated inside.…”

Section: Resultsmentioning

confidence: 99%

Purification of Single‐Walled Carbon Nanotubes Using Acid Treatment and Magnetic Separation

Gurova

Arhipov

Koroteev

et al. 2019

Physica Status Solidi (b)

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A detailed analysis of TUBALL single‐walled carbon nanotubes (SWCNTs) after two‐step purification involving acid purification treatment with concentrated HCl, HNO3, H2SO4 and solution of HNO3:H2SO4 followed by magnetic processing is presented. The purity degree from iron higher than 99% is achieved, and the yield obtained by the above process is about 75 wt.%. Such high purity of the resultant sample is achieved by removing of the external iron nanoparticles by acid treatment and following extraction of nanotubes containing encapsulated nanoparticles under applied magnetic field. A comprehensive characterization of SWCNTs by Raman, optical absorption, and X‐ray photoelectron spectroscopies reveals purification‐induced changes in the integrity, composition, and electronic properties of SWCNT.

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Iron-filled multi-walled carbon nanotubes for terahertz applications: effects of interfacial polarization, screening and anisotropy

Cited by 11 publications

References 57 publications

Hydrogen Plasma Treatment of Aligned Multi-Walled Carbon Nanotube Arrays for Improvement of Field Emission Properties

Hydrogen Plasma Treatment of Aligned Multi-Walled Carbon Nanotube Arrays for Improvement of Field Emission Properties

Terahertz Spectroscopy of Nanomaterials: a Close Look at Charge‐Carrier Transport

Purification of Single‐Walled Carbon Nanotubes Using Acid Treatment and Magnetic Separation

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