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There are two basic approaches to synthesizing nanowires: top-down and bottom-up. A top-down approach reduces a large piece of material to small pieces, by various means such as lithography, [5] [6] milling or thermal oxidation. A bottom-up approach synthesizes the nanowire by combining constituent adatoms. Most synthesis techniques use a ...
Schematic representation of the different stages and routes of the sol–gel technology. In this chemical procedure, a "sol" (a colloidal solution) is formed that then gradually evolves towards the formation of a gel-like diphasic system containing both a liquid phase and solid phase whose morphologies range from discrete particles to continuous polymer networks.
A nanostructure is a structure of intermediate size between microscopic and molecular structures.Nanostructural detail is microstructure at nanoscale.. In describing nanostructures, it is necessary to differentiate between the number of dimensions in the volume of an object which are on the nanoscale.
The top-down approach is breaking down of a system into small components, while bottom-up is assembling sub-systems into larger system. [15] A bottom-up approach for nano-assembly is a primary research target for nano-fabrication because top down synthesis is expensive (requiring external work) and is not selective on very small length scales, but is currently the primary mode of industrial ...
Nanomaterials research takes a materials science-based approach to nanotechnology, leveraging advances in materials metrology and synthesis which have been developed in support of microfabrication research. Materials with structure at the nanoscale often have unique optical, electronic, thermo-physical or mechanical properties.
Several synthesis methods are known for SiNWs and these can be broadly divided into methods which start with bulk silicon and remove material to yield nanowires, also known as top-down synthesis, and methods which use a chemical or vapor precursor to build nanowires in a process generally considered to be bottom-up synthesis.
Their specific surface exceeds 1,000 m 2 /g (capped) or 2,200 m 2 /g (uncapped), [30] surpassing the value of 400–1,000 m 2 /g for HiPco samples. The synthesis efficiency is about 100 times higher than for the laser ablation method. The time required to make SWNT forests of the height of 2.5 mm by this method was 10 minutes in 2004.
Molecular self-assembly is a key concept in supramolecular chemistry. [6] [7] [8] This is because assembly of molecules in such systems is directed through non-covalent interactions (e.g., hydrogen bonding, metal coordination, hydrophobic forces, van der Waals forces, pi-stacking interactions, and/or electrostatic) as well as electromagnetic interactions.