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Introduction to Computational Physics - Class Project

DIELECTRIC PROPERTIES OF NANOCOMPOSITE MATERIALS

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

Computational Physics Class


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