Physics 440 Condensed Matter Physics a.k.a. Materials Physics Solid-State Physics - PowerPoint PPT Presentation

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Physics 440 Condensed Matter Physics a.k.a. Materials Physics Solid-State Physics

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Physics 440 Condensed Matter Physics a.k.a. Materials Physics Solid-State Physics I. Introduction A. Domain of Study In this course we will focus mainly on perfect ... – PowerPoint PPT presentation

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Title: Physics 440 Condensed Matter Physics a.k.a. Materials Physics Solid-State Physics


1
Physics 440Condensed Matter Physicsa.k.a.Mate
rials PhysicsSolid-State Physics
2
I. Introduction
  1. The Domain of Study
  2. Materials We Will Study
  3. Phenomena and Properties of Interest
  4. Types of Interactions that Bind CM
  5. Potential Energy Functions Diagrams

3
A. Domain of Study
Any physical system in which the particle
separation is small enough so particles have
significant interactions can be regarded as
condensed.
crystalline solids (the basic paradigm for
CM) amorphous solids liquids soft matter
(foams, gels, biological systems) atomic
clusters/nanoparticles (lt 1000 atoms) white
dwarf neutron stars nuclear matter
domain of astrophysics and nuclear physics
4
In this course we will focus mainly on perfect
crystalline solids because their periodic
structure allows for simple mathematical models
to predict their properties
5
B. Materials We Will Study
Elemental solids in the periodic table are
arranged in families or groups, including
alkali metals (Li, Na, K, Rb, Cs) alkaline earth
metals (Be, Mg, Ca, Sr, Ba) transition metals
(Fe, Ni, Co, ) coinage metals (Cu, Ag,
Au) semiconductors (Si, Ge, Sn) noble gas solids
(He, Ne, Ar, Kr, Xe, Rn)
We will study mainly the metals and
semiconductors, which make up the majority of the
periodic table
6
C. Phenomena and Properties of Interest
structural mechanical thermal
electrical magnetic optical superconducting
We will concentrate on these
7
Experimental Techniques
Most CMP experiments use a probe (electrons,
photons, neutrons) and measure the scattering or
absorption of such particles or the response of
the sample in order to deduce properties of the
sample and details of the interactions inside
Ex. Photoemission experiment
ejected electron
photons
sample
8
D. Types of Interactions that Bind CM
1. van der Waals (noble gas liquids and solids)
Neutral atoms with closed electronic shells have
no time-average dipole moment but have
fluctuating dipole moments that can be
correlated with the fluctuating dipoles of nearby
atoms to produce a weak attraction
-

snapshot at one instant in time
-

9
2. Hydrogen bonding (molecular liquids and
solidsH2O)
Molecules with permanent dipole moments align in
such a way that causes a fairly weak ionic
attraction
H
these are small fractional charges due to unequal
sharing of electrons
O-
H
H
O-
H
10
3. Ionic bonding (atoms with very different
electronegativities)
e -
Na
Cl-
Na
Cl
Transfer of electron allows each ion to attain a
stable closed electronic shell. The molecule or
compound formed has a strong Coulomb attraction.
11
4. Covalent bonding (atoms with very similar
electronegativities semiconductors, diamond)
Tetrahedral coordination of atoms (sp3 bonding)
Valence electrons are shared between atoms, so
the negative electron clouds localized along the
interatomic axes attract the ion cores. These
produce strong, directional bonds.
12
5. Metallic bonding (most metals)
One or more valence electrons leaves its parent
atoms and is free to move throughout the solid.
The negative electrons in the free electron
gas attract the ion cores and keep them
together. Bonding here is non-directional.
free electron gas
positive ion cores
13
E. Potential Energy Functions and Diagrams
All of these interactions have potential energy
curves that look something like this, where U 0
means there is no interaction
U
short-range repulsion (Pauli exclusion)
R0
0
Long-range attraction (Coulomb or van der Waals)
14
Approximate Potential Energy Functions
vdW systems Lennard-Jones potential
ionic systems Born-Mayer potential
These and other approximate potential energy
functions are chosen in order to best fit
experimental measurements.
15
Remember
Problems worthy of attack Prove their worth
by hitting back --Piet Hein
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