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Nanomaterials Study Guide

The document discusses nanomaterials and how their properties change at the nanoscale level. It defines various nanoscale terms like nanomaterials, nanocrystalline, nanotechnology, clusters, and quantum dots. It then explains that as particle size decreases, properties like mechanical, thermal and electronic properties change due to an increase in the percentage of grain boundaries. Examples are given for 1D, 2D and 3D nanomaterials. The mechanism of size-dependent color changes in nanoparticle clusters is also explained, with gold nanoparticles changing color based on their diameter.

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Wasan Shakir
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57 views3 pages

Nanomaterials Study Guide

The document discusses nanomaterials and how their properties change at the nanoscale level. It defines various nanoscale terms like nanomaterials, nanocrystalline, nanotechnology, clusters, and quantum dots. It then explains that as particle size decreases, properties like mechanical, thermal and electronic properties change due to an increase in the percentage of grain boundaries. Examples are given for 1D, 2D and 3D nanomaterials. The mechanism of size-dependent color changes in nanoparticle clusters is also explained, with gold nanoparticles changing color based on their diameter.

Uploaded by

Wasan Shakir
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
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Download as DOCX, PDF, TXT or read online on Scribd
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‫وسن شاكر محمود‬

‫رابع – ميكا – صباحي‬


HOME WORK
1. Define, Nanomaterials. Nanocrystalline, Nanotechnology,
cluster, quantum dot.

Nanomaterials: refer to the class of materials with at least one of


the dimensions in the nanometric range.

Nanocrystalline: materials have a grain size of


the order of 1−100 nm and smaller 1000 time than microsize
particles.

Nanotechnology: The creation of functional materials,devices and


systems through control of matter on the nanometer length scale
(1–100 nm), and exploitation of novel phenomena and properties
(physical, chemical,biological) at that length scale.

Cluster: When atoms come together in a material, they initially


form two-dimensional

quantum dot: are clusters of atoms of a semiconductor material.


The electrons in quantum dots have a range of energies.

2. Explain the reasons for change in the mechanical and thermal


properties of a nanoparticle with respect to its bulk size.

A large number of atoms reside at the grain boundaries, as


the grain size decreases, there is a significant increase in the
volume fraction of grain boundaries. The properties of the material
are bound to be governed to a large extent by defect
configurations, dynamics and interactions.
3. Write a brief note on a nanophenomena in your study
(materials or electronic properties).

a- Most electronic and optical properties vary when the grain size
is reduced typically below 10 nm.
b- However, their mechanical, chemical and many physical
properties begin to vary significantly from bulk below 50–100
nm.
c- Hence, nanomaterials classified as those materials which have
at least one of their dimensions in the nanometric range, there is
significant variation in the property of interest compared to
microcrystalline materials.
d- Nanomaterials can be metals, ceramics, polymers or
composites.

4. Give examples for 1D, 2D and 3D nanomaterials and describe


their unique properties.

1. The one-dimensional (1D) nanostructures: with the length much


larger than the width or diameter: Nanowires or nanotubes.
2. Two-dimensional nanostructure (2D) nanostructures: in which
the magnitudes of length and width are much greater than the
thickness that is nanoscale, such as thin films for electronic device
applications.
3. The bulk nanostructured material (3D) is a three-dimensional
and bulk material with nanoscale structures in all its three
dimensions. These materials are used in all structural applications.
5. Explain the mechanism of size dependence of colours in
nanopartics clusters.

Reflected light of gold nanoparticles varies in colour, depending


upon their
dimensions. Particles that are about 50 nm in diameter appear blue
or purple, at 25 nm
they are red, and at 1 nm they are orange. The melting point of
gold also drops by
almost 50% when the grain size is reduced below 10 nm. Similar
changes have been
observed in different nanomaterials with regard to a variety of
other properties like
magnetism and conductivity.

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