The dc electrical conductivity, σdc, of the composite system Ag4RbI5–(β-AgI), which was composed of a good ionic conductor and a bad one, was measured by the ac impedance method. The obtained σdc increased with the volume fraction, V, of the good conductor, Ag4RbI5. This V-dependence of σdc was analyzed based on the generalized effective medium theory. The scaling law analysis was also applied. The obtained threshold value of the volume fraction, Vc, was 0.162. The critical exponents, t and s, were determined to be 2.0 and 0.88, respectively. These values were in almost complete agreement with the universal values of Vc,t and s predicted by the computer simulation for the electrical conduction. So far as the present authors know, this study was the first to provide the full set of universal characteristic values of percolation, Vc,t and s, for the electrical conduction from a single experimental study for the artificial composite material.

The Determination of the Full Set of Characteristic Values of Percolation, Percolation Threshold and Critical Exponents for the Artificial Composite with Ionic Conduction

Ag4RbI5–(β-AgI). K.Nozaki, T.Itami: Journal of Physics - Condensed Matter, 2006, 18, 2191-8