Low Temperature Electrical Behaviour of Nanocrystalline Silver and Copper Grown in a Glass-Ceramic

The resistivity of metallic particles of silver and copper respectively having diameters in the range 4.2 to 11.4 nm and grown within a glass-ceramic has been measured over the temperature range 5 to 300 K. The resistivity vs. temperature curve shows a dip at a temperature in the range 40 to 60 k the exact temperature depending on the metal particle diameter. The resistivity data have been fitted to Ziman equation and the effective Debye temperature θ_D as estimated shows a minimum value corresponding to a metal particle diameter around 6 nm for both the metallic species. This is explained as arising due to the occurrence of at least two fractal dimensions in the structure of the percolative chains of the metal particles.