Caging density threshold

Above the critical threshold concentration of 4 1 wt.%, the CdS clusters must populate adjacent sodalite units for statistical reasons. For a three-dimensional percolation process, the percolation threshold is predicted to be around 15 vol.% [323]. If only the free volume of the sodalite cages is taken into account, 4 wt.% CdS corresponds to 14 vol.%, in excellent agreement with the percolation theory. Two cubes point to each other through the Cd atoms at the vertices, the Cd-Cd distance being =0.6 nm (Fig. 14). Since this is too long a distance for a direct interaction, and since the electron density inside the double six-ring windows was found to be very low by X-ray diffraction, a through-bond interac-... 

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