پاورپوینت نانو متر چیست (pptx) 29 اسلاید
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تعداد اسلاید: 29 اسلاید
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What is nanotechnology?
A Nanometer
There are 1 billion (1,000,000,000) nanometers in 1 meter
There are 1 million (1,000,000) micrometers (or microns) in 1 meter
A line of ten hydrogen atoms lined up side by side is 1 nanometer long
Your finger nail grows 1 nanometer in 1 second
The diameter of your hair is approximately 50,000 nanometers
The abbreviation for nanometer is “nm”
Nanostructures/Nanomaterials
Nanostructures are materials that, in at least one dimension, measure approximately 1 – 100 nm
Nanostructures or nanomaterials exhibit properties different from their macroscale counterparts (their “big brothers”) such as:
Mechanical strength (how hard they are to break)
Electrical conductivity (how fast electrons flow through them)
Thermal conductivity (how fast heat flows through them)
Chemical reactivity (how well/fast they react with other chemicals)
Transparency (how well you can see through them)
Magnetism (whether or not they are magnetic)
… and many more…
Microstructures, the cousin to nanostructures, typically measure between 100 nanometers and 100 micrometers in at least one dimension, but likely do not exhibit unique properties like nanostructures do
Types Of Nanostructures/Nanomaterials
Nanoparticles or nanospheres: nanoscale lengths are measured in all three dimensions
Nanotubes or nanowires or nanorods: nanoscale lengths are measured in two dimensions only
Nanoscale thin films or ultra-thin films: nanoscale lengths are measured in one dimension only
Nanocomposites: a material comprised of many nanoscale inclusions (such as nanoparticles)
Nanostructured materials: a material that exhibits a unique structure that can be measured at the nanoscale
Common Examples of Nanostructures/Nanomaterials
Quantum dots: nanoparticles 2–10 nm in diameter, made from semiconductors, emit light in a specific wavelength range
Carbon nanotubes: hollow cylinders one to tens of nanometers in diameter, extremely strong (hard to break), conduct heat faster than any other known material
Buckyballs: nanoparticles comprised of exactly 60 carbon atoms (though there are other types), forming a network that resembles a soccer ball
Why does this happen?
Nanostructures obey the same fundamental laws of the universe as everything else in nature
But… some things that are negligible (can be ignored) at big scales cannot be ignored at small scales
For example:
Imagine you are an electron moving through a “big” copper wire 1 cm in diameter – you may never see the boundaries of the wire because you are so small compared to its diameter
Imagine you are an electron moving through a “small” copper wire 1 nm in diameter (more comparable to the electron’s size) – now you bump into the boundaries of the wire often, which affects how you move through that wire
Therefore, the 1 nm diameter copper wire exhibits different electrical properties than its macroscale counterpart!
So What is Nanotechnology?
Nanotechnology is:
Comprised of nanomaterials with at least one dimension that measures between approximately 1 and 100 nm
Comprised of nanomaterials that exhibit unique properties as a result of their nanoscale size
Based on new nanoscale discoveries across the various disciplines of science and engineering
The manipulation of these nanomaterials to develop new technologies/applications or to improve on existing ones
Used in a wide range of applications from electronics to medicine to energy and more
Some Current Applications of Nanotechnology
Solar Cells
Nanotechnology enhancements provide:
Improved efficiencies: novel nanomaterials can harness more of the sun’s energy
Lower costs: some novel nanomaterials can be made cheaper than alternatives
Flexibility: thin film flexible polymers can be manipulated to generate electricity from the sun’s energy