Electrum is a metal alloy mainly consisting of gold, silver and traces of some other metals. This naturally occurring alloy has a long history of being used for making coins, vessels and also for coatings. It was referred to as âgoldâ or âwhite goldâ by ancient Greeks.
In Interstitial defect, atom occupies the interstitial space of the lattice structure of solid crystal. In Substitutional defect, the foreign atom occupies only the lattice site of a crystalline solid. Interstitial defect may occur by the atoms of either same solid (called self-interstitial) or foreign material. Substitutional defect is always caused by foreign atoms.
Interstitial impurity atoms fit into the open space between the bulk atoms of the lattice structure. An example of interstitial impurity atoms is the carbon atoms that are added to iron to make steel. Carbon atoms, with a radius of 0.071 nm, fit nicely in the open spaces between the larger (0.124 nm) iron atoms.