Enhancement mechanisms for the far-infrared absorption of metal-smoke-insulator composites based on the clustering of metal smoke

The strong far-infrared absorption observed by many workers in metal-smoke-insulator composites has been re-investigated thoroughly using well characterised samples of Ag-smoke-Teflon composites. The absorption coefficient of well separated Ag smoke can be explained quantitatively by the Maxwell-Garnett theory modified to include the size distribution of the Ag particles and the oxide coating effects. Particle clustering is shown to have an enormous impact on the far-infrared absorption of these composites. Comparisons between the authors experimental data and certain clustering modes are made. These comparisons show that most of the experimental results are consistent with the predictions of the cluster percolation model.