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.
Types of Defects Defects may be classified into four categories depending on their dimension: Â¾0D, Point defects: atoms missing or in irregular places in the lattice (vacancies, interstitials, impurities) Â¾1D, Linear defects: groups of atoms in irregular positions (e.g. screw and edge dislocations) Â¾2D, Planar defects: the interfaces between homogeneous regions of the material (grain boundaries, external surfaces) Â¾3D, Volume defects: extended defects (pores, cracks) Introduction To Materials Science, Chapter 4, Imperfections in solids University of Tennessee, Dept. of Materials Science and Engineering 6 Point defects: vacancies & self-interstitials Self-interstitials Vacancy Vacancy - a lattice position that is vacant because the atom is missing. Interstitial - an atom that occupies a place outside the normal lattice position. It may be the same type of atom as the others (self interstitial) or an impurity interstitial atom.