Unit 1, Part 1: Introduction to Nanotechnology (Read Chapter 2 in Di Ventra) Dr. Brian Grady-Lecturer bpgrady@ou.edu - PowerPoint PPT Presentation

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Unit 1, Part 1: Introduction to Nanotechnology (Read Chapter 2 in Di Ventra) Dr. Brian Grady-Lecturer bpgrady@ou.edu

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Title: Unit 1, Part 1: Introduction to Nanotechnology (Read Chapter 2 in Di Ventra) Dr. Brian Grady-Lecturer bpgrady@ou.edu


1
Unit 1, Part 1 Introduction to Nanotechnology
(Read Chapter 2 in Di Ventra)Dr. Brian
Grady-Lecturerbpgrady_at_ou.edu
2
Four Units
  • Synthesis Dr. Warren Ford wtford_at_okstate.edu
  • Characterization Dr. Brian Grady bpgrady_at_ou.edu
  • Applications/Microscopy Dr. Alan Cheville
  • Presentation of Review Papers
  • Mechanics Issues (On-line quizzes, laboratory
    issues etc.) Chris Young nanotechta_at_gmail.com

3
Format of Class
  • On-line lectures, assigned reading
  • On-line quizzes Purpose is to be sure you have
    read and comprehended material
  • Multiple attempts if necessary not graded except
    pass-fail

4
Format of the Class-Continued
  • Three laboratories
  • Read material in advance
  • On-line video showing you how to do the
    experiments
  • On-line quiz to be completed PRIOR to laboratory
    or you will not be allowed in the laboratory
  • Complete laboratory- on site on Saturday
  • Logistical transportation issues will be dealt
    with later
  • Lab report Important part of your grade
  • In order to be allowed to do the lab and get
    anything but a failing grade for that lab you
    must successfully complete ALL of the on-line
    quizzes for that unit (unless indicated as not
    necessary by an instructor) PRIOR to being
    allowed to enter the laboratory

5
Format of the Class (cont.)
  • Comprehensive review paper
  • Topics must be approved by Dr. Grady no later
    than November 1st.
  • Papers due December 7th
  • You will also prepare and give a 15-20 minute
    presentation at a mini-conference that will be
    held on Dec 1st. Location of miniconference will
    be at TU

6
Format of the Class (continued)
  • Read the Syllabus

7
What is nanotechnology
  • Nanomaterials are materials where at least one
    dimension is very small (i.e. on the order of
    nanometers)
  • 1 nanometer10 Angstroms.001 microns10-9 meters
  • Almost always talking about solids (not liquids
    or gases)
  • Nanotechnology is the study of the
    synthesis/manufacture of those materials, the
    characterization of those materials and the
    application of those materials

8
Why Nanotechnology
  • Materials having very small sizes have unique
    properties
  • See Figure 1.19 in the text
  • The size of the particles controls the colors
    that are emitted when the particles are exposed
    to UV light
  • Only certain chemical compositions will have this
    property (i.e. this behavior is not generic to
    all nanoparticles)
  • Materials with small sizes can be packed into
    small areas and can do lots of stuff
  • Integrated circuits Millions of electrical
    components (resistors, transistors) per square
    inch
  • Materials with small sizes can be packed in a
    regular arrangement and do interesting things
  • See Figure 1.21 on inverse opals (unique colors
    due to a regular arrangement of spheres)
  • By and large, the chemical identity of the
    spheres is irrelevant to the effect this is
    strictly a size effect.

9
Inverse Opals
  • If spheres in regular pattern as shown to the
    right, and the spheres are the size of the
    wavelength of light (400-700 nm) get unique
    colors and can change color by changing sphere
    size

10
Why is nanotechnology unique?
  • Certain phenomena occur only when characteristic
    dimensions reach the nanometer scale
  • Quantum tunnelling effects If you put a voltage
    across an insulator, then the current is given by
    VIR. If the insulator becomes small less than
    100 nm the current is much higher (orders of
    magnitude!) than that predicted by the formula
    due to tunnelling
  • Surface effects are very important (surface to
    volume ratio is extremely large)
  • One sense how atoms are arranged at the surface
    have a very large influence on all properties,
    not just surface properties
  • 2nd sense Certain phenomena that are surface
    phenomena become dominant phenomena at nanoscale.
    For example, in flow through a pipe (think of
    water flowing through your garden hose!) the
    fluid right near the wall acts very differently
    than the rest of the fluid. This fact has a
    negligible effect though on the behavior of the
    water coming out of the hose end. If the garden
    hose becomes of nanoscale dimensions, all of the
    fluid is near the wall and all of the laws that
    tell you (for example) how much fluid comes out
    of your garden hose as a function of the pressure
    of the water do not apply.

