AC IMPEDANCE MEASUREMENT IN RANDOM METAL-INSULATOR COMPOSITES.

Composite materials generally have properties very different from those of their constituents. For example, it is well known that as the metal volume fraction in a metal-insulator composite increases the electrical conductivity increases. Near some critical metal volume fraction the conductivity of such a composite increases by as much as 6 to 10 orders of magnitude. This critical point is known as the percolation threshold. A series of different metal-insulator composite materials including Ag-KCl and Ag-Teflon specimens have been prepared by mixing predetermined amounts of Ag particles and either KCl or teflon powder. The results will be discussed in terms of two complementary models.