Introduction to Computational Physics - Class Project
DIELECTRIC PROPERTIES OF
Tamar Tepper - Materials Engineering, Technion.
Composite materials are artificial mixtures, which contain two phases:
filler and matrix, where the filler is included in the matrix in order
to improve its properties.
In this research we focus on improving the dielectric properties of an
insulating matrix by adding conducting particles to it.
When dealing with a mixture of conducting and non-conducting phases,
such in our case, percolation theory expects a dielectric enhancement
for compositions near the percolation threshold. The dielectric constant
of such compositions is supposed to obey a power law as a function of
composition. At the actual percolation threshold another power law behavior
is expected, as a function of frequency.
This percolative behavior was described for random percolation cases, where
all particles have the same size, and each site of space is occupied
independently of the others. In our case, conducting particles are 100
times and more bigger than the insulating ones. This problem is called
"correlated percolation" and has to be treated individually.
Since we are dealing with nanometer-sized particles here, some size effects
might be involved as well.
This program is meant to help us check whether power laws are valid in this
particular case as well. To do so, we measured electric capacitance of
different mixtures as a function of frequency. This program enables us to
draw the results as a function of composition and frequency and to look
graphically for any divergences of the dielectric constant.
The matlab programs and this text description can be obtained by
http from the Computational Physics http server.
If anyone would like more information I could contact
Tamar Tepper who is now at Rafael.
Online material is avaliable for the Fall 1997