11
Why study nanotechnology?
  • Today there is a large amount of research, but,
    outside of integrated circuits, not a large
    number of commercial applications of
    nanotechnology
  • Still primarily in the realm of start-up
    companies, and in the research departments of
    large companies

12
Is nanotechnology the wave of the future?
  • Certain politicians think so (i.e. money!)
  • I think most people would agree that the term
    microelectronics will (or at least should!)
    eventually be replaced by the term
    nanoelectronics
  • Already niche applications in other areas
  • Take advantage of small size leading to some
    unique characteristic or the fact that the
    material changes behavior entirely because the
    surface to volume ratio is so high
  • The other logical area that one would think where
    nanotechnology will be huge is medicine
  • Blood vessels etc. are pretty small, and to be
    able to navigate those vessels without disrupting
    function, which nanosize things should be able to
    do, should prove very useful.

13
Two Important Introductory Concepts
  • Bulk vs. Surface Properties
  • Arrangement of Atoms

14
Bulk vs. Surface
  • Think of Scotch Tape
  • Surface Property Adhesion. Scotch tape sticks
    to things
  • Bulk Property Strength. How much force does it
    take to pull scotch tape apart
  • Surface properties are determined by atoms within
    a few angstroms of the surface
  • In nanotechnology surface properties are much
    more important relatively than bulk properties
    than with other materials because surface/volume
    ratio is so high

15
Examples
  • Examples of Surface Properties
  • Surface energy (adhesion ability), charge on a
    particle (i.e. can it be made to have static
    electricity), catalytic ability (ability to cause
    reactions), ability to nucleate (think of putting
    boiling chips in heated water).
  • Examples of Bulk Properties
  • Mechanical strength, stiffness and flexibility,
    electrical conductivity, density etc.

16
Arrangement of Atoms
  • Consider a solid
  • Three possibilities atoms are arranged in a
    regular pattern, atoms are not arranged in a
    regular pattern, some atoms are arranged in a
    regular pattern and some are not
  • If atoms are all arranged in a regular pattern
    crystalline
  • If atoms are not arranged in a regular pattern
    amorphous
  • If some atoms are arranged in a regular pattern
    and some are not semi-crystalline

17
What do I mean by regular pattern
  • Think of a single type of atom material, e.g.
    gold
  • Gold atoms are arranged in cubes (atoms at
    corners and at 6 faces).

Ball and Stick Model
Space Filling Model
This particular structure is called
face-centered cubic
18
  • Stack Cubes in all three directions to make up
    repeating structure. This is how atoms lie in
    regular patterns

(Dont show in and out of page because drawing
becomes too confusing)
19
Crystalline
  • All crystalline materials are made up of regular
    cubic-like structures (cubes, rhombohedrans,
    cubes with lengths of sides not equal there are
    seven total) with atoms at the same positions
    within every cube. There are only 230 different
    atom/cube combinations.
  • Most of the time, each side of these cubic-like
    structures have dimensions between 0.5 nm and 2
    nm
  • Amorphous materials have no such cubes, i.e. if
    you draw cubes atoms arent in the same position
    within every cube.

20
Something to Consider
  • Suppose we make spherical gold nanoparticles that
    contains enough volume for 10000 unit cells
    (which is equivalent to a 5.5 nm diameter
    particle). Note that in this particle
    approximately 1/3 of the unit cells have one side
    touching the surface!
  • Since gold forms into cubes, one could easily see
    how a nanoparticle could be cubic but how
    spherical and still have cubic unit cell???
  • The answer is that it is not possible either the
    outside of the sphere has to look like this
    or the atoms
    have to change positions at the surface. If atoms
    change positions, how deep into the nanoparticle
    does this go?
  • It turns out that in some systems, you can make a
    material that is normally crystalline into an
    amorphous material, or even change the crystal
    structure entirely. Of course, the properties of
    the material change dramatically if this happens

21
Surface Composition
  • For a single atom material, the arrangement of
    atoms at the surface can be very different than
    the arrangement of atoms in the bulk
  • For materials with more than one atom, not only
    can the arrangement of atoms at the surface be
    different, but the composition can be different
  • For example, say we have the compound AB.
    Overall, we have equal amounts of A and B, but it
    is possible at the surface we have much more A
    than B. In non-nanomaterials, this surface
    enhancement of A does not affect the bulk
    properties, since the amount of material at the
    surface is miniscule. In nanomaterials, this
    surface enhancement not only affects the surface
    properties, but it also effects the bulk
    properties since there is much more B in the bulk
    than A, since the amount of material at the
    surface is NOT miniscule.

22
On to Synthesis
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