Carbon nanotubes are elongated cylindrical structures with a diameter of one to several tens of nanometers and length up to several microns comprised of one or more hexagonal planes of graphite (graphene) rolled into a nanotube, usually ended with hemispherical head.
Carbon nanotubes, discovered in 1991, can be single-walled or multi-layered. Accordingly, the diameter of these nanotubes is in the range of 0.4 – 500 nm, with a length from 1 micron to several tens of micrometers (and even tens of cm in the synthesis of long fibers). These nanotubes are formed by the decomposition of carbon-gases (CH4, C2H4, C2H2, CO, S6N6 vapor, etc.) on catalytically active surfaces of metals (Fe, Co, Ni, etc.) in t-Rahim 300 – 1500 ° C. They can take a variety of forms, from straight to twisted fibers (including spirals). The main feature of these carbon nanostructures, as well as fullerenes, are their frame structure. Identified natural forms of carbon nanotubes (e.g., shung) can be produced artificially. It is found that the natural nanotubes are formed during the processing of carbon-biological tissue by specific fungus, discovered, particularly in karstic caves of New Zealand and in Karelia (Shung field).
There are metallic and semiconducting nanotubes. Metallic nanotubes conduct electricity even at absolute zero temperature, while the conductivity of semiconducting nanotubes is zero at absolute zero and increases with increasing temperature. Technically speaking, semiconducting nanotubes have a band gap.
This applies to simple single-walled nanotubes. When in the real world you can often see multilayered nanotubes, which can be presented as a few single-walled nanotubes nested into one another (so-called “Russian dolls”).
Single-walled and multilayered coaxial nanotubes are formed by rolling strips of flat grid nuclear graphite in seamless cylinders. The inner diameter of carbon nanotubes can vary from 0.4 to a few nanometers, and the internal volume may contain other compounds. Single-layer nanotubes have fewer defects, and after high-temperature annealing in an inert atmosphere, defect-free nanotubes can be obtained. Nanotube type structure affects its chemical, electronic, and mechanical properties. Individual nanotubes are aggregated to form the different types of aggregates with cracks.
Students writing their research proposal on the subject may use free sample or example research paper topics on carbon nanotubes, from which they may learn that multilayered nanotubes are different from single-walled by a wider range of shapes and configurations. Various types of structure are both longitudinal and in the transverse direction. The structure of the “Russian dolls” is a set of coaxially nested single-walled cylindrical nanotubes. Another kind of structure, is a set of nested coaxial prisms. For all the above-mentioned structures, the distance between adjacent graphene layers is close to the value of 0.34 nm characteristic, corresponding to the crystal planes of graphite. Implementation of a structure in a given situation depends on the experimental conditions of the nanotubes synthesis.
At EssayLib.com writing service you can order a custom research paper on Carbon Nanotube topics. Your research paper will be written from scratch. We hire top-rated Ph.D. and Master’s writers only to provide students with professional research paper assistance at affordable rates. Each customer will get a non-plagiarized paper with timely delivery. Just visit our website and fill in the order form with all research paper details:
Enjoy our professional research paper writing service